Comparison studies on recovery schemes of combining protection and restoration at different layers in IP over WDM networks

In this paper, we investigate the problem of protection and restoration scheme for IP over wavelength division multiplexing (WDM) networks. Protection and restoration are important recovery mechanisms in networks. The emergence of MPLS and its extension, MPλS, opens up new possibilities for developing simple integrated protection/restoration schemes that can be coordinated at both the IP and optical layers. However, on the multi-layer network, e.g. IP over WDM with MPLS network, which recovery mechanism is deployed at which layer is an interesting issue. It raises many questions and challenges, given the characteristic of optical aggregated lightpath and relatively coarse traffic granularity. This paper first presents an overview of existing MPLS/ MPλS recovery mechanisms. Then we propose a series of joint two-layer recovery schemes for IP-centric WDM based optical networks where the optical layer will take the recovery actions first and subsequently the upper IP layer initiates its own recovery mechanism, if the optical layer does not recover all affected services. A simulation-based experiment studies and compares the performance of combinations of protection and restration in joint two-layer recovery schemes. The impacts of several network parameters on recovery performance are also studied in the paper, e.g., shared or dedicated protection and path or link switching.