BUSINESS DRIVEN TECHNOLOGY

Plug-In T2 Networks and

Telecommunications

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LEARNING OUTCOMES

1. Summarize the individual components of a computer network

2. Describe the three main network topologies

3. Explain the difference between the three main forms of network access methods

4. Summarize the difference between guided media and unguided media

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LEARNING OUTCOMES

5. Explain how a network operating system works

6. List the transmitting and receiving devices used in a computer network

7. Describe the function of TCP/IP

8. Summarize the use of a virtual private network (VPN)

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Introduction

• The core chapters introduced the concept of computer networks– Computer network (or just network) - a group of two

or more computer systems linked together using wires or radio waves over a geographical area

– Computer networks that do not use physical wires are called wireless

• This plug-in takes a detailed look at the key concepts that are integrating computer networks and data communications

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Introduction

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The Need for Networking

• A network provides two principle benefits:1. The ability to communicate 2. The ability to share

• A network supports communication among users in ways that other media cannot

• Groupware - software that supports team interactions and dynamics including calendaring, scheduling, and videoconferencing

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THE BENEFITS OF COMPUTER NETWORKING

• Store virtually any kind of information at, and retrieve it from, a central location on the network

• Combines the power and capabilities of diverse equipment providing a collaborative medium to combine the skills of different people, regardless of physical location

• Enables people to share information and ideas easily– They can work more efficiently and productively

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NETWORKING BASICS

• Networks are assembled according to certain rules:– Cabling, has to be a certain length

• Each cabling strand can only support a certain amount of network traffic, etc

– Topology - the actual physical organization of the computers (and other network devices) including connections

– Bandwidth - indicates how much information can be carried in a given time period (usually a second) over a wired or wireless communications link

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• The network industry refers to nearly every type of network as an “area network”:– Local Area Network (LAN) - connects network devices

over a relatively short distance – Wide Area Network (WAN) – is a geographically

dispersed telecommunications network– Metropolitan Area Network (MAN) - interconnects

users in a geographic area or region larger than a local area network, but smaller than a wide area network

NETWORKING BASICS

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NETWORKING BASICS

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Local Area Network (LAN) Basics

• A networked office building, school, or home usually contains a single LAN

• Sometimes one building will contain a few small LANs, and occasionally a LAN will span a group of nearby buildings

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Wide Area Network (WAN) Basics

• A WAN like the Internet spans most of the world

• A WAN is a geographically dispersed telecommunications network

• A WAN may be privately owned or rented, but the term implies the inclusion of public networks

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Metropolitan Area Network (MAN) Basics

• A MAN connects an area larger than a LAN but smaller than a WAN, such as a city– Example: A university or college may have a MAN that

joins together many of their local area networks situated around its campus

– From their MAN they could have several wide area network links to other universities or the Internet

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Networks – The Big Picture

• A network is made up of many physical elements:– Computers, printers, and other devices

• The manner in which all these items are connected is referred to as the network topology

• Networks must be arranged in a particular way in order to work properly

• Network topologies are further subdivided into two categories:

1. Physical topologies2. Logical topologies

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PHYSICAL TOPOLOGIES

• Physical topology - the actual physical organization of the computers on the network and its connections

• There are five principal topologies used in LANs: 1. Bus topology - all devices are connected to a central cable2. Star topology - all devices are connected to a hub 3. Ring topology - all devices are connected to one another in a closed loop4. Tree topology – combines the characteristics of the bus and star topologies5. Wireless topology - all devices are connected by a receiver/transmitter to a

special network interface card that transmits signals between a computer and a server; all within an acceptable transmission range

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PHYSICAL TOPOLOGIES

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PHYSICAL TOPOLOGIES

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PHYSICAL TOPOLOGIES

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NETWORK ACCESS METHODS (PROTOCOLS)

• Protocol - the predefined way that someone (who wants to use a service) talks with or utilizes that service

• The most popular LAN protocols include:– Token Ring– Ethernet– Fiber Distributed Data Interface (FDDI)

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Token Ring

• Token ring network - a LAN in which all computers are connected in a ring or star topology and a token-passing schema is used in order to prevent the collision of data between two computers that want to send messages at the same time

• Second most widely used protocol on local area networks • IBM originally developed the Token Ring network in the

1970s

• Data transfer rates of either 4 or 16 megabits per second

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Ethernet

• Ethernet - a physical and data layer technology for LAN networking

• Ethernet is the most widely installed LAN access method originally developed by Xerox

• When it first began to be widely deployed in the 1980s, Ethernet supported a maximum theoretical data rate of 10 megabits per second (Mbps)– Fast Ethernet standards have extended traditional Ethernet

technology to 100 Mbps peak– Gigabit Ethernet technology extends performance up to 1000

Mbps

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Ethernet

• Ethernet and Token Ring Network

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Fiber Distributed Data Interface (FDDI)

• Fiber Distributed Data Interface (FDDI) - a set of protocols for sending digital data over fiber optic cable

• FDDI networks are token-passing networks that supports data rates of up to 100 megabits per second

• FDDI networks are typically used as backbones for wide area networks

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• Fiber Distributed Data Interface

Fiber Distributed Data Interface (FDDI)

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Networking Hardware

• To be sent from one location to another, a signal must travel along a physical path

• The physical path that is used to carry a signal between a signal transmitter and a signal receiver is called the transmission medium– Network transmission media - the various types of

media used to carry the signal between computers – There are two types of transmission media:

1. Guided2. Unguided

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GUIDED MEDIA

• Guided media - transmissions material manufactured so that signals will be confined to a narrow path and will behave predictably

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GUIDED MEDIA

• The three most common types of guided media include twisted-pair wiring, coaxial cable, and fiber optic cable

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Twisted-Pair Wiring

• Twisted-pair wiring - a type of cable composed of four (or more) copper wires twisted around each other within a plastic sheath

• The wires are twisted to reduce outside electrical interference

• The RJ-45 connectors on twisted-pair cables resemble large telephone jacks

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Coaxial Cable

• Coaxial cable - cable that can carry a wide range of frequencies with low signal loss

• Consists of a metallic shield with a single wire placed along the center of a shield and isolated from the shield by an insulator

• Coaxial cable is divided into two different types: 1. Thinnet coaxial cable - similar to the cable used by cable

television companies2. Thicknet coaxial cable - similar to thinnet except that it is

larger in diameter

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Fiber Optic Cable

• Fiber optic (or "optical fiber") - the technology associated with the transmission of information as light impulses along a glass or plastic wire or fiber

• Optical fiber cable can transmit data over long distances with little loss in data integrity

• Optical fiber is not subject to interference

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Fiber Optic Cable

• Cable Summary

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UNGUIDED MEDIA

• Unguided media - natural parts of the Earth’s environment that can be used as physical paths to carry electrical signals– Examples include microwaves, infrared light waves, and

radio waves

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TRANSMITTING AND RECEIVING DEVICES

• Transmitting and receiving devices include:– Network adapters– Modems– Repeaters– Wiring concentrators, hubs, and switches– Bridges, routers, and gateways– Microwave transmitters– Infrared and laser transmitters– Cellular transmitters– Wireless LAN transmitters

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Network Adapters

• Network adapter - the hardware installed in computers that enables them to communicate on a network

• The most common form is designed to be installed directly into a standard expansion slot inside a PC

• Network adapters are manufactured for connection, including twisted-pair wire, coaxial cable, and fiber-optic cable

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Modems

• Modems - provide the means to transmit digital computer data typically over ordinary telephone lines– The transmitting modem converts the encoded data signal to an

audible signal and transmits it– A modem connected at the other end of the line receives the

audible signal and converts it back into a digital signal for the receiving computer

• Modems are commonly used for inexpensive communications between a network and geographically isolated computers

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Modems

Start

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Modems - Connecting to the Internet

Start

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Repeaters

• Repeaters - used to increase the distance over which a network signal can be propagated

• A signal travels through a transmission medium, it encounters resistance and gradually becomes weak and distorted

• The repeater receives the network signal and retransmits it at the original transmission strength

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Concentrators, Hubs, and Switches

• Concentrators, hubs, and switches - provide a common physical connection point for computing devices

• Most hubs and all wiring concentrators and switches have built-in signal repeating capability to perform signal repair and retransmission

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Bridges, Routers, and Gateways

• The devices used to interconnect network segments are divided into three classifications:1. Bridges2. Routers3. Gateways

• Bridges and routers - generally used to connect networks that use similar protocols; example includes TCP/IP

• Gateways - used to connect networks that use dissimilar protocols; examples includes TCP/IP and IPX

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Microwave Transmitters

• Microwave transmitters and receivers - commonly used to transmit network signals over great distances

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Infrared and Laser Transmitters

• Infrared and laser transmitters - similar to microwave systems: they use the atmosphere and outer space as transmission media

• They require a line-of-sight transmission path

• Useful for signaling across short distances where it is impractical to lay cable

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Cellular Transmitters

• Cellular transmitters - radio transmissions and therefore have the advantage of being able to penetrate solid objects

• A cellular base station at the center of each cell contains:– Low-power transmitters– Receivers– Antennas– Common control computer equipment

• Cellular devices are configured to operate at low power to avoid interfering with other cellular devices in the area

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Wireless LAN Transmitters

• Wireless LAN transmitters (or access points) - function like hubs and switches in a wired environment, only they propagate signals through radio waves or infrared light instead of wires

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The Network Operating System

• Network operating system (NOS) - an operating system that includes special functions for connecting computers and devices into a local area network

• The NOS is the “brain” of the entire network

• Network operating systems are divided into two categories:

1. Client-server 2. Peer-to-peer

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The Network Operating System

Start

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CLIENT-SERVER NETWORKS

• Client-server network - a versatile, message-based, and modular infrastructure that is intended to improve usability, flexibility, interoperability, and scalability as compared to centralized, mainframe computing

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CLIENT-SERVER NETWORKS

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THIN CLIENT-SERVER NETWORKS

• Thin clients - similar to terminals connected to mainframes, the server performs the bulk of the processing, and the client presents the interface

• Thin clients are usually devoid of floppy drives, expansion slots, and hard disks; consequently, the “box” or central processing unit is much smaller than that of a conventional PC

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PEER-TO-PEER NETWORKS

• Peer-to-peer networks - enable networked computers to function as both servers and workstations

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PEER-TO-PEER NETWORKS

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Internet Technology

• The Internet is the world’s largest computer network

• Two of the most influential technologies are:1. Transmission Control Protocol/Internet Protocol

(TCP/IP) suite 2. World Wide Web (WWW)

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TRANSMISSION CONTROL PROTOCOL/INTERNET PROTOCOL (TCP/IP)

• Transmission Control Protocol/Internet Protocol (TCP/IP) - a group, or suite, of networking protocols used to connect computers on the Internet

• TCP and IP are the two main protocols in the suite1. TCP provides transport functions, ensuring, among

other things, that the amount of data received is the same as the amount transmitted

2. The IP part of TCP/IP provides the addressing and routing mechanism

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• The TCP/IP suite of applications include:– File Transfer Protocol (FTP) - allows files to be

downloaded off or uploaded onto a network– Simple Mail Transfer Protocol (SMTP)-TCP/IP’s own

messaging system for e-mail– Telnet protocol - provides terminal emulation – Hypertext Transfer Protocol (HTTP) - allows Web

browsers and servers to send and receive Web pages– Simple Network Management Protocol (SNTP) -

allows the management of networked nodes to be managed from a single point

Transmission Control Protocol/Internet Protocol (TCP/IP)

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Transmission Control Protocol/Internet Protocol (TCP/IP)

• The TCP/IP Protocol Suite

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WORLD WIDE WEB

• The World Wide Web is a client-server environment

• Information is managed through Web sites on computers called Web servers

• Accessing Web sites is done through the use of client software (i.e., a browser) and the Internet’s HTTP

• Computers and Web sites on the Internet are linked through documents called Web pages written in HTML

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Intranet

• Intranet – an internalized portion of the Internet, protected from outside access, that allows an organization to provide access to information and application software to only its employees

• An intranet enables a business to collect, manage, and disseminate information more quickly and easily

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Extranet

• Extranet - a private network that uses the Internet protocol and the public telecommunication system to securely share part of a business's information or operations with suppliers, vendors, partners, customers, or other businesses

• Companies create extranets that:– Consolidate data gathering and share data– To jointly develop and share training programs– To coordinate project management for a common work project

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Virtual Private Network (VPN)

• Virtual private network (VPN) - a private WAN that uses the Internet as a low-cost WAN backbone to transport data between tow or more geographically separate sites

• Advantages that a VPN has over a dedicated-line WAN:– The cost of implementation– No need to lay cable or lease dedicated lines between the

remote sites needing to connect– Additional Internet connection would be required – Businesses can network remote offices into one large WAN and

provide access to the Internet

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• Intranet, Extranet, and VPN Technologies

Virtual Private Network (VPN)