Subject: Re: Hand Configuration of Ad Hoc Nets?

From: Charles Perkins <[email-masked]>
Date: Mon, 9 Mar 1998 00:03:50 -0800 (PST)

Chip,

> I would argue that the strawman #1 choice is "not scalable".
> That is, the protocol design should make it EASY to have a
> network come together properly, and this may include features
> that check for duplicate IDs, or (better yet), rule out
> those kinds of problems all together.

In an earlier note, I alluded to the possibility of an
initialization step during which all nodes "number" themselves.
This is possible, and workable as long as new nodes have
access to the entire ad-hoc network before they claim a
new address.

It's the case of dynamic partition and healing of a network,
with new nodes coming at arbitrary times, that makes automatic
address assignment hard.  If you are willing to do without
that, then the problem seems tractable.

>      ......               I propose as a step going forward
> that any draft solution must describe:
> 
> -- what configuration is required
> 
> -- how that configuration will take place
> 
> -- what happens if things are misconfigured

How about if the nodes are numbered before they leave
the "infrastructure", and keep the same number during
their entire ad-hoc wandering?

> Is that too much to ask? I hope not. A little care in
> the protocol design now will have big payoffs in usability
> over the next few years.

I just don't see you can justify it in the general case, which
would basically require a new DAD for every node in the system
every time a new link gets established.

> -- Chip

Charlie P.

---

From: Chip Elliott <[email-masked]>
Date: Mon, 09 Mar 1998 09:15:01 -0500

Hi Charlie,

Wait, wait, wait. I'm not trying to push any protocol here,
and particularly not one like you describe! Let me just

>> -- what happens if things are misconfigured

I know this places a burden on the draft-writer, but given
the IP suite's rather sorry history of ignoring configuration
isues, it might help more than it hurts. And the node and
addressing number issues are only the tip of the iceberg.

Please think a bit about what happens if different nodes
have different route cache time-out values, and if one has been
misconfigured to have a huge value (a month, say).

And now I promise I'll sit down and be quiet.

- Chip

---

From: Bora Akyol <[email-masked]>
Date: Mon, 09 Mar 1998 07:37:11 -0700

As far as I understand there is two states to an Ad-HOC Network:

1) Connected to the rest of the world and the Internet.
2) Not connected to the rest of the world.

Consider case 2, if there are three notebook computers in a room forming
an
ad-hoc network. Do we really care that they may duplicate an address
somewhere else?
I think that address duplication in this case is not important.

In case 1, since they are connected to the rest of the world, there must
be a gateway in their network. I think that this gateway should be
responsible for address assignment via an automated protocol. If there
are two or more gateways in the MANET then they should use an
arbitration protocol to decide which one can assign addresses.

Now transitioning from 1 to 2 is automatic and no work needs to be done.

Transitioning from 2 to 1 is where problems may occur in terms of
address duplication.

There are two options in this case:
a) Renumber the addresses dynamically.
b) The gateway realizes the transition and operates in proxy mode
thereby isolating
the network from the rest of the world. So address duplication does not
matter.

Regarding the distributed directories. In state 2, since you can't be
reached by anyone else besides your MANET, directory updates do not
matter beyond your MANET.
In case 1, you need to update your directory entry in the closest
database and possibly in your home database as soon as the new address
is assigned.

The case of transitioning from 2 to 1 needs to be investigated and I
will follow up on that
later.

Please comment.

Regards

Bora Akyol

BBN Technologies