Call performance studies on the ATM forum UNI signalling implementations

Abstract

Asynchronous Transfer Mode (ATM) is widely accepted as the transfer mode for Broadband Integrated Services Digital Networks (B-ISDN). As ATM networks provide connection-oriented services, signalling is an essential component of these networks. The performance of the signalling system is crucial in determining the scalability of the network. Call performance measurements on two different ATM switches were carried out using a broadband network analyzer. Calls are generated according to a deterministic/Poisson distribution and various components of the call set up delay are analyzed. The probability distribution of the delays is obtained and the correlation between the set up delay and its different constituents is established. It is observed that the delays at the calling and the called user entities of the UNI form a major component of the call set up delay. The average call set up delay is found to be 21 and 27 ms, respectively, when a single switch is involved in call set up and 50 ms when two switches are involved in call set up. With simultaneous call arrivals, though with higher delays, both the switches are found to establish calls at the rate of 100 calls/s.