Computer Concepts 5th Edition Parsons/Oja Page 216 CHAPTER 5 Network Building Blocks Section A PARSONS/OJA Internet and LAN Technology

Computer Concepts 5th Edition Parsons/Oja Page 218 Section A Chapter 5 Network Building Blocks Transmitting Data: Is it easy to transmit data?  A communications network is a collection of computers and other devices that communicate to share data, hardware and software

Computer Concepts 5th Edition Parsons/Oja Page 219 Section A Chapter 5 Network Building Blocks What kind of coding process happens on a communication network?  Computers use several coding schemes based on binary digits  ASCII  EBCDIC  Unicode  Binary numbers

Computer Concepts 5th Edition Parsons/Oja Page 220 Section A Chapter 5 Network Building Blocks Exactly what is transmitted when I send a message?  When data is transmitted, it usually takes the form of an electromagnetic signal  On a communication network, your data may be converted into several different types of waves

Computer Concepts 5th Edition Parsons/Oja Page 220 Section A Chapter 5 Network Building Blocks Exactly what is transmitted when I send a message?

Computer Concepts 5th Edition Parsons/Oja Page 221 Section A Chapter 5 Network Building Blocks Network Links: How do signals travel over a network?  Data can travel from one network device to another over a cable or through the air  A communications channel is a physical path or a frequency for a signal frequency  Networks use different types of cables

Computer Concepts 5th Edition Parsons/Oja Page 221 Section A Chapter 5 Network Building Blocks How do signals travel over a network?  Today’s networks use twisted-pair cables  UTP (unshielded twisted pair)  STP (shielded twisted pair)  looks similar to telephone cable  has square plastic RJ-45 connector

Computer Concepts 5th Edition Parsons/Oja Page 221 Section A Chapter 5 Network Building Blocks How do signals travel over a network?  Another option is coaxial cable  resembles cable-TV cable  round, silver BNC connector

Computer Concepts 5th Edition Parsons/Oja Page Section A Chapter 5 Network Building Blocks How do signals travel over a network?  Fiber-optic cable is a bundle of extremely thin tubes of glass  Each optical fiber (tube) is thinner than a human hair  Consists of strong inner support wire, multiple strands of optical fiber and a tough outer cable  Transmit pulses of light  Data can also travel airways in form of RF signals sent and received by a transceiver

Computer Concepts 5th Edition Parsons/Oja Page 222 Section A Chapter 5 Network Building Blocks How do signals travel over a network?  Microwaves provide another option for transporting data  Radio and microwave transmissions are bent around the surface of the earth to reach towers  Communications satellites play an important part in long-distance communications  A transponder on the satellite receives the signal, amplifies it, and retransmits the signal back to a ground station

Computer Concepts 5th Edition Parsons/Oja Page 222 Section A Chapter 5 Network Building Blocks How do signals travel over a network?  Infrared light can also carry data signals, but for short distances with a clear line of sight  Best for transmitting between notebook computers and a printer, or between a PDA and a desktop computer  Laser light can also carry data signals, for a longer distance, but requires a clear line of sight  Experimental, but possibly may be useful for transmitting data between buildings

Computer Concepts 5th Edition Parsons/Oja Page 222 Section A Chapter 5 Network Building Blocks What’s bandwidth?  Bandwidth is the transmission capacity of a communications channel  High-bandwidth communications systems, such as cable TV, are sometimes referred to as broadband  Systems with less capacity, such as the telephone system, are referred to as narrowband  The bandwidth of a digital channel is usually measured in bits per second (bps)

Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks Network Devices: What kind of equipment populates data communications networks?  Each device that is connected to a network is referred to as a node  The term workstation usually refers to a personal computer connected to a local area network (LAN), it is also called a client  A modem is a device that converts signals from a computer into a signal that can travel over a wide area network

Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks What kind of equipment populates data communications networks?  A network interface card (NIC) is the key hardware component for connecting a computer to a local area network.  small circuit board that sends data to and from workstation to network  A server refers to any computer on a LAN or the Internet that contains the software to manage and process files for other network nodes

Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks What kind of equipment populates data communications networks?  A host computer usually refers to any computer that provides services to network users  A hub is a device that connects several nodes of a LAN  A router is a device that is connected to at least two networks and makes decisions about the best route for data  A gateway is a device that performs functions similar to a router  A repeater amplifies and regenerates signals so they can retain the strength to reach their destinations

Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks Network Addresses: How does data find its destination?  Every node on a network has an address  Every packet of data that travels over a network also has an address which helps to route a packet to its destination

Computer Concepts 5th Edition Parsons/Oja Page 224 Section A Chapter 5 Network Building Blocks Network Topology: Does a network require a certain configuration of nodes?  The layout of a network is referred to as its physical topology

Computer Concepts 5th Edition Parsons/Oja Page 224 Section A Chapter 5 Network Building Blocks Does a network require a certain configuration of nodes?  A real-world network can make use of more than one topology

Computer Concepts 5th Edition Parsons/Oja Page 225 Section A Chapter 5 Network Building Blocks Packet and Circuit Switching Technology: What’s a packet?  When you transmit data, it is broken up into small pieces called packets  A packet is a parcel of data that is sent across a network  Has the address of its sender  Has the address of the destination  Has some data  When they reach the destination, they are put back together into original form

Computer Concepts 5th Edition Parsons/Oja Page 226 Section A Chapter 5 Network Building Blocks Why not just send an entire message?  Engineers wanted a more robust communications link for computer networks  They devised packet switching in which a message was divided into several packets that can be routed independently to their destination to avoid out-of-service or congested links  Packet switching makes very efficient use of available bandwidth and provides a steady stream of data

Computer Concepts 5th Edition Parsons/Oja Page 226 Section A Chapter 5 Network Building Blocks Communications Protocols: What is a communications protocol?  Communications protocol refers to set of rules for transmitting data from one node to another  Protocols allow two devices to negotiate and agree on how data will be transmitted  Scripts for dial-up modem

Computer Concepts 5th Edition Parsons/Oja Page Section A Chapter 5 Network Building Blocks How does a protocol initiate a transmission?  Protocols establish communications through handshaking  The devices decide on how to coordinate its transmission  Synchronous protocols are synchronized by a signal called a clock when sending and receiving data  Asynchronous protocols require the transmitting computer to send a start bit, then data is sent, and a stop bit to mark the end of the data

Computer Concepts 5th Edition Parsons/Oja Page 227 Section A Chapter 5 Network Building Blocks Does data travel in both directions over the same channel?  Simplex – signal travels in only one direction  Half duplex – signal travels in both directions, but only one direction at a time  Full duplex – signal travels in both directions at the same time

Computer Concepts 5th Edition Parsons/Oja Page 227 Section A Chapter 5 Network Building Blocks How does a protocol make sure that data arrives without errors?  Computers use error-checking protocols to make ensure accurate delivery of data (such as over the Internet)  Parity bit – added to keep track of the number of 1s and 0s  Even parity protocol – requires number of 1s to be an even number

Computer Concepts 5th Edition Parsons/Oja Page 228 Section A Chapter 5 Network Building Blocks Network Classifications: How are networks classified?  Internetwork – a network composed of many smaller networks  Intranet – uses TCP/IP protocols but owned by a private business and does not typically allow remote access  Extranet – similar to intranet except that it allows remote password-protected access  WAN – (wide area network) covers a large geographical area and may consist of smaller networks

Computer Concepts 5th Edition Parsons/Oja Page 228 Section A Chapter 5 Network Building Blocks How are networks classified?  LAN (local area network) – typically covers a very limited geographical area  Wireless network – uses radio frequencies  HomeRF network – low-power wireless network for home use  HomePLC – uses building’s existing power line cables  HomePNA – uses existing telephone cables  Novell – LAN that uses Novell Netware

Computer Concepts 5th Edition Parsons/Oja Page 229 Section A Chapter 5 Network Building Blocks How are networks classified?  Ethernet – free for all

Computer Concepts 5th Edition Parsons/Oja Page 229 Section A Chapter 5 Network Building Blocks How are networks classified?  Token Ring – connects nodes in a physical star configuration, but passes data around a logical ring using a technology called a “token”.  Wait for your turn…

Computer Concepts 5th Edition Parsons/Oja Page 230 Section A Chapter 5 Network Building Blocks How are networks classified?  Client/server – contains servers and clients  Peer-to-peer (P2P) – every computer is considered an equal  KaZaa: file sharing among peers

Computer Concepts 5th Edition Parsons/Oja Page 231 Section B Chapter 5 Internet Building Blocks Background: How did the Internet get started?  The United States created ARPA (Advanced Research Projects Agency).  to help scientists communicate and share valuable computer resources  in response to the Soviet Union’s launch of Sputnik in 1957, the first artificial satellite  The ARPANET, created in 1969, connected computers at four universities

Computer Concepts 5th Edition Parsons/Oja Page 231 Section B Chapter 5 Internet Building Blocks How did the Internet get started?  In early 1990s, software developers created new user-friendly Internet access tools  Web browser: created at the University of Illinois  Today, the Internet connects computers all over the globe and supplies information to people of all ages and interests

Computer Concepts 5th Edition Parsons/Oja Page 232 Section B Chapter 5 Internet Building Blocks Internet Hardware and Connections: What type of hardware populates Internet nodes?  Difficult to diagram due to over 100 million nodes and 350 million users

Computer Concepts 5th Edition Parsons/Oja Page 232 Section B Chapter 5 Internet Building Blocks What kinds of network devices are part of an ISP?  An ISP operates network devices that handle the physical aspects of transmitting and receiving data from your computer  Modems  Domain name server  Router

Computer Concepts 5th Edition Parsons/Oja Page 233 Section B Chapter 5 Internet Building Blocks What kinds of network devices are part of an ISP?  An ISP links to other ISPs in a sort of ISP network  Network service Providers (NSPs) supply ISPs with access to high-speed transmission lines that form the backbone of the Internet  Interstate highways of the Internet  NSPs also provide routers at network connection points

Computer Concepts 5th Edition Parsons/Oja Page 233 Section B Chapter 5 Internet Building Blocks How fast does data travel over the Internet?  Using Ping or Traceroute, you can discover how long data is in transit  On average, data within the US usually arrives at its destination ms (milliseconds) after it is sent  Overseas transmission require a little more time

Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks Internet Protocols: Why does the Internet use TCP/IP?  TCP/IP provides a standard that is fairly easy to implement, public, free, and extensible  The Internet is not owned, operated, or controlled by any single entity  TCP/IP is glue that holds the Internet together

Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks How does TCP/IP work?  It is a suite of protocols  TCP (Transmission Control Protocol) – breaks a message or file into packets  IP (Internet Protocol) – responsible for addressing packets so that they can be routed to their destination

Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks Is TCP/IP the only Internet Protocol?

Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks IP Addresses: Does the Internet use a special addressing scheme?  The IP part of TCP/IP defines the format for the addresses that identify computers on the Internet  These addresses are called IP addresses  An IP address is a series of numbers, such as  It is separated into four sections by periods  Each section’s number cannot exceed 255  Each address requires 32 bits (8 bits per section)

Computer Concepts 5th Edition Parsons/Oja Page 235 Section B Chapter 5 Internet Building Blocks Do I need a permanent IP address?  Static IP address – permanently assigned IP address  Dynamic IP address – temporarily assigned  ISPs need static IP addresses  Clients typically use dynamic IP addresses as the IP addressing scheme provides approximately only 4.3 billion unique addresses

Computer Concepts 5th Edition Parsons/Oja Page 235 Section B Chapter 5 Internet Building Blocks Domain Names: What’s a domain name?  People find it difficult to remember long strings of numbers, so host computers also have names called domain names  Domain name – “fully qualified domain name” (FQDN), usually typed in all lowercase  Key component of URLs and addresses  files is the domain name

Computer Concepts 5th Edition Parsons/Oja Page 236 Section B Chapter 5 Internet Building Blocks What’s a domain name?  A domain name ends with an extension that indicates its top-level domain

Computer Concepts 5th Edition Parsons/Oja Page 236 Section B Chapter 5 Internet Building Blocks How are domain names related to IP addresses?  Each name corresponds to an IP address  Domain name system – huge database that houses the names and IP addresses  Domain name servers – computers that house the database

Computer Concepts 5th Edition Parsons/Oja Page 237 Section B Chapter 5 Internet Building Blocks Do I need my own domain name?  Not for normal client-style Internet activities  If you plan to operate your own Web server, you may want a name

Computer Concepts 5th Edition Parsons/Oja Page 237 Section B Chapter 5 Internet Building Blocks How do I get a domain name?  ICANN (Internet Corporation for Assigned Names and Numbers) – global organization that coordinates the technical management of the Internet’s domain name system, allocation of IP addresses, and the assignment of protocol parameters  Organizations or individuals can select a domain name and register it by using an online registration service

Computer Concepts 5th Edition Parsons/Oja Page 237 Section B Chapter 5 Internet Building Blocks How do I get a domain name? Click to start

Computer Concepts 5th Edition Parsons/Oja Page 238 Section B Chapter 5 Internet Building Blocks Is a fee required to obtain a domain name?  You can register a domain name for a minimal annual fee ($25 - $50)  Some Internet entrepreneurs have registered high-profile domain names and resell them  Sell-videos.com - $35,000  Thelocallistings.com - $87,500

Computer Concepts 5th Edition Parsons/Oja Page 240 Section C Chapter 5 Internet Access Dial-Up Connections: How does a dial- up connection work?  Uses POTS (plain old telephone service) to transport data between your computer and your ISP

Computer Concepts 5th Edition Parsons/Oja Page 241 Section C Chapter 5 Internet Access How does a dial-up connection work?  While connected to your ISP, your call is routed through the telephone company’s local switch to the ISP Local Switch

Computer Concepts 5th Edition Parsons/Oja Page 241 Section C Chapter 5 Internet Access How does a modem work?

Computer Concepts 5th Edition Parsons/Oja Page 242 Section C Chapter 5 Internet Access Can I talk and send data at the same time?  When connected to ISP, data is transmitted in same frequencies used for voice conversations

Computer Concepts 5th Edition Parsons/Oja Page 242 Section C Chapter 5 Internet Access How fast is a modem?  Speed was measured as baud rate, number of times per second that a signal in a communications channel varies speeds  Today, measure in terms of bits per second  V.90 – theoretical maximum speed of 56 Kbps  Even with perfect connection, a 56 Kbps modem tops out at about 44 Kbps  Downstream vs. upstream

Computer Concepts 5th Edition Parsons/Oja Page 243 Section C Chapter 5 Internet Access Cable Television Connections: How can the cable TV system provide Internet access?  Community antenna television – CATV  The satellite dish farm at which television broadcasts are received and retransmitted is referred to as the head-end  From the head-end, cabling system branches out and eventually reaches consumers’ homes  Topology is similar to computer network, and that is what is formed when you use cable TV as your ISP

Computer Concepts 5th Edition Parsons/Oja Page 243 Section C Chapter 5 Internet Access How can the cable TV system provide Internet access?

Computer Concepts 5th Edition Parsons/Oja Page 244 Section C Chapter 5 Internet Access Are television and data signals carried over the same cable?  Lowest-capacity coaxial cable has far greater capacity than POTS lines  Cable’s bandwidth is divided among 3 activities

Computer Concepts 5th Edition Parsons/Oja Page 244 Section C Chapter 5 Internet Access How do I set up a cable modem connection?  Need an Ethernet NIC  Need a cable modem, which converts your computer’s signal into one that can travel over CATV cable

Computer Concepts 5th Edition Parsons/Oja Page 245 Section C Chapter 5 Internet Access What’s the significance of becoming part of a “neighborhood network”?  With CATV, your computer becomes part of a neighborhood data network  More people on the network, means slower service  Also, in early days your network neighborhood showed your neighbors

Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access What’s the significance of becoming part of a “neighborhood network”?  An always-on connection is always connected  A hacker who discovers that your computer has a security weakness can easily find it again, and its high-speed access makes it a very desirable target

Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access How do I secure an always-on connection?  Disable file and print sharing

Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access How do I secure an always-on connection?  Shut down your computer when you are not using it  Install personal firewall software, which is designed to analyze and control incoming and outgoing packets  Pick level – high, medium, or low

Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access DSL, ISDN, T1, and T3: What other options are available for high-speed Internet access?  Several services such as DSL, ISDN, T1, and T3 take advantage of full capacity of the telephone connections (normal dial-up services do not)  Offers high-speed digital communications links for voice and data

Computer Concepts 5th Edition Parsons/Oja Page 247 Section C Chapter 5 Internet Access What is DSL?  DSL (Digital Subscriber Line) is a high-speed, always-on, Internet access technology that runs over standard phone lines

Computer Concepts 5th Edition Parsons/Oja Page 247 Section C Chapter 5 Internet Access What is DSL?

Computer Concepts 5th Edition Parsons/Oja Page 248 Section C Chapter 5 Internet Access What is DSL?  Speed varies, but most are rated at 1.5 Mbps downstream

Computer Concepts 5th Edition Parsons/Oja Page 248 Section C Chapter 5 Internet Access How do I install DSL?  Telephone line connected to DSL switch at your house  Line connected to DSL modem which connects to your computer’s Ethernet card

Computer Concepts 5th Edition Parsons/Oja Page 249 Section C Chapter 5 Internet Access Who uses T1 or T3 service?  T1 – high-speed Mbps digital network  Consists of 24 individual channels (64 Kbps for each)  Popular for businesses and ISPs  Not as fast as DSL  T3  672 channels  Supports data rates of about 43 Mbps  Sometimes referred to as DS3 (Digital Service-3) lines  Provide many of the links on the Internet backbone

Computer Concepts 5th Edition Parsons/Oja Page 249 Section C Chapter 5 Internet Access Wireless Internet Access: What are the options for wireless connections to the Internet?  Personal satellite connections – expensive, but sometimes only option (particularly in remote rural areas)  Cellular telephones – slowest, but provides mobile Internet access

Computer Concepts 5th Edition Parsons/Oja Page Section C Chapter 5 Internet Access How does satellite access work?  Direct satellite service (DSS) uses a geosynchronous or low-earth satellite to send television, voice, or computer data directly to a satellite dish  Two-way satellite service ships both upstream and downstream data through the satellite  offers 500 Kbps downstream  Kbps upstream

Computer Concepts 5th Edition Parsons/Oja Page 249 Section C Chapter 5 Internet Access How does satellite access work?

Computer Concepts 5th Edition Parsons/Oja Page 251 Section C Chapter 5 Internet Access What’s the fastest Internet connection?

Computer Concepts 5th Edition Parsons/Oja Page 254 Section D Chapter 5 LAN Technology LAN Services and Resources: What sort of resources does a LAN provide?  Main advantage of a LAN is that multiple users can share a limited number of resources  Can share a high-speed connection

Computer Concepts 5th Edition Parsons/Oja Page 254 Section C Chapter 5 LAN Technology How do I access network resources?  When you boot your computer, OS looks to see if it can access a LAN  Generally need to reboot after loosing network connection  The OS keeps track of network resources you can access automatically  Some network resources become available as soon as your computer completes the boot process, and others after you use your networking utilities

Computer Concepts 5th Edition Parsons/Oja Page Section D Chapter 5 LAN Technology Can a LAN use existing phone or electrical wiring?  HomePNA uses a special NIC and cable to connect each computer to a standard telephone wall jack  Network frequency is usually different from voice, so can use network at same time you place a call  You can not make a call when dial-up Internet connection is active however  HomePLC uses special NIC to connect to standard electrical outlet, but power fluctuations can adversely affect signal

Computer Concepts 5th Edition Parsons/Oja Page 256 Section D Chapter 5 LAN Technology Can LANs use wireless technology?  Wireless LANs are slower but eliminate unsightly wires  Signals can be disrupted by large metal objects, cell phones, pagers, and other wireless devices  Most popular s b  11 Mbps, spans 300 feet, and can be used with Ethernet networks  Bluetooth  Kbps, range of 35 feet

Computer Concepts 5th Edition Parsons/Oja Page Section A Chapter 5 Network Building Blocks LANs with wireless technology  Wi-Fi: Wireless Fidelity:  Avoid expense of wiring installation for network  Enjoy mobility  Up to 100 times faster than dial-up connection 11 mps  Range of 100 up to 1,000 feet  Signals operate in the 2.4 and 5Ghz radio bands, which are also used today by many cordless phones  Hot spot operators Starbucks, hotels, airports, etc.