A multipath framework architecture for integrated services

A major concern with the IETF proposed integrated services (Intserv) architecture for providing quality of service is that the amount of reservation state it stores in the routers and the RSVP protocol it uses to maintain the consistency of reservation state may not be scalable to high-speed backbone networks. Because of the large number of flows in the backbone network, the refresh messages associated with RSVP's soft-state mechanism, apart from consuming memory, bandwidth and computing power, can experience significant queuing delays and prevent correct functioning of the soft-state mechanism. For the refresh mechanism to scale, therefore, the reservation state size must be bounded so that delays of time-sensitive refresh messages can also be bounded through adequate bandwidth allocation. Vutukury and Garcia-Luna-Accves (see. Proc. of ICCCN, 1999) described the scalable multipath aggregated routing architecture (SMART) In which the reservation state size is a function of number of destinations rather than number of flows in the network. In this paper, we describe a reservation protocol (AGREE) to maintain this reservation state aggregated along the multipaths. The AGREE protocol, like RSVP, uses soft-states, but also ensures that the refresh messages experience bounded queuing delays. The SMART architecture combined with AGREE protocol is significantly more scalable compared to the Intserv/RSVP model.