A Protection-based Approach to QoS in Packet over Fiber Networks

We propose a novel approach to Quality of Service, intended for IP over SONET (or IP over WDM) networks, that offers end-users the choice between two service classes defined according to their level of transmission protection. The first service class (called Fully Protected (FP)) offers end-users a guarantee of survivability: all FP traffic is protected in the case of a (single) failure. The second service class (called Best-Effort Protected (BEP)) does not offer any specific level of protection but is cheaper. When failures occur, the network does the best it can by only restoring as much BEP traffic as possible. We motivate the need for two classes of protection services based on observations about backbone network practices that include overprovisioning and an ongoing but unbalanced process of link upgrades. We use an ILP formulation of the problem for finding primary and backup paths for these two classes of service. As a proof of concept, we evaluate the gain of providing two protection services rather than one in a simple topology. These initial results demonstrate that it is possible to increase the network load (and hence revenue) without affecting users that want complete survivability guarantees.