• Data center bridging exchange protocol• FCoE initialization protocol (FIP) snoopingDCB processes virtual local area network (VLAN)-tagged packets and dot1p priority values. Untagged packets are treated with adot1p 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.To enable DCB with PFC buffers on a switch, enter the following commands, save the configuration, and reboot the system to allowthe 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 the system.NOTE: Dell 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 AttributesThis 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 ProcedureA DCB map consists of PFC and ETS parameters. By default, PFC is not enabled on any 802.1p priority and ETS allocates equalbandwidth to each priority. To configure user-defined PFC and ETS settings, you must create a DCB map. The following is anoverview 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 each priority group, or whetherthe priority group traffic should be handled with strict priority scheduling. You can enable PFC on a maximum of two priorityqueues on an interface. Enabling PFC for dot1p priorities makes the corresponding port queue lossless. The sum of all allocatedbandwidth percentages in all groups in the DCB map must be 100%. Strict-priority traffic is serviced first. Afterwards, you canconfigure either the peak rates or the committed rates. The bandwidth allocated to other priority groups is made available andallocated according to the specified percentages. If a priority group does not use its allocated bandwidth, the unused bandwidthis made available to other priority groups.• Repeat the above procedure to configure PFC and ETS traffic handling for each priority group• Specify the dot1p priority-to-priority group mapping for each priority. The priority group range is from 0 to 7. All priorities thatmap to the same queue must be in the same priority group.Leave a space between each priority group number. For example: priority-pgid 0 0 0 1 2 4 4 4 in which priority group 0 maps todot1p priorities 0, 1, and 2; priority group 1 maps to dot1p priority 3; priority group 2 maps to dot1p priority 4; priority group 4 mapsto dot1p priorities 5, 6, and 7.Data Center Bridging (DCB) 245
