--------
Note: I'm moving discussion of an offline thread to int-area and
manetautoconf to broaden the discussion.
Background: myself and others have expressed concerns about the
autoconf charter. IMO, the current charter has some significant issues
and the focus of the work needs to be redirected if this effort is
going to have a good outcome.
I'll post some background messages and then reply to an ongoing
thread.
Here is an excerpt from an earlier message:
From: Thomas Narten <[EMAIL PROTECTED]>
To: Margaret Wasserman <[EMAIL PROTECTED]>
cc: [EMAIL PROTECTED], Ralph Droms <[EMAIL PROTECTED]>,
Bob Hinden <[EMAIL PROTECTED]>,
Bernard Aboba <[EMAIL PROTECTED]>, Alex Zinin <[EMAIL PROTECTED]>,
Mark Townsley <[EMAIL PROTECTED]>,
Brian E Carpenter <[EMAIL PROTECTED]>, [EMAIL PROTECTED],
[EMAIL PROTECTED]
Date: Tue, 27 Sep 2005 11:51:16 -0400
Subject: Re: AUTOCONF Chartering Call
Hi. I just looked at what I assume is the most recent charter
(margaret sent it out on sept 22).
Second, looking at the charter, I think the first three paragraphs
completely miss the most important aspect of this work...
>Ad-Hoc Network Autoconfiguration (autoconf) Working Group
>
>Chairs:
>Shubhranshu Singh <[EMAIL PROTECTED]>
>Thomas Clausen <[EMAIL PROTECTED]>
>
>Internet Area Directors:
>Mark Townsley <[EMAIL PROTECTED]>
>Margaret Wasserman <[EMAIL PROTECTED]>
>
>Internet Area Advisor:
>Margaret Wasserman <[EMAIL PROTECTED]>
>
>Mailing List:
>
>General Discussion: [EMAIL PROTECTED]
>To Subscribe: [EMAIL PROTECTED]
>
>In order to communicate among themselves, ad hoc nodes (refer to RFC
>2501) need to configure their network interface(s) with local
>addresses that are valid within an ad hoc network.
yes. But this is not enough to communicate. There also needs to be a
model/framework/architecture that defines an "ad hoc subnet":
- what is the subnet model? I.e., for a collection of links, what
are the boundaries of a "subnet", where each node is part of the
same ad hoc network?
- how are packets forwarded within a subnet? How is address
resolution done? How does a sender decide whether a destination on
the "subnet" is directly reachable, or is reachable through a
forwarding node?
- How is multicast traffic distributed within the subnet?
- in IPv6, how are RAs distributed?
>Ad hoc nodes may also need to configure globally routable addresses,
>in order to communicate with devices on the Internet.
Depending on the answers to the questions above, this may not be an
issue at all. I.e., global addresses could be distributed via RAs. Why
(or why not) is this insufficient?
>From the IP layer perspective, ad hoc networks present severa
>challenges. Unlike in the traditional IP networks, each ad hoc node,
>besides being a traffic end-point,
>should be capable of forwarding traffic destined for other hosts.
This would seem to be making assumptions about what the subnet model
is. I.e., how one delivers packets to other destinations on the same
"ad hoc" subnet. How is that done? Is that what this WG needs to
decide, or has this already been decided? If the latter, where is that
documented?
>Additionally, nodes constituting an ad-hoc network do not share access
>to a single multicast-capable link for signaling.
so a key architectural question is whether an "ad hoc subnet" will
emulate multicast service. And if not, what the implications are and
whether that is actually a desirable direction to go in.
Has this issue already been decided? Is this WG supposed to figure
this out and come up with an approach/solution?
>Many protocol
>specifications used in the traditional IP networks e.g. RFCs 2462,
>2463 etc. do, however, assume that subnet-local signals (e.g.
>link-local multicast signal) are received by each of the hosts on the
>particular subnet without being forwarded by the routers defining the
>subnet boundary. Hence ad hoc networks, (as defined and understood by
>the IETF MANET WG) supporting routing protocol at the network layer in
>order to provide multi-hop communication, cannot use these protocol
>specifications as-is.
A reason my previous question is so critical is whether we are better
off emulating multicast (so all multicast applications work as is), or
whether every higher-layer protocol that uses multicast has to be
rewritten to work over an "ad hoc subnet"? I sure hope we aren't
doing the latter...
>The main purpose of the AUTOCONF WG is to standardize mechanisms to be
>used by ad hoc nodes for configuring unique local and/or globally
>routable IPv6 addresses.
IMO, this above is the tip of the iceberg, and it is the larger
questions that must be dealt with. The addressing part is just one
component of the bigger picture, and without a coherent bigger
picture, none of this makes sense.
>The ad hoc nodes under consideration are,
>once configured, expected to be able to support multi-hop
>communication by running the MANET routing protocol developed by the
>IETF MANET WG.
Which document is this? Is there just one?
And, is this a routing protocol that carries unicast, or is this the
definition of the abstract service an "ad hoc subnet" provides?
Thomas
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