Transcript Intro to the AS/400 - Florida State College

Intro to Info Tech
Networks
This presentation can be viewed on line at:
http://web.fscj.edu/janson/cgs1060/wk10.Networks.ppt
Copyright 2003
by Janson Industries
1
Objectives

Explain
 Components
 Type
of a network
of networks
 Network
providers
2
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Networks


Enable communication
Don't have to be computer
networks
Phone
TV
Radio
Cable
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Networks


The Rothchild's network
Today, high frequency traders
rely on getting trade
information before others
 So
they can go to other
exchanges and make trades
based on the info
 Called
front running
 Ie.
short a stock if you know the
price is going to go down
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4
Networks

How much sooner do they
need the information
 All
they need is a 500
microsecond (ms) advantage
 What's
a ms: one millionth of a
second
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Networks

1,000,000 ms (1 second)
 Time
for a single human heartbeat
at rest

100,000 ms


One fast blink of a human eye
1000 ms
 One
beat of a tsetse fly’s wings
 150 separate trades of a stock can
occur
6
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Networks

How do/did the high freq traders
get the advantage
 Building
faster networks
 Squeezing
out nanosecond (billionth
of a second) improvements
 Pay
to place their computers
closer to the stock exchanges
 Pay
banks/funds to execute their
stock trades (called a rebate for
order flow)
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Networks


Estimated that they made
$160,000,000 a day
If you're interested in more info,
great article based on the book
"Flash Boys: A Wall Street
Revolt"
 http://www.nytimes.com/2014/04/
06/magazine/flash-boys-michaellewis.html?hp&_r=0
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Networks

Modern networks all have
 Some
device(s) /node(s) that
humans interact with that
 Either
receives and/or sends
 Some
device(s) to manage/direct
the communication
 Some
transmission medium
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Computer Networks

Communication does not have to
be between people
 EDI
(electronic data interchange)
 Download

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files
When it does, a "computer" acts
as the human interface device
 GPS
device
 PDA
(Palm, Blackberry)
 Smart
Phone
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Network Classifications

Amount of area covered

Architecture

Topology

Wireless vs. physical lines
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Networks

LAN – Local Area Network
 Limited
area
A
room, a home, a building, a small
group of bldgs
 Shared

resources – printer
MAN – Metropolitan Area Network
 High
speed network that connects
LANS
 Usually larger area
 Town,
 Ex.
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city, county
Comcast's cable based network
12
Networks

WAN – Wide Area Network
 Largest
 State,
geographic area
country, world
 Can
be a bunch of LANS/MANS tied
together
 The
 Or
Internet
can be a single high speed network
 Satellite
phone network
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Network Architectures

Client/Server
 Server
acts as network's storage
 Manages
 Web
 Can
the network resources
pages, data, pictures, music
have many different types
 Print
Server
 Application Server
 File Server
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Network Architectures

Peer to Peer
 Each
computer acts as a server
unique resources – files, printer
 Provides access for all other network
computer s
 Has

P2P (Internet Peer to Peer)
 Uses
the Internet to share resources
 S/W enables users to access other
currently logged on users computers
 BitTorrent,
Kazaa, LimeWire
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Network Topologies

"Shape" of the network
 Bus
 Single
line, bidirectional
 Node fails – no prob
 Ring
 Single
line, unidirectional
 Each device involved in routing
 Node fails, all nodes after unavailable
 Star
 Central
routing hub/switch
 Node fails – no prob
 Hub fails – network fails
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16
Network Media

Physical Lines
 Twisted
Pair
 Two
twisted copper wires
 Can have many in one cable
• Phone land lines
 Not
good for long distances
 Coaxial
Cable
 Single
shielded copper wire
 No noise
 Good for longer distances
• Cable company
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Network Media

Physical Lines
 Fiber
Optic
 Many
shielded glass/plastic lines
 Transmit
 Vs.
light
copper wires
• No interference from other electrical devices
• Smaller, lighter and faster
• More expensive and harder to install and
modify
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Network Media

Wireless
 Infrared
 Often
used by peripherals (wireless
mouse, keyboard, printer)
 Need
line of sight
 Broadcast
Radio
 Good
for broad area transmissions
 Wi-Fi,
Bluetooth
19
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Network Media

Wireless
 Cellular
 High
Radio
frequency radio waves
 Uses
network of towers to relay signal
 Popular
with mobile devices
 Microwave
 Ultrahigh
frequency radio waves
 Called
fixed wireless because
transmitted from dish to dish
 Line
of sight needed
• On top of buildings: Empire State Bldg
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20
Network Media

Wireless
How many satellites are there?
 Satellite
 Receives
transmissions from earth
based station
 Relays
to other earth based station
 Often microwave
 Vs.
terrestrial wireless
• Wide range – half the Earth
• Less interference
• Less real estate needed - no towers, relay
stations, wires, etc.
• Satellites are expensive
• Difficult to repair
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Network Providers

Do it yourself
 Lay
your copper wire
 Get a router
 Hotels,

schools, businesses
Common Carriers
 Regulated
by gov't
 Must provide access to anyone
 Phone

company, cable company
Value Added Network
 Provide
a service over common
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carrier line (1-800-Big-Date)
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Phone Company Services

Switched vs. Dedicated Lines
 Switched
uses standard telephone
lines
 Dedicated connects two points
 Provides
 Advs

constant connection
and Disadvs?
Dial up connection
 Use
the telephones switched network
 Temporary analog connection
 Problem: computers are digital
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 Need a modem
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Phone Company Services

ISDN (Integrated Services Digital
Network)
 Digital
over copper (faster than dial up)
 Need ISDN modem
 Distance limitation – 3.5 miles

DSL (Digital Subscriber Line)
 Digital
over copper (faster than ISDN)
 Need DSL modem and network card
 Distance limitation – 3.5 miles
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Phone Company Services

FTTH/FTTB –Fiber to the
Home/Business
 The
last quarter mile problem
 Very fast
 Distance limitation – 3.5 miles

T Lines (T1, T2, T3, etc.)
 High
speed lines
 Usually make up the backbone of a
network
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Network Equipment

With cable need cable modem

Wireless modem

Router
 Manages
transmissions over the
network
 Home routers enable multiple
computers to share Internet
connection
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Network Standards


Protocols dictate how two devices
communicate over the network
Network standards dictate h/w
 Connectors
 Medium
 Cabling
 Plug
types
 Speed
27
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Network Standards

Ethernet is most popular for LANS
 Easy
to install and cheap
 No central controlling device
 Two computers trying to send at same
time cause a "collision"

Token Ring
 Token
passes around network
 Only one token so only one computer
can communicate at a time
 No collisions
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Wireless Network Standards


WiFi (Wireless Fidelity) similar to
Ethernet for radio wave
communication
UWB (Ultra Wideband)
 Short
range, high speed, radio wave
communication
 Video

and image transfers
IrDA: infrared communications
 Must
be line of sight
29
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Wireless Network Standards

RFID: radio communication
between a reader and a tag
 Tag
consists of at least an antenna
and memory

Near Field Communication (NFC)
 AKA
A
Beaming
subset of RFID
 Dictates
how devices communicate
at short distances 4 cm (1½ inches)
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Wireless Network Standards

Sprint’s WiMAX (Worldwide
Interoperability for Microwave Access)
MW communication over a WAN
 Dictates
how devices talk to towers,
towers communicate to Internet or other
towers
 Like

WiFi with a bigger hotspot
Verizon’s LTE (Long Term Evolution)
 Same
as Sprint’s WiMAX: MW
communication over a WAN
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31
Protocols


TCP/IP dictates how Internet
communications work
Bluetooth how short range radio
communication work
 Include
non-computer devices like
 Headsets,

fax machines, cameras
WAP (Wireless Application
Protocol)
 How
smaller devices display Internet
resources
 Web
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page on a phone
 Email to blackberry
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Points to Remember



Communication networks require
both h/w and software
Standards dictate h/w, protocols
dictate s/w
Computer networks have at
least:
 User
node
 Medium
 Communication
management device
33
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