Abstract In this paper, we propose an enhanced p-cycle (preconfigured protection cycle) scheme for WDM mesh networks with QoS constraints. In the previous researches on p-cycle, it is assumed that user’s connection has a bi-directional connectivity and the same bandwidth on both direction. Therefore it is difficult to apply p-cycle based link protection to uni-directional connections for multicasting or asymmetric broadband multimedia communications with bi-directional connectivity. And it didn’t consider QoS of backup path.
We enhanced the p-cycles to accomodate uni-directional connections for multicasting or asymmetric bandwidth communications with bi-directional connectivity. And we propose a selection procedure of p-cycle to assure QoS of backup path. We were able to reduce a required backup bandwidth by applying a uni-directional p-cycle concept to asymmetric broadband multimedia communication environment. The proposed p-cycle selection procedure is applied to the U.S. sample network to evaluate whether the configured p-cycles can support QoS constraint of working path and backup path.