Help: Stange connection stalls using PPP

From: Fredderic (fredderic._at_.iprimus.DOT.com.DOT.au)
Date: 07/29/03 

Date: 29 Jul 2003 22:11:25 +1000

I hereby appeal to the internet community, to see if anyone can help me
figure this out:

Iptraf and friends show that new connections are made, run for a couple
kb, then stall permanently. Very low traffic connections however, such
as IRC and ICQ, manage to keep going. But web, email and news, rarely
manage to download the headers. (IRC and ICQ usually can't be restarted
if they fail, however, because the initial burst of traffic stalls)

It was happening a while ago, then it stopped. Now it's started again.
It happens at seemingly random times, and doesn't appear to go away
after disconnecting and reconnecting. However if you leave it long
enough, either online or offline, it does sometimes come back good.

I have less trouble with this stalling problem when the PC's on my LAN
are down (I masq my connection for two other machines), however it does
still sometimes occure. It seems to happen most often during high
traffic periods, especially when I launch five or six new web pages
simultaneously (or, as is more often the case, the sum total of web
pages being loaded at that time comes to five or six).

I originally thought the ISP was being fickle about my rather brutish
firewall, and the problem did seem to dissapear when I made it a little
more RFC-compliant. However plenty of other people seem to get by just
fine with brutish firewalls (though there was a reduction in repeat hits
early on in connections, so I'll be keeping it this way), and as stated,
the problem's back without any further tinkering to either firewall or
network settings.

So the question is, what is it? And, how can I find it? Are there any
good diagnostic packages or quick tests to see if it's the local TCP
stack that's stalling? Any way to check the modem connection without
either downloading, or relying on a functional remote TCP stack? (Which
is where I'm _guessing_ the problem lies)

Fredderic

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