A minimal cost WDM network for incremental traffic

A wavelength division multiplexed (WDM) network is considered for arbitrary topologies. The network allows optical signals to pass through nodes, which often results in less electronic and optoelectronic equipment than networks that do not, i.e., networks that only switch traffic electronically. A disadvantage of having optical pass-through is that there is less capability to switch tributary traffic streams and so there may be more blocking. However, it is shown that the network operates as well as a network with only electronic switching under a particular incremental traffic model. Examples are given that shows that the network can have lower cost when the cost is dominated by the line terminating equipment.