Local restoration algorithm for link-state routing protocols

Link-state protocols such as OSPF are the dominant routing technology in today's Internet. Despite their many advantages, these protocols require the flooding of new information across the entire routing area after changes in any link state (e.g., link failures). As the routing area grows or the frequency of link-state changes increases, the overhead (in terms of bandwidth and processing cost) of flooding becomes prohibitive. Furthermore, such flooding over a large area will cause temporary inconsistency of link states among many routers, potentially creating many transient routing loops that can last for a long time. This limits the scalability of the routing protocols to large routing areas. To overcome such problems, we present in this paper a novel algorithm that minimizes the amount of information distributed by link-state routing protocols. Upon a link failure, our algorithm will distribute the link-state changes to the minimum number of routers that are needed to ensure loop-free routing. Moreover, implementing our algorithm requires only a simple extension to any existing link-state protocol.