Hop-by-hop quality of service routing

Based on the self-adaptive multiple constraints routing algorithm (SAMCRA), an improved and exact version of our QoS routing algorithm, the tunable ac curacy multiple constraints routing algorithm (TAMCRA) we have investigated QoS routing in a hop-by-hop manner because it forms the basis of IP networ king as e.g. in OSPF. In particular, we studied 'hop-by-hop destination bas ed only' (HbHDBO) QoS routing that ignores the source and previous path his tory (as in current IP routing). We demonstrate that an exact QoS algorithm assures the avoidance of routing loops in this HbHDBO setting. However, de spite the use of an exact QoS routing algorithm as SAMCRA, the exact soluti on cannot be guaranteed with HbHDBO routing. Fortunately, large simulation results on various sizes of random graphs show that the overall quality of the HbHDBO QoS routing is remarkably good. Finally, we show that, by using active networking as opposed to current IT routing, exact QoS routing in a hop-by-hop way can be guaranteed. (C) 2001 Elsevier Science B.V. Ail rights reserved.