60M : Upstream Power Levels Dropped 12dbmv

[blue166]

Hi all,

I am looking for some help. On Monday morning my upstream power levels sat at 49dbmv. That evening I noticed my SH had a load of messages in the log and after checking noticed my upstream power levels had dropped to 37dbmv.

Now since then my internet has been slow and lazy. Upload speed has halved.

Any need for concern?

[Sephiroth]

On the face of it, no. Probably grounds for joy as you're closer to what's ideal (40 dBmv).

Can you recall what your downstream power did?
Also had your upstream channel changed?
What else changed? Like your IP address?

Also best to paste your full levels otherwise we have nothing to diagnose.

[blue166]

Thank you for your post.

My DS power levels crept up slightly. Probably by 2-3dbmv across 8 DS channels.

I have had an engineer out today and he replaced my SH.

I have also been made aware of a high utilization on my cable which has a fault ref.(Could you please explain more about high DS/US utilization).

I used to be able to connectio to upstream channel 49,50 and 51 (51 did not last long). But always had 49 and 50. I now only ever have 49 and 49 only. I have rebooted well over 100 times and returned the superhub to defaults and it will not budge.

Please help.

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 266750000 Hz 274750000 Hz 282750000 Hz 290750000 Hz 298750000 Hz 306750000 Hz 314750000 Hz 322750000 Hz
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 107 108 109 110 111 112 36 37
Modulation QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 2.0 dBmV 1.8 dBmV 1.5 dBmV 1.2 dBmV 2.6 dBmV 2.5 dBmV 2.7 dBmV 2.6 dBmV
RxMER (dB) 42.5 dB 41.9 dB 41.9 dB 41.9 dB 41.4 dB 41.4 dB 41.4 dB 41.4 dB

Upstream
US-1 US-2 US-3 US-4
Channel Type 2.0 N/A N/A N/A
Channel ID 49 N/A N/A N/A
Frequency (Hz) 45800000 Hz N/A N/A N/A
Ranging Status Success N/A N/A N/A
Modulation QAM16 N/A N/A N/A
Symbol Rate (Sym/sec) 5120000 N/A N/A N/A
Mini-Slot Size 128 N/A N/A N/A
Power Level (dBmV) 38.0 dBmV N/A N/A N/A
T1 Timeouts 0 N/A N/A N/A
T2 Timeouts 0 N/A N/A N/A
T3 Timeouts 0 N/A N/A N/A
T4 Timeouts 0 N/A N/A N/A

My IP has only changed since the hub was replaced today.

Thanks,

[Sephiroth]

Thanks for that. So you were previously on two upstreams and now you're on one. You've got 8 downstreams and so prolly your area was thoght by VM to be close to upgraded.

But then, I speculate, problems appeared on the upstream. Most likely one channel was impaired and the CMTS needed 49 dBmv to get the data from your modem. So they've reverted pro tem to one channel and the power level has settled down.

It's spot on. The nominal target is 0 dBmv DS/40 dBmv US and they try to equalise things at the street cabinet amplifier to achieve this. Your US is as much below 40 as your downstream is above. So that's good.

Now to the utilisation question. Without going into the full technicalities, each downstream channel is capable of 55 meg. If you're on 60 meg, it would need less than 8 downloaders at full speed to saturate the downstream capacity on the 8 frequencies that are shared.

Similarly with the upstream, where one channel has 9 meg capacity. If VM were upgrading properly then you shouln't have congestion. If they haven't finished upfrading, they could have swung some cables onto your UBR.

[horseman]

Originally Posted by Sephiroth

Thanks for that. So you were previously on two upstreams and now you're on one. …..

Dave, In the unlikely event you haven't filled in the gaps - this scenario refers to the "Lancing Lemon" aka our old friend "lanc6".
I suspect VM are still potty training the baby while implementing additional upstreams and hit the usual problem of "noisy nodes".

Baby probably won't be out of "nappies" till Easter completely…..

[blue166]

Hi guys,

cpc2-lanc6-2-0- ALSO .. Is the cpc a Cisco Provisioning Center?

Yes terrible old lanc6 (seems to be total garbage at best).

To clear things up I have only had 1 upstream channel.

When I used to reboot superhub during low speeds at peak times I would often get chucked onto upstream channel 50, later also getting 51 for a couple of weeks (on 51 I had full speed service 24-7 in that period).

Since then I am left on upstream channel 49 and for love nor money never ever get 50 or 51 upon rebooting to the point I feel that I am locked only to 49.

Your advice,information etc.. would be great. Also please more info on LANC6 would be ever much appreciated.

Thanks,

[qasdfdsaq]

No, IIRC it used to stand for customer premisis card or something, but is now vestigial and meaningless.

[jb66]

same happening in my area, they are doing a bit of noise busting so they can lower the upstream power level

[blue166]

Just off topic slightly but the green cabinets on the street, how many customers does one hold? Because I hage a great stretch of road with only 1 .. have Nynex originally not planned properly?

Also what are the tade secrets of these cabinets. I hear about 2 or 3 customers hanging off one tap and stuff like that ?!? Is that bound to contribute to utilization or is it purely the node UBR suffering from to many cables hooked up??

Thanks,

[judgey]

in some cabinets its true that on some taps there are 2/3 way splitters on them which is a NO NO, but we report it and **** happens .........

[blue166]

Is this causing problems on broadband?? I would imagine it would?

[Sephiroth]

Almost certainly. Power level would drop if your tap point, previusly exclusive to you, had had a splitter put on, each port connected and adding 4 dB per port. It's bad practice, against VM's rules and you should vigorously explore this theory.

[blue166]

Would this cause speed fluctuations?

[Sephiroth]

If they've had to put a splitter onto tap points in a green cabinet,then they're oversubscribing the area. This situation generally needs what's known as a Category C Resegmentation, with a new fibre at the optical node and additional street boxes to snip the load.

[blue166]

Is this speed doubling work going to clear utilization and if you know, how much extra capacity are they adding to areas (if any?)