I have multiple VLANs in my network. One VLAN is for my Wireless network and another VLAN for my Wired network. (There are other management VLANs)
My main router is a Cisco 2900 series with a WLAN controller for the Cisco Aironet Access Points.
When I connect the Apple TVs to the wired network, computers in the same VLAN can communicate with them and the Wireless laptops can't; and when the Apple TVs are used as wireless clients, only the Wireless laptops can communicate with the Apple TVs.
I understand the Apple TVs are not using multicasting but mDNS as I was originally targetting my focus for a solution. The funny thing is that once a multicast address was established in the WLAN, the wireless laptops were able to reach the wireless Apple TVs (Air Speaker function) which were not reachable. Perhaps this is a mDNS and multicast issue?
Cisco tells me: "The issue with this application is that it uses mDNS ip address 188.8.131.52. According to the RFC it will not route any packets with that destination:
Per RFC3171 (http://www.iana.org/assignments/multicast-addresses
Be able to reach the Apple TVs across multiple VLANs regardless of the client source subnet (locally, of course).
IF I AM MISTAKEN IN ANY OF THE CONCEPTS DESCRIBED ABOVE, PLEASE ALSO CLARIFY WHY.