Followup - Re: [CentOS] Ethernet poor performance

Robert Moskowitz rgm at
Wed Jul 2 20:04:48 UTC 2008

NiftyClusters Mitch wrote:
> Good list:
> Also add multiple runs of "traceroute" and also try ping,  ping -f ,
> ping -A and ping -R.  See also ping6
> If routes are dynamic we have one answer to the problem, I would
> expect traceroute to have 'one' answer on a simple net.
> If packets are falling on the floor then we need to know why.
> The different invocations of ping can tell you if packets drop at slow
> or fast transfer rates.
> ping -R is slightly different than traceroute but if the return routes
> flip one way then the
> other we should know why.
> Watch out for /etc/sysconfig/network-scripts/ifcfg* where hardware addresses,
> subnet masks, device driver links/ names etc. no longer match the hardware
> when things move.
More, watch out for /etc/sysconfig/networking/devices where configs that 
you thought you deleted live on to get you when your run 
system-config-network. I just could not figure out, for a while, why 
when I deleted /etc/sysconfig/network-scripts/ifcfg-eth1.bak it would be 
right back there!
> Consider snooping packets on the link to see if all is as you expect.  I keep an
> old, slow  network hub (not a switching hub) for the times when I want
> to see the bits on the wire and
> not the bits that the local driver is able to show me.
I have one as well. It is so hard to find them anymore....

More information about the CentOS mailing list