Black Box Dual-Speed Stackable Hubs Installation and User Guide
7
2.3 Stacking
LH8000As
Up to four LH8000As can be stacked to operate as one 10/100 dual-speed repeater
with up to 32 dual-speed ports. Normally, one LH8000A-M hub per stack is needed to provide
a switched
interconnection between
the two separate
100Mbps and 10Mbps
traffic domains in the
stack. Additional
stacked units are
normally Model
LH8000A-C “add-on”
units, which cost less.
Figure 2.3 : LH8000As stacked. Cables connect between “Out” and “In” Ports
The LH8000A-M models with the bridge module inside look the same as the
LH8000A-C units (no bridge inside) from the outside. The “BR” LED on the front will light up
when power is applied to indicate that an LH8000A is a -M (bridge inside) model. (The “BR”
LED will be off if the unit is a Model LH8000A-C). The LH8000A-M models cannot be
stacked together, as their internal bridges would not be able to function properly when more
than one is present. Use LH8000A-M models un-stacked, or with only 1 Model LH8000A-M in
an LH8000A stack. See Section 2.7, Example 3.
When stacking LH8000As, please make sure to use only the shielded 9-inch long
stacking cable provided with each LH8000A-C unit. The cable length is designed to provide
proper operation of up to four LH8000A units in a stack, and longer cables or unshielded cables
are not permitted as they will not operate properly at 100Mbps speeds.
The 9-inch length is enough to provide for side-by-side stacking. This can be
convenient when locating the LH8000As in a rack, for example, as two LH8000As will fit side-
by-side on a tray in a standard 19” rack space.
When connecting LH8000As in a stack, use the stacking cable to connect the “Out”
stacking port from one LH8000A unit to the “In” stacking port of the other. Push in the cable
connectors until they snap in firmly. Also, leave space in the left-rear area for the exhaust of
the internal cooling fan in each LH8000A unit. See Figure 2.3 above.
OUT
IN
OUT
IN
OUT
IN
OUT
IN
FAN EXHAUST
