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 specic

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 congured for a priority group in a DCB map, do not modify the existing DCB map

conguration. Instead, rst 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

When you apply a DCB map with PFC enabled on an S6000 interface, a memory buer for PFC-enabled priority trac is automatically

allocated. The buer 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:

1 Enter interface conguration mode on an Ethernet port.

CONFIGURATION mode

interface {tengigabitEthernet slot/port | fortygigabitEthernet slot/port

2 Apply the DCB map on the Ethernet port to congure it with the PFC and ETS settings in the map; for example:

INTERFACE mode

dcb-map name

You cannot apply a DCB map on an interface that has been already congured for PFC using thepfc priority command or which

is already congured for lossless queues (

pfc no-drop queues command).

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.

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.

1 Enter interface conguration mode on an Ethernet port.

CONFIGURATION mode

interface {tengigabitEthernet slot/

port

| fortygigabitEthernet slot/

port

}

2 Enable PFC on specied priorities. Range: 0-7. Default: None.

Data Center Bridging (DCB)