Administrator Guide

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.
Important Points to Remember
• If you remove a dot1p priority-to-priority group mapping from a DCB map (no priority pgid command), the PFC and ETS
parameters revert to their default values on the interfaces on which the DCB map is applied. By default, PFC is not applied on specic
802.1p priorities; ETS assigns equal bandwidth to each 802.1p priority.
As a result, PFC and lossless port queues are disabled on 802.1p priorities, and all priorities are mapped to the same priority queue and
equally share the port bandwidth.
• To change the ETS bandwidth allocation congured for a priority group in a DCB map, do not modify the existing DCB map
conguration. Instead, rst create a new DCB map with the desired PFC and ETS settings, and apply the new map to the interfaces to
override the previous DCB map settings. Then, delete the original dot1p priority-priority group mapping.
Data Center Bridging (DCB)
257