QoS support for multimedia sessions in the Diffserv-Aware ATM based MPLS network

Abstract

Communication links with high data throughput capacity (bandwidth) and low latency are the prime requirements to support multimedia applications such as voice on demand services, video conferencing and virtual reality. These applications require a particular Quality of Service (QoS) defined by the delivery of voluminous continuous media (audio or video) data packets over the network with a certain delay and jitter bound. Best-effort service is unsuitable for all the above-mentioned requirements because all packets compete equally for network resources. The necessity to develop better QoS solutions to address these issues of multimedia transmission has led Internet Engineering Task Force (IETF) to develop Integrated Services (Intserv) architecture with Resource Reservation Protocol (RSVP) and Differentiated Services (Diffserv) architecture. In Intserv architecture, RSVP is used to set up paths and reserve resources towards receiver before sending data. But in large networks it enjoys the drawbacks of scalability. In this thesis a new flow-based admission control algorithm has been proposed for routing the multimedia traffics with a predefined QoS through a Diffserv-Aware ATM based MPLS network. The routers in the networks work as distributed admission controllers to find a particular path satisfying a particular QoS. A scheme of rerouting multimedia flows during the congestion in a particular part of the network is also presented. Admission controlling would be done by the router connected to the source of the multimedia traffic by observing the current delay and jitter of the calculated path for the multimedia request. Virtual Circuits (Ve) in an ATM-based MPLS network are used to reduce end-to-end delay and router load and for higher throughput. In the proposed technique, QoS of a multimedia session can be violated if congestion occurs in a router on its path. Diverting traffic towards low congested path is a common technique used by the routers to avoid congestion in the network. Consideration has been given in one particular rerouting option during congestion, to guarantee the overall QoS. However, this rerouting decision would be made by the source of the multimedia traffic. Unlike the \ Vll traditional routing of data packets, the intermediate routers on the flow of a multimedia session have nothing to do with this routing scheme. Based upon the knowledge of the customers' Service Level Agreements (SLAs), simulation results are also presented that show the improvement of session success rate by rerouting the multimedia traffic to relatively under-utilized links during congestion.