[pfSense Support] Strange TCP connection behavior 2.0 RC2 (+3)

Rhys Rhaven rhys at rhavenindustrys.com
Tue Jun 28 14:30:06 UTC 2011

Obviously not helping if you are trying to tune standard TCP, but I
lament that protocols like Tsunami are not in wider use.
http://tsunami-udp.sourceforge.net/ Short of it, a TCP control channel
takes care of error checking and resends while the data channel is a UDP
stream, specifically built to max out LFNs.

On 06/28/2011 03:52 AM, Eugen Leitl wrote:
> ----- 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 (+3)
> 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 very
> 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 190mbps,
> taking nearly 2 minutes to climb to this speed before *plateauing*.
> We have to initiate many (5+) connections to saturate the link with tcp
> connections with iperf.
> Real world tests transferring files, max out at 100mbps, using multiple
> 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 relevant
> 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 -----

More information about the NANOG mailing list