Users Guide

Step Task Command Command Mode
fortygigabitEthernet slot/
port}
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.
Example:
Port A —> Port B
Port C —> Port B
PFC no-drop queues are configured for queues 1, 2 on Port B. PFC capability is enabled on priorities 3, 4 on
PORT A and C.
Port B acting as Egress
During the congestion, [traffic pump on priorities 3 and 4 from PORT A and PORT C is at full line rate], PORT
A and C send out the PFCs to rate the traffic limit. Egress drops are not observed on Port B since traffic flow
on priorities is mapped to loss less queues.
Port B acting as Ingress
If the traffic congestion is on PORT B , Egress DROP is on PORT A or C, as the PFC is not enabled on PORT B.
Data Center Bridging (DCB) 313