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docsIfSigQMicroreflections - docsIfSigQCorrecteds - docsIfSigQUnerroreds

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deividfiguer
docsIfSigQMicroreflections - docsIfSigQCorrecteds - docsIfSigQUnerroreds

Hi

Please help me interpret these snmp query results to 2 cable modem to compare and understand

I want to know what is the recommended value of the results of each of these queries to a cable modem

name = "docsIfSigQMicroreflections"
oid = "1.3.6.1.2.1.10.127.1.1.4.1.6"

for example from docsIfSigQMicroreflections what is the recommended value on the cable modem

Cable Modem 1:
snmpwalk -v 2c -c public 10.1.198.3 1.3.6.1.2.1.10.127.1.1.4.1.6
iso.3.6.1.2.1.10.127.1.1.4.1.6.3 = INTEGER: 19
iso.3.6.1.2.1.10.127.1.1.4.1.6.48 = INTEGER: 16
iso.3.6.1.2.1.10.127.1.1.4.1.6.49 = INTEGER: 18
iso.3.6.1.2.1.10.127.1.1.4.1.6.50 = INTEGER: 16
iso.3.6.1.2.1.10.127.1.1.4.1.6.51 = INTEGER: 15
iso.3.6.1.2.1.10.127.1.1.4.1.6.52 = INTEGER: 15
iso.3.6.1.2.1.10.127.1.1.4.1.6.53 = INTEGER: 18
iso.3.6.1.2.1.10.127.1.1.4.1.6.54 = INTEGER: 17

Cable Modem 2:
snmpwalk -v 2c -c public 10.1.184.193 1.3.6.1.2.1.10.127.1.1.4.1.6
iso.3.6.1.2.1.10.127.1.1.4.1.6.3 = INTEGER: 25
iso.3.6.1.2.1.10.127.1.1.4.1.6.48 = INTEGER: 27
iso.3.6.1.2.1.10.127.1.1.4.1.6.49 = INTEGER: 28
iso.3.6.1.2.1.10.127.1.1.4.1.6.50 = INTEGER: 28
iso.3.6.1.2.1.10.127.1.1.4.1.6.51 = INTEGER: 26
iso.3.6.1.2.1.10.127.1.1.4.1.6.52 = INTEGER: 31
iso.3.6.1.2.1.10.127.1.1.4.1.6.53 = INTEGER: 25
iso.3.6.1.2.1.10.127.1.1.4.1.6.54 = INTEGER: 34

-------------------------------------------------------------------------------

name = "docsIfSigQCorrecteds"
oid = "1.3.6.1.2.1.10.127.1.1.4.1.3"

Cable Modem 1:
snmpwalk -v 2c -c public 10.1.198.3 1.3.6.1.2.1.10.127.1.1.4.1.3
iso.3.6.1.2.1.10.127.1.1.4.1.3.3 = Counter32: 4
iso.3.6.1.2.1.10.127.1.1.4.1.3.48 = Counter32: 7
iso.3.6.1.2.1.10.127.1.1.4.1.3.49 = Counter32: 2
iso.3.6.1.2.1.10.127.1.1.4.1.3.50 = Counter32: 0
iso.3.6.1.2.1.10.127.1.1.4.1.3.51 = Counter32: 4
iso.3.6.1.2.1.10.127.1.1.4.1.3.52 = Counter32: 12
iso.3.6.1.2.1.10.127.1.1.4.1.3.53 = Counter32: 2
iso.3.6.1.2.1.10.127.1.1.4.1.3.54 = Counter32: 2

Cable Modem 2:
snmpwalk -v 2c -c public 10.1.184.193 1.3.6.1.2.1.10.127.1.1.4.1.3
iso.3.6.1.2.1.10.127.1.1.4.1.3.3 = Counter32: 8
iso.3.6.1.2.1.10.127.1.1.4.1.3.48 = Counter32: 6
iso.3.6.1.2.1.10.127.1.1.4.1.3.49 = Counter32: 7
iso.3.6.1.2.1.10.127.1.1.4.1.3.50 = Counter32: 18
iso.3.6.1.2.1.10.127.1.1.4.1.3.51 = Counter32: 38
iso.3.6.1.2.1.10.127.1.1.4.1.3.52 = Counter32: 28
iso.3.6.1.2.1.10.127.1.1.4.1.3.53 = Counter32: 13
iso.3.6.1.2.1.10.127.1.1.4.1.3.54 = Counter32: 33

-----------------------------------------------------------------------------
name = "docsIfSigQUnerroreds"
oid = "1.3.6.1.2.1.10.127.1.1.4.1.2"

Cable Modem 1:
snmpwalk -v 2c -c public 10.1.198.3 1.3.6.1.2.1.10.127.1.1.4.1.2
iso.3.6.1.2.1.10.127.1.1.4.1.2.3 = Counter32: 1442613912
iso.3.6.1.2.1.10.127.1.1.4.1.2.48 = Counter32: 1442512815
iso.3.6.1.2.1.10.127.1.1.4.1.2.49 = Counter32: 1442524408
iso.3.6.1.2.1.10.127.1.1.4.1.2.50 = Counter32: 1442519631
iso.3.6.1.2.1.10.127.1.1.4.1.2.51 = Counter32: 1442493937
iso.3.6.1.2.1.10.127.1.1.4.1.2.52 = Counter32: 1442511883
iso.3.6.1.2.1.10.127.1.1.4.1.2.53 = Counter32: 1442501741
iso.3.6.1.2.1.10.127.1.1.4.1.2.54 = Counter32: 1442507998

Cable Modem 2:
snmpwalk -v 2c -c public 10.1.184.193 1.3.6.1.2.1.10.127.1.1.4.1.2
iso.3.6.1.2.1.10.127.1.1.4.1.2.3 = Counter32: 128633862
iso.3.6.1.2.1.10.127.1.1.4.1.2.48 = Counter32: 128536742
iso.3.6.1.2.1.10.127.1.1.4.1.2.49 = Counter32: 128531958
iso.3.6.1.2.1.10.127.1.1.4.1.2.50 = Counter32: 128527228
iso.3.6.1.2.1.10.127.1.1.4.1.2.51 = Counter32: 128505919
iso.3.6.1.2.1.10.127.1.1.4.1.2.52 = Counter32: 128523308
iso.3.6.1.2.1.10.127.1.1.4.1.2.53 = Counter32: 128513403
iso.3.6.1.2.1.10.127.1.1.4.1.2.54 = Counter32: 128519534

kwesibrunee
docsIfSigQMicroreflections is

docsIfSigQMicroreflections is a measurement of how much of the signal is being reflected back to the sender when it hits things like an impedance mismatch. I have always used < ~20 dB as the rule of thumb but I don't remember exactly why.

docsIfSigQUnerroreds, docsIfSigQCorrecteds and docsIfSigQUncorrectables are all related.

When codewords ( How data is transmitted in Docsis) are received, one of three things happen:

1) it is received with no error, and the docsIfSigQUnerroreds counter is incremented
2) it is received with an error that FEC can account for, and the docsIfSigQCorrecteds is incremented
3) it is received with too many errors that FEC cannot account for, and the docsIfSigQUncorrectables counter is incremented

The counters by themselves are fairly unhelpful, in order to interpret this information you need to:

retrieve all three values, note the timestamp, retrieve all three values a second time, noting the timestamp.

now you need to get the difference between the second retrieval and the first retrieval, if the first retrieval is larger than the second, then the counter has overflowed and reset down to zero, and you need to account for it. This is done by taking 2^32 (for 32 bit counters) and subtracting first retrieval, and adding second retrieval to the result.

Now you need to determine the time difference between the two timestamps and divide the result from previous result by time in seconds to get the rate per second.

Now that you have a rate, you need to determine how much % wise each type is occurring.

Add docsIfSigQUnerroreds, docsIfSigQCorrecteds and docsIfSigQUncorrectables rates together, and take each individual value and divide it by the total which will give you the percentage of the data that falls into each category

Here is an example:

First Retrieval: timestamp 4/2/2023 9:50 AM
docsIfSigQUnerroreds : 4294967000
docsIfSigQCorrecteds : 5
docsIfSigQUncorrectables : 25

Second Retrieval: timestamp 4/2/2023 9:51 AM
docsIfSigQUnerroreds : 404
docsIfSigQCorrecteds : 50
docsIfSigQUncorrectables : 250

Difference in codewords:
docsIfSigQUnerroreds : (4,294,967,296 - 4294967000) + 404 = 700
docsIfSigQCorrecteds : 50 - 5 = 45
docsIfSigQUncorrectables : 250 - 25 = 225

Difference in timestamps in seconds
4/2/2023 9:51 AM - 4/2/2023 9:50 AM = 60 secs

Codewords Rate per second
docsIfSigQUnerroreds : 700 / 60 = 11.67
docsIfSigQCorrecteds : 45 / 60 = 0.75
docsIfSigQUncorrectables : 225 / 60 = 3.75

now to find the % of each type of codewords:
add all values together: 11.67 + 0.75 + 3.75 = 16.17 total codewords per second
docsIfSigQUnerroreds : 11.67/16.17 = 0.722 *100 = 72.2%
docsIfSigQCorrecteds : 0.75 / 16.17 = 0.046 * 100 = 4.6%
docsIfSigQUncorrectables : 3.75 / 16.17 = 0.232 * 100 = 23.2%

To me it makes the most sense to display this breakdown in a graph where, docsIfSigQUnerroreds are green, docsIfSigQCorrecteds are yellow, and docsIfSigQUncorrectables are red

So one that looked like this:
https://imgur.com/ygixNm5 would be considered great 100% unnerorred

whereas one that looks like this:
https://imgur.com/H0lczJ2 would be very bad, with 25% uncorrectable.

I have always used the rules:
<1% uncorrectable will be barely noticeable to a customer, but anything over 1% will cause problems and lead to a poor customer experience
<5% correctable will be barely noticeable to customers but is an indicator that uncorrectables are very likely (Docsis 3.0, for Docsis 3.1 correctables are not an indicator that uncorrectables are likely due to different FEC mechanics)

Other people prefer to break it down into a BER value, in this example, this would be 0.232 or 2.31e-1 anything larger than 0.000001 or 1e-6 will cause problems.

deividfiguer
docsIfSigQMicroreflections

Hi
Looking in another forum I found this information:
https://docsis.org/forums/docsis-chat/downstream-micro-reflections

The result of the oid .1.3.6.1.2.1.10.127.1.1.4.1.6 is expressed in dBc and the higher the better, "because that means a big distance between the carrier and the effects of the microreflection"

if it is greater than 20 dBc it is better than if it is a lower value, what would be the limit value to define between good and bad.?

please help me understand and define what is the value to tell my technicians what dBc value is good or bad

For example

less than x dBc is bad or good.

kwesibrunee
Try this page: https:/
deividfiguer
docsIfSigQMicroreflections - docsIfSigQCorrecteds - docsIfSigQUn

Hi

according to the information: anything greater than -25 dBc is considered bad
taking into account that the unit is -dBc (negative value)

for example in this test with cable modem 1 and 2

The cable modem 1 has bad levels (greater than -25 dBc)
The cable modem 2 has good levels (less than -25 dBc)

note that the output of the snmp command does not include the sign "-"

please help me indicating if my conclusion is correct ?

Cable Modem 1:
snmpwalk -v 2c -c public 10.1.198.3 1.3.6.1.2.1.10.127.1.1.4.1.6
iso.3.6.1.2.1.10.127.1.1.4.1.6.3 = INTEGER: 19
iso.3.6.1.2.1.10.127.1.1.4.1.6.48 = INTEGER: 16
iso.3.6.1.2.1.10.127.1.1.4.1.6.49 = INTEGER: 18
iso.3.6.1.2.1.10.127.1.1.4.1.6.50 = INTEGER: 16
iso.3.6.1.2.1.10.127.1.1.4.1.6.51 = INTEGER: 15
iso.3.6.1.2.1.10.127.1.1.4.1.6.52 = INTEGER: 15
iso.3.6.1.2.1.10.127.1.1.4.1.6.53 = INTEGER: 18
iso.3.6.1.2.1.10.127.1.1.4.1.6.54 = INTEGER: 17

Cable Modem 2:
snmpwalk -v 2c -c public 10.1.184.193 1.3.6.1.2.1.10.127.1.1.4.1.6
iso.3.6.1.2.1.10.127.1.1.4.1.6.3 = INTEGER: 28
iso.3.6.1.2.1.10.127.1.1.4.1.6.48 = INTEGER: 27
iso.3.6.1.2.1.10.127.1.1.4.1.6.49 = INTEGER: 28
iso.3.6.1.2.1.10.127.1.1.4.1.6.50 = INTEGER: 28
iso.3.6.1.2.1.10.127.1.1.4.1.6.51 = INTEGER: 26
iso.3.6.1.2.1.10.127.1.1.4.1.6.52 = INTEGER: 31
iso.3.6.1.2.1.10.127.1.1.4.1.6.53 = INTEGER: 25
iso.3.6.1.2.1.10.127.1.1.4.1.6.54 = INTEGER: 34

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