Admission of high priority real-time calls in an ATM network via bandwidth reallocation and dynamic rerouting of active channels

A high-priority real-time connection is denied admission to an ATM network if insufficient bandwidth is available along all suitable paths through the network. Bandwidth reallocation and dynamic active channel rerouting are techniques that allow a node to select lower-priority channels and reallocate their bandwidth to the new higher-priority connection being admitted. The selected lower-priority channels must then be rerouted through the network so that their QoS requirements can still be satisfied. A local detouring technique, using backup channels, is employed so that reroutes can be handled quickly and efficiently, without violating the QoS requirements of the rerouted channels. Techniques are described which ensure that transmitted data is received on time and in sequence, which is essential for real-time communications. The SANRoP (Simulator for ATM Network Routing Protocols) cell-level discrete event simulator was developed to simulate these protocols in an ATM network in order to determine how well they perform.