6533b85bfe1ef96bd12ba975

RESEARCH PRODUCT

SUBOPTIMAL-OPTIMAL ROUTING FOR LAN INTERNETWORKING USING TRANSPARENT BRIDGES

subject

description

The current standard transparent bridge protocol IEEE-802.1D is based on the Spanning Tree (ST) algorithm. It has a very important restriction: it cannot work when the topology has active loops. Therefore, a tree is the only possible interconnection topology that can be used. The ST algorithm guarantees that the active topology is a tree discarding lines that form loops. However, because of this, network bandwidth cannot be fully utilized. Moreover, trees have a very serious bottleneck near the root. This paper proposes a new transparent bridge protocol for LAN interconnection that allows active loops. Therefore, strongly connected regular topologies like tori, hypercubes, meshes, etc., as well as irregular topologies can be used without wasting bandwidth. As loops provide alternative paths, the new protocol (named OSR for Optimal-Suboptimal Routing) uses optimal routing or, in the worst case, suboptimal routing.