(Two) Zyxel p870h modems cannot establish VDSL line sync, Energy Imports modem works fine

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sbiddle

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#1024160 12-Apr-2014 20:51

To be completely honest I don't think you have a problem - you're outside the initial 10.8dB spec requirement for VDSL2 and your attenuation figure shows that. Just be grateful you actually have a connection that is working.

You haven't yet answered if you're within the VDSL2 coverage area according to the Chorus maps - I'd pick you aren't. If you are then maybe you could have a faulty MPF pair, but I think the chances of this are pretty slim.

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#1024180 12-Apr-2014 21:13

sbiddle: To be completely honest I don't think you have a problem - you're outside the initial 10.8dB spec requirement for VDSL2 and your attenuation figure shows that. Just be grateful you actually have a connection that is working.

You haven't yet answered if you're within the VDSL2 coverage area according to the Chorus maps - I'd pick you aren't. If you are then maybe you could have a faulty MPF pair, but I think the chances of this are pretty slim.

I believe I am within the coverage area, I can pm you my address if you know a better way to check; I used the 'fibre rollout map' on Chorus' website to check my availability and I am within a "> 20Mbps Broadband" shaded area. I have no scheduled rollout date for FTTH unfortunately. Both Telecom and Slingshot confirmed my eligibility for VDSL2 when I enquired about it, but when you type my address into those 'address checkers' on ISP websites it doesn't usually give VDSL2 as an option. Slingshot's website says "An error occurred when searching for this address. Please contact Slingshot for more information." while Telecom's website says I am eligible for VDSL2 at 18-19Mbps.

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#1024183 12-Apr-2014 21:17

I think I've been given rights to post links now, so here is the map I used: http://www.chorus.co.nz/fibre-rollout-map

The colour scheme is a bit difficult to see but I am definitely in a >20Mbps area, though near the edge of it. I used another similar map a year or so ago to check my eligibility and back then the map specifically stated what types of services were available - I was in the VDSL2 area at the time, but back then Slingshot and Telecom didn't offer VDSL2.

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#1024276 13-Apr-2014 08:54

If you're right on the edge of a 20Mbps zone it's pretty much proof there is pretty much nothing wrong with your connection.

To be honest just be thankful you have VDSL2, accept the speeds you have aren't going to get any better, and enjoy the 10Mbps upstream.

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#1024415 13-Apr-2014 15:56

Yes, they are not twisted pairs, but there are four of them in total bonded together in a black outer jacket.

That isn't 'Tru-rip'. Tru-rip is a single pair, untwisted, 'flat' cable and is rather old.

What you have is an 049 (said "Oh Fotry Nine") and the pairs are twisted, just not as tight as a Cat5e/Cat6 cable.

Your "rubbish" speeds do suggest you are just a long way away. And while your download hasn't improved massively your upload has - something I wish I had on my home connection.

geostuff

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#1024508 13-Apr-2014 19:53

chevrolux:
Yes, they are not twisted pairs, but there are four of them in total bonded together in a black outer jacket.

That isn't 'Tru-rip'. Tru-rip is a single pair, untwisted, 'flat' cable and is rather old.

What you have is an 049 (said "Oh Fotry Nine") and the pairs are twisted, just not as tight as a Cat5e/Cat6 cable.

Your "rubbish" speeds do suggest you are just a long way away. And while your download hasn't improved massively your upload has - something I wish I had on my home connection.

Ah, that's good to know! Thanks for clarifying. If I already have an 049 cable, do you reckon I'd see a 'worthwhile' performance increase from a cat6a or similar outdoor cable?

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sbiddle

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#1024515 13-Apr-2014 20:11

geostuff:
chevrolux:
Yes, they are not twisted pairs, but there are four of them in total bonded together in a black outer jacket.

That isn't 'Tru-rip'. Tru-rip is a single pair, untwisted, 'flat' cable and is rather old.

What you have is an 049 (said "Oh Fotry Nine") and the pairs are twisted, just not as tight as a Cat5e/Cat6 cable.

Your "rubbish" speeds do suggest you are just a long way away. And while your download hasn't improved massively your upload has - something I wish I had on my home connection.

Ah, that's good to know! Thanks for clarifying. If I already have an 049 cable, do you reckon I'd see a 'worthwhile' performance increase from a cat6a or similar outdoor cable?

None whatsoever.

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#1025016 14-Apr-2014 17:09

Regarding line rate... 19dB attenuation is about 1.5km line distance

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#1025018 14-Apr-2014 17:14

Anyway your original question was why are the Zyxel's not working...

Probably chipset incompatibility with the line cards in use. Chorus mostly uses IKANOS line cards but there are other brands too, eg Broadcom. If you took those to a friends place who has VDSL2 on a different cabinet/exchange they'd probably work, actually that would be a good test to determine whether it's just the line card you're connected too or a problem with the actual model.

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#1025029 14-Apr-2014 17:32

Ragnor: Anyway your original question was why are the Zyxel's not working...

Probably chipset incompatibility with the line cards in use. Chorus mostly uses IKANOS line cards but there are other brands too, eg Broadcom. If you took those to a friends place connected to a different cabinet/exchange they'd probably work.

broadcoms are generally exchange, where as ikanos are cabinet.

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#1025035 14-Apr-2014 17:41

Yeah from his original post is sounds like he's on an exchange not a cabinet.

The ZyXEL P870H-51a v2 modem he was having trouble actually uses a broadcom chipset (I think) so quite weird for broadcom chipset device to not work on broadcom line card.

Could just be this device is quite sensitive to distance.

Might be interesting to try a Draytek Vigor 130 on his line (Infineon chipset).

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#1027692 19-Apr-2014 11:58

Here's an update folks,

I sent back both Zyxel modems and bought a Technicolor TG589vn v2 off trademe for less than half the price and boom! it works instantly. 10 minutes of fluffing around to get the configuration the way I like it with the modem bridged on a separate subnet to the LAN and she's away with a 21.5/10Mbps connection speed and similar line attenuation/SNR margins. I used speedtest.net to confirm the higher throughput, and it is definitely a whole lot better:

Technicolor modem stats are as follows:

Link Information

Uptime: 0 days, 0:20:50
DSL Type: ITU-T G.993.2
Bandwidth (Up/Down) [kbps/kbps]: 10,073 / 21,521
Data Transferred (Sent/Received) [B/B]: 0 / 0
Output Power (Up/Down) [dBm]: 7.8 / 13.5
Line Attenuation (Up/Down) [dB]: 40.6 / 19.1
SN Margin (Up/Down) [dB]: 11.9 / 12.2
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IKNS
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 12 / 0
FEC Errors (Up/Down): 0 / 79
CRC Errors (Up/Down): 0 / 16
HEC Errors (Up/Down): 0 / 72

Ragnor: Yeah from his original post is sounds like he's on an exchange not a cabinet.

The ZyXEL P870H-51a v2 modem he was having trouble actually uses a broadcom chipset (I think) so quite weird for broadcom chipset device to not work on broadcom line card.

Could just be this device is quite sensitive to distance.

Might be interesting to try a Draytek Vigor 130 on his line (Infineon chipset).

@Ragnor, it seems (from what the Technicolor modem is reporting) as though there is an IKANOS card at the exchange like you initially guessed. Perhaps - like you suggested - there is some level of incompatibility between the broadcom chipset in the Zyxel and the IKANOS chipset at the exchange, which is exacerbated somehow by my high line attenuation. I suppose we'll never know...

Again heartfelt thanks to all who contributed to the discussion! I would still be stuck with the Zyxel and a 16Mbps line speed without you guys!

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#1027707 19-Apr-2014 13:23

Hi, you have to appreciate that the way the modem pump responds to certain conditions is not set in stone, in a past life I worked for a Canadian company developing DSL pumps, that code was for the TI chipsets that now belongs to Nokia/Siemens albeit it was DSL1 code, so have some understanding of how these things work at a very low level. Each pump design can have its own strategies of dealing with the inbound spectrum that it has to deal with, its not uncommon that when you get to the edges of the useable environment one end heads off in a different direction to the other and the two never have a chance of merging on a solution. The answer is that while you are in the comfort zone that the intended system was designed to work in you will get pretty predictable outcomes, push the envelope and you have no comeback.

Cyril

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