Networking
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WALT: Networking Fundamentals
Know about: What a network is Network standards Different types of networks What’s required to connect to a network Advantages and disadvantages of being
connected to a network
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What is a Network?
Two or more computers connected together to share resources and information
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What is a Network?
Computers connected to network can be any type of computer
– Each computer could be configured with different operating system
– No restrictions other than having network software understand rules and language needed to recognize computer type and operating system
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Where the Personal Computer Fits
PC most commonly used tool to connect to network– Microprocessor chip is “brains”
of PC– Communicates with other
components of PC via internal connecting device called “bus”
– To communicate with external devices, PC needs interface card
To connect PC to network, need interface card for type of network, suitable cable, and appropriate software
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Networking Standards
When two or more computers interconnected to communicate and share resources, you have a network
Protocols are rules governing type of cables, interface cards, and electrical signal format
Also govern how information flows between computers on network called transport protocols:– indicates how computer needs to send information over
network – how receiving computer checks that information was
received correctly– how sending computer must address information so it
goes to correct destination computer Application level protocols determine how program on one
computer communicates with program on another computer
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Peer-to-Peer Networks
Inexpensive and easy to put together Ideal for home and small office networks Called peer-to-peer because all computers have equal
authority Protocols included in Microsoft Windows 95/98/ME but
several proprietary peer-to-peer network systems available also
Windows NT (or higher) has network component built in with more complex protocols to connect computers
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Client - Server Networks
Typical on large networks where one computer (network server) dedicated to controlling network traffic and managing resources
Provides better performance and security as server controls who can access what resources and when
Also called central server as all files stored here Server can be any type of computer with server software
installed, and users clearly identified with access rights Client computer can be any type of computer with network
card and appropriate software to connect to server
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Topologies - Structure
Star– All the network devices connected to a central computer which
is often used as the file server
Ring– Each of the devices on the network is connected in a ring or a
loop. (Each machine has a connection to the one previous and the one after it in the loop)
Bus– Each of the devices is connected directly to a main
communications line, called a bus
MESH– All the computers connected to each other
Click here to view animations on topologies
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Figure 8-5
Star Network Topology
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Star: Advantages and Disadvantages
Advantages of a Star– If one cable fails the other stations are not affected
– Consistent performance even under heavy use
– Reliable market proven system
– No problems with collisions of data since each station has its own cable to the server
– Easy to add new stations without disrupting the network
Disadvantages of a Star– May be costly to install because of the cable lengths
required
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Bus Network Topology
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Bus: Advantages and Disadvantages
Advantages of a Bus– Easy and inexpensive to install as it requires the
least amount of cable of the network types
– Easy to add more stations without disrupting the network
Disadvantages of a Bus– The whole network goes down if the main cable fails
at any point
– Cable failure is difficult to isolate
– Network performance degrades under a heavy load
– Information can be transmitted in either direction and occasionally there is data collision.
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Figure 8-7
Ring Network Topology
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Ring: Advantages and Disadvantages
Advantages of a Ring– No dependence on a central computer or file server and
each node controls communication to and from itself
– Transmission around the network is one way only
– High data transmission rates are possible
Disadvantages of a Ring– If one node breaks down transmission is disrupted
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Mesh Network Topology
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Mesh: Advantages and Disadvantages
Advantages of a MESH– Communication is not disrupted– Alternative routes to node points/machines– Security – packages can arrive/be sent via many
different routes– Backup – with multiple connections it is easier to
distribute the data in case of disaster Disadvantages of a MESH
– Cost• of cables required to link machines together• Of machines – similar spec machines required at
each location to be able to take over– Difficult to install and reconfigure
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LANs and WANs
Difference lies in who is responsible for cabling
– LAN network stays within building
– WAN if network crosses public street and uses publicly-supplied cabling for part of network
When computer or LAN connected to another computer or LAN in another city or country, public portion of WAN represented schematically by “cloud”
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Connecting to a Network
Standard network devices facilitate putting network together
Cabling comes in standard lengths complete with appropriate connectors
Which options, devices, or software you use depends on needs and requirements for network
Variety of connection or cabling options available to access information to or from network
– Newer connection types allow the data to be transferred between computer and network to flow much faster
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Connection/Cabling Options
Coaxial Wire with center wire surrounded with insulation and then grounded cover of braided wire.
Fiber Optics Made up of bundled glass or plastic fibers (threads) to transmit data.
Broadband Single wire that can handle multiple paths or channels
Wireless Work with radio frequencies for data transmission.
Infrared Wireless option works with infrared light waves to transmit data.
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The Network Interface Card (NIC)
To connect to network, PC must have network interface card (NIC)
Each NIC has unique number or address and connector appropriate for type of cabling chosen
Come in variety of styles and models appropriate for computer type being connected to network
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The Hub Connect PCs together to
form network
– Cable from NIC in each PC connects to port on hub
– Cable from hub required to connect to network
Relatively inexpensive to purchase and install
Main disadvantage of hub is all users connected to hub share equal maximum transfer speed
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Network Segments
If network has two or more network interface cards, each card considered a segment
Segments allow network traffic to flow faster, depending on which devices are used to manage amount of requests at network
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The Bridge
Connects network segments to handle network requests
Do not analyze or re-route messages which makes receiving information faster
Will not re-route or re-transmit information if anything is wrong with connection at either end until first transmission received completely
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The Router
Work similar to bridges except examine destination address of information and pass it on appropriate segments only
Bridges may be faster than routers but will not check information coming in
When installing wireless router to network, be sure to set up encryption security options to prevent unauthorized access from external sources using connection
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The Switch
Works similar to hub except that each user connected to switch has access to full bandwidth
Can also be used to join network segments
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The Firewall
Can be physical device or specialized software installed to prevent any unauthorized external access into any network connected to Internet
Designed to check any messages that travel through network and ensure it matches specified security requirements set up by company
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Benefits of Networking
Networking does not make individual workstations faster or more powerful!
Benefits of networking fall into two main categories:
– Communication
– Sharing of resources
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Communicating
To send information generated on stand-alone PC requires manual process whereas users on network send information electronically
Messages can be stored on network and are not lost if recipient isn’t available when messages sent or received
Many communication software allows users to instantly message someone else without using e‑mail – “Real time interaction”– Multiple users can participate in same conversation– Some limitations but can be minor issues in
exchange for ability to communicate with each other in real time
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Sharing Devices
Some devices can be expensive to set up on every PC and networking allows devices to be shared
– Can be cost savings for capital expenditures as well as productivity time for technical support or maintenance
Connecting devices shared by multiple users via network allows Network Administrator to perform updates or troubleshoot problems from server location
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Sharing Information
In network environment, files or folders on any disk can be set up to be shared
Whenever group of people want to share information, referred to as workgroup– Group of users who share business documents
transfer or save files to common network– Common network becomes centralized server
wherein server has control over which files are accessed and which users can use those files
Extremely helpful to network administrator for setting up rights or performing maintenance for workgroups
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Using Dedicated Servers Network
– Control network traffic and security– May perform same tasks and contain same information
as file or database server File
– High speed, high capacity hard drive, usually to handle back-up needs
Web– Stores information in web format and information
accessed with browser for company intranets Mail
– Manages high volume of internal and external e-mail Database
– Generally used in complex database applications where many users need to access data at same time
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Disadvantages of Networking
Dependency Big disadvantage in that organization’s activities
depend on network to be up and running
– If network fails, users lose access to information and ability to communicate electronically
– In some instances can work from local drive, but if company’s information stored and shared from server, cost of downtime may be more expensive in long term
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Disadvantages of Networking
Expensive For installation and maintenance If network complex with many users, additional
need and expense to employ network administrator
Need “disaster and recovery” plan, not just for theft or security breach, but also power outages or potential hardware failure
Setting up or upgrading a network server should always be discussed with network administrator or consultant who specializes in networks prior to making any decisions
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Disadvantages of Networking
Security Risk
Every person who logs into server has valid login id, and set up according to company’s standards
Every person who logs into server has valid password
When setting up new user, ensure name and information about user entered correctly
Audit each user to ensure access rights to programs and files are same
Requests received for access rights must have signature from corresponding manager
Delete users who no longer work for company
Do not ever give out passwords
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Disadvantages of Networking
Staff who work with network administrator should have own login id and password set up
Firewall set up for Internet connection that has been set up to check user id when sending or receiving messages
If access authorized for users outside network, ensure firewall checks these user ids when request received to access network from remote location
Restrict any users from being able to delete files from any folder on any network drives
Antivirus program installed on server is current and has latest protection files
Perform maintenance checks periodically as well to see what activities may have occurred
Encourage users to have latest updates of Windows on local computers
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Disadvantages of Networking
Loss of Autonomy or Privacy Obliged to work in network environment Privacy may be concern for confidential material “Private” drive set up on network for personal or
confidential files but network administrator can still see these files
If share computer, even though they log in with their own id, they can still see files on local
General business rules dictate that anything you work on a company computer belongs to the company, even though you may work on it on your own time
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Disadvantages of Networking
Viruses Vulnerable to virus attacks Some viruses, called worm viruses, specifically
target servers New viruses being created every day and it
becomes more prudent to read screen carefully before automatically opening message or clicking highlighted button on screen
All antivirus programs provide a feature to automatically detect in “real time”
Remember to run scan of computer on frequent basis and check for updates
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