Hi All,
Despite of what Stephen explains, I'm having the problem Michiel
describes as well. I have a bridge br2 containing 1 (but potentially
more) tap interface for kvm. Windows 7 VM doesn't like the bridge
mac address to change, so I try to make it fixed.
ifconfig br2 hw ether 02:00:00:00:01:02
Interface br2 becomes instantly unreachable from the VM (via the tap
interface). No arp response or anything else.
So, Michiel's claim seems to be true: the bridge mac address should
apparently be one of the bridge interfaces. But I don't see the
logic, this seems like a bug to me.
kernel is Fedora kernel-2.6.35.9-64.fc14.x86_64.
Cheers,
Rolf
On Tue, 12 Oct 2010 15:40:25 +0200 Michel Lammertink <mlammertink@xxxxxxxxx> wrote:
> Hi all,
>
> I've read many messages on this mailing list with the question about
> setting a static MAC address on the bridge interface, but two questions
> remain:
>
> 1. Why should the MAC address of the bridge match the address of one of
> its interfaces? Setting the MAC address to a different value does not
> generate an error, but the bridge is not working properly (Local data
> does not arrive).
No longer a requirement. It was just a good way to ensure a good
address that was unique, and not being used by other systems.
> 2. Why does the bridge by default choose the "lowest" MAC address,
> instead of the MAC address of the first port added, as is proposed by
> the standard [1]?
It was a convenience in original design to choose a consistent value.
Since ports can be added in any order, using the lowest seemed like
a good idea for the original author. This has been maintained for
backwards compatibility.
> [1] IEEE802.1D, Par. 7.12.5.
> Quote: "The Bridge Address may be the individual MAC Address of a
> Bridge Port, in which case, use of the address of the lowest numbered
> Bridge Port (Port 1) is recommended."
>
> Thanks in advance,
>
> Michel.
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