[63225] in North American Network Operators' Group
Re: Adjusting TCP windows on production systems?
daemon@ATHENA.MIT.EDU (Steve Francis)
Tue Sep 30 18:32:25 2003
Date: Tue, 30 Sep 2003 15:30:40 -0700
From: Steve Francis <steve@expertcity.com>
To: "Temkin, David" <temkin@sig.com>
Cc: nanog@merit.edu
In-Reply-To: <web-1781273@multicasttech.com>
Errors-To: owner-nanog-outgoing@merit.edu
Just as a head up - this sort of below should not be done on things like
web servers that support lots of concurrent connections - you'll eat all
your memory for sockets.
Marshall Eubanks wrote:
>On Tue, 30 Sep 2003 15:44:03 -0400
> "Temkin, David" <temkin@sig.com> wrote:
>
>
>>Is there anyone in a production environment who, as part of their system
>>build process, adjusts the TCP receive window/MSS/etc. on production
>>systems?
>>
>>
>>
As a concrete data point:
the tuning below on Solaris 9 increased the TCP data transfer rates from
SJC to NYC by a factor of 10:
(i.e. from 2 to about 20Mbps with ftp; 1 to 11Mbps with scp.)
ndd -set /dev/tcp tcp_recv_hiwat 400000
ndd -set /dev/tcp tcp_xmit_hiwat 400000
ndd -set /dev/tcp tcp_wscale_always 1
ndd -set /dev/tcp tcp_max_buf 10485760
