Re: [gentoo-user] Strange network behaviour: NIC goes down, DHCP lease renewal fails

[Mick]

On Thursday 05 Mar 2015 18:33:23 Todd Goodman wrote:
> * Marc Joliet <marcec@×××.de> [150305 04:47]:
> [..SNIP..]
>
> > 1.) The NIC is brought up (some built-in Intel model).
> >
> > 2.) A DHCP client configures it.
> >
> > 3.) The network connection is lost at some point (the amount of time this
> > takes
> >
> >     varies, but it can be as little as 20 minutes).
> >
> > 4.) Eventually the lease runs out and the DHCP client tries to renew it,
> > but
> >
> >     gets no response.  Sometimes, after many hours (at least 6), it will
> >     get a DHCPACK, but that's it.  One of our sysadmins says that not
> >     only does the DHCP server never see the packets, but the managed
> >     switch that the PC is directly attached to *also* never does (again,
> >     except for when the occasional DHCPACK comes).
> >
> > 4.) Restart the network device.  A reboot is not required, but it is
> > necessary
> >
> >     to terminate the DHCP client.  After that everything works again.
> >
> > 5.) GOTO 3.
>
> [..SNIP..]
>
> Is this a WiFi NIC?
>
> Is it possible the device is powering down?
>
> I've had lots of problems with WiFi devices powering down (both driver
> issues as well as just trying to disable the default setting of powering
> down.)
>
> Todd

If not a WiFi, have you also tried to mirror a port at the router where the 
DHCP server is running and sniff packets there?  Does the router see the 
DHCPREQ coming through from the client PCs?

-- 
Regards,
Mick