Cost-effective network capacity upgrade by heterogeneous wavelength division multiplexing density with bandwidth-variable virtual direct links

Abstract

A cost-effective and fast network capacity upgrade with what we believe to be novel bandwidth-variable virtual direct links (BV-VDLs) is proposed. BV-VDLs are designed to pass through the physical links expected to be heavily congested and realize very dense path accommodation. We adopt cut-set analysis to identify the links likely to be heavily congested; however, high computation loads will be incurred in finding all the cut-sets, and justifying these loads is essential. Thus a simple-path-search based graph splitting method is proposed that substantially shortens the calculation time. This strategy allows us to efficiently upgrade network capacity while keeping existing facilities unchanged and can be installed in networks in operation. The proposal is also valid for enhancing the capacity of new networks. The capacity enhancement can reach 13%–33% even in dynamic path operation scenarios on the real topologies of pan-European, North American, and Japanese networks.