 Clicker registration is linked on the Calendar page  Regarding s  If not your UW address, be sure to include your name (or even your UW netID) in the message  Sign your s with your name (and preferably in English)  Be sure that you are contacting me: Katherine Deibel, Fluency in Information Technology1

 0.5 extra credit  I worked longer on this lecture due to its importance Katherine Deibel, Fluency in Information Technology2

 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 me your UW netID and a reminder that you registered late Katherine Deibel, Fluency in Information Technology3

 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 Katherine Deibel, Fluency in Information Technology4

 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 Katherine Deibel, Fluency in Information Technology5

Fluency with Information Technology Katherine Deibel, Fluency in Information Technology 6 Katherine Deibel INFO100 and CSE100 Katherine Deibel

 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, , texting, mobile, etc Katherine Deibel, Fluency in Information Technology7

 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 Katherine Deibel, Fluency in Information Technology8

Katherine Deibel, Fluency in Information Technology9 Network TypeDifferentiating Factors Peer-to-Peer No computer running server software Server-Based NetworksComputer 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 NetworkBuildings in close proximity Metropolitan Area Network (MAN) Clusters of buildings in close proximity separated from other clusters Third-party service provider

 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) Katherine Deibel, Fluency in Information Technology10

 EtherNet is a popular LAN protocol ▪ Recall, it’s a “party” protocol Katherine Deibel, Fluency in Information Technology11 Connection to campus network infrastructure PC Ether Net Cable Typical MGH or OUGL Lab

 The campus subnetworks interconnect computers of the UW domain which connects to Internet via a gateway Katherine Deibel, Fluency in Information Technology12 All communication by TCP/IP Homer Dante Student CS MGH Gateway washington.edu Internet

 Transfer Control Protocol / Internet Protocol  The primary protocol for data transmission on the Internet  Video: Warriors of the Net   Linked to on the Calendar page Katherine Deibel, Fluency in Information Technology13

 Again, a video: History of the Internet  The basic story:  Computer systems at multiple locations  Desire to share data and eliminate duplicate work  Two major design challenges Katherine Deibel, Fluency in Information Technology14

 Diversity of systems in place Katherine Deibel, Fluency in Information Technology15 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

 Diversity of systems in place Solution: Accept the diversity Katherine Deibel, Fluency in Information Technology16 Site C: Uses carrier pigeons Site B: Morse Code Site A: Pig Latin

 Within a local network, any protocol is allowed  To send messages outside a local network, it must be converted into the IP protocol Katherine Deibel, Fluency in Information Technology17

Katherine Deibel, Fluency in Information Technology18 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

Katherine Deibel, Fluency in Information Technology19 Turtle Cobra Crocodile Squirrel Echidna Mole Reptiles Mammals DNA

Katherine Deibel, Fluency in Information Technology20 AOL Comcast ClearWire UW UBC UM ISPs University Networks IP connects them all

Katherine Deibel, Fluency in Information Technology21 ? ? ? ? ? ? ? ? ? Talk with your neighbor for a minute and come up with other examples of hourglass analogies.

 Diversity of systems in place  Maintain communication in times of disasters, breakdowns, etc Katherine Deibel, Fluency in Information Technology22

 Diversity of systems in place  Maintain communication in times of disasters, breakdowns, etc. Solution: Postcard analogy Katherine Deibel, Fluency in Information Technology23

 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 Katherine Deibel, Fluency in Information Technology24

Katherine Deibel, Fluency in Information Technology25 You can find such “trace route” facilities by Googling, and then type in the IP-Addresses around the world tracert

 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 computer Katherine Deibel, Fluency in Information Technology26 Domains begin with a “dot” and get “larger” going right

 Computers are named by IP address, four numbers in the range ▪ cse.washington.edu: ▪ ischool.washington.edu:  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 Katherine Deibel, Fluency in Information Technology27

.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) Katherine Deibel, Fluency in Information Technology28

 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 Katherine Deibel, Fluency in Information Technology29

 Many people misuse the terms “Internet” and “World Wide Web”  Let’s get them right Katherine Deibel, Fluency in Information Technology30 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

 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 Katherine Deibel, Fluency in Information Technology31

 Net neutrality  SOPA  Digital divide  Government control of Internet access  Web 2.0  VPNs  Wireless pirating  Etc Katherine Deibel, Fluency in Information Technology32 These topics could be interesting fodder for GoPost threads for this chapter… hint hint hint

 Check the calendar for due dates  Read Chapter 4  Lab 2 is due on Thursday by 10pm  Continue GoPosting Katherine Deibel, Fluency in Information Technology33