VDSL SNR Margins

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Kayoss

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Hey guys,

So I finally got moved onto the MSAN in my area and am hoping to move onto VDSL. I noticed that my SNR margins went up from 10 (downstream) to 31, and my line attenuation went from 51 (downstream) to 14.8 (as great as this sounds, I'm less than 200m from the MSAN so 14.8 is still quite high). Interestingly, the ZyXel show my attenuation at 0.0 so I'm assuming that's just a bug.

Anyways, I went and got one of those ZyXel 1312B VDSL routers and have hooked my line up. Here's were I see a problem. My SNR margins have dropped from 31 down to 15 on this router?!? I'm still only on a 2mb profile, so I'm now worried what will happen on 20mb. Surely a SNR margin of 15 (down) on 2mb is going to drop significantly once it get's changed to 20mb?

Simple, just call telkom and ask them to bump me onto a 20/40mb profile and I'll check.. Nope, it takes 48 hours for them to make that simple change. I can't even test it. Now I don't want to wait 2 days to try out 20mb, then a further 2 days to try out 40mb, and then decide that the router is a problem..

Should I just return this router for a refund, and get myself a different VDSL router? I'm surprised that my R299 Billion has double the SNR of this thing...
 
Kayoss said:
Hey guys,

So I finally got moved onto the MSAN in my area and am hoping to move onto VDSL. I noticed that my SNR margins went up from 10 (downstream) to 31, and my line attenuation went from 51 (downstream) to 14.8 (as great as this sounds, I'm less than 200m from the MSAN so 14.8 is still quite high). Interestingly, the ZyXel show my attenuation at 0.0 so I'm assuming that's just a bug.

Anyways, I went and got one of those ZyXel 1312B VDSL routers and have hooked my line up. Here's were I see a problem. My SNR margins have dropped from 31 down to 15 on this router?!? I'm still only on a 2mb profile, so I'm now worried what will happen on 20mb. Surely a SNR margin of 15 (down) on 2mb is going to drop significantly once it get's changed to 20mb?

Simple, just call telkom and ask them to bump me onto a 20/40mb profile and I'll check.. Nope, it takes 48 hours for them to make that simple change. I can't even test it. Now I don't want to wait 2 days to try out 20mb, then a further 2 days to try out 40mb, and then decide that the router is a problem..

Should I just return this router for a refund, and get myself a different VDSL router? I'm surprised that my R299 Billion has double the SNR of this thing...
Click to expand...

No not really.
 
Which Billion router?

Those stats do seem really bad though for 2Mbit if the exchange is soo close.


My SNR drops when I use a Telkom D-Link 2750U and jumps up by quite a bit when I make use of a Billion 7300W.
My attenuation is 15.5dB and SNR (on 10Mbit line) is 24dB with the Billion and 10-16dB with the D-Link.

It comes down to chipsets and I have not done any firmware changes to the D-Link where the Billion has had changes made.
I know the D-Link 2750 comes in two chipset flavours, a Broadcom one and another one - not sure which mine has.
 
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MickeyD said:
Then your routers cannot do true SNR VDSL tests...
Click to expand...

So SNR margins on ADSL2+ are completely irrelevant in determining what the SNR margins will be on VDSL? I never thought that would make a different because, if i'm honest, I saw no difference in SNR margins when moving from G.DMT to ADSL2+.

If that's the case then I'm quite pleased and I guess I'll just have to wait and see what sort of connection I can get on VDSL. Although I am surprised that, as an ADSL2+ router, the ZyXel has such poor stats when compared to a cheap Billion..
 
PsyCLown said:
Which Billion router?

Those stats do seem really bad though for 2Mbit if the exchange is soo close.


My SNR drops when I use a Telkom D-Link 2750U and jumps up by quite a bit when I make use of a Billion 7300W.
Click to expand...

A cheap Billion 5200S.

The exchange that I was on was 2.5km away, so a line attenuation of 51 was to be expected. The MSAN that I've just been put on is a mere 200m away from me.. 14.8 is still high for 200m, but I can only assume that's because there must be 200m of rubbish copper between myself and the MSAN.

In saying that, when I use the Billion router that Telkom supplied me with, my line attenuation jumps up to 22. The difference between 14.8 and 22 is huge! That's why I'm so concerned about which VDSL router to get, because the difference between 14.8 and 22 is about 12mb/s in the max possible sync rate.
 
Wait....

Is it the attenuation which changes or the SNR?

also keep in mind that just because the exchange is 200m away doesn't mean the copper runs in a straight line.
 
Kayoss said:
So SNR margins on ADSL2+ are completely irrelevant in determining what the SNR margins will be on VDSL? I never thought that would make a different because, if i'm honest, I saw no difference in SNR margins when moving from G.DMT to ADSL2+.

If that's the case then I'm quite pleased and I guess I'll just have to wait and see what sort of connection I can get on VDSL. Although I am surprised that, as an ADSL2+ router, the ZyXel has such poor stats when compared to a cheap Billion..
Click to expand...
You can phone Telkom and ask them to do a line test to determine your max DL/UL rate and also ask them for your SNR stats.
 
PsyCLown said:
Wait....

Is it the attenuation which changes or the SNR?

also keep in mind that just because the exchange is 200m away doesn't mean the copper runs in a straight line.
Click to expand...

Both..

I have 2 Billion routers (the 5200S, and the 400G which Telkom gave me on a do package), and 1 planet router. All 3 show different SNR margins and line attenuation. SNR ranges from 15 - 31 (15 being the ZyXel), and attenuation ranges from 14.8 - 22 (although the ZyXel shows attenuation at 0.0).

All those stats remain consistent on the respective routers (maybe some fluctuation in SNR at night).

Regarding the route that the line takes, it's actually pretty straight. Via the road, I'm actually about 500m from the MSAN, but all the Telkom lines run along the golf course which borders my house. There are no Telkom lines in my area that follow the street, they are all on the golf course.. In fact, I discussed it with a Telkom techie and he said that I should be able to get Max speed on the MSAN when it gets activated.

Whilst I may be disappointing that my line attenuation is 14.8, that really is a first world problem. Most people still can't even get a 4mb line (up until now, I was one of those people), so I can't complain if I only get 35mb out of a 40mb line!
 
ive just upgraded from a 10mb to 20mb on my d-limk adsl2+ router, speeds is 1.9mb/s which is fantastic, how ever my Downstream SNR 5.1 dB and Upstream SNR 6.2 dB which are not great but i dont see any problems with my internet.

pretty happy
 
Kayoss said:
Both..

I have 2 Billion routers (the 5200S, and the 400G which Telkom gave me on a do package), and 1 planet router. All 3 show different SNR margins and line attenuation. SNR ranges from 15 - 31 (15 being the ZyXel), and attenuation ranges from 14.8 - 22 (although the ZyXel shows attenuation at 0.0).

All those stats remain consistent on the respective routers (maybe some fluctuation in SNR at night).

Regarding the route that the line takes, it's actually pretty straight. Via the road, I'm actually about 500m from the MSAN, but all the Telkom lines run along the golf course which borders my house. There are no Telkom lines in my area that follow the street, they are all on the golf course.. In fact, I discussed it with a Telkom techie and he said that I should be able to get Max speed on the MSAN when it gets activated.

Whilst I may be disappointing that my line attenuation is 14.8, that really is a first world problem. Most people still can't even get a 4mb line (up until now, I was one of those people), so I can't complain if I only get 35mb out of a 40mb line!
Click to expand...

My copper run is 1.1KM and my attenuation is 15.5dB so you won't get much more than I would be able to get. According to graphs not full 40Mbit but over 30Mbit for sure.
 
PsyCLown said:
My copper run is 1.1KM and my attenuation is 15.5dB so you won't get much more than I would be able to get. According to graphs not full 40Mbit but over 30Mbit for sure.
Click to expand...

Yeah from a line attenuation point of view, that is correct. However, I'm more concerned about m,y SNR margins than my line attenuation. I'm not sure if they can even handle 10mb based on my current margins on the ZyXEL router (14.9 [down] on 2mbs).

I spoke to Telkom yesterday afternoon and they insisted that the only way to check is by applying for 40mb, waiting 48hrs, and then see what happens (which I did).. I'm hoping that my SNR margins improve when I get swapped from ADSL2+ modulation to VDSL. If not, then I'm going to have to replace this router because the ZyXEL is clearly the issue. Only time will tell I suppose. The issue is, I have to idea which router to get if it needs replacing... I don't want the Pace router if I can't change my DNS settings (Unotelly) at a router level.
 
Have you checked for firmware upgrades? Check on the kitz forum as the zyxel firmware is horrid for their VDSL routers.

I've ordered a billion VDSL router and shall provide feedback as soo as I receive it. Same or similar chipset and with much better firmware! :D
 
PsyCLown said:
Have you checked for firmware upgrades? Check on the kitz forum as the zyxel firmware is horrid for their VDSL routers.

I've ordered a billion VDSL router and shall provide feedback as soo as I receive it. Same or similar chipset and with much better firmware! :D
Click to expand...

Thanks, will check there now! I did look on the ZyXEL site yesterday and there is no new firmware..

I wanted to order the Billion 8800NXL router but Syberatic got back to me by saying that there is no stock available from the suppliers.
 
PsyCLown said:
Have you checked for firmware upgrades? Check on the kitz forum as the zyxel firmware is horrid for their VDSL routers.

I've ordered a billion VDSL router and shall provide feedback as soo as I receive it. Same or similar chipset and with much better firmware! :D
Click to expand...

Nah, doesn't seem to be any unofficial firmware available for the ZyXel..
 
Hmm, pitty.

I know there are multiple firmwares for the VMG8324 and VMG8924 floating around. Released by Zyxel but not on the official Zyxel site.

I heard that stock of the Billion should be arriving on the 7th.
 
Ok, so I've finally been put onto a 40mb profile, and I'm rather confused by my line stats.

My line attenuation has gone even worse (23.7dB), and yet I'm syncing at 41mb/s. According to a DSL calculator, I should barely be able to sync at 20mb with such a high attenuation (and according to Telkom, I'm only 800m from the MSAN).

Additionally, the router is connecting on VDSL2 Annex B. I was under the impression that Telkom were making use of Annex A, and not Annex B.

Now I have both the ZyXEL and the Pace routers, and I can confirm that the stats are pretty consistent between the two. Same SNR (6-7dB) and same attenuation. Doing a speedtest, I can get roughly 37mbps on either router (although I can't get more than 600kbps on any download due to Afrihost capped being so poor atm).

However, I still have an orange light on my ZyXEL router for the line. I'm really not sure why.. It seems to be working smoothly, but perhaps there is some sort of fault on the line. Any Ideas?


ZyXEL.jpg
 
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