538     6   

 BECN (Backward Explicit Congestion Bit)     
        -
.  BECN         frame
relay  ,    CSU/DSU.  frame
relay    ,      FECN
 BECN,       , 
   RNR  .25.      
    (TCP, SPX, NCP  . .)   
 .        -
 -    ,   ,   -
  frame relay     
   .

    FECN  BECN  .   -
    frame relay (Frame Relay Access Device, FRAD) 
    BECN.

       -
       0,931.   -
       .

  frame relay,     -
    ,       D -
 SETUP,    ,   :

. DLCI;

  (  .164, .121  ISO 7498);

       ;

   CIR   ;

      ;

   Be   .

,    ,    
 CALL PROCEEDING   .    ,
  ,       (, -
,   ,         -
),    SETUP  . 
    .   -
     frame relay  , 
       
  .         -
  ,   SETUP      -
.        CALL PROCEEDING
   .   ,   
      CONNECT,      
 .    ,   
   .    CONNECT -
        CONNECT ACKNOWLEDGE.

       CONNECT
ACKNOWLEDGE,      .  -
    .