X25 and isdn

[brucebanner]

Hi folks,

I have a Server which i used for isdn/x25 connection to my local provider. now i want to substitue my server with a router. what i need to know therefore is , how on earth am i going to make a X25 over isdn connection, when the X25- ISP-machine I'm authenticated before doesn't have an IP address. as far as i know i need to map the x121 address to a layer 3 address which is the ip address or can i also map the x121 to an isdn-nr.

thx for your contribution

 

[KY]

Hi Bruce,
I've set up a similar solution for Siemens HiComs. You can route X25 over ip with XOT, it's pretty ok to do, but you need a dedicated interface on the router for the X25 device, so don't forget to spec for this, also not all routers support XOT (X25 over TCP/IP). I know for a fact that most 800 models don't (still got 2 that I bought in error on a shelf...), check on cisco.com first... Also you will need to research the interface/cabling requirements for your x25 device...

Here's my PNE conf:

!
x25 routing (enables x25)
!
interface Serial0/0
description XOT/X25 PNE SERIAL LINK
ip address x.x.x.x x.x.x.x (a routable ip address)
no ip redirects
no ip unreachables
no ip proxy-arp
encapsulation x25 dce
x25 address 009000217 (whatever your device address is)
clock rate 9600 (again, depends on the device)
!
!
x25 route 009000217 interface Serial0/0 (should map the ip to x25 address)



For the router at remote end of your ISDN use this conf:

!
x25 routing (enables x25)
!
!
x25 route 009000217 xot x.x.x.x (whatever ip address you set up on your local router)

Hope this helps!

 

[brucebanner]

Hi KY,

thx for your reply,

in my case i dont have a TCP/IP net, i have to dial out over the PSTN / ISDN and over ISDN there will be x25 running, my problem is i dont know the ip address of the
remote device in order to map the x121 address to a Layer3 address.

DO i neccessarily need a L3 address to dial out or not?

Thx again

 

[KY]

Sorry, I assumed you would already be thinking about ip routing over the isdn...
I would have thought ip is the solution, you are looking at routing traffic from one place to another, and routing is layer 3. IP is the most widely used layer 3 protocol. I don't know if you can encapsulate an isdn line with raw x25, I've never tried or even looked into it.
wrt knowing the remote ip, you would also configure that address (or get the other end to do it). It would be a mirror of your end.
If I was setting this up I would go with ip routing over the isdn with the x25 stuff encapsulated with xot... any one else have any thoughts?