1. Overview of the CLX System

1.1 What is CLX?

PacketCluster nodes have been around since around 1985. The original PacketCluster idea came from Dick Newell, AK1A, and was running under DOS. Circa in 1992 Dick stopped the development of the PacketCluster software for amateur radio. Many systems are still using this relatively old DOS software today.

CLX is a system which clones a PacketCluster node. To the outside user, commands and features are mostly identical, remote PacketCluster nodes, which can be networked, don't see the difference between a generic PacketCluster node and CLX. So it fits well into an established network of PacketCluster nodes.

1.2 CLX --- Another PacketCluster clone based on Linux

CLX, short for ``Cluster Software running under Linux'' has been under development since February 1994. For many years before we were dreaming of improving Pavillion's PacketCluster software, which was developed in the mid-eighties. Now the time had come.

In order to add features to the cluster software it was necessary to look for a new operating system platform. Under DOS it was practically impossible to improve anything. The 640k memory limit makes things very difficult when it comes to writing a multi user application with up to 60 users or more, handling port interrupts for internal and external TNCs and database queries. So we came to the conclusion to use the Unix platform for this new project. The Linux Operating System seemed like an ideal playground for us.

Here are some of the features of CLX

• Full compatibility with the original PCxx protocol and from a users' point of view. It comes with multitasking and different priorities.
• The software allows loops and multiple connects without generating endless DX spots and announce messages. This is a feature to make the network more reliable.
• CLX uses modern programming concepts like shared memory for common data, lex & yacc for syntax checking, shared libraries to keep binaries small, remote procedure calls for inter process communication. It is strictly modularised with its own dedicated process for every major task.
• CLX can be extended, you can add your own programs and software.
• You may re-use the old PacketCluster database files (*.ful files). They can be imported into the new system without too much trouble.
• CLX is based on a data base system called PostgreSQL version 6.1. Currently, the CLX code consists of about 60,000 lines of C++ code.
• CLX's connectivity is very flexible. It supports the generic AX.25 drivers in the Linux kernel, uses WAMPES, NOS, JNOS or TNOS and plain TCP/IP via telnet. You can accommodate even the wildest network configurations including hook-up to the Internet via a dial-up line. Through the use of universal connect scripts almost everything is possible in CLX.

First on-air experiments started in late May (1994) under the callsign DB0PV-6, which now has become DB0CLX. It currently runs on Linux Version 2.0.25 with Alan Cox's and Jonathan Naylor's AX.25 kernel driver and a KISS connection to the local digipeater.

A current list of CLX users can be found in CLX User List.

1.3 Hardware requirements

CLX runs on PC 386-40 with 8 MB memory.

Well, it creeps.

This is absolutely the minimum. If you have a choice, put in 16 MB of memory or more. It will run much faster then. CLX certainly will appreciate that. Also a faster CPU is not a bad idea. At DB0CLX we currently have a 486-100 with 32 MB RAM and 500 MB disk space.

For an average Linux installation you will need about 50 MB. We have installed a minimal system with 12 MB. CLX is about 5 MB after the installation but the data grows quickly. If you keep log files, these can easily fill up to 10-20 MB. So 100 MB is certainly no luxury.

For a connection to the the external world you can either use a KISS TNC on a serial port, WAMPES, AX.25 over Ethernet or even plain TCP/IP.

1.4 Availability

CLX is available by anonymous ftp from the following address:

ftp://ftp.funet.fi/pub/ham/unix/Linux/cluster/clx

This site is mirrored by many other sites world wide so you may pick up CLX from another place. Be aware, however, that ftp.funet.fi is the place where the most recent version of CLX usually gets uploaded first. Thanks for the ham-admins of ftp.funet.fi for the nice service they provide to the ham community and we hope that we will be able to continue using ftp.funet.fi as our main distribution site.

KB8EHT has offered to make CLX available in the US under the following address:

http://www.timsnet.com/pub/clx