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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
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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 Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
INFO100 and CSE100 Fluency with Information Technology Connecting with Networks Katherine Deibel Katherine Deibel Katherine Deibel, Fluency in Information Technology
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. Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
Basic Types of Networks Katherine Deibel, Fluency in Information Technology
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) Katherine Deibel, Fluency in Information Technology
LAN in the Lab • EtherNet is a popular LAN protocol • Recall, it’s a “party” protocol Connection to campus network infrastructure Typical MGH or OUGL Lab PC PC PC PC PC PC Ether Net Cable Katherine Deibel, Fluency in Information Technology
Campus & The World • The campus subnetworks interconnect computers of the UW domain which connects to Internet via a gateway washington.edu Internet MGH Homer Dante Student Gateway CS All communication by TCP/IP Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
Design Goals for the Internet • Diversity of systems in place Site B: Morse Code Not feasible to rebuild every site with the same type of connectivity Site A: Pig Latin Site C: Uses carrier pigeons Katherine Deibel, Fluency in Information Technology
Design Goals for the Internet • Diversity of systems in placeSolution: Accept the diversity Site B: Morse Code Site A: Pig Latin Site C: Uses carrier pigeons Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
Internet Protocol Network A convert Pig Latin into IP Packets and sends out on Internet A Pig Latin B Morse Code IP IP IP IP Network B converts IP into Morse Code Katherine Deibel, Fluency in Information Technology
Hourglass Analogy Reptiles Turtle Cobra Crocodile DNA Echidna Squirrel Mole Mammals Katherine Deibel, Fluency in Information Technology
Hourglass Analogy ISPs AOL Comcast ClearWire IP connects them all UBC University Networks UW UM Katherine Deibel, Fluency in Information Technology
Hourglass Analogy ? ? ? ? Talk with your neighbor for a minute and come up with other examples of hourglass analogies. ? ? ? ? ? Katherine Deibel, Fluency in Information Technology
Design Goals for the Internet • Diversity of systems in place • Maintain communication in times of disasters, breakdowns, etc. Katherine Deibel, Fluency in Information Technology
Design Goals for the Internet • Diversity of systems in place • Maintain communication in times of disasters, breakdowns, etc.Solution: Postcard analogy Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
Tracing these Virtual Routes tracert 128.227.205.2 You can find such “trace route” sites through Google Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
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) Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
Internet vs World Wide Web • 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 Katherine Deibel, Fluency in Information Technology
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" Katherine Deibel, Fluency in Information Technology
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 Katherine Deibel, Fluency in Information Technology
What we did not cover • 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 Katherine Deibel, Fluency in Information Technology
For Wednesday • Check the calendar for due dates • Read Chapters 5 & 6 • Continue GoPosting Katherine Deibel, Fluency in Information Technology