Internet Protocol Networks

When using Link-State Protocols in IP networks, forwarding loops can occur transiently when the routers adapt their forwarding tables as a response to a topological change. In this Book, we present a mechanism that lets the network converge to its optimal forwarding state without risking any transient loops and the related packet loss. The mechanism is based on an ordering of the updates of the forwarding tables of the routers. Our solution can be used in the case of a planned change in the state of a set of links and in the case of unpredictable changes when combined with a local protection scheme. The supported topology changes are link transitions from up to down, down to up, and updates of link metrics. Typically we have chosen a Network consisting of routers. Link costs are generated randomly for simulation. Dijkstra’s algorithm has been employed for computing shortest paths. Routing tables are computed dynamically. Link failures are simulated. Avoiding transient loops in each case is demonstrated, by constructing a Reverse Shortest Path Tree using Spanning Tree Algorithm of the Graph.