Deploying multiple SonicPoints and Apple TVs to stream content via AirPlay
In this scenario, multiple Apple TVs are connected wirelessly to a distributed (multiple SonicPoints broadcasting the same SSID, all managed by one SonicWall UTM appliance) wireless mesh of SonicPoints. Wired and wireless devices alike need to be able to stream content via AirPlay to the Apple TVs.
AirPlay uses Bonjour, actually MDNS, which is a protocol on top of multicast. Multicast is a special type of UDP IP traffic, which must be explicitly allowed in the SonicWall's configuration. To do so for this scenario, the LAN and WLAN interfaces were edited (Network menu > Interfaces page > Edit button) such that their advanced settings allow multicast (in the popup window that opens when the edit button is clicked, go to the Advanced tab and enable the Multicast checkbox). The Firewall module also had to be configured to allow multicast (Firewall Settings menu > Multicast page > Enable Multicast checkbox).
Furthermore, firewall access rules between the LAN and WLAN were necessary to open reception to/from the Apple TVs. Apple maintains a list of well-known ports used by their products (http://support.apple.com/kb/ts1629); however, this list may not be comprehensive as some ports were found to be in use for AirPlay which are not mentioned in the Apple KB. Those ports could be dynamic, so your results may vary. If you are a security minded administrator and don't wish to simply allow all traffic to/from the Apple TVs, theSonicWall 's built-in Packet Monitor feature will help you to identify which ports are in use.
At this point, AirPlay from the LAN to the WLAN will work as expected, but AirPlay from WLAN to WLAN *may* not work. SonicOS 18.104.22.168 contains a behavioral change for the way multicast traffic is handling in some WLAN to WLAN scenarios. It was necessary for this particular case, but may not be for all cases. If your SonicWall UTM appliance has an active Support contract, it may be advisable to consider upgrading to SonicOS 22.214.171.124 if you are experiencing a problem with WLAN to WLAN AirPlay (or other multicast) issues.