3Com MSR 50 Series Configuration Manual page 325

<RouterD> system-view
[RouterD] interface serial 2/0
[RouterD-Serial2/0] link-protocol x25 dte ietf
[RouterD-Serial2/0] x25 x121-address 2
[RouterD-Serial2/0] x25 map ip 1.1.1.1 x121-address 1
[RouterD-Serial2/0] ip address 1.1.1.2 255.0.0.0
3 Configure Router B
# Enable X.25 switching.
<RouterB> system-view
[RouterB] x25 switching
# Configure local X.25 switching, specifying packets to X.121 address 1 to pass
through Serial 2/0.
[RouterB] x25 switch svc 1 interface serial 2/0
# Configure XOT switching, specifying an X.25 switching route to XOT channel.
[RouterB] x25 switch svc 2 xot 10.1.1.2
# Configure Serial 2/0.
[RouterB] interface serial 2/0
[RouterB-Serial2/0] link-protocol x25 dce ietf
[RouterB-Serial2/0] quit
# Configure interface Ethernet 1/0.
[RouterB] interface ethernet 1/0
[RouterB-Ethernet1/0] ip address 10.1.1.1 255.0.0.0
4 Configure Router C
# Enable X.25 switching.
<RouterC> system-view
[RouterC] x25 switching
# Configure local X.25 switching, specifying packets to X.121 address 2 to pass
through Serial 2/0.
[RouterC] x25 switch svc 2 interface serial 2/0
# Configure XOT switching, specifying an X.25 switching route to XOT channel.
[RouterC] x25 switch svc 1 xot 10.1.1.1
# Configure interface Serial 2/0.
[RouterC] interface serial 2/0
[RouterC-Serial2/0] link-protocol x25 dce ietf
[RouterC-Serial2/0] quit
# Configure interface Ethernet 1/0.
X.25 Configuration Examples 325