The Internet and The Internet and ApplicationsApplications

Unit 8, Chapter 15 & 16

Objectives

Compare TCP and UDP.Identify the uses of multicasting.Describe how TCP controls congestion on a network.Identify the TCP port numbers that are regularly used in communication systems.Describe the functions of an ISP.Explain the differences between an intranet and an extranet and how they relate to the Internet.Describe how the early Internet or ARPNET differs from the modern Internet.Discuss the three components that make up the World Wide Web.Describe some of the most common Internet and Web applications.

History of The Internet

1957 – Advanced Research Projects Agency Formed1962 – Intergalactic Computer Network paper written by J.C.R. Licklider, first director of DARPA– Principle was anyone could access data anywhere

1960’s – Information Flow in Large Communication Nets paper written by Leonard Kleinrock– Discussed concept of packet switching instead of

circuit switching to send data

History of The Internet -ARPANET

1965 – 2 computers share data for the first time over low speed dial up telephone network. 1969 – Success of the data sharing allowed the development of a plan for the ARPANET which has as a goal to connect all time-sharing computers.– December 1969 – 4 separate nodes had been

connected via telephone lines, ARPANET was born

History of The Internet – 1970’s

Alohanet created – first wireless network connection. Used at the University of Hawaii.Arpanet and Alohanet connected together in 1972First commercial version of Arpanet offered, Telenet.Email developed to send text messages between domainsMany problem with incompatibility between collections of packet-switching networks. TCP/TP was born.Ethernet developed to handle issues with communications, collisions and retransmissions1975 – Altair 8800 first personal computer, $495 1979 - Usenet groups are developed and able to transfer files

History of The Internet – 1980’s

IBM Markets the personal computer in 19811982 Department of Defense declares TCP/IP as the standard for connecting networksNovell Netware offered in 1983 (XNS)January 1, 1983 All ARPANET hosts transition to TCP/IP from NCPDomain names are created to identify the type of institution on the network (edu,gov,mil,com,org,net)1989 ARPANET was decommissionedDue to the release of a worm on the Internet, Computer Emergency Response Team (CERT) was created to facilitate response to computer security threats

History of The Internet – 1990’s

1991 World Wide Web program created to make information available to allWorld Wide Web program had 3 major components– Universal Record Locator, address of which the first part tells the

program to use www=world wide web, ftp = file transfer protocol– Hypertext Transfer Protocol (HTTP) is the client/server protocol that

allows text and graphics to be transmitted via TCP/IP. Pages look the same no matter what system is used.

– Hypertext Markup Language is used to create HTTP World Wide Web pages

1993 Mosaic developed – first graphical interface browserNetscape followed shortly after, based on MosaicInternet Explorer release by Microsoft

The Internet

Very Large High Speed Backbones are funded by the governmentOther Backbones are provided by large companies that connect various sites around the country and worldInternet Society (ISOC)– Focuses on standards, public policy, education and training

Internet Engineering Task Force(IETF)– Concerned with evolution of the Internet

Internet Architecture Board (IAB)– Technical advisory for the ISOC and a committee of the IETF

Internet Research Task Force (IRTF)– Promote research of importance to the evolution of the Internet

Internet Engineering Steering Committee(IESG)– Executive committee of the IETF

World Wide Web Consortium (W3C)– Developing standards for the World Wide Web

Connection To The Internet

Access Hardware– Physical Connection to the Internet requires hardware

• Analog modem, cable modem, DSL modem, ISDN Terminal Adapter

Final Mile– Delivery Technology – How data are transmitted over the last

connect from the ISP to the home or business– Deliver Channel – Pipeline used to carry data from home or

business to ISP

Internet Service Provider – Provides the gateway to the Internet, there is a monthly feeInternet Backbone – Very High Bandwidth Network run by large companies and organizations

Connection To The Internet

International connections are through satellite or underwater cablesRouters connect ISPs to dedicated T-1 or T-3 (1.44 to 54Mbps) connectivity to larger backbones which in turn would connect into larger backbones ( Network Access Points)Network Access Points (NAPs) where traffic is exchanged usually tier 1 or tier 2 of the InternetMetropolitan Area Exchanges are the largest NAPS and there are 3 in the US (MAE East in DC, MAE West in San Francisco and MAE central in Dallas)Path is individual user, local ISP, regional ISP to National ISP and sometimes International access carriers

Types of Connections

Dial-up Networking (DUN)Integrated Services Digital Networking (ISDN)Digital Subscriber Line (DSL)Cable AccessWeb TVWireless & Satellite

Types of Connections Dial-up

Most are at 56KbpsRequires modemISP Point of Presence – local connectivity to eliminate long distance chargesProtocols used are either– Serial Line Interface Protocol (SLIP)– Point-to-point Protocol (PPP)

• PPP is the better more versatile protocol• Has error detection and authentication

Types of Connections ISDN

Not used much anymoreRequires terminal adapter or ISDN modem2 Flavors– Basic Rate Interface(BRI)

• 2- 64Kbs data channels and 1 16Kbps signaling channel• Can send data and talk by using each channel separately

– Primary Rate Interface(PRI)• Very expensive• 23 – 64Kbs data channels and 1 – 64Kbps signaling channel• Can integrate Internet, voice, and fax services

Types of Connections DSLInexpensive high speed option (1.5 Mpbs to 55 Mbps)Distance from switching office will determine true speed of this serviceRequires a DSL modemData is sent and received digitallyCan use voice and data at same time, normally connected to a FAX lineFlavors– Asymmetric DSL

• Upstream speed is 64Kbps to 1.54Mbps• Downstream speed is 256Kbps to 9Mbps

– Symmetric DSL• Upload and download speeds are the same up to 2.3 Mbps

– Very High Rate DSL• Used by businesses• Requires close proximity to switches• Top speeds of 52Mbps

Types of Connections Cable

Inexpensive high speed option (1.5 Mpbs)Cable was not originally installed with 2 way communications in mindRequires a splitter Normally upload and download speeds are different with download being around 300KbpsBroadband Technology, all signals (channels) on the same cable at the same timeArea being served is divided into nodes, about 500 home to a node

Types of Connections WebTV

Ability to use TV as a Web BrowserHook up for printers and keyboardsWork through local points of presenceConnects to WebTV network, a VPN

Types of Connections Wireless & Satellite

Mobile Wireless – Personal Digital Assistant (PDA)data access and can tether device to your computer

Bandwidth is about 9.6KbpsFixed Wireless – Line of site Internet providers bandwidth 2.5 to 2.7Ghz– Interference is a problem and access to communications

Bluetooth – normally used to connect a device to a computer with access to the Internet. Caution when using Bluetooth. The signal can be intercepted more than a mile awaySatellite – Uses satellites to access network. Problems with satellites are latency for signal transmission and reception and also interference.

Network Address Translation NAT)

Used to conceal the true identity of the device on your network from the InternetUse internal network addresses such as a 10.n.n.n address.Router will have an outside IP address that is known to the InternetWhen you talk to the Internet, the router takes note of your IP address and substitutes its in the network packet and sends it to the InternetWhen a packet arrives from the Internet, the router inspects it and looks in its internal tables to see where the packet is to be delivered or to what internal IP address

World Wide Web

World Wide Web program had 3 major components– Universal Record Locator, address of which the first

part tells the program to use www=world wide web, ftp = file transfer protocol

– Hypertext Transfer Protocol (HTTP) is the client/server protocol that allows text and graphics to be transmitted via TCP/IP. Pages look the same no matter what system is used. Daemon program on server waits for requests

– Hypertext Markup Language is used to create HTTP World Wide Web pages

Client – Server Computing

Basic Sequence – Server application starts and waits for request– Client specifies server location and requests communication– Client and Server exchange communications– Client and Server terminate communications

Common Gateway Interface – connection to a database and allows web content to be dynamicWell-Known Ports– 21 FTP – 23 Telnet– 25 SMTP– 37 Time– 80 WWW

Browsers

Controller– Calls client or set of clients to retrieve documents from

its remote server

Interpreter– Displays document on the screen by translating HTML

Cache– Storage of a document in memory or on disk for reuse

HTML Web Pages (Page 456)

Hypertext Markup Language is the primary language used for web pagesPages Contain– Header – one of 2 primary parts to a web page. Contains

particular information about the document– Body – second primary part to a web page. Holds the data

for the web page– Tag – Commands that define the way text or layout should

appear. Surrounded by < and > signs must be paired, end tag will have a / after < sign. Example

<HEAD> </HEAD>– Hyperlink Tags – Start with <A HREF> and end with </A>

allow you to jump to another page

HTML Web Pages (Page 456)

Pages Contain– IMG Tag – allow graphics to be used using graphics

interchange format (GIF) or joint photographic experts group format (JPG)

– Cascading Style Sheets (CSS) – allow other content to be embedded in a web page such as streaming video

Extensible Markup Language (XML) – Web page formatting language. This language is not concerned with format for page presentation but is used for the organization of data on a web page

EMAIL

Started with simple text sending on ARPANETClient-Server architectureClients such as Eudora, Outlook, Yahoo , MSNClients organize and display email information and send and attach documents to emailsMultipurpose Internet Mail Extensions (MIME) developed to encode and send text and files across the InternetEmail Server – manages message stores and user information. Example ExchangeSimple Mail Transfer Protocol (SMTP) is the protocol for email traffic, port 25Email exchange example, See page 461 and 462

Other Internet Applications/Terms

Mailing Lists – broadcast list of people to receive a particular email topicListserv – (ARPANET days) Everyone on the list of recipients for this list server receives a copyDistribution Lists – groups of people to receive a particular email topicBroadcast Message – message that is sent to all people known to this server

Other Internet Applications/Terms

Newsgroups – continuous public, electronic discussion forum– Moderated – postings are reviewed before released– Non-moderated – postings are made available as soon as they are

posted– Thread – conversation that is going on and can be read and posted to

Internet Relay Chat (IRC) – Use handles to communicate to others on-line. Messages are sent client to client through servers and groups can be involved in the discussionInstant Messaging (IM) – Similar to IRC but can be between 2 people. Client logs into server and communicates with another IM client through the server

Voice Over IP (VOIP)

Telephony over IP-based networksSeveral Methods to use – Client software on you computer which allows you to

“call” someone using the software over the Internet. Could be to another user with the same setup or outside of this system (analog phone).

– Using an analog telephone which is then translated into digital form and hauled over the carriers network and translated back to analog on the other side

– Implementation of a VOIP telephone system which all phones communicate over the network. Outgoing calls are handed off to the carrier to handle.

Voice Over IP (VOIP)

Must have plenty of bandwidthMust be able to prioritize VOIP trafficMust be concerned about security both of the data (voice) being transmitted and the software used to implement VOIPReduction of long distant chargesMuch more functionality, software clients and integration with email

Internet Tools

File Transfer Protocol (FTP) – Used to move files across the internet. Requires client and server software to be running. Secure FTP should be used to protect data and you should avoid using anonymous FTPArchie – Older tools, index of anonymous FTP sites. Not use much anymoreGopher – Original browser tool and was text based, Not use much anymoreTelnet – Terminal-remote host protocol used to connect to another machine. This is a terminal emulation program and use a virtual display and keyboard.

Search Tools

All provide 3 basic tasks– Searching the Internet based on key words or phrases– Indexing key words and their locations (URL)– Providing links to those URLs

Search engine is an indexed database of websites. Spiders crawl through web sites building these lists. Meta data tags are important in generating good information on a pageMetasearch Engines are tools that search many search engines are one time. Ex. www.metacrawler.comSubject Directories – Commercial tools or portals like Yahoo! or About.com built by human selectionGateway pages – links to pages that have resource related to a specific topic

Review Questions

1. CERT was created after the Morris worm infected 10 percent of the Internet's online hosts in 1989.a. Trueb. False

Review Questions

2. Bandwidth options to connect to the Internet include _______ and _______.a. ISDNb. DSLc. Satellite Radiod. TV

Review Questions

3. The _____ _____ _____ is the wealth of information attached to the Internet and accessible because of its three major components: URL, HTTP, and HTML.a. countryb. webc. wided. conversation

Review Questions

4. The main disadvantage of VoIP has been latency, which causes poor voice quality.a. Trueb. False

Review Questions

5. The “killer ap” of internetworking since its earliest days was _____________.a. FTPb. e-mailc. instant messagingd. inquiry of customer’s sales records

Review Questions

6. J.C.R. Licklider’s contribution to internetworking was important because ______.a. his ideas inspired later developmentsb. he created the first RFCc. his inventions were the basis for Ethernetd. his money funded computer research

Review Questions

7. The thousands of databases on the Internet that cannot be located by search engines are collectively called ______________.a. subject directoriesb. portalsc. the hidden Webd. the invisible Web

Review Questions

8. When a URL does not contain a filename after the slash mark, the Web server automatically delivers the default file, which is most often called __________.a. mypage.htmlb. index.htmlc. index.comd. www.html

Review Questions

9. Extensible markup language (XHTML) is ________________.a. being replaced by XMLb. made obsolete by HTMLc. a hybrid of XML and HTMLd. unrelated to XML and HTML

Review Questions

10. An organization that charges a fee to connect subscribers to its own Internetconnected servers, providing a gateway to the Internet, is called ___________.a. a common carrierb. a telephone companyc. a packet carrierd. an ISP

Homework

Assignment: Due Next Week– Review:

• Chapter 15, pp. 416-445• Chapter 16, pp. 450-480

– Read:• Chapter 17, pp. 488-515• Chapter 19, pp. 544-573

– Complete:* Multiple Choice Questions 1-10 on pp. 481-483