DVMRP

DVMRP
Name	DVMRP
Full name	Distance Vector Multicast Routing Protocol
Initial release	1988
Developers	David Waitzman; Internet Engineering Task Force
Status	Obsolete/Legacy (superseded by Protocol Independent Multicast variants)
Type	Multicast routing protocol
Layer	Network layer (IP)
Related	MOSPF, PIM, IGMP, MBONE

DVMRP DVMRP is a multicast routing protocol designed to support IP multicast distribution across internets by building reverse-path forwarding trees. Initially developed to enable multicast delivery for experimental testbeds and early deployments, DVMRP influenced subsequent multicast technologies and the multicast routing architecture used in the early Internet Engineering Task Force discussions, MBone demonstrations, and wide-area experiments.

Overview

DVMRP uses distance-vector techniques and reverse-path forwarding to establish multicast distribution trees and to prune branches without receivers. It interoperated with address allocation and group management systems such as Internet Assigned Numbers Authority policies and Internet Group Management Protocol signaling. Early implementations ran on kernels and routing daemons developed for platforms including BSD Unix, SunOS, and router linecards from vendors like Cisco Systems, Juniper Networks, and Alcatel-Lucent-era products tested in projects by institutions such as Stanford University, MIT, USC Information Sciences Institute, and Lawrence Berkeley National Laboratory.

History and Development

DVMRP originated in the late 1980s, authored by researchers including David Waitzman while participating in multicast experiments coordinated among organizations like DARPA, NSF, and the IETF multicast working groups. It was instrumental in the creation of the MBone overlay, which linked research sites such as Carnegie Mellon University, UC Berkeley, Princeton University, and University of California, Los Angeles for multimedia demonstrations at conferences like SIGCOMM, Usenix, and IETF meetings. The protocol matured alongside multicast group management advances embodied in IGMPv1 and later IGMPv2, and influenced multicast routing proposals presented at venues such as ACM SIGCOMM and standards discussions in IETF tracks.

Protocol Design and Operation

DVMRP’s core operation relies on periodic exchange of distance-vector updates between neighboring routers to compute next hops toward multicast sources, using reverse-path forwarding checks derived from source address reachability via unicast routing. The protocol interacts with multicast group membership reports from hosts via IGMPv2 and with unicast routing protocols such as RIP, OSPF, and BGP for source reachability information. Prune and graft messages remove or restore branches of the multicast tree, and tunneling techniques were used over networks with limited multicast support, resembling mechanisms also discussed in RFC documents and implementations by vendors that participated in interoperability tests at IETF interop events.

Routing Algorithms and Mechanisms

DVMRP uses distance-vector algorithms akin to those in RIP but augmented for multicast-specific delivery: routers maintain neighbor reachability, hop counts, and next-hop information to perform reverse-path forwarding (RPF) checks toward the source. When downstream routers indicate no local receivers via prune messages, the protocol suppresses forwarding on those links until soft-state timers expire or graft messages are received. The mechanism contrasts with link-state multicast methods such as MOSPF and with protocol-independent approaches exemplified by PIM-SM and PIM-DM. The algorithmic behavior was analyzed in academic works from institutions like MIT, Columbia University, ETH Zurich, and University College London in papers presented at ACM SIGCOMM, IEEE INFOCOM, and USENIX conferences.

Implementation and Deployment

Production and experimental implementations of DVMRP were included in router software and research daemons from projects at UC Berkeley networking labs, vendor prototypes from Cisco Systems and early multicast-capable platforms from Sun Microsystems and IBM. DVMRP featured in MBone demonstrations connecting sites such as NASA Ames Research Center, Los Alamos National Laboratory, and Lawrence Livermore National Laboratory for multimedia streaming and teleconferencing at events like IETF plenaries and SIGGRAPH exhibitions. Operators integrated DVMRP with network management platforms from firms like HP, EMC-era tooling, and with monitoring systems used in measurement studies from CAIDA and academic measurement projects at University of Michigan and University of Washington.

Security and Scalability Considerations

DVMRP’s original design did not include strong authentication, making it vulnerable to falsified route updates and prune manipulation in hostile environments; such vulnerabilities were highlighted in analyses by researchers at SRI International, NRL, and Bell Labs. Scaling DVMRP to large internets proved challenging due to flood-and-prune behaviors, state explosion for many groups, and reliance on periodic distance-vector exchanges, prompting studies at CMU, Stanford, and MIT that compared scalability with link-state and protocol-independent approaches. Operational mitigations drew on access control lists in vendor platforms, rate-limiting in multicast daemons, and network engineering practices applied at backbone operators such as UUNET, Sprint, and regional research networks like SURFnet and CESNET.

Extensions and Related Protocols

DVMRP influenced and coexisted with other multicast protocols and extensions, including sparse-mode and dense-mode concepts later formalized in PIM-SM and PIM-DM, multicast extensions to OSPF in MOSPF, and group management evolutions in IGMPv3. Protocol-independent multicast suites such as PIM incorporated lessons from DVMRP’s prune/graft semantics while avoiding dependence on unicast routing engines seen in DVMRP. Experimental overlays and measurement platforms such as MBone, PlanetLab, and trials conducted by RIPE NCC and ANRI-linked projects used DVMRP insights for multicast emulation, while academic and standards contributions appeared in proceedings and drafts by researchers affiliated with Bellcore, AT&T, Nortel Networks, and universities including Yale University and Cornell University.

Category:Routing protocols