A DELAY-EFFICIENT REROUTING SCHEME FOR VOICE OVER IP TRAFFIC By NARASINHA KAMAT A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA

of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science A DELAY-EFFICIENT REROUTING SCHEME FOR VOICE OVER IP TRAFFIC By Narasinha Kamat December 2002 Chair: Jonathan C. L. Liu Major Department: Computer and Information Science and Engineering Routing the packet flows through the network is a very important function and if done efficiently, it can contribute appreciably towards ensuring the desired levels of Voice over IP (VoIP) quality. Current implementations do not attempt to reconfigure the path of the flows in the case of loss of quality. There is no guarantee that the real-time traffic will maintain a single path throughout the transmission. Based on source routing, we propose a dynamic rerouting scheme called the BPAR scheme for voice traffic, in which the packet voice flows are dynamically reconfigured to be sent along different paths, if the default or the currently used path is discovered to be unsatisfactory. The proposed scheme consists of three steps: (1) a probing technique to measure conditions on the network, (2) an admission control and routing technique to send out the data on the most desirable route, and (3) a rerouting scheme to change the routes taken by the voice packets in case the chosen route becomes congested. Rerouting decisions are made after an initial probing of the chosen path and a periodic probing of the alternate paths when the chosen path is found to be congested. We