Users Guide

• A maximum of two PFC-enabled, lossless queues are supported on an interface.
Otherwise, the reconfiguration of a default dot1p-queue assignment is rejected.
• To ensure complete no-drop service, apply the same PFC parameters on all PFC-enabled peers.
PFC Prerequisites and Restrictions
On a switch, PFC is globally enabled by default, but not applied on specific 802.1p priorities. To enable PFC on 802.1p priorities, create a
DCB map.
The following prerequisites and restrictions apply when you configure PFC in a DCB map:
• You can enable PFC on a maximum of two priority queues on an interface. Enabling PFC for dot1p priorities configures the
corresponding port queue as lossless.
• You cannot enable PFC and link-level flow control at the same time on an interface.
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 15. 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.
Maximum number of lossless queues supported on an
Ethernet port: 2.
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 when PFC mode is disabled in a DCB map, 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.
Configuring no-drop queues is applicable only on the interfaces which do not need PFC.
Data Center Bridging (DCB)
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