Subject: Re: critical networking problem
To: None <>
From: Michael L. VanLoon -- <>
List: tech-net
Date: 03/28/1996 21:24:37
>I have noticed that I can reproducably kill tcp connections by sending
>whole ethernet blocks of zeros down them. For example, if I try to
>upload via FTP the file created by the command 

I don't know if this is related, but I also have problems with PPP and
Netscape.  My ppp connection runs mail without a hitch, and even does
OK with single-connection bursty traffic like sup.  But, it seems
like, without fail, if I start up Netscape, I will lock up the ppp
connection at least a few times before a page is finished loading.

The symptom is it will start loading whatever page I've specified,
then it will stall.  I have ppp set up to send LCP echo packets every
15 seconds.  I'll go over to the window where I have "tail -f
/var/log/debug" running, and it will be, at that point, sendind echo
packets without receiving responses until it times out, kills the
connection, and starts a new one (I have an auto-redial script, too),
where it will take up where it left off, possibly dying like this a
few more times, after grabbing a few kilobytes more of data.

Sometimes, telnet, with lots of little bouncy packets will trigger it,
also (telneting to or from my box, over the link).

Now that I think about it, I don't believe this could have anything
obvious to do with TCP, since it's happing below there at the ppp
device level, or somewhere close.

It could just be the old Livingston Portmaster on the other side -- I
really can't verify that.  But it is frustrating.  Anyone else heard
of anything like this?

FYI, I have tried turning all the header compression off, with no
benefit.  I've also tried turning my modem compression off, with no
benefit.  I have used this very same modem to connect my NT box to the
Microsoft campus via RAS (MS ppp), and I have had a connection stay up
for five hours, with both sporadic and heavy traffic, so I know it's
not the modem.

  Michael L. VanLoon                       
       --<  Free your mind and your machine -- NetBSD free un*x  >--
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