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If not your UW e-mail address, be
sure to include your name (or even
your UW netID) in the message
Sign your e-mails with your name
(and preferably in English)
Also e-mail your TA to ensure we
reply promptly
2012-04-02
Katherine Deibel, Fluency in Information Technology
1
Now posted on the website
You can attend any TA’s office hours
My hours are
after class on Fridays
by appointment
when I’m in my office with the door open
2012-04-02
Katherine Deibel, Fluency in Information Technology
2
INFO100 and CSE100
Fluency with Information Technology
Katherine Deibel
Katherine Deibel
2012-04-02
Katherine Deibel, Fluency in Information Technology
3
Computers are useful alone, but are
better when connected (networked)
Access more information and software
than is stored locally
Help users to communicate, exchange
information…changing ideas about social
interaction
Perform other services—printing, Web,
email, texting, mobile, etc.
2012-04-02
Katherine Deibel, Fluency in Information Technology
4
Different networks depending on
distance between computers:
Local area network (LAN)
▪ Small area: room or building
▪ Either wired or wireless
Wide area networks (WAN)
▪ Large area: more than 1 km
▪ Fiber-optic, copper transmission lines, satellite
2012-04-02
Katherine Deibel, Fluency in Information Technology
5
Network Type
Differentiating Factors
Peer-to-Peer
• No computer running server software
Server-Based Networks
• Computer running server software
manages network traffic
Local Area Network (LAN)
• Limited geographical area
Wide Area Network (WAN)
•
•
•
•
Campus Network
• Buildings in close proximity
Metropolitan Area Network
(MAN)
• Clusters of buildings in close proximity
separated from other clusters
• Third-party service provider
2012-04-02
Across town or across the globe
Third-party service provider
More bandwidth = more expense
Connects to LANs with a router
Katherine Deibel, Fluency in Information Technology
6
To communicate computers need to
know how to set up the data to be sent
and interpret the data received
Example protocols
EtherNet—for physical connection in a LAN
TCP/IP: transmission control protocol /
internet protocol (Internet)
HTTP: hypertext transfer protocol (Web)
2012-04-02
Katherine Deibel, Fluency in Information Technology
7
EtherNet is a popular LAN protocol
▪ Recall, it’s a “party” protocol
Connection to
campus
network
infrastructure
PC
PC
Typical MGH or OUGL Lab
PC
PC
PC
PC
Ether Net
Cable
2012-04-02
Katherine Deibel, Fluency in Information Technology
8
The campus subnetworks interconnect
computers of the UW domain which
connects to Internet via a gateway
washington.edu
MGH
Homer
Internet
Dante
Student
CS
Gateway
All communication by TCP/IP
2012-04-02
Katherine Deibel, Fluency in Information Technology
9
Transfer Control Protocol / Internet Protocol
The primary protocol for data transmission
on the Internet
Video: Warriors of the Net
http://www.youtube.com/watch?v=PBWhzz_Gn10
Linked to on the Calendar page
2012-04-02
Katherine Deibel, Fluency in Information Technology
10
Again, a video: History of the Internet
http://vimeo.com/2696386
The basic story:
Computer systems at multiple locations
Desire to share data and eliminate
duplicate work
Two major design challenges
2012-04-02
Katherine Deibel, Fluency in Information Technology
11
Diversity of systems in place
Site B:
Morse Code
Site A:
Pig Latin
Not feasible to rebuild
every site with the same
type of connectivity
Site C:
Uses carrier
pigeons
2012-04-02
Katherine Deibel, Fluency in Information Technology
12
Diversity of systems in place
Solution: Accept the diversity
Site B:
Morse Code
Site A:
Pig Latin
Site C:
Uses carrier
pigeons
2012-04-02
Katherine Deibel, Fluency in Information Technology
13
Within a local network, any protocol
is allowed
To send messages outside a local
network, it must be converted into
the IP protocol
2012-04-02
Katherine Deibel, Fluency in Information Technology
14
Network A convert Pig Latin
into IP Packets and sends
out on Internet
A
Pig Latin
B
IP
IP
IP
IP
Morse
Code
Network B converts IP
into Morse Code
2012-04-02
Katherine Deibel, Fluency in Information Technology
15
Turtle
Cobra
Reptiles
Crocodile
DNA
Echidna
Squirrel
Mole
2012-04-02
Mammals
Katherine Deibel, Fluency in Information Technology
16
AOL
Comcast
ISPs
ClearWire
IP connects them all
UBC
UW
UM
2012-04-02
University
Networks
Katherine Deibel, Fluency in Information Technology
17
?
?
?
?
?
Talk with your neighbor
for a minute and come
up with other examples
of hourglass analogies.
?
?
?
2012-04-02
?
Katherine Deibel, Fluency in Information Technology
18
Diversity of systems in place
Maintain communication in times of
disasters, breakdowns, etc.
2012-04-02
Katherine Deibel, Fluency in Information Technology
19
Diversity of systems in place
Maintain communication in times of
disasters, breakdowns, etc.
Solution: Postcard analogy
2012-04-02
Katherine Deibel, Fluency in Information Technology
20
Break messages into parts
Send each message separately
Delivery:
Each card moves forward to a server
that knows how to get to the destination
Cards can take multiple paths
Cards arrive out of order
2012-04-02
Katherine Deibel, Fluency in Information Technology
21
tracert 128.227.205.2
You can find such “trace route” sites through Google
2012-04-02
Katherine Deibel, Fluency in Information Technology
22
People give computers domain names
Hierarchical scheme
Domains begin with a “dot” and get “larger”
going right
▪ .edu
All educational computers, a TLD
▪ .washington.edu
All computers at UW
▪ dante.washington.edu A UW computer
▪ .ischool.washington.edu
iSchool computers
▪ .cs.washington.edu CSE computers
▪ june.cs.washington.edu
2012-04-02
A CSE computer
Katherine Deibel, Fluency in Information Technology
23
Computers are named by IP address,
four numbers in the range 0-255
▪ cse.washington.edu: 128.95.1.4
▪ ischool.washington.edu: 128.208.100.150
Remembering IP addresses would be
brutal for humans, so we use domains
Computers find the IP address for a
domain name from the Domain Name
System—an IP address-book computer
2012-04-02
Katherine Deibel, Fluency in Information Technology
24
.edu .com .mil .gov .org .net domains
are “top level domains” for the US
Recently, new TLD names added
Each country has a top level domain name:
▪ .ca (Canada)
▪ .es (Spain)
▪ .de (Germany)
▪ .au (Australia)
▪ .at (Austria)
▪ .us (US)
2012-04-02
Katherine Deibel, Fluency in Information Technology
25
View the Internet in two ways:
Humans see a hierarchy of domains relating
computers—logical network
Computers see groups of four number IP
addresses—physical network
Both are ideal for the “user's” needs
The Domain Name System (DNS)
relates the logical network to the
physical network by translating
domains to IP addresses
2012-04-02
Katherine Deibel, Fluency in Information Technology
26
Many people misuse the terms “Internet”
and “World Wide Web”
Let’s get them right
Internet:
All of the wires, fibers, switches, routers etc.
connecting named computers
World Wide Web:
That part of the Internet that stores and serves
Web pages—web servers, client computers
2012-04-02
Katherine Deibel, Fluency in Information Technology
27
The terms "internet" and "Internet"
refer to different things
"Internet" is the complete collection of
internetworked computers
"internet" refers to any collection of
networked computers
Most of the time, you probably mean
the "Internet"
2012-04-02
Katherine Deibel, Fluency in Information Technology
28
Networking is changing the world
Internet: named computers using TCP/IP
WWW: servers providing Web pages
Principles
▪ Logical network of domain names
▪ Physical network of IP addresses
▪ Protocols rule: LAN, TCP/IP, http...
▪ Domain Name System connects the two
▪ Client/Server, fleeting relationship on WWW
2012-04-02
Katherine Deibel, Fluency in Information Technology
29
Net neutrality
SOPA
Digital divide
Government control of Internet access
Web 2.0
VPNs
Wireless pirating
Etc.
These topics could be interesting
fodder for GoPost discussions
2012-04-02
Katherine Deibel, Fluency in Information Technology
30
Check the calendar for due dates
Read Chapters 5 & 6
Continue GoPosting
2012-04-02
Katherine Deibel, Fluency in Information Technology
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