INTERNET-DRAFT                                              J. Hawkinson
draft-ietf-mboned-pruning-01.txt                              BBN Planet
Category: Best Current Practice                        10 September 1996

                     Multicast pruning a necessity

Status of this Memo

   This document specifies an Internet Best Current Practice for the
   Internet Community, and requests discussion and suggestions for
   improvements.  Distribution of this memo is unlimited.

Internet Drafts

   This document is an Internet-Draft.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
   and its working groups.  Note that other groups may also distribute
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Abstract

   This document mandates that the MBone will be free of non-pruning
   multicast implementations by 31 October 1996.

   It is a product of the Multicast Deployment Working Group in the
   Operational Requirements area of the Internet Engineering Task Force.
   Submit comments to <mboned@ns.uoregon.edu> or the author.

Discussion

   The MBone (Multicast Backbone) of the Internet is composed of a DVMRP
   backbone connected to regions that may be running other multicast
   routing protocols.

   DVMRP versions prior to 3 do not support pruning. Every multicast
   packet transmitted is delivered to every non-pruning router (subject
   to scoping rules), regardless of the presence of members of that



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Expires 31 September 1996   INTERNET-DRAFT             10 September 1996


   group. Network paths between each source and each non-pruning router
   are thus forced to carry all multicast traffic from those sources.
   This behavior is fundamentally incompatible with a scalable multicast
   backbone.

   Effective 31 October 1996, the MBone community will no longer accept
   such non-pruning implementations as a part of the MBone. Such
   implementations should be upgraded or disconnected from the MBone
   prior to that date. Service providers should assist their customers
   in these processes.

   DVMRP implementations that do not support pruning include mrouted
   versions prior to 3, and Cisco Systems IOS prior to version 11.0(3).
   3Com's NETBuilder routers and LANplex switches have supported pruning
   as long as DVMRP has been available for them (releases 8.3 and 7.0,
   respectively).  Bay Networks' implementation supports pruning in
   version 9.00 and up.

   Within non-DVMRP regions, software that does not support DVMRP
   pruning but does support a similar mechanism of a different protocol
   (such as CBT, MOSPF, or PIM) is acceptable, as long as the border
   routers of such a region can translate that mechansism into DVMRP
   pruning.

Security Considerations

   Security considerations are not addressed in this memo.

References

   [IPMULTI] S.E. Deering, "Host extensions for IP multicasting", RFC1112,
           1 August 1989.

   [MREQ] R. Braudes, S. Zabele, "Requirements for Multicast Protocols",
           RFC1458, 26 May 1993.

   [DVMRP] T. Pusateri, "Distance Vector Multicast Routing Protocol",
           Work in progress (internet-draft).

Author's Address

   John Hawkinson
   BBN Planet
   150 CambridgePark Drive
   Cambridge, MA 02140

   phone: +1 617 873 3180
   email: jhawk@bbnplanet.com



Hawkinson                                                       [Page 2]