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Chapter 5 Business Networks & Telecommunications
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  1. Chapter 5Business Networks & Telecommunications p189 – 203: 1.VPN 2. Switching 3. Protocols 1

  2. Revision: • What is makes up the Telecommunications Network Model? • What are the two categories of media? • Name the different media? • What is the difference between a digital and analog signal? • List the 4 different types of networks? • What type of network is on slide 4? 2

  3. Telecommunications NW Model: • A telecommunications network is any arrangement where • A sender transmits a message • To a receiver • Over a channel • Consisting of some sort of medium 3

  4. What type of network? 4

  5. Different Media: • Wired (or …….) and Wireless (…………) • See next slides 5

  6. Telecommunications Media • Twisted-Pair Wire • Ordinary telephone wire • Copper wire is twisted into pairs 6-6

  7. Telecommunications Media • Coaxial Cable • Sturdy copper oraluminum wire wrappedwith spacers to insulateand protect it 6-7

  8. Telecommunications Media • Fiber-Optic Cable • One or more hair-thinfilaments of glass fiber wrapped in a protective jacket 6-8

  9. Analog versus Digital • Analog or digital refers to the method used to convert information into an electrical signal • Analog: an electrical current is generated that is proportional to the quantity being observed • Digital: the quantity being observed is expressed as a number 9

  10. Digital Network Technologies • Telecommunications are being revolutionized by switch from analog to digital • Analog: voice-oriented transmission • Digital: discrete pulse transmission • Benefits • Higher transmission speeds • Moves larger amounts of information • Greater economy and much lower error rates • Transmits multiple types of communications (data, voice, video) on the same circuits 10

  11. Virtual Private Network: • A network is private, when only authorized users can access the network. • So instead leasing lines and services from an ISP, a company can use the internet by isolating a part of it for private use: creating a “tunnel” through the internet or any public network. • This is done by implementing sophisticated security measures. See next slide. 11

  12. VPN (cont.) • Used to establish secure intranets and extranets • The Internet is the main backbone network • Relies on network firewalls, encryption, and other security features to build a “pipe” through the Internet • Creates a private network without the high cost of a separate proprietary connection 14

  13. VPN (p188) • Intranet: • Extranet: 15

  14. Switching Techniques • How can computers or nodes link to each other on the network: • Circuit switching: dedicated channel (path or circuit) established for duration of transmission • Packet switching: message broken into packets • Packet: group of bits transmitted together 16

  15. Switching Techniques (continued) 17

  16. Switching Tech. (cont.) • Frame relay: high-speed packet-switching protocol used in WANs • Variable-sized packets routed quickly • Better ratio of data bits to non-data bits • Multi-protocol label switching: enhances services like VoIP. • Still broken into packages, but all will use the same path on the network 18

  17. Protocols • Protocol: set of rules governing communication between computers • Protocol is like human language and basic understanding • Some protocols designed for WANs, LANs, and wireless communications • Most important set of protocols called TCP/IP 19

  18. TCP/IP • TCP/IP: Transmission Control Protocol/Internet Protocol • Ensures packets arrive accurately • Ensures delivery of packets from node to node, respectively • Internet backbone: highest speed channels • Host: computer connect directly to backbone • IP number: unique identification for device • DNS: Domain Name Service maintains character-based names of IP numbers 20

  19. What is your PC’s IP Address? • Start > All Programs > Accessories Command Prompt > ENTER • Type: ipconfig • So, what is your IP address

  20. Let’s check for GOOGLE!! • Still in command prompt: • Type: ping google.com • If you are having connectivity problems, you can use the ping command to check the destination IP address you want to reach and record the results. The ping command displays whether the destination responded and how long it took to receive a reply.

  21. Google.com • OPEN the browser and type in the address the ip address of google and ENTER • What is the DNS service doing?

  22. TCP/IP (continued) • Static IP number: permanent number assigned to device • Dynamic IP number: temporary IP number assigned for duration of connection 24

  23. IP or URL Address: • The Uniform Resource Locator is an address that points to a specific resource on the Web • http://www.stanford.edu/jengk/useless.html • http:// protocol for Web pages • www.standford.edu is the Domain name: it identifies the computer that stores the Web pages • Jengk/ is the directory path; identifies where the page is store on the computer • Useless.html is the document name or web page 25

  24. Ethernet • Ethernet: LAN protocol using coaxial cable, also known as IEEE 802.3 • Gigabit Ethernet: faster Ethernet connections • Devices on network contend with other devices for transmission time • CSMA/CD protocol ensures no collisions in transmission 26

  25. Know more about bands: • See: http://www.disa.mil/jsc/speccht.html

  26. Wireless Protocols • IEEE 802.11: known as Wi-Fi (wireless fidelity) • Supports wireless communication within 100 metres of router with speed of 11 Mbps: 802.11b • 802.11g Max speed 54 Mbps all in range 2.4-2.5 GHz • Access point: Wi-Fi router connects to AP that connects to the Internet. • Access point (hotspot): allows Internet access within range of equipment • Encryption: ability to scramble and code messages • Use keys shared between sender and receiver 30

  27. Wireless Protocol (cont.): • IEEE 802.15 Bluetooth: allows devices to communicate within 10 metres • Examples: Wireless keyboards and mice, microphones for mobile phones. 31

  28. Wireless Protocols (continued) • Worldwide Interoperability for Microwave Access (WIMAX): increases range and speed of wireless communication IEEE 802.16 • 110 km, speed of 100 Mbps • Works with metropolitan area networks • Mobile Broadband Wireless Access (MBWA): similar to cell phone communications • Compatible with IP services • Compatible with Wi-Fi and Bluetooth 32

  29. Wireless Protocols (continued) 33

  30. Generations in Mobile Communications • Generations of mobile communication technologies are determined by capabilities and transmission speed: • 1G, First generation analog and circuit switching • 2G, Second generation used digital voice encoding • 2.5G, Speed 144 Kbps, packet switching and limited Internet access • 3G, speeds up to1 Mbps, support video, Internet access • 4G, digital, packet switching, bandwidths up to 100 Mbps and tighter security. • Future: 34

  31. Internet Networking Services • Variety of options to choose from when subscribing to network services • Downstream: speed of receiving from network • Upstream: speed of transmitting to network 35

  32. Cable • Internet links provided by television cable firms • Cable connected to Internet server • At residence, cable split into TV set and computer • Cable shared by all subscribers 36

  33. Digital Subscriber Line (DSL) • Digital subscriber line (DSL): data remains digital through entire transmission; 8Mbps • Uses telephone lines connected to DSL bridge/modem • Several types of DSL • Asymmetric (ADSL) allows different upstream and downstream rates • SDSL for short distances 37

  34. Satellite • Satellite services use microwaves • Service provider installs dish antenna, used as communications satellite • Speeds up to 45 Mbps • GPS free satellite service 38

  35. Fixed Wireless • Fixed wireless: point-to-point transmission between two stationary devices • Wireless Internet service provider (WISP) • Provides fixed wireless service • Highly modular and scalable 39

  36. Optical Carrier • Optical carrier using optical fibre. • Expensive • High connection speeds • Uses basic unit of 51.84 Mbps • Used by • ISPs • Search engines • Content-rich Web sites 40

  37. Broadband over Power Lines (BPL) • Broadband over Power Lines (BPL): uses electric power lines to carry digital signals • Used by utility companies • Monitor power consumption • Detect power failure • Track power outages 41

  38. The Future of Networking Technologies: • Broadband Telephoning: VoIP • Radio Frequency Identification: RFID • Converging Technologies: 42

  39. Broadband Telephoning: • Voice over Internet Protocol: uses Internet connection to conduct telephone conversations using VoIP. • Regular telephone companies charge according to number of minutes a call last • ISP charge customers a flat monthly connection fee for connection to Internet • Three different topologies:

  40. Technologies: • PC-to-PC • PC-to-Phone • Phone-to-Phone

  41. PC-to-PC: • In this model, both caller and receiver must have Internet phone equipment (VoIP) to talk to each other. • The call is routed through an ISP such as Netcom. • Both caller and receiver must have their computers on to complete calls

  42. PC-to-Phone • These calls are routed like a normal telephone call, except: • The PC must have Internet phone equipment • A call is dialed to the ISP, routed back through the internet backbone • And then sent back to the voive phone network

  43. Phone-to-Phone • One caller would dial a code, similar to a long-distance code • The ISP gateway will rout the call through the Internet and • Then converts it the signal back to the voice phone network upon reaching its connection.

  44. Advantages/Disadvantages • P202, 203 • VoIP becomes portable

  45. Radio Frequency Identification • RFID tags tiny and need little power • Objects are embedded with tags that contain a transponder: • It’s a radio ‘transmitter-receiver’ that is activated for transmission by a signal that is transmitted to it • The tag has a digital memory with a unique EPC 49

  46. RFID: • The interrogator • An Arial • Transceiver • Decoder • Emits a signal activating the RFID tag so that the interrogator can READ/WRITE data to it • Readers decode data stored in tag’s memory and data passed to host computer