Users Guide

Configuring Lossless Queues
DCB also supports the manual configuration of lossless queues on an interface after you disable PFC mode in
a DCB map and apply the map on 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 802.1p traffic from PFC-enabled peers is
automatically mapped to the no-drop egress queues.
When configuring lossless queues on a port interface, consider the following points:
• By default, no lossless queues are configured on a port.
• A limit of 4 lossless queues are supported on a port. If the number of lossless queues configured
exceeds the maximum supported limit per port (two), an error message is displayed. You must re-
configure the value to a smaller number of queues.
• If you configure lossless queues on an interface that already has a DCB map with PFC enabled (pfc on),
an error message is displayed.
Table 17. Configuring Lossless Queues
Step Task Command Command Mode
1 Enter INTERFACE Configuration
mode.
interface {tengigabitEthernet
slot/port | fortygigabitEthernet
slot}
port-number is a port number from 0 to
23.
CONFIGURATION
2
Open a DCB map and enter DCB
map configuration mode.
dcb-map name
INTERFACE
3
Disable PFC.
no pfc mode on
DCB MAP
4
Return to interface configuration
mode.
exit
DCB MAP
5
Apply the DCB map, created to
disable the PFC operation, on the
interface
dcb-map {name }
INTERFACE
6
Configure the port queues that still
function as no-drop queues for
lossless traffic. For the dot1p-queue
assignments.
The maximum number of lossless
queues globally supported on a port
is 2.
pfc no-drop queuesqueue-range
INTERFACE
Data Center Bridging (DCB) 301