Network Problems with Linux-Bridges after update

[Paul Scheller]

Hi

I have a problem with using Linux-bridges on Ubuntu-Server 12.04 after 
upgrading on Monday 24th September.

The Problem is that all incoming Packages are dropped/lost between the 
physical device and the bridge. I can see, by using tcpdump and pinging, 
that the icmp-replays hit the physical device but not the bridge.
setting ´sysctl net.bridge.bridge-nf-call-iptables=0' prevents the 
problem and the machine has full network access again.
This bug:
https://bugs.launchpad.net/ubuntu/+source/procps/+bug/50093
is preventing me from using the workaround at the right place(adding it 
to sysctl.conf) because the machine is subject to automated shutdowns 
and boots (for power-saving) and there for it can not be done by hand too.

For the environment:
The server is a quiet minimal machine with KVM installed as host for 
virtual machine in a cloudenviroment (OpenNebula) and is using the 
bridges to create a HPC-Cluster of virtual machines with other servers 
in the network.

Currently 2 machines are affected(one freshly installed today 27.9, the 
other one upgraded on 24.9). Other machines are not fully up to 
date(using Linux-image 3.2.0-30) and working fine.

If some one can point out what is causing this problem or has a solution 
i would be thankful.
If you need any more info I can provide this also testing is currently 
no problem.

Thanks in advance
Paul Scheller