Juniper EX8208 Complete Hardware Manual page 142

Complete Hardware Guide for EX8208 Ethernet Switches
Table 52: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Modal and chromatic dispersion
Connector
Splice
Fiber attenuation
Clock Recovery Module (CRM)
Related
Documentation
116
Estimated Link-Loss Value
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 (
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
M
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.
Calculating the EX8200 Switch Fiber-Optic Cable Power Budget on page 114
Optical Interface Support in EX8200 Switches on page 60
Understanding EX8200 Switch Fiber-Optic Cable Signal Loss, Attenuation, and
Dispersion on page 100
Sample (LL) Calculation Values
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) = 1dBm
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
LL ) from ( P ):
B
M
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