Subject: Re: IP Addressing in MANET

From: Charles Perkins <[email-masked]>
Date: Fri, 6 Mar 1998 07:18:45 -0800 (PST)

Chip,

> Thank you for your patient explanations.

Thank you for your relentless probing.  These are questions that
need discussion and resolution.

> REPLAY:

Check, check, and check.

> 1. How does this affect the IP forwarding engine in each
>    host/router? Are these wireless IP addresses just entered
>    as 32-bit-long matches? Note that this has the slightly
>    perverse effect of favoring a wireless route over
>    (say) an Ethernet, since the Ethernet IP address will
>    undoubtedly have a shorter mask.

The situation as far as I have designed it in the past is
that all the routes look like host routes.  If you don't have
infrastructure, then you may not have aggregation based on
network address.  If you have an ad-hoc node attached to
an infrastructure Ethernet, then I think you should use
Mobile IP (e.g., [epmcc97]) to make them whole.  I never looked
at the case of having a whole Ethernet floating in ad-hoc land.

> 2. I guess we're already talking about modifying the
>    forwarding path, right, since in general we will forward
>    packets back out the same interface they came in on?

We didn't modify the forwarding path especially for this, although
it's true we hacked it to death for route optimization.

> 3. With this scheme, haven't we totally given up on the
>    ideas of IP Broadcast and IP Multicast? If there's no
>    notion of an IP-addressable subnet, these services
>    cannot be based on any standard IP mechanisms.

Absolutely not!  In fact, an IP Multicast solution is likely
to emerge from these quarters before too much longer, if I can
just detach some of these alligators here ...  Besides -- why
is there a problem?  IGMP doesn't depend upon aggregation of
the multicast address space anyway ...?  Or am I missing
something here?

> Thanks again for your patience,

Likewise, and thanks for the discussion.

Regards,
Charlie P.

@InProceedings{epmcc97,
        author = "Hui Lei and Charles E. Perkins",
        title = "{Ad Hoc Networking with Mobile IP}",
        booktitle="{Proceedings European Portable and
                   Mobile Communications Conference}",
        year = 1997,
        month = oct,
        pages = 197--202,
}  (which you can get from my web page http://www.svrloc.org/~charliep)