Connection Admission Control (CAC) Algorithms

CAC algorithms should predict the fraction of the network resources that will be consumed by the traffic generated by each application. One of the most important resources is channel bandwidth. The problem of bandwidth allocation, in particular in ATM environments, has been addressed in a number of works.

Traffic descriptors, in particular those standardized by the ATM forum (UPC), play an important role in conveying the minimum amount of traffic information to the algorithms. Briefly, in many of these works, the loss probability is estimated based on the traffic descriptors and amount of available bandwidth.

The CAC module implements two CAC algorithms [#!guerin91!#,#!elmitra95!#], which are useful to provide a basis for comparison against laboratory measurements and other possible CAC algorithms. The CAC module calculates the effective capacity and the number of admitted sources based on the traffic descriptors specified by the user, the buffer size, link capacity, and the desired QoS. As shown in Figure () the user can specify the following parameters:

Transmission Capacity

This parameter specifies the transmission capacity of network node in (bytes/s).

Buffer Size

The size of the buffer in bytes, used in the effective capacity calculations.

QoS - Loss Probability

The desired loss probability.

The traffic descriptors used for each CAC algorithm are as follows.