Chapter 8 - Internet: The Early Years

• Many Independent Networks • The Proliferation Of LANS

• Facts About LANs – Engineers have devised many LAN technologies – LAN performance determines cost– high performance LANs are expensive – A particular LAN technology may only work with specific

computers.

– A LAN technology is chosen for its speed, ease of use, and the availability of interfaces for specific computers. Many large organizations use many LAN technologies.

Chapter 8 - Internet: The Early Years• LANs Are Incompatible

– Various LAN technologies are completely incompatible.

• Wide Area Technologies Exist– A WAN differs from a set of disjoint transmission lines because

the WAN includes an additional special-purpose computer at each site that connects to the transmission lines and keeps communication independent of the computers that use the WAN.

• Few WANs, Many LANs • WANs And LANs Are Incompatible

– Many LAN and WAN technologies exist, and most are incompatible with each other. One cannot produce a usable large network merely by interconnecting the wires from two different networks.

Chapter 8 - Internet: The Early Years• The Desirability Of A Single Network

• The Department Of Defense Had Multiple Networks • Connecting Disconnected Machines • The Internet Emerges

– ARPA funded research to investigate ways to solve the problem of incompatible networks. Both the project and the prototype system that researchers built became known by the name Internet.

• The ARPANET Backbone • Internet Software

• The Name Is TCP/IP (The TCP/IP Internet Protocol Suite)

Chapter 8 - Internet: The Early Years• The Shock Of An Open System

– Prevailing opinion suggested that a company selling computer networks could achieve maximum profits by protecting their technology with patents

– A network system is closed if a company owns the technology and uses patents and trade secrets to prevent other companies from building products that use it. By contrast, the Internet is an open system because all specifications are publically available and any company can build a compatible technology.

• Open Systems Are Necessary– A large organization needs an open network system because it

acquires computers from multiple vendors; using a closed network system restricts the computers that can connect to the network.

Chapter 8 - Internet: The Early Years

• TCP/IP Documentation Is Online – For historical reasons, the documents that define

TCP/IP and related Internet technology are called Requests for Comments [RFCs]

– Because RFCs that documented the technical details of TCP/IP and the Internet project were accessible over the ARPANET, work on the project proceeded more quickly.

• The Military Adopts TCP/IP

Chapter 8 - Internet: The Early Years

• Terms– ARPA

– backbone network

– Internet

– open system

– RFC

– TCP/IP

– TCP/IP software

– Wide Area Network (WAN)