Cb-Re Interface Cable And Wire Specifications For Mx Series Routers - Juniper MX2020 Hardware Manual

MX2020 3D Universal Edge Router Hardware Guide
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CB-RE Interface Cable and Wire Specifications for MX Series Routers

130
Table 42: Estimated Values for Factors Causing Link Loss (continued)
Link-Loss Factor
Connector
Splice
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 127
Table 43 on page 131 lists the specifications for the cables that connect to management
ports and the wires that connect to the alarm relay contacts.
Estimated Link-Loss Value
0.5 dB
0.5 dB
Single-mode—0.5 dB/km
Multimode—1 dB/km
Table 42 on page 129
) is calculated as follows:
M
Table 42 on page 129
Copyright © 2015, Juniper Networks, Inc.
to calculate link loss
to calculate link loss
) is calculated as
M