Bootstrap Router (BSR) Mechanism for Protocol Independent Multicast (PIM)
RFC 5059

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Network Working Group                                         N. Bhaskar
Request for Comments: 5059                                       Arastra
Obsoletes: 2362                                                  A. Gall
Updates: 4601                                                     SWITCH
Category: Standards Track                                     J. Lingard
                                                                 Arastra
                                                               S. Venaas
                                                                 UNINETT
                                                            January 2008

                   Bootstrap Router (BSR) Mechanism
                for Protocol Independent Multicast (PIM)

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.

Abstract

   This document specifies the Bootstrap Router (BSR) mechanism for the
   class of multicast routing protocols in the PIM (Protocol Independent
   Multicast) family that use the concept of a Rendezvous Point as a
   means for receivers to discover the sources that send to a particular
   multicast group.  BSR is one way that a multicast router can learn
   the set of group-to-RP mappings required in order to function.  The
   mechanism is dynamic, largely self-configuring, and robust to router
   failure.

Bhaskar, et al.             Standards Track                     [Page 1]
RFC 5059                 BSR Mechanism for PIM              January 2008

Table of Contents

   1. Introduction ....................................................3
      1.1. Background .................................................3
      1.2. Protocol Overview ..........................................5
      1.3. Administrative Scoping and BSR .............................6
   2. BSR State and Timers ............................................8
   3. Bootstrap Router Election and RP-Set Distribution ...............9
      3.1. Bootstrap Router Election ..................................9
           3.1.1. Per-Scope-Zone Candidate-BSR State Machine .........10
           3.1.2. Per-Scope-Zone State Machine for
                  Non-Candidate-BSR Routers ..........................11
           3.1.3. Bootstrap Message Processing Checks ................13
           3.1.4. State Machine Transition Events ....................14
           3.1.5. State Machine Actions ..............................15
      3.2. Sending Candidate-RP-Advertisement Messages ...............17
      3.3. Creating the RP-Set at the BSR ............................18
      3.4. Forwarding Bootstrap Messages .............................21
      3.5. Bootstrap Messages to New and Rebooting Routers ...........22
           3.5.1. No-Forward Bootstrap Messages ......................23
           3.5.2. Unicasting Bootstrap Messages ......................23
      3.6. Receiving and Using the RP-Set ............................23
   4. Message Formats ................................................24
      4.1. Bootstrap Message Format ..................................26
           4.1.1. Semantic Fragmentation of BSMs .....................30
      4.2. Candidate-RP-Advertisement Message Format .................31
   5. Timers and Timer Values ........................................33
   6. Security Considerations ........................................36
      6.1. Possible Threats ..........................................36
      6.2. Limiting Third-Party DoS Attacks ..........................36
      6.3. Bootstrap Message Security ................................37
           6.3.1. Unicast Bootstrap Messages .........................37
           6.3.2. Multi-Access Subnets ...............................38
      6.4. Candidate-RP-Advertisement Message Security ...............38
           6.4.1. Non-Cryptographic Security of C-RP-Adv Messages ....38
           6.4.2. Cryptographic Security of C-RP-Adv Messages ........39
      6.5. Denial of Service using IPsec .............................39
   7. Contributors ...................................................40
   8. Acknowledgments ................................................40
   9. Normative References ...........................................40
   10. Informative References ........................................41

Bhaskar, et al.             Standards Track                     [Page 2]
RFC 5059                 BSR Mechanism for PIM              January 2008

1.  Introduction

   This document assumes some familiarity with the concepts of Protocol
   Independent Multicast - Sparse Mode (PIM-SM) [1] and Bidirectional