TYPE-OF-SERVICE ROUTING IN DATAGRAM DELIVERY SYSTEMS

The Internet is expected to support various services, including best-e ffort services and guaranteed services. For best-effort services, we p ropose a new approach to achieving type-of-service (TOS) classes with adaptive next-hop routing, We consider two TOS classes, namely, delay- sensitive and throughput-sensitive, As in routing protocols such as OS PF and integrated IS-IS, each node has a different next-hop for each d estination and TOS class, Traditionally, a node has a single FCFS queu e for each outgoing link, and the next-hops are computed using link me asurements, In our approach, we attempt to isolate the two traffic cla sses by using for each outgoing link a separate FCFS queue for each TO S class; the link is shared cyclicly between its TOS queues, The nest- hops for the delay-sensitive traffic adapts to link delays of that tra ffic, The next-hops for the throughput-sensitive traffic adapts to ove rall link utilizations. We compare our approach with the traditional a pproach using discrete-event simulation and Lyapunov analysis (for sta bility of routes). Our approach offers lower end to-end delay to the d elay-sensitive traffic. A related property is that the routes for the delay-sensitive traffic are more stable, i.e., less oscillations. An u nexpected property is that the overall end-to-end delay is lower, beca use the throughput-sensitive traffic moves away to under-utilized rout es.