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The Physical Interconnection

The following diagram depicts the physical interconnection of a PC (Workstation) to the Ethernet LAN:

Functional Overview:

• Twisted pair cable is used as the transport media. This is known as a Type "10BASE-T" Ethernet. In these configurations, each station (PC) is connected to a central "repeater" or "hub" (Star Network). The cable length may be up to 100 meters when Category 3 cable is used.

• Items C and D (MAU and AUI) are associated with a "Transceiver", if applicable. Usually, these functions are onboard the Ethernet board in the PC and no Transceiver is required. Typical pinouts for the RJ-45 jack are:

  1 = DTE Transmit Data (+)
  2 = DTE Transmit Data (-)
  3 = DTE Receive Data (+)
  6 = DTE Receive Data (-)
  

  Typical Transceiver pinouts are:

  1. = Collision Shield
  2. = Collision (+)
  3. = Transmit (+)
  4. = Receive Shield
  5. = Receive (+)
  6. = Power Return
  7. = Not Used
  8. = Not Used
  9. = Collision (-)
  10. = Transmit (-)
  11. = Transmit Shield
  12. = Receive (-)
  13. = +12 VDC
  14. = Voltage Shield
  15. = Not Used
  • Item E, the MAC (Media Access Control) function resides onboard the Ethernet card. MAC operation controls the electrical functions associated with Carrier Sense Multiple Access (CSMA)/Collision Detection (CD) and the output/decoding of Manchester-coded 10 MBPS Ethernet HDLC frames.

  A Typical Ethernet Frame

  A typical Ethernet frame will look something like this:

  

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