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Cannot Multicast within a VLAN

Posted: Sat Dec 12, 2015 3:11 am
by awonglk
Hi all..

I seem to having an issue with multicast/broadcast traffic on a VLAN (protocols like DLNA, Chromecast etc etc). I have a Mikrotik wireless AP in 'ap bridge' mode attached to RB850gx2 router trunk port (ether4 in this case). Some key characteristics I thought might be important for my issue (screenshots attached):

1. AP clients configured to use VLAN tag 20
2. The wAP itself gets a 'management IP' on a different network

All wireless clients connect just fine, receiving IP from DHCP server on VLAN2, and can ping/talk to each other. But the problem starts when I need to use multicast protocols like DLNA. I thought that by having clients on the same 'VLAN' that protocols that broadcast on that VLAN is visible to all clients. For me DLNA or Chromecast servers are not visible to other clients at all.

Am I missing anything obvious?


Anthony

Re: Cannot Multicast within a VLAN

Posted: Sun Dec 20, 2015 12:28 am
by ConnectivityEngineer
I am not 100% sure however when you referenced the WAP is getting its management IP on a different network - it had me thinking.

If both the sender and receiver for a multicast group are on the same local broadcast subnet, then the routers do not need to be involved in the process, and communication can take place directly...

Can you verify the Chromecast is on the same subnet ?

If it is not - the good news is - This is still possible.
MikroTik supports PIM-SM multicast routing protocol.( basically platform independent)

http://wiki.mikrotik.com/index.php?titl ... edirect=no is a great place to start.

In the WIKI there is a pretty decent example that should help if they are NOT in the same subnet

Re: Cannot Multicast within a VLAN

Posted: Fri Aug 16, 2019 8:30 pm
by jeandconte
I got the same issue. Someone managed to solve it?

Re: Cannot Multicast within a VLAN

Posted: Sun Jan 30, 2022 4:40 am
by awonglk
Realised I never really solved this until 6 years later since I posted it :) had a look into it more this time. What fixed it in the end had nothing to do with VLANs..

I just turned on multicast-helper and set it to "full"

My Airprint printer showed up and even getting IPv6 address. So I guess I can finally call it solved.