Combined routing and flow control in computer communication networks: A two-level adaptive scheme

The problem of designing combined routing and flow control strategies for packet-switched computer communication networks is considered in this paper and a new two-level adaptive scheme is presented. State dependent models for routing and input buffer limit flow control are introduced to facilitate formulating the problem, for which a solution in the framework of system stabilization is developed. The overall decision-making consists of a distributed computation of the routing parameters and the flow control parameters at the lower level of network nodes and a computation on a slower time-scale of a set of combined parameters by a supervisor (network control center) at a higher hierarchical level. The parameters are adaptively updated at both levels to improve the network performance with respect to a set of objectives concerning delay, throughput, and buffer utilization. Some implementational aspects of the algorithm are discussed and simulation results that illustrate the performance are presented. Major strong points of the present scheme are i) adaptivity to changes in load and/or network topology, ii) capability of handling different objectives individually at different hierarchical levels, and iii) consideration of capacity constrained nodal buffers in addition to capacity limited links, unlike in the earlier developed schemes, for a more realistic representation of network environment.