I- (I-) (I/S-) m ( .25), - 0 < <127. .25 - (m =128), .
, , , .5-4 ( - ).
5-4. LAPD m=128
| 1- | I | N(s) | P | N(r) | ||||||||
| S- | RR | RR | P/F | N(r) | ||||||||
| RNR | RNR | P/F | N(r) | |||||||||
| REJ | REJ | P/F | N(r) | |||||||||
| U- | SABME | P | ||||||||||
| UI | P | |||||||||||
| DISC | P | |||||||||||
| DM | F | |||||||||||
| UA | F | |||||||||||
| FRMR | F | |||||||||||
| .. | XID | XID | P/F | |||||||||
| : | 10-16 |
.5-4 /:
I - - I (m=128); , .. P/F, () , N(r) N(s);
RR - ( N(r)-1), ;
RNR - - , - 1-;
REJ - - , 1- N(r), - REJ;
SABME - - , .., , UA;
UI - - UI; ;
DISC - - , .., -, UA;
DM - - , , DTE DCE ;
UA - (-) - ;
FRMR - - , ; XID - () - / ; XID 260 .
|
|
|
FR, , 1 2. 2 - - - (UNI) FR
, . Q.921 HDLC. (LAPD core) .5-5. FR (LAPD). - , DLCI ( LLI - ) 13 (6+7) , .. 0 8191. , DLCI=0 , DLCI=8191 - , 8190 .
LAPD core .5-5, - .5-56, .
5-5. LAPD core
| Flag | Address | FCS | Flag | |
| 1 | 2 | l/U- | 2 | 1 |
5-5. LAPD core
| DLCI0 | Res | EA0 | DLCI1 | EA1 | |||||||||||
- RES - , C/R;
- 0 (=0) EA1 (=1) - ( ), (- 1);
- DLCI - DLC - 2, : DLCI0 DLCI1, TEI SAPI.
-, (LC) . DLC- ( 2).
Q.922(LAPF)
FMBS 2 : core control, . Q.922. : , , , , FRBS - (U-), . . 1.233.1.
. Q.922 LAPD. FMBS, LAPF. LAPF, core- ( Q.922-core), FRBS. LAPF Q.922-control.
LAPF - (SDU) - U (. .5-2) UNI ISDN -, D- -. FMBS Q.933 ( SVC), - PVC. LAPF UNI- (. . 1.430, 1.431).
LAPD, LAPF -, D- -. , LAPF :
- core-, Q.922-core;
- ( ) Q.922-core;
|
|
|
- ISDN- (-, D- ) ( LAPD) D-;
- : SVC PVC PVC .25.
LAPF , 2 . control- LAPD (. .5-1), core- , LAPD-core (. .5-5), .
LAPF-core , .5-6. .5-7 : 2 ( , .5-7); 3 (.5-7).
5-6. LAPF-core
| 1 Flag | Address | FCS | Flag | |
| 1 | 2/3/4 | l/U- | 2 | 1 |
5-7. 2- LAPF-core
| DLCI ( - msb) | C/R | 0 | ||||||
| DLCI | FECN | BECN | DE | 1 |
5-7. 3- LAPF-core
| DLCI ( - msb) | C/R | EA0 | ||||||
| DLCI | FECN | BECN | DE | EA0 | ||||
| DLCI (. - Isb.) DL-core control | D/C | EA1 |
D/C=0, Isb DLCI 3 4, D/C=1, - 5 3
- DLCI - , : 10 ( 2-) 16 ( 3-);
- 0 (=0) EA1 (=1) - , ; C/R - "/".
, FR, D/C:
- FECN - , -;
- BECN - , -;
- DE - / ;
- D/C - : DLCI ( , D/C=0) DL-core control DL-core ( D/C=1).
DLCI ( .5-8 10/16 ).
5-8, . 10- () 16- DLCI
| DLCI | |
| )0 | ( ) |
| 1-15 | |
| 15-511 | : D-, |
| 512-991 | ID 1 |
| 992-1007 | 2 FMBS |
| 1008-1022 | |
| / ( ) | |
| ) 0 | ( ) |
| 1-1023 | |
| 1024-32767 | : D-, |
| 32768-63487 | ID 1 |
| 63488-64511 | 2 FMBS |
| 64512-65534 | |
| ( ) |
( .5-6) .. 1 8 , .. 1,6-4 . . Q.922 260 262 ( LAPD D-), - 1598 1600 , . , ( Flag Address) - (FCS Flag) , . : " ". , . LMI - .
|
|
|
, FR , , , .
FR , , : TCP/IP, IPX, DECNet, AppleTalk, X.25 .
FR , PVC , .5-8 ( DLCI).
