Technology in Action Chapter 12 Behind the Scenes

Networking Advantages • Networks – Increase productivity – Enable the sharing of hardware resources – Facilitate knowledge sharing – Enable the sharing of software – Facilitate Internet connectivity – Enable enhanced communication Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 2

Client/Server Networks • Server-based network – Clients and servers • Data flows efficiently • Servers respond to requests from clients • Servers perform specific tasks • Scalable • Centralized Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 3

Classifications of Client/Server Networks • LAN – Local area network – Computers linked over

Classifications of Client/Server Networks • WAN – Wide area network – Computers linked over large geographic locations • MAN – Metropolitan area network – Computers linked within a city or county Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 5

Classifications of Client/Server Networks • PAN – Personal area network – Wireless devices connected in close proximity to each other • Intranet – Private corporate network – Protected by a firewall Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 6

Classifications of Client/Server Networks • Extranets – Only certain corporations or individuals can access – Useful for enabling electronic data interchange – Use virtual private networks (VPN) for security added security measures Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 7

Constructing Client/Server Networks • • Servers Network topologies Transmission media Network operating system (NOS) software • Network adapters • Network navigation devices (routers) Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 8

Servers • Number and types of servers depend on network size and workload • Dedicated servers: (described below) – Perform one specific function • Authentication servers – Keep track of network logins and services available • File servers – Store and manage files Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 9

Servers • Print servers – Manage client-requested printing jobs – Create print queue (prioritize print jobs) • Application servers – Act as a storage area for application software • Database servers – Provide clients with access to database information • E-mail servers – Process and deliver incoming and outgoing e-mail (anti-virus, anti-spam, anti-spyware, firewall) Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 10

Servers • Communications servers – Handle communications between networks, including the Internet (firewall, anti-hacking) – Often the only device on the network directly connected to the Internet • Web servers – Host a Web site available through the Internet – Markup pages, interaction with user Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 11

Network Topologies • The physical or logical layout of computers, transmission media, and other components • Types of network topologies – Bus topology – Ring topology – Star topology – Hybrid topology Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 12

Bus Topology • All nodes are connected in sequence on a single cable • Used most often in peer-to-peer networks • Networked computers communicate with each other • One computer transmits data at a time – Access methods avoid data collisions – Data is transmitted in packets – 512 -1024 bytes Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 13

Ring Topology • Nodes are laid out in a ring. • A token (data packet) flows in one direction from device to device. • Recent versions have data transfer rates of up to 100 Mbps. Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 14

Star Topology • Nodes connect to a central communications device (switch or hub). • A node sends a signal to the switch, which retransmits it to the destination node only. • Hub-sends to all nodes • A node accepts only signals addressed to it (? ). Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 15

Avoiding Data Collisions on an Ethernet Network Copyright © 2010 Pearson Education, Inc. Publishing

Transmission Media • The routes data takes to flow between devices on a network • Wired – Twisted pair – Coaxial – Fiber-optic • Wireless • -usually microwave, could be RF Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 17

Choosing a Cable • • Maximum run length Bandwidth Bend radius Cable cost Cable and installation costs Susceptibility to interference Signal transmission methods Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 18

Twisted Pair Cable • Pairs of copper wire twisted around each other • Twists make the wires less susceptible to interference • Shielded twisted pair (STP) – Layer of foil shielding • Unshielded twisted pair (UTP) – Cat 5 E: Bandwidth 200 Mbps – Cat 6: Bandwidth 1 Gbps – No foil layer Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 19

Coaxial Cable • Four components – Copper core – Nonconductive insulating material – Braided

Fiber-Optic Cable • Components include – Glass or plastic fibers – Cladding – Outer jacket • Uses light impulses to transmit data • Immune to interference Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 21

Wireless Media 802. 11 Standard • Wi-Fi (short for Wireless Fidelity) – 802. 11

Network Operating Systems (NOS) • Provide the protocol that controls the communication among devices on the network • Many modern OSs include NOS client software • Major network operating systems – Windows Server 2008 – UNIX – Novell Open Enterprise Server Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 23

Network Adapters • Devices that enable computers to communicate on a network • Network interface cards (NICs) • Three functions – Generate network transmission signals – Create data packets – Act as information gatekeepers • Ethernet compliant • Wireless NICs Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 24

Network Navigation Devices • Media Access Control (MAC) address – Six two-digit numbers (such as 01: 40: 87: 44: 79: A 5) – Physical address of network adapter – Internal network identification Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 25

Network Navigation Devices • Switches and bridges – Send data on a specific route through the network – Bridges send data between collision domains • Routers – Send information between two networks Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 26

Network Navigation Devices • Repeaters – Amplify a signal and retransmit it – Extend cable runs • Hubs – Transmit signals; have multiple ports • Receive a signal from a device • Reconstruct the signal • Transmit the signal to all ports on the hub (amplifies also) Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 27

Network Security Threats • Human errors and mistakes • Malicious human activity – Current and former employees hacking or planting viruses • Natural events and disasters – Hurricanes, floods, fire – Disaster Recovery Plan Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 28

Network Security • Firewalls – Prevent access to the network by unauthorized users – Composed of software and/or hardware – Screen and validate data packets – Bastion host/proxy server Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall 29