NetLets: measurement-based routing daemons for low end-to-end delays over networks

Routing in the Internet is based on the best-effort mechanism, wherein the routers generally forward packets to minimize the number of hops to the destination. Furthermore, all packets of a type are treated the same independent of their size. We propose the framework of NetLets to enable the applications to send data packets to the destination with certain guarantees on the end-to-end delay. NetLets employ in situ instruments to measure the effective bandwidth and propagation delays on the links, and compute the paths with minimum measured endto-end delay for data packets of various sizes. Based on experiments over local area networks, the paths selected by NetLets indeed achieve the minimum end-to-end delay, and our method outperformed the best-effort mechanism based on the hop count. We also describe an implementation of NetLets over the Internet to illustrate their viability for wide-area networks. q 2002 Elsevier Science B.V. All rights reserved.