Administrator Guide

Creating a DCB Map
Congure the priority-based ow control (PFC) and enhanced trac selection (ETS) settings in a DCB map before you apply them on
downstream server-facing ports on an NPG.
1 Create a DCB map to specify PFC and ETS settings for groups of dot1p priorities.
CONFIGURATION mode
dcb-map name
2 Congure the PFC setting (on or o) and the ETS bandwidth percentage allocated to trac in each priority group or whether priority
group trac should be handled with strict-priority scheduling.
DCB MAP mode
priority-group group_num {bandwidth percentage | strict-priority} pfc {on | off}
The sum of all allocated bandwidth percentages must be 100%.
Strict-priority trac is serviced rst. Afterward, 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.
NOTE: Restriction: You can enable PFC on a maximum of two priority queues.
Repeat this step to congure PFC and ETS trac handling for each priority group; for example:
priority-group 0 bandwidth 60 pfc off
priority-group 1 bandwidth 20 pfc on
priority-group 2 bandwidth 20 pfc on
priority-group 4 strict-priority pfc off
3 Specify the priority group ID number to handle VLAN trac for each dot1p class-of-service: from 0 through 7.
DCB MAP mode
priority-pgid dot1p0_group_num dot1p1_group_num dot1p2_group_num dot1p3_group_num
dot1p4_group_num dot1p5_group_num dot1p6_group_num dot1p7_group_num
Leave a space between each priority group number.
For example: priority-pgid 0 0 0 1 2 4 4 4.
Where dot1p priorities 0, 1, and 2 are mapped to priority group 0; dot1p priority 3 is mapped to priority group 1; dot1p priority 4 is
mapped to priority group 2; dot1p priorities 5, 6, and 7 are mapped to priority group 4.
NOTE
: All priorities that map to the same egress queue must be in the same priority group.
Important Points to Remember
• If you remove a dot1p priority-to-priority group mapping from a DCB map (the 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 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 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.
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