Why IP Over WDM?
Typically, the network consists of multiple layers, from the IP to the ATM to the SDH/SONET to the optical to the fiber duct. Each one of those layers offers their own flexibility, advantages, and features. The goal is to optimize the network in order to take advantage of the capabilities of a particular layer in a certain part of the network. For example, it does not make sense to do IP layer forwarding with traffic from New York to San Francisco at two or three routers in between. It would make much more sense to carry the traffic that is originating in New York to San Francisco in one single hop within the optical domain completely. That will provide higher performance, protocol transparency, and cost optimization. Currently, there are too many layers in the protocol stack. IP is running over a frame relay and/or ATM layers. SONET/SDH, which is quite dominant, is also included here. Now, the emergence of WDM results in IP-over-ATM-over-WDM or IP-over-SDH-over-WDM. Multiplicity of th
