A Loss Model for VBR Sources in ATM Networks

A variable bit rate source is modeled as a Markov modulated deterministic uid ow (MMDFF) process. Each state in the stationary discrete time Markov chain represents one of a nite number of deterministic messages of xed lengths and variable bit rates. At the user network interface this sequence is served at a constant bit rate with a bu er of xed length. The combined system forms a regenerative process, which is modeled as a bivariate Markov chain, representing the message type and the bu er content. The mean loss due to bu er over ow is explicitly found and is shown to be decreasing and convex in both bu er length and service rate. Tight bounds on the sensitivity of the expected loss with bu er length and service rate are derived.