A Comparative Study of Fast Protection Schemes in WDM Mesh Networks

Abstract

The concept of p-cycle (Preconfigured Protection Cycle) allows fast and efficient span protection in WDM mesh networks. Compared to a simple p-cycle, a non-simple p-cycle can traverse a node or span multiple times. As a result, non-simple pcycles can better explore mesh connectivity of a network. On the other hand, the recently proposed PXT (Pre-Cross-Connected Trail) concept removes the cycle constraint by allowing arbitrary protection trails. In this paper, we carry out a comparative study among these fast protection schemes, and formulate ILPs (Integer Linear Programs) for non-simple p-cycle and PXT design. As far as we know, our ILP for non-simple p-cycle design is the first one without candidate cycle enumeration, and our ILP for PXT design is the first one proposed in this area. Based on our ILPs, we find simple, non-simple p-cycle and PXT solutions for a simple network. We show that the required spare capacity for 100% protection in each scheme is reduced in the same order above.

Monitoring Trail: On Fast Link Failure Localization in All-Optical WDM Mesh Networks

“…1c), this dramatically reduces the required number of m-cycles from O(||E||-||V||+1) to O(log 2 ||E||). Compared with simple cycles, non-simple cycles are more flexible in exploiting mesh connectivity of a network [18], but such flexibility is still limited by the cycle constraint. For example, without the aid of link-based monitors, link failures in a two-edge cut cannot be distinguished by any simple or non-simple m-cycle solution.…”