Juniper EX2300 Series Hardware Guide

mode loss (HOL) occurs. Together, these factors reduce the transmission distance of mulmode ber
compared to that of single-mode ber.
Single-mode ber is so small in diameter that rays of light reect internally through one layer only.
Interfaces with single-mode opcs use lasers as light sources. Lasers generate a single wavelength of
light, which travels in a straight line through the single-mode ber. Compared to mulmode ber, single-
mode ber has a higher bandwidth and can carry signals for longer distances. It is consequently more
expensive.
Exceeding the maximum transmission distances can result in signicant signal loss, which causes
unreliable transmission.
Aenuaon and Dispersion in Fiber-Opc Cable
An opcal data link funcons correctly provided that modulated light reaching the receiver has enough
power to be demodulated correctly. Aenuaon is the reducon in strength of the light signal during
transmission. Passive media components such as cables, cable splices, and connectors cause
aenuaon. Although aenuaon is signicantly lower for opcal ber than for other media, it sll
occurs in both mulmode and single-mode transmission. An ecient opcal data link must transmit
enough light to overcome aenuaon.
Dispersion is the spreading of the signal over me. The following two types of dispersion can aect
signal transmission through an opcal data link:
• Chromac dispersion, which is the spreading of the signal over me caused by the dierent speeds
of light rays.
• Modal dispersion, which is the spreading of the signal over me caused by the dierent propagaon
modes in the ber.
For mulmode transmission, modal dispersion, rather than chromac dispersion or aenuaon, usually
limits the maximum bit rate and link length. For single-mode transmission, modal dispersion is not a
factor. However, at higher bit rates and over longer distances, chromac dispersion limits the maximum
link length.
An ecient opcal data link must have enough light to exceed the minimum power that the receiver
requires to operate within its specicaons. In addion, the total dispersion must be within the limits
specied for the type of link in Telcordia Technologies document GR-253-CORE (Secon 4.3) and
Internaonal Telecommunicaons Union (ITU) document G.957.
When chromac dispersion is at the maximum allowed, its eect can be considered as a power penalty
in the power budget. The opcal power budget must allow for the sum of component aenuaon,
power penales (including those from dispersion), and a safety margin for unexpected losses.
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Juniper EX2300 Series Specifications

General

Software	Junos OS
Model	EX2300
Ports	24 or 48 10/100/1000BASE-T ports
Uplinks	4 x 1GbE/10GbE SFP+/SFP uplinks
Power Supply	Internal or external power supply options
Rack Units	1U
PoE/PoE+ Ports	Available on some models (EX2300-C and EX2300)
Operating Temperature	0° to 45°C
Input Voltage	100 to 240 VAC
Layer 3 Features	RIP, OSPF, VRRP
Layer 2 Features	VLAN, STP, RSTP, MSTP, LACP
Security Features	802.1X, DHCP snooping
Management	CLI, Web UI, SNMP