if not your uw e-mail address, be sure to include your name (or even your uw netid) in the message ...

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


Connecting with NetworksFluency with Information Technology


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.


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


Basic Types of Networks


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)


LAN in the Lab

EtherNet is a popular LAN protocol▪ Recall, it’s a “party” protocol


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


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




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


http://vimeo.com/2696386

http://vimeo.com/2696386

Design Goals for the Internet

Diversity of systems in place


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 placeSolution: Accept the diversity


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


Internet Protocol


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


TurtleCobra

Crocodile

Squirrel

Echidna

Mole

Reptiles

Mammals

DNA

Hourglass Analogy


AOLComcast

ClearWire

UWUBC

UM

ISPs

University Networks

IP connects them all

Hourglass Analogy


??

?

?

?

?

?

?

?

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.



Diversity of systems in place Maintain communication in times of

disasters, breakdowns, etc.Solution: Postcard analogy


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


Tracing these Virtual Routes


You can find such “trace route” sites through GoogleYou 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 computer2012-04-02 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


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)


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


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

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

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"


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


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

For Wednesday

Check the calendar for due dates Read Chapters 5 & 6 Continue GoPosting


if not your uw e-mail address, be sure to include your name (or even your uw netid) in the message ...

Documents

internet slide

cse100 katherine deibel

katherine deibel info100

information technology2

information technology7

information technology4

information technology10

information technology1