RCBR - A SIMPLE AND EFFICIENT SERVICE FOR MULTIPLE TIME-SCALE TRAFFIC

Variable bit-rate (VER) compressed video traffic is expected to be a s ignificant component of the traffic mix in integrated services network s, This traffic is hard to manage because it has strict delay and loss requirements while simultaneously exhibiting burstiness at multiple t ime scales, We show tl;at burstiness over long time scales, in conjunc tion with resource reservation using one-shot traffic descriptors, can substantially degrade the loss rate, end-to-end delay, and statistica l multiplexing gain of a connection, We use large-deviation theory to model the performance of multiple time-scale traffic and to motivate t he design of renegotiated constant bit rate (RCBR) service, Sources us ing RCBR service are presented with an abstraction of a fixed-size buf fer which is drained at a constant rate, They may renegotiate the drai n rate to match their workload, Because all traffic entering the netwo rk is constant bit-rate (CBR), RCBR requires minimal buffering and sch eduling support in switches, We show that the service is suitable for both stored and online video sources, An RCBR source must decide when to renegotiate its service rate and what the new service rate should b e, We present: 1) an algorithm to compute the optimal renegotiation sc hedule for stored (offline) traffic and 2) a heuristic to approximate the optimal schedule for online traffic, We also discuss measurement-b ased admission control (MBAC) for RCBR traffic, Simulation experiments show that RCBR is able to extract almost all of the statistical multi plexing gain available by exploiting slow time-scale variations in tra ffic, Moreover, simple admission control schemes are sufficient to kee p the renegotiation failure probability below a small threshold while still offering high link utilization, Thus, we believe that RCBR is a simple, practical, and effective service for carrying multiple time sc ale traffic.