6.4.            519

 ,       -
.           -
  56 /    - 
  .

        :

Switched 56  ISDN.

 Switched 56    ,    
 4-    1/1,  
 56 /.       -
 .  Switched 56   -
      56 /.

       ISDN    -
        . ISDN
     , 
,       (frame relay).

  UNI   ISDN     BRI 
PRI.  BRI       
 2B+D.  PRI     
23B+D   30B+D.

   D     ,  
   ISDN: -,     -
       , -,   .25 
  ISDN    .25,    ISDN.

    DSL  ISDN   BRI -
  2-     5,5 .

       ISDN   
        -
       . 
     D       
 ,      9600 /. 
 ISDN   ,     ,  
    .

6.4.   
  

        -
       . ,
          -
 ,      ,   -
 ,      IP  IPX,  
    .