Performance of bandwidth allocation strategies in fast packet-switched broadband ISDNs

Abstract

The main objective of this dissertation work is to investigate the performances of bandwidth allocation and bandwidth enforcement strategies for traffic controls in fast packet-switched broadband ISDNs(called ATM networks). In ATM networks, network congestion is controlled by limiting the traffic flow into the network so as not to reach the level causing unacceptable congestion. This is done by a prior bandwidth allocation for calls at call set-up and by the enforcement of the allocated bandwidth during the call holding time. But, before applying specific bandwidth allocation and enforcement strategies, the estimation of the performance of each traffic is needed in order to satisfy the grade-of-service for each traffic and to achieve the maximum efficiency of the network. For this purpose, we first studied the deterministic bandwidth allocation strategies for the integration of wide-band and narrow-band traffics. As a traffic control strategy in the deterministic bandwidth allocation mode, we set the access restriction on each type of traffic to protect overloading of one traffic and meet the GOS for each type of traffic. Also, as an improved strategy, we proposed a strategy that allows overflowing of bandwidth allocations over the access restrictions to use the idle channels reserved for there other traffic. We analyzed these allocation strategies using the matrix-analytic solution approach, and obtained the system time for NB calls, the blocking probability for WB calls, and the power combining the performance of the NB and WB traffics. Numerical results showed that the performance of the NB and WB traffics. Numerical results showed that the performance depends on the ratio of mean service times, the ratio of bandwidth requirements, each traffic load, and the cutoff values. These strategies can adapt to the varying traffic loads easily to meet the GOS required for each type of traffic by simply changing the restriction levels. We also showed that these strate...