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Topic BNCSPEC from HARDW FAQ base

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   BNC cabling specifications

   Specifications and recommendations for Thin Ethernet cable
   ==========================================================


      The EtherExpress(TM) PRO/10 adapters have a cylindrical, bayonet 
      BNC connector.

      BNC cabling is also known as thin Ethernet, RG-58A/U, Cheapernet,
      and 10BASE-2.
  
      This document contains cabling and installation recommendations. 
      For more information on thin Ethernet cabling,contact your local 
      network supplier or call the IEEE at 1-800-678-IEEE.


   Recommended cables
   ==================     
      Here is a list of IEEE approved and non-approved cables.

      Approved cable types
      ------------------------------------------------
      802.3 10Base2     50 ohms, stranded tinned core
      RG-58 a/u         50 ohms, stranded tinned core
      RG-58 c/u         50 ohms, stranded tinned core
      ------------------------------------------------

      NON-Approved cable types
      ------------------------------------------------
      RG-58             50 ohms, solid center core
      RG-58 u           50 ohms, solid center core
      ------------------------------------------------


   Installation recommendations
   ============================
      Thin Ethernet is a linear bus topology that uses a COAX cable. 
      A break in the cable will disrupt the entire segment.

      Each node is connected to the cable using a T-connector.

      - Don't connect the end of the cable directly to the BNC connector
        on the EtherExpress card.  
  
      - Don't use cable drops or external transceivers unless you are
        using the AUI connector instead of the BNC connector.
  
      Both ends of a trunk must be terminated with 50 ohm terminators.  One
      end should be grounded.

      Up to 5 trunk segments may be connected (through repeaters), but only 3
      of these segments can have workstations attached.  Repeaters count as a
      workstation so if you have two repeaters on a segment, then the maximum
      number of user workstations is 28.

      Example:    
                     no workstations               no workstations
                            |                             |
                            v                             v
       |--+----------+  +--------+  +------+-------+  +--------+  +----+----|
       
          |          |  |        |  |      |       |  |        |  |    |
          |        repeater     repeater   |     repeater    repeater  |
          |                                |                           |
       workstation                    workstation                workstation
          1-29                           1-28                        1-29
 
      
      Cable lengths
      ---------------------------------------------------------------------
      Max trunk length                  185 meters (607 feet)
      Max number of nodes per trunk      30
      Max number of trunks                5 (only 3 can have wkst attached)  
      Max length of entire network      925 meters (3035 feet)
        (all trunks added together)
      Min cable length between nodes     .5 meters (1 1/2 feet)
      ---------------------------------------------------------------------
 
     
  

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