480     6   _________________________________

  ,   .   
     ,  
       ( 
1 - ,    1 - )    
  -      , -
   PDH,       .

       
Synchronous Digital Hierarchy, SDH ( G.707-G.709),   -
  SONET  ,     SDH  SONET
       
  PDH   ,   .  
    SDH  SONET  ,   
    ,   SONET/
SDH     .    -
    SDH.

       SONET/SDH,
   SONET/SDH,   . 6.3.

 6.3.   SONET/SDH

SDH               SONET               

                   STS-1, -1             51,840 /

STM-1                STS-3, -3             155,520 /

STM-3                STS-9, -9             466,560 /

STM-4               STS-12, -12           622,080 /

STM-6               STS-18, -18           933,120 /

STM-8                STS-24, -24           1,244 5/

STM-12               STS-36, -36           1,866 5/

STM-16________STS-48, -48______2,488 /_________________________

  SDH    (, ,   
 )   : STM-n  Synchronous Transport Module level n.
  SONET      : STS-n 
Synchronous Transport Signal level n,     -
 ,  -  Optical Carrier level n,   
    - .   STS
  .

   ,  SONET    51,84 /,
  SDH    155,52 /,    -
 SONET.       
155,52 /,       SDH
  PDH      SDH    
DS-4,    139,264 /.    SONET/
SDH   STS-1.    155,52 / 
   DS-4     
   SONET/SDH.

   SONET  SDH,   ,  -
 ,      STS-3/STM-1.  