Hierarchical DistanceVector Multicast Routing for MBone分层向量距离MBONE组播路由.ppt

Hierarchical Distance-Vector Multicast Routing for MBone Presented by Nitin Deshpande Darpan Bhuva Outline Introduction Current MBone Scenario Hierarchical DVMRP Protocol Evaluation Other Issues Conclusion Introduction What is MBone? MBone is Multicast Internet Backbone Established in 1992 with 40 subnets in 4 countries Interconnected set of routers and subnets that provide IP multicast delivery in Internet Distance Vector Multicast Routing Protocol (DVMRP) MBone routers run a protocol to decide where to forward IP multicast packets Routers treat MBone topology as a single flat routing domain Entry for every subnet in the MBone Problem of additional processing resources and memory If nothing is done the MBone will collapse Solution lies in using Hierarchical Distance-Vector Multicast Routing for the MBone Use two-level hierarchy in which the MBone is divided into regions and the regions contain subnets The routing protocol in each region maintains topological information only for its own region, not for other regions The intra-region multicast routing may be accomplished by any number protocols, including DVMRP Inter-region protocol maintains information only about interconnection of regions and not about any internal topologies Inter-region routing protocol uses a modified version of DVMRP that computes multicast routes among regions rather than among subnets Advantages of using Hierarchical Routing Partitioning of regions allows different multicast routing protocols to be used in different regions Topological changes such as link or router failures are isolated to that particular affected region Limit on the maximum diameter of topology imposed by some protocols can be relaxed Current MBone Structure and Routing. Very few of the Internet routers support multicast routing Most of the MBone routing is done by general purpose routers which run multicast routing software MBone Components. Description of