550     6   _________ ____ ____    __

 AAL1        
 (Constant Bit Rate, CBR),  , ,  -
         .  
     ,    
 .  AAL1       1 
2 ,       47 
46 .        ,  
    ,         . 
       ,  
        125 ,    
      ,  
 12546 .        ,   
     .  
 AAL1      
  .

 AAL2       ,   -
        ,   
      AAL1, AAL3/4  AAL5.

 AAL3/4      
         (Variable Bit
Rate, VBR).    ,     , 
   .  AAL3/4  -
      ,   -
         .
,          -
,           ,  
        
  / AAL3/4    
 AAL3  AAL4,     
        .
        
   AAL3  AAL4   .

 AAL5     AAL4  
,          , 
            -
.   AAL5      frame
relay,          
.  AAL5      -
,  ,       -
 .         ,
    ,      D. 
     AAL5   CBR,
      .

 AAL5      ,     
.      ,    
 .     AAL5 
    ,   -
  .