Great Video! Is there any industry standard that states roughly when a subscriber would start to notice impairments due to CCER specifically? My company currently uses a diagnostics tool that graphs CER/CCER on the same scale as a fail at 1% for both CER/CCER. And I personally believe this is a form of misinformation as it leaves a lot of remote care representatives saying example 1.5% CCER is causing slow internet issues when I am hesitant to believe that. It also leads to a lot of repeat trouble tickets being submitted because uninformed technicians don't truly understand these metrics so they assume it being in the red is bad and improperly link the problem to this. Obviously, any level of uncorrectable is caused by some form of impairment and should be watched closely but realistically what percentage of corrected codeword errors would you begin to see services impacted?
Yes, if your support reps are flagging a 1% codeword error rate as something to be overly concerned about, and that is really made up of correctable codewords, then that's not good. Of course, if it's uncorrectables, that might be different, and if you can't differentiate as to what they are, then it's difficult to know when it's likely causing a problem. As far as recommended percentages, it's going to depend on the service the subscriber is using. We would say keep *uncorrectable* codeword errors under 1% for VoIP, or the customer will start to notice voice quality issues, like the audio breaking up at times due to dropped packets. Once you get to 3% uncorrectables it's going to start to get pretty noticeable for normal use due to the amount of dropped and retransmitted packets. At 5% we would expect customers to be complaining about their service. In our TruVizion application we set the defaults to this: For Correctable Codeword Errors we change from green to yellow at 15%, and from yellow to red at 25%. For Uncorrectables we change from green to yellow at 0.005%, and from yellow to red at 0.01%. Those thresholds can be changed by the service provider if they like. You might find this other broadcast interesting, where we show our TruVizion software and how it separately tracks correctable and uncorrectable codeword errors: ruclips.net/video/-t40eQo0nh4/видео.html
When looking at CER/CCER on your modem or the CMTS, other techs have said "look at that packet loss...45% CCER". Formally we have only been able to tell if there is truly packet loss on the RF by running a live DOCSIS packet loss test with our signal level meter to see it in real time and verify it is coming from plant. Is it incorrect to use that terminology for CER/CCER or is it okay to call it packet loss without doing that live RF DOCSIS test over coax?
Also, when making the distinction between codeword error ratio and corrected codeword error ratio; is it safe to think of CER as uncorrectables and CCER as correctables? Thanks.
If you have uncorrectable codeword errors, you have some level of packet loss, because some number of bits could not be repaired by error correction and so had to be dropped. Those packets then need to be re-transmitted. Obviously, the higher the uncorrectable codeword errors, the more issues this will cause, especially with certain applications. On an application like VoIP even a lower percentage of UCEs can cause problems, because you can't re transmit those packets due to the nature of voice service. That's when you get skips in the audio. Yes, it is safe to think of CER and CCER as uncorrectable and correctable codeword rates.
Resetting the modem would at most be a temporary fix, because the source of the codeword errors is probably not the modem itself. The issue is more likely in the physical cable plant somewhere. It could be a loose or corroded connector, cracked cable, or some other impairment that is interfering with the signal. If you are talking about in the home, you can make sure the connector on the modem is tight. If it's further out in the cable plant, the cable company would need to find the source of the impairment causing the codeword errors. That could also be bad connectors, actives, passives, or cable. For the cable operator, a diagnostics application like TruVizion can help track that down, as well as a Proactive Network Maintenance (PNM) tool like PreEqualization Analyzer (www.PreEqualizationAnalyzer.com).
Great Video! Is there any industry standard that states roughly when a subscriber would start to notice impairments due to CCER specifically? My company currently uses a diagnostics tool that graphs CER/CCER on the same scale as a fail at 1% for both CER/CCER. And I personally believe this is a form of misinformation as it leaves a lot of remote care representatives saying example 1.5% CCER is causing slow internet issues when I am hesitant to believe that. It also leads to a lot of repeat trouble tickets being submitted because uninformed technicians don't truly understand these metrics so they assume it being in the red is bad and improperly link the problem to this. Obviously, any level of uncorrectable is caused by some form of impairment and should be watched closely but realistically what percentage of corrected codeword errors would you begin to see services impacted?
Yes, if your support reps are flagging a 1% codeword error rate as something to be overly concerned about, and that is really made up of correctable codewords, then that's not good. Of course, if it's uncorrectables, that might be different, and if you can't differentiate as to what they are, then it's difficult to know when it's likely causing a problem. As far as recommended percentages, it's going to depend on the service the subscriber is using. We would say keep *uncorrectable* codeword errors under 1% for VoIP, or the customer will start to notice voice quality issues, like the audio breaking up at times due to dropped packets. Once you get to 3% uncorrectables it's going to start to get pretty noticeable for normal use due to the amount of dropped and retransmitted packets. At 5% we would expect customers to be complaining about their service. In our TruVizion application we set the defaults to this: For Correctable Codeword Errors we change from green to yellow at 15%, and from yellow to red at 25%. For Uncorrectables we change from green to yellow at 0.005%, and from yellow to red at 0.01%. Those thresholds can be changed by the service provider if they like. You might find this other broadcast interesting, where we show our TruVizion software and how it separately tracks correctable and uncorrectable codeword errors: ruclips.net/video/-t40eQo0nh4/видео.html
When looking at CER/CCER on your modem or the CMTS, other techs have said "look at that packet loss...45% CCER". Formally we have only been able to tell if there is truly packet loss on the RF by running a live DOCSIS packet loss test with our signal level meter to see it in real time and verify it is coming from plant. Is it incorrect to use that terminology for CER/CCER or is it okay to call it packet loss without doing that live RF DOCSIS test over coax?
Also, when making the distinction between codeword error ratio and corrected codeword error ratio; is it safe to think of CER as uncorrectables and CCER as correctables? Thanks.
If you have uncorrectable codeword errors, you have some level of packet loss, because some number of bits could not be repaired by error correction and so had to be dropped. Those packets then need to be re-transmitted. Obviously, the higher the uncorrectable codeword errors, the more issues this will cause, especially with certain applications. On an application like VoIP even a lower percentage of UCEs can cause problems, because you can't re transmit those packets due to the nature of voice service. That's when you get skips in the audio. Yes, it is safe to think of CER and CCER as uncorrectable and correctable codeword rates.
So what can I do about it other than resetting the modem?
Resetting the modem would at most be a temporary fix, because the source of the codeword errors is probably not the modem itself. The issue is more likely in the physical cable plant somewhere. It could be a loose or corroded connector, cracked cable, or some other impairment that is interfering with the signal. If you are talking about in the home, you can make sure the connector on the modem is tight. If it's further out in the cable plant, the cable company would need to find the source of the impairment causing the codeword errors. That could also be bad connectors, actives, passives, or cable. For the cable operator, a diagnostics application like TruVizion can help track that down, as well as a Proactive Network Maintenance (PNM) tool like PreEqualization Analyzer (www.PreEqualizationAnalyzer.com).
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The last time i had this problem the cable company had to go up the pole and fix the connection