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." 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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]