View source for Unicast

[[Image:3networks-unicast.jpg]]


Unicast is peer-to-peer.  One sender and one receiver.  
The [[port|world wide web]] is built on unicasting, so is email exchange.  Most unicasting is done via [[TCP]], but isn't restricted to this.  

A [[p2p|peer to peer]] network is built on top of unicasting and takes advantage of the fact that you have relatively low-bandwidth uplink nodes distributed among many peers that then "feed" a high-speed consuming node. The receiver then assembles the chopped up pieces into a larger file which is compared to a checksum to make sure that all pieces are genuine.

Contrast this with [[broadcast|broadcasting]] which has one source that "feeds" multiple receivers at the same time (usually on the same [[LAN]]).  

Similarely [[multicast|multicasting]] does the same but allows the receiver to "opt-in".  Multicasting is designed to be routed and was historically not popular because of the CPU it took up for no charge of the sender.  There is a certain turn-around point though when it is costlier to harbour unicast traffic than multicast.