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From: Nate Williams <nate@mt.sri.com>
To: BSD Mailinglisten-User <bsd@birdland.rhein-neckar.de>
Cc: Nate Williams <nate@mt.sri.com>, Peter Hawkins <peter@clari.net.au>,
        freebsd-isp@freebsd.org
Subject: Re: mail weirdness
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[ Popper hanging in the middle of large email downloads ]

> > > Has anyone any clues what may be going on here?
> 
> [...]
> 
> > FWIW, there are some folks running BSDi who see the same problem.  I'm
> > beginning to smell some sort of incompatability in the BSD stack and
> > Qualcomm's popper, but I personally have users who download megabytes of
> > email every day w/out a problem, so maybe it's a modem setup problem?
> 
> We have exactly the same problem. Customers with absolutely stable links 
> (using modems with CSLIP and/or ISDN with PPP) have sometimes problems
> with popper, especially with large mails. I tried to reproduce the 
> problem using perl to no avail....

My suspicion (and it's only that) is that the users somehow have
software hand-shaking set at their end.  Normal traffic is slow enough
(and in short bursts) such that the handshaking isn't a problem
normally, but when they download large email from the ISP it's a long
sustained download that isn't interrupted which would cause the modem to
tell things to slow down.  Since only one end is using software
handshaking, I think things get confused and the modem is never sent the
'XON' signal and everything hangs.

At my site (since I'm really not an ISP but provide similar services to
co-workders on the road and at home) *I* setup their machines (or sit
over their shoulder) and make sure things are setup correctly from their
end using hardware handshaking.


Nate