In-service monitoring of quality of service in ATM networks using OAM cells
J. García-Hernández, M. Ghanbari · IEE Proceedings - Communications · 1999
Congestion conditions in ATM switches may cause gradual deterioration in QoS. QoS monitoring, using OAM, can accurately measure the overall quality of monitored parameters to detect such deterioration before the service quality has dropped below an acceptable level. Several factors can affect the accuracy of the in-service QoS performance monitoring technique, such as the burstiness of the background traffic, network load, monitoring frequency, and bit rate. However, acceptable levels of accuracy can be achieved using OAM cells. Because of the fluctuations presented by VBR video, QAM cells can measure their characteristics more accurately than CBR video. Also, for low bursty background traffic, cell delay variation (CDV) of VBR is higher than CBR. As the burstiness of the background traffic increases, CDV of CBR grows faster than that of VBR. At high burstiness, CDV of CBR is higher than VBR. For all background data burstiness, the first multiplexer of the network absorbs most of the CDV.