Introduction Prerequisites
Requirements
Components Used
Conventions Configure
Network Diagram
Configurations Verify
Test 1: TCP to X.25 Translation
Test 2: X.25 to TCP translation Troubleshoot NetPro Discussion Forums - Featured Conversations Related Information
Introduction
XOT (X.25 Over TCP) is designed by Cisco Systems, and is detailed in Request For Comments (RFC) 1613,
to transport X.25 over IP internets. 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.
XOT is a method of sending X.25 packets over IP internets through encapsulation of the X.25 Packet Level in
TCP packets.
This document presents a sample configuration that illustrates these two translations:
Transmission Control Protocol (TCP) to X.25 translation.
X.25 to TCP translation.
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
This translation requires the ENTERPRISE feature set, which is only supported on Cisco router platforms
26xx and above.
The information in this document was created from the devices in a specific lab environment. All of the
devices used in this document started with a cleared (default) configuration. If your network is live, make sure
that you understand the potential impact of any command.
Conventions
For more information on document conventions, refer to Cisco Technical Tips Conventions.
Configure
In this section, you are presented with the information to configure the features described in this document.
Note: To find additional information on the commands used in this document, use the Command Lookup
Tool ( registered customers only) .
Network Diagram
This document uses this network setup:
As shown here, back-to-back links are used between Routers 1 and 2 and between Routers 2 and 3.
Configurations
This document uses these configurations:
Router1
Router2
Router3
Note: We have truncated the following configurations to display the relevant information.
Verify
Use the following commands to test that your network is operating properly:
Certain show commands are supported by the Output Interpreter Tool ( registered customers only) , which allows
you to view an analysis of show command output.
show debugenables you to display a variety of debug information, or to perform specific
troubleshooting activities.
telnet 192.168.7.2connects to computer systems on the Internet in prompt mode. ·
pad 345logs you on to a PAD.
show x25 vcdisplays information about active switched virtual circuits (SVCs), and permanent
virtual circuits (PVCs) in privileged EXEC mode.
The output shown in the tests below is a result of entering these commands on the devices shown in the
network diagram above. This output shows that the network is operating properly.
Test 1: TCP to X.25 Translation
In this test, we perform a Telnet session from Router1 to the IP address of Router2:
Telnet 192.168.7.2 from Router1.
Note: This address belongs to the network 192.168.7.0 /24 in Router2. This address must not be
assigned to any other system in the network.
Router2 does a TCP to X.25 translation in order to reach Router3. The output is shown below.
Router2#show debug
TCP:
TCP special event debugging is on
X.29 PAD:
X25 PAD debugging is on
X.25:
X.25 special event debugging is on
Protocol translation:
Protocol Translation debugging is on
Router2#
Router1#telnet 192.168.7.2
Trying 192.168.7.2 ... Open
Trying 123...Open
User Access Verification
Password:
Router3>
Router2#
*Mar 1 01:50:28.759: TCP0: state was LISTEN -> SYNRCVD [23 -> 10.0.0.6(11007)]
*Mar 1 01:50:28.763: TCB00499CAC setting property TCP_TOS (11) C0094
*Mar 1 01:50:28.767: tcppad2: fork started
*Mar 1 01:50:28.767: TCP: sending SYN, seq 3338770911, ack 4026886977
*Mar 1 01:50:28.771: TCP2: Connection to 10.0.0.6:11007, advertising MSS 1460
*Mar 1 01:50:28.775: TCP2: Connection to 10.0.0.6:11007, received MSS 556, MSS is 556
*Mar 1 01:50:28.791: TCP2: state was SYNRCVD -> ESTAB [23 -> 10.0.0.6(11007)]
*Mar 1 01:50:28.803: pad_open_connection: found a valid route
*Mar 1 01:50:28.807: Serial0: X.25 O R1 Call (11) 8 lci 1
*Mar 1 01:50:28.811: From (0): To (3): 123
*Mar 1 01:50:28.811: Facilities: (0)
*Mar 1 01:50:28.815: Call User Data (4): 0x01000000 (pad)
*Mar 1 01:50:28.827: Serial0: X.25 I R1 Call Confirm (5) 8 lci 1
*Mar 1 01:50:28.831: From (0): To (0):
*Mar 1 01:50:28.835: Facilities: (0)
*Mar 1 01:50:28.835: PAD2: Call completed
*Mar 1 01:50:28.839: PAD2: Control packet received.
*Mar 1 01:50:28.851: PAD2: Input X29 packet type 4 (Read X.3 param) len 1
*Mar 1 01:50:28.855: PAD2: Output X29 packet type 0 (Parameter indication) len 45
1:1, 2:1, 3:2, 4:1, 5:0, 6:0, 7:4,
8:0, 9:0, 10:0, 11:14, 12:0, 13:0, 14:0, 15:0,
16:127, 17:21, 18:18, 19:0, 20:0, 21:0, 22:0,
*Mar 1 01:50:28.879: PAD2: Control packet received.
*Mar 1 01:50:28.883: PAD2: Input X29 packet type 6 (Set and Read) len 9
2:0, 4:1, 15:0, 7:21,
Mar 1 01:50:28.887: tcppad2: Sending WILL ECHO
Mar 1 01:50:28.891: PAD2: Output X29 packet type 0 (Parameter indication)len9
Before issuing debug commands, refer to Important Information on Debug Commands.
Troubleshoot
There is currently no specific troubleshooting information available for this configuration.
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