| Classical IP routing provides only a "best effort" service, which makes routing simple, but which cannot meet the Quality of Service (QoS) requirements of streaming applications such as voice and video. End users negotiate their needs with the network using the Resource Reservation Protocol (RSVP). One model for the management of the network is Integrated Services (IntServ), which provides for per-flow negotiation, but does not scale to many connections. It was designed to work together with RSVP, and is well-suited to managing connections in access networks.; For backbone networks, where there may be hundreds or thousands of connections, Differentiated Services (DiffServ) was introduced. It assigns flows to classes, and uses only the classes to assign priority for packet handling in the routers. However, Diffserv routers do not understand RSVP messages. Independent Diffserv domains may use different IntServ-to-Diffserv mappings.; Within a DiffServ domain, path assignment and admission control are handled by a "Bandwidth Broker" (BB). However, the BB concept does not extend well to access networks. Inter-BB communication can be achieved using a proposed protocol, SIBBS.; By making each BB aware of RSVP messages, and extending SIBBS to carry RSVP messages between an ingress router and its associated BB, between adjacent BBs, and between the "last" BB on a path and the associated egress router, we develop an architecture that permits retaining the advantages of IntServ in the access networks, retaining the advantages of DiffServ in the backbone networks, and minimizing the changes that have to be made to existing DiffServ networks. The set of DiffServ domains appear to the end user as a series of RSVP nodes, and the routers inside the DiffServ domains need not be aware of RSVP messages at all.; In this way, the user's needs are met, without impacting the scalability of the backbone network. |
