[libvirt-users] Some missunderstanding in the wiki page

[Tom Hughes]

On 30/06/10 10:35, Leopold Palomo-Avellaneda wrote:

> The configuration (I have follow only the debian/ubuntu steps) shows that br0
> has assigned an IP. I did the mistake to try to assign the same IP in the
> guest network configuration, I understand that, and obviously it doesn't work
> (duplicate IPs). So, to me, it would me more clear if the br0 interface has
> no IP. In my case, I have two nics: eth0 the interface for the host and eth1
> for the guest. The eth1 part in my network/interfaces is:
>
> ...
> auto eth1
> iface eth1 inet manual
>
> auto br0
> iface br0 inet manual
>          bridge_ports  eth1
>          bridge_stp    on
>          bridge_maxwait  0
>          bridge_fd       0
> ...
>
> and then in the guest you configure the IP as you want. In the host, eth1 (or
> whatever interface you bridge) has no IP, so it's not used, and the guest
> uses completely.

The common configuration that the wiki is documenting is presumably the 
case where the host has a single ethernet interface that is shared by 
the host and the guests. In that configuration the bridge does have an 
address, which is the address of the host machine.

Basically a bridge is like a virtual ethernet switch inside your 
machine, where one port is connected to each device that is enslaved to 
it and another port is connected to the kernel's IP stack - that port 
appears as the brN interface and can have an IP address (for the host) 
assigned to it.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://compton.nu/