Juniper M7i Hardware Guide

generate a single wavelength of light, which travels in a straight line through the
single-mode fiber. Compared with multimode fiber, single-mode fiber has higher
bandwidth and can carry signals for longer distances. It is consequently more expensive.
The router uses optical lasers for SONET/SDH PIC single-mode interfaces. These optics
comply with IR-1 of Bellcore GR-253-CORE Issue 2, December 1995 and ANSI TI.105.06.
For information about the maximum transmission distances and wavelength ranges
supported by multimode and single-mode (ATM and SONET/SDH) PIC interfaces, see
the interface module reference for your device. Exceeding the maximum transmission
distances can result in significant signal loss, which causes unreliable transmission.
Related
Documentation
Fiber-Optic and Network Cable Specifications for the M7i Router on page 91•
• Attenuation and Dispersion in Fiber-Optic Cable on M Series, MX Series, and T Series
Routers on page 91
• Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 93
• Calculating Power Margin for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers on page 94
Calculating Power Budget for Fiber-Optic Cable for M Series, MX Series, and T Series
Routers
To ensure that fiber-optic connections have sufficient power for correct operation, you
need to calculate the link's power budget, which is the maximum amount of power it
can transmit. When you calculate the power budget, you use a worst-case analysis to
provide a margin of error, even though all the parts of an actual system do not operate
at the worst-case levels. To calculate the worst-case estimate of power budget (P
B
),
you assume minimum transmitter power (P
T
) and minimum receiver sensitivity (P
R
):
P
B
= P
T
– P
R
The following hypothetical power budget equation uses values measured in decibels
(dB) and decibels referred to one milliwatt (dBm):
P
B
= P
T
– P
R
P
B
= –15 dBm – (–28 dBm)
P
B
= 13 dB
Related
Documentation
Fiber-Optic and Network Cable Specifications for the M7i Router on page 91•
• Signal Loss in Multimode and Single-Mode Fiber-Optic Cable for the M7i Router on
page 92
• Attenuation and Dispersion in Fiber-Optic Cable on M Series, MX Series, and T Series
Routers on page 91
93Copyright © 2019, Juniper Networks, Inc.
Chapter 12: Network Cable and Transceiver Planning

Juniper M7i Specifications

General

Brand	Juniper
Model	M7i
Category	Network Router
Language	English