120M : Looks like Virgin are determined to flush out old modems

[Neptune_Twilight]

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.

[Sephiroth]

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!

[Rankrotten]

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?

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[General Maximus]

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.

[Kushan]

Originally Posted by Rankrotten

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?

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.

[Rankrotten]

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.

[General Maximus]

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.

[qasdfdsaq]

Originally Posted by Kushan

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

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.

[Sephiroth]

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.

[Kushan]

Originally Posted by qasdfdsaq

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.

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?

[qasdfdsaq]

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 ----------

Originally Posted by Kushan

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?

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.

[Kushan]

Originally Posted by qasdfdsaq

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

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

Originally Posted by qasdfdsaq

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.

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).

Originally Posted by qasdfdsaq

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.

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.

[potbelly]

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

[Kushan]

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

[qasdfdsaq]

Originally Posted by Kushan

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

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

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

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.

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).

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.

Can the CMTS switch one of those two users "on-the-fly"?

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).

Can it do that as soon as channels 1 and 2 become maxed out?

Yes.

(or rather, once channels 1-4 go above 50% capacity).

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%)

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?

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

What I mean is, how quickly can the CMTS tell the modem that it needs to jump channels?

Several times a second.

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?

Yes

There's another scenario as well. Assume the CMTS is load balancing effectively, but the area has heavy use.

Then you should still notice no difference.

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.

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.