LinuxSA Mailing list archives

  From: Glen Turner <glen.turner@aarnet.edu.au>
  To  : linuxsa <linuxsa@linuxsa.org.au>
  Date: Sat, 02 Dec 2000 12:13:10 +1030

Re: Broadband options in SA (was Re: ADSL talk suggestion)

Jake Hawkes wrote:
> 
> Didn't Lucent do some research into this, and found that the effects are
> actually negligable? I didn't belive it when I heard it .....

The crosstalk effects may be for telephony, as most phones
already filter out 50Hz-60Hz to reduce pickup hum.

The real issues are life cycle questions, like what happens
with the insulation starts to break down.  Do you then need
to turn off the power to the street to safely repair a phone?

A street-wide power diversion takes about six weeks to organise
and costs more than $5,000.

This is more than acceptable when running fiber, as the failure
modes are relatively safe[1].  Also DWDM gives a nice failure scenario,
as by puting some gear at both ends you can run all the traffic
down just two non-degraded fibers.

Most facilties sharing schemes involving copper usually involve trench
sharing, not conduit sharing.  You see this in new suburbs quite a
bit.

Fiber is a bit unusual, in that it less risky to run in the same
conduit as power.  However, merely entering the pit still requires
a power diversion.  So the question is if this ongoing cost is
less than the capital cost of additional trenching.

Glen

[1] Essentially, no one enters a pit until the power is off and
    the lasers are off.  There's some nice fiber switches with
    locks that allow you to 'switch off' the fiber and take the
    key with you into the pit.  It's likely that these will be
    built into the next generation of long-haul laser units.

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