Addendum

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.
• If you configure more than one priority group as strict priority, the higher numbered priority queue is
given preference when scheduling data traffic.
Applying a DCB Map in a Switch Stack
You must apply the same DCB map with PFC and ETS configuration to all stacked ports in a switch stack.
You cannot apply different DCB maps to different stacked switches. This functionality is supported on the
S6000 platform.
Entering the no dcb-map stack-unit all command removes all PFC and ETS settings applied to stacked
ports from the DCB map and resets PFC and ETS to their default settings.
Task Command Command Mode
Apply the specified DCB map on all
ports of the switch stack.
dcb-map stack-unit all stack-ports
all dcb-map-name
CONFIGURATION
Data Center Bridging Exchange Protocol (DCBx)
The data center bridging exchange (DCBx) protocol is disabled by default on the S4810; ETS is also
disabled.
DCBx allows a switch to automatically discover DCB-enabled peers and exchange configuration
information. PFC and ETS use DCBx to exchange and negotiate parameters with peer devices. DCBx
capabilities include:
• Discovery of DCB capabilities on peer-device connections.
• Determination of possible mismatch in DCB configuration on a peer link.
Data Center Bridging (DCB)
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