Shared protection of virtual private networks with traffic concentration

In our paper we analyse algorithms that solve the optimal path search problem including the protection as well. We investigated the special case when multiple full mesh demand sets (forming VPNs) have to be built. We addressed the pro-active path based shared protection scheme and investigated heuristic algorithms to calculate the pair of paths. We formulated the problem generally without specialising to any particular network technology, i.e. the proposed methods can be used for various networks (e.g. ATM, MPLS, GMPLS, etc.). The service demands of VPNs are characterised by the bandwidth requirements of node-pairs (pipe-model). The input is the capacity matrix of the physical network and the traffic demand matrices of the VPNs. Our aim was to find efficient ways to protect the working paths. We analysed three different shared protection algorithms. All of them use Dijkstra's shortest path calculation, but with different edge weights. The demands are routed one-by-one, therefore the order in which they are processed matters. To eliminate this factor we used the simulated allocation scheme. We present numerical results from simulations on sample networks regarding the reserved capacity, the number of reserved edges, and the average path lengths.