Service Manual

Data Center Bridging in a Traffic Flow
The following figure shows how DCB handles a traffic flow on an interface.
Figure 34. DCB PFC and ETS Traffic Handling
Enabling Data Center Bridging
DCB is automatically configured when you configure FCoE or iSCSI optimization.
Data center bridging supports converged enhanced Ethernet (CEE) in a data center network. DCB is disabled by default. It must
be enabled to support CEE.
● 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.
To enable DCB, enable either the iSCSI optimization configuration or the FCoE configuration.
NOTE:
Dell EMC Networking OS Behavior: DCB is not supported if you enable link-level flow control on one or more
interfaces. For more information, refer to Ethernet Pause Frames.
DCB Maps and its Attributes
This topic contains the following sections that describe how to configure a DCB map, apply the configured DCB map to a port,
configure PFC without a DCB map, and configure lossless queues.
DCB Map: Configuration Procedure
A DCB map consists of PFC and ETS parameters. By default, PFC is not enabled on any 802.1p priority and ETS allocates equal
bandwidth to each priority. To configure user-defined PFC and ETS settings, you must create a DCB map. The following is an
overview of the steps involved in configuring DCB.
Data Center Bridging (DCB)
257