Configuring X2T

X.25 to TCP switch (X2T) connects X.25 to TCP/IP networks, allowing the access between X.25 and IP hosts. Figure 134 shows a typical X2T application scenario.

The X.25 terminal has an X.121 address on the IP host. Whenever the router receives an X.25 call request packet, it checks the destination address of X.121 in the packet and looks up in the X2T routing table for a match. If a matching route is found, the router will set up a TCP connection with the host at the destination IP address of the X2T route. After that, the router will extract the pure data from the X.25 packet and send it to the IP host through the TCP connection.

The IP host can go through the IP address on the interface of the IP network to access the X.25 host. Whenever the router receives a TCP connection request, it checks the destination IP address and TCP port number of the TCP connection and looks up in the X2T routing table for a match. If a match is found, the router will set up an X.25 SVC destined to the host at the associated destination X.121 address of the X2T route. After that, the router will extract the pure data from the TCP packet and send it to the X.25 host through the X.25 SVC. If the router sets up a PVC connection with the X.25 host, it transmits the data directly to X.25 host through X.25 PVC.