[Lxc-users] Bug discussion: implementing high virtual device MAC addresses

Brian K. White brian at aljex.com
Wed Oct 19 17:33:53 UTC 2011

On 10/18/2011 7:31 PM, Derek Simkowiak wrote:

>       That MAC address has nothing to do with the bug; the host's bridge
> device (br0) will never assume a configured LXC MAC address as its own.
> Instead, the MAC address in question is the one of the virtual vethXXXX
> device, as shown with "ifconfig" on the host:
> veth0IEDlk Link encap:Ethernet  HWaddr 4e:34:7c:dc:92:e8
> [...snip...]
>       That HWaddr should be given a high prefix to avoid the network
> blackouts, just like they've done for libvirt.  That does not exist in
> any config file anywhere; it must be fixed in the LXC source code.
>       I looked in network.c for the LXC source code and I think the fix
> should go in lxc_bridge_attach() near line 991.  The fix would put a
> manually-generated MAC address -- one with a high prefix -- into
> ifr.ifr_hwaddr.sa_data and thus replace the random one assigned by the
> kernel.

Nice find!
(Sorry, no functional help from me, I'm just really glad to hear about 
zeroing in on the real problem.)


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