Delivery Semantics in Routing

Routing schemes differ in their delivery semantics:

• unicast delivers a message to a single specified node;
• broadcast delivers a message to all nodes in the network;
• multicast delivers a message to a group of nodes that have expressed interest in receiving the message;
• anycast delivers a message to any one out of a group of nodes, typically the one nearest to the source.

Unicast is the dominant form of message delivery on the Internet, and this article focuses on unicast routing algorithms.