3COM 3C16702A (01) PDF MANUAL

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.

A single OfficeConnect hub allows you to create a small network with up to sixteen workstations.

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.

The front panel LEDs provide the following indications:

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.

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 or off. It is yellow if the port has partitioned.

Network Utilization LEDs (green/yellow/orange): Indicates how much your network is being used.

The rear panel components have the following functions:

Power Adapter socket: Only use the power adapter that is supplied with this OfficeConnect hub. Do not use any other adapter.

Coaxial port: Can be used to connect your hub to other OfficeConnect hubs and equipment with 10BASE-2 (Coaxial) cabling.

Uplink/Normal switch: Affects the operation of port 16. If you are connecting a hub to the port, set to Uplink (in), otherwise set to Normal (out).

Sixteen 10BASE-T RJ-45 ports: Use suitable TP cable with RJ-45 connectors. You can connect the OfficeConnect hub to any workstation or OfficeConnect hub that has a 10BASE-T port.

Your OfficeConnect hub comes with:

One power adapter for use with the OfficeConnect hub.

A Product Registration card for you to fill out and return.

Four rubber feet.

A stacking clip.

Two unit labels and eight cable ties.

An OfficeConnect Network Assistant CD-ROM.

To connect workstations or other equipment to your hub, you need:

10BASE-T connections for all your equipment. 3Com produce a range of easy to install network adapters, which provide your workstations with 10BASE-T connections.

An operating system (for example, Netware or Windows 95/98) with network support configured, running on your workstations.

One ‘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).

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).

If you want to connect additional hubs using 10BASE-T, you need:

One ‘Straight-through’ 10BASE-T cable for each additional hub.

The four self-adhesive rubber feet prevent your hub from moving around on your desk. Only stick the feet to the marked areas at each corner of the underside of your hub if you intend to place the unit directly on top of the desk. Do not fix the feet if you are going to use the clip.

You can stack up to a maximum of four units. Smaller units must be stacked above larger units.

To fit the clip:

1. Place your unit on a flat surface.

2. Fit the clip across the top of the unit, ensuring that the longer sections of the fastening pieces are pointing downwards.

3. Align the fastening pieces over the slots found on each side of the unit.

4. Push the clip down gently to secure it, ensuring the fastening pieces snap into the slots on the unit.

To fit another unit:

1. Rest the second unit on top of the clip and align it with the front of the unit below.

2. Press down gently on the unit to secure it onto the clip, ensuring the fastening pieces fit into the slots on the unit below.

To remove the clip:

1. Remove the top unit together with the clip. If you hook a finger around one of 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.

2. Push the clip in the center, so it bends towards the base of the unit, and then separate once the clip is loose.

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.

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. 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.

Only wall mount single units, do not wall mount stacked units.

Read the ‘Important Safety Information’ section before you start.

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.

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).

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.

Do not connect the same two hubs together using both 10BASE-T and 10BASE-2 (Coaxial). This causes a network loop.

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. 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.

For simplicity, we recommend the following method:

1. Starting from the bottom, connect port 16 of the lower hub to port 15 of the hub immediately above. Repeat for each hub.

2. Set 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).

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.

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.

Perform these actions first:

Ensure all equipment is powered on.

Power each unit off, wait about 5 seconds and then power them on.

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.

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.

Check your hub connections; follow the information given in the “Connecting OfficeConnect Hubs Together” section. 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).

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.

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.

A Network 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.

A Local 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.

A Network 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.

A segment 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.

The dimensions and operating conditions for the OfficeConnect hub are:

Power requirement: 18 VA, 61 BThU/hr

Operating temperature: 0 to 40°C (32 to 105°F)

Humidity: 0 to 90% (non-condensing)

Weight: 960 g (2.1 lb)

Dimensions: 228 mm (9.12 in.) length

Height: 54.6 mm (2.1 in.)

Depth: 185.4 mm (7.3 in.) + 15.2 mm (0.6 in.) for coaxial port