Network Working Group C. Schmitt Internet-Draft B. Stiller Intended status: Informational University of Zurich Expires: December 2, 2017 B. Trammell ETH Zurich May 31, 2017 TinyIPFIX for smart meters in constrained networks draft-schmitt-ipfix-tiny-02 Abstract This document specifies the TinyIPFIX protocol that serves for transmitting smart metering data in constrained networks such as 6LoWPAN [RFC4944]. TinyIPFIX is derived from IPFIX [RFC7011] 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 unTinyIPFIX data in a proxy device. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on December 2, 2017. 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 (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 Schmitt, et al. TinyIPFIX [Page 1] Internet-Draft TinyIPFIX May 2017 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Document structure . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Constraints . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Hardware constraints . . . . . . . . . . . . . . . . . . 6 3.2. Energy constraints . . . . . . . . . . . . . . . . . . . 6 3.3. Packet size constraints . . . . . . . . . . . . . . . . . 7 3.4. Transport protocol constraints . . . . . . . . . . . . . 7 4. Application scenarios for TinyIPFIX . . . . . . . . . . . . . 8 5. Architecture for TinyIPFIX . . . . . . . . . . . . . . . . . 10 6. TinyIPFIX Message Format . . . . . . . . . . . . . . . . . . 13 6.1. TinyIPFIX Message Header . . . . . . . . . . . . . . . . 14 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 . . . . . . . . . . . . . . . . . . . . . 27 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 12.1. Normative References . . . . . . . . . . . . . . . . . . 27 12.2. Informative References . . . . . . . . . . . . . . . . . 28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29 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. Schmitt, et al. TinyIPFIX [Page 2] Internet-Draft TinyIPFIX May 2017 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, but are only part of the wireless network as needed when there is data that needs to be exported. A push protocol like TinyIPFIX, where data is transmitted autonomic from the meters to one or more collectors, is suitable for reporting metering data in such networks. TinyIPFIX is derived from IPFIX [RFC7011] and therefore inherits most of its 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 draft. 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. 2. Terminology Most of the terms used in this draft are defined in [RFC7011]. All these terms are written with their first letter being capitalized. Most of the terms that are defined for IPFIX can be used to describe TinyIPFIX. This draft 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 term "Tiny" is used in front of the IPFIX term to distinguish between the IPFIX version and the TinyIPFIX version. Schmitt, et al. TinyIPFIX [Page 3] Internet-Draft TinyIPFIX May 2017 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 these 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 complements 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 IEEE802.15.4 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. 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 Schmitt, et al. TinyIPFIX [Page 4] Internet-Draft TinyIPFIX May 2017 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. 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. Schmitt, et al. TinyIPFIX [Page 5] Internet-Draft TinyIPFIX May 2017 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", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Constraints 3.1. Hardware constraints The target devices for TinyIPFIX are usually equipped with low-cost hardware and therefore 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) [Crossbow]. Thus, there is little space for micro controller, memory (128 kb program flash, 512 kb measurement serial flash, 8 kb RAM, 4 kb configuration EEPROM), and radio frequency transceiver, which are located on the board. Similar issues occure by TelosB produced by Crossbow Technologies Inc. [Crossbow] and Advantic Sys. Inc. [Advantic] but offering more memory (48 kb flash, 1024 kb serial flash, 10 kb RAM, 16 kb configuration EEPROM). 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]. By power supply of two 2 AA 2,800-mAh batteries this means approximately 30,240J. If they run out of power, their battery has to be changed, which means physical manipulation to the device is necessary. Using as little energy as possible for network communication is therefore desired. Schmitt, et al. TinyIPFIX [Page 6] Internet-Draft TinyIPFIX May 2017 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 but 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 translating the TinyIPFIX data into the data format used in the other network (e.g., IPFIX) and is able to map the 6LoWPAN addresses to the addresses used in the other network. 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. IPv6 on the other hand defines a minimum MTU 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. 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 Schmitt, et al. TinyIPFIX [Page 7] Internet-Draft TinyIPFIX May 2017 compression for TCP or SCTP headers. If header compression can be employed, more space for application payload is available. Using UDP on the transport layer for transmitting IPFIX Messages is therefore 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 case 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 non-constrained 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 n other transport protocols in the payload whenever is needed making TinyIPFIX highly flexible and usable for different communication protocols (e.g., COAP, UDP, TCP). TinyIPFIX itself just specifies a messages format for the collected data to be transmitted. 4. Application scenarios for TinyIPFIX TinyIPFIX is derived from IPFIX [RFC7011] and is therefore 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 request 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 feasable, but the filtering SHOULD be done by the gateway and not by the constrained device, meaning if a pull is performed the constained 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 sends message to the gateway. Where 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 Schmitt, et al. TinyIPFIX [Page 8] Internet-Draft TinyIPFIX May 2017 to an application developer, that TinyIPFIX can only be used over UDP if these TinyIPFIX Message losses are not a problem. Avoiding this loss it is RECOMMEND to repeat the Template Message periodically having in mind that a Template never changes for a constrained device after deployment. Even when Template Messages becomes lost in the network the data can be manually translated later when the Template Messages is resend. Including an acknowledgement mechanism is NOT RECOMMENDED due to overhead, because this would require storage of any send data on the constrained devices until it is acknowledged. In critial 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. Applications that use smart sensors for accounting purposes for long time 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 time period. TinyIPFIX is a good fit for such scenarios. The sensors of the TinyIPFIX Smart Meter can be queried over several 5 minute time intervals and the query results can be accumulated into a single TinyIPFIX Message. As soon as enough query results 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]. Schmitt, et al. TinyIPFIX [Page 9] Internet-Draft TinyIPFIX May 2017 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 per default. The timing intervals when to push data should be pre-defind before deployment. 2. 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. 3. If real-time reporting is not required, the application might benefit from accumulate several measurements into a single TinyIPFIX Message, causing delay but lowering traffic in the network. TinyIPFIX easily allows the accumulation of several measurements into a single TinyIPFIX Message (or a single packet). This accumulation can happen on the TinyIPFIX Smart Meter that accumulates several of its own measurements. Or it can happen within a multi-hop wireless network where one IPFIX Proxy accumulates several TinyIPFIX Messages into a single TinyIPFIX Message before forwarding them. 4. 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: if Message loss is acceptable for some reason). 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. Schmitt, et al. TinyIPFIX [Page 10] Internet-Draft TinyIPFIX May 2017 +------------------------+ +------------------------+ | 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.) queries its internal sensors to retrieve the sensor data to create its TinyIPFIX messages. It then encodes the results into a TinyIPFIX Message usinf 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 non-constrained 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. Schmitt, et al. TinyIPFIX [Page 11] Internet-Draft TinyIPFIX May 2017 +------------------------+ +------------------------+ | 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 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 be also 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 again 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. Schmitt, et al. TinyIPFIX [Page 12] Internet-Draft TinyIPFIX May 2017 +-------------------------+ +-------------------------+ | 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 IFPIX 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. Schmitt, et al. TinyIPFIX [Page 13] Internet-Draft TinyIPFIX May 2017 +----------------------------------------------------+ | TinyIPFIX Message Header | +----------------------------------------------------+ | TinyIPFIX Set | +----------------------------------------------------+ | TinyIPFIX Set | +----------------------------------------------------+ ... +----------------------------------------------------+ | TinyIPFIX Set | +----------------------------------------------------+ Figure 4: TinyIPFIX Message Format 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 Figure 7 to Figure 10. Schmitt, et al. TinyIPFIX [Page 14] Internet-Draft TinyIPFIX May 2017 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ext. SetID | +-+-+-+-+-+-+-+-+ Figure 6: Format of the TinyIPFIX Message Header including fixed and optional parts The fixed part has a length of three 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. 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 Schmitt, et al. TinyIPFIX [Page 15] Internet-Draft TinyIPFIX May 2017 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. 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 constraind networks (e.g., Wireless Sensor Networks Schmitt, et al. TinyIPFIX [Page 16] Internet-Draft TinyIPFIX May 2017 (WSN), Cyper-Physical-Systems (CPS)) and, 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 also the combination E1 = E2 = 1 is possible resulting in the maximum TinyIPFIX Message header shown in Figure 10 where 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 means Lookup extended SetID field, Shifting enabled. Value = 1 means SetID = 2 and message contains a Template definition. Value = 2 means SetID = 256 and message containts 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 means SetIDs are reserved for future extensions. Value = 15 means lookup extended SetID field, shifting enabled. Length The length field has a fixed length of 10 bits. 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 applications require several Observation Domains the Schmitt, et al. TinyIPFIX [Page 17] Internet-Draft TinyIPFIX May 2017 information can be included in the TinyIPFIX data message. The version field has been removed since the SetID lookup field provides room for future extensions. The specification of a 32 bit time stamp 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 concret observation time (e.g., timestamp) it is RECOMMENDED to include it as a separat field 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 either be 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 an two octet "Set ID" field and a two octet "Length" field. These two fields are compressed to one 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 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 is used by IPFIX [[RFC7011]]. TinyIPFIX Set ID number 3 MUST NOT be used. All values from 4 to 127 are reserved for future use. Values above 127 are used for TinyIPFIX Data Sets. Length Schmitt, et al. TinyIPFIX [Page 18] Internet-Draft TinyIPFIX May 2017 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 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. 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 Schmitt, et al. TinyIPFIX [Page 19] Internet-Draft TinyIPFIX May 2017 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. 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. Enterprise Number IANA Private Enterprise Number of the authority defining the Information Element identifier in this Template Record. Schmitt, et al. TinyIPFIX [Page 20] Internet-Draft TinyIPFIX May 2017 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 non-constrained network. This mediation changes the network and transport protocol from 6LoWPAN preferring UDP to IP/(SCTP|TCP|UDP) and is shown in Figure 16. Schmitt, et al. TinyIPFIX [Page 21] Internet-Draft TinyIPFIX May 2017 +-----------------------+ | 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. Schmitt, et al. TinyIPFIX [Page 22] Internet-Draft TinyIPFIX May 2017 +-----------------------+ | 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 Schmitt, et al. TinyIPFIX [Page 23] Internet-Draft TinyIPFIX May 2017 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 If the "Export Time" in the TinyIPFIX Message Header has a length of 4 octets, the value from the TinyIPFIX Message Header MUST be used for the IPFIX Message Header. The "Export Time" MUST be generated by the Mediator, because the "export Time" field was dropped as defined in Section 6.1. If the IPFIX Message is exported again, the "Export Time" field MUST contain the time in seconds since 0000 UTC Jan 1, 1970, at which the IPFIX Message leaves the Exporter. If the Message is passed to an IPFIX Collector for decoding directly, the "Export Time" field is the time in seconds since 0000 UTC Jan 1 1970 at which the TinyIPFIX Message has been received by the TinyIPFIX Exporter. 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 Schmitt, et al. TinyIPFIX [Page 24] Internet-Draft TinyIPFIX May 2017 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. 7.2. Translating the Set Headers Both fields in the TinyIPFIX Set Header have a size of one octet and need to be expanded: Set ID The field needs to be expanded from one octet to two 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 two octets. 8. Template Management As with IPFIX, TinyIPFIX templates 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, and template loss can occur. If a Schmitt, et al. TinyIPFIX [Page 25] Internet-Draft TinyIPFIX May 2017 Template is lost on its way to the Collector, all the 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 template directly after booting. 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 Device have a default setup when deployed and after booting they announce their TinyIPFIX Template directly to the networkand 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. As 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. It MUST therefore re-send its TinyIPFIX Templates periodically. A TinyIPFIX Template MUST be re- send after a fixed number of N TinyIPFIX Messages that contained TinyIPFIX Data Sets that referred to this TinyIPFIX Template. The number N MUST be configured by the application developer. This re- sending, especially 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. Schmitt, et al. TinyIPFIX [Page 26] Internet-Draft TinyIPFIX May 2017 10. IANA Considerations This document has no actions for IANA. 11. Acknowledgments Many thanks to Lothar Braun, Georg Carle, and Benoit Claise, who contributed significant work to earlier versions especially to the document entitled "Compressed IPFIX for Smart Meters in Constrained Networks" (draft-braun-core-compressed-ipfix), of this work. Many thanks to Thomas Kothmayr, Michael Meister, and Livio Sgier, who implemented TinyIPFIX for TinyOS 2.x, Contiki 2.7/3.0 (except the mediator) for different sensor platforms (IRIS, TelosB, and OpenMote). 12. References 12.1. 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, . [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, . [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, . [RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, September 2013, . [RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek, "Architecture for IP Flow Information Export", RFC 5470, DOI 10.17487/RFC5470, March 2009, . Schmitt, et al. TinyIPFIX [Page 27] Internet-Draft TinyIPFIX May 2017 [RFC5982] Kobayashi, A., Ed. and B. Claise, Ed., "IP Flow Information Export (IPFIX) Mediation: Problem Statement", RFC 5982, DOI 10.17487/RFC5982, August 2010, . [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, . 12.2. Informative References [Schmitt09] Schmitt, C. and G. Carle, "Applications for Wireless Sensor Networks", In Handbook of Research on P2P and Grid Systems for Service-Oriented Computing: Models, Methodologies and Applications, Antonopoulos N.; Exarchakos G.; Li M.; Liotta A. (Eds.), Information Science Publishing. , 2010. [Tolle05] Tolle, G., Polastre, J., Szewczyk, R., Turner, N., Tu, K., Buonadonna, P., Burgess, S., Gay, D., Hong, W., Dawnson, T., and D. Culler, "A macroscope in the redwoods", In the Proceedings of the 3rd ACM Conference on Embedded Networked Sensor Systems (Sensys 05), San Diego, ACM Press , November 2005. [Kim07] Kim, S., Pakzad, S., Culler, D., Demmel, J., Fenves, G., Glaser, S., and M. Turon, "Health Monitoring of Civil Infrastructure Using Wireless Sensor Networks", In the Proceedings of the 6th International Conference on Information Processing in Sensor Networks (IPSN 2007), Cambridge, MA, ACM Press, pp. 254-263 , April 2007. [SMPC04] Szewczyk, R., Mainwaring, A., Polastre, J., and D. Culler, "An analysis of a large scale habitat monitoring application", The Proceedings of the Second ACM Conference on Embedded Networked Sensor Systems (SenSys 04) , November 2004. [GreatDuck] Habitat Monitoring on Great Duck Island, , "http://www.greatduckisland.net", The Proceedings of the Second ACM Conference on Embedded Networked Sensor Systems (SenSys 04) , November 2004. Schmitt, et al. TinyIPFIX [Page 28] Internet-Draft TinyIPFIX May 2017 [Harvan08] Harvan, M. and J. Schoenwaelder, "TinyOS Motes on the Internet: IPv6 over 802.15.4 (6LoWPAN)", 2008. [Crossbow] Crossbow Technologies Inc., , "http://www.xbow.com", 2010. [Advantic] Advantic Sistemas y Servicios, , "https://www.advanticsys.com/", 2017. [kothmayr10] Kothmayr, T., "Data Collection in Wireless Sensor Networks for Autonomic Home Networking", Bachelor Thesis, Technical University of Munich, Germany , 2010. [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, DOI: 10.1016/ j.comcom.2014.05.012 , 2014. [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, M.Sheng, Y. Qin, L. Yao, and B. Benatallah (Eds.), Morgen Kaufmann (imprint of Elsevier), Chapter 8, pp. 229-247, ISBN: 978-0-12-809764-9 , 2017. Authors' Addresses Corinna Schmitt University of Zurich Department of Informatics Communication Systems Group Binzmuehlestrasse 14 Zurich 8050 Switzerland Email: schmitt@ifi.uzh.ch Schmitt, et al. TinyIPFIX [Page 29] Internet-Draft TinyIPFIX May 2017 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 Schmitt, et al. TinyIPFIX [Page 30]