A multicast address is a logical identifier for a group of hosts in a computer network that is available to process datagrams or frames intended to be multicast for a designated network service. A multicast address can be used in data link layer ( layer 2) of the OSI Model. For IP multicasting, the authorities reserved the multicast mac address range from 01-00-5E-00-00-00 to 01-00-5E-7F-FF-FF for Ethernet and Fiber Distributed Data Interface (FDDI) media access control (MAC) addresses. The multicast MAC address is a special value that begins with 01-00-5E in hexadecimal. The remaining portion of the multicast MAC address is created by converting the lower 23 bits of the IP multicast group address into 6 hexadecimal characters.
The range of IPv4 multicast addresses is 224.0.0.0 to 239.255.255.255. By the help of multicast addresses, a source device can send a packet to a group of devices that belong to a multicast group. These devices are assigned a multicast group IP address. The source will always be a unicast address.
Multicast addresses can be used in remote gaming, where many players are connected remotely but playing the same game. Another use of multicast addresses is in distance learning through video conferencing, where many students are connected to the same class.
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