Reference Guide

situation occurs when the new dot1p-queue assignment exceeds the maximum number (2) of lossless
queues supported globally on the switch. In this case, all PFC configurations received from PFC-enabled
peers are removed and re-synchronized with the peer devices.
Traffic may be interrupted when you reconfigure PFC no-drop priorities in an input policy or reapply the
policy to an interface.
Dell Networking OS does not support MACsec Bypass Capability (MBC).
Configuring Lossless Queues
DCB also supports the manual configuration of lossless queues on an interface when PFC mode is turned
off and priority classes are disabled in a DCB input policy applied to the interface.
Prerequisite: A DCB input policy with PFC configuration is applied to the interface with the following
conditions:
• PFC mode is off (no pfc mode on).
• No PFC priority classes are configured (no pfc priority priority-range).
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 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 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.
Data Center Bridging (DCB)
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