ATM AVAILABLE BIT RATE CONGESTION CONTROL WITH ACTION DELAYS

Abstract

In the computer networks, congestion occurs when the resource demands exceeds the capacity which the network can provide. The presence of too many packets in the network, which the network is not able to cope with due to its limited resources and it begins losing packets, gives birth to the situation called congestion. ATM networks have to deal with the two types of congestions, first the long term congestion, caused by more traffic coming in than the system can handle, and second the short term congestion caused by burstiness in the traffic. In this . dissertation, two ABR congestion control algorithms are implemented. The problem of action delay in ABR congestion control is addressed. How switches manage to provide fairness in presence of action delays. In first controller the VBR sources are also present and switches have knowledge of number of controlled sources present, while in second controller VBR sources are omitted and switches don't have knowledge of number of controlled sources present. They use the presented algorithm to calculate this number, as this number is required so that switches could fairly distribute its available bandwidth among the controlled sources. One improvement is done by proposing a scheme, according to this scheme all the cells of those packets whose any cell is lost are simply discarded by the switches. As there is* no meaning in keeping these cells in queue, they will consume the precious buffer space and the available bandwidth of switches which can be given to other cells.