Dammam Community College

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Dammam Community College

• Network Overview

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Advantages of networks

• Enable sharing of files
• Enables sharing of resources
• It saves time
• Internet access

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What is a Network ?

• Two or more computers connected together by a
  cable.
• LAN - Local Area Network
• MAN - Metropolitan Area Network
• WAN - Wide Area Network

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Basic Network Components

• Network Interface Cards - NIC
• Network cabling connections
• Servers Workstations
• Network Operating System NOS

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Extending a LAN

• Repeaters
• Bridges
• Routers
• Gateways

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Network Interface Card

• Interrupt (IRQ) request line
• Base I/O port address
• Base memory address
• Direct memory access (DMA) request line

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Basic Types of LANs

• Peer-to-Peer Two computers participating equally
  in the network.
• Server Based Security and other network
  functions are provided by a dedicated server.

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Network Elements

• Sending Computer
• Receiving Computer
• Protocol
• Media - Wire or Wireless

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Network Protocols

• A protocol is a set of rules that govern network
  communication.
• A protocol suite is a group of protocols that can
  be used together.
• The standard protocols are
• Internetwork Packet Exchange/Sequenced Packet
  Exchange (IPX/SPX)
• Networked Basic Input/Output System/NetBIOS
  Enhanced User Interface (NetBEUI)
• Transmission Control Protocol/Internet Protocol
  (TCP/IP)
• AppleTalk
• Data Link Control (DLC)

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Protocols Summary

• Protocols - A set of rules for a network
• Examples
• TCP/IP
• TELNET
• IPX/SPX
• NET BEUI
• To cater for the following types of networking
  technology
• Ethernet
• Fast Ethernet
• Token Ring
• FDDI

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Main Types of Cable

• Coaxial Cable
• Twisted Pair
• Fiber Optic

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Network Cabling
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Cabling types and advantages
Three different types of network cabling and
their advantages are 1. Twisted pair cable is
readily available, easy to install and
inexpensive 2. Coaxial cable is standard
technology that resists rough treatment and EMI,
can transmit over longer distance than twisted
pair 3.Fibre Optic cable is immune to EMI and
detection outside and provides reliable and
secure media with high bandwidth
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Types of Cable Connectors

• BNC Connector
• RJ-45 Connector
• Duplex SC Connector

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Ethernet Cable Summary

• Specification Cable Type Maximum length
• 10BaseT Unshielded Twisted Pair 100 meters
• 10Base2 Thin Coaxial 185 meters
• 10Base5 Thick Coaxial 500 meters
• 10BaseF Fiber Optic 2000 meters

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LAN Communication

• Ethernet uses Carrier Sense Multiple Access with
  Collision Detection (CSMA/CD) as well as bus
  topology.
• Token ring allows only the station holding the
  token to transmit data.

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LAN Topology

• Topology is the way the network is connected
  physically. Following are topologies
• Bus Topology
• Ring Topology
• Star Topology
• Mesh Topology
• Hybrid Topology

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BUS TOPOLOGY
PRINTER
WORKSTATION 1
WORKSTATION 2
WORKSTATION 3
SERVER
T-CONNECTOR
TERMINATOR
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Workstation 5
Workstation 4
server
RING TOPOLOGY
Workstation 3
printer
Workstation 2
Workstation 1
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Workstation 5
Workstation 4
server
MESH TOPOLOGY
Workstation 3
printer
Workstation 2
Workstation 1
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HYBRID TOPOLOGY
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Networking Essentials

• Local Area Network (LAN)
• Usually limited to short distances
• Owned by the organization that uses it
• Usually employs solid cable
• Transmission rates tend to be high in the range
  of 1Mbps to 100Mbps

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Networking Essentials

• Local Area Network

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Networking Essentials

• Wide Area Network (WAN)
• Usually owned by major telephone companies
• Cover extremely large areas
• Most common WAN protocol is TCP/IP (common for
  internet)
• Transmission rates are usually slower than LAN or
  MAN rates (2400bps to 128Kbps)
• Technology such as ATM is improving data
  transmission rates

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Networking Essentials

• Wide Area Network

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Networking Essentials

• Network Components
• Network Interface Card (NIC)
• Usually found in the form of an expansion card
• Can have multiple connector types
• Can be integrated into the motherboard
• Can be 8-bit, 16-bit ISA, VLBus or PCI
• Is used to connect the computer or PC to the
  network

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Networking Essentials

• Network Components (cont.)
• Network cable
• Coaxial cable
• Thinnet (10Base-2) and Thicknet (10Base-5)
• RG-59 used in broadband networks to support video
  and data
• Twisted pair
• Is used by dial-up modems for dial up connection
  to the internet
• Unshielded and Shielded twisted pair (UTP and
  STP)
• Category 1 to 5
• Fiber optic

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Networking Essentials

• Network Protocols
• TCP/IP
• Transmission Control Protocol/Internet Protocol
• The most widely used protocol suite in the world
• Most major NOSs support the use of TCP/IP
• Originally designed for WAN use
• Routable protocol that offers true
  internetworking and interoperability between
  disparate NOSs

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Common Topologies

• Bus Topology
• Computers in the network are connected to a
  single cable
• Main cable is called the backbone
• Signals from computers travel in both directions
• Cable must be properly terminated at both ends
• Only a single computer can transmit a signal at
  any given time

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Common Topologies

• Bus Topology

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Common Topologies

• Bus Topology
• Advantages
• Easy to apply and maintain
• Requires minimal amount of cabling
• Easy to extend by adding cable or adding
  repeaters
• Can be extended with the addition of hubs
  connected to the bus

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Common Topologies

• Bus Topology
• Disadvantages
• The speed of the network is directly related to
  the number of computers connected to the bus
• Damage to the cable at any location may bring
  down the entire network
• The network usually has to be taken down to add
  additional computers
• It may be difficult to locate a break or short in
  the cable without specialized equipment

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Common Topologies

• Star Topology
• All computers are connected to a central device
  called a hub
• Each signal is initially sent to the central hub
  and then either out to all computers (broadcast
  star network) or to the recipient computer
  (switched star network)
• Several star networks can be linked together

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Common Topologies

• Star Topology

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Common Topologies

• Star Topology
• Advantages
• Easy to expand
• If one computer fails or one cable connecting a
  computer fails, the rest of the network stays up
• Hubs can support different types of cable
• UTP is the least expensive type of cable

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Common Topologies

• Star Topology
• Disadvantages
• Failure of the central hub results in failure of
  the entire network
• Separate cables are required to connect each
  workstation to a hub
• The initial cost of the equipment is more than
  with a straight bus topology due to the added
  expense of the hubs and running separate cables
  to each computer

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Common Topologies

• Ring Topology
• All computers in the network are joined in a
  logical ring
• The actual appearance may look like the star
  topology
• The central network device, called an MAU, has a
  loop inside of it, which creates the ring
• utilises token-ring to transmit data around the
  network. If a token is free of data a
  transmitting computer grabs it to send data by it
  and on the receiving end the data is removed and
  free token passed on to the network

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Common Topologies

• Ring Topology
• Advantages
• Ring networks handle collisions more efficiently
  than bus networks
• No single computer can end up using the network
  all the time. This is theoretically possible in
  the bus topology.
• It is faster than the star topology
• Can be very long because each computer reinforces
  the message

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Common Topologies

• Ring Topology
• Disadvantages
• On a physical ring network, you must down the
  entire network to add or remove computers
• On a physical ring network, if a computer goes
  down the entire network may go down
• It may not be easy to locate a faulty computer or
  device on the physical ring network

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Common Topologies

• Ring Topology

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Connectivity Within Networks

• Hubs
• Hubs can be used to connect networks but are more
  commonly used to extend a network
• Most hubs will simply rebroadcast signals to all
  ports
• Intelligent hubs rebroadcast signals only to the
  actual destination port

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Connectivity Within Networks

• Repeaters
• Amplify signals on networks
• Most commonly used to increase the length of the
  network backbone
• Normally signals should not pass through more
  than two repeaters before reaching their
  destination

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Connectivity Within Networks

• Bridges
• Selectively sends signals from one segment to the
  other
• Can filter signals based on the protocol type
• Transparent bridges contain the addresses of each
  computer and calculate the shortest route to the
  destination computer
• Source-routing bridgessender determines the
  proper route

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Connectivity Between Networks

• Routers
• Connect independent networks
• Dynamic and static routers
• Distance-vector routing
• Each router sends its table to all other routers
  at regular intervals
• Link-state routing
• Instead of sending the entire table, only the
  changes are sent

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Connectivity Between Networks

• Gateways
• Provides all the connectivity, and even greater
  functionality of routers and bridges
• usually resides on a dedicated computer and acts
  as a translator between two completely dissimilar
  systems or applications
• Are slower than bridges or routers
• Also provide access to special services such as
  e-mail or fax functions

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Maintaining and Troubleshooting Networks

• Reduced bandwidth
• Loss of data
• Slow loading of programs and files
• Unauthorized software

• Traffic overloads
• Common mode failures
• Network security violations

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Cisco 1601
Cisco 2503
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Summary

• A network provides connections, communications,
  and services.
• Networks are either peer-to-peer or server-based.
  
• Network topology types are star, bus, and ring.
• A NIC connects the computer to the network.
• Network cable types are twisted-pair, coaxial,
  and fiberoptic.
• A network protocol provides the rules for network
  communications.
• Networks can be extended with repeaters, bridges,
  routers, and gateways.