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3 C O M
®
N J 10 0 N E T W O R K J A C K
Power over Ethernet
enables the
simultaneous
transmission of
voice and power
over Cat 5 or 5e
cabling.
3Com Network Jack AC Power Supply
(3CNJPSL) provides local power to
a single 3Com NJ100 Network Jack.
List price: $26.00
What is Power over Ethernet?
Power over Ethernet is simply the
transmission of power over an exist-
ing Ethernet cable. It has become the
preferred method for powering wire-
less access points and IP telephone
handsets. The IEEE is currently
developing a standard for Power
over Ethernet, labeled 802.3af.
Has the 802.3af specification been
ratified?
No, however, it is expected to be
ratified in 2002. 3Com is actively
involved with the standard, and the
3Com NJ100 Network Jack complies
with the proposed IEEE 802.3af speci-
fication for Power over Ethernet.
What are the advantages of Power
over Ethernet?
Power over Ethernet offers the follow-
ing benefits:
• Networked devices can obtain
power and data over the same
wiring, streamlining installation
and configuration.
• Power can be supplied over existing
Category 5 or 5e UTP wiring with-
out additional modifications or
requirements to the cabling plant.
• Power can be supplied to networked
devices without relying on end-user
action.
What are the dipswitches used for?
The dipswitches must be set to match
the power source. The default setting
is IEEE 802.3af-compatible Power
over Ethernet. Before setting the dip-
switches, make sure that power to the
3Com NJ100 Network Jack is off. For
specific dipswitch settings, consult
your Installation Guide.
Where are the dipswitches?
Before setting the dipswitches, make
sure that power to the 3Com NJ100
Network Jack is off. The dipswitches
are located on the back, above the
opening for the pass-through connec-
tors. For more information, consult
your Installation Guide.
In a Power-over-Ethernet-capable
network, the 3Com NJ100 Network
Jack can forward power to a device
connected to Port #1. How does
that work?
The 3Com NJ100 Network Jack is
not only designed to be powered by
Power over Ethernet, but it can also
forward power to a device such as an
IP phone that needs it as well. In the
example of the IP phone, you can plug
it into Port #1. If it's compatible with
the basic standards of the draft 802.3af
Power-over-Ethernet standard—48 V
DC and a resistive power discovery
scheme—the network jack will detect
the phone and forward power to it.
Since the 802.3af standard has not
been ratified, some equipment uses a
pre-standard detection scheme called
capacitive power discovery.
Does Port #1 forward power when
using local AC power supply?
Yes, power forwarding over the unused
pairs on Port #1 happens regardless
of the 3Com NJ100 Network Jack
power source.
Which Power-over-Ethernet
switches are compatible with the
3Com NJ100 Network Jack?
The 3Com NJ100 Network Jack should
be compatible with any Power-over-
Ethernet switch that complies with
the proposed 802.3af Power-over-
Ethernet standard.
3
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