Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 251

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 pfctotal-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 1 2 Task Enter interface configuration mode on an Ethernet port. Apply the DCB map on the Ethernet port to configure it with the PFC and ETS settings in the map; for example: Command interface {tengigabitEthernet slot/port fortygigabitEthernet slot/port} dcb-map name 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 Command Mode CONFIGURATION INTERFACE Data Center Bridging (DCB) 251