, , , , OSI. , , , . OSI, , , , .
, , . , Internet. , Internet, . Web- , , , , , - chat, ( News), .
( ) , , , Internet, , chat, .
Internet , . Web-, , . - intranet, , Internet . intranet Web, Internet , , , Internet .
- .
, . , .
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. 5.2. : S (switch) - , - , R (router) - , MUX (multiplexor)- , UNI (User-Network Interface) - - NNI (Network-Network Interface) - - . , , - DCE, .
. 5.2.
() , . (), , - , cell. , , . , frame relay , .
, , . , , , , , .
. , , , . , , . , , , . , - . - , .
- . ( ), .
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, . . 5.2. : , , R MUX, ( ). , DTE (Data Terminal Equipment). ( ), DTE - .
, , . , (remote bridges), - , - . , , , , , , . - (, IP IPX) , , frame relay, , .
- . , - , , , , . , , . - , , - , - . , . - . , , - frame relay, ATM.
, DTE DCE (Data Circuit terminating Equipment) . DCE : , DSU/CSU TDM () ISDN. DTE DCE , - Customer Premises Equipment, CPE.
, , . - , .
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- (User-to-Network Interface, UNI). , , UNI (, .25).
, -(Network-to-Network Interface, NNI), . , , , , , . , , -, -, , . NNI , , .
. 5.2 - . , , . 2-3 , , .
, , . 5.2, .
. , , . , .
, , , :
;
;
.
, , . , .
44. : SLIP, DL, PPP.
SLIP (Serial Line Internet Protocol) OSI TCP/IP IP-. - -. PPP.
SLIP 80- 3COM. Berkeley Unix 4.2 (Rick Adams) 1984, COM-, . .
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IP-, SLIP .
SLIP IP. SLIP IP . IP- .
UART: 8 (8 data bits), (no parity), (EIA hardware flow control) - (3-wire null-modem CLOCAL mode).
-, IP- (). SLIP- END (0xC0). - (byte stuffing) ESC- 0xDB, END (0x0) (0xDB, 0xDC), ESC (0xDB) (0xDB, 0xDD).
IP-.
IP.
, TCP.
- (+20 %), SLIP- IP-(+20 ) , -.
1006 Berkeley Unix.
High-Level Data Link Control (HDLC) -[1] OSI, ISO.
HDLC ISO 13239.
HDLC , - (ABM).
() (Primary terminal) . . - .
() (Secondary terminal) , . 1 .
(Combined terminal) , . . -.
3 :