Network Working Group A. Boers
Request for Comments: 5384 I. Wijnands
Category: Standards Track E. Rosen
Cisco Systems, Inc.
November 2008
The Protocol Independent Multicast (PIM)
Join Attribute Format
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
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Abstract
A "Protocol Independent Multicast - Sparse Mode" Join message sent by
a given node identifies one or more multicast distribution trees that
that node wishes to join. Each tree is identified by the combination
of a multicast group address and a source address (where the source
address is possibly a "wild card"). Under certain conditions it can
be useful, when joining a tree, to specify additional information
related to the construction of the tree. However, there has been no
way to do so until now. This document describes a modification of
the Join message that allows a node to associate attributes with a
particular tree. The attributes are encoded in Type-Length-Value
format.
Boers, et al. Standards Track [Page 1]
RFC 5384 PIM Join Attribute November 2008
Table of Contents
1. Introduction ....................................................2
2. Specification of Requirements ...................................3
3. Use of Join Attributes ..........................................3
3.1. Sending Join Attributes ....................................3
3.2. The Join Attribute Option in the PIM Hello .................4
3.3. Receiving Join Attributes ..................................4
3.3.1. General Considerations ..............................4
3.3.2. Transitive and Non-Transitive Attributes ............5
3.3.3. Conflicting Attributes ..............................5
3.3.4. Attribute Change ....................................6
3.4. PIM Attribute Packet Format ................................7
3.4.1. PIM Join Packet Format ..............................7
3.4.2. PIM Join Attribute Hello Option .....................8
4. IANA Considerations .............................................8
5. Security Considerations .........................................9
6. Acknowledgments .................................................9
7. Normative References ............................................9
8. Informative References ..........................................9
1. Introduction
In the protocol known as "Protocol Independent Multicast - Sparse
Mode" [RFC4601] (henceforth referred to as "PIM"), a Join message
sent by a given node may identify one or more multicast distribution
trees that that node wishes to join. Each tree is identified by the
combination of a multicast group address and a source address (where
the source address is possibly a "wild card"). Under certain
conditions it can be useful, when joining a tree, to specify
additional information related to the construction of the tree.
However, there has been no way to do so until now. This document
describes a modification of the Join message that allows a node to
associate an attribute, encoded in Type-Length-Value (TLV) format,
with a particular tree that it wishes to join. These attributes are
known as "PIM Join Attributes".
In the PIM Join message, the Source Address is identified by being
encoded as an "Encoded-Source Address" ([RFC4601], section 4.9.1).
Each Encoded-Source Address occurs in the context of a particular
group address, represented as an "Encoded-Group Address". Together,
the Encoded-Source Address and the Encoded-Group Address identify a
datatracker.ietf.org