Open systems are a recent telecommunications trend. open systems:

Chapter 6 Telecommunications and Networks Mc. Graw-Hill/Irwin Copyright © 2010 by the Mc. Graw-Hill Companies, Inc. All rights reserved.

Network Concepts l A network is an interconnected or interrelated chain, group, or system l The number of possible connections on a network is N(N– 1) or N 2 –N N = number of nodes (points of connection) 10 computers on a network = 10(10– 1) = 10 x 9 = 90 possible connections 2 - 33

Metcalfe’s Law The usefulness (utility) of a network equals the square of the number of users The more users on a network, the more useful it becomes Until critical mass is reached, a change in technology only affects the technology Once critical mass is attained, social, political, and economic systems change Ex: The Internet is growing exponentially. We can expect more value, for less cost, virtually every time we log on 3 - 33

Telecommunication Trends 4 - 33

Telecommunications-Based Services 5 - 33

Open Systems l Open systems use common standards for hardware, software, applications, and networks – Internet networking technologies are a common standard for open systems l Connectivity – Open systems provide greater connectivity and network interoperability – Middleware may be needed to help diverse systems work together 6 - 33

Middleware Programming that mediates between two separate programs Allows a particular database to access other databases without custom programming Routes data and information between back-end data sources and end user applications The “Plumbing” Essential component of any IT infrastructure 7 - 33

Digital Network Technologies l Telecommunications are being revolutionized by the switch from analog to digital – Analog: voice-oriented transmission – Digital: discrete pulse transmission l 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 8 - 33

Wireless Technologies l Fiber-optic – Uses pulses of laser-generated light – Reduced size and installation effort – Vastly greater communication capacity – Faster transmission speeds – Freedom from electrical interference l Satellite Transmission – Can move massive quantities of data, audio, and video over global networks – Especially useful in isolated areas 9 - 33

Business Application Trends Telecommunications networks now play a vital and pervasive role in Web-enabled… E-business processes Electronic commerce Enterprise collaboration Other applications that support operations, management, and strategic objectives 10 - 33

Internet 2 – The Next Generation High performance Will not replace current Internet Different infrastructure In limited use already Users connect via Abilene at 120 Gbps Infinite bandwidth May never become totally open 11 - 33

Value of Telecommunications Networks Overcome geographic barriers Overcome time barriers Strategic Capabilities Overcome structural barriers Overcome cost barriers 12 - 33

Internet Service Providers Companies that specialize in providing easy access to the Internet For a monthly fee, they provide software, user names, passwords, and Internet access ISPs themselves are connected to one another through network access points One ISP can easily connect to another to obtain addresses of websites or user nodes 13 - 33

Popular Uses of the Internet E-Mail Surf Download Connect Buy & Sell Publish Discuss Compute Phone Calls And more… 14 - 33

Business Use of the Internet 15 - 33

Business Value of the Internet 16 - 33

The Role of Intranets Many companies have sophisticated and widespread intranets Detailed data retrieval Collaboration Personalized customer profiles Links to the Internet Web browsers and servers Intranets use Internet technologies TCP/IP network protocols HTML publishing and databases 17 - 33

Intranets Encryption Passwords Intranets are protected by… Firewalls Customers, suppliers, and other business partners can access an intranet via extranet links 18 - 33

Intranets as Information Portals 19 - 33

Extranets Network Links Uses Internet technologies to connect the intranet of a business to the intranets of another Virtual Private Networks Direct private network links, or private secure Internet links between companies Unsecured Extranet Link between a company and others via the Internet, relying on encryption of sensitive data and firewall security systems 20 - 33

Extranet Connectivity and Value 21 - 33

Telecommunications Network Model l A telecommunications network is any arrangement where… – A sender transmits a message to a receiver – Over a channel – Consisting of some sort of medium 22 - 33

Types of Communications Networks Wide Area Local Area Communication Networks Peer-to-Peer Virtual Private Client/Server 23 - 33

Wide Area Network (WAN) Covers a large geographic area 24 - 33

Local Area Network (LAN) Connects computers within a limited physical area, such as an office, classroom, or building 25 - 33

Virtual Private Network 26 - 33

Client/Server Network 27 - 33

Network Computing l Networks are the central computing resource of the organization – Thin clients provide a browser-based user interface for processing applets l Thin clients include – Network computers – Net PCs – Other low-cost network devices or information appliances 28 - 33

Network Computing 29 - 33

Peer-to-Peer Networks Central Server Architecture P 2 P file-sharing software connects all PCs to a central server The server sends the requesting PC a list of links to all active peers who have the file Clicking a link connects the two PCs and automatically transfers the file to the requesting PC 30 - 33

Peer-to-Peer Networks Pure Peer-to-Peer Architecture No central directory or server File-sharing software connects one PC to another online user When you request a file, the software searches every online user, then sends you a list of active file names Clicking a link automatically transfers the file from that user’s hard drive to yours 31 - 33

Central Server Peer-to-Peer Networks Advantages Disadvantages Can better protect the integrity and security of the content and users of the network Directory server can be slowed or overwhelmed by too many users or technical problems 32 - 33

Peer-to-Peer Network Diagrams 33 - 33