[TriLUG] Tuning WAN links

[Jeremy Portzer]

Shawn Hood wrote:
> 
> 
> I've run iperf between two RHEL4 boxes connected to the 3560s.  The most
> throughput I've been able to get is ~45mbit by increasing the buffer sizes
> in /etc/sysctl and using massive window sizes on iperf.  I was hoping you
> guys could point me in the right direction.  I need to do some reading about
> how to get the most out of this link, and any reference would be greatly
> appreciated.  Will this be a matter of create a Linux router on each end to
> shape the traffic destined for this link?  Is this something better suited
> for proprietary technology that claims to 'auto-tune' this kinds of links.
> I'm fairly fluent when it comes to talking about this stuff 'in theory,' but
> have yet to get any hands on experience.
> 

I don't know too much about iperf*, but my general "scientific method" 
approach troubleshooting makes me wonder if you have a "control" in your 
experiment.  What is the maximum throughput you can get between two Red 
Hat boxes with the same type of interface (I assume single GigE card?), 
just directly connected?  What about the capabilities of the switches or 
other network equipment between the RH boxes and the routers?

Just wanted to make sure you're pointing your finger at the right culprit.

--Jeremy

*meaning, I've never heard of it before reading your post!