Various Performance Measures in ATM Switch Design:
1. Packet Loss Probability:
This parameter refers to the probability of a packet being dropped within the switch before it can be successfully transferred to its destination outlet. Overload conditions, internal design and shortage of buffer space are the three main reasons for packet loss in a switch.
This refers to the time required to switch a packet, right from the time it leaves the output module. The delay includes the time required to process a packet at every intermediate switching element.
There are two ways in which people define the throughput of the switch. According to one school of thought, throughput is equal to the port speed of an input link. According to other specification, throughput is the sum total of link rates of all input links. A better measure is the rate of output traffic rate and input rate ratio.
Throughput(of Switch) = Output Traffic Rate at Switch/ Input Traffic Rate at Switch
4. Design Complexity:
Switch design are generally a way of making a complicated switch design. A complex switch design invariably translates into either higher costs or limited switching capability.
Scalability refers to the ease with which a switch can be expanded. First, a scalable switch must be capable of supporting additional inlets without any deterioration in other performance measures. Secondly, it must also be capable of supporting any increase in the port speed of its inlets.
Cost is a significant factor in deciding the success or failure of a switch design. Quite often, performance efficient switch designs prove to be commercially unavailable option, thereby locating the design to a place in research papers only.
More articles: ATM