Juniper EX9214 Hardware Manual page 128

EX9214 Switch Hardware Guide
Table 49: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Splice
Fiber attenuation
Clock Recovery Module (CRM)
Related
Documentation
104
Estimated Link-Loss Value
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
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 EX Series Switch Fiber-Optic Cable Power Budget on page 102
Understanding EX Series Switches Fiber-Optic Cable Signal Loss, Attenuation, and
Dispersion on page 123
Pluggable Transceivers Supported on EX Series Switches on page 106
Sample (LL) Calculation Values
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
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