1*4882a593Smuzhiyun.. SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun 3*4882a593Smuzhiyun================== 4*4882a593SmuzhiyunLinux X.25 Project 5*4882a593Smuzhiyun================== 6*4882a593Smuzhiyun 7*4882a593SmuzhiyunAs my third year dissertation at University I have taken it upon myself to 8*4882a593Smuzhiyunwrite an X.25 implementation for Linux. My aim is to provide a complete X.25 9*4882a593SmuzhiyunPacket Layer and a LAPB module to allow for "normal" X.25 to be run using 10*4882a593SmuzhiyunLinux. There are two sorts of X.25 cards available, intelligent ones that 11*4882a593Smuzhiyunimplement LAPB on the card itself, and unintelligent ones that simply do 12*4882a593Smuzhiyunframing, bit-stuffing and checksumming. These both need to be handled by the 13*4882a593Smuzhiyunsystem. 14*4882a593Smuzhiyun 15*4882a593SmuzhiyunI therefore decided to write the implementation such that as far as the 16*4882a593SmuzhiyunPacket Layer is concerned, the link layer was being performed by a lower 17*4882a593Smuzhiyunlayer of the Linux kernel and therefore it did not concern itself with 18*4882a593Smuzhiyunimplementation of LAPB. Therefore the LAPB modules would be called by 19*4882a593Smuzhiyununintelligent X.25 card drivers and not by intelligent ones, this would 20*4882a593Smuzhiyunprovide a uniform device driver interface, and simplify configuration. 21*4882a593Smuzhiyun 22*4882a593SmuzhiyunTo confuse matters a little, an 802.2 LLC implementation for Linux is being 23*4882a593Smuzhiyunwritten which will allow X.25 to be run over an Ethernet (or Token Ring) and 24*4882a593Smuzhiyunconform with the JNT "Pink Book", this will have a different interface to 25*4882a593Smuzhiyunthe Packet Layer but there will be no confusion since the class of device 26*4882a593Smuzhiyunbeing served by the LLC will be completely separate from LAPB. The LLC 27*4882a593Smuzhiyunimplementation is being done as part of another protocol project (SNA) and 28*4882a593Smuzhiyunby a different author. 29*4882a593Smuzhiyun 30*4882a593SmuzhiyunJust when you thought that it could not become more confusing, another 31*4882a593Smuzhiyunoption appeared, XOT. This allows X.25 Packet Layer frames to operate over 32*4882a593Smuzhiyunthe Internet using TCP/IP as a reliable link layer. RFC1613 specifies the 33*4882a593Smuzhiyunformat and behaviour of the protocol. If time permits this option will also 34*4882a593Smuzhiyunbe actively considered. 35*4882a593Smuzhiyun 36*4882a593SmuzhiyunA linux-x25 mailing list has been created at vger.kernel.org to support the 37*4882a593Smuzhiyundevelopment and use of Linux X.25. It is early days yet, but interested 38*4882a593Smuzhiyunparties are welcome to subscribe to it. Just send a message to 39*4882a593Smuzhiyunmajordomo@vger.kernel.org with the following in the message body: 40*4882a593Smuzhiyun 41*4882a593Smuzhiyunsubscribe linux-x25 42*4882a593Smuzhiyunend 43*4882a593Smuzhiyun 44*4882a593SmuzhiyunThe contents of the Subject line are ignored. 45*4882a593Smuzhiyun 46*4882a593SmuzhiyunJonathan 47*4882a593Smuzhiyun 48*4882a593Smuzhiyung4klx@g4klx.demon.co.uk 49