Looks like Virgin are determined to flush out old modems
 

I was hoping for shrub2 but ended up with a shrub one some weeks back.
So decided to keep using the old reliable work horse on 120mb.
Started getting grumpy text messages on my mobile. The last one return the hub now if you don't intend to activate it in seven days. Guess they wish old kit of the network.
Since I was getting some slow downs in the evening I've activated it.

Re: Looks like Virgin are determined to flush out old modems
 

deary me dude, you have shot yourself in the foot big time. I assuming you had a vmng300 before if you are on 120mbit, you should have kept. Technically a shub could improve your evening speeds as it can load balance across more channels but if your area is prone to congestion I would assume the other channels would be in the same position and thus any performance increase would be marginal.

I don't know if this has been covered in another thread yet but I am curious to know whether they have stopped producing shub1's yet and trying to get rid of their stock so they can focus on shub2's. I hope they aren't still buying them because they are way behind the mark now technlogy wise and should be EOL. I need to pick Ben's brains.

Re: Looks like Virgin are determined to flush out old modems
 

Yeah mon General. But won't he now be in modem mode because he only had a modem before?

So he won't be worse off, may be marginally better off.

Re: Looks like Virgin are determined to flush out old modems
 

Yup Modem mode. I could have ignored the text. What would they do send a bailiff for it????

Seems to be okay.

Re: Looks like Virgin are determined to flush out old modems
 

You tagged this 120M. I thought they were only issuing Superhub 1s for 30Mb and every other speed get the superhub 2 :confused:

Re: Looks like Virgin are determined to flush out old modems
 

Nope clearly not.

Re: Looks like Virgin are determined to flush out old modems
 

too true too true

only for fauilts and new 120mbit customers. They aren't sending them out willy nilly to existing 120mbit customers otherwise we'd all have one. Tbh even if one arrived in the post tomorrow i still wouldn't use it. I would keep it safe in its box until I started having speed problems and then I would ring up and get it registered.

Re: Looks like Virgin are determined to flush out old modems
 

They'd ask for it back mate.

Re: Looks like Virgin are determined to flush out old modems
 

i had 2 shub1's and they never asked for them back

Re: Looks like Virgin are determined to flush out old modems
 

I bet they would now.

Re: Looks like Virgin are determined to flush out old modems
 

remember seph my last 2 months on VM with the shub in modem mode, I had more latency than the vmng300 and in ssh terminal's I could visibly see the extra jitter. So I personally think a shub1 in modem mode (even with new firmware) is not upto par of a vmng300.

The jitter on my shub1 only went down when VM did a node split, bonded the US channels and added DS channels to make 8, in my last few weeks of service. I think even then tho ssh still felt more jittery than the vmng300 did.

shub2 I got no idea as I never used one.

Re: Looks like Virgin are determined to flush out old modems
 

i have a superhub 1 in a box here that they have never asked for it back.

Im now using a Superhub 2 in modem mode alongside a Netgear WNDR3700V4 and works like a dream.

---------- Post added at 21:40 ---------- Previous post was at 21:38 ----------

Well here is mine....

[img]Download Failed (1)[/img]

Re: Looks like Virgin are determined to flush out old modems
 

are you on my node? no.

and also to point out my shub felt jittery regardless of what my tbb graph looked like.

those who were on this forum in 2012 may remember what my graphs looked like when I changed from the vmng300 to the shub1.

Re: Looks like Virgin are determined to flush out old modems
 

someones a bit touchy about their node.

U said u had no idea what about a SH2 so i posted mine, whats the problem?

Re: Looks like Virgin are determined to flush out old modems
 

The fact that yours has nothing to do with his.

Re: Looks like Virgin are determined to flush out old modems
 

I was on the SH2 trial & we have now been told to take the SH1's to the council recycling centre though originally when the trial started they did want them back now it seems they don't.

Re: Looks like Virgin are determined to flush out old modems
 

Their note about the Council recycling centre says that they (VM) then get the SH1 back by arrangement.

Sod that for a bunch of bananas!

Re: Looks like Virgin are determined to flush out old modems
 

Still using a VMNG300 and have recently received the 120/12 upgrade from 100/5, got 4 downsteams and 2 upstreams. VM say my current modem needs to be replaced by a SH but will it improve my stats any at present?

[img]Download Failed (1)[/img]

[img]Download Failed (1)[/img]

Re: Looks like Virgin are determined to flush out old modems
 

rubbish dude. I was using a vmng300 on 100mbits for one and a half years and have been only 120mbits for somewhere around 6 months now at least and haven't had any speed problems at all. The irony (and I do laugh) is that rather leaving happy customers who have no problems along (I never have any probs with my connection) VM seem determined to force shubs on customers and introduce problems. Maybe the [Mod Edit - offensive comment removed] in India haven't got enough to do!

If it ain't broken don't fix it dude. I am not going to look at getting a shub till the next tier upgrade (200mbits?) because I'll defo an 8 channel modem.

Re: Looks like Virgin are determined to flush out old modems
 

There are two opinions on this and both are equally valid:

Opinion 1) The superhubs can handle 8 D/S channels and thus load balance more effectively than the Ambit 300 (your modem). However, in less congested areas the difference will be minimal. So in that respect, upgrading to a superhub (1 or 2) may help you in certain instances.


Opinion 2) Although the SHubs may be more effective in certain instances, the SH1 is fraught with issues on the routing side and the SH2 is still relatively new and thus somewhat unproven. I.e. if it isn't broke, don't fix it.


I, personally, feel that in modem mode, the hubs are just as effective as the Ambit 300 and it's nice to know your connection is balanced over more channels. That being said, the SH1 is a poor design and I don't think it's worth the hassle of the upgrade. The SH2 however is much better and it's quite competent as a router as well, which even if you use your own, is nice to have as a backup. So what I would suggest you do is give them a call and see which they'd be sending you - if they try to give you a SH1, politely decline and keep your ambit. If it's a SH2, take the upgrade, then decide later if you want to keep it as a modem or use it as a decent dual-band router.

Re: Looks like Virgin are determined to flush out old modems
 

Thanks for the replies guys, if I did get a SH i'd be using it in modem mode anyway so will probably hang onto the VMNG300 for now. No guarantees that VM would send me out a SH2 anyway.

The reason I was asking if the SH(1/2) was better is that the ping and latency with the modem on my UBR has always ben a bit on the high side but it's probably down to the UBR itself cpc3-broo8-2-0 which tends to be the worst performing one on the local network and I'm seemingly stuck with it.

Re: Looks like Virgin are determined to flush out old modems
 

yup, I have seen no evidence to say the shubs are better latency wise, technically they should be worse by design. There has been a huge debate about it on the forum will some people asserting that the vmng300 is better but I believe this was unproven. At best the shubs will equal the vmng300, they definitely won't beat it.

Following on from Kush's advice, if you ever do want/feel the need to ring up for a shub don't take any bs. It has been VM's policy from the get go to make shub2's available exclusively for 120mbits. They are the ones wanting you to get rid of your vmng300 so make sure they give you a shub2 in exchange and not a poxy shub1.

Re: Looks like Virgin are determined to flush out old modems
 

The Superhub doesn't do any load balancing, it's the CMTS' job to do load balancing. A Superhub may make the job a tiny amount easier on a badly run network, but depending on that is just a lousy excuse for a badly run network, not a benefit of the Superhub.

Re: Looks like Virgin are determined to flush out old modems
 

Qasi

You know exactly what Kush meant. 8 channels are better for load balancing than 4. You really do like to pick the minutest holes.

Re: Looks like Virgin are determined to flush out old modems
 

As Seph said, you know exactly what I mean. 8 Channels means twice the bandwidth as 4 channels (Though I'm sure you'll nitpick at that statement as well). It's not inconceivable that 4 channels could get congested briefly where 8 would not. Especially those still on Ambit 300's and 120Meg, Just one user could saturate more than half of the available bandwidth 4 channels provides. If you happen to be on the same 4 channels, then what? An admittedly rare occurrence, but that's just one other user. How about 2 or 3?

Re: Looks like Virgin are determined to flush out old modems
 

You've both gone off on a tangent and completely missed the point it seems.

Yes, 8 channels is double the capacity of 4 channels. But no single user can even fill 3 channels let alone 4, plus simply because one person has a 4 channel modem does not reduce the entire network down to a 4 channel bottleneck. The maximum any user can use right now is about 2.5 channels anyway. 2.5 out of 4 is exactly the same as 2.5 out of 8 - it's still 2.5.

Taking your scenario, while hypothetically several Ambit users are demanding full speed from their 120Mbit services simultaneously via the same 4 channels of an 8 channel set, while presumably the other 4 channels remain empty, then that just means the CMTS' load balancing setup is broken. Getting a million channel modem won't unbreak it.

---------- Post added at 15:02 ---------- Previous post was at 14:57 ----------

What exactly do you see as the problem here?

Say the network has 8 channels.

You're on channels 1-4. Someone else is on channels 1-4. Channels 1-4 get heavily loaded.

You get load balanced onto channels 5-8. Problem solved.

Re: Looks like Virgin are determined to flush out old modems
 

Have we? Everything was pretty clear until you came along and started nitpicking.

I've highlighted the bit that's most obviously wrong here, from a simple maths point of view.

2.5 out of 4 leaves 1.5
2.5 out of 8 leaves 5.5

Not "exactly the same" at all. IF two Ambit users have 120mbit and happen to be on the same 4 channels, then it's impossible for them both to achieve 120Mbit down at the same time (2.5 + 2.5 = 5). This is a scenario with just 2 users, obviously there's a lot more users on the local network than that. Can the CMTS switch one of those two users "on-the-fly"? Can it do that as soon as channels 1 and 2 become maxed out? (or rather, once channels 1-4 go above 50% capacity).

Right, someone who's a bit more qualified than me will have to come along and answer this, but how dynamic IS that load balancing on the CMTS?

What I mean is, how quickly can the CMTS tell the modem that it needs to jump channels? I thought it was only during the initial sync that the modem does, i.e. roughly every reboot (and presumably there's a kind of resync that happens occasionally - again, I need to stress that I'm not an expert here at all and I would like someone to clarify). So yes, the CMTS load balances but can it load balance usage down to the minute, such as when one user starts downloading a large file versus overall usage in the area?


There's another scenario as well. Assume the CMTS is load balancing effectively, but the area has heavy use. If load balancing is working as it should, it's reasonable to assume that all available channels have roughly the same amount of utilisation. Say all channels are regularly on 75% utilisation - quite high but quite a lot of capacity to spare. You've got 4 channels, what does that leave you with? On 4 channels, that leaves you with approximately 2 channels worth of bandwidth - not enough for your 120Mbit. However, if you have 8 channels? You've got effectively 4 channels worth of bandwidth, so still plenty to go around.

Re: Looks like Virgin are determined to flush out old modems
 

Just had shub2 installed today and they wanted my shub1 back will be checking speeds later on 120mb to see if any difference on me ipad and laptop can't notice any difference on me iMac or PC

Re: Looks like Virgin are determined to flush out old modems
 

Be sure you connect to the 5ghz for best results.

Re: Looks like Virgin are determined to flush out old modems
 

It's not nitpicking when you've seem to got the whole idea wrong.


The network has 8, 2.5 out of 4 leaves 1.5 + 4 = still 5.5 Once again, simply because one modem has 4 channels doesn't reduce the entire network to 4 channels.

IF two Ambit users have 120mbit and happen to be on the same 4 channels trying to achieve 120Mbit down at the same time then load balancing is broken.

Yes. The CMTS can switch any users and any individual channels of any users at any time (well, any time the modem is actually connected).

Yes.

Yes. It can switch at any capacity level, modem count, or SID count specified by the network administrator (though IIRC some Cisco IOS versions won't allow you to set a threshold below 25%)

As dynamic as the network administrator is competent enough to set it up to be.

Several times a second.

Yes


Then you should still notice no difference.

Load balancing isn't static. If all channels were at 75% and you load up your 4 to 100% while trying to pull 125%, then it'll get rebalanced so all 8 channels end up at 100%.

In many places this is already part of normal operation - 16 or more downstream channels across which many 1, 4, and 8 channel modems are distributed.

Re: Looks like Virgin are determined to flush out old modems
 

Well then, I obviously have misunderstood how the whole channel system works. I still maintain that 8 channels are better than 4 though, I can still see many scenarios whereby 4 would see congestion that 8 wouldn't.

Re: Looks like Virgin are determined to flush out old modems
 

4 would see congestion maybe if an area is heavily utilised and eg. all 8 channels only have 5mbit/sec spare capacity, so then a 30mbit user would get 20mbit on 4 channels and full 30 on 8.

But if an area is that heavy utilised and given how spiky utilisation is on such small shared pipes then I think 8 channel modems would still see congestion as well just not so severe.

VM/ntl have for years supplied more channels than the modem can use, this was how they operated before bonding started, eg. back in the docsis1 days was 4 US channels load balancing modems that could only use 1 US channel. Of course it was configured in a flawed manner, as channel hopping often got results in dodging congestion. It still happens now with users connected to 1 or 2 US with 2 or 3 US in the pool.

On my vmng300 I did see channel rotation on the DS as well, but it wasnt much as was only 5 DS channels activated in my area, VM didnt bump it to 8 until after I started using my superhub.

I only changed to the superhub in my last month of service as I had FTTC installed and no longer cared as much for my VM connection, if I didnt have FTTC I likely would still be using the vmng300 now.

Re: Looks like Virgin are determined to flush out old modems
 

I still maintain the only time you'll ever see a difference is if the network is being run badly.

Re: Looks like Virgin are determined to flush out old modems
 

This IS Virgin media...

Re: Looks like Virgin are determined to flush out old modems
 

:D

Re: Looks like Virgin are determined to flush out old modems
 

In my more tech savvie days, I used to be able to understand conversations such as in this thread, but these days such stuff goes over my head. So, like you, I am not sure what is being said here.

For those that understand such things, could someone please give an easy to understand summary of just how the internet is delivered to customers and where and why the congestion/problems happen?

I know there is/was about 750mhz of bandwidth/capacity on the cable network which is split into transport streams or channels. Each channel is about 8mhz each and there are about 75 channels in total, in theory, that could be used. Many of these channels are used for tv, currently 48 in my area. When I last looked at my modem's stats, I think there were 8 downstream channels and 2 upstream channels. So that makes 58 channels in total being delivered to my area.

I know in homes we have the cable modem. In the street we have the cabinet and eventually there is the headend. What next?

Re: Looks like Virgin are determined to flush out old modems
 

What next? You ask:

In addition to Horizon's analysis, it more or less works like this (but can vary in different parts of the country according to who was the original cable supplier):

1/
A small street cabinet connects either 16 or 32 customers. A larger street cabinet connects 48 or 96. It is passive equipment.

2/
The cable from a cabinet passes along to another cabinet configured as above.

3/
5 or 6 cabinets go to a powered Launch Cabinet and 4 or 5 of these go to an optical node and it's fibre from there to the local hub. The optical node cabinet is active.

4/
In high density population areas, street cabinets may all be of the 48/96 capacity kind.

5/
The optical node originally would have supported only 2 upstream channels and these might have been split between two nodes at the VM end line card. So that's a heck of a lot of users who think they're getting, say 10 meg upstream sharing just 40 meg upstream capacity.

6/
A downstream service group comprises 16 channels, within which a user's bonding group currently has up to 8 downstream channels with c. 400 meg capacity to share across one or two optical nodes. VM are also bonding two upstream channels.

That explains how over utilisation can occur.

For high contention areas, VM should be adding more optical nodes and line cards and CMTS devices at their end to cope with the additional channels allocated. That's what they say they're doing.

7/
The optical node connects via fibre to a line card on a UBR/CMTS at the local hub/local head end. Many optical nodes terminate on a single line card. An individual's downstream and upstream (both shared with other users) terminate on the same line card andin the same Service Group.

Re: Looks like Virgin are determined to flush out old modems
 

Thank you for very much for posting all that Seph. I'm digesting it all now, may have a few questions later.

---------- Post added at 16:49 ---------- Previous post was at 16:33 ----------

Ok, a few questions:

Would it be accurate to say that 16 channels or 800mb is the maximum download capacity available in any one area? And potentially using the most extreme example, that 800mb has to serve the following:

6 large street cabinets of 96 customers each = 576 customers in one launch cabinet.

5 launch cabinets of 576 customers each = 2880 customers at one node.

Thus one node at its maximum capacity has to share 800mb between 2880 customers.

So if all 2880 customers are downloading at the same time, the maximum speed they can get is 3.6mb each.

Is that correct so far?

Re: Looks like Virgin are determined to flush out old modems
 

These extrapolations have been attempted many times. In densely populated areas, cabs are usually fully subscribed and many a horror story exists about splitters in the cab.

So your 2880 customers per optical node is a maximum where no splitters are used. The node serves a service group of 16 downstream channels and the CMTS aims to load balance customers onto 8 channel bonding groups by some algorithm or other that can be tweaked by the admin.

In my area, I have examined street cabs and have assessed that an optical node probably services not more than 500 customers. I did a sensibility check on that. The Liberty Global web site says that VM passes 12 million homes and has 4 million cable broadband customers. That's 33%. In my area there are c. 3,000 homes passed. We have 2 optical nodes in Winnersh - so that's c. 500 customers per optical node.

Does that help?

So, make of that what you will.

Re: Looks like Virgin are determined to flush out old modems
 

Ok, so you reckon in real terms, excluding inner city areas, its 500 customers sharing the 800mb capacity?

Re: Looks like Virgin are determined to flush out old modems
 

That's what I think. All plus/minus of course.

Re: Looks like Virgin are determined to flush out old modems
 

I concur there with my personal experience, made my line almost unusable when it was added by a tech, and thankfully a tech came and removed it about 2 weeks later when I complained (armed with ping graphs and stats) via VM's Twitter team.

Re: Looks like Virgin are determined to flush out old modems
 

Out of interest, what do you see as a 'sensible' configuration? Keeping in mind reasonable financial constraints, of course.

Given LG have stepped back from ADSL/VDSL stuff, it seems likely they might concentrate on overhauling the core network ready for DOCSIS 3.1/IPv6/whatever.

Re: Looks like Virgin are determined to flush out old modems
 

If they plan to remain competitive, this is pretty much their only option. 3.1 is still a couple of years away but I dare say it's the most financially sound way to increase capacity on the network.

Re: Looks like Virgin are determined to flush out old modems
 

Depends on the area, not all areas have 16 channels, some may have more, some may have less. They stared with as low as 3 per area and have been adding more as and when required. AFAIK most should have at least 8 by now but that's not necessarily the case.

There's no hard limit that says they cannot deliver more than 16 channels through one node either.

Should also point out your extreme example is indeed an extreme example, uptake, population density, node size, and cabinet size all vary widely, one cabinet does not always equal one node, and finally, 3.6Mb per customer isn't actually all that bad.

Not long ago ISPs were selling to a contention ratio of about 50:1, meaning a "Up to 24Mbps" ADSL customer could be allocated only 0.5Mbps (or less). I recall once hearing of a certain ISP only allocating sufficient bandwidth for 64Kbps per customer at peak time. Consumer ISPs have always been overselling to those sorts of levels, on the basis that most people will not be using most their speed most of the time. That's how consumer broadband ended up being so cheap.

---------- Post added at 18:57 ---------- Previous post was at 18:48 ----------

IMO 50:1 contention ratios are just fine, especially on faster lines. Back where I used to work, we had around 2,200 student residences sharing 1000Mbps of capacity. And that never went above 30% load. Course, that was 2006...

Last I recall the average consumer used something around 50GB a month or less. On an average connection speed of 12Mbps, that's about 1.2% the capacity of their line. Assuming usage was evenly distributed throughout the month (which it isn't) then you'd only need 144 kbps per customer for everyone to get full speed. Even on VM where average speeds are over double that, 3.6Mbps is still over ten times the bare minimum in worst case scenario, supposedly. Which really isn't that bad.

Re: Looks like Virgin are determined to flush out old modems
 

yeah if the shared pipe is fat enough high contention ratios can be reached, of course some isp's abused this, when 50:1 was removed from the adsl spec (adsl max launch) it became apparent plusnet were contending at over 200:1 for a while and the result wasnt pretty :)

Re: Looks like Virgin are determined to flush out old modems
 

Cheers.

Re: Looks like Virgin are determined to flush out old modems
 

I had a super hub replaced with super hub 2 due wireless dying, they sent me one for self installation and a letter in the box saying I send it back to freepost address in letter, there was no address on the letter , and phoned serveral times they said they would send me a bag to send it back which
never came so in the end I put in the box along with a old modem which was never taken away along with the router . and sent it (just added)freepost to address on box . which was for if parcel was undelivered.

that was only a couple of months ago, they did not seams bothered then about getting them the one time when I phoned I was told I could take them to a recycling centre

Re: Looks like Virgin are determined to flush out old modems
 

Never said it was.

I was thinking about the Netflix news the other day saying they need 1.5MB to stream ultra hd. Well, if VM can deliver 3.6MB to everyone, well..., sorted!

Thanks for your comments too.

I should just add that out of those 75 channels of the 750Mhz of bandwidth, several of them are unusable due to interference issues and other things.

I'm really just trying to find out what VM can deliver today in terms of capacity and what they need to do for tomorrow. I keep reading that FTTC services will far outstrip VM soon in terms of capacity, but I'm not so sure.

If it were a choice between VM's cable network or Openreach/BT's network, I know which one I'd opt for which can deliver greater capacity without too much additional outlay.

Re: Looks like Virgin are determined to flush out old modems
 

*units corrected for consistency with previous discussion

[OT comment]

You will be disappointed - Ultra HD will need around 15Mb/s

http://www.dslreports.com/shownews/N...15-Mbps-125924

[/OT comment]

Re: Looks like Virgin are determined to flush out old modems
 

Agreed on contention ratios not being such a bad thing. If you want 100Mbit of uncontented bandwidth, be prepared to pay about £800 per month for it - and that's still cheap. The speeds we get for the price we pay are unrealistic for purely uncontented bandwidth. Yet as most people never max their connection, it's really not that big a deal. I believe Airlines do the same thing with plane tickets, as about 10% of passengers tend not to show up - hence why you occasionally get asked if you want to get the next flight instead or bumped up a class.

Re: Looks like Virgin are determined to flush out old modems
 

It's not far off unlimited cinema tickets or railway season passes - the general assumption is not everyone will be using it all the time. Bus companies would go out of business if all season ticket holders were using the bus 24 hours a day...

Indeed, Netflix "ultra HD" or in my view, bog standard what-HD-should-have-been-right-from-the-beginning streams on average around 12Mbps and so saying you should have a 15Mbps connection isn't far off. That said the UK average isn't far off that either, so it won't be long before most people can stream the highest quality widely available stream, but still doesn't mean anywhere near everyone will be doing it simultaneously.