Design of link-state alternative path routing protocols for connection-oriented networks

Alternative path routing (APR) can be used to achieve efficient routing in communications networks. Several approaches to APR in connection-oriented networks running a link-state routing protocol are described, and their performance evaluated using call-level simulations. A source routing paradigm is assumed where primary paths for calls are computed only at source nodes. However, depending on the approach, alternate paths can be computed at source, intermediate or even destination nodes. Simulation results are presented to show that, if not carefully used, APR may degrade network performance under heavy load. Finally, two methods of controlling APR under heavy load are described and their performances demonstrated