[111860] in North American Network Operators' Group
Re: Linux Router: TCP slow, UDP fast
daemon@ATHENA.MIT.EDU (Lee)
Sat Feb 14 09:57:28 2009
In-Reply-To: <c8a7026b0902140548y6ec3cfb9w1ba8b9efb6b70ee7@mail.gmail.com>
Date: Sat, 14 Feb 2009 09:57:13 -0500
From: Lee <ler762@gmail.com>
To: Chris <chris@ghostbusters.co.uk>
Cc: nanog list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On 2/14/09, Chris <chris@ghostbusters.co.uk> wrote:
> Thanks loads for the quick replies. I'll try and respond individually.
> Lee > I recently disabled tcp_window_scaling and it didn't solve the
> problem. I don't know enough about it. Should I enable it again ? Settings
> differing from defaults are copied in my first post.
I don't know if the tcp window size makes any difference when the box
is acting as a router. But when UDP works as expected & each
additional TCP connection gets 300-600kbps the first thing I'd look at
is the window size. If it was a duplex mismatch additional TCP
connections would make things worse instead of each getting 3-600Kb
bandwidth.
> The only other change to the box is that over Christmas IPtables
> (ip_conntrack and its associated modules mainly) was loaded into the kernel
If all else fails, backing out recent changes usually works :)
Regards,
Lee
