If you distribute content using multicast streaming, network traffic is directed through the standard Class D IP addresses (126.96.36.199 through 188.8.131.52). To multicast, you must have enabled multicast-forwarding on your network. The Internet Group Management Protocol (IGMP), supported by Windows Media Services, ensures that multicast traffic passes through your network only when a player requests a multicast connection, so enabling multicast on your routers does not flood your network.
The following firewall configuration enables multicast packets to traverse your firewall:
IP multicast address range: 184.108.40.206 to 220.127.116.11
To enable IP multicasting, you must allow packets sent to the standard IP multicast address range to come through your firewall. This IP multicast address range must be enabled on both the player and server sides, as well as on every router in between.