540     6   

  PVC  frame relay    
    ,         
    ,   
 .      Ethernet
 FDDI    LAP-F     
 LAP-F  .  Internet RFC 1490  
 SNAP      frame relay  -
  .

    frame relay    ,  -
,         frame relay
     FRAD (  ,   -
,    UNI frame relay,    FRAD).

   frame relay     ,   -
     SNA,    ,   
    ,  SDLC ( 
   IBM).

        
          
     ,   
 .      ,  
TCP/IP,       ,    
  .

6.4.4.  

       , 
       -
     .   ,  -
   ,   
 .     (Asynchronous
Transfer Mode, )       
    ,    -
 ISDN (Broadband-ISDN, B-ISDN).

   ,  ,   
,        -
  .

         -
 (, ) ,   ,  
        -
.

    ,      -
        
.

        .

       
: 1/1, /, SDH STM-n, FDDI.