[pfSense Support] Strange TCP connection behavior 2.0 RC2 (+3)
leigh.porter at ukbroadband.com
Tue Jun 28 10:29:56 UTC 2011
Indeed, we had similar issues on a 3G radio network. Long RTTs made it impossible to reach the maximum potential throughput of the network. I installed one of these:
And the problem just went away.
> -----Original Message-----
> From: Jérôme Nicolle [mailto:jerome at ceriz.fr]
> Sent: 28 June 2011 11:26
> To: Eugen Leitl
> Cc: NANOG list
> Subject: Re: [pfSense Support] Strange TCP connection behavior 2.0 RC2
> This is a well known issues called "Long Fat Pipe Network".
> There's many university papers about it and many tricks to get around
> it on software-based boxes.
> Adjusting your TCP window size was the best start, if it's set
> properlu. The basic formula is provided in this forum post :
> Good luck !
> 2011/6/28 Eugen Leitl <eugen at leitl.org>:
> > ----- Forwarded message from William Salt
> <williamejsalt at googlemail.com> -----
> > From: William Salt <williamejsalt at googlemail.com>
> > Date: Tue, 28 Jun 2011 08:03:25 +0100
> > To: support at pfsense.com
> > Subject: [pfSense Support] Strange TCP connection behavior 2.0 RC2
> > Reply-To: support at pfsense.com
> > Hi All,
> > For the last couple of months i have been pulling my hair out
> > trying to solve this problem.
> > We have a 1Gbps transatlantic link from the UK to the US, which has
> > successfully passed the RFC2544 test.
> > At either end, we have a media converter, and a supermicro server
> with an
> > intel quad port NIC running pfsense 2 (RC2 at one end RC3 at the
> other) and
> > the IGB driver on the quad port.
> > We can pass 1gbps either way with UDP. However we are experiencing
> > strange issues with tcp connections.
> > With window scaling enabled, and a max socket buffer set to 16MB, we
> see no
> > difference.
> > Even disabling window scaling and setting the window to 16MB makes no
> > difference.
> > Each TCP connection starts very slowly, and will max out at around
> > taking nearly 2 minutes to climb to this speed before *plateauing*.
> > We have to initiate many (5+) connections to saturate the link with
> > connections with iperf.
> > Real world tests transferring files, max out at 100mbps, using
> > connections.
> > I have followed guides like this:
> > http://www.psc.edu/networking/projects/tcptune/#FreeBSD
> > With no luck, and have tweaked, disabled, and enabled nearly every
> > sysctl parameter with no luck.
> > Can anyone shed some light on this?
> > I am now doubting the IGB driver, and am looking to swap out the
> cards as a
> > last ditch effort.
> > However, we have tried different hardware (L3 switches, media
> convertes +
> > laptops etc), and the symptoms still persist...
> > The only constant is freebsd 8.1 - pfsense (or 8.2 for our production
> > systems).
> > I have tried the freebsd net mailinglist, but im hoping you lot can
> help me!
> > Cheers in advance
> > Will
> > ----- End forwarded message -----
> > --
> > Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
> > ______________________________________________________________
> > ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
> > 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE
> Jérôme Nicolle
> 06 19 31 27 14
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