1. Introduction

1.1. Auto-Negotiation in Link Training Test

In accordance with the IEEE standard, in the event of a failure during the AN/LT procedure, the port should initiate the procedure anew, as illustrated in Fig. 1.1 below.

Freya, functioning as a test port, possesses the capability to perform AN and LT as distinct and autonomous processes. Nevertheless, remote ports under test from different vendors may lack this capability. Consequently, when conducting LT tests, the testing port must activate or deactivate AN based on the settings configured on the remote port.

Fig. 1.1 AN in LT test

1.2. PRBS BER Measurement

As depicted in Fig. 1.2, the LT phase involves the measurement of LT BER using the PRBS-13 pattern. The LT algorithm relies on these LT BER values as its criteria.

It’s essential to clarify that LT’s primary goal is to enhance the PRBS BER during the DATA phase. However, it’s important to note that the pattern employed during the DATA phase may not necessarily be PRBS-13.

Therefore, any LT algorithm should strive to IMPROVE the PRBS BER rather than degrade it. Any LT algorithm that has a detrimental impact on the PRBS BER must be categorized as a “poor” algorithm.

Fig. 1.2 LT BER and PRBS BER