Transcript Chapter 1 - The Internet Has Arrived

Chapter 8 - Internet: The Early Years
• Many Independent Networks
• The Proliferation Of LANS
• Facts About LANs
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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 specialpurpose 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
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
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ARPA
backbone network
Internet
open system
RFC
TCP/IP
TCP/IP software
Wide Area Network (WAN)