Help debugging network problem

scott redhowlingwolves at nc.rr.com
Sat Nov 8 07:56:26 UTC 2008


Michael Peek wrote:
> Hi gurus,
>
> I have a machine running 2.6.24-19-server from the amd64 version of
> 8.04LTS, and I have a strange networking problem. Periodically (every
> few minutes) the network connection will stop working. The strange
> thing is that 50% of the time, any active SSH connections to the machine
> continue to work, I can ping the machine from the outside, but new
> connections don't happen.
>
> As an example:
>
> In one window I ran tcpdump, while in the other window I attempted to
> use apt-get to install a package. Apt said it was attempting to contact
> http://us.archive.ubuntu.com, but no packets showed up in tcpdump.
> Eventually
> apt quit with "Could not resolve 'us.archive.ubuntu.com'", and when I
> quit tcpdump it said: "664 packets dropped by kernel"
>
> The network will work for a few minutes, then seize up for a few
> minutes, then magically start working again -- for a few minutes.
> During the network blackout, I can bring things back by ifdown/ifup the
> interface. Then things will work again -- for a few minutes.
>
> The ethernet is built in to a SuperMicro X7DWE, and is an Intel
> 82563EB. I tried both the e1000 driver that came with the stock kernel,
> and compiled the newer version that came on the motherboard driver CD.
>
> Anybody have any idea why the kernel would drop packets? Is this a
> driver issue, a hardware failure, or something completely different?
>
>
> Thanks for your help!
>
> Michael
>
Possibly your router is too close to a cordless phone, microwave or
any other appliance that uses nearly the same radio band.

Are you using any encryption (WEP, WPA)for your connection? Have you
tried manually changing channels on your router to not interfere with
another router close by,... eg: your neighbor?

Just a few thoughts off the top of my head.





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