Dcb Maps And Its Attributes - Dell S4048T Configuration Manual

To enable DCB with PFC buffers on a switch, enter the following commands, save the configuration, and
reboot the system to allow the changes to take effect.
1 Enable DCB.
CONFIGURATION mode
dcb enable
2 Set PFC buffering on the DCB stack unit.
CONFIGURATION mode
Dell(conf)#dcb enable pfc-queues
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

DCB Maps and its Attributes

This 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 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 configure user-defined PFC and ETS settings, you must
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 each
priority 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 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 traffic is serviced first. Afterwards, you can
configure either the peak rates or the committed rates. The bandwidth allocated to other priority groups
is made available and allocated according to the specified 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 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 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
Ethernet Pause Frames.
Data Center Bridging (DCB) 299