IP Multicast (1)
IP Unicast, Multicast and Broadcast
- A IP broadcast goes to every device on the network, often distributing control data that supports the network.
- In IP multicasting, the data goes only to devices that request it.
- Unicast datagram has defined and unique sender and recipient.
IP multicasting is a way of forwarding data to a group of host systems simultaneously. It is similar to IP broadcasting except that instead of all hosts receiving the data, only systems which belong to a multicast host group receive the data.
A multicast host group is a group of systems which have the same Class D
- IP destination address (for example 224.99.0.6);
- Class D covers addresses: 224.0.0.0 - 239.255.255.255
Multicast must be enabled on hosts and routers
If multicast is not supported, we have to built a tunnel i.e. encapsulate multicast messages in unicast datagrams