Fast dissemination of link states using bounded sequence numbers with no periodic updates or age fields

Abstract

Routing protocols based on the distribution of link-state information rely on sequence numbers to validate information that a router receives. A fundamental problem is to bound the sequence-number space. We propose a new sequence-number reset algorithm that needs neither periodic retransmissions nor age fields. It is based on a recursive query-response procedure and is designed to handle resource failures during operation. This new algorithm is applicable to routing protocols based on both flooding and selective distribution of link-state information. The correctness of the algorithm is verified in the context of selective dissemination of topology information, and its complexity analyzed. Because the reset algorithm does not use any aging, the distribution of new link-state information or the purging of old information is always done in a time proportional to the time it takes to traverse the network.