The evolution of transport network survivability

The bandwidth explosion ushered in by the popularity of the Internet has sp urred the recent acceleration in the development and deployment of equipmen t supporting packet-based services. This - coupled with the widespread depl oyment of dense wavelength-division multiplexed systems in the core transpo rt network to satisfy the corresponding increase in capacity demand - has l ed network planners to reconsider traditional approaches to network surviva bility. Existing architectures for transport network survivability were dev eloped based on a ubiquitous circuit-switched/TDM network paradigm. As tari ffed services increasingly migrate from circuit-switched/rDM to packet-swit ched/DWDM networks, survivability architectures must also evolve to meet th e service requirements of this "new" packet-switched/DWDM network paradigm. In this article we begin with an overview of existing strategies for provi ding transport network survivability, followed by an analysis of how the ar chitectures for network survivability may evolve to satisfy the requirement s of emerging networks.