Bounds for optimal flow control window size design with application to high-speed networks

In this paper, we study the problem of optimal window size design that arises in flow control of communications protocols. We consider both the sliding and pacing window flow control mechanisms. We address the case of one data transfer session between a sender and a receiver. The assumption is that the sending station is transmitting a large volume of data in a burst to the receiving station. There are no restrictions on the distribution of arrival or service times at the intermediate packet switching stations in the communication path connecting the sender and receiver. Our criterion for optimal window size design is the maximization of the network power. We derive upper and lower bounds of the optimal window size that depend on the network performance characteristics. The main result of this paper is that the upper bound is a simple function of the number of hops, the round trip propagation delay, and the maximum throughput of the communication path. Our analysis and results incorporate the round trip propagation delay which may be very important in the design of window sizes for high-speed networks. This work could be applied to a Transmission Control Protocol (TCP) connection over a Wide Area Network (WAN), or to a virtual Advanced Peer to Peer Networking (APPN) session.