Description of problem:

During testing of https://bugzilla.redhat.com/show_bug.cgi?id=1575512 I found that multicast traffic is not able to pass from north to south (and vice versa). 

After talking with Lucas (lgomes) and Dimitru (dceara) I understood that we only enable igmp in the logical_switch itself and we do not do anything at the router level. The router will just drop multicast packets unless mcast_relay is enabled at router level.

Feel free to change the BZ component to documentation in case we are not going to support north-south multicast traffic through OVN router in OSP16.1.


Version-Release number of selected component (if applicable):
RHOS-16.1-RHEL-8-20201110.n.1

How reproducible:
100%

Steps to Reproduce:
1. Create security group that allows ssh, icmp, igmp and udp port for multicast traffic (5001)
2. Create VM (sender) on the external network using this security group
3. Create router, internal network, connect both networks to the router
4. Create a VM (receiver) on internal network using the security group from step 1.
5. Send multicast stream from the sender VM and subscribe from the receiver VM

Actual results:
Multicast stream from the sender is not reaching the receiver

Expected results:
Multicast stream from the sender reaches the receiver

Additional info: