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DCB map. This type of DCB configuration is useful on interfaces that require PFC for lossless traffic, but
do not transmit converged Ethernet traffic.
Step Task Command Command Mode
1 Enter interface configuration mode on an
Ethernet port.
interface
{tengigabitEthernet slot/
port /subport |
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.
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
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Data Center Bridging (DCB)