Black Box LZ1500A-R3, Руководство пользователя

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UTP AND THIN ETHERNET REPEATERS
5. Monitoring and Troubleshooting
Solving network problems is easy once you learn a few basics. If you find
that the information in this chapter does not address a problem you are
having with your network, call Technical Support. Besides software issues,
the most common network problems are cable faults, accounting for over
75% of all network hardware problems. Always suspect the cabling, and
always suspect the connections to the cabling first—connectors unplugged,
wires not making good contact in the connectors, punch-down block
connections faulty, etc.
5.1 Monitoring the UTP Repeater LEDs
1. The LEDs near the ports of the LZ150xA series repeaters show
whether the system power is on and the ports are properly connected.
If no LEDs are on, the system is not powered. When a 10BASE2 port is
properly connected and the power is on, the red LED is on
continuously. When two repeater channels are connected together,
one will turn on its red LED, the other its green. There are three fault
conditions the repeaters cannot distinguish from a proper connection:
• When the phone wire polarity is reversed in a link, both Repeater ports
will turn on the same color LED. The only effect is that the crossed
link doesn’t function. The rest of the network will continue to operate,
but messages that must traverse the crossed link won’t be received.
• A short in a cable that is more than 100 feet from a repeater port will
not be detected, and that port will have its red LED on; depending on
how far the short is from the other repeater, that repeater’s port may
have its LED either lit red or alternating. The rest of the network will
continue to operate, but messages that must traverse the shorted link
won’t be received.
• There are too many 10BASE2 terminations. The network must have
one (only) terminator at the far end. Some repeaters and network
interface cards contain an internal 50 ohm terminator that is
connected to the 10BASE2 leg by means of an on-board jumper. If this
terminator is in place and there is a second external terminator on the
coax leg (for a total of 3), the repeater will not allow the connection to
become active. Make sure that only one terminator is on the coax and
that it is at the far end of the segment. Disable any terminators in the
middle of the segment, leaving only one at the far end.
2. When a port’s LEDs alternate between red and green, the port is not
properly connected. The LEDs on a port alternate when:
• There is nothing connected to the jack.