On a CentOS 6.5 host, I have a couple of guests - Ubuntu 12.04 and CentOS 6.5.
The Ubuntu guest is generating mcast traffic that is visible via a
tcpdump on the br3 interface. It is also visible on the other VM.
It is not on the associated eth3 interface, nor does it make it out the wire to other hosts.
We've been through bridged networking with kvm and this:
$ sed -I 's/^\(net.ipv4.ip_forward =\).*/\1 1/' /etc/sysctl.conf; sysctl -p
Along with these articles titled:
- Centos 6.5 KVM issue with bridged interface to virtual machine
- and setting
2, via this articled, titled: Why does Red Hat Enterprise Linux 6 and above invalidate / discard packets when the route for outbound traffic differs from the route of incoming traffic?
- ... and a few other things.
Does anyone have anything else?