Networking Basics:

A network is a group of interconnected devices (computers, printers, peripherals, etc) that allow for the sharing of information and resources between senders (source) and receivers (destination computer)

node: a device capable of communicating on a network

Devices connected by cables (copper, glass, plastic, radio wave and microwave transmissions.

internetwork: two or more devices connected together and communicating
--internetworking: ability of different networks to communicate using special hardware and software making it possible for two networks to communicate even when using different protocols.

Types of Networks:

LAN (local area network)

Characteristics:

• good for small areas
• high speed comminication - 10 Mbps or faster
• provide access for multiple devices
• use LAN specific equipment (repeaters, hubs and NICs

LANs lower equipment costs by centralizing resources and maintain security of information. Can be used to enhance collaboration and provie training via audio and video streaming.

A LAN is designed to connect nodes so they may share resources.

Due to limitations in distance, performance and manageability a LAN is typically confined to an office or building.

Hubs and switches are central devices that are interconnected via cables to allow data transmission to pass between network nodes.

Wireless LANs use access Access Points (APs) to transmit and receive data.

Bridges and Routers are used to interconnect LANs.

Network Interface Cards (NICs) -allow communication among devices.

MAN (metropolitan area network)

Characteristics:

• Sites dispersed across city and surroundings
• communication speeds of 100s of Mbps to gigabit speeds
• Single point of connection between LANs
• Use routers, telephone and ATM (Asynchronous Transfer Mode) switches and microwave antennas.

Constitute LANs interconnected across a city.

Very expensive but much faster than WANs. Offer better speed because of high-end cable and equipment.

Typically have one connection between sites due to cost of purchasing existing cable from telecommunication companies or having new cable installed.

WAN (wide area network)

Characteristics:

• Cover large geographical areas (can be gobal)
• Slow communication speeds
• Access is limited (one WAN link shared among all LAN devices)
• use routers, modems and WAN switches for communication

Wide Area Network (WAN) -connects two or more LANs (or MANs) over slow connections leased from phone company.

Global connections require satellite connectivity.

WAN speed is between 56Kbps and 1.5 Mbps (though 45Mbps is possible)

The internet is one big WAN!

CAN (campus area network)

A specialized network providing services through high-speed fiber connections between buildings with more than one LAN

Public Telephone System

Public Switched Telephone Network (PTSN) - comprised of several interconnected telecomunication companies.

Hush-a-Phone & Carter Electronics court cases ended AT&Ts monopoly. In 1966 the FCC ruled that devices not owned by AT&T could be attached to the telephone network.


Origins of First Networks:

First networks were mainframe systems running over dedicated lines

Semi Automatic Ground Environment (SAGE) developed in 1958 to link goverment computers at radar stations in US and Canada

Compatible Time Sharing System developed on IBM mainframe in the 1960's at MIT allowing users to run tasks at the same on the same system. Later used modems to connect over dedicated lines internally (user dialed number to access system) and eventually spread campus wide and even some remote home access.

Network Communication

Early networks were large, expensive and difficult to use, relying on terminals to process requests to mainframes before another terminal could make a request.

The 1970s saw the advent of communication protocols including Token Ring, ARCNET and Ethernet)

Ethernet being the most significant as it became part of the packet switching necessary for ARPAnet and ALOHAnet networks
ARPAnet Advanced Research Projects Agency (ARPA) of the US Department of Defense developed an experimental network created as a communication solution capable of withstanding a bomb attack. Also provide collaboration methods fo universities and government using e-mail. Disolved in 1989 leaving behind a public structure known as the internet and renamed the military system DARPAnet (Defense Advanced Research Projects Agency network).

The Internet:
Developed from the success of ARPAnet which provided reliable service even with partial failure and the distribution of BSD UNIX (an operating system allowing universities to access ARPAnet). Internet gained support with the birth of NSFNET (National Science Foundations linking of five universities) This would become ARPAnets backbone allowing interconnection of more networks.

NSF decomisions backbone in 1995 leaving the internet intact as a self-supporting industry.

Internet 2 is a very high performance Backbone Network Service (vBNS) and is being developed to support research and communication needs of Academic Institutions. 95 sites are linked by 12 regional gigabit Points of Presence (gigaPOPs).