1. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall Essentials of Telecommunications

2. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall2 Learning Objectives Compare and contrast network topologies Explain the basic functions of the TCP/IP protocols Evaluate the limitations of the various classes of Internet addresses Select the best Internet link service according to organizational or individual needs

3. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall3 Network Topologies A network is made up of nodes and communication lines topology Network topology refers to the physical layout of the network Star Ring Bus

4. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall4 StarRingBus

5. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall5 Peer-to-peer vs. client-server networks Peer-to-peer: each computer has equal capabilities Client-server: Servers offer services to clients Predominant on the Internet

6. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall6 Switching Techniques Switches – devices that direct the flow of signals and route communication traffic

7. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall7 Circuit switching Circuit switching The entire communication path is reserved for the duration of the session Typical of voice communication Inefficient for data communication Resources are being wasted while reserved, but not in use

8. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall8 Packet switching Packet switching Data divided into packets Each packet travels independently through the network Upon arriving at the final destination, packets are reassembled Efficient solution for data communication

9. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall9 Network Protocols A set of rules that governs the flow and processing of information in a network

10. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall10 TCP/IP: IP: IP: Addressing Packet reassembly Multiplexing Operates between hosts TCP: TCP: Controls flow of information from client to server

11. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall11 LANs and WANs Local Area Network (LAN) – serves a building or a campus of adjacent buildings Owned by an organization Used for internal purposes Typically linked to the Internet

12. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall12 Wide Area Network (WAN) – cover large areas Employ different types of transmission media Ex.: telephone networks, Internet backbone, etc.

13. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall13 Intranet Intranet - an internal network based on TCP/IP Extranet Extranet - an intranet that can also be partially accessed by customers and/or suppliers Often, LANs of two or more partners linked through the Internet

14. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall14 Virtual private networks (VPNs) Virtual private networks (VPNs) Secure Secure internal networks connected to the Internet To be covered in more detail later

15. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall15 Internet Addressing unique Each device connected to the internet must be assigned a unique IP number Also called Internet address or IP address The IP number may be temporary (just for the duration of the connection) The IP number is made up of up to four blocks

16. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall16 Staticdynamic Static vs. dynamic IP numbers An IP address consists of two parts, identifying the Network, and The node within the network IPv4 vs. IPv6

17. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall17 Five network classes Class A – very large networks Class B – medium-sized networks Class C – small networks Classes D and E are currently not assigned

18. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall Bandwidth, bandwidth, and more bandwidth

19. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall19 Integrated Services Digital Network (ISDN) International standard Transmits voice, data, and video over digital lines 64Kbps and 128Kbps Service offered by phone companies Already outdated

20. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall20 Cable modem Permanent connection to the Internet Shared resource Actual speed depends on the number of subscribers sharing the same cable

21. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall21 Digital Subscriber Line (DSL) Service offered by phone companies Several standards and technologies Permanent connection Speed deteriorates with distance Most common: asymmetric DSL (ADSL) High download speed Low upload speed

22. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall22 T lines T1: 1.544Mbps Point-to-point Not switched Dedicated Digital

23. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall23 T2: A combination of four T1 lines T3: A combination of 28 T1 lines T1 and T3 lines form the basis of most private networks T lines (continued)

24. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall24 Asynchronous Transmission Mode (ATM) Very high speed, fiber optics based, standard Cell switching Cell switching A cell = 53 bytes All cells use the same route from source to destination

25. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall25 Wireless Communication Mobile communication PDAs Wireless Internet connections

26. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall26 Business considerations in telecommunications Scalability – the ability to easily augment a network Three types of costs: The one time investment in lines Monthly fees for leased lines Maintenance costs Security issues

27. Oz – Foundations of Electronic Commerce © 2002 Prentice Hall Essentials of Telecommunications