Configuring bridges to use with KVM

[Serge E. Hallyn]

Quoting carlopmart (carlopmart at gmail.com):
> Hi all,
> 
>   I have a problem with an ubuntu lucid 10.04 server used for KVM virtualization. My 
> problem appears when I try to configure an "empty" bridge in /etc/network/interfaces 
> file. For example, with a RedHat based distro (RHEL, CentOS) I can create a config 
> file ifcfg-br20 like this:
> 
> DEVICE=br20
> TYPE=Bridge
> ONBOOT=yes
> DELAY=0
> STP=off
> NM_CONTROLLED=no
> 
>   and then network startup script creates an empty bridge without bind any physical 
> interface. I have tried same procedure to configure several empty bridges under 
> ubuntu without luck:
> 
> auto intprodif
> iface intprodif inet static
> 	bridge_stp off
> 	bridge_fd 9
> 	bridge_hello 2
> 	bridge_maxage 12
> 
>   When i try to start this bridge with "ifup intprodif" command returns me this error:
> 
> carlos at silmaril:~$ sudo ifup intprodif
> Don't seem to be have all the variables for intprodif/inet.
> Failed to bring up intprodif.
> 
>   How can I define an empty bridge without binding any physical interface into it??
> 
>   Many thanks.

man 5 interfaces says that for 'inet static', the following are required:
	address
	netmask

Add those and see if it still complains?

-serge