From: Christoph Paasch <christoph.paasch@uclouvain.be>
To: Phil Oester <kernel@linuxace.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
Corey Hickey <bugfood-ml@fatooh.org>,
Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
Linux Netdev List <netdev@vger.kernel.org>,
netfilter-devel@vger.kernel.org
Subject: Re: NAT stops forwarding ACKs after PMTU discovery
Date: Mon, 19 Aug 2013 17:33:28 +0200 [thread overview]
Message-ID: <20130819153328.GH3583@cpaasch-mac> (raw)
In-Reply-To: <20130819143509.GA31320@linuxace.com>
On 19/08/13 - 07:35:09, Phil Oester wrote:
> On Mon, Aug 19, 2013 at 06:58:05AM -0700, Eric Dumazet wrote:
> > Yeah, but here, this is conntrack who is blocking the thing.
> >
> > TCP receiver has no chance to 'fix' it.
> >
> > See conntrack is one of those buggy middle box as well.
> >
> > So if you want to properly handle this mess, you'll also have to fix
> > conntrack.
>
> Better to fix the box which is randomizing the acks and ignoring
> the SACKs. Usually these are older Cisco PIX/ASA devices which just
> need a code upgrade.
I agree, the problem are these horrid middleboxes...
Unfortunately, they will hardly go away in the near futur. Rather the
opposite is the case.
If you have a public server running, I would be interested in the count of
invalid SACK-blocks received (netstat -s | grep TCPSACKDiscard). This is an
indication for such kind of middlebox between your server and the client,
implying that these connections cannot benefit from TCP-FastRetransmission
and each packet-loss will require an RTO to recover.
Cheers,
Christoph
next prev parent reply other threads:[~2013-08-19 15:33 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-18 5:55 NAT stops forwarding ACKs after PMTU discovery Corey Hickey
2013-08-18 15:24 ` Eric Dumazet
2013-08-18 16:59 ` Corey Hickey
2013-08-18 21:23 ` Jozsef Kadlecsik
2013-08-19 0:00 ` Eric Dumazet
2013-08-19 0:03 ` Eric Dumazet
2013-08-19 8:43 ` Corey Hickey
2013-08-19 12:33 ` Christoph Paasch
2013-08-19 13:24 ` Eric Dumazet
2013-08-19 13:49 ` Christoph Paasch
2013-08-19 13:58 ` Eric Dumazet
2013-08-19 14:35 ` Phil Oester
2013-08-19 15:32 ` Eric Dumazet
2013-08-19 15:33 ` Christoph Paasch [this message]
2013-08-19 16:00 ` Eric Dumazet
2013-08-19 17:15 ` Christoph Paasch
2013-08-19 18:00 ` Phil Oester
2013-08-19 18:10 ` Eric Dumazet
2013-08-19 19:29 ` [RFC 0/2] Account for duplicate ACKs with invalid SACK-blocks Christoph Paasch
2013-08-19 19:29 ` [RFC 1/2] Use acked_out for reno-style ack acounting instead of sacked_out Christoph Paasch
2013-08-19 19:29 ` [RFC 2/2] Account acked_out in sack, if the sack is invalid Christoph Paasch
2013-08-19 21:22 ` [RFC 0/2] Account for duplicate ACKs with invalid SACK-blocks Corey Hickey
2013-08-20 7:36 ` Christoph Paasch
2013-08-22 3:32 ` David Miller
2013-08-22 4:15 ` Corey Hickey
2013-08-19 14:43 ` NAT stops forwarding ACKs after PMTU discovery Christoph Paasch
2013-08-19 20:13 ` Jozsef Kadlecsik
2013-08-19 20:43 ` Christoph Paasch
2013-08-19 21:08 ` Eric Dumazet
2013-08-19 22:07 ` Jozsef Kadlecsik
2013-08-20 4:18 ` Corey Hickey
2013-08-19 18:22 ` Corey Hickey
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