stand-alone dials in to office via isdn

[Reil]

Hi all,

i think my problem is trivial, but i don't get this thing done ...

In our office a linux-box ("gw") is connected like this:
- via eth0 to the local net (192.168.1.0/24)
- via eth1 to the DSL-router (dynamic ip)
- via ippp0 (isdn-card) 192.168.2.245 to the stand-alone pc 
192.168.2.250 ("single")

"single" is a w2k box and have an isdn-card, too and is able to dial 
in to "gw". Routing is ok, reaching the pc's in 192.168.1.0/24 is 
working.

Now i want to have a vpn between "single" and "gw". 

I don't understand, how "single" is able to dial in to "gw" with the 
new TAP-Win32 interface called "vpn". 

Does it use the existing dial in (isdn)? Where do i tell tinc to use 
it?

Is switch mode the better solution to connect a stand-alone pc to our 
office?

I'm confused ... 

So please, push me to the right direction ...

Thank you very much in advance,


Alex