Chapter 5 - Physical Topology/Logical Topology

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Text of Chapter 5 - Physical Topology/Logical Topology

    • Physical topology
    • Physical layout of a network


  • ABus topologyconsists of a single cablecalled abus connecting all nodes on a network without intervening connectivity devices

Bus topology network 4. A terminated bus network 5.

  • 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 istoken passing

A typical ring network 6.

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

A typical star topology network 7. Hybrid Physical Topologies

    • Hybrid topology
    • Complex combination of the simple physical topologies

Hierarchicalhybrid topology Star-wired ring Star-wired bus Daisy-Chained 8.

  • Star-wired ring
    • Star-wired topologiesuse physical layout of a star in conjunction with token ring-passing data transmission method

A star-wired ring topology network Hybrid Physical Topologies 9. Hybrid Physical Topologies

  • Star-wired bus
    • In astar-wired bus topology , groups of workstations are star-connected to hubs and then networked via a single bus

A star-wired bus network topology 10. Hybrid Physical Topologies

  • Daisy-Chained
    • ADaisy chainis linked series of devices

A daisy-chained star-wired bus topology 11. Hybrid Physical Topologies

  • Hierarchical hybrid topology
    • Uses layers to separate devices by priority or function

A hierarchical ring topology 12. Enterprise-Wide Topologies

  • Enterprise
    • An entire organization
  • Backbone networks
    • Serial backbone
    • Distributed backbone
    • Collapsed backbone
    • Parallel backbone

13. Enterprise-Wide Topologies

  • Serial backbone
    • Two or more hubs connected to each other by a single cable
  • Distributed backbone
    • Hubs connected to a series of central hubs or routers in a hierarchy

A simple distributed backbone network 14. Enterprise-Wide Topologies A distributed backbone connecting multiple LANs VA GA NC 15. Enterprise-Wide Topologies

  • Collapsed backbone
    • Uses a router or switch as the single central connection point for multiple subnetworks

A collapsed backbone network 16. Enterprise-Wide Topologies

  • Parallel Backbone
    • Collapsed backbone arrangement that consists of more than one connection from central router or switch to each network segment

A parallel backbone network 17. Enterprise-Wide Topologies

  • Mesh networks
    • Routers are interconnected with other routers, with at least two pathways connecting each router

An example of a mesh network 18. Wide Area Network (WAN) Topologies

  • Peer-to-peer topology
    • WAN with single interconnection points for each location
    • Dedicated circuits
      • Continuous physical or logical connections between two access points that are leased from a communication provider

A peer-to-peer WAN 19. Wide Area Network (WAN) Topologies

  • Ring WAN topology
    • Each site is connected to two other sites so that entire WAN forms a ring pattern

A ring-configured WAN 20. Wide Area Network (WAN) Topologies

  • Star WAN topology
    • Single site acts as the central connection point for several other points

A star-configured WAN 21. Wide Area Network (WAN) Topologies

  • Mesh WAN topology
    • Many directly interconnected locations forming a complex mesh

Full-mesh and partial-mesh WANs 22. Wide Area Network (WAN) Topologies

  • Tiered WAN topology
    • Sites connected in star or ring formations are interconnected at different levels, with interconnection points organized into layers

A tiered WAN topology 23. Logical Topologies

  • Refers to the way in which data are transmitted between nodes
  • Describes the way:
    • Data are packaged in frames
    • Electrical pulses are sent over networks physical media
  • Logical topology may also be callednetwork transport system

24. Switching

  • Component of networks logical topology that determines how connections are created between nodes
    • Circuit switching
      • Connection is established between two network nodes before they begin transmitting data
    • Message switching
      • Establishes connection between two devices, transfers information to second device, and then breaks connection
    • Packet switching
      • Breaks data into packets before they are transmitted

25. Ethernet

  • Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
    • Theaccess methodused in Ethernet
    • Collision
      • In Ethernet networks, the interference of one network nodes data transmission with another network nodes data transmission
    • Jamming
      • Part of CSMA/CD in which, upon detection of collision, station issues special 32-bit sequence to indicate to all nodes on Ethernet segment that its previously transmitted frame has suffered a collision and should be considered faulty

26. Ethernet CSMA/CD process 27. Ethernet

  • Collision domain
    • Segment on a network in which collisions will occur if two nodes transmit data at same time
  • Data propagation delay
    • Length of time data take to travel from one point on the segment to another point

28. Ethernet

  • Demand priority
    • Method for data transmission used by 100BaseVG Ethernet networks
    • Demand priority requires anintelligent hub

CSMA/CD versus demand priority 29. Ethernet

  • Traditional Ethernet LANs, calledshared Ethernet , supply fixed amount of bandwidth that must be shared by all devices on a segment
  • Switch
    • Device that can separate network segments into smaller segments, with each segment being independent of the others and supporting its own traffic
  • Switched Ethernet
    • Newer Ethernet model that enables multiple nodes to simultaneously transmit and receive data over logical network segments

30. Ethernet Figure 5-21: A switched Ethernet network 31. Ethernet

  • Gigabit Ethernet
    • 1 Gigabit Ethernet
      • Ethernet standard for networks that achieve 1-Gbps maximum throughput
    • 10 Gigabit Ethernet
      • Standard currently being defined by IEEE 802.3ae committee
      • Will allow 10-Gbps throughput
      • Will include full-duplexing and multimode fiber requirements

32. Understanding Frame Types

  • Learning about networks is analogous to learning a foreign language, with the frame type being the languages syntax
    • Just as you may know the Japanese word for go but how to use it in a sentence, you may know all about the IPX/SPX protocol but not how devices handle it
  • Autosense
    • Feature of modern NICs that enables a NIC to automatically sense what types of frames are running on a network and set itself to that specification


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