100M : Small Download Speed Upgrade

[Chrysalis]

Originally Posted by Ignitionnet

My own area has tons of room free now having a 1GHz network, even 750MHz networks have 300MHz+ free thanks to analogue switch off - each analogue channel consumed 8MHz, enough for 4 HD channels.

are most ares 750 or 1ghz?

[Sephiroth]

Originally Posted by Ignitionnet

Not so much, past 256QAM you get into increasingly diminishing returns.

256QAM -> 1024QAM = 25% increase

The SNR including coding gain to make this happen is 37dB - 6dB above that for 256QAM.

2048QAM = 10% increase over 1024QAM but increases SNR requirement by 3dB - now up to 40dB.

4096QAM = 9% increase over 2048QAM and you're now in need of 43dB SNR.

So in return for an increase from 50Mb/s per channel to 75Mb/s per channel you've increased downstream SNR requirements by 12dB.

Increasing the number of downstream channels is, on the whole, a better way to go. VM can get RF bandwidth back by shifting TV channels from 64QAM to 256QAM and using the freed up multiplexes for additional downstreams.

My own area has tons of room free now having a 1GHz network, even 750MHz networks have 300MHz+ free thanks to analogue switch off - each analogue channel consumed 8MHz, enough for 4 HD channels.

That's why I said that it requires VM's infrastructure to be improved so as to support the QAM increase.

[Ignitionnet]

Little point in a QAM increase. With the advent of DOCSIS 3 more economical to just use additional channels.

[Chrysalis]

I agree with seph, whilst it may be more economical to use more channels, but its clear VM dont want to use more channels, for whatever reasons they see fit. You have told us there is free space for extra channels with the analogue turn off so the question is where are these channels?

I think you previously answered for downstream there is a licensing issue so cannot use 8 channels yet but many areas dont even have 5 channels yet and also many areas only have 2 upstream channels instead of 3 or 4 or 5 or whatever is needed to prevent congestion.

[Sephiroth]

At least Igni is consistent by saying SNR is a stumbling block. (See here).

But as I see it, if 1024QAM requires 38-41 dB SNR and if most of the SH's are reporting this downstream SNR value, it may be worth trialling this because modems will also acquire at 256QAM.

[Ignitionnet]

Originally Posted by Sephiroth

At least Igni is consistent by saying SNR is a stumbling block. (See here).

But as I see it, if 1024QAM requires 38-41 dB SNR and if most of the SH's are reporting this downstream SNR value, it may be worth trialling this because modems will also acquire at 256QAM.

No they won't, any modems that can't handle 1024QAM will error and/or fall offline, there is no spectrum management and no ability to downrate downstreams to accommodate modems with marginal SNRs.

VM could work around this by periodically probing modems for their downstream SNR however where do you draw the line as far as the amount of customers you allow to have a marginal or non-existent service and think of the OSS expense?

Compare this to investing in higher density line cards when you are going to be swapping some line cards out due to upstream bonding requirements anyway - no brainer.

The acid test for this really is a simple one - how many operators are running 1024QAM, and how many have supplied additional capacity simply by using 8 x 256QAM downstream compatible CPE and filling the downstream channels?

Is there a pressing need for more than 400Mbps to a single service group right now? When there is a need for more than this 16 downstream silicon both on line cards and modems is waiting.

[buckleb]

Originally Posted by telfordcable

Mine had been upgraded:



Nice one VM

That's a wicked ping you have there!

I had to wait until Santa brought me my new TP-Link Router before I could test out my upgrade, seems to be working just fine using Superhub in modem mode.



The superhub is using 4 downstream channels and 1 upstream channel, but my area does seem to be (thankfully) free of torrent freaks.

[kwikbreaks]

Don't be jealous - I've improved yours for you...

Ahem....

Originally Posted by Hugh

Polite request - play nicely, please

[Ignitionnet]

Originally Posted by buckleb

That's a wicked ping you have there!

The speed tester's ping reporting is unreliable, ignore it. On the gaming machine I have the ping time is 5ms, on this laptop it's 40ms+, both have the same latency on traceroutes.

Pinging gonzales.namesco.net [85.233.160.167] with 32 bytes of data:
Reply from 85.233.160.167: bytes=32 time=28ms TTL=52
Reply from 85.233.160.167: bytes=32 time=16ms TTL=52
Reply from 85.233.160.167: bytes=32 time=16ms TTL=52
Reply from 85.233.160.167: bytes=32 time=16ms TTL=52

Ping statistics for 85.233.160.167:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 16ms, Maximum = 28ms, Average = 19ms

[qasdfdsaq]

Originally Posted by Chrysalis

qasdfdsaq usage goes up with max speed, the problem is isp's have a nack of underestimating it on a regular basis. However I am not reffering here to total monthly usage but rather burst speed demands on the network. A 200mbit user can and will do in most cases double the burst rate demand on the network.

I disagree there. Statistical contention again, here thinking of the user's own connection. A single person is unlikely to use 200mb on their own for any significant length of time - the oft-quoted most webservers only have 100mb for example. Usage goes up but nowhere near linearly - something like 20% higher usage when speed gets doubled in the last study I saw.

So a 200mbit user downloading the same as a 100mbit user will still double the load on the port whilst downloading.

Assuming all the conditions are favourable, yes, but they would only do so for half the amount of time. Again, reducing statistical contention.

---------- Post added at 15:47 ---------- Previous post was at 15:41 ----------

Originally Posted by Chrysalis

are most ares 750 or 1ghz?

I believe upgrading from 750 to 1Ghz was part of the 100mb rollout upgrades.

[Ignitionnet]

Originally Posted by qasdfdsaq

I believe upgrading from 750 to 1Ghz was part of the 100mb rollout upgrades.

Nah, most areas are 750MHz or 860MHz. Overbuilding has been done on areas running at 550MHz, areas at 750MHz have only had work done where needed for upload upgrades and downstream laser changes to permit use of 256QAM in areas previously doing 64QAM.

[Chrysalis]

Originally Posted by Ignitionnet

The speed tester's ping reporting is unreliable, ignore it. On the gaming machine I have the ping time is 5ms, on this laptop it's 40ms+, both have the same latency on traceroutes.

Pinging gonzales.namesco.net [85.233.160.167] with 32 bytes of data:
Reply from 85.233.160.167: bytes=32 time=28ms TTL=52
Reply from 85.233.160.167: bytes=32 time=16ms TTL=52
Reply from 85.233.160.167: bytes=32 time=16ms TTL=52
Reply from 85.233.160.167: bytes=32 time=16ms TTL=52

Ping statistics for 85.233.160.167:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 16ms, Maximum = 28ms, Average = 19ms

I assumed was a tcp ping on the speedtest not a udp one which would then make it affected by tcp window sizes which are smaller on laptops which is what explanation I gave to myself why my laptop got lower ping times on it. However with your results my idea is out the window unless your laptop is tuned for large tcp window sizes or has a dodgy wireless signal.

---------- Post added at 17:56 ---------- Previous post was at 17:52 ----------

Originally Posted by qasdfdsaq

I disagree there. Statistical contention again, here thinking of the user's own connection. A single person is unlikely to use 200mb on their own for any significant length of time - the oft-quoted most webservers only have 100mb for example. Usage goes up but nowhere near linearly - something like 20% higher usage when speed gets doubled in the last study I saw.


Assuming all the conditions are favourable, yes, but they would only do so for half the amount of time. Again, reducing statistical contention.

---------- Post added at 15:47 ---------- Previous post was at 15:41 ----------


I believe upgrading from 750 to 1Ghz was part of the 100mb rollout upgrades.

They dont need to use it for a significant amount of time. Even a 200mbit user doing a 10 second speedtest can cause 10 seconds of congestion. I am talking about burst rate demand, not overall usage. Incidently its not too diffilcult to exceed 100mbit assuming no congestion on VM side, various servers now use gigabit interfaces, p2p uses multiple sources meaning they can exceed 100mbit by collective means rather than a single fast connection, giganews and the like will very unlikely still be using 100mbit interfaces, eg. every ftp file server I run is at least a gigabit interface, a few are actually multi gigabit bonded as even a gigabit is considered small now days for file hosting. The only downloads that would struggle is http downloads as they usually single stream only with web server software often not using rfc1323.

---------- Post added at 18:00 ---------- Previous post was at 17:56 ----------

Originally Posted by Ignitionnet

Nah, most areas are 750MHz or 860MHz. Overbuilding has been done on areas running at 550MHz, areas at 750MHz have only had work done where needed for upload upgrades and downstream laser changes to permit use of 256QAM in areas previously doing 64QAM.

So those with the delayed uplift work for overbuilding are now in the best position with more useable bandwidth?

[Ignitionnet]

Originally Posted by Chrysalis

I assumed was a tcp ping on the speedtest not a udp one which would then make it affected by tcp window sizes which are smaller on laptops which is what explanation I gave to myself why my laptop got lower ping times on it. However with your results my idea is out the window unless your laptop is tuned for large tcp window sizes or has a dodgy wireless signal.

Why would window size affect a TCP ping?

Originally Posted by Chrysalis

So those with the delayed uplift work for overbuilding are now in the best position with more useable bandwidth?

Yep.

[Sephiroth]

Not in my area.