, . / .. . ..
(.25, FR, ATM, ISDN) , OSI (). . , , - HDLC.
HDLC
HDLC (High-level Data Link Control) - - - , ISO, - OSI ( 2). LAPx.
HDLC (.3-6), ( ""), , . ( "") .
3-6. HDLC
| FCS | |||||
| 1 | 1-2 | 1-2 | ( ) | 2 | 1 |
.3-6 :
- : "01111110"; , (, ) .. 7 14 "1", ;
- , -, , ;
- , / .
( ) .. :
- (I) - / ( . .3-7);
- (S) - : (); . ( . .3-7);
- (U) - ; 32 ( . .3-7).
3-7. HDLC
| ) | N(s) | P/F | N(r) | |||||||||
| ) | P/F | N(r) | ||||||||||
| ) | P/F | N(r) | ||||||||||
|
|
|
.3-7 :
N(s), N(r) - (s) () , 3 , 8;
P/F - () (F); , , , - ; ;
- , LAPB 3 ;
FCS - CRC 16- .
HDLC 1 3. 3 "". HDLC " " 3 , HDLC " ". 3 :
(NRM), (, ) ( ) ;
(ARM), ;
(), , .
HDLC "" "".
