Xref: utzoo comp.protocols.iso:1253 comp.protocols.tcp-ip:13138
Path: utzoo!attcan!uunet!jarthur!usc!julius.cs.uiuc.edu!apple!voder!pyramid!csg
From: csg@pyramid.pyramid.com (Carl S. Gutekunst)
Newsgroups: comp.protocols.iso,comp.protocols.tcp-ip
Subject: Re: SLIP over X.25
Message-ID: <128135@pyramid.pyramid.com>
Date: 24 Sep 90 20:21:27 GMT
References: <1990Sep18.143414.4441@hq.demos.su> <1990Sep19.112128.2154@swbull.bull.se> <BOB.90Sep19164020@volitans.MorningStar.Com> <PATRICK.HAYES.90Sep24152302@troy.cediag.bull.fr>
Reply-To: csg@pyramid.pyramid.com (Carl S. Gutekunst)
Organization: Pyramid Technology Corp., Mountain View, CA
Lines: 21

>The major problem seems to be that B.O.S.'s X3/X29 interface uses one line-
>discipline, and SLIP uses another. Trying to use both blows my connection.

Bingo. You're probably stuck. A *good* X.29 implementation will operate as a
real tty device driver, and hence be able to use any line discipline. This is
needed not only for SLIP, but also for xt and sxt drivers. Alas, many vendors,
including Bull apparently, implement X.29 *as* a line discipline; so trying to
switch to SLIP kills X.29. The other blunderous and common way to implement
X.29 is to not hook into the tty driver at all, or only minimally. Then a
request to change the line discipline is simply ignored. 

(Note that we're talking all Berkeley/V7 style tty devices here. Under Streams
all the rules change. Generally, it's easier to get it right with Streams.)

[Enter Flame Mode: My big gripe with virtually everyone who is implementing
CCITT and ISO protocols on UNIX is that they insist on forcing new and unusual
paradigms on the users, instead of implementing the protocols in such a way
that they fit well into UNIX paradigms. The present implementations of X.400
are especially extreme examples, seeming to have been designed in a vacuum.]

<csg>