Revision of the tcpControlBits IPFIX Information Element

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Document Type Active Internet-Draft (individual)
Authors Brian Trammell  , Paul Aitken
Last updated 2013-09-09
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IPFIX Working Group                                          B. Trammell
Internet-Draft                                                ETH Zurich
Intended status: Informational                                 P. Aitken
Expires: March 13, 2014                               Cisco Systems, Inc
                                                      September 09, 2013

        Revision of the tcpControlBits IPFIX Information Element


   This document revises the tcpControlBits IPFIX Information Element
   defined in [RFC5102] to reflect changes to the TCP Flags header field
   since [RFC0793].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on March 13, 2014.

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Trammell & Aitken        Expires March 13, 2014                 [Page 1]
Internet-Draft            IPFIX tcpControlBits            September 2013

1.  Introduction

   Octets 12 and 13 of the TCP header encode the data offset (header
   length) in four bits, as well as 12 bits of flags.  The least
   significant 6 bits of these were defined in [RFC0793] as URG, ACK,
   PSH, RST, SYN, and FIN for TCP control.  Subsequently, [RFC3168]
   defined the CWR and ECE flags for Explicit Congestion Notification
   (ECN) negotiation and signaling; [RFC3540] additionally defined the
   NS flag for the ECN Nonce Sum.

   As defined in the IANA IPFIX Information Element Registry
   [IANA-IPFIX], taken from [RFC5102], the tcpControlBits Information
   Element for IPFIX [I-D.ietf-ipfix-protocol-rfc5101bis] only covers
   the original six bits from [RFC0793].  To allow IPFIX to be used to
   measure the use of ECN, and to bring the IPFIX Information Element
   definition in line with the current definition of the TCP Flags
   header field, it is necessary to revise this definition.

   The revised definition of the Information Element in Section 2 was
   developed and approved through the IE-DOCTORS process
   [I-D.ietf-ipfix-ie-doctors] in August 2013.  Section 5.1 of
   [I-D.ietf-ipfix-ie-doctors] states "This process should not in any
   way be construed as allowing the IE-DOCTORS to overrule IETF
   consensus.  Specifically, Information Elements in the IANA IE
   registry which were added with IETF consensus require IETF consensus
   for revision or deprecation".  Since the tcpControlBits Information
   Element was defined in [RFC5102], an IETF Proposed Standard, any
   revision of this Information Element definition requires IETF
   Consensus.  The publication of this document fulfills that

   The following section defines the revised tcpControlBits Information
   Element as in Section 9.1 of [I-D.ietf-ipfix-ie-doctors].

2.  The tcpControlBits Information Element

   ElementId:   6
   Data Type:   unsigned16
   Data Type Semantics:   flags
   Description:   TCP control bits observed for the packets of this
      Flow.  This information is encoded as a bit field; for each TCP
      control bit, there is a bit in this set.  The bit is set to 1 if
      any observed packet of this Flow has the corresponding TCP control
      bit set to 1.  The bit is cleared to 0 otherwise.

      The values of each bit are shown below, per the definition of the
      bits in the TCP header [RFC0793]:

Trammell & Aitken        Expires March 13, 2014                 [Page 2]
Internet-Draft            IPFIX tcpControlBits            September 2013

    MSb                                                         LSb
     0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
   |               |           | N | C | E | U | A | P | R | S | F |
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