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Ethernet Wiring

Ethernet Wiring

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Ethernet Wiring

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  1. Ethernet Wiring Qutaibah Malluhi CSE Department Qatar University

  2. Network Interface Cards • CPU can't process data at network speeds • Computers use special purpose hardware for network connection • Typically a separate card in the backplane • Network adapter card or network interface card (NIC) • Connector at back of computer then accepts cable to physical network • NIC is built for one kind of physical network • Ethernet interface can't be used with token ring • ATM interface can't be used with FDDI • Some NICs can be used with different, similar hardware • Thick, thin and 10Base-T Ethernet • 10Mbps and 100Mbps Ethernet

  3. NICs

  4. NIC and CPU • NIC processes network frames independent of the CPU • Looks like any other I/O device to system CPU • System CPU forms message request • Sends instructions to NIC to transmit data • Receives interrupt on arrival of incoming data

  5. Ethernet Wiring • Network technology not limited to one style of connection • Ethernet Technologies • Three wiring schemes correspond to three generations • All run same link speed of 10Mbps • All use same frame format • All are Ethernet

  6. Original Ethernet Wiring - Thicknet • Used thick coaxial cable -- Called thicknet • Formal name 10Base5 -- Each segment can be up to 500m and 100 stations • AUI cable (or transceiver or drop cable connects from NIC to transceiver • AUI cable carries digital signal from NIC to transceiver • Transceiver generates analog signal on coax • Wires in AUI cable carry digital signals, power and other control signals • Requires termination to avoid signal reflectance

  7. Connection of a station to the medium using 10Base5

  8. Connection Multiplixers • Transceivers can be inconvenient • e.g., workstations in a lab • Connection multiplexor connects multiple computers to a single transceiver • Connection multiplexor completely invisible to attached computers

  9. Thin Ethernet Wiring - Thinnet • Uses thinner coax • cheaper and easier to install than thick Ethernet coax • Transceiver electronics built into NIC • NIC connects directly to network medium • Coax cable uses BNC connector Formal name 10Base2 -- Each segment can be up to 200m and 30 stations

  10. Connection of stations to the medium using 10Base2

  11. Thinnet Illustration

  12. Hub-based 10BaseT • Uses a hub -- Replaces thick coax with hub • Formal name 10BaseT -- Each segment can be up to 100m and runs on twisted pair • Called 10Base-T, twisted pair or TP Ethernet • Replaces AUI cable with twisted pair cable

  13. Connection of stations to the medium using 10Base-T

  14. 10BaseT illustration • Sometimes called ``Ethernet-in-a-box'' • Effectively a very short Ethernet with very long AUI cables • Can be connected into larger Ethernets

  15. Office Ethernet Wiring

  16. Comparing Ethernet Wiring Schemes • Thicknet: • Separate transceiver allows computer to be changed or disconnected without disrupting other communication • Transcievers are inconvenient • located in difficult to reach place • Finding malfunctioning transceiver can be hard • Thinnet • Lower cost than thicknet. Coax takes minimum cabling • Disconnecting one computer (or one loose connection) can disrupt entire network • 10Base-T • Hub wiring centralizes management and makes it easier • Bottom line - 10BaseT most popular because of cost

  17. Extending Ethernet • More details in the next chapter • Example: • Multiple Ethernet segments can be connected using repeaters (no more than four => total length 2,500m).

  18. Wiring Scheme Adapters AUI to Thinnet AUI to 10BaseT

  19. Logical and Physical Topologies • Physically • Original Ethernet used bus topology • Modern Ethernet uses star topology • In fact, modern Ethernet is • Physical star • Logical bus • Called star-shaped bus • Distinguish between logical and physical topologies • 10BaseT logical topology is a bus; wiring topology is a star • Token Ring logical topology is a ring; wiring topology is a star • Token Ring hub: Ring-in-a-box

  20. Summary Network interface card (NIC) • connects computer system to network • operates independently of the system CPU • Typically uses interrupts to interact with CPU • Many physical wiring schemes are available for a logical network topology • Three basic Ethernet wiring schemes • 10Base5, 10Base2, and 10BaseT • 10Base-T is a logical bus and a physical star