Reference Guide

FTOS Behavior: Create a DCB output policy to associate a priority group with an ETS output policy with scheduling and
bandwidth configuration. You can apply a DCB output policy on multiple egress ports.
The ETS configuration associated with 802.1p priority traffic in a DCB output policy is used in DCBx negotiation with ETS
peers.
When you apply an ETS output policy to an interface, ETS-configured scheduling and bandwidth allocation take
precedence over any configured settings in the QoS output policies.
To remove an ETS output policy from an interface, use the no dcb-policy output policy-name command.
DCB and ETS are both disabled by default. When DCB is enabled, ETS is enabled on all interfaces that have the default
ETS configuration applied.
If you disable ETS in an output policy applied to an interface (the no ets mode on command), any previously
configured QoS settings at the interface or global level take effect. If QoS settings are configured at the interface or
global level and in an output policy map (the service-policy output command), the QoS configuration in the
output policy take precedence.
ETS Operation with DCBx
The following section describes DCBx negotiation with peer ETS devices.
In DCBx negotiation with peer ETS devices, ETS configuration is handled as follows:
• ETS TLVs are supported in DCBx versions CIN, CEE, and IEEE2.5.
• The DCBx port-role configurations determine the ETS operational parameters (refer to Configure a DCBx
Operation).
• ETS configurations received from TLVs from a peer are validated.
• If there is a hardware limitation or TLV error:
– DCBx operation on an ETS port goes down.
– New ETS configurations are ignored and existing ETS configurations are reset to the previously
configured ETS output policy on the port or to the default ETS settings if no ETS output policy was
previously applied.
• ETS operates with legacy DCBx versions as follows:
– In the CEE version, the priority group/traffic class group (TCG) ID 15 represents a non-ETS priority group.
Any priority group configured with a scheduler type is treated as a strict-priority group and is given the
priority-group (TCG) ID 15.
– The CIN version supports two types of strict-priority scheduling:
* Group strict priority: Use this to increase its bandwidth usage to the bandwidth total of the
priority group and allow a single priority flow in a priority group. A single flow in a group can use
all the bandwidth allocated to the group.
* Link strict priority: Use this to increase to the maximum link bandwidth and allow a flow in any
priority group.
CIN supports only the dot1p priority-queue assignment in a priority group. To configure a dot1p priority flow in a
priority group to operate with link strict priority, you configure: The dot1p priority for strict-priority scheduling
(strict-priority command; Enabling Strict-Priority Queueing). The priority group for strict-priority
scheduling (scheduler strict command; Creating a QoS ETS Output Policy).
If you configure only the priority group in an ETS output policy or only the dot1p priority for strict-priority
scheduling, the flow is handled with group strict priority.
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