Designing an IP Link Topology for a Metro Area Backbone Network

Massive increases in IP (Internet Protocol) traffic have led to rapid deployment of IP-based networks in metropolitan (metro) areas. In order to facilitate this deployment, computer-based design tools are needed. One of the most difficult decisions that engineers face in designing an IP network is choosing the IP link topology (i.e., the set of router-to-router connections). This is especially complicated when it is also necessary to route these IP links over an underlying physical network of optical fibers. In this paper, the authors describe a new heuristic for simultaneously designing a backbone IP link topology for a metro area network, and routing these IP links over a given physical network. The IP network must be designed for survivability in the event of a network failure (i.e., the loss of a physical link, router or IP link). Initially, they employ a Construction Heuristic that explicitly considers the number of router-to-router connections that would be carried over each physical link. In this way it seeks to minimize the impact of any single physical link failure. An optional Local Search routine then attempts to improve on the solution by a sequence of topology changes. IP link routings are adjusted at each topology change. This heuristic is readily able to be incorporated into an interactive design tool. Some computational experience is described.