Dell Networking N4000 Series Configuration Manual page 1330

1
mapping from the switch defaults to support lossless transport of frames on
CoS queue 4, with a 50% minimum bandwidth guarantee. Lossless traffic
classes generally use the default WRR scheduling mode as opposed to strict
priority, to avoid starving other traffic. For example, the following commands
assign user priority 4 to CoS queue 4 and reserve 50% of the scheduler
bandwidth to CoS queue 4. This implies that, when the switch is congested,
the scehduler will service CoS queue 4 fifty percent of the time to the
exclusion of all other CoS queues, including higher-priority CoS queues.
classofservice dot1p-mapping 4 4
cos-queue min-bandwidth 0 0 0 0 50 0 0
1. Lossless behavior is guaranteed only when configured in conjunction with a conges-
tion control mechanism such as PFC.
1330
Configuring Class-of-Service