Black Box LZ1500A-R3, Руководство пользователя

Страница: 34 / 39

31
UTP AND THIN ETHERNET REPEATERS
Distance Repeaters.
• Some repeaters and network interface cards contain an internal 50-
ohm terminator that is connected to the Thin Ethernet leg by means of
an on-board jumper. If this terminator is in place and there is a
second, external terminator and a coax connection 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.
• In networks with 10BASE5 (thick Ethernet) backbones, take care to
ensure that the MAU (Media Access Unit) feeding the Repeaters have
the SQE (Signal Quality Error) test disabled. If it is enabled, all
equipment on the UTP portion of the net will operate very slowly, but
the rest of the equipment will be unaffected.
• Do not use flat telephone cables for patch cables or any other network
connection for two reasons:
1. Some devices are quite sensitive to EMI and RFI noise. If you use flat
untwisted wire—even short patch cables— you may experience very
poor performance.
2. Flat telephone cables have their polarity reversed; any device on a leg
with the wrong polarity won’t communicate with the repeater. Replace
all flat cables with twisted ones.
• Be sure the protection devices you are using are compatible with high
speed data networks. For further information on precautions and
protection devices, refer to Chapter 3. If you have any other safety
concerns or questions, stop and call Technical Support for assistance.
• Trust and use the Repeater LEDs. They will prevent problems from
occurring and greatly reduce troubleshooting time and effort. If you
have read this chapter and still cannot solve a problem, please call
Technical Support.