[Users] Re: network problems: eth0: received packet with

[frank]

Thanks a lot for you explanation Benoit
I hope OpenVZ developers will take this in account.

Regards.

Frank

Al 21/05/10 18:00, En/na users-request at openvz.org ha escrit:
> Date: Fri, 21 May 2010 17:56:52 +0200 From: Benoit Branciard 
> <Benoit.Branciard at univ-paris1.fr> Subject: Re: [Users] Re: network 
> problems: eth0: received packet with own SOLVED and POSSIBLE BUG 
> *WARNING*) To: users at openvz.org Message-ID: 
> <4BF6AD44.8030907 at univ-paris1.fr> Content-Type: text/plain; 
> charset=ISO-8859-1; format=flowed frank a écrit :
>> >  Hi,
>> >  after a lot of tests I looked at a Xen machine, which also use ethernet
>> >  bridges and veths, and I noticed that it always use MAC
>> >  address FE:FF:FF:FF:FF:FF for the veths. I have test it on VE's
>> >  and...voila! No more mess with the MACs! Now the MAC of the ethernet
>> >  bridge is always the same, the host main ethernet interface one.
>> >  
>> >  I don't know the exact reason for this, but I'm sure it is an important
>> >  BUG for all who use veths with ethernet bridge.
>> >  Please, solve it as soon as you can.
>> >  Thanks.
>> >  
>>      
> This is a feature (I don't remember where I read it, but it's documented
> somewhere): under Linux, a bridge's MAC address takes the numerically
> *lowest*  value amongst those of the bridged interfaces which belong to it.
>
> FE:FF:FF:FF:FF:FF is the higher possible locally-defined unicast MAC
> address value and therefore is the least prone to interfere with the
> bridge's MAC (unless there are no other MAC addresses into the bridge).
>
> So the bridge-side of veths (not the VE-side, which will be visible on
> the network and should remain unique) SHOULD ALWAYS be FE:FF:FF:FF:FF:FF
> for convenience, or at least be chosen higher than any other MACs
> present on the system (FE:xx:xx:xx:xx range is a good choice).
>
> To my knowledge, mention about this is extremely sparse in OpenVZ's
> documentation, and*not*  taken into account by vzctl when automatically
> generating MAC addresses with "vzctl --netif-add" with blank MAC
> parameters. This may be considered as a bug.
>
>
> -- Benoit BRANCIARD Pôle Infrastructures Centre de ressources 
> informatiques et du réseau (CRIR) Université Paris 1 Panthéon-Sorbonne 
> http://crir.univ-paris1.fr Tel. 01 44 07 89 68


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