3Com OfficeConnect User manual

OfficeConnect
®
Ethernet Hub 16C (3C16702A)
User Guide

3Com Corporation ■5400 Bayfront Plaza
■Santa Clara, California ■95052-8145
Copyright © 2002, 3Com Technologies. All rights reserved.
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copy, please contact 3Com and a copy will be provided to you.
UNITED STATES GOVERNMENT LEGEND
If you are a United States government agency, then this documentation and the
software described herein are provided to you subject to the following:
All technical data and computer software are commercial in nature and
developed solely at private expense. Software is delivered as “Commercial
Computer Software” as defined in DFARS 252.227-7014 (June 1995) or as a
“commercial item” as defined in FAR 2.101(a) and as such is provided with only
such rights as are provided in 3Com’s standard commercial license for the
Software. Technical data is provided with limited rights only as provided in DFAR
252.227-7015 (Nov 1995) or FAR 52.227-14 (June 1987), whichever is
applicable. You agree not to remove or deface any portion of any legend
provided on any licensed program or documentation contained in, or delivered to
you in conjunction with, this User Guide.
Unless otherwise indicated, 3Com registered trademarks are registered in the
United States and may or may not be registered in other countries.
3Com and OfficeConnect are registered trademarks of 3Com Corporation. The
3Com logo is a trademark of 3Com Corporation
Microsoft, MS-DOS, Windows, and Windows NT are registered trademarks of
Microsoft Corporation. Novell and NetWare are registered trademarks of
Novell, Inc.
All other company and product names may be trademarks of the respective
companies with which they are associated.
Please e-mail any comments about this document to 3Com at:
[e-mail]. Please include the document title
(OfficeConnect Ethernet Hub 16C), part number (DUA1670-2AAA04) and, if
appropriate, the page number.

3
Introduction 5
Creating Your Network 6
Ethernet Hub 16C—Front 6
Ethernet Hub 16C—Rear 7
Before You Start 8
Product Registration 8
Workstation Connections 8
Hub Connections 8
Stacking the Units together 9
The Rubber Feet 9
The Stacking Clip 9
Positioning Your OfficeConnect Hub 10
Securing the OfficeConnect Hub 10
Connecting Workstations and Other Equipment to Your Hub 11
Connecting OfficeConnect Hubs Together 11
Connecting Hubs Using 10BASE-2 (Coaxial) 12
Connecting Hubs Using 10BASE-T 13
Checking Hub Connections 13
Spot Checks 13
Problem Solving 14
Networking Terminology 16
Dimensions and Standards 17
Dimensions and Operating Conditions 17
Standards 17
Environmental Statements 18
End Of Life Statement 18
Regulated Materials Statement 18
Environmental Statement about the Documentation 18
Environmental Statement about the Product Packaging 18
Regulatory Notices 19

4

5
INTRODUCTION
Welcome to the world of networking with 3Com®. In the
modern business environment, communication and sharing
information is crucial. Computer networks have proved to
be one of the fastest modes of communication but, until
recently, only large businesses could afford the networking
advantage. The OfficeConnect®product range from 3Com
has changed this, bringing networks to the small office.
The OfficeConnect Ethernet Hub 16C is ideal for creating
small networks. It is compact and attractively designed for
desktop use. This product forms part of the OfficeConnect
range which neatly stack together with the OfficeConnect
stacking clip.
When referring to the OfficeConnect Ethernet Hub 16C, this
guide uses the term ‘OfficeConnect hub’.
A single OfficeConnect hub allows you to create a small
network with up to sixteen workstations, as shown in
Figure 1.
Figure 1 Small Network With OfficeConnect Hub And Optional
Print Server
If you need to connect more workstations, simply use the
stacking clip to connect another OfficeConnect hub to form
a stack (each hub is a single repeater).
The OfficeConnect Ethernet Hub 16C has sixteen 10BASE-T
ports and one 10BASE-2 (Coaxial) connector.
HP JetDirect
OfficeConnect
print server
OfficeConnect hub

6
CREATING Y
OUR NETWORK
Ethernet Hub 16C—Front
Alert LED
orange
Alerts you to
excessive network
use or an isolated
(partitioned)
10BASE-T port.
Power LED
green
Indicates that the
power supply to
the hub is present.
Network Utilization LEDs
green/yellow/orange
Indicates how much your
network is being used.
Collision LED
yellow
Flashes each time
a collision is
detected on the
network.
Collisions are part
of normal network
operation.
Port Status LEDs
green/yellow
Indicates the status of each port. If the
LED is green, the link between the port
and the next piece of network equipment
is OK.
If nothing is connected, the LED is off.
If yellow, the port has partitioned due to a
fault on that segment.
The Coaxial port LED can only be yellow
Power
Port Status
Green = OK, Yellow = Partitioned
910 11 12
Collision
OfficeConnect Ethernet Hub 16C
Network Utilization
3C16702A
1% 2% 3% 6% 12% 25% 50% 80%
Alert 13 14 15 16 COAX
12345678

7
Ethernet Hub 16C—Rear

8
Before You Start
Your OfficeConnect hub comes with:
■One power adapter for use with the OfficeConnect hub.
■Four rubber feet.
■A stacking clip.
■One Support and Safety Information Sheet
■One Warranty Flyer
The extra parts mentioned in the next section are not
supplied with the hub.
Product Registration
You can now register your OfficeConnect hub on the 3Com
web site and receive up-to-date information on your
product.
http://support.3com.com/registration/frontpg.pl
Workstation Connections
To connect workstations or other equipment to your hub,
you need:
110BASE-T connections for all
your equipment. 3Com
produce a range of easy to
install network adapters, which
provide your workstations with
10BASE-T connections.
2An operating system (for example, Netware or Windows
95/98) with network support configured, running on
your workstations.
3One ‘Straight-through’ 10BASE-T cable for every
workstation or piece of equipment. A ‘Straight-through’
cable is one where the pins of one connector are
connected to the same pins of the other connector.
10BASE-T cables can be shielded or unshielded. We
recommend you use shielded. The maximum length you
can use is 100m (328ft).
In order to comply with the 10BASE-T standard, ports
designed for workstation connections have been marked
with the graphical symbol ‘x’. This denotes a crossover in
the port’s internal wiring, for example 1x, 2x, 3x...
Hub Connections
If you have additional hubs you want to connect using
10BASE-2 (Coaxial), you need:
■One 10BASE-2 50 Ohm cable for each additional hub.
The minimum cable length you can use is 0.5m (1.6 ft).
The maximum segment length you can have is 185m
(607ft).
■One 10BASE-2 ‘Y’ piece for each hub. You can use ‘T’
pieces but ‘Y’ pieces provide optimum clearance of the
other ports.
■Two 10BASE-2 50 Ohm terminators (end pieces).
3
2
1

9
If you want to connect additional hubs using 10BASE-T, you
need:
■One ‘Straight-through’ 10BASE-T cable for each
additional hub.
Stacking the Units together
The Rubber Feet
The four self-adhesive rubber feet prevent your hub from
moving around on your desk. Stick the feet to the marked
areas at each corner of the underside of your hub. Do not
fix the feet if you are going to use the clip.
The Stacking Clip
The stacking clip allows you to stack your OfficeConnect
units together neatly and securely.
CAUTION: You can stack up to a maximum of four
units. Smaller units must be stacked on top.
To fit the clip:
1Place your unit on a flat surface.
2Fit the clip across the top of the unit, as shown in
Figure 2 (picture 1), ensuring that the longer sections of
the fastening pieces are pointing downwards.
3Align the fastening pieces over the slots found on each
side of the unit.
4Push the clip down gently to secure it, ensuring the
fastening pieces snap into the slots on the unit.
To fit another unit:
1Rest the second unit on top of the clip and align it with
the front of the unit below.
2Press down gently on the unit to secure it onto the clip,
ensuring the fastening pieces fit into the slots on the unit
below, as shown in Figure 2 (picture 2).
Figure 2 Stacking Your Units Together
To remove the clip:
1Remove the top unit together with the clip. If you hook
a finger around one of the the fastening pieces and then
pull it gently from out of the slot, the clip should come
away with the upper unit attached to it.
2Push the clip in the center, so it bends towards the base
of the unit, and then separate once the clip is loose.
1
Fastening
Piece
2
Fastening
Piece

10
Positioning Your OfficeConnect Hub
When installing your OfficeConnect hub, ensure:
■It is out of direct sunlight and away from sources of
heat.
■Cabling is away from power lines, fluorescent lighting
fixtures, and sources of electrical noise such as radios,
transmitters and broadband amplifiers.
■Water or moisture cannot enter the case of the unit.
■Air flow around the unit and through the vents in the
side of the case is not restricted. We recommend you
provide a minimum of 25.4 mm (1in.) clearance.
Securing the OfficeConnect Hub
There are two slots on the underside of the OfficeConnect
hub which can be used for wall mounting. It is
recommended that you mount the hubs with the LEDs
facing upwards to prevent dust entering the cooling vents.
When wall mounting the unit, ensure that it is within
reach of the power outlet.
You need two suitable screws. Ensure that the wall you are
going to use is smooth, flat, dry and sturdy. Make two
screw holes which are 142mm (5.6in.) apart. Use the guide
at the back of this manual to mark the position of the
holes. Fix the screws into the wall, leaving their heads 3mm
(0.12in.) clear of the wall surface.
Remove any connections to the unit and locate it over the
screw heads. When in line, gently push the unit on to the
wall and move it downwards to secure. When making
connections, be careful not to push the unit up and off the
wall.
CAUTION: Only wall mount single units, do not wall
mount stacked units.
Also available from 3Com, is the OfficeConnect Mounting
Unit (part number 3C16765). This allows you to firmly
secure a stack of OfficeConnect devices to the desktop or
onto a shelf in a rack.

11
Connecting Workstations and Other
Equipment to Your Hub
WARNING: Please read the ‘Important Safety
Information’ sheet before you start.
WARNHINWEIS: Bitte lesen Sie den Abschnitt
‘Wichtige Sicherheitsinformationen’ sorgfältig durch,
bevor Sie das Gerät einschalten.
AVERTISSEMENT: Veuillez lire attentivement la
section “Consignes importantes de sécurité” avant de
mettre en route.
CAUTION: Do not power the hub off and on quickly.
Wait about five seconds between power cycles.
Connecting workstations and other equipment to your hub
is easy. Connect them using 10BASE-T cables to any of the
hub’s sixteen 10BASE-T RJ-45 ports.
10BASE-T cables are very easy to use. To connect a
10BASE-T cable, simply slot the connector into the relevant
RJ-45 port. When the connector is fully in, its latch locks it
into place. To disconnect the cable, push the connector’s
latch in and remove it.
The hub detects all port connections, so you can start using
your network immediately. When you need more ports,
simply add more OfficeConnect hubs.
If you are using port 16 to connect to a workstation,
ensure the Uplink/Normal switch is set to Normal
(out).
Connecting OfficeConnect Hubs Together
You can increase the number of workstations that can
connect to your network by adding more OfficeConnect
hubs. You can use either 10BASE-T or 10BASE-2 (Coaxial) to
do this:
■With 10BASE-2 (Coaxial) you can connect up to 30 hubs
on a single segment, leaving all of the RJ-45 ports free.
■With 10BASE-T you can connect up to four hubs in
series.
CAUTION: Do not connect the same two hubs
together using both 10BASE-T and 10BASE-2
(Coaxial). This causes a network loop.

12
Connecting Hubs Using 10BASE-2 (Coaxial)
When using 10BASE-2 (Coaxial) cable, it is important
that both ends of the segment are properly
terminated with 50 Ohm terminators (end pieces).
Only use 50 Ohm 10BASE-2 (Coaxial) cables and use
a ‘Y’ piece for each hub. You can use ‘T’ pieces but
‘Y’ pieces provide optimum clearance of the other
ports.
Connect a 10BASE-2 ‘Y’ piece to each of your hubs.
Daisy-chain each ‘Y’ piece with 10BASE-2 (Coaxial) cable to
form a single segment (as shown in Figure 3). Remember to
terminate the two free ends of the segment by fitting
terminators (end pieces).
To disconnect a 10BASE-2 (Coaxial) cable, twist each
connector counter-clockwise to unlock it, and remove it.
Figure 3 Correct Hub Connections Using 10BASE-2 (Coaxial)

13
Connecting Hubs Using 10BASE-T
You can connect hubs together with 10BASE-T in a number
of ways, but for simplicity we recommend the following
method:
1Starting from the bottom, connect port 16 of the lower
hub to port 15 of the hub immediately above. Repeat for
each hub (as shown in Figure 4).
2Set all Uplink/Normal switches to Uplink (in) except for
the top hub (the one with port 16 not connected to
another hub). This unused port can be connected to a
workstation provided that the Uplink/Normal switch is set
to Normal (out).
Checking Hub Connections
When you have connected your hubs, power them on. The
Port Status LEDs for the ports you have used on the hubs
should be green. If they are not, check your connections
and the settings of the Uplink/Normal switches.
Spot Checks
At frequent intervals, visually check that:
■The Alert LED is off — this is the best way to find out if
there are problems with your network.
■Case vents are not obstructed.
■Cabling is secure and not pulled taut.
Figure 4 Correct Hub Connections Using 10BASE-T
10BASE-T cable
with RJ-45 connectors.
Maximum length is
100m (328ft)
Switch set to
Uplink (in)
Switch set to
Normal (out)
10BASE-T
16
8X
POWER
COAX
10BASE-T
16
8X
POWER
COAX
10BASE-T
16
8X
POWER
COAX
Uplink/Normal
Uplink/Normal
Uplink/Normal

14
PROBLEM SOLVING
The OfficeConnect hub has been designed to aid you when
detecting and solving possible problems with your network.
These problems are rarely serious; the cause is usually a
disconnected or damaged cable, or incorrect configuration.
If this section does not solve your problem, contact your
supplier for information on what to do next.
Perform these actions first:
■Ensure all equipment is powered on.
■Power each unit off, wait about 5 seconds and then
power them on.
Check the following symptoms and solutions:
Power LED not lit. Check your power adapter connection.
If there is still no power, you may have a faulty power
adapter which needs replacing with another OfficeConnect
power adapter. Do not use any other power adapter
with the hub.
Port Status LED yellow for a 10BASE-T port. It is likely
that there is a loop in your network which has caused this
port to partition. Examine your connections and remove the
loop. Each piece of equipment needs only one connection
to your OfficeConnect hub. The LED will change from
yellow to green, on receiving a valid packet on the port.
Link between two OfficeConnect hubs not working.
Check your hub connections; follow the information given in
the “Connecting OfficeConnect Hubs Together” on page 11.
With 10BASE-T it is likely that an Uplink/Normal switch is
incorrectly set. With 10BASE-2 (Coaxial) it is likely a terminator
(end piece) is not properly fitted; this would cause the Coaxial
Port Status LED to light yellow (partition).
Alert LED continuously lit. There is either continual
excessive use of your network (over 80%) or, more likely, a
10BASE-T port has partitioned due to a loop in your
network (in which case the corresponding Port Status LED
will be yellow). Examine your connections and remove the
loop. Each piece of equipment needs only one connection
to your OfficeConnect hub.
Port Status LED not lit for a port that has a
connection. There is a problem with this connection. Check
that you are using a ‘Straight-through’ cable which is
properly connected at both ends, and is not damaged. If the
cable is connected to port 16, ensure that the
Uplink/Normal switch is set to Normal (out). Also check that
the equipment being connected to the hub is powered on,
operating correctly and contains the correct type of
connection.

15
Refer to Figure 5 below to compare the wiring of a
straight-through and a crossover cable.
Figure 5 Straight-through Cable/Crossover Cable
1
Normal
port Pin Pin Uplink port
Rx+
Rx-
Tx+
Tx-
Tx+
Tx-
Rx+
Rx-
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
Normal
port Pin Pin Normal port
Rx+
Rx-
Tx+
Tx-
Rx+
Rx-
Tx+
Tx-
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8

16
NETWORKING T
ERMINOLOGY
ANetwork is a collection of workstations (for example,
IBM-compatible PCs) and other equipment (for example,
printers), connected for the purpose of exchanging
information or sharing resources. Networks vary in size,
some are within a single room, others span continents.
ALocal Area Network (LAN) is a network, usually in an
office, that spans no more than a single site.
Ethernet is a type of LAN, referring to the technology used
to pass information around the network. It operates at
10Mbps (megabits per second).
10BASE-T is the name given to the Ethernet protocol that
runs over Twisted Pair (TP) cable at 10Mbps. The
OfficeConnect hub uses RJ-45 type connectors for
connecting your TP network
10BASE-2 is the name given to the Ethernet protocol that
runs over Coaxial cable.
ANetwork Loop occurs when two pieces of network
equipment are connected by more than one path. Your hub
detects this and partitions (isolates) one of its ports to
break the loop.
Asegment is the length of cable connected to a port,
whether this cable is 10BASE-T, 10BASE-2 (Coaxial), or
another type. When you daisy-chain equipment together
with 10BASE-2 (Coaxial) cable, via single speed hubs, the
entire cable forms a single segment.
Packets are the units of information your workstations and
other equipment send to each other over the network.
Collisions are a part of normal Ethernet operation and
occur if two or more devices (pieces of network equipment)
attempt to transmit at the same time. A sudden sustained
increase in the number of collisions can indicate a problem
with a device, particularly if it is not accompanied by a
general increase in traffic. On coaxial segments an increase
in collisions can also indicate faulty cabling.

17
DIMENSIONS AND STANDARDS
Dimensions and Operating Conditions Standards
Functional: ISO 8802/3
IEEE 802.3
Safety: UL 1950
EN 60950
CSA 22.2 #950
IEC 60950
EMC: EN 55022 Class B†
EN 55024
FCC Part 15 Class B†*
ICES-003 Class B
VCCI Class B†
CNS 13438 Class A
Environmental: EN 60068 (IEC 68) Various parts
†Category 3 or 5 screened or unscreened cables can be
used to comply with the Class B requirements.
*Refer to “Regulatory Notices” on page 19 for conditions of
operation.
960 g (2.1 lb)
228 mm (9.12 in.)
54.6 mm
(2.1 in.)
185.4 mm (7.3 in.)
+ 15.2 mm (0.6 in.)
for coaxial port
0 to 40°C (32 to 105°F)
operating
temperature
6.73 W
23.00 BThU/hr
power requirement
0 to 90%
(non-condensing)
humidity

18
ENVIRONMENTAL STATEMENTS
It is the policy of 3Com Corporation to be
environmentally-friendly in all operations. To uphold our
policy, we are committed to:
■Establishing environmental performance standards that
comply with national legislation and regulations.
■Conserving energy, materials and natural resources in all
operations.
■Reducing the waste generated by all operations.
■Ensuring that all waste conforms to recognized
environmental standards.
■Maximizing the recyclable and reusable content of all
products.
■Ensuring that all products can be recycled, reused and
disposed of safely.
■Ensuring that all products are labelled according to
recognized environmental standards.
■Improving our environmental record on a continual basis.
End Of Life Statement
3Com processes allow for the recovery, reclamation and safe
disposal of all end-of-life electronic components.
Regulated Materials Statement
3Com products do not contain any hazardous or
ozone-depleting material.
Environmental Statement about the Documentation
The documentation for this product is printed on paper that
comes from sustainable, managed forests; it is fully
biodegradable and recyclable, and is completely
chlorine-free. The varnish is environmentally-friendly, and the
inks are vegetable-based with a low heavy-metal content.
Environmental Statement about the Product
Packaging
The packaging for this product is fully recyclable. It has a
recycled (post consumer) waste content of at least 40% by
weight, and no heavy-metal content.

19
REGULATORY NOTICES
FCC STATEMENT
This equipment has been tested and found to comply with the limits for a Class B
digital device, pursuant to Part 15 of the FCC Rules, and the Canadian
Department of Communications Equipment Standards entitled, “Digital
Apparatus,” ICES-003. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment
generates, uses and can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur
in a particular installation.
If this equipment causes interference to radio or television reception, which can
be determined by turning the equipment off and on, try to correct the
interference by using one or more of the following measures:
■Reorient the receiving antenna.
■Relocate the equipment with respect to the receiver.
■Move the equipment away from the receiver.
■Plug the equipment into a different outlet so that equipment and receiver are
on different branch circuits.
■Consult the dealer or an experienced radio/television technician for help.
CSA STATEMENT
This Class B digital apparatus meets all requirements of the Canadian
interference-Causing Equipment Regulations.
Cet appareil numérique de la classe B respecte toutes les exigences du Règlement
sur le matériel brouilleur du Canada.
CE STATEMENT (EUROPE)
This product complies with the European Low Voltage Directive 73/23/EEC and
EMC Directive 89/336/EEC as amended by European Directive 93/68/EEC.
VCCI STATEMENT
BSMI STATEMENT
INFORMATION T
OTHE USER
The user may find the following booklet prepared by the Federal Communications
Commission helpful:
How to Identify and Resolve Radio-TV Interference Problems
This booklet is available from the U.S. Government Printing Office, Washington,
DC 20402, Stock No. 004-000-00345-4.
In order to meet FCC emissions limits, this equipment must be used only with
cables which comply with IEEE 802.3.

20
Wall mounting screw hole guide
142mm (5.6in.)