Administrator Guide

Refer the following configuration for queue to dot1p mapping:
Dell(conf)#do show qos dot1p-queue-mapping
Dot1p Priority : 0 1 2 3 4 5 6 7 -> On ingress interfaces[Port A and C]
we used the PFC on priority level.
Queue : 0 0 0 1 2 3 3 3 -> On Egress interface[Port B] we used
no-drop queues.
The configuration of no-drop queues provides flexibility for ports on which PFC is not needed but lossless
traffic should egress from the interface.
Lossless traffic egresses out the no-drop queues. Ingress dot1p traffic from PFC-enabled interfaces is
automatically mapped to the no-drop egress queues.
1 Enter INTERFACE Configuration mode.
CONFIGURATION mode
interface type slot/port
2 Configure the port queues that still functions as no-drop queues for lossless traffic.
INTERFACE mode
pfc no-drop queues queue-range
For the dot1p-queue assignments, refer to the dot1p Priority-Queue Assignment table.
The maximum number of lossless queues globally supported on the switch is four.
The range is from 0 to 3. Separate the queue values with a comma; specify a priority range with a dash;
for example, pfc no-drop queues 1,3 or pfc no-drop queues 2-3.
The default: No lossless queues are configured.
NOTE: Dell Networking OS Behavior: By default, no lossless queues are configured on a port.
A limit of two lossless queues is supported on a port. If the amount of priority traffic that you configure to be
paused exceeds the two lossless queues, an error message displays. Reconfigure the input policy using a
smaller number of PFC priorities.
If you configure lossless queues on an interface that already has a DCB input policy with PFC enabled (pfc
mode on), an error message displays.
Traffic may be interrupted due to an interface flap (going down and coming up) when you reconfigure
lossless queues on no-drop priorities in an input policy and re-apply the policy to an interface.
Configuring the PFC Buffer in a Switch Stack
In a switch stack, you must configure all stacked ports with the same PFC configuration. In addition, you must
configure a separate buffer of memory allocated exclusively to a service pool accessed by queues on which
priority-based control flows are mapped.
These PFC-enabled queues ensure the lossless transmission of storage and server traffic. The buffer required
for the PFC service pool is calculated based on the number of ports and port queues used by PFC traffic.
You can configure the size of the PFC buffer for all switches in a stack or all port pipes on a specified stack
unit by entering the following commands on the master switch.
Data Center Bridging (DCB) 288