XKL DarkStar DBA-L, Руководство пользователя

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DarkStar User Guide
3: Software
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You can measure the interface BER using a Bit Error Ratio Test (BERT), which transmits bit test patterns and counts the bit errors
at the receiver, over an extended period.
The DarkStar BERT testing method uses patterns of logical ones and zeros generated by a Pseudo-Random Binary Sequence
(PRBS). The DarkStar system generates a PRBS with a bit length of 2
31
-1.
You can run a BERT on a single DarkStar system, on one interface, by looping together the Rx and Tx sides. You can also run a
BERT on paired DarkStar systems by transmitting on an interface on the first system, and receiving on an interface on the
second system. A DarkStar system can transmit BERTs from multiple interfaces, but receive just one BERT transmission at a
time; you must cancel receiving an existing BERT transmission before attempting to receive a new BERT transmission.
The BERT feature uses a single clock setting and will automatically adjust to the encapsulation of the most recently selected
interface; for this reason separate interfaces used with BERT must be set to the same encapsulation.
The commands used to run BERT are fully detailed in the “DarkStar DXMOS Command Reference”. To run BERT, first select the
desired interface(s) and run
bert logging
to configure testing frequency and logging files. Issue a
bert transmit
on
the transmitting interface to initiate PRBS generation, followed by a
bert receive
command that initiates checking of the
PRBS stream, begins counting errors, and measures elapsed time. Use
show bert
and
show bert logging
to verify
that a BERT is running, and to view BERT results.
3.4.1 Configure BERT logging
Before enabling BERT, ensure that LOS and/or LOL conditions are not present by using the
show interface
command.
Verify that the optical fibers between the selected interfaces are properly secured and appropriately powered.
On startup of a DarkStar system, BERT logging is disabled by default. You configure logging settings using the
bert
logging
command, which allows you to specify the time between logs, as well as the maximum number of logs kept. You
can use the
write memory
command to save these settings to the startup configuration file, as in this example:
labcons9 CONF# bert logging number-of-samples 15
labcons9 CONF# exit
labcons9# write memory
Are you sure? [yes/no] yes
labcons9# sho startup-config
Contents of config file /dxmos/config.dat:
… …
bert logging max-log-count 25
bert logging log-interval seconds 1
bert logging number-of-samples 15
… …
Verify a BERT is running
While a BERT is running, the
show bert
command can be used on any transport interface to obtain test results up to the
time that the command was issued. This method displays the BERT status for all interfaces running a BERT, and may be useful
to spot check results during an ongoing BERT run.