Internet Engineering Task Force J. Hadi Salim
Internet-Draft Mojatatu Networks
Intended status: Informational April 03, 2013
Expires: October 05, 2013
ForCES Protocol Extensions
draft-jhs-forces-protoextenstion-00
Abstract
Experience in implementing and deploying ForCES architecture has
demonstrated need for a few small extensions both to ease
programmability and to improve wire efficiency of some transactions.
This document describes a few extensions to the ForCES Protocol
Specification [RFC5810] semantics to achieve that end goal.
Status of This Memo
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Table of Contents
1. Terminology and Conventions . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Problem Overview . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Table Ranges . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Table Append . . . . . . . . . . . . . . . . . . . . . . 5
3.3. Error codes . . . . . . . . . . . . . . . . . . . . . . . 5
3.4. Bitmap Datatype . . . . . . . . . . . . . . . . . . . . . 5
4. Protocol Update Proposal . . . . . . . . . . . . . . . . . . 6
4.1. Table Ranges . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Table Append . . . . . . . . . . . . . . . . . . . . . . 6
4.3. Error Codes . . . . . . . . . . . . . . . . . . . . . . . 6
4.4. Bitmap Datatype . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
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 by the ForCES
architecture in various documents for the sake of clarity.
FE Model - The FE model is designed to model the logical
processing functions of an FE. The FE model proposed in this
document includes three components; the LFB modeling of individual
Logical Functional Block (LFB model), the logical interconnection
between 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].
LFB (Logical Functional Block) Class (or type) - A template that
represents a fine-grained, logically separable aspect of FE
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processing. Most LFBs relate to packet processing in the data
path. LFB classes are the basic building blocks of the FE model.
LFB Instance - As a packet flows through an FE along a data path,
it flows through one or multiple LFB instances, where each LFB is
an instance of a specific LFB class. Multiple instances of the
same LFB class can be present in an FE's data path. Note that we
often refer to LFBs without distinguishing between an LFB class
and LFB instance when we believe the implied reference is obvious
for the given context.
LFB Model - The LFB model describes the content and structures in
an LFB, plus the associated data definition. XML is used to
provide a formal definition of the necessary structures for the
modeling. Four types of information are defined in the LFB model.
The core part of the LFB model is the LFB class definitions; the
other three types of information define constructs associated with
and used by the class definition. These are reusable data types,
supported frame (packet) formats, and metadata.
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, but not how the per-packet state is
implemented within actual hardware. Metadata is sent between the
FE and the CE on redirect packets.
ForCES Component - A ForCES Component is a well-defined, uniquely
identifiable and addressable ForCES model building block. A
component has a 32-bit ID, name, type, and an optional synopsis
description. These are often referred to simply as components.
LFB Component - An LFB component is a ForCES component that
defines the Operational parameters of the LFBs that must be
visible to the CEs.
ForCES Protocol - Protocol that runs in the Fp reference points in
the ForCES Framework [RFC3746].
ForCES Protocol Layer (ForCES PL) - A layer in the ForCES protocol
architecture that defines the ForCES protocol messages, the
protocol state transfer scheme, and the ForCES protocol
architecture itself as defined in the ForCES Protocol
Specification [RFC5810].
ForCES Protocol Transport Mapping Layer (ForCES TML) - A layer in
ForCES protocol architecture that uses the capabilities of
existing transport protocols to specifically address protocol
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message transportation issues, such as how the protocol messages
are mapped to different transport media (like TCP, IP, ATM,
Ethernet, etc.), and how to achieve and implement reliability,
ordering, etc. the ForCES SCTP TMLP [RFC5811] describes a TML
that is mandated for ForCES.
2. Introduction
Experience in implementing and deploying ForCES architecture has
demonstrated need for a few small extensions both to ease
programmability and to improve wire efficiency of some transactions.
This document describes a few extensions to the ForCES Protocol
Specification [RFC5810] semantics to achieve that end goal.
This document describes and justifies the need for 3 small extensions
which are backward compatible.
1. A table range query to allow a controller or control application
to request for a range of table rows.
2. A table append operation to allow a controller to add a new table
row using the next available table index
3. Additional Error codes returned to the controller (or control
application) to improve granularity of existing defined error
codes.
3. Problem Overview
In this section we present sample use cases to illustrate the
challenge being addressed.
3.1. Table Ranges
Consider, for the sake of illustration, an FE table with 1 million
table rows which are sparsely populated.
ForCES GET requests from a controller (or control app) are prepended
with a path to a component and sent to the FE. In the case of
indexed tables, the component path can either be a table or a table
row index. A control application desiring to receive the first 2000
table rows appearing between row indices 23 and 10023 can achieve its
goal in one of:
o Dump the whole table and filter for the needed 2000 table rows.
o Send upto 10000 ForCES PL requests with monotonically incrementing
indices and stop when the first 2000 entries are retrieved.
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o Use ForCES batching to send fewer large messages (2000 path
requests at a time until you hit the require number of entries).
All of these approaches can be seen as programmatically unfriendly,
tedious, and both compute and bandwidth abuse.
3.2. Table Append
For the sake of illustration, assume that a newly spawned controller
application wishes to install a table row but it has no apriori
knowledge of which table index to use.
ForCES allows a controller/control app to request for the next
available table index as demonstrated in (Figure 1) (refer to
[RFC5810] section 4.8.2 for details of table properties).
CE/App FE
| |
| |
|GETproperty firstUnusedSubscript of table X |
1 |------------------------------------------->|
| |
| Table X firstUnusedSubscript is 1234 |
2 |<-------------------------------------------|
| |
| Table update using index 1234 |
3 |<------------------------------------------>|
| |
Figure 1: ForCES table property request
The problem with the above setup is the application requires one
roundtrip time to figure out the index to insert into. Moreover,
depending on implementation (and in presence of multiple possible
control applications), there is no guarantee that the next unused
subscript in the above example would be 1235; which means if the
application wishes to insert more than one entry, it will have to
incur the roundtrip time for every to-be-inserted table row. XXX:
talk about possibly enforcing reservations for multi-app etc.
3.3. Error codes
TBA
3.4. Bitmap Datatype
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TBA
4. Protocol Update Proposal
4.1. Table Ranges
We propose to add a Table-range TLV (type ID 0x117) that will be
associated with the PATH-DATA TLV in the same manner the KEYINFO-TLV
is. Path flag of F_SELTABRANGE (0x2) is set to indicate the presence
of the Table-range TLV. XXX: This pathflag can only be used in a GET
and is mutually exclusive with F_SELKEY.
The Table-range TLV contents constitute:
o A 32 bit start index. XXX: May need a wild-card.
o A 32 bit end index. XXX: May need a wild-card.
The response for a table range query will either be:
o When referenced table rows exist, then a response with a path
pointing to the table and whose data content contain the rows will
be sent to the CE. The encapsulating sparse data will have the
"I" (in ILV) indicating the table indices.
o When data is absent, a return code indicating absence of content
in the specified range is sent back to the CE.
4.2. Table Append
We propose using a path flag, F_TABAPPEND(0x4) to achieve this goal.
When a CE application wishes to append to the table, it will set the
path to a desired table index and set the path flag to F_TABAPPEND.
The FE will first attempt to use the specified index and when
unsuccessful will use an available table row index.
When successful, an E_SUCCESS return code is sent back to the CE.
The path piece of the response will contain the table row index where
the table row was inserted.
4.3. Error Codes
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4.4. Bitmap Datatype
TBA
5. IANA Considerations
TBA: request to IANA for Table-range TLV, F_SELTABRANGE etc.
6. Security Considerations
TBD
7. References
7.1. 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.
7.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Author's Address
Jamal Hadi Salim
Mojatatu Networks
Suite 400, 303 Moodie Dr.
Ottawa, Ontario K2H 9R4
Canada
Email: hadi@mojatatu.com
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