Internet and LAN Technology

1. Section A Network Building Blocks CHAPTER 5 Internet and LAN Technology PARSONS/OJA Page 216

2. 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 Page 218

3. 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 Page 219

4. 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 Page 220

5. Section A Chapter 5 Network Building Blocks Exactly what is transmitted when I send a message? Page 220

6. 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 Page 221

7. 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 Page 221

8. 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 Page 221

9. 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 Page 221-222

10. 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 Page 222

11. 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 Page 222

12. 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) Page 222

13. 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 Page 223

14. 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 Page 223

15. 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 Page 223

16. 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 Page 223

17. 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 Page 224

18. 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 Page 224

19. 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 Page 225

20. 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 Page 226

21. 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 Page 226

22. 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 Page 226-227

23. 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 Page 227

24. 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 Page 227

25. 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 Page 228

26. 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 Page 228

27. Section A Chapter 5 Network Building Blocks How are networks classified? • Ethernet – free for all Page 229

28. 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… Page 229

29. 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 Page 230

30. 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 Page 231

31. 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 Page 231

32. 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 Page 232

33. 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 Page 232

34. 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 Page 233

35. 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 110-120 ms (milliseconds) after it is sent • Overseas transmission require a little more time Page 233

36. 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 Page 234

37. 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 Page 234

38. Section B Chapter 5 Internet Building Blocks Is TCP/IP the only Internet Protocol? Page 234

39. 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 204.127.129.001 • It is separated into four sections by periods • Each section’s number cannot exceed 255 • Each address requires 32 bits (8 bits per section) Page 234

40. 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 Page 235

41. 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 e-mail addresses • www.thex-files.com/episode236 - www.thex-files is the domain name Page 235

42. 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 Page 236

43. 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 Page 236

44. 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 Page 237

45. 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 Page 237

46. Section B Chapter 5 Internet Building Blocks How do I get a domain name? Click to start Page 237

47. 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 Page 238

48. 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 Page 240

49. 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 Page 241

50. Section C Chapter 5 Internet Access How does a modem work? Page 241