By default, a Silverlight application may use UDP multicast networking APIs. If this policy is disabled, the application can't directly use multicast.
This setting does not affect the Silverlight MediaElement, which can use multicast if the media server and network support it. Unlike the UDP multicast API, the MediaElement doesn't allow the application to see the multicast data that's being sent and received.
| Registry Hive | HKEY_LOCAL_MACHINE |
| Registry Path | Software\Microsoft\Silverlight |
| Value Name | AllowUdpMulticastClientApi |
| Value Type | REG_DWORD |
| Enabled Value | 1 |
| Disabled Value | 0 |