Reference Guide

56 | Data Center Bridging (DCB)
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Data Center Bridging: Auto-Configuration
Data center bridging is enabled by default on an Aggregator in standalone mode to support converged
enhanced Ethernet (CEE) in a data center network, and is a required for:
• Priority-based flow control
• Enhanced transmission selection
• Data center bridging exchange protocol
• FCoE initialization protocol (FIP) snooping
DCB processes virtual local area network (VLAN)-tagged packets and dot1p priority values. Untagged
packets are treated with a dot1p priority of 0.
For DCB to operate effectively, ingress traffic is classified according to its dot1p priority so that it maps to
different data queues. The dot1p-queue assignments used on an Aggregator are shown in Table 6-1 in QoS
dot1p Traffic Classification and Queue Assignment.
Disabling DCB
In some network topologies, you may want to disable DCB on an Aggregator and allow link-level flow
control to control data transmission between the Aggregator and other network devices (Flow Control
Using Ethernet Pause Frames).
After you enter the
no dcb enable command, you are prompted to reload the Aggregator to disable DCB
and enable link-level flow control.
Re-enabling DCB
You can later re-enable DCB on an Aggregator by entering the dcb enable command.
After you enter the
dcb enable command, you are prompted to reload the Aggregator to enable DCB and
disable link-level flow control.
Task Command Command Mode
Disable DCB.
no dcb enable
CONFIGURATION
Task Command Command Mode
Re-enable DCB.
dcb enable
CONFIGURATION