Comment 12 for bug 919068

I'm starting to run out of idea here...
I just tried with the following configuration Ubuntu 12.04:
 - 6 network cards
 - 3 configured as you do in your /etc/network/interfaces
 - 3 not mentioned at all in /etc/network/interfaces
 - br0 with static IP and bridge-ports all

Can you try your configuration with Ubuntu 12.04 beta1 (or later, running updates) and ideally in a VM so we can ensure we have the exact same setup.

I had a very quick look at ebtables, at least in 12.04 it doesn't seem to contain a postinst, config or a debconf templates, so dpkg-reconfigure should be a no-op here, however it does contain an init script that could impact the system.

Result is:
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root@stgraber-vm:~# brctl show
bridge name bridge id STP enabled interfaces
br0 8000.52540017bb0d no eth0
       eth1
       eth2
       eth3
       eth4
       eth5
root@stgraber-vm:~# ifconfig
br0 Link encap:Ethernet HWaddr 52:54:00:17:bb:0d
          inet addr:172.23.0.50 Bcast:0.0.0.0 Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe17:bb0d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:21859 errors:0 dropped:0 overruns:0 frame:0
          TX packets:44 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1086706 (1.0 MB) TX bytes:8477 (8.4 KB)

eth0 Link encap:Ethernet HWaddr 52:54:00:e2:bf:bc
          UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
          RX packets:4618 errors:0 dropped:73795 overruns:0 frame:0
          TX packets:17293 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:269714 (269.7 KB) TX bytes:1099997 (1.0 MB)
          Interrupt:11

eth1 Link encap:Ethernet HWaddr 52:54:00:88:c5:53
          inet6 addr: fe80::5054:ff:fe88:c553/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
          RX packets:4579 errors:0 dropped:73787 overruns:0 frame:0
          TX packets:17356 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:259356 (259.3 KB) TX bytes:1120260 (1.1 MB)
          Interrupt:11 Base address:0x4000

eth2 Link encap:Ethernet HWaddr 52:54:00:58:86:ae
          UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
          RX packets:3445 errors:0 dropped:73727 overruns:0 frame:0
          TX packets:18471 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:196380 (196.3 KB) TX bytes:1184883 (1.1 MB)
          Interrupt:11 Base address:0x6000

eth3 Link encap:Ethernet HWaddr 52:54:00:7e:91:50
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:3093 errors:0 dropped:72262 overruns:0 frame:0
          TX packets:18835 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:178774 (178.7 KB) TX bytes:1207209 (1.2 MB)
          Interrupt:11 Base address:0x8000

eth4 Link encap:Ethernet HWaddr 52:54:00:19:a8:ad
          inet6 addr: fe80::5054:ff:fe19:a8ad/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:3075 errors:0 dropped:72255 overruns:0 frame:0
          TX packets:18898 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:175020 (175.0 KB) TX bytes:1222424 (1.2 MB)
          Interrupt:10 Base address:0xa000

eth5 Link encap:Ethernet HWaddr 52:54:00:17:bb:0d
          inet6 addr: fe80::5054:ff:fe17:bb0d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:3075 errors:0 dropped:72254 overruns:0 frame:0
          TX packets:18901 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:178154 (178.1 KB) TX bytes:1218092 (1.2 MB)
          Interrupt:10 Base address:0xc000

lo Link encap:Local Loopback
          inet addr:127.0.0.1 Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING MTU:16436 Metric:1
          RX packets:95 errors:0 dropped:0 overruns:0 frame:0
          TX packets:95 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:6884 (6.8 KB) TX bytes:6884 (6.8 KB)

root@stgraber-vm:~# cat /etc/network/interfaces
auto lo
iface lo inet loopback

auto br0
iface br0 inet static
    address 172.23.0.50
    netmask 255.255.255.0
    bridge-ports all

auto eth0
iface eth0 inet manual
    up ifconfig $IFACE 0.0.0.0 up
    up ip link set $IFACE promisc on
    down ip link set $IFACE promisc off
    down ifconfig $IFACE down

auto eth1
iface eth1 inet manual
    up ifconfig $IFACE 0.0.0.0 up
    up ip link set $IFACE promisc on
    down ip link set $IFACE promisc off
    down ifconfig $IFACE down

auto eth2
iface eth2 inet manual
    up ifconfig $IFACE 0.0.0.0 up
    up ip link set $IFACE promisc on
    down ip link set $IFACE promisc off
    down ifconfig $IFACE down
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