GMPLS-based unified traffic engineering in IP over optical networks

In this paper, we propose a GMPLS-based unified traffic engineering scheme in optical networks to cooperate at both optical layer and IP/MPLS layer achieving high efficiency of resource utilization. In WDM networks, end-to-end all-optical paths, called lightpath, can be setup between two edge optical routers. The set of lightpath comprise of the logical topology of optical networks. In IP/MPLS layer, a LSP is established on the logical topology. With the traffic increasing or decreasing, it is expected that the logical topology can adapt to traffic changes. When the traffic in a lightpath increases and becomes extremely heavy, allotting a new lightpath can partition some traffic and relieve the congestion. On the contrary, when the bandwidth utilization in a lightpath is very low, the lightpath may be released to free up its occupied resources. Based on this idea, a topology-adaptive scheme is proposed and two adjustable thresholds are introduced which are employed to control the frequency of lightpath setup or release. Finally, several key issues in unified traffic engineering are presented.