Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

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 FN IOM 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.

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).