Enabling Data Center BridgingDCB is automatically configured when you configure FCoE or iSCSI optimization.Data center bridging supports converged enhanced Ethernet (CEE) in a data center network. DCB isdisabled 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) snoopingDCB processes virtual local area network (VLAN)-tagged packets and dot1p priority values. Untaggedpackets 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 itmaps 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.To enable DCB with PFC buffers on a switch, enter the following commands, save the configuration, andreboot the system to allow the changes to take effect.1. Enable DCB.CONFIGURATION modedcb enable2. Set PFC buffering on the DCB stack unit.CONFIGURATION modeDell(conf)#dcb enable pfc-queuesNOTE: To save the pfc buffering configuration changes, save the configuration and reboot thesystem.NOTE: Dell Networking OS Behavior: DCB is not supported if you enable link-level flow control onone or more interfaces. For more information, refer to Ethernet Pause Frames.DCB Maps and its AttributesThis topic contains the following sections that describe how to configure a DCB map, apply theconfigured DCB map to a port, configure PFC without a DCB map, and configure lossless queues.DCB Map: Configuration ProcedureA DCB map consists of PFC and ETS parameters. By default, PFC is not enabled on any 802.1p priorityand ETS allocates equal bandwidth to each priority. To configure user-defined PFC and ETS settings, youmust create a DCB map. The following is an overview of the steps involved in configuring DCB.• Enter global configuration mode to create a DCB map or edit PFC and ETS settings.• Configure the PFC setting (on or off) and the ETS bandwidth percentage allocated to traffic in eachpriority group, or whether the priority group traffic should be handled with strict priority scheduling.You can enable PFC on a maximum of two priority queues on an interface. Enabling PFC for dot1p242 Data Center Bridging (DCB)
