Network Working Group A. Adams
Request for Comments: 3973 NextHop Technologies
Category: Experimental J. Nicholas
ITT A/CD
W. Siadak
NextHop Technologies
January 2005
Protocol Independent Multicast - Dense Mode (PIM-DM):
Protocol Specification (Revised)
Status of This Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document specifies Protocol Independent Multicast - Dense Mode
(PIM-DM). PIM-DM is a multicast routing protocol that uses the
underlying unicast routing information base to flood multicast
datagrams to all multicast routers. Prune messages are used to
prevent future messages from propagating to routers without group
membership information.
Adams, et al. Experimental [Page 1]
RFC 3973 PIM - Dense Mode January 2005
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Pseudocode Notation . . . . . . . . . . . . . . . . . . 5
3. PIM-DM Protocol Overview . . . . . . . . . . . . . . . . . . . 5
4. Protocol Specification . . . . . . . . . . . . . . . . . . . . 6
4.1. PIM Protocol State . . . . . . . . . . . . . . . . . . . 7
4.1.1. General Purpose State . . . . . . . . . . . . . 7
4.1.2. (S,G) State . . . . . . . . . . . . . . . . . . 8
4.1.3. State Summarization Macros . . . . . . . . . . . 8
4.2. Data Packet Forwarding Rules . . . . . . . . . . . . . . 10
4.3. Hello Messages . . . . . . . . . . . . . . . . . . . . . 11
4.3.1. Sending Hello Messages . . . . . . . . . . . . . 11
4.3.2. Receiving Hello Messages . . . . . . . . . . . . 11
4.3.3. Hello Message Hold Time . . . . . . . . . . . . 12
4.3.4. Handling Router Failures . . . . . . . . . . . . 12
4.3.5. Reducing Prune Propagation Delay on LANs . . . . 13
4.4. PIM-DM Prune, Join, and Graft Messages . . . . . . . . . 13
4.4.1. Upstream Prune, Join, and Graft Messages . . . . 14
4.4.1.1. Transitions from the Forwarding
(F) State . . . . . . . . . . . . . . 17
4.4.1.2. Transitions from the Pruned
(P) State . . . . . . . . . . . . . . 18
4.4.1.3. Transitions from the AckPending
(AP) State . . . . . . . . . . . . . . 19
4.4.2. Downstream Prune, Join, and Graft Messages . . . 21
4.4.2.1. Transitions from the NoInfo State . . 23
4.4.2.2. Transitions from the PrunePending
(PP) State . . . . . . . . . . . . . . 24
4.4.2.3. Transitions from the Prune
(P) State . . . . . . . . . . . . . . 25
4.5. State Refresh . . . . . . . . . . . . . . . . . . . . . 26
4.5.1. Forwarding of State Refresh Messages . . . . . . 26
4.5.2. State Refresh Message Origination . . . . . . . 28
4.5.2.1. Transitions from the NotOriginator
(NO) State . . . . . . . . . . . . . . 29
4.5.2.2. Transitions from the Originator
(O) State . . . . . . . . . . . . . . 29
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RFC 3973 PIM - Dense Mode January 2005
4.6. PIM Assert Messages . . . . . . . . . . . . . . . . . . 30
4.6.1. Assert Metrics . . . . . . . . . . . . . . . . . 30
4.6.2. AssertCancel Messages . . . . . . . . . . . . . 31
4.6.3. Assert State Macros . . . . . . . . . . . . . . 32
4.6.4. (S,G) Assert Message State Machine . . . . . . . 32
4.6.4.1. Transitions from NoInfo State . . . . 34
4.6.4.2. Transitions from Winner State . . . . 35
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