Subject: [Autoconf] Is autoconf meeting in Minneapolis?

From: Carlos Jesús Bernardos Cano <[email-masked]>
Date: Tue, 04 Nov 2008 00:34:56 +0100

Hi,

	Is autoconf meeting this time? have been any progress since Dublin in
the manetarch issue?

	Thanks!

	Carlos

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From: Shubhranshu <[email-masked]>
Date: Thu, 6 Nov 2008 13:21:07 +0530

Hello Carlos, All,

Autoconf WG has been scheduled on Tuesday, November 18, 2008 1520-1700
Afternoon Session II, Salon G. Refer to
https://datatracker.ietf.org/meeting/73/agenda.html

We'd like to spend considerable amount of the meeting time on
architectural discussions, please refer to
draft-clausen-manet-linktype and draft-ietf-autoconf-manetarch-07

Also, let us know if you have any related agenda item that you would
like to discuss during the meeting.

- Shubhranshu

---

From: Carlos Jesús Bernardos Cano <[email-masked]>
Date: Mon, 10 Nov 2008 19:55:08 +0100

Hi Shubranshu, all,

> like to discuss during the meeting.

I agree we should focus on the architectural discussions. Unless we move
forward on that direction, nothing else can happen.

	Kind Regards,

	Carlos

---

From: "Teco Boot" <[email-masked]>
Date: Tue, 11 Nov 2008 08:54:52 +0100

> 
> I agree we should focus on the architectural discussions. Unless we
> move forward on that direction, nothing else can happen.

IMHO we should finish the architectural discussions and manetarch & PS
documents as soon as possible.
We don't help improve the Internet by just discussions. We have to solve
some problems.

Maybe the "old" document from Fred Templin is helpful:
draft-templin-manet-autoconf-link-00.txt

Personally, I prefer a mathematical model for MANET links and stay away from
terms like "fuzzy".

My attempt on defining a "MANET Link" model:
---
A MANET Interface has a single non-reflexive P2MP link to a set of
neighbors, a set of reflexive P2P link to a set of neighbors and a set of
non-reflexive P2P link to a set of neighbors. The sets of neighbors and the
link qualities vary over time. A characteristic of MANET Links is
interference, i.e. a transmission from a MANET Interface could influence
other MANET Links.
---

BTW, why are the two WG I-Ds expired?

Teco.

---

From: "Dearlove, Christopher (UK)" <[email-masked]>
Date: Tue, 11 Nov 2008 09:55:20 -0000

> neighbors,

"Non-reflexive" has become misused, not for the first time here.
I think the term intended is non-transitive.

Of a relationship R:
Reflexive is that for all x, xRx
Symmetric is that for all x, y, xRy => yRx
Transitive is that for all x, y, z, xRy and yRz => xRz

MANET links are neither symmetric, not transitive. It's the lack of
transitivity - and that there's nothing you can do about it directly
- that makes it most problematic. (Lack of symmetry, in the sense of
whether there simply is a link, can be handled using some sort of
acknowledgement process. Of course that may still leave asymmetry in
terms of data rates etc.)

Whether a link is reflexive (whether a node has a link to itself) is
really a matter of definition, and not very important.

> A characteristic of MANET Links is

There needs to be quite a bit more said here. I think Thomas's
draft does.

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---

From: "Teco Boot" <[email-masked]>
Date: Tue, 11 Nov 2008 11:43:44 +0100

> I think the term intended is non-transitive.
I meant non-reflexive, as defined in RFC4861:
###  Non-reflexive reachability means packets from A reach B,
###  but packets from B don't reach A.
For myself, I would use the term uni-directional.
I'm fine with symmetric, but link metrics would not need to be symmetric.
My ADSL provides bidirectional communication but has different data rates
for up- and downlink.
We need text on clarification / correction of RFC4861.

> Of course that may still leave asymmetry in
Yes!

> There needs to be quite a bit more said here. I think Thomas's
I am OK with having a document that describes the MANET model in detail.
I suggested to include a more mathematical model for the MANET links.

Teco.

---

From: "Dearlove, Christopher (UK)" <[email-masked]>
Date: Tue, 11 Nov 2008 10:57:15 -0000

> Non-reflexive reachability means packets from A reach B,
> but packets from B don't reach A.

That is unfortunate, a bad usage enshrined in an RFC, and an
important RFC at that.

But, the RFC notwithstanding, that's contrary to long
established mathematical usage - see for example
http://mathworld.wolfram.com/Reflexive.html
and to normal English, see for example
http://dictionary.reference.com/browse/reflexive

While changing RFC4861 isn't practical, I don't see any
reason to perpetuate the error.

> My ADSL provides bidirectional communication but has different data
rates

This is where two uses of symmetric come into conflict.
The relationship "has a link with" mayt be symmetric,
while the properties of the link may not be.

But replacing by reflexive (which has another meaning)
is not the answer.

But actually, as I noted, I think it's the non-transitivity,
not the non-symmetry (for either usage of symmetry, and as
you say, uni/bi-directional is a good usage) that's the
killer as to why ND doesn't work (though non-symmetry doesn't
help of course).

---

From: "Teco Boot" <[email-masked]>
Date: Tue, 11 Nov 2008 13:21:41 +0100

> That is unfortunate, a bad usage enshrined in an RFC, and an

OK, let's go for an errata for RFC4861:
=== Old text:
   asymmetric reachability
                  - a link where non-reflexive and/or non-transitive
                    reachability is part of normal operation.  (Non-
                    reflexive reachability means packets from A reach B,
                    but packets from B don't reach A.  Non-transitive
                    reachability means packets from A reach B, and
                    packets from B reach C, but packets from A don't
                    reach C.)  Many radio links exhibit these
                    properties.
=== New text:
   asymmetric reachability
                  - a link where non-symmetric and/or non-transitive
                    reachability is part of normal operation.  (Non-
                    symmetric reachability means packets from A reach B,
                    but packets from B don't reach A.  Non-transitive
                    reachability means packets from A reach B, and
                    packets from B reach C, but packets from A don't
                    reach C.)  Many radio links exhibit these
                    properties. 
===
OK with this?

And an adjusted attempt on defining a "MANET Link" model:
---
A MANET Interface has a single non-symmetric P2MP link to a set of
neighbors, a set of symmetric P2P links to a set of neighbors and a set of
non-symmetric P2P links to a set of neighbors. The sets of neighbors and the
link qualities vary over time. A characteristic of MANET Links is
interference, i.e. a transmission from a MANET Interface could influence
other MANET Links.
---

I am not satisfied with the "set of symmetric P2P links", because the link
metrics may be asymmetric.
And non-transitivity could be included.
And the P2MP link can be refined. The MANET interface has two roles here, as
a hub for sending and as spokes for receiving. 
Another shot:
===
A MANET Interface has a single outbound uni-directional P2MP link to a set
of neighbors, a set of inbound uni-directional P2MP links from a set of
neighbors, a set of bi-directional P2P links with a set of neighbors and a
set of uni-directional P2P links from a set of neighbors. The sets of
neighbors and the link qualities vary over time and link metrics may be
asymmetric. Furthermore, links between the MANET Interfaces could be
non-transitive. A characteristic of MANET Links is interference, i.e. a
transmission from a MANET Interface could influence other MANET Links.
===

> killer as to why ND doesn't work (though non-symmetry doesn't
 
Maybe parts of ND doesn't work.
Duplicate Address Detection doesn't work because both non-symmetry and
non-transitivity.
Neighbor Unreachability Detection should work.
If parts of ND doesn't work, I think it is important to specify which parts.
This should be included in the PS.

Teco.

---

From: "Dearlove, Christopher (UK)" <[email-masked]>
Date: Tue, 11 Nov 2008 12:30:04 -0000

properties.
>                   reach C.)  Many radio links exhibit these

Personally, yes. But even if it is accepted (as I think it should be)
that reflexive is wrong, I can see arguments over symmetric, which as
we've noted has alternative meanings. In addition I'd rather not get
into the administrative process of errataing (if that's a word) a
well-supported RFC right at the moment without good support from the
powers that be. (I'm not familiar with the RFC errata process details.)

---

From: "Teco Boot" <[email-masked]>
Date: Tue, 11 Nov 2008 14:47:21 +0100

> In addition I'd rather not get
> powers that be. 

I posted the issue:
 http://www.rfc-editor.org/errata_search.php?rfc=4861

Teco.