X.25 subinterface configuration example
Network requirements
Configure multiple subinterfaces on a physical interface for connecting to multiple network segments.
In Figure 141, Router A is configured with two subinterfaces, which are connected with Router B and Router C. Router D operates as an X.25 switch.
Configure the subinterfaces, so that Router A can communicate with Router B and Router C, respectively.
Figure 141: Network diagram
![](images/image137.png)
Configuration procedure
Configure Router A:
<RouterA> system-view [RouterA] interface serial 2/0 [RouterA-Serial2/0] link-protocol x25 dte [RouterA-Serial2/0] x25 x121-address 100 [RouterA-Serial2/0] quit
# Configure subinterface Serial 2/0.1, and X.25 mapping to Router B.
[RouterA] interface serial 2/0.1 [RouterA-Serial2/0.1] ip address 10.1.1.2 255.255.0.0 [RouterA-Serial2/0.1] x25 map ip 10.1.1.1 x121-address 200 [RouterA-Serial2/0.1] quit
# Configure subinterface serial 2/0.2, and X.25 mapping to Router C.
[RouterA] interface serial 2/0.2 [RouterA-Serial2/0.2] ip address 20.1.1.2 255.255.0.0 [RouterA-Serial2/0.2] x25 map ip 20.1.1.1 x121-address 300 [RouterA-Serial2/0.2] quit
Configure Router B:
<RouterB> system-view [RouterB] interface serial 2/0 [RouterB-Serial2/0] link-protocol x25 dte [RouterB-Serial2/0] x25 x121-address 200 [RouterB-Serial2/0] x25 map ip 10.1.1.2 x121-address 100 [RouterB-Serial2/0] ip address 10.1.1.1 255.255.0.0
Configure Router C:
<RouterC> system-view [RouterC] interface serial 2/0 [RouterC-Serial2/0] link-protocol x25 dte [RouterC-Serial2/0] x25 x121-address 300 [RouterC-Serial2/0] x25 map ip 20.1.1.2 x121-address 100 [RouterC-Serial2/0] ip address 20.1.1.1 255.255.0.0
Configure Router D as an X.25 switch:
<RouterD> system-view [RouterD] interface serial 2/0 [RouterD-Serial2/0] link-protocol x25 dce [RouterD-Serial2/0] quit [RouterD] interface serial 2/1 [RouterD-Serial2/1] link-protocol x25 dce [RouterD-Serial2/1] quit [RouterD] interface serial 2/2 [RouterD-Serial2/2] link-protocol x25 dce [RouterD-Serial2/2] quit
# Configure SVC switching routes.
[RouterD] x25 switching [RouterD] x25 switch svc 100 interface serial 2/0 [RouterD] x25 switch svc 200 interface serial 2/1 [RouterD] x25 switch svc 300 interface serial 2/2
Verifying the configuration
The virtual circuit configured in this example is an SVC. The routers establish it only when they must communicate.
# Ping Router B from Router A.
[RouterA] ping 10.1.1.1 PING 10.1.1.1: 56 data bytes, press CTRL_C to break Reply from 10.1.1.1: bytes=56 Sequence=1 ttl=255 time=64 ms Reply from 10.1.1.1: bytes=56 Sequence=2 ttl=255 time=52 ms Reply from 10.1.1.1: bytes=56 Sequence=3 ttl=255 time=53 ms Reply from 10.1.1.1: bytes=56 Sequence=4 ttl=255 time=52 ms Reply from 10.1.1.1: bytes=56 Sequence=5 ttl=255 time=52 ms --- 10.1.1.1 ping statistics --- 5 packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 52/54/64 ms
The output shows that the SVC has been established between the two routers.
# Display the X.25 address mapping table on Router A.
[RouterA] display x25 map Interface: Serial2/0.2(protocol status is UP) ip 20.1.1.1 X.121 address:300 Map-type: SVC_MAP VC-number: 0 Facility: Interface: Serial2/0.1(protocol status is UP) ip 10.1.1.1 X.121 address:200 Map-type: SVC_MAP VC-number: 0 Facility:
# Display X.25 virtual circuit information on Router A.
[RouterA] display x25 vc Interface: Serial2/0.1 SVC 1024 State: P4(transmit) Map: ip 10.1.1.1 to 200 Window size: input 2 output 2 Packet Size: input 128 output 128 Local PS: 5 Local PR: 5 Remote PS: 4 Remote PR: 5 Local Busy: FALSE Reset times: 0 Input/Output: DATA 5/5 INTERRUPT 0/0 RR 0/0 RNR 0/0 REJ 0/0 Bytes 420/420 Send Queue(Current/Max): 0/200
# Display the X.25 SVC switching table of Router D.
[RouterD] display x25 switch-table svc static Number Destination Substitute-src Substitute-dst CUD SwitchTo(type/name) 1 100 I/Serial2/0 2 200 I/Serial2/1 3 300 I/Serial2/2 Total of static svc is 3. The item type of SwitchTo meaning: I: interface H: hunt-group T: xot [RouterD] display x25 switch-table svc dynamic #1 (In: Serial2/0 - SVC1024) <--> (Out: Serial2/1 - SVC1 )