Autoneg & Link Training

This White Paper looks at Autonegotiation and Link Training and explains how Thor-400G-7S-1P supports these functions for the new PAM4-based 400GE 200GE, 100GE and 50GE data rates.

PAM-4 Auto-Negotiation & Link Training White Paper

Autonegotiation is a tried-and-tested process where a device is connected to a network through an Ethernet interface, and the end points of a link share information on various capabilities relevant for the communication.

Autonegotiation determines the highest common denominator among the end-point capabilities, and these will be used for the communication. Link Training is another process that can take place when a device is connected to a high-speed Ethernet port through a copper cable or backplane. In this case it is important that the characteristics of the transmitted signal are tuned to be optimally carried over the copper cable.

Xena’s 7-speed dual-media test module Thor-400G-7S-1P supports the new PAM4-based 400GE, 200GE, 100GE and 50GE speeds defined in the IEEE 802.3bs and 802.3cd standards. It also has the unique advantage of also being able to test the NRZ-based speeds: 100GE, 50GE, 40GE, 25GE and 10GE. Installed in a ValkyrieBay or ValkyrieCompact chassis, it provides advanced Ethernet test capabilities up to Layer 3.

Learn more about Auto-negotiation and Link Training for the new PAM4-based 400GE 200GE, 100GE and 50GE data rates and how Xena’s Thor-400G-7S-1P can be used for testing these speeds with these functions enabled.


  • Introduction
  • The PAM4 Line Code
  • Autonegotiation
  • Link Training
  • No Autonegotiation, No Link Training
  • No Autonegotiation, Link Training
  • Autonegotiation and Link Training
  • Thor-400G-7S-1P
  • Manual Tuning of Transmitter Characteristics
  • Conclusion

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030 WP: PAM-4 Auto-negotiation & Link Training

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