Chatper 1 Flashcards by Stephanie Launico

In __ , the Greeks used __ to established a rudimentary information networks.

700 BC
homing pigeons

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Around a millennium later, in __ , __ proved that a wire carrying an electric current could deflect a magnetized needle, opening the way for wire-based telegraph networks.

1819
Hans Oersted

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Three types of networks

– Word-of-mouth communication
– Telephone
– Computer

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Transmit information to person or group like word-of mouth.
Carry data, voice, and video
communications

Computer networks

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__ communication infrastructure
• Communication cables and radio waves
• Specialized equipment to connect networks

Telephone network

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Computer network components

– Computer hardware and software
– Print devices
– Network Devices

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System components linked using various media

– Copper wire
– Fiber-optic cables
– Radio waves
– Infrared waves
– Microwaves

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– Different network types
– Different terms for various network elements
– Processes about how networks should work

Master basic networking concepts

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Three types of computer networks

– Local area networks (LANs)
– Metropolitan area networks (MANs)
– Wide area networks (WANs)

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– Interconnects computers, printers, other equipment
– Consists of shared hardware and software resources in close physical proximity

LAN

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– Spans a greater distance than a LAN
• Up to 48 kilometers (about 30 miles)
– Links multiple LANs within city or __ region
• Typically uses fiber-optic/wireless connections
– LANs may be separately owned

MAN (metropolitan area network)

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– Composed of two or more LANs or MANs
– Connected across distance greater than 48 km
– May have constituent LANs on different continents

WAN (wide area network)

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– Links different users across one or more organizations
– Provides variety of resources
– Used to fulfill business, research, educational tasks
– Typically consists of several LANs

Enterprise network

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_network component
– Personal computer, server, mainframe, minicomputer, printer, fax, CD-ROM array, disk array

Node (or station)

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Nodes linked through communications media

Wire cabling,
fiber-optic cables,
radio or infrared waves

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Three network nodes important to users:

– Workstations
– Hosts
– Servers

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– Has CPU (central processing unit) and operating system
– Home to local applications such as Microsoft Office
– Runs network applications to access data on server or mainframe
– May fulfill roles as client and host

Workstation computer

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workstation accessing data or software on another computer

Client

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computer accessed for data or software

Host

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– Single computers offering multiuser access
– Repository for software applications and data files
– Host from two to as many as several thousand users
– Network operating system is key to capability

Servers

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– Board installed in computer or network device
– Attached to communication media by connector or antenna

NIC (network interface card)

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Two reasons for studying network history

– Shows how practices and concepts have evolved
– Provides social, political, technical context

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rooted in telegraph and telephone
systems

LANs/WANs

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Driving forces in networking technology

– Interpersonal communication
– Business transactions
– Entertainment products

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Three prominent uses of home networks

– Sharing files and printers – Accessing the Internet and entertainment resources – Connecting home resources

– Connecting home resources

Computers, Entertainment devices, Appliances

Three common ways to share printers

– Share workstation printer using operating system – Attach printer directly to network using built-in NIC – Utilize print server with multiple connections and NIC

No one can use printer if workstation off

Caveat

– Utilize print server with multiple connections and NIC

• Plug one or more printers into print server • Connect print server to network

– Configure Internet sharing in home with Windows XP – Can also be set up in Windows Server 2003

Internet Connection Sharing (ICS)

– Configure Internet sharing in home with Windows XP

• Create Internet connection with Windows XP computer • Link connected computer to network • Configure ICS in Windows XP

__opportunities with home networks – Connects digital devices with NIC to network – Uses media hubs to connect home _ center

Entertainment

__ can be network devices – Example: refrigerators with digital message boards • Message boards linked to Internet

Home appliances

Other control features enhanced in home networks

– Temperature settings – Turning music on/off – Managing lighting systems

* Offices greatly enhanced through networks * Networks increase productivity and lower costs

Using a Network in an Office

Two ways networks save time and money

– Share information without leaving office – Telecommute to office via home network

_served by well-planned network – Illustrate using two companies selling specialty food

Business strategy

– Efficiency most likely rewarded with more orders

Company one handles more volume

• Advantages to networking office equipment • Networking capabilities enhance business of any size

Connecting Office Resources

Resources shared when connected to a network

– Files – Printers – CD-ROM arrays – Fax machines – Internet connectivity – Internet telephony – Specialty printers, such as plotters – Network conferencing devices – Network storage through disk arrays – Centralized tape or CD backups of critical files

Distinguish network types using four properties

– Communications medium – Protocol – Topology – Network type (private versus public)

– LAN boundaries based on communication medium changes

Examining communications medium

– Formatting and transmission of data • Discrete units of data called packets or frames

Examining protocols

– Two components • Physical layout of network cables and devices • Logical path followed by network packets or frames – Example: Logical path of frames follows star pattern

Examining topology

– Often change at network boundary – Example: beginning/end points of public and private networks

Examining network types

– Private network tunnels through larger network – Restricted to designated member clients

Virtual private network (VPN)

Physical layout combined with logical path

Topology

Pattern of physical layout

Cable plant

Cable plant: pattern of physical layout

– Wired networks – Wireless networks

Wired networks

Cabling laid in office, Building, Campus

Wireless networks

Types of antennas, Devices, Direction of transmission

– Cable between each station on network – Analogy: mountain climbers connected by a rope

Decentralized network layout

– Each station physically connected to central device – Analogy: star with workstation as its points

Centralized network layout

Main topologies:

bus, ring, star, and mesh

Hybrid topologies:

star-bus, star-ring

– Terminator attached to each end of bus cable segment

Bus topology

– Detected by all nodes on segment – Given time limit to reach destination

Transmitting packet across bus

– Develops standards for network cabling, transmission – Specifies length of bus segment

IEEE (Institute of Electrical and Electronics Engineers)

__ end of physical segment – Functions as resistor that absorbs signal

Terminator signals

__ on bus networks – Prevents signal reflection back on to covered path

Terminator critical

– Requires less cable than other topologies – Easy to extend bus with a workstation

Advantages of bus design

– High management costs • Single defective node can take down entire network – Can become quickly congested with network traffic

Disadvantages of bus topology

Continuous data path – Workstations attached to cable at points around ring

Ring topology

– Easier to manage than bus – Handles high volume network better than bus – Suited to transmitting signals over long distances

Advantages to ring topology

– More expensive to implement than bus – Fewer equipment options than bus

Disadvantages to ring topology

_ multiple nodes attached to central device (hub, switch, router) – Cable segments radiate from center like a star – Example: workstations connected to switch

Star topology

– Start-up costs comparable to ring topology – Easier to manage, defective nodes quickly isolated – Easier to expand by connecting nodes or networks – Offers better equipment and high-speed options

Advantages of star topology

– Failure of central device may cause network failure – Requires more cable than bus

Disadvantages of star topology

– Each radiating finger is separate logical bus segment – Each segment terminated at both ends

Star-bus (star-wired) topology

– No exposed terminators – Connect multiple central devices to expand network – Connection between central devices is a backbone • Backbone enables high-speed communication – Central devices have built-in intelligence – Many equipment and high-speed options available

Advantages of star-bus topology

– Hub or access unit acts as linking device – Transmission using logical communication of ring – No need for built-in terminators

Star-ring (star-wired) topology

– Every node connected to every other node in network * If link breaks, nodes can still communicate

Mesh topology

_ used less on LANs – Expensive to implement _ often used in MANs and WANs

Mesh topology

Step 1: _ – Example: Telecommunications-based WAN vs. satellite-based WAN

Understand protocols, access methods, topologies

Step 2: _ – Example: Different media for backbone and internal network

Understand physical equipment used

• Step 3: _ – Structured wiring and networking – Designing for multimedia and client/server applications – Taking advantage of LAN and WAN characteristics

Understand basic network design principles

Step 4: _ – Types of computers used as well as location – Software applications used and resources required – Patterns in organization relative to network use – High and low network use periods – How to simplify troubleshooting and maintenance – Determine security need for the network – Anticipate how growth affects network resources

Assess nature of home, office, organization

Four components of solid design

– Star-bus hybrid topology – Switch connecting computes in middle of star layout – Share certain information on network – Share printers on network

– Star-bus economical to implement and maintain – Use of switch satisfies need for fast communication – Resource sharing using peer-to-peer network – Internet access easily added

Rationale for design

Essential design knowledge:

protocols, topologies, equipment, principles, organization needs

Chief advantage of network

Resource sharing