Dell S4820T, Configuration Manual

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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 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: 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 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.
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Data Center Bridging (DCB)