Re: [Autoconf] Autoconf addressing model

Alexandru Petrescu <> Wed, 04 March 2009 17:29 UTC

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Date: Wed, 04 Mar 2009 18:29:17 +0100
From: Alexandru Petrescu <>
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To: "Stan Ratliff (sratliff)" <>
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Subject: Re: [Autoconf] Autoconf addressing model
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Stan Ratliff (sratliff) a écrit :
> First off, you *can't* arbitrarily limit subnets to 25m. 25m from 
> what? The center?

Yes, an area of 25meters with a wifi access point in the center.

> And, how do you designate the center? Do you constantly re-calculate
>  the center based on movement?

No, not constantly re-computed.  But have a fixed view at a point in
time.  Saying everything varies isn't helpful either.

> Also, from a radio perspective, how do you tell how far apart you are
>  in the first place? Do you suppose that all radios have GPS? That's
> a non-starter, because GPS signals aren't always available.

No I didn't suppose GPS is available on each device, it wouldn't work
well under foliage.  Just a rough evaluation of a specific link-layer
radio range, correspondign to widely used networks.

> And what about the wired MANET case brought up by Christopher
> Dearlove? Should we limit the cable runs?

YEs, certainly.  All cabled link-layers have specific limitations on 
their lengths: 2m USB, 50m Ethernet Category6 (IIRC) and so on.

> I could understand (but
> wouldn't really like) the notion of limiting the discussion to links
> that are transitive; but placing some arbitrary distance limit that's
> based on 802.11 just doesn't cut it for me.

802.11 is being used widely, no reason to ignore.

I'd happily accept to add another specific limitation, from the 
link-layer of your choice.  And be speecifically addressing these two 
link layers.  And maybe three.  No more than three.

I find addressing them all to be difficult for me.

(about single point of failure being destroyed by a falling tree:
  problem could be addressed at its layer: don't move the command center
  under trees risking falling); or maybe have two command centers, but
  specificllay two, not an arbitrary large unknown number.