Users Guide

• If priority group 3 has free bandwidth, it is distributed as follows: 20% of the free bandwidth to priority
group 1 and 30% of the free bandwidth to priority group 2.
• If priority group 1 or 2 has free bandwidth, (20 + 30)% of the free bandwidth is distributed to priority
group 3. Priority groups 1 and 2 retain whatever free bandwidth remains up to the (20+ 30)%.
Strict-priority
groups:
If two priority groups have strict-priority scheduling, trac assigned from the priority group with the higher
priority-queue number is scheduled rst. However, when three priority groups are used and two groups have
strict-priority scheduling (such as groups 1 and 3 in the example), the strict priority group whose trac is
mapped to one queue takes precedence over the strict priority group whose trac is mapped to two
queues.
Therefore, in this example, scheduling trac to priority group 1 (mapped to one strict-priority queue) takes precedence over
scheduling trac to priority group 3 (mapped to two strict-priority queues).
Using ETS to Manage Converged Ethernet Trac
To use ETS for managing converged Ethernet trac, use the following command:
dcb-map stack-unit all dcb-map-name
Applying DCB Policies in a Switch Stack
You can apply DCB policies with PFC and ETS congurations to all stacked ports in a switch stack or on a stacked switch.
To apply DCB policies in a switch stack, follow this step.
• Apply the specied DCB policy on all ports of the switch stack or a single stacked switch.
CONFIGURATION mode
dcb-map {stack-unit all | stack-ports all} dcb-map-name
Congure a DCBx Operation
DCB devices use data center bridging exchange protocol (DCBx) to exchange conguration information with directly connected
peers using the link layer discovery protocol (LLDP) protocol.
DCBx can detect the misconguration of a peer DCB device, and optionally, congure peer DCB devices with DCB feature settings
to ensure consistent operation in a data center network.
DCBx is a prerequisite for using DCB features, such as priority-based ow control (PFC) and enhanced trac selection (ETS), to
exchange link-level congurations in a converged Ethernet environment. DCBx is also deployed in topologies that support lossless
operation for FCoE or iSCSI trac. In these scenarios, all network devices are DCBx-enabled (DCBx is enabled end-to-end). For
more information about how these features are implemented and used, refer to:
• Congure Enhanced Transmission Selection
DCBx supports the following versions: CIN, CEE, and IEEE2.5.
Prerequisite: For DCBx, enable LLDP on all DCB devices.
DCBx Operation
DCBx performs the following operations:
• Discovers DCB conguration (such as PFC and ETS) in a peer device.
Data Center Bridging (DCB)
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