Frame Relay ..
| FCS | ||||
| 1 | 2 | 2 | 1 |
.
, Frame Relay.
Frame Relay .
FCS 16- Frame Relay "".
Frame Relay:
;
;
;
.
Frame Relay:
;
;
;
- .
ATM
(Asynchronous ^ansfer Mode) 90- . :
N-ISDN , ( 2 /) () ;
.25 ( 64 /) ;
Frame Relay .
:
;
( ) ;
;
;
(Ethernet, IP, ISDN .).
:???
.
:
- , , ;
|
|
|
;
- .
, , 53 . (cell). - . ( ) ( , ), 155 /
2,2 / ( 10 /).
, UNI
- .
(Customer Premises Equipment) - - .
UNI (User - Network Interface) - - .
NNI (Network - Network Interface) - - .
|
. . - , .
, - .
- . , :
- (UNI, User-to-Network Interface), - ;
- (NNI, Network-to-Network Interface), .
??
- 53 , 5 48 - . , UNI NNI, (. 21.8).
| 384 < | ||||||
| GFC | VPI | VCI | PT | CLP | HEC | |
| UNI, 5 | , 48 | |||||
| 384 | ||||||
| VPI | VCI | PT | CLP | HEC | ||
| NNI, 5 | , 48 |
UNI NNI GFC (Generic Flow Control) - , UNI , , . NNI , , VPI.
VPI (Virtual Path Identifier), . , , , .
VCI (Virtual Channel Identifier), , . , , VCI. VCI VPI - . , VPI VCI , .
|
|
|
PT (Payload Type), , . 0, - 1.
CLP (Congestion Loss Priority), , 1 , .
HEC (Header Error Control), , , .
, VCI VPI:
;
.
, .
, .
VCI VPI. , - . - , VPI VCI.
-
- :
(PVC, Permanent Virtual Circuits) , . ( ) .
(SVC, Switched Virtual Circuits) - , .
(connectionless service) .
, ATM, ( ),
| (CBR, Constant Bit Rate) , , ( ). | |
| B | (VBR, Variable Bit Rate) , , , . |
| C | , , - TCP, X.25 .. |
| D | , , , - IP (UDP), Ethernet .. |
| X | , . |
-
- :
|
|
|
, CLR (Cell Lost Ratio);
- - ( ) CDV (Cell Delay Variation);
Max CTD (Maximum Cell ^ansfer Delay);
Mean CTD (Mean Cell ^ansfer Delay);
MCR (Minimum Cell Rate).
:
;
, ;
;
.
:
;
;
, ;
.
