Verily I say unto thee, that Mark Kent spake thusly:
> Homer <usenet@xxxxxxxxxx> espoused:
>> Theoretically one could bond 24 64Kb ISDN channels to achieve
>> 1.5Mb/s the really hard (and expensive) way, I suppose. Also I
>> believe that each line only supports 128k ISDN2e, so he'd need to
>> have 12 phone lines too. In UK (BT) price terms, that's 12 line
>> rentals @ £10.50/month, plus 12 ISDN2e subs @ £97.47/quarter, plus
>> the cost of calls (no flat rate like ADSL), plus VAT @ 17.5%.
>> That's £7,273.91/year ($13,573.21) including VAT, but excluding the
>> cost of calls, which according to my experience might easily be
>> around £1000.00/quarter for a heavily used line, giving a
>> conservative rounded total of around 10 grand UK (20 grand US) a
>> year.
>>
>> Ouch!
>
> Why on earth would you do it that way...
Well of course I wouldn't, it's purely hypothetical :)
Also, I note I've /underestimated/ the call charges, since that's £1000
per quarter per /line/ ... I've only accounted for /one/ line, not all
12, so the actual final total would be over 55 *grand*. Double ouch!
> Even if you wanted a lot of lines as individual ISDN lines, surely
> you'd go for ISDN30, so you have only one access line?
Ah OK, I hadn't heard of that before. The last time I used ISDN it was a
residential product nicknamed Home Highway (roughly comparable to ISDN2e).
> and I see that ISDN30 rental starts at £54.57 + vat for rental, per
> quarter. All BT's prices are up on its website (ofcom requirement)
> for services where BT has "significant market power", so you don't
> need to guess, you can just look them up. In any case, that means
> that the rental figure you quote above is, by my quick calculation,
> around £6,000 per year too high.
This is where I obtained the prices for ISDN2e:
http://www.productsandservices.bt.com/btbusinessProducts/displayProduct.do?productId=BTB-5163
I'm not sure why ISDN30 is cheaper.
> ISDN call charges, again according to the price list, range from 0.85
> pence per minute for weekend off peak up to 7.9ppm for national peak
> rate. To get £1,000 per quarter in call charges, you'd need to be
> making 12,600 minutes of calls per quarter, all in peak time, or
> almost 27 days of constant peak-time calling, to national numbers, to
> get there.
At the time I was using the Home Highway product, I was using it pretty
much the same way I use ADSL now (always-on), which means 24 hours/day
background activity from the server for things like rsync (mirroring),
as well as normal usage, so each quarter I was essentially making ~90
days of constant calls 24 hours/day on two lines (channel bonded ISDN)
to an 0845 or so-called "lo-call" number, which was also my "Friends and
Family" so-called "Best Friend" number. Even including the fact that it
was discounted for being both an 0845 and a "Best Friend" number, my
call charges came to ~£1000 per quarter. I had that service for approx 2
years before ADSL finally came to town.
Ultimately there may have been a cheaper alternative at the time, but
not one for residential customers AFAIK. If I'd been made aware of such
a product than I certainly would have jumped at the chance to save £1000
per quarter.
> If you're really making that many calls *to the same number*, then
> it's most likely that some kind of leased line solution will be much
> less expensive, as your're just tieing up the switched network all
> day, every day.
I seem to recall investigating leased lines at the time, but all of the
products I looked at were in the 10K bracket, and were all oriented to
business use.
> If this is for internet dial-up, then I would think that you'd be
> getting a local rate, which would be much less expensive, but I don't
> know for sure.
Yes it was 0845 "lo-call" rates, which I believe lies somewhere in
between local and national.
>> Our 21CN PSTN switchover target is supposed to be Q3 2011. Until
>> then I'll have to "make do" with 8Mb/s.
>
> You can always have an additional ADSL line, if you need additional
> bandwidth.
ATM it's not really an issue, since I sync at 8Mb and get a steady 6.5Mb
on most days (Entanet). The cost of a second line doesn't really appeal
to me either :( Although 16Mb bonded does sound nice in theory.
> One thing to consider, of course, with ADSL, is the contention rate.
> You don't actually get 8Mbit/s, constantly, guaranteed to any
> destination, what you actually get is up to 8Mbit/s of access into
> the wider internet, shared with probably up to 30 other users, who
> might also want the same access rates... the whole thing works on
> the assumption that consumption of IP networks is, well,
> statistically muxable. Of course, this only works to a point, as
> like in the case of the PSTN, we get busy-hours.
My exchange covers 3 houses and a post office (OK, that's a /slight/
underestimation), so the contention round these parts is pretty low :)
> For ADSL2+, the maximum rate should rise up to 24Mbit/s, but
> obviously this will depend on normal transmission line issues,
> including length of the line, condition of the line and so on. You
> canna change the laws of physics.
You misspelled "cannae", Scotty :)
(As in "Ye cannae shove yer grannie aff the bus".)
Personally I'm rather apprehensive about 21CN, in much the same way as I
was about the probability of being LLU'ed without warning by my ISP, and
ending up on a dog-slow Datastream rather than my current BT-managed
IPStream. Indeed this is one of the main reasons I migrated recently,
along with my overall distaste for the company that assimilated the ISP
I was with (Tiscali bought Nildram). WRT 21CN, I simply don't know much
about it at all, so I'll reserve judgement until the reports start
flooding in.
> The presently mooted plan to do fibre to the kerb (see recent news)
> could bring as much as 100Mbit/s to every house, but again, you'd
> need to look at contention ratios and the economics of the whole
> thing - it doesn't come free.
Oh I'm more than happy to pay for a good service (£1000 per quarter,
remember), but something tells me it'll be a /very/ long time before my
muddy backwater sees 100Mb ... or even 24Mb. Right now I'm happy enough
on 8Mb.
> On ISDN30 connections, each timeslot (64kbit/s channel) is guaranteed
> to take the same route on any call either nationally or
> internationally so that any bonding equipment in use can assume that
> bits sent in order will arrive in order at the distant end.
> Furthermore, the calls are guaranteed to meet G.114 delay
> requirements, ie., not exceed 400ms round-trip delay to any
> destination, with error performance meeting G.826, and maintenance to
> M.2101 parts 1 and 2.
Interesting; thanks for the explanation. So why is ISDN2e more expensive
then, is it because it's a legacy product that takes additional support?
> Now, if you want some *serious* bandwidth, you could take a look at
> "Wavestream".
> http://www.serviceview.bt.com/list/public/current/DWDM_Wavelength_Svc_boo/1435_d0e5.htm#1435-d0e5
2.5Gb! Holy crap, that's faster than the central pipes!
--
K.
http://slated.org
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