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Re: Alex Bochannek: TCP issue.



My GF had a similiar problem:
user on a modem (through earthlink) would hang on certain messages.
The laptop on the LAN had no problems but did via modem.

Now, a number of things were happening on the network at the time,
not the least was a provider change.  On a whim, (and some other
reasons), they switched the CSU/DSU to the old one.  The problem went
away.

She wasn't sure if it was some CSU/DSU setting that was wrong on
the new one or if SOMETHING else had changed on the net.  By that
time, there were 10 other trouble tickets to handle.

Big Packets that get frag'd (by a CSU/DSU?).  No clue.  Perhaps
someone else can draw some sane conclusions.


Quick debuging option might include throwing up alternate POPPER
(qpopper, cucipop, who cares?) and use TCPD to direct THAT users
machine to use the new popper.  Locking will be different, changes
might occur.  Ideally, you could type into the POP protocol directly
(eg "USER xxx\n PASS yyy\n  RETR 1\n").

Indepth sniffing may also help.
c

Quoting Alex Bochannek (alex@p9.com):
> Has anybody had a chance to look at this problem below? I am starting
> to get some heat to replace the system with a Linux box which I would
> rather not do. Any ideas how to debug this further?
> 
> Thanks.
> 
> Alex.
> 

> From: Alex Bochannek <alex@p9.com>
> 
> I have observed an interesting problem which is related to TCP. Our
> POP/IMAP server (imap-4.6.BETA) works great for everybody here. One
> user has been complaining though that when how tries to download large 
> messages from home, "it just hangs". Here are some of the parameters
> that I think we have been able to establish:
>