19
CHAPTER 4: Operation
4.1 LED Indicators
Power On (PWR) LED:
Shines GREEN to show functional DC power.
Link Status (LINK) LEDs:
Stackable MiniHubs have a LINK LED for each
port, which shines GREEN when the MiniHub detects that a 10BASE-T
segment is properly connected to that port. Each LINK LED will turn OFF
independently if either end of the segment’s cable comes loose or if the
MiniHub or the device at the other end loses power.
Receive Packets (RX) LEDs:
The RX LEDs, one for each RJ-45 port, flicker
GREEN to show that data packets are being received from the segment
connected to that port. These LEDs provide reassurance of normal network
activity and help you diagnose abnormal activity.
4.2 Operating Features
Partitioning and Reconnection:
Stackable MiniHubs will automatically
partition any port where 32 consecutive collisions occur or after 6.5 ms of
continuous transmissions. Network integrity is checked every 800 ms, and the
segment is reconnected after one 512-bit packet is transmitted without an
error.
Preamble Regeneration:
As per Ethernet standards, the Stackable MiniHubs
add bits to the preambles of output packets so that each output packet
contains a minimum 64-bit preamble.
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:
The Stackable MiniHubs will automatically add bits to a
received data packet of less than 96 bits (a “fragment”) so that the size of the
packet sent on toward its destination is at least 96 bits.
4. Operation
