Chapter 2 Accessing the Internet
Learning Objectives Describe how the last mile connects users to the Internet. Examine the difference between bandwidth, throughput, and latency. Explain the different hardware and software requirements for connecting to the Internet. Contrast the different types of wired and wireless Internet connection methods. Evaluate Internet Service Providers and determine best practices.
Chapter Focus Internet Infrastructure Bandwidth, Throughput, and Latency Hardware and Software Requirements for Connecting to the Internet Wired Internet Connections Wireless Internet Connections Choosing an Internet Service Provider
Internet Infrastructure The Last Mile The last portion of any telephone connection from a central office to an end user Most homes still have standard telephone service POTS – plain old telephone service Uses twisted-pair cables Usually slowest portion of Internet connection
Internet Infrastructure The Last Mile
Internet Infrastructure Internet Service Providers (ISPs) Provides Internet access and Web development and hosting Internet Access Providers (IAPs) Provides Internet access only Network access points (NAPs) ISPs and IAPs connect to an Internet backbone through an NAP Smaller ISPs and IAPs may connect first to larger ISPs and IAPs, who will in turn connect to an NAP
Internet Infrastructure The Internet Backbone High-speed lines that form the core network of the Internet First Internet backbones supported by ARPANET and later NSFnet Now supported by the private sector – a number of different companies Lines include T1, T3, OC-1, and OC-3 cables
Internet Infrastructure T1 cables Contain two twisted-pair cables Bandwidth of 1.5444 Mbps T3 cables Contain 28 T1 lines Bandwidth of 44.736 Mbps
Internet Infrastructure OC-1 and OC-3 cables OC – Optical Carrier Contains fiber-optic cable OC-1 Bandwidth of 51.84 Mbps OC-3 Bandwidth of 155.52 Mbps
Internet Infrastructure Twisted-pair cable
Internet Infrastructure Fiber-optic cable
Internet Infrastructure Review Why do the last mile and the hardware in a central office often present a stumbling block to fast and reliable Internet connections? What is the difference between an ISP and an IAP? How do fiber-optic cables work? What is a network access point (NAP)?
Bandwidth, Throughput, and Latency Expresses the theoretical maximum amount of data that an Internet connection can transmit in one second Internet bandwidth Measured in bits per second Expressed in decimal format
Bandwidth, Throughput, and Latency Relative Bandwidth Size
Bandwidth, Throughput, and Latency One bit (binary digit) A single digit – zero or one Kilobit 1,000 bits Megabit 1,000 kilobits Gigabit 1,000 megabits
Bandwidth, Throughput, and Latency Bandwidth Measurements bps – bits per second Kbps – kilobits per second File Size Measurements Byte – eight bits KB – kilobytes
Bandwidth, Throughput, and Latency Bandwidth Speeds Symmetrical Uploading or downloading are the same Asymmetrical Uploading and downloading speeds are different Usually more bandwidth for downloading compared to uploading
Bandwidth, Throughput, and Latency Measures actual transmission speed per second As opposed to bandwidth which measures theoretical rate Measures only useable data transmitted and does not include data used for network overhead
Bandwidth, Throughput, and Latency Time between transmission and reception of data across a network Usually measured in milliseconds (ms) Causes of latency Device delays Network congestion Long route necessary for satellite signal to travel between earth and outerspace Ping Program to measure latency
Bandwidth, Throughput, and Latency Review How do bandwidth, throughput, and latency differ from each other? What kind of Internet connection is most affected by high latency rates? How are bandwidth, file storage, and latency measured? What is the difference between symmetrical and asymetrical Internet connections?
Hardware and Software Requirements for Connecting to the Internet Hardware Requirements Computer Modem Cable for connecting the modem Specific requirements depends on the type of Internet connection that will be used
Hardware and Software Requirements for Connecting to the Internet Modem (modulator – demodulator) Originally named for purpose To convert digital computer data into analog data to be sent over an analog phone line, then on the receiving side, convert back to digital data Satellite modems Transmit data using radio waves Other types ISDN, xDSL, and cable modems Different modem types are not interchangeable
Hardware and Software Requirements for Connecting to the Internet Current computer operating system that will support TCP/IP Windows Vista, Linux, Mac OS, and others Web browser E-mail program
Hardware and Software Requirements for Connecting to the Internet Review How does a modem work? What kind of software is needed to connect to the Internet? What basic hardware requirements are necessary for connecting to the Internet?
Wired Internet Connections Includes any method that uses cable or wires to connect to the Internet Dial-up connections (POTS) ISDN xDSL Cable Leased lines Broadband over power line (BPL)
Wired Internet Connections Dial-up Internet Access (POTS) Bandwidth between 28.8 and 56 Kbps Referred to as narrowband Accelerated Internet Uses standard modems and POTS Employs compression and caching technologies to increase: Throughput Web page loading up to 5 times faster Reduce text and image file sizes
Wired Internet Connections Integrated Services Digital Network (ISDN) Integrates voice and data Multiple digital channels Users can talk on the phone and surf the Internet over a single telephone wire Bandwidth of 64 Kbps or 128 Kbps Distance-related Users must be located within 18,000 of central office (CO)
Wired Internet Connections Digital Subscriber Line (DSL) High-speed Internet service using POTS twisted-pair cable xDSL Represents different members of DSL services Asymmetric Digital Subscriber Line (ADSL) Most common DSL service Can carry simultaneous voice and data if splitter is installed Bandwidth up to 9 Mbps Always-on connection
Wired Internet Connections Discrete Multitone (DMT) Modulation
Wired Internet Connections Cable Utilizes coaxial cable used to provide cable television service to connect users to the Internet All cable Internet users share bandwidth with other users on the same channel Bandwidth depends on how many users are connected Always-on asymmetric Internet connection
Wired Internet Connections Leased Lines Dedicated line remains separate from the phone line Offers always-on symmetrical bandwidth with identical speeds for data uploads and downloads Most commonly leased lines are T1 and T3 lines Very large businesses may lease an optical carrier line such as an OC-3
Wired Internet Connections Broadband over power line (BPL) Delivers Internet data over electrical power lines and into homes Bandwidth 500 Kbps to 3 Mbps Limited availability in US, Canada, and Europe Future is uncertain
Wired Internet Connections Review Is there a fixed or agreed-upon definition for the term broadband Internet? What are the differences among the different types of DSL technologies? How does a cable modem Internet connection work? How does an accelerated Internet connection work?
Wireless Internet Connections Uses radio waves to connect computers equipped for wireless IEEE 802.11 most common series of specifications Commonly called Wi-Fi To operate wirelessly a computer must have: Wireless network interface card (NIC) Or adapter installed Or factory equipped with wireless technology
Wireless Internet Connections Security Open connection Allows anyone with a wireless NIC access to the connection Secure connection Connection can be made secure by using a 128-bit encryption system known as Wired Equivalency Privacy (WEP)
Wireless Internet Connections Fixed Wireless Service Broadcasts data in the form of microwave frequencies from a tower or series of towers Broadcasting range is up to 35 miles Line of sight technology Between 256 Kbps and 1 Mbps downloading Between 512 Kbps uploading
Wireless Internet Connections Wireless LAN (WLAN) To connect a computer or series of computers to an ADSL or cable modem to access the Internet Connection is to a transceiver known as a wireless access point Wireless equipment To provide wireless Internet access for a home or business Or to create a public hotspot
Wireless Internet Connections Cellular Phone Internet Access Work by dividing geographic regions into a grid of cells Users travel through one cell to another cell First generation (1G) were analog networks Wireless Application Protocol (WAP) Microbrowser designed for small screens found on hand-held devices such as PDAs Wireless Markup Language (WML) Used to develop pages to be shown in microbrowser
Wireless Internet Connections Satellite Internet Access Offers broadband Internet Popular in rural or remote areas Users need: Small dish Satellite modem Coaxial cable connection
Wireless Internet Connections Review How can a wireless local area network (WLAN) be connected to a wired Internet service? How does a satellite Internet connection work? What are some different methods that can be used to access the Internet using cellular service?
Choosing an Internet Service Provider The first step begins with a needs assessment Considerations Hours per week or month of usage needed Cost of disk storage if Web site hosting is needed E-mail addresses provided Ability to access account on the road Minimum hardware and software required Possibility of Online Service Provider (OSP) America Online (AOL) CompuServe Support service provided References
Choosing an Internet Service Provider Review What is the first thing you should do before evaluating what kind of Internet service is best for you? What is an OSP? How does an OSP differ from an ISP or IAP?