  We present an extension of the window flow control analysis by R. Agrawal
et.al. (Reference [1]), C.-S. Chang (Reference [6]), and C.-S. Chang et. al.
(Reference [8]) to a system with random service time and fixed feedback delay.
We consider two network service models. In the first model, the network service
process itself has no time correlations. The second model addresses a two-state
Markov-modulated service.
