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Announcements
Clicker registration is linked on the Calendar page
Regarding e-mails 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)
Be sure that you are contacting me: [email protected]
2012-01-11 Katherine Deibel, Fluency in Information Technology 1
Announcements
0.5 extra credit I worked longer on this lecture due to
its importance
2012-01-11 Katherine Deibel, Fluency in Information Technology 2
Announcements
If you recently registered and You did not attend labs last week
You contacted me about late turnins for Lab 1 and the GoPost biographies
E-mail me your UW netID and a reminder that you registered late
2012-01-11 Katherine Deibel, Fluency in Information Technology 3
Two New Things
First optional reading will be posted by tomorrow noon The Digital Divide
First “IT in Short Focus” talk on Friday Short (2-3 minute) presentation about an
topic related to the social side of IT
Topic: Clippy and digital assistants
2012-01-11 Katherine Deibel, Fluency in Information Technology 4
Office Hours
Now posted on the website You can attend any TA’s office hours My hours are
after class on Wednesdays
by appointment
when I’m in my office with the door open
2012-01-11 Katherine Deibel, Fluency in Information Technology 5
Connecting with NetworksFluency with Information Technology
2012-01-11 Katherine Deibel, Fluency in Information Technology 6
Katherine Deibel
INFO100 and CSE100
Katherine Deibel
Networks...
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.
2012-01-11 Katherine Deibel, Fluency in Information Technology 7
Network Structure
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
2012-01-11 Katherine Deibel, Fluency in Information Technology 8
Basic Types of Networks
2012-01-11 Katherine Deibel, Fluency in Information Technology 9
Network Type Differentiating FactorsPeer-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) • Across town or across the globe• Third-party service provider• More bandwidth = more expense• Connects to LANs with a router
Campus Network • Buildings in close proximity
Metropolitan Area Network (MAN)
• Clusters of buildings in close proximity separated from other clusters
• Third-party service provider
Protocols
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)
2012-01-11 Katherine Deibel, Fluency in Information Technology 10
LAN in the Lab
EtherNet is a popular LAN protocol▪ Recall, it’s a “party” protocol
2012-01-11 Katherine Deibel, Fluency in Information Technology 11
Connection to campus network infrastructure
PC PC PC PC PC PCEther Net Cable
Typical MGH or OUGL Lab
Campus & The World
The campus subnetworks interconnect computers of the UW domain which connects to Internet via a gateway
2012-01-11 Katherine Deibel, Fluency in Information Technology 12
All communication by TCP/IP All communication by TCP/IP
Homer
Dante
Student CS
MGH
Gateway
washington.edu
Internet
What is TCP/IP
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
2012-01-11 Katherine Deibel, Fluency in Information Technology 13
History of the Internet
Again, a video: History of the Internethttp://vimeo.com/2696386
The basic story: Computer systems at multiple locations
Desire to share data and eliminate duplicate work
Two major design challenges
2012-01-11 Katherine Deibel, Fluency in Information Technology 14
Design Goals for the Internet
Diversity of systems in place
2012-01-11 Katherine Deibel, Fluency in Information Technology 15
Site C:Uses carrier pigeons
Site B:Morse Code
Site A:Pig Latin
Not feasible to rebuild every site with the same
type of connectivity
Design Goals for the Internet
Diversity of systems in placeSolution: Accept the diversity
2012-01-11 Katherine Deibel, Fluency in Information Technology 16
Site C:Uses carrier pigeons
Site B:Morse Code
Site A:Pig Latin
Internet Protocol
Within a local network, any protocol is allowed
To send messages outside a local network, it must be converted into the IP protocol
2012-01-11 Katherine Deibel, Fluency in Information Technology 17
Internet Protocol
2012-01-11 Katherine Deibel, Fluency in Information Technology 18
A
Pig Latin
Network A convert Pig Latin into IP Packets and sends out on Internet
IP
B
Network B converts IP into Morse Code
Morse Code
IP IP IP
Hourglass Analogy
2012-01-11 Katherine Deibel, Fluency in Information Technology 19
TurtleCobra
Crocodile
Squirrel
Echidna
Mole
Reptiles
Mammals
DNA
Hourglass Analogy
2012-01-11 Katherine Deibel, Fluency in Information Technology 20
AOLComcast
ClearWire
UWUBC
UM
ISPs
University Networks
IP connects them all
Hourglass Analogy
2012-01-11 Katherine Deibel, Fluency in Information Technology 21
??
?
?
?
?
?
?
?
Talk with your neighbor for a minute and come up with other examples of hourglass analogies.
Design Goals for the Internet
Diversity of systems in place Maintain communication in times of
disasters, breakdowns, etc.
2012-01-11 Katherine Deibel, Fluency in Information Technology 22
Design Goals for the Internet
Diversity of systems in place Maintain communication in times of
disasters, breakdowns, etc.Solution: Postcard analogy
2012-01-11 Katherine Deibel, Fluency in Information Technology 23
Postcard Analogy
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
2012-01-11 Katherine Deibel, Fluency in Information Technology 24
Tracing these Virtual Routes
2012-01-11 Katherine Deibel, Fluency in Information Technology 25
You can find such “trace route” facilities by Googling, and then type in the IP-Addresses around the world
You can find such “trace route” facilities by Googling, and then type in the IP-Addresses around the world
tracert 128.227.205.2
Naming Computers—Take 1
People give computers domain names Hierarchical sheme
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 A CSE computer2012-01-11 Katherine Deibel, Fluency in Information Technology 26
Domains begin with a “dot” and get “larger” going rightDomains begin with a “dot” and get “larger” going right
Naming Computers—Take 2
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
2012-01-11 Katherine Deibel, Fluency in Information Technology 27
Top-Level Domains (TLDs)
.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)
2012-01-11 Katherine Deibel, Fluency in Information Technology 28
Logical vs Physical
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
2012-01-11 Katherine Deibel, Fluency in Information Technology 29
Internet vs World Wide Web
Many people misuse the terms “Internet” and “World Wide Web”
Let’s get them right
2012-01-11 Katherine Deibel, Fluency in Information Technology 30
Internet:
All of the wires, fibers, switches, routers etc. connecting named computers
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
World Wide Web:
That part of the Internet that stores and serves Web pages—web servers, client computers
Summary
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
2012-01-11 Katherine Deibel, Fluency in Information Technology 31
What we did not cover
Net neutrality SOPA Digital divide Government control of Internet access Web 2.0 VPNs Wireless pirating Etc.
2012-01-11 Katherine Deibel, Fluency in Information Technology 32
These topics could be interesting fodder for GoPost threads for this chapter… hint hint hint