The Care and Feeding of ISDN4BSD
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9 The isdnmonitor Utility The Care and Feeding 10.1 isdnd.rc Setup

10 Setting up a Synchronous PPP Link using isp/sppp

In this section i'll try to go through the steps required to set up a link to a remote site using synchronous PPP over ISDN. The following picture presents an overview of the components and paths involved in the isdn4bsd PPP implementation:


The isdn daemon isdnd has to be configured to handle the connection establishment over the D-channel. Once the connection to the remote site has been established, a B-channel is connected to the i4bisppp network device driver, which handles the PPP protocol in the isdn4bsd package. It does this with the help of the sppp module, which does the real work of handling the PPP protocol. The i4b PPP network device is then visible as one of the isp<n> (i.e. isp0 or isp1) interfaces.

What does each component do?

Here is the setup for the following example:


A Cisco 1003 Router and a PC running FreeBSD 3.x and isdn4bsd are connected to a PBX. The Cisco is connected to an ISDN S0 port on that PBX which has the extension (telephone-) number 581 to it and the FreeBSD machine is connected to an S0 port with the extension 241.


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Hellmuth Michaelis 2000-05-08