Fault tolerance in Unicast Cartesian networks by polygon walking (FTCN-PW)

The need for providing robustness to a network whether local area or enterprise network has lead to an extensive work on fault tolerance in recent years. The protocols developed vary in complexity based on the network topology. Cartesian network is a recent network topology developed to overcome many problems in current IP based routing like need for routing table updates and high processing capability support. The Cartesian network inherently provides very basic fault tolerance using the Arterial Direction Indicator (ADI) and Reachability Information (RI) stored and updated in the routers. The need to make a Cartesian network completely fault-tolerant by maintaining the key advantages of Cartesian network lead to an in depth research into fault tolerance.; A novel technique named Fault tolerance in Cartesian networks by polygon walking (FTCN-PW) is presented for providing fault tolerance to unicast Cartesian networks. The proposed scheme can tolerate (n-1) link failures in Cartesian routers, where n is the number of links connected to each router. Certain constraints are imposed on the Cartesian networks to implement FTCN-PW. Minimal state information is required to be stored in each router and four or less packets are exchanged on each link failure. The algorithm is loop free as it destroys any packet whose destination is found to be within the fault region. The algorithm also has the capability to select the path around the fault polygon so that the packet is successfully delivered to the destination.; The algorithm is developed for the proposed scheme. FTCN-PW is implemented on Optimum Network (OPNET) modeler 9.0 simulation tool. Five different test scenarios are developed and tested. Results are analyzed by comparing the time taken by a packet to reach the destination in a fault free environment and in a faulty environment.