Some update on this:

I've created an identical virtualized environment an a different machine, and here the broadcast massages get forwarded to the guests. Only difference is the hardware.

So could it really be the hw with the brand NIC? (Dell PowerEdge T110 II / Intel 82574L Gigabit)


Thanks,
Andras


Begin forwarded message:

Date: Thu, 31 Jul 2014 08:17:31 +0200
From: Andras Horvath <[log in to unmask]>
To: [log in to unmask]
Subject: kvm bridge broadcast traffic


Hi Everyone,

I've run into a strange problem that I am not able to track down in the last 3 days. Could someone kindly help and give directions?

On my 6.5 x64 system my bridged KVM guests (several kind of Windows and many kind of Linux guests) do not get the broadcast messages. Every network packets reach them from the subnet except broadcast and multicast messages. How can that be?

In kernel the bridge filter by iptables is turned off - turning on STP does not help - enabling promisc mode in interface does not help either.

Running tcpdump on host shows that the broadcast reaches the interface from a different computer on the subnet, but does not get in the guest. I ran tcpdump on the Linux guests and wireshark on the Windows ones. Testing the same with VirtualBox on a different computer, tcpdump and wireshark shows the broadcast packets.

What is weird that every network packets reach my guests in KVM except the broadcast ones.


Any help appreciated.

Thanks,
Andras