PERFORMANCE OF AN ADAPTIVEROUTINGOVERLAY UNDER DYNAMIC LINK IMPAIRMENTS

We proposean adaptive software routing overlay toimprovetheperformance ofTCP/IP-based internets overlinks withdynamicimpairments. Therout- ingoverlay adaptively distributes traffic overa setof alternative paths basedonreal-time link status information provided bya systemofnetworksensors. Therouting overlay alsoprovides explicit ratefeedback torate-aware TCPclients, allowing themtoachieve higher throughputs thanlegacy clients understatic linkloss anddelay impair- ments.We present performance results fromacollection ofEmulabexperiments onsimple network topologies with dynamiclinkimpairments. Theresults showthatthe adaptive routing overlay achieves significantly higher bulk file transfer throughput thanlegacy systems inthepres- enceoflinkimpairments. Sensor-based adaptive routing provides substantial gainsinTCP throughput evenfor legacy TCPclients. Whenrate-aware TCPclients areused, theperformance gainoftheadaptive routing overlay with respect tolegacy systems improves dramatically.'