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What causes high doses of CRC errors Down at night?

danludlow
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What causes high doses of CRC errors Down at night?

Getting doses of CRC Errors DOWN at night, none at all UP. 14000 in 6 days mostly at night, almost none during the day, maybe 20.
I suspect its why DLM is holding my downlink back and why Up remains a fast connection.
Any thoughts? Could it be my ASUS DSL-AC68U router-modem behind it?
15 REPLIES
Terranova667
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Re: What causes high doses of CRC errors Down at night?

there is more signal interference during the evening than during the day,  street lamps being on more people home using appliances etc, even the atmosphere bounces Rein back to earth more during the evening than during the day.   
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Re: What causes high doses of CRC errors Down at night?

That does appear to be a feature of the Asus.
Have you seen this thread over at Kitz?
If not start towards the end of the thread and check if you need the latest firmware.
http://forum.kitz.co.uk/index.php/topic,14399.msg284815.html#msg284815
Please let us know how this goes.
wisty
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Re: What causes high doses of CRC errors Down at night?

What sort of time at night do they occur? Don't know if Routerstats will monitor your modem stats, but it can be set up to log and graph CRC errors per 15 minutes.
If it's overnight it might be AM radio interference on the wire between the cab & you - AM noise is much worse at night as signals propagate better at night. On the other hand it could be simply a factor of usage. If it all happens during the evening , could it be that you are simply streaming a lot more data packets at that time so a constant error rate ( CRC errors per 1000 packets) will show up as lots more errors.
Attached is last nights noise graph from my standard ADSLmax line. from about 18:00-06:30 the noise is very stable during daylight but gets significantly worse during the night.
fishpan
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Re: What causes high doses of CRC errors Down at night?

I had the DSL-AC68U for around 2 weeks. Updated immediately on the latest firmware and followed instructions on Kitz and Overclockers UK forums to set the ESNP setting in the firmware to "Stable". Nothing at all helped and it caused so many CRC errors (and presumably ES errors though this is not reported in the router stats) that DLM intervened and caused my line to drop from 65mbps to 55mbps and interleaved to switch on and bring my ping up from 6ms to 17ms.
Switched mine out for a Netgear D6400 and slowly line is recovering. Problem most like comes from your router. What I suggest is perhaps trying out your BT Openreach modem (if it is Huawei) and unlocking it so you can compare the stats to the Asus and see if you get a similar amount of CRC errors in a 24 hour period.
danludlow
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Re: What causes high doses of CRC errors Down at night?

Thank you fishpan, npr, and wisty, for your replies, they give me an idea, and much to think about.
fishpan, I have concerns about the ASUS, I think it's settings are reasonable, but cannot say they are right. Nowhere has a "standard" setup (even default looks flawed) and everyone who posts (very few) seem to have some differing ideas of what works. Having used some suggested settings in the past has lost me performance. if anything, the AC68U is just too adjustable and I suspect that it doesn't "speak quite the same language" as my port in the cabinet.
I have got the original Huwei BTO modem supplied, and have tried using it with the AC68U set up as just a router. It works, but performance tumbles by comparison. I have left the Huwei in place for perhaps 8 hours a couple of times (assuming that it hasn't been updated for G.INP, although it is a newish unit -a 3A, I believe). It may be that I haven't persevered long enough, but one would think software would update  within a couple of hours.
Anyway, I'm giving some thought to it all.
Thanks again, everyone.
fishpan
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Re: What causes high doses of CRC errors Down at night?

danludlow, I agree with the ASUS settings varying widely between person to person. I think the real problem is the DLM system not allowing us to tinker freely with the ASUS router without getting hit hard. You say you may not be on the latest firmware with your HG612 Huawei Openreach router, have you looked into updating it manually and even unlocking its settings so you can have a peak at the CRC, ES, FEC errors etc?
http://forum.kitz.co.uk/index.php/topic,14262.0.html - This is where you can download the latest (modified) firmware to show your stats on the Openreach Huawei modem. You ideally want the 'unlocked' or 'webgui' versions of the B030SP08 firmware which support G.INP.
http://huaweihg612hacking.files.wordpress.com/2011/11/hg612_unlock_instructions_v1-3.pdf - Guide to unlocking the Openreach router - just replace the firmware in the guide with the B030SP08 firmware above.
All in all, takes a few minutes to set up but you will be on the latest firmware which can improve ping/sync speeds and also will support G.INP if your cab is enabled. You can also telnet into the device to see the stats (shown in the guide) or use DSLstats program to automatically list everything for you.
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Re: What causes high doses of CRC errors Down at night?

It has nothing to do with DLM, which is reacting to monitored errors/resyncs reported by the DSLAMs.
The ASUS router would undoubtedly fail the OR modem conformance testing. There are a lot of people on the Asus forums that have reported issues with the DSL FTTx modem/routers on BT's network.
danludlow
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Re: What causes high doses of CRC errors Down at night?

Thanks for your reply AndyH. So you're saying that DLM does not worry about CRC errors at all? I notice that the SNR Down is 10.1, whilst Up is 6.0, when my connection was reset at the cabinet about 3 weeks ago, both were at 6.0 and speeds down were higher, I assume that's DLM? Why does it affect Down, but not up? I can only think its because there are CRC's down (14K in 6 days) but there are "Never" any up (I have not seen an up CRC in months).
If the ASUS modem fails OR testing, why is it sold as a solution and why do reviews highlight it as a modem with higher performance worth consideration? it is far from cheap. Also, if it's a software issue and it doesn't communicate with BTO equipment, why haven't ASUS already addressed this? Furthermore, with BTO and presumably PlusNet ending supply of "free" modem and router, why have cabinets that don't "gel" with other equipment?
I'm no expert by any means, but DLM seems set to restrict quickly, return to normal ultra slowly. Far too one-sided in my ignorant opinion, if it can react quickly (and it does) what is the harm in attempting to return speeds bit by bit starting 24 hours after the restriction?  To wait a week before attempting (as seems to be the case, judging by posts here and on other sites, "speed should hopefully return after about a week" is not an uncommon response).
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Re: What causes high doses of CRC errors Down at night?

Quote from: danludlow
Thanks for your reply AndyH. So you're saying that DLM does not worry about CRC errors at all? I notice that the SNR Down is 10.1, whilst Up is 6.0, when my connection was reset at the cabinet about 3 weeks ago, both were at 6.0 and speeds down were higher, I assume that's DLM? Why does it affect Down, but not up? I can only think its because there are CRC's down (14K in 6 days) but there are "Never" any up (I have not seen an up CRC in months).

DLM looks are three things - ES/SES and retrains.
Quote from: danludlow
If the ASUS modem fails OR testing, why is it sold as a solution and why do reviews highlight it as a modem with higher performance worth consideration? it is far from cheap. Also, if it's a software issue and it doesn't communicate with BTO equipment, why haven't ASUS already addressed this? Furthermore, with BTO and presumably PlusNet ending supply of "free" modem and router, why have cabinets that don't "gel" with other equipment?

The problem is more that router/modem manufacturers are producing their devices for global markets - but each country has different network setups. Compared to ADSL2/2+, VDSL2 uses higher frequencies and is a lot more sensitive.
The process with Openreach is that an ISP can submit a modem for conformance testing. It's a lengthy process and it's my understanding that most manufacturers have to tweak and update their firmware to make the router/modems pass all the tests.
I can tell you immediately that there are certain features that end users can control on Asus DSL-x modem/routers which would cause a fail under Openreach's conformity testing. In some countries, this might be useful features but in the UK they can cause issues to other lines on the same DSLAM.
Asus routers aren't cheap, but they are good quality. I think the problem is more the chipset they use for their modems (Trendchip) are not as good as the likes as Broadcom or Lantiq.
Quote from: danludlow
I'm no expert by any means, but DLM seems set to restrict quickly, return to normal ultra slowly. Far too one-sided in my ignorant opinion, if it can react quickly (and it does) what is the harm in attempting to return speeds bit by bit starting 24 hours after the restriction?  To wait a week before attempting (as seems to be the case, judging by posts here and on other sites, "speed should hopefully return after about a week" is not an uncommon response).

Most people blame DLM - but all it is doing is reacting to the information that is sent to it on a daily basis.
Lines are rate adaptive, so they will go as fast as they can to meet the target SNr of 6dB. For the first 48 hours after a new line is installed, it's on an open profile (i.e. DLM is doing nothing) but not every line will sync at 80/20Mbps.
DLM is only restricting a sync speed if someone has their line banded and it is synced at the upper end of the banded profile. This doesn't happen too often though.
In terms of the reactiveness of DLM to make positive changes, it's been designed to act on the side of caution - perhaps too much caution. It does prefer stability over speed, as this is what most end users want. The introduction of retransmission (aside from the ECI issues...) has further reduced errors and given most people a speed increase.
danludlow
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Re: What causes high doses of CRC errors Down at night?

Thanks for your comprehensive reply AndyH, much appreciated.
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Re: What causes high doses of CRC errors Down at night?

In the not too distant future, we will see ISPs disclosing which modems (as long as they agree to this) they have submitted for testing and which have passed.
AshPowell
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Re: What causes high doses of CRC errors Down at night?

Regarding Asus DSL-AC68U Settings, Over the last few days I've tried a few variations and this one so far is solid, Only 2 CRC down errors in 8 hours. Worth a try...
danludlow
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Re: What causes high doses of CRC errors Down at night?

Thanks for your reply AshPowell, and taking the trouble to post a screen shot of your settings, much appreciated.
Well worth a try!!
I have just reset my settings to these and look forward to seeing what the results are. Minutes in only, far too early to judge, nothing detrimental noticed, and down speed seems a tad faster.
Fingers crossed!!!
AshPowell
Grafter
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Re: What causes high doses of CRC errors Down at night?

no problem, if you're still getting high crc just increase the stability adjustment setting. If it affects your speed too much you can set Power control to -2db or -3db and itll push it back up a bit (may give more errors though).. just about getting a balance