Reducing the size of routing tables for large-scale network simulation

In simulating large-scale networks, due to the limitation of available resources on computers, the size of the networks and the scale of simulation scenarios are often restricted. Especially, routing tables, which indicate the directions to forward packets, are considered to consume memory space. A simple general routing table requires O(N/sup 2/) space where N is the number of nodes. An algorithmic routing approach recently proposed by Heung et al. only requires O(N) space for representing routing tables, however this can be applied in the case that all the routes between two nodes are contained in a spanning tree (i.e. very limited routing strategies are allowed). We propose a new method to reduce the size of routing tables under any routing strategy. Given a general simple routing table, our method represents a routing table as the combination of an algorithmic routing based table and a general routing table, by translating a part of the given general routing table into the algorithmic routing based one. In order to reduce the size of the routing table, we find a (near-optimal)algorithmic routing based table that represents most part of the given routing table. Our experimental results have shown that our method could reduce the size of the table to 10 % of the given routing table in hierarchical networks.