Revision of the tcpControlBits IP Flow Information Export (IPFIX) Information Element
RFC 7125
| Document | Type |
RFC - Informational
(February 2014; No errata)
Was draft-trammell-ipfix-tcpcontrolbits-revision (individual in ops area)
|
|
|---|---|---|---|
| Authors | Brian Trammell , Paul Aitken | ||
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | Adrian Farrel | ||
| Shepherd write-up | Show (last changed 2013-10-07) | ||
| IESG | IESG state | RFC 7125 (Informational) | |
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Benoît Claise | ||
| Send notices to | n.brownlee@auckland.ac.nz | ||
| IANA | IANA review state | IANA OK - Actions Needed | |
| IANA action state | RFC-Ed-Ack | ||
Internet Engineering Task Force (IETF) B. Trammell
Request for Comments: 7125 ETH Zurich
Category: Informational P. Aitken
ISSN: 2070-1721 Cisco Systems, Inc
February 2014
Revision of the tcpControlBits
IP Flow Information Export (IPFIX) Information Element
Abstract
This document revises the tcpControlBits IP Flow Information Export
(IPFIX) Information Element as originally defined in RFC 5102 to
reflect changes to the TCP Flags header field since RFC 793.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7125.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Trammell & Aitken Informational [Page 1]
RFC 7125 IPFIX tcpControlBits February 2014
1. Introduction
Octets 12 and 13 (counting from zero) of the TCP header encode the
data offset (header length) in 4 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 [RFC7011] only covers the original 6 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 3 was
developed and approved through the IE-DOCTORS process [RFC7013] in
August 2013. Section 5.1 of [RFC7013] 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
Information Element registry that were added with IETF consensus
require IETF consensus for revision or deprecation". Since the
tcpControlBits Information Element was originally defined in
[RFC5102], an IETF Proposed Standard, any revision of this
Information Element definition requires IETF Consensus. The
publication of this document fulfills that requirement.
Section 3 defines the revised tcpControlBits Information Element as
in Section 9.1 of [RFC7013].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
3. The tcpControlBits Information Element
ElementId: 6
Data Type: unsigned16
Data Type Semantics: flags
Trammell & Aitken Informational [Page 2]
RFC 7125 IPFIX tcpControlBits February 2014
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] [RFC3168] [RFC3540]:
MSb LSb
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