Is there any way to obtain a measurement of the downstream BER or MER with a cable modem, without using a QAM analyzer/tester?
The Cisco uBR900s are reporting always 0, and they say in the docs it does not report this value. Are there any SNMP MIBS for obtaining pre/post-FEC error rates?
I use docsIfSignalQualityEntry. It gives you signal to noise. Also the codeword stats which I find very usefull. A significant number of uncorrectables bursting, not slowly incrementing, is a bad thing. You will find as the modem reported S/N degrades the codeword errors will begin to increase.
RegattaProvisioning:~ # snmpwalk -v2c -c xxxxxxxxx 159.159.24.175 docsIfSignalQualityEntry
DOCS-IF-MIB::docsIfSigQIncludesContention.3 = INTEGER: false(2)
DOCS-IF-MIB::docsIfSigQUnerroreds.3 = Counter32: 801319211
DOCS-IF-MIB::docsIfSigQCorrecteds.3 = Counter32: 3
DOCS-IF-MIB::docsIfSigQUncorrectables.3 = Counter32: 0
DOCS-IF-MIB::docsIfSigQSignalNoise.3 = INTEGER: 42.3 dB
DOCS-IF-MIB::docsIfSigQMicroreflections.3 = INTEGER: 16 dBc
DOCS-IF-MIB::docsIfSigQEqualizationData.3 = ""
DOCS-IF-MIB::docsIfSignalQualityEntry.8.3 = Counter64: 801319211
DOCS-IF-MIB::docsIfSignalQualityEntry.9.3 = Counter64: 3
DOCS-IF-MIB::docsIfSignalQualityEntry.10.3 = Counter64: 0
What are these counters relate to:
DOCS-IF-MIB::docsIfSignalQualityEntry.8.3 = Counter64: 801319211
DOCS-IF-MIB::docsIfSignalQualityEntry.9.3 = Counter64: 3
DOCS-IF-MIB::docsIfSignalQualityEntry.10.3 = Counter64: 0
Thanks.
these are 64bit version of
DOCS-IF-MIB::docsIfSigQUnerroreds.3 = Counter32: 801319211
DOCS-IF-MIB::docsIfSigQCorrecteds.3 = Counter32: 3
DOCS-IF-MIB::docsIfSigQUncorrectables.3 = Counter32: 0
--
affordable, robust provisioning and monitoring software for DOCSIS networks: dps.cable@gmail.com
Look at the CM-SP-PHYv3.0-I08-090121.pdf from http://www.cablelabs.com/specifications/doc30.html
Page 96
6.3.3.11 64QAM CM BER Performance
there is an formula on the next page to calculate the CER/BER via the codewords
regards,
wittmann