6.1.         461

          
  ,     DTE  -
   DCE (Data Circuit terminating Equipment),  -
      .  
          DCE 
 :        -
 ,  DSU/CSU      -
   TDM    ()    
  ISDN.  DTE  DCE   ,
       Customer Premises
Equipment, CPE.

      ,   -
 ,        .  -
          
    ,    -
        -
     .

         
- (User-to-Network Interface, UNI).    , 
         -
   ,    UNI -
  (, .25).

     , -
  - (Network-to-Network Interface, NNI), -
  . ,  ,   ,  
 ,   ,   
    .      ,  -
  ,   -,   --
,   ,       
     .   
  NNI ,       
   ,    .

 DTE-DCE

   DCE  ,    -
 ,     DTE,    -
,      .  
    V CCITT,    EIA  RS
(Recomended Standards).          
,    .    -
     300 /      
  (15-20 ),    , -
,   .

 RS-232C/V.24    
.         -
       9600 /    15 .
         