Re: [Snac] Relax the requirement on a single 'root' ULA prefix generated by stub router?

[Erik Auerswald <[e-mail]>]

Hi,

On Thu, Aug 24, 2023 at 11:49:12AM +0000, Esko Dijk wrote:
> 
> Thanks for the summary of points.
> 
> > A host implementing the RFC 6724 section 10.6 procedure would detect
> >    the stub router's 48-bit ULA prefix on the AIL as local.  
> 
> If there are say N stub routers, each with own stub network, there
> would be N different ULA prefixes.
> [...]
> We assume also that the case of one auto-assigned ULA prefix and one
> GUA prefix on the AIL is not applicable, since the stub router only
> assigns the ULA prefix if there's nothing else already assigned.

The current draft seems to rely exclusively on RFC 4191 type C hosts by
advertising stub prefixes as off link on the AIL.

Always using a single ULA prefix per stub network, combined with
advertising a subnet from this ULA prefix on the AIL as on-link, could
be an additional method to also support RFC 4191 type A/B hosts that
implement RFC 6724 section 5 rule 5.5.  Such a host would use a ULA from
the stub network's prefix as source address, and would use a stub router
connected to that sepcific stub network.

The RFC 6724 section 10.6 procedure is not even required for this to work.

An explicit requirement for hosts to implement the behavior of RFC 4191
type C to work with SNAC would IMHO improve the draft.

Best regards,
Erik