trol to the clones of the PC market it single-handedly created), several small startups, among which was an unknown little entity at that time called Cisco Systems, started delivering small network machines called routers. They were simple microcomputers based on a bus architecture. I/O adapters for dif- ferent layer 1 and layer 2 protocols, such as RS-232, IEEE-488, SDLC/BSC, X.25, frame relay, and Ethernet, would be plugged into the fast backplane of the router chassis. A master CPU along with plenty of memory would route the traffic from any port to any port based on some forwarding poli- cies. These policies would associate addresses with end systems, and a lookup table would show from which port each address could be accessed and under what conditions or circumstances. The router was eventually sold with user-friendly configuration software, which would allow a network admin- istrator to easily configure the lookup tables and to install the router inside a network in a straight- forward way. A huge new multibillion-dollar industry was created. The success of the router manufacturers enabled them to invest heavily in R&D. Carrying the torch of standardization bodies such as the Internet Engineering Task Force (IETF), a plethora of routing protocols were developed. They would enable adjacent routers to communicate automatically with each other. They would also notify their peers about the status of the network at every neigh- borhood, communicate route links toward specific target addresses, and SO on. The Routing Information Protocol (RIP), Open Shortest Path First (OSPF), Interior Gateway Protocol (IGP), Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. THE EVOLUTION OF NETWORK TECHNOLOGY: DISTRIBUTED COMPUTING AND THE CONVERGENCE OF NETWORKS THE EVOLUTION OF NETWORK TECHNOLOGY 11 Exterior Gateway Protocol (EGP), and Border Gateway Protoco