Peer Authentication Phase (optional)

Optionally, one or both of the endpoints can request peer authentication. Solstice PPP supports peer authentication based on the Password Authentication Protocol (PAP) and the Challenge-Handshake Authentication Protocol (CHAP). If authentication is successful, the link remains up and the network layer protocol phase is started. If authentication fails, the link termination phase is started to close the link.

During the peer authentication phase only LCP and authentication frames should be transmitted in the PPP frames. All other frames are discarded.