ATM traffic-policing and traffic-shaping measurements

ATM (Asynchronous Transfer Mode) defines several Quality of Service (QoS) levels such as CBR (Constant Bit Rate) and VBR (Variable Bit Rate). Each service has parameters that are associated with its performance characteristic. The parameters used for specifying CBR service are Peak Cell Rate (PCR) and Cell Delay Variation Tolerance (CDVTOL). The parameters used for specifying VBR service are PCR, SCR (Sustainable Cell Rate), and BT (Burst Tolerance). The network takes responsibility for monitoring and policing the traffic of each VCC/VPC at the ingress of the network. The CPE needs to traffic shape at the ingress of the network in order to meet the contracted QoS requirements. Measurement procedures and tools are required in order to provide a means of tuning the CPE and network service to meet the customer's end-to-end QoS expectations. The following paper describes how the Generic Cell Rate Algorithm variables can be adjusted to provide acceptable levels of QoS in a mixed VBR, and CBR environment. In addition, the paper examines a methodology for measuring the performance of VBR and CBR services. The authors uses this information to build a QoS measurement tool.