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Whole document tree 5. A note on callsigns, addresses and things before we startEach AX.25 and NET/ROM port on your system must have a callsign/ssid allocated to it. These are configured in the configuration files that will be described in detail later on. Some AX.25 implementations such as NOS and BPQ will allow you to configure the same callsign/ssid on each AX.25 and NET/ROM port. For somewhat complicated technical reasons Linux does not allow this. This isn't as big a problem in practice as it might seem. This means that there are things you should be aware of and take into consideration when doing your configurations.
5.1. What are all those T1, T2, N2 and things ?Not every AX.25 implementation is a TNC2. Linux uses nomenclature that differs in some respects from that you will be used to if your sole experience with packet is a TNC. The following table should help you interpret what each of the configurable items are, so that when you come across them later in this text you'll understand what they mean.
5.2. Run time configurable parametersThe kernel allows you to change many parameters at run time. If you take a careful look at the /proc/sys/net/ directory structure you will see many files with useful names that describe various parameters for the network configuration. The files in the /proc/sys/net/ax25/ directory each represent one configured AX.25 port. The name of the file relates to the name of the port. The structure of the files in /proc/sys/net/ax25/portname/ is as follows:
In the table T1, T2 and T3 are given in seconds, and the Idle Timeout is given in minutes. But please note that the values used in the sysctl interface are given in internal units where the time in seconds is multiplied by 10, this allows resolution down to 1/10 of a second. With timers that are allowed to be zero, e.g. T3 and Idle, a zero value indicates that the timer is disabled. The structure of the files in /proc/sys/net/netrom/ is as follows:
The structure of the files in /proc/sys/net/rose/ is as follows:
To set a parameter all you need to do is write the desired value to the file itself, for example to check and set the ROSE window size you'd use something like:
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