Efficient Network Capacity Expansion by Differentiated WDM-Density with Bandwidth-Variable Virtual Direct Links

A cost-effective network capacity expansion method with novel bandwidth-variable virtual direct links (BV-VDLs) is proposed. BV-VDLs are located to traverse physical links expected to be heavily congested and highly dense path accommodation to BV-VDLs is applied. This strategy allows us to efficiently upgrade network capacity while keeping existing facilities unchanged. The capacity enhancement in dynamic path operation scenarios on real topologies can reach 20%.