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Network Topology�

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BRANCH-E&TC ENGINEERING

SEM – 4th

SUBJECT-DATA COMMUNICATION AND COMPUTER NETWORK

CHAPTER-06- lan technology

TOPIC- network topology

Ay-2021-2022 ,summer-2022

FACULTY-ER V BEHERA.(LECTURER E & Tc engg dept)

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Objectives

  • Describe the basic and hybrid LAN physical topologies, and their uses, advantages and disadvantages
  • Describe the backbone structures that form the foundation for most LANs

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Simple Physical Topologies

  • Physical topology: physical layout of nodes on a network
  • Three fundamental shapes:
    • Bus
    • Ring
    • Star
  • May create hybrid topologies
  • Topology integral to type of network, cabling infrastructure, and transmission media used

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Bus

  • Single cable connects all network nodes without intervening connectivity devices
  • Devices share responsibility for getting data from one point to another
  • Terminators stop signals after reaching end of wire
    • Prevent signal bounce
  • Inexpensive, not very scalable
  • Difficult to troubleshoot, not fault-tolerant

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Bus (continued)

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Advantages & Disadvantages of Bus Topology

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Advantages

  • Works well for small networks
  • Relatively inexpensive to implement
  • Easy to add to it

Disadvantages

  • Management costs can be high
  • Potential for congestion with network traffic

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Ring

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Simple Physical Topologies

  • Ring topology
    • Each node is connected to the two nearest nodes so the entire network forms a circle
    • One method for passing data on ring networks is token passing
  • Active topology
    • Each workstation transmits data

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Advantages of Ring Topology

  • Easier to manage; easier to locate a defective node or cable problem
  • Well-suited for transmitting signals over long distances on a LAN
  • Handles high-volume network traffic
  • Enables reliable communication

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Disadvantages of�Ring Topology

  • Expensive
  • Requires more cable and network equipment at the start
  • Not used as widely as bus topology
    • Fewer equipment options
    • Fewer options for expansion to high-speed communication

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Star

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Simple Physical Topologies

  • Star topology
    • Every node on the network is connected through a central device

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Star (continued)

  • Any single cable connects only two devices
    • Cabling problems affect two nodes at most
  • Requires more cabling than ring or bus networks
    • More fault-tolerant
  • Easily moved, isolated, or interconnected with other networks
    • Scalable
  • Supports max of 1024 addressable nodes on logical network

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Advantages & Disadvantages of Star Topology

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Advantages

  • Good option for modern networks
  • Low startup costs
  • Easy to manage
  • Offers opportunities for expansion
  • Most popular topology in use; wide variety of equipment available

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Disadvantages

  • Hub is a single point of failure
  • Requires more cable than the bus

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Hybrid Physical Topologies: �Star-Wired Ring

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Star-Wired Bus

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Backbone Networks: Serial Backbone

  • Daisy chain: linked series of devices
    • Hubs and switches often connected in daisy chain to extend a network
  • Hubs, gateways, routers, switches, and bridges can form part of backbone
  • Extent to which hubs can be connected is limited

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Logical Topologies

  • Logical topology: how data is transmitted between nodes
    • May not match physical topology
  • Bus logical topology: signals travel from one network device to all other devices on network
    • Required by bus, star, star-wired physical topologies
  • Ring logical topology: signals follow circular path between sender and receiver
    • Required by ring, star-wired ring topologies

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