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Author Topic: Errors and Sync speed  (Read 2806 times)

xreyuk

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Errors and Sync speed
« on: March 11, 2012, 09:24:56 PM »

Hi guys,

Just a quick question.

With regards to to ADSL, is it better to have a slightly higher sync speed, and clock up a few errors, compared to having a lower sync speed with no errors?

For example:

I am sync'd at 21Mb, with no errors.

I fiddle with SNR, and sync at 22Mb, but start clocking up a few errors.

Is it better to stay at 22Mb or go back to 21Mb? I know it depends on the amount of errors, bu is there a number I should be aiming to keep errors lower than?
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burakkucat

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Re: Errors and Sync speed
« Reply #1 on: March 11, 2012, 11:42:50 PM »

My personal opinion is (and that is as someone who achieves ~ 5 Mbps DS sync) that as the difference between a DS sync of 21 Mbps & 22 Mbps is not that great (all right, it's ~ 4.75%), why bother "pushing the line" and clocking up errors?

In other words, I would be content with a 21 Mbps DS sync without any errors rather than a 22 Mbps DS sync with some errors.  :)
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roseway

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Re: Errors and Sync speed
« Reply #2 on: March 12, 2012, 07:21:06 AM »

I agree with b*cat. I suppose that the literal answer to the question which was asked is that 22 is more then 21, but the practical difference is close to zero, and if the error rate becomes very high it could reduce the throughput or even make the connection unstable.
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xreyuk

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Re: Errors and Sync speed
« Reply #3 on: March 14, 2012, 12:09:47 AM »

I had a look at my stats tonight and this is the info...

Total time = 1 days 2 hours 46 min 45 sec
FEC:            0               0
CRC:            69549           0
ES:             6749            189
SES:            1218            64
UAS:            112             112
LOS:            0               0
LOF:            0               0

That is synced at 22.5Mb and it's had complete uptime since last resync. Would that amount of errors in that time mean it's actually bad for me to be at the sync speed I'm at, and I'd benefit from lowering it?
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burakkucat

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Re: Errors and Sync speed
« Reply #4 on: March 14, 2012, 01:40:08 AM »

Let me ask you a couple of questions.

Do you notice any real, practical difference when you are sync'd at 22.5 Mbps DS from when you are sync'd at 21 Mbps DS?
If yes, then please tell. If no, could it just be that you are chasing a bigger number for the sake of it?  ::)

We now have sight of 24 hours of statistics, with errors present. For completeness, you should now raise your target SNRM by one increment and collect another 24 hours of statistics. It will be interesting to compare both sets.  :-\

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kitz

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Re: Errors and Sync speed
« Reply #5 on: March 14, 2012, 06:40:47 PM »

You dont say what SNRM you are using between the sync speeds.
TBH, like the others say I dont think you'll notice any difference between the 2 speeds when on the fly, you'd have to be more or less downloading constantly and/or huge files to notice the difference.

Remember that when you have errors this is when data has been lost and had to be transmitted..  so in actual fact you wont be getting the sync speed in real time speeds.

For example I could perhaps push my downstream up to get another 1Mb sync speed, but I dont do so.  Once my SNRM gets too low then everything starts to crawl because so much data has to be retransmitted.  Even browsing can become hard and slow.

As Bcat says you could try taking it up in little stages to try find a happy medium, its all about knowing your line and what is best.
You could also try using routerstats to record your SNRM and see how much it fluctuates over the course of the day, which will give you a base line to work on.  Depending on the router too as some routers seem to work better than others at a lower SNRM.

Finally it should be said..  If you are on an ISP such as Be* (which you appear to be from your IP) then it doesnt matter too much about messing around and taking your SNRM too low as they allow you to set certain profiles from within their CP.
However if you are with some BTw based ISP's then you could find automatic profiles kicking in.
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jeffbb

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Re: Errors and Sync speed
« Reply #6 on: March 14, 2012, 07:53:58 PM »

Hi
Funnily enough I have recently decided to reduce my target SNR margin from 9db to 6 db . I am on 8 max with the 9db margin my average CRC/ES was about 1 to 1.5 per DAY .with a synch rate of about 7300 giving an IP profile of 6000Kbps occasionally 6500Kbps if the synch rate was a little higher . Choosing my time carefully  I decided to reduce the target to 6db .This has given me a synch rate of 8064 Kbps with a profile of 7000 Kbps . This is a gain of 1000Kbps  . The error rate has increased 200 fold   but that is still < 300 per DAY . :).
 I am not sure that I really notice the difference in actual performance (speed testers do show the improvement)even though it is nearly 17%  . I will leave it as it is as the errors are still very low compared to many .
Regards Jeff
 
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kitz

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Re: Errors and Sync speed
« Reply #7 on: March 14, 2012, 08:00:45 PM »

>>  rate has increased 200 fold   but that is still < 300 per DAY

Should be perfectly fine then.. it really is about knowing your line, hence why I suggested monitoring with routerstats to see what goes on.
   
My SNR doesnt normally fluctuate that much over the course of the day, therefore once I go below a certain SNRM I will get 1000's of errors that just continue to rack up.
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Ottersnose

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Re: Errors and Sync speed
« Reply #8 on: March 15, 2012, 11:49:54 AM »

I guess my question is what do you use the circuit for?

If you are simply surfing the web and emailing you would notice no difference unless you are a robot.
If your streaming HD video it could make a slight difference I guess?
If you need to download huge files it may save you a minute or two a week! 
If your a gaming guru then the error free connection is the best.
The same could be said if your running VOIP applications.

Overall error free would always be my personal choice.

 
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burakkucat

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Re: Errors and Sync speed
« Reply #9 on: March 15, 2012, 05:53:21 PM »

Quote
Overall error free would always be my personal choice.

 :thumbs:
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xreyuk

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Re: Errors and Sync speed
« Reply #10 on: March 16, 2012, 12:13:04 AM »

Cheers guys.

Is there an amount of errors in a 24 hour period that you guys would consider acceptable?

The problem I have is, I do constant downloding of things, and obviously due to the higher download speed, my download client tells me I'm getting faster speeds, but that's obviously not taking into account re-transmissions.

I also want to point out,  I only used those speeds as an example, it's not what I'm using!
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burakkucat

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Re: Errors and Sync speed
« Reply #11 on: March 16, 2012, 12:55:09 AM »

To be honest, it is really a case of "suck it and see".  ;)

As long as you appreciate the concept of what is taking place, trial and error (pun intended) will eventually provide you with the optimum setting.
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