Core Based Trees (CBT version 2) Multicast Routing -- Protocol Specification --
RFC 2189

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Network Working Group                                       A. Ballardie
Request for Comments: 2189                                    Consultant
Category: Experimental                                    September 1997

           Core Based Trees (CBT version 2) Multicast Routing

                      -- Protocol Specification --

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.

Abstract

   This document describes the Core Based Tree (CBT version 2) network
   layer multicast routing protocol. CBT builds a shared multicast
   distribution tree per group, and is suited to inter- and intra-domain
   multicast routing.

   CBT may use a separate multicast routing table, or it may use that of
   underlying unicast routing, to establish paths between senders and
   receivers. The CBT architecture is described in [1].

   This document is progressing through the IDMR working group of the
   IETF.  CBT related documents include [1, 5, 6]. For all IDMR-related
   documents, see http://www.cs.ucl.ac.uk/ietf/idmr.

TABLE OF CONTENTS

  1. Changes Since Previous version............................. 2
  2. Introduction & Terminology................................. 3
  3. CBT Functional Overview.................................... 3
  4. CBT Protocol Specificiation Details........................ 6
     4.1 CBT HELLO Protocol..................................... 6
         4.1.1 Sending HELLOs................................... 7
         4.1.2 Receiving HELLOs................................. 7
     4.2 JOIN_REQUEST Processing................................ 8
         4.2.1 Sending JOIN_REQUESTs............................ 8
         4.2.2 Receiving JOIN_REQUESTs.......................... 8
     4.3 JOIN_ACK Processing.................................... 9
         4.3.1 Sending JOIN_ACKs................................ 9
         4.3.2 Receiving JOIN_ACKs.............................. 9

Ballardie                     Experimental                      [Page 1]
RFC 2189              CBTv2 Protocl Specification         September 1997

     4.4 QUIT_NOTIFICATION Processing........................... 10
         4.4.1 Sending QUIT_NOTIFICATIONs....................... 10
         4.4.2 Receiving QUIT_NOTIFICATIONs..................... 10
     4.5 CBT ECHO_REQUEST Processing............................ 11
         4.5.1 Sending ECHO_REQUESTs............................ 11
         4.5.2 Receiving ECHO_REQUESTs.......................... 12
     4.6 ECHO_REPLY Processing.................................. 12
         4.6.1 Sending ECHO_REPLYs.............................. 12
         4.6.2 Receiving ECHO_REPLYs............................ 12
     4.7 FLUSH_TREE Processing.................................. 13
         4.7.1 Sending FLUSH_TREE Messages...................... 13
         4.7.2 Receiving FLUSH_TREE Messages.................... 13
  5. Non-Member Sending......................................... 13
  6. Timers and Default Values.................................. 13
  7. CBT Packet Formats and Message Types....................... 14
     7.1 CBT Common Control Packet Header....................... 14
     7.2 HELLO Packet Format.................................... 15
     7.3 JOIN_REQUEST Packet Format............................. 16
     7.4 JOIN_ACK Packet Format................................. 16
     7.5 QUIT_NOTIFICATION Packet Format........................ 17
     7.6 ECHO_REQUEST Packet Format............................. 18
     7.7 ECHO_REPLY Packet Format............................... 18
     7.8 FLUSH_TREE Packet Format............................... 19
  8. Core Router Discovery...................................... 19
     8.1  "Bootstrap" Mechanism Overview........................ 20
     8.2  Bootstrap Message Format.............................. 21
     8.3  Candidate Core Advertisement Message Format........... 21
  9. Interoperability Issues.................................... 21
  10.  Security Considerations.................................. 21
  Acknowledgements.............................................. 22
  References.................................................... 22
  Author Information............................................ 23

1.  Changes from CBT version 1

   This version of the CBT protocol specification differs significantly
   from the previous version. Consequently, this version represents
   version 2 of the CBT protocol.  CBT version 2 is not, and was not,
   intended to be backwards compatible with version 1; we do not expect
   this to cause extensive compatibility problems because we do not
   believe CBT is at all widely deployed at this stage. However, any
   future versions of CBT can be expected to be backwards compatible
   with this version.