Routers; Routing Engine Interface Cable And Wire Specifications For Mx Series Routers - Juniper mx240 Hardware Manual

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Routing Engine Interface Cable and Wire Specifications for MX Series Routers

Copyright © 2016, Juniper Networks, Inc.
Table 62: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Fiber attenuation
The following sample calculation for a 2-km-long multimode link with a power budget
(P ) of 13 dB uses the estimated values from
B
(LL) as the sum of fiber attenuation (2 km @ 1 dB/km, or 2 dB) and loss for five connectors
(0.5 dB per connector, or 2.5 dB) and two splices (0.5 dB per splice, or 1 dB) as well as
higher-order mode losses (0.5 dB). The power margin (P
P = P – LL
M B
P = 13 dB – 2 km (1 dB/km) – 5 (0.5 dB) – 2 (0.5 dB) – 0.5 dB
M
P = 13 dB – 2 dB – 2.5 dB – 1 dB – 0.5 dB
M
P = 7 dB
M
The following sample calculation for an 8-km-long single-mode link with a power budget
(P ) of 13 dB uses the estimated values from
B
(LL) as the sum of fiber attenuation (8 km @ 0.5 dB/km, or 4 dB) and loss for seven
connectors (0.5 dB per connector, or 3.5 dB). The power margin (P
follows:
P = P – LL
M B
P = 13 dB – 8 km (0.5 dB/km) – 7(0.5 dB)
M
P = 13 dB – 4 dB – 3.5 dB
M
P = 5.5 dB
M
In both examples, the calculated power margin is greater than zero, indicating that the
link has sufficient power for transmission and does not exceed the maximum receiver
input power.
Understanding Fiber-Optic Cable Signal Loss, Attenuation, and Dispersion on page 122
Table 63 on page 126 lists the specifications for the cables that connect to management
ports and the wires that connect to the alarm relay contacts.
Chapter 10: Transceiver and Cable Specifications
Estimated Link-Loss Value
Single-mode—0.5 dB/km
Multimode—1 dB/km
Table 62 on page 124
) is calculated as follows:
M
Table 62 on page 124
to calculate link loss
to calculate link loss
) is calculated as
M
125