[Lxc-users] lxcbr0 MAC addr issue

Michael H. Warfield mhw at WittsEnd.com
Wed Jun 5 15:32:30 UTC 2013


Crap...  Bumped the keyboard and this one got away from me prematurely.

On Wed, 2013-06-05 at 11:23 -0400, Michael H. Warfield wrote: 
> On Wed, 2013-06-05 at 15:17 +0000, Jäkel, Guido wrote: 
> > >yes and it does this.  The point is that lxcbr0 is not tied to any
> > >physical nic.  So the first container you start, however high the
> > >macaddr is, lxcbr0 takes its mac.  If the next container gets a
> > >lower macaddr, lxcbr0's macaddr drops.

> > This lxcbr0 is special to Ubuntu, right? And if not to a physical
> NIC, to what is this bridge connected to on the host?

> Not to the best of my knowledge.  It should be a simple bridge.

> What do you get for this command?

> brctl show

> A bridge doesn 

A bridge doesn't have to be attach to a device.  A bridge is its own
logical entity in the kernel to which you may attach devices.  You can
not "attach a bridge" to something else.  You can only attach something
else "to the bridge".  There's a difference.

In the case of a NATing configuration, you set up a bridge (name it
whatever you want) and attach the containers to it.  Then you use the
NAT modules to route between the bridge and the external interface while
NATing the addresses.  I use "lxcbr0" on my Fedora hosts.  It's just a
bridge.

I could see where Ubuntu might have some preconfigured setups for this
purpose where I have to set them up by hand in Fedora.  That's just a
matter of the distro specific support scripts.

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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