Enabling Data Center Bridging
Data center bridging is enabled by default on an MXL 10/40GbE Switch to support converged enhanced
Ethernet (CEE) in a data center network.
A prerequisite for configuring DCB:
• 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, you can classify ingress traffic according to its dot1p priority so that it
maps to different data queues. The dot1p-queue assignments used are shown in the following table.
On the MXL Switch, by default, DCB is enabled and MMU buffers are reserved to achieve no-drop traffic
handling for PFC. Disabling DCB does not release the buffers reserved by default. To utilize reserved
buffers for non-DCB applications, you have to explicitly release the buffers (Refer to Configuring the PFC
Buffer in a Switch Stack).
To disable or re-enable DCB on a switch, enter the following commands.
1. Disable DCB.
CONFIGURATION mode
no dcb enable
2. Re-enable DCB.
CONFIGURATION mode
dcb enable
NOTE: Dell Networking OS Behavior: DCB is not supported if you enable link-level flow control on
one or more interfaces.
After you disable DCB, if link-level flow control is not automatically enabled on an interface, to enable
flow control, manually shut down the interface (the shutdown command) and re-enable it (the no
shutdown command).
Data Center Bridging (DCB) 255