Re: [Autoconf] Updated ad hoc addressing model document

["Charles E. Perkins" <[e-mail]>]

Hello Teco,

On 2/4/2010 6:22 AM, Teco Boot wrote:
>
> Up to now, all IP addressing models I am aware of provide 1-hop L3
> communication between nodes that have L2 connectivity.
>    

If I get your point, what you mean is that when two nodes
share a link, they can use L3 protocols to communicate.

As far as I understand it, the addressing model does not
change this.  IP supports point-to-point communication
between such "adjacent" nodes.

How adjacency is discovered is usually considered
out of scope.  Either subnet prefixes are "assigned"
(suddenly, it doesn't look like a Manet anymore)
or "discovered" (oops, we're running new protocols)
or "assumed".  In the latter case, you'd better make
your assumptions minimal, or else (protocol-wise)
you are moving back into traditional a fixed network
model.  I know it's nicer there and all.


> The proposed addressing model for MANETs breaks this. Now there
> is a need for something clever. This clever thing could be
> stopped.
>    

I do not agree with this.  See above.  I also do not
agree that we must avoid being clever.  However,
I agree that simpler is better, all the while adhering
to Einstein's famous dictum.

> There is no reason not using link-locals for 1-hop traffic.
> If you say this is a particular and specific setup, is this a
> qualification for IPv6?
> If not, what are you referring to?
>    

I read this, and had to smile.  Of course there's no reason
to avoid link-locals for 1-hop traffic as long as you _know_
it's one hop.  In fact, blast away.

But for people who are running networks without such
comforts, assurance of availability for a L2 communication
channel is often necessary or at least highly desirable.
Then suddenly your link-local address is potentially
(a) invalid (b) unavailable or (c) ambiguous.  These
are normally considered poor indicators for IP-based
communications.

And that is the problem needing solution in the
general case, which has motivated the current form
of the addressing model document.

Regards,
Charlie P.