tlug: RH 5.0 and ISDN woes

[Rex Walters <rex@example.com>]

Anyone using a NEC ATerm here in Japan with RedHat 5.0?

In a fit of hysterical optimism I upgraded my home machine to RedHat 5.0
(from a heavily hacked upon slackware system).  For the most part this
went without a hitch, but I'm having no end of woes with my ISDN
connection to my ISP (Global Online).

Prior to the upgrade I had no problem at all communicating with my ISDN
TA (I'm using a NEC ATerm IT55DSU) at 115200 bps, and regularly got ~7
KB/s transfer rates during ftp transfers (right about what I'd expect
for a 64 K line).  After the upgrade, however, I can *only* connect at
38400 bps and even if I connect successfully the connection drops at
random intervals (usually a few KB before the end of some huge transfer
I'm in the middle of -- sigh).  I can't for the life of me figure out
what's going on. 

Win95 and Win95J both work fine (I keep 'em around for the random
irritating mail attachment) but of course need the NEC driver.  I may
have done something long ago to my original linux setup to use the
ATerm, but I don't remember making any changes (as far as I remember, it
just looks like a fast modem as far as linux is concerned).

It isn't a ppp configuration issue (at least not entirely) because the
problem manifests itself even if I dial manually with minicom.

If I connect to the TA with minicom at 115200 (or 57600) I can talk to
the TA fine (typing "at" returns an "OK") but when I dial with ATDT it
eventually drops the line (and generates a "NO CARRIER" message).  If I
configure minicom to use 38400 and then dial with ATDT I get a "CONNECT
38400" message and I'm able to log in and fire up ppp just fine.  Again
though, if I start up ppp at 38400 and keep the link active (packets in
and out) the link refuses to stay up for longer than 10 or 20 minutes
(the remote modem appears to hangup at random times -- 3 minutes, 8
minutes, ...., almost like a human is closing the connection manually).

I've turned on pppd debugging, and the system logs show timeouts sending
configuration requests (CCP?) but if I remember correctly these occured
before the upgrade, too.

I've upgraded to the latest ATerm firmware, and I've added all the
latest libraries, pppd, initscripts, etc. from the RedHat site, all to
no avail.

I've even fooled around with setserial and spd_vhi (which shouldn't be
necessary) but still no joy.

Any and all suggestions will be greatly appreciated.  I can't figure
this one out for the life of me (it really annoys me that I had it all
working before and now can't get back where I started).

TIA
-- 
Rex

P.S.  Oh!  One other small change that I made at the same time as the 
      OS upgrade that *might* be related....  I also upgraded from a
      90 MHz AMD clone to a 200 MHz pentium.  I'm actually clocking at
      less than 200 MHz, though (another story) and if this were the
      problem, I'd expect Win95 to also fail to connect.  Dunno.
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