VDSL Performance & Tuning

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298 posts

Ultimate Geek

#882737 22-Aug-2013 13:12

Paul1977: OK, over a million FEC errors in 15 minutes... that can't possibly be normal???

No that doesn't sound normal to me. Sounds like packet loss? Heavy packet loss at that too. have you tried Teamspeak 3 etc? or www.pingtest.net

When logged onto Teamspeak TS3 will give you live feeds of your connection and tell you if you had packet loss speeds etc.

Paul1977

5039 posts

Uber Geek

#882753 22-Aug-2013 13:30

Dairusire:

No that doesn't sound normal to me. Sounds like packet loss? Heavy packet loss at that too. have you tried Teamspeak 3 etc? or www.pingtest.net

When logged onto Teamspeak TS3 will give you live feeds of your connection and tell you if you had packet loss speeds etc.

This is what i get from pingtest.net

Paul1977

5039 posts

Uber Geek

#882767 22-Aug-2013 13:49

stevehodge:

FEC errors are nothing to worry about and we have seen numbers that high before.

Sorry, didn't see that comment. I just hadn't seen anyone else with numbers even remotely that high before. You say you seen numbers that high before, was that on people on DLM1 who are getting nice low latency?

stevehodge

393 posts

Ultimate Geek

#882772 22-Aug-2013 14:02

smac: So with no apparent latency, does that mean I'm straight on DLM1?

Don't really know what to make of the attenuation - on ADSL with my old TP-LINK modem it used to hover around 8.5-9. Then switched to Fritzy (still ADSL) and it reported 4. Now VDSL and it reports 7. Distance? No idea, depends on the cable route.

Yes, looks like DLM-1.

Your attenuation change is consistent on the Fritz. Mine went from 2db on ADSL to 4-5db on VDSL. The difference is due to the higher frequencies that VDSL use (high frequencies attenuate faster with distance). Not sure why the TP-Link was so different.

stevehodge

393 posts

Ultimate Geek

#882775 22-Aug-2013 14:03

Paul1977:
stevehodge:

FEC errors are nothing to worry about and we have seen numbers that high before.

Sorry, didn't see that comment. I just hadn't seen anyone else with numbers even remotely that high before. You say you seen numbers that high before, was that on people on DLM1 who are getting nice low latency?

Yep. See this comment, for example: http://www.geekzone.co.nz/forums.asp?forumid=90&topicid=105744&page_no=40#713722
It's certainly not common, but it's not something that has apparently caused issues in the past.

When you change your wiring you should get Snap to do a DLM reset.

Paul1977

5039 posts

Uber Geek

#882820 22-Aug-2013 15:13

stevehodge:

Yep. See this comment, for example: http://www.geekzone.co.nz/forums.asp?forumid=90&topicid=105744&page_no=40#713722
It's certainly not common, but it's not something that has apparently caused issues in the past.

When you change your wiring you should get Snap to do a DLM reset.

Interesting, I read a little further in that section of the thread and there was discussion on whether it was a good idea to set the Fritz to Max Stability for the first 10 days after a DLM reset, and then slowly crank it up. Do you think this is a good idea? I'm happy to lose a few Mb/s if it means better latency.

In fact being that I am close to the cabinet, by setting the Fritz to max stability am I more likely to get a 17a due to fewer CRCs etc - and thus greatly increase the throughput anyway? I.e. will sacrificing throughput on 8b give me a greater chance to get 17a?

seatil

40 posts

Geek

#882829 22-Aug-2013 15:32

Paul1977: Interesting, I read a little further in that section of the thread and there was discussion on whether it was a good idea to set the Fritz to Max Stability for the first 10 days after a DLM reset, and then slowly crank it up. Do you think this is a good idea? I'm happy to lose a few Mb/s if it means better latency.

In fact being that I am close to the cabinet, by setting the Fritz to max stability am I more likely to get a 17a due to fewer CRCs etc - and thus greatly increase the throughput anyway? I.e. will sacrificing throughput on 8b give me a greater chance to get 17a?

You say you're 60m line length from the cabinet. However 8dB attenuation seems high for such a short run. Either the run is longer than you think it is, or something is causing the attenuation to be higher than it should be.

You've got a dip in your spectrum graph around the 200 mark. I'm absolutely not an expert on this stuff, but it doesn't Look Right to me.

You also mentioned that 20m of the cable run to your DSL modem is the "existing" cable. What grade of cable is this?

The intended signal-to-noise ratio setting increases the downstream SNRM target value. In doing so will decrease your line speed and give the line much more wiggle room before it falls over due to line condition changes. You may see a reduced error rate, but the default settings (12dB) are already very conservative. This would be more by way of a band-aid than anything else, but you may be happy with one. :-)

If you decide to fiddle with ANY of those settings I strongly recommend ensuring that the DSL line is DISCONNECTED from your Fritz box when you click Apply. If you are running the latest firmware (05.51) and don't disconnect your line, you may encounter the issue where the line will refuse to resync afterwards. (The cure for this is to disconnect the Fritz box from the phone line for an extended period - I found 10 minutes not enough, but 50 minutes were enough - and then to reconnect it.) Once the settings have been applied you can go ahead and plug the line back in again.

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stevehodge

393 posts

Ultimate Geek

#882833 22-Aug-2013 15:43

Paul1977:
stevehodge:

Yep. See this comment, for example: http://www.geekzone.co.nz/forums.asp?forumid=90&topicid=105744&page_no=40#713722
It's certainly not common, but it's not something that has apparently caused issues in the past.

When you change your wiring you should get Snap to do a DLM reset.

Interesting, I read a little further in that section of the thread and there was discussion on whether it was a good idea to set the Fritz to Max Stability for the first 10 days after a DLM reset, and then slowly crank it up. Do you think this is a good idea? I'm happy to lose a few Mb/s if it means better latency.

Putting it on max stability should maximise your chance of getting to a low latency DLM level so if latency is a big issue for you then it's probably worth a go. We do know that too many resyncs is bad for your DLM level so don't change it too often.

In fact being that I am close to the cabinet, by setting the Fritz to max stability am I more likely to get a 17a due to fewer CRCs etc - and thus greatly increase the throughput anyway? I.e. will sacrificing throughput on 8b give me a greater chance to get 17a?

We haven't seen much evidence that lower CRC errors makes it more likely that you'll get on 17a, but there have only been a handful of reports so far. Before I went to 17a my error rates were often fairly high (by the standards of the day). It's even possible that higher errors might make it more likely if DLM (assuming it is DLM that makes the decision) thinks that putting you on 17a would reduce crosstalk. Personally I think attenuation is the major factor and IIRC 8db is higher than we've seen for anyone who has gone to 17a. 8db seems a bit high if you are really only 60m from the cabinet. I estimate there's about 130m of cable between me and the cabinet and I had 4-5db. I'd try your rewiring plan to see if that makes any difference (incidentally put an RJ45 on the Fritz end rather than an RJ11 if you can, it's better for the socket on the Fritz). Do you know what your attenuation was for ADSL?

Paul1977

5039 posts

Uber Geek

#882840 22-Aug-2013 15:48

seatil:

You say you're 60m line length from the cabinet. However 8dB attenuation seems high for such a short run. Either the run is longer than you think it is, or something is causing the attenuation to be higher than it should be.

You've got a dip in your spectrum graph around the 200 mark. I'm absolutely not an expert on this stuff, but it doesn't Look Right to me.

You also mentioned that 20m of the cable run to your DSL modem is the "existing" cable. What grade of cable is this?

I based the 60m on the calculation I'd read in the first post "Receive attenuation figure and divide it by 13.81 - this will give you the distance in kilometers", but now see I didn't move the decimal point enough!

So 8 divided by 13.81 = 0.579km = 570.9m That's somewhat disheartening now! Does this rule out ever getting the elusive 17a?

The "existing cable" is whatever was running from the demarc point to the old phone jack. This predates me moving in so I don't know - but it is an old house.

Paul1977

5039 posts

Uber Geek

#882847 22-Aug-2013 15:56

stevehodge:
We haven't seen much evidence that lower CRC errors makes it more likely that you'll get on 17a, but there have only been a handful of reports so far. Before I went to 17a my error rates were often fairly high (by the standards of the day). It's even possible that higher errors might make it more likely if DLM (assuming it is DLM that makes the decision) thinks that putting you on 17a would reduce crosstalk. Personally I think attenuation is the major factor and IIRC 8db is higher than we've seen for anyone who has gone to 17a. 8db seems a bit high if you are really only 60m from the cabinet. I estimate there's about 130m of cable between me and the cabinet and I had 4-5db. I'd try your rewiring plan to see if that makes any difference (incidentally put an RJ45 on the Fritz end rather than an RJ11 if you can, it's better for the socket on the Fritz). Do you know what your attenuation was for ADSL?

I don't know what my attenuation was on ADSL, I always got really good sync speeds though 24 or 25 Mbps. Dunno if that tells you anything though. And as per my above post I had calculated my distance from the cabinet wrong, more like 600m.

I thought it was the smaller socket on the Fritz for the DSL port, I just spent $4 on a bag of RJ11s... that's money I'll never see again!

Paul1977

5039 posts

Uber Geek

#882850 22-Aug-2013 15:58

Paul1977:
So 8 divided by 13.81 = 0.579km = 570.9m

Still can't get it right, 579m

Dairusire

298 posts

Ultimate Geek

#882859 22-Aug-2013 16:05

Paul1977:
stevehodge:
We haven't seen much evidence that lower CRC errors makes it more likely that you'll get on 17a, but there have only been a handful of reports so far. Before I went to 17a my error rates were often fairly high (by the standards of the day). It's even possible that higher errors might make it more likely if DLM (assuming it is DLM that makes the decision) thinks that putting you on 17a would reduce crosstalk. Personally I think attenuation is the major factor and IIRC 8db is higher than we've seen for anyone who has gone to 17a. 8db seems a bit high if you are really only 60m from the cabinet. I estimate there's about 130m of cable between me and the cabinet and I had 4-5db. I'd try your rewiring plan to see if that makes any difference (incidentally put an RJ45 on the Fritz end rather than an RJ11 if you can, it's better for the socket on the Fritz). Do you know what your attenuation was for ADSL?

I don't know what my attenuation was on ADSL, I always got really good sync speeds though 24 or 25 Mbps. Dunno if that tells you anything though. And as per my above post I had calculated my distance from the cabinet wrong, more like 600m.

I thought it was the smaller socket on the Fritz for the DSL port, I just spent $4 on a bag of RJ11s... that's money I'll never see again!

Not to be a dick or anything, but are you sure you where syncing at 24 or 25mb/s? when on ADSL that is? What I sudgest is get Cat 6. go to demarc, and wire DIRECTLY from the demarc to your router. Done. If there are any wiring issues this will solve it.

Paul1977

5039 posts

Uber Geek

#882866 22-Aug-2013 16:14

Dairusire:
Not to be a dick or anything, but are you sure you where syncing at 24 or 25mb/s? when on ADSL that is? What I sudgest is get Cat 6. go to demarc, and wire DIRECTLY from the demarc to your router. Done. If there are any wiring issues this will solve it.

Yep, I have a friend at Telecom who had me send him screenshots to show his boss cause it was the fastest he'd seen one sync. I Didn't ever get that sort of usable throughput, downloads seemed to max at about 18 or 19 for a segmented download. But VDSL is a whole other kettle of fish I guess, but I am more than happy with the sync speed (about 45 Mb/s), it the high latency and DLM7 that annoys me.

As you say, I'll do the CAT6 this weekend and get a DLM reset Monday and see what happens.

stevehodge

393 posts

Ultimate Geek

#882911 22-Aug-2013 16:48

Paul1977:
I don't know what my attenuation was on ADSL, I always got really good sync speeds though 24 or 25 Mbps. Dunno if that tells you anything though. And as per my above post I had calculated my distance from the cabinet wrong, more like 600m.

You're getting pretty good sync speeds for VDSL too. It might be good to try to nail down exactly where the cabinet is. You can track it down using the Chorus cabinet list at http://www.chorus.co.nz/file/12279/Existing_Distribution_Cabinet_List_May_2013.xlsx. The coordinates in that file are NZ Map Grid coordinates. You can use something like http://apps.linz.govt.nz/coordinate-conversion/ to convert from NZ Map Grid to NZ Geodetic Datum 2000 which gives a latitude and longitude that can be put straight into Google maps.

I thought it was the smaller socket on the Fritz for the DSL port, I just spent $4 on a bag of RJ11s... that's money I'll never see again!

Looking at the back it's the socket on the far left. The RJ11 sockets are phone outputs. But don't worry about it, RJ11 will work so long as you get it in straight. It can damage the outside pins of the socket but you're not using them anyway.

Paul1977

5039 posts

Uber Geek

#882924 22-Aug-2013 17:04

stevehodge:

You're getting pretty good sync speeds for VDSL too. It might be good to try to nail down exactly where the cabinet is. You can track it down using the Chorus cabinet list at http://www.chorus.co.nz/file/12279/Existing_Distribution_Cabinet_List_May_2013.xlsx. The coordinates in that file are NZ Map Grid coordinates. You can use something like http://apps.linz.govt.nz/coordinate-conversion/ to convert from NZ Map Grid to NZ Geodetic Datum 2000 which gives a latitude and longitude that can be put straight into Google maps.

Looking at the back it's the socket on the far left. The RJ11 sockets are phone outputs. But don't worry about it, RJ11 will work so long as you get it in straight. It can damage the outside pins of the socket but you're not using them anyway.

Thanks I'll have a look tonight at the cabinet location. It's not problem getting some RJ45s, if I'm taking the time to do it I may as well do it properly (I just assumed the DSL input was an RJ11 like on most ADSL routers, so I didn't even think to check it).

Thanks for your help, it's very much appreciated.

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