Fault tolerant core based tree

Abstract

Multicasting refers to transmit a single packet to a set of receivers that are members of a multicast group and it has an advantage of decreasing network traffic and load of sender. There are two classic types of trees widely used in today’s multicasting protocols. They are "source-based tree" and "shared tree" schemes. Source-based tree multicasting means that multicast delivery tree is built from each active source (sender) to its current members. Distance Vector Multicast Routing Protocol (DVMRP) and Multicast Open Shortest Path First (MOSPF) are examples of the source-based tree multicast routing protocols. On the contrary of source-based multicast routing protocols, each sender does not have their own multicast delivery tree and share multicast delivery tree within group members in shared tree approach. In this approach, a single node is designated to be the root of shared tree and the root takes charge of multicasting. Core Based Tree (CBT) multicast routing protocol is an example of the shared tree multicast routing protocols. In CBT, there is no recovery mechanism when core has fault. If core is in failure, a new core must be selected and all nodes must rejoin to new multicast group. To reduce these overheads, we propose a new multicast routing protocol, Fault Tolerant Core Based Tree (FTCBT) that has survivability of core. Having cross and double core structure, FTCBT can easily restore multicast tree when a core has fault. The FTCBT shows a good performance on tree restoration compared with CBT and MCBT when core fault is happened.