1962., Bell System () 24 . - DS1 ( 1). 1, 24 DS0 (64-/), 1544 /.
1 - (PDH). 1 DS1C (3 /, 48 DS0); DS2 (6 /, 96 DS0), 2, DS3 (45 /, 672 DS0), . (1344 ) 4 (6048 ). - 274-432 /. () 4ESS (Bell System) 1976, - () - 1980. Tl, T2 (AC) PDH, ITU-T 1984.
-30 1, () 32 2048 /. () PDH (1, 2, 4 - 2, 8, 34, 140 /), ITU-T 1984.
( ) , , 1 2, () PDH (Tl, T2, JDS3 JDS4 - 1,5; 6; 32 97 /), ITU-T 1984.
PDH 1988., (SDH), . .3-2.
3-2. PDH
| / | ITU-T | ||||||
| 1 | ITU-T G.702 | 1,544 / | , | 1600 | AMI/B8ZS | ||
| 1 | 3,152 | , | 1600 | ||||
| 2 | ITU-T G. 702 | 6,312 | , | 1800 | B6ZS/B8ZS | ||
| ITU-T G.702 | 44,736 | 6 | B3ZS | ||||
| 90,524 | 6 | B3ZS | |||||
| 4-144 | 144,000 | 10-20 | / | ||||
| 4 | 274,176 | 1800 | B3ZS | ||||
| 4-432 | 432,000 | 10-20 | / | ||||
| 1 | ITU-T G.702 | 2,048 | , | 2000 | HDB3 | ||
| 2 | ITU-T G.702 | 8,448 | , | 2000 | HDB3 | ||
| ITU-T G.702 | 34,368 | , | 6-20 | HDB3 | |||
| 4 | ITU-T G.702 | 139,264 | , | 3-20 | CMI | ||
| 5 | 564,992 | , | 1-10 | / | |||
| JDS3 | ITU-T G.702 | 32,064 | , | 6-20 | AMI | ||
| JDS4 | ITU-T G.702 | 97,728 | , | 6-20 | AMI | ||
| JDS5 | 397,200 | . | 3-20 | / |
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.3.2 , ITU-T (G.702). , , -, , .
SONET/SDH. ( PDH) 140 / (4). PDH ( -), , , : (SONET ) (SDH ). SONET/SDH. .
, , , , (64 /), , .
ISDN. , , , 19761980. : , ISDN. - ISDN. 2 (128 /), (D=16 /), .. 2B+D (144 /, - 160 /). -- : ISDN (N-ISDN). 23B+D () 30B+D (), : ISDN (B-ISDN) 1980 / () D=64 /.
, , , .. SS#7, 7 (). - , , , , Frame Relay (FR), - (ATM).
WDM. SONET/SDH 1990- ( 2,5 10 /) , , - (PMD). SDH , , (WDM). , , . 320 , , 10 /, 320x483840=154 828 800 .
(. .3-3) WDM , . , - : Ethernet, IP, X.25, FR, ATM, PDH SDH. .
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