Chapter 5: TOPOLOGY

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Chapter 5TOPOLOGY

• By Andrew Severin

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Agenda

• What is Topology?
• Main Types of Topology
• Linear Bus
• Star
• Star Wired Ring
• Tree
• Summary of Topologies
• Choosing a Topologies

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What is Topology?

• Two forms of Topology
• Physical Topology the configuration of cables,
  computers and other peripherals.
• Logical Topology method used to pass
  information between workstations.
• In this presentation, I will be talking to you
  about Physical Topology.

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Agenda

• What is Topology?
• Main Types of Topologies
• Linear Bus
• Star
• Star Wired Ring
• Tree
• Summary of Topologies
• Choosing a Topologies

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Linear Bus Topology

• Consists of a main run of cable with a terminator
  at each end.
• All nodes, such as file servers, workstations and
  peripherals are connected to the linear cable.
• Ethernet and LocalTalk networks use a Linear Bus
  Topography.

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Linear Bus Topology

• ADVANTAGES
• Easy to connect a computer or peripheral.
• Requires less cable length than a Star
  Topography.

• DISADVANTAGES
• Entire network shuts down if there is a break in
  the main cable
• Terminators are required at both ends of backbone
  cable.
• Extremely difficult to identify the problem when
  the entire network shuts down.
• Not to be used as stand-alone solution for
  large building.

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Star Topology

• Two forms
• Star Topology.
• Star-Wired Ring Topology.
• Each node (file server, workstation and
  peripherals) connect directly to central network
  hub or concentrator.
• How it Works
• Data passes through the hub or concentrator
  before continuing to its destination.
• The hub or concentrator manages and controls all
  the functions of the network, as well as a
  repeater for data flow.
• Common with twisted pair cable, but can also be
  used with coaxial cable or fiber optic cable.

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Star Topology

• ADVANTAGES
• Easy to install and wire.
• No disruptions to the network when adding or
  removing devices.
• Easy to detect problems.
• Easy to remove parts.

• DISSADVANTAGES
• More cable length required than Linear Bus
  Topology.
• If hub or concentrator fails, nodes attached are
  disabled.
• More expensive than Linear Bus Topology, mainly
  due to the cost of the concentrators.

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Star Topology
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Star-Wired Ring Topology

• Externally, Star-Wired Ring Topology may appear
  to be identical to Star Topology.
• Difference
• The MAU (Multistation Access Unit) contains
  wiring that allows information to pass from one
  device to another in a circle or ring.
• Token Ring protocol uses Star-Wired Ring Topology.

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Tree Topology

• Combines characteristics of Linear Bus and Star
  Topologies.
• Groups of Star-configured workstations connected
  to a Linear Bus Backbone cable.
• Allows for easy expansion of an existing network.
• Often used in schools, as it enables to configure
  network to meet their needs.

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Tree Topology

• ADVANTAGES
• Point-to-point wiring for individual segments.
• Supported by several hardware and software
  vendors.

• DISSADVANTAGES
• Overall length of each segment is limited by the
  type of cable used.
• Entire segment goes down if backbone line breaks.
• Most difficult to configure and wire of the three
  topologies.

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Tree Topology 5-4-3 Rule

• When setting up Tree Topology Network using
  Ethernet, a good idea to use the 5-4-3 Rule.
• Ethernet protocol requires that a signal sent out
  reach every part of the network within a
  specified amount of time.
• Each concentrator or hub that the signal passes
  through adds a small amount of time.
• Rule
• Between any two nodes on the network, there can
  only be a maximum of five segments, connected
  through four concentrators.
• Only three of the segments can be populated if
  they are made of coaxial cable. (Populated
  Segment segment which has one or more nodes
  attached to it.)
• This rule does not apply if the cable used is
  fiber optic, or a combination of fiber optic and
  UTP.
• The rule is translated to 7-6-5 Rule.

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Tree Topology

• This diagram of Tree Topography adheres to the
  5-4-3 Rule.
• The furthest two nodes on the network have 4
  segments and 3 concentrators between them.

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Agenda

• What is Topology?
• Main Types of Topologies
• Linear Bus
• Star
• Star Wired Ring
• Tree
• Summary of Topologies
• Choosing a Topologies

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Summary Chart
Physical Topology Common Cable Common Protocol
Linear Bus Twisted Pair Coaxial Fiber Ethernet LocalTalk
Star Twisted Pair Fiber Ethernet LocalTalk
Star-Wired Ring Twisted Pair Token Ring
Tree Twisted Pair Coaxial Fiber Ethernet
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Agenda

• What is Topology?
• Main Types of Topologies
• Linear Bus
• Star
• Star Wired Ring
• Tree
• Summary of Topologies
• Choosing a Topologies

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Choosing a Topology

• Here are some considerations you should think
  about when selecting a Topology
• Money. Linear Bus Network is often the least
  expensive way to install a network, as you do not
  need to purchase concentrators.
• Length of Cable Needed. Linear Bus Network uses
  the least amount of cable.
• Future Growth. If you are planning on expanding a
  network, Star Topology is easily done by adding
  another concentrator.
• Cable Type. In a school for instance, the most
  common cable is unshielded twisted pair, and is
  generally used with Star Topologies.