ALTERNATIVE PROTOCOL SELECTION

A link controller, method, and data processing platform are provided with dual-protocol capability. The link controller includes a physical layer circuit for providing a data lane over a communication link, a first data link layer controller which operates according to a first protocol, and a second data link layer controller which operates according to a second protocol. A multiplexer/demultiplexer selectively connects both data link layer controllers to the physical layer circuit. A link training and status state machine (LTSSM) selectively controls the physical layer circuit to transmit and receive first training ordered sets over the data lane, and inside the training ordered sets, transmit and receive alternative protocol negotiation information over the data lane. In response to receiving the alternative protocol negotiation information, the LTSSM causes the multiplexer/demultiplexer to selectively connect the physical layer circuit to the second data link layer controller.