Implementation Of Ip Multicast - 3Com 8807 Configuration Manual

Application of Multicast
Implementation of IP
Multicast
IP Multicast Addresses
distribution of these users in the group. Finally, the information is transmitted to
the intended receivers B,D and E properly and correctly.
In multicast mode, the information sender is called the "multicast source", the
receiver is called the "multicast group", and the routers for multicast information
transmission are called "multicast routers". Members of a multicast group can
scatter around the network; the multicast group therefore has no geographical
limitation. It should be noted that a multicast source does not necessarily belong
to a multicast group. It sends data to multicast groups but is not necessarily a
receiver. Multiple sources can send packets to a multicast group simultaneously.
Advantages
The main advantages of multicast are:
Enhanced efficiency: It reduces network traffic and relieves server and CPU of
■
loads.
Optimized performance: It eliminates traffic redundancy.
■
Distributed application: It enables multipoint application.
■
IP multicast technology effectively implements point to multi-point forwarding
with high speed, as saves network bandwidth a lot and can relieve network loads.
It facilitates also the development of new value-added services in the Internet
information service area that include online live show, Web TV, tele-education,
telemedicine, network radio station and real-time audio/video conferencing. It
takes a positive role in:
Multimedia and streaming media application
■
Occasional communication for training and cooperation
■
Data storage and finance (stock) operation
■
Point-to-multipoint data distribution
■
With the increasing popularity of multimedia services over IP network, multicast is
gaining its marketplace. In addition, the multicast service becomes popular and
prevalent gradually.
In multicast mode, there are questions about where to send the information, how
to locate the destination or know the receiver. All these questions can be
narrowed down to multicast addressing. To guarantee the communication
between a multicast source and a multicast group (that is, a group of receivers),
the network layer multicast address (namely the IP multicast address) is required,
along with the technique to correlate it with the link layer MAC multicast address.
Following is the introduction to these two kinds of addresses.
IP Multicast Addresses
According to the definition in Internet Assigned Number Authority (IANA), IP
addresses fall into four types: Class A, Class B, Class C and Class D. Unicast
packets use IP addresses of Class A, Class B or Class C, depending on specific

Implementation of IP Multicast

411