Table of Contents

Overview

Configuration Process

Show Link Training Status

Example

Example model & SONiC version:

• Aurora 830, Aurora 721, Aurora 621
• Netberg SONiC: sonic-broadcom-202311.n0

Overview

Link training is a process by which the transmitter and receiver on a high-speed serial link communicate with each other to tune their equalization settings. In theory, link training enables automatic tuning of the FIR filter for each channel in an ASIC to achieve the desired bit error rate (BER).

SONiC focuses on IEEE clauses 72 and 93 to dynamically improve the link quality over the SFP coppers and backplanes.

Link training applies only to copper cables, and aims to improve connection quality among different switches.

Configuration Process

A CLI command supports port link training.

config interface link-training <interface_name> <mode>

Parameter description:

interface_name: [mandatory] name of the interface to be configured. e.g: Ethernet0
mode: [mandatory] link training mode, can be either "on" or "off"

Show Link Training Status

show interfaces link-training status <interface_name>

Parameter description:

interface_name: [optional] Name of the interface to be shown. e.g: Ethernet0.
                 If interface_name is not given, this command shows link training status for all interfaces.

Example

nba621-1:

admin@nba621-1:~$ sudo config interface link-training Ethernet2 on

nba621-2:

admin@nba621-2:~$ sudo config interface link-training Ethernet2 on

Check the status:

admin@nba621-1:~$ show interfaces link-training status
  Interface    LT Oper    LT Admin    Oper    Admin
-----------  ---------  ----------  ------  -------
  Ethernet0        N/A         N/A      up       up
  Ethernet1        N/A         N/A    down       up
  Ethernet2    trained          on      up       up
  Ethernet3        N/A         N/A    down       up
admin@nba621-1:~$ show interfaces link-training status Ethernet2
  Interface    LT Oper    LT Admin    Oper    Admin
-----------  ---------  ----------  ------  -------
  Ethernet2    trained          on      up       up

admin@nba621-2:~$ show interfaces link-training status
  Interface    LT Oper    LT Admin    Oper    Admin
-----------  ---------  ----------  ------  -------
  Ethernet0        N/A         N/A      up       up
  Ethernet1        N/A         N/A    down       up
  Ethernet2    trained          on      up       up
  Ethernet3        N/A         N/A    down       up