About multicast IP addresses and ports
Applies To: Windows Server 2008, Windows Server 2008 R2
Multicast IP addresses are class-D addresses that fall within two ranges: 224.0.0.0 through 239.255.255.255 and FF00:0000:0000:0000:0000:0000:0000:0000 through FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF. The addresses in the first range are Internet Protocol version 4 (IPv4) addresses. The addresses in the second range are Internet Protocol version 6 (IPv6) addresses.
For intranet use, it is recommended that you use IPv4 addresses in the range 239.*.*.*. Port numbers can range between 1 and 65535. The routers on the network over which you are transmitting your content must be multicast-enabled, meaning that they must be able to interpret class-D addresses or they will not be able to forward your multicast information to clients.