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:

Does anyone have anything else?

closed as off-topic by Jeff Schaller, Rui F Ribeiro, Satō Katsura, mdpc, Stephen Rauch Sep 7 '17 at 2:00

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions describing a problem that can't be reproduced and seemingly went away on its own (or went away when a typo was fixed) are off-topic as they are unlikely to help future readers." – Jeff Schaller, Rui F Ribeiro, Satō Katsura, mdpc, Stephen Rauch
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We do not understand what was under SELinux control, but something was and simply turning off selinux and rebooting got it working.

SELinux: Secure or Useable. Pick one.

  • 1
    Did you try running with "Permissive' settings, and simply following the popups to enable whatever selinux was complaining about? – Dani_l Nov 22 '16 at 14:35

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