Reference Guide

Data Center Bridging (DCB) | 301
ETS Operation with DCBx
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.
• ETS operational parameters are determined by the DCBx port-role configurations (see Configuring
DCBx Operation).
• ETS configurations received from TLVs from a peer are validated.
• In case of 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: Allows a single priority flow in a priority group to increase its
bandwidth usage to the bandwidth total of the priority group. A single flow in a group can
use all the bandwidth allocated to the group.
— Link strict priority: Allows a flow in any priority group to increase to the maximum link
bandwidth.
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 must configure:
- The dot1p priority for strict-priority scheduling (
strict-priority command; Strict-priority
Queueing)
- The priority group for strict-priority scheduling (
scheduler strict command)
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.