Setup Guide

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 17. Conguring PFC without a DCB Map
Step Task Command Command Mode
1 Enter interface conguration mode on an Ethernet port.
interface interface-type}
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.
Example:
Port A —> Port B
Port C —> Port B
PFC no-drop queues are congured 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, [trac 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 trac limit. Egress drops are not observed on Port B since trac ow on priorities is mapped to loss less queues.
Port B acting as Ingress
If the trac congestion is on PORT B , Egress DROP is on PORT A or C, as the PFC is not enabled on PORT B.
Refer the following conguration for queue to dot1p mapping:
DellEMC(conf)#do show qos dot1p-queue-mapping
Dot1p Priority : 0 1 2 3 4 5 6 7 -> On ingress interfaces[Port A and C] we used the
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Data Center Bridging (DCB)