[olug] Full Duplex - NIC

[Will Langford]

On Wed, Feb 3, 2010 at 11:56 PM, Luke-Jr <luke at dashjr.org> wrote:

> On Wednesday 03 February 2010 08:24:09 pm Kelly Williams wrote:
> > I checked my Nic on my server and it run full duplex. I noticed that I
> > was running two machines with XDMCP disable it on both machines and
> > still not getting any faster. I took off a switch on my network still
> > not any faster. Any thoughts.
>
> One thing to consider is that if you're using TCP, there are ACK packets
> going
> the other way. Usually it shouldn't make a big difference, but if you're
> sending lots of small packets, it could...
>
>
Lots of tiny packets would be inherently slower, yup.

Lowering your MTU to 1490 or similar can help some, especially if you're
VLAN'ing.  As Luke suggested, google is your friendly.

Conversely, if all of your network can handle it (or segmented bits can),
jumbo frames (huge MTU over 1500) can also possibly benefit you a lot.

Out of curiosity, what about your network is slower ? Certain things are
'inherently' slower.  SFTP stuff is typically 2-3MB/sec, Windows file
sharing will also automatically chop your transfer speed in half over
whatever medium you're using (ie: on a 115200 serial connection, you'll only
get 5k/sec versus expected 11k/sec... or 512K/sec over 10baseT, etc).

The iPerf/jPerf/etc tools mentioned by Rob is also a great idea.  Wire
sniffers might be a last ditch effort to see what's going on, too.

The only hardware related thing that comes to mind is that cheap NIC's can
be flakey, but even worse is cheap hub/switches.  For example: an Encore
branded switch is begging for performance and stability issues (we've noted
it in the field).  Even some Netgear switches have issues...

-Will