Stackable Personal Hubs
Installation and User Guide (04/01)
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Preamble Regeneration
: Stackable Personal Hubs add preamble bits so that
output packets contain a minimum 64-bit preamble per the Ethernet standard.
Collisions:
When carrier is detected simultaneously on multiple ports, a jam
pattern is generated on each port to create a collision condition. When a
collision signal from one port is detected, it generates a jam pattern to other
ports.
Fragment Extension:
Stackable Personal Hubs will automatically add bits to a
received data packet of less than 96 bits (a "fragment") so that the minimum
output packet to the other port is 96 bits long.
4.2
Using the Up-Link switch
Port 8 of the ST80 is equipped with an up-link switch to allow
connection to another hub or concentrator without a special crossover cable.
When set to the “=” position, port 8 is set up as a user port. When the switch is
in the “X” position, port 8 operates as an up-link port. To ensure that the up-
link switch is in the proper position, observe port 8’s LINK/TX LED. If this
LED is illuminated or flickering, the switch is properly set. If it is off, try the
other switch position. If neither position seems to work, check the 10BASE-T
cable and the connected device for proper installation. For more information on
the up-link switch, see Sections 3.8 and 3.10, “Switchable Up-Link Option” and
“
Cascading the ST80 Personal Hub with the Up-Link port
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4.3
Using the BNC Internal Termination Switch (Model ST80-B only)
Model ST80-B is equipped with a rear-mounted BNC connector with an
internal termination switch. This switch allows connection to 10BASE2 cable without
use of an external “T” type terminator. When set to the left position, external termination
is required. When the switch is in the right position, the connector is internally
terminated. For more details on the internal termination switch, see Section 3.6, “BNC
Connection”.
