Forwarding and Control Element Separation (ForCES) Logical Function Block (LFB) Library
RFC 6956
| Document | Type | RFC - Proposed Standard (June 2013) Errata | |
|---|---|---|---|
| Authors | Weiming Wang , Evangelos Haleplidis , Kentaro Ogawa , Chuanhuang Li , Joel M. Halpern | ||
| Last updated | 2021-08-13 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Jamal Hadi Salim | ||
| Shepherd write-up | Show Last changed 2012-10-25 | ||
| IESG | IESG state | RFC 6956 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Adrian Farrel | ||
| Send notices to | (None) | ||
| IANA | IANA review state | IANA - Review Needed | |
| IANA action state | RFC-Ed-Ack |
RFC 6956
Internet Engineering Task Force (IETF) W. Wang
Request for Comments: 6956 Zhejiang Gongshang University
Category: Standards Track E. Haleplidis
ISSN: 2070-1721 University of Patras
K. Ogawa
NTT Corporation
C. Li
Hangzhou DPtech
J. Halpern
Ericsson
June 2013
Forwarding and Control Element Separation (ForCES)
Logical Function Block (LFB) Library
Abstract
This document defines basic classes of Logical Function Blocks (LFBs)
used in Forwarding and Control Element Separation (ForCES). The
basic LFB classes are defined according to the ForCES Forwarding
Element (FE) model and ForCES protocol specifications; they are
scoped to meet requirements of typical router functions and are
considered the basic LFB library for ForCES. The library includes
the descriptions of the LFBs and the XML definitions.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6956.
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Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................3
2. Terminology and Conventions .....................................4
2.1. Requirements Language ......................................4
2.2. Definitions ................................................4
3. Overview ........................................................6
3.1. Scope of the Library .......................................6
3.2. Overview of LFB Classes in the Library .....................8
3.2.1. LFB Design Choices ..................................8
3.2.2. LFB Class Groupings .................................9
3.2.3. Sample LFB Class Application .......................10
3.3. Document Structure ........................................11
4. Base Types .....................................................11
4.1. Data Types ................................................13
4.1.1. Atomic .............................................13
4.1.2. Compound Struct ....................................13
4.1.3. Compound Array .....................................14
4.2. Frame Types ...............................................14
4.3. Metadata Types ............................................15
4.4. XML for Base Type Library .................................16
5. LFB Class Descriptions .........................................41
5.1. Ethernet-Processing LFBs ..................................42
5.1.1. EtherPHYCop ........................................42
5.1.2. EtherMACIn .........................................44
5.1.3. EtherClassifier ....................................46
5.1.4. EtherEncap .........................................48
5.1.5. EtherMACOut ........................................50
5.2. IP Packet Validation LFBs .................................52
5.2.1. IPv4Validator ......................................52
5.2.2. IPv6Validator ......................................54
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5.3. IP Forwarding LFBs ........................................55
5.3.1. IPv4UcastLPM .......................................56
5.3.2. IPv4NextHop ........................................58
5.3.3. IPv6UcastLPM .......................................60
5.3.4. IPv6NextHop ........................................62
5.4. Redirect LFBs .............................................64
5.4.1. RedirectIn .........................................64
5.4.2. RedirectOut ........................................65
5.5. General Purpose LFBs ......................................66
5.5.1. BasicMetadataDispatch ..............................66
5.5.2. GenericScheduler ...................................68
6. XML for LFB Library ............................................69
7. LFB Class Use Cases ............................................97
7.1. IPv4 Forwarding ...........................................98
7.2. ARP Processing ...........................................101
8. IANA Considerations ...........................................102
8.1. LFB Class Names and LFB Class Identifiers ................103
8.2. Metadata ID ..............................................105
8.3. Exception ID .............................................106
8.4. Validate Error ID ........................................107
9. Security Considerations .......................................108
10. References ...................................................108
10.1. Normative References ....................................108
10.2. Informative References ..................................108
Appendix A. Acknowledgements ....................................110
Appendix B. Contributors ........................................110
1. Introduction
[RFC3746] specifies the Forwarding and Control Element Separation
(ForCES) framework. In the framework, Control Elements (CEs)
configure and manage one or more separate Forwarding Elements (FEs)
within a Network Element (NE) by use of a ForCES protocol. [RFC5810]
specifies the ForCES protocol. [RFC5812] specifies the Forwarding
Element (FE) model. In the model, resources in FEs are described by
classes of Logical Function Blocks (LFBs). The FE model defines the
structure and abstract semantics of LFBs and provides XML schema for
the definitions of LFBs.
This document conforms to the specifications of the FE model
[RFC5812] and specifies detailed definitions of classes of LFBs,
including detailed XML definitions of LFBs. These LFBs form a base
LFB library for ForCES. LFBs in the base library are expected to be
combined to form an LFB topology for a typical router to implement IP
forwarding. It should be emphasized that an LFB is an abstraction of
functions rather than implementation details. The purpose of the LFB
definitions is to represent functions so as to provide
interoperability between separate CEs and FEs.
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More LFB classes with more functions may be developed in the future
and documented by the IETF. Vendors may also develop proprietary LFB
classes as described in the FE model [RFC5812].
2. Terminology and Conventions
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.2. Definitions
This document follows the terminology defined by the ForCES protocol
in [RFC5810] and by the ForCES FE model in [RFC5812]. The
definitions below are repeated for clarity.
Control Element (CE) - A logical entity that implements the ForCES
protocol and uses it to instruct one or more FEs on how to process
packets. CEs handle functionality such as the execution of
control and signaling protocols.
Forwarding Element (FE) - A logical entity that implements the
ForCES protocol. FEs use the underlying hardware to provide per-
packet processing and handling as directed/controlled by one or
more CEs via the ForCES protocol.
ForCES Network Element (NE) - An entity composed of one or more
CEs and one or more FEs. To entities outside an NE, the NE
represents a single point of management. Similarly, an NE usually
hides its internal organization from external entities.
Logical Function Block (LFB) - The basic building block that is
operated on by the ForCES protocol. The LFB is a well-defined,
logically separable functional block that resides in an FE and is
controlled by the CE via the ForCES protocol. The LFB may reside
at the FE's data path and process packets or may be purely an FE
control or configuration entity that is operated on by the CE.
Note that the LFB is a functionally accurate abstraction of the
FE's processing capabilities but not a hardware-accurate
representation of the FE implementation.
FE Model - The FE model is designed to model the logical
processing functions of an FE, which is defined by the ForCES FE
model document [RFC5812]. The FE model proposed in this document
includes three components: the LFB modeling of individual Logical
Functional Blocks (LFB model), the logical interconnection between
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LFBs (LFB topology), and the FE-level attributes, including FE
capabilities. The FE model provides the basis to define the
information elements exchanged between the CE and the FE in the
ForCES protocol [RFC5810].
FE Topology - A representation of how the multiple FEs within a
single NE are interconnected. Sometimes this is called inter-FE
topology, to be distinguished from intra-FE topology (i.e., LFB
topology).
LFB Class and LFB Instance - LFBs are categorized by LFB classes.
An LFB instance represents an LFB class (or type) existence.
There may be multiple instances of the same LFB class (or type) in
an FE. An LFB class is represented by an LFB class ID, and an LFB
instance is represented by an LFB instance ID. As a result, an
LFB class ID associated with an LFB instance ID uniquely specifies
an LFB existence.
LFB Metadata - Metadata is used to communicate per-packet state
from one LFB to another but is not sent across the network. The
FE model defines how such metadata is identified, produced, and
consumed by the LFBs. It defines the functionality but not how
metadata is encoded within an implementation.
LFB Component - Operational parameters of the LFBs that must be
visible to the CEs are conceptualized in the FE model as the LFB
components. The LFB components include, for example, flags,
single parameter arguments, complex arguments, and tables that the
CE can read and/or write via the ForCES protocol (see below).
LFB Topology - Representation of how the LFB instances are
logically interconnected and placed along the data path within one
FE. Sometimes it is also called intra-FE topology, to be
distinguished from inter-FE topology.
Data Path - A conceptual path taken by packets within the
forwarding plane inside an FE. Note that more than one data path
can exist within an FE.
ForCES Protocol - While there may be multiple protocols used
within the overall ForCES architecture, the term "ForCES protocol"
and "protocol" refer to the Fp reference points in the ForCES
framework in [RFC3746]. This protocol does not apply to CE-to-CE
communication, FE-to-FE communication, or to communication between
FE and CE managers. Basically, the ForCES protocol works in a
master-slave mode in which FEs are slaves and CEs are masters.
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Physical Port - A port refers to a physical media input port or
output port of an FE. A physical port is usually assigned with a
physical port ID, abbreviated with a PHYPortID. This document
mainly deals with physical ports with Ethernet media.
Logical Port - A conceptually virtual port at the data link layer
(L2) or network layer (L3). A logical port is usually assigned
with a logical port ID, abbreviated with a LogicalPortID. The
logical ports can be further categorized with an L2 logical port
or an L3 logical port. An L2 logical port can be assigned with an
L2 logical port ID, abbreviated with an L2PortID. An L3 logical
port can be assigned with an L3 logical port ID, abbreviated with
an L3PortID. MAC-layer VLAN ports belong to logical ports, and
they belong to L2 logical ports.
LFB Port - The connection points where one LFB can be connected to
another within an FE. As described in [RFC5812], the CE can
connect LFBs together by establishing connections between an
output port of one LFB instance and an input port of another LFB
instance. Also see Section 3.2 of [RFC5812] for more details.
Singleton Port - A named input or output port of an LFB. This
port is referred to by a name. When the context is clear, the
term "singleton" by itself is used to refer to a singleton port.
Group Port - A named collection of input or output ports of an
LFB. A group port is referred to by a name. A group port
consists of a number of port instances, which are referred to by a
combination of a name and an index.
LFB Class Library - The LFB class library is a set of LFB classes
that has been identified as the most common functions found in
most FEs and hence should be defined first by the ForCES Working
Group. The LFB class library is defined by this document.
3. Overview
3.1. Scope of the Library
It is intended that the LFB classes described in this document are
designed to provide the functions of a typical router. [RFC1812]
specifies that a typical router is expected to provide functions to:
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(1) Interface to packet networks and implement the functions
required by that network. These functions typically include:
* Encapsulating and decapsulating the IP datagrams with the
connected network framing (e.g., an Ethernet header and
checksum),
* Sending and receiving IP datagrams up to the maximum size
supported by that network (this size is the network's Maximum
Transmission Unit or MTU),
* Translating the IP destination address into an appropriate
network-level address for the connected network (e.g., an
Ethernet hardware address), if needed, and
* Responding to network flow control and error indications, if
any.
(2) Conform to specific Internet protocols including the Internet
Protocol (IPv4 and/or IPv6), Internet Control Message Protocol
(ICMP), and others as necessary.
(3) Receive and forward Internet datagrams. Important issues in
this process are buffer management, congestion control, and
fairness.
* Recognize error conditions and generate ICMP error and
information messages as required.
* Drop datagrams whose time-to-live fields have reached zero.
* Fragment datagrams when necessary to fit into the MTU of the
next link or interface.
(4) Choose a next-hop destination for each IP datagram, based on the
information in its routing database.
(5) Usually support an interior gateway protocol (IGP) to carry out
distributed routing and reachability algorithms with the other
routers in the same autonomous system. In addition, some
routers will need to support an exterior gateway protocol (EGP)
to exchange topological information with other autonomous
systems. For all routers, it is essential to provide the
ability to manage static routing items.
(6) Provide network management and system support facilities,
including loading, debugging, status reporting, statistics
query, exception reporting, and control.
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The classical IP router utilizing the ForCES framework constitutes a
CE running some controlling IGP and/or EGP function or static route
setup and FEs implemented by use of Logical Function Blocks (LFBs)
conforming to the FE model [RFC5812] specification. The CE, in
conformance to the ForCES protocol [RFC5810] and the FE model
[RFC5812] specifications, instructs the LFBs on the FE how to treat
received/sent packets.
Packets in an IP router are received and transmitted on physical
media typically referred to as "ports". Different physical media
will have different ways for encapsulating outgoing frames and
decapsulating incoming frames. The different physical media will
also have different attributes that influence its behavior and how
frames get encapsulated or decapsulated. This document will only
deal with Ethernet physical media. Future documents may deal with
other types of media. This document will also interchangeably refer
to a port as an abstraction that constitutes a physical layer (PHY)
and a Media Access Control (MAC) layer, as described by LFBs like
EtherPHYCop, EtherMACIn, and EtherMACOut.
IP packets emanating from port LFBs are then processed by a
validation LFB before being further forwarded to the next LFB. After
the validation process, the packet is passed to an LFB where an IP
forwarding decision is made. In the IP Forwarding LFBs, a Longest
Prefix Match LFB is used to look up the destination information in a
packet and select a next-hop index for sending the packet onward. A
next-hop LFB uses the next-hop index metadata to apply the proper
headers to the IP packets and direct them to the proper egress. Note
that in the process of IP packet processing, in this document, we are
adhering to the weak-host model [RFC1122] since that is the most
usable model for a packet processing a Network Element.
3.2. Overview of LFB Classes in the Library
It is critical to classify functional requirements into various
classes of LFBs and construct a typical but also flexible enough base
LFB library for various IP forwarding equipments.
3.2.1. LFB Design Choices
A few design principles were factored into choosing what the base
LFBs look like:
o If a function can be designed by either one LFB or two or more
LFBs with the same cost, the choice is to go with two or more LFBs
so as to provide more flexibility for implementers.
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o An LFB should take advantage of its independence as much as
possible and have minimal coupling with other LFBs. The coupling
may be from LFB attributes definitions as well as physical
implementations.
o Unless there is a clear difference in functionality, similar
packet processing in the base LFB library should not be
represented simultaneously as two or more LFBs. For instance, it
should not be simultaneously defined with two different LFBs for
the same next-hop processing. Otherwise, it may add extra burden
on implementation to achieve interoperability.
3.2.2. LFB Class Groupings
This document defines groups of LFBs for typical router function
requirements:
(1) A group of Ethernet-processing LFBs are defined to abstract the
packet processing for Ethernet as the port media type. As
Ethernet is the most popular media type with rich processing
features, Ethernet media processing LFBs were a natural choice.
Definitions for processing of other port media types like Packet
over SONET (POS) or Asynchronous Transfer Mode (ATM) may be
incorporated in the library in future versions of this document
or in a separate document. The following LFBs are defined for
Ethernet processing:
* EtherPHYCop (Section 5.1.1)
* EtherMACIn (Section 5.1.2)
* EtherClassifier (Section 5.1.3)
* EtherEncap (Section 5.1.4)
* EtherMACOut (Section 5.1.5)
(2) A group of LFBs are defined for IP packet validation process.
The following LFBs are defined for IP validation processing:
* IPv4Validator (Section 5.2.1)
* IPv6Validator (Section 5.2.2)
(3) A group of LFBs are defined to abstract IP forwarding process.
The following LFBs are defined for IP forwarding processing:
* IPv4UcastLPM (Section 5.3.1)
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* IPv4NextHop (Section 5.3.2)
* IPv6UcastLPM (Section 5.3.3)
* IPv6NextHop (Section 5.3.4)
(4) A group of LFBs are defined to abstract the process for redirect
operation, i.e., data packet transmission between CE and FEs.
The following LFBs are defined for redirect processing:
* RedirectIn (Section 5.4.1)
* RedirectOut (Section 5.4.2)
(5) A group of LFBs are defined for abstracting some general purpose
packet processing. These processing processes are usually
general to many processing locations in an FE LFB topology. The
following LFBs are defined for redirect processing:
* BasicMetadataDispatch (Section 5.5.1)
* GenericScheduler (Section 5.5.2)
3.2.3. Sample LFB Class Application
Although Section 7 will present use cases for the LFBs defined in
this document, this section shows a simple sample LFB class
application in advance so that readers can get a quick overlook of
the LFB classes with the usage.
Figure 1 shows a simple LFB processing path for Ethernet packets
entered from Ethernet physical ports.
+-----+ +------+
| |EtherPHYIn | | from some LFB(s) that
| |<---------------|Ether |<---------- generate Ethernet
| | |MACOut| packets
| | | LFB |
|Ether| +------+
|PHY | +------+
|Cop | | |
|LFB |EtherPHYOut | Ether| to some LFB(s) that
| |--------------->| MACIn|----------> may classify Ethernet
| | | LFB | packets and do IP-layer
| | | | processing
+-----+ +------+
Figure 1: A Simple Sample LFB Use Case
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In the figure, Ethernet packets from outer networks enter via the
EtherPHYCop LFB (Section 5.1.1), which describes Ethernet copper
interface properties (like the link speed) at the physical layer.
After physical-layer processing, Ethernet packets are delivered to
the EtherMACIn LFB (Section 5.1.2) to describe its MAC-layer
processing functions (like locality check). The packets after the
EtherMACIn LFB may require further processing to implement various
functions (like IP-layer forwarding); therefore, some LFBs may follow
the EtherMACIn LFB in topology to describe followed processing
functions.
Meanwhile, packets generated by some LFB(s) may need to be submitted
to outer physical networks. The process is described in the figure
by an EtherMACOut LFB (Section 5.1.5) at the MAC layer and the
EtherPHYCop LFB at the physical layer.
3.3. Document Structure
Base type definitions, including data types, packet frame types, and
metadata types, are presented in advance for definitions of various
LFB classes. Section 4 ("Base Types") provides a description on the
base types used by this LFB library. To enable extensive use of
these base types by other LFB class definitions, the base type
definitions are provided as a separate library.
Within every group of LFB classes, a set of LFBs are defined for
individual function purposes. Section 5 ("LFB Class Descriptions")
provides text descriptions on the individual LFBs. Note that for a
complete definition of an LFB, a text description and an XML
definition are required.
LFB classes are finally defined by XML with specifications and schema
defined in the ForCES FE model [RFC5812]. Section 6 ("XML for LFB
Library") provides the complete XML definitions of the base LFB
classes library.
Section 7 provides several use cases on how some typical router
functions can be implemented using the base LFB library defined in
this document.
4. Base Types
The FE model [RFC5812] has specified predefined (built-in) atomic
data types: char, uchar, int16, uint16, int32, uint32, int64, uint64,
string[N], string, byte[N], boolean, octetstring[N], float16,
float32, and float64.
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Note that, unlike the Simple Network Management Protocol (SNMP)
information model, called the Structure of Management Information
(SMI) [RFC2578], the FE model has not defined specific atomic data
types for counting purposes. This document also does not define
specific counter types. To describe LFB elements for packet
statistics, which actually requires counters on packets, an unsigned
integer, like an uint32 or an uint64, is adopted. This document
states that any LFB element defined for counting purposes is
specified to monotonically increase until it reaches a maximum value,
when it wraps around and starts increasing again from zero. This
document also states that how the unsigned integer element might be
maintained to cope with issues like counter discontinuities when a
counter wraps or is reset for any reason is an implementation's
issue. If a CE is expected to understand more meanings of the
counter element than stated above, a private definition on the
element between the CE and FE may be required.
Based on the atomic data types and with the use of type definition
elements in the FE model XML schema, new data types, packet frame
types, and metadata types can be defined.
To define a base LFB library for typical router functions, a set of
base data types, frame types, and metadata types should be defined.
This section provides a brief description of the base types and a
full XML definition of them as well.
The base type XML definitions are provided with a separate XML
library file named "BaseTypeLibrary". Users can refer to this
library by the statement:
<load library="BaseTypeLibrary" location="..."/>
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4.1. Data Types
Data types defined in the base type library are categorized by the
following types: atomic, compound struct, and compound array.
4.1.1. Atomic
The following data types are defined as atomic data types and put in
the base type library:
Data Type Name Brief Description
-------------- -----------------
IPv4Addr IPv4 address
IPv6Addr IPv6 address
IEEEMAC IEEE MAC address
LANSpeedType LAN speed by value types
DuplexType Duplex types
PortStatusType The possible types of port status, used for
both administrative and operative status
VlanIDType The type of VLAN ID
VlanPriorityType The type of VLAN priority
SchdDisciplineType Scheduling discipline type
4.1.2. Compound Struct
The following compound struct types are defined in the base type
library:
Data Type Name Brief Description
-------------- -----------------
EtherDispatchEntryType Entry type for Ethernet dispatch table
VlanInputTableEntryType Entry type for VLAN input table
EncapTableEntryType Entry type for Ethernet encapsulation table
MACInStatsType Statistics type for EtherMACIn LFB
MACOutStatsType Statistics type for EtherMACOut LFB
EtherClassifyStatsType Entry type for statistics table in
EtherClassifier LFB
IPv4PrefixInfoType Entry type for IPv4 prefix table
IPv6PrefixInfoType Entry type for IPv6 prefix table
IPv4NextHopInfoType Entry type for IPv4 next-hop table
IPv6NextHopInfoType Entry type for IPv6 next-hop table
IPv4ValidatorStatsType Statistics type in IPv4validator LFB
IPv6ValidatorStatsType Statistics type in IPv6validator LFB
IPv4UcastLPMStatsType Statistics type in IPv4UcastLPM LFB
IPv6UcastLPMStatsType Statistics type in IPv6UcastLPM LFB
QueueStatsType Entry type for queue depth table
MetadataDispatchType Entry type for metadata dispatch table
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4.1.3. Compound Array
Compound array types are mostly created based on compound struct
types for LFB table components. The following compound array types
are defined in this base type library:
Data Type Name Brief Description
-------------- -----------------
EtherClassifyStatsTableType Type for Ethernet classifier statistics
information table
EtherDispatchTableType Type for Ethernet dispatch table
VlanInputTableType Type for VLAN input table
EncapTableType Type for Ethernet encapsulation table
IPv4PrefixTableType Type for IPv4 prefix table
IPv6PrefixTableType Type for IPv6 prefix table
IPv4NextHopTableType Type for IPv4 next-hop table
IPv6NextHopTableType Type for IPv6 next-hop table
MetadataDispatchTableType Type for Metadata dispatch table
QueueStatsTableType Type for Queue depth table
4.2. Frame Types
According to the FE model [RFC5812], frame types are used in LFB
definitions to define packet frame types that an LFB expects at its
input port and that the LFB emits at its output port. The <frameDef>
element in the FE model is used to define a new frame type.
The following frame types are defined in the base type library:
Frame Name Brief Description
-------------- -----------------
EthernetII An Ethernet II frame
ARP An ARP packet frame
IPv4 An IPv4 packet frame
IPv6 An IPv6 packet frame
IPv4Unicast An IPv4 unicast packet frame
IPv4Multicast An IPv4 multicast packet frame
IPv6Unicast An IPv6 unicast packet frame
IPv6Multicast An IPv6 multicast packet frame
Arbitrary Any type of packet frames
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4.3. Metadata Types
LFB metadata is used to communicate per-packet state from one LFB to
another. The <metadataDef> element in the FE model is used to define
a new metadata type.
The following metadata types are currently defined in the base type
library.
Metadata Name Metadata ID Brief Description
------------ ----------- -----------------
PHYPortID 1 Metadata indicating a physical port ID
SrcMAC 2 Metadata indicating a source MAC address
DstMAC 3 Metadata indicating a destination MAC
address
LogicalPortID 4 Metadata of a logical port ID
EtherType 5 Metadata indicating an Ethernet type
VlanID 6 Metadata of a VLAN ID
VlanPriority 7 Metadata of a VLAN priority
NextHopIPv4Addr 8 Metadata representing a next-hop IPv4
address
NextHopIPv6Addr 9 Metadata representing a next-hop IPv6
address
HopSelector 10 Metadata indicating a hop selector
ExceptionID 11 Metadata indicating exception types for
exceptional cases during LFB processing
ValidateErrorID 12 Metadata indicating error types when a
packet passes validation process
L3PortID 13 Metadata indicating ID of an L3 logical
port
RedirectIndex 14 Metadata that CE sends to RedirectIn LFB,
indicating an associated packet a group
output port index of the LFB
MediaEncapInfoIndex 15 A search key a packet uses to look up a
table in related LFBs to select an
encapsulation media
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4.4. XML for Base Type Library
<?xml version="1.0" encoding="UTF-8"?>
<LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
provides="BaseTypeLibrary">
<frameDefs>
<frameDef>
<name>EthernetAll</name>
<synopsis>Packet with any Ethernet type</synopsis>
</frameDef>
<frameDef>
<name>EthernetII</name>
<synopsis>Packet with Ethernet II type</synopsis>
</frameDef>
<frameDef>
<name>ARP</name>
<synopsis>ARP packet</synopsis>
</frameDef>
<frameDef>
<name>IPv4</name>
<synopsis>IPv4 packet</synopsis>
</frameDef>
<frameDef>
<name>IPv6</name>
<synopsis>IPv6 packet</synopsis>
</frameDef>
<frameDef>
<name>IPv4Unicast</name>
<synopsis>IPv4 unicast packet</synopsis>
</frameDef>
<frameDef>
<name>IPv4Multicast</name>
<synopsis>IPv4 multicast packet</synopsis>
</frameDef>
<frameDef>
<name>IPv6Unicast</name>
<synopsis>IPv6 unicast packet</synopsis>
</frameDef>
<frameDef>
<name>IPv6Multicast</name>
<synopsis>IPv6 multicast packet</synopsis>
</frameDef>
<frameDef>
<name>Arbitrary</name>
<synopsis>Any type of packet</synopsis>
</frameDef>
</frameDefs>
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<dataTypeDefs>
<dataTypeDef>
<name>IPv4Addr</name>
<synopsis>IPv4 address</synopsis>
<typeRef>byte[4]</typeRef>
</dataTypeDef>
<dataTypeDef>
<name>IPv6Addr</name>
<synopsis>IPv6 address</synopsis>
<typeRef>byte[16]</typeRef>
</dataTypeDef>
<dataTypeDef>
<name>IEEEMAC</name>
<synopsis>IEEE MAC address</synopsis>
<typeRef>byte[6]</typeRef>
</dataTypeDef>
<dataTypeDef>
<name>LANSpeedType</name>
<synopsis>LAN speed type</synopsis>
<atomic>
<baseType>uint32</baseType>
<specialValues>
<specialValue value="0x00000000">
<name>LAN_SPEED_NONE</name>
<synopsis>Nothing connected</synopsis>
</specialValue>
<specialValue value="0x00000001">
<name>LAN_SPEED_10M</name>
<synopsis>10M Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000002">
<name>LAN_SPEED_100M</name>
<synopsis>100M Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000003">
<name>LAN_SPEED_1G</name>
<synopsis>1G Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000004">
<name>LAN_SPEED_10G</name>
<synopsis>10G Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000005">
<name>LAN_SPEED_40G</name>
<synopsis>40G Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000006">
<name>LAN_SPEED_100G</name>
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<synopsis>100G Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000007">
<name>LAN_SPEED_400G</name>
<synopsis>400G Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000008">
<name>LAN_SPEED_1T</name>
<synopsis>1T Ethernet</synopsis>
</specialValue>
<specialValue value="0x00000009">
<name>LAN_SPEED_OTHER</name>
<synopsis>Other LAN speed type</synopsis>
</specialValue>
<specialValue value="0x0000000A">
<name>LAN_SPEED_AUTO</name>
<synopsis>LAN speed by auto negotiation</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>DuplexType</name>
<synopsis>Duplex mode type</synopsis>
<atomic>
<baseType>uint32</baseType>
<specialValues>
<specialValue value="0x00000001">
<name>Auto</name>
<synopsis>Auto negotiation</synopsis>
</specialValue>
<specialValue value="0x00000002">
<name>HalfDuplex</name>
<synopsis>Half duplex</synopsis>
</specialValue>
<specialValue value="0x00000003">
<name>FullDuplex</name>
<synopsis>Full duplex</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>PortStatusType</name>
<synopsis>
Type for port status, used for both administrative and
operative status.
</synopsis>
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<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>Disabled</name>
<synopsis>Port disabled</synopsis>
</specialValue>
<specialValue value="1">
<name>Up</name>
<synopsis>Port up</synopsis>
</specialValue>
<specialValue value="2">
<name>Down</name>
<synopsis>Port down</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>MACInStatsType</name>
<synopsis>
Data type defined for statistics in EtherMACIn LFB.
</synopsis>
<struct>
<component componentID="1">
<name>NumPacketsReceived</name>
<synopsis>Number of packets received</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="2">
<name>NumPacketsDropped</name>
<synopsis>Number of packets dropped</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>MACOutStatsType</name>
<synopsis>
Data type defined for statistics in EtherMACOut LFB.
</synopsis>
<struct>
<component componentID="1">
<name>NumPacketsTransmitted</name>
<synopsis>Number of packets transmitted</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="2">
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<name>NumPacketsDropped</name>
<synopsis>Number of packets dropped</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>EtherDispatchEntryType</name>
<synopsis>
Data type defined for entry of Ethernet dispatch
table in EtherClassifier LFB.
</synopsis>
<struct>
<component componentID="1">
<name>LogicalPortID</name>
<synopsis>Logical port ID</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2">
<name>EtherType</name>
<synopsis>
The Ethernet type of the Ethernet packet.
</synopsis>
<typeRef>uint16</typeRef>
</component>
<component componentID="3">
<name>Reserved</name>
<synopsis>
A reserved bit space mainly for purpose of padding
and packing efficiency.
</synopsis>
<typeRef>uint16</typeRef>
</component>
<component componentID="4">
<name>LFBOutputSelectIndex</name>
<synopsis>
Index for a packet to select an instance in the
group output port of EtherClassifier LFB to output.
</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
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<name>EtherDispatchTableType</name>
<synopsis>
Data type defined for Ethernet dispatch table in
EtherClassifier LFB. The table is composed of an array
of entries with EtherDispatchEntryType data type.
</synopsis>
<array type="variable-size">
<typeRef>EtherDispatchEntryType</typeRef>
</array>
</dataTypeDef>
<dataTypeDef>
<name>VlanIDType</name>
<synopsis>Data type for VLAN ID</synopsis>
<atomic>
<baseType>uint16</baseType>
<rangeRestriction>
<allowedRange min="0" max="4095"/>
</rangeRestriction>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>VlanPriorityType</name>
<synopsis>Data type for VLAN priority</synopsis>
<atomic>
<baseType>uchar</baseType>
<rangeRestriction>
<allowedRange min="0" max="7"/>
</rangeRestriction>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>VlanInputTableEntryType</name>
<synopsis>
Data type for entry of VLAN input table in EtherClassifier
LFB. Each entry of the table contains an incoming port ID,
a VLAN ID and a logical port ID. Every input packet is
assigned with a new logical port ID according to the
packet incoming port ID and the VLAN ID.
</synopsis>
<struct>
<component componentID="1">
<name>IncomingPortID</name>
<synopsis>The incoming port ID</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2">
<name>VlanID</name>
<synopsis>The VLAN ID</synopsis>
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<typeRef>VlanIDType</typeRef>
</component>
<component componentID="3">
<name>Reserved</name>
<synopsis>
A reserved bit space mainly for purpose of padding
and packing efficiency.
</synopsis>
<typeRef>uint16</typeRef>
</component>
<component componentID="4">
<name>LogicalPortID</name>
<synopsis>The logical port ID</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>VlanInputTableType</name>
<synopsis>
Data type for the VLAN input table in EtherClassifier
LFB. The table is composed of an array of entries with
VlanInputTableEntryType.
</synopsis>
<array type="variable-size">
<typeRef>VlanInputTableEntryType</typeRef>
</array>
</dataTypeDef>
<dataTypeDef>
<name>EtherClassifyStatsType</name>
<synopsis>
Data type for entry of statistics table in EtherClassifier
LFB.
</synopsis>
<struct>
<component componentID="1">
<name>EtherType</name>
<synopsis>
The Ethernet type of the Ethernet packet.
</synopsis>
<typeRef>uint16</typeRef>
</component>
<component componentID="2">
<name>Reserved</name>
<synopsis>
A reserved bit space mainly for purpose of padding
and packing efficiency.
</synopsis>
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<typeRef>uint16</typeRef>
</component>
<component componentID="3">
<name>PacketsNum</name>
<synopsis>Packets number</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>EtherClassifyStatsTableType</name>
<synopsis>
Data type for statistics table in EtherClassifier LFB.
</synopsis>
<array type="variable-size">
<typeRef>EtherClassifyStatsType</typeRef>
</array>
</dataTypeDef>
<dataTypeDef>
<name>IPv4ValidatorStatsType</name>
<synopsis>
Data type for statistics in IPv4validator LFB.
</synopsis>
<struct>
<component componentID="1">
<name>badHeaderPkts</name>
<synopsis>Number of packets with bad header</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="2">
<name>badTotalLengthPkts</name>
<synopsis>
Number of packets with bad total length
</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="3">
<name>badTTLPkts</name>
<synopsis>Number of packets with bad TTL</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="4">
<name>badChecksumPkts</name>
<synopsis>Number of packets with bad checksum</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
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<dataTypeDef>
<name>IPv6ValidatorStatsType</name>
<synopsis>
Data type for statistics in IPv6validator LFB.
</synopsis>
<struct>
<component componentID="1">
<name>badHeaderPkts</name>
<synopsis>Number of packets with bad header</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="2">
<name>badTotalLengthPkts</name>
<synopsis>
Number of packets with bad total length.
</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="3">
<name>badHopLimitPkts</name>
<synopsis>
Number of packets with bad hop limit.
</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>IPv4PrefixInfoType</name>
<synopsis>Data type for entry of IPv4 longest prefix match
table in IPv4UcastLPM LFB. The destination IPv4 address
of every input packet is used as a search key to look up
the table to find out a next-hop selector.</synopsis>
<struct>
<component componentID="1">
<name>IPv4Address</name>
<synopsis>The destination IPv4 address</synopsis>
<typeRef>IPv4Addr</typeRef>
</component>
<component componentID="2">
<name>Prefixlen</name>
<synopsis>The prefix length</synopsis>
<atomic>
<baseType>uchar</baseType>
<rangeRestriction>
<allowedRange min="0" max="32"/>
</rangeRestriction>
</atomic>
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</component>
<component componentID="3">
<name>ECMPFlag</name>
<synopsis>The ECMP flag</synopsis>
<atomic>
<baseType>boolean</baseType>
<specialValues>
<specialValue value="false">
<name>False</name>
<synopsis>
ECMP false, indicating the route
does not have multiple next hops.
</synopsis>
</specialValue>
<specialValue value="true">
<name>True</name>
<synopsis>
ECMP true, indicating the route
has multiple next hops.
</synopsis>
</specialValue>
</specialValues>
</atomic>
</component>
<component componentID="4">
<name>DefaultRouteFlag</name>
<synopsis>Default route flag</synopsis>
<atomic>
<baseType>boolean</baseType>
<specialValues>
<specialValue value="false">
<name>False</name>
<synopsis>
Default route false, indicating the
route is not a default route.
</synopsis>
</specialValue>
<specialValue value="true">
<name>True</name>
<synopsis>
Default route true, indicating the
route is a default route.
</synopsis>
</specialValue>
</specialValues>
</atomic>
</component>
<component componentID="5">
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<name>Reserved</name>
<synopsis>
A reserved bit space mainly for purpose of padding
and packing efficiency.
</synopsis>
<typeRef>uchar</typeRef>
</component>
<component componentID="6">
<name>HopSelector</name>
<synopsis>
The HopSelector produced by the prefix matching LFB,
which will be output to downstream LFB to find next-
hop information.
</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>IPv4PrefixTableType</name>
<synopsis>
Data type for IPv4 longest prefix match table in
IPv4UcastLPM LFB. Entry of the table is
of IPv4PrefixInfoType data type.
</synopsis>
<array type="variable-size">
<typeRef>IPv4PrefixInfoType</typeRef>
</array>
</dataTypeDef>
<dataTypeDef>
<name>IPv4UcastLPMStatsType</name>
<synopsis>
Data type for statistics in IPv4UcastLPM LFB.
</synopsis>
<struct>
<component componentID="1">
<name>InRcvdPkts</name>
<synopsis>Number of received input packets.</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="2">
<name>FwdPkts</name>
<synopsis>Number of forwarded packets.</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="3">
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<name>NoRoutePkts</name>
<synopsis>
Number of packets with no route found.
</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>IPv6PrefixInfoType</name>
<synopsis>Data type for entry of IPv6 longest prefix match
table in IPv6UcastLPM LFB. The destination IPv6 address
of every input packet is used as a search key to look up
the table to find out a next-hop selector.</synopsis>
<struct>
<component componentID="1">
<name>IPv6Address</name>
<synopsis>The destination IPv6 address</synopsis>
<typeRef>IPv6Addr</typeRef>
</component>
<component componentID="2">
<name>Prefixlen</name>
<synopsis>The prefix length</synopsis>
<atomic>
<baseType>uchar</baseType>
<rangeRestriction>
<allowedRange min="0" max="128"/>
</rangeRestriction>
</atomic>
</component>
<component componentID="3">
<name>ECMPFlag</name>
<synopsis>ECMP flag</synopsis>
<atomic>
<baseType>boolean</baseType>
<specialValues>
<specialValue value="false">
<name>False</name>
<synopsis>ECMP false</synopsis>
</specialValue>
<specialValue value="true">
<name>True</name>
<synopsis>ECMP true</synopsis>
</specialValue>
</specialValues>
</atomic>
</component>
<component componentID="4">
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<name>DefaultRouteFlag</name>
<synopsis>Default route flag</synopsis>
<atomic>
<baseType>boolean</baseType>
<specialValues>
<specialValue value="false">
<name>False</name>
<synopsis>Default false</synopsis>
</specialValue>
<specialValue value="true">
<name>True</name>
<synopsis>Default route true</synopsis>
</specialValue>
</specialValues>
</atomic>
</component>
<component componentID="5">
<name>Reserved</name>
<synopsis>
A reserved bit space mainly for purpose of padding
and packing efficiency.
</synopsis>
<typeRef>uchar</typeRef>
</component>
<component componentID="6">
<name>HopSelector</name>
<synopsis>
The HopSelector produced by the prefix matching LFB,
which will be output to downstream LFB to find next-
hop information.
</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>IPv6PrefixTableType</name>
<synopsis>
Data type for IPv6 longest prefix match table in
IPv6UcastLPM LFB. Entry of the table is
of IPv6PrefixInfoType data type.
</synopsis>
<array type="variable-size">
<typeRef>IPv6PrefixInfoType</typeRef>
</array>
</dataTypeDef>
<dataTypeDef>
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<name>IPv6UcastLPMStatsType</name>
<synopsis>Data type for statistics in IPv6UcastLPM LFB
</synopsis>
<struct>
<component componentID="1">
<name>InRcvdPkts</name>
<synopsis>Number of received input packets</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="2">
<name>FwdPkts</name>
<synopsis>Number of forwarded packets</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="3">
<name>NoRoutePkts</name>
<synopsis>
Number of packets with no route found.
</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>IPv4NextHopInfoType</name>
<synopsis>
Data type for entry of IPv4 next-hop information table
in IPv4NextHop LFB. The table uses a hop selector
received from upstream LFB as a search key to look up
index of the table to find the next-hop information.
</synopsis>
<struct>
<component componentID="1">
<name>L3PortID</name>
<synopsis>
The ID of the logical output port that is to pass
onto downstream LFB, indicating what port to the
neighbor is as defined by L3.
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2">
<name>MTU</name>
<synopsis>
Maximum Transmission Unit for outgoing port
</synopsis>
<typeRef>uint32</typeRef>
</component>
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<component componentID="3">
<name>NextHopIPAddr</name>
<synopsis>The next-hop IPv4 address</synopsis>
<typeRef>IPv4Addr</typeRef>
</component>
<component componentID="4">
<name>MediaEncapInfoIndex</name>
<synopsis>
The index passed onto a downstream encapsulation
LFB, used there as a search key to lookup further
encapsulation information.
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="5">
<name>LFBOutputSelectIndex</name>
<synopsis>
The index for the IPv4NextHop LFB to choose an
instance in the group output port of the LFB to
output.
</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>IPv4NextHopTableType</name>
<synopsis>
Data type for IPv4 next-hop table in IPv4NextHop LFB.
Entry of the table is of IPv4NextHopInfoType data type.
</synopsis>
<array type="variable-size">
<typeRef>IPv4NextHopInfoType</typeRef>
</array>
</dataTypeDef>
<dataTypeDef>
<name>IPv6NextHopInfoType</name>
<synopsis>
Data type for entry of IPv6 next-hop information table
in IPv6NextHop LFB. The table uses a hop selector
received from upstream LFB as a search key to look up
index of the table to find the next-hop information.
</synopsis>
<struct>
<component componentID="1">
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<name>L3PortID</name>
<synopsis>
The ID of the logical output port that is to pass
onto downstream LFB, indicating what port to the
neighbor is as defined by L3.
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2">
<name>MTU</name>
<synopsis>
Maximum Transmission Unit for outgoing port
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="3">
<name>NextHopIPAddr</name>
<synopsis>The next-hop IPv6 address</synopsis>
<typeRef>IPv6Addr</typeRef>
</component>
<component componentID="4">
<name>MediaEncapInfoIndex</name>
<synopsis>
The index passed onto a downstream encapsulation
LFB, used there as a search key to lookup further
encapsulation information.
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="5">
<name>LFBOutputSelectIndex</name>
<synopsis>
The index for the IPv6NextHop LFB to choose an instance
in the group output port of the LFB to output.
</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>IPv6NextHopTableType</name>
<synopsis>
Data type for IPv6 next-hop table in IPv6NextHop LFB.
Entry of the table is of IPv6NextHopInfoType data type.
</synopsis>
<array type="variable-size">
<typeRef>IPv6NextHopInfoType</typeRef>
</array>
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</dataTypeDef>
<dataTypeDef>
<name>EncapTableEntryType</name>
<synopsis>
Data type for entry of Ethernet encapsulation table in
EtherEncap LFB. The LFB uses the MediaEncapInfoIndex
received from upstream LFB as index of the table to
find encapsulation information of every packet.
</synopsis>
<struct>
<component componentID="1">
<name>DstMac</name>
<synopsis>
Destination MAC address for Ethernet encapsulation of
the packet.
</synopsis>
<typeRef>IEEEMAC</typeRef>
</component>
<component componentID="2">
<name>SrcMac</name>
<synopsis>
Source MAC address for Ethernet encapsulation of the
packet.
</synopsis>
<typeRef>IEEEMAC</typeRef>
</component>
<component componentID="3">
<name>VlanID</name>
<synopsis>The VLAN ID assigned to the packet</synopsis>
<typeRef>VlanIDType</typeRef>
</component>
<component componentID="4">
<name>Reserved</name>
<synopsis>
A reserved bit space mainly for purpose of padding
and packing efficiency.
</synopsis>
<typeRef>uint16</typeRef>
</component>
<component componentID="5">
<name>L2PortID</name>
<synopsis>
The L2 logical output port ID for the packet.
</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
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<dataTypeDef>
<name>EncapTableType</name>
<synopsis>
Data type for Ethernet encapsulation table in EtherEncap
LFB. Entry of the table is of EncapTableEntryType data
type.
</synopsis>
<array type="variable-size">
<typeRef>EncapTableEntryType</typeRef>
</array>
</dataTypeDef>
<dataTypeDef>
<name>MetadataDispatchType</name>
<synopsis>
Data type for entry of metadata dispatch table used in
BasicMetadataDispatch LFB. The LFB uses a metadata value
as a search key to look up the table to find an index of
the LFB group output port to output the packet.
</synopsis>
<struct>
<component componentID="1">
<name>MetadataValue</name>
<synopsis>The value of the dispatch metadata</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2">
<name>OutputIndex</name>
<synopsis>
Index of a group output port for outgoing packets.
</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>MetadataDispatchTableType</name>
<synopsis>
Data type for metadata dispatch table used in
BasicMetadataDispatch LFB. Metadata value of
the table is also defined as a content key field.
</synopsis>
<array type="variable-size">
<typeRef>MetadataDispatchType</typeRef>
<contentKey contentKeyID="1">
<contentKeyField>MetadataValue</contentKeyField>
</contentKey>
</array>
</dataTypeDef>
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<dataTypeDef>
<name>SchdDisciplineType</name>
<synopsis>Scheduling discipline type</synopsis>
<atomic>
<baseType>uint32</baseType>
<specialValues>
<specialValue value="1">
<name>RR</name>
<synopsis>
Round Robin scheduling discipline
</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>QueueStatsType</name>
<synopsis>
Data type for entry of queue statistics table in
GenericScheduler LFB.
</synopsis>
<struct>
<component componentID="1">
<name>QueueID</name>
<synopsis>The input queue ID</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2">
<name>QueueDepthInPackets</name>
<synopsis>Current queue depth in packets</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="3">
<name>QueueDepthInBytes</name>
<synopsis>Current queue depth in bytes</synopsis>
<typeRef>uint32</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>QueueStatsTableType</name>
<synopsis>
Data type for queue statistics table in GenericScheduler
LFB. Entry of the table is of QueueStatsType data type.
</synopsis>
<array type="variable-size">
<typeRef>QueueStatsType</typeRef>
</array>
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</dataTypeDef>
</dataTypeDefs>
<metadataDefs>
<metadataDef>
<name>PHYPortID</name>
<synopsis>Metadata indicating physical port ID</synopsis>
<metadataID>1</metadataID>
<typeRef>uint32</typeRef>
</metadataDef>
<metadataDef>
<name>SrcMAC</name>
<synopsis>Metadata indicating source MAC address</synopsis>
<metadataID>2</metadataID>
<typeRef>IEEEMAC</typeRef>
</metadataDef>
<metadataDef>
<name>DstMAC</name>
<synopsis>
Metadata indicating destination MAC address.
</synopsis>
<metadataID>3</metadataID>
<typeRef>IEEEMAC</typeRef>
</metadataDef>
<metadataDef>
<name>LogicalPortID</name>
<synopsis>Metadata of logical port ID</synopsis>
<metadataID>4</metadataID>
<typeRef>uint32</typeRef>
</metadataDef>
<metadataDef>
<name>EtherType</name>
<synopsis>Metadata indicating Ethernet type</synopsis>
<metadataID>5</metadataID>
<typeRef>uint16</typeRef>
</metadataDef>
<metadataDef>
<name>VlanID</name>
<synopsis>Metadata of VLAN ID</synopsis>
<metadataID>6</metadataID>
<typeRef>VlanIDType</typeRef>
</metadataDef>
<metadataDef>
<name>VlanPriority</name>
<synopsis>Metadata of VLAN priority</synopsis>
<metadataID>7</metadataID>
<typeRef>VlanPriorityType</typeRef>
</metadataDef>
<metadataDef>
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<name>NextHopIPv4Addr</name>
<synopsis>
Metadata representing a next-hop IPv4 address
</synopsis>
<metadataID>8</metadataID>
<typeRef>IPv4Addr</typeRef>
</metadataDef>
<metadataDef>
<name>NextHopIPv6Addr</name>
<synopsis>
Metadata representing a next-hop IPv6 address
</synopsis>
<metadataID>9</metadataID>
<typeRef>IPv6Addr</typeRef>
</metadataDef>
<metadataDef>
<name>HopSelector</name>
<synopsis>Metadata indicating a hop selector</synopsis>
<metadataID>10</metadataID>
<typeRef>uint32</typeRef>
</metadataDef>
<metadataDef>
<name>ExceptionID</name>
<synopsis>
Metadata indicating exception types for exceptional cases
during packet processing.
</synopsis>
<metadataID>11</metadataID>
<atomic>
<baseType>uint32</baseType>
<specialValues>
<specialValue value="0">
<name>AnyUnrecognizedExceptionCase</name>
<synopsis>Any unrecognized exception case</synopsis>
</specialValue>
<specialValue value="1">
<name>ClassifyNoMatching</name>
<synopsis>
Exception case: no matching of tables in
EtherClassifier LFB.
</synopsis>
</specialValue>
<specialValue value="2">
<name>MediaEncapInfoIndexInvalid</name>
<synopsis>
Exception case: the MediaEncapInfoIndex value of
the packet is invalid and cannot be allocated in
the EncapTable in EtherEncap LFB.
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</synopsis>
</specialValue>
<specialValue value="3">
<name>EncapTableLookupFailed</name>
<synopsis>
Exception case: the packet fails lookup of the
EncapTable table in EtherEncap LFB even though the
MediaEncapInfoIndex is valid.
</synopsis>
</specialValue>
<specialValue value="4">
<name>BadTTL</name>
<synopsis>
Exception case: packet with expired TTL
</synopsis>
</specialValue>
<specialValue value="5">
<name>IPv4HeaderLengthMismatch</name>
<synopsis>
Exception case: packet with header length more
than 5 words.
</synopsis>
</specialValue>
<specialValue value="6">
<name>RouterAlertOptions</name>
<synopsis>
Exception case: packet IP head includes router
alert options.
</synopsis>
</specialValue>
<specialValue value="7">
<name>IPv6HopLimitZero</name>
<synopsis>
Exception case: packet with the hop limit to zero.
</synopsis>
</specialValue>
<specialValue value="8">
<name>IPv6NextHeaderHBH</name>
<synopsis>
Exception case: packet with next header set to
Hop-by-Hop.
</synopsis>
</specialValue>
<specialValue value="9">
<name>SrcAddressException</name>
<synopsis>
Exception case: packet with exceptional source
address.
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</synopsis>
</specialValue>
<specialValue value="10">
<name>DstAddressException</name>
<synopsis>
Exception case: packet with exceptional destination
address.
</synopsis>
</specialValue>
<specialValue value="11">
<name>LPMLookupFailed</name>
<synopsis>
Exception case: packet failed the LPM table lookup
in a prefix match LFB.
</synopsis>
</specialValue>
<specialValue value="12">
<name>HopSelectorInvalid</name>
<synopsis>
Exception case: HopSelector for the packet is
invalid.
</synopsis>
</specialValue>
<specialValue value="13">
<name>NextHopLookupFailed</name>
<synopsis>
Exception case: packet failed lookup of a next-hop
table even though HopSelector is valid.
</synopsis>
</specialValue>
<specialValue value="14">
<name>FragRequired</name>
<synopsis>
Exception case: packet fragmentation is required
</synopsis>
</specialValue>
<specialValue value="15">
<name>MetadataNoMatching</name>
<synopsis>
Exception case: there is no matching when looking
up the metadata dispatch table in
BasicMetadataDispatch LFB.
</synopsis>
</specialValue>
</specialValues>
</atomic>
</metadataDef>
<metadataDef>
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<name>ValidateErrorID</name>
<synopsis>
Metadata indicating error types when a packet passes
validation process.
</synopsis>
<metadataID>12</metadataID>
<atomic>
<baseType>uint32</baseType>
<specialValues>
<specialValue value="0">
<name>AnyUnrecognizedValidateErrorCase</name>
<synopsis>
Any unrecognized validate error case.
</synopsis>
</specialValue>
<specialValue value="1">
<name>InvalidIPv4PacketSize</name>
<synopsis>
Error case: packet length reported by the link
layer is less than 20 bytes.
</synopsis>
</specialValue>
<specialValue value="2">
<name>NotIPv4Packet</name>
<synopsis>
Error case: packet is not IP version 4</synopsis>
</specialValue>
<specialValue value="3">
<name>InvalidIPv4HeaderLengthSize</name>
<synopsis>
Error case: packet with header length field in
the header less than 5 words.
</synopsis>
</specialValue>
<specialValue value="4">
<name>InvalidIPv4LengthFieldSize</name>
<synopsis>
Error case: packet with total length field in the
header less than 20 bytes.
</synopsis>
</specialValue>
<specialValue value="5">
<name>InvalidIPv4Checksum</name>
<synopsis>
Error case: packet with invalid checksum.
</synopsis>
</specialValue>
<specialValue value="6">
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<name>InvalidIPv4SrcAddr</name>
<synopsis>
Error case: packet with invalid IPv4 source
address.
</synopsis>
</specialValue>
<specialValue value="7">
<name>InvalidIPv4DstAddr</name>
<synopsis>
Error case: packet with invalid IPv4 destination
address.
</synopsis>
</specialValue>
<specialValue value="8">
<name>InvalidIPv6PacketSize</name>
<synopsis>
Error case: packet size is less than 40 bytes.
</synopsis>
</specialValue>
<specialValue value="9">
<name>NotIPv6Packet</name>
<synopsis>
Error case: packet is not IP version 6
</synopsis>
</specialValue>
<specialValue value="10">
<name>InvalidIPv6SrcAddr</name>
<synopsis>
Error case: packet with invalid IPv6 source address.
</synopsis>
</specialValue>
<specialValue value="11">
<name>InvalidIPv6DstAddr</name>
<synopsis>
Error case: packet with invalid IPv6 destination
address.
</synopsis>
</specialValue>
</specialValues>
</atomic>
</metadataDef>
<metadataDef>
<name>L3PortID</name>
<synopsis>
Metadata indicating ID of an L3 logical port
</synopsis>
<metadataID>13</metadataID>
<typeRef>uint32</typeRef>
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</metadataDef>
<metadataDef>
<name>RedirectIndex</name>
<synopsis>
Metadata that CE sends to RedirectIn LFB, indicating
the index of the LFB group output port.
</synopsis>
<metadataID>14</metadataID>
<typeRef>uint32</typeRef>
</metadataDef>
<metadataDef>
<name>MediaEncapInfoIndex</name>
<synopsis>
A search key a packet uses to look up a table to select
an encapsulation media.
</synopsis>
<metadataID>15</metadataID>
<typeRef>uint32</typeRef>
</metadataDef>
</metadataDefs>
</LFBLibrary>
5. LFB Class Descriptions
According to ForCES specifications, an LFB (Logical Function Block)
is a well-defined, logically separable functional block that resides
in an FE and is a functionally accurate abstraction of the FE's
processing capabilities. An LFB class (or type) is a template that
represents a fine-grained, logically separable aspect of FE
processing. Most LFBs are related to packet processing in the data
path. LFB classes are the basic building blocks of the FE model.
Note that [RFC5810] has already defined an 'FE Protocol LFB', which
is a logical entity in each FE to control the ForCES protocol.
[RFC5812] has already defined an 'FE Object LFB'. Information like
the FE Name, FE ID, FE State, and LFB Topology in the FE are
represented in this LFB.
As specified in Section 3.1, this document focuses on the base LFB
library for implementing typical router functions, especially for IP
forwarding functions. As a result, LFB classes in the library are
all base LFBs to implement router forwarding.
In this section, the terms "upstream LFB" and "downstream LFB" are
used. These are used relative to the LFB that is being described.
An "upstream LFB" is one whose output ports are connected to input
ports of the LFB under consideration such that output (typically
packets with metadata) can be sent from the "upstream LFB" to the LFB
under consideration. Similarly, a "downstream LFB" whose input ports
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are connected to output ports of the LFB under consideration such
that the LFB under consideration can send information to the
"downstream LFB". Note that in some rare topologies, an LFB may be
both upstream and downstream relative to another LFB.
Also note that, as a default provision of [RFC5812], in the FE model,
all metadata produced by upstream LFBs will pass through all
downstream LFBs by default without being specified by input port or
output port. Only those metadata that will be used (consumed) by an
LFB will be explicitly marked in the input of the LFB as expected
metadata. For instance, in downstream LFBs of a physical-layer LFB,
even if there is no specific metadata expected, metadata like
PHYPortID produced by the physical-layer LFB will always pass through
all downstream LFBs regardless of whether or not the metadata has
been expected by the LFBs.
5.1. Ethernet-Processing LFBs
As the most popular physical- and data-link-layer protocol, Ethernet
is widely deployed. It becomes a basic requirement for a router to
be able to process various Ethernet data packets.
Note that different versions of Ethernet formats exist, like Ethernet
V2, 802.3 RAW, IEEE 802.3/802.2, and IEEE 802.3/802.2 SNAP.
Varieties of LAN techniques based on Ethernet also exist, like
various VLANs, MACinMAC, etc. Ethernet-processing LFBs defined here
are intended to be able to cope with all these variations of Ethernet
technology.
There are also various types of Ethernet physical interface media.
Among them, copper and fiber media may be the most popular ones. As
a base LFB definition and a starting point, this document only
defines an Ethernet physical LFB with copper media. For other media
interfaces, specific LFBs may be defined in future versions of the
library.
5.1.1. EtherPHYCop
EtherPHYCop LFB abstracts an Ethernet interface physical layer with
media limited to copper.
5.1.1.1. Data Handling
This LFB is the interface to the Ethernet physical media. The LFB
handles Ethernet frames coming in from or going out of the FE.
Ethernet frames sent and received cover all packets encapsulated with
different versions of Ethernet protocols, like Ethernet V2, 802.3
RAW, IEEE 802.3/802.2, and IEEE 802.3/802.2 SNAP, including packets
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encapsulated with varieties of LAN techniques based on Ethernet, like
various VLANs, MACinMAC, etc. Therefore, in the XML, an EthernetAll
frame type has been introduced.
Ethernet frames are received from the physical media port and passed
downstream to LFBs, such as EtherMACIn LFBs, via a singleton output
known as "EtherPHYOut". A PHYPortID metadata, which indicates the
physical port from which the frame came in from the external world,
is passed along with the frame.
Ethernet packets are received by this LFB from upstream LFBs, such as
EtherMacOut LFBs, via the singleton input known as "EtherPHYIn"
before being sent out to the external world.
5.1.1.2. Components
The AdminStatus component is defined for the CE to administratively
manage the status of the LFB. The CE may administratively start up
or shut down the LFB by changing the value of AdminStatus. The
default value is set to 'Down'.
An OperStatus component captures the physical port operational
status. A PHYPortStatusChanged event is defined so the LFB can
report to the CE whenever there is an operational status change of
the physical port.
The PHYPortID component is a unique identification for a physical
port. It is defined as 'read-only' by the CE. Its value is
enumerated by FE. The component will be used to produce a PHYPortID
metadata at the LFB output and to associate it to every Ethernet
packet this LFB receives. The metadata will be handed to downstream
LFBs for them to use the PHYPortID.
A group of components are defined for link speed management. The
AdminLinkSpeed is for the CE to configure link speed for the port,
and the OperLinkSpeed is for the CE to query the actual link speed in
operation. The default value for the AdminLinkSpeed is set to auto-
negotiation mode.
A group of components are defined for duplex mode management. The
AdminDuplexMode is for the CE to configure proper duplex mode for the
port, and the OperDuplexMode is for CE to query the actual duplex
mode in operation. The default value for the AdminDuplexMode is set
to auto-negotiation mode.
A CarrierStatus component captures the status of the carrier and
specifies whether the port link is operationally up. The default
value for the CarrierStatus is 'false'.
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5.1.1.3. Capabilities
The capability information for this LFB includes the link speeds that
are supported by the FE (SupportedLinkSpeed) as well as the supported
duplex modes (SupportedDuplexMode).
5.1.1.4. Events
Several events are generated. There is an event for changes in the
status of the physical port (PhyPortStatusChanged). Such an event
will notify that the physical port status has been changed, and the
report will include the new status of the physical port.
Another event captures changes in the operational link speed
(LinkSpeedChanged). Such an event will notify the CE that the
operational speed has been changed, and the report will include the
new negotiated operational speed.
A final event captures changes in the duplex mode
(DuplexModeChanged). Such an event will notify the CE that the
duplex mode has been changed and the report will include the new
negotiated duplex mode.
5.1.2. EtherMACIn
EtherMACIn LFB abstracts an Ethernet port at the MAC data link layer.
This LFB describes Ethernet processing functions like checking MAC
address locality, deciding if the Ethernet packets should be bridged,
providing Ethernet-layer flow control, etc.
5.1.2.1. Data Handling
The LFB is expected to receive all types of Ethernet packets (via a
singleton input known as "EtherPktsIn"), which are usually output
from some Ethernet physical-layer LFB, like an EtherPHYCop LFB, along
with a metadata indicating the physical port ID of the port on which
the packet arrived.
The LFB is defined with two separate singleton outputs. All output
packets are emitted in the original Ethernet format received at the
physical port, unchanged, and cover all Ethernet types.
The first singleton output is known as "NormalPathOut". It usually
outputs Ethernet packets to some LFB, like an EtherClassifier LFB,
for further L3 forwarding process along with a PHYPortID metadata
indicating the physical port from which the packet came.
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The second singleton output is known as "L2BridgingPathOut".
Although the LFB library this document defines is basically to meet
typical router functions, it will attempt to be forward compatible
with future router functions. The L2BridgingPathOut is defined to
meet the requirement that L2 bridging functions may be optionally
supported simultaneously with L3 processing and some L2 bridging LFBs
that may be defined in the future. If the FE supports L2 bridging,
the CE can enable or disable it by means of a "L2BridgingPathEnable"
component in the FE. If it is enabled, by also instantiating some L2
bridging LFB instances following the L2BridgingPathOut, FEs are
expected to fulfill L2 bridging functions. L2BridgingPathOut will
output packets exactly the same as in the NormalPathOut output.
This LFB can be set to work in a promiscuous mode, allowing all
packets to pass through the LFB without being dropped. Otherwise, a
locality check will be performed based on the local MAC addresses.
All packets that do not pass through the locality check will be
dropped.
This LFB can optionally participate in Ethernet flow control in
cooperation with EtherMACOut LFB. This document does not go into the
details of how this is implemented. This document also does not
describe how the buffers that induce the flow control messages behave
-- it is assumed that such artifacts exist, and describing them is
out of scope in this document.
5.1.2.2. Components
The AdminStatus component is defined for the CE to administratively
manage the status of the LFB. The CE may administratively start up
or shut down the LFB by changing the value of AdminStatus. The
default value is set to 'Down'.
The LocalMACAddresses component specifies the local MAC addresses
based on which locality checks will be made. This component is an
array of MAC addresses and of 'read-write' access permission.
An L2BridgingPathEnable component captures whether the LFB is set to
work as an L2 bridge. An FE that does not support bridging will
internally set this flag to false and additionally set the flag
property as read-only. The default value for the component is
'false'.
The PromiscuousMode component specifies whether the LFB is set to
work in a promiscuous mode. The default value for the component is
'false'.
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The TxFlowControl component defines whether the LFB is performing
flow control on sending packets. The default value is 'false'. Note
that the component is defined as "optional". If an FE does not
implement the component while a CE tries to configure the component
to that FE, an error from the FE may be responded to the CE with an
error code like 0x09 (E_COMPONENT_DOES_NOT_EXIST) or 0x15
(E_NOT_SUPPORTED), depending on the FE processing. See [RFC5810] for
details.
The RxFlowControl component defines whether the LFB is performing
flow control on receiving packets. The default value is 'false'.
The component is defined as "optional".
A struct component, MACInStats, defines a set of statistics for this
LFB, including the number of received packets and the number of
dropped packets. Note that this statistics component is optional to
implementers. If a CE tries to query the component while it is not
implemented in an FE, an error code will be responded to the CE
indicating the error type like 0x09 (E_COMPONENT_DOES_NOT_EXIST) or
0x15 (E_NOT_SUPPORTED), depending on the FE implementation.
5.1.2.3. Capabilities
This LFB does not have a list of capabilities.
5.1.2.4. Events
This LFB does not have any events specified.
5.1.3. EtherClassifier
The EtherClassifier LFB abstracts the process to decapsulate Ethernet
packets and then classify them.
5.1.3.1. Data Handling
This LFB describes the process of decapsulating Ethernet packets and
classifying them into various network-layer data packets according to
information included in the Ethernet packets headers.
The LFB is expected to receive all types of Ethernet packets (via a
singleton input known as "EtherPktsIn"), which are usually output
from an upstream LFB like EtherMACIn LFB. This input is also capable
of multiplexing to allow for multiple upstream LFBs to be connected.
For instance, when an L2 bridging function is enabled in the
EtherMACIn LFB, some L2 bridging LFBs may be applied. In this case,
after L2 processing, some Ethernet packets may have to be input to
the EtherClassifier LFB for classification, while simultaneously,
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packets directly output from EtherMACIn may also need to input to
this LFB. This input is capable of handling such a case. Usually,
all expected Ethernet packets will be associated with a PHYPortID
metadata, indicating the physical port from which the packet comes.
In some cases, for instance, in a MACinMAC case, a LogicalPortID
metadata may be expected to associate with the Ethernet packet to
further indicate the logical port to which the Ethernet packet
belongs. Note that PHYPortID metadata is always expected while
LogicalPortID metadata is optionally expected.
Two output LFB ports are defined.
The first output is a group output port known as "ClassifyOut".
Types of network-layer protocol packets are output to instances of
the port group. Because there may be various types of protocol
packets at the output ports, the produced output frame is defined as
arbitrary for the purpose of wide extensibility in the future.
Metadata to be carried along with the packet data is produced at this
LFB for consumption by downstream LFBs. The metadata passed
downstream includes PHYPortID, as well as information on Ethernet
type, source MAC address, destination MAC address, and the logical
port ID. If the original packet is a VLAN packet and contains a VLAN
ID and a VLAN priority value, then the VLAN ID and the VLAN priority
value are also carried downstream as metadata. As a result, the VLAN
ID and priority metadata are defined with the availability of
"conditional".
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
o There is no matching when classifying the packet.
Usually, the ExceptionOut port may point to nowhere, indicating
packets with exceptions are dropped, while in some cases, the output
may be pointed to the path to the CE for further processing,
depending on individual implementations.
5.1.3.2. Components
An EtherDispatchTable array component is defined in the LFB to
dispatch every Ethernet packet to the output group according to the
logical port ID assigned by the VlanInputTable to the packet and the
Ethernet type in the Ethernet packet header. Each row of the array
is a struct containing a logical port ID, an EtherType and an output
index. With the CE configuring the dispatch table, the LFB can be
expected to classify various network-layer protocol type packets and
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output them at different output ports. It is expected that the LFB
classify packets according to protocols like IPv4, IPv6, MPLS,
Address Resolution Protocol (ARP), Neighbor Discovery (ND), etc.
A VlanInputTable array component is defined in the LFB to classify
VLAN Ethernet packets. Each row of the array is a struct containing
an incoming port ID, a VLAN ID, and a logical port ID. According to
IEEE VLAN specifications, all Ethernet packets can be recognized as
VLAN types by defining that if there is no VLAN encapsulation in a
packet, a case with VLAN tag 0 is considered. Every input packet is
assigned with a new LogicalPortID according to the packet's incoming
port ID and the VLAN ID. A packet's incoming port ID is defined as a
logical port ID if a logical port ID is associated with the packet or
a physical port ID if no logical port ID is associated. The VLAN ID
is exactly the VLAN ID in the packet if it is a VLAN packet, or 0 if
it is not. Note that a logical port ID of a packet may be rewritten
with a new one by the VlanInputTable processing.
Note that the logical port ID and physical port ID mentioned above
are all originally configured by the CE, and are globally effective
within a ForCES NE (Network Element). To distinguish a physical port
ID from a logical port ID in the incoming port ID field of the
VlanInputTable, physical port ID and logical port ID must be assigned
with separate number spaces.
An array component, EtherClassifyStats, defines a set of statistics
for this LFB, measuring the number of packets per EtherType. Each
row of the array is a struct containing an EtherType and a packet
number. Note that this statistics component is optional to
implementers.
5.1.3.3. Capabilities
This LFB does not have a list of capabilities.
5.1.3.4. Events
This LFB has no events specified.
5.1.4. EtherEncap
The EtherEncap LFB abstracts the process to replace or attach
appropriate Ethernet headers to the packet.
5.1.4.1. Data Handling
This LFB abstracts the process of encapsulating Ethernet headers onto
received packets. The encapsulation is based on passed metadata.
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The LFB is expected to receive IPv4 and IPv6 packets (via a singleton
input port known as "EncapIn"), which may be connected to an upstream
LFB like IPv4NextHop, IPv6NextHop, BasicMetadataDispatch, or any LFB
that requires output packets for Ethernet encapsulation. The LFB
always expects from upstream LFBs the MediaEncapInfoIndex metadata,
which is used as a search key to look up the encapsulation table
EncapTable by the search key matching the table index. An input
packet may also optionally receive a VLAN priority metadata,
indicating that the packet originally had a priority value. The
priority value will be loaded back to the packet when encapsulating.
The optional VLAN priority metadata is defined with a default value
of 0.
Two singleton output LFB ports are defined.
The first singleton output is known as "SuccessOut". Upon a
successful table lookup, the destination and source MAC addresses and
the logical media port (L2PortID) are found in the matching table
entry. The CE may set the VlanID in case VLANs are used. By
default, the table entry for VlanID of 0 is used as per IEEE rules
[IEEE.802-1Q]. Whatever the value of VlanID, if the input metadata
VlanPriority is non-zero, the packet will have a VLAN tag. If the
VlanPriority and the VlanID are all zero, there is no VLAN tag for
this packet. After replacing or attaching the appropriate Ethernet
headers to the packet is complete, the packet is passed out on the
"SuccessOut" LFB port to a downstream LFB instance along with the
L2PortID.
The second singleton output is known as "ExceptionOut" and will
output packets for which the table lookup fails, along with an
additional ExceptionID metadata. Currently defined exception types
only include the following cases:
o The MediaEncapInfoIndex value of the packet is invalid and can not
be allocated in the EncapTable.
o The packet failed lookup of the EncapTable table even though the
MediaEncapInfoIndex is valid.
The upstream LFB may be programmed by the CE to pass along a
MediaEncapInfoIndex that does not exist in the EncapTable. This
allows for resolution of the L2 headers, if needed, to be made at the
L2 encapsulation level, in this case, Ethernet via ARP or ND (or
other methods depending on the link-layer technology), when a table
miss occurs.
For neighbor L2 header resolution (table miss exception), the
processing LFB may pass this packet to the CE via the redirect LFB or
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FE software or another LFB instance for further resolution. In such
a case, the metadata NextHopIPv4Addr or NextHopIPv6Addr generated by
the next-hop LFB is also passed to the exception handling. Such an
IP address could be used to do activities such as ARP or ND by the
handler to which it is passed.
The result of the L2 resolution is to update the EncapTable as well
as the next-hop LFB so subsequent packets do not fail EncapTable
lookup. The EtherEncap LFB does not make any assumptions of how the
EncapTable is updated by the CE (or whether ARP/ND is used
dynamically or static maps exist).
Downstream LFB instances could be either an EtherMACOut type or a
BasicMetadataDispatch type. If the final packet L2 processing is on
a per-media-port basis, resides on a different FE, or needs L2 header
resolution, then it makes sense for the model to use a
BasicMetadataDispatch LFB to fan out to different LFB instances. If
there is a direct egress port point, then it makes sense for the
model to have a downstream LFB instance be an EtherMACOut.
5.1.4.2. Components
This LFB has only one component named EncapTable, which is defined as
an array. Each row of the array is a struct containing the
destination MAC address, the source MAC address, the VLAN ID with a
default value of zero, and the output logical L2 port ID.
5.1.4.3. Capabilities
This LFB does not have a list of capabilities.
5.1.4.4. Events
This LFB does not have any events specified.
5.1.5. EtherMACOut
The EtherMACOut LFB abstracts an Ethernet port at the MAC data link
layer. This LFB describes Ethernet packet output process. Ethernet
output functions are closely related to Ethernet input functions;
therefore, many components defined in this LFB are aliases of
EtherMACIn LFB components.
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5.1.5.1. Data Handling
The LFB is expected to receive all types of Ethernet packets (via a
singleton input known as "EtherPktsIn"), which are usually output
from an Ethernet encapsulation LFB along with a metadata indicating
the ID of the physical port that the packet will go through.
The LFB is defined with a singleton output port known as
"EtherPktsOut". All output packets are in Ethernet format, possibly
with various Ethernet types, along with a metadata indicating the ID
of the physical port that the packet is to go through. This output
links to a downstream LFB that is usually an Ethernet physical LFB
like the EtherPHYCop LFB.
This LFB can optionally participate in Ethernet flow control in
cooperation with the EtherMACIn LFB. This document does not go into
the details of how this is implemented. This document also does not
describe how the buffers that induce the flow control messages behave
-- it is assumed that such artifacts exist, but describing them is
out of the scope of this document.
Note that as a base definition, functions like multiple virtual MAC
layers are not supported in this LFB version. It may be supported in
the future by defining a subclass or a new version of this LFB.
5.1.5.2. Components
The AdminStatus component is defined for the CE to administratively
manage the status of the LFB. The CE may administratively start up
or shut down the LFB by changing the value of AdminStatus. The
default value is set to 'Down'. Note that this component is defined
as an alias of the AdminStatus component in the EtherMACIn LFB. This
infers that an EtherMACOut LFB usually coexists with an EtherMACIn
LFB, both of which share the same administrative status management by
the CE. Alias properties, as defined in the ForCES FE model
[RFC5812], will be used by the CE to declare the target component to
which the alias refers, which includes the target LFB class and
instance IDs as well as the path to the target component.
The MTU component defines the maximum transmission unit.
The optional TxFlowControl component defines whether or not the LFB
is performing flow control on sending packets. The default value is
'false'. Note that this component is defined as an alias of the
TxFlowControl component in the EtherMACIn LFB.
The optional RxFlowControl component defines whether or not the LFB
is performing flow control on receiving packets. The default value
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is 'false'. Note that this component is defined as an alias of the
RxFlowControl component in the EtherMACIn LFB.
A struct component, MACOutStats, defines a set of statistics for this
LFB, including the number of transmitted packets and the number of
dropped packets. This statistics component is optional to
implementers.
5.1.5.3. Capabilities
This LFB does not have a list of capabilities.
5.1.5.4. Events
This LFB does not have any events specified.
5.2. IP Packet Validation LFBs
The LFBs are defined to abstract the IP packet validation process.
An IPv4Validator LFB is specifically for IPv4 protocol validation,
and an IPv6Validator LFB is specifically for IPv6.
5.2.1. IPv4Validator
The IPv4Validator LFB performs IPv4 packet validation.
5.2.1.1. Data Handling
This LFB performs IPv4 validation according to [RFC1812] and its
updates. The IPv4 packet will be output to the corresponding LFB
port, indicating whether the packet is unicast or multicast or
whether an exception has occurred or the validation failed.
This LFB always expects, as input, packets that have been indicated
as IPv4 packets by an upstream LFB, like an EtherClassifier LFB.
There is no specific metadata expected by the input of the LFB.
Four output LFB ports are defined.
All validated IPv4 unicast packets will be output at the singleton
port known as "IPv4UnicastOut". All validated IPv4 multicast packets
will be output at the singleton port known as "IPv4MulticastOut"
port.
A singleton port known as "ExceptionOut" is defined to output packets
that have been validated as exception packets. An exception ID
metadata is produced to indicate what has caused the exception. An
exception case is the case when a packet needs further processing
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before being normally forwarded. Currently defined exception types
include:
o Packet with expired TTL
o Packet with header length more than 5 words
o Packet IP head including router alert options
o Packet with exceptional source address
o Packet with exceptional destination address
Note that although Time to Live (TTL) is checked in this LFB for
validity, operations like TTL decrement are made by the downstream
forwarding LFB.
The final singleton port known as "FailOut" is defined for all
packets that have errors and failed the validation process. An error
case is when a packet is unable to be further processed or forwarded
without being dropped. An error ID is associated with a packet to
indicate the failure reason. Currently defined failure reasons
include:
o Packet with size reported less than 20 bytes
o Packet with version not IPv4
o Packet with header length less than 5 words
o Packet with total length field less than 20 bytes
o Packet with invalid checksum
o Packet with invalid source address
o Packet with invalid destination address
5.2.1.2. Components
This LFB has only one struct component, the
IPv4ValidatorStatisticsType, which defines a set of statistics for
validation process, including the number of bad header packets, the
number of bad total length packets, the number of bad TTL packets,
and the number of bad checksum packets. This statistics component is
optional to implementers.
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5.2.1.3. Capabilities
This LFB does not have a list of capabilities
5.2.1.4. Events
This LFB does not have any events specified.
5.2.2. IPv6Validator
The IPv6Validator LFB performs IPv6 packet validation.
5.2.2.1. Data Handling
This LFB performs IPv6 validation according to [RFC2460] and its
updates. Then the IPv6 packet will be output to the corresponding
port regarding of the validation result, indicating whether the
packet is a unicast or a multicast one, an exception has occurred or
the validation failed.
This LFB always expects, as input, packets that have been indicated
as IPv6 packets by an upstream LFB, like an EtherClassifier LFB.
There is no specific metadata expected by the input of the LFB.
Similar to the IPv4validator LFB, the IPv6Validator LFB has also
defined four output ports to emit packets with various validation
results.
All validated IPv6 unicast packets will be output at the singleton
port known as "IPv6UnicastOut". All validated IPv6 multicast packets
will be output at the singleton port known as "IPv6MulticastOut".
There is no metadata produced at this LFB.
A singleton port known as "ExceptionOut" is defined to output packets
that have been validated as exception packets. An exception case is
when a packet needs further processing before being normally
forwarded. An exception ID metadata is produced to indicate what
caused the exception. Currently defined exception types include:
o Packet with hop limit to zero
o Packet with next header set to hop-by-hop
o Packet with exceptional source address
o Packet with exceptional destination address
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The final singleton port known as "FailOut" is defined for all
packets that have errors and failed the validation process. An error
case when a packet is unable to be further processed or forwarded
without being dropped. A validate error ID is associated to every
failed packet to indicate the reason. Currently defined reasons
include:
o Packet with size reported less than 40 bytes
o Packet with version not IPv6
o Packet with invalid source address
o Packet with invalid destination address
Note that in the base type library, definitions for exception ID and
validate error ID metadata are applied to both IPv4Validator and
IPv6Validator LFBs, i.e., the two LFBs share the same metadata
definition, with different ID assignment inside.
5.2.2.2. Components
This LFB has only one struct component, the
IPv6ValidatorStatisticsType, which defines a set of statistics for
the validation process, including the number of bad header packets,
the number of bad total length packets, and the number of bad hop
limit packets. Note that this component is optional to implementers.
5.2.2.3. Capabilities
This LFB does not have a list of capabilities.
5.2.2.4. Events
This LFB does not have any events specified.
5.3. IP Forwarding LFBs
IP Forwarding LFBs are specifically defined to abstract the IP
forwarding processes. As definitions for a base LFB library, this
document restricts its LFB definition scope only to IP unicast
forwarding. IP multicast may be defined in future documents.
The two fundamental tasks performed in IP unicast forwarding
constitute looking up the forwarding information table to find next-
hop information and then using the resulting next-hop details to
forward packets out on specific physical output ports. This document
models the forwarding processes by abstracting out the described two
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steps. Whereas this document describes functional LFB models that
are modular, there may be multiple ways to implement the abstracted
models. It is not intended or expected that the provided LFB models
constrain implementations.
Based on the IP forwarding abstraction, two kinds of typical IP
unicast forwarding LFBs are defined: unicast LPM lookup LFB and next-
hop application LFB. They are further distinguished by IPv4 and IPv6
protocols.
5.3.1. IPv4UcastLPM
The IPv4UcastLPM LFB abstracts the IPv4 unicast Longest Prefix Match
(LPM) process.
This LFB also provides facilities to support users to implement
equal-cost multipath (ECMP) routing or reverse path forwarding (RPF).
However, this LFB itself does not provide ECMP or RPF. To fully
implement ECMP or RPF, additional specific LFBs, like a specific ECMP
LFB or an RPF LFB, will have to be defined.
5.3.1.1. Data Handling
This LFB performs the IPv4 unicast LPM table lookup. It always
expects as input IPv4 unicast packets from one singleton input known
as "PktsIn". Then, the LFB uses the destination IPv4 address of
every packet as a search key to look up the IPv4 prefix table and
generate a hop selector as the matching result. The hop selector is
passed as packet metadata to downstream LFBs and will usually be used
there as a search index to find more next-hop information.
Three singleton output LFB ports are defined.
The first singleton output is known as "NormalOut" and outputs IPv4
unicast packets that succeed the LPM lookup (and got a hop selector).
The hop selector is associated with the packet as a metadata.
Downstream from the LPM LFB is usually a next-hop application LFB,
like an IPv4NextHop LFB.
The second singleton output is known as "ECMPOut" and is defined to
provide support for users wishing to implement ECMP.
An ECMP flag is defined in the LPM table to enable the LFB to support
ECMP. When a table entry is created with the flag set to true, it
indicates this table entry is for ECMP only. A packet that has
passed through this prefix lookup will always output from the
"ECMPOut" output port, with the hop selector being its lookup result.
The output will usually go directly to a downstream ECMP processing
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LFB, where the hop selector can usually further generate optimized
one or multiple next-hop routes by use of ECMP algorithms.
A default route flag is defined in the LPM table to enable the LFB to
support a default route as well as loose RPF. When this flag is set
to true, the table entry is identified as a default route, which also
implies that the route is forbidden for RPF. If a user wants to
implement RPF on FE, a specific RPF LFB will have to be defined. In
such an RPF LFB, a component can be defined as an alias of the prefix
table component of this LFB, as described below.
The final singleton output is known as "ExceptionOut" of the
IPv4UcastLPM LFB and is defined to output exception packets after the
LFB processing, along with an ExceptionID metadata to indicate what
caused the exception. Currently defined exception types include:
o The packet failed the LPM lookup of the prefix table.
The upstream LFB of this LFB is usually an IPv4Validator LFB. If RPF
is to be adopted, the upstream can be an RPF LFB, when defined.
The downstream LFB is usually an IPv4NextHop LFB. If ECMP is
adopted, the downstream can be an ECMP LFB, when defined.
5.3.1.2. Components
This LFB has two components.
The IPv4PrefixTable component is defined as an array component of the
LFB. Each row of the array contains an IPv4 address, a prefix
length, a hop selector, an ECMP flag and a default route flag. The
LFB uses the destination IPv4 address of every input packet as a
search key to look up this table in order extract a next-hop
selector. The ECMP flag is for the LFB to support ECMP. The default
route flag is for the LFB to support a default route and for loose
RPF.
The IPv4UcastLPMStats component is a struct component that collects
statistics information, including the total number of input packets
received, the IPv4 packets forwarded by this LFB, and the number of
IP datagrams discarded due to no route found. Note that this
component is defined as optional to implementers.
5.3.1.3. Capabilities
This LFB does not have a list of capabilities.
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5.3.1.4. Events
This LFB does not have any events specified.
5.3.2. IPv4NextHop
This LFB abstracts the process of selecting IPv4 next-hop action.
5.3.2.1. Data Handling
The LFB abstracts the process of next-hop information application to
IPv4 packets. It receives an IPv4 packet with an associated next-hop
identifier (HopSelector) and uses the identifier as a table index to
look up a next-hop table to find an appropriate LFB output port.
The LFB is expected to receive unicast IPv4 packets, via a singleton
input known as "PktsIn", along with a HopSelector metadata, which is
used as a table index to look up the NextHop table. The data
processing involves the forwarding TTL decrement and IP checksum
recalculation.
Two output LFB ports are defined.
The first output is a group output port known as "SuccessOut". On
successful data processing, the packet is sent out from an LFB port
from within the LFB port group as selected by the
LFBOutputSelectIndex value of the matched table entry. The packet is
sent to a downstream LFB along with the L3PortID and
MediaEncapInfoIndex metadata.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
o The HopSelector for the packet is invalid.
o The packet failed lookup of the next-hop table even though the
HopSelector is valid.
o The MTU for outgoing interface is less than the packet size.
Downstream LFB instances could be either a BasicMetadataDispatch type
(Section 5.5.1), used to fan out to different LFB instances or a
media-encapsulation-related type, such as an EtherEncap type or a
RedirectOut type (Section 5.4.2). For example, if there are Ethernet
and other tunnel encapsulation, then a BasicMetadataDispatch LFB can
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use the L3PortID metadata (Section 5.3.2.2) to dispatch packets to a
different encapsulator.
5.3.2.2. Components
This LFB has only one component, IPv4NextHopTable, which is defined
as an array. The HopSelector received is used to match the array
index of IPv4NextHopTable to find out a row of the table as the next-
hop information result. Each row of the array is a struct
containing:
o The L3PortID, which is the ID of the logical output port that is
passed on to the downstream LFB instance. This ID indicates what
kind of encapsulating port the neighbor is to use. This is L3-
derived information that affects L2 processing and so needs to be
based from one LFB to another as metadata. Usually, this ID is
used for the next-hop LFB to distinguish packets that need
different L2 encapsulating. For instance, some packets may
require general Ethernet encapsulation while others may require
various types of tunnel encapsulations. In such a case, different
L3PortIDs are assigned to the packets and are passed as metadata
to a downstream LFB. A BasicMetadataDispatch LFB (Section 5.5.1)
may have to be applied as the downstream LFB so as to dispatch
packets to different encapsulation LFB instances according to the
L3PortIDs.
o MTU, the Maximum Transmission Unit for the outgoing port.
o NextHopIPAddr, the IPv4 next-hop address.
o MediaEncapInfoIndex, the index that passes on to the downstream
encapsulation LFB instance and that is used there as a search key
to look up a table (typically media-encapsulation-related) for
further encapsulation information. The search key looks up the
table by matching the table index. Note that the encapsulation
LFB instance that uses this metadata may not be the LFB instance
that immediately follows this LFB instance in the processing. The
MediaEncapInfoIndex metadata is attached here and is passed
through intermediate LFBs until it is used by the encapsulation
LFB instance. In some cases, depending on implementation, the CE
may set the MediaEncapInfoIndex passed downstream to a value that
will fail lookup when it gets to a target encapsulation LFB; such
a lookup failure at that point is an indication that further
resolution is needed. For an example of this approach, refer to
Section 7.2, which discusses ARP and mentions this approach.
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o LFBOutputSelectIndex, the LFB group output port index to select
the downstream LFB port. This value identifies the specific port
within the SuccessOut port group out of which packets that
successfully use this next-hop entry are to be sent.
5.3.2.3. Capabilities
This LFB does not have a list of capabilities.
5.3.2.4. Events
This LFB does not have any events specified.
5.3.3. IPv6UcastLPM
The IPv6UcastLPM LFB abstracts the IPv6 unicast Longest Prefix Match
(LPM) process. The definition of this LFB is similar to the
IPv4UcastLPM LFB except that all IP addresses refer to IPv6
addresses.
This LFB also provides facilities to support users to implement
equal-cost multipath (ECMP) routing or reverse path forwarding (RPF).
However, this LFB itself does not provide ECMP or RPF. To fully
implement ECMP or RPF, additional specific LFBs, like a specific ECMP
LFB or an RPF LFB, will have to be defined. This work may be done in
future versions of this document.
5.3.3.1. Data Handling
This LFB performs the IPv6 unicast LPM table lookup. It always
expects as input IPv6 unicast packets from one singleton input known
as "PktsIn". The destination IPv6 address of an incoming packet is
used as a search key to look up the IPv6 prefix table and generate a
hop selector. This hop selector result is associated to the packet
as a metadata and sent to downstream LFBs; it will usually be used in
downstream LFBs as a search key to find more next-hop information.
Three singleton output LFB ports are defined.
The first singleton output is known as "NormalOut" and outputs IPv6
unicast packets that succeed the LPM lookup (and got a hop selector).
The hop selector is associated with the packet as a metadata.
Downstream from the LPM LFB is usually a next-hop application LFB,
like an IPv6NextHop LFB.
The second singleton output is known as "ECMPOut" and is defined to
provide support for users wishing to implement ECMP.
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An ECMP flag is defined in the LPM table to enable the LFB to support
ECMP. When a table entry is created with the flag set to true, it
indicates this table entry is for ECMP only. A packet that has
passed through this prefix lookup will always output from the
"ECMPOut" output port, with the hop selector being its lookup result.
The output will usually go directly to a downstream ECMP processing
LFB, where the hop selector can usually further generate optimized
one or multiple next-hop routes by use of ECMP algorithms.
A default route flag is defined in the LPM table to enable the LFB to
support a default route as well as loose RPF. When this flag is set
to true, the table entry is identified as a default route, which also
implies that the route is forbidden for RPF.
If a user wants to implement RPF on FE, a specific RPF LFB will have
to be defined. In such an RPF LFB, a component can be defined as an
alias of the prefix table component of this LFB, as described below.
The final singleton output is known as "ExceptionOut" of the
IPv6UcastLPM LFB and is defined to output exception packets after the
LFB processing, along with an ExceptionID metadata to indicate what
caused the exception. Currently defined exception types include:
o The packet failed the LPM lookup of the prefix table.
The upstream LFB of this LFB is usually an IPv6Validator LFB. If RPF
is to be adopted, the upstream can be an RPF LFB, when defined.
The downstream LFB is usually an IPv6NextHop LFB. If ECMP is
adopted, the downstream can be an ECMP LFB, when defined.
5.3.3.2. Components
This LFB has two components.
The IPv6PrefixTable component is defined as an array component of the
LFB. Each row of the array contains an IPv6 address, a prefix
length, a hop selector, an ECMP flag, and a default route flag. The
ECMP flag is so the LFB can support ECMP. The default route flag is
for the LFB to support a default route and for loose RPF, as
described earlier.
The IPv6UcastLPMStats component is a struct component that collects
statistics information, including the total number of input packets
received, the IPv6 packets forwarded by this LFB and the number of IP
datagrams discarded due to no route found. Note that the component
is defined as optional to implementers.
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5.3.3.3. Capabilities
This LFB does not have a list of capabilities.
5.3.3.4. Events
This LFB does not have any events specified.
5.3.4. IPv6NextHop
This LFB abstracts the process of selecting IPv6 next-hop action.
5.3.4.1. Data Handling
The LFB abstracts the process of next-hop information application to
IPv6 packets. It receives an IPv6 packet with an associated next-hop
identifier (HopSelector) and uses the identifier to look up a next-
hop table to find an appropriate output port from the LFB.
The LFB is expected to receive unicast IPv6 packets, via a singleton
input known as "PktsIn", along with a HopSelector metadata, which is
used as a table index to look up the next-hop table.
Two output LFB ports are defined.
The first output is a group output port known as "SuccessOut". On
successful data processing, the packet is sent out from an LFB port
from within the LFB port group as selected by the
LFBOutputSelectIndex value of the matched table entry. The packet is
sent to a downstream LFB along with the L3PortID and
MediaEncapInfoIndex metadata.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
o The HopSelector for the packet is invalid.
o The packet failed lookup of the next-hop table even though the
HopSelector is valid.
o The MTU for outgoing interface is less than the packet size.
Downstream LFB instances could be either a BasicMetadataDispatch
type, used to fan out to different LFB instances, or a media
encapsulation related type, such as an EtherEncap type or a
RedirectOut type. For example, when the downstream LFB is
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BasicMetadataDispatch and Ethernet and other tunnel encapsulation
exist downstream from BasicMetadataDispatch, then the
BasicMetadataDispatch LFB can use the L3PortID metadata (see section
below) to dispatch packets to the different encapsulator LFBs.
5.3.4.2. Components
This LFB has only one component named IPv6NextHopTable, which is
defined as an array. The array index of IPv6NextHopTable is used for
a HopSelector to find out a row of the table as the next-hop
information. Each row of the array is a struct containing:
o The L3PortID, which is the ID of the logical output port that is
passed onto the downstream LFB instance. This ID indicates what
kind of encapsulating port the neighbor is to use. This is L3-
derived information that affects L2 processing and so needs to be
based from one LFB to another as metadata. Usually, this ID is
used for the next-hop LFB to distinguish packets that need
different L2 encapsulating. For instance, some packets may
require general Ethernet encapsulation while others may require
various types of tunnel encapsulations. In such a case, different
L3PortIDs are assigned to the packets and are passed as metadata
to a downstream LFB. A BasicMetadataDispatch LFB (Section 5.5.1)
may have to be applied as the downstream LFB so as to dispatch
packets to different encapsulation LFB instances according to the
L3PortIDs.
o MTU, the Maximum Transmission Unit for the outgoing port.
o NextHopIPAddr, the IPv6 next-hop address.
o MediaEncapInfoIndex, the index that is passed on to the downstream
encapsulation LFB instance and that is used there as a search key
to look up a table (typically media-encapsulation-related) for
further encapsulation information. The search key looks up the
table by matching the table index. Note that the encapsulation
LFB instance that uses this metadata may not be the LFB instance
that immediately follows this LFB instance in the processing. The
MediaEncapInfoIndex metadata is attached here and is passed
through intermediate LFBs until it is used by the encapsulation
LFB instance. In some cases, depending on implementation, the CE
may set the MediaEncapInfoIndex passed downstream to a value that
will fail lookup when it gets to a target encapsulation LFB; such
a lookup failure at that point is an indication that further
resolution is needed. For an example of this approach, refer to
Section 7.2, which discusses ARP and mentions this approach.
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o LFBOutputSelectIndex, the LFB group output port index to select
the downstream LFB port. This value identifies the specific port
within the SuccessOut port group out of which packets that
successfully use this next-hop entry are to be sent.
5.3.4.3. Capabilities
This LFB does not have a list of capabilities.
5.3.4.4. Events
This LFB does not have any events specified.
5.4. Redirect LFBs
Redirect LFBs abstract the data packet transportation process between
the CE and FE. Some packets output from some LFBs may have to be
delivered to the CE for further processing, and some packets
generated by the CE may have to be delivered to the FE and further to
some specific LFBs for data path processing. According to [RFC5810],
data packets and their associated metadata are encapsulated in a
ForCES redirect message for transportation between CE and FE. We
define two LFBs to abstract the process: a RedirectIn LFB and a
RedirectOut LFB. Usually, in an LFB topology of an FE, only one
RedirectIn LFB instance and one RedirectOut LFB instance exist.
5.4.1. RedirectIn
The RedirectIn LFB abstracts the process for the CE to inject data
packets into the FE data path.
5.4.1.1. Data Handling
A RedirectIn LFB abstracts the process for the CE to inject data
packets into the FE LFB topology so as to input data packets into FE
data paths. From the LFB topology's point of view, the RedirectIn
LFB acts as a source point for data packets coming from the CE;
therefore, the RedirectIn LFB is defined with a single output LFB
port (and no input LFB port).
The single output port of RedirectIn LFB is defined as a group output
type with the name of "PktsOut". Packets produced by this output
will have arbitrary frame types decided by the CE that generated the
packets. Possible frames may include IPv4, IPv6, or ARP protocol
packets. The CE may associate some metadata to indicate the frame
types and may also associate other metadata to indicate various
information on the packets. Among them, there MUST exist a
RedirectIndex metadata, which is an integer acting as an index. When
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the CE transmits the metadata along with the packet to a RedirectIn
LFB, the LFB will read the RedirectIndex metadata and output the
packet to one of its group output port instances, whose port index is
indicated by this metadata. Any other metadata, in addition to
RedirectIndex, will be passed untouched along the packet delivered by
the CE to the downstream LFB. This means the RedirectIndex metadata
from CE will be "consumed" by the RedirectIn LFB and will not be
passed to downstream LFB. Note that a packet from the CE without a
RedirectIndex metadata associated will be dropped by the LFB. Note
that all metadata visible to the LFB need to be global and IANA
controlled. See Section 8 ("IANA Considerations") of this document
for more details about a metadata ID space that can be used by
vendors and is "Reserved for Private Use".
5.4.1.2. Components
An optional statistics component is defined to collect the number of
packets received by the LFB from the CE. There are no other
components defined for the current version of the LFB.
5.4.1.3. Capabilities
This LFB does not have a list of capabilities.
5.4.1.4. Events
This LFB does not have any events specified.
5.4.2. RedirectOut
RedirectOut LFB abstracts the process for LFBs in the FE to deliver
data packets to the CE.
5.4.2.1. Data Handling
A RedirectOut LFB abstracts the process for LFBs in the FE to deliver
data packets to the CE. From the LFB topology's point of view, the
RedirectOut LFB acts as a sink point for data packets going to the
CE; therefore, the RedirectOut LFB is defined with a single input LFB
port (and no output LFB port).
The RedirectOut LFB has only one singleton input, known as "PktsIn",
but is capable of receiving packets from multiple LFBs by
multiplexing this input. The input expects any kind of frame type;
therefore, the frame type has been specified as arbitrary, and also
all types of metadata are expected. All associated metadata produced
(but not consumed) by previous processed LFBs should be delivered to
the CE via the ForCES protocol redirect message [RFC5810]. The CE
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can decide how to process the redirected packet by referencing the
associated metadata. As an example, a packet could be redirected by
the FE to the CE because the EtherEncap LFB is not able to resolve L2
information. The metadata "ExceptionID" created by the EtherEncap
LFB is passed along with the packet and should be sufficient for the
CE to do the necessary processing and resolve the L2 entry required.
Note that all metadata visible to the LFB need to be global and IANA
controlled. See Section 8 ("IANA Considerations") of this document
for more details about a metadata ID space that can be used by
vendors and is "Reserved for Private Use".
5.4.2.2. Components
An optional statistics component is defined to collect the number of
packets sent by the LFB to the CE. There are no other components
defined for the current version of the LFB.
5.4.2.3. Capabilities
This LFB does not have a list of capabilities.
5.4.2.4. Events
This LFB does not have any events specified.
5.5. General Purpose LFBs
5.5.1. BasicMetadataDispatch
The BasicMetadataDispatch LFB is defined to abstract the process in
which a packet is dispatched to some output path based on its
associated metadata value.
5.5.1.1. Data Handling
The BasicMetadataDispatch LFB has only one singleton input known as
"PktsIn". Every input packet should be associated with a metadata
that will be used by the LFB to do the dispatch. This LFB contains a
metadata ID and a dispatch table named MetadataDispatchTable, all
configured by the CE. The metadata ID specifies which metadata is to
be used for dispatching packets. The MetadataDispatchTable contains
entries of a metadata value and an OutputIndex, specifying that the
packet with the metadata value must go out from the LFB group output
port instance with the OutputIndex.
Two output LFB ports are defined.
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The first output is a group output port known as "PktsOut". A packet
with its associated metadata having found an OutputIndex by
successfully looking up the dispatch table will be output to the
group port instance with the corresponding index.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types only include one case:
o There is no matching when looking up the metadata dispatch table.
As an example, if the CE decides to dispatch packets according to a
physical port ID (PHYPortID), the CE may set the ID of PHYPortID
metadata to the LFB first. Moreover, the CE also sets the PHYPortID
actual values (the metadata values) and assigned OutputIndex for the
values to the dispatch table in the LFB. When a packet arrives, a
PHYPortID metadata is found associated with the packet, and the
metadata value is further used as a key to look up the dispatch table
to find out an output port instance for the packet.
Currently, the BasicMetadataDispatch LFB only allows the metadata
value of the dispatch table entry to be a 32-bit integer. A metadata
with other value types is not supported in this version. A more
complex metadata dispatch LFB may be defined in future versions of
the library. In that LFB, multiple tuples of metadata with more
value types supported may be used to dispatch packets.
5.5.1.2. Components
This LFB has two components. One component is MetadataID and the
other is MetadataDispatchTable. Each row entry of the dispatch table
is a struct containing the metadata value and the OutputIndex. Note
that currently, the metadata value is only allowed to be a 32-bit
integer. The metadata value is also defined as a content key for the
table. The concept of content key is a searching key for tables,
which is defined in the ForCES FE model [RFC5812]. With the content
key, the CE can manipulate the table by means of a specific metadata
value rather than by the table index only. See the ForCES FE model
[RFC5812] and also the ForCES protocol [RFC5810] for more details on
the definition and use of a content key.
5.5.1.3. Capabilities
This LFB does not have a list of capabilities.
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5.5.1.4. Events
This LFB does not have any events specified.
5.5.2. GenericScheduler
This is a preliminary generic scheduler LFB for abstracting a simple
scheduling process.
5.5.2.1. Data Handling
There exist various kinds of scheduling strategies with various
implementations. As a base LFB library, this document only defines a
preliminary generic scheduler LFB for abstracting a simple scheduling
process. Users may use this LFB as a basic LFB to further construct
more complex scheduler LFBs by means of "inheritance", as described
in [RFC5812].
Packets of any arbitrary frame type are received via a group input
known as "PktsIn" with no additional metadata expected. This group
input is capable of multiple input port instances. Each port
instance may be connected to a different upstream LFB output. Inside
the LFB, it is abstracted that each input port instance is connected
to a queue, and the queue is marked with a queue ID whose value is
exactly the same as the index of corresponding group input port
instance. Scheduling disciplines are applied to all queues and also
all packets in the queues. The group input port property
PortGroupLimits in ObjectLFB, as defined by the ForCES FE model
[RFC5810], provides means for the CE to query the capability of total
queue numbers the scheduler supports. The CE can then decide how
many queues it may use for a scheduling application.
Scheduled packets are output from a singleton output port of the LFB
knows as "PktsOut" with no corresponding metadata.
More complex scheduler LFBs may be defined with more complex
scheduling disciplines by succeeding this LFB. For instance, a
priority scheduler LFB may be defined by inheriting this LFB and
defining a component to indicate priorities for all input queues.
5.5.2.2. Components
The SchedulingDiscipline component is for the CE to specify a
scheduling discipline to the LFB. Currently defined scheduling
disciplines only include Round Robin (RR) strategy. The default
scheduling discipline is thus RR.
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The QueueStats component is defined to allow the CE to query every
queue status of the scheduler. It is an array component, and each
row of the array is a struct containing a queue ID. Currently
defined queue status includes the queue depth in packets and the
queue depth in bytes. Using the queue ID as the index, the CE can
query every queue for its used length in unit of packets or bytes.
Note that the QueueStats component is defined as optional to
implementers.
5.5.2.3. Capabilities
The following capability is currently defined for the
GenericScheduler.
o The queue length limit providing the storage ability for every
queue.
5.5.2.4. Events
This LFB does not have any events specified.
6. XML for LFB Library
<?xml version="1.0" encoding="UTF-8"?>
<LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
provides="BaseLFBLibrary">
<load library="BaseTypeLibrary"/>
<LFBClassDefs>
<LFBClassDef LFBClassID="3">
<name>EtherPHYCop</name>
<synopsis>
The EtherPHYCop LFB describes an Ethernet interface
that limits the physical media to copper.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort>
<name>EtherPHYIn</name>
<synopsis>
The input port of the EtherPHYCop LFB. It expects any
type of Ethernet frame.
</synopsis>
<expectation>
<frameExpected>
<ref>EthernetAll</ref>
</frameExpected>
</expectation>
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</inputPort>
</inputPorts>
<outputPorts>
<outputPort>
<name>EtherPHYOut</name>
<synopsis>
The output port of the EtherPHYCop LFB. The output
packet has the same Ethernet frame type as the
input packet, associated with a metadata indicating
the ID of the physical port.
</synopsis>
<product>
<frameProduced>
<ref>EthernetAll</ref>
</frameProduced>
<metadataProduced>
<ref>PHYPortID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1" access="read-only">
<name>PHYPortID</name>
<synopsis>
The identification of the physical port
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2" access="read-write">
<name>AdminStatus</name>
<synopsis>
The port status administratively requested
</synopsis>
<typeRef>PortStatusType</typeRef>
<defaultValue>2</defaultValue>
</component>
<component componentID="3" access="read-only">
<name>OperStatus</name>
<synopsis>
The port actual operational status
</synopsis>
<typeRef>PortStatusType</typeRef>
</component>
<component componentID="4" access="read-write">
<name>AdminLinkSpeed</name>
<synopsis>
The port link speed administratively requested
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</synopsis>
<typeRef>LANSpeedType</typeRef>
<defaultValue>LAN_SPEED_AUTO</defaultValue>
</component>
<component componentID="5" access="read-only">
<name>OperLinkSpeed</name>
<synopsis>
The port actual operational link speed
</synopsis>
<typeRef>LANSpeedType</typeRef>
</component>
<component componentID="6" access="read-write">
<name>AdminDuplexMode</name>
<synopsis>
The port duplex mode administratively requested
</synopsis>
<typeRef>DuplexType</typeRef>
<defaultValue>Auto</defaultValue>
</component>
<component componentID="7" access="read-only">
<name>OperDuplexMode</name>
<synopsis>
The port actual operational duplex mode
</synopsis>
<typeRef>DuplexType</typeRef>
</component>
<component componentID="8" access="read-only">
<name>CarrierStatus</name>
<synopsis>The carrier status of the port </synopsis>
<typeRef>boolean</typeRef>
<defaultValue>false</defaultValue>
</component>
</components>
<capabilities>
<capability componentID="30">
<name>SupportedLinkSpeed</name>
<synopsis>
A list of link speeds the port supports
</synopsis>
<array>
<typeRef>LANSpeedType</typeRef>
</array>
</capability>
<capability componentID="31">
<name>SupportedDuplexMode</name>
<synopsis>
A list of duplex modes the port supports
</synopsis>
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<array>
<typeRef>DuplexType</typeRef>
</array>
</capability>
</capabilities>
<events baseID="60">
<event eventID="1">
<name>PHYPortStatusChanged</name>
<synopsis>
An event reporting change on operational status of the
physical port.
</synopsis>
<eventTarget>
<eventField>OperStatus</eventField>
</eventTarget>
<eventChanged/>
<eventReports>
<eventReport>
<eventField>OperStatus</eventField>
</eventReport>
</eventReports>
</event>
<event eventID="2">
<name>LinkSpeedChanged</name>
<synopsis>
An event reporting change on operational link speed
of the physical port.
</synopsis>
<eventTarget>
<eventField>OperLinkSpeed</eventField>
</eventTarget>
<eventChanged/>
<eventReports>
<eventReport>
<eventField>OperLinkSpeed</eventField>
</eventReport>
</eventReports>
</event>
<event eventID="3">
<name>DuplexModeChanged</name>
<synopsis>
An event reporting change on operational duplex mode
of the physical port.
</synopsis>
<eventTarget>
<eventField>OperDuplexMode</eventField>
</eventTarget>
<eventChanged/>
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<eventReports>
<eventReport>
<eventField>OperDuplexMode</eventField>
</eventReport>
</eventReports>
</event>
</events>
</LFBClassDef>
<LFBClassDef LFBClassID="4">
<name>EtherMACIn</name>
<synopsis>
EtherMACIn LFB describes an Ethernet port at MAC data link
layer. The LFB describes Ethernet processing functions
of MAC address locality check, deciding if the Ethernet
packets should be bridged, providing Ethernet-layer flow
control, etc.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>EtherPktsIn</name>
<synopsis>
The input port of the EtherMACIn LFB. It expects any
type of Ethernet frame.
</synopsis>
<expectation>
<frameExpected>
<ref>EthernetAll</ref>
</frameExpected>
<metadataExpected>
<ref>PHYPortID</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort group="false">
<name>NormalPathOut</name>
<synopsis>
An output port in the EtherMACIn LFB. It outputs
Ethernet packets to downstream LFBs for normal
processing like Ethernet packet classification and
other L3 IP-layer processing.
</synopsis>
<product>
<frameProduced>
<ref>EthernetAll</ref>
</frameProduced>
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<metadataProduced>
<ref>PHYPortID</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort>
<name>L2BridgingPathOut</name>
<synopsis>
An output port in
the EtherMACIn LFB. It outputs Ethernet packets
to downstream LFBs for layer 2 bridging processing.
The port is switched on or off by the
L2BridgingPathEnable flag in the LFB.
</synopsis>
<product>
<frameProduced>
<ref>EthernetAll</ref>
</frameProduced>
<metadataProduced>
<ref>PHYPortID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1" access="read-write">
<name>AdminStatus</name>
<synopsis>
The LFB status administratively requested, which has
the same data type with a port status. Default is in
'Down' status.
</synopsis>
<typeRef>PortStatusType</typeRef>
<defaultValue>2</defaultValue>
</component>
<component componentID="2" access="read-write">
<name>LocalMACAddresses</name>
<synopsis>
Local MAC address(es) of the Ethernet port the LFB
represents.
</synopsis>
<array>
<typeRef>IEEEMAC</typeRef>
</array>
</component>
<component componentID="3" access="read-write">
<name>L2BridgingPathEnable</name>
<synopsis>
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A flag indicating if the LFB L2 BridgingPath output
port is enabled or not. Default is not enabled.
</synopsis>
<typeRef>boolean</typeRef>
<defaultValue>false</defaultValue>
</component>
<component componentID="4" access="read-write">
<name>PromiscuousMode</name>
<synopsis>
A flag indicating whether the LFB is in promiscuous
mode or not. Default is not.
</synopsis>
<typeRef>boolean</typeRef>
<defaultValue>false</defaultValue>
</component>
<component componentID="5" access="read-write">
<name>TxFlowControl</name>
<synopsis>
A flag indicating whether transmit flow control is
applied or not. Default is not.
</synopsis>
<optional/>
<typeRef>boolean</typeRef>
<defaultValue>false</defaultValue>
</component>
<component componentID="6" access="read-write">
<name>RxFlowControl</name>
<synopsis>
A flag indicating whether receive flow control is
applied or not. Default is not.
</synopsis>
<optional/>
<typeRef>boolean</typeRef>
<defaultValue>false</defaultValue>
</component>
<component componentID="7" access="read-reset">
<name>MACInStats</name>
<synopsis>
The statistics of the EtherMACIn LFB
</synopsis>
<optional/>
<typeRef>MACInStatsType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="5">
<name>EtherClassifier</name>
<synopsis>
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EtherClassifier LFB describes the process to decapsulate
Ethernet packets and then classify them into various
network-layer packets according to information in the
Ethernet headers. It is expected the LFB classifies packets
by packet types like IPv4, IPv6, MPLS, ARP, ND, etc.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort>
<name>EtherPktsIn</name>
<synopsis>
Input port of Ethernet packets. PHYPortID metadata is
always expected while LogicalPortID metadata is
optionally expected to associate with every input
Ethernet packet.
</synopsis>
<expectation>
<frameExpected>
<ref>EthernetAll</ref>
</frameExpected>
<metadataExpected>
<ref>PHYPortID</ref>
<ref dependency="optional" defaultValue="0">
LogicalPortID</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort group="true">
<name>ClassifyOut</name>
<synopsis>
A group port for output of Ethernet classifying
results.
</synopsis>
<product>
<frameProduced>
<ref>Arbitrary</ref>
</frameProduced>
<metadataProduced>
<ref>PHYPortID</ref>
<ref>SrcMAC</ref>
<ref>DstMAC</ref>
<ref>EtherType</ref>
<ref availability="conditional">VlanID</ref>
<ref availability="conditional">VlanPriority</ref>
</metadataProduced>
</product>
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</outputPort>
<outputPort group="false">
<name>ExceptionOut</name>
<synopsis>
A singleton port for output of all Ethernet packets
that fail the classifying process. An ExceptionID
metadata indicates the failure reason.
</synopsis>
<product>
<frameProduced>
<ref>Arbitrary</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component access="read-write" componentID="1">
<name>EtherDispatchTable</name>
<synopsis>
An EtherDispatchTable array component that is defined
in the LFB to dispatch every Ethernet packet to output
ports according to logical port ID assigned by the
VlanInputTable in the LFB and Ethernet type in the
Ethernet packet header.
</synopsis>
<typeRef>EtherDispatchTableType</typeRef>
</component>
<component access="read-write" componentID="2">
<name>VlanInputTable</name>
<synopsis>
A VlanInputTable array component that is defined in
the LFB to classify VLAN Ethernet packets. Every input
packet is assigned with a new LogicalPortID according
to the packet's incoming port ID and VLAN ID.
</synopsis>
<typeRef>VlanInputTableType</typeRef>
</component>
<component access="read-reset" componentID="3">
<name>EtherClassifyStats</name>
<synopsis>
A table recording statistics on the Ethernet
classifying process in the LFB.
</synopsis>
<optional/>
<typeRef>EtherClassifyStatsTableType</typeRef>
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</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="6">
<name>EtherEncap</name>
<synopsis>
The EtherEncap LFB abstracts the process of encapsulating
Ethernet headers onto received packets. The encapsulation
is based on passed metadata.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>EncapIn</name>
<synopsis>
An input port receiving IPv4 and/or IPv6 packets for
encapsulation. A MediaEncapInfoIndex metadata is
expected, and a VLAN priority metadata is optionally
expected with every input packet.
</synopsis>
<expectation>
<frameExpected>
<ref>IPv4</ref>
<ref>IPv6</ref>
</frameExpected>
<metadataExpected>
<ref>MediaEncapInfoIndex</ref>
<ref dependency="optional" defaultValue="0">
VlanPriority</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort group="false">
<name>SuccessOut</name>
<synopsis>
An output port for packets that have found Ethernet
L2 information and have been successfully encapsulated
into an Ethernet packet. An L2PortID metadata is
produced for every output packet.
</synopsis>
<product>
<frameProduced>
<ref>IPv4</ref>
<ref>IPv6</ref>
</frameProduced>
<metadataProduced>
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<ref>L2PortID</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ExceptionOut</name>
<synopsis>
An output port for packets that fail encapsulation
in the LFB. An ExceptionID metadata indicates failure
reason.
</synopsis>
<product>
<frameProduced>
<ref>IPv4</ref>
<ref>IPv6</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
<ref>MediaEncapInfoIndex</ref>
<ref availability="conditional">VlanPriority</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1" access="read-write">
<name>EncapTable</name>
<synopsis>
An array table for Ethernet encapsulation information
lookup. Each row of the array contains destination MAC
address, source MAC address, VLAN ID, and output
logical L2 port ID.
</synopsis>
<typeRef>EncapTableType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="7">
<name>EtherMACOut</name>
<synopsis>
EtherMACOut LFB abstracts an Ethernet port at MAC data link
layer. It specifically describes Ethernet packet process
for output to physical port. A downstream LFB is usually
an Ethernet physical LFB like EtherPHYCop LFB. Note that
Ethernet output functions are closely related to Ethernet
input functions; therefore, some components defined in this
LFB are aliases of EtherMACIn LFB components.
</synopsis>
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<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>EtherPktsIn</name>
<synopsis>
The input port of the EtherMACOut LFB. It expects
any type of Ethernet frame.
</synopsis>
<expectation>
<frameExpected>
<ref>EthernetAll</ref>
</frameExpected>
<metadataExpected>
<ref>PHYPortID</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort group="false">
<name>EtherPktsOut</name>
<synopsis>
A port to output all Ethernet packets, each with a
metadata indicating the ID of the physical port
that the packet is to go through.
</synopsis>
<product>
<frameProduced>
<ref>EthernetAll</ref>
</frameProduced>
<metadataProduced>
<ref>PHYPortID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1" access="read-write">
<name>AdminStatus</name>
<synopsis>
The LFB status administratively requested, which has
the same data type with a port status. The
component is defined as an alias of AdminStatus
component in EtherMACIn LFB.
</synopsis>
<alias>PortStatusType</alias>
</component>
<component componentID="2" access="read-write">
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<name>MTU</name>
<synopsis>Maximum transmission unit (MTU) </synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="3" access="read-write">
<name>TxFlowControl</name>
<synopsis>
A flag indicating whether transmit flow control is
applied, defined as an alias of TxFlowControl
component in EtherMACIn LFB.
</synopsis>
<optional/>
<alias>boolean</alias>
</component>
<component componentID="4" access="read-write">
<name>RxFlowControl</name>
<synopsis>
A flag indicating whether receive flow control is
applied, defined as an alias of RxFlowControl
component in EtherMACIn LFB.
</synopsis>
<optional/>
<alias>boolean</alias>
</component>
<component componentID="5" access="read-reset">
<name>MACOutStats</name>
<synopsis>
The statistics of the EtherMACOut LFB
</synopsis>
<optional/>
<typeRef>MACOutStatsType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="8">
<name>IPv4Validator</name>
<synopsis>
This LFB performs IPv4 validation according to RFC 1812 and
its updates. The IPv4 packet will be output to the
corresponding LFB port, indicating whether the packet is
unicast or multicast or whether an exception has occurred
or the validation failed.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort>
<name>ValidatePktsIn</name>
<synopsis>
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Input port for data packets to be validated
</synopsis>
<expectation>
<frameExpected>
<ref>Arbitrary</ref>
</frameExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort>
<name>IPv4UnicastOut</name>
<synopsis>
Output port for validated IPv4 unicast packets
</synopsis>
<product>
<frameProduced>
<ref>IPv4Unicast</ref>
</frameProduced>
</product>
</outputPort>
<outputPort>
<name>IPv4MulticastOut</name>
<synopsis>
Output port for validated IPv4 multicast packets
</synopsis>
<product>
<frameProduced>
<ref>IPv4Multicast</ref>
</frameProduced>
</product>
</outputPort>
<outputPort>
<name>ExceptionOut</name>
<synopsis>
Output port for all packets with exceptional cases
when validating. An ExceptionID metadata indicates
the exception case type.
</synopsis>
<product>
<frameProduced>
<ref>IPv4</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
</metadataProduced>
</product>
</outputPort>
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<outputPort>
<name>FailOut</name>
<synopsis>
Output port for packets that failed validating
process. A ValidateErrorID metadata indicates the
error type or failure reason.
</synopsis>
<product>
<frameProduced>
<ref>IPv4</ref>
</frameProduced>
<metadataProduced>
<ref>ValidateErrorID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component access="read-write" componentID="1">
<name>IPv4ValidatorStats</name>
<synopsis>
The statistics information for validating process in
the LFB.
</synopsis>
<optional/>
<typeRef>IPv4ValidatorStatsType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="9">
<name>IPv6Validator</name>
<synopsis>
This LFB performs IPv6 validation according to RFC 2460 and
its updates. Then, the IPv6 packet will be output to the
corresponding port, indicating whether the packet is
unicast or multicast or whether an exception has occurred
or the validation failed.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort>
<name>ValidatePktsIn</name>
<synopsis>
Input port for data packets to be validated
</synopsis>
<expectation>
<frameExpected>
<ref>Arbitrary</ref>
Wang, et al. Standards Track [Page 83]
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</frameExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort>
<name>IPv6UnicastOut</name>
<synopsis>
Output port for validated IPv6 unicast packets
</synopsis>
<product>
<frameProduced>
<ref>IPv6Unicast</ref>
</frameProduced>
</product>
</outputPort>
<outputPort>
<name>IPv6MulticastOut</name>
<synopsis>
Output port for validated IPv6 multicast packets
</synopsis>
<product>
<frameProduced>
<ref>IPv6Multicast</ref>
</frameProduced>
</product>
</outputPort>
<outputPort>
<name>ExceptionOut</name>
<synopsis>
Output port for packets with exceptional cases when
validating. An ExceptionID metadata indicates the
exception case type.
</synopsis>
<product>
<frameProduced>
<ref>IPv6</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort>
<name>FailOut</name>
<synopsis>
Output port for packets failed validating process.
A ValidateErrorID metadata indicates the error type
Wang, et al. Standards Track [Page 84]
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or failure reason.
</synopsis>
<product>
<frameProduced>
<ref>IPv6</ref>
</frameProduced>
<metadataProduced>
<ref>ValidateErrorID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component access="read-write" componentID="1">
<name>IPv6ValidatorStats</name>
<synopsis>
The statistics information for validating process in
the LFB.
</synopsis>
<optional/>
<typeRef>IPv6ValidatorStatsType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="10">
<name>IPv4UcastLPM</name>
<synopsis>
The IPv4UcastLPM LFB abstracts the IPv4 unicast Longest
Prefix Match (LPM) process. This LFB supports
implementing equal-cost multipath (ECMP) routing and
reverse path forwarding (RPF).
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>PktsIn</name>
<synopsis>
A port for input of packets to be processed.
IPv4 unicast packets are expected.
</synopsis>
<expectation>
<frameExpected>
<ref>IPv4Unicast</ref>
</frameExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
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<outputPort group="false">
<name>NormalOut</name>
<synopsis>
An output port to output IPv4 unicast packets that
successfully passed the LPM lookup. A HopSelector
metadata is produced to associate every output packet
for downstream LFB to do next-hop action.
</synopsis>
<product>
<frameProduced>
<ref>IPv4Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>HopSelector</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ECMPOut</name>
<synopsis>
The port to output packets needing further ECMP
processing. A downstream ECMP processing LFB is
usually followed to the port. If ECMP is not
required, no downstream LFB may be connected to
the port.
</synopsis>
<product>
<frameProduced>
<ref>IPv4Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>HopSelector</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ExceptionOut</name>
<synopsis>
The port to output all packets with exceptional cases
happened during LPM process. An ExceptionID metadata
is associated to indicate what caused the exception.
</synopsis>
<product>
<frameProduced>
<ref>IPv4Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
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</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1" access="read-write">
<name>IPv4PrefixTable</name>
<synopsis>
A table for IPv4 Longest Prefix Match(LPM). The
destination IPv4 address of every input packet is
used as a search key to look up the table to find
out a next-hop selector.
</synopsis>
<typeRef>IPv4PrefixTableType</typeRef>
</component>
<component componentID="2" access="read-reset">
<name>IPv4UcastLPMStats</name>
<synopsis>
The statistics information for the IPv4 unicast LPM
process in the LFB.
</synopsis>
<optional/>
<typeRef>IPv4UcastLPMStatsType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="11">
<name>IPv6UcastLPM</name>
<synopsis>
The IPv6UcastLPM LFB abstracts the IPv6 unicast Longest
Prefix Match (LPM) process. This LFB supports
implementing equal-cost multipath (ECMP) routing and
reverse path forwarding (RPF).
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>PktsIn</name>
<synopsis>
A port for input of packets to be processed.
IPv6 unicast packets are expected.
</synopsis>
<expectation>
<frameExpected>
<ref>IPv6Unicast</ref>
</frameExpected>
</expectation>
</inputPort>
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</inputPorts>
<outputPorts>
<outputPort group="false">
<name>NormalOut</name>
<synopsis>
An output port to output IPv6 unicast packets that
successfully passed the LPM lookup. A HopSelector
metadata is produced to associate every output packet
for downstream LFB to do next-hop action.
</synopsis>
<product>
<frameProduced>
<ref>IPv6Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>HopSelector</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ECMPOut</name>
<synopsis>
The port to output packets needing further ECMP
processing. A downstream ECMP processing LFB is
usually followed to the port. If ECMP is not
required, no downstream LFB may be connected to
the port.
</synopsis>
<product>
<frameProduced>
<ref>IPv6Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>HopSelector</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ExceptionOut</name>
<synopsis>
The port to output all packets with exceptional cases
happened during LPM process. An ExceptionID metadata
is associated to indicate what caused the exception.
</synopsis>
<product>
<frameProduced>
<ref>IPv6Unicast</ref>
</frameProduced>
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<metadataProduced>
<ref>ExceptionID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1" access="read-write">
<name>IPv6PrefixTable</name>
<synopsis>
A table for IPv6 Longest Prefix Match (LPM). The
destination IPv6 address of every input packet is
used as a search key to look up the table to find
out a next-hop selector.
</synopsis>
<typeRef>IPv6PrefixTableType</typeRef>
</component>
<component componentID="2" access="read-reset">
<name>IPv6UcastLPMStats</name>
<synopsis>
The statistics information for the IPv6 unicast LPM
process in the LFB.
</synopsis>
<optional/>
<typeRef>IPv6UcastLPMStatsType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="12">
<name>IPv4NextHop</name>
<synopsis>
The IPv4NextHop LFB abstracts the process of next-hop
information application to IPv4 packets. It receives an
IPv4 packet with an associated next-hop identifier
(HopSelector) and uses the identifier as a table index
to look up a next-hop table to find an appropriate output
port. The data processing also involves the forwarding
TTL decrement and IP checksum recalculation.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>PktsIn</name>
<synopsis>
A port for input of unicast IPv4 packets, along with
a HopSelector metadata.
</synopsis>
<expectation>
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<frameExpected>
<ref>IPv4Unicast</ref>
</frameExpected>
<metadataExpected>
<ref>HopSelector</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort group="true">
<name>SuccessOut</name>
<synopsis>
The group port for output of packets that
successfully found next-hop information. Some
metadata are associated with every packet.
</synopsis>
<product>
<frameProduced>
<ref>IPv4Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>L3PortID</ref>
<ref>NextHopIPv4Addr</ref>
<ref availability="conditional">
MediaEncapInfoIndex</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ExceptionOut</name>
<synopsis>
The output port for packets with exceptional or
failure cases. An ExceptionID metadata indicates
what caused the case.
</synopsis>
<product>
<frameProduced>
<ref>IPv4Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1">
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<name>IPv4NextHopTable</name>
<synopsis>
The IPv4NextHopTable component. A
HopSelector is used to match the table index
to find out a row that contains the next-hop
information result.
</synopsis>
<typeRef>IPv4NextHopTableType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="13">
<name>IPv6NextHop</name>
<synopsis>
The LFB abstracts the process of next-hop information
application to IPv6 packets. It receives an IPv6 packet
with an associated next-hop identifier (HopSelector) and
uses the identifier as a table index to look up a next-hop
table to find an appropriate output port.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>PktsIn</name>
<synopsis>
A port for input of unicast IPv6 packets, along with
a HopSelector metadata.
</synopsis>
<expectation>
<frameExpected>
<ref>IPv6Unicast</ref>
</frameExpected>
<metadataExpected>
<ref>HopSelector</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort group="true">
<name>SuccessOut</name>
<synopsis>
The group port for output of packets that successfully
found next-hop information. Some metadata are
associated with every packet.
</synopsis>
<product>
<frameProduced>
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<ref>IPv6Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>L3PortID</ref>
<ref>NextHopIPv6Addr</ref>
<ref availability="conditional">
MediaEncapInfoIndex</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ExceptionOut</name>
<synopsis>
The output port for packets with exceptional or
failure cases. An ExceptionID metadata indicates
what caused the case.
</synopsis>
<product>
<frameProduced>
<ref>IPv6Unicast</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1">
<name>IPv6NextHopTable</name>
<synopsis>
The IPv6NextHopTable component. A HopSelector is
used to match the table index to find out a row that
contains the next-hop information result.
</synopsis>
<typeRef>IPv6NextHopTableType</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="14">
<name>RedirectIn</name>
<synopsis>
The RedirectIn LFB abstracts the process for the ForCES CE to
inject data packets into the ForCES FE LFBs.
</synopsis>
<version>1.0</version>
<outputPorts>
<outputPort group="true">
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<name>PktsOut</name>
<synopsis>
The output port of RedirectIn LFB, which is defined as
a group port type. From the LFB topology's point of
view, the RedirectIn LFB acts as a source point for
data packets coming from CE; therefore, the LFB is
defined with a singleton output port (and no input
port).
</synopsis>
<product>
<frameProduced>
<ref>Arbitrary</ref>
</frameProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component componentID="1">
<name>NumPacketsReceived</name>
<synopsis>
Number of packets received from CE.
</synopsis>
<optional/>
<typeRef>uint64</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="15">
<name>RedirectOut</name>
<synopsis>
The RedirectOut LFB abstracts the process for LFBs in a
ForCES FE to deliver data packets to the ForCES CE.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="false">
<name>PktsIn</name>
<synopsis>
The input port for the RedirectOut LFB. From the LFB
topology's point of view, the RedirectOut LFB acts as
a sink point for data packets going to the CE;
therefore, RedirectOut LFB is defined with a
singleton input port (and no output port).
</synopsis>
<expectation>
<frameExpected>
<ref>Arbitrary</ref>
</frameExpected>
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</expectation>
</inputPort>
</inputPorts>
<components>
<component componentID="1">
<name>NumPacketsSent</name>
<synopsis>
Number of packets sent to CE.
</synopsis>
<optional/>
<typeRef>uint64</typeRef>
</component>
</components>
</LFBClassDef>
<LFBClassDef LFBClassID="16">
<name>BasicMetadataDispatch</name>
<synopsis>
The BasicMetadataDispatch LFB is defined to abstract the
process by which packets are dispatched to various output
paths based on associated metadata value. Current
version of the LFB only allows the metadata value to be
a 32-bit integer.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort>
<name>PktsIn</name>
<synopsis>
The packet input port for dispatching. Every input
packet should be associated with a metadata that will
be used by the LFB to do the dispatch.
</synopsis>
<expectation>
<frameExpected>
<ref>Arbitrary</ref>
</frameExpected>
<metadataExpected>
<ref>Arbitrary</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort group="true">
<name>PktsOut</name>
<synopsis>
The group output port that outputs dispatching
results. A packet with its associated metadata
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having found an OutputIndex by successfully looking
up the dispatch table will be output to the group
port instance with the corresponding index.
</synopsis>
<product>
<frameProduced>
<ref>Arbitrary</ref>
</frameProduced>
</product>
</outputPort>
<outputPort group="false">
<name>ExceptionOut</name>
<synopsis>
The output port that outputs packets that failed
to process. An ExceptionID metadata indicates what
caused the exception.
</synopsis>
<product>
<frameProduced>
<ref>Arbitrary</ref>
</frameProduced>
<metadataProduced>
<ref>ExceptionID</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component access="read-write" componentID="1">
<name>MetadataID</name>
<synopsis>
The ID of the metadata to be
used for dispatching packets.
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component access="read-write" componentID="2">
<name>MetadataDispatchTable</name>
<synopsis>
The MetadataDispatchTable component, which contains
entries of a metadata value and an output index,
specifying that a packet with the metadata value must
go out from the instance with the output index of the
LFB group output port.
</synopsis>
<typeRef>MetadataDispatchTableType</typeRef>
</component>
</components>
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</LFBClassDef>
<LFBClassDef LFBClassID="17">
<name>GenericScheduler</name>
<synopsis>
This is a preliminary generic scheduler LFB abstracting
a simple scheduling process, which may be used as a
basic LFB to construct a more complex scheduler LFB.
</synopsis>
<version>1.0</version>
<inputPorts>
<inputPort group="true">
<name>PktsIn</name>
<synopsis>
The group input port of the LFB. Inside the LFB,
each instance of the group port is connected to
a queue marked with a queue ID, whose value is
index of the port instance.
</synopsis>
<expectation>
<frameExpected>
<ref>Arbitrary</ref>
</frameExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort>
<name>PktsOut</name>
<synopsis>
The output port of the LFB. Scheduled packets are
output from the port.
</synopsis>
<product>
<frameProduced>
<ref>Arbitrary</ref>
</frameProduced>
</product>
</outputPort>
</outputPorts>
<components>
<component access="read-write" componentID="1">
<name>SchedulingDiscipline</name>
<synopsis>
The SchedulingDiscipline component, which is for the
CE to specify a scheduling discipline to the LFB.
</synopsis>
<typeRef>SchdDisciplineType</typeRef>
<defaultValue>1</defaultValue>
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</component>
<component access="read-only" componentID="2">
<name>QueueStats</name>
<synopsis>
The QueueStats component, which is defined to allow
the CE to query every queue statistics in the
scheduler.
</synopsis>
<optional/>
<typeRef>QueueStatsTableType</typeRef>
</component>
</components>
<capabilities>
<capability componentID="30">
<name>QueueLenLimit</name>
<synopsis>
The QueueLenLimit capability, which specifies
maximum length of each queue. The length unit is in
bytes.
</synopsis>
<typeRef>uint32</typeRef>
</capability>
</capabilities>
</LFBClassDef>
</LFBClassDefs>
</LFBLibrary>
7. LFB Class Use Cases
This section demonstrates examples on how the LFB classes defined by
the base LFB library in Section 6 can be applied to achieve some
typical router functions. The functions demonstrated are:
o IPv4 forwarding
o ARP processing
It is assumed the LFB topology on the FE described has already been
established by the CE and maps to the use cases illustrated in this
section.
The use cases demonstrated in this section are mere examples and by
no means should be treated as the only way one would construct router
functionality from LFBs; based on the capability of the FE(s), a CE
should be able to express different NE applications.
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7.1. IPv4 Forwarding
Figure 2 shows the typical LFB processing path for an IPv4 unicast
forwarding case with Ethernet media interfaces by use of the base LFB
classes. Note that in the figure, to focus on the IP forwarding
function, some inputs or outputs of LFBs that are not related to the
IPv4 forwarding function are not shown. For example, an
EtherClassifier LFB normally has two output ports: a "ClassifyOut"
group output port and an "ExceptionOut" singleton output port, with
the group port containing various port instances according to various
classified packet types (Section 5.1.3). In this figure, only the
IPv4 and IPv6 packet output port instances are shown for displaying
the mere IPv4 forwarding processing function.
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+-----+ +------+
| | | |
| |<---------------|Ether |<----------------------------+
| | |MACOut| |
| | | | |
|Ether| +------+ |
|PHY | |
|Cop | +---+ |
|#1 | +-----+ | |----->IPv6 Packets |
| | | | | | |
| | |Ether| | | IPv4 Packets |
| |->|MACIn|-->| |-+ +----+ |
+-----+ | | | | | | |---> Multicast Packets |
+-----+ +---+ | | | +-----+ +---+ |
Ether +->| |------->| | | | |
. Classifier| | |Unicast |IPv4 | | | |
. | | |Packets |Ucast|->| |--+ |
. | +----+ |LPM | | | | |
+---+ | IPv4 +-----+ +---+ | |
+-----+ | | | Validator IPv4 | |
| | | | | NextHop| |
+-----+ |Ether| | |-+ IPv4 Packets | |
| |->|MACIn|-->| | | |
| | | | | |----->IPv6 Packets | |
|Ether| +-----+ +---+ | |
|PHY | Ether +----+ | |
|Cop | Classifier | | +-------+ | |
|#n | +------+ | | |Ether | | |
| | | | | |<--|Encap |<-+ |
| | | |<------| | | | |
| |<---------------|Ether | ...| | +-------+ |
| | |MACOut| +---| | |
| | | | | +----+ |
+-----+ +------+ | BasicMetadataDispatch |
+----------->-------------+
Figure 2: LFB Use Case for IPv4 Forwarding
In the LFB use case, a number of EtherPHYCop LFB (Section 5.1.1)
instances are used to describe physical-layer functions of the ports.
PHYPortID metadata is generated by the EtherPHYCop LFB and is used by
all the subsequent downstream LFBs. An EtherMACIn LFB
(Section 5.1.2), which describes the MAC-layer processing, follows
every EtherPHYCop LFB. The EtherMACIn LFB may do a locality check of
MAC addresses if the CE configures the appropriate EtherMACIn LFB
component.
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Ethernet packets out of the EtherMACIn LFB are sent to an
EtherClassifier LFB (Section 5.1.3) to be decapsulated and classified
into network-layer types like IPv4, IPv6, ARP, etc. In the example
use case, every physical Ethernet interface is associated with one
Classifier instance; although not illustrated, it is also feasible
that all physical interfaces are associated with only one Ethernet
Classifier instance.
EtherClassifier uses the PHYPortID metadata, the Ethernet type of the
input packet, and VlanID (if present in the input Ethernet packets)
to decide the packet network-layer type and the LFB output port to
the downstream LFB. The EtherClassifier LFB also assigns a new
logical port ID metadata to the packet for later use. The
EtherClassifier may also generate some new metadata for every packet,
like EtherType, SrcMAC, DstMAC, LogicPortID, etc., for consumption by
downstream LFBs.
If a packet is classified as an IPv4 packet, it is sent downstream to
an IPv4Validator LFB (Section 5.2.1) to validate the IPv4 packet. In
the validator LFB, IPv4 packets are validated and are additionally
classified into either IPv4 unicast packets or multicast packets.
IPv4 unicast packets are sent to downstream to the IPv4UcastLPM LFB
(Section 5.3.1).
The IPv4UcastLPM LFB is where the longest prefix match decision is
made, and a next-hop selection is selected. The next-hop ID metadata
is generated by the IPv4UcastLPM LFB to be consumed downstream by the
IPv4NextHop LFB (Section 5.3.2).
The IPv4NextHop LFB uses the next-hop ID metadata to derive where the
packet is to go next and the media encapsulation type for the port,
etc. The IPv4NextHop LFB generates the L3PortID metadata used to
identify a next-hop output physical/logical port. In the example use
case, the next-hop output port is an Ethernet type; as a result, the
packet and its L3 port ID metadata are sent downstream to an
EtherEncap LFB (Section 5.1.4).
The EtherEncap LFB encapsulates the incoming packet into an Ethernet
frame. A BasicMetadataDispatch LFB (Section 5.5.1) follows the
EtherEncap LFB. The BasicMetadataDispatch LFB is where packets are
finally dispatched to different output physical/logical ports based
on the L3PortID metadata sent to the LFB.
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7.2. ARP Processing
Figure 3 shows the processing path for the Address Resolution
Protocol (ARP) in the case the CE implements the ARP processing
function. By no means is this the only way ARP processing could be
achieved; as an example, ARP processing could happen at the FE, but
that discussion is out of the scope of this use case.
+---+ +---+
| | ARP packets | |
| |-------------->---------+--->| | To CE
...-->| | . | | |
| | . | +---+
| | . | RedirectOut
+---+ ^
Ether EtherEncap | IPv4 packets lack
Classifier +---+ | address resolution information
| | |
Packets need | |--------->---+
...--------->| |
L2 Encapsulation| |
+---+ | | +------+
| | +-->| |--+ +---+ |Ether |
| | | +---+ | | |--------->|MACOut|-->...
From CE| |--+ +-->| | . +------+
| |ARP Packets | | .
| |from CE | | . +------+
| | | |--------> |Ether |-->...
+---+ +---+ |MACOut|
RedirectIn BasicMetadata +------+
Dispatch
Figure 3: LFB Use Case for ARP
There are two ways ARP processing could be triggered in the CE as
illustrated in Figure 3:
o ARP packets arriving from outside of the NE.
o IPV4 packets failing to resolve within the FE.
ARP packets from network interfaces are filtered out by
EtherClassifier LFB. The classified ARP packets and associated
metadata are then sent downstream to the RedirectOut LFB
(Section 5.4.2) to be transported to CE.
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The EtherEncap LFB, as described in Section 5.1.4, receives packets
that need Ethernet L2 encapsulating. When the EtherEncap LFB fails
to find the necessary L2 Ethernet information with which to
encapsulate the packet, it outputs the packet to its ExceptionOut LFB
port. Downstream to EtherEncap LFB's ExceptionOut LFB port is the
RedirectOut LFB, which transports the packet to the CE (see
Section 5.1.4 on EtherEncap LFB for details).
To achieve its goal, the CE needs to generate ARP request and
response packets and send them to external (to the NE) networks. ARP
request and response packets from the CE are redirected to an FE via
a RedirectIn LFB (Section 5.4.1).
As was the case with forwarded IPv4 packets, outgoing ARP packets are
also encapsulated to Ethernet format by the EtherEncap LFB, and then
dispatched to different interfaces via a BasicMetadataDispatch LFB.
The BasicMetadataDispatch LFB dispatches the packets according to the
L3PortID metadata included in every ARP packet sent from CE.
8. IANA Considerations
IANA has created a registry of ForCES LFB class names and the
corresponding ForCES LFB class identifiers, with the location of the
definition of the ForCES LFB class, in accordance with the rules to
use the namespace.
This document registers the unique class names and numeric class
identifiers for the LFBs listed in Section 8.1. Besides, this
document defines the following namespaces:
o Metadata ID, defined in Sections 4.3 and 4.4
o Exception ID, defined in Section 4.4
o Validate Error ID, defined in Section 4.4
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8.1. LFB Class Names and LFB Class Identifiers
LFB classes defined by this document belong to LFBs defined by
Standards Track RFCs. According to IANA, the registration procedure
is Standards Action for the range 0 to 65535 and First Come First
Served with any publicly available specification for over 65535.
The assignment of LFB class names and LFB class identifiers is as in
the following table.
+----------+--------------- +------------------------+--------------+
|LFB Class | LFB Class Name | Description | Reference |
|Identifier| | | |
+----------+--------------- +------------------------+--------------+
| 3 | EtherPHYCop | Define an Ethernet port| RFC 6956, |
| | | abstracted at physical | Section 5.1.1|
| | | layer. | |
| | | | |
| 4 | EtherMACIn | Define an Ethernet | RFC 6956, |
| | | input port at MAC data | Section 5.1.2|
| | | link layer. | |
| | | | |
| 5 |EtherClassifier | Define the process to | RFC 6956, |
| | | decapsulate Ethernet | Section 5.1.3|
| | | packets and classify | |
| | | the packets. | |
| | | | |
| 6 | EtherEncap | Define the process to | RFC 6956, |
| | | encapsulate IP packets | Section 5.1.4|
| | | to Ethernet packets. | |
| | | | |
| 7 | EtherMACOut | Define an Ethernet | RFC 6956 |
| | | output port at MAC | Section 5.1.5|
| | | data link layer. | |
| | | | |
| 8 | IPv4Validator | Perform IPv4 packets | RFC 6956, |
| | | validation. | Section 5.2.1|
| | | | |
| 9 | IPv6Validator | Perform IPv6 packets | RFC 6956, |
| | | validation. | Section 5.2.2|
| | | | |
| 10 | IPv4UcastLPM | Perform IPv4 Longest | RFC 6956, |
| | | Prefix Match Lookup. | Section 5.3.1|
| | | | |
| 11 | IPv6UcastLPM | Perform IPv6 Longest | RFC 6956, |
| | | Prefix Match Lookup. | Section 5.3.3|
| | | | |
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| 12 | IPv4NextHop | Define the process of | RFC 6956, |
| | | selecting IPv4 next-hop| Section 5.3.2|
| | | action. | |
| | | | |
| 13 | IPv6NextHop | Define the process of | RFC 6956, |
| | | selecting IPv6 next-hop| Section 5.3.4|
| | | action. | |
| | | | |
| 14 | RedirectIn | Define the process for | RFC 6956, |
| | | CE to inject data | Section 5.4.1|
| | | packets into FE LFB | |
| | | topology. | |
| | | | |
| 15 | RedirectOut | Define the process for | RFC 6956, |
| | | LFBs in FE to deliver | Section 5.4.2|
| | | data packets to CE. | |
| | | | |
| 16 | BasicMetadata | Dispatch input packets | RFC 6956, |
| | Dispatch | to a group output | Section 5.5.1|
| | | according to a metadata| |
| | | | |
| 17 |GenericScheduler| Define a preliminary | RFC 6956, |
| | | generic scheduling | Section 5.5.2|
| | | process. | |
+----------+--------------- +------------------------+--------------+
Table 1
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8.2. Metadata ID
The Metadata ID namespace is 32 bits long. Below are the guidelines
for managing the namespace.
Metadata IDs in the range of 0x00000001-0x7FFFFFFF are Specification
Required [RFC5226]. A metadata ID using this range MUST be
documented in an RFC or other permanent and readily available
reference.
Values assigned by this specification:
+--------------+-------------------------+--------------------------+
| Value | Name | Definition |
+--------------+-------------------------+--------------------------+
| 0x00000000 | Reserved | RFC 6956 |
| 0x00000001 | PHYPortID | RFC 6956, Section 4.4 |
| 0x00000002 | SrcMAC | RFC 6956, Section 4.4 |
| 0x00000003 | DstMAC | RFC 6956, Section 4.4 |
| 0x00000004 | LogicalPortID | RFC 6956, Section 4.4 |
| 0x00000005 | EtherType | RFC 6956, Section 4.4 |
| 0x00000006 | VlanID | RFC 6956, Section 4.4 |
| 0x00000007 | VlanPriority | RFC 6956, Section 4.4 |
| 0x00000008 | NextHopIPv4Addr | RFC 6956, Section 4.4 |
| 0x00000009 | NextHopIPv6Addr | RFC 6956, Section 4.4 |
| 0x0000000A | HopSelector | RFC 6956, Section 4.4 |
| 0x0000000B | ExceptionID | RFC 6956, Section 4.4 |
| 0x0000000C | ValidateErrorID | RFC 6956, Section 4.4 |
| 0x0000000D | L3PortID | RFC 6956, Section 4.4 |
| 0x0000000E | RedirectIndex | RFC 6956, Section 4.4 |
| 0x0000000F | MediaEncapInfoIndex | RFC 6956, Section 4.4 |
| 0x80000000- | Reserved for | RFC 6956 |
| 0xFFFFFFFF | Private Use | |
+--------------+-------------------------+--------------------------+
Table 2
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8.3. Exception ID
The Exception ID namespace is 32 bits long. Below are the guidelines
for managing the namespace.
Exception IDs in the range of 0x00000000-0x7FFFFFFF are Specification
Required [RFC5226]. An exception ID using this range MUST be
documented in an RFC or other permanent and readily available
reference.
Values assigned by this specification:
+--------------+---------------------------------+------------------+
| Value | Name | Definition |
+--------------+---------------------------------+------------------+
| 0x00000000 | AnyUnrecognizedExceptionCase | See Section 4.4 |
| 0x00000001 | ClassifyNoMatching | See Section 4.4 |
| 0x00000002 | MediaEncapInfoIndexInvalid | See Section 4.4 |
| 0x00000003 | EncapTableLookupFailed | See Section 4.4 |
| 0x00000004 | BadTTL | See Section 4.4 |
| 0x00000005 | IPv4HeaderLengthMismatch | See Section 4.4 |
| 0x00000006 | RouterAlertOptions | See Section 4.4 |
| 0x00000007 | IPv6HopLimitZero | See Section 4.4 |
| 0x00000008 | IPv6NextHeaderHBH | See Section 4.4 |
| 0x00000009 | SrcAddressException | See Section 4.4 |
| 0x0000000A | DstAddressException | See Section 4.4 |
| 0x0000000B | LPMLookupFailed | See Section 4.4 |
| 0x0000000C | HopSelectorInvalid | See Section 4.4 |
| 0x0000000D | NextHopLookupFailed | See Section 4.4 |
| 0x0000000E | FragRequired | See Section 4.4 |
| 0x0000000F | MetadataNoMatching | See Section 4.4 |
| 0x80000000- | Reserved for | RFC 6956 |
| 0xFFFFFFFF | Private Use | |
+--------------+---------------------------------+------------------+
Table 3
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8.4. Validate Error ID
The Validate Error ID namespace is 32 bits long. Below are the
guidelines for managing the namespace.
Validate Error IDs in the range of 0x00000000-0x7FFFFFFF are
Specification Required [RFC5226]. A Validate Error ID using this
range MUST be documented in an RFC or other permanent and readily
available reference.
Values assigned by this specification:
+--------------+---------------------------------+------------------+
| Value | Name | Definition |
+--------------+---------------------------------+------------------+
| 0x00000000 | AnyUnrecognizedValidateErrorCase| See Section 4.4 |
| 0x00000001 | InvalidIPv4PacketSize | See Section 4.4 |
| 0x00000002 | NotIPv4Packet | See Section 4.4 |
| 0x00000003 | InvalidIPv4HeaderLengthSize | See Section 4.4 |
| 0x00000004 | InvalidIPv4LengthFieldSize | See Section 4.4 |
| 0x00000005 | InvalidIPv4Checksum | See Section 4.4 |
| 0x00000006 | InvalidIPv4SrcAddr | See Section 4.4 |
| 0x00000007 | InvalidIPv4DstAddr | See Section 4.4 |
| 0x00000008 | InvalidIPv6PacketSize | See Section 4.4 |
| 0x00000009 | NotIPv6Packet | See Section 4.4 |
| 0x0000000A | InvalidIPv6SrcAddr | See Section 4.4 |
| 0x0000000B | InvalidIPv6DstAddr | See Section 4.4 |
| 0x80000000- | Reserved for | RFC 6956 |
| 0xFFFFFFFF | Private Use | |
+--------------+---------------------------------+------------------+
Table 4
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9. Security Considerations
The ForCES framework document [RFC3746] provides a description of the
security needs for the overall ForCES architecture. For example, the
ForCES protocol entities must be authenticated per the ForCES
requirements before they can access the information elements
described in this document via ForCES. The ForCES protocol document
[RFC5810] includes a comprehensive set of security mechanisms that
implementations are required to support to meet these needs. SCTP-
based Transport Mapping Layer (TML) for the ForCES protocol [RFC5811]
specifies security mechanisms for transport mapping for the ForCES
protocol. The LFBs defined in this document are similar to other
LFBs modeled by the FE model [RFC5812]. In particular, they have the
same security properties. Thus, the security mechanisms and
considerations from the ForCES protocol document [RFC5810] apply to
this document.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H.,
Wang, W., Dong, L., Gopal, R., and J. Halpern,
"Forwarding and Control Element Separation (ForCES)
Protocol Specification", RFC 5810, March 2010.
[RFC5811] Hadi Salim, J. and K. Ogawa, "SCTP-Based Transport
Mapping Layer (TML) for the Forwarding and Control
Element Separation (ForCES) Protocol", RFC 5811,
March 2010.
[RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control
Element Separation (ForCES) Forwarding Element Model",
RFC 5812, March 2010.
10.2. Informative References
[IEEE.802-1Q] IEEE, "IEEE Standard for Local and metropolitan area
networks -- Media Access Control (MAC) Bridges and
Virtual Bridged Local Area Networks", IEEE Standard
802.1Q, 2011.
[RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989.
Wang, et al. Standards Track [Page 108]
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[RFC1812] Baker, F., "Requirements for IP Version 4 Routers",
RFC 1812, June 1995.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version
6 (IPv6) Specification", RFC 2460, December 1998.
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management
Information Version 2 (SMIv2)", STD 58, RFC 2578,
April 1999.
[RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal,
"Forwarding and Control Element Separation (ForCES)
Framework", RFC 3746, April 2004.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing
an IANA Considerations Section in RFCs", BCP 26,
RFC 5226, May 2008.
Wang, et al. Standards Track [Page 109]
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Appendix A. Acknowledgements
The authors would like to acknowledge the following people, whose
input was particularly helpful during development of this document:
Edward Crabbe
Adrian Farrel
Rong Jin
Bin Zhuge
Ming Gao
Jingjing Zhou
Xiaochun Wu
Derek Atkins
Stephen Farrell
Meral Shirazipour
Jari Arkko
Martin Stiemerling
Stewart Bryant
Richard Barnes
Appendix B. Contributors
The authors would like to thank Jamal Hadi Salim, Ligang Dong, and
Fenggen Jia, all of whom made major contributions to the development
of this document. Ligang Dong and Fenggen Jia were also two of the
authors of earlier documents from which this document evolved.
Jamal Hadi Salim
Mojatatu Networks
Ottawa, Ontario
Canada
EMail: hadi@mojatatu.com
Ligang Dong
Zhejiang Gongshang University
18 Xuezheng Str., Xiasha University Town
Hangzhou 310018
P.R. China
EMail: donglg@zjsu.edu.cn
Fenggen Jia
National Digital Switching Center (NDSC)
Jianxue Road
Zhengzhou 452000
P.R. China
EMail: jfg@mail.ndsc.com.cn
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Authors' Addresses
Weiming Wang
Zhejiang Gongshang University
18 Xuezheng Str., Xiasha University Town
Hangzhou 310018
P.R. China
Phone: +86 571 28877751
EMail: wmwang@zjsu.edu.cn
Evangelos Haleplidis
University of Patras
Department of Electrical & Computer Engineering
Patras 26500
Greece
EMail: ehalep@ece.upatras.gr
Kentaro Ogawa
NTT Corporation
Tokyo
Japan
EMail: ogawa.kentaro@lab.ntt.co.jp
Chuanhuang Li
Hangzhou DPtech
6th Floor, Zhongcai Group, 68 Tonghe Road, Binjiang District
Hangzhou 310051
P.R. China
EMail: chuanhuang_li@zjsu.edu.cn
Joel Halpern
Ericsson
P.O. Box 6049
Leesburg, VA 20178
USA
Phone: +1 703 371 3043
EMail: joel.halpern@ericsson.com
Wang, et al. Standards Track [Page 111]