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 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. For information to configure iSCSI

optimization, refer to

iSCSI Optimization. For information to configure FCoE, refer to Fibre Channel over Ethernet.

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

dcb stack-unit all pfc-buffering pfc-ports 64 pfc-queues 2

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 Flow Control Using Ethernet Pause Frames.

Configuring 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.

1 Enter global configuration mode to create a DCB map or edit PFC and ETS settings.

CONFIGURATION mode

dcb-map name

2 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, 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.

DCB MAP mode

priority-group group_num {bandwidth percentage | strict-priority} pfc {on | off}

Data Center Bridging (DCB)