How to test NIC performance?

[Andy Pieters]

Hi

What exactly do you mean with high latency?  Do you mean that it takes a long 
time to connect (anywhere)?

There are a few precautions to follow with gigabit ethernet.

1. Only use CAT-5 cables.
2. To obtain highest possible speed on the LAN, use a Gigabit 
switch/hub/router
3. Make sure speed autonegociation is turned on.

giving the blame to your nic is easy but 8 times out of ten it's not the 
culprit.

Other devices on your network may be transmitting (broadcasting) a lot of 
giberish.

Use network scan tools to find out what is happening, also check your messages 
log.  

Do a service network restart and then tail /var/log/messages -n 20 and see at 
what speed it came on

Another thing you might want to check is how fast your dns server is 
responding.  It is not unusual for "shady" providers to have quite a bit of 
lag on their dns servers. try pinging the ip address of one of the dns 
servers; look in /etc/resolv.conf for the addresses

Tools like netstat and ethereal are your friend as well.

HTH

Andy

On Saturday 29 October 2005 06:06, Dan Hensley wrote:
> Since my first post about this got no replies, I'll rephrase.
>
> I am experiencing extremely high latency with my network interface.  AMD
> X2 64, Gigabyte K8N Pro-SLI, using the built-in gigabit NIC which I
> believe is using the forcedeth driver.
>
> Transfer speeds are fine, but latency is ridiculous.  Does the forcedeth
> driver have known issues like this?  Do I need to invest in different
> hardware?
>
> I'm not sure how to test the performance of my NIC to try to
> troubleshoot why this is so bad.  Can someone point me in the right
> direction?
>
> Thanks,
> Dan

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