Energy Efficient Network Resource Allocation Scheme for Hose Model

Given the exponential growth in telecommunication networks, more and more attention is being paid to their energy consumption. However, the often over-provisioned　wired network is still overlooked. In core networks, pairs of routers are typically connected by multiple physical cables that form one logical bundled link participating in　the intra-domain routing protocol. To reduce the energy consumption of hose-model　networks with bundled cables, we propose a scheme to deactivate the maximum number　of cables, and associated equipment, possible. A similar approach has been presented　for the pipe model, where the exact traffic matrix is assumed to be known. Due to　traffic　uncertainty, however, it is difficult for operators to have exact knowledge of the　traffic matrix. This traffic uncertainty can be avoided by using the hose model, which　specifies only the upper bounds of the egress/ingress traffic from/to a node. We introduce a mixed integer linear problem formulation that yields the optimal solution and a more practical and near optimal heuristic algorithm for large networks. Our performance evaluation results show that it offers up to 50% power reduction compared to shortest path routing.電気通信大学201

Preconfiguring ip-over-optical networks to handle router failures and unpredictable traffic

We consider the realization of traffic-oblivious routing in IP-over-Optical networks where routers are interconnected over a switched optical backbone. The traffic-oblivious routing we consider is a scheme where incoming traffic is first distributed in a preset manner to a set of intermediate nodes. The traffic is then routed from the intermediate nodes to the final destination. This splitting of the routing into two phases simplifies network configuration significantly. In implementing this scheme, the first and second phase paths are realized at the optical layer with router packet grooming at a single intermediate node only. Studies like [13] indicate that IP routers are 200 times more unreliable than traditional carrier-grade switches and average 1219 minutes of down time per year. Given this unreliability of routers, we consider how two-phase routing in IP-over-Optical networks can be made resilient against router node failures. We propose two different schemes for provisioning the optical layer to handle router node failures – one that is failure node independent and static, and the other that is failure node dependent and dynamic. We develop linear programming formulations for both schemes and a fast combinatorial algorithm for the second scheme so as to maximize network throughput. In each case, we determine (i) the optimal distribution of traffic to various intermediate routers for both normal (no-failure) and failure conditions, and (ii) provisioning of optical layer circuits to provide the needed inter-router links. We evaluate the performance of the two router failure protection schemes (in terms of throughput) and compare it with that of unprotected routing