Date: Wed, 04 Apr 2012 08:28:31 +1000 From: Darren Reed <darrenr@freebsd.org> To: Andre Oppermann <andre@freebsd.org> Cc: freebsd-net@freebsd.org Subject: Re: FreeBSD TCP ignores zero window size Message-ID: <4F7B798F.3080203@freebsd.org> In-Reply-To: <4F7B3098.3090901@freebsd.org> References: <4F75C1A3.4030401@freebsd.org> <4F75D9ED.7080707@freebsd.org> <4F780373.6030107@freebsd.org> <4F7AFEEF.60708@freebsd.org> <4F7B1981.1050009@freebsd.org> <4F7B3098.3090901@freebsd.org>
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On 4/04/2012 3:17 AM, Andre Oppermann wrote: > On 03.04.2012 17:38, Darren Reed wrote: >> On 3/04/2012 11:45 PM, Andre Oppermann wrote: >>> It's the other way around. remote.ssh is sending old data >>> which freebsd82.62922 has already ack'ed. The sessions seems >>> to be de-synchronized, perhaps some middle box mucking with >>> the segments trying to modulate something? >> >> I suspect that the ISP is dropping packets and/or applying >> some other means of throttling the connection. So, yes. > > That doesn't explain it. The other side is retransmitting data > we have already received and acknowledged! There is not > nothing we can do on our side. That behavior is totally > non-compliant. > > The zero-window is not involved in this as it would affect > FreeBSD sending data, not the other end sending data. > > Can you try to find out what kind of middle-box is mucking > TCP here on your side and the other side? It must be some > device that actively touches the TCP session transiting > through it. A router with active queue management (like WFQ > or RED) is not enough to cause this behavior. > > What is the OS of your remote.ssh? I should add that given the other end of this is NetBSD I have also been following up discussion of this behaviour on their appropriate list too. That discussion can be found here: http://mail-index.netbsd.org/tech-net/2012/04/01/msg003203.html The currently last installment of which is here: http://mail-index.netbsd.org/tech-net/2012/04/03/msg003216.html Darren
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