R&M Data Center Handbook

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An example of this:
It should be possible to transmit 10
gigabit Ethernet per IEEE 802.3ae
standards over the maximum distance
of 300 m with OM3 fibers. In accordance
with the standard, 1.5 dB will
remain for connection losses after deducting
fiber attenuation and power
penalties (graphic, red line). Operating
with current grade M multimode connectors
and an insertion loss of 0.75 dB
per connector, two plug connections
would therefore be possible. However,
this is not very realistic.
Looking at it from the other side, assume
that we want to use two MPO
and two LC plug connections. With an
insertion loss of 0.75 dB per connection,
total attenuation will amount to 3 dB.
As a result, the link could only measure
about 225 meters (graphic, green line).
Determining the Attenuation Budget of an OM3 Fiber
with 10 gigabit Ethernet
Blue: Remaining attenuation budget for connections
Red: Remaining budget for 300-meter length
Green: Remaining line length for two MPO and two LC connectors
The same example, using a data rate of 40 Gbit/s, decreases the link to 25 meters. This shows that the attenuation
budget available for connections becomes smaller and smaller as the data rate increases.
Since up to this point the IEC 61755 group of standards could not present any reliable, and above all meaningful
values, R&M defined its own quality grades for multimode connectors – based on the empirical values acquired
over years of experience. These multimode grades are based on the classification for single mode, extended by
grade E M or grade 5 for PCF and POF connectors.
Grades in accordance with IEC 61753-1:
IL, Insertion Loss > 97 % Mean Comments
Grade A < 0.15 DB < 0.07 dB Not yet conclusively established
Grade B < 0.25 dB < 0.12 dB
Grade C < 0.50 dB < 0.25 dB
Grade D < 1.00 dB < 0.50 dB
Grade M < 0.75 dB (100 %) < 0.35 dB Not specified in IEC 61753-1
RL, Return Loss 100 % Comments
Grade 1 > 60 dB > 55 dB in unplugged state (APC only)
Grade 2
Grade 3
Grade 4
> 45 dB
> 35 dB
> 26 dB
Grades for R&M multimode connectors:
IL 100 % 95 % Median RL 100 % Comments
Grade A M 0.25 dB 0.15 dB 0.10 dB Grade 2 45 dB
Grade B M 0.50 dB 0.25 dB 0.15 dB Grade 3 35 dB
Only LSH, SC and LC
single-fiber connectors
Only single-fiber
connectors
Grade C M 0.60 dB 0.35 dB 0.20 dB Grade 4 26 dB Multi-fiber connectors
Grade D M 0.75 dB 0.50 dB 0.35 dB Grade 4 26 dB Similar to current grade M
Grade E M 1.00 dB 0.75 dB 0.40 dB Grade 5 20 dB For PCF and POF
R&M Data Center Handbook V2.0 © 08/2011 Reichle & De-Massari AG Page 121 of 156