CentOS - Jun 2012 - Centos 6 - Networking: Some Queries -- GURUS HELP PL

With NM_Controlled=No in the ifcfg file, NM applet shows "Not
Managed", so
the ifcfg file is being read. What is the extent of interaction of
NetworkManager with ifcfg files is unknown....very little information on
the net. Seems Network Manager is still mostly unplublished compared to
other utilities. Any pointers to literature on this or macro architecture
of NM would be appreciated, as Google is not throwing up the right results.

On a separate note however, I'd still like to know how to use a bridge to
route packets between two networks.....say network card having
address...192.168.1.3 and a kvm based virtual network say
172.31.1.0/24needing to use this device for Internet access (through
router 192.168.1.1)
using a bridge? How to do it?

With regards.
Sanjay.

On 06/01/2012 02:38 AM, Sanjay Arora wrote:
> With NM_Controlled=No in the ifcfg file, NM applet shows "Not
Managed", so
> the ifcfg file is being read. What is the extent of interaction of
> NetworkManager with ifcfg files is unknown....very little information on
> the net. Seems Network Manager is still mostly unplublished compared to
> other utilities. Any pointers to literature on this or macro architecture
> of NM would be appreciated, as Google is not throwing up the right results.
You're right.  Documentation is sparse.
https://live.gnome.org/NetworkManager/SystemSettings
$ man NetworkManager
$ man NetworkManager.conf
less /usr/share/doc/initscripts-*/sysconfig.txt
> On a separate note however, I'd still like to know how to use a bridge
to
> route packets between two networks.....say network card having
> address...192.168.1.3 and a kvm based virtual network say
> 172.31.1.0/24needing to use this device for Internet access (through
> router 192.168.1.1)
> using a bridge? How to do it?
If your networks are on different IPv4 broadcast domains (as you 
describe), you don't want a bridge.

If you want bridged networking with KVM, your guests will be on the same 
network as the host.  They'll use your existing DHCP services and 
routing.  They can be configured according to this document:
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6-Beta/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/sect-Virtualization_Host_Configuration_and_Guest_Installation_Guide-Network_Configuration-Network_Configuration-Bridged_networking_with_libvirt.html

That configuration used to be reflected here:
http://wiki.centos.org/HowTos/KVM
...but someone went and put in some really braindamaged instructions. 
That should be fixed or removed.