- , . 20- . PNNI (Private NNI), . , .25, PNNI.
(Virtual Channel Identifier, VCI), . , , , , , , , . ., , IP- CIDR.
(Permanent Virtual Circuit, PVC) (Switched Virtual Circuit, SVC). - Virtual Path, , . (Virtual Path Identifier, VPI) . , - ( ) ( ).
UNI (User Network Interface). UNI , , , , . UNI 4.0, , , UNI 3.1.
. SDH/SONET, . - -3 155 /. Forum SDH, -3 -12 (622 /). 155 / - , 5. 622 / - , SMF, MMF.
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, SDH/ SONET. 1/1 /, , - 4/5 100 / (FDDI) 25 /, IBM Forum. , 155,52 / cell-based , , , SDH/SONET. SDH/SONET, , , .
, , , . , .
. , . - , ( ) 200, - 20. , .
, , , , , ( ) (- ).
. 6.29.
. 6.29. : - ; -
. (, 29 4500 , FDDI), . , 4500 2 / ( frame relay) 18 . 144 . , , - .
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, , - , - 53 . - cell. 48 , - 5 .
, - 24 , ( ) .
- 32 , - 64 .
, , . , , , .
, 53 , 155 / 3 . , 125 .
, . - , . 48 48 , 125 . 6 , . , 6 - , , . 32 4 , . 64 - . 48- 10 %, 32- 16 %.
, . , frame relay. frame relay ( frame relay ), , , 4 , .
( - service class) . , , , , , , , - , , , , . - , , .
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, , . - (Constant Bit Rate, CBR) (Variable Bit Rate, VBR).
, , . , , . , .
, :
, CBR VBR;
;
, , - ( ). . 6.4.
6.4.
, , , . , . , , , - , . , .
:
Peak Cell Rate (PCR) - ;
Sustained Cell Rate (SCR) - ;
Minimum Cell Rate (MCR) - ;
Maximum Burst Size (MBS) - ;
Cell Loss Ratio (CLR) - ;
Cell Transfer Delay (CTD) - ;
Cell Delay Variation (CDV) - .
, - , - . , PCR, . . , .
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- QoS. ( RCR, SCR, MCR, MBS), (CTD CDV), (CLR). QoS, . QoS CTD, CDV CLR. , , , .
- . , frame relay, , , . frame relay , .
, ( QoS) , .
, . X, , QoS, - .
QoS, , Best Effort . - Unspecified Bit Rate, UBR.
- , , , . UBR , , , .
, ( frame relay, ). - , , , .
6.30, - . 6.31.
. 6.30.
. 6.31.
ISO/OSI , . OSI .
AAL
( Adaptation Layer, AAL) AAL1-AAL5, . OSI, TCP UDP. AAL (. . 6.31), .
AAL . AAL, . AAL , AAL.
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. AAL (Segmentation And Reassembly, SAR). AAL (, , ) () , AAL or , , .
AAL - Convergence Sublayer, CS. . , , , ( , ), , (.25, frame relay).
AAL , AAL. , , SAR AAL ( ) AAL, , 48- , . AAL AAL .
AAL . , AAL, - . , . ( ) , .
AAL1 (Constant Bit Rate, CBR), , , . , . AAL1 1 2 , 47 46 . , , . , 125 , , 12546 . , . AAL1 .
AAL2 , , AAL1, AAL3/4 AAL5.
AAL3/4 - - (Variable Bit Rate, VBR). , , . AAL3/4 , . , , - , . AAL3/4 AAL3 AAL4, . AAL3 AAL4 .
AAL5 AAL4 , , . AAL5 frame relay, . AAL5 , , . , , D. AAL5 CBR, .
AAL5 , . , . , AAL5 , .
, , AAL. ( , ) , , , QoS. QoS: - , - . , .
QoS AAL . - . , .
, IP TCP/IP LAP-F frame relay. , . , - (Virtual Path Identifier, VPI) (Virtual Channel Identifier, VCI). - , -, - , (, - ).
, . 6.32.
. 6.32.
(Generic Flow Control) . .
(VitualPath Identifier, VPI) (Vitual Channel Identifier, VCI) 1 2 . , (VPI) (VCI) .
(Payload Type Identifier, PTI) 3- , , - (, ). , - Explicit Congestion Forward Identifier, EFCI - , FECN frame relay, .
(Cell Loss Priority, CLP) , DE frame relay - , , . , CLP=0 , CLP=1 - .
(Header Error Control, ) , . , , , . , SDH, , , . , STS-n (STM-n) SONET/SDH ( , , , 1/1), . 5 , STM-n, , , . , . , SDH , .
VPI/VCI. - . VPI, VCI . . , . , .
VPI, VCI, , VCI, VPI . .
, . 6.30. ISDN - Q.2931, . Q.931 Q.933 ( ), , , , . Q.2931 SSCOP, Q.2931 . , SSCOP AAL5, SSCOP SSCOP .
Q.2931 UNI 3.1, UNI 3.0 Q.93B. - Q.2931 Q.93B UNI 3.0 UNI 3.1 . UNI 4.0 UNI 3.1, , UNI 3.1.
, Q.2931, () .
Q.2931 -- (point-to-point) -- (point-to-multipoint). , , , . -- , . , . , - . , , , , - ( ), .
Q.2931, , , Q.933, frame relay, , , .
20- . , ISO 7498. .164, 1 AFI, 8 IDI - .164 (15 ), 11 DSP (Domain Specific Part) .
4 DSP - High-Order Domain Spesific Part (HO-DSP), , , , PNNI, , CIDR IP.
6 - End System Identifier (ESI), - , - IEEE.
1 , , .
, , Forum. IDI 2 , Forum, ISO, DSP , HO-DSP 4, 10 .
ESI - IEEE, 3 , - , .
. ESI - , , , .
CALL SETUP Q.2931, , , QoS. , . , CALL SETUP , , .