6-1 McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

Telecommunications and Networks Business value of networks The Internet Network components Chapter 6 McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

6-3 Network Concepts Network An interconnected chain, group or system Number of possible connections on a network is N * (N-1) Where N = number of nodes (points of connections on the network) Example, if there are 10 computers on a network, there are 10 * 9 = 90 possible connections

6-4 Telecommunications Exchange of information in any form (voice, data, text, images, audio, video) over networks

6-5 Trends in Telecommunications

6-6 Open Systems Information systems that use common standards for hardware, software, applications and networks Internet networking technologies are a common standard for open systems Connectivity: Ability of networked computers to easily access and communicate with each other and share information Interoperability: The ability of an open system to enable end user applications to be accomplished using different varieties of computer systems, software packages, and databases provided by a variety of interconnected networks

6-7 Middleware Any programming that serves to “glue together” two separate programs

6-8 Digital Network Technologies Rapid change from analog to digital network technologies Analog: voice-oriented transmission, sound waves Digital: discrete pulse transmission Digital allows: Higher transmission speed Larger amounts of information Greater economy Lower error rates Multiple forms of communications on same circuit

6-9 Internet2 Next generation of the Internet High-performance network In use at 200 universities, scientific institutions, communications corporations

6-10 Business Value of Telecommunication Networks

6-11 The Internet Over 46 million servers (2004) 710 – 945 million users (2004) No central computer system No governing body No one owns it

6-12 Internet Service Provider ISP A company that specializes in providing easy access to the Internet For a monthly fee, you get software, user name, password and access ISPs are connect to one another through network access points

6-13 Popular uses of the Internet

6-14 Using the Internet for business

6-15 Business value of the Internet

6-16 An Intranet A network inside an organization That uses Internet technologies (such as Web browsers and servers, TCP/IP protocols, HTML, etc.) To provide an Internet-like environment within the organization For information sharing, communications, collaboration and support of business processes Protected by security measures Can be accessed by authorized users through the Internet

6-17 Enterprise Information Portal

6-18 Extranet Network links that use Internet technologies To connect the Intranet of a business With the Intranets of its customers, suppliers or other business partners

6-19 Extranet Uses

6-20 Telecommunications network Any arrangement where a sender transmits a message to a receiver over a channel consisting of some type of medium

6-21 Telecommunications network components Terminals: any input/output device that uses networks to transmit or receive data Telecommunications Processors: devices that support data transmission and reception Telecommunications Channels: media over which data are transmitted and received Computers: all sizes and types Telecommunications Control Software: programs that control telecommunications activities

6-22 Telecommunications network model

6-23 Wide Area Network (WAN) Telecommunications network that covers a large geographic area Source: Courtesy of Cisco Systems Inc.

6-24 Local Area Network (LAN) Connect computers within a limited physical area such as an office, classroom, or building

6-25 Virtual Private Networks (VPN) A secure network that uses the Internet as its backbone but relies on firewalls, encryption and other security A pipe traveling through the Internet

6-26 VPN

6-27 Client/Server networks Clients: End user personal computers or networked computers Interconnected by LANs Servers: manage networks Processing shared between clients and servers

6-28 Client/Server Network

6-29 Network Computing Networks are the central computing resource of the organization Thin clients: network computers and other clients provide a browser-based user interface

6-30 Peer-to-peer networks Networks that connect from one PC to another PC Common use is the downloading and trading of files

6-31 Telecommunications Media Twisted-pair wire: Ordinary telephone wire Copper wire twisted into pairs Source: Phil Degginger/Getty Images.

6-32 Telecommunications Media Coaxial cable: Sturdy copper or aluminum wire wrapped with spacers to insulate and protect it Source: Ryan McVay/Getty Images.

6-33 Telecommunications Media Fiber-optic cable: One or more hair-thin filaments of glass fiber wrapped in a protective jacket Source: CMCD/Getty Images.

6-34 Problem of “The Last Mile” Network providers use fiber optic to provide backbone But houses are connected to the backbone via twisted-pair Cannot get the benefit of the faster, better technology

6-35 Wireless Technologies Terrestrial microwave Earthbound microwave systems that transmit high- speed radio signals in a line-of-sight path Between relay systems spaced approximately 30-miles apart Communications satellites Satellite serves as relay stations for communications signals Uses microwave radio signals

6-36 Wireless Technologies Cellular and PCS telephone and pager systems Divide the geographic area into small areas or cells Each cell has transmitter or radio relay antenna to send message from one cell to another Wireless LANs Radio signals within an office or building Connect PCs to networks Bluetooth Short-range wireless technology To connect PC to peripherals such as printer

6-37 Wireless Web Connect portable communications devices to the Internet

6-38 Telecommunications Processors Modems Convert digital signals from a computer into Analog frequencies that can be transmitted over ordinary telephone lines

6-39 Internetwork Processors Switch – makes connections between telecommunications circuits in a network Router – intelligent communications processor that interconnects networks based on different protocols Hub – a port switching communications processor Gateway – connects networks using different communications architectures

6-40 Telecommunications Processors Multiplexer Allows a single communications channel to carry simultaneous data transmissions from many terminals

6-41 Telecommunications Software Used by servers and other computers to manage network performance Network Operating Systems Middleware

6-42 Network management functions Traffic Management – manage network resources and traffic to avoid congestion and optimize service levels to users Security – provide authentication, encryption, firewall, auditing and enforcement Network Monitoring – troubleshoot and watch over the network, informing network administrators of potential problems before they occur Capacity Planning – survey network resources and traffic patterns and users’ needs to determine how best to accommodate the needs of the network as it grows and changes

6-43 Network Topologies Topology: structure of a network Star: ties end user computers to a central computer Ring: ties local computer processors together in a ring on a relatively equal basis Bus: local processors share the same communications channel

6-44 Network Topologies

6-45 Internet Telephony Using an Internet connection to pass voice data using IP Voice over IP (VoIP) Skips standard long-distance phone charges

6-46 Bandwidth Frequency range of a telecommunications channel Determines transmission rate Classified in bits per second (bps) Transmission Rates: Narrow-band – low-speed Broadband – high-speed

6-47 Transmission Speeds

6-48 Network Interoperability Ensure that anyone anywhere on one network Can communicate With anyone anywhere on another network Telecommunications as discussed in this chapter wouldn’t be possible without interoperability