A flexible integrated multi-layer protection scheme for IP-over-WDM networks

This paper considers the problem of controlling signaling overhead in client-IP/MPLS layer due to a link failure in MPLS layer protection approach, while giving 100% guaranteed recovery assurance for admitted dynamic requests in integrated IP-over-WDM networks. In providing survivability, MPLS layer protection approach is more attractive from the perspective of resource usage. In this approach, an LSP is protected by providing a link-disjoint backup LSP between its end nodes. On the other hand, in optical layer protection, an LSP is protected by backup lightpath of each lightpath traversed by the LSP, The optical layer protection is attractive from the perspective of fast recovery and reduced signaling overhead. When MPLS layer protection is used, a single component failure (link or node failure) may require a large number of LSPs to be recovered. This causes a sudden increase in signaling messages in client-IP/MPLS layer, and raises the issue of signaling scalability in IP-over-WDM networks. In this paper, we propose a novel multi-layer protection scheme: Dynamic Heavily loaded Lightpath Protection scheme (DHLP), to control the signaling overhead in the client-IP/MPLS layer due to a link failure and at the same time to ensure guaranteed failure recovery for admitted requests using MPLS layer protection approach. To control the signaling overhead, we propose two methods of implementation in our scheme: DHLP based on path traversal (DHLP-pt) and DHLP based on network traversal (DHLP-nt). An attractive feature of our scheme is that it is flexible to achieve a desired tradeoff between the signaling overhead and blocking performance. Through simulation experiments, we demonstrate that our scheme is very effective to be practically used in networks.