Black Box Mixed-Media Fiber Hubs
Installation and User Guide (4/99)
When a twisted-pair port is connected and LINK is present, the speed on that port that
has been sensed by the LH8050A Mixed-Media Fiber Hub will be indicated by the ‘S’ LED for
that port. The ‘S’ LED is steady ON when 100Mbps speed is sensed, and is steady OFF when
10 Mbps speed is in use. When the port is not connected, the ‘S’ LED on that port will be
blinking to indicate that it is trying to auto-negotiate. (See section 4.3 for the LED’s).
2.7
Stacking Mixed-Media LH8050A Fiber Hubs
The rear of the LH8050A Mixed-Media Fiber Hubs have an Inter-Repeater Bus (IRB)
connector on the left side. The IRB interconnects stacked units with a stacking cable, enabling
all stacked L LH8016A-C units to operate as a single dual-speed repeater. There are
two 25-pin IRB connectors on each unit: the bottom IRB connector which is used to daisy chain
the IRB to the stacked unit below (unused on bottom unit in an LH8050A stack); and the top
IRB connector which is used to daisy chain the IRB to the stacked unit above (unused on top
unit in an LH8050A stack). The IRB connectors for non-stacked units are unused.
When stacking LH8050A’s and LH8016-C’s, please make sure to use only the
shielded 9-inch long stacking cable provided with each “add-on” or “client” unit. The IRB
stacking cables supplied with each LH8016A-C or special LH8050A-C units are designed to
provide proper operation
of up to three dual-speed
hub units in a stack, and
longer or unshielded
cables are not permitted
as they will not operate
properly at 100Mb speeds.
Figure 2.7a A stack of one LH8050A and two LH8016A-C’s
15
The LH8050A Mixed-Media Fiber Hub can be stacked with LH8016A-C models,
too. (But not with LH8016A-B because of the “bridge-inside” conflict) Normally, one
LH8050A hub is needed to provide a switch between the 10 and 100Mbps domains.
With one base model LH8050A, up to two additional special LH8050A-C “add-on”
units or two LH8016A-C hub units can be stacked to operate as one 10/100 Dual-Speed
repeater with up to 48 dual-speed ports, with any mix of fiber and copper port types.
When connecting mixed-media LH8050A’s in a stack, use the stacking cable to
connect the “OUT” stacking port from one LH8050A unit to the “IN” stacking port of the
other. Push in the cable connectors until they seat in firmly. Also, leave space along the left-
side area for the exhaust of the internal cooling fan in each LH8050A unit.
100
PWR BRD
ACT
COL
1
R L S
R L S
R L S
R L S
R L
R L
R L
R L
R L
R L
R L
R L
R L
R L
R L
R L
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 X
LK/RX
PORT
100
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
PWR
BR
COL 10
COL 100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 X
LK/RX
PORT
100
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
PWR
BR
COL 10
COL 100
Black Box Rackmount Dual Speed Hub
Black Box Rackmount Dual Speed Hub
10 1 00
PWR BRD
ACT
COL
Black Box LH8050A
Mixed Media Fiber Hub
