*BSD News Article 94216


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From: udomunk@ertgseq.du.gtn.com (Udo Munk)
Subject: Re: Cheap ISDN solutions [was: What's the state of ISDN support?]
Organization: Europipe GmbH, Germany
Date: Tue, 22 Apr 1997 20:26:56 GMT
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Tony Griffiths (tonyg@OntheNet.com.au) wrote:
: If you're talking about the "local exchange" box's switching fabric,
: then it has plenty of time slices available.  In the case we are
: discussing, the 64Kbps bit stream is coming in on the 144Kbps BRI and
: then being mux'd into (I presume) the ISP's PRI 1.5Mbps stream.  I don't
: see any bits flying across the Telecom's 'backbone' here!

If you dial and got a connect you are ready to send 64Kbits of data from
point A to point B, you don't want so send from point A only to the
switching device of the provider. To connect point A to point B the
switching device of the provider reserves a time slot on the multiplexed
backbone, so that you can send your data anytime you want, as long as the
connection is active. If you disconnect the time slice you got on the
multiplexed backbone becomes free for usage by others again.

: This is the reason why it is SO cheap.  All of the hardware used in the
: call is effectively dedicated to the pairs of wires involved and is
: there, powered up and working, regardless of whether there is a call
: established or not...

Nope. For that you pay the basic monthly fee, for usage of bandwith
there is an additional fee (for a dialup connection). Real bad is
that they don't charge for bandwith only, but also for distance.
The ISP's I use don't do that.

: If anyone should be complaining, it should be the ISP because the
: long-held call is holding up one of the B-channels of the PRI.  If the
: call is to a business (ie. telecommuting) then enough B-channels have to
: be provided to cater for the maximum number of simultaneous calls.

But imagine, not only the ISP has a limited number of B channels,
also does the telco provider (on the systems with the dialup customers).

: I believe that the case we are discussing is telecommuting where the
: $60/m is the ISDN rental to the local switch provider.  Do you pay that
: much for your telephone rental?  The only difference (in the case of

In Germany a line with 2 B channels and a bus termination costs DM46
per month. For a local call we pay between DM4.80 and DM1.80 (not
quite sure if that is right, someone please correct me) per hour,
depending on time of day, weekend, holiday, whatever. You don't want
to know what they charge for > local call. A permanent line is DM700
per month (without installation costs).

: Australia) is a jumper on the line card in the RIM box down the end of
: the street saying that this is ISDN rather than analogue!  The called
: party is also paying for their end so effectively ALL of the
: intrastructure being used IS being payed for as far as the Telco is
: concerned.

Really, no costs for connections? Cool, hope the Australian telco
provides the same service here for us next year then, because the
German telco doesn't do that. I definitely would love it to see
my telco provider bill drop down to nearly zero, AU$60/m that is :)

: In Australia, the price cross-over point between an SVC and an SPC
: (Semi-Permanent Connection; Telstra doesn't offer REAL PVC's) is 2 hrs
: per day.

More here I think, but that depends a lot on the time of day you use it.

: In fact, an 'idle' B-channel is simply sending idling bits (flags).  I
: would sincerely hope that the switches are smart enough to NOT send idle
: bits across the country/world!!!  In other words, an idle B-channel
: should not be consuming bandwidth on the Telecom's long-distance fibres.

It is not a packet switching network, it's not connectionless, it's not
TCP/IP. Instead it's a protocol to transfer an unknown 64Kbit/s bitstream
in realtime between two connected endpoints, which is technically very
different.
If you want to send all 0 or 1 bits you can do that, the bandwith you pay
for is yours for whatever you want to use it. Remember it wasn't designed
for running an idle TCP/IP connection, the transport layer doesn't have
any idea about what your data bits mean, the term idle doesn't exist if
you need to transfer an unknown bit stream in realtime.
On the system of the telco provider you use 64Kbits/s bandwith if connected,
what they do on the long distance fibres I don't know, wasn't my playground.

: I don't demand anything...  Being a 25% shareholder in a smallish
: regional ISP I can tell you that we don't subscribe to the "All you can
: eat for almost no $$$s!" philosophy.  We have bills to pay, and our

Yep, not an ISP, but I don't do that either.

: employees don't work for peanuts.  And then we want to see some return
: for the LARGE number of hours that all the directors put in to keeping
: the business running and growing the way it is.

And the telco companies of course don't have the same problem? <g>

: However, if an ISP offers 24x7 ISDN at a fixed low price then they have
: to live with the consequences of their decision.  If it's uneconomic,
: then they will simply have to change their policies or go our of
: business.  Noone else is going to protect them from their own stupidity!

That is correct, when they sell that to you, you pay for that and they
are responsible to provide you with that. But a dialup connection
is not for using 24x7, that's what they offer permanent or semipermanent
connections for.
--
Udo Munk	http://ourworld.compuserve.com/homepages/Udo_Munk/