daveb@llama.rtech.UUCP (Dave Brower) (07/30/87)
I have stumbled over some mumblespeak documentation about x25
programming on one (nameless) vendors's UNIX system. It contains a lot
of standards-y talk about bytes in messages, and is a bit drier than my
present interest can tolerate: It doesn't include any C program
examples that would show how one _really_ uses it.
I would appreciate pointers to any sample programs using an x25 link, or
to a tutorial programming guide.
Finally, what x25 support is available for various UNIX machines? Is
there any programming interface standard, or is it every manufacturer to
himself? For instance, our SV.2 VAX source contains source that
certainly looks like it is x25 related, but there doesn't seem to be any
documentation on what it does or how to use it.
Thanks in advance,
-dB
{amdahl, cbosgd, mtxinu, ptsfa, sun}!rtech!daveb daveb@rtech.uucpheath@ncrcae.Columbia.NCR.COM (Robert Heath) (07/31/87)
You brought up a good point -- there is practically no material on how to program for an X.25 link. There is also no standard programming inteface. One reason is that most applications interface at a level higher than X.25. (Consider why noone writes applications for an RS-232 interface.) The X.25 which you get with SVr2 UNIX is almost useless for general X.25 networking. X.25 is typically used with higher, PAD (packet assembler/disassembler) layers such as: X.3, X.28, or X.29 which map TTY data streams to X.25 QLLC (qualified link level control) for mapping SNA to X.25 OSI layer 3A, which maps OSI network layer to X.25 DSP which maps 3270 BSC data to X.25, or BPAD which maps 2780/3780 BSC to X.25 Though one could write an application to interface directly to X.25, its interconnectability would be limited. For a description of how we created a useful interface for the X.25 on the NCR TOWER, see my article in the Feb. '87 issue of Data Communications magazine on UNIX and X.25. Robert Heath heath@Columbia.NCR.COM ncrcae!heath
gwyn@brl-smoke.ARPA (Doug Gwyn ) (08/02/87)
In article <24642@sun.uucp> guy%gorodish@Sun.COM (Guy Harris) writes: > -rw-rw-r-- 1 sys 0 Dec 31 1969 bx25b.c Those aren't just 0-length files; from the date one can guess that the inodes have been zapped. I vaguely recall that I once had a batch of non-null bis-X25 files in one of our AT&T distributions (I don't maintain them on-line since we don't use them here). I don't know WHAT happened to the ones Guy has. "Very interesting..."
guy%gorodish@Sun.COM (Guy Harris) (08/02/87)
> Those aren't just 0-length files; from the date one can guess that > the inodes have been zapped. Most likely, they were zapped by AT&T. When I read in the X.25 tape at CCI, all the X.25 source files had zero length; it seems extremely unlikely that the exact same zapping occurred on two different machines. Somebody else reported to me that their S5R2 and S5R2V2 tapes both had zero-length files for the X.25 source - but with different modification times! Guy Harris {ihnp4, decvax, seismo, decwrl, ...}!sun!guy guy@sun.com
guy%gorodish@Sun.COM (Guy Harris) (08/02/87)
> Those aren't just 0-length files; from the date one can guess that > the inodes have been zapped. Not necessarily. A more likely possibility is that the files were truncated to zero length, and the modification times cranked back to the epoch with something like the "touch" command, before they cut the S5R2 tape at AT&T. An additional interesting data point, from the S5 "Release 1" tape: gorodish$ cd /archbeluga/s5/usr/src/uts/vax/io gorodish$ ls -l *x25* -rw-rw-r-- 1 sys 0 Nov 3 1982 x25b.c -rw-rw-r-- 1 sys 0 Nov 3 1982 x25m.c -rw-rw-r-- 1 sys 0 Nov 3 1982 x25r.c -rw-rw-r-- 1 sys 0 Nov 3 1982 x25s.c -rw-rw-r-- 1 sys 0 Nov 3 1982 x25u.c Still zero-length, but with a non-zero mod time. Guy Harris {ihnp4, decvax, seismo, decwrl, ...}!sun!guy guy@sun.com