On Mon, Dec 20, 2010 at 11:07 PM, Eric Dumazet <[email protected]> wrote:
> Le mardi 21 décembre 2010 à 13:53 +0800, Yueyu Lin a écrit :
>> Hello, everyone
>>       I just encountered a very strange issue in Ubuntu 10.10 server
>> edition X86 64bits.  I just start up my kvm like :
>> kvm -net nic,macaddr=B3:C0:64:AF:73:28,model=virtio -net
>> tap,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown,ifname=tap2
>> -enable-kvm -drive file=cassandra.raw,format=raw,aio=native -vnc :2
>>      This Mac address doesn't work at all. No working means the
>> virtual machine just thinks the eth0 is not plugged in. After I
>> changed the MAC address, it works as I expected.
>>       Are there any restrictions that I  can't use certain MAC
>> addresses?--
>
>
> Sure
>
> First byte must be even.
>
> B3 is odd, so its not valid.
>
> low order bit is a marker for 'multicast'

See here for reference: http://en.wikipedia.org/wiki/MAC_address

Typically also makes sense to set the locally administered bit to
avoid collisions with real devices too.

Alex
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