Dell SmartFabric OS10 User Guide Release 10.5.6

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Link training

This section describes the link training feature that is used for optimal hardware signal tuning.

Link training feature allows you to dynamically optimize hardware signals for high-speed Ethernet links through a copper cable. It involves a handshake process that fine-tunes the hardware signals for optimal performance.

When link training is enabled on both ends of a link, the handshake process begins to dynamically adjust the hardware signals. If autonegotiation (AN) is enabled on both sides of the link, link training only initiates after the interface speed negotiation is complete. Link training eliminates the need for manual adjustment of specific channels in a copper cable link, including standards such as IEEE 802.3bj-2014, 10GBASE-KR, and 100GBASE-KR4.

By default, autonegotiation and link training are enabled on a Direct Attach Cable (DAC). If autonegotiation is disabled on an interface, you can manually enable or disable link training using the link-training command. Use the show interface ethernet node/slot/port[:subport] command to view the configuration status of the link training feature on individual ports.

The following table shows the operational status of link training on hardware transceivers, which are categorized by autonegotiation and link training configuration:

Table 1. Operational status of link training on hardware transceivers by autonegotiation and link training configuration Operational status of link training on hardware transceivers by autonegotiation and link training configuration
Autonegotiation	Link training	Operational link training status for DAC media	Operational link training status for Optics media
OFF	OFF (default)	OFF	OFF (link is expected to come up).
OFF	ON	ON (DAC: SFP, QSFP, QSFP-DD)	ON (the link is not expected to come up).
ON	OFF is not allowed.	ON (DAC: SFP, QSFP, QSFP-DD)	OFF (AN is not supported for optic; link is not expected to come up).
ON	ON (default)	ON (DAC: SFP, QSFP, QSFP-DD)	OFF (AN is not supported for optic; link is not expected to come up).