Deployment Guide

● Use the xoff-state threshold polling-count {number of polling-interval} command to set the
number of times the polling should be done. If the traffic and the egress counter remain the same after the subsequent
polling, then the corresponding port or priority is detected to have PFC storm.
● Once PFC storm is detected on an interface, you can use the storm-control pfc in queue-drop command on the
interface to drop the ingress packets. This command triggers a queue drop state on the interface with PFC storm, so that
the traffic through other ports and priorities are not affected.
For more information about the above commands, see the Dell EMC Networking OS Command Line Reference Guide.
Restore Queue Drop State
You can restore the queue drop triggered due to the storm control PFC detection to the normal state.
Once the storm control PFC is detected on a port or priority, you can activate the queue drop action. You can restore the
dropped queue to normal state on the following conditions.
● You can restore the queue after a particular period of time. Use the queue-drop backoff-force polling—count
command to remove the queue-drop state after the specified number of polling is done. The queue-drop state, which has
been activated due to the detection of storm control PFC, is forced to get removed. When the number of polling-interval
is set as ‘zero’, the queue-drop state is not removed until it is explicitly cleared using the storm-control pfc in
queue-drop-state clear command.
● You can restore the queue when additional PFC packets for a particular priority are not received for a specified period
of time. Use the queue-drop backoff-on-norxpfc polling-count command to remove the queue-drop state if
additional PFCs are not received after the specified number of polling is done.
For more information about the above commands, see the Dell EMC Networking OS Command Line Reference Guide.
View Details of Storm Control PFC
You can view the status of storm control PFC and the statistical details by using the following Show commands.
Use the show storm-control pfc status stack-unit unit-number port—set portpipe-number command
to view the status of the storm control PFC on a specified stack unit. The following example shows the status on stack unit 0
with port set 0.
DellEMC#show storm-control pfc status stack-unit 1 port-set 0
-------------------------------------------------------------------------------------------------------
Interface Priority State Duration in discard state(in ms) Pkts Dropped(Ingress) Pkts Dropped(Egress) Pkts
Dropped(Ingress,Cumulative) Pkts
Dropped(Egress,Cumulative)--------------------------------------------------------------------------------------------------
-----
Fo 1/32/1 4 Drop 1194740 2389 135759218588
2389 135759218588
Fo 1/1/1 4 Normal 0 0 0
0 0
Fo 1/17/1 4 Normal 0 0 0
0 0
Use the show storm-control pfc statistics stack-unit unit-number port—set portpipe-number
command to view the statistical data of the storm control PFC on a specified stack unit. The following example shows the
statistics on stack unit 0 with port set 0.
DellEMC#show storm-control pfc statistics stack-unit 0 port—set 0
--------------------------------------------------------------------------------
Interface Priority Discard State Count Discard State Clear Count
forced No rxPfc
--------------------------------------------------------------------------------
Te 0/0 3 2 0 0
4 2 0 0
5 2 0 0
6 2 0 0
Te 0/1 3 0 0 0
4 0 0 0
5 0 0 0
6 0 0 0
Te 0/2 3 2 0 0
4 2 0 0
5 2 0 0
6 2 0 0
880
Storm Control