CONNECTION ADMISSION CONTROL IN ATM NETWORKS

Connection admission control is of vital importance for ATM networks. Any control strategy must balance network and user demands, satisfying user quality of service requirements while at the same time allowing the network to run efficiently. This paper provides a layered solution to the problem, with particular emphasis on real time services. A time-scale decomposition is given which aids understanding and analysis-buffers in the network are dimensioned to cope with variation on a short time-scale, and related to the way connections are policed, while on a longer time-scale the number of connections is limited to ensure the available bandwidth is not exceeded. The simplest way to limit connections is to allocate each connection its peak bandwidth. However it is possible to do much better than this and fit much more on to the network; this paper shows how it is possible to safely statistically multiplex connections by allocating an effective bandwidth to a connection. An adaptive call admission control is presented which allows the effective bandwidths to be estimated in real time, with no further information required from the user and which explicitly treats the trade-off between cell loss and call rejection.