LOCAL AREA NETWORK

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LOCAL AREA NETWORK

• Presented by
• Tan Teng Meng WET010148
• Chan Choi Ngor WET020019
• Philip Lim Loong Hin WET020144

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Table of Contents

• LAN Definition
• Presented by Tan Teng Meng
• LAN Topology and Device
• Presented by Chan Choi Ngor
• LAN Cabling, ATM and wireless LAN
• Presented by Philip Lim

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• Local Area Network (LAN)

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What is LAN?

• High speed, fault-tolerant data network
• Cover a relatively small geographic area
• Connects workstations, personal computers,
  printers, and others devices.

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LAN Technologies

• Ethernet
• Token Ring
• FDDI

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Ethernet

• Most widely-installed
• Specified in a standard, IEEE802.3
• Connected to the cable and compete for access
  using a CSMA/CD protocol
• shared media - media access is controlled on a
  first come, first serve basis
• 10BASE-T provides transmission speeds up to 10
  Mbps
• 100BASE-T provides transmission speeds up to 100
  Mbps

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Token Ring

• Second most widely-used
• Specified as IEEE 802.5
• Connected in a ring or star topology
• Provides for data transfer rates of either 4 or
  16 Mbps

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FDDI

• A set of ANSI and ISO standards for data
  transmission
• Can extend in range up to 200 km
• Based on the Token Ring protocol
• Used on the backbone for a WAN

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Advantages and Disadvantages with LANs
Advantages Disadvantages
Recourse Sharing Vulnerability
Communication Poor password
Central and routine back-ups costs
Users can login from wherever Installation
security Maintenance
Less Expensive Systems Training
Performance
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Types of LANs

• Server-based LAN
• Has a dedicated machine/computer, that has the
  file server software located on it.
• All the workstations point towards this computer
  for accessing the resources
• Peer-to-Peer LAN
• Small has the files server software installed
  on each of the workstations
• Acting as both a file server a workstation.

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LAN Transmission Methods

1. Unicast - a single packet is sent from the source
   to a destination on a network.
2. Multicast - consists of a single data packet that
   is copied and sent to a specific subset of nodes
   on the network
3. Broadcast - consists of a single data packet that
   is copied and sent to all nodes on the network

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LAN Topologies

• Physical topologies
• Bus topology
• Ring topology
• Star topology
• Extended star topology
• Hierarchical topology
• Mesh topology
• Logical topologies
• Broadcast topology
• Token passing

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Bus Topology

• uses a single backbone segment (length of cable)
• the hosts connect to it directly.

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Ring Topology

• connects one host to the next and the last host
  to the first

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Star Topology

• connects all cables to a central point ( Hub or
  Switch )

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Extended Star topology

• links individual stars together by linking the
  hubs or switches
• extend the length and size of the network

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Hierarchical topology

• similar to an extended star
• linking the hubs/switches together, the system is
  linked to a computer
• The computer controls the traffic on the topology

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Mesh topology

• is used when there can be absolutely no break in
  communications.

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Broadcast topology

• Each host sends its data to all other hosts on
  the network medium
• First come, first serve
• Is the way that Ethernet works

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Token Passing

• Controls network access by passing an electronic
  token sequentially to each host
• The host receives the token can send data on the
  network
• If the host has no data to send, it passes the
  token to the next host the process repeats
  itself

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Devices in LAN

• A LAN consists of PC and external hardware, named
  hosts.
• Apart from hosts, there are other devices
  functioning as the connecting medium
• Repeater
• Hub
• Bridge
• Switch
• Router

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Network Interface Card

• Printed circuit board, also called network
  adapter.
• Carries a MAC address ( Layer 2 device )
• Each hardware and PC in the network must have a
  NIC to be connected to a network.

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Repeater

• Used to lengthen the range in the network.
• Layer 1 device which receive and transmit the
  data.
• Will not check for error, or determine the
  destination.

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Hub

• Layer 1 device also called multi-port repeater
• Receive and transmit data without checking for
  error or consistency of data packet.
• Advantage decrease wiring and increase
  reliability.

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Bridge

• Operates via MAC address ( Layer 2 device )
• Connect different part of the LAN while filtering
  the traffic to keep local traffic local, yet
  allow connectivity to other parts.
• Keeps track on MAC address on each side

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Switch

• Layer 2 device also called multi port bridge.
• Filters data by switching data only to the port
  where the appropriate destination is located
• Can be used to segment networks.

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Router

• Layer 3 device used to regulate traffic
• Forward the data packet to appropriate host via
  IP address.
• It also examine data packets and choose the best
  path for it.
• Can connect different Layer 2 technologies.

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Wire / Cable

• Another essential component of a network, example
  LAN
• There are different wire / cable types to be
  chose based on the range and bandwidth the
  network requires.
• Example of cable
• UTP
• STP
• Fiber Optic
• Coaxial Cable

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Unshielded Twisted Pair

• Consists of 2 4 unshielded copper solid or
  stranded wires.
• Most network protocol using the UTP will require
  2 pairs of wires, one for transmission and one
  for reception.
• General choice of wiring in office and home, with
  the RJ45 connectors
• Comes in 5 categories based on the EIA/TIA
  standards

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Unshielded Twisted Pair ( cont )

• Advantage Inexpensive and easy to work with.
  Flexible and can fit in full conduits. Many
  people familiar with UTP.
• Disadvantage Prone to interference. Short range
  of distance.
• Speed and throughput 10 100 Mbps
• Media and connector size small
• Maximum range of connection 100m

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Shielded Twisted Pair

• Similar to the UTP in operation and design.
• Reduction of noise and interference, from both
  within and outside.
• More expensive and difficult to install compared
  to UTP

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Fiber Optic

• Cable with glass and plastic medium
• Uses light ( laser ) to transmit data.
• Multimode fiber is often used in LAN.
• Has a low error rate and degrading is lower. High
  performance and longer range.
• Expensive and difficult to implement.
• Normally used as backbone in a LAN.

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Fiber Optic Cable
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Coaxial Cable

• Consists of a central copper core encased in a
  plastic sheath
• Quite easy to implement, and popular choice in
  LAN
• Speed and throughput 10 100 Mbps
• Media and connector size medium
• Maximum cable length 50m

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Coaxial Cable

• Divided into 2 types
• Baseband
• One channel single message a time at a high
  speed
• Able to handle 10 80 Mbps
• An important component in Ethernet
• Easy to plug in / out a network without
  disturbing network flow
• 500m optimum range
• Unable to send integrated signals

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Coaxial Cable

• Broadband
• Can carry several different signals broadcasted
  at different frequency simultaneously
• Possible to allocate 6-346 MHz for forward and 25
  MHz for reception channels
• Can be single cable or dual cable.
• Can have 50 channels broadcast at 5 Mbps maximum
• Require more planning, and installation of
  amplifiers are needed

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Asynchronous Transfer Mode

• Another popular networking technology working in
  a different way compared to LAN
• It is possible to implement ATN in a LAN, and
  vice versa, by emulating the 2 technologies.

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Differences between LAN and ATM

• Connection
• LAN is connectionless, ATM is connection
  oriented.
• Size of transmission
• LAN have variable packet size, up to 1.5
  kilobytes, while in ATM, each cell is 53 bytes.
• Broadcast
• LAN support broadcast and MAC address, while ATM
  is switch-based
• Mode
• LAN work in best effort mode, ATM is similar
  except how it provide effective congestion control

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Wireless LAN

• A traditional LAN uses electricity and light as
  medium of data transmission.
• Wireless technology uses the atmosphere as
  transmission medium
• While it is applicable, wireless LAN is costly,
  and have high error rate

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