Advanced multilayer resilience scheme with optical restoration for IP-over-DWDM core networks

Future IP-over-DWDM networks improve economics not only from eliminating grey interfaces substituted by coloured interfaces directly plugged into the packet routers. An even major leverage reducing cost of a traditionally over-dimensioned packet network can be attributed to architectural aspects including advanced multilayer resilience. This is enabled by newly available, flexible optical technology allowing a more dynamic mode of operation of IP-over-DWDM networks. The flexible optical layer can be used to offer service-differentiated resilience combining IP protection with optical restoration in IP-over-Optical networks. By this approach, higher interface utilization can be achieved reducing capital expenditures. In addition, this also improves the overall network availability and reduces operational expenditures. After a short overview on the key enabling technologies for flexible IP-over-DWDM interworking, the authors provide guidelines for the cost-efficient IP topology design of multilayer IP-over-DWDM core networks and show that for a German backbone reference network the combination of IP A/B-plane protection with optical restoration requires 24 - 27% fewer line interfaces compared to the multilayer optimized bypass network design.