Multi-postpath-based lookahead multiconstraint QoS routing

Multiconstraint QoS (quality of service) routing is an essential mechanism for QoS-guaranteed services. Unfortunately, the multiconstraint QoS routing problem is NP-complete. In this paper, we propose a heuristic multiconstraint QoS routing scheme, MPLMR (multi-postpath-based lookahead multiconstraint routing). MPLMR is a routing scheme using an extended shortest-path algorithm. As in previous schemes such as TAMCRA and H_MCOP, MPLMR stores a limited number of subpaths between the source node and each intermediate node, and extends these subpaths toward the destination node. However, MPLMR uses an improved “lookahead” method to estimate the path length of the full path to which each subpath is extended. MPLMR then selects and stores the subpaths that have higher likelihood than other subpaths to be extended to feasible paths. We show via simulation that MPLMR has a smaller probability of missing a feasible path than competing schemes in the literature.