Introduction to Routing

Routing is the process that a router uses to transmit packets to a destination network. A router makes decisions based on the destination IP address of a packet. Along the way, use the various facilities of the destination IP address to direct the packet in the right direction so that it reaches its destination. To make the right decisions, routers must know the direction to take to the remote networks. When routers use dynamic routing, this information is provided by other routers. When static routing is used, a network administrator manually configures information about remote networks.Since the static routes must be configured manually, any change in the network topology requires the administrator to add and remove static routes to reflect the changes. In a large network, this manual maintenance of routing tables can generate a significant administrative burden. On small networks where few changes are possible, static routes require very little maintenance. Due to administrative requirements, static routing does not offer the same scalability as dynamic routing. Even in large networks, static routes are planned to achieve a specific purpose are often configured in conjunction with a dynamic routing protocol.