Users Guide

You can obtain a snapshot of the buer statistics for the dierent buer 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 buer 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 buer utilization value and determine a new peak buer 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 buer utilization over a period of time. At any given point in time, the peak buer usage from the past is displayed.
For example, if you enable BST at time T0 and use the show command to view the peak buer utilization value at time T1, the peak usage
between T0 and T1 is displayed. If you view the peak buer 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 buer utilization at time T4, the peak usage between T3 and T4 is displayed.
NOTE: When BST is enabled, if you make any conguration changes that aect the priority group or priority mapping
conguration, such as removal of class map, addition of class map to policy map (nqos), and so on, be sure to clear the buer
statistics using the clear qos statistics type buffer-statistics-tracking command to view the actual peak
buer utilization for the current conguration.
Advantages of BST include:
• Detecting microburst congestions
• Monitoring buer utilization and historical trends
• Determining optimal sizes and thresholds for the ingress or egress shared buers and headroom on a given port or queue based on real-
time data
NOTE
: BST is not supported on the S4248F-ON platforms.
After you disable BST, be sure to clear the counter using the clear qos statistics type buffer-statistics-tracking
command.
Port to port-pipe and MMU mapping
A port pipe handles network trac to and from a set of front-end I/O ports. On the Z9100–ON and Z9264F–ON platforms, interfaces are
shared across port pipes and port pipes are shared across Memory Management Units (MMUs).
As interfaces span port pipes, Dell EMC Networking recommends using interfaces from same port pipes for both ingress and egress for
optimal performance. To nd the port to port-pipe and MMU mapping, use the show qos port-map details command.
Z9100–ON output example:
OS10# show qos port-map details
---------------------------------------------------------------------------
Interface Port Pipe Ingress MMU Egress MMU Oper Status
---------------------------------------------------------------------------
Eth 1/1/1 1 2, 3 0, 2 up
Eth 1/1/2 1 2, 3 0, 2 up
Quality of service
1149