IPFIX Working Group B. Trammell
Internet-Draft ETH Zurich
Intended status: Informational April 16, 2014
Expires: October 18, 2014
Textual Representation of IPFIX Abstract Data Types
draft-ietf-ipfix-text-adt-04.txt
Abstract
This document defines UTF-8 representations for IPFIX abstract data
types, to support interoperable usage of the IPFIX Information
Elements with protocols based on textual encodings.
Status of This Memo
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This Internet-Draft will expire on October 18, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Identifying Information Elements . . . . . . . . . . . . . . 3
4. Data Type Encodings . . . . . . . . . . . . . . . . . . . . . 3
4.1. octetArray . . . . . . . . . . . . . . . . . . . . . . . 3
4.2. unsigned8, unsigned16, unsigned32, and unsigned64 . . . . 4
4.3. signed8, signed16, signed32, and signed64 . . . . . . . . 5
4.4. float32 and float64 . . . . . . . . . . . . . . . . . . . 6
4.5. boolean . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.6. macAddress . . . . . . . . . . . . . . . . . . . . . . . 7
4.7. string . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.8. dateTime* . . . . . . . . . . . . . . . . . . . . . . . . 7
4.9. ipv4Address . . . . . . . . . . . . . . . . . . . . . . . 8
4.10. ipv6Address . . . . . . . . . . . . . . . . . . . . . . . 8
4.11. basicList, subTemplateList, and subTemplateMultiList . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Appendix A. Example . . . . . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
The IPFIX Information Model[RFC7012] provides a set of abstract data
types for the IANA IPFIX Information Element Registry [IANA-IPFIX],
which contains a rich set of Information Elements for description of
information about network entities and network traffic data, and
abstract data types for these Information Elements. The IPFIX
Protocol Specification [RFC7011], in turn, defines a big-endian
binary encoding for these abstract data types suitable for use with
the IPFIX Protocol.
However, present and future operations and management protocols and
applications may use textual encodings, and generic framing and
structure, as in JSON or XML. A definition of canonical textual
encodings for the IPFIX abstract data types would allow this set of
Information Elements to be used for such applications, and for these
applications to interoperate with IPFIX applications at the
Information Element definition level.
In most cases where a textual representation will be used, an
explicit tradeoff is made for human readability or manipulability
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over compactness; this assumption is used in defining standard
representations of IPFIX ADTs.
Note that templating or other mechanisms for data description for
such applications and protocols are application specific, and
therefore out of scope for this document: only Information Element
identification and data value representation are defined here.
2. Terminology
Capitalized terms defined in the IPFIX Protocol Specification
[RFC7011] and the IPFIX Information Model [RFC7012] are used in this
document as defined in those documents. In addition, this document
defines the following terminology for its own use:
Enclosing Context
A textual representation of IPFIX data values is applied to use
the IPFIX Information Model within some existing textual format
(e.g. XML, JSON). This outer format is referred to as the
Enclosing Context within this document. Enclosing Contexts define
escaping and quoting rules for represented data values.
3. Identifying Information Elements
The IPFIX Information Element Registry [IANA-IPFIX] defines a set of
Information Elements numbered by Information Element Identifiers and
named for human-readability. These Information Element Identifiers
are meant for use with the IPFIX protocol, and have little meaning
when applying the IPFIX Information Element Registry to textual
representations.
Instead, applications using textual representations of Information
Elements should use Information Element names to identify them; see
Appendix A for examples illustrating this principle.
4. Data Type Encodings
Each subsection of this section defines a textual encoding for the
abstract data types defined in [RFC7012]. This section uses ABNF,
including the Core Rules in Appendix B of [RFC5234], to describe the
format of textual representations of IPFIX abstract data types.
4.1. octetArray
If the Enclosing Context defines a representation for binary objects,
that representation should be used.
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Otherwise, since the goal of textual representation of Information
Elements is human-readability over compactness, the values of
Information Elements of the octetArray data type are represented as a
string of pairs of hexadecimal digits, one pair per byte, in the
order the bytes would appear on the wire were the octetArray encoded
directly in IPFIX per [RFC7011]. Whitespace may occur between any
pair of digits to assist in human readability of the string, but is
not necessary, and is disregarded by any process reading the string.
In ABNF:
hex-octet = 2HEXDIG
octetarray = 1*(hex-octet [WSP])
4.2. unsigned8, unsigned16, unsigned32, and unsigned64
If the Enclosing Context defines a representation for unsigned
integers, that representation should be used.
In the special case that the unsigned Information Element has
identifier semantics, and refers to a set of codepoints, either in an
external registry, a sub-registry, or directly in the description of
the Information Element, then the name or short description for that
codepoint may be used to improve readability.
Otherwise, the values of Information Elements of an unsigned integer
type may be represented either as unprefixed base-10 (decimal)
strings, as base-16 (hexadecimal) strings prefixed by "0x", or as
base-2 (binary) strings prefixed by "0b". In ABNF:
unsigned = 1*DIGIT / "0x" 1*HEXDIG / "0b" 1*BIT
Leading zeroes are allowed in any either encoding, and do not signify
base-8 (octal) encoding. Binary encoding is intended for use with
Information Elements with flag semantics, but can be used in any
case.
The encoded value must be in range for the corresponding abstract
data type or Information Element. Out of range values should be
interpreted as clipped to the implicit range for the Information
Element as defined by the abstract data type, or to the explicit
range of the Information Element if defined. Minimum and maximum
values for abstract data types are shown in Table 1 below.
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+------------+---------+----------------------------+
| type | minimum | maximum |
+------------+---------+----------------------------+
| unsigned8 | 0 | 255 |
| unsigned16 | 0 | 65 536 |
| unsigned32 | 0 | 42 94 967 295 |
| unsigned64 | 0 | 18 446 744 073 709 551 615 |
+------------+---------+----------------------------+
Table 1: Ranges for unsigned abstract data types
4.3. signed8, signed16, signed32, and signed64
If the Enclosing Context defines a representation for signed
integers, that representation should be used.
Otherwise, the values of Information Elements of signed integer types
should be represented as optionally-prefixed base-10 (decimal)
strings. In ABNF:
sign = "+" / "-"
signed = [sign] 1*DIGIT
If the sign is omitted, it is assumed to be positive. Leading zeroes
are allowed, and do not signify base-8 (octal) encoding. The
representation "-0" is explicitly allowed, and is equal to zero.
The encoded value must be in range for the corresponding abstract
data type or Information Element. Out of range values should be
interpreted as clipped to the implicit range for the Information
Element as defined by the abstract data type, or to the explicit
range of the Information Element if defined. Minimum and maximum
values for abstract data types are shown in Table 2 below.
+----------+---------------------------+----------------------------+
| type | minimum | maximum |
+----------+---------------------------+----------------------------+
| signed8 | -128 | +127 |
| signed16 | -32 768 | +32 767 |
| signed32 | -2 147 483 648 | +2 147 483 647 |
| signed64 | -9 223 372 036 854 775 | +9 223 372 036 854 775 807 |
| | 808 | |
+----------+---------------------------+----------------------------+
Table 2: Ranges for signed abstract data types
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4.4. float32 and float64
If the Enclosing Context defines a representation for floating point
numbers, that representation should be used.
Otherwise, the values of Information Elements of float32 or float64
types are represented as optionally sign-prefixed, optionally base-10
exponent-suffixed, floating point decimal numbers, as in
[IEEE.754.2008]. The special strings "NaN", "+inf", and "-inf"
represent not a number, positive infinity and negative infinity,
respectively.
In ABNF:
sign = "+" / "-"
exponent = ( "e" / "E" ) [sign] 1*3DIGIT
right-decimal = "." *DIGIT
mantissa = 1*DIGIT [right-decimal]
num = [sign] mantissa [exponent]
naninf = "NaN" / sign "inf"
float = num / naninf
The expressed value is ( mantissa * 10 ^ exponent ). If the sign is
omitted, it is assumed to be positive. If the exponent is omitted,
it is assumed to be zero. Leading zeroes may appear in the mantissa
and/or the exponent. Values must be within range for [IEEE.754.2008]
single or double precision numbers. Finite values outside the range
must be clamped to be within the range.
Note that, since this representation is meant for human readability,
writers may sacrifice precision to use a more human-readable
representation of a given value, at the expense of the ability to
recover the exact bit pattern at the reader.
4.5. boolean
If the Enclosing Context defines a representation for boolean values,
that representation should be used.
Otherwise, a true boolean value is represented by the literal string
"true", and a false boolean value with the literal string "false".
In ABNF:
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boolean-true = "true"
boolean-false = "false"
boolean = boolean-true / boolean-false
4.6. macAddress
MAC addresses are represented as IEEE 802 MAC-48 addresses,
hexadecimal bytes, most significant byte first, separated by colons.
In ABNF:
hex-octet = 2HEXDIG
macaddress = hex-octet 5( ":" hex-octet )
4.7. string
As Information Elements of the string type are simply UTF-8 encoded
strings, they are represented directly, subject to the escaping and
encoding rules of the Enclosing Context. If the Enclosing Context
cannot natively represent UTF-8 characters, the escaping facility
provided by the Enclosing Context must be used for non-representable
characters. Additionally, strings containing characters reserved in
the Enclosing Context (e.g. markup characters, quotes) must be
escaped or quoted according to the rules of the Enclosing Context.
4.8. dateTime*
Timestamp abstract data types are represented generally as in
[RFC3339], with two important differences. First, all IPFIX
timestamps are expressed in terms of UTC, so textual representations
of these Information Elements are explicitly in UTC as well. Time
zone offsets are therefore not required or supported. Second, there
are four timestamp abstract data types, separated by the precision
which they can express. Fractional seconds must be omitted in
dateTimeSeconds, expressed in milliseconds in dateTimeMilliseconds,
and so on.
In ABNF, taken from [RFC3339] and modified:
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date-fullyear = 4DIGIT
date-month = 2DIGIT ; 01-12
date-mday = 2DIGIT ; 01-28, 01-29, 01-30, 01-31
time-hour = 2DIGIT ; 00-23
time-minute = 2DIGIT ; 00-59
time-second = 2DIGIT ; 00-58, 00-59, 00-60
time-msec = "." 3DIGIT
time-usec = "." 6DIGIT
time-nsec = "." 9DIGIT
full-date = date-fullyear "-" date-month "-" date-mday
partial-time = time-hour ":" time-minute ":" time-second
datetimeseconds = full-date "T" partial-time
datetimemilliseconds = full-date "T" partial-time "." time-msec
datetimemicroseconds = full-date "T" partial-time "." time-usec
datetimenanoseconds = full-date "T" partial-time "." time-nsec
4.9. ipv4Address
IP version 4 addresses are represented in dotted-quad format, most-
significant-byte first, as it would in a Uniform Resource Identifier
[RFC3986]; the ABNF for an IPv4 address is taken from [RFC3986] and
reproduced below:
dec-octet = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255
ipv4address = dec-octet 3( "." dec-octet )
4.10. ipv6Address
IP version 6 addresses are represented as in section 2.2 of
[RFC4291], as updated by section 4 of [RFC5952]. The ABNF for an
IPv6 address is taken from [RFC3986] and reproduced below, using the
ipv4address production from the previous section:
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ls32 = ( h16 ":" h16 ) / ipv4address
; least-significant 32 bits of address
h16 = 1*4HEXDIG
; 16 bits of address represented in hexadecimal
; zeroes to suppressed as in RFC 5952
ipv6address = 6( h16 ":" ) ls32
/ "::" 5( h16 ":" ) ls32
/ [ h16 ] "::" 4( h16 ":" ) ls32
/ [ h16 ":" h16 ] "::" 3( h16 ":" ) ls32
/ [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
/ [ *3( h16 ":" ) h16 ] "::" h16 ":" ls32
/ [ *4( h16 ":" ) h16 ] "::" ls32
/ [ *5( h16 ":" ) h16 ] "::" h16
/ [ *6( h16 ":" ) h16 ] "::"
4.11. basicList, subTemplateList, and subTemplateMultiList
These abstract data types, defined for IPFIX Structured Data
[RFC6313], do not represent actual data types; they are instead
designed to provide a mechanism by which complex structure can be
represented in IPFIX below the template level. It is assumed that
protocols using textual Information Element representation will
provide their own structure. Therefore, Information Elements of
these Data Types are not useful in textual representations.
5. Security Considerations
The security considerations for the IPFIX Protocol [RFC7011] apply;
this document presents no additional security considerations.
Implementations of decoders of Information Element values using these
representations must take care to correctly handle invalid input, but
the encodings presented here are not special in that respect.
6. IANA Considerations
This document has no considerations for IANA.
7. Acknowledgments
Thanks to Paul Aitken, Andrew Feren, and Juergen Quittek for the
review and comments. Thanks to Dave Thaler and Stephan Neuhaus for
discussions which improved the floating-point representation section.
This work is materially supported by the European Union Seventh
Framework Programme under grant agreement 318627 mPlane.
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8. References
8.1. Normative References
[RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the
Internet: Timestamps", RFC 3339, July 2002.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952, August 2010.
[RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of
the IP Flow Information Export (IPFIX) Protocol for the
Exchange of Flow Information", STD 77, RFC 7011, September
2013.
[IANA-IPFIX]
Internet Assigned Numbers Authority, , "IP Flow
Information Export Information Elements
(http://www.iana.org/assignments/ipfix/ipfix.xml)",
November 2012.
8.2. Informative References
[RFC6313] Claise, B., Dhandapani, G., Aitken, P., and S. Yates,
"Export of Structured Data in IP Flow Information Export
(IPFIX)", RFC 6313, July 2011.
[RFC7012] Claise, B. and B. Trammell, "Information Model for IP Flow
Information Export (IPFIX)", RFC 7012, September 2013.
[RFC7013] Trammell, B. and B. Claise, "Guidelines for Authors and
Reviewers of IP Flow Information Export (IPFIX)
Information Elements", BCP 184, RFC 7013, September 2013.
[IEEE.754.2008]
Instute of Electrical and Electronic Engineers, ,
"Standard for Floating-Point Arithmetic (IEEE Standard
754)", August 2008.
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Appendix A. Example
In this section, we examine an IPFIX Template and a Data Record
defined by that Template, and show how that Data Record would be
represented in JSON according to the specification in this document.
Note that this is specifically NOT a recommendation for a particular
representation, merely an illustration of the encodings in this
document; the quoting and formatting in the example are JSON-
specific.
Figure 1 shows a Template in IESpec format as defined in section 10.1
of [RFC7013]. A Message containing this Template and a Data Record
is shown in Figure 2, and a corresponding JSON Object using the text
format defined in this document is shown in Figure 3.
flowStartMilliseconds(152)<dateTimeMilliseconds>[8]
flowEndMilliseconds(153)<dateTimeMilliseconds>[8]
octetDeltaCount(1)<unsigned64>[4]
packetDeltaCount(2)<unsigned64>[4]
sourceIPv6Address(27)<ipv4Address>[4]{key}
destinationIPv6Address(28)<ipv4Address>[4]{key}
sourceTransportPort(7)<unsigned16>[2]{key}
destinationTransportPort(11)<unsigned16>[2]{key}
protocolIdentifier(4)<unsigned8>[1]{key}
tcpControlBits(6)<unsigned8>[1]
flowEndReason(136)<unsigned8>[1]
Figure 1: Sample flow template in IESpec format
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1 2 3 4 5 6
0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x000a | length 135 | export time 1352140263 | msg
| sequence 0 | domain 1 | hdr
| SetID 2 | length 52 | tid 256 | fields 11 | tmpl
| IE 152 | length 8 | IE 153 | length 8 | set
| IE 1 | length 4 | IE 2 | length 4 |
| IE 27 | length 16 | IE 28 | length 16 |
| IE 7 | length 2 | IE 11 | length 2 |
| IE 4 | length 1 | IE 6 | length 1 |
| IE 136 | length 1 | SetID 256 | length 83 | data
| start time 1352140261135 | set
| end time 1352140262880 |
| octets 195383 | packets 88 |
| sip6 |
| 2001:0db8:000c:1337:0000:0000:0000:0002 |
| dip6 |
| 2001:0db8:000c:1337:0000:0000:0000:0003 |
| sp 80 | dp 32991 | prt 6 | tcp 19| fe 3 |
+-------------------------------------------------------+
Figure 2: IPFIX Message containing sample flow
{
"flowStartMilliseconds": "2012-11-05T18:31:01.135",
"flowEndMilliseconds": "2012-11-05T18:31:02.880",
"octetDeltaCount": 195383,
"packetDeltaCount": 88,
"sourceIPv6Address": "2001:db8:c:1337::2",
"destinationIPv6Address": "2001:db8:c:1337::3",
"sourceTransportPort": 80,
"destinationTransportPort": 32991,
"protocolIdentifier": "tcp",
"tcpControlBits": 19,
"flowEndReason": 3
}
Figure 3: JSON object containing sample flow
Author's Address
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Brian Trammell
Swiss Federal Institute of Technology Zurich
Gloriastrasse 35
8092 Zurich
Switzerland
Phone: +41 44 632 70 13
Email: ietf@trammell.ch
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