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Re: dry pair
From: Ian Mason <nanog () ian co uk>
Date: Sat, 30 Aug 2003 00:43:37 +0100

At 23:03 29/08/2003, Joel Jaeggli wrote:

On Fri, 29 Aug 2003, Patrick Felt wrote:


> If not,
> how would the alarm company get the signal pushed through the fiber, and
> could that be done with the dsl signal?

The alarm companies need to deliver extremely small amounts of data which
can range from make or break circuits to 60 300 or 2400bps data for things
like building control systems, that's a considerably different problem
than try to ram 1-7mb/s through a 25,000 foot long piece of wire.

Not necessarily, the bit rate may be higher. Good modern alarms use a cryptographically secured bitstream to provide the anti-tamper part of the line protection. A cryptographically useful message size with a reasonably short delay between 'raise alarm' and 'indicate alarm' requires a fair bit rate.

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