cxrider's profile

Regular Contributor

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89 Messages

Tue, Jan 28, 2020 5:00 AM

What are the acceptable error rates for downstream connections?

I am using a SB8200 modem and I am noticing what I consider a high rate of correctable errors.   I am concerned that this is a sign of a pending problem.   While I understand that uncorrectable errors are a bigger problem, and that a few uncorrectables is not a huge concern, I'd like to know what level of correctables indicates a pending problem.     I log counters hourly and I am seeing a rate of about 100 correctable errors / hr.     Is this a concern or should I turn down my level of alerting?    If I go back through my history of approximately six  months I do not see this rate; typically closer to 10s of correctables / hr so this represents about an order of magnitude more errors on an hourly rate.  

 

TIA

Responses

jweaver0312

Expert

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1.9K Messages

1 y ago

For correctables, it doesn’t matter. It could say 10,000 and mean nothing. Correctables are errors the modem was able to correct.

Like you said, higher accumulation of uncorrectables are where a problem indicator comes into play. For uncorrectables, the key is to notice an issue and then monitor it. Ideally, you should have 0 uncorrectables but a few here and there are ok. If it’s accumulating 100s or even 1000 in short time span, up to a day, that could be the indicator of an issue.
EG

Expert

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87.2K Messages

1 y ago


@cxrider wrote:

I am using a SB8200 modem and I am noticing what I consider a high rate of correctable errors.   I am concerned that this is a sign of a pending problem.   While I understand that uncorrectable errors are a bigger problem, and that a few uncorrectables is not a huge concern,


FWIW, a large number of correctable errors (even though they have been corrected) can indeed be an indicator that something is going on with the quality of the connection. Most times it is caused by noise ingress into the lines / system somewhere.

cxrider

Regular Contributor

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89 Messages

1 y ago

What's considered a large number and more importantly, what rate of errors is considered high and needing remediation?  

 

I get that correctables happen from time to time.    In my experience with ethernet and infiniband networks errors are exceptionally rare so when an infiniband port starts reporting more than a handful of correctable errors an hour remediation is performed.   For ethernet hardware problems seem to be binary; you see effectively zero errors for months/years or the connection is virtually unusable.     How does cable media behave?  

cxrider

Regular Contributor

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89 Messages

1 y ago

It's not necessarily true that correctables mean nothing.    While I have no doubt that occasional correctables represent no concern, error correction is not free.   The device doing the correction has to perform some kind of calculation before sending the data on which in the end represents latency on the network.  While 10,000 correctables over a month might go unnoticed, I'm pretty certain 10,000 correctables a minute is going to provide an unpleasant user experience.    How fast they come matters and a change in how fast they come indicates a change somewhere in the system.

jweaver0312

Expert

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1.9K Messages

1 y ago

I was using 10,000 as a hypothetical.
cxrider

Regular Contributor

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89 Messages

1 y ago

As was I.   The point is you can not just ignore correctables.   Rate of change matters.    Given the number of line problems I have had in the past, I am convinced Comcast does not pro-actively monitor for problems which means I must.    That's fine and I will.  I plan to be pro-active and if I detect a problem I plan to call out maintenance, afterall, it takes Comcast time to dispatch a line tech and if a problem is brewing I'd rather nip it in the bud than have it take me down for a few days.  

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