Telecommunications , Networks & Internet

1. Telecommunications, Networks & Internet

2. Learning Objectives: In this modul, we will study • The basic components of a telecomm system • The technologies used in telecomm systems • Various ways to configure networks • Various ways that businesses use networks today

3. notebookcomputers Web-enabledPDAs smartphones servers GPS receivers desktopcomputers mainframecomputers set-top boxes Tablet PCs Communications in general • What are computercommunications? • Process in which two or more computers or devices transfer data, instructions, and information

4. The Telecommunications System • The hardware and software that transmits information from one location to another • Components include: • Hardware • Media • Networks • Software • Data communication providers • Protocols • Applications

5. Telecommunication Signals • Analog Signals • Continuous waves • Information conveyed by changing wave characteristics (amplitude and frequency • Digital Signals • Discrete pulses • Information conveyed in binary form (on or off pulses) • Easily understood by computer

6. Hardware: Communication Processors • Hardware devices utilized in data transmission and reception are: Modem device that converts analog signals to digital (and vice versa); enables signal transmission over telephone system Multiplex device that transmits multiple signals over single medium Front-end Processor specialized computer dedicated to managing communication tasks

7. Host computer hardware Telecomm. media channel Front- End processor Multiplex Modem Modem DeMultiplex Front- End processor Receiver Transmitter Host computer hardware Hardware: Communication Processors

8. Wire-based Communication Channels • Twisted-pair wire(telephone wire) • Cheap and easy to work with • Slow; subject to interference; low security • Coaxial cable • Carries more data; shielded from interference • More expensive; harder to work with; low security

9. Wire-based Communication Channels • Fiber-optic cable • Transmit information as light waves through glass fiber • Fast; high-capacity; secure; not subject to interference • Hard to work with • Microwave • High capacity; inexpensive relative to wire • Requires line of sight transmission towers; subject to environmental interference

10. Wire-based Communication Channels • Satellite • Very high capacity; large coverage area • Expensive; propagation delay; requires encryption for security • Radio • Suitable for short distance communication; inexpensive; easy to install; high speed • Interference problems; insecure • Cellular radio technology • Infrared • Blue Tooth

11. Understanding Communication Media • Transmission speed • Bandwidth – the range of frequencies available in a channel • More bandwidth, more channel capacity • Transmission mode • Character by character (asynchronous) • Streams of characters (synchronous) • Transmission accuracy • Accuracy controls added to messages • Error detection and correction required

12. Telecomm Services • Switched lines – transmission is routed along path to destination • Dedicated lines – continuous connection is established • Wide-area Telecomm Service (WATS) – lower cost long distance telephone service • Integrated Services Digital Network (ISDN) – high speed data transmission over existing phone lines • Digital Subscriber Lines (DSL) - high speed digital transmission over existing phone lines

13. Network Basics • Network – the communication devices, media, and software needed to connect two or more computer systems • Local Area Networks (LANs) – a network that spans a relatively small geographic distance • Wide Area Networks (WANs) – network that spans a large geographic distance

14. Local Area Networks • Connect computers and other devices enabling resource sharing • Variety of topologies can be used, each with performance strengths and weaknesses • Several LANs can be connected via bridges • LANs can be connected to external networks via gateways

15. db Local Area Networks: Topologies

16. Local Area Networks • Required technology: • Cables or wireless technology • Network interface adaptor cards • Network management software • Chosen topology is implemented by selection of software, interface cards, and wiring strategy.

17. Local Area Networks • Gateway – is a communication processor that connect dissimilar networks by translating from one set of protocol to another • Bridge – connects two networks of the same type • Router – routes messages through several connected LANs or to a WAN

18. Wide Area Networks • Service provided by common carriers • Internet is a public WAN • Value-added networks (VAN) – private, data-only networks managed by third party; accessed via subscription. • Virtual private network (VPN) – secure gateway between corporate systems and the Internet.

19. Network Processing Strategies • Client/server processing • Applications can be divided into presentation, applications, and data management components • Components can be partitioned between the server and the clients to form different implementations • Peer-to-peer processing • Simplified form of client/server • Devices attached to network have access to all other devices • No file server involved • Simple set up and maintenance • Implemented in many operating systems such as Windows 2000 and Windows XP

20. Network Processing Strategies Client/server processing Peer-to-peer processing

21. Telecomm Applications • Electronic Mail – computer-based messaging • Videoconferencing – group meetings between separate locations • Electronic Data Interchange – electronic transmission of routine business transactions • Electronic Funds Transfer – electronic processing of financial transactions • Facsimileselectronic document transmittal • Telecommutingworking at home via telecomm links • Distance Learningclasses offered on same time/different place, or different time/ different place basis

22. What is the Internet? • The Internet: an interconnected networkof thousands of networks • Links academic, research, government, and commercial institutions • Connects computers to about every country in the world • Growing too fast to measure its growth • Internet is decentralized • Internet doesn’t have hard boundaries

23. The Operation of the Internet • Packets of information flow between machines governed by common rules (protocols): • Internet protocol (IP) • Transport control protocol (TCP) • Internet is a packet-switching network • Messages are decomposed into packets, containing part of the message, plus information on the sending and receiving machines and how the packet relates to the other packets • Packets travel independently and possibly on different routes through the Internet • Packets are reassembled into the message at the receiving machine.

24. Internet Protocols • Transmission Control Protocol/Internet Protocol, TCP/IP… • At the heart of the Internet • Allows cross-network communication • TCP breaks messages into packets. • Each packet has all the information needed to travel from network to • network. • Host systems called routers determine how to route transmissions. • Packet-switching is flexible and robust.

25. Internet Protocols • IP is the address for the packets. • Each Internet host computer has a unique IP address. • Each address is comprised of four sets of numbers separated by periods, • such as 123.23.168.22. • NextGeneration Internet will allow more addresses and multicasting.

26. Internet Servers • E-mail server • acts like a local post office for a particular Internet host—abusiness, an organization, or an ISP. • File servers are common within LANs. • Also used to share programs, media files, and other data across the Internet • File transfer protocol (FTP) • allows users to transfer files. • Download files from remote servers to their computers • Upload files to remote computers • File compression saves storage space on disk and saves transmission time whenfiles are transferred through networks.

27. Internet Servers • Application server • stores PC office applications, databases, or other applications. • Makes them available to client programs that request them • Might be housed at an application service provider (ASP), a company thatmanages and delivers application services on a contract basis • Web server • stores Web pages and sends pages to client Web browsers.

28. Web Protocols: HTTP and HTML • HTTP (Hypertext transfer protocol) used to transfer Web pages • HTML (HyperText Markup Language) created for encoding and displaying documents

29. Extranetallows customers or suppliers to access part of company’s intranet Makes information accessible to employees Typically includes connection to Internet Internal network that uses Internet technologies Intranets • What is an intranet?

30. Intranets • A private network that uses Internet software and TCP/IP protocols • Provide employees with easy access to corporate information • Used to deploy corporate applications • Examples – policies and procedures manuals; human resource forms; product catalogs • Security is a concern • Security measures include – public key security, encryption, digital certificates, firewalls

31. Extranets • An extension of an intranet to selected outside business partners, such as suppliers, distributors, and key customers • Provide business partners with easy access to corporate information and easy collaboration • Security • Critical to prevent unwanted entry into internal systems • Virtual private networks (VPNs) are often used to add security to Internet communication

32. Extranets (continued) • Extranet configurations • One company sets up a Extranet for its dealers, customers, or suppliers • Companies within an industry set up a collaborative Extranet for mutual benefit • Several companies collaborate over an Extranet for joint venture • Benefits include – • Lower communication costs; better communication; improved order entry and customer service; improvement in business effectiveness

33. Thank You C U Next Week