120M : (Advice) Thinking of leaving Virgin Media 120mb for BT Infinity up to 76mb

[horseman]

Originally Posted by blue166

Many thanks for your answers, ....

Not a trick question but a genuine interest in how you performed a Risk Assessment and comparative evaluation on potential advantages of BT21CN over VM?

Mainly because despite being a VM customer consistently on a low end tier for 15yrs I've also regularly looked at alternative ADSL ISPS's and obviously in latter times then BT's Infinity.

So some criteria and "intangible risks" I've looked at that probably only relates to my limited usage profile and not any avid gamester or torrenter, downloader or video streamer:

1. Just as one can't statistically evaluate the reliability/performance of an areas VM tier from the VM H&S forum site posts neither from my many cursory reviews of BT Support site posts can you achieve any better objective evaluation of Infinity?

2. Probably like many others I lazily attribute an advantage to opting for "bundles" that include my eclectic needs for Phone, TV and BB as it results in a more logistically simple single payment methodology. I appreciate more discerning subscribers will evaluate their specific specialised needs for gaming etc will attribute more "Value add" in perhaps selecting different services from different ISP's?

3. Old IT habits die hard so over 4 decades (I'm permanently retired now) I still retain and apply concepts of Disaster Recovery,Continuity of Production, Back ups and Risk Assessment strategies to provide commensurate redundancy for telephone,TV and broadband irrespective of "main" ISP(s) involved.

4. Therefore based on the above criteria I notice the following crude comparisons between BT & VM:

a) BT seem to also have an Off shore (Indo-Asian) call centre support methodology? Which appears to have as much credibility and derision as VM's Level1 offshore support!

b) BT seem to have some satisfaction guarantee(conceptually similar to VM's 28day one) with some forum posts suggesting from 10 days to even 90days!?

c) BT seem to be a far more realistically conservative in their initial speed estimates prior to installation, thus many find their actual installed data rates exceed or always consistently come within 10% of that initial advertised(?) estimated prediction. However like VM's reliability during a fixed term contract there's no indication of how easy it is to get compensation for degraded service nor exit a contract term without penalty?

d) However there's also much confusion over how DLM is instigated with diametrically opposed views of whether this is 10days on FTTC or 48hrs and what user provoked multiple Modem reboots within a certain period will re-invoke DLM triggers with a risk of IP Profile being changed to a lower data rate?

e) Equally this leads to problematic issue of re-setting the IP Profile when DLM may have been artificially confused by aforementioned user actions?

f) Thus guarantee of service speeds also seem confusing with only some tenuous guarantee related to 15Mbps minimum and no other distinction between Infinity 1 or Infinity 2 data rates not meeting it's original installed (or install + 10day) rate at some time in the future?

g) While "contention","congestion" or "over-utilisation" appear further back in BT F/O network relative to VM's last mile + HEAD END, there's still some disconcerting pointers on BT Forum that circumstantially point to BT can user connection increase causing suggestion? No doubt related to "crosstalk" before "vectoring" rollout but still a potential issue perhaps in some areas?

h) As regards TV bundling then BT's Infinity sales spin seems nothing more than a FreeView service that requires a terrestrial aerial anyway? As such apart from an STB it doesn't seem to provide any additional value add over a subscribers own Smart TV with embedded Freeview anyway?
BT also seem to leverage Sky as another option but not AFAIK any significant TVIP to equate with VM's TV STB service??

i) then there's the rather discouraging concept of BT OR actually potentially charging for tech visit if NFF?

j)Of course their Forum support does appear to have a more hands-on and responsive BT level2 team (that's not intended as any denigration of any individual VM's forum team members but merely the higher management commitment to staffing resource support levels on BT)?.

Now while I hopefully try and retain some objectivity there are undoubtedly many incorrect interpretations I've made in my cursory comparisons and thus why I'm genuinely interested in other opinions particularly yourself Blue that has already endured some of VM's reliability issues in past for a protracted period?.

FWIW I've used BT(or GPO back in the age of dinosaurs with 300baud jack plug modem) in the past and as a landline and later via dialup V56 and also when migrating to NTL digital TV(+embedded CM) + telephone but still retained BT telephone as backup until mobiles reduced in price and became a viable backup to landline.

However it just seems as much confusion caused by "myth", mis information and probably to a lesser degree "marketing spin" on BT fora as that found on VM fora?
The grass is always greener to some extent no doubt?

That said my "half-a-gut" feeling is that on the whole BT Infinity is on average more reliable and consistent in basic data rates and latency generally than VM and I'm still tempted (like Seph already has done for some time now) to use BT Infinity bundle as a "back up" to replace my current FreeSat,Sky and MobileBB dongle alternative strategies?

[MaverickJesus]

I pre-emptively decline your invitation to any kind of social gathering - I think the blistering excitement of the discussion might kill me.

[kwikbreaks]

The DLM question is easy to answer. DLM runs 24x7 on BTw systems from day 1 onwards. The only significance of the 10 days for ADSL is that the lowest sync rate during the first 10 days is recorded and no fault is accepted if the sync rate remains within 70%(iirc) of the recorded minimum. I don't know what it is with FTTC but quite probably the same.

The way it works is simple too. There is no "line training" - how do you train a length of twisted pair cable? Nor any "test to see what speeds can be achieved" on BTw systems although I believe Sky may start artificially low then go higher. All that happens on BTw is that there is a default target noise margin of 6dB set and the router/DSLAM negotiate the highest sync rate with that margin at the time. Increasing noise may cause the margin to fall. If it falls far enough sync is lost and then re-established still with that noise margin so as the noise was higher than means a lower sync. This is an ongoing process. If the software determines there have been excessive resyncs the target margin gets increased in 3dB steps up to (iirc) 15dB in an attempt to achieve stability. A long period of stability (typically a couple of weeks) is rewarded with a reduced noise margin - only down to 6dB although some ISPs will manually set it at 3dB. Really bad lines can be set at a fixed rate rather than rate adaptive.

A BRAS profile (maximum datarate) is set based on sync. The old system was an immediate reduction for lower sync and delayed increase - sometimes as long as 5 days. The newer system makes closer to instant changes but as it was developed after the days when I took much of an interest in this stuff I don't know the details. The equipment datarate gets passed to ISPs and they sometimes have delays updating theirs so you can get "stuck profiles" with lower data rates than the sync could support.

The problems I saw in my days on cable were what I suspect were cowboy installers juggling customer connections to cabinet taps leading to short outages and twice in my case out of spec power levels that had to be fixed. The biggest problem though was congestion which kept raising its ugly head and I think is down to the low capacity local pipes cable has coupled with VM's determination to keep "unlimited" in their advertising.

I never really had many problems in my ADSL days apart from a duff line which never got fixed when I moved house and that drove me to cable. The sort of problems I saw reported on boards were frequently down to poor internal house phone wiring. Other issues after ADSL had been around a few years were cheapskate ISPs cramming far more customers on the expensive BT kit than it could sensibly support leading to huge peak time slowdowns. Early LLU operators for the most part were first rate but some of the later arrivals were poor too.


I haven't been on FTTC long enough to see any problems at all so far.

[qasdfdsaq]

Originally Posted by kwikbreaks

All that happens on BTw is that there is a default target noise margin of 6dB set and the router/DSLAM negotiate the highest sync rate with that margin at the time. Increasing noise may cause the margin to fall. If it falls far enough sync is lost and then re-established still with that noise margin so as the noise was higher than means a lower sync. This is an ongoing process. If the software determines there have been excessive resyncs the target margin gets increased in 3dB steps up to (iirc) 15dB in an attempt to achieve stability. A long period of stability (typically a couple of weeks) is rewarded with a reduced noise margin - only down to 6dB although some ISPs will manually set it at 3dB. Really bad lines can be set at a fixed rate rather than rate adaptive.

Not quite. The system doesn't tend to modify target SNR as often, but actually prefers to put your line on a capped profile, with a minimum and maximum speed it can sync at. With excessive resyncs, it'll both reduce your maximum line speed directly (not via adjusting SNRM) and increase interleaving/INP depending on the cause.

It can take weeks or months for a capped profile to be automatically removed from your line, and often it goes up gradually. As an example my line was capped down to about 47Mbps after I messed about with it for a while, and gradually went back up to the full 80Mbps by increasing in approximately 5Mbps steps every week or so.

A BRAS profile (maximum datarate) is set based on sync. The old system was an immediate reduction for lower sync and delayed increase - sometimes as long as 5 days. The newer system makes closer to instant changes but as it was developed after the days when I took much of an interest in this stuff I don't know the details. The equipment datarate gets passed to ISPs and they sometimes have delays updating theirs so you can get "stuck profiles" with lower data rates than the sync could support.

The newer system is instant. Or rather, every time you reconnect your PPPoE session, the server obtains the live sync rate from the DSLAM (well, not directly) and sets your IP/BRAS profile to be exactly 96.8% of that.

IP profiles are only adjusted upon PPPoE reconnect, so if your line resyncs without your PPPoE session resetting, your IP profile will not adjust until your next PPPoE reconnect.

It is worth noting IP profiles *only* apply to BTw connections. LLU providers (i.e. Sky) do not have a BRAS/IP profile.

I haven't been on FTTC long enough to see any problems at all so far.

BT, in my experience, have been generally good at keeping up with capacity increases and congestion. Longest period of congestion I ever saw during my 2.5 years on BT Infinity was around 3 days.

Openreach as well, have been very proactive in keeping the cabinet loops on FTTC up to scratch. This is made easy partly because of the massive overprovisioning of spare fibre when they built the network, as well as it being a relatively new, modern infrastructure that is easily upgradeable. Each cabinet has the ability to be fed with enough capacity to exceed a dozen VM nodes.

Personal experience aside, OFCOM's national figures have shown FTTC's peak time speed losses, a key marker of congestion, jitter, and packet loss to be consistently lower than on VM, and sometimes several orders of magnitude lower.

[kwikbreaks]

Originally Posted by qasdfdsaq

The system doesn't tend to modify target SNR as often, but actually prefers to put your line on a capped profile, with a minimum and maximum speed it can sync at.

That sounds like it's new behaviour from when I last took any real interest in the idiosyncracies of BT based systems about 5 years or so ago - as soon as an LLU provider became available to me so I could escape the tyranny of BTw DLM as it was in those days and presumably still is on 20C ADSL. The LLU ISP was UKOnline using Easynet infrastructure which later got bought out by Sky. I left them after a year to go with O2 purely on price. Both were excellent.

[telfordcable]

U need mk2 openreach faceplate for FTTC

[qasdfdsaq]

Originally Posted by kwikbreaks

That sounds like it's new behaviour from when I last took any real interest in the idiosyncracies of BT based systems about 5 years or so ago - as soon as an LLU provider became available to me so I could escape the tyranny of BTw DLM as it was in those days and presumably still is on 20C ADSL. The LLU ISP was UKOnline using Easynet infrastructure which later got bought out by Sky. I left them after a year to go with O2 purely on price. Both were excellent.

The Openreach FTTC DLM is a completely new beast and quite different to the traditional ADSL DLM. It wouldn't have been in use 5 years ago.

[craigj2k12]

AFAIK there is no training period on FTTC products

[AbyssUnderground]

The other great thing with FTTC is there should be no local congestion issues with it all being fiber, unlike the limited bandwidth of copper that I believe virgin uses (not all cabs are linked with fiber).

[Kushan]

Originally Posted by AbyssUnderground

The other great thing with FTTC is there should be no local congestion issues with it all being fiber, unlike the limited bandwidth of copper that I believe virgin uses (not all cabs are linked with fiber).

Fibre has limited bandwidth as well, you know. It's just....better than copper. A lot better.

[AbyssUnderground]

Of course, but it's no where near as pitiful as copper. A single fiber can carry over 1Tbps of bandwidth. copper will never come close

[Kushan]

Probably not, but then again is BT's fibre running at 1Tbit capacity? I would have thought they'd be 1Gbps or possibly 10Gbps if you're lucky. Even copper, shielded copper like what VM has, can hit speeds above 1Gbps though I'd doubt Virgin's do.

[AbyssUnderground]

No of course not. I thought it was 1Gbps but someone in this topic said it's now 10Gbps. That's still a lot more than VM use.

[qasdfdsaq]

Originally Posted by Kushan

Even copper, shielded copper like what VM has, can hit speeds above 1Gbps though I'd doubt Virgin's do.

The biggest difference comes down to the fact each street cab is fed by multiple fibres on Openreach FTTC, each street cab is fed by less than one fibre on Virgin Media FTTN.

---------- Post added at 13:36 ---------- Previous post was at 13:35 ----------

Originally Posted by AbyssUnderground

No of course not. I thought it was 1Gbps but someone in this topic said it's now 10Gbps. That's still a lot more than VM use.

I've not done a spectral analysis of VM's copper to see how much of the spectrum they actually use - but even the copper coax can carry up to 5-6Gbps under good conditions.

[Kushan]

Originally Posted by qasdfdsaq

The biggest difference comes down to the fact each street cab is fed by multiple fibres on Openreach FTTC, each street cab is fed by less than one fibre on Virgin Media FTTN.

Is that true for all VM cabs? I know that some aren't even fed by fibre but more coax, but is it really only one fibre at most? Surely some of the busier areas have additional capacity?

Originally Posted by qasdfdsaq

I've not done a spectral analysis of VM's copper to see how much of the spectrum they actually use - but even the copper coax can carry up to 5-6Gbps under good conditions.

Seems from various stats posted that Virgin is attempting to improve conditions, though? This is well above my understanding of things but don't they seem to be at least attempting to clean up the network and boost things like modulation?