how is multicast ip assigned ?

hi again!

need some help with understanding how multicast ip is assigned to machines in an organisation???????

usually; if you try to force a static multicast ip to a machine; it does not take it!!!!!!!!

then how is it done??????

I don't know the ins and outs of it but you cannot assign a multicast address in the way you would assign a standard IP address. Simply, there is a class problem and the multicast ranges live in Class D. Thats not how multicasts are used.

Dependant on the application, the multicast uses different IP addresses which the application on the device will then respond to when it hears it on the wire.

A good example of this is the address 224.0.0.1 which is a multicast address that means all hosts in this broadcast domain please respond. If you have a packet sniffer and a network with several devices you can ping 224.0.0.1 and see all hosts responding to the ping even though the actual ping output will show only one reply. Similarly, 224.0.0.5 corresponds to all routers running OSPF within your network which I think is how OSPF communicates. 224.0.0.10 = IGRP Routers, 224.0.0.12 = DHCP, etc, etc.

You can find out more information here : www.cisco.com/en/US/tech/tk828/technolog...186a00802d4643.shtml - Make sure you are sitting down for this link. :twisted:

As I said, I am not up on all the details of multicast yet but just letting you get the idea of how multicast works.

Hi leopold,
According to my knowledge.
Multicast ip are used vertually they are not used like other range of IP.
Peredefined Multicast IP are used by routing protocol e.g. OSPF use 224.0.0.5 and 224.0.0.6

some application aslo use multicat range of IP.
Like use for videostriming
one databse server having videos when user access some video
that server load software in to the client in that software one multicast IP is cofigure and videos are send on that IP whic will reach up to client..

Please correct me if I am wrong. :oops: