Reference Guide

ETS: Equal bandwidth is assigned to each port queue and each dot1p priority in a priority group.

To congure PFC and ETS parameters on an S6000 interface, you must specify the PFC mode, the ETS bandwidth allocation for a

priority group, and the 802.1p priority-to-priority group mapping in a DCB map. No default PFC and ETS settings are applied to

Ethernet interfaces.

Data Center Bridging in a Trac Flow

The following gure shows how DCB handles a trac ow on an interface.

Figure 3. DCB PFC and ETS Trac Handling

Data Center Bridging: Auto-DCB-Enable Mode

On an Aggregator in standalone or VLT modes, the default mode of operation for data center bridging on Ethernet ports is auto-

DCB-enable mode. In this mode, Aggregator ports detect whether peer devices support CEE or not, and enable ETS and PFC or

link-level ow control accordingly:

• Interfaces come up with DCB disabled and link-level ow control enabled to control data transmission between the Aggregator

and other network devices (see Flow Control Using Ethernet Pause Frames). When DCB is disabled on an interface, PFC, and

ETS are also disabled.

• When DCBx protocol packets are received, interfaces automatically enable DCB and disable link-level ow control.

DCB is required for PFC, ETS, DCBx, and FCoE initialization protocol (FIP) snooping to operate.

NOTE: Normally, interfaces do not ap when DCB is automatically enabled.

DCB processes VLAN-tagged packets and dot1p priority values. Untagged packets are treated with a dot1p priority of 0.

For DCB to operate eectively, ingress trac is classied according to its dot1p priority so that it maps to dierent data queues. The

dot1p-queue assignments used on an Aggregator are shown in Table 6-1 in dcb enable auto-detect on-next-reload Command

Example QoS dot1p Trac Classication and Queue Assignment.

When DCB is Disabled (Default) By default, Aggregator interfaces operate with DCB disabled and link-level ow control enabled.

When an interface comes up, it is automatically congured with:

• Flow control enabled on input interfaces.

Data Center Bridging (DCB)