[CentOS-virt] xenbr0 vs. virtbr0

Thu Mar 20 15:54:30 UTC 2008
Ross S. W. Walker <rwalker at medallion.com>

Kai Schaetzl wrote:
> Just created the first completely new Xen VM with the Virtual Machine 
> Manager after 5.0 became 5.1 and I notice these two differences:
> - there's now virbr0 instead of xenbr0. Which means I have now xenbr0 and 
> vitbr0 interfaces running. As virbr0 just the new name for xenbr0? If so, 
> can I just change that name in the older configuration files, so that all 
> use the same interface name?

I was confused initially by this too, but it turns out that virbr0 is the
libvirt managed interface (dnsmasq and non-xen qemu) and libvirt managed
clients use it by default. It should be pre-set with subnet

I believe it is set to NAT with peth0.

xenbr0 is the Xen managed bridge and it comes with no default IP and it's
characteristics are managed purely through the xend configuration.

> - there is a (I think) new option for networking. There's virtual network 
> and there's shared device. What's the latter? I don't remember this being 
> available earlier. It doesn't list any devices for me. Does this refer to 
> virtual devices of type eth0:5 etc. on the host?

I believe the virtual network is the standard xen network interface config
and the shared network is the virbr0 thing, but don't quote me on that,
as you said documentation isn't plentiful here.

> help is no help for this, it's empty for this section.

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