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XB6 gateway shows incorrect (really bad) DOCSIS stats

toolcubed
I'm a senior contributor

Hello community. My Ignite XB6 gateway has been showing horrendous DOCSIS stats for the past couple of weeks. Almost all DOCSIS channels are in the -16db range and SNR at around 34db. My upstream power levels are also all elevated at 52db. Yet I have absolutely zero problems. My internet speeds are fast, stable, and consistent. My pings and jitter are consistently very low. My Ignite TV service is working perfectly fine. I don’t have any drops or disconnections either.

I rebooted the gateway but the stats remained poor. I then factory reset the gateway, and still my stats are really bad, but still no issues with internet or TV.

I called tech support. They ran a test and confirmed exactly what I’m seeing, which caused the test to fail and triggered a tech visit for tomorrow morning.

This is really odd. With these DOCSIS stats, I would expect problems but I don’t have any whatsoever.

Could the XB6 be reporting false readings?

 

 

***Edited Labels***

7 REPLIES 7

Re: XB6 gateway shows incorrect (really bad) DOCSIS stats

toolcubed
I'm a senior contributor

Nevermind. Tech showed up. The outside line is fine but the tap (pedestal) is bad. He’s getting a reading of -8db at the tap. My line is almost 200ft from tap to house, which leads to another 7-8 db loss with attenuation. So the levels reported by the XB6 are accurate. Tech escalated to maintenance. I hope this doesn’t turn into a multi-month ordeal.

Re: XB6 gateway shows incorrect (really bad) DOCSIS stats

-G-
Resident Expert
Resident Expert

@toolcubed wrote:

Hello community. My Ignite XB6 gateway has been showing horrendous DOCSIS stats for the past couple of weeks. Almost all DOCSIS channels are in the -16db range and SNR at around 34db. My upstream power levels are also all elevated at 52db. Yet I have absolutely zero problems. My internet speeds are fast, stable, and consistent. My pings and jitter are consistently very low. My Ignite TV service is working perfectly fine. I don’t have any drops or disconnections either.

I rebooted the gateway but the stats remained poor. I then factory reset the gateway, and still my stats are really bad, but still no issues with internet or TV.

I called tech support. They ran a test and confirmed exactly what I’m seeing, which caused the test to fail and triggered a tech visit for tomorrow morning.

This is really odd. With these DOCSIS stats, I would expect problems but I don’t have any whatsoever.

Could the XB6 be reporting false readings?


Really hard to say what's going on.  With those stats, you are still within the operating limits, albeit right at the edge... but I'm very curious to know what changed.  Could be a problem with the local node.  Perhaps they moved your connection to a different tap.  I don't think that those are false readings from your modem.  The tech will have to investigate.  Probably the first thing that they will do is check your line with their test equipment and go from there.

 

Hope this gets resolved soon!

Re: XB6 gateway shows incorrect (really bad) DOCSIS stats

toolcubed
I'm a senior contributor

Maintenance crew showed up yesterday (Tuesday), ran a bunch of tests and confirmed the problem is with the coax cable running between the node across my street and the tap/pedestal feeding my house.  A 3 year old cable...gone already!  Construction crew showed up today (Wednesday), dug, and ran a new coax cable.  DOCSIS stats are now back to normal and where they were before I reported the problem.  Have to say...I'm very impressed with how quickly and professionally this was handled.

 

Here are my stats.  Does anyone know why there's a power and SNR drop on channels 13 thru 16 (between 630MHz and 650MHz)?  Is that normal for the Rogers network?  I mean, the stats for those four channels are still good, and the QAM channels in general likely don't matter much anymore anyways since the modem is using OFDM channels, but I'm still curious.

 

IndexLock StatusFrequencySNRPower LevelModulation
Downstream
Channel Bonding Value
23
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
24
25
26
27
28
29
30
31
32
34
33
34
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
693 MHz
279 MHz
849 MHz
855 MHz
861 MHz
579 MHz
585 MHz
591 MHz
597 MHz
603 MHz
609 MHz
615 MHz
621 MHz
633 MHz
639 MHz
645 MHz
651 MHz
657 MHz
663 MHz
669 MHz
675 MHz
681 MHz
687 MHz
699 MHz
705 MHz
711 MHz
717 MHz
723 MHz
825 MHz
831 MHz
837 MHz
843 MHz
920 MHz
350000000
920000000
40.3 dB
40.1 dB
41.4 dB
41.3 dB
41.0 dB
40.9 dB
40.6 dB
40.5 dB
40.5 dB
40.5 dB
40.4 dB
39.8 dB
40.1 dB
38.7 dB
37.1 dB
37.1 dB
38.4 dB
39.5 dB
40.0 dB
40.3 dB
39.6 dB
40.2 dB
40.3 dB
40.4 dB
40.5 dB
40.5 dB
40.6 dB
40.2 dB
41.3 dB
41.2 dB
41.3 dB
41.0 dB
39.6 dB
40.1 dB
39.4 dB
3.1 dBmV
1.4 dBmV
5.5 dBmV
5.5 dBmV
5.1 dBmV
3.0 dBmV
2.7 dBmV
2.8 dBmV
2.8 dBmV
2.8 dBmV
2.6 dBmV
2.5 dBmV
2.4 dBmV
1.2 dBmV
0.4 dBmV
0.4 dBmV
1.1 dBmV
2.2 dBmV
2.7 dBmV
3.1 dBmV
3.0 dBmV
3.0 dBmV
3.2 dBmV
3.3 dBmV
3.5 dBmV
3.6 dBmV
3.5 dBmV
3.0 dBmV
5.7 dBmV
5.6 dBmV
5.3 dBmV
5.2 dBmV
3.9 dBmV
1.8 dBmV
3.8 dBmV
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
OFDM
OFDM
OFDM
IndexLock StatusFrequencySymbol RatePower LevelModulationChannel Type
Upstream
Channel Bonding Value
1
2
3
4
5
Locked
Locked
Locked
Locked
Locked
21 MHz
25 MHz
32 MHz
38 MHz
42 MHz
2560
5120
5120
5120
0
39.3 dBmV
40.8 dBmV
40.8 dBmV
40.8 dBmV
4200000.0 dBmV
QAM
QAM
QAM
QAM
OFDMA
TDMA_AND_ATDMA
ATDMA
ATDMA
ATDMA
TDMA

Re: XB6 gateway shows incorrect (really bad) DOCSIS stats

-G-
Resident Expert
Resident Expert

@toolcubed wrote:

Here are my stats.  Does anyone know why there's a power and SNR drop on channels 13 thru 16 (between 630MHz and 650MHz)?  Is that normal for the Rogers network?  I mean, the stats for those four channels are still good, and the QAM channels in general likely don't matter much anymore anyways since the modem is using OFDM channels, but I'm still curious.

This is typical.  I also see variances in Power Level and SNR but also see higher/lower output on different channels than you do.  There's no simple explanation but it is partly due to the performance of the cable plant and also partly due to how they have their equipment fine-tuned in order to optimize performance across all homes in the area.

 

The important things are that the Power Level and SNR are within spec across all channels, that noise is not problematic, that Uncorrectable Codewords errors are as close to zero as possible, and that your DOCSIS 3.1 channel(s) are performing well.

Re: XB6 gateway shows incorrect (really bad) DOCSIS stats

toolcubed
I'm a senior contributor
Cool. Thanks! Uncorrectable code words are 0 across the board and zero noise according to all techs I’ve spoken with. So all good once again 🙂

Re: XB6 gateway shows incorrect (really bad) DOCSIS stats

@toolcubed the interesting item to note is the presence of 2 downstream OFDM channels.  Thats not very common these days, but, I'd expect to see that occur more often.  I'd expect very good downstream performance given that you have two OFDM channels running.  And .... you also have an OFDMA upstream channel running.  I wouldn't expect a huge gain out of that, but, no one really knows except for the network engineers.  

 

The variation in the signal levels is typical.  Its all dependent on the signal slopes set at the neighbourhood node, the condition of the cabling all the way to the modem and the condition of all of the connectors along that path.  Given that you appear to have a very short run from the local tap to the neighbourhood node, the only problem that I'd expect to see are signal levels that are too high across the board, but, yours look ok.  The signal variation is a little higher than I'd expect, but, its not terrible.

Re: XB6 gateway shows incorrect (really bad) DOCSIS stats

toolcubed
I'm a senior contributor

@Datalinkthanks. Downstream performance has always been good. I’m only on the 150Mbps plan but consistently get 300. When I was on legacy digital with a CODA modem, I would consistently get over 500 on the same 150 plan. The switch to Ignite and XB6 seemed to hard cap my over provisioned speed to 300.  Latency and jitter are also consistently very low. This neighbourhood has multiple nodes, so all runs from nodes to taps are short. There are at least 8 nodes. We went thru a massive segmentation and network uplift project three years ago.

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