Subject: [ipfix-info] Comments on Info draft

From: Nevil Brownlee <[email-masked]>
Date: Mon, 14 Jul 2003 20:07:11 +1200

Hi all:

It's taken a while for me to catch up, but here are my comments on the
Info Model draft.  The draft itself is a good start, these are just
the issues I spotted while reading it on the 'plane to Vienna.

Cheers, Nevil

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   Nevil Brownlee                   Director, Technology Development
   Phone: +64 9 373 7599 x88941     ITSS, The University of Auckland
   FAX: +64 9 373 7021      Private Bag 92019, Auckland, New Zealand

Ni1:  Variable Length Data Type:
      The Protocol I-D has a section about 'variable-length data types'
      shouldn't that be here, in the Information Model I-D?
      Can anything other than a string be variable-length?

Ni2:  ipdr: types.  Do we need to have the ipdr: prefix?
      The Info Model RFC will need an IANA Considerations section,
      so we'll need a Appendices listing the data types - can we not
      give them all simple names, and comment on which of them are
      identical to their ipdr: cousins?
      [Also, for the IANA Considerations, we'll need a list of all
      the Field Ids.]

Ni3:  Section 6, Extending the Info Model:
      typo in para 3, s/flow ids/field ids/

Ni4:  Section 9.11, byteCount
      Para 2 says a flow can be bi-directional, in which case byteCount
      is the sum of both directions.
      How would a collector know whether a flow 1- or 2-directional?

Ni5:  Section 9.11, byteCount
      Is int big enough for this?  (RTFM used unsignedLong)

Ni6:  Section 9.14 and 9.15, flowCreation- and EndTime
      Is seconds precision enough?

Ni7:  Section 9.20 sourceExporterAddress
      This is defined as an IPv4 address.  What about IPv6 Exporters?

Ni8: Sections 9.22 samplingInterval and 9.23 samplingAlgorithn.
     I think samplingAlgorithm should appear before samplingInterval.
     Maybe what's needed is samplingAlgorithm first, with values
     like 'count-based,' 'time-based' or 'content-based,' using the
     algorithm names from our Requirements I-D.  That could have
     subsections for each of the algorithm's parameters, e.g. 
     count-based would have samplingInterval = n meaning 'meter every
     nth packet within each flow.'

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