[CentOS] KVM Client NetworkManager Problem

Sun Dec 16 13:27:33 UTC 2018
Günther J. Niederwimmer <gjn at gjn.priv.at>

hello Greg,

thanks for the answer, now I am not so alone ;-)

this Problem with the third NIC in a KVM Client is from Update to Update 
stronger. I mean on start the Installation "CentOS 7.0" we don't have this 

without NetworkManager is run, on my system, I can't start the third Network-
Card, I have always a LSB Error on the KVM-Clients ??

So now I found a workaround for my Problem :-(. (What are changed in the 
Network Configuration)

I set up the first and second NIC to "hostdev" (hardware) this is running also 
before the update and set “NM_CONTROLLED=no” to this NIC's.

The third is a Bridge controlled Interface now is running with NetworkManager 
as a static Interface with "PEERDNS=no" so I have my resolv.conf is not always 
change and NetworkManager don't create a new Interface with a DHCP config ??

Why Network Manager do that with 7.6, I can't say but I am not happy witzh 
this update :-(. 

Am Samstag, 15. Dezember 2018, 18:27:39 CET schrieb Gregory P. Ennis:
> I have two units that are different users with desktop KVM hypervisors
> Centos 7 hosts.  One had only one network card and it went through the
> migration from 7.5 to 7.6 without a problem.  The other had three network
> cards and it became disabled with failed network connections. I had to
> rebuild the network and did so in the following manner.
> #1. NetworkManager had been turned off.  I turned NetworkManger from off to
> on so that it would create appropriate ifcfg-* files for three network
> cards after a reboot.
> #2.  I modified the appropriate ifcf-* files and created a new network
> bridge with one of the cards.  After the update to 7.6 I was able to leave
> NetworkManager running as long as I had the appropriate ifcf-* file and the
> bridge set with “NM_CONTROLLED=no”.  With Centos 7.5 I had to disable
> NetworkManager because it kept destroying the bridge even with the switch
> #3.  Lastly I had to change the references to the new bridge in the KVM
> guests.
> After this everything has worked like it did before the upgrade.  My take on
> this is that kvm hypervisors that are set up with more than one nic card
> have the potential of having their network setup corrupted when the
> migration from 7.5 to 7.6 occurs.  On a positive note NetworkManager now
> works with a network bridge with 7.6, but it did not work for me with 7.5.
> Good Luck!!!
> Greg

mit freundliche Grüßen / best regards,

  Günther J. Niederwimmer