Black Box Dual-Speed Stackable Hubs Installation and User Guide
6
2.2.1 Dual-Speed Hub Chassis
The LH8000A chassis houses one main PC board, a bridge module daughter- board
in the Model LH8000A-M, and an internal power supply unit. The front side of the chassis has
eight RJ-45 twisted-pair ports and one cascading (UP-LINK) switch for Port 8 on the right.
LEDs to indicate operating status are on the left front side. There are power (PWR)
and bridge-inside (BR)
indicators for the unit.
There are activity (ACT)
and collision (COL)
indicators for each of the
10Mbps and 100M b domains,
LH8000A Dual-Speed Hub
set unto a “square” arrangement, for visual indication of the operating status of each domain.
And there are link (LK), receive (RX) and speed (100) indicators for each port. (See Section
1.1 “Specifications” for a technical description of the LEDs). The unit has a cooling fan on the
bottom left corner which sends warm air out away from the unit to the rear. Stacking cables
connect in the rear (see Section 2.3 for stacking information).
The AC power cord connector, a universal recessed-male IEC type, is in the left
rear of the chassis. The internal power supply is auto-ranging for any AC power input of 115 -
230 vac, 50 - 60 Hz. (An internal DC power supply is optional).
2.2.2 10 / 100 Speed Auto-sensing
All eight RJ-45 twisted pair ports support auto-sensing for speed, independent of the
other ports. Speed-sensing is performed by the LH8000As electronics in accordance with the
standards of the IEEE 802.3u auto-negotiation standard. If the connected device or node
indicates that it is capable of 100Mbps speed, then operation on that port will be at 100Mbps .
If the connected device does not positively indicate that it is capable of 100Mbps speed, then
the operation on that LH8000A port will be at 10Mbps . Of course, the hubs’ auto-negotiation
technique is only for 10 / 100 speed, and does not provide for any full-duplex operation.
When a port is connected and LINK is present, the speed on that port that has been
sensed by the LH8000A hub will be indicated by the ‘100’ LED for that port. The ‘100’ LED is
ON when 100Mbps speed is sensed, and is OFF when 10Mbps speed is in use. When a port is
not connected, the ‘100’ LED corresponding to that port will be blinking to indicate that it is
trying to auto-negotiate. (See section 4.3 for operation of the LED’s).
1 2 3 4 5 6 7 8
COL
ACT
100 10
PWR
LK
RX
BR
100
UPLINK
1 2 3 4 5 6 7 8
BLACK BOX
Dual Speed Stackable Hub
(412) 746-5500
