Chatper 1 Flashcards
In __ , the Greeks used __ to established a rudimentary information networks.
700 BC
homing pigeons
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
Three types of networks
– Word-of-mouth communication
– Telephone
– Computer
Transmit information to person or group like word-of mouth.
Carry data, voice, and video
communications
Computer networks
__ communication infrastructure
• Communication cables and radio waves
• Specialized equipment to connect networks
Telephone network
Computer network components
– Computer hardware and software
– Print devices
– Network Devices
System components linked using various media
– Copper wire
– Fiber-optic cables
– Radio waves
– Infrared waves
– Microwaves
– Different network types
– Different terms for various network elements
– Processes about how networks should work
Master basic networking concepts
Three types of computer networks
– Local area networks (LANs)
– Metropolitan area networks (MANs)
– Wide area networks (WANs)
– Interconnects computers, printers, other equipment
– Consists of shared hardware and software resources in close physical proximity
LAN
– 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)
– 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)
– 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
_network component
– Personal computer, server, mainframe, minicomputer, printer, fax, CD-ROM array, disk array
Node (or station)
Nodes linked through communications media
Wire cabling,
fiber-optic cables,
radio or infrared waves
Three network nodes important to users:
– Workstations
– Hosts
– Servers
– 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
workstation accessing data or software on another computer
Client
computer accessed for data or software
Host
– 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
– Board installed in computer or network device
– Attached to communication media by connector or antenna
NIC (network interface card)
Two reasons for studying network history
– Shows how practices and concepts have evolved
– Provides social, political, technical context
rooted in telegraph and telephone
systems
LANs/WANs
Driving forces in networking technology
– Interpersonal communication
– Business transactions
– Entertainment products
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
