Service Manual

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 interface-type
2. Configure the port queues that will still function 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 two.
The range is from 0 to 7. Separate the queue values with a comma; specify a priority range with a dash; for example, pfc
no-drop queues 1,7 or pfc no-drop queues 2-7.
The default: No lossless queues are configured.
3. Configure to drop the unknown unicast packets flooding on lossless priorities.
CONFIGURATION mode
pfc-nodrop-priority l2-dlf drop
4. View the packets drop count corresponding to the priority.
EXEC mode
EXEC Privilege mode
show hardware pfc-nodrop-priority l2-dlf drops stack-unit stack-unit-number port-set
port-pipe
DellEMC#show hardware pfc-nodrop-priority l2-dlf drops stack-unit 0 port-set 0
---------------------------------------------------
Priority DropCount
---------------------------------------------------
0 0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
To clear the drop statistics, use the clear hardware pfc-nodrop-priority l2-dlf drops stack-unit
stack-unit-number port-set port-pipe command.
NOTE: Dell EMC 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.
It is the user responsibility to have symmetric PFC configurations on the interfaces involved in a particular PFC-enabled traffic-
flow to obtain lossless behavior.
Configuring PFC in a DCB Map
A switch supports the use of a DCB map in which you configure priority-based flow control (PFC) setting. To configure PFC
parameters, you must apply a DCB map on an interface.
PFC Configuration Notes
PFC provides flow control based on the 802.1p priorities in a converged Ethernet traffic that is received on an interface and is
enabled by default when you enable DCB. As an enhancement to the existing Ethernet pause functionality, PFC stops traffic
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Data Center Bridging (DCB)