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
Fiber-Optic and Network Cable Specifications for the M120 Router on page 241
•
•
Attenuation and Dispersion in Fiber-Optic Cable on M Series, MX Series, and T Series
Routers on page 243
•
Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 244
•
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable for the M120 Router on
page 242
Routing Engine Interface Cable and Wire Specifications for the M120 Router
For management and service operations, you connect the Routing Engine to an external
console or management network. (For more information, see “M120 Routing Engine
Description” on page 18.)
Table 35 on page 246 lists the specifications for the cables that connect to management
ports and the wires that connect to the alarm relay contacts.
Table 35: Routing Engine Interface Cable and Wire Specifications
Router
Receptacle
Maximum
Length
Cable/Wire Supplied
Cable Specification
Port
DB-9 male
6 ft (1.83 m)
One 6-ft (1.83-m) length
with DB-9/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
—
None
No
Wire with gauge between
24-AWG and 12-AWG (0.20 and
3.33 mm
2
)
Alarm relay contacts
Related
Documentation
•
Replacing Connections to M120 Routing Engine Interface Ports on page 132
•
M120 Routing Engine Description on page 18
Copyright © 2010, Juniper Networks, Inc.
246
M120 Multiservice Edge Router Hardware Guide
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