Establishment of a connection using PPP always begins with a negotiation of the parameters to be used for the connection. This negotiation is carried out in four phases which should be understood for the sake of configuration and troubleshooting.
- Establish phase Once a connection has been made at the data communication level, negotiation of the connection parameters begins through the LCP. This ascertains whether the remote site is also ready to use PPP, and the packet sizes and authentication protocol (PAP, CHAP, MS-CHAP or none) are determined. The LCP then switches to the opened state.
- Authenticate phase Passwords will then be exchanged, if necessary. The password will only be sent once if PAP is being used for the authentication process. An encrypted password will be sent periodically at adjustable intervals if CHAP or MS CHAP is being used. Perhaps a callback is also negotiated in this phase via CBCP (Callback Control Protocol).
- Network phase LANCOM, supports the protocols IPCP and IPXCP. After the password has been successfully transmitted, the IPCP and/or IPXCP network layer can be established. IP and/or IPS packets can be transferred from the router modules to the opened line if the negotiation of parameters is successful for at least one of the network layers.
- Terminate phase In the final phase the line is cleared, when the logical connections for all protocols are cleared.