1Linux X.25 Project
2
3As my third year dissertation at University I have taken it upon myself to
4write an X.25 implementation for Linux. My aim is to provide a complete X.25
5Packet Layer and a LAPB module to allow for "normal" X.25 to be run using
6Linux. There are two sorts of X.25 cards available, intelligent ones that
7implement LAPB on the card itself, and unintelligent ones that simply do
8framing, bit-stuffing and checksumming. These both need to be handled by the
9system.
10
11I therefore decided to write the implementation such that as far as the
12Packet Layer is concerned, the link layer was being performed by a lower
13layer of the Linux kernel and therefore it did not concern itself with
14implementation of LAPB. Therefore the LAPB modules would be called by
15unintelligent X.25 card drivers and not by intelligent ones, this would
16provide a uniform device driver interface, and simplify configuration.
17
18To confuse matters a little, an 802.2 LLC implementation for Linux is being
19written which will allow X.25 to be run over an Ethernet (or Token Ring) and
20conform with the JNT "Pink Book", this will have a different interface to
21the Packet Layer but there will be no confusion since the class of device
22being served by the LLC will be completely separate from LAPB. The LLC
23implementation is being done as part of another protocol project (SNA) and
24by a different author.
25
26Just when you thought that it could not become more confusing, another
27option appeared, XOT. This allows X.25 Packet Layer frames to operate over
28the Internet using TCP/IP as a reliable link layer. RFC1613 specifies the
29format and behaviour of the protocol. If time permits this option will also
30be actively considered.
31
32A linux-x25 mailing list has been created at vger.kernel.org to support the
33development and use of Linux X.25. It is early days yet, but interested
34parties are welcome to subscribe to it. Just send a message to
35majordomo@vger.kernel.org with the following in the message body:
36
37subscribe linux-x25
38end
39
40The contents of the Subject line are ignored.
41
42Jonathan
43
44g4klx@g4klx.demon.co.uk
45