Re: [nemo] RE: draft-ietf-nemo-home-network-models-05

[Alexandru Petrescu <[e-mail]>]

Pascal Thubert \(pthubert\) wrote:
> Hi Mattias;
> 
> Yes, the idea is that the prefix is generally shorter than /64.
> 
> We had long discussions in this ML about autoconfigs with shorter 
> prefixes (Alex?).

Yes, I agree that a host should auto-configure an address from an RA
with a prefix shorter than /64 - fill the intermediary bits with '0'.
However, capacity of auto-configuring an address from prefix shorter
than /64 is not a support for the aggregated mode itself.

I also support /56 on the home link and /64 on the moving network links.
  That's as natural as it gets.  But this does not mean I support mixing
the home link with the moving network links into an L2-VLAN-proxy-ND
that may work in some single places but is by no means the standard at
deployed Access Routers.

The main reason why the aggregated mode is not supported by RFC3963 is
that it breaks the scope of ND (LFN receiving RA from AR?  and from HA?)
and turns MR into an MR and a bridge at the same time.  There's no
software that allows a machine to dynamically change from bridge to
router without loosing ongoing communications.

> But yes, NEMO should work in theory with a shorter prefix assigned to
>  the Home Link.

Yes, NEMOv6 as specified by RFC3963.  But RFC3963 does not support the
aggregated mode.

> Note that NEMO does not require autoconf operations; and last that I
>  know, a Cisco router will not auto-configure an address on a prefix
>  that is shorter than 64.

You seem to imply that a router _will_ auto-configure an address from an
RA with prefix /64.  YEs?  A "router" fixed or mobile shouldn't
statelessly auto-configure an IPv6 address at all, be it prefix /64 or
shorter, no?

> So there might be some implementation specific issues to do at least
>  autoconf. DAD should work, though, which is what we need. Would I, 
> personally, recommend the aggregated mode? I don't think so. But if a
>  good half of the population starts with that mode in mind, it's good
>  to document the pro/cons, and hopefully, at the end the day, they 
> will make the right deployment decision for their needs...

Who recommends the aggregated mode?  I don't.

Alex