Chapter 5 - Physical Topology/Logical Topology


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Chapter 5 - Physical Topology/Logical Topology

  1. 1. TOPOLOGY <ul><li>Physical topology </li></ul><ul><ul><li>Physical layout of a network </li></ul></ul>
  3. 3. <ul><li>A Bus topology consists of a single cable—called a bus — connecting all nodes on a network without intervening connectivity devices </li></ul>Bus topology network
  4. 4. A terminated bus network
  5. 5. <ul><li>Ring topology </li></ul><ul><ul><li>Each node is connected to the two nearest nodes so the entire network forms a circle </li></ul></ul><ul><ul><li>One method for passing data on ring networks is token passing </li></ul></ul>A typical ring network
  6. 6. <ul><li>Star topology </li></ul><ul><ul><li>Every node on the network is connected through a central device </li></ul></ul>A typical star topology network
  7. 7. Hybrid Physical Topologies <ul><ul><li>Hybrid topology </li></ul></ul><ul><ul><li>Complex combination of the simple physical topologies </li></ul></ul>Hierarchical hybrid topology Star-wired ring Star-wired bus Daisy-Chained
  8. 8. <ul><li>Star-wired ring </li></ul><ul><ul><li>Star-wired topologies use physical layout of a star in conjunction with token ring-passing data transmission method </li></ul></ul>A star-wired ring topology network Hybrid Physical Topologies
  9. 9. Hybrid Physical Topologies <ul><li>Star-wired bus </li></ul><ul><ul><li>In a star-wired bus topology , groups of workstations are star-connected to hubs and then networked via a single bus </li></ul></ul>A star-wired bus network topology
  10. 10. Hybrid Physical Topologies <ul><li>Daisy-Chained </li></ul><ul><ul><li>A Daisy chain is linked series of devices </li></ul></ul>A daisy-chained star-wired bus topology
  11. 11. Hybrid Physical Topologies <ul><li>Hierarchical hybrid topology </li></ul><ul><ul><li>Uses layers to separate devices by priority or function </li></ul></ul>A hierarchical ring topology
  12. 12. Enterprise-Wide Topologies <ul><li>Enterprise </li></ul><ul><ul><li>An entire organization </li></ul></ul><ul><li>Backbone networks </li></ul><ul><ul><li>Serial backbone </li></ul></ul><ul><ul><li>Distributed backbone </li></ul></ul><ul><ul><li>Collapsed backbone </li></ul></ul><ul><ul><li>Parallel backbone </li></ul></ul>
  13. 13. Enterprise-Wide Topologies <ul><li>Serial backbone </li></ul><ul><ul><li>Two or more hubs connected to each other by a single cable </li></ul></ul><ul><li>Distributed backbone </li></ul><ul><ul><li>Hubs connected to a series of central hubs or routers in a hierarchy </li></ul></ul>A simple distributed backbone network
  14. 14. Enterprise-Wide Topologies A distributed backbone connecting multiple LANs VA GA NC
  15. 15. Enterprise-Wide Topologies <ul><li>Collapsed backbone </li></ul><ul><ul><li>Uses a router or switch as the single central connection point for multiple subnetworks </li></ul></ul>A collapsed backbone network
  16. 16. Enterprise-Wide Topologies <ul><li>Parallel Backbone </li></ul><ul><ul><li>Collapsed backbone arrangement that consists of more than one connection from central router or switch to each network segment </li></ul></ul>A parallel backbone network
  17. 17. Enterprise-Wide Topologies <ul><li>Mesh networks </li></ul><ul><ul><li>Routers are interconnected with other routers, with at least two pathways connecting each router </li></ul></ul>An example of a mesh network
  18. 18. Wide Area Network (WAN) Topologies <ul><li>Peer-to-peer topology </li></ul><ul><ul><li>WAN with single interconnection points for each location </li></ul></ul><ul><ul><li>Dedicated circuits </li></ul></ul><ul><ul><ul><li>Continuous physical or logical connections between two access points that are leased from a communication provider </li></ul></ul></ul>A peer-to-peer WAN
  19. 19. Wide Area Network (WAN) Topologies <ul><li>Ring WAN topology </li></ul><ul><ul><li>Each site is connected to two other sites so that entire WAN forms a ring pattern </li></ul></ul>A ring-configured WAN
  20. 20. Wide Area Network (WAN) Topologies <ul><li>Star WAN topology </li></ul><ul><ul><li>Single site acts as the central connection point for several other points </li></ul></ul>A star-configured WAN
  21. 21. Wide Area Network (WAN) Topologies <ul><li>Mesh WAN topology </li></ul><ul><ul><li>Many directly interconnected locations forming a complex mesh </li></ul></ul>Full-mesh and partial-mesh WANs
  22. 22. Wide Area Network (WAN) Topologies <ul><li>Tiered WAN topology </li></ul><ul><ul><li>Sites connected in star or ring formations are interconnected at different levels, with interconnection points organized into layers </li></ul></ul>A tiered WAN topology
  23. 23. Logical Topologies <ul><li>Refers to the way in which data are transmitted between nodes </li></ul><ul><li>Describes the way: </li></ul><ul><ul><li>Data are packaged in frames </li></ul></ul><ul><ul><li>Electrical pulses are sent over network’s physical media </li></ul></ul><ul><li>Logical topology may also be called network transport system </li></ul>
  24. 24. Switching <ul><li>Component of network’s logical topology that determines how connections are created between nodes </li></ul><ul><ul><li>Circuit switching </li></ul></ul><ul><ul><ul><li>Connection is established between two network nodes before they begin transmitting data </li></ul></ul></ul><ul><ul><li>Message switching </li></ul></ul><ul><ul><ul><li>Establishes connection between two devices, transfers information to second device, and then breaks connection </li></ul></ul></ul><ul><ul><li>Packet switching </li></ul></ul><ul><ul><ul><li>Breaks data into packets before they are transmitted </li></ul></ul></ul>
  25. 25. Ethernet <ul><li>Carrier Sense Multiple Access with Collision Detection (CSMA/CD) </li></ul><ul><ul><li>The access method used in Ethernet </li></ul></ul><ul><ul><li>Collision </li></ul></ul><ul><ul><ul><li>In Ethernet networks, the interference of one network node’s data transmission with another network node’s data transmission </li></ul></ul></ul><ul><ul><li>Jamming </li></ul></ul><ul><ul><ul><li>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 </li></ul></ul></ul>
  26. 26. Ethernet CSMA/CD process
  27. 27. Ethernet <ul><li>Collision domain </li></ul><ul><ul><li>Segment on a network in which collisions will occur if two nodes transmit data at same time </li></ul></ul><ul><li>Data propagation delay </li></ul><ul><ul><li>Length of time data take to travel from one point on the segment to another point </li></ul></ul>
  28. 28. Ethernet <ul><li>Demand priority </li></ul><ul><ul><li>Method for data transmission used by 100BaseVG Ethernet networks </li></ul></ul><ul><ul><li>Demand priority requires an intelligent hub </li></ul></ul>CSMA/CD versus demand priority
  29. 29. Ethernet <ul><li>Traditional Ethernet LANs, called shared Ethernet , supply fixed amount of bandwidth that must be shared by all devices on a segment </li></ul><ul><li>Switch </li></ul><ul><ul><li>Device that can separate network segments into smaller segments, with each segment being independent of the others and supporting its own traffic </li></ul></ul><ul><li>Switched Ethernet </li></ul><ul><ul><li>Newer Ethernet model that enables multiple nodes to simultaneously transmit and receive data over logical network segments </li></ul></ul>
  30. 30. Ethernet Figure 5-21: A switched Ethernet network
  31. 31. Ethernet <ul><li>Gigabit Ethernet </li></ul><ul><ul><li>1 Gigabit Ethernet </li></ul></ul><ul><ul><ul><li>Ethernet standard for networks that achieve 1-Gbps maximum throughput </li></ul></ul></ul><ul><ul><li>10 Gigabit Ethernet </li></ul></ul><ul><ul><ul><li>Standard currently being defined by IEEE 802.3ae committee </li></ul></ul></ul><ul><ul><ul><li>Will allow 10-Gbps throughput </li></ul></ul></ul><ul><ul><ul><li>Will include full-duplexing and multimode fiber requirements </li></ul></ul></ul>
  32. 32. Understanding Frame Types <ul><li>Learning about networks is analogous to learning a foreign language, with the frame type being the language’s syntax </li></ul><ul><ul><li>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 </li></ul></ul><ul><li>Autosense </li></ul><ul><ul><li>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 </li></ul></ul>