Subject: [IPFIX] draft minutes of the IPFIX session yesterday

From: Juergen Quittek <[email-masked]>
Date: Wed, 21 Mar 2007 18:34:10 +0100

Dear all,

Please find the draft minutes of our session yesterday at

    <http://www3.ietf.org/proceedings/07mar/minutes/ipfix.htm>

    Many thanks to Rolf Wolter for taking the minutes!

Please check them and send your comments or requests for changes
until April 13.

Thanks,

    Juergen
-- 
Juergen Quittek        [email-masked]       Tel: +49 6221 4342-115
NEC Europe Limited,    Network Laboratories        Fax: +49 6221 4342-155
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From: Paul Aitken <[email-masked]>
Date: Wed, 21 Mar 2007 18:27:20 +0000

Juergen,

> Please check them and send your comments or requests for changes

Regarding "file format", I disagree with this comment:

   Emile: storage looks like a specific function of a mediator

I wanted to reply to that point in the meeting, but there wasn't time.

Sure, a mediator is one place where storage could be implemented - as we 
saw in Matsubara-san's presentation - but storage is not limited only to 
a mediator. I can think of scenarios where it's useful, and I'm sure 
Brian has real applications which led to the storage draft which aren't 
based on a mediator either.

Regarding "Order of Information Elements", Gerhard said:

   "the draft mentions that you cannot change the ordering
    as it has a semantic behind"

which is true if you have the same IE repeated inside a data record. 
However, re-ordering different IEs is not prohibited because the meaning 
and interpretation of any IE must be independent of any other IEs.

And as I understand it, Irino-san's draft would not re-order IEs of the 
same type, only IEs of different types.

ie, reordering

   "a1, b1, c1, a2, b2, c2, a3, b3, c2"

into

   "a1, a2, a3, b1, b2, b3, c1, c2, c3"

is not prohibited and should not cause any problems.

So, I believe there is no issue.

Cheers.
-- 
Paul Aitken
Cisco Systems Ltd, Edinburgh, Scotland.

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From: Paul Aitken <[email-masked]>
Date: Wed, 21 Mar 2007 18:27:20 +0000

Juergen,

ie, reordering

into

Cheers.

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From: Paul Aitken <[email-masked]>
Date: Wed, 21 Mar 2007 22:47:31 +0000

> same type, only IEs of different types.

To be clear, when I said "type" I meant "IE number".

---

From: Paul Aitken <[email-masked]>
Date: Wed, 21 Mar 2007 22:47:31 +0000

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From: Gerhard Muenz <[email-masked]>
Date: Thu, 22 Mar 2007 11:08:19 +0100

Dear all,

> based on a mediator either.

I would like to add a comment here: I think that the potential of the
file format is to serve as a standard exchange format for IPFIX/PSAMP
data! Internally in your system (which might be a mediator), you may
save/store the data in a different way.

> which is true if you have the same IE repeated inside a data record.

Yes, that is what my comment was about: If there are multiple fields of
the same IE, the order has to be preserved.

> same type, only IEs of different types.

Right. At first, I was confused and thought that reduced size encoded
field were to be located behind fields with full size encoding - which
would have destroyed the ordering if some of the same IEs were encoded
with reduced size and others were not.
Now, I reread the proposal and it says "reduced size encoding applicable
IEs" behind IEs that do not allow reduced size encoding, and that is ok
then.

Thanks,
Gerhard

-- 
Dipl.-Ing. Gerhard Münz
Computer Networks and Internet
Wilhelm Schickard Institute for Computer Science
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From: Gerhard Muenz <[email-masked]>
Date: Thu, 22 Mar 2007 11:08:19 +0100

Dear all,

Thanks,
Gerhard

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From: Paul Aitken <[email-masked]>
Date: Thu, 22 Mar 2007 11:28:37 +0000

Gerhard,

> with reduced size and others were not.

True.

> IEs" behind IEs that do not allow reduced size encoding, and that is ok

Irino-san's draft could be clearer about this. Consider if you have one 
IE using a mixture of normally encoded and reduce size encoding.

The simplest rule would be to say that all instances of this IE must be 
in the reduced size encoding area, ensuring that the order is preserved.

However, everything up to (but not including) the first reduced size one 
could go in the ordinary section without affecting the outcome.

But I think it makes the draft even more complicated than it already is 
- and I think it's already difficult enough to follow.

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From: Paul Aitken <[email-masked]>
Date: Thu, 22 Mar 2007 11:28:37 +0000

Gerhard,

True.