[63232] in North American Network Operators' Group
Re: Adjusting TCP windows on production systems?
daemon@ATHENA.MIT.EDU (Petri Helenius)
Wed Oct 1 03:26:11 2003
Date: Wed, 01 Oct 2003 10:24:39 +0300
From: Petri Helenius <pete@he.iki.fi>
To: Steve Francis <steve@expertcity.com>
Cc: "Temkin, David" <temkin@sig.com>, nanog@merit.edu
In-Reply-To: <3F7A0410.5010803@expertcity.com>
Errors-To: owner-nanog-outgoing@merit.edu
Steve Francis wrote:
>
> 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.
>
Unless you have something like FreeBSDīs auto-tuning inflight window
stuff which
would allow large windows to be allocated only when the delay*bandwidth
product
justifies it.
Pete
> 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
>
>
>
