Unicast, Multicast, Broadcast. What Does It Mean?
By Stephen Bucaro
Unicast, Multicast, and Broadcast are different network transmission methods.
Unicast is a transmission between a single sender and a single receiver
identified by a unique address over a network.
For video, even though multiple client computers might request the same video
at the same time, a separate unicast data stream is transmitted to each client computer.
Multicast is a transmission between a single sender and multiple receivers
simultaneously. The clients that receive the multicast may have a common set of criteria,
or be specifically set up as a multicast group. A special kind of multicast, referred to as
"anycast" is a communication between any sender and the nearest receivers in a network.
Broadcast is a transmission from a single sender to all clients on the network.
Routers can be used to divide a network into separate broadcast domains. A broadcast is
then limited to a broadcast domain. The IP address 255.255.255.255 indicates a broadcast,
and this address is never forwarded by routers.
More Networking Protocols and Standards:
• The OSI Physical Layer
• A Simple Description of the IPv6 Header and Datagram
• Video - The Upper Layers 5 Through 7 of the OSI Networking Model
• TCP/IP Features
• OSI Transport Layer
• IPv4 Datagram Fields
• Network Operating Systems
• OSI Network Model
• Protocol Suites
• SYN-ACK Handshake to Establish a TCP Connection