[Docs] [txt|pdf] [Tracker] [WG] [Email] [Nits]

Versions: 00

INTERNET-DRAFT                                                    R. Coltun
draft-ietf-idmr-dvmrp-v1-as-00                                 FORE Systems
                                                                 S. Deering
                                                                      Cisco
                                                                T. Pusateri
                                                           Juniper Networks
                                                                 R. Shekhar
                                                               FORE Systems
                                                      Expires: January 1999






               DVMRPv1 Applicability Statement for Historic Status






Status of this Memo

     This document is an Internet Draft.  Internet Drafts are working docu-
     ments of the Internet Engineering Task Force (IETF), its Areas, and
     its Working Groups. Note that other groups may also distribute working
     documents as Internet Drafts.

     Internet Drafts are draft documents valid for a maximum of six months.
     Internet Drafts may be updated, replaced, or obsoleted by other docu-
     ments at any time.  It is not appropriate to use Internet Drafts as
     reference material or to cite them other than as a "working draft" or
     "work in progress."

     To view the entire list of current Internet-Drafts, please check the
     "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
     Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Europe),
     ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Rim),
     ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast).

     Distribution of this memo is unlimited.









Coltun, Deering, Pusateri, Shekhar                                 [Page 1]


Internet-Draft        DVMRPv1 Applicability Statement             July 1998


Table Of Contents

     1.0 Abstract ................................................. 2

     2.0 Introduction ............................................. 2

     3.0 DVMRPv1 Restrictions ..................................... 3

     3.2 Network Advertisements ................................... 3

     3.3 Tunnel Support ........................................... 3

     4.0 Conclusion ............................................... 3

     5.0 Security Considerations .................................. 4

     6.0 Authors' Addresses ....................................... 4

     7.0 References ............................................... 4





1.0 Abstract

     DVMRP version 1 (DVMRPv1) [RFC-1075] has been declared a historic
     document.  This applicability statement provides the supporting
     motivation for that declaration.


2.0 Introduction

     DVMRP is an Internet multicast routing protocol that provides an effi-
     cient mechanism for datagram delivery to a group of hosts across an
     internetwork. It is a distributed protocol that dynamically generates
     IP Multicast delivery trees using a technique called Reverse Path Mul-
     ticasting (RPM) [Deering].

     While current versions of DVMRP are widely used throughout the Inter-
     net, DVMRPv1 as defined in RFC-1075, is not applicable for use.  RFC-
     1075 describes a very early version of DVMRP which was never fully
     implemented. A partial implementation was deployed on three Unix boxes
     for a few months in 1988. Experience with that early implementation
     led to a complete, non-backwards-compatible redesign; it is the des-
     cendants of that redesign that are widely implemented and widely used
     in the MBone and elsewhere.




Coltun, Deering, Pusateri, Shekhar                                 [Page 2]


Internet-Draft        DVMRPv1 Applicability Statement             July 1998


3.0 DVMRPv1 Restrictions

     DVMRPv1 has a number of restrictions and behaviors which limit its
     usability in the global Internet.


3.1 Protocol Reliability Mechanisms

     DVMRPv1 had no "keep-alive" mechanism between neighboring DVRMP
     routers.  It was therefore not possible to detect that a router was
     restarted. A restarted router would introduce inconsistency in the
     state of previously sent non-membership reports.  Until the upstream
     and downstream dependencies were updated the network would not have
     consistent information. This would result in slow network convergence.

     DVMRPv1 did not include acknowledgements for non-membership cancella-
     tions (i.e., grafts).  Consequently, there was no way of knowing
     whether a graft was lost or the graft was successfully received but
     the source has stopped transmitting the data.  The effects of this was
     also to slow down network convergence.


3.2 Network Advertisements

     In DVMRPv1, non-membership reports didn't contain source networks,
     they only contained groups.  This resulted in less optimal multicast
     forwarding trees and multicast data being distributed further down the
     forwarding tree than necessary.

     In DVMRPv1, route masks were too restrictive. As a result it was not
     possible to include the default route (0/0) or a host network mask
     (/32) in route updates.  Additionally, routes with subnet masks were
     not allowed to be advertised outside of the classful network (i.e., no
     CIDR support).


3.3 Tunnel Support

     In DVMRPv1 tunnels were supported using the IP loose source route
     option; protocol messages were sent un-encapsulated directly to the
     tunnel endpoint.  While this was the more direct approach to tunnels,
     it resulted in a significant performance penalty (in addition to delay
     and jitter) imposed by most routers on packets that carry IP options.


4.0 Conclusion

     The recommendation of this Applicability Statement is that networks



Coltun, Deering, Pusateri, Shekhar                                 [Page 3]


Internet-Draft        DVMRPv1 Applicability Statement             July 1998


     that desire to use DVMRP in a network environment should use the
     current version of DVMRP (DVMRPv3) as defined in [Pusateri].

5.0 Security Considerations

     DVMRPv1 includes no security functions.

     Security for DVMRPv3 follows the general security architecture pro-
     vided for the Internet Protocol.  This framework provides for both
     privacy and authentication.  It recommends the use of the IP Authenti-
     cation Header to provide trusted neighbor relationships. Confidential-
     ity is provided by the addition of the IP Encapsulating Security Pay-
     load.


6.0 Authors' Addresses

     Rob Coltun
     FORE Systems
     Phone: (703) 245-4543
     EMail: rcoltun@fore.com

     Stephen E. Deering
     Cisco Systems, Inc.
     170 West Tasman Drive
     San Jose, CA 95134-1706
     EMail: deering@cisco.com
     Phone: (408) 527-8213

     Tom Pusateri
     Juniper Networks, Inc.
     385 Ravendale Dr.
     Mountain View, CA  94043
     Phone: (919) 558-0700
     EMail: pusateri@juniper.net

     Ravi Shekhar
     FORE Systems
     Phone: (703) 245-4534
     EMail: rshekhar@fore.com


7.0 References

     [Deering]  Deering, S., Cheriton, D., "Multicast Routing in Datagram
                Internetworks and Extended LANs",  ACM Transactions on
                Computer Systems, Vol. 8, No. 2, May 1990, pp. 85-110.




Coltun, Deering, Pusateri, Shekhar                                 [Page 4]


Internet-Draft        DVMRPv1 Applicability Statement             July 1998


     [RFC-1075] Waitzman, D., Partridge, C., Deering, S., "Distance Vector
                Multicast Routing Protocol",  RFC 1075, November 1988.


     [Pusateri] Pusateri, T. "Distance Vector Multicast Routing Protocol",
                Work in Progress, May 1998.













































Coltun, Deering, Pusateri, Shekhar                                 [Page 5]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/