Policy-based shared path protection for dual link failures

In this paper, we study novel shared path protection schemes that use different policies to deal with different dual-link failure scenarios in order to minimize total bandwidth consumption (or spare capacity allocation). Our work addresses two open problems. The first is minimum total bandwidth allocation under deterministic routing (i.e., when three link-disjoint paths, one active path and two backup paths are pre-selected for each connection). For the dual-link failure case, this problem is much more complex than a similar problem for the single-link failure case because one needs to decide which one of the two backup paths for a connection is preferred to reroute the traffic along its active path affected by a single-link (or a simultaneously dual-link) failure. We propose a new concept of policy, which specifies the preferred backup path to use, and study different policies (including no policy) which will result in different performances in terms of amount of bandwidth needed and different implementation complexity. The second open problem we address in this paper is to minimize additional bandwidth to be allocated for each connection under several different policies and adaptive routing in on-line setting. In this case, the solution entails how to find optimal paths for each connection. From our simulation results, we find that shared path protection with a policy can considerably reduce bandwidth consumption compared with shared path protection without a policy.