X25 and TCPIP on the same interface

[a.mountouris]

Hello forum,

consider the following case:

RouterA-----x25----RouterB

We want to pass both x25 native traffic plus TCPIP traffic on the same line that connects the two routers. X25 packets will be switched to other serial interfaces and tcpip traffic will be forwarded to ethernet interfaces.

How should we configure the serial interfaces of A and B??

Is this a case of TCP/IP over x25 (opposite of xot)???

[#2]

XOT is X25 Over TCP, Request For Comments (RFC) 1613. This allows X.25 packets to be sent over a Transmission Control Protocol/Internet Protocol (TCP/IP) network instead of a Link Access Procedure, Balanced (LAPB) link.

http://www.cisco.com/warp/public/133/x25_over_tcpip.html

[GRAEME DANIELSON]

As above, it is more usual to have the link running IP and then pass encapsulated x.25 over it using XOT.

If you have to keep the link running x.25 you can encapsulate IP traffic inside either x.25 SVCs or PVCs.

You can configure an ip address on an interface that is running x.25 (encapsulation x25) but that doesn't mean that IP will run over the link on it's own. Since IP and x.25 are both Layer3 protocols you need to help them out by manually mapping an IP address to either an x.25 PVC or SVC.

For x.25 SVCs you map IP addresses to x.25 (x.121) addresses using the "x25 map ip ..." command

RouterA-----x25----RouterB

X.121 33301 44401

IP 1.1.1.1 1.1.1.2

!RouterA

x25 map ip 1.1.1.2 44401

!RouterB

x25 map ip 1.1.1.1 33301

For PVCs you can map IP address to PVCs using the "x25 pvc ..." command

RouterA-----x25----RouterB

PVC 5 5

IP 1.1.1.1 1.1.1.2

!RouterA

x25 pvc 5 ip 1.1.1.2

!RouterB

x25 pvc 5 ip 1.1.1.1