Table 67: Estimated Values For Factors Causing Link Loss - Juniper EX4300 Hardware Manual

EX4300 Switch Hardware Guide

Table 67: Estimated Values for Factors Causing Link Loss

Link-Loss Factor
Higher-order mode losses (HOL)
Modal and chromatic dispersion
Connector
Splice
Fiber attenuation
Clock Recovery Module (CRM)
104
as provided in Table 67 on page 104
the (P ) is 13 dBm):
B
Estimated Link-Loss Value
Multimode—0.5 dBm
Single mode—None
Multimode—None, if product of
bandwidth and distance is less than
500 MHz/km
Single mode—None
0.5 dBm
0.5 dBm
Multimode—1 dBm/km
Single mode—0.5 dBm/km
1 dBm
NOTE: For information about the actual amount of signal loss caused by
equipment and other factors, see your vendor documentation for that
equipment.
Calculate the (P ) by subtracting (LL) from (P
2.
M
P – LL = P
B M
(13 dBm) – (0.5 dBm [HOL]) – ((5) * (0.5 dBm)) – ((2) * (0.5 dBm)) – ((2 km) *
(1.0 dBm/km)) – (1 dB [CRM]) = P
13 dBm – 0.5 dBm – 2.5 dBm – 1 dBm – 2 dBm – 1 dBm = P
13 dBm – 0.5 dBm – 2.5 dBm – 1 dBm – 2 dBm – 1 dBm = P
P = 6 dBm
M
The calculated power margin is greater than zero, indicating that the link has sufficient
power for transmission. Also, the power margin value does not exceed the maximum
receiver input power. Refer to the specification for your receiver to find the maximum
receiver input power.
(here, the link is 2 km long and multimode, and
Sample (LL) Calculation Values
0.5 dBm
0 dBm
0 dBm
0 dBm
This example assumes 5 connectors.
Loss for 5 connectors:
(5) * (0.5 dBm) = 2.5 dBm
This example assumes 2 splices. Loss for
two splices:
(2) * (0.5 dBm) = 1 dBm
This example assumes the link is 2 km
long. Fiber attenuation for 2 km:
(2 km) * (1.0 dBm/km) = 2 dBm
(2 km) * (0.5 dBm/km) = 1 dBm
1 dBm
):
B
M
M
M
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