Users Guide

• All 802.1p priorities mapped to the same queue must be in the same priority group.
• A maximum of two PFC-enabled, lossless queues are supported on an interface.
Otherwise, the reconguration 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 specic 802.1p priorities. To enable PFC on 802.1p priorities, create a
DCB map.
The following prerequisites and restrictions apply when you congure PFC in a DCB map:
• You can enable PFC on a maximum of two priority queues on an interface. Enabling PFC for dot1p priorities congures the
corresponding port queue as lossless.
• You cannot enable PFC and link-level ow control at the same time on an interface.
Conguring 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 specic dot1p-priorities on individual interfaces without using a DCB map. This type of DCB conguration is useful on interfaces that
require PFC for lossless trac, but do not transmit converged Ethernet trac.
Table 15.
Conguring PFC without a DCB Map
Step Task Command Command Mode
1 Enter interface conguration mode on an Ethernet port.
interface {tengigabitEthernet
slot/port |
fortygigabitEthernet slot/port}
CONFIGURATION
2 Enable PFC on specied 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 congure PFC using the pfc priority
command on an interface on which a DCB map has
been applied or which is already congured for lossless
queues (pfc no-drop queues command).
pfc priority priority-
range
INTERFACE
Conguring Lossless Queues
DCB also supports the manual conguration of lossless queues on an interface when PFC mode is disabled in a DCB map, apply the map on
the interface. The conguration of no-drop queues provides exibility for ports on which PFC is not needed, but lossless trac should
egress from the interface.
Conguring no-drop queues is applicable only on the interfaces which do not need PFC.
252
Data Center Bridging (DCB)