Subject: [manet] DLEP-15: extending/enhancing DLEP

From: RJ Atkinson <[email-masked]>
Date: Tue, 14 Jul 2015 10:35:02 -0400

All

The new approach to adding DLEP Signal/Message Types,
adding DLEP Data Items, and DLEP Extension values is
a vast improvement over the previous approach.  This
new approach makes it easier to promote something 
useful in the lab for broader more general use.

However, only 15 code points are allocated for “Private Use”, 
which is not nearly enough, despite now having a very
large code point space (64K code points).  Folks likely
will want to try multiple DLEP enhancements concurrently 
— in part to see how they interact with each other.  Increasing 
the “Private Use” block to something much larger, for example
O(100), would not limit the number of published enhancements
given the very large number space available for published
enhancements.

Further, interoperability is its own reward, encouraging
folks with any useful enhancements to publish them.  With
many IETF protocols, enhancements that initially were
unpublished later were published (and in many cases 
standardized) after their broad applicability and 
broad utility had been well established.

The reality is that there are going to be link-specific 
parameters that really don’t have general applicability,
whether those relate to VSATs, VHF/UHF LoS radio waveforms,
or some other kind of radio.  The “Private Use” code
point blocks enable those kinds of waveform-specific
enhancements without forcing one to use a code point that
has not officially been allocated to oneself.  So they
fill a well-known need.  The entire existence of “Private
Use” within Section 4.1 of RFC-5226 shows that this 
approach is widely accepted within the IETF.

I think 15 “Private Use” code points is not nearly enough.  

My straw man proposal would be to make that 150 code points 
for the “Private Use” Data Item Type space, 30 code points 
for the “Private Use” Signal/Message Type space, and 180
(180 == 150 + 30) code points for the DLEP Extension Type space.

Yours,

Ran

---

From: Henning Rogge <[email-masked]>
Date: Tue, 14 Jul 2015 16:50:36 +0200

I disagree...

we talked about this and limiting the private signal/extension space
was a design decision.

180 private extension points sounds way beyond a reasonable, what
would you do with them? If you only have 150 private TLVs, does it
even make sense to have more than 150 private extensions?

We WANT people to come up with official DLEP extensions for things
like VSAT. I don't even see the reason why VHF/UHF should be a special
case (maybe HF, but even this should be standardized).

Henning Rogge

On Tue, Jul 14, 2015 at 4:35 PM, RJ Atkinson <[email-masked]> wrote:
> _______________________________________________
> manet mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/manet

---

From: RJ Atkinson <[email-masked]>
Date: Tue, 14 Jul 2015 12:35:38 -0400

> On 14  Jul 2015, at 10:50 , Henning Rogge <[email-masked]> wrote:
> 

Yes.  

The math is pretty simple:
	 30 for signaling support for new Signal/Message Types
      + 150 for signaling support for new Data Item Types
 equals 180.

If you think I’ve misplaced a clue, please do explain. :-)

> We WANT people to come up with official DLEP extensions
> for things like VSAT.

That would be great.  I expect that some will be openly
specified over time.  

However, there also are likely to be some that are properties
of specific SATCOM waveforms that would not make sense outside 
of that particular waveform.

> I don't even see the reason why VHF/UHF should be a special

We agree that it would be great to have various openly
specified extensions.  Again, I expect that naturally
will happen over time.  

However, the same principles on why a larger “Private Use” block
(especially for Data Items) are needed as I’ve outlined above, 
previously, and also prior to DLEP-15.  Some items aren’t generic 
enough, are waveform-specific, or otherwise don’t make sense 
to publicly specify.  Allowing generous Private Use blocks 
is quite common in IETF protocols, so this ought not seem novel.

Yours,

Ran

---

From: Henning Rogge <[email-masked]>
Date: Thu, 16 Jul 2015 21:05:16 +0200

>       + 150 for signaling support for new Data Item Types

Yes...

a signal is just a container for TLVs... what kind of use-case do you
see for "single signal, no TLV" extensions?

Practically all extensions I have thought about myself or heard about
were either "zero signal, lots of TLVs" or "few signal, lots of TLVs".

Henning

---

From: Rick Taylor <[email-masked]>
Date: Fri, 17 Jul 2015 08:40:33 +0000

Ran,

I'm with Henning on this one.  As designed, 1 extension introduces 0..N 
signals and 0..N data items, so the math isn't as simple as you say.

In reality, supporting more than 1 Private Use extension per session is 
impossible, so the 14 private use extensions we have provided is (in my 
mind) plenty.  If one needs to run 14 different modems all supporting 
private use extensions simulataneously, then either a) Your experimental 
methodology is flawed, or b) It's time to write up a few of these 
experiments and bring them to MANET.

The reworked math:

14 exts * (126 msgs + 126 dis) = 3528 code points for customization.

Actually this calculation is pretty meaningless, but it does point out 
that there is enough Private Use room in DLEP-15.

Cheers,

Rick

---

From: "Wiggins, David - 0665 - MITLL" <[email-masked]>
Date: Fri, 17 Jul 2015 12:08:42 +0000

On 7/17/15, 4:40 AM, "Rick Taylor" <[email-masked]> wrote:
>impossible,

Why is this the case?  I can see that if you tried to mix two arbitrary
Private Use extensions, there could be conflicts, but if someone checks
them for compatibility beforehand, why wouldn't it work?

David

---

From: Rick Taylor <[email-masked]>
Date: Fri, 17 Jul 2015 12:27:04 +0000

> them for compatibility beforehand, why wouldn't it work?

Okay, perhaps 'impossible' is too strong, but it becomes hard.  In some 
way one could describe 2 compatible private use extensions as just 1 
extension.

I'm not concerned about putting any limit on simultaneous private use 
extensions, but I do think we have enough space in the registry as it 
stands.

Rick

---

From: "Wiggins, David - 0665 - MITLL" <[email-masked]>
Date: Fri, 17 Jul 2015 12:59:12 +0000

>extensions, but I do think we have enough space in the registry as it

I'd still like to see more.  If you have a handful of collaborators, and
each one has a handful of extensions, 15 is going to get cramped in a
hurry.  You can say that they should publish those extensions and get them
out of private use space, but that takes time.  I'd be more comfortable
with at least 32.

David

---

From: Henning Rogge <[email-masked]>
Date: Fri, 17 Jul 2015 16:41:21 +0200

> out of private use space, but that takes time.  I'd be more comfortable

With private extensions you also have the point to add the "id" just
to your configuration file and remap them to different private numbers
if necessary.

Henning Rogge

---

From: RJ Atkinson <[email-masked]>
Date: Fri, 17 Jul 2015 15:50:50 -0400

> On 17  Jul 2015, at 08:27 , Rick Taylor <[email-masked]> wrote:
> extensions, 

I am glad to hear that.  

As of DLEP-15, we have number spaces with 64K numbers.
Lets increase the “Private Use” allocations to reasonable
sizes and then we (and the document) all can move forward.

Yours,

Ran

---

From: RJ Atkinson <[email-masked]>
Date: Fri, 17 Jul 2015 15:51:43 -0400

> On 17  Jul 2015, at 10:41 , Henning Rogge <[email-masked]> wrote:
> 

I am very sorry, but I do not understand the sentence quoted 
just above.  Please rephrase.  :-)

Yours,

Ran

---

From: Henning Rogge <[email-masked]>
Date: Fri, 17 Jul 2015 21:58:13 +0200

> just above.  Please rephrase.  :-)

A private extension can easily changed its ID because it is NOT part
of a standard. So id collisions are not that big problem.

Henning Rogge

---

From: "Ratliff, Stanley" <[email-masked]>
Date: Fri, 17 Jul 2015 20:42:10 +0000

> -----Original Message-----
> From: manet [mailto:[email-masked]] On Behalf Of RJ Atkinson
> Sent: Friday, July 17, 2015 3:51 PM
> To: MANET IETF <[email-masked]>
> Subject: Re: [manet] DLEP-15: extending/enhancing DLEP
> 
> 
> Lets increase the “Private Use” allocations to reasonable sizes and then we
> (and the document) all can move forward.
> 

The crux of the disagreement is over what is "reasonable", so this comment is unhelpful. I'm on the same opinion as others have stated on this list - the current private-use allocations *are* reasonable, and we should proceed. 

Stan

> Ran

_____________________________________________________
This electronic message and any files transmitted with it contains
information from iDirect, which may be privileged, proprietary
and/or confidential. It is intended solely for the use of the individual
or entity to whom they are addressed. If you are not the original
recipient or the person responsible for delivering the email to the
intended recipient, be advised that you have received this email
in error, and that any use, dissemination, forwarding, printing, or
copying of this email is strictly prohibited. If you received this email
in error, please delete it and immediately notify the sender.
_____________________________________________________

---

From: RJ Atkinson <[email-masked]>
Date: Fri, 17 Jul 2015 18:59:37 -0400

> On 17  Jul 2015, at 16:42 , Ratliff, Stanley <[email-masked]> wrote:
> 
> I'm on the same opinion as others have stated on this list - the current private-use allocations *are* reasonable, and we should proceed. 

Stan,

A range of views about what’s reasonable have been expressed on the list.
I understand that you believe the current numbers are reasonable.  

We disagree.

Maybe soliciting another opinion is useful in this situation.

Lou,

  What is your take on this ?  What would be an IETF customary
range of “Private Use” values in this situation ?

Yours,

Ran

PS:  I am not, regrettably, going to be in Prague next week.
     I look forward to reading the meeting minutes for this
     and several other WGs.

---

From: Lou Berger <[email-masked]>
Date: Sat, 18 Jul 2015 06:53:35 -0400

Ran,

See below.

On July 17, 2015 7:00:02 PM RJ Atkinson <[email-masked]> wrote:

> > I'm on the same opinion as others have stated on this list - the current 
> private-use allocations *are* reasonable, and we should proceed.
>
> Stan,
>

I'm not sure there really is a 'customary range'. Generally the
allocations with the different policies are separated sufficiently
(e..g., one policy allocates incrementally from 0, while the other is
allocated from the top of the range) to allow the size of the ranged
to be revisited based on real use.

Lou