Using Bit Error Rate Tests - Cisco ASR 1000 Series Software Configuration Manual

Using Bit Error Rate Tests

Using Bit Error Rate Tests
BERT (Bit-Error Rate Testing) is used for analyzing quality and for problem resolution of digital transmission
equipments. BERT tests the quality of an interface by directly comparing a pseudorandom or repetitive test
pattern with an identical locally generated test pattern.
The BERT operation is data-intensive. Regular data cannot flow on the path while the test is in progress. The
path is reported to be in alarm state when BERT is in progress and restored to a normal state after BERT has
been terminated.
BERT is built into most of the serial SPAs. With BER tests, you can test cables and signal problems in the
field.
• For the 2-Port and 4-Port Channelized T3 SPA, you can configure individual T1 lines to run BER tests,
• For the 8-port Channelized T1/E1 SPA, there are six framer-assisted BERT engines, and six BER tests
• For the 1-Port Channelized OC-3/STM-1 SPA and 1-Port Channelized OC-12/STM-4 SPA, you can
Note BERT operation is data-intensive. Regular data cannot flow on the path while the test is in progress. The
path is reported to be in alarm state when BERT is in progress and restored to a normal state after BERT
has been terminated.
There are two categories of test patterns that can be generated by the onboard BER test circuitry: pseudorandom
and repetitive. Pseudorandom test patterns are exponential numbers and conform to the CCITT/ITU O.151
and O.153 specifications; repetitive test patterns are all zeros, all ones, or alternating zeros and ones.
A description of the test patterns follows:
• Pseudorandom test patterns:
• Repetitive test patterns:
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS
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but only one BER test circuit exists for all 28 T1 lines. Hence, only one BER test can be run on a single
T3 port at any given time.
may run concurrently.
run a maximum of 27 concurrent tests across all paths on the SPA.
◦ 2^15 (per CCITT/ITU O.151)
◦ 2^20 (per CCITT/ITU O.153)
◦ 2^23 (per CCITT/ITU O.151)
◦ QRSS (quasi-random signal sequence) (per CCIT/ITU O.151)
◦ All zeros (0s)
◦ All ones (1s)
◦ Alternating zeros (0s) and ones (1s)
Troubleshooting the Serial SPAs
OL-14127-17