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Site Wiring Guidelines
Subtracting the data link loss from the power budget should produce a result greater than
zero. If a result is less than zero, you may have insufficient power for receiver operation.
For SONET line cards, the signal must meet the signal requirements listed in Table 2-6.
Table 2-6
Characteristic
Minimum transmitter
power (PT)
Minimum receiver
sensitivity (PR)
Power Budget (PB)
Multimode Power Budget Example (with Sufficient Power for Transmission)
This section contains a sample calculation of a multimode power budget, based on the
following variables:
•
Length of multimode link = 3 km
•
Four connectors
•
Three splices
•
Higher order loss (HOL)
•
Clock recovery module (CRM)
Estimate the power budget, as follows:
PB = 13 dB – 3 km (1.0 dB/km) – 4 (0.5 dB) – 3 (0.5 dB) – 0.5 dB (HOL) – 1 dB (CRM)
PB = 13 dB – 3 dB – 2 dB – 1.5 dB – 0.5 dB – 1 dB
PB = 5 dB
The resulting power budget (PB) value of 5 dB indicates that this link would have sufficient
power for fiber-optic transmission.
2-24
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide
Line Card SONET Signal Requirements
Single-Mode
–18.5
–30
–11.5
Multimode
–15
–28
–13
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Troubleshooting
