Abstract.

Calls that make large, persistent demands for network resources will be denied consistent service, unless the network employs adequate control mechanisms. Calls of this type include video conferences. Although overprovisioning network capacity would increase the likelihood of accepting these calls, it is a very expensive option to apply uniformly in a large network, especially as the calls require high bandwidth and low blocking probabilities. Such large calls typically require coordination of geographically dstributed facilities and people at the end systems. So it is natural to book the network requirements ahead of their actual use. In this paper, we present a new, effective admission control algorithm for booking ahead network services. The admission control is based on a novel application of effective bandwidth theory to the time domain. Systematic and comprehensive simulation experiments provide understanding of how booking ahead affects call blocking and network utilization, considering call duration, number of links, bandwidth, routing, and the mix of bookahead versus immediate arrival traffic. Allowing some calls to book ahead radically redices their chance of service denial, while allowing flexible and efficient sharing of network resources with normal calls that do not book ahead.

Lepidus. But small to greater matters must give way
Enobarbus. Not if the small come first