Multicast

Multicast is a the delivery of information to multiple destinations simultaneously. Typically used to refer to IP Multicasting, which is a protocol for efficiently sending to multiple receivers at the same time on TCP-IP networks, by use of a multicast address. It's also commonly associated with audio/video protocols such as RTP.

By comparison with multicast, conventional point-to-single-point delivery is called unicast.

There are two basic kinds of multicast delivery:

• dense multicast
• sparse multicast

Modern multicast algorithms are often capable of combining and managing the two.

Multicast is not in general use in the commercial Internet, due to interoperability problems and the lack of a compelling business model for multicast.

However, some communities within the public Internet make regular use of multicast (see the MBONE for an example), and multicast is used for special applications within private IP networks.

IP multicast protocols

• Protocol independent multicast (PIM)
• Distance vector multicast routing protocol (DVRMP)
• Multicast OSPF (MOSPF)
• Multicast BGP (MBGP)
• Internet group management protocol (IGMP)

See also:

• Spanning tree
• Flooding algorithm
• Anycast

External links

• IP Multicast Applications: Challenges and Solutions (RFC 3170)