124     2     ___________________ __

           -
  .       ,
,    11801   EN50173  -
  ,     EIA/TAI-568A.

   EIA/TIA     
   Underwriters Labs,    -
 Anixter.       EIA/TIA-568.

   ,      
  ,        
     IBM.

     - .  -
,     ,    -
,          
  ,    . .     -
  ,   .     
 Ethernet  FDDI,   ,    
  Ethernet  FDDI.

       ,  -
.        
 ( TSB-36  TSB-40A,     568),   
 (),      ,
       ,  ,  
(  90    ),   (,    
  )     ,  -
  .

        ,  
     .

      ,  -
     (      
 ).

  (Attenuation).        -
     .

      (Near End Cross Talk, NEXT). -
      .

  ( )    (  ) -
   .      
      (,  -
 ,    Ethernet,   -
  50 ).      
    100  120 .    
(100-200 )    .

         -
 .          -
      .

        . 
   ,  , 
 ,   .   -