Hello, @Alex4161
We appreciate you posting your concerns to the Community!
Trying to enjoy your TV service when the picture of sound is choppy can become a major source of frustration. Please provide us with the answers to the questions below.
- Can you describe the way most of your devices are connected? Is it only via Wi-Fi or are some affected devices connected via Ethernet as well?
- Do you notice the slow speeds throughout the home or do you find it improves if you are closer to the modem?
@-G-, has discussed the topic of correctable codewords previously and may be able to provide us with some valuable insight.
We look forward to your response!
RogersTony
@RogersTony wrote:
@-G-, has discussed the topic of correctable codewords previously and may be able to provide us with some valuable insight.
Hi, Tony. I'll do my best to shed a bit more light on this topic but it's important to understand how the underlying technologies work before you can really understand what the different errors and error stats mean. DOCSIS 3.0 and 3.1 are very different. Uncorrectable codeword errors are bad. They represent packet loss. Uncorrectable codeword errors also need to be kept low on D3.1 because when they reach a certain threshold, the modem can drop down to using D3.0. However, the correctable codewords error stats need to be interpreted differently in D3.1 than they do with D3.0.
With D3.0, you ideally want to assign channels that are as clean as possible. When the bit error rate starts increasing, it's an indicator that problems on the line are getting worse, and you will start to see an increase in the number of correctable codeword errors relative to the amount of data transmitted in a given time period. You need to deal with a high correctable codeword error rate before line conditions worsen to the point that the uncorrectable codeword error rates spike and you start to get poor performance and packet loss.
With D3.0, you want to avoid bad line conditions; the protocol does not deal with them very well. However, the reality is that line conditions are also never perfect. One of the DOCSIS 3.1 design goals is to do a better job dealing with imperfect line conditions that we see in the real world, and to enable cable operators to get the most out of their cable plants.
For a D3.1 primer and a summary of the best practices for deploying it, I will refer you to this white paper:
When deploying D3.1 you can encode data on the channel in different ways. You want to use a profile that allows you to get the maximum throughput that is possible. Let the protocol correct for errors... but you still want to keep uncorrectable codeword errors as close to zero as possible. You can deploy D3.1 using a profile that does keep correctable errors to a minimum. However, correctable errors do not impact performance or cause packet loss... so if you do not have any, you either have an incredibly clean line or you are not using the cable plant to its maximum capacity.
So... as long as the uncorrectable codeword errors are zero or close to zero, correctable codeword errors are arguably a good thing. Don't believe me? Then have a look at this:
Even if the technical level of the paper is above you, it does echo what I have said before:
In reality if you aren’t pushing your higher profiles to the level that you have correctable errors and an acceptable level of uncorrectable errors, you aren’t getting the maximum effectiveness and efficiency that OFDM with LDPC can provide. You should expect to see the higher profiles continually operating with Correctable CWE’s. This is OKAY.
The takeaway is that as long as you are not seeing the uncorrectable codeword errors on the D3.1 channels spike, there is no cause for concern. The downside to D3.1 is that when the correctable codeword errors spike beyond what is nominal, you will likely also see uncorrectable codeword errors spike as well, and you can no longer use correctable codeword errors as an "early warning system" of line conditions worsening.
@Alex4161 wrote:
Thanks for your response. My Ignite TV devices are connected by wired and wireless and they all have these issues on some channels. Both WiFi and Ethernet connected devices also experience slow speeds time to time.
Only on some channels? That's more indicative of a problem with the source feed and how it is being processed by the IPTV encoders.
If you are seeing audio/video dropouts on all channels, then that is indicative of a network problem somewhere. It could be a problem within your home or it could be a problem on Rogers' side, or both. It could also be caused by problems on the HDMI link between the set-top box and the TV.
Ignite TV is streamed/buffered and consumes roughly 10 Mb/s for HD channels. The traffic is sent in bursts. You will get a dropout when the decoder in the set-top box needs to process the next segment in the video stream but either did not receive it or did not receive it in time.
If your WiFi network is performing exceptionally poorly, the data rate on the link may drop down to only 6 Mb/s and that will cause problems for Ignite TV on wireless set-top boxes.
I won't go into troubleshooting WiFi here. However, keep in mind that even wired set-top boxes maintain WiFi connections, and I've seen even wired set-top boxes do weird things when their WiFi connection is unstable.
It's possible that you can also see problems even on a wired Ethernet connection. (It could be caused by a bad Ethernet cable or a problem with the LAN switch hardware.) Unfortunately, these can be hard to diagnose because neither the Ignite modem nor most consumer LAN switches report MAC-level errors or provide you with any helpful diagnostic tools.
If your local Rogers node is overloaded and network latency is exceptionally high, or you are getting packet loss (due to uncorrectable codeword errors or packet buffers in network gear overflowing), that will also cause problems for Ignite TV.
If you suspect a perform with the Rogers network, you need to perform the following sustained ping tests:
- From your computer to the Ignite modem, to test for high latency/packet loss in your home network.
- From your computer to the local CMTS router: to test for high latency/packet loss in your connection to the Rogers network.
- From your computer to a well-connected Internet host: to test for high latency/packet loss upstream.
To resolve any Ignite TV issues, I would recommend simplifying your network as much as possible and connecting all of your set-top boxes over WiFi. At that point, you will be running Ignite TV on infrastructure that Rogers can test and troubleshoot end-to-end.
@TheBings wrote:
Just wanting to know if this is normal to have error codewords so high seems like my channel 1 and 33 are crazy high
The CM Error Codewords stats in index 1 and 33 are identical, and those are the counts are for the DOCSIS 3.1 OFDM channel. It's totally normal to have a high number of correctable codewords errors on the OFDM channel but the number of uncorrectable codewords errors should be 0, or as close to 0 as possible. Yours error counts are VERY high.
Actually, all your error counts are high across the board... and your SNR values on the downstream channels are low. How long has your modem been up for and are all the error counts still climbing at a high rate or have they levelled off?
I would call into Rogers and have them check the signal levels to your modem, check the error counts on the CMTS, noise levels, and whether there are any issues affecting your neighbourhood. All of this could potentially also be caused by something as simple as a bad coax patch cable, or perhaps noise leakage onto a common ground. Hard to say for sure what this could be but things definitely do not look right to me.
@TheBings I would call into tech support, tell them that you are seeing a ton of packet loss and that your modem is logging a huge number of uncorrectable codeword errors.
Before calling, log into your modem, go to "Troubleshooting > Logs" and view the "Events log" for the Last week. Normally, that error log should be clean. If you are seeing a bunch of Critical errors, let them know as well.
If they still tell you that everything looks good then, as nicely as possible, ask why the modem would logging all of those errors, on all downstream channels, if there is nothing wrong. Request that they open a ticket and transfer you to a level-2 agent that can troubleshoot further.
There's definitely a problem somewhere. Hopefully they will see something amiss that can be corrected.
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RogersTony
@yyzguy wrote:
I recently switched over to Ignite internet/TV. While checking my signal levels today, I noticed very high levels of correctable codewords on Index 1 and 33. In both cases, the number of correctable codewords exceeded (by an order of magnitude) the number of unerrored codewords. Is this a problem?
A huge number of Correctable Codewords on DOCSIS 3.1 channels is not a problem. Actually, it's a good thing: https://communityforums.rogers.com/t5/Ignite-TV/High-CM-Correctable-Codewords/m-p/464934/highlight/t...
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