Westermo MR Series - Manual (Page 171)

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Web Interface and Command Line Reference Guide www.westermo.com
Confi gure > L2TP > L2TP n 4.54
L2TP (Layer 2 Tunnelling Protocol) provides a means by the termination of a logical PPP connection
can take place on a device other than that which terminates the physical connection over which
the PPP traffic is carried. Typically, both the physical layer connection and the logical PPP connection
would be terminated on the same device, e.g. a Westermo router. This is illustrated below:
With L2TP answering the call however, the router terminates the layer 2 connection only and the
PPP frames are passed in an L2TP “tunnel” to another device which terminates the PPP connection.
This device is sometimes referred to as a Network Access Server (NAS). This scenario is shown
below:
Using the Web Page(s)
Answering:
This parameter is used to enable or disable L2TP answering.
MSN:
The MSN parameter provides the filter for the ISDN Multiple Subscriber Numbering facility. It is
blank by default but when set to an appropriate value with Answering “On” it will cause the unit
to answer incoming calls only to ISDN numbers where the trailing digits match the MSN value.
For example, setting the MSN parameter to 123 will prevent the unit from answering any calls
to numbers that do not end in 123.
If Answering is “Off” this parameter is not used.
Sub-address:
The Sub-address parameter provides the filter for the ISDN sub-addressing facility. It is blank by
default but when set to an appropriate value, with Answering “On” will cause the unit to answer
incoming ISDN calls only where the trailing digits of the sub address called match the Sub-
address value. For example, setting the Sub-address parameter to 123 will prevent the unit from
answering any calls where the sub-address called does not end in 123.
If Answering is “Off” this parameter is not used.
Window:
This parameter specify the L2TP window size which can be set from 1 to 7.
Layer 1 interface:
This parameter determines which physical interface is to be used to terminate an L2TP connec-
tion. This can be set to either “ISDN” or “PORT”. When set to “PORT”, one of the synchronous
serial ports is used.
Sync port:
When Layer 1 interface is set to “PORT”, this parameter specifies the number of the SYNC
port to be used.