pete@octopus.UUCP (Pete Holzmann) (03/23/89)
Rather than try more homebrew solutions, I actually called Telebit product
support yesterday. Here's what they said (and the remaining questions I
will call back for today, and post a second message with the answers):
1) No need to go back to rev 3.0. The new 'micropackets' in the 4.0 ROMs
can cause havoc on low quality connections. Setting S120=12 disables
micropackets and makes your connection look just like rev 3.0. If that
isn't enough, go to S120=2, which also disables short packets, leaving
you just 'long' packets. That will make interactive response terrible,
but should make things happier for file transfers.
2) It turns out that the retrains-leading-to-connection-death syndrome is
usually caused by the following: on an international connection, the
first part of any burst of information is often chopped off by the
phone connection (satellite echo cancellers? I don't know...). Normally,
this would destroy the first part of a data packet. If too much of this
happens, the modems will retrain. If it happens a LOT, they'll retrain
a LOT, and eventually give up. To solve this, use the J6S36 register
(that is NOT a typo: it is a hidden debug register...). The default
value is 0. As you increase the value to 1,2, or 3, you cause an
increasing period of "guard tone" to be inserted before each packet
is sent. The guard tone gets chopped rather than your data, and you
don't have any retrains any more. The guy I talked to suggested starting
at J6S36=2, increasing to 3 if that doesn't help, decreasing to 1 if
it works great (just in case you can get along with less tone).
3) If S120 is non-zero, it will show up in your ATN?. J6S36 will never show
up.
4) From personal experiment, S120 *is* saved by AT&W. I have no easy way
to tell whether J6S36 is saved.
My remaining questions, which will hopefully be answered in a call to Telebit
today, are:
a) Is J6S36 saved? (And what about Naomi? :-) (old, very old, Sesame Street
Joke)
b) Must these parameters be used at both ends of the line?
c) Does J6S36 exist in earlier versions of the ROM
d) Why not auto-increase the J6S36 value if there is trouble?
Hope this helps! I am anxious to hear about results! I'm trying to help
some people get a trans-pacific connection to work correctly...
Pete
--
Peter Holzmann, Octopus Enterprises |(if you're a techie Christian & are
19611 La Mar Ct., Cupertino, CA 95014 |interested in helping w/ the Great
UUCP: {hpda,pyramid}!octopus!pete |Commission, email dsa-contact@octopus)
DSA office ans mach=408/996-7746;Work (SLP) voice=408/985-7400,FAX=408/985-0859kunkee@ficc.uu.net (randy kunkee XNX MGR) (03/24/89)
| | 1) No need to go back to rev 3.0. The new 'micropackets' in the 4.0 ROMs | can cause havoc on low quality connections. Setting S120=12 disables | micropackets... | but should make things happier for file transfers. | ... | a LOT, and eventually give up. To solve this, use the J6S36 register | (that is NOT a typo: it is a hidden debug register...). The default | value is 0. As you increase the value to 1,2, or 3, you cause an | increasing period of "guard tone" to be inserted before each packet | ... | 3) If S120 is non-zero, it will show up in your ATN?. J6S36 will never show | up. | ... | | b) Must these parameters be used at both ends of the line? | No, not according to my conversations with Telebit. Set one end and the other follows suit. This makes a lot of sense. Just 'cause you can't do micropackets across a satellite is no reason to have to disable them for local phonecalls too. ... | | d) Why not auto-increase the J6S36 value if there is trouble? Sounds like a great idea to me. I've been playing with those registers too. No breakthroughs yet. My main point here when I call Telebit they are courteous and helpful. However, their backlog is usually a day or two to return your phone call. I don't think I'd suggest holding. By the way, I asked and they are probably going to come out and document those mystery registers. -- Randy Kunkee Ferranti International Controls Corporation 12808 W. Airport Blvd. Sugar Land, TX 77478 UUCP: uunet!ficc!kunkee ph: (713) 274-5132