Users Guide

Configuring PFC without a DCB Map
In a network topology that uses the default ETS bandwidth allocation (assigns equal bandwidth to each
priority), you can also enable PFC for specific dot1p-priorities on individual interfaces without using a
DCB map. This type of DCB configuration is useful on interfaces that require PFC for lossless traffic, but
do not transmit converged Ethernet traffic.
Table 16. Configuring PFC without a DCB Map
Step Task Command Command Mode
1 Enter interface configuration mode
on an Ethernet port.
interface {tengigabitEthernet
slot/port |fortygigabitEthernet
slot/port}
CONFIGURATION
2 Enable PFC on specified priorities.
Range: 0-7. Default: None.
Separate priority values with a
comma. Specify a priority range with
a dash, for example: pfc priority
3,5-7
1. You cannot configure PFC
using the pfc priority
command on an interface on
which a DCB map has been
applied or which is already
configured for lossless queues
(pfc no-drop queues
command).
pfc priority priority-range
INTERFACE
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.
Data Center Bridging (DCB)
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