Administrator Guide

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.
Applying a DCB Map on a Port
When you apply a DCB map with PFC enabled on a switch interface, a memory buffer for PFC-enabled priority traffic is automatically
allocated. The buffer size is allocated according to the number of PFC-enabled priorities in the assigned map.
To apply a DCB map to an Ethernet port, follow these steps:
Table 17. DCB Map to an Ethernet Port
Step Task Command Command Mode
1
Enter interface configuration mode on an Ethernet port.
interface interface-type }
CONFIGURATION
2
Apply the DCB map on the Ethernet port to configure it with
the PFC and ETS settings in the map; for example:
DellEMC# interface tengigabitEthernet 1/1
DellEMC(config-if-te-1/1)# dcb-map
SAN_A_dcb_map1 Repeat Steps 1 and 2 to apply a DCB
map to more than one port.
You cannot apply a DCB map on an interface that has been
already configured for PFC using the pfc priority
command or which is already configured for lossless queues
(pfc no-drop queues command).
dcb-map name
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 18. Configuring PFC without a DCB Map
Step Task Command Command Mode
1 Enter interface configuration mode on an Ethernet port.
interface interface-type}
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.
250
Data Center Bridging (DCB)