[PLUG] Network failure

linux-yug linux-yug at xprt.net
Sat Nov 14 20:30:38 UTC 2009


On Sat, 2009-11-14 at 11:13 -0800, Denis Heidtmann wrote:
> Trying to understand what happened to my network on Sep 21, 2009, and
> actions to take if it happens again.
> 
> Background: Running Ubuntu 9.04 with NetworkManager
> (http://projects.gnome.org/NetworkManager/)
> DSL modem.  No wireless.
> 
> On 9/21/09 all network communication failed.  I power cycled the modem
> to no effect.  My son changed /etc/network/interfaces from:
> auto lo
> 
> iface lo inet loopback
> 
> 
> to:
> auto lo
> 
> iface lo inet loopback
> 
> 
> 
> auto eth0
> 
> iface eth0 inet dhcp
> 
> 
> After restarting the network was restored, but the NetworkManager
> applet which displays the network status on the task bar shows the
> network as not functional.
> 
> Since this occurrence I have had two more times that the network
> failed.  In both cases after shutting down for an hour or so then
> restarting the network came back up functional.  During one of these
> most recent failures, I looked at a GUI which displays, among other
> things, Netstat outputs.
> 
>  When it had failed:
> 
> 
> 
>   Destination Gateway        Netmask      Interface
> 
>   169.254.0.0 0.0.0.0           255.255.0.0 eth0
> 
>   0.0.0.0             0.0.0.0        0.0.0.0         eth0
> 
>   fe80::                  ::                64        eth0
> 
>   ...snip...
> 
> When it was functional:
> 
> 
> 
>   Destination Gateway  Netmask         Interface
> 
>   192.168.0.0 0.0.0.0          255.255.255.0   eth0
> 
>   169.254.0.0 0.0.0.0          255.255.0.0     eth0
> 
>   0.0.0.0           192.168.0.1   0.0.0.0         eth0
> 
>   fe80::                   ::                64            eth0
> 
>   ...snip...
> 
> 
> The spontaneous fixes since the first occurrence leads me to consider
> the possibility that Evan's edit of /etc/network/interfaces did not
> fix the issue, but only served to break the NetworkManager applet.
> 
> I am interested in having a bag of diagnostic tricks at the ready when
> it happens again.  High on my list of suspects is the DSL modem.  I am
> also interested in restoring the NetworkManager applet to function.
> 
> Suggestions?
> 
> -Denis



  169.254.xx.xx  is NOt a good  IP address..

HTH

Linux-yug




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