Telecommunications and Networking Chapter 4 Telecommunications and Networking

Chapter Objectives To understand the basic performance characteristics of telecommunications and networking technologies. To have an appreciation for the trends in telecommunications technologies and how they influence technology options and decisions. To understand how it is possible to view telecommunications as an enabler of organizational communications. To appreciate the potential for distortion in organizational communications, and how information and telecommunication technologies may help to reduce distortion.

Organizational Communication Communication is the sharing of information between two or more entities. Organizational Communication is the sharing of information related to an organization activity between two or more individuals or organizational units. Sharing of information implies, collection, analysis, and transmission of information. Formal and Informal Communication

Communication Dyads A communication network is made of a series of communication dyads. A dyad consists of Sender Receiver Message Channel Medium

Distortion in Communication Communication Distortion is the transformation of the meaning of a message by intentionally or unintentionally altering its content. Lost Destroyed Modified or Altered Noise consists of disturbances in the communication process that interferes with the intended effect of the message.

Types of Distortion Distortion Intentional Unintentional Routing – the message gets routed to the wrong receiver or not at all. Delaying the message Modifying it the content of the message Summarizing Intentional Unintentional

Distortion Type Intentional Unintentional Routing Sending a message to wrong person; news leaks Not knowing where to send message; sending to wrong address Delaying Purposely waiting for a deadline to go by Not being able to send message due to overload Modifying Changing the message; destroying data Forgetting to include some material in message Summarizing Leaving negative data out Not having time to integrate all available material

Analog and Digital Data Analog signals are transmitted as sound waves along a channel such as a copper telephone wire Digital signals are transmitted as a series of bits or on/off signals A modem converts digital signals into analog signals and another modem can be used to convert analog signals back to digital signals. See Figure 4.6

Telecommunications Voice communications require: A source device A switching system A data channel A destination device Data communications is used to refer to telecommunications involving computerized data. Data traffic on the Internet doubles every 100 days.

Data Channels Bandwidth is used to describe the capacity of a communications medium bps, bits per second kHz, kilohertz and MHz, megahertz Narrowband (transmission speeds of 64 kbps or less) Wideband (transmission speeds between 64 kbps and 1.544 Mbps) Broadband (transmission rates of 1.544 Mbps or higher)

Data Channels Wireline Wireless Twisted pair copper Coaxial cable (cable television) Fiber-optic cable Wireless Infrared light Cellular telephone (analog or digital) Microwave Satellite (geostationary or low-earth)

Communication Protocol A communication protocol is essentially a set of codes or conventions used for facilitating communications between hardware and software. IP or Internet Protocol directs packets on the Internet. TCP or Transmission control protocol puts the packets in their correct sequence. HTTP or hyper text transfer protocol is used to transmit web pages over the Internet. Mobile IP provides IP routing for mobile devices.

Telecommunications ISDN or Integrated Services Digital Network is a set of standards that provide additional capabilities for copper wire. DSL or digital subscriber line technology refers to a a group of methods for transmitting at speeds up to 8 Mbps over copper wire. Cable Modems allow transmission of Internet traffic through the cable TV network.

Telecommunications T-carrier systems are digital transmission systems that take analog voice circuits and converts them to digital form for transmission. Companies typically lease T lines. Frame relay carries data packets over the system that vary in length and are referred to as frames. Fast Ethernet is a protocol that was designed originally local area networks.

Networks A computer network is used to connect multiple uses and computing devices together, using telecommunications technologies. Three classes of networks Local Area Network (LAN) Metropolitan Area Network (MAN) Wide Area Network (WAN) Two types of networks Server-based networks Peer-to-peer networks

LAN Components LANs employ both wireline and wireless communications Twisted pair cable, Coaxial cable, & Fiber optical cable Wireless Infrared light, & Radio waves A bridge connects two networks of the same type A router connects several networks A gateway is used to connect different types of networks.

Music Industry Napster and Gnutella Morpheus and KaZaA Allow users to swap files using file sharing software. Napster allowed a users machine to become a client in a server-based network. Gnutella allows users to share files via a peer-to-peer network. Morpheus and KaZaA Tried peer-to-peer but still needed a central web server to provide service.

LAN Protocols Network communications are facilitated by some type of protocol. Ethernet Data are moved at 10 Mbps Fast Ethernet Data are moved at 100 Mbps Giga Ethernet Data are moved at 1 Gbps

LAN Protocols Other Network Protocols Token ring protocol Used in wired LANs IEEE 802.11 (WI-FI) Several variations designed for used in medium range, higher data rate applications. Range less than 150 yards and 22 Mbps are possible. Bluetooth is a radio frequency technology designed to provide wireless connectivity to a broad range of devices. Uses less power than most wireless LAN technologies Named for Danish King

LAN Topologies Topology is the configuration of the LAN (See Figure 4.15) Star, Ring, Bus Performance can be measured by the mode of the connection. Simplex transmission, messages can be carried in only one direction. Half-duplex, messages can be carried in both directions just not simultaneously. Full-duplex, messages can be carried in both directions simultaneously.

Intranets and Extranets An Intranet is a controlled, self contained grouping of information resources that can be accessed using Web browsers. An Extranet is similar to an Intranet but is designed to facilitate communications between two or more business partners.