120M : Virgin Media 150Mb Coming 2014

[MUD_Wizard]

Originally Posted by Chrysalis

A docsis will assign 4 DS channels to a connecting vmng300, unless there is a fault or restriction in config. If there is more than 4 DS channels the docsis can choose which 4 to assign, it doesnt have to be the same 4 every time, so as such a degree of load balancing can still occur with 4 DS modems on 8 DS channels. Indeed VM have operated like that for years prior to docsis 3 eg. using 1 US channel modems in service groups of 4 US channels.

A vmng300 modem wont automatically get less speed in 8 DS channel service groups, in fact its more likely to get higher speeds as there is more capacity available to all users.

Yet if one of the VMNG300's in each of the 4 DS channels take 120Mb then the other VMNG300 in your example can only achieve the remaining 80Mb. So only half the VMNG300's achieve full speed. i.e. two modems.

Compare that with 8 DS channels where 3 Superhubs can achieve the full 120Mb with a remaining 40Mb left over.

I'd say that's getting less speed.

If you mix VMNG300's into already saturated channels then the situation can be even worse where none of them achieve full speed.

[craigj2k12]

Originally Posted by MUD_Wizard

Yet if one of the VMNG300's in each of the 4 DS channels take 120Mb then the other VMNG300 in your example can only achieve the remaining 80Mb. So only half the VMNG300's achieve full speed. i.e. two modems.

Although thats an unlikely situation

Originally Posted by MUD_Wizard

Compare that with 8 DS channels where 3 Superhubs can achieve the full 120Mb with a remaining 40Mb left over.

With the 120Mbit config set at 133Mbit, that leaves 1Mbit of shared capacity left over, although, again, not a likely situation, and will also vary area by area see here for a simple explanation of bandwidth contention, its not something that can be plotted, or have rules applied to it, it varies area by area, and VM have to manage it as so

Originally Posted by MUD_Wizard

If you mix VMNG300's into already saturated channels then the situation can be even worse where none of them achieve full speed.

And superhubs on saturated channels can magically add their own bandwidth!?

[MUD_Wizard]

Originally Posted by craigj2k12

Although thats an unlikely situation

It doesn't matter how unlikely a situation it is. Less VMNG300's will achieve full speed than Superhub's given a finite set of channels, no matter how large that number is.

Originally Posted by craigj2k12

And superhubs on saturated channels can magically add their own bandwidth!?

That's a strawman argument and you know it.

[craigj2k12]

Originally Posted by MUD_Wizard

It doesn't matter how unlikely a situation it is. Less VMNG300's will achieve full speed than Superhub's given a finite set of channels, no matter how large that number is.

As already noted, only on saturated channels, otherwise the only limiting factor is the max traffic rate set by the config

Originally Posted by MUD_Wizard

That's a strawman argument and you know it.

On a saturated group of channels, the superhub will potentially see more bandwidth, whereas the VMNG will give a more consistent quality of service

[MUD_Wizard]

Originally Posted by craigj2k12

With the 120Mbit config set at 133Mbit, that leaves 1Mbit of shared capacity left over, although, again, not a likely situation, and will also vary area by area see here for a simple explanation of bandwidth contention, its not something that can be plotted, or have rules applied to it, it varies area by area, and VM have to manage it as so

There's 54 Mb's per 256 QAM channel x 8 = 432Mb.
You already counted Docsis overheads in the 133Mb config.
So ~33Mb left over, but lets not quibble over a few Mb.

I'm not making rules for contention, just showing that you are wrong about the VMNG300 having no impact on speed vs the Superpup.

---------- Post added at 07:13 ---------- Previous post was at 07:06 ----------

Found another reason why VM are advertising 152Mb (see page 5):
http://www.cablelabs.com/cablemodem/.../docsis_30.pdf

[Kushan]

Originally Posted by Chrysalis

in VM support mode during that post?

Not sure whats so complex about it.

A docsis will assign 4 DS channels to a connecting vmng300, unless there is a fault or restriction in config. If there is more than 4 DS channels the docsis can choose which 4 to assign, it doesnt have to be the same 4 every time, so as such a degree of load balancing can still occur with 4 DS modems on 8 DS channels. Indeed VM have operated like that for years prior to docsis 3 eg. using 1 US channel modems in service groups of 4 US channels.

A vmng300 modem wont automatically get less speed in 8 DS channel service groups, in fact its more likely to get higher speeds as there is more capacity available to all users.

The sh2 a fine device which completely obseletes the vmng300? never used a sh2 so cant speak on own experience but there is problems reported by sh2 users so I expect the statement is false.

I don't see where you're getting that from. I laid out two different sides of the argument.

Yet I find it interesting that you're complaining about the SH2 not having used one, yet I've used both the Ambit 300 and the SH2 - apparently my opinion is still invalid, though.

[craigj2k12]

Originally Posted by MUD_Wizard

[/COLOR]Found another reason why VM are advertising 152Mb (see page 5):
http://www.cablelabs.com/cablemodem/.../docsis_30.pdf

Whats that got to do with it, as you even mentioned above EURODOCSIS channels have more bandwidth so the 38mbit per channel on that link is irrelevant

[Sephiroth]

Craig is right, Muddie.

38 meg is what a 6MHz channel bandwidth delivers (to put it another way).

[MUD_Wizard]

Originally Posted by craigj2k12

Whats that got to do with it, as you even mentioned above EURODOCSIS channels have more bandwidth so the 38mbit per channel on that link is irrelevant

152Mb is a bit of an odd number, as has been pointed out before (apart from being more than twice BT's top FTTC speed). More than a bit of a coincidence that it coincides with Cable Labs rate suggestions. Legacy standards can have an ongoing impact on arbitrary choices in all kinds of technology areas.

However it's always possible they've chosen 162Mb (3 Eurodocsis DS channels) as the config size and not 168Mb. We will see.

---------- Post added at 20:59 ---------- Previous post was at 20:47 ----------

Originally Posted by Sephiroth

38 meg is what a 6MHz channel bandwidth delivers (to put it another way).

Of course it does Seph, however 152Mb is still an arbitrary number for a Eurodocsis system until you put it into some kind of context that makes sense.

[Sephiroth]

It mightl be an arbitrary number (and I now see that you meant VM may have taken its cue from CableLabs's number). But as others have said, 2 x 76 Meg is an enticing number.

[MaverickJesus]

If VMs broadband strategy over the last few years has taught me anything, its that everything is about one-upmanship. Therefore, it seems entirely likely its chosen purely due to FTTC x2 (I suspect given the tiers they were originally aiming for 150mbit, but figured they may as well throw the extra 2mbit on there just for marketing reasons).

[oscar87ni]

To those who wonder if their broadband ONLY package will see a price increase from 1st February 2014.

In my case I can CONFIRM YES it will.

Have just received letter. It will go up by 3.25 GBP for me. So will be 38.25GBP per month.

My Package is: XXL120 BB ONLY

[BenMcr]

Originally Posted by oscar87ni

To those who wonder if their broadband ONLY package will see a price increase from 1st February 2014.

In my case I can CONFIRM YES it will.

Have just received letter. It will go up by 3.25 GBP for me. So will be 38.25GBP per month.

My Package is: XXL120 BB ONLY

Something isn't right there then, BB standalone shouldn't be going up in Feb.

[oscar87ni]

It could only be explained that I have just downgraded from BB & Phone to BB ONLY early in October and my 12 month contract have just started on 5th October 2013, so I have avoided October price increase by 5 days.

I still got a feeling that it applies to everybody then regardless when contract was taken.

But surely 3.25 added to 35 quid is much more than 6.9% or whatever they mentioned. It's close to 10% increase. I can live with that, but if there is another increase after that will ask for a discount to bring the price down straight after increase.

Anybody else on broadband only package? Any letters yet?

[kev445]

Isn’t it a bad thing to have modems with different downstream capabilities on the same segment?

My understanding is that the CMTS distributes packets in a round robin fashion on the available downstream channels… Which means if your segment has more than 4 downstream channels and has a combination of VMNG300’s and Superhubs, you could end up in a situation where 1 or more VMNG300's would cause congestion when downloading for the Superhubs when there is actually spare downstream capacity on the 4 remaining channels…


The VMNG300’s effectively stop the SuperHubs utilising all the available capacity.