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Networking BASICS. Introduction to Networking. Objectives. Define a computer network. List the four purposes of a network. Explain the elements of communication. List and describe the two types of networks. What Is a Computer Network?.
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Networking BASICS Introduction to Networking
Objectives • Define a computer network. • List the four purposes of a network. • Explain the elements of communication. • List and describe the two types of networks.
What Is a Computer Network? • A computer network is computers and devices connected together. • A single computer is limited to its own hardware and software. • The capabilities of a computer are increased when connected with other devices to form a computer network.
Purpose of a Computer Network • Summarized in a single word: sharing. • Individual computers are isolated. • Networked computers can share resources. • Three types of resources can be shared. • Networks also make computer management easier.
Share Software and Data • Application and utility software can be shared by all users across the network. • This requires only a single software copy to be purchased and maintained. • Data files can also be shared. • This makes data more accessible and maintains integrity.
Share Hardware • Sharing is an essential feature of a computer network. • This reduces costs and the work of support staff. • Printers, fax modems, scanners, hard drives, CD-ROMs, and DVDs can all be shared.
Improve Communications • Communication is essential in today’s businesses. • Computer networks can help in improved communications through groupware. • E-mail, electronic calendars, collaborative writing, and video conferencing are available.
Centralize Management • Support staffs are stretched to the limits. • Computer networks allow computers to be managed from one central location. • Software updates can be “pushed” to users’ computers. • Problems can be diagnosed over the network. • Training can be done over the network.
Types of Networks • Two types of network classifications • Classified by device that controls network • Classified by distance between devices
Peer-to-Peer Network • No single computer controls the network. • Each computer is the same (a peer) to all others. • It is suitable for small offices.
Server-Based Network • The network is controlled by a special high-powered server. • The server is dedicated to running the network. • Print and file servers, application servers, communication servers, and directory service servers are common.
Local Area Network • Network computers are located relatively close to each other. • They are generally limited to buildings owned by one organization. • They operate at high speeds. • They are low-cost networks.
Wide Area Network • Network computers are spread out over a larger area. • They generally cross public thoroughfares. • They are often managed by public carriers. • They operate at lower speeds. • They are a higher-cost network.
Summary • A computer network is defined as multiple computers and devices that are all connected together. By connecting the computers together, the capabilities of each computer are increased so the users can accomplish more. • The purpose of a computer network is to share. Application software, utility software, and the data that serves as input into the software can all be shared across a network. Computer hardware can also be shared on a computer network. Printers, fax machines, scanners, modems, hard disk drives, CD-ROM drives, and DVD drives are just a few of the hardware devices that can be shared across a computer network.
Summary (continued) • Computer networks can be important tools that help improve communication between users. A special category of software that assists with communication over a computer network is known as groupware. Groupware refers to programs that help people work together collectively even if they are located remotely from each other. One of the most common groupware applications used across computer networks is electronic mail, or e-mail. Groupware services also include electronic calendars, collaborative writing software, and video conferencing. • The communication that takes place between devices on a computer network is known as telecommunications. Telecom-munications is defined as transmitting information over a distance and is generally considered to be a two-way transmission of voice, video, or data.
Summary (continued) • Computer networks allow the computers connected to the network to be managed from one central location. Software updates can be “pushed” across the network to all computers, thus eliminating the need for support staff to visit every office and perform the new installation. Problem diagnosis can be performed across the network. Centralized management can be used for training as well. • Computer networks are generally classified two different ways. The first classification of networks involves the device that actu-ally controls the network. In a peer-to-peer network, no single high-powered computer controls and manages the network. The computers collectively run the network instead of a special dedicated computer doing it. These networks are suitable for small offices that need to share a printer or computer data.
Summary (continued) • The second type of network classified by the device that con-trols the network is known as a server-based network. Unlike a peer-to-peer network, a server-based computer network is con-trolled by at least one special high-powered computer. These special computers are called servers, while the individual com-puters on the network are called clients. Servers are usually dedicated to running the network and do not function as clients. Instead, their sole job is to service requests quickly from the network clients and ensure the security of the software and hardware. There are many different types of specialized servers.
Summary (continued) • Networks can also be classified by geography or how close the devices are to each other. There are two categories of networks based on geography. The first is a local area network (LAN). A LAN is a computer network that has all the computers relatively close to each other. They operate at high speeds for a low cost. A wide area network (WAN) transmits over a public thorough-fare, such as a road, highway, railroad, or body of water. A WAN service must be purchased from a carrier. WANs are managed by the carrier instead of by the user. Compared to LANs, the cost of WANs is high and they operate at a low speed.
Networking BASICS Network Media
Objectives • Explain how data transmissions are sent and received. • List and describe the types of transmission media. • Describe the functions of a network interface card.
Types of Networks • There are two types of networks by which information is transmitted: • circuit switched networks • packet switched networks
Circuit Switched Network • There is a dedicated and direct physical connection between sender and receiver. • No other transmissions can take place while the connection is active. • Once the transmission is ended, other connections can be made with other devices. • It is ideal for voice communications because there are no interruptions from other devices or delays.
Packet Switched Network • This network requires data transmission be broken into smaller units called packets. • Each packet is sent independently through the network. • It is used for data transmission because data is not as time-sensitive as voice communication. • It allows multiple devices to share one line or frequency. • It facilitates error correction.
Transmission Media • Copper cables • Fiber optic cables • Wireless
Copper Cables • Thin coaxial • Shielded twisted pair (STP) • Unshielded twisted pair (UTP) • UTP rated by Category 1 - 6
Fiber Optic • This cable uses a thin cylinder of glass to send light impulses. • The cable consists of a strand of glass (core) surrounded by a glass tube (cladding). • Single mode - one light source flashes a light down the cable. • Multimode - supports many simultaneous light transmissions.
Wireless • Transmission is sent and received through invisible waves • Less expensive than copper or fiber optic lines. • Allows the user to move freely around the office or campus and still remain connected to the network • Fastest-growing segment of network media today
Wireless Transmissions • Infrared transmits data using infrared (IR) light. • IR shares many of the same properties as visible light . • Radio frequencysignals can be transmitted over radio waves similar to local radio station transmissions. • The signal comes in at a lower power level and does not reach as far.
Network Interface Card • The NIC serves as the connection between the personal computer and the network media. • It connects to the computer on its base by plugging into an expansion slot of the computer. • Another connection is accessible from the outside of the computer and has connections for the cables to plug into the network.
Network Interface Card • Changes from parallel to serial transmission • Creates packets • Determines when to send • Transmits packet
Summary • Switching involves moving (switching) the signal from one wire or frequency to another. A circuit switched network creates a dedicated and direct physical connection between the sender and receiver. No other transmissions can take place while the connection is active, but once the transmission is ended, other connections can be made with other devices. Circuit switching is ideal for voice communications. Computer networks sending data use packet switched networks. Packet switching requires that the data transmission be broken into smaller units called packets. Each packet is then sent independently through the network to reach the destination.
Summary (continued) • There are many different types of network media, yet they all can be classified into three major categories: copper, fiber optic, and wireless. Thin coaxial cable is approximately one-quarter of an inch in diameter, has a single copper wire at its center, and is surrounded by a layer of insulation. Around the insulation is a braided copper mesh channel, and everything is covered by a thick outer shield of insulation. Twisted pair cable has become the standard today for copper cabling used in computer net-works, replacing thin coaxial cable. Twisted pair cable is two insulated copper wires that are twisted around each other. Each pair is then bundled together with other pairs in a jacket. There are two types of twisted pair cables. Shielded twisted pair (STP) cables have a foil shielding on the inside of the jacket, which reduces interference. Unshielded twisted pair (UTP) cables do not have any shielding.
Summary (continued) • A fiber optic cable uses a very thin cylinder of glass, instead of copper, at its center. Fiber optic cables send light impulses instead of transmitting electrical signals. Wireless communica-tion uses no visible connection, such as a copper cable or fiber optic line, between the network devices. Instead, the transmis-sion is sent and received through invisible waves. Transmission signals can be sent by infrared light waves or radio frequency waves.
Summary (continued) • When connecting a personal computer to the transmission media on a LAN, hardware known as a network interface card (NIC) is used. A NIC serves as the connection between the personal computer and the network media. The NIC connects to the computer on its base by plugging into one of the expansion slots of the computer. The other connection, found on the side of the NIC, is accessible from the outside of the computer and has connections for the cables to plug into the network (or an antenna for wireless transmissions). These connections depend on the type of network media being used.
Networking BASICS Network Design
Objectives • List and describe the characteristics of the mesh, bus, ring, star, and hybrid topologies. • Tell what items should be considered when selecting a network topology.
Objectives (continued) • Define channel access method. • Give the advantages and disadvantages of contention, polling, token passing, and demand priority channel access methods.
Topologies • Physical layout of network devices • Four types: mesh, bus, ring, and star
Mesh Topology • It is also called a point-to-point topology. • Each device is connected directly to all other network devices. • It provides fault tolerance. • It is only found in wide area networks.
Bus Topology • It is a multipoint topology. • Each device shares the connection. • The bus has one starting and one ending point. • Packets stop at each device on the network. • Only one device at a time can send.
