Abstract: TSQR (two-way selective probing QoS routing), a distributed algorithm for NPCPCPO (path-constrained path-optimization) problem is proposed. Taking example for DCLC (delay-constrained least-cost) problem that belongs to PCPO problem, according to TSQR algorithm, source node sends two kinds of probing messages(MinCProbe1/MinDProbe1, MinCProbe2/MinDProbe2) to destination node based onthe minimum-cost path and the least-delay path between them, and these two kinds of probing messages correspond to two kinds of path-selection operations; themid nodes collect the path information that a message has traversed, and mutatethe message to probe in another direction while sending the message in originaldirection; destination node selects one or more paths from feasible paths set. TSQR can remove loop paths naturally, and has low storage and computation complexity. Simulation results show that TSQR has best path-optimization performance compared with some other referenced algorithms.

Key words: quality-of-service, routing, path-constrained path-optimization, delay-constrained least-cost