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Ethernet 802.3 Physical Layer

Ethernet 802.3 Physical Layer. Topology : Order in which stations receive bits Ethernet hubs use a bus topology Signal is broadcast All stations receive almost simultaneously. Ethernet 802.3 Physical Layer. Topology: Order in which stations receive bits

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Ethernet 802.3 Physical Layer

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  1. Ethernet 802.3 Physical Layer • Topology: Order in which stations receive bits • Ethernet hubs use a bus topology • Signal is broadcast • All stations receive almost simultaneously

  2. Ethernet 802.3 Physical Layer • Topology: Order in which stations receive bits • Early Ethernet standards arranged stations in a daisy chain • Stations broadcast on the chain in both directions • All stations receive almost simultaneously • Original idea of bus

  3. Ethernet 802.3 Physical Layer • Topology: Order in which stations receive bits • Ethernet switches use a switched topology • Signal only goes to one station

  4. Ethernet 802.3 Physical Layer • Ethernet began as a bus network • Some question whether Ethernet switching is really Ethernet • However, hubs will be disappearing in the next few years, and almost all Ethernet will be switched

  5. Ethernet 802.3 Physical Layer • Recent Ethernet 802.3 Standards use Unshielded Twisted Pair (UTP) Wiring or Optical Fiber • For Small LANs with a Single Hub or Switch, use UTP Exclusively

  6. Physical Layer 802.3 UTP Standards 802.3 • Ethernet 802.3 10Base-T • Physical layer standard • Created by the 802.3 Working Group • 10 Mbps • Baseband transmission • Insert signal directly into wire • No channels • T means uses UTP twisted-pair wire 10 Mbps

  7. Physical Layer 802.3 UTP Standards • Ethernet 802.3 100Base-TX • 100 Mbps • 100Base-TX: Not just 100Base-T because other 100Mbps UTP standards were created but were not used significantly • Ethernet 802.3 1000Base-T • Gigabit Ethernet • Overkill for small LANs

  8. Physical Layer 802.3 UTP Standards • Wiring • Unshielded Twisted Pair • Bundle of 4 pairs (only uses 2 pairs) • One pair to send • One pair to receive • Terminates in RJ-45 connector • Slightly larger than RJ-11 home phone connector

  9. Physical Layer 802.3 UTP Standards • Categories of UTP Wiring • Wiring Quality, Category 3 being lowest • For 10Base-T • Categories 3, 4, or 5 are OK • However, most installed wiring is Cat 5 • For 100Base-TX, Cat 5 is required • For Gigabit Ethernet, Enhanced Category 5 is recommended, although Cat 5 should work if perfectly installed

  10. Physical Layer: 802.3 UTP Standards • Wiring • 100 meters maximum UTP distance hub-to-station or hub-switch • 200 meters maximum distance between stations 200 m 100 m 100 m

  11. Physical Layer 802.3 Standards • NIC-Hub Communication • NIC transmits on one pair (Pins 1&2) • Hub or switch transmits on another pair (Pins 3 & 6) • Other 4 wires are not used To Hub or Switch (Pins 1&2) From Hub or Switch (Pins 3&6)

  12. Physical Layer 802.3 Standards • Upgrading from 10Base-T to 100Base-TX • Need new hub or switch • May have autosensing 10/100 ports that handle either 10 Mbps or 100 Mbps NICs • Need new NICs • Only for stations that need more speed • No need to rewire • This would be expensive

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