Itu-t rec. G. 957 (06/99) Optical interfaces for equipments and systems relating to the synchronous digital hierarchy

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T-REC-G.957-199907-S!!PDF-E
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Table IV.1/G.957 – Grade classification for long-haul applications Maximum attenuation STM-1 STM-4 STM-16
Figure IV.1/G.957 – Maximum attenuation for STM-N long-haul inter-office interfaces with two grades

IV.2 Example
2
Another approach to upgradability is to employ the concept of a set of grades in higher order STM-N
systems for the long-haul inter-office interfaces. Table IV.1 and Figure IV.1 show the grade
classification based on maximum attenuation. Parameter values for the various grades are for further
study. These grades might be applied by users when considering network planning and cost
performance, etc. Moreover, higher grade system design should allow incorporation of future
technology advances and changing service requirements.
Table IV.1/G.957 – Grade classification for long-haul applications
Maximum
attenuation
STM-1 STM-4 STM-16
28 dB
Grade 1
Grade 2
Grade 2
24 dB
–
Grade 1
Grade 1

Recommendation G.957 (06/99)
30
T1518700-95
0
10
20
30
28 dB
24 dB
dB
STM-1
STM-4,
STM-16
Upgradability
Grade 2 (upgrade compatible value from lower STM-level)
Grade 1
M
a
xi
m
u
m
at
te
nua
ti
on
Figure IV.1/G.957 – Maximum attenuation for STM-N long-haul
inter-office interfaces with two grades

ITU-T RECOMMENDATIONS SERIES
Series A
Organization of the work of the ITU-T
Series B
Means of expression: definitions, symbols, classification
Series C
General telecommunication statistics
Series D
General tariff principles
Series E
Overall network operation, telephone service, service operation and human factors
Series F
Non-telephone telecommunication services

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