VLAN tagged traffic and different behavior on two CentOS 6.6 boxes

Hi list,
I have a bridged KVM setup where I would trunk both tagged and untagged traffic. In other words, some VMs will reside on the untagged portion, while other on the tagged one.

I have two CentOS 6.6 boxes that behave quite differently each other and I can not understand why. On both boxes I have:
- an eth0 interface bridged to lanbr0
- an eth0.10 interface bridged to lanbr10

From what I read here [1] and here [2], to have a working setup I need to create an ebtables rules similar to "ebtables -t broute -A BROUTING -p 802_1Q -i eth0 -j DROP". On the first system, until I create that rules I can not ping the lanbr10 interface (from another system).

But on the second system, after some 20-25 seconds (less if I disable STP on the bridge) I can ping the lanbr10 interface even _without_ the ebtables rules above.

How that is possibile? Why the second box seems to auto-configure it while the first one need the ebtables rule? I hope this is the right list...

Thanks.

[1] http://ebtables.netfilter.org/misc/brnf-faq.html
[2] http://www.rackspace.com/blog/vms-vlans-and-bridges-oh-my-part-2/

Additional informations:

FIRST BOX:
[root@singularity ~]# ifconfig eth0.10 0.0.0.0 [root@singularity ~]# brctl addbr lanbr10
[root@singularity ~]# brctl addif lanbr10 eth0.10 [root@singularity ~]# ifconfig lanbr10 10.0.0.100 netmask 255.255.255.0 [root@singularity ~]# brctl show
bridge name bridge id STP enabled interfaces
dmzbr0 8000.00a0d213ef5d yes eth1
vnet0 vnet4 vnet7
lanbr0 8000.002522027e10 yes eth0
vnet1 vnet2 vnet3 vnet5
lanbr10 8000.002522027e10 no eth0.10
virbr0 8000.5254005a0aac yes virbr0-nic

SECOND BOX:
[root@kvm-black ~]# brctl addbr lanbr10
[root@kvm-black ~]# brctl addif lanbr10 eth0.10 [root@kvm-black ~]# ifconfig lanbr10 10.0.0.85 netmask 255.255.255.0 [root@kvm-black ~]# brctl show
bridge name bridge id STP enabled interfaces
lanbr 8000.0022196645d4 yes eth0
lanbr10 8000.0022196645d4 no eth0.10

Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: [email protected] - [email protected]
GPG public key ID: FF5F32A8