In computer networking a multicast address is an identifier for a group of hosts that have joined a multicast group. A computer network is a system for communication among two or more computers. ... Multicast is the delivery of information to a group of destinations simultaneously using the most efficient strategy to deliver the messages over each link of the network only once and only create copies when the links to the destinations split. ...

IP Multicast Addresses

Within IP it is historically known as a class D address, a type of IP address. It ranges from 224.0.0.0 to 239.255.255.255 or 224.0.0.0/4. Address assignments out of this range are specified in the IETF 'best current practice' document also known as RFC 3171. The Internet Protocol (IP) is a data-oriented protocol used by source and destination hosts for communicating data across a packet-switched internetwork. ... An IP address (Internet Protocol address) is a unique number, similar in concept to a telephone number, used by machines (usually computers) to refer to each other when sending information through the Internet. ... The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards. ...

The 224.0.0.0 to 224.0.0.255 range is assigned to multicasting on the local LAN only. Well known examples are RIP which uses 224.0.0.9 and OSPF which uses 224.0.0.5. A local area network (LAN) is a computer network covering a local area, like a home, office or small group of buildings such as a college. ... This article is chiefly about the Routing Information Protocol for IPv4 and IPv6. ... Open Shortest Path First (OSPF) is a link-state, hierarchical Interior Gateway Protocol (IGP) routing protocol. ...

The following table is a partial list of well-known Class D addresses that are reserved for IP multicasting and registered with the Internet Assigned Numbers Authority (IANA). The Internet Assigned Numbers Authority (IANA) is an organisation that oversees IP address, top level domain and Internet protocol code point allocations. ...

For a full and current listing of additional IP addresses that are reserved for multicasting, see the Internet Multicast Addresses Web site. Virtual Router Redundancy Protocol (VRRP) is a non proprietary routing protocol described in RFC 3768 meant to increase the availability of a first hop router servicing statically configured hosts behind it. ... An H.323 Gatekeeper is an entitiy that manages a H.323 zone, providing address information/translation and other services to the terminals within the zone, and for Gatekeepers managing other zones. ...

The 233.0.0.0/8 range has been assigned by RFC 2770 as public multicast address space that is aligned along autonomous system number allocations. Each byte of the AS number corresponds to the second and third octets of the multicast address. In the Internet, an autonomous system (AS) is a collection of IP networks under control of a single entity, typically an Internet service provider or a very large organisation with redundant connections to the rest of the Internet, that adhere to a single and clearly defined routing policy. ... An octet, in general, is a group consisting of eight (8) elements. ...

The 239.0.0.0/8 range has been assigned by RFC 2365 as a locally administered address space with local or organizational scope.

For advice on choosing multicast addresses for use in your application, see this page on multicast address assignment.

Ethernet Multicast Addresses

Some well known Ethernet multicast addresses: Ethernet, Wi-Fi, Token ring, FDDI, PPP RS-232, EIA-422, RS-449, EIA-485, 10BASE2, 10BASE-T... Ethernet (this name comes from the physical concept of ether) is a frame based computer networking technology for local area networks (LANs). ...

Complete list: http://www.cavebear.com/CaveBear/Ethernet/multicast.html Cisco Discovery Protocol is an OSI Layer 2 network protocol, a Cisco Systems proprietary protocol used by Cisco routers to obtain protocol addresses of nearby devices, also to show the IOS version running on these devices. ...