Multicast application in Local area network

The multicast address isn't assigned to the machine, it is the address you put in the destination address of the data you send. If the address matches the system addressing and such it will be accepted and acted on.

Multicast is a system where multiple devices listen on a common address. Usually such devices will have a unique address as well. Typically it is used for things like discovery protocols so systems can find devices of a particular type such as printers.

For more information see here:
http://en.wikipedia.org/wiki/Multicast_DNS

hai

           Suppose my ubuntu system have ip address and 10.1.0.100/24 .How can this system join a multicast group ?
and access the live video streaming fro the network

regards
Aneesh

A device can have multiple addresses simultaneously, if this is a PC, printer or anything else. For example your PC probably has a unique IPv4 and a unique IPv6 address.

These unique addresses are useful because they allow you to set-up a one to one connection and because its one to one then protocols exist to ensure all data gets to its intended recipient and handle any problems such as lost data. The best known on these is TCP and without it you would not have been able to ask your question and I could not have sent you the answer because the web relies on it.

The problem with this is that it's a one to one connection so if I want to send something to 1000 computers at the same time I need to open 1000 connections each sending effectively the same information. This is inefficient so another method for sending data exists UDP is potentially a one to many protocol. The upside of this is the data only needs to be sent once. It does not matter how many devices are listening. The down side is that there is no inherent way for the computer doing the sending to know if all the recipients got the message. Everyone just looks for all messages from a particular address.

Taking this one stage further more than one device can respond to messages sent to a particular address. This is a multicast system. Because of the possibility of data being lost then it is usually used either as a mechanism to discover services or in cases where data loss is acceptable such as streaming live video or sound because being live if you missed the data its gone. I can't be sent again because it would then be old data (not live).

As an end user you do not need to change the IP address of the computer to access multicast services. The application just has to listen to data sent to the multicast address. UDP is also used with non multicast addresses

The computer will still its own unique address its just listening to packets for other addresses too. This is the software developers problem for a particular application not yours.