Cisco CCIE: X.25 on the D Channel

In preparation of your CCNP exam, we want to make sure we cover the various concepts that we could see on your Cisco CCNP exam. So to assist you, below we will discuss on of the more difficult CCNP concepts; X.25 on the D Channel. As you progress through your CCNP exam studies, I am sure with repetition you will find this topic becomes easier. So even though it may be a difficult concept and confusing at first, keep at it as no one said getting your Cisco certification would be easy!

Introduction

This document presents a sample configuration of X.25 on the ISDN D channel.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.

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.

Background Information

X.25 on the D channel is a feature that was introduced in Cisco IOS® Software release 11.2(4)F. Hence, it is also available in 11.3 and higher IOS main releases. To view the original feature description, see Release Notes for Cisco IOS Release 11.2F.

Currently, the IOS software allows two ways to transport X.25 traffic on the ISDN D channel:

The first method is the aforementioned X.25 on the D channel feature, available since IOS version 11.2(4)F. The sample configuration shown in this document corresponds to this first method.

The second method is the X.25 on ISDN using Always On/Direct ISDN (AO/DI) feature, available since IOS version 11.3(3)T.

To configure X.25 traffic over an ISDN D channel, refer to the Configuring X.25 on ISDN and Configuring X.25 on ISDN using Always On/Dynamic ISDN (AO/DI) chapters in the Dial Solutions Configuration Guide.

For a complete description of the commands, refer to the X.25 on ISDN Commands and X.25 on ISDN using Always On/Dynamic ISDN (AO/DI) Commands chapters in the Dial Solutions Command Reference.

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

The Telephone Company's switch must provide the X.25 on the ISDN D channel service. In the sample configuration shown below, the static terminal endpoint identifier (TEI) configured must also be given by the Telephone Company.

Configurations

This document uses these configurations:

Verify

This section provides information you can use to confirm your configuration is working 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 x25 vcDisplay information about active switched virtual circuits (SVCs) and permanent virtual circuits (PVCs)

show x25 mapDisplay information about configured address maps

  remote#ping 192.168.1.2
  Type escape sequence to abort.
  Sending 5, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds:
  !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 392/412/428 ms
  remote#

  remote#show x25 vc
  SVC 2, State: D1, Interface: BRI0:0
  Started 00:01:08, last input 00:00:32, output 00:00:32
  Connects 2231146 <-> ip 192.168.1.2
  Call PID cisco, Data PID none
  Window size input: 2, output: 2
  Packet size input: 128, output: 128
  PS: 3? PR: 3? ACK: 2 Remote PR: 3? RCNT: 1 RNR: no
  P/D state timeouts: 0 timer (secs): 27
  data bytes 1900/1900 packets 19/19 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
  remote#

  remote#show x25 map
  BRI0:0: X.121 2231146 <-> ip 192.168.1.2
  permanent, 0 VC:

Troubleshoot

Troubleshooting Commands

Note: Before issuing debug commands, refer to Important Information on Debug Commands.

debug x25Display information about all X.25 traffic or a specific X.25 service class

Output from the debug x25 command is shown here:

  remote#
  00:13:44: BRI0:0-D: X.25 O R1 Call (18) 8 lci 2
  00:13:44: From (11): 12503372501 To (7): 2231146
  00:13:44: Facilities: (0)
  00:13:44: Call User Data (4): 0xCC000000 (ip)
  00:13:44: BRI0:0-D: X.25 I R1 Call Confirm (14) 8 lci 2
  00:13:44: From (11): 12503372501 To (7): 2231146
  00:13:44: Facilities: (0)
  remote#

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