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 the tsgconfig utility and the 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 x25net stop; x25net start to have the new configuration take effect.
Note: tsgconfig supports only the most common subset of all X.25 parameters. In rare situations, it may be necessary for you to edit the file directly.
Link configuration files used by Netcom II are found in the /usr/lib/x25/config/ directory.
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 can occur on a line, and a parameter keyword must always be separated from the parameter value.
Parameters and their values are separated by either a space or =. For example:
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 in the configuration file you specify is not present, the default is silently supplied.
Things to remember when creating link configuration files:
Parameter order doesn't matter. If you duplicate a parameter, the
last value is used.
When you are creating a link parameter file, 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.
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.
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.
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.
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.
When you select Timers from the menu, a list of circuit timers appears.
When you select Counters from the menu, a list of circuit counters appears.
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.
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