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Date:      Sun, 21 Jul 1996 02:35:58 -0700
From:      Paul Traina <pst@shockwave.com>
To:        hackers@freebsd.org, questions@freebsd.org
Subject:   SIO problems - random "deafness" on my serial lines
Message-ID:  <199607210935.CAA11638@precipice.shockwave.com>

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After 3 weeks of flawless operation, I've recently started having problems with
*both* the kernel mode and the iij ppp code when I connect with my ISP.

I'm trying to make sure that the problem isn't on my side, as I've never seen
this problem with Ascends until recently on two -current systems.

Basicly, the remote side appears to go deaf under *bursty* traffic loads and
the link remains dead until I restart it by hanging up.  By dead, I mean that
even LCP echos are not being received back, and turning on tons of debugging
shows data being fed to the internal modem.  I can't debug past there.

This could either mean send buffers are wedged/full on my side, or I've got
flaky modem/serial 16550 emulation on the modem, or the problem really is
with "the other guy."

I'm using some relatively cruddy $99 TI modems which are relatively suspicious
clones of the US Robotics Sportster 288/344 + PnP.

The interesting thing is that it seems to happen most often when I would be
seeing the window opening up on a second TCP flow, which makes me insanely
suspicious of the 16550 emulation hardware or our driver.

Any suggestions as to where to start digging to get into the guts of our
driver?

Anyone else see anything suspicious like this?

Paul



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