Transport protocols and bulk file transfer

[Jeff W.Boote <>]

So, one thing I think we should also take from here... Phoebus makes  
the end-host tuning less important (by design).

jeff

On May 15, 2009, at 11:42 AM, Larry Dunn wrote:

> Steve S., others,
> Per the discussion on our phone call today,
> here's a quick pointer if you want to check/adjust
> socket buffers on OS X:
>
> http://www.psc.edu/networking/projects/tcptune/#MacOS
>
> (I'm running 10.5.6 on my laptop; the defaults are 65k;
> many folks set that to 256k or 1MB (or more) for experiments
> like these).
>
> Of course,
> sysctl -a | grep space
> will display the tcp buffers...
>
> Remember that even if you make changes permanent across reboots
> by editing /etc/sysctl.conf,
> the next OS X update might reset /etc/sysctl.conf and un-do your  
> changes. ;-)
>
> Also sometimes nice to bounce things off of Rich Carlson's ndt server
> by opening any browser to ndt.anl.gov,
> doing the speed-test there (takes ~1minute usually);
> opening the "More Details" tab after completion will show what the
> other side sees as your advertised buffers, etc.
>
> Note that sometimes buffers are reported as 2x above what you set.
> For example, I set my buffers to 250KBytes,
> and ndt reported "511kbyte buffer"...
> Still, it'll confirm the difference between 65k and 1MByte. ;-)_
>
> Larry
> --