Unicast is the process of forwarding unicasted traffic from a source to a destination on network. Unicasted traffic is destined for a unique address. In this case there is just one sender, and one receiver. The term exists in contradistinction to multicast, communication between a single sender and a group of selected receivers, and anycast, communication between any sender and a group of receivers near the sender in a network. An earlier term, point-to-point communication, is similar in meaning to unicast.

Unicast transmission is the predominant form of transmission on LANs and within the Internet. All LANs (e.g. Ethernet) and IP networks support the unicast transfer mode, and most users are familiar with the standard unicast applications such as http, smtp, ftp and telnet, which employ the TCP transport protocol. The new Internet Protocol version 6 (IPv6) supports unicast as well as anycast and multicast. Many routing protocols such as Routing Information Protocol (RIP) and Open Shortest Path First (OSPF), are designed to provide unicast routing on Internet effectively.

IPv6 has unicast, multicast, and anycast. Broadcast has disappeared as a term, but is considered one form of multicast.

Unicast and Unicast Routing

Related Terms:Multicast, Broadcast, Anycast, TCP, IPv4, RIP, OSPF