ELSA LANCOM Business 6000, Manual

Page: 126 / 174

Technical basics
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ELSA LANCOM Business 6000
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126
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necessary for these protocols, for example IP/IPX addresses. This process
is carried out using IPCP (IP Control Protocol).
Verification of the connection through the LCP (Link Control Protocol)
Bundling of several channels (multilink PPP)
PPP is the standard used by router connections for communication between
devices or the WAN connection software of different manufacturers.
Connection parameters are negotiated and a common denominator is agreed
using standardized control protocols (e.g. LCP, IPCP, CCP) which are
contained in PPP, in order to ensure successful data transfer where possible.
What is PPP used for?
It is best to use the point-to-point protocol in the following applications:
for reasons of compatibility when communicating with external routers,
for example
Remote access of remote workstations with ISDN adapters
Internet access (when sending addresses)
The PPP which is implemented in ELSA LANCOM Business can be used
synchronously or asynchronously not only via a transparent HDLC connection,
but also via a X.75 connection.
The phases of a 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.
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