Juniper Networks MX480 - 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 Table 44 on page 309 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
Table 45 on page 310 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. 310
MX480 3D Universal Edge Router Hardware Guide