Graceful Adaptation of Guaranteed Performance Service Connections.

	Colin Parris, Giorgio Ventre, and Hui Zhang.

	Most of the solutions proposed to support real-time communication 
	services in a packet-switching network adopt a connection-oriented 
	and reservation-oriented approach. In this approach,
	the resource allocation and route selection decisions are made
	before the start of the application on the basis of resource
	availability and real-time network load at that time, and are usually
	kept for the duration of the application. However, such an
	approach shows two major limitations: 	first, the communication 
	service provided is usually fixed, with no or limited capability 
	of adaptation to dynamic changes in the clients' requirements; second, 
	a low utilization of the network may be observed. In this
	paper, we present a flexible management scheme that allows 
	graceful adaptation of guaranteed performance service connections. 
	Mechanisms have been devised to allow changing of the traffic 
	and performance parameters of a real-time communication during
	its lifetime. These mechanisms, together with an
	adaption policy, can make more efficient use of the network resources
	by performing cooperative, consenting, high-level multiplexing. 
	We distinguish between two types of adaptation: client 
	initiated adaptation and network initiated adaptation. We 
	give examples for both types and we also present results from
	simulation experiments to verify the correctness our proposal.