X.25 Link Configuration

Introduction

X.25 configuration is the process of defining the protocol parameters for X.25 links. Although most X.25 protocol parameters can safely be left as default values, some values, such as the number of logical channels, have to be changed for every installation.

Link configuration is performed by using tsgconfig utility and x25daemon at link initialization time. You can use tsgconfig to edit the configuration files under /usr/lib/x25/config, as specified in /etc/packetnets. tsgconfig does not actually reconfigure the link. You must run x25config or wanware stop; wanware start to have the new configuration take effect.

Note: tsgconfig supports only the most common subset of all X.25 parameters. It may be necessary to edit the link configuration file directly.



Configuration File Location

Link configuration files used by Wanware are found in the /usr/lib/x25/config/ directory. (link0, link1, etc.) This directory also contains the default parameters file (net.defaults) described in the File Structure section below.


File Structure

X.25 configuration files are ASCII text, and can be modified with any text editor. The files may contain blank lines, and the conversion program ignores all text that follows a "#" character. Only one parameter per line. The parameter keyword must always be separated from the parameter value by either a space or =.

For example:

KeywordValue
linkenable YES
linkenable=YES

There are default values for every parameter. You can look at the default values in /usr/lib/x25/config/net.defaults. Changing this file does not affect the defaults. If a parameter is not specified in the configuration file, the default is silently supplied.

When you are creating a link parameter file, using tsgconfig, you only need to specify parameters that differ from the default ones. Therefore, you can set up a link with the exact characteristics described in net.defaults by specifying the name of an empty file.

net.defaults contains comments which describe each item in the file, so you can use it for reference when you create your own link configuration (or modify one of the supplied files). If there is any difference between the following descriptions and the file itself, follow what is in the file as it is more current.

For a description of parameters, see X.25 Link Configuration Parameters.

Things to remember when creating link configuration files:


Link Configuration With tsgconfig

To edit a configuration file, enter the following command:

tsgconfig [-h] [-m] [-n netID|netname]

The main menu appears, presenting a list of known networks. For a description of parameters, see X.25 Link Configuration Parameters. Refer to the Utilities for a description of tsgconfig.

Links Page

Figure 1. Links Page

Use the arrow keys or SPACEBAR and BACKSPACE keys to access items. Press ENTER to select an item.

When you press ENTER on an X.25 link name, a menu for the link appears.

X.25 Configuration Main Menu

Figure 2. X.25 Configuration Main Menu

Miscellaneous screen example
Virtual Circuits screen example
Timers screen example
Counters screen example

When you select Miscellaneous from the menu, a list of parameters appears.

Miscellaneous Configuration

Figure 3. Miscellaneous Configuration

When changing configuration parameters, pressing "?" displays an explanation of the current parameter.

To change a parameter, position the highlight bar over it, then press ENTER. Fields displaying YES or NO, toggle between YES or NO. Pressing ENTER on a numeric value field displays a dialog box where you can change the value. If the parameter expects a value, tsgconfig prompts you for it. Once you change a parameter, an asterisk is displayed to the left of the parameter name.

To save your changes, press "Q". To quit without saving press ESC.

When you select Virtual Circuits from the menu, a list of circuits appears.

Virtual Circuits Configuration

Figure 4. Virtual Circuits Configuration

When you select Timers from the menu, a list of circuit timers appears.

Timers Configuration

Figure 5. Timers Configuration

When you select Counters from the menu, a list of circuit counters appears.

Counters Configuration

Figure 6. Counters Configuration


Changing Link Startup Behaviour

If the data network to which you are connecting is not one of those specified for the netid parameter, you may find that the X.25 link does not start up properly. If you need to change the way the HDLC (LAPB) protocol is started, experiment by changing netid, then restarting the protocol. X.25 Troubleshooting explains how to determine the state of the HDLC link, while X.25 Link Configuration Parameters contains information on the various protocol options associated with different netid values.


Revision 6.3.0 (April 2004)

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