Data Center Bridging (DCB) | 311
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. 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.
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).
To configure lossless queues on a port interface, follow these steps:
A DCB input policy for PFC applied to an interface may become invalid if dot1p-queue mapping is
reconfigured (refer to Create Input Policy Maps in Chapter 38, Quality of Service (QoS)). This
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 re-apply
the policy to an interface.
Step Task Command Command Mode
1 Enter INTERFACE Configuration mode.
interface type slot/port
CONFIGURATION
2 Configure the port queues that will still function as
no-drop queues for lossless traffic. For the
dot1p-queue assignments, refer to Table 13-1.
Maximum number of lossless queues globally
supported on the switch: 2.
Range: 0-3. Separate 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
Default: No lossless queues are configured.
pfc no-drop queues
queue-range
INTERFACE
To Next Page
Loading...
