LAPB , .25. , LAPB , SDLC HDLC. , LAPB ABM, . LAPB (DTE DCE) . LAPB , . , , LAPB : 1 (Information (I) frame). - ( ). 2 (Supervisory (S) frames). - . . S , I. 3 (Unnumbered (U) frames). - , . .
LAPB .
flag LAPB. , , . 01111110. 0, . 11111 0. address , - . 00000001 00000011. HDLC "".
control , (U, I S)), (, receiver ready - " ", disconnect - "") / . SDLC.
data . 3. PSN . FCS .
Frame Relay
Frame Relay (FR) -қ қ ү ә құғ. FR , X.25 қ, ұ , қ ә ғ , QoS . X.25 ө , қ ө , ә ә қ , ң- қғ. FR ү ғ :
-ң қғ . қ , ғ ;
- ұғ . , қ ғ .
FR ң ү қ ү: (SVC) ә ұқ (PVC). FR ө (PVC) ұқ . - FR- қ. FR ү :
DTE құғ (Data Terminal Equipment);
DCE құғ (Data Circuit-Terminating Equipment);
FRAD құғ (Frame Relay Access Device).