Users Guide

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. The
maximum number of priority groups is 3.
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.
• On the C9010, DCB is supported per-line card. If the traffic handled by a DCB map is transmitted on ports on different line
cards, you must manually configure the DCB map on the backplane ports of the C9010 line cards on which the ports reside
(dcb-map linecard all backplane all command).
If the DCB map you apply to the backplane ports of C9010 RPMs (linecard 10–11) configures two or more priority
groups, you must increase the size of the PFC shared and total buffers (
dcb pfc-shared-buffer-size and dcb pfc-
total-buffer-size commands).
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 15. Applying a DCB map to an Ethernet port
Step Task Command Command Mode
1
Enter interface configuration mode on an
Ethernet port.
interface
{tengigabitEthernet
slot/port
fortygigabitEthernet
slot/port}
CONFIGURATION
2
Apply the DCB map on the Ethernet port to
configure it with the PFC and ETS settings in
the map; for example:
Dell# interface tengigabitEthernet 1/1
Dell(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 thepfc priority command or which
dcb-map name
INTERFACE
Data Center Bridging (DCB) 251