IP routing is needed to direct units of data known as packets through a network. In a packet-based network, a large file is broken down into packets before it is transmitted from one end of the network to the other. Routing is required in network environments where multiple segments are patched together over a large area. The segments, which can potentially be different transport media, are linked by routers. No routing is required when nodes are connected to the same network segment, such as a LAN or a point-to-point link. The following two kinds of routing are distinguishable by their different approaches to packet forwarding:
In unicast routing, packets are forwarded toward ...