Subject: [IPFIX] Questions about compliance statement in IPFIX-selection-techniqes draft

From: Nevil Brownlee <[email-masked]>
Date: Wed, 22 May 2013 14:13:18 +1200

Hi all:

draft-ietf-ipfix-flow-selection-tech-16 is now in IESG Evaluation;
it currently has a blocking DISCUSS

Section 6.1 contains a compliance statement, which says
   "In order to be compliant with this document, at least the
    Property Match Filtering MUST be implemented."
The AD concerned asks whether we could remove this requirement.

This was triggered by a remark in my Shepherd statement for this draft,
which said
   "This draft raised IPR concerns, in the same manner as the PSAMP
   selection draft had done.  Nick Duffield (AT&T) commented that
   the AT&T IPR claim relates only to statistical sampling, and PSAMP
   handled this by saying "at least on of the sampling techniques
   must be implemented."
   In this draft, we have tightened that up a little by saying
   "a conforming implementation MUST implement at least the
   Property Match Filtering."
I realise now that the IPR in question was that relating to
draft-krishnan-opsawg-large-flow-load-balancing, which was discussed
on the IPFIX list back in Feb/Mar 2013; the issue that raised was
cleared by the company concerned making an IPR declaration.

That leaves us with the question about the compliance requirement.
The motivation for this remains the same as it was for RFC 5475,
"Sampling and Filtering Techniques for IP Packet Selection,"
the statement in section 6.1 simply refines it a little, and makes it
clear to implementors what's needed for a minimal conforming
implementation.

So now, I need some feedback from the WG.  Please send a note to
the list saying
"yes, keep the compliance statement in section 6.1" or
"no, delete the compliance statement in section 6.1.

Real soon now, please!

Cheers, Nevil

-- 
---------------------------------------------------------------------
  Nevil Brownlee                          Computer Science Department
  Phone: +64 9 373 7599 x88941             The University of Auckland
  FAX: +64 9 373 7453   Private Bag 92019, Auckland 1142, New Zealand

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From: Benoit Claise <[email-masked]>
Date: Wed, 22 May 2013 08:35:04 +0200

Hi Nevil,

"yes, keep the compliance statement in section 6.1".
I want to keep the consistency to makes it clear to implementors what's 
needed for a minimal conforming
implementation, and to be similar to RFC 5475

Regards, Benoit (as a contributor)

---

From: Paul Aitken <[email-masked]>
Date: Wed, 22 May 2013 08:58:04 +0100

Benoit, Nevil, All,

Option 3, "yes and no".

A clear specification of the compliance criteria is a must.

However, with the current compliance statement an implementation of all 
the specified Flow Sampling techniques without Property Match Filtering, 
is not compliant. Similarly, a device which implements Hash-based Flow 
Filtering rather than Property Match Filtering is not compliant.

We can't predict what future device requirements will be or how the 
draft will be used. Therefore the choice of Property Match Filtering as 
the compliance criteria seems somewhat arbitrary. It may seem like an 
obvious choice today, but in future might turn out like the 640KB limit. 
We don't want this to be a decision we regret with hindsight as we 
struggle with an awkward implementation of Property Match 
Filteringsimply to claim compliance.

So I'd prefer the compliance statement to say, "In order to be compliant 
with this document, at least one of the Filtering or Sampling techniques 
MUST be implemented."
Or, "... at least one of the Intermediate Flow Selection Process 
Techniques specified in section 6 MUST be implemented".

P.

On 22/05/13 07:35, Benoit Claise wrote:
> I want to keep the consistency to makes it clear to implementors 
> what's needed for a minimal conforming
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