VDSL Performance & Tuning

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Lizard Networks

#1231321 4-Feb-2015 19:11

at 20.8dB almost certainly 8b, he asked of his DLM profile though

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Athlonite

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#1231345 4-Feb-2015 19:57

I thought that is what 8b was is it not the DLM profile

Jase2985

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#1231363 4-Feb-2015 20:12

Athlonite: I thought that is what 8b was is it not the DLM profile

8b is the vdsl profile, DLM has its own profile system too which dictates latancy

The dynamic line management system changes the vdsl profile (8b or 17a) and the DLM profile (DLM-1 to DLM-8) to get you the best comprise between speed latency and errors on your line.

nzgeek

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#1231455 5-Feb-2015 00:03

Athlonite: If you look at the very first page that opens when you log in to your router it will tell you there which profile your on like me you look to be on 8b

At 20.7dB attenuation, (s)he is pretty much guaranteed to be on an 8b VDSL profile (bandplan). You'll only get onto a 17a if you're less than 300m from the cabinet/exchange, as 17a uses higher frequencies and these degrade faster with distance. For 300m, you're looking at 9-10dB attenuation on 8b.

The question was probably more aimed at DLM profiles, which are based on latency and INP. The optimal target is DLM-1, which has 1ms latency and 0 INP. Anything lower and you're liking at 8ms or 16ms latency, which shows on your ping times.

Interesting side-note: I recently heard a Chorus installer refer to DLM as DTLM. He said this a couple of times. I assumed that he'd just got the name wrong. Does anyone know why he might have called it DTLM?

hio77

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#1231456 5-Feb-2015 00:09

nzgeek:
Athlonite: If you look at the very first page that opens when you log in to your router it will tell you there which profile your on like me you look to be on 8b

At 20.7dB attenuation, (s)he is pretty much guaranteed to be on an 8b VDSL profile (bandplan). You'll only get onto a 17a if you're less than 300m from the cabinet/exchange, as 17a uses higher frequencies and these degrade faster with distance. For 300m, you're looking at 9-10dB attenuation on 8b.

The question was probably more aimed at DLM profiles, which are based on latency and INP. The optimal target is DLM-1, which has 1ms latency and 0 INP. Anything lower and you're liking at 8ms or 16ms latency, which shows on your ping times.

Interesting side-note: I recently heard a Chorus installer refer to DLM as DTLM. He said this a couple of times. I assumed that he'd just got the name wrong. Does anyone know why he might have called it DTLM?

dont see any white papers on DTLM for VDSL, or DSL for that matter.

What i do find references to what ild assume is just another name for the E1s used in PCM, Digital Transmission Line Module - a 2 Mbps interface.

is it possible the chorus installer was actually saying DLM and somehow tossing a T in there, or having an off day?

on the note of 17a, there have been odd situations where these limits haven't been negated, but ild count that as a nullissue considering how it generally comes about.

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Any comments made are personal opinion and do not reflect directly on the position my current or past employers may have.

nzgeek

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#1231457 5-Feb-2015 00:24

hio77:
nzgeek: Interesting side-note: I recently heard a Chorus installer refer to DLM as DTLM. He said this a couple of times. I assumed that he'd just got the name wrong. Does anyone know why he might have called it DTLM?

dont see any white papers on DTLM for VDSL, or DSL for that matter.

What i do find references to what ild assume is just another name for the E1s, Digital Transmission Line Module - a 2 Mbps interface.

is it possible the chorus installer was actually saying DLM and somehow tossing a T in there, or having an off day?

I suspect that it was just an off day for the poor guy. It was a Friday afternoon VDSL install in an office in the Auckland CBD, and it took him an hour to do the install. Most of that was running between the 3rd floor comms room and wherever the wiring entered the building, trying to find a decent connection.

The good news is that he managed to get a 24/8 connection in the end, and that's before DLM training. That's better than I'd expected. I know of an office a few floors up that's stuck on ADSL, poor souls.

Athlonite

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#1232099 6-Feb-2015 07:15

Jase2985:
Athlonite: I thought that is what 8b was is it not the DLM profile

8b is the vdsl profile, DLM has its own profile system too which dictates latancy

The dynamic line management system changes the vdsl profile (8b or 17a) and the DLM profile (DLM-1 to DLM-8) to get you the best comprise between speed latency and errors on your line.

Ah right got it now

so the best you can hope for outside the 300mtr mark is 8b and DLM-1

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Jase2985

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#1232118 6-Feb-2015 09:21

no you could get 17a but you would need to have a perfect line

distance plays a part but ultimately its attenuation that dictates the speed profile

zenourn

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#1235770 11-Feb-2015 16:16

I've had VDSL installed today out in rural Canterbury (initial estimate was 0.5-1.5 km from exchange but turned out to be ~2 km from the exchange once cable path and driveway taken into account). Chorus tech was amazed that could even get a connection this far from the exchange and said he had never had a VDSL connection work beyond 1 km before. The modem reports attenuation of 28 dB which matches closely with a distance of ~2 km. I've got a DrayTek Vigor 130 bridged to a MikroTik router and are are getting 14.8 Mbps down and 0.5 Mbps up.

Given the actual distance I assume it is likely better to have the port changed to ADSL2+ as it will likely still give ~15 Mbps down but a slightly better upload?

TechSol

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#1251334 4-Mar-2015 20:44

Is there any way to get more stats out of the Spark Huawei HG630b?

Had one installed nearly 3 days ago.... 3 days of uptime, only 49 crc errors in that time. Attenuation of 8.1db and cabinet is around 260meters from me.

Doesn't look like anything had changed.... definitely not on DLM-1 and speed is 33/10 at the moment.....

Would be great if I could find out more, as the modem stats page is pretty basic:

Line standard VDSL2
Downstream line rate (kbit/s) 36005
Upstream line rate (kbit/s) 10354
Downstream SNR (dB) 12.1
Upstream SNR (dB) 17.9
Downstream line attenuation (dB) 8.1
Upstream line attenuation (dB) 15
Downstream output power (dBmV) 13.5
Upstream output power (dBmV) -11.9
Downstream CRC 49
Upstream CRC 0
Downstream FEC 69050
Upstream FEC 7819

Jase2985

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#1251357 4-Mar-2015 21:22

you are getting about 15 FEC errors a minute, means not a great quality line.

whats your ping? i dont think those modems display the INP or delay so you can only really use ping to give a rough indication on what DLM profile you are on

TechSol

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#1251358 4-Mar-2015 21:22

wow ... just realised this is in the snap forum... apologies if this shouldn't be in here, but I think there is a lot of non-snap related stuff

TechSol

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#1251360 4-Mar-2015 21:24

Jase2985: you are getting about 15 FEC errors a minute, means not a great quality line.

whats your ping? i dont think those modems display the INP or delay so you can only really use ping to give a rough indication on what DLM profile you are on

Ping is 23 or so MS to a site like nzherald, so I understand that is not DLM-1

I thought the FEC errors were not a huge worry and that CRC was a more important stat?

Jase2985

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#1251361 4-Mar-2015 21:30

this started as a snap VDSL thread but kinda morphed into the be all and end all VDSL thread for all ISP's

whats the ping to your nearest speed test server, testing to a website isnt the most accurate
i get about 5-6ms to the spark speedtest server in auckland, but 335ms to the NZHerald site, go figure, crappy routing on NZHeralds part

FEC errors are not a huge worry untill the number per minute/second get up there

TechSol

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#1251367 4-Mar-2015 21:35

It's about 23 ms to sparks speed test server

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