Addendum

• The configuration of bandwidth allocation and strict-queue scheduling is not supported at the same

time for a priority group.

• Bandwidth assignment: By default, equal bandwidth is assigned to each dot1p priority in a priority

group. To configure the bandwidth assigned to the port queues associated with dot1p priorities in a

priority group, use the bandwidth percentage parameter. The sum of the bandwidth allocated to all

priority groups in a DCB map must be 100% of the bandwidth on the link. You must allocate at least

1% of the total bandwidth to each priority group.

• Scheduling of priority traffic: dot1p priority traffic on the switch is scheduled to the current queue

mapping. dot1p priorities within the same queue must have the same traffic properties and scheduling

method.

• ETS configuration error: If an error occurs in an ETS configuration, the configuration is ignored and

the scheduler and bandwidth allocation settings are reset to the ETS default value: 100% of available

bandwidth is allocated to priority group 0 and bandwidth is equally assigned to each dot1p priority.

If an error occurs when a port receives a peer’s ETS configuration, the port’s configuration resets to the

ETS configuration in the previously configured DCB map. If no DCB map was previously applied, the port

resets to the default ETS parameters.

ETS Prerequisites and Restrictions

On an S6000 switch, ETS is enabled by default on Ethernet ports; equal bandwidth is assigned to each

802.1p priority. You can change the default ETS configuration only by using a DCB map. For more

information, see Configuring DCB Maps and its Attributes.

The following prerequisites and restrictions apply when you configure ETS bandwidth allocation or strict-

priority queuing in a DCB map:

• When allocating bandwidth or configuring strict-priority queuing for dot1p priorities in a priority group

on a DCBx CIN interface, take into account the CIN bandwidth allocation (see Configuring Bandwidth

Allocation for DCBx CIN) and dot1p-queue mapping.

• Although ETS bandwidth allocation or strict-priority queuing does not support weighted random early

detection (WRED), explicit congestion notification (ECN), rate shaping, and rate limiting because these

parameters are not negotiated by DCBx with peer devices, you can apply a QoS output policy with

WRED and/or rate shaping on a DCBx CIN-enabled interface (see Configuring Port-based Rate

Shaping and Weighted Random Early Detection). In this case, the WRED or rate shaping configuration

in the QoS output policy must take into account the bandwidth allocation or queue scheduler

configured in the DCB map.

Priority-Group Configuration Notes

When you configure priority groups in a DCB map:

• A priority group consists of 802.1p priority values that are grouped together for similar bandwidth

allocation and scheduling, and that share the same latency and loss requirements. All 802.1p priorities

mapped to the same queue must be in the same priority group.

• In a DCB map, each 802.1p priority must map to a priority group.

• The maximum number of priority groups supported in a DCB map on an interface is equal to the

number of data queues (4) on the port. Each priority group can support more than one data queue.

• You can enable PFC on a maximum of two priority queues on an interface.

Data Center Bridging (DCB)