580     6   

      ,  -
 .

        -
 ,       
     ,    
      .

*         
  dial-in ( ),    
   dial-out.

*        -
        ,
   .     -
         -
,      4800  9600 /.

*        , -
    ,   
,      .

*         
  ,       -
        
 Internet,   Internet       -
 ,       .

*     Internet    
       
       *DSL, 
      -
 ADSL.

  

1.      DSU/CSU?

2.      .   -
    ,   
    -     -
 ,    ?  -
        
   500 /  1 /.

3.  ,       2- -
   ,     .    -
?

4.        OSI   -
 ?