. ..
( HDLC, .25 )
6
2008
() , . ( ) .
() () ( V.24, X.21, RS-232 .), .. , .
( , .) - .
, , .. .
[1] , .25 I, S U -.
HDLC X.25 .
:
- ;
- ;
- .
, [1].
, . ( , , .) , , .
. :
NRM (Normal Response Mode);
ARM (Asynchronous Response Mode);
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|
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(Asynchronous Balance Mode).
NRM , . (, ) ( ) . , . , , , . . , ( ).
ARM . , NRM, , , .
. -, - . , , . .
, . .
() ( , ):
1. , , .. , . . , " " , , .
2. . .
3. , , ( ). .
4. , , . (, " ".)
5. (, ). . . "" ( , ).
|
|
|
, , , : ( , ), ( ) ( ).
, HDLC . .
, , , (ISO) [2], ().
, . 1.
1
| I | I |
| RR | RR |
| RNR | RNR |
| SABM | UA |
| DISC | DM |
| FRMR |
() . 2.
2
| / | ||
| () | XID XID | |
| I - | REJ REJ | |
| () I - | SREJ SREJ | |
| I - | UI UI | |
| ( "") | SIM RIM | |
| UP | ||
| , | ||
| 128 | SABME | |
| NR NS | RSET | |
| TEST TEST | ||
| RD |
1 2.
:
- . .
- .1. . . .
- .2. . . .
- .3. () . . .
- . .
" ", ( ) . , .
| NR; NS | P/F | ( ) | |
     |
, , .. , (. 1).
1
, ( ) . . U - SABM, . , .. ( , ) = 1.
|
|
|
, . ( - ) U - UA. ., ., F = 1, , = 1.
. . .
. . U - DISC = 1. . , U - DM . F = 1.
, .
.
.1. (-)
, , [4].
