Unicast, Broadcast, Multicast, Anycast

There are different transmission techniques in communication if we divide communication according to the receivers. These communication techniques are:

• Unicast
• Multicast
• Broadcast
• Anycast

  Unicast is the communication that there is only one receiver. This is one-to-one communication. Multicast is the communication that there is one more receiver. Only the members of the multicast group receive the multicast traffic. Broadcast is also the communication that there is one more receiver but this time, all the receivers receive broadcast traffic. Anycast is the communication that is developed with IPv6. With anycast, the traffic is received by the nearest receiver in a group of the receivers that has the same IP.

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  Here, in this article series, we will focus on multicast.   Simply,  we can do the multicast job, with unicast messages or with one broadcast message. But these methods has disadvantages.   For example, if you use Unicast Message, you need to send the same message as many  as receivers. If you have 3 reciepent, you need to send 3 same message. Think about it. What if you have 100 receipent! This will be bandwith intensive.   If you use Broadcast Message, this time all the network nodes even if they do not need that message willl receive the message. This is an unnecessary traffic. But if you use Multicast Message, you can send the packet to the only related nodes with only one message. With multicast you can send one message to a group of receivers. This is the main definition for multicast. There is also Anycast Message that the packet is sent to the closest host between the destinations that has the same IP address. Multicast is used with Multicast Groups in IP networks. IP Multicast Group is a group consist of the Multicast Receivers. The nodes that wants to receive this Multicast traffic, become a member of this Multicast Group. A Multicast Source send Multicast traffic to this group and all the members receive this Multicast traffic. Source itself do not need to be a member of that Multicast Group.