Window selection in flow controlled networks

ABSTRACT

The end-to-end window scheme is a popular mechanism for flow and congestion control in packet switched networks. The window scheme may be implemented in the transport layer protocol (like in TCP), or in the source-to-destination protocol(like in ARPANET), or in the network layer protocol (like X.25). In many implementations, the window size is chosen at connection set up time. In this paper, we provide guidelines for window selection. Specifically, we show that if the network becomes overloaded, that is, the offered load exceeds network capacity, then the selection of user windows has a critical impact on individual user throughputs. Thus, user windows should be chosen judiciously, so as to satisfy a well defined “fairness” criterion. We formulate the optimal window assignment as a mathematical programming problem, and show that the exact solution is computationally impractical because of the combinatorial nature of the problem and the complexity of the underlying multiple chain, closed network of queue model. We then develop a heuristic approach which is computationally very efficient and provides nearly optimal solutions. Numerical results are provided to illustrate and validate the method.

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.1 Network Architecture and Design
          Subjects: Packet-switching networks

Additional Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS

General Terms:
Design, Experimentation, Management, Theory