Transcript 8[1]. Chapter 9 Norton

Chapter 9
Network Basics
Network Definition
 A network is a set of technologies that is used to connect
computers
 The network allows communication and collaboration
between users
 Networking is a group of technologies working together.
These technologies include:
Media is the wiring that connects the computers
2. Hardware needs to be installed to connect the media
3. Software needs to be written to handle networks
1.
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The Uses of a Network
1.
Simultaneous access to data
 Network server is a central computer with large storage device
and other resources that all users can share
 Data files are shared
 File servers
 Shared files stored on a server
 Access can be limited
 Software can be shared
 Application servers
 Site licenses
 Network versions
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Network server
Users can share data stored on central server
The Uses of a Network
2.
Shared peripheral device
 Printers and Faxes are commonly shared
 Reduces the cost per user
 Devices can be connected to the network
 Print servers control network printing
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The Uses of a Network
3.
Personal communication
– Email
• Instantaneous communication
– Conferencing
• Tele conferencing
1.
Videoconferencing
2.
Audio-conferencing
3.
Data-conferencing
– Voice over IP
• Phone communication
over network wires
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The Uses of a Network
4.
Easier data backup
 Backup copies data to removable media
 Server data backed up in one step
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Assignment No. 2
What are the Network Operating Systems (NOS).
Describe their roles?
b) Comparison of features of Linux and Windows operating
systems
c) Write advantages and drawbacks of Internet in our life. (at
least 5 each)
a)
Due date: 05 February, 2009
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Common Network Types
 Local Area Network (LAN)
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Contains printers, servers and computers
Systems are close to each other
Contained in one office or building
Organizations often have several LANS
 Wide Area Networks (WAN)
 Two or more LANs connected
 Over a large geographic area
 Typically use public or leased lines
 Phone lines
 Satellite
 The Internet is a WAN
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Hybrid Network Types
 Metropolitan Area Network (MAN)
 Large network that connects different organizations
 Shares regional resources
 A network provider sells time
 Typically covers an area of between 5 and 50 km diameter
 Campus Area Networks (CAN)
 A LAN in one large geographic area
 Resources related to the same organization
 Each department shares the LAN
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LAN, MAN, WAN
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Hybrid Network Types
 Home Area Network (HAN)
 Small scale network
 Connects computers and entertainment appliances
 Found mainly in the home
 Personal Area Network (PAN)
 Very small scale network
 Range is less than 2 meters
 Cell phones, PDAs, MP3 players
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How Networks Are Structured
 Server based network
 Node is any network device
 Servers control what the node accesses
 Users gain access by logging in
 Server is the most important computer
 Client/Server network
 Nodes and servers share data roles
 Nodes are called clients
 Servers are used to control access
 Database software
 Access to data controlled by server
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How Networks Are Structured
 Peer to peer networks (P2P)
 All nodes are equal
 Nodes access resources on other nodes
 Each node controls its own resources
 Most modern OS allow P2P Network
 Distributing computing is a form of P2P
 Kazaa is a P2
 Possible threats?
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Network Topologies
 Topology
 Logical layout of wires and equipment
 Choice affects
 Network performance
 Network size
 Network collision detection
 Packets
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 Pieces of data transmitted over a network
• Packets are created by sending node
• Data is reassembled by receiving node
 Packet header
• Sending and receiving address
 Packet payload
• Number and size of data
• Actual data
Network Topologies
1.
Bus topology
– Also called linear bus
– One wire connects all nodes
– Terminator ends the wires
– Advantages
• Easy to setup
• Small amount of wire
– Disadvantages
• Slow
• Easy to crash
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Network Topologies
2.
Star topology
– All nodes connect to a hub
• Packets sent to hub
• Hub sends packet to destination
– Advantages
• Easy to setup
• One cable can not crash network
– Disadvantages
• One hub crashing downs entire network
• Uses lots of cable
– Most common topology
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Network Topologies
3.
Ring topology
– Nodes connected in a circle
– Tokens used to transmit data
• Nodes must wait for token to send
– Advantages
• Time to send data is known
• No data collisions
– Disadvantages
• Slow
• Lots of cable
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Network Topologies
4.
Mesh topology
 All computers connected together
 Internet is a mesh network
 Advantage
 Data will always be delivered
 Disadvantages
 Lots of cable
 Hard to setup
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Network Media
 Links that connect nodes in a network
 Choice can be made depending upon the following factors:
 Speed of transmission
 Size of network
 Security
 Can be broadly categorized as:
 Wire-Based Media
 Wireless Media
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Wire Based Media
1.
Twisted-pair cabling
 Most common LAN cable
 Called Cat5 or 100BaseT
 Four pairs of copper cable
twisted
 May be shielded from
interference
 Speeds range from
1 Mbps to 1,000 Mbps
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Wire Based Media
Coaxial cable
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Fiber-optic cable
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Similar to cable TV wire
One wire runs through cable
Shielded from interference
Speeds up to 10 Mbps
Nearly obsolete
Data is transmitted with light pulses
Glass strand instead of cable
Immune to interference
Very secure
Speeds up to 100 Gbps
Wireless Media
 Data transmitted through the air
 LANs use radio waves
 WANs use microwave signals
 Easy to setup
 Difficult to secure
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Network Hardware
 Network interface cards
 Network adapter
 Connects node to the media
 Unique Machine Access Code (MAC)
 Network linking devices
 Connect nodes in the network
 Cable runs from node to device
 Crossover cable connects two computers
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Network Hardware
 Hubs
 Center of a star network
 All nodes receive transmitted packets
 Slow and insecure
 Switches
 Replacement for hubs
 Only intended node receives transmission
 Fast and secure
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Network Hardware
 Bridge
 Connects two or more LANs together
 Packets sent to remote LAN cross
 Other packets do not cross
 Segments the network on MAC addresses
 Router
 Connects two or more LANs together
 Packets sent to remote LAN cross
 Network is segmented by IP address
 Connect internal networks to the Internet
 Need configured before installation
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Network Hardware
 Gateway
 Connects two dissimilar networks
 Most gateways contained in other devices
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Network Cabling
 Cabling specifications
 Bandwidth measures cable speed
 Typically measured in Mbps
 Maximum cable length
 Connector describes the type of plug
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Network Cabling
 Ethernet
 Very popular cabling technology
 10 Base T, 10Base2, 10Base5
 Maximum bandwidth 10 Mbps
 Maximum distances100 to 500 meters
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Network Cabling
 Fast Ethernet
 Newer version of Ethernet
 Bandwidth is 100 Mbps
 Uses Cat5 or greater cable
 Sometimes called 100Base T
 Requires a switch
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Network Cabling
 Gigabit Ethernet
 High bandwidth version of Ethernet
 1 to 10 Gbps
 Cat 5 or fiber optic cable
 Video applications
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Network Cabling
 Token ring
 Uses shielded twisted pair cabling
 Bandwidth between 10 and 25 Mbps
 Uses a multiple access unit (MAU)
 Popular in manufacturing and finance
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Network Protocols
 Language of the network
 Rules of communication
 Error resolution
 Defines collision and collision recovery
 Size of packet
 Naming rules for computers
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Network Protocols
 TCP/IP
 Transmission Control Protocol/Internet Protocol
 Most popular protocol
 Machines assigned a name of 4 numbers
 IP address
 209.8.166.179 is the White House’s web site
 Dynamic Host Configuration Protocol
 Simplifies assignment of IP addresses
 Required for Internet access
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Network Protocols
 IPX/SPX
 Internet Packet Exchange/Sequenced Packet Exchange
 Older protocol
 Associated with Novell Netware
 Replaced by TCP/IP
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Network Protocols
 NetBEUI
 Network BIOS Extended User Interface
 Used by Windows to name computers
 Transmission details handled by TCP/IP
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Network Protocols
 Token ring
 Popular in manufacturing and finance
 Nodes communicate when they have the token
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Modem Communications
 Plain Old Telephone System (POTS)
 Standard phone line
 Also known as Public Switched Telephone Network (PSTN)
 Two-way voice communication
 Uses analog transmission techniques
 Data communication is slow
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Modem Communications
 Modems
 Modulator/Demodulator
 Modulator converts digital to analog
 Speed measured in bits per second (bps)
 Current fastest speed is 56 Kbps
 Quality of phone lines dictates speed
 V.92 is the current modem standard
 Several modem types
 Internal
 External
 Voice
 Fax
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Modem Communications
 Modem uses
 Connection to the Internet
 File transfer
 Uploading
 Downloading
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Digital Data Connections
 Digital phone lines
 Local telephone companies are upgrading
 Service will faster and more reliable
 New phones will be needed
 Modems will need to be upgraded
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Digital Data Connections
 Broadband connection
 Any data connection faster than 56 Kbps
 Common in business
 Becoming popular in home installations
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Digital Data Connections
 ISDN lines
 Integrated Services Digital Network
 Basic rate uses three channels
 Two data channels each support 64 Kbps
 Error correction channel
 Primary rate uses 24 data channels
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ISDN Connection
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Digital Data Connections
 T lines
 High-capacity voice/data lines
 Used to control phone and data
 Several variants
 T1 transmits at 1.544 Mbps
 T3 transmits at 44.736 Mbps
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Digital Data Connections
 DSL technologies
 Digital Subscriber Line
 Popular with home users
 Speeds range from 100 Kbps to 30 Mbps
 Asymmetrical DSL (ADSL)
 Upload speed slower than download speed
 Symmetrical DSL (SDSL)
 Requires a DSL modem
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Digital Data Connections
 Cable modem connections
 Popular with home and office users
 Speeds between 1 and 3 Mbps
 Requires a cable modem
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Digital Data Connections
 ATM
 Asynchronous Transfer Mode
 Efficient transfer of video and sound
 Requires a special NIC and hardware
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Wireless Networks
 Benefits
 No cable to pull
 Mobile devices access network resources
 Mobility and flexibility for office workers
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Wireless Networks
 Wireless 802.11
 Also called Wi-Fi
 IEEE standard
 Institute of Electronic and Electrical Engineers
 Several versions
 802.11b connects up to 11Mbps
 802.11g connects up to 56Mbps
 Use the same type of devices
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Wireless Networks
 Wireless Access Point
 Center of a wireless network
 WAP combined cover a larger area
 Range is 50 to 150 meters
 Extension points can extend range
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Wireless Networks
 Wireless Adapters
 Used by devices to connect
 Includes signal strength software
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Project
 Abstract Submission (next week)
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Chapter 9
End of Chapter