Dell PowerSwitch S4128F-ON OS10 Enterprise Edition User Guide Release 10.4.3.0 - Page 995

You can obtain a snapshot of the buffer statistics for the different buffer objects, such as a snapshot of all ingress priority-groups associated to a port, all egress unicast queues bound to a port, and so on. You can enable BST at the global level. OS10 tracks buffer utilization and provides the maximum peak statistics value over a period of time and the current value of the monitored BST counter. Use the buffer-statistics-tracking command in SYSTEM-QOS mode to enable BST: OS10# configure terminal OS10(config)# configure system-qos OS10(config-sys-qos)# buffer-statistics-tracking Clear the counter You can choose to reset the peak buffer utilization value and determine a new peak buffer utilization value. Use the clear qos statistics type buffer-statistics-tracking command to clear the tracked value and to refresh this counter. BST tracks peak buffer utilization over a period of time. At any given point in time, the peak buffer usage from the past is displayed. For example, if you enable BST at time T0 and use the show command to view the peak buffer utilization value at time T1, the peak usage between T0 and T1 is displayed. If you view the peak buffer utilization again at time T2, the peak usage between T0 and T2 is displayed. However, if you clear the counter using the clear qos statistics type buffer-statistics-tracking command at time T3 and view the peak buffer utilization at time T4, the peak usage between T3 and T4 is displayed. NOTE: When BST is enabled, if you make any configuration changes that affect the priority group or priority mapping configuration, such as removal of class map, addition of class map to policy map (nqos), and so on, be sure to clear the buffer statistics using the clear qos statistics type buffer-statistics-tracking command to view the actual peak buffer utilization for the current configuration. Advantages of BST include: • Detecting microburst congestions • Monitoring buffer utilization and historical trends • Determining optimal sizes and thresholds for the ingress or egress shared buffers and headroom on a given port or queue based on real- time data NOTE: BST is not supported on the S4248F-ON and S5148F-ON platforms. After you disable BST, be sure to clear the counter using the clear qos statistics type buffer-statistics-tracking command. QoS commands bandwidth Assigns a percentage of weight to the queue. Syntax Parameters Default Command Mode Usage Information bandwidth percent value percent value - Enter the percentage assignment of bandwidth to the queue, from 1 to 100. Not configured POLICY-MAP QUEUE If you configure this command, you cannot use the priority command for the class. Quality of service 995