Subject: [Ospf-manet] Re: Ospf-manet Digest, Vol 11, Issue 7

From: Aniket Desai <[email-masked]>
Date: Tue, 03 Oct 2006 12:27:09 -0400

At 12:01 PM 10/3/2006, you wrote:
>For example, that is why Aniket and I have been
>explaining why the MDR approach is a "natural extension".
>This is a very important point, since once people understand
>*why* we claim it is a "natural extension", they will understand
>the MDR approach better.

That is the point I have also made and I corroborate it. It should be 
acceptable to use the phrase that "an MDR is a natural extension of a 
broadcast DR". MDRs must be discussed in that context. Otherwise the 
whole point is lost in unimportant issues. As far as I understand, 
this debate is about scalability versus robustness, and I don't think 
anyone can claim that other solutions can achieve better scalability 
than MDR. The claim is only that MDRs lose in robustness what they 
achieve in scalability (which has to be seen anyway and can be 
discounted upfront for the simple reason that MDRs don't force you to 
use reduced adjacencies; MDRs give you the reduced adjacencies as a 
*gift* - but that is another discussion). The point is that MDRs do 
achieve something, which is scalability BECAUSE it naturally extends 
the broadcast DR.

Thus if no one has any more objection to the usage of this term, I 
think it is perfectly legit for Dr. Ogier and others to continue using it.

Sincerely,

Aniket 

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---

From: Padma Pillay-Esnault <[email-masked]>
Date: Tue, 03 Oct 2006 09:46:39 -0700

Aniket

> think it is perfectly legit for Dr. Ogier and others to continue using 

This is a engineering forum and a scientific one. In IETF, we use precise
language - RFC 2119 for example. IMHO "Natural extension" does not fit in 
aforementionned category. This term is too foggy, "natural" has too many complex 
meaning in layman terms it is best avoided. I don't understand why "natural" has 
to be here, in most drafts "extension" is just sufficient.

Padma

---

From: Aniket Desai <[email-masked]>
Date: Tue, 03 Oct 2006 13:08:14 -0400

Hi Padma,

I know RFC 2119 very well.

Let me cut and paste some sentences from RFC 3626 from the OLSR draft:

    The purpose of dividing the functioning of OLSR into a core
    functionality and a set of auxiliary functions is to provide a simple
    and easy-to-comprehend protocol

    Due to its proactive nature, the OLSR protocol has a natural control
    over the flow of its control traffic

Now if I were to write an MDR draft and if I constructed a sentence as:

         The purpose of creating this MDR draft is to extend the 
OSPF's broadcast interface in a natural way. Details follow.

How is it different from what is there in RFC 3626? As long as we 
understand the context in which we are talking, I think this term 
should be acceptable. You are always free to challenge the context.

I understand that the fuss was about the reference that MDRs were a 
natural way to extend OSPF for MANET. I agree that it was an 
aggressive overclaim. I am merely advocating putting it in its 
correct context; that is a *natural extension of broadcast DR 
interface*. I think that there should be a qualifying adjective 
before *extension*, because no one else has shown that there is any 
other way to extend a broadcast interface for MANETs. Hence the 
emphasis on natural. Please suggest if you would like to use another 
adjective instead of *natural*.

Sincerely,

Aniket

At 12:46 PM 10/3/2006, Padma Pillay-Esnault wrote:
>>That is the point I have also made and I corroborate it. It should 
>>be acceptable to use the phrase that "an MDR is a natural extension 
>>of a broadcast DR". MDRs must be discussed in that context. 
>>Otherwise the whole point is lost in unimportant issues. As far as 
>>I understand, this debate is about scalability versus robustness, 
>>and I don't think anyone can claim that other solutions can achieve 
>>better scalability than MDR. The claim is only that MDRs lose in 
>>robustness what they achieve in scalability (which has to be seen 
>>anyway and can be discounted upfront for the simple reason that 
>>MDRs don't force you to use reduced adjacencies; MDRs give you the 
>>reduced adjacencies as a *gift* - but that is another discussion). 
>>The point is that MDRs do achieve something, which is scalability 
>>BECAUSE it naturally extends the broadcast DR.
>>
>language - RFC 2119 for example. IMHO "Natural extension" does not 
>fit in aforementionned category. This term is too foggy, "natural" 
>has too many complex meaning in layman terms it is best avoided. I 
>don't understand why "natural" has to be here, in most drafts 
>"extension" is just sufficient.
>
>
>Padma
>
>
>>Sincerely,
>>
>>Aniket
>>

---

From: Padma Pillay-Esnault <[email-masked]>
Date: Tue, 03 Oct 2006 10:45:10 -0700

Aniket

Aniket Desai wrote:

>         The purpose of creating this MDR draft is to extend the OSPF's 
> broadcast interface in a natural way. Details follow.
>
In OSPF drafts you don't see natural, DC is not a natural extension, nor 
is NSSA, nor are other features. They are just extensions.

> aggressive overclaim. I am merely advocating putting it in its correct 
> context; that is a *natural extension of broadcast DR interface*. I 
> think that there should be a qualifying adjective before *extension*, 
> because no one else has shown that there is any other way to extend a 
> broadcast interface for MANETs. Hence the emphasis on natural. Please 
> suggest if you would like to use another adjective instead of *natural*.
>
Why is it so important to put this adjective, would removing it change 
the meaning of the functionality ?
I don't think so.
It's presence kind of open the debate - What is natural and what is not ?

Extensions are just extensions and that should suffice.
Let's not add superfluous terms.

Padma

>>> Otherwise the whole point is lost in unimportant issues. As far as I 
>>> understand, this debate is about scalability versus robustness, and 
>>> I don't think anyone can claim that other solutions can achieve 
>>> anyway and can be discounted upfront for the simple reason that MDRs 
>>> don't force you to use reduced adjacencies; MDRs give you the

---

From: Aniket Desai <[email-masked]>
Date: Tue, 03 Oct 2006 13:53:50 -0400

I understand that usage of such a term in a draft is not a good idea. 
But to make the discussions as precise as a draft is very daunting, 
and we will stall if we did not take liberty of the ongoing context 
and tried to qualify something as a result. As Dr. Ogier has said, 
from a functional perspective, there are great similarities between a 
DR and MDR and hence it follows *naturally*. The term is not without 
a valid context. That said, I think this is stretching too far and I 
retract from this discussion. I believe that the following sentence 
would do: "OSPF MDR extends the functionality and capabilities of the 
OSPF broadcast interface".

Sincerely,

Aniket

At 01:45 PM 10/3/2006, Padma Pillay-Esnault wrote:
>In OSPF drafts you don't see natural, DC is not a natural extension, 
>nor is NSSA, nor are other features. They are just extensions.
>
>>emphasis on natural. Please suggest if you would like to use 
>>another adjective instead of *natural*.
>Why is it so important to put this adjective, would removing it 
>change the meaning of the functionality ?
>I don't think so.
>>>>That is the point I have also made and I corroborate it. It 
>>>>should be acceptable to use the phrase that "an MDR is a natural 
>>>>extension of a broadcast DR". MDRs must be discussed in that 
>>>>context. Otherwise the whole point is lost in unimportant issues. 
>>>>As far as I understand, this debate is about scalability versus 
>>>>robustness, and I don't think anyone can claim that other 
>>>>solutions can achieve better scalability than MDR. The claim is 
>>>>only that MDRs lose in robustness what they achieve in 
>>>>scalability (which has to be seen anyway and can be discounted 
>>>>upfront for the simple reason that MDRs don't force you to use 
>>>>reduced adjacencies; MDRs give you the reduced adjacencies as a 
>>>>*gift* - but that is another discussion). The point is that MDRs 
>>>>do achieve something, which is scalability BECAUSE it naturally 
>>>>extends the broadcast DR.
>>>>
>>>>Thus if no one has any more objection to the usage of this term, 
>>>>I think it is perfectly legit for Dr. Ogier and others to continue using it.
>>>
>>>

---

From: Richard Ogier <[email-masked]>
Date: Tue, 03 Oct 2006 15:47:25 -0700

Aniket Desai wrote:

> DR and MDR and hence it follows *naturally*. The term is not without a 
> valid context. That said, I think this is stretching too far and I 

Lots of people, including mathematicians, use the term "natural extension".
(Just do an internet search.)
Of course, the term should not be used without some justification, but
I think we have provided such justification.  It's OK for people to
disagree with our use of the term, but we have a right to continue
using the term if we believe it represents the truth.
To me, a "natural extension" is an extension that uses techniques
and maintains properties that are similar to those of the thing
being extended.  Sure, an MDR is a generalization
of a DR (whereas an MPR is not as discussed), and that helps.
But to be a "natural extension", we want to maintain techniques
and properties of the thing being extended, i.e., an OSPF broadcast
network.  For example, just as each DR Other forms an adjacency
with each DR and Backup DR in an OSPF broadcast network,
each MDR Other forms an adjacency with each MDR and Backup MDR
in a MANET.   Thus, OSPF-MDR achieves adjacency reduction in a
MANET similar to the way OSPF achieves adjacency reduction in
a broadcast network.  This also has other advantages, such as
helping to minimize the changes to OSPF.

Richard

>>>>> be acceptable to use the phrase that "an MDR is a natural 
>>>>> only that MDRs lose in robustness what they achieve in scalability 
>>>>> (which has to be seen anyway and can be discounted upfront for the 
>>>>> simple reason that MDRs don't force you to use reduced 
>>>>> adjacencies; MDRs give you the reduced adjacencies as a *gift* - 
>>>>> but that is another discussion). The point is that MDRs do achieve 
>>>>> something, which is scalability BECAUSE it naturally extends the 
>>>>> broadcast DR.
>>>>>

---

From: Aniket Desai <[email-masked]>
Date: Tue, 03 Oct 2006 19:10:19 -0400

Hi everyone,

I apologize to Dr. Ogier for letting my position down after getting 
influenced from replies by the others on the contrary.

I should have simply put the search string "ietf natural extension" 
in Google, which is what I did. Guess what? A lot of RFCs use this 
term (i did a similar search on IEEE with the same result -- it is an 
accepted term in scientific and engineering journals). Hence I do not 
feel at all that the OSPF-MDR RFC should abandon one of his 
strongholds just because a few people cannot agree with this obvious 
use of terminology.

Sincerely,

Aniket

At 06:47 PM 10/3/2006, Richard Ogier wrote:
>Aniket Desai wrote:
>
>>I understand that usage of such a term in a draft is not a good 
>>idea. But to make the discussions as precise as a draft is very 
>>daunting, and we will stall if we did not take liberty of the 
>>ongoing context and tried to qualify something as a result. As Dr. 
>>Ogier has said, from a functional perspective, there are great 
>>similarities between a DR and MDR and hence it follows *naturally*. 
>>The term is not without a valid context. That said, I think this is 
>>stretching too far and I retract from this discussion. I believe 
>>that the following sentence would do: "OSPF MDR extends the 
>>functionality and capabilities of the OSPF broadcast interface".
>
>
>>>In OSPF drafts you don't see natural, DC is not a natural 
>>>extension, nor is NSSA, nor are other features. They are just extensions.
>>>
>>>>I understand that the fuss was about the reference that MDRs were 
>>>>a natural way to extend OSPF for MANET. I agree that it was an 
>>>>before *extension*, because no one else has shown that there is 
>>>>any other way to extend a broadcast interface for MANETs. Hence 
>>>>the emphasis on natural. Please suggest if you would like to use 
>>>>>>should be acceptable to use the phrase that "an MDR is a 
>>>>>>natural extension of a broadcast DR". MDRs must be discussed in 
>>>>>>that context. Otherwise the whole point is lost in unimportant 
>>>>>>issues. As far as I understand, this debate is about 
>>>>>>scalability versus robustness, and I don't think anyone can 
>>>>>>claim that other solutions can achieve better scalability than 
>>>>>>MDR. The claim is only that MDRs lose in robustness what they 
>>>>>>discounted upfront for the simple reason that MDRs don't force 
>>>>>>you to use reduced adjacencies; MDRs give you the reduced 
>>>>>>adjacencies as a *gift* - but that is another discussion). The 
>>>>>>point is that MDRs do achieve something, which is scalability 
>>>>>>Thus if no one has any more objection to the usage of this 
>>>>>>term, I think it is perfectly legit for Dr. Ogier and others to 
>>>>>>continue using it.
>>>>>
>>>>>
>>>>>
>>>>>language - RFC 2119 for example. IMHO "Natural extension" does 
>>>>>not fit in aforementionned category. This term is too foggy, 
>>>>>"natural" has too many complex meaning in layman terms it is 
>>>>>best avoided. I don't understand why "natural" has to be here, 
>>>>>in most drafts "extension" is just sufficient.
>>>>>
>>>>>
>>>>>Padma
>>>>>
>>>>>
>>>>>>Sincerely,
>>>>>>
>>>>>>Aniket
>>>>>>

---

From: Padma Pillay-Esnault <[email-masked]>
Date: Tue, 03 Oct 2006 16:46:23 -0700

Both

Any extension preserves the capabilities of the underlying base that is 
being extended or else
that would be called a new version.

I mentionned OSPF documents and I still don't see natural extensions in 
those documents and proposed to
keep the custom as in OSPF so far - after all this is a OSPF draft.

I refuse to spend more time over this - if each word change triggers an 
email thread - we are far from finished.
Hence this is my last response on this.

Padma

Aniket Desai wrote:

> I should have simply put the search string "ietf natural extension" in 
> Google, which is what I did. Guess what? A lot of RFCs use this term 
> (i did a similar search on IEEE with the same result -- it is an 
>>>>>>> context. Otherwise the whole point is lost in unimportant 
>>>>>>> issues. As far as I understand, this debate is about scalability 
>>>>>>> versus robustness, and I don't think anyone can claim that other 
>>>>>> "natural" has too many complex meaning in layman terms it is best 
>>>>>> avoided. I don't understand why "natural" has to be here, in most 
>>>>>> drafts "extension" is just sufficient.
>>>>>>
>>>>>>
>>>>>> Padma
>>>>>>
>>>>>>
>>>>>>> Sincerely,
>>>>>>>
>>>>>>> Aniket
>>>>>>>

---

From: Aniket Desai <[email-masked]>
Date: Tue, 03 Oct 2006 20:10:45 -0400

OSPF does not need any work to make it function as is for MANET 
environment...the point to multipoint interface would do fine. Then, 
what is really the qualifying difference between the 2 proposals?

a) OSPF DR exists only for scalability purpose.
b) OSPF MDR achieves scalability using the same functionality as OSPF DR.
c) OSPF DR is a special case of OSPF MDR. (DR = MDR for a single hop MANET).
d) follows a, b and c: Hence OSPF MDR naturally extends OSPF DR.

Sincerely,

Aniket

At 07:46 PM 10/3/2006, Padma Pillay-Esnault wrote:
>Both
>
>Any extension preserves the capabilities of the underlying base that 
>is being extended or else
>I mentionned OSPF documents and I still don't see natural extensions 
>in those documents and proposed to
>I refuse to spend more time over this - if each word change triggers 
>an email thread - we are far from finished.
>>term (i did a similar search on IEEE with the same result -- it is 
>>an accepted term in scientific and engineering journals). Hence I 
>>do not feel at all that the OSPF-MDR RFC should abandon one of his 
>>strongholds just because a few people cannot agree with this 
>>obvious use of terminology.
>>Sincerely,
>>
>>Aniket
>>
>>>>ongoing context and tried to qualify something as a result. As 
>>>>Dr. Ogier has said, from a functional perspective, there are 
>>>>great similarities between a DR and MDR and hence it follows 
>>>>*naturally*. The term is not without a valid context. That said, 
>>>>I think this is stretching too far and I retract from this 
>>>>discussion. I believe that the following sentence would do: "OSPF 
>>>>MDR extends the functionality and capabilities of the OSPF 
>>>>broadcast interface".
>>>
>>>
>>>
>>>>>>         The purpose of creating this MDR draft is to extend 
>>>>>> the OSPF's broadcast interface in a natural way. Details follow.
>>>>>>
>>>>>>How is it different from what is there in RFC 3626? As long as 
>>>>>>we understand the context in which we are talking, I think this 
>>>>>>term should be acceptable. You are always free to challenge the context.
>>>>>
>>>>>
>>>>>>I understand that the fuss was about the reference that MDRs 
>>>>>>were a natural way to extend OSPF for MANET. I agree that it 
>>>>>>was an aggressive overclaim. I am merely advocating putting it 
>>>>>>in its correct context; that is a *natural extension of 
>>>>>>broadcast DR interface*. I think that there should be a 
>>>>>>qualifying adjective before *extension*, because no one else 
>>>>>>has shown that there is any other way to extend a broadcast 
>>>>>>interface for MANETs. Hence the emphasis on natural. Please 
>>>>>>>>natural extension of a broadcast DR". MDRs must be discussed 
>>>>>>>>in that context. Otherwise the whole point is lost in 
>>>>>>>>unimportant issues. As far as I understand, this debate is 
>>>>>>>>about scalability versus robustness, and I don't think anyone 
>>>>>>>>can claim that other solutions can achieve better scalability 
>>>>>>>>than MDR. The claim is only that MDRs lose in robustness what 
>>>>>>>>they achieve in scalability (which has to be seen anyway and 
>>>>>>>>can be discounted upfront for the simple reason that MDRs 
>>>>>>>>reduced adjacencies as a *gift* - but that is another 
>>>>>>>>discussion). The point is that MDRs do achieve something, 
>>>>>>>>which is scalability BECAUSE it naturally extends the broadcast DR.
>>>>>>>>
>>>>>>>>term, I think it is perfectly legit for Dr. Ogier and others 
>>>>>>>>to continue using it.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>

---

From: Richard Ogier <[email-masked]>
Date: Tue, 03 Oct 2006 17:58:56 -0700

Aniket,

I will avoid using the term "natural" in this message. Instead I will
refer to the properties of MDRs that are similar to those of DRs, and
discuss another benefit of this similarity.  (I already mentioned that
this similarity minimizes the number of changes that must be made to OSPF.)
In general, a good extension will minimize the number of new objects
that are introduced.
Thus, it is better to generalize a DR than to introduce a new object
such as an MPR (which as discussed does not generalize a DR since
it is source dependent).  Another advantage, related to item (c) below
from Aniket, is that an OSPF broadcast network can be treated as a
special case of a MANET, since in both cases the DR/MDR and the
set of adjacencies are the same.  This is described in Section 8.1.2
of the MDR draft.  (I believe that the smart peering solution does
not select the same set of adjacencies since it selects adjacencies
in a more random fashion.)

> that would be called a new version.

Right. But we are not talking about preserving the capabilities of the
underlying base.  First, we are not just talking about capabilities.
Second, we want to minimize the changes and the addition of new objects,
concepts, techniques, properties, etc.

Richard

P.S.  Someone pointed out that there is no single "natural" way to
extend a protocol.  That is true, and I never said MDRs is the
only natural way to extend an OSPF broadcast network, or to
generalize DRs.  I said "a natural extension", not "the natural
extension".

Aniket Desai wrote:

>>> an accepted term in scientific and engineering journals). Hence I do 
>>> not feel at all that the OSPF-MDR RFC should abandon one of his 
>>>>> similarities between a DR and MDR and hence it follows 
>>>>> *naturally*. The term is not without a valid context. That said, I 
>>>>> think this is stretching too far and I retract from this 
>>>>>>> were a natural way to extend OSPF for MANET. I agree that it was 
>>>>>>> an aggressive overclaim. I am merely advocating putting it in 
>>>>>>> its correct context; that is a *natural extension of broadcast 
>>>>>>> DR interface*. I think that there should be a qualifying 
>>>>>>> adjective before *extension*, because no one else has shown that 
>>>>>>> there is any other way to extend a broadcast interface for 
>>>>>>> MANETs. Hence the emphasis on natural. Please suggest if you 
>>>>>>> would like to use another adjective instead of *natural*.
>>>>>>
>>>>>>
>>>>>>

---

From: Richard Ogier <[email-masked]>
Date: Wed, 04 Oct 2006 18:05:02 -0700

Ironically, my slides for the MDR position draft presented
at the Dallas meeting did not even use the word "natural"!
Instead there was a slide titled "Similarities Between OSPF-MDR and OSPF"
http://www3.ietf.org/proceedings/06mar/slides/ospf-4/sld6.htm

I guess some unnecessary arguing could have been avoided if I
had referred to this slide instead the older one, so that
the relevant properties of OSPF-MDR could be discussed without
quibbling over the term "natural".

Anyway, these similarities between OSPF-MDR and OSPF are an
important aspect of the MDR approach.  (I know of several
people who agree with this.)  As mentioned, this similarity
is beneficial because it minimizes the number of objects,
concepts, techniques, etc. that must be added to OSPF.

Richard