IP multicast is a method of sending IP packets from a single sender to multiple receivers simultaneously. It is a technique for efficient one-to-many and many-to-many communication over the internet.
In IP multicast, a single sender sends a single copy of a packet to a multicast group address, which is a special class D IP address. The packets are then delivered to all the members of the multicast group who have subscribed to receive them.
The main advantage of IP multicast over unicast or broadcast communication is that it conserves network bandwidth by sending a single copy of a packet to multiple receivers at once. This is especially useful for applications such as video and audio streaming, online gaming, and real-time collaboration.
To use IP multicast, applications must use a protocol such as Internet Group Management Protocol (IGMP) to join a multicast group and receive packets sent to the group address. Network devices such as routers must also be configured to support multicast routing and forwarding.
Some commonly used applications of IP multicast include video and audio streaming, stock quotes, online gaming, live events, and video conferencing.
- IP multicast is a network-layer protocol, which means it operates at the same layer as IP unicast and IP broadcast.
- IP multicast addresses are in the range of 126.96.36.199 to 188.8.131.52, with the high-order 4 bits of the address set to “1110”.
- IP multicast packets are forwarded only to networks that have interested receivers, which reduces unnecessary network traffic.
- IP multicast routing is based on Reverse Path Forwarding (RPF), which is used to ensure that multicast packets are forwarded only along valid paths, and not back to the source or in loops
- IP multicast can be used over both IPv4 and IPv6 networks.
- To join a multicast group, an application sends an IGMP join message to the local multicast router, which forwards it upstream toward the source of the multicast stream.
- Multicast traffic can be controlled through network policies, such as traffic shaping, access control lists, and Quality of Service (QoS) settings.
- Some popular IP multicast applications include IPTV (Internet Protocol Television), videoconferencing, stock market data feeds, online gaming, and real-time data distribution for scientific and industrial applications.
- IP multicast can help reduce the load on network servers and improve scalability by enabling efficient distribution of data to large groups of recipients without requiring separate unicast connections to each recipient.