Re: [6lowpan] FW: TID in ARO [was: "Advertize on Behalf" flag in ARO]

"Pascal Thubert (pthubert)" <> Fri, 22 April 2011 07:30 UTC

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Date: Fri, 22 Apr 2011 09:30:37 +0200
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Thread-Topic: [6lowpan] FW: TID in ARO [was: "Advertize on Behalf" flag in ARO]
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From: "Pascal Thubert (pthubert)" <>
To: "Erik Nordmark" <>, <>
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Subject: Re: [6lowpan] FW: TID in ARO [was: "Advertize on Behalf" flag in ARO]
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Hello Nicolas, Erik,

> >
> > As Pascal answered in his post, the TID is not particularly coupled
> > with RPLv1. The TID is just an extra information provided by the
> > during ND registration which dramatically simplifies node
> > but also enable DAD across a backbone of Edge Routers advertizing
> same prefix.
> > Which alternative solution would you suggest for DAD?
> DAD works fine with what we have in ARO.
> If the same EUI-64 (re)registers the same IPv6 address, then it is not
> duplicate.
> If a different EUI-64 tries to registers an IPv6 address (already
registered with
> some other EUI-64), then it is a duplicate.
> That is independent whether the check is done in a 6LR or 6LBR.
> What do you see as the problem with DAD? Can you provide an example of
> what doesn't work with 6lowpan-nd?

[Pascal] TID is not related to uniqueness/DAD. It is related to
movement. A node that stays attached to the same router would not need
it. Tragically, LLNs are not like that.
TID enables to invalidate states that have a deprecated sequence.
Typically if you want to redistribute an ND registration into something
else then you need such thing.

I listed in another post 3 issues with ND that can be fixed with a TID
(scalability, out-of-order, and anti-replay). DAD is not in the list. 
DAD works as long as the EUI is unique, which is an assumption we
accepted for this work.