Telecommunications and Networks Chapter 6 Telecommunications and Networks

Learning Objectives Understand the concept of a network. Apply Metcalfe’s law in understanding the value of a network. Identify several major developments and trends in the industries, technologies, and business applications of telecommunications and Internet technologies. Provide examples of the business value of Internet, intranet, and extranet applications.

Learning Objectives Identify the basic components, functions, and types of telecommunications networks used in business. Explain the functions of major components of telecommunications network hardware, software, media, and services. Explain the concept of client/server networking. Understand the two forms of peer-to-peer networking. Explain the difference between digital and analog signals.

Learning Objectives Identify the various transmission media and topologies used in telecommunications networks. Understand the fundamentals of wireless network technologies. Explain the concepts behind TCP/IP. Understand the seven layers of the OSI network model.

Network Concepts Network An interconnected chain, group or system Number of possible connections on a network is N * (N-1) / 2 Where N = number of nodes (points of connections on the network) Example, if there are 10 computers on a network, there are 10 * 9 / 2 = 45 possible connections

Trends in Telecommunications

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

Internet2 Next generation of the Internet High-performance network In use at several hundred universities, scientific institutions, communications corporations Internet2 may never replace the Internet. May remain a scientific and government network.

Business Value of Telecommunication Networks

The Internet 2.27 billion users (2012) No central computer system No governing body No one owns it With all these users, Metcalfe’s law suggests the possible connections are extraordinary

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

Using the Internet for business

Business value of the Internet

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

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

Extranet Uses

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

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

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

VPN

Client/Server networks Clients: End user personal computers or networked computers Interconnected by LANs Servers: manage networks Processing shared between clients and servers Two tiered client server includes just client and server Maybe connected to optional super servers

Client/Server Network

Network Computing Networks are the central computing resource of the organization Thin clients: network computers and other clients provide a browser-based user interface Thin client means that very little processing is done on the client. Most the processing is done on the server. Three-tier model includes thin clients, application servers and database servers

Peer-to-peer networks Networks that connect from one PC to another PC Common use is the downloading and trading of files With a central server architecture, P2P file-sharing software connects your PC to a central server that contains a directory of all the other users in the network. When you request a file, the server searches the directory for any other users who have that file and are online. You click on list and make the P2P connection. Napster used this architecture. Pure P2P has no central directory or server.

Peer-to-Peer Network

Telecommunications Media Twisted-pair wire: Ordinary telephone wire Copper wire twisted into pairs Twisted pair transmission speeds range from 2 million bits per second (unshielded) to 100 million bits (shielded) Coaxial cable from 200 million bits to over 500 million bits per second Fiber optic cable as high as trillions of bits per second. Uses light elements instead of electricity Source: Phil Degginger/Getty Images.

Telecommunications Media Coaxial cable: Sturdy copper or aluminum wire wrapped with spacers to insulate and protect it Twisted pair transmission speeds range from 2 million bits per second (unshielded) to 100 million bits (shielded) Coaxial cable from 200 million bits to over 500 million bits per second Fiber optic cable as high as trillions of bits per second. Uses light elements instead of electricity Source: Ryan McVay/Getty Images.

Telecommunications Media Fiber-optic cable: One or more hair-thin filaments of glass fiber wrapped in a protective jacket Twisted pair transmission speeds range from 2 million bits per second (unshielded) to 100 million bits (shielded) Coaxial cable from 200 million bits to over 500 million bits per second Fiber optic cable as high as trillions of bits per second. Uses light elements instead of electricity Source: CMCD/Getty Images.

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 Need to connect houses with a higher-speed technology. One solution is cable connection. Another solution is to skip the wires and use satellite or wireless.

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

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

Wireless Web Connect portable communications devices to the Internet Very thin client such as telephone, pager, PDA WAP: wireless application protocol WML: wireless markup language

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 Multiplexer - Allows a single communications channel to carry simultaneous data transmissions from many terminals

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

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

Network Topologies

Network Architectures & Protocols Protocol: standard set of rules and procedures for the control of communications in a network Transmission Control Protocol / Internet Protocol (TCP/IP) A five layer telecommunications protocol used by the Internet

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

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