Linestats after second line enabled...

Right, I've had a line on FTTC since the beginning of last year with pretty good stats. The other line in the house on the same dropwire was on ADSL2.

Today the ADSL2 line got switched to FTTC and I expected a bit of worsening in stats and speed however I was wrong.

Previously the stats were...

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 33812 Kbps, Downstream rate = 106000 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 79999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 13.2 15.7
Attn(dB): 8.9 0.0
Pwr(dBm): 12.8 -9.9

After the second line has been activated the stats have dropped to

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 27121 Kbps, Downstream rate = 86144 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 79999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 7.8 11.2
Attn(dB): 8.9 0.0
Pwr(dBm): 12.8 -9.9

Is that expected? I mean the two lines are only together from the pole to the house, ~40 metres or so...would that have such an effect on it? :|

In reply to a post by NBK:

... I expected a bit of worsening in stats and speed however I was wrong.

Don't you mean "... speed and I was right"?

Re the lines being together, they may be so all the way from the cabinet.

Have you got the stats for the second line?

In reply to a post by RobertoS:

In reply to a post by NBK:

... I expected a bit of worsening in stats and speed however I was wrong.

Don't you mean "... speed and I was right"?

Re the lines being together, they may be so all the way from the cabinet.

Have you got the stats for the second line?

I wasn't wrong, it's more than a bit
The second line is using a smart hub and it reports...
Maximum data rate: 19999 / 80809
Noise margin: 15.4 / 6.7
Line attenuation: 9.6
Signal attenuation is blank

The assumption is that it is a large worsening rather than a bit. The max attainable has gone down by about 20%. However, the actual sync speed has not been affected.

In reality the service hasn't changed at all. I don't entirely trust the routers calculations of max attainable and how the lines are managed.

Post deleted by RobertoS

Edited by RobertoS (Fri 09-Sep-16 14:59:25)

From the original post:

I expected a bit of worsening

I'd said I expected a bit of worsening however i got a lot more than a bit

Just for a laugh I turned off the router on the other line and my linestats went to...

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 34292 Kbps, Downstream rate = 107528 Kbps
Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 79999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 13.6 19.9
Attn(dB): 8.9 0.0
Pwr(dBm): 12.8 -9.9

In reply to a post by NBK:

Today the ADSL2 line got switched to FTTC and I expected a bit of worsening in stats and speed however I was wrong.

That's right, your speed on Line1 is unchanged and much improved on Line2.

The lines, as already mentioned, could be together all the way from the cabinet (and possibly exchange). With ADSL there was only cross talk at the low end however, with two VDSL lines the cross talk will be all the way up to 17MHz and could affect every tone.

Have you been unlucky? Yes.

Is there anything you can do? No - apart from turn off one line!

Will a complaint be entertained? No.


It might be worth turning off each modem in turn and then disconnecting it. Wait say 15 minutes and then recheck the line stats on the line remaining active. Does your old line go back to the former levels, or better?

You posted this as I replied to your original post. It certainly seems to confirm that it is only cross talk causing the degradation.



What are the new line stats? Both with and without the original line running.

They're on the same 20 pair up the pole and probably in the same cable back to the cabinet, other lines that are active would be too, though.
I wonder if it's worth trying to seperate both of these lines to the pole i.e. currently they're a 4 pair dropwire to the house and then into a 2 pair aluminium wire until they split off 2 metres before my master socket...
If I paid for a seperate drop run straight to my socket I wonder if it would be worth it

It's not off 20Mbit from my max possible speed and puts me perilously close to dropping under the 80Mb sync threshold which would be very annoying since my original sync speed was 140, sigh.

Umm...I don't know what it is with the original line modem off but the new line only has a smart hub (home hub 6) so the only info I can get is...
Max data rate 29522 / 81923
noise margin 15.4 / 6.8
Attenuation 9.6

Unlikely ... what benefits would you see? A Megabit per second increase on max attainable? It will not change the sync or actual download speed.

Swap the modems over and use the original modem on the new line for a couple of tests with and without the original line connected.

.

My apologies. I checked and double-checked that I wasn't misreading it .... Now where's that place in the ad - Should have gone to ?

Which is this 107528 Maximum? (Seeing as I'm confused). The original FTTC or the new, as it's the highest you have posted.

Your Max Possible Speed isn't really your maximum possible and may as well be ignored. Your line is syncing at the max possible speed right now.

In reply to a post by MHC:

Swap the modems over and use the original modem on the new line for a couple of tests with and without the original line connected.

.

Noooooo!

He needs to leave well alone until midnight Sat>Sun.

It's not as if it's urgent.

107528 was the original FTTC lines sync speed when I turned off the router on the new connection to see if it changed the stats...and it did.

Until the next time somebody gets connected that knocks my stats down some more taking me under 80 :|

In reply to a post by NBK:

107528 was the original FTTC lines sync speed

The maximum sync speed is 80 Mbps, or 79,999 Kbps in your case.

it depends how much the 40-50 metres the lines are together affect it which I have no idea about...I know other lines in that 20 pair cable up the pole are connected to FTTC so I can only assume it's from the pole that the interference is...but I don't know

I should have said max possible according to the modem

He has already been "playing" with it - turning off te new and rechecking te old.

"Sync" is the Bearer 0 line, not the Max line. Similarly you should have an actual connection speed on the Home Hub I expect.

Please stop messing with the new line until Sunday, and preferably the old one as well, seeing as they are interacting.

2.2.1 Dynamic Line Management
Dynamic Line Management (DLM) is employed in GEA-FTTC. DLM constantly manages lines to maintain a target link quality (speed and stability). It does this for as long as the product exists.
At provision, the line is put on �wide open� VDSL2 line profiles allowing the upstream and downstream line speeds to run at the upper limit of the product option selected.
On the first day of operation, DLM will intervene if severe instability is detected. Otherwise, DLM will wait until the day after provision before deciding if it must intervene, provided that the line has been trained up for at least 15 minutes during the preceding day.
If DLM intervenes it will set a profile with a maximum rate and a minimum rate, where the minimum rate is set at approximately half of the maximum rate.

That's from Openreach SIN 498.

By intervening it means put banding on the line, which takes months to be removed. It doesn't mean the normal adjustments of interleaving and the like.

You may be in danger of triggering interleaving as it is, with what you have done so far. That costs typically 10Mbps and adds 8ms to latency. Again, taking weeks to go away.

I know - just told him not to . At least for now.

In reply to a post by RobertoS:

You may be in danger of triggering interleaving as it is, with what you have done so far. That costs typically 10Mbps and adds 8ms to latency. Again, taking weeks to go away.

He may be happy if that happens because it will increase the max attainable

Sorry boss

You're probably fine with what you've done so far. But you needed to know . After the second day a few tests and so on as MHC has suggested aren't likely to do any harm.

Unlike the ADSLx DLM, this one normally makes all its changes some time after midnight.

yes 40m of crosstalk can cause that.

You know...
It's all well and good you saying not to mess with it but it doesnt stop BT's systems messing with it...
Internet on that line went down for 20 minutes, couldnt even access the web interface but it was responding to ping and giving out DHCP addresses...very odd...the connection went off and came back on...then lights went out and green light came on, oh it's rebooting, great. when it came back on internet was working again...but i still couldnt access the web interface for a few minutes till I could and I noticed BT wifi was enabled...so it messed me about for 20 minutes so it could enable BT wifi? :|

If I paid for a seperate drop run straight to my socket I wonder if it would be worth it

Just so that a theoretical statistic changes ? What huge folly.