One document matched: draft-trammell-ipfix-set9hack-00.txt

IPFIX Working Group                                          B. Trammell
Internet-Draft                                                ETH Zurich
Intended status: Standards Track                           July 26, 2010
Expires: January 27, 2011


    Reserved Set IDs to Enable Boundary Finding in Mixed IPFIX Files
                  draft-trammell-ipfix-set9hack-00.txt

Abstract

   This document reserves the IPFIX Set IDs 9 and 10 to prevent them
   from being allocated in the future.  The reason behind this is to
   ensure that heuristic methods for determining PDU boundaries in files
   containing NetFlow V9 PDUs and IPFIX Messages work in a standards-
   compliant way.

Status of this Memo

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   This Internet-Draft will expire on January 27, 2011.

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1.  Rationale

   Although Cisco NetFlow V9 [RFC3954] was never designed to be used as
   a storage format, and [RFC5655] defines a simple method for storing
   NetFlow V9 data in IPFIX Files, serialized files containing NetFlow
   V9 PDUs are nevertheless in use for storage.  NetFlow V9, unlike
   IPFIX, counts records as opposed to bytes in its Packet Header and as
   such does not provide a simple method for finding the boundaries of a
   Packet in a serialized stream.  A reader searching for the next
   NetFlow V9 Packet in a file must either parse the entire Message and
   count records to match with the V9 Count header, or simply skip sets
   and assume that a "Set ID" of 9 is actually a NetFlow V9 Packet
   Header Version field, and that the "Set Header" in this case is
   actually a Packet Header.

   This works because Cisco NetFlow V9 will never export a Set with a
   Set ID of 9.  However, if a file contains mixed NetFlow V9 and IPFIX
   messages, the fact that IPFIX could allocate a set ID of 9 for future
   use would cause any reader using this method to fail.  Reserving Set
   ID 9 to keep it from being allocated in the future would solve this
   problem.  Similarly, Set ID 10 could be used to recognize IPFIX
   Messages in a file containing a mix of NetFlow V9 and IPFIX data.

   "Future use" Set IDs (4-255) are not a particularly scarce resource,
   considering they require non-interoperable changes to the protocol to
   implement; therefore, reserving two to prevent future allocation
   presents no serious problem.


2.  IANA Considerations

   IANA has added two entries to the IPFIX Set ID registry: Set ID 9 is
   now Reserved.  Set ID 10 is now Reserved.


3.  Normative References

   [RFC3954]  Claise, B., "Cisco Systems NetFlow Services Export Version
              9", RFC 3954, October 2004.

   [RFC5655]  Trammell, B., Boschi, E., Mark, L., Zseby, T., and A.
              Wagner, "Specification of the IP Flow Information Export
              (IPFIX) File Format", RFC 5655, October 2009.








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Author's Address

   Brian Trammell
   Swiss Federal Institute of Technology Zurich
   Gloriastrasse 35
   8092 Zurich
   Switzerland

   Phone: +41 44 632 70 13
   Email: trammell@tik.ee.ethz.ch









































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