In-service monitoring of quality of service in ATM networks using OAM cells

Congestion conditions in ATM switches may cause gradual deterioration in Qo S. QoS monitoring, using OAM, can accurately measure the overall quality of monitored parameters to detect such deterioration before the service quali ty has dropped below an acceptable level. Several factors can affect the ac curacy of the in-service QoS performance monitoring technique, such as the burstiness of the background traffic, network load, monitoring frequency, a nd bit rate. However, acceptable levels of accuracy can be achieved using O AM cells. Because of the fluctuations presented by VER video. QAM cells can measure their characteristics more accurately than CBR video. Also, for lo w bursty background traffic, cell delay variation (CDV) of VER is higher th an CBR. As the burstiness of the background traffic increases, CDV of CBR g rows faster than that of VER. At high burstiness. CDV of CBR is higher than VER. For all background data burstiness, the first multiplexer of the netw ork absorbs most of the CDV.