Survivable IP link topology design in an IP-over-WDM architecture

The design of an IP link topology (i.e., deciding which set of router-to-router communication links to establish) is an important factor in determining both the cost and performance of an IP network. In an IP-over-WDM architecture, these router-to-router links consist of wavelengths carried over an optical network. Each physical link in the optical network can carry multiple router-to-router wavelengths. The IP network must be designed for survivability in the event of an optical network failure (i.e., the loss of any given physical link or optical switch). Therefore, if there are particular physical links that carry an inordinate number of router-to-router wavelengths, a substantial amount of capacity may be required elsewhere in the IP network in order to assure survivability. In this paper, we describe a heuristic for designing an IP link topology in an IP-over-WDM architecture. In choosing which IP links to establish, the heuristic explicitly considers which router-to-router wavelengths that would be carried over each physical link and the various failure scenarios that could result. It is particularly targeted toward large, sparse networks. Some computational comparisons are included.