6.4.            533

         -
 ,         ,   
  ,      .25.

  (. 6.25)     frame
relay    ISDN,    frame relay   
  ISDN,      -
 .

    LAP-F core,   -
    LAP-D.  LAP-F ( Q.922
ITU-T)      ISDN,      1/1.
      LAP-F    -
,         . 
 PVC  frame relay    -
 LAP-F core.

 LAP-F contol     LAP-F core,
        .
   LAP-F control    frame switching.

      ITU-T -
  D  .   -  -
  LAP-D,        
ISDN.      0,931   Q..933 (-
      Q..931 ISDN), -
        ( 
.164  ISO 7498),     ,   -
 frame relay   Data Link Connection Identifier  DLCI.

        frame relay -
   LAP-D  Q.931/933,    
 LAP-F,        -
,      DLCI.  LAP-F _^
          LAP-D,
 ITU-T    - ,   LAP-D, -
        LAP-F control.

- ,   frame relay    , 
        ,
 IP,      ,  .
       frame relay
, ,   RFC 1490,  -
    frame relay     -
      SNA.

   frame relay     -
   .  frame relay ,  
          -
    .     -
   ,       
 .     frame relay   
 ,   Ethernet, Token Ring  FDDI,    -
  ,       .

   LAP-F   . 6.26.