Internet Engineering Task Force D. Joachimpillai
Internet-Draft Verizon
Intended status: Informational J. Hadi Salim
Expires: June 7, 2015 Mojatatu Networks
December 4, 2014
ForCES Inter-FE LFB
draft-joachimpillai-forces-interfelfb-05
Abstract
Forwarding and Control Element Separation (ForCES) defines an
architectural framework and associated protocols to standardize
information exchange between the control plane and the forwarding
plane in a ForCES Network Element (ForCES NE). RFC5812 has defined
the ForCES Model which provides a formal way to represent the
capabilities, state, and configuration of forwarding elements(FEs)
within the context of the ForCES protocol. More specifically, the
model describes the logical functions that are present in an FE, what
capabilities these functions support, and how these functions are or
can be interconnected. The control elements (CEs) can control the
FEs using the ForCES model definition.
The ForCES WG charter has been extended to allow the LFB topology to
be across FEs. This documents describes a non-intrusive way to
extend the LFB topology across FEs.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 7, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
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document authors. All rights reserved.
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Table of Contents
1. Terminology and Conventions . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem Scope And Use Cases . . . . . . . . . . . . . . . . . 4
3.1. Basic Router . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Distributing The LFB Topology . . . . . . . . . . . . 6
3.2. Arbitray Network Function . . . . . . . . . . . . . . . . 7
3.2.1. Distributing The Arbitray Network Function . . . . . . 8
4. Proposal Overview . . . . . . . . . . . . . . . . . . . . . . 9
4.1. Inserting The Inter-FE LFB . . . . . . . . . . . . . . . . 9
5. Inter-FE connectivity . . . . . . . . . . . . . . . . . . . . 11
5.1. Inter-FE Ethernet connectivity . . . . . . . . . . . . . . 13
5.1.1. Inter-FE Ethernet Connectivity Issues . . . . . . . . 15
6. Detailed Description of the Ethernet inter-FE LFB . . . . . . 15
6.1. Data Handling . . . . . . . . . . . . . . . . . . . . . . 16
6.1.1. Egress Processing . . . . . . . . . . . . . . . . . . 16
6.1.2. Ingress Processing . . . . . . . . . . . . . . . . . . 18
6.2. Metadata . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.3. Components . . . . . . . . . . . . . . . . . . . . . . . . 19
6.4. Inter-FE LFB XML Model . . . . . . . . . . . . . . . . . . 19
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
9. Security Considerations . . . . . . . . . . . . . . . . . . . 22
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
10.1. Normative References . . . . . . . . . . . . . . . . . . . 22
10.2. Informative References . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Terminology and Conventions
1.1. 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].
1.2. Definitions
This document reiterates the terminology defined in several ForCES
documents [RFC3746], [RFC5810], [RFC5811], and [RFC5812] for the sake
of contextual clarity.
Control Engine (CE)
Forwarding Engine (FE)
FE Model
LFB (Logical Functional Block) Class (or type)
LFB Instance
LFB Model
LFB Metadata
ForCES Component
LFB Component
ForCES Protocol Layer (ForCES PL)
ForCES Protocol Transport Mapping Layer (ForCES TML)
2. Introduction
In the ForCES architecture, a packet service can be modelled by
composing a graph of one or more LFB instances. The reader is
refered to the details in the ForCES Model [RFC5812].
The FEObject LFB capabilities in the ForCES Model [RFC5812] define
component ModifiableLFBTopology which, when advertised with by the
FE, implies that the advertising FE is capable of allowing creation
and modification the LFB graph by the control plane. Details on how
a graph of LFB class instances can be created can be derived by the
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control plane by looking at the FE's FEObject LFB table
SupportedLFBs. That table contains information about each LFB class
that the FE supports. For each LFB class supported, details are
provided on how that LFB class may be connected to other LFB classes.
The SupportedLFBs table describes which LFB class a specified LFB
class may succeed or precede in an LFB class instance topology. Each
link connecting two LFB class instances is described in the
LFBLinkType dataTypeDef and has sufficient details to identify
precisely the end points of a link of a service graph.
The CE may therefore create a packet service by describing an LFB
instance graph connections; achieved by updating the FEOBject
LFBTopology table.
Often there are requirements for the packet service graph to cross FE
boundaries. This could be from a desire to scale the service or need
to interact with LFBs which reside in a separate FE (eg lookaside
interface to a shared TCAM, an interconnected chip, or as coarse
grained functionality as an external NAT FE box being part of the
service graph etc).
Given that the ForCES inter-LFB architecture calls out for ability to
pass metadata between LFBs, it is imperative therefore to define
mechanisms to extend that existing feature and allow passing the
metadata between LFBs across FEs.
The new ForCES charter allows the LFB links in a topology to be
across multiple FE (inter-FE connectivity).
This document describes extending the LFB topology across FEs i.e
inter-FE connectivity without needing any changes to the ForCES
definitions. It focusses on using Ethernet as the interconnection as
a starting point while leaving room for other protocols (such as
directly on top of IP, UDP, VXLAN, etc) for different documents.
3. Problem Scope And Use Cases
The scope of this document is to solve the challenge of passing
ForCES defined metadata and exceptions across FEs (be they physical
or virtual). To illustrate the problem scope we present two use
cases where we start with a single FE running all the functionality
then split it into multiple FEs.
3.1. Basic Router
A sample LFB topology Figure 1 demonstrates a service graph for
delivering basic IPV4 forwarding service within one FE. Note:
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although the diagram shows LFB classes connecting in the graph in
reality it is a graph of LFB class instances that are inter-
connected.
Since the illustration is meant only as an exercise to showcase how
data and metadata is sent down or upstream on a graph of LFBs, it
abstracts out any ports in both directions and talks about a generic
ingress and egress LFB. Again, for illustration purposes, the
diagram does not show expection or error paths. Also left out are
details on Reverse Path Filtering, ECMP, multicast handling etc. In
other words, this is not meant to be a complete description of an
IPV4 forwarding application; for a more complete example, please
refer to the LFBlib document [RFC6956] .
The output of the ingress LFB(s) coming into the IPv4 Validator LFB
will have both the IPV4 packets and, depending on the implementation,
a variety of ingress metadata such as offsets into the different
headers, any classification metadata, physical and virtual ports
encountered, tunnelling information etc. These metadata are lumped
together as "ingress metadata".
Once the IPV4 validator vets the packet (example ensures that no
expired TTL etc), it feeds the packet and inherited metadata into the
IPV4 unicast LPM LFB.
+----+
| |
IPV4 pkt | | IPV4 pkt +-----+ +---+
+------------->| |------------->| | | |
| + ingress | | + ingress |IPv4 | IPV4 pkt | |
| metadata | | metadata |Ucast|------------>| |--+
| +----+ |LPM | + ingress | | |
+-+-+ IPv4 +-----+ + NHinfo +---+ |
| | Validator metadata IPv4 |
| | LFB NextHop|
| | LFB |
| | |
| | IPV4 pkt
| | + {ingress
+---+ + NHdetails}
Ingress metadata |
LFB +-------+ |
|Egress | |
<--|LFB |<------------------+
+-------+
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Figure 1: Basic IPV4 packet service LFB topology
The IPV4 unicast LPM LFB does a longest prefix match lookup on the
IPV4 FIB using the destination IP address as a search key. The
result is typically a next hop selector which is passed downstream as
metadata.
The Nexthop LFB receives the IPv4 packet with an associated next hop
info metadata. The NextHop LFB consumes the NH info metadata and
derives from it a table index to look up the next hop table in order
to find the appropriate egress information. The lookup result is
used to build the next hop details to be used downstream on the
egress. This information may include any source and destination
information (MAC address to use, if ethernet;) as well egress ports.
[Note: It is also at this LFB where typically the forwarding TTL
decrement and IP checksum recalculation occurs.]
The details of the egress LFB are considered out of scope for this
discussion. Suffice it is to say that somewhere within or beyond the
Egress LFB the IPV4 packet will be sent out a port (ethernet, virtual
or physical etc).
3.1.1. Distributing The LFB Topology
Figure 2 demonstrates one way the router LFB topology in Figure 1 may
be split across two FEs (eg two ASICs). Figure 2 shows the LFB
topology split across FEs after the IPV4 unicast LPM LFB.
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FE1
+-------------------------------------------------------------+
| +----+ |
| +----------+ | | |
| | Ingress | IPV4 pkt | | IPV4 pkt +-----+ |
| | LFB |+------------->| |------------->| | |
| | | + ingress | | + ingress |IPv4 | |
| +----------+ metadata | | metadata |Ucast| |
| ^ +----+ |LPM | |
| | IPv4 +-----+ |
| | Validator | |
| LFB | |
+---------------------------------------------------|---------+
|
IPv4 packet +
{ingress + NHinfo}
metadata
FE2 |
+---------------------------------------------------|---------+
| V |
| +--------+ +--------+ |
| | Egress | IPV4 packet | IPV4 | |
| <-----| LFB |<----------------------|NextHop | |
| | |{ingress + NHdetails} | LFB | |
| +--------+ metadata +--------+ |
+-------------------------------------------------------------+
Figure 2: Split IPV4 packet service LFB topology
Some proprietary inter-connect (example Broadcom Higig over XAUI
(XXX: ref needed)) maybe exist to carry both the IPV4 packet and the
related metadata between the IPV4 Unicast LFB and IPV4 NextHop LFB
across the two FEs.
The purpose of the inter-FE LFB is to define standard mechanisms for
interconnecting FEs and for that reason we are not going to touch
anymore on proprietary chip-chip interconnects other than state the
fact they exist and that it is feasible to have translation to and
from proprietary approaches. The focus is going to stick to FE-FE
interconnect where the FE could be physical or virtual and the
interconnecting technology runs a standard protocol such as ethernet,
IP or other protocols on top of IP.
3.2. Arbitray Network Function
In this section we show an example of an arbitrary network function
which is more coarse grained in terms of functionality. Each Network
function may constitute more than one LFB.
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FE1
+-------------------------------------------------------------+
| +----+ |
| +----------+ | | |
| | Network | pkt |NF2 | pkt +-----+ |
| | Function |+------------->| |------------->| | |
| | 1 | + NF1 | | + NF1/2 |NF3 | |
| +----------+ metadata | | metadata | | |
| ^ +----+ | | |
| | +-----+ |
| | | |
| | |
+---------------------------------------------------|---------+
V
Figure 3: A Network Function Service Chain within one FE
The setup in Figure 3 is atypical of most packet processing boxes
where we have functions like DPI, NAT, Routing, etc connected in such
a topology to deliver a packet processing service to flows.
3.2.1. Distributing The Arbitray Network Function
The setup in Figure 3 can be split out across 3 FEs instead as
demonstrated in Figure 4. This could be motivated by scale out
reasons or because different vendors provide different functionality
which is plugged-in to provide such functionality. The end result is
to have the same packet service delivered to the different flows
passing through.
FE1 FE2
+----------+ +----+ FE3
| Network | pkt |NF2 | pkt +-----+
| Function |+------------->| |------------->| |
| 1 | + NF1 | | + NF1/2 |NF3 |
+----------+ metadata | | metadata | |
^ +----+ | |
| +-----+
|
V
Figure 4: A Network Function Service Chain Distributed Across
Multiple FEs
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4. Proposal Overview
We address the inter-FE connectivity by proposing an inter-FE LFB.
Using an LFB implies no change to the basic ForCES architecture in
the form of the core LFBs (FE Protocol or Object LFBs). This design
choice was made after considering an alternative approach that would
have required changes to both the FE Object capabilities
(SupportedLFBs) as well LFBTopology component to describe the
inter-FE connectivity capabilities as well as runtime topology of the
LFB instances.
4.1. Inserting The Inter-FE LFB
The distributed LFB topology described in Figure 2 is re-illustrated
in Figure 5 to show the topology location where the inter-FE LFB
would fit in.
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FE1
+-------------------------------------------------------------+
| +----------+ +----+ |
| | Ingress | IPV4 pkt | | IPV4 pkt +-----+ |
| | LFB |+------------->| |------------->| | |
| | | + ingress | | + ingress |IPv4 | |
| +----------+ metadata | | metadata |Ucast| |
| ^ +----+ |LPM | |
| | IPv4 +-----+ |
| | Validator | |
| | LFB | |
| | IPv4 pkt + metadata |
| | {ingress + NHinfo + InterFEid}|
| | | |
| +----V----+ |
| | InterFE | |
| | LFB | |
| +---------+ |
+---------------------------------------------------|---------+
|
IPv4 packet and metadata
{ingress + NHinfo + Inter FE info}
FE2 |
+---------------------------------------------------|---------+
| +----V----+ |
| | InterFE | |
| | LFB | |
| +---------+ |
| | |
| IPv4 pkt + metadata |
| {ingress + NHinfo} |
| | |
| +--------+ +----V---+ |
| | Egress | IPV4 packet | IPV4 | |
| <-----| LFB |<----------------------|NextHop | |
| | |{ingress + NHdetails} | LFB | |
| +--------+ metadata +--------+ |
+-------------------------------------------------------------+
Figure 5: Split IPV4 forwarding service with Inter-FE LFB
As can be observed in Figure 5, the same details passed between IPV4
unicast LPM LFB and the IPV4 NH LFB are passed to the egress side of
the Inter-FE LFB. In addition an index for the inter-FE LFB
(interFEid) is passed as metadata.
The egress of the inter-FE LFB uses the received Inter-FE index
(InterFEid metadata) to select details for encapsulation towards the
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neighboring FE. These details will include what the source and
destination FEID to be communicated to the neighboring FE. In
addition the original metadata, any exception IDs may be passed along
with the original IPV4 packet.
On the ingress side of the inter-FE LFB the received packet and its
associated details are used to decide the graph continuation i.e
which FE instance is to be passed the packet and what of the original
metadata and exception IDs. In the illustrated case above, an IPV4
Nexthop LFB instance metadata is passed.
The ingress side of the inter-FE LFB consumes some of the information
passed (eg the destination FEID) and passes on the IPV4 packet
alongside with the ingress + NHinfo metadata to the IPV4 NextHop LFB
as was done earlier in both Figure 1 and Figure 2.
5. Inter-FE connectivity
We describe the generic encapsulation format in Figure 6 extended
from the ForCES redirect packet format. We intend for this
encapsulation to be a generic guideline of the different needed
fields to be made available by any used transport for inter-FE LFB
connectivity. We expect that for any transport mechanism used, that
a description of how the different fields will be encapsulated to be
correlated to the information described in Figure 6. The goal of
this document is to provide ethernet encapsulation, and to that end
in Section 5.1 we illustrate how we use the guidelines provided in
this section to describe the fit for inter-FE LFB interfacing over
ethernet.
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+-- Main ForCES header
| |
| +---- msg type = REDIRECT
| +---- Destination FEID
| +---- Source FEID
| +---- NEID (first word of Correlator)
|
+-- T = ExceptionID-TLV
| |
| +-- +-Exception Data ILV (I = exceptionID , L= length)
| | | |
| | | +----- V= Metadata value
| . |
| . |
| . +-Exception Data ILV
.
|
+- T = METADATA-TLV
| |
| +-- +-Meta Data ILV (I = metaid, L= length)
| | | |
| | | +----- V= Metadata value
| . |
| . |
| . +-Meta Data ILV
.
+- T = REDIRECTDATA-TLV
|
+-- Redirected packet Data
Figure 6: Packet format suggestion
o The ForCES main header as described in RFC5810 is used as a fixed
header to describe the Inter-FE encapsulation.
* The Source ID field is mapped to the originating FE and the
destination ID is mapped to the destination FEID.
* The first 32 bits of the correlator field are used to carry the
NEID. The 32-bit NEID defaults to 0.
o The ExceptionID TLV carries one or more exception IDs within ILVs.
The I in the ILV carries a globally defined exceptionID as per-
ForCES specification defined by IANA. This TLV is new to ForCES
and sits in the global ForCES TLV namespace.
o The METADATA and REDIRECTDATA TLV encapsulations are taken
directly from [RFC5810] section 7.9.
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It is expected that a variety of transport encapsulations would be
applicable to carry the format described in Figure 6. In such a
case, a description of a mapping to intepret the inter-FE details and
translate into proprietary or legacy formatting would need to be
defined. For any mapping towards these definitions a different
document to describe the mapping, one per transport, is expected to
be defined.
5.1. Inter-FE Ethernet connectivity
In this specific document, we describe a format that is to be used
over Ethernet.
The following describes the mapping from Figure 6 to ethernet wire
encapsulation illustrated in Figure 7.
o When an NE tag is needed, a VLAN tag will be used. Note: that the
NEID as per Figure 6 is described as being 32 bits while a vlan
tag is 12 bits. It is however thought to be sufficient to use 12
bits within the scope of a LAN NE cluster.
o An ethernet type will be used to imply that a wire format is
carrying an inter-FE LFB packet. The ethernet type will be
requested from the appropriate IEEE Standards Association. We
feel that given that a ForCES NE may end up being owned by a
single organization, the CE could program all participating FEs
via the inter-FE LFB (described in this document) to recognize a
private ethernet type used for inter-LFB traffic.
o The destination FEID will be mapped to the destination MAC address
of the target FEID.
o The source FEID will be mapped to the source MAC address of the
originating FEID.
o In this version of the specification, we only focus on data and
metadata. Therefore we are not going to describe how to carry the
ExceptionID information (future versions may). We are also not
going to use METADATA-TLV or REDIRECTDATA-TLV in order to save
shave off some overhead bytes. Figure 7 describes the payload
when
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Destination MAC Address (Destination FEID) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Destination MAC Address | Outer Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Source MAC Address (Source FEID) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Optional 802.1Q info (NEID) | Inter-FE ethertype |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metadata length | TLV encoded Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV encoded Metadata ~~~..............~~ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Original Ethernet payload ~~................~~ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Packet format suggestion
An outer Ethernet header is introduced to carry the information on
Destination FEID, Source FEID and optional NEID.
o The Outer Destination MAC Address carries the Destination FEID
identification.
o Outer Source MAC Address carries the Source FEID identification.
o When an NEID is needed, an optional 802.1Q is carried with 12-bit
VLANid representing the NEID.
o The ethernet type is used to identify the frame as inter-FE LFB
type.
o The 16-bit metadata length is used to described the total encoded
metadata length (including the 16 bits used to encode the metadata
length).
o One or more TLV encoded metadatum follows the metadata length
field. The TLV type identifies the Metadata id. We recognize
that this restricts the metadata id to 16 bits instead of ForCES
define space of 32 bits. However, at the time of publication we
believe this is sufficient to carry all the info we need and this
would save us 4 bytes per Metadata transferred. XXX: If there is
objection from the we could convert this to an ILV.
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o The original ethernet payload is appended at the end.
5.1.1. Inter-FE Ethernet Connectivity Issues
There are several issues that may arise due to using direct ethernet
encapsulation.
o Because we are adding data to existing ethernet frames, MTU issues
may arise. We recommend:
* To use large MTUs when possible (example with jumbo frames).
* Limit the amount of metadata that could be transmitted; our
definition allows for filtering of which metadata is to be
encapsulated in the frame. We recommend complementing this by
setting the egress port MTU to allow space for maximum size of
the metadata total size you wish to allow between FEs. MTU
setting can be achieved by configuration or ForCES control of
the port LFB. An extra 64 bytes reserved on the MTU will
account for 5 32-bit metadatum or 3 64-bit metadatum. In
essence, the control plane making a decision for the MTU size
of the egress port is implicitly deciding how much metadata
will be allowed.
o The frame may be dropped if there is congestion on the receiving
FE side. One approach to mitigate this issue is to make sure that
inter-FE LFB frames receive the highest priority treatment when
scheduled on the wire. Typically protocols that tunnel in the
middle box do not care and depend on the packet originator to
resend if the originator cares about reliability. We do not
expect to be any different.
6. Detailed Description of the Ethernet inter-FE LFB
The ethernet inter-FE LFB has two LFB input ports and three LFB
output ports.
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+-----------------+
Inter-FE LFB | |
Encapsulated | OUT2+--> decapsulated Packet + metadata
-------------->|IN2 |
Packet | |
| |
raw Packet + | OUT1+--> encapsulated Packet
-------------->|IN1 |
Metadata | |
| EXCEPTIONOUT +--> Errorid, packet + metadata
| |
+-----------------+
Figure 8: Inter-FE LFB
6.1. Data Handling
The Inter-FE LFB will be positioned at the egress of an FE at the
source FE. In such a case an Inter-FE LFB instance receives via port
IN1, raw packet and metadata IDs from the preceeding LFB instance.
The InterFEid metadatum MAY be present on the incoming raw data. The
processed encapsulated packet will go out on either LFB port OUT1 to
a downstream LFB or EXCEPTIONOUT port in the case of a failure.
The Inter-FE LFB will be positioned at the ingress of a receiving FE.
In such a case an Inter-FE LFB receives, via port IN2, an
encapsulated packet. Successful processing of the packet will result
in a raw packet with associated metadata IDs going downstream to an
LFB connected on OUT2. On failure the data is sent out EXCEPTIONOUT.
Depending on the implementation, the Inter-FE LFB may use the
InterFEid metadatum on egress of an FE to lookup the NextFE table.
The interFEid in such a case will be generated by an upstream LFB
instance (i.e one preceeding the Inter-FE LFB). The output result
constitutes a matched table row which has the InterFEinfo details
i.e. the tuple {NEID,Destination FEID,Source FEID, inter FE type,
metafilters}. The metafilters lists define which Metadatum are to be
passed to the neighboring FE. XXX: alternative implementations may
preprogram the Inter-FE LFB details to be used (and therefore do not
need presence of InterFEid metadatum). We look at the InterFEid
metadatum as lowest common denominator for inter-operability but
leave it up to the implementation to make the call.
6.1.1. Egress Processing
The egress Inter-FE LFB will receive an ethernet frame and
accompanying metadatum (including optionally the InterFEid
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metadatum). The ethernet frame may be 802.1Q tagged.
The InterFEid may be used to lookup NextFE table. If lookup is
successful, the inter-FE LFB will perform the following actions:
o create the outer ethernet header which is a duplicate of the
incoming frame's ethernet header. The outer ethernet header may
have an optional 802.1q header.
o If the NEID field is present (not 0) and the original header had a
vlan tag, replace the vlan tag on the outer header with the value
from the matched NEID field. If the NEID field is present (not 0)
and the original header did not have a vlan tag, create one that
matches the NEID field and appropriately add it to the outer
header. If the NEID field is absent or 0, do nothing.
o Set the Destination MAC address of the outer header with value
found in the DSTFE field.
o If the optional SRCFE is present, set the Source MAC address of
the outer header with value found in the SRCFE field. If SRCFE is
absent then the inner source MAC address is used (at this point
already copied).
o If the optional IFETYPE is present, set the outer ethernet type to
the value found in IFETYPE. If IFETYPE is absent then the
standard ethernet type is used (XXX: to be requested from IEEE).
o Walk the passed metadatum, apply against the MetaFilterList and
encapsulate each allowed metadatum in a TLV. Use the Metaid as
the "type" field in the TLV header. The TLV should be aligned to
32 bits. This means you may need to add padding of zeroes to
ensure alignment.
o Update the Metadata length to the sum of each TLV's space + 2
bytes (for the Metadata length field 16 bit space).
The resulting packet is sent to the LFB instance connected to the
OUT1; typicall a port LFB.
In the case of a failed lookup or a zero-value InterFEid, or absence
of InterFEid, the default inter-FE LFB processing will:
o create the outer ethernet header which is a duplicate of the
incoming frame's ethernet header. The outer ethernet header may
have an optional 802.1q header.
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o If the DefaultNextFE NEID component is not 0 and the original
header had a vlan tag, replace the vlan tag on the outer header
with the value from the matched DefaultNextFE NEID field. If the
DefaultNextFE NEID field is present (not 0) and the original
header did not have a vlan tag, create one that matches the
DefaultNextFE NEID field and appropriately add it to the outer
header. If the DefaultNextFE NEID field is absent or 0, do
nothing.
o Set the Destination MAC address of the outer header with value
found in the DefaultNextFE DSTFE component.
o If the DefaultNextFE SRCFE is non-zero, set the Source MAC address
of the outer header with value found in the DefaultNextFE SRCFE
field. If DefaultNextFE SRCFE is zero then the inner source MAC
address is used (at this point already copied).
o If the optional DefaultNextFE IFETYPE is non-zero, set the outer
ethernet type to the value found in DefaultNextFE IFETYPE. If
DefaultNextFE IFETYPE is zero then the standard ethernet type is
used (XXX: to be requested from IEEE).
o Walk all the passed metadatum, apply against the DefaultNextFE
MetaFilterList and encapsulate each allowed metadatum in a TLV.
Use the Metaid as the "type" field in the TLV header. The TLV
should be aligned to 32 bits. This means you may need to add
padding of zeroes to ensure alignment.
o Update the Metadata length to the sum of each TLV's space + 2
bytes (for the Metadata length field 16 bit space).
The resulting packet is sent to the LFB instance connected to the
OUT1 LFB port (typicall a Port LFB).
6.1.2. Ingress Processing
An inter-FE LFB packet is recognized by looking at the etherype.
o The inter-FE LFB instance looks at the metadata length field and
walks the packet data extracting from the TLVs the metadata
values. For each metadata extracted, the corresponding
implementation metadatum field is set.
o Upon completion of processing all the metadata, the inter-FE LFB
instance resets the header to point to the original (inner)
ethernet header i.e skips the metadata information. At this point
the the original ethernet frame that was passed to the egress
Inter-FE LFB at the source FE is reconstructed. This data is then
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passed alongside the reconstructed metadata downstream to the next
programmed LFB instance.
In the case of processing failure of either ingress or egress
positioning of the LFB, the packet and metadata are sent out the
EXCEPTIONOUT LFB port with proper error id (XXX: More description to
be added).
6.2. Metadata
A single (to be define from IANA space) metadatum, InterFEid, is
defined.
6.3. Components
There are two LFB component populated by the CE. Each components
information is of type IFEInfo. The IFEInfo datatype constitutes:
NEID, optional IFETYPE, Destination FEID(DSTFE), optional Source FEID
(SRCFE), array of allowed Metaids (MetaFilterList).
The CE optionally programs LFB instances in a service graph that
require inter-FE connectivity with InterFEid values to correspond to
the inter-FE LFB NextFE table entries to use.
The first component is an array known as the NextFE table. The array
rows are made up of IFEInfo structure. The table is looked up by a
32 bit index passed from an upstream LFB class instance in the form
of InterFEid metadatum.
The second component(ID 2) is an IFEInfo structure known as
DefaultNextFE. The DefaultNextFE component carries similar
information to any one table row in the NextFE table and is used as
the default source of Inter-FE encapsulation information if there is
failure to use any entry in the NextFE table.
6.4. Inter-FE LFB XML Model
XXX: add ports and metadata definition
XXX: add stats as in implementation (including error stats)
<LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
provides="IFE">
<dataTypeDefs>
<dataTypeDef>
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<name>IFEInfo</name>
<synopsis>Describing IFE table row Information</synopsis>
<struct>
<component componentID="1">
<name>NEID</name>
<synopsis>
The VLAN Id 12 bits part of the 802.1q TCI field.
</synopsis>
<typeRef>uint16</typeRef>
</component>
<component componentID="2">
<name>IFETYPE</name>
<synopsis>
the ethernet type to be used for outgoing IFE frame
</synopsis>
<optional/>
<typeRef>uint16</typeRef>
</component>
<component componentID="3">
<name>DSTFE</name>
<synopsis>
the destination MAC address of destination FE
</synopsis>
<typeRef>byte[6]</typeRef>
</component>
<component componentID="4">
<name>SRCFE</name>
<synopsis>
the source MAC address used for the source FE
</synopsis>
<optional/>
<typeRef>byte[6]</typeRef>
</component>
<component componentID="5">
<name>MetaFilterList</name>
<synopsis>
the metadata filter table
</synopsis>
<array type="variable-size">
<typeRef>uint32</typeRef>
</array>
</component>
</struct>
</dataTypeDef>
</dataTypeDefs>
<LFBClassDefs>
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<LFBClassDef LFBClassID="6612">
<name>IFE</name>
<synopsis>
This LFB describes IFE connectivity parametrization
</synopsis>
<version>1.0</version>
<components>
<component componentID="1" access="read-write">
<name>NextFE</name>
<synopsis>
the table of all InterFE relations
</synopsis>
<array type="variable-size">
<typeRef>IFEInfo</typeRef>
</array>
</component>
<component componentID="2" access="read-write">
<name>DefaultNextFE</name>
<synopsis>
the Default Next FE info. Used when we are not able
to determine what to use from NextFE
</synopsis>
<typeRef>IFEInfo</typeRef>
</component>
</components>
</LFBClassDef>
</LFBClassDefs>
</LFBLibrary>
Figure 9: Inter-FE LFB XML
7. Acknowledgements
The authors would like to thank Joel Halpern and Dave Hood for the
stimulating discussions.
8. IANA Considerations
This memo includes two IANA requests within the registry
https://www.iana.org/assignments/forces
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The first request is for the sub-registry "Logical Functional Block
(LFB) Class Names and Class Identifiers" to request for the
reservation of LFB class name IFE with LFB classid 6112 with version
1.0.
The second request is for the sub-registry "Metadata ID" to request
for the InterFEid metadata the value 0x00000010.
9. Security Considerations
TBD
10. References
10.1. Normative References
[RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal,
"Forwarding and Control Element Separation (ForCES)
Framework", RFC 3746, April 2004.
[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
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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Authors' Addresses
Damascane M. Joachimpillai
Verizon
60 Sylvan Rd
Waltham, Mass. 02451
USA
Email: damascene.joachimpillai@verizon.com
Jamal Hadi Salim
Mojatatu Networks
Suite 400, 303 Moodie Dr.
Ottawa, Ontario K2H 9R4
Canada
Email: hadi@mojatatu.com
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