Multicast-Scope Zone Announcement Protocol (MZAP)
RFC 2776

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Network Working Group                                         M. Handley
Request for Comments: 2776                                         ACIRI
Category: Standards Track                                      D. Thaler
                                                               Microsoft
                                                              R. Kermode
                                                                Motorola
                                                           February 2000

           Multicast-Scope Zone Announcement Protocol (MZAP)

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 (2000).  All Rights Reserved.

Abstract

   This document defines a protocol, the Multicast-Scope Zone
   Announcement Protocol (MZAP), for discovering the multicast
   administrative scope zones that are relevant at a particular
   location.  MZAP also provides mechanisms whereby common
   misconfigurations of administrative scope zones can be discovered.

Table of Contents

   1 Introduction ................................................  2
   2 Terminology .................................................  4
   3 Overview ....................................................  5
   3.1 Scope Nesting .............................................  6
   3.2 Other Messages ............................................  7
   3.3 Zone IDs ..................................................  7
   4 Detecting Router Misconfigurations ..........................  8
   4.1 Detecting non-convex scope zones ..........................  8
   4.2 Detecting leaky boundaries for non-local scopes ...........  9
   4.3 Detecting a leaky Local Scope zone ........................ 10
   4.4 Detecting conflicting scope zones ......................... 10
   5 Packet Formats .............................................. 11
   5.1 Zone Announcement Message ................................. 14
   5.2 Zone Limit Exceeded (ZLE) ................................. 15
   5.3 Zone Convexity Message .................................... 15

Handley, et al.             Standards Track                     [Page 1]
RFC 2776                          MZAP                     February 2000

   5.4 Not-Inside Message ........................................ 16
   6 Message Processing Rules .................................... 17
   6.1 Internal entities listening to MZAP messages .............. 17
   6.2 Sending ZAMs .............................................. 18
   6.3 Receiving ZAMs ............................................ 18
   6.4 Sending ZLEs .............................................. 20
   6.5 Receiving ZLEs ............................................ 20
   6.6 Sending ZCMs .............................................. 21
   6.7 Receiving ZCMs ............................................ 21
   6.8 Sending NIMs .............................................. 21
   6.9 Receiving NIMs ............................................ 22
   7 Constants ................................................... 22
   8 Security Considerations ..................................... 23
   9 Acknowledgements ............................................ 24
   10 References ................................................. 25
   11 Authors' Addresses ......................................... 26
   12 Full Copyright Statement ................................... 27

1.  Introduction

   The use of administratively-scoped IP multicast, as defined in RFC
   2365 [1], allows packets to be addressed to a specific range of
   multicast addresses (e.g., 239.0.0.0 to 239.255.255.255 for IPv4)
   such that the packets will not cross configured administrative
   boundaries, and also allows such addresses to be locally assigned and
   hence are not required to be unique across administrative boundaries.
   This property of logical naming both allows for address reuse, as
   well as provides the capability for infrastructure services such as
   address allocation, session advertisement, and service location to
   use well-known addresses which are guaranteed to have local
   significance within every organization.

   The range of administratively-scoped addresses can be subdivided by
   administrators so that multiple levels of administrative boundaries
   can be simultaneously supported.  As a result, a "multicast scope" is
   defined as a particular range of addresses which has been given some
   topological meaning.

   To support such usage, a router at an administrative boundary is
   configured with one or more per-interface filters, or "multicast
   scope boundaries".  Having such a boundary on an interface means that