3Com IntelliJack NJ100 Instruction Manual

FREQUENTLY ASKED QUESTIONS
3Com®NJ100 Network Jack
Product Specifications
Is this a hub?
No. The 3Com®NJ100 Network Jack is
a four-port, 10/100 wire-speed switch
with one switched 10/100-uplink port
in the back of the unit. The five inte-
grated independent Fast Ethernet
transceivers are fully compliant with
IEEE 802.3 and 802.3u standards.
What colors are available?
The 3Com NJ100 Network Jack comes
in two colors:
• Black, 3CNJ100-BLK
• Cream, 3CNJ100-CRM
Which adapter plates are included
with the 3Com NJ100 Network Jack?
The single-unit pack includes three
adapter plates—blank, Avaya, and
Panduit—that match the network
jack color, black or cream. The
20-unit packs do not come with
adapter plates, which must be
ordered separately. Currently, the
20-unit packs of adapter plates are
only available in cream.
Are the switched ports autosensing
or autonegotiating?
All four switched ports support
IEEE-compliant 10/100 autonegotia-
tion and full duplex or half-duplex
connections.
What switch mode does the 3Com
NJ100 Network Jack utilize?
The 3Com NJ100 Network Jack uses
store-and-forward switch mode. Ethernet
packets from each port are buffered
until the full packet is received. Once
the packet is received, it is forwarded
to any one of the other ports based on
the destination MAC address. The
network jack switch cannot be config-
ured for “cut through” mode.
How many MAC addresses does the
switch table hold?
The 3Com NJ100 Network Jack includes
a high-performance lookup engine with
support for up to 4,096 MAC address
entries. It also includes automatic
learning and aging.
Network Compatibility
Are there compatibility issues with
other networking equipment in the
wiring closet?
No. The 802.3-compliant 3Com NJ100
Network Jack is designed as a client
device. Because it’s an unmanaged
switch, there’s no software to conflict
with your existing management or
networking applications.
Does the 3Com NJ100 Network Jack
support traffic prioritization, QoS,
or multiple VLANs?
No. The 3Com NJ100 Network Jack is
an unmanaged switch, so it doesn’t
deploy 802.1p traffic prioritization,
The cost-saving,
cabling alternative
for IEEE 802.3-
compliant LANs.

2
3COM®NJ100 NETWORK JACK
Quality of Service (QoS), or 802.1Q
VLANs. However, although it cannot
add VLAN or QoS information to the
frames as they pass through the switch,
the network jack supports any VLAN
or QoS tags the frames contain. Future
versions are expected to support
802.3p traffic prioritization.
VoIP Compatibility
Does the 3Com NJ100 Network Jack
support VoIP?
The 3Com NJ100 Network Jack can
accommodate voice traffic two ways:
In a converged voice and data net-
work environment, an IP phone can
be plugged into one of the 10/100
switched ports. To support Power
over Ethernet, the IP phone must be
plugged into Port #1 of the 3Com
NJ100 Network Jack. For more dis-
cussion of Power over Ethernet and
power forwarding, please review the
Power Sources section of this docu-
ment and the Power Considerations FAQ.
If voice and data networks are wired
separately, you can use one of the
3Com NJ100 Network Jack’s pass-
through ports as the connection point
for the IP phone. The pass-through
port is wired separately from the
switched 10/100 ports—with cable
being pulled and terminated in the
traditional manner.
An additional way to connect voice
and data through the network jack is
by using the pass-through port to
connect your legacy voice system to
the PBX in the telephone room.
Does the 3Com NJ100 Network Jack
adversely affect VoIP quality?
3Com lab tests of the 3Com NJ100
Network Jack indicate that even at
data transfer loads within 98 percent
of capacity, there is no significant
degradation in voice response or
quality—even when the other three
switched ports are actively connected.
Power Sources
Does the 3Com NJ100 Network Jack
require power?
Yes. The 3Com NJ100 Network Jack is
an active device and requires a source
of power, which must be purchased
separately. LEDs on the face indicate
power and LAN connectivity.
How is the 3Com NJ100 Network
Jack powered?
The 3Com NJ100 Network Jack is
powered by one of the following
options:
3Com Network Jack Single-Port
Power-over-Ethernet Midspan
Solution (3CNJPSE) provides
midspan power to a single 3Com
NJ100 Network Jack. This in-line
power source can be connected to
the network jack at the end-user
location or installed in the wiring
closet. List price: $29.00
3Com Network Jack Multiport
Power-over-Ethernet Midspan
Solution (3CNJPSE24) provides IEEE
802.3af-compatible midspan power
for up to 24 network jacks. It must be
installed in the wiring closet, where it
adds Power over Ethernet to any man-
ufacturer’s switch. This is the optimal
choice for installation convenience.
List price: $1,299.00
3Com Ethernet Power Sources
(3C10220, 3C10222) provide midspan
power for 12 or 24 ports, respectively.
3Com Ethernet Power Sources do not
conform to the proposed 802.3af stan-
dard. These 19-inch, rack-mountable
units were originally designed to
power 3Com NBX®telephone equip-
ment, but can also power 3Com NJ100
Network Jacks with the proper dip-
switch settings. 3C10220 List price:
$1,282.00 3C10222 List price: $1,683.00
Any 802.3af-compliant power-
forwarding device can be used to
provide midspan power for 3Com
NJ100 Network Jacks.
The 3Com®NJ100
Network Jack
supports VoIP
and the proposed
IEEE 802.3af
specification for
Power over Ethernet.

3COM®NJ100 NETWORK JACK
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

This unmanaged
network device is
fully compliant with
BICSI TIA 568A and
TIA 569A cabling
installation
standards.
4
3COM®NJ100 NETWORK JACK
3Com NBX System and the
3Com Network Jack
Will the 3Com NJ100 Network Jack
forward power to a 3Com NBX
handset if the 3Com Network Jack
Multiport Power-over-Ethernet
Midspan Solution (3CNJPSE24) is
powering the system?
No. The 3Com NJ100 Network Jack
and 3Com Network Jack Multiport
Power-over-Ethernet Midspan Solution
are designed to meet the current
version of the proposed 802.3af
Power-over-Ethernet specification.
As a result, they use a resistive power
discovery scheme. Any device
plugged into it must have a resistive
signature in order to have power for-
warded to it by the 3Com NJ100
Network Jack. Currently, the 3Com
NBX handset does not have a resistive
power discovery scheme.
In addition, the 3Com NBX handset
is designed for a 24 V system. The
802.3af specification is 48 V, as is
the 3Com NJ100 Network Jack. The
only way for an NBX handset to run
through a 3Com NJ100 Network Jack
today is if the handset has its own
local power source.
Are there plans to enable the 3Com
NJ100 Network Jack to power a
3Com NBX handset in the future?
We anticipate that IEEE will ratify
the 802.3af standard. Subsequently,
other networking products will most
likely transition to supporting this
type of Power-over-Ethernet. In the
interim, we are exploring possible
power options.
Traditional Wiring and
Current Installation Practices
What are the standards that govern
cabling in buildings?
TIA 568A and TIA 569A are the basic
standards. BICSI is generally recog-
nized as the governing body for the
professional cabling industry.
Will my cabling remain TIA 568A- and
TIA 569A-compliant after installing
the 3Com NJ100 Network Jack?
Yes. The 3Com NJ100 Network Jack
is a network device that complies
with TIA 568A and TIA 569A stan-
dards. Installing the network jack
terminates the Ethernet connection
to a switch port.
How does this fit with a structured
cabling system?
Connection from a structured cabling
system (SCS) to the 3Com NJ100
Network Jack is no different than
the connection from an SCS to an
Ethernet NIC in a PC. When connect-
ing an SCS and NIC, horizontal
cabling is pulled to the user’s work-
space and terminated to a female
RJ-45. The cable and connector
integrity are tested following TIA-
established methods. An approved
patch cord connects the female RJ-45
to the NIC.
In a similar way, the connection
between an SCS and the network jack
is established with a factory-tested
male-to-male cable. The network jack
presents the same interface back to
the switch as an Ethernet NIC in a PC.
The integrity of the signaling through
the network jack is tested at the fac-
tory and is also verifiable by the
installer using an optional test unit.
The procedure for doing this is estab-
lished as part of the 3Com Approved
Network Jack Installer Program.

Deploying a
network jack can
save up to 60
percent versus
traditional cabling
expansion and port
activation.
5
3COM®NJ100 NETWORK JACK
Why don't you have a punch-down
connector instead of an RJ-45 uplink
port on the back of the 3Com NJ100
Network Jack?
There are two main reasons why the
3Com NJ100 Network Jack doesn’t
connect to horizontal cabling via an
IDC punch-down. First, the product is
designed to reduce the cost of moves,
adds, or changes as a result of either
reconfiguring cubicles or moving to
another facility. The RJ-45 connection
allows you to easily install and, when
necessary, remove the network jack.
Second, BICSI’s wire test standards
prohibit you from testing the cabling
system through active components. If
you were to punch down the horizon-
tal cabling directly to the back of the
network jack, you would not be able
to test the cabling system according
to the BICSI standard. 3Com is work-
ing to develop a version of the
network jack that will have a punch-
down connection that does not
violate those wire test standards.
Can I daisy-chain multiple 3Com
NJ100 Network Jacks together?
If so, how many?
Although it is possible to daisy-chain
multiple 3Com NJ100 Network Jacks
together, we do not recommend it. A
Power-over-Ethernet solution will not
provide enough power to multiple
network jacks. With local power, you
will be constrained by switching-
topology considerations.
What types of pass-through
connectors do you support?
The adapter plates for the pass-
through connections support Panduit-
or Avaya-brand interface modules, RJ-
11 or RJ-45 connectors.
The 3Com NJ100 Network Jack
single-unit pack includes three
adapter plates—blank, Avaya, and
Panduit. The 20-unit packs do not
come with adapter plates, which
must be ordered separately.
Panduit interface modules:
Single category 3 CJ66BL (black)
module CJ66EI (ivory)
Single category 5 CJ588TBL (black)
module CJ588TEI (ivory)
Single category 5e CJ5E88TBL (black)
module CJ5E88TEI (ivory)
Avaya interface modules:
Single category 3 107321697 (black)
module 107321721 (ivory)
Single category 3/5e 108232695 (black)
module 108232737 (ivory)
Isn’t this more expensive than just
activating another port in my closet?
You cannot get the same functionality
by activating another port in your
closet that you can get from installing a
3Com NJ100 Network Jack. To get the
same number of active connections,
you would have to activate three new
ports in your closet, which is more
expensive than the cost of installing
a single network jack. In a new
installation, it is significantly more
expensive—up to 60 percent—to
deploy a traditional cabling system and
get the same number of active connec-
tions as deploying the network jack.
Competitive Positioning
Are there other products like this on
the market?
The 3Com NJ100 Network Jack is
unique in the networking world. As a
product, it is most often compared to
a desktop hub or switch. As a cabling
solution, it is compared to traditional,
passive-component cabling systems.
Isn’t this more expensive than just
adding a desktop hub or switch?
People ask why they shouldn’t just
buy a desktop hub or switch. A price
comparison between a 3Com NJ100
Network Jack and a desktop hub is
an apples-to-oranges comparison.

3COM®NJ100 NETWORK JACK
Customers
can maximize
existing cabling
infrastructures
and improve the
integration of their
networked devices.
The basic value of the network jack is
that it’s part of the cabling infrastruc-
ture rather than a desktop device. As
a result, it replaces cabling and uses
fewer switch ports—which can save
an organization a tremendous amount
of money. Our studies indicate that
by deploying the 3Com NJ100
Network Jack, you can save up to
$430 over a traditional installation
of four active ports.
Beyond cost savings, what are
the benefits of the 3Com NJ100
Network Jack?
In addition to cost savings, the 3Com
NJ100 Network Jack:
• Prevents the deployment of unau-
thorized desktop devices. Most IT
managers indicate they have prob-
lems with end users introducing
unauthorized desktop devices into
their networks. The 3Com NJ100
Network Jack provides a solution
that gives the end user the added
connectivity but puts control back
in the hands of the IT manager.
• Consolidates voice and data
connections. The 3Com NJ100
Network Jack is VoIP-compatible
in a converged voice/data environ-
ment via its switched ports or in
a separate voice network (VoIP or
legacy analog) via its pass-through
ports. What’s more, it connects all
those functions within a 3" x 5"
space. Desktop hubs and switches
don’t offer this level of functional-
ity within the footprint of a
network jack.
• Minimizes potential disruption. By
making the added connectivity part
of the infrastructure, there is less
chance of the end user accidentally
disrupting the connection. These
disruptions typically prompt phone
calls to IT support. The 3Com NJ100
Network Jack significantly reduces
the costs associated with those calls.
This is especially true in a Power-
over-Ethernet environment.
• Increases the integrity of the net-
work. From a data perspective, this
point is more relevant to desktop
hubs because it reduces the poten-
tial for end users to create loopback
errors. From a power perspective, a
Power-over-Ethernet solution virtu-
ally eliminates the possibility of
power disruption, increasing the
overall integrity of the network.
• Reduces possibility of theft. Free-
standing desktop hubs and switches
are more likely to “grow legs and
walk away” than a 3Com NJ100
Network Jack that is screwed
into the wall.
• Cleans up the desktop area. The
3Com NJ100 Network Jack allows
you to reduce the number of cables
exposed on the desktop.
Sales & Marketing
Who are your customers?
Anyone in a networked environment
who needs to connect more devices
than their number of existing active
connections should consider the 3Com
NJ100 Network Jack. A customer that
deploys network jacks in a new instal-
lation receives the maximum amount of
savings in their network infrastructure
costs. Customers that install network
jacks in their existing installations,
maximize their existing cabling infra-
structure without incurring the high
cost of pulling additional cable.
Customers with limited or fixed IT
budgets can expand connectivity
with the network jacks and free up
resources for other equipment.
What are some specific applications?
Here are a few examples of organiza-
tions and locations that can benefit by
installing 3Com NJ100 Network Jacks:
Education
• Training rooms
• Faculty or administrative offices
• Computer labs
• Dorm rooms
• Libraries
• Group study areas
6

3COM®NJ100 NETWORK JACK
3Com Corporation, Corporate Headquarters, 5400 Bayfront Plaza, P.O. Box 58145, Santa Clara, CA 95052-8145
To learn more about 3Com solutions, visit www.3com.com. 3Com is publicly traded on Nasdaq under the symbol COMS.
Copyright © 2002 3Com Corporation. All rights reserved. 3Com and NBX are registered trademarks and the 3Com logo
is a trademark of 3Com Corporation. All other company and product names may be trademarks of their respective
companies. While every effort is made to ensure the information given is accurate, 3Com does not accept liability for
any errors or mistakes which may arise. All specifications are subject to change without notice.
103020-001 04/02
Government
• Federal headquarters
• State offices
• Local offices
Enterprise
• Cubicles
• Conference rooms
• Public areas, such as network
printer rooms
• Work areas for consultants or
temporary workers
• Laboratories
Other
• Hard-to-wire locations, such as
older buildings with asbestos
• Historical buildings
• Tradeshows or event venues
Does the 3Com NJ100 Network Jack
ship with a power supply?
No. There are several different solutions
for powering the 3Com NJ100 Network
Jack. Rather than burdening customers
with the cost of a power solution they
can’t use, we offer a variety of options
so they can choose the power solution
to best fit their needs.
Pricing
Do you offer a discount for
multi-packs?
Yes. The current list price for a single-
unit pack is $140. The current list price
for a 20-pack is $2,600 or $130 per unit.
Where can I buy a 3Com NJ100
Network Jack?
If you have an account with Graybar
Electric Company, Inc., you can pur-
chase directly from them. You can also
purchase 3Com NJ100 Network Jacks
through your local cabling contractor
or value-added reseller. Finally, you can
purchase online at www.3com.com.
Is this available outside of the
United States?
Currently, the 3Com NJ100 Network
Jack is only available in the United
States. We are working to offer it in
other countries as soon as possible.
Warranty Information
When I wire a building, I expect that
cabling infrastructure to last at least 15
years. Does the 3Com NJ100 Network
Jack have a comparable warranty?
The 3Com NJ100 Network Jack has
a Lifetime Limited warranty on hard-
ware repair or replacement. “Lifetime
Limited” means that it is covered
for as long as the customer owns the
product or 5 years after the product is
discontinued, whichever occurs first.
Does the warranty include technical
support?
Phone-based technical support is
available within the U.S. for 90 days
through our toll-free number, 1-800-
527-8677.
We offer around-the-clock, web-based
support at http://support.3com.com,
including product support, service
and warranty information, training,
and software downloads. Also available
through our support page is the 3Com
Knowledgebase. This interactive tool
provides technical product informa-
tion from top 3Com engineers around
the globe.
For additional product information,
such as technical tips, product data
sheets, technology white papers, fre-
quently asked questions (FAQs), and
more, visit www.3com.com.
Are there any 3Com Maintenance
Services available for the 3Com
NJ100 Network Jack?
No maintenance services apply to
this product.
The 3Com®NJ100
Network Jack is
covered by our
Lifetime Limited
warranty.