Users Guide

• 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 eectively, you can classify ingress trac according to its dot1p priority so that it maps to dierent data queues.
The dot1p-queue assignments used are shown in the following table.
To enable DCB, enable either the iSCSI optimization conguration or the FCoE conguration.
To enable DCB with PFC buers on a switch, enter the following commands, save the conguration, and reboot the system to allow
the changes to take eect.
1. Enable DCB.
CONFIGURATION mode
dcb enable
2. Set PFC buering on the DCB stack unit.
CONFIGURATION mode
Dell(conf)#dcb enable pfc-queues
NOTE: To save the pfc buering conguration changes, save the conguration and reboot the system.
NOTE: Dell Networking OS Behavior: DCB is not supported if you enable link-level ow 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 congure a DCB map, apply the congured DCB map to a port,
congure PFC without a DCB map, and congure lossless queues.
DCB Map: Conguration 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 congure user-dened PFC and ETS settings, you must create a DCB map. The following is an
overview of the steps involved in conguring DCB.
• Enter global conguration mode to create a DCB map or edit PFC and ETS settings.
• Congure the PFC setting (on or o) and the ETS bandwidth percentage allocated to trac in each priority group, or whether
the priority group trac should be handled with strict priority scheduling. You can enable PFC on a maximum of two priority
queues on an interface. Enabling PFC for dot1p priorities makes the corresponding port queue lossless. The sum of all allocated
bandwidth percentages in all groups in the DCB map must be 100%. Strict-priority trac is serviced rst. Afterwards, you can
congure either the peak rates or the committed rates. The bandwidth allocated to other priority groups is made available and
allocated according to the specied percentages. If a priority group does not use its allocated bandwidth, the unused bandwidth
is made available to other priority groups.
• Repeat the above procedure to congure PFC and ETS trac 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 that
map 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 to
dot1p priorities 0, 1, and 2; priority group 1 maps to dot1p priority 3; priority group 2 maps to dot1p priority 4; priority group 4 maps
to dot1p priorities 5, 6, and 7.
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Data Center Bridging (DCB)