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2.0 Installation
This chapter provides instructions for installing the RS dual-speed hubs.
2.1 Locating the dual-speed hubs
The location of a Dual-speed hub is dependent on the physical layout of the network.
Typically the hub is placed where combinations of 10Mbps and 100Mbps network devices
need to be connected to communicate with each other. The compact size of the unit allows
it to be conveniently placed in an office or lab area and can be either shelf or wall mount-
ed using the wall-mounting brackets supplied. The width of two units will fit in a 19” rack
when they are side-by-side.
Locate a mains socket that is within six feet (2 metres) of the selected location. The rugged
metal case of the hub will normally protect it from accidental damage in a lab or workplace
environment. Maintain an open view of the front to visually monitor the status LEDs. Keep
an open area around the unit so that cooling can occur from the fan in the bottom-rear
while the unit is in operation.
2.1.1 Table-top or shelf mounting
The
RS
dual-speed hub can be easily mounted on a table-top or any suitable horizontal
surface, and has four rubber feet to provide stability without scratching finished surfaces.
When stacked, the rubber feet also provide separation between units for the exhaust of the
rear cooling fan.
2.1.2 Wall (or vertical surface) mounting
Each dual-speed hub is shipped with two metal mounting brackets (and screws) to allow
the unit to be mounted in most of the desired orientation or position. The brackets are
attached to the metal hub case using one of the metal screws for each bracket and attach-
ing to the hub through the round hole of the bracket. A user-supplied screw attaches the
bracket to the mounting surfaces. it is recommended that the brackets are attached to two
opposite corners of the unit. When properly attached, the brackets will extend slightly
below the base of the unit to allow clearance for the rubber feet and the cooling fan
exhaust.
2.2 Connecting Ethernet media
The dual-speed stackable hubs can be connected to the following two media types:
100BASE-TX and 10BASE-T. CAT 5 cables should be used when making 100BASE-TX
connections. When the ports are used as 10BASE-T ports, CAT 3 may be used. In either
case, the maximum distance for unshielded twisted pair cabling is 100 meters (3287ft).
Media
IEEE standard
Connector
Twisted pair (CAT 3)
10BASE-T
RJ-45
Twisted pair (CAT 5)
100BASE-TX
RJ-45
Note:
It is recommended that high quality CAT 5 cables (which work for both 10Mbps
and 100Mbps) be used whenever possible in order to provide flexibility in a
mixed-speed network, since dual-speed ports are auto-sensing for either 10 and
100Mbps.
2.2.1 Connecting twisted pair (RJ-45, CAT 3 or CAT 5, unshielded or shielded)
The following procedure describes how to connect a 10BASE-T or 100BASE-TX twisted
pair segment to the RJ-45 port. The procedure is the same for both unshielded and shield-
ed twisted pair cables.
1.
Using standard twisted pair media, insert either end of the cable with an RJ-45
plug
into the RJ-45 connector of the port.
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Example 3:
For additional expansion, the hubs can be stacked using additional DS8-A units. The addition-
al stacked ports are all auto-sensing dual-speed, and can be used at either 10Mbps or
100Mbps.
The stacking cables connect the units and carry the signals for both the 100Mbps and the
10Mbps domains. In a stack, all 10Mbps ports operate in a 10Mbps traffic domain while all
100Mbps ports operate on a separate 100Mbps traffic domain. When one DS8-B unit with a
bridge inside is present in a stack, its bridge will support all of the ports in the stack and
enable network traffic to move between the two stacked domains.
A stack operates as one dual-speed repeater. A dual-speed repeater is both a 10Mbps hub
and a 100Mbps hub at the same time. This means that the 10Mbps traffic domain obeys all of
the rules of 10Mbps shared Ethernet networks (hop counts, cable types, cable distances, etc.)
and can be treated as one 10Mbps repeater accordingly. The 100Mbps traffic domain obeys
all of the rules of 100Mbps Fast Ethernet shared networks (hop counts, PDVs, cable types,
cable distances, etc.) and can be treated as one 100Mbps repeater. Both traffic domains func-
tion within the same physical hub or stack of hubs.
When you are expanding an Ethernet or Fast Ethernet network, the dual-speed hubs are
ideally suited for connecting servers and stations that have (or may have in the future)
mixed speeds. Each traffic domain or segment has its own local traffic with the DS8-B per-
forming bridge-isolation of one domain from the other, filtering and selectively forward-
ing 10Mbps and 100Mbps packets between the two domains. This keeps the traffic
between the domains to a minimum and provides peak performance on both domains.
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Router
Figure 4
Figure 5
