Multicast Routing in a Datagram Internetwork.
Abstract
Most local-area networks, as well as some other packet-switched networks, support multicast, the ability to address and deliver a packet to a set of destinations. Currently, when those networks are interconnected by routers or bridges to form an internetwork, the multicast service is either unavailable beyond a single network-as when using IP router or is offered in a way that significantly limits the scalability of the internetwork-as when using LAN bridges. To address those problems, we present a new service model for multicasting in a datagram (or connectionless) internetwork, and a set of new store-and-forward multicast routing algorithms to support that service model. The multicast service model, which we call the Host Group Model, is a natural generalization of the unicast service model offered by datagram internetworks. Multicast packets are delivered to each member of a multicast group with the same best-efforts reliability and performance as unicast packets to that member. Multicast groups may be of arbitrary size, may change membership dynamically, and may have either global scope, that is, with members located anywhere in the internetwork, or local scope, with members confined to a particular administrative domain. The new multicast routing algorithms to support the Host Group Model take the form of extensions to the two unicast routing algorithms most commonly used in network-layer routers-the distance-vector algorithm and the link-state algorithm and to the spanning-tree algorithm used by most datalink-layer bridges. In all cases, the delivery path of a multicast packet forms a tree, rooted at the sender, with copies of the packet being generated only at those points where the tree branches. The routing algorithms have low overhead, good performance, and scalability as good as, or better than, unicast routing. They may be used hierarchically, alone o
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1991
- Accession Number
- ADA325909
Entities
People
- Stephen E. Deering
Organizations
- Stanford University