01:198:170 Chapter Notes - Chapter 3.2: Local Area Network, Digital Subscriber Line, Internet Service Provider
16 May 2018
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Far and Near: WAN and LAN
●Internet is collection of wide area networks (WANs)
AKA networks designed to send info
between 2 locations widely separated and not directly connected
○Ex: Tahiti and NYC we don’t expect a single airline fight. So each postcard takes a
sequence of connecting flights
●Computers close enough to be linked by a single cable or pair of wires, interconnection is local
area networks (LAN)
○Ethernet main tech for local area networks, and is appropriate for connecting all
computers in a lab or building
Ethernet, the Setup
●Wire, wire pair, or optical fiber, called the channel
, that winds past a set of computers
●Engineers "tap" the channel to connect a computer allowing it to send a signal. All computers
connected to channel can detect the signal, including sender. This, channel supports broadcast
communication
Ethernet, Party Analogy
●Talk until done, and next person talks, if 2 ppl at once, waits, and starts
Ethernet, the Protocol
●A computer sends signals on the channel. Pause indicates the end of the transmission when no
computer is sending signals and the channel is quiet. Computer wanting to transmit signal starts
and starts listening to the channel to detect what is being transmitted. If it’s the info the
computer sent, computer continues knowing it’s the one sending it and completes transmission.
If signals mixed in with another computer, it notices garbled msg and stops transmitting.
Everyone stops transmitting. Waits and starts again
Connecting Your Computer to the Internet
●2 basic methods:
○Connection vis Internet service provider (ISP)
○Connection provided by a campus or enterprise network
Connections by ISP
●ISP sell connection to the internet
○Ex: phone and cable companies
●How it works
○ISP company give us modem for house
○Modem converts the bits a computer outputs in a form that’s compatible with the
carrier
○Signals sent to the carrier's business and converted to a form suitable for the server that
connects to internet via internet gateway
●Digital Subscriber Line (DSL) and cable are 2 very common service providers
Enterprise Network Connections (LAN)
●School, business, or governmental unit
●Connect computers to form a local area network (LAN) or interconnected LANs using Ethernet
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Document Summary
Internet is collection of wide area networks (wans) aka networks designed to send info. Ex: tahiti and nyc we don"t expect a single airline fight. So each postcard takes a between 2 locations widely separated and not directly connected sequence of connecting flights. Computers close enough to be linked by a single cable or pair of wires, interconnection is local area networks (lan) Ethernet main tech for local area networks, and is appropriate for connecting all computers in a lab or building. Wire, wire pair, or optical fiber, called the channel , that winds past a set of computers. Engineers tap the channel to connect a computer allowing it to send a signal. All computers connected to channel can detect the signal, including sender. Talk until done, and next person talks, if 2 ppl at once, waits, and starts. A computer sends signals on the channel.
