Transmission Communication Modes

Unicast

As the name suggests, it is the communication between two nodes. It is also known as one-to-one. In unicast, the traffic is intended for a specific host and not detected by any other host on the network. It is used in our daily lives in the form of browsing websites, file downloading through FTP (file transfer protocol), and connection with other devices through SSH (Secure Shell).

Broadcast

It is usually known as a one-to-all type of communication. In broadcast, the traffic reaches all nodes irrespective of whether they are the intended nodes, or even if they need the traffic or not. It is used when all the hosts are on the same subnet. Broadcast usually apply on layer 2 where MAC addresses of hosts are used to transfer messages or traffic. Some of the problems attached with broadcast communication include wastage of bandwidth, disturbance in LAN, and causing many collisions. The ARP (address resolution protocol) is used for broadcast communication. One of the examples of the broadcast is the discovering of messages by DHCPv4.

Multicast

It is also known as one-to-many. Multicast also transfer the traffic to more than one host, but it transfers the traffic to the selected number of hosts which are interested in that traffic, rather than the uninterested ones. As compare to broadcast the bandwidth usage becomes low, the disturbance also becomes low, and collision in the network are also comes down, as only the selected number of hosts received the traffic. The protocols used for multicast are usually UDP protocols, such as SLP (service location protocol), which is mostly used for multicast. Some of the examples of multicast include video conferencing, hello messages of OSPF (open shortest path first) protocol, hello messages of EIGRP (Enhanced Interior Gateway Routing Protocol) protocol, and IPTV (Internet Protocol television).

Anycast

Anycast is based on the distance, as in anycast router selects the path which has fewer hops, less cost, and less distance to the required destination or endpoint. It is known as one-to-one-of-many, as one single accessing point has many potential receivers, but the sender selects only one receiver. Anycast can be easily illustrated through an example, like suppose a person has a home in the US, and he is trying to access the webserver which has DNS servers located in France, Germany and US. So while accessing the DNS server anycast has the ability to find the DNS server with the shortest path, which is the US, and connects the user with it. By using anycast, the user will get a faster reply, and the network traffic also becomes low. One of the most common examples is content delivery systems.