Routers, Alarm interfaces – Juniper Networks MX480 User Manual
Page 334
P
M
= P
B
– LL
P
M
= 13 dB – 2 km (1.0 dB/km) – 5 (0.5 dB) – 2 (0.5 dB) – 0.5 dB [HOL] – 1 dB [CRM]
P
M
= 13 dB – 2 dB – 2.5 dB – 1 dB – 0.5 dB – 1 dB
P
M
= 6 dB
The following sample calculation for an 8-km-long single-mode link with a power budget
(P
B
) of 13 dB uses the estimated values from
to calculate link loss
(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
M
) is calculated as
follows:
P
M
= P
B
– LL
P
M
= 13 dB – 8 km (0.5 dB/km) – 7(0.5 dB)
P
M
= 13 dB – 4 dB – 3.5 dB
P
M
= 5.5 dB
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.
Related
Documentation
Supported Network Interface Standards by Transceiver
•
•
Understanding Fiber-Optic Cable Signal Loss, Attenuation, and Dispersion on page 307
Routing Engine Interface Cable and Wire Specifications for MX Series Routers
lists the specifications for the cables that connect to management
ports and the wires that connect to the alarm relay contacts.
Table 45: Cable and Wire Specifications for Routing Engine Management
and Alarm Interfaces
Router
Receptacle
Maximum
Length
Cable/Wire
Supplied
Cable
Specification
Port
RJ-45 female
6 ft (1.83 m)
One 6-ft
(1.83-m) length
with RJ-45/DB-9
connectors
RS-232
(EIA-232) serial
cable
Routing Engine
console or
auxiliary
interface
RJ-45
autosensing
328 ft (100 m)
One 15-ft
(4.57-m) length
with
RJ-45/RJ-45
connectors
Category 5 cable
or equivalent
suitable for
100Base-T
operation
Routing Engine
Ethernet
interface
Copyright © 2013, Juniper Networks, Inc.
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MX480 3D Universal Edge Router Hardware Guide