Network Working Group B. Fenner
Request for Comments: 4601 AT&T Labs - Research
Obsoletes: 2362 M. Handley
Category: Standards Track UCL
H. Holbrook
Arastra
I. Kouvelas
Cisco
August 2006
Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)
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.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document specifies Protocol Independent Multicast - Sparse Mode
(PIM-SM). PIM-SM is a multicast routing protocol that can use the
underlying unicast routing information base or a separate multicast-
capable routing information base. It builds unidirectional shared
trees rooted at a Rendezvous Point (RP) per group, and optionally
creates shortest-path trees per source.
This document obsoletes RFC 2362, an Experimental version of PIM-SM.
Fenner, et al. Standards Track [Page 1]
RFC 4601 PIM-SM Specification August 2006
Table of Contents
1. Introduction ....................................................5
2. Terminology .....................................................5
2.1. Definitions ................................................5
2.2. Pseudocode Notation ........................................7
3. PIM-SM Protocol Overview ........................................7
3.1. Phase One: RP Tree .........................................8
3.2. Phase Two: Register-Stop ...................................8
3.3. Phase Three: Shortest-Path Tree ............................9
3.4. Source-Specific Joins .....................................10
3.5. Source-Specific Prunes ....................................11
3.6. Multi-Access Transit LANs .................................11
3.7. RP Discovery ..............................................12
4. Protocol Specification .........................................12
4.1. PIM Protocol State ........................................13
4.1.1. General Purpose State ..............................14
4.1.2. (*,*,RP) State .....................................15
4.1.3. (*,G) State ........................................16
4.1.4. (S,G) State ........................................17
4.1.5. (S,G,rpt) State ....................................20
4.1.6. State Summarization Macros .........................21
4.2. Data Packet Forwarding Rules ..............................26
4.2.1. Last-Hop Switchover to the SPT .....................28
4.2.2. Setting and Clearing the (S,G) SPTbit ..............29
4.3. Designated Routers (DR) and Hello Messages ................30
4.3.1. Sending Hello Messages .............................30
4.3.2. DR Election ........................................32
4.3.3. Reducing Prune Propagation Delay on LANs ...........34
4.3.4. Maintaining Secondary Address Lists ................37
4.4. PIM Register Messages .....................................38
4.4.1. Sending Register Messages from the DR ..............38
4.4.2. Receiving Register Messages at the RP ..............43
4.5. PIM Join/Prune Messages ...................................45
4.5.1. Receiving (*,*,RP) Join/Prune Messages .............45
4.5.2. Receiving (*,G) Join/Prune Messages ................49
4.5.3. Receiving (S,G) Join/Prune Messages ................53
4.5.4. Receiving (S,G,rpt) Join/Prune Messages ............56
4.5.5. Sending (*,*,RP) Join/Prune Messages ...............62
4.5.6. Sending (*,G) Join/Prune Messages ..................66
4.5.7. Sending (S,G) Join/Prune Messages ..................71
4.5.8. (S,G,rpt) Periodic Messages ........................76
4.5.9. State Machine for (S,G,rpt) Triggered Messages .....77
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