Re: SEND/DIID interoperabilility (was: Re: [rfc2462bis issue 275] DAD text inconsistencies)

[Pekka Nikander <pekka.nikander@xxxxxxxxxxxxxx>]

Nick,

> My assumption is that SEND WG will adapt to the changes that RFC2462bis
> will make.  So if we tweak 2462 to require configuration of a 
> link-local
> address per suffix, SEND-CGA nodes will do this.  This will then 
> prevent
> (well, detect) collision as discussed above.

Well, strictly speaking, a (pure) SEND node cannot configure a 
link-local
address with such a suffix, since the resulting address will not be a
SEND address.  The CGA test will fail.

Let me clarify:

  1. Say that a (pure, strict) SEND node configures a new
     global address P::A, where A is computed by the CGA
     algorithm:  A = cga(public key, prefix P, other info)

  2. If a SEND node now would like to configure a link local
     address fe80::A, it (strictly speaking) cannot do that,
     since for fe80 it MUST use a different suffix, L,
     where L = cga(public key, prefix fe80, other info).

Putting that aside, a SEND node could well *defend* the address
fe80::A for DAD/DIID purposes, but it would never actually use it.

--Pekka Nikander


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