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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