Technology in Action Chapter 12 Behind the Scenes: Networking and Security 1
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 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 3
LAN Classifications of Client/Server Networks Local area network Computers linked over a small geographic region 4
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 5
PAN Classifications of Client/Server Networks Personal area network Wireless devices connected in close proximity to each other Intranet Private corporate network Protected by a firewall 6
Extranets Classifications of Client/Server Networks Only certain corporations or individuals can access Useful for enabling electronic data interchange Use virtual private networks (VPN) for security added security measures 7
Servers Constructing Client/Server Networks Network topologies Transmission media Network operating system (NOS) software Network adapters Network navigation devices (routers) 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 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) 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 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 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 13
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. Ring Topology 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 (?). 15
Avoiding Data Collisions on an Ethernet Network 16
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 17
Choosing a Cable Maximum run length Bandwidth Bend radius Cable cost Cable and installation costs Susceptibility to interference Signal transmission methods 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 5E: Bandwidth 200 Mbps Cat 6: Bandwidth 1 Gbps No foil layer 19
Coaxial Cable Four components Copper core Nonconductive insulating material Braided metal Plastic cover 20
Fiber-Optic Cable Components include Glass or plastic fibers Cladding Outer jacket Uses light impulses to transmit data Immune to interference 21
Wireless Media 802.11 Standard Wi-Fi (short for Wireless Fidelity) 802.11b 802.11a 802.11g Super G 802.11n 22
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 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 24
Network Navigation Devices Media Access Control (MAC) address Six two-digit numbers (such as 01:40:87:44:79:A5) Physical address of network adapter Internal network identification 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 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) 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 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 29
Network Firewall Layout 30