Re: Why should static MAC address match one of the port MAC addresses.
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).
So, Michiel's claim still seems to be true: the bridge mac address should apparently be one of the bridge interfaces.
I don't see the logic, this seems like a bug to me.
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 ? 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. >  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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