Multicast over Openvpn



  • All, I know this topic has been brought up a few times but, as per my findings, I have not seen any successful outcomes from the various discussions. The target is to have multicast working over an OpenVPN tunnel in tap mode between two sites (A and B) allowing site B to receive the media streaming generated by a media server on site A. I set up the tunnel using the SSL peer-to-peer configuration and I can actually ping/see the machines on both sides. Site B machines (192.168.255.50/27) are on the same subnet of site A (192.168.255.1/24).

    Looking at the pfTop or at the Diagnostic-States on site B I can see that the media server ip from site A is trying to reach for the typical multicast ip addresses (224.0.0.x or 239.255.255.x). Something similar can be found on site A: I can see the client machine ip address looking to connect to the multicast addresses.

    I tried unsuccessfully to configure also the IGMP proxies but I guess I am making mistakes either with the upstream/downstream lans on both sides or with the usage of the proxies themselves because I get many messages like this one "The IGMP message was local multicast. Ignoring.**"

    My questions are:

    1. if IGMP proxies are actually needed to make multicast work over the OpneVPN tunnel which is their correct configuration?
    2. If IGMP proxies are not required (because I am running a TAP VPN?) what else is needed to make multicast work?

    I can provide all the network details and configuration if required but I think the answer to the two "philosophical" questions above should solve the issue or at least address the solution...maybe :-)


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