CIR. PVC/SVC .. , (Vim). , , CIR : 9,6; 19,2; 32; 48; 64 / ( V =64 /) 9,6xN; 19,2xN; 32xN; 48xN; 64xN / ( V =Nx64 / ≤ 1/) 1-/ STM-0/OC-1.
OR FR , .
.. , .. ( , V).
. FR , , ( ) FR.
, . .
FR
, FR OSI (1 2), .. FR , .
FR, , ISDN, . : (U) (), FR PVC SVC. - (.5-2), PVC, , , FR .
. 5-2. FR PVC
Q.921 LAPD, .. - PVC, SVC, Q.921 Q.922. Q.922 core Q.922 control , - : core- ( ), PVC, control- (
), - Q.921. Q.922 core LAPF.
Q.921 (LAPD)
Q.921 (LAPD) :
- , ;
- / ;
- : ;
- ( ).
LAPD LAPB, ISDN. , D- - 16/64 /, , 3 (OSI). D- .25, FR ATM.
|
|
|
LAPD :
- ( , .25);
- ( );
- ( , .25).
, . . , , FR, .
3- , ( ) . , LAPB. : , . D-.
LAPD
LAPD 6 (.5-1).
5-1. LAPD
| Flag | Address | Control | FCS | Flag | |
| 1 | 2 | 1/2 | l/U- | 2 | 1 |
Flag - ( ) - 1 : 01111110 - ; "0" , ;
Address - - 2 ( , );
Control - - 1/2 - - 1 (U-) 2 - ;
- // - 1- ( U-); . 1.441, - 260 ( .. 2100 ), .. 4096 ;
FCS - - 2 - ( R-16).
, : - 6/5 / , ,
FCS, 1 . .. .
