CTC Union FRM220-NMC, Руководство пользователя

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Appendix A
108
The FRM-E1 and FRM-T1 fiber media converters' transmissions are transparent to clock and data. They are
designed to be placed in an existing E1 or T1 application as an extension over fiber. When connected by fiber pair,
the received analog signal of each device is used to generate the transmitted optical signal. Because of their
transparent nature, they can be applied where the transmissions are unframed or fractional without regard and with
minimal configuration (only need to configure the proper line code).
Figure A-? Transparent operation of FRM-E1 and FRM-T1
The FRM-E1/T1 media converter incorporates a Far End Fault feature which allows the converters on both
ends of a pair of fibers to be informed when there is a problem with one of the fibers. Without Far End Fault, it is
impossible for a fiber interface to detect a problem that affects only its Transmit fiber. When Far End Fault is
supported and enabled, a loss of receive signal (link) will cause the transmitter to generate a Far End Fault pattern
in order to inform the device at the far end of the fiber pair that a fault has occurred. When the local receiver again
detects a signal, the local transmitter automatically returns to normal operation. The design of the
FRM-E1/T1
utilizes the FEF to generate AIS to the connected CSU equipment, so that alarms are transmitted in the traditional
fashion when there is a fiber fault.
Figure A-? Far End Fault feature of FRM-E1 and FRM-T1
The FRM-E1 and FRM-T1 media converters incorporate Loop back testing features that may be used with BER
(Bit Error Rate) test equipment. Loop back is enabled by the DIP switch#3&4 on the front panel. When installed in a
manageable rack, loop back testing is enabled via the console menu, Telnet menu, SNMP get/set commands, or
from a web browser.
Figure A-? FRM-E1 and FRM-T1 loop back functions
Fiber
fault
FEF received
E1 CSU
AIS
FEF generated
AIS
E1 CSU
LLB
Local
loopback
Remote
Local Side
RLB
Remote
loopback
Remote
Local Side
RRLB
Request
Remote
loopback
Remote
Local Side
Remote
Local Side
RX
TX
RX
TX