Poor upstream performance

[ccarmock]

During the past few days I have experienced poor performance. I have the Business 10 Mb/s service with Fixed IP address. I am in an ex-Telewest area that is (hopefully!) about to get some major refurbishment to provide for the improved upstream bandwidth and 100 Mb/s

I am in Merton, but fed from New Malden.

My modem (EPC2100R2) stats are:-

Downstream Status Operational
Channel ID 7
Downstream Frequency 339000000 Hz
Modulation 256QAM
Bit Rate 10241000 bits/sec
Power Level 2.4 dBmV
Signal to Noise Ratio 40.8 dB


Upstream Status Operational
Channel ID 4
Upstream Frequency 29200000 Hz
Modulation QPSK
Symbol Rate 769000 bits/sec
Power Level 43.5 dBmV


Having read other posts it would appear that QPSK is a problem. However for the 4 years I have had this service I have always been on QPSK.

I have a 15 dB forward path attenuator on the back of the modem as I am directly across the street from the green cabinet, and even on the lowest tap the power levels were too high.

I don't have any T3 errors etc in the event log, nor do I get disconnects.

Is it possible that in this area that 16QAM upstreams are not provided at the moment and that after the upgrade work this will change?

Or should 16QAM be operational here now and I have a fault?

[Ignitionnet]

Originally Posted by ccarmock

Is it possible that in this area that 16QAM upstreams are not provided at the moment and that after the upgrade work this will change?

Yes, you're on the same ex-Croydon Cable network as myself, QPSK seems to be standard due to upstream laser loading. 16QAM pushes twice as much power as QPSK.

[ccarmock]

Thanks for clarifying. So it coudl be SNR issues or poor/old laser technology that could force QPSK then. It does sound like the ex Croydon/Telewest area is a total mess!

Here's hoping they push on with the upgrades!

[Ignitionnet]

The only results I've seen from mine are out of kilter power levels and a new error message in the logs

[ccarmock]

That doesn't sound like an improvement...!

I guess they need to replace the amplifiers etc first and then make changes to the symbol rate etc? Are you still on QPSK then?

I don't think they have started the upgrades in my area yet. Though I did see higher upstream power levels that fluctuates.

I have been keeping an eye on the Council roadworks list and don't see anything from VM in the area apart from the long list of 'unlock Tee in footway' jobs etc. I assume that the type of work they do will require council notification if it's to lift equipment out of manholes and move to the cabinets.

[qasdfdsaq]

Aren't all ex-TW areas a total mess?

[Peter_]

Originally Posted by qasdfdsaq

Aren't all ex-TW areas a total mess?

No as per below.

[Ignitionnet]

Originally Posted by ccarmock

That doesn't sound like an improvement...!

I guess they need to replace the amplifiers etc first and then make changes to the symbol rate etc? Are you still on QPSK then?

I don't think they have started the upgrades in my area yet. Though I did see higher upstream power levels that fluctuates.

I have been keeping an eye on the Council roadworks list and don't see anything from VM in the area apart from the long list of 'unlock Tee in footway' jobs etc. I assume that the type of work they do will require council notification if it's to lift equipment out of manholes and move to the cabinets.

I was on 16QAM anyway as on 50Mb. They've replaced 'something' but apart from that no other effects.

There were no council roadworks or other requests went in for the work.

---------- Post added at 22:14 ---------- Previous post was at 22:13 ----------

Originally Posted by qasdfdsaq

Aren't all ex-TW areas a total mess?

Nah, just a considerable amount.

[ccarmock]

As an update to this I have noticed some changes in the past week. Fed from New Malden for the past 4 years upstream modulation has always been QPSK on either Channel 1, 2 or 4. Last week there was an outage of around 30 mins a couple of times. Since then there seems to be a new upstream avaiable - Channel 3 on 37500000 Hz which is using 16QAM and also I notice Channel 1 at 18800000 Hz is also at 16QAM.

When my EPC2100 modem reboots if I am quick to look at the web pages during the boot procedure I see initially the upstream would be 5120000 bit/sec until ranging was complete when it would be set to 769000 (I am on the business 10 Mb/s service - due to upgrade to 50 Mb/s business Weds next week). Now when the modem reboots I see the initial rate is 10240000 - ie double the previous rate.

Does this indicate that some of the work to provide the enhanced upstream services has taken place in this area now?

Downstream Status Operational
Channel ID 7
Downstream Frequency 339000000 Hz
Modulation 256QAM
Bit Rate 10241000 bits/sec
Power Level 2.6 dBmV
Signal to Noise Ratio 40.2 dB



Upstream Status Operational
Channel ID 3
Upstream Frequency 37500000 Hz
Modulation 16QAM
Symbol Rate 769000 bits/sec
Power Level 43.0

[Ignitionnet]

The initial rate you saw was actually the rate for the entire channel, which at QPSK is 5120000 bits/s and 10240000 bits/s at 16QAM.

You have indeed had upgrades, 37.5MHz wasn't available to New Malden before them as the upstream capacity topped out just above 30MHz.

Nice one, you've seen more positive impact from the upgrades than I have despite your area having a date 3 months behind mine for uplift.

[ccarmock]

Sounds like progress then... The interesting thing is that there hasn't yet been extended outages of the 4 hours or more others have reported, nor have I recevied a card warning of them. However maybe the business customers will miss out on the mailshot :-) I assume more work needs to take place before the config files actually change to provide the uplifted bandwidth to customers.

I assume that optical units have been replaced somewhere then to allow the upstream lasers to run at 16QAM?

I note though that when I try speedtest.net to the London node I get about 560 kbps upstream so not quite the 700+ I'd hope that the config file for the business service should provide.

We'll see what happens on Weds with the 50 Mb/s business service, which is with their 5 fixed IP option.