One of the techniques the ethernet physical layer uses to achieve high speed rates is pulse-amplitude modulation(PAM). An implementation of a specific physical layer is commonly referred to as PHY. If you want to adjust the speed on the wire from say 1Gbps to 800Gbps (caveat emptor!) you pick a different set of signal ranges to be used for equalization for different combinations of bits on the wire. When a vendor ships you a NIC, these ranges will be embedded in the firmware and are fixed. If you have to interop then the idea is the peer NIC vendor has similar settings.

How do you test these ranges? Lee Tragger says there are no open source tools available. Essentially, vendors provide their own proprietary tools to set equalization values and run pattern tests. In this talk, Lee will discuss whether setting equalization values and enabling pattern tests has matured enough across various vendors to develop a standard open source interface.

Details: https://netdevconf.info/0x19/37

cheers, jamal