Re: SOLVED: Network slow with "new" kernel
On Fri, 25 Nov 2011 08:59:40 +0100
+debianuser+thegrue+733a2fc4c3.debianuser.thegrue#spamgourmet.com@spamgourmet.com
wrote:
> Hello,
>
> > We have a few linux machines behind a firewall. When we start a
> > download on the "newer" machines (kernel 2.6.32-5), the download
> > starts fast (~3M/s), then quickly gets slower after about 10 or 20
> > seconds and soon stalls completely or proceeds at ~3 Byte/s or
> > something like that.
>
> Now that I know the name of the firewall (it's a Sonicwall NSA3500),
> I found a very interesting thread:
>
>
> http://shadowknight.real-time.com/pipermail/tclug-list/2009-October/056617.html
>
The name of the firewall did really help. The solution is to either get
a firewall that can handle RFC1323 or to disable window scaling on the
clients:
sysctl -w net.ipv4.tcp_window_scaling=0
I got the solution from these articles:
http://serverfault.com/questions/117319/linux-servers-seeing-bad-download-performance-behind-sonicwall-firewall
http://prowiki.isc.upenn.edu/wiki/TCP_tuning_for_broken_firewalls
Thanks for your help,
--
Markus Grunwald
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