Special Edition Using TCP/IP, Second Edition

Evolution of Network Routing Architecture

Now that you are familiar with how routing is managed, knowledge of the underlying routing architecture is essential to comprehend how routing mechanisms work. Routing architectures have evolved over the years beginning with the early ARPAnet to the Internet that we know today. Initially, the Internet was designed with a collection of core routers that stored all possible destination routes in their routing tables. Each router that linked the sending computer’s network to the Internet used the default route that always pointed to any one of the core routers. By following the default route determined by local routers, datagrams that contained partial routing information ultimately reached their correct ...