Re: [homenet] Let's make in-home ULA presence a MUST !?

Michael Richardson <> Tue, 21 October 2014 13:17 UTC

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From: Michael Richardson <>
To: Pierre Pfister <>
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Date: Tue, 21 Oct 2014 09:17:35 -0400
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Cc: James Woodyatt <>, HOMENET Working Group <>, Ted Lemon <>
Subject: Re: [homenet] Let's make in-home ULA presence a MUST !?
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Pierre Pfister <> wrote:
    > 9.1.2.  Advertising a ULA prefix

    >    A router MAY start advertising a ULA prefix whenever the two
    > following conditions are met:

    >    o It is the network leader.

    >    o There is no other advertised ULA prefix.

I am concerned about this part.

Consider a home automation LLN, installed at home construction time, and
therefore provisioned with a ULA by the installers.  There is gateway from
the LLN to the home network, which likely has a dangling cable until the
owner moves in.
It is useful for that cable to advertise a ULA that can be used by various
parties (installers, realtors, home owners camping on the living room floor
while wait for the moving van) to control the home.  We can argue about
whether or not this gateway will be an application layer gateway, or a
router into the Home LLN; I would claim that it will be both for a long time.

okay, so it seems that there is always an advertised ULA from the LLN.
Should the homenet use that one, or should it somehow know to ignore it for
addressing purposes (accepting routing for it, though), and create another

Maybe the word "advertised" here is mis-understood.

Does it mean via Router Advertisements, or does it mean via HNCP? Probably
that's explained in some other part of the draft.   I think that the HNCP
would permit the network leader to *defend* it's ULA, not just advertise it.

Michael Richardson <>ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-