Operation Manual

Operating modes and functions
ELSA LANCOM Wireless
36
English
The phases of PPP negotiation
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.
쮿
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 station is also ready to use PPP, and the packet
sizes and authentication protocol (PAP, CHAP or none) are determined. The LCP then
switches to the opened state.
쮿
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 is being used.
쮿
Network-phase
If the negotiation of the parameters is successful, IP packets may be sent over the
open (logical) line by the router modules.
쮿
Terminate phase
In the final phase the line is cleared, when the logical connections for all protocols
are cleared.
PPP negotiation in the
ELSA LANCOM
The progress of a PPP negotiation is logged in the devices' PPP statistics and the protocol
packets listed in detail there can be used for checking purposes in the event of an error.
The PPP trace outputs offer a further method of analysis. You can use the command
trace + ppp
to begin output of the PPP protocol frames exchanged during a terminal session. You can
perform a detailed analysis once the connection has been broken if this terminal session
has been logged in a log file.
The PPP list
You can specify a custom definition of the PPP negotiation for each of the remote stations
that contact your net. The PPP list can be found in the
ELSA LANconfig in the
'Communication' configuration section on the 'Protocols' tab, or in the
/Setup/WAN-
module/PPP List
menu.