regarding e-mails
DESCRIPTION
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) Also e-mail your TA to ensure we reply promptly. Office Hours. Now posted on the website - PowerPoint PPT PresentationTRANSCRIPT
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)
Also e-mail your TA to ensure we reply promptly
2012-04-02 Katherine Deibel, Fluency in Information Technology 1
Office Hours 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
Connecting with NetworksFluency with Information Technology
2012-04-02 Katherine Deibel, Fluency in Information Technology 3
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.
2012-04-02 Katherine Deibel, Fluency in Information Technology 4
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
2012-04-02 Katherine Deibel, Fluency in Information Technology 5
Basic Types of Networks
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Network Type Differentiating FactorsPeer-to-Peer • No computer running server softwareServer-Based Networks • Computer running server software
manages network traffic
Local Area Network (LAN) • Limited geographical areaWide 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 proximityMetropolitan 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)
2012-04-02 Katherine Deibel, Fluency in Information Technology 7
LAN in the Lab EtherNet is a popular LAN protocol
▪ Recall, it’s a “party” protocol
2012-04-02 Katherine Deibel, Fluency in Information Technology 8
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
2012-04-02 Katherine Deibel, Fluency in Information Technology 9
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
2012-04-02 Katherine Deibel, Fluency in Information Technology 10
History of the Internet 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
Design Goals for the Internet Diversity of systems in place
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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 place
Solution: Accept the diversity
2012-04-02 Katherine Deibel, Fluency in Information Technology 13
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
2012-04-02 Katherine Deibel, Fluency in Information Technology 14
Internet Protocol
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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 CodeIP IP IP
Hourglass Analogy
2012-04-02 Katherine Deibel, Fluency in Information Technology 16
Turtle Cobra
Crocodile
SquirrelEchidna
Mole
Reptiles
Mammals
DNA
Hourglass Analogy
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AOL Comcast
ClearWire
UWUBC
UM
ISPs
University Networks
IP connects them all
Hourglass Analogy
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? ?
?
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?
?
?
?
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.
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Design Goals for the Internet Diversity of systems in place Maintain communication in times of
disasters, breakdowns, etc.Solution: Postcard analogy
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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
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Tracing these Virtual Routes
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You can find such “trace route” sites through Google
tracert 128.227.205.2
Naming Computers—Take 1 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 A CSE computer
2012-04-02 Katherine Deibel, Fluency in Information Technology 23
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
2012-04-02 Katherine Deibel, Fluency in Information Technology 24
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)
2012-04-02 Katherine Deibel, Fluency in Information Technology 25
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
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Internet vs World Wide Web Many people misuse the terms “Internet”
and “World Wide Web” Let’s get them right
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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
internet or Internet? 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
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
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What we did not cover Net neutrality SOPA Digital divide Government control of Internet access Web 2.0 VPNs Wireless pirating Etc.
2012-04-02 Katherine Deibel, Fluency in Information Technology 30
These topics could be interesting fodder for GoPost discussions
For Wednesday Check the calendar for due dates Read Chapters 5 & 6 Continue GoPosting
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