What is Unicast?
Unicast is a type of communication where data is sent from one computer to another computer. Unicast is a one-to-one type of network communication. Different data streams are generated for each Unicast connection. This type of communication is the option when clients need different data from network server.
In Unicast type of communication, there is only one sender, and only one receiver.
Example for IPv6 Unicast type of network communication:
1) Browsing a website. (Webserver is the sender and your computer is the receiver.)
2) Downloading a file from a FTP Server. (FTP Server is the sender and your computer is the receiver.)
What is Multicast?
Multicast is a type of communication where multicast traffic addressed for a group of devices on the network. IPv6 multicast traffic are sent to a group and only members of that group receive the Multicast traffic.
Devices which are interested in a particular Multicast traffic must join to that Multicast group to receive the traffic. IPv6 Multicast Groups are identified by IPv6 Multicast Addresses.
In Multicast, the sender transmit only one copy of data and it is delivered to many devices (Not all devices as in IPv4 Broadcast) who are interested in that traffic.
What is Anycast?
Anycast is a type of IPv6 network communication in which IPv6 datagrams from a source are routed to the nearest device (in terms of routing distance) from a group servers which provide the same service. Every nodes which provide the same service are configured with same Anycast destination address.