path: root/doc/rfc/rfc8272.txt

Independent Submission                                        C. Schmitt
Request for Comments: 8272                                    B. Stiller
Category: Informational                             University of Zurich
ISSN: 2070-1721                                              B. Trammell
                                                              ETH Zurich
                                                           November 2017


           TinyIPFIX for Smart Meters in Constrained Networks

Abstract

   This document specifies the TinyIPFIX protocol that is used for
   transmitting smart-metering data in constrained networks such as IPv6
   over Low-Power Wireless Personal Area Networks (6LoWPAN, RFC 4944).
   TinyIPFIX is derived from IP Flow Information Export (RFC 7011) and
   adopted to the needs of constrained networks.  This document
   specifies how the TinyIPFIX Data and Template Records are transmitted
   in constrained networks such as 6LoWPAN and how TinyIPFIX data can be
   converted into data that is not TinyIPFIX in a proxy device.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8272.

Copyright Notice

   Copyright (c) 2017 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
   (https://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.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Document Structure  . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Constraints . . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Hardware Constraints  . . . . . . . . . . . . . . . . . .   6
     3.2.  Energy Constraints  . . . . . . . . . . . . . . . . . . .   7
     3.3.  Packet Size Constraints . . . . . . . . . . . . . . . . .   7
     3.4.  Transport Protocol Constraints  . . . . . . . . . . . . .   8
   4.  Application Scenarios for TinyIPFIX . . . . . . . . . . . . .   9
   5.  Architecture for TinyIPFIX  . . . . . . . . . . . . . . . . .  11
   6.  TinyIPFIX Message Format  . . . . . . . . . . . . . . . . . .  14
     6.1.  TinyIPFIX Message Header  . . . . . . . . . . . . . . . .  15
     6.2.  TinyIPFIX Set . . . . . . . . . . . . . . . . . . . . . .  18
     6.3.  TinyIPFIX Template Record Format  . . . . . . . . . . . .  19
     6.4.  Field Specifier Format  . . . . . . . . . . . . . . . . .  20
     6.5.  TinyIPFIX Data Record Format  . . . . . . . . . . . . . .  21
   7.  TinyIPFIX Mediation . . . . . . . . . . . . . . . . . . . . .  21
     7.1.  Expanding the Message Header  . . . . . . . . . . . . . .  24
     7.2.  Translating the Set Headers . . . . . . . . . . . . . . .  25
     7.3.  Expanding the Template Record Header  . . . . . . . . . .  25
   8.  Template Management . . . . . . . . . . . . . . . . . . . . .  25
     8.1.  TCP/SCTP  . . . . . . . . . . . . . . . . . . . . . . . .  26
     8.2.  UDP . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  26
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  26
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  27
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  27
     11.2.  Informative References . . . . . . . . . . . . . . . . .  28
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  29
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  30



















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1.  Introduction

   Smart meters that form a constrained wireless network need an
   application-layer protocol that allows the efficient transmission of
   metering data from the devices to a central analysis device.  The
   meters used to build such networks are usually equipped with low-cost
   and low-power hardware.  This leads to constraints in computational
   capacities, available memory, and networking resources.

   The devices are often battery powered and are expected to run for a
   long time without having the possibility of recharging themselves.
   In order to save energy, smart meters often power off their wireless
   networking device.  Hence, they don't have a steady network
   connection; they are only part of the wireless network as needed when
   there is data to be exported.  A push protocol like TinyIPFIX, where
   data is transmitted autonomically from the meters to one or more
   collectors, is suitable for reporting metering data in such networks.

   TinyIPFIX is derived from IPFIX [RFC7011]; therefore, it inherits
   most of IPFIX's properties.  One of these properties is the
   separation of data and its data description by encoding the former in
   Data Sets and the latter in Template Sets.

   Transforming TinyIPFIX to IPFIX as per [RFC7011] is very simple and
   can be done on the border between the constrained network and the
   more general network.  The transformation between one form of IPFIX
   data into another is known as "IPFIX Mediation" [RFC5982].  Hence,
   smart-metering networks that are based on TinyIPFIX can be easily
   integrated into an existing IPFIX measurement infrastructure.

1.1.  Document Structure

   Section 2 introduces the terminology used in this document.
   Afterwards, hardware and software constraints in constrained
   networks, which will motivate our modifications to the IPFIX
   protocol, are discussed in Section 3.  Section 4 describes the
   application scenarios and Section 5 describes the architecture for
   TinyIPFIX.  Section 6 defines the TinyIPFIX protocol itself and
   discusses the differences between TinyIPFIX and IPFIX.  The Mediation
   Process from TinyIPFIX to IPFIX is described in Section 7.  Section 8
   defines the process of Template Management on the Exporter and the
   Collector.  Section 9 and Section 10 discuss the security and IANA
   considerations for TinyIPFIX.








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2.  Terminology

   Most of the terms used in this document are defined in [RFC7011].
   Each of these terms begins with a capital letter.  Most of the terms
   that are defined for IPFIX can be used to describe TinyIPFIX.  This
   document uses the term "IPFIX" to refer to IPFIX as defined in
   [RFC7011] and the term TinyIPFIX for the protocol specified in this
   draft document assuming constrained networks.  The prefix "Tiny" is
   added to IPFIX to distinguish between the IPFIX version and the
   TinyIPFIX version.

   The terms IPFIX Message, IPFIX Device, Set, Data Set, Template Set,
   Data Record, Template Record, Collecting Process, Collector,
   Exporting Process, and Exporter are defined as in [RFC7011].  The
   term IPFIX Mediator is defined in [RFC5982].  The terms Intermediate
   Process, IPFIX Proxy, IPFIX Concentrator are defined in [RFC6183].

   All the terms above have been adapted from the IPFIX definitions.  As
   they keep a similar notion but in a different context of constrained
   networks, the term "TinyIPFIX" now precedes the defined terms.

   The term "smart meter" is used to refer to constrained devices like
   wireless sensor nodes, motes, or any other kind of small constrained
   device that can be part of a network that is based on IEEE 802.15.4
   and 6LoWPAN [RFC4944].

   TinyIPFIX Exporting Process

      The TinyIPFIX Exporting Process is a process that exports
      TinyIPFIX Records.

   TinyIPFIX Exporter

      A TinyIPFIX Exporter is device that contains at least one
      TinyIPFIX Exporting Process.

   TinyIPFIX Collecting Process

      The TinyIPFIX Collecting Process is a process inside a device that
      is able to receive and process TinyIPFIX Records.

   TinyIPFIX Collector

      A TinyIPFIX Collector is a device that contains at least one
      TinyIPFIX Collecting Process.






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   TinyIPFIX Device

      A TinyIPFIX Device is a device that contains one or more TinyIPFIX
      Collectors or one or more TinyIPFIX Exporters.

   TinyIPFIX Smart Meter

      A TinyIPFIX Smart Meter is a device that contains the
      functionality of a TinyIPFIX Device.  It is usually equipped with
      one or more sensors that meter a physical quantity, like power
      consumption, temperature, or physical tampering with the device.
      Every TinyIPFIX Smart Meter MUST at least contain a TinyIPFIX
      Exporting Process.  It MAY contain a TinyIPFIX Collecting Process
      in order to work as a TinyIPFIX Proxy or TinyIPFIX Concentrator.

   TinyIPFIX Data Record

      A TinyIPFIX Data Record equals an IPFIX Data Record in [RFC7011].
      The term is used to distinguish between IPFIX and TinyIPFIX
      throughout this document.

   TinyIPFIX Template Record

      A TinyIPFIX Template Record is similar to an IPFIX Template Record
      in [RFC7011].  The Template Record Header is substituted with a
      TinyIPFIX Template Record Header and is otherwise equal to a
      Template Record.  See Section 6.3.

   TinyIPFIX Set

      The TinyIPFIX Set is a group of TinyIPFIX Data Records or
      TinyIPFIX Template Records with a TinyIPFIX Set Header.  Its
      format is defined in Section 6.2.

   TinyIPFIX Data Set

      The TinyIPFIX Data Set is a TinyIPFIX Set that contains TinyIPFIX
      Data Records.

   TinyIPFIX Template Set

      A TinyIPFIX Template Set is a TinyIPFIX Set that contains
      TinyIPFIX Template Records.








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   TinyIPFIX Message

      The TinyIPFIX Message is a message originated by a TinyIPFIX
      Exporter.  It is composed of a TinyIPFIX Message Header and one or
      more TinyIPFIX Sets.  The TinyIPFIX Message Format is defined in
      Section 6.

   TinyIPFIX Intermediate Process

      A TinyIPFIX Intermediate Process is an IPFIX Intermediate Process
      that can handle TinyIPFIX Messages.

   TinyIPFIX Proxy

      A TinyIPFIX Proxy is an IPFIX Proxy that can handle TinyIPFIX
      Messages.

   TinyIPFIX Concentrator

      A TinyIPFIX Concentrator is device that can handle TinyIPFIX
      Messages (e.g., pre-process them) and is not constrained.

   TinyIPFIX Proxy

      A TinyIPFIX Proxy is an IPFIX Proxy that can handle TinyIPFIX
      Messages and is not constrained.

   A TinyIPFIX Transport Session is defined by the communication between
   a TinyIPFIX Exporter (identified by an 6LoWPAN-Address, the Transport
   Protocol, and the Transport Port) and a TinyIPFIX Collector
   (identified by the same properties).

   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
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Constraints

3.1.  Hardware Constraints

   The target devices for TinyIPFIX are usually equipped with low-cost
   hardware; therefore, they face several constraints concerning CPU and
   memory [Schmitt09].  For example, the IRIS mote from Crossbow
   Technologies, Inc. has a size of 58 x 32 x 7 mm (without a battery
   pack) [IRIS].  Thus, there is little space for a micro-controller,
   memory (128 kb program flash, 512 kb measurement serial flash, 8 kb



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   RAM, 4 kb configuration EEPROM), and radio-frequency transceiver,
   which are located on the board.  The TelosB motes produced by
   Crossbow Technologies, Inc. [TelosB] and ADVANTIC SISTEMAS Y
   SERVICIOS S.L.  [Advantic] are similar sized, but offering more
   memory (48 kb flash, 1024 kb serial, flash, 10 kb RAM, 16 kb
   configuration EEPROM).  The same holds for OpenMote, but the offering
   is 512 kb flash and 32 kb RAM [openMote].

   Network protocols used on such hardware need to respect these
   constraints.  They must be simple to implement using little code and
   little run-time memory and should produce little overhead when
   encoding the application payload.

3.2.  Energy Constraints

   Smart meters that are battery powered have hard energy constraints
   [Schmitt09].  If two AA 2800-mAh batteries power the mote, they
   contain approximately 30,240 Joule of energy.  If they run out of
   power, their battery has to be changed, which means physical
   manipulation to the device is necessary.  Therefore, using as little
   energy as possible for network communication is desired.

   A smart-metering device can save a lot of energy, if it powers down
   its radio-frequency transceiver.  Such devices do not have permanent
   network connectivity; they are only part of the network as needed.  A
   push protocol, where only one side is sending data, is suitable for
   transmitting application data under such circumstances.  As the
   communication is unidirectional, a meter can completely power down
   its radio-frequency transceivers as long as it does not have any data
   to send.  If the metering device is able to keep a few measurements
   in memory, and if real-time metering is not a requirement, the
   TinyIPFIX Data Records can be pushed less frequently, therefore
   saving some more energy on the radio-frequency transceivers.

3.3.  Packet Size Constraints

   TinyIPFIX is mainly targeted for the use in 6LoWPAN networks, which
   are based on IEEE 802.15.4 [RFC4944].  However, the protocol can also
   be used to transmit data in other networks when a mediator is used
   for translating the TinyIPFIX data into the data format used in the
   other network (e.g., IPFIX).  And the protocol is able to map the
   6LoWPAN addresses to the addresses used in the other network.  This
   operation typically consists of per-message re-encapsulation and/or
   re-encoding.  As defined [RFC4944], IEEE 802.15.4 starts from a
   maximum physical layer packet size of 127 octets (aMaxPHYPacketSize)
   and a maximum frame overhead of 25 octets (aMaxFrameOverhead),
   leaving a maximum frame size of 102 octets at the media access
   control (MAC) layer.  On the other hand, IPv6 defines a minimum MTU



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   of 1280 octets.  Hence, fragmentation has to be implemented in order
   to transmit such large packets.  While fragmentation allows the
   transmission of large messages, its use is problematic in networks
   with high packet loss because the complete message has to be
   discarded if only a single fragment gets lost.

   TinyIPFIX enhances IPFIX by a header-compression scheme, which allows
   the header size overhead to be significantly reduced.  Additionally,
   the overall TinyIPFIX Message size is reduced, which reduces the need
   for fragmentation.

3.4.  Transport Protocol Constraints

   The IPFIX standard [RFC7011] defines several transport protocol
   bindings for the transmission of IPFIX Messages.  Stream Control
   Transmission Protocol (SCTP) support is REQUIRED for any IPFIX Device
   to achieve standard conformance [RFC7011], and its use is highly
   recommended.  However, sending IPFIX over UDP and TCP MAY also be
   implemented.

   This transport protocol recommendation is not suitable for TinyIPFIX.
   A header compression scheme that allows a compression of an IPv6
   header from 40 octets down to 2 octets is defined in 6LoWPAN.  There
   is a similar compression scheme for UDP, but there is no such
   compression for TCP or SCTP headers.  If header compression can be
   employed, more space for application payload is available.

   Therefore, using UDP on the transport layer for transmitting
   TinyIPFIX Messages is RECOMMENDED.  Furthermore, TCP or SCTP are
   currently not supported on some platforms, like on TinyOS [Harvan08].
   Hence, UDP may be the only option.

   Every TinyIPFIX Exporter and Collector MUST implement UDP transport-
   layer support for transmitting data in a constrained network
   environment.  It MAY also offer TCP or SCTP support.  In the case in
   which TCP or SCTP MAY be used, power consumption will grow and the
   available size of application payload compared to the use of UDP May
   be reduced.  If TinyIPFIX is transmitted over a unconstrained
   network, using SCTP as a transport-layer protocol is RECOMMENDED.
   TinyIPFIX works independent of the target environment, because it
   MUST only be ensured that all intermediate devices can understand
   TinyIPFIX and be able to extract needed packet information (e.g., IP
   destination address).  TinyIPFIX messages can be included in other
   transport protocols in the payload whenever is necessary, making
   TinyIPFIX highly flexible and usable for different communication
   protocols (e.g., Constrained Application Protocol (CoAP), UDP, TCP).
   TinyIPFIX itself just specifies a messages format for the collected
   data to be transmitted.



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   The constraints on UDP usage given in Section 6.2 of [RFC5153] apply
   to TinyIPFIX as well.  TinyIPFIX is not intended for use over the
   open Internet.  In general, the networks on which it runs are
   considered dedicated for sensor operations and are under the control
   of a single administrative domain.

4.  Application Scenarios for TinyIPFIX

   TinyIPFIX is derived from IPFIX [RFC7011]; therefore, it is a
   unidirectional push protocol assuming UDP usage.  This means all
   communication that employs TinyIPFIX is unidirectional from an
   Exporting Process to a Collecting Process.  Hence, TinyIPFIX only
   fits for application scenarios where meters transmit data to one or
   more Collectors.  In case pull requests should also be supported by
   TinyIPFIX, it is RECOMMENDED not to change the code of TinyIPFIX much
   to get along with the restricted memory available [Schmitt2017].
   Meaning including just a one bit field, called type, to distinguish
   between push and pull messages would be feasible, but the filtering
   SHOULD be done by the gateway and not by the constrained device;
   meaning if a pull is performed, the constrained device is triggered
   to create a TinyIPFIX message immediately as usual, set the type
   field to one instead of zero (for a push message), and send message
   to the gateway.  At the gateway, the filtering is performed based on
   the pull request.

   If TinyIPFIX is used over UDP, as recommended, packet loss can occur.
   Furthermore, if an initial Template Message gets lost, and is
   therefore unknown to the Collector, all TinyIPFIX Data Sets that
   reference this Template cannot be decoded.  Hence, all these Messages
   are lost if they are not cached by the Collector.  It should be clear
   to an application developer that TinyIPFIX can only be used over UDP
   if these TinyIPFIX Message losses are not a problem.  To avoid this
   loss, it is RECOMMENDED to repeat the Template Message periodically,
   keeping in mind that a Template never changes for a constrained
   device after deployment.  Even when Template Messages become lost in
   the network, the data can be manually translated later when the
   Template Messages is re-sent.  Including an acknowledgement mechanism
   is NOT RECOMMENDED due to overhead, because this would require
   storage of any sent data on the constrained devices until it was
   acknowledged.  In critical applications, it is RECOMMENDED to repeat
   the Template Message more often.

   TinyIPFIX over UDP is especially not a suitable protocol for
   applications where sensor data trigger policy decisions or
   configuration updates for which packet loss is not tolerable.






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   Applications that use smart sensors for accounting purposes for long-
   term measurements can benefit from the use of TinyIPFIX.  One
   application for IPFIX is long-term monitoring of large physical
   volumes.  In [Tolle05], Tolle et al. built a system for monitoring a
   "70-meter tall redwood tree, at a density interval of 5 minutes in
   time and 2 meters in space".  The sensor node infrastructure was
   deployed to measure the air temperature, relative humidity, and
   photosynthetically active solar radiation over a long-term period.

   TinyIPFIX is a good fit for such scenarios.  Data can be measured by
   the sensors of the TinyIPFIX Smart Meter over several 5-minute time
   intervals; the measurements can be accumulated into a single
   TinyIPFIX Message.  As soon as enough measurements are stored in the
   TinyIPFIX Message, e.g., if the TinyIPFIX Message size fills the
   available payload in a single IEEE 802.15.4 packet, the wireless
   transceiver can be activated and the TinyIPFIX Message can be
   exported to a TinyIPFIX Collector.

   Similar sensor networks have been built to monitor the habitat of
   animals, e.g., in the "Great Duck Island Project" [GreatDuck]
   [SMPC04].  The purpose of the sensor network was to monitor the birds
   by deploying sensors in and around their burrows.  The measured
   sensor data was collected and stored in a database for offline
   analysis and visualization.  Again, the sensors can perform their
   measurements periodically, accumulate the sensor data, and export
   them to a TinyIPFIX Collector.

   Other application scenarios for TinyIPFIX could be applications where
   sensor networks are used for long-term structural health monitoring
   in order to investigate long-term weather conditions on the structure
   of a building.  For example, a smart-metering network has been built
   to monitor the structural health of the Golden Gate Bridge [Kim07].
   If a sensor network is deployed to perform a long-term measurement of
   the structural integrity, TinyIPFIX can be used to collect the
   sensor-measurement data.

   If an application developer wants to decide whether to use TinyIPFIX
   for transmitting data from smart meters, he must take the following
   considerations into account:

   1.  The application should require a push protocol by default.  The
       timing intervals of when to push data should be predefined before
       deployment.  The property above allows a TinyIPFIX Smart Meter to
       turn off its wireless device in order to save energy, as it does
       not have to receive any data.






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   2.  If real-time reporting is not required, the application might
       benefit from combining several measurements into a single
       TinyIPFIX Message, causing delay but lowering traffic in the
       network.  TinyIPFIX easily allow the combination of several
       measurements into a single TinyIPFIX Message (or a single
       packet).  This combination can happen on the TinyIPFIX Smart
       Meter that combines several of its own measurements.  Or, it can
       happen within a multi-hop wireless network where one IPFIX Proxy
       combines several TinyIPFIX Messages into a single TinyIPFIX
       Message before forwarding them.

   3.  The application must accept potential packet loss.  TinyIPFIX
       only fits for applications where metering data is stored for
       accounting purposes and not for applications where the sensor
       data triggers configuration changes or policy decisions, except
       when Message loss is acceptable for some reason.

   4.  The application must not require per-message export timestamps
       (e.g., for auditing).  TinyIPFIX removes export timestamps,
       generally only useful for Template Management operations, which
       it also does not support, from IPFIX.  This is a minor
       inconvenience, since per-record timestamp Information Elements
       are also available in IPFIX.

5.  Architecture for TinyIPFIX

   The TinyIPFIX architecture is similar to the IPFIX architecture,
   which is described in [RFC5470].  The most common deployment of
   TinyIPFIX Smart Meters is shown in Figure 1, where each TinyIPFIX
   Smart Meter can have different sensors available (e.g., IRIS:
   Temperature, Humidity, Sound; TelosB: Temperature, Bridgeness,
   Humidity, GPS) building the sensor data.



















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        +------------------------+     +------------------------+
        |     TinyIPFIX Device   | ... |     TinyIPFIX Device   |
        |   [Exporting Process]  |     |   [Exporting Process]  |
        +------------------------+     +------------------------+
                  |                                  |
        TinyIPFIX |                                  | TinyIPFIX
                  |                                  |
                  v                                  v
                  +----------------------------------+
                                  |
                                  v
                      +----------------------------+
                      |    TinyIPFIX Collector     |
                      |  [Collecting Process(es)]  |
                      +----------------------------+
                                  |
                                  v
                        +-----------------------+
                        |                       |
                        v                       v
               +----------------+     +----------------+
               |[*Application 1]| ... |[*Application n]|
               +----------------+     +----------------+

              Figure 1: Direct Transmission between TinyIPFIX
                         Devices and Applications

   A TinyIPFIX Smart Meter (S.M.) receives measurement data from its
   internal sensors to create its TinyIPFIX Messages.  Then, it encodes
   the results into a TinyIPFIX Message using a TinyIPFIX Exporting
   Process and exports this TinyIPFIX Message to one or more TinyIPFIX
   Collectors.  The TinyIPFIX Collector runs one or more applications
   that process the collected sensor data.  The TinyIPFIX Collector can
   be deployed on unconstrained devices at the constrained network
   border.

   A second way to deploy TinyIPFIX Smart Meter can employ accumulation
   on TinyIPFIX Messages during their journey through the constrained
   network as shown in Figure 2.  This accumulation can be performed by
   TinyIPFIX Concentrators.  Such devices must have enough resources to
   perform the accumulation.










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      +------------------------+     +------------------------+
      |     TinyIPFIX Device   | ... |     TinyIPFIX Device   |
      |   [Exporting Process]  |     |   [Exporting Process]  |
      +------------------------+     +------------------------+
                |                                  |
      TinyIPFIX |                                  | TinyIPFIX
                |                                  |
                v                                  v
                +----------------------------------+
                                  |
                                  v
                      +------------------------+
                      | TinyIPFIX Concentrator |
                      |  [Collecting  Process] |
                      |  [Exporting Process]   |
                      +------------------------+
                                  |
                        TinyIPFIX |
                                  |
                                  v
                     +--------------------------+
                     |        Collector         |
                     | [Collecting Process(es)] |
                     +--------------------------+

                    Figure 2: Accumulation of TinyIPFIX

   TinyIPFIX Smart Meters send their data to a TinyIPFIX Concentrator,
   which needs to have enough storage space to store the incoming data.
   If the TinyIPFIX Concentrator is hosted in a TinyIPFIX Smart Meter,
   it MAY also be able to collect data from it sensors, if activated.
   It may also accumulate the incoming data with its own measurement
   data.  The accumulated data can then be re-exported to one or more
   Collectors.  In that case, the TinyIPFIX Concentrator can be viewed
   as receiving data from multiple Smart Meters: one locally and some
   remotely.

   The last deployment, shown in Figure 3, employs another TinyIPFIX
   Mediation process.












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        +-------------------------+     +-------------------------+
        |   Remote Smart Meter    |     |    Local Smart Meter    |
        +-------------------------+     +-------------------------+
        |    TinyIPFIX Device     |     |    TinyIPFIX Device     |
        |   [Exporting Process]   |     |   [Exporting Process]   |
        +-------------------------+     +-------------------------+
                             |               |
                   TinyIPFIX |               | TinyIPFIX
                             |               |
                             v               v
                        +-------------------------+
                        | TinyIPFIX Concentrator  |
                        |  [Collecting  Process]  |
                        +-------------------------+

                       Figure 3: TinyIPFIX Mediator

   In this deployment, the TinyIPFIX Smart Meters transmit their
   TinyIPFIX Messages to one node, e.g., the base station, which
   translates the TinyIPFIX Messages to IPFIX Messages.  The IPFIX
   Messages can then be exported into an existing IPFIX infrastructure.
   The Mediation process from TinyIPFIX to IPFIX is described in
   Section 7.

6.  TinyIPFIX Message Format

   A TinyIPFIX IPFIX Message starts with a TinyIPFIX Message Header,
   followed by one or more TinyIPFIX Sets.  The TinyIPFIX Sets can be
   either of type TinyIPFIX Template Set or of type TinyIPFIX Data Set.
   A TinyIPFIX Message MUST only contain one type of TinyIPFIX Set.  The
   format of the TinyIPFIX Message is shown in Figure 4.

           +----------------------------------------------------+
           | TinyIPFIX Message Header                           |
           +----------------------------------------------------+
           | TinyIPFIX Set                                      |
           +----------------------------------------------------+
           | TinyIPFIX Set                                      |
           +----------------------------------------------------+
           ...
           +----------------------------------------------------+
           | TinyIPFIX Set                                      |
           +----------------------------------------------------+

                    Figure 4: TinyIPFIX Message Format






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6.1.  TinyIPFIX Message Header

   The TinyIPFIX Message Header is derived from the IPFIX Message
   Header, with some optimization using field compression.  The IPFIX
   Message Header from [RFC7011] is shown in Figure 5.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Version Number          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Export Time                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Sequence Number                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Observation ID                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 5: IPFIX Message Header

   The length of the IPFIX Message Header is 16 octets, and every IPFIX
   Message has to be started with it.  The TinyIPFIX Message Header
   needs to be smaller due to the packet size constraints discussed in
   Section 3.3.  The TinyIPFIX Header consists of a fixed part of three
   octets as shown in Figure 6, followed by a variable part as shown in
   Figures 7 to 10.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |E|E| SetID |        Length     | Sequence      | Ext. Sequence |
     |1|2|Lookup |                   | Number        |  Number       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Ext. SetID    |
     +-+-+-+-+-+-+-+-+

             Figure 6: Format of the TinyIPFIX Message Header
                    including Fixed and Optional Parts

   The fixed part has a length of 3 octets and consists of the "E1"
   field (1 bit), the "E2" field (1 bit), the "SetID Lookup" field (4
   bits), the "Length" field (10 bits), and the "Sequence Number" field
   (8 bits).  The variable part has a variable length defined by the
   "E1" and "E2" fields in the fixed header.  The four variants are
   illustrated in Figure 7 to Figure 10 below.






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     0                   1                   2
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0|0| SetID |        Length     | Sequence      |
    | | |Lookup |                   | Number        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 7: TinyIPFIX Message Header Format if E1 = E2 = 0

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |1|0| SetID |        Length     | Sequence      | Ext. SetID    |
    | | |Lookup |                   | Number        |               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 8: TinyIPFIX Message Header Format if E1 = 1 and E2 = 0

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |E|E| SetID |        Length     | Sequence      | Ext. Sequenz  |
    |1|2|Lookup |                   | Number        |  Number       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 9: TinyIPFIX Message Header Format if E1 = 0 and E2 = 1

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |1|1| SetID |        Length     | Sequence      | Ext. Sequenz  |
    | | |Lookup |                   | Number        |  Number       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Ext. SetID    |
    +-+-+-+-+-+-+-+-+

      Figure 10: TinyIPFIX Message Header Format if E1 = E2 = 1

   The fixed header fields are defined as follows [Kothmayr10]
   [Schmitt2014]:

   E1 and E2

      The bits marked "E1" and "E2" control the presence of the field
      "Ext.  SetID" and the presence of the field "Ext.  Sequence
      Number", respectively.





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      In case E1 = E2 = 0, the TinyIPFIX Message Header has the format
      shown in Figure 7.  The fields Extended Sequence Number and
      Extended SetID MUST NOT be present.

      When E1 = 1, the extended SetID field MUST be present.  Custom
      SetIDs can be specified in the extended SetID field, setting all
      SetID Lookup bits to 1 (cf.  Figure 8.)  When evaluated, the value
      specified in the extended SetID field is shifted left by 8 bits to
      prevent collisions with the reserved SetIDs 0-255.  To reference
      these, shifting can be disabled by setting all SetID lookup bits
      to 1.

      Depending on the application, sampling rates might be larger than
      in typical constrained networks (e.g., Wireless Sensor Networks
      (WSNs), Cyber-Physical-Systems (CPS)); thus, they may have a large
      quantity of records per packet.  In order to make TinyIPFIX
      applicable for those cases, E2 = 1 is set (cf.  Figure 9).  This
      means the Extended Sequence Number field MUST be present, offering
      8-bit more sequence numbers as usual.  Depending on the
      constrained network settings, the combination E1 = E2 = 1 is also
      possible, resulting in the maximum TinyIPFIX Message header shown
      in Figure 10 where the Extended Sequence Number field and Extended
      SetID field MUST both be present.

   SetID Lookup

      This field acts as a lookup field for the SetIDs and provides
      shortcuts to often used SetIDs.  Four values are defined:

      Value = 0; Look up extended SetID field, Shifting enabled.

      Value = 1; SetID = 2 and message contains a Template definition.

      Value = 2; SetID = 256 and message contains Data Record for
      Template 256.  This places special importance on a single template
      ID, but, since most sensor nodes only define a single template
      directly after booting and continue to stream data with this
      template ID during the whole session lifetime, this shorthand is
      useful for this case.

      Value = 3-14; SetIDs are reserved for future extensions.

      Value = 15; look up extended SetID field, shifting enabled.

   Length

      The length field has a fixed length of 10 bits.




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   Sequence Number

      Due to the low sampling rate in typical WSNs, the "Sequence
      Number" field is only one byte long.  However, some applications
      may have a large quantity of records per packet.  In this case,
      the sequence field can be extended to 16 bit by setting the E2-bit
      to 1.

   Since TinyIPFIX packets are always transported via a network
   protocol, which specifies the source of the packet, the "Observation
   Domain" can be equated with the source of a TinyIPFIX packet.
   Therefore, this IPFIX field has been removed from the TinyIPFIX
   Header.  Should an application require explicit Observation Domain
   information, each Data Record in the TinyIPFIX data message may
   contain an Observation Domain ID Information Element; see Section 3.1
   of [RFC7011].  The version field has been removed since the SetID
   lookup field provides room for future extensions.  The specification
   of a 32-bit timestamp in seconds would require the time
   synchronization across a wireless-sensor network and produces too
   much overhead.  Thus, the "Export Time" field has been removed.  If
   applications should require a concrete observation time (e.g.,
   timestamp), it is RECOMMENDED to include it as a separate Information
   Element in the TinyIPFIX Records.

6.2.  TinyIPFIX Set

   A TinyIPFIX Set is a set of TinyIPFIX Template or TinyIPFIX Data
   Records.  Depending on the TinyIPFIX Record type, the TinyIPFIX Set
   can be either a TinyIPFIX Template Set or a TinyIPFIX Data Set. Every
   TinyIPFIX Set starts with a TinyIPFIX Set Header and is followed by
   one or more TinyIPFIX Records.

   The IPFIX Set Header consists of a 2-octet "Set ID" field and a
   2-octet "Length" field.  These two fields are compressed to 1 octet
   each for the TinyIPFIX Set Header.  The format of the TinyIPFIX Set
   Header is shown in Figure 11.

    0                   1
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Tiny Set ID  |    Length     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 11: TinyIPFIX Set Header







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   The two fields are defined as follows:

   TinyIPFIX Set ID

      The "Tiny Set ID" identifies the type of data that is transported
      in the TinyIPFIX Set. A TinyIPFIX Template Set is identified by
      TinyIPFIX Set ID 2.  This corresponds to the Template Set IDs that
      are used by IPFIX [RFC7011].  TinyIPFIX Set ID number 3 MUST NOT
      be used, as Options Templates are not supported; a TinyIPFIX
      Collector MUST ignore and SHOULD log any Set with Set ID 3.  All
      values from 4 to 127 are reserved for future use.  Values above
      127 are used for TinyIPFIX Data Sets.

   Length

      The "Length" Field contains the total length of the TinyIPFIX Set,
      including the TinyIPFIX Set Header.

6.3.  TinyIPFIX Template Record Format

   The format of the TinyIPFIX Template Records is shown in Figure 12.
   The TinyIPFIX Template Record starts with a TinyIPFIX Template Record
   Header and this is followed by one or more Field Specifiers.  The
   Field Specifier format is defined as in Section 6.4 and is identical
   to the Field Specifier definition in [RFC7011].

           +--------------------------------------------------+
           | TinyIPFIX Template Record Header                 |
           +--------------------------------------------------+
           | Field Specifier                                  |
           +--------------------------------------------------+
           | Field Specifier                                  |
           +--------------------------------------------------+
           ...
           +--------------------------------------------------+
           | Field Specifier                                  |
           +--------------------------------------------------+

                   Figure 12: TinyIPFIX Template Format

   The format of the TinyIPFIX Template Record Header is shown in
   Figure 13.









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    0                   1
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Template ID |  Field Count  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 13: TinyIPFIX Template Record Header

   TinyIPFIX Template ID

      Each TinyIPFIX Template Record must have a unique TinyIPFIX
      Template ID (Comp.  Temp ID) between 128 and 255.  The TinyIPFIX
      Template ID must be unique for the given TinyIPFIX Transport
      Session.

   Field Count

      The number of fields placed in the TinyIPFIX Template Record.

6.4.  Field Specifier Format

   The type and length of the transmitted data is encoded in Field
   Specifiers within TinyIPFIX Template Records.  The Field Specifier is
   shown in Figure 14 and is identical with the Field Specifier that was
   defined for IPFIX [RFC7011].

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |E|  Information Element ident. |        Field Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Enterprise Number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 14: TinyIPFIX Data Field Specifier

   Where:

   E

      Enterprise bit.  This is the first bit of the Field Specifier.  If
      this bit is zero, the Information Element Identifier identifies an
      IETF-specified Information Element, and the four-octet Enterprise
      Number field MUST NOT be present.  If this bit is one, the
      Information Element Identifier identifies an enterprise-specific
      Information Element, and the Enterprise Number field MUST be
      present.




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   Information Element Identifier

      A numeric value that represents the type of Information Element.

   Field Length

      The length of the corresponding encoded Information Element, in
      octets.  Refer to [RFC7012].  The value 65535 is illegal in
      TinyIPFIX, as variable-length Information Elements are not
      supported.

   Enterprise Number

      IANA Private Enterprise Number of the authority defining the
      Information Element identifier in this Template Record.

   Vendors can easily define their own data model by registering a
   Enterprise ID with IANA.  Using their own Enterprise ID, they can use
   any ID in the way they want them to use.

6.5.  TinyIPFIX Data Record Format

   The Data Records are sent in TinyIPFIX Data Sets.  The format of the
   Data Records is shown in Figure 15 and matches the Data Record format
   from IPFIX.

   +--------------------------------------------------+
   | Field Value                                      |
   +--------------------------------------------------+
   | Field Value                                      |
   +--------------------------------------------------+
   ...
   +--------------------------------------------------+
   | Field Value                                      |
   +--------------------------------------------------+

               Figure 15: Data Record Format

7.  TinyIPFIX Mediation

   There are two types of TinyIPFIX Intermediate Processes.  The first
   one can occur on the transition between a constrained network (e.g.,
   6LoWPAN) and the unconstrained network.  This mediation changes the
   network and transport protocol from 6LoWPAN preferring UDP to
   IP/(SCTP|TCP|UDP) and is shown in Figure 16.






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                   +-----------------------+
                   |    TinyIPFIX Device   |
                   | [Exporting Process]   |
                   +-----------------------+
                                     |
                           TinyIPFIX |
                   over 6LoWPAN/UDP  |
                                     v
                  +-------------------------+
                  |   TinyIPFIX mediator    |
                  |   [Collecting Process]  |
                  |   [Exporting Process]   |
                  +-------------------------+
                                     |
                  TinyIPFIX          |
                  IP/(UDP/SCTP|TCP)  |
                                     v
                  +--------------------------+
                  |      Collector           |
                  | [Collecting Process(es)] |
                  +--------------------------+

          Figure 16: Translation from TinyIPFIX over 6LoWPAN/UDP
                    to TinyIPFIX over IP/(SCTP|TCP|UDP)

   The mediator removes the TinyIPFIX Messages from the 6LoWPAN/UDP
   packets and wraps them into the new network and transport protocols.
   Templates MUST be managed the same way as in the constrained
   environment after the translation to IP/(SCTP|UDP|TCP) (see
   Section 8).

   The second type of mediation transforms TinyIPFIX into IPFIX.  This
   process MUST be combined with the transport protocol mediation as
   shown in Figure 17.

















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                        +-----------------------+
                        |    TinyIPFIX Device   |
                        | [Exporting Process]   |
                        +-----------------------+
                                          |
                                TinyIPFIX |
                                          |
                                          v
                        +-------------------------+
                        |   TinyIPFIX mediator    |
                        |   [Collecting Process]  |
                        |   [Exporting Process]   |
                        +-------------------------+
                                          |
                              IPFIX       |
                        IP/(UDP/SCTP|TCP) |
                                          v
                        +--------------------------+
                        |      Collector           |
                        | [Collecting Process(es)] |
                        +--------------------------+

             Figure 17: Transformation from TinyIPFIX to IPFIX

   This mediation can also be performed by an IPFIX Collector before
   parsing the IPFIX message as shown in Figure 18.  There is no need
   for a parser from TinyIPFIX to IPFIX if such a mediation process can
   be employed in front of an existing IPFIX collector.


   +------------------------+                  +----------------------+
   |     TinyIPFIX Device   |    TinyIPFIX     |     IPFIX Mediator   |
   | [Exporting Processes]  |----------------->| [Collecting Process] |
   +------------------------+                  |  [Exporting Process] |
                                               |         |            |
                                               |         |IPFIX       |
                                               |         |            |
                                               |         v            |
                                               |   Collector          |
                                               | [Collecting Process] |
                                               +----------------------+

             Figure 18: Transformation from TinyIPFIX to IPFIX








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   The TinyIPFIX Mediation Process has to translate the TinyIPFIX
   Message Header, the TinyIPFIX Set Headers, and the TinyIPFIX Template
   Record Header into their counterparts in IPFIX.  Afterwards, the new
   IPFIX Message Length needs to be calculated and inserted into the
   IPFIX Message header.

7.1.  Expanding the Message Header

   The fields of the IPFIX Message Header that are shown in Figure 5 can
   be determined from a TinyIPFIX Message Header as follows:

   Version

      This is always 0x000a.

   Length

      The IPFIX Message Length can only be calculated after the complete
      TinyIPFIX Message has been translated.  The new length can be
      calculated by adding the length of the IPFIX Message Header, which
      is 16 octets, and the length of all Sets that are contained in the
      IPFIX Message.

   Export Time

      The "Export Time" MUST be generated by the Mediator, and contains
      the time in seconds since 00:00 UTC Jan 1, 1970, at which the
      IPFIX Message leaves the Mediator.

   Sequence Number

      If the TinyIPFIX Sequence Number has a length of 4 octets, the
      original value MUST be used for the IPFIX Message.  If the
      TinyIPFIX Sequence Number has a size of one or two octets, the
      TinyIPFIX Mediator MUST expand the TinyIPFIX Sequence Number into
      a four octet field.  If the TinyIPFIX Sequence Number was omitted,
      the Mediator needs to calculate the Sequence Number as per
      [RFC7011].

   Observation Domain ID

      Since the Observation Domain ID is used to scope templates in
      IPFIX, it MUST be set to a unique value per TinyIPFIX Exporting
      Process, using either a mapping algorithmically determined by the
      Intermediate Process or directly configured by an administrator.






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7.2.  Translating the Set Headers

   Both fields in the TinyIPFIX Set Header have a size of 1 octet and
   need to be expanded:

   Set ID

      The field needs to be expanded from 1 octet to 2 octets.  If the
      Set ID is below 128, no recalculation needs to be performed.  This
      is because all IDs below 128 are reserved for special messages and
      match the IDs used in IPFIX.  The TinyIPFIX Set IDs starting with
      128 identify TinyIPFIX Data Sets.  Therefore, every TinyIPFIX Set
      ID above number 127 needs to be incremented by number 128 because
      IPFIX Data Set IDs are numbered above 255.

   Set Length

      The field needs to be expanded from one octet to two octets.  It
      needs to be recalculated by adding a value of 2 octets to match
      the additional size of the Set Header.  For each TinyIPFIX
      Template Record that is contained in the TinyIPFIX Set, 2 more
      octets need to be added to the length.

7.3.  Expanding the Template Record Header

   Both fields in the TinyIPFIX Template Record Header have a length of
   one octet and therefore need translation:

   Template ID

      The field needs to be expanded from one octet to two octets.  The
      Template ID needs to be increased by a value of 128.

   Field Count

      The field needs to be expanded from one octet to 2 octets.

8.  Template Management

   As with IPFIX, TinyIPFIX Template Management depends on the transport
   protocol used.  If TCP or SCTP is used, it can be ensured that
   TinyIPFIX Templates are delivered reliably.  If UDP is used,
   reliability cannot be guaranteed: template loss can occur.  If a
   Template is lost on its way to the Collector, any following TinyIPFIX
   Data Records that refer to this TinyIPFIX Template cannot be decoded.
   Template Withdrawals are not supported in TinyIPFIX.  This is
   generally not a problem, because most sensor nodes only define a
   single static template directly after booting.



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8.1.  TCP/SCTP

   If TCP or SCTP is used for the transmission of TinyIPFIX, Template
   Management MUST be performed as defined in [RFC7011] for IPFIX, with
   the exception of Template Withdrawals, which are not supported in
   TinyIPFIX.  Template Withdrawals MUST NOT be sent by TinyIPFIX
   Exporters.

8.2.  UDP

   All specifications for Template Management from [RFC7011] apply
   unless specified otherwise in this document.

   TinyIPFIX Templates MUST be sent by a TinyIPFIX Exporter before any
   TinyIPFIX Data Set that refers to the TinyIPFIX Template is
   transmitted.  TinyIPFIX Templates are not expected to change over
   time in TinyIPFIX and, thus, they should be pre-shared.  TinyIPFIX
   Devices have a default setup when deployed; after booting, they
   announce their TinyIPFIX Template directly to the network and MAY
   repeat it if UDP is used.  Hence, a TinyIPFIX Template that has been
   sent once MAY NOT be withdrawn and MUST NOT expire.  If a TinyIPFIX
   Smart Meter wants to use another TinyIPFIX Template, it MUST use a
   new TinyIPFIX Template ID for the TinyIPFIX Template.

   While UDP is used, reliable transport of TinyIPFIX Templates cannot
   be, guaranteed and TinyIPFIX Templates can be lost.  A TinyIPFIX
   Exporter MUST expect TinyIPFIX Template loss.  Therefore, it MUST
   re-send its TinyIPFIX Templates periodically.  A TinyIPFIX Template
   MUST be re-sent after a fixed number N of TinyIPFIX Messages that
   contain TinyIPFIX Data Sets referring to the TinyIPFIX Template.  The
   number N MUST be configured by the application developer.
   Retransmission and the specification of N can be avoided if TinyIPFIX
   Exporter and TinyIPFIX Collector use pre-shared templates.

9.  Security Considerations

   The same security considerations as for the IPFIX Protocol [RFC7011]
   apply.

10.  IANA Considerations

   This document does not require any IANA actions.









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11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
              <https://www.rfc-editor.org/info/rfc4944>.

   [RFC5153]  Boschi, E., Mark, L., Quittek, J., Stiemerling, M., and P.
              Aitken, "IP Flow Information Export (IPFIX) Implementation
              Guidelines", RFC 5153, DOI 10.17487/RFC5153, April 2008,
              <https://www.rfc-editor.org/info/rfc5153>.

   [RFC5470]  Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
              "Architecture for IP Flow Information Export", RFC 5470,
              DOI 10.17487/RFC5470, March 2009,
              <https://www.rfc-editor.org/info/rfc5470>.

   [RFC5982]  Kobayashi, A., Ed. and B. Claise, Ed., "IP Flow
              Information Export (IPFIX) Mediation: Problem Statement",
              RFC 5982, DOI 10.17487/RFC5982, August 2010,
              <https://www.rfc-editor.org/info/rfc5982>.

   [RFC6183]  Kobayashi, A., Claise, B., Muenz, G., and K. Ishibashi,
              "IP Flow Information Export (IPFIX) Mediation: Framework",
              RFC 6183, DOI 10.17487/RFC6183, April 2011,
              <https://www.rfc-editor.org/info/rfc6183>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/info/rfc7011>.

   [RFC7012]  Claise, B., Ed. and B. Trammell, Ed., "Information Model
              for IP Flow Information Export (IPFIX)", RFC 7012,
              DOI 10.17487/RFC7012, September 2013,
              <https://www.rfc-editor.org/info/rfc7012>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.



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11.2.  Informative References

   [Advantic] ADVANTIC SISTEMAS Y SERVICIOS S.L.,
              <https://www.advanticsys.com/>, 2017.

   [GreatDuck]
              Mainwaring, A., Polastre, J., Szewczyk, R., Culler, D.,
              and J. Anderson, "Wireless Sensor Networks for Habitat
              Monitoring", In Proceedings of the 1st ACM international
              workshop on Wireless sensor networks and applications ACM,
              pp. 88-97, DOI 10.1145/570738.570751, 2002.

   [Harvan08] Harvan, M. and J. Schoenwaelder, "TinyOS Motes on the
              Internet: IPv6 over 802.15.4 (6LoWPAN)",
              DOI 10.1515/piko.2008.0042, December 2008.

   [IRIS]     Memsic, "Data Sheet IRIS", 2017,
              <http://www.memsic.com/userfiles/files/Datasheets/WSN/
              IRIS_Datasheet.pdf>.

   [Kim07]    Kim, S., Pakzad, S., Culler, D., Demmel, J., Fenves, G.,
              Glaser, S., and M. Turon, "Health monitoring of civil
              infrastructures using wireless sensor networks",
              Proceedings of the 6th international conference on
              Information processing in sensor networks (IPSN
              2007), Cambridge, MA, ACM Press, pp. 254-263,
              DOI 10.1145/1236360.1236395, April 2007.

   [Kothmayr10]
              Kothmayr, T., "Data Collection in Wireless Sensor Networks
              for Autonomic Home Networking", Bachelor Thesis, Technical
              University of Munich, Munich, Germany, January 2010.

   [openMote] openMote Technologies S.L., 2017, <http://openmote.com>.

   [Schmitt09]
              Schmitt, C. and G. Carle, "Applications for Wireless
              Sensor Networks", Handbook of Research on P2P and Grid
              Systems for Service-Oriented Computing: Models,
              Methodologies and Applications, Edited by Antonopoulos N.,
              Exarchakos G., Li M., and A. Liotta, Information Science
              Publishing, Chapter 46, pp. 1076-1091,
              ISBN: 978-1615206865, 2010.








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   [Schmitt2014]
              Schmitt, C., Kothmayr, T., Ertl, B., Hu, W., Braun, L.,
              and G. Carle, "TinyIPFIX: An efficient application
              protocol for data exchange in cyber physical systems",
              Computer Communications, ELSEVIER, Vol. 74, pp. 63-76,
              DOI 10.1016/j.comcom.2014.05.012, 2016.

   [Schmitt2017]
              Schmitt, C., Anliker, C., and B. Stiller, "Efficient and
              Secure Pull Requests for Emergency Cases Using a Mobile
              Access Framework", Managing the Web of Things: Linking the
              Real World to the Web, Edited by Sheng, M., Qin, Y., Yao,
              L., and B. Benatallah, Morgen Kaufmann (imprint of
              Elsevier), Chapter 8, pp. 229-247,
              ISBN: 978-0-12-809764-9, 2017.

   [SMPC04]   Szewczyk, R., Mainwaring, A., Polastre, J., and D. Culler,
              "An analysis of a large scale habitat monitoring
              application", Proceedings of the 2nd international
              conference on Embedded networked sensor systems (SenSys
              04), DOI 10.1145/1031495.1031521, November 2004.

   [TelosB]   Memsic, "Data Sheet TelosB", 2017,
              <http://www.memsic.com/userfiles/files/DataSheets/WSN/
              telosb_datasheet.pdf>.

   [Tolle05]  Tolle, G., Polastre, J., Szewczyk, R., Culler, D., Turner,
              N., Tu, K., Burgess, S., Dawnson, T., Buonadonna, P., Gay,
              D., and W. Hong, "A macroscope in the redwoods",
              Proceedings of the 3rd international conference on
              Embedded networked sensor systems (SenSys 05),
              DOI 10.1145/1098918.1098925, November 2005.

Acknowledgments

   Many thanks to Lothar Braun, Georg Carle, and Benoit Claise, who
   contributed significant work to earlier draft versions of this work,
   especially to the document titled "Compressed IPFIX for Smart Meters
   in Constrained Networks".

   Many thanks to Thomas Kothmayr, Michael Meister, and Livio Sgier, who
   implemented TinyIPFIX (except the mediator) for TinyOS 2.x and
   Contiki 2.7/3.0 for 3 different sensor platforms (IRIS, TelosB, and
   OpenMote).







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Authors' Addresses

   Corinna Schmitt
   University of Zurich
   Department of Informatics
   Communication Systems Group
   Binzmuehlestrasse 14
   Zurich  8050
   Switzerland

   Email: schmitt@ifi.uzh.ch


   Burkhard Stiller
   University of Zurich
   Department of Informatics
   Communication Systems Group
   Binzmuehlestrasse 14
   Zurich  8050
   Switzerland

   Email: stiller@ifi.uzh.ch


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

   Email: ietf@trammell.ch




















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