Important Points to Remember
• If you remove a dot1p priority-to-priority group mapping from a DCB map (no priority pgid
command), the PFC and ETS parameters revert to their default values on the interfaces on which the
DCB map is applied. By default, PFC is not applied on specific 802.1p priorities; ETS assigns equal
bandwidth to each 802.1p priority.
As a result, PFC and lossless port queues are disabled on 802.1p priorities, and all priorities are
mapped to the same priority queue and equally share the port bandwidth.
• To change the ETS bandwidth allocation configured for a priority group in a DCB map, do not modify
the existing DCB map configuration. Instead, first create a new DCB map with the desired PFC and
ETS settings, and apply the new map to the interfaces to override the previous DCB map settings.
Then, delete the original dot1p priority-priority group mapping.
If you delete the dot1p priority-priority group mapping (no priority pgid command) before you
apply the new DCB map, the default PFC and ETS parameters are applied on the interfaces. This
change may create a DCB mismatch with peer DCB devices and interrupt network operation.
Applying a DCB Map on a Port
To apply a DCB map to an Ethernet port, follow these steps:
Step Task Command Command Mode
1Enter interface configuration mode on an
Ethernet port. interface
{tengigabitEthernet slot/
port |
fortygigabitEthernet
slot/port}
CONFIGURATION
2Apply the DCB map on the Ethernet port to
configure it with the PFC and ETS settings in
the map; for example:
Dell# interface tengigabitEthernet 0/0
Dell(config-if-te-0/0)# 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
thepfc 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.
Data Center Bridging (DCB) 257