IMA: technical foundations, application and performance analysis
Using WAN established infrastructure, one of the main problems ATM network planners and users face, when greater than T1/E1 bandwidth is required, is the disproportionate cost associated with T3/E3 links. The technology to cover the gap between T1/E1 and T3/E3 bandwidth at a reasonable cost is known as inverse multiplexing for ATM (IMA). IMA allows multiple T1/E1 lines to be aggregated to support the transparent transmission of ATM cells over one single virtual trunk. In this paper, the fundamentals and major applications of IMA technology are described. Also, the behavior of IMA multiplexers is carefully analyzed and a method to dimension them proposed. For this purpose, an IMA simulation tool has been developed. The IMA simulator permits the study of individual devices and the evaluation of the end-to-end performance of a logical trunk under several ATM input traffic patterns. The analytical study is based on the comparison with an M/D/C/(N+C) queue system. Under Poisson input traffic, an approximation for the cell loss ratio (CLR) is derived and an estimate of the cell delay in an IMA multiplexer obtained. In addition, the suitability of these results for two types of bursty traffic is investigated.
inverse multiplexing for atm network planning modeling performance evaluation