IPFIX Working Group B. Claise Internet-Draft G. Dhandapani Intended Status: Standards Track S. Yates Expires: January 10, 2011 P. Aitken Cisco Systems, Inc. July 10, 2010 Export of Structured Data in IPFIX draft-ietf-ipfix-structured-data-02.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." 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Abstract This document specifies an extension to the IP Flow Information eXport (IPFIX) protocol specification in [RFC5101] and the IPFIX information model specified in [RFC5102] to support hierarchical structured data and lists (sequences) of Information Elements in data records. This extension allows definition of complex data structures such as variable-length lists and specification of hierarchical containment relationships between Templates. Conventions used in this document 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 RFC 2119 [RFC2119]. Expires January 10 2011 [Page 2] Internet-Draft July 2010 Table of Contents 1. Overview................................................... 7 1.1. IPFIX Documents Overview.............................. 7 1.2. Relationship between IPFIX and PSAMP.................. 7 2. Terminology................................................ 8 2.1. New Terminology....................................... 8 3. Introduction............................................... 8 3.1. The IPFIX Track....................................... 9 3.2. The IPFIX Limitations................................ 10 3.3. The Proposal......................................... 12 4. Linkage with the Information Model........................ 13 4.1. New Abstract Data Types.............................. 13 4.1.1. basicList....................................... 13 4.1.2. subTemplateList................................. 14 4.1.3. subTemplateMultiList............................ 14 4.2. New Data Type Semantic............................... 14 4.2.1. List............................................ 14 4.3. New Information Elements............................. 14 4.3.1. basicList....................................... 14 4.3.2. subTemplateList................................. 15 4.3.3. subTemplateMultiList............................ 15 4.4. New Structured Data Type Semantics................... 15 4.4.1. undefined....................................... 15 4.4.2. noneOf.......................................... 15 4.4.3. exactlyOneOf.................................... 16 4.4.4. oneOrMoreOf..................................... 17 4.4.5. allOf........................................... 17 4.4.6. ordered......................................... 18 4.5. Encoding of IPFIX Data Types......................... 18 4.5.1. basicList....................................... 18 4.5.2. subTemplateList................................. 21 4.5.3. subTemplateMultiList............................ 22 5. Structured Data Format.................................... 25 5.1. Length Encoding Considerations....................... 25 5.2. Recursive Structured Data............................ 26 5.3. Structured Data Information Elements Applicability in Options Template Sets..................................... 26 5.4. Usage Guidelines for Equivalent Data Representations. 27 5.5. Padding.............................................. 28 5.6. Semantic............................................. 28 6. Template Management....................................... 32 7. The Collecting Process's Side............................. 33 8. Structured Data Encoding Examples......................... 33 8.1. Encoding a Multicast Data Record with BasicList...... 34 8.2. Encoding a Load-balanced Data Record with a BasicList 36 Expires January 10 2011 [Page 3] Internet-Draft July 2010 8.3. Encoding subTemplateList............................. 37 8.4. Encoding subTemplateMultiList........................ 40 8.5. Encoding an Options Template Set using Structured Data44 9. Relationship with the Other IFPIX Documents............... 48 9.1. Relationship with Reducing Redundancy................ 48 9.1.1. Encoding Structured Data Element using Common Properties............................................. 49 9.1.2. Encoding Common Properties elements With Structured Data Element........................................... 49 9.2. Relationship with Guidelines for IPFIX Testing....... 51 9.3. Relationship with Bidirectional Flow Export.......... 52 9.4. Relationship with IPFIX Mediation Function........... 52 10. IANA Considerations...................................... 53 10.1. New Abstract Data Types............................. 53 10.1.1. basicList...................................... 53 10.1.2. subTemplateList................................ 53 10.1.3. subTemplateMultiList........................... 53 10.2. New Data Type Semantics............................. 54 10.2.1. list........................................... 54 10.3. New Information Elements............................ 54 10.3.1. basicList...................................... 54 10.3.2. subTemplateList................................ 54 10.3.3. subTemplateMultiList........................... 55 10.4. New Structured Data Semantics....................... 55 10.4.1. undefined...................................... 55 10.4.2. noneOf......................................... 55 10.4.3. exactlyOneOf................................... 56 10.4.4. oneOrMoreOf.................................... 56 10.4.5. allOf.......................................... 56 10.4.6. ordered........................................ 56 11. Security Considerations.................................. 56 12. References............................................... 56 12.1. Normative References................................ 56 12.2. Informative References.............................. 57 13. Acknowledgement.......................................... 58 14. Authors' Addresses....................................... 58 Appendix A. Additions to XML Specification of IPFIX Information Elements and Abstract Data Types................. 59 Appendix B. Example of Biflow Encoding using Structured Data Information Elements.................................... 64 Appendix C. Encoding IPS Alert using Structured Data Information Elements......................................... 67 Expires January 10 2011 [Page 4] Internet-Draft July 2010 Table of Figures Figure A: basicList Information Element Encoding.............. 19 Figure B: basicList Encoding with Enterprise Number........... 20 Figure C: Variable-Length basicList Information Element Encoding (Length < 255 octets) ..................................... 20 Figure D: Variable-Length basicList Information Element Encoding (Length 0 to 65535 octets) ................................ 20 Figure E: subTemplateList Encoding............................ 21 Figure F: Variable-Length subTemplateList Information Element Encoding (Length < 255 octets) ............................ 22 Figure G: Variable-Length subTemplateList Information Element Encoding (Length 0 to 65535 octets) ....................... 22 Figure H: subTemplateMultiList Encoding....................... 24 Figure I: Variable-Length subTemplateMultiList Information Element Encoding (Length < 255 octets) ............................ 25 Figure J: Variable-Length subTemplateMultiList Information Element Encoding (Length 0 to 65535 octets) ....................... 25 Figure K: Encoding basicList, Template Record................. 34 Figure L: Encoding basicList, Data Record, Semantic allOf..... 35 Figure M: Encoding basicList, Data Record with Variable-Length Elements, Semantic allOf .................................. 36 Figure N: Encoding basicList, Data Record, Semantic ExactlyOneOf37 Figure O: Encoding subTemplateList, Template for One-Way Delay Metrics ................................................... 38 Figure P: Encoding subTemplateList, Template Record........... 38 Figure Q: Encoding subTemplateList, Data Set.................. 39 Figure R: Encoding subTemplateMultiList, Template for Classification Attributes ................................. 42 Figure S: Encoding subTemplateMultiList, Template for Sampling Attributes ................................................ 43 Figure T: Encoding subTemplateMultiList, Template for Flow Record .......................................................... 43 Figure U: Encoding subTemplateMultiList, Data Set............. 44 Figure V: PSAMP SSRI to be encoded............................ 46 Figure W: Options Template Record for PSAMP SSRI using subTemplateMultiList ...................................... 46 Figure X: PSAMP SSRI, Template Record for interface........... 47 Figure Y: PSAMP SSRI, Template Record for linecard............ 47 Figure Z: PSAMP SSRI, Template Record for linecard and interface47 Figure ZA: Example of a PSAMP SSRI Data Record, Encoded using a subTemplateMultiList ...................................... 48 Figure ZB: Common and Specific Properties Exported Together [RFC5473] ................................................. 49 Figure ZC: Common and Specific Properties Exported Separately according to [RFC5473] .................................... 50 Expires January 10 2011 [Page 5] Internet-Draft July 2010 Figure ZD: Common and Specific Properties Exported with Structured Data Information Element .................................. 50 Figure B0: Using a subTemplateList to represent a Biflow...... 64 Figure B1: Template for the Biflow Fields..................... 65 Figure B2: Template for the Key Fields........................ 65 Figure B3: Biflow Data Set Encoded using Structured Data...... 66 Figure C0: Encoding IPS Alert, Template for Target............ 69 Figure C1: Encoding IPS Alert, Template for Attacker.......... 69 Figure C2: Encoding IPS Alert, Template for Participant....... 70 Figure C3: Encoding IPS Alert, Template for IPS Alert......... 70 Figure C4: Encoding IPS Alert, Data Set....................... 72 Expires January 10 2011 [Page 6] Internet-Draft July 2010 1. Overview 1.1. IPFIX Documents Overview The IPFIX Protocol [RFC5101] provides network administrators with access to IP Flow information. The architecture for the export of measured IP Flow information out of an IPFIX Exporting Process to a Collecting Process is defined in the IPFIX Architecture [RFC5470], per the requirements defined in RFC 3917 [RFC3917]. The IPFIX Architecture [RFC5470] specifies how IPFIX Data Records and Templates are carried via a congestion-aware transport protocol from IPFIX Exporting Processes to IPFIX Collecting Processes. IPFIX has a formal description of IPFIX Information Elements, their name, type and additional semantic information, as specified in the IPFIX information model [RFC5102]. In order to gain a level of confidence in the IPFIX implementation, probe the conformity and robustness, and allow interoperability, the Guidelines for IPFIX Testing [RFC5471] presents a list of tests for implementers of compliant Exporting Processes and Collecting Processes. The Bidirectional Flow Export [RFC5103] specifies a method for exporting bidirectional flow (biflow) information using the IP Flow Information Export (IPFIX) protocol, representing each Biflow using a single Flow Record. The "Reducing Redundancy in IP Flow Information Export (IPFIX) and Packet Sampling (PSAMP) Reports" [RFC5473] specifies a bandwidth saving method for exporting Flow or packet information, by separating information common to several Flow Records from information specific to an individual Flow Record: common Flow information is exported only once. 1.2. Relationship between IPFIX and PSAMP The specification in this document applies to the IPFIX protocol specifications [RFC5101]. All specifications from [RFC5101] apply unless specified otherwise in this document. Expires January 10 2011 [Page 7] Internet-Draft July 2010 The Packet Sampling (PSAMP) protocol [RFC5476] specifies the export of packet information from a PSAMP Exporting Process to a PSAMP Collecting Process. Like IPFIX, PSAMP has a formal description of its information elements, their name, type and additional semantic information. The PSAMP information model is defined in [RFC5477]. As the PSAMP protocol specifications [RFC5476] are based on the IPFIX protocol specifications, the specifications in this document are also valid for the PSAMP protocol. Indeed, the major difference between IPFIX and PSAMP is that the IPFIX protocol exports Flow Records while the PSAMP protocol exports Packet Reports. From a pure export point of view, IPFIX will not distinguish a Flow Record composed of several packets aggregated together, from a Flow Record composed of a single packet. So the PSAMP export can be seen as a special IPFIX Flow Record containing information about a single packet. 2. Terminology IPFIX-specific terminology used in this document is defined in Section 2 of the IPFIX protocol specification [RFC5101] and Section 3 of PSAMP protocol specification [RFC5476]. As in [RFC5101], these IPFIX-specific terms have the first letter of a word capitalized when used in this document. 2.1. New Terminology Structured Data Information Element One of the Information Elements supporting structured data, i.e., the basicList, subTemplateList, or subTemplateMultiList Information Elements specified in section 4.3. 3. Introduction While collecting the interface counters every five minutes has proven to be useful in the past, more and more granular information is required from network elements for a series of applications: performance assurance, capacity planning, security, billing, or simply monitoring. However, the amount of information has become so important that, when dealing with highly granular information such as Flow information, a push mechanism (as opposed Expires January 10 2011 [Page 8] Internet-Draft July 2010 to a pull mechanism, such as SNMP) is the only solution for routers whose primary function is to route packets. Indeed, polling short-live Flows via SNMP is not an option: high end routers can support hundreds of thousands of Flows simultaneously. Furthermore, in order to reduce the export bandwidth requirements, the network elements have to integrate mediation functions to aggregate the collected information, both in space and time. Typically, it would be beneficial if access routers could export Flow Records, composed of the counters before and after the WAN optimization mechanism, instead of exporting two Flow Records with identical tuple information. In terms of aggregation in time, let us imagine that, for performance assurance, the network management application must receive the performance metrics associated with a specific flow, every millisecond. Since the performance metrics will be constantly changing, there is a new dimension to the Flow definition: we are not dealing anymore with a single Flow lasting a few seconds or a few minutes, but with a multitude of one millisecond sub flows for which the performance metrics are reported. Which current protocol is suitable for these requirements: push mechanism, highly granular information, and huge number of similar records? IPFIX, as specified in RFC5101 would give part of the solution. 3.1. The IPFIX Track The IPFIX working group has specified a protocol to export IP Flow information [RFC5101]. This protocol is designed to export information about IP traffic Flows and related measurement data, where a Flow is defined by a set of key attributes (e.g. source and destination IP address, source and destination port, etc.). The IPFIX protocol specification [RFC5101] specifies that IP traffic measurements for Flows are exported using a TLV (type, length, value) format. The information is exported using a Template Record that is sent once to export the {type, length} pairs that define the data format for the Information Elements in a Flow. The Data Records specify values for each Flow. Based on the Requirements for IP Flow Information Export (IPFIX) [RFC3917], the IPFIX protocol has been optimized to export Flow related information. However, thanks to its Template mechanism, Expires January 10 2011 [Page 9] Internet-Draft July 2010 the IPFIX protocol can export any type of information, as long as the relevant Information Element is specified in the IPFIX information model [RFC5102], registered with IANA [IANA-IPFIX], or specified as an enterprise-specific Information Element. For each Information Element, the IPFIX information model [RFC5102] defines a numeric identifier, an abstract data type, an encoding mechanism for the data type, and any semantic constraints. Only basic, single-valued data types, e.g., numbers, strings, and network addresses are currently supported. 3.2. The IPFIX Limitations The IPFIX protocol specification [RFC5101] does not support the encoding of hierarchical structured data and arbitrary-length lists (sequences) of Information Elements as fields within a Template Record. As it is currently specified, a Data Record is a "flat" list of single-valued attributes. However, it is a common data modeling requirement to compose complex hierarchies of data types, with multiple occurrences, e.g., 0..* cardinality allowed for instances of each Information Element in the hierarchy. A typical example is the MPLS label stack entries model. An early NetFlow implementation used two Information Elements to represent the MPLS label stack entry: a "label stack entry position" followed by a "label stack value". However, several drawbacks were discovered. Firstly, the Information Elements in the Template Record had to be imposed so that the position would always precede the value. However, some encoding optimizations are based on the permutation of Information Element order. Secondly, a new semantic intelligence, not described in the information model, had to be hardcoded in the Collecting Process: the label value at the position "X" in the stack is contained in the "label stack value" Information Element following by a "label stack entry position" Information Element containing the value "X". Therefore, this model was abandoned. The selected solution in the IPFIX information model [RFC5102] is a long series of Information Elements: mplsTopLabelStackSection, mplsLabelStackSection2, mplsLabelStackSection3, mplsLabelStackSection4, mplsLabelStackSection5, mplsLabelStackSection6, mplsLabelStackSection7, mplsLabelStackSection8, mplsLabelStackSection9, mplsLabelStackSection10. While this model removes any ambiguity, it overloads the IPFIX information model with repetitive information. Furthermore, if mplsLabelStackSection11 is required, IANA [IANA-IPFIX] will not be able to assign the new Information Expires January 10 2011 [Page 10] Internet-Draft July 2010 Element next to the other ones in the registry, which might cause some confusion. Clearly a real structured data type composed of ("label stack entry position", "label stack value") pairs, potentially repeated multiple times in Flow Records would be more efficient from an information model point of view. Some more examples enter the same category: how to encode the list of output interfaces in a multicast Flow, how to encode the list of BGP Autonomous Systems (AS) in a BGP Flow, how to encode the BGP communities in a BGP Flow, etc? The one-way delay passive measurement, which is described in the IPFIX Applicability [RFC5472], is yet another example that would benefit from a structured data encoding. Assuming synchronized clocks, the Collector can deduce the one-way delay from the following two Information Elements, collected from two different Observation Points: - Packet arrival time: observationTimeMicroseconds [RFC5477] - Packet ID: digestHashValue [RFC5477] Ideally, the measurement at the second Observation Point should start a little bit later than at the first Observation Point, allowing the packets to arrive at the destination. In practice, this implies that many pairs of (observationTimeMicroseconds, digestHashValue) must be exported for each Observation Point, even if some optimization based on Hash-Based Filtering [RFC5475] is used. Instead of exporting repetitive information as part of every single Flow Record (for example, the 5 tuple), an optimized flow record composed of a structured data type such as the following would save a lot of bandwidth: 5 tuple { observationTimeMicroseconds 1, digestHashValue 1 } { observationTimeMicroseconds 2, digestHashValue 2 } { observationTimeMicroseconds 3, digestHashValue 3 } { ... , ... } As a last example, here is a more complex case of hierarchical structured data encoding. Consider the example scenario of an IPS (Intrusion Prevention System) alert data structure containing multiple participants, where each participant contains multiple attackers and multiple targets, with each target potentially composed of multiple applications, as depicted below: alert Expires January 10 2011 [Page 11] Internet-Draft July 2010 signatureId protocolIdentifier riskRating participant 1 attacker 1 sourceIPv4Address applicationId ... attacker N sourceIPv4Address applicationId target 1 destinationIPv4Address applicationId 1 ... applicationId n ... target N destinationIPv4Address applicationId 1 ... applicationId n participant 2 ... To export this information in IPFIX, the data would need to be flattened (thus losing the hierarchical relationships) and a new IPFIX Template created for each alert, according to the number of applicationID elements in each target, the number of targets and attackers in each participant, and the number of participants in each alert. Clearly each Template will be unique to each alert, and a large amount of CPU, memory and export bandwidth will be wasted creating, exporting, maintaining, and withdrawing the Templates. See Appendix C for a specific example related to this case study. 3.3. The Proposal This document specifies an IPFIX extension to support hierarchical structured data and variable-length lists by defining three new Information Elements and three corresponding new abstract data types called basicList, subTemplateList, and subTemplateMultiList. Expires January 10 2011 [Page 12] Internet-Draft July 2010 These are defined in Section 4.1. The three list Information Elements carry some semantic information so that the Collecting Process can understand the relationship between the different list elements. It is important to note that whereas the Information Elements and abstract data types defined in the IPFIX information model [RFC5102] represent single values, these new abstract data types are structural in nature and primarily contain references to other Information Elements and to Templates. By referencing other Information Elements and Templates from an Information Element's data content, it is possible to define complex data structures such as variable-length lists and to specify hierarchical containment relationships between Templates. Therefore, this document prefers the more generic "Data Record" term to the "Flow Record" term. This document specifies three new abstract data types, which are basic blocks to represent structured data. However, this document does not comment on all possible combinations of basicList, subTemplateList, and subTemplateMultiList. Neither, does it limit the possible combinations. 4. Linkage with the Information Model As in the IPFIX Protocol specification [RFC5101], the new Information Elements specified in Section 4.3. below MUST be sent in canonical format in network-byte order (also known as the big- endian byte ordering). 4.1. New Abstract Data Types This document specifies three new abstract data types, as described below. 4.1.1. basicList The type "basicList" represents a list of zero or more instances of any single Information Element, primarily used for single- valued data types. For example, a list of port numbers, a list of interface indexes, a list of AS in a BGP AS-PATH, etc. Expires January 10 2011 [Page 13] Internet-Draft July 2010 4.1.2. subTemplateList The type "subTemplateList" represents a list of zero or more instances of a structured data type, where the data type of each list element is the same and corresponds with a single Template Record. For example, a structured data type composed of multiple pairs of ("MPLS label stack entry position", "MPLS label stack value"), a structured data type composed of performance metrics, a structured data type composed of multiple pairs of IP address, etc. 4.1.3. subTemplateMultiList The type "subTemplateMultiList" represents a list of zero or more instances of a structured data type, where the data type of each list element can be different and corresponds with different template definitions. For example, a structured data type composed of multiple access-list entries, where entries can be composed of different criteria types. 4.2. New Data Type Semantic This document specifies a new data type semantic, as described below. 4.2.1. List A list represents an arbitrary-length sequence of zero or more structured data elements, either composed of regular Information Elements or composed of data conforming to a Template Record. 4.3. New Information Elements This document specifies three new Information Elements, as described below. 4.3.1. basicList A basicList specifies a generic Information Element with a basicList abstract data type as defined in Section 4.1.1. and list semantics as defined in Section 4.2.1. For example, a list of port numbers, a list of interface indexes, etc. Expires January 10 2011 [Page 14] Internet-Draft July 2010 EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this new Information Element identifier, the value XXX is used in all the examples and in the XML in Appendix A. 4.3.2. subTemplateList A subTemplateList specifies a generic Information Element with a subTemplateList abstract data type as defined in Section 4.1.2. and list semantics as defined in Section 4.2.1. EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this new Information Element identifier, the value YYY is used in all the examples. 4.3.3. subTemplateMultiList A subTemplateMultiList specifies a generic Information Element with a subTemplateMultiList abstract data type as defined in Section 4.1.3. and list semantics as defined in Section 4.2.1. EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this new Information Element identifier, the value ZZZ is used in all the examples. 4.4. New Structured Data Type Semantics Structured Data type semantics are provided in order to express the relationship among multiple list elements in a Structured Data Information Element. These Structured Data type semantics require a new IPFIX subregistry, as specified in the "IANA Considerations" section. The semantics are specified in the next following sections. 4.4.1. undefined The "undefined" Structured Data type semantic specifies that the semantic of list elements is not specified, and that, if a semantic exists, then it is up to the Collecting Process to draw its own conclusions. The "undefined" structured data type semantic is the default Structured Data type semantic. 4.4.2. noneOf The "noneOf" Structured Data type semantic specifies that none of the elements are actual properties of the Data Record. Expires January 10 2011 [Page 15] Internet-Draft July 2010 For example, a mediator might want to report to a Collector that a specific Flow is suspicious, but that it checked already that this Flow does not belong to the attack type 1, attack type 2, and attack type 3. So this Flow might need some further inspection. In such a case, the mediator would report the Flow Record with a basicList composed of (attack type 1, attack type 2, attack type 3) and the respective Structured Data type semantic of "noneOf". Another example is a router that monitors some specific BGP AS- PATHs and reports if a Flow belongs to any of them. If the router wants to export that a Flow does not belong to any of the monitored BGP AS-PATHs, the router reports a Data Record with a basicList composed of (BGP AS-PATH 1, BGP AS-PATH 2, BGP AS-PATH 3) and the respective Structured Data type semantic of "noneOf". 4.4.3. exactlyOneOf The "exactlyOneOf" Structured Data type semantic specifies that only a single element from the Structured Data is an actual property of the Data Record. This is equivalent to a logical XOR operation. For example, if a Flow record contains a basicList of outgoing interfaces with the "exactlyOneOf" semantic, then it implies that the reported Flow only egressed from a single interface, although the Flow Record lists all of the possible outgoing interfaces. This is a typical example of a per destination load-balanced Flow IPFIX encoding. For example, a mediator must report an aggregated observation point, composed of multiple Template Records: Template Record 1: exporterIPaddress This reports a specific exporter Template Record 2: exporterIPaddress, basicList of interfaces This reports a series of interfaces from an exporter Template Record 3: exporterIPaddress, line card This reports a specific line card from an exporter If these three Template Records are exported with a subTemplateMultiList with the semantic "exactlyOneOf", then it implies that the Flow Observation Point is reported with the values of either Template Record 1, Template Record 2, or Template Expires January 10 2011 [Page 16] Internet-Draft July 2010 Record 3 but not more than one Template Record. 4.4.4. oneOrMoreOf The "oneOrMoreOf" Structured Data type semantic specifies that one or more element(s) from the list in the Structured Data is/are actual propertie(s) of the Data Record. This is equivalent to a logical OR operation. For example, a mediator must report an aggregated Flow (for example aggregated from IP addresses to IP prefixes), with an aggregated observation point, composed of multiple Template Records: Template Record 1: exporterIPaddress This reports a specific exporter Template Record 2: exporterIPaddress, basicList of interfaces This reports a series of interfaces from an exporter Template Record 3: exporterIPaddress, line card This reports a specific line card from an exporter If these three Template Records are exported with a subTemplateMultiList with the semantic "oneOrMoreOf", then the aggregated Flow has been observed on at least one of the individual Observation Points reported with the values of a specific Template Record, and potentially on multiple Observation Points. 4.4.5. allOf The "allOf" structured data type semantic specifies that all of the list elements from the Structured Data are actual properties of the Data Record. For example, if a Record contains a basicList of outgoing interfaces with the "allOf" semantic, then the observed Flow is typically a multicast Flow where each packet in the Flow has been replicated to each outgoing interface in the basicList. Expires January 10 2011 [Page 17] Internet-Draft July 2010 4.4.6. ordered The "ordered" Structured Data type semantic specifies that elements from the list in the Structured Data are ordered. For example, an Exporter might want to export the AS10 AS20 AS30 AS40 BGP AS-PATH. In such a case, the Exporter would report a basicList composed of (AS10, AS20, AS30, AS40) and the respective Structured Data type semantic of "ordered". 4.5. Encoding of IPFIX Data Types The following sections define the encoding of the data types defined in Section 4.1. above. When the encoding of a Structured Data Information Element has a fixed length (because, for example, it contains the same number of fixed-length elements, or if the permutations of elements in the list always produces the same total length), the element length can be encoded in the corresponding Template Record. However, when representing variable-length data, hierarchical data, and repeated data with variable element counts, we RECOMMEND these are encoded as a Variable-Length Information Element as described in Section 7 of [RFC5101], with the length carried in one or three octets before the Structured Data Information Element encoding. 4.5.1. basicList The basicList Information Element defined in Section 4.3.1. represents a list of zero or more instances of an Information Element and is encoded as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Semantic |0| Field ID | Element... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ...Length | BasicList Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires January 10 2011 [Page 18] Internet-Draft July 2010 Figure A: basicList Information Element Encoding Semantic The Semantic indicates the semantic of the list elements, i.e., the relationship among the different Information Element values within this Structured Data. Field ID The Field ID is the Information Element identifier of the Information Element(s) contained in the list. Element Length The Element Length indicates the length of each list element specified by the Field ID, or contains the value 0xFFFF if the length is encoded as a variable-length Information Element at the start of the BasicList Content. The Element Length field is effectively part of a header, so even in the case of a zero-element list with no Enterprise Number, it MUST NOT be omitted. BasicList Content A Collection Process decodes list elements from the BasicList Content until no further data remains. A field count is not included but can be derived when the Information Element is decoded. Note that in the diagram above, the Field ID is shown with the Enterprise bit (most significant bit) set to 0. If instead the Enterprise bit is set to 1, a four-byte Enterprise Number MUST be encoded immediately after the Element Length as shown below. See the "Field Specifier Format" section in the IPFIX Protocol [RFC5101] for additional information. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Semantic |1| Field ID | Element... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires January 10 2011 [Page 19] Internet-Draft July 2010 | ...Length | Enterprise Number ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | BasicList Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure B: basicList Encoding with Enterprise Number Also note that, if a basicList has zero elements, the encoded data contains the Semantic, Field ID, the Element Length and the four- byte Enterprise Number (if present), while the BasicList Content is empty. If the basicList is encoded as a Variable-Length Information Element in less than 255 octets, it is encoded with the Length per Section 7 of [RFC5101] as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length (< 255)| basicList Content | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... continuing as needed | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure C: Variable-Length basicList Information Element Encoding (Length < 255 octets) If the basicList is encoded as a Variable-Length Information Element in 255 or more octets, it is encoded with the Length per Section 7 of [RFC5101] as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | Length (0 to 65535) | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | basicList Content | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure D: Variable-Length basicList Information Element Encoding (Length 0 to 65535 octets) Expires January 10 2011 [Page 20] Internet-Draft July 2010 4.5.2. subTemplateList The subTemplateList Information Element represents a list of zero or more instances of Template data. Because the Template Record referenced by a subTemplateList Information Element can itself contain other subTemplateList Information Elements, and because these Template Record references are part of the Information Elements content in the Data Record, it is possible to represent complex hierarchical data structures. The following diagram shows how a subTemplateList Information Element is encoded within a Data Record: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Semantic | Template ID | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SubTemplateList Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure E: subTemplateList Encoding Semantic The Semantic indicates the semantic of the list elements, i.e. the relationship among the different Data Records within this Structured Data. Template ID The Template ID is the ID of the template used to encode and decode the SubTemplateList Content. SubTemplateList Content The SubTemplateList Content consists of zero or more instances of Data Records corresponding to the Template ID. A Collecting Process decodes the Data Records until no further data remains. A record count is not included but can be derived when the subTemplateList is decoded. Encoding and decoding are performed recursively if the specified Template itself contains Structured Data Information Elements as described here. Expires January 10 2011 [Page 21] Internet-Draft July 2010 Note that, if a subTemplateList has zero elements, the encoded data contains only the Semantic and the Template ID, while the SubTemplateList Content is empty. If the subTemplateList is encoded as a Variable-Length Information Element in less than 255 octets, it is encoded with the Length per Section 7 of [RFC5101] as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length (< 255)| subTemplateList Content | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... continuing as needed | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure F: Variable-Length subTemplateList Information Element Encoding (Length < 255 octets) If the subTemplateList is encoded as a Variable-Length Information Element in 255 or more octets, it is encoded with the Length per Section 7 of [RFC5101] as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | Length (0 to 65535) | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... SubTemplateList Content | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure G: Variable-Length subTemplateList Information Element Encoding (Length 0 to 65535 octets) 4.5.3. subTemplateMultiList Whereas each top-level element in a subTemplateList Information Element corresponds with a single Template ID and therefore has the same data type, sometimes it is useful for a list to contain elements of more than one data type. To support this case, each top-level element in a subTemplateMultiList Information Element carries a Template ID, Length and zero or more Data Records corresponding to the Template ID. The following diagram shows how Expires January 10 2011 [Page 22] Internet-Draft July 2010 a subTemplateMultiList Information Element is encoded within a Data Record. Note that the subTemplateMultiList encoding is consistent with Set Header specified in [RFC5101], once the Semantic field has been decoded. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Semantic | Template ID X |Data Records...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... Length X | Data Record X.1 Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Data Record X.2 Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Data Record X.L Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Template ID Y |Data Records...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... Length Y | Data Record Y.1 Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Data Record Y.2 Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Data Record Y.M Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Template ID Z |Data Records...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... Length Z | Data Record Z.1 Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Data Record Z.2 Content ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | Data Record Z.N Content ... | Expires January 10 2011 [Page 23] Internet-Draft July 2010 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+ Figure H: subTemplateMultiList Encoding Semantic The Semantic indicates the top level semantic among Template Records, i.e. the relationship among the series of Data Records from the different Template Records within this Structured Data. Note: if a semantic is required to describe the relationship among the different Data Records corresponding to a single Template ID within the subTemplateMultiList, then an encoding based on a basicList of subTemplateLists should be used. Refer to Section 5.6 for more information. Template ID Unlike the subTemplateList Information Element, each list element contains a Template ID which specifies the encoding of the following Data Records. Data Records Length The total length of the Data Records encoding for the Template ID previously specified, including the 2 bytes for the Template ID and the 2 bytes for the Data Records Length field itself. Data Record X.M The Data Record X.M consists of the Mth Data Record of the Template Record X. A Collecting Process decodes the Data Records until no further data remains, according to the Data Records Length. A record count is not included but can be derived when the Element Content is decoded. Encoding and decoding are performed recursively if the specified Template itself contains Structured Data Information Elements as described here. Expires January 10 2011 [Page 24] Internet-Draft July 2010 In the exceptional case of zero instances in the subTemplateMultiList, no data is encoded and the Data Record Length is set to zero. If the subTemplateMultiList is encoded as a Variable-Length Information Element in less than 255 octets, it is encoded with the Length per Section 7 of [RFC5101] as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length (< 255)| subTemplateMultiList Information Element | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... continuing as needed | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure I: Variable-Length subTemplateMultiList Information Element Encoding (Length < 255 octets) If the subTemplateMultiList is encoded as a Variable-Length Information Element in 255 or more octets, it is encoded with the Length per Section 7 of [RFC5101] as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | Length (0 to 65535) | IE | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... continuing as needed | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure J: Variable-Length subTemplateMultiList Information Element Encoding (Length 0 to 65535 octets) 5. Structured Data Format 5.1. Length Encoding Considerations The new Structured Data Information Elements represent a list that potentially carries complex hierarchical and repeated data. In the normal case where the number and length of elements can vary from record to record, these Information Elements are encoded as variable-length Information Elements as described in Section 7 of [RFC5101]. Expires January 10 2011 [Page 25] Internet-Draft July 2010 Because of the complex and repeated nature of the data, it is potentially difficult for the Exporting Process to efficiently know in advance the exact encoding size. As a result, data may be recursively encoded starting at a fixed offset, with the final length only known and filled in afterwards. Therefore, the three-byte length encoding is RECOMMENDED for variable-length information elements in all Template Records containing a Structured Data Information Element, even if the encoded length can be less than 255 bytes, because the starting offset of the data is known in advance. An Exporting Process MUST take care when encoding such data to not exceed the maximum allowed length of an IPFIX Message, 65535 bytes, respecting the IPFIX specifications [RFC5101] that imposes: "The IPFIX Message Header 16-bit Length field limits the length of an IPFIX Message to 65535 octets, including the header". 5.2. Recursive Structured Data It is possible to define recursive relationships between IPFIX structured data instances, for example when representing a tree structure. The simplest case of this might be a basicList where each element is itself a basicList, or a subTemplateList where one of the fields of the referenced template is itself a subTemplateList referencing the same Template. When such a recursive relationship exists, variable-length encoding as described in Section 7 of [RFC5101] MUST be used. Also, the Exporting Process MUST take care when encoding recursively-defined structured data, not to exceed the maximum allowed length of an IPFIX Message (as noted in Length Encoding Considerations). 5.3. Structured Data Information Elements Applicability in Options Template Sets Structured Data Information Elements MAY be used in Options Template Sets. As an example, consider a mediation function that must aggregate Data Records from multiple Observation Point types: Router 1, (interface 1) Router 2, (line card A) Router 3, (line card B) Expires January 10 2011 [Page 26] Internet-Draft July 2010 Router 4, (line card C, interface 2) In order to encode the PSAMP Selection Sequence Report Interpretation [RFC5476], the mediation function must express this combination of Observation Points as a single new Observation Point. Recall from [RFC5476] that the PSAMP Selection Sequence Report Interpretation consists of the following fields: Scope: selectionSequenceId Non-Scope: one Information Element mapping the Observation Point selectorId (one or more) Without structured data, there is clearly no way to express the complex aggregated Observation Point as "one Information Element mapping the Observation Point". However, the desired result may be easily achieved using the structured data types. Refer to Section 8.5. for an encoding example related to this case study. Regarding the scope in the Options Template Record, the IPFIX specification [RFC5101] mentions that "The IPFIX protocol doesn't prevent the use of any Information Elements for scope". Therefore, a Structured Data Information Element MAY be used as scope in an Options Template Set. Extending the previous example, the mediation function could export a given name for this complex aggregated Observation Point: Scope: Aggregated Observation Point (Structured Data) Non-Scope: a new Information Element containing the name 5.4. Usage Guidelines for Equivalent Data Representations Because basicList, subTemplateList, and subTemplateMultiList are all lists, in several cases there is more than one way to represent what is effectively the same data structure. However, in some cases, one approach has an advantage over the other e.g. more compact, uses fewer resources, etc., and is therefore preferred over an alternate representation. A subTemplateList can represent the same simple list of single- value Information Elements as a basicList, if the Template referenced by the subTemplateList contains only one single-valued Information Element. Although the encoding is more compact than a basicList by two bytes, using a subTemplateList in this case requires a new Template per Information Element. The basicList Expires January 10 2011 [Page 27] Internet-Draft July 2010 requires no additional Template and is therefore RECOMMENDED in this case. Although a subTemplateMultiList with one Element can represent the contents of a subTemplateList, the subTemplateMultiList carries two additional bytes (Element Length). It is also potentially useful to a Collecting Process to know in advance that a subTemplateList directly indicates that list element types are consistent. The subTemplateList Information Element is therefore RECOMMENDED in this case. The Semantic in a subTemplateMultiList indicates the top level semantic among Template Records, i.e. the relationship among the series of Data Records from the different Template Records, within this Structured Data. If a semantic is required to describe the relationship among the different Data Records corresponding to a single Template ID within the subTemplateMultiList, then an encoding based on a basicList of subTemplateLists should be used. Note that the referenced Information Element(s) in the Structured Data Information Elements can be taken from the IPFIX information model [RFC5102], the PSAMP information model [RFC5477], or any of the Information Elements defined in the IANA IPFIX registry [IANA- IPFIX]. 5.5. Padding The Exporting Process MAY insert some padding octets in structured data field values in a Data Record by including the 'paddingOctets' Information Element as described in [RFC5101] Section 3.3.1. The paddingOctets Information Element can be included in a Template Record referenced by Structured Data Information Element for this purpose. 5.6. Semantic Semantic interpretations of received Data Records at or beyond the Collecting Process remain explicitly undefined, unless that data is transmitted using this extension with explicit Structured Data type semantic information. The Exporter SHOULD NOT check all semantically meaningless combinations before exporting the Data Record. Expires January 10 2011 [Page 28] Internet-Draft July 2010 Most forms of Structured Data type semantics are possible, without necessarily specifying new semantic values. For example, the export of the AS10 AS20 AS30 AS40 {AS50,AS60} BGP AS-PATH would be reported as a basicList of two elements, each element being a basicList of BGP AS, with the top level Structured Data type semantic of "ordered". The first element would contain a basicList composed of (AS10,AS20,AS30,AS40) and the respective Structured Data type semantic of "ordered", while the second element would contain a basicList composed of (AS50, AS60) and the respective Structured Data type semantic of "exactlyOneOf". A high level Data Record diagram would be represented as: (basicList, ordered, (basicList, ordered, AS10,AS20,AS30,AS40), (basicList, exactlyOneOf, AS50, AS60) ) Note that the subTemplateMultiList Structured Data type semantic provides the top level semantic among Template Records, i.e. the relationship among the series of Data Records from the different Template Records within this Structured Data, and not the relationships of the different Data Records corresponding to a single Template ID within the subTemplateMultiList. If this is required, semantic information needs to be exported for every Template ID, in other words a basicList of subTemplateLists should be used. The following case studies show the advantage of a basicList of subTemplateLists over a subTemplateMultiList. Case study 1: In this example, an Exporter monitoring security attacks must export a list of attackers and targets. For the sake of the example, consider attackers A1 or A2 may attack targets T1 and T2. The first case uses a subTemplateMultiList composed of two Template Records, one representing the attacker and one representing the target, each of them containing an IP address and a port. Attacker Template Record = (src IP address, src port) Expires January 10 2011 [Page 29] Internet-Draft July 2010 Target Template Record = (dst IP address, dst port) A high level Data Record diagram would be represented as: (subTemplateMultiList, allOf, (Attacker Template Record, A1, A2), (Target Template Record, T1, T2) ) The Collecting Process can only conclude that all of the attackers A1, A2 and the targets T1, T2 are present, without knowing the relationship amongst attackers and targets. The Exporting Process would have to explicitly call out the relationship amongst attackers and targets and the top level semantic offered by the subTemplateMultiList isn't sufficient. The only proper encoding for the previous semantic (i.e. attacker A1 or A2 may attack target T1 and T2) uses a basicList of subTemplateLists and is represented as follows: Attacker Template Record = (src IP address, src port) Target Template Record = (dst IP address, dst port) (basicList, allof, (subTemplateList, exactlyOneOf, attacker A1, A2) (subTemplateList, allOf, target T1, T2) ) Case study 2: In this example, an Exporter monitoring security attacks must export a list of attackers and targets. For the sake of the example, attackers A1 or A2 may attack targets T1, attacker A3 is attacking targets T2 and T3. The first case uses a subTemplateMultiList composed of two Template Records, one representing the attacker and one representing the target, each of them containing an IP address and a port. Expires January 10 2011 [Page 30] Internet-Draft July 2010 Attacker Template Record = (src IP address, src port) Target Template Record = (dst IP address, dst port) A high level Data Record diagram would be represented as: (subTemplateMultiList, allOf, (Attacker Template Record, A1, A2, A3), (Target Template Record, T1, T2, T3) ) The Collecting Process can only conclude that all of the attackers A1, A2, A3 and the targets T1, T2, T3 are present, without knowing the relationship amongst attackers and targets. The second case could use a Data Record definition composed of the following: (subTemplateMultiList, allOf, (Attacker Template Record, A1, A2), (Target Template Record, T1), (Attacker Template Record, A3), (Target Template Record, T2, T3) ) With the above representation, the Collecting Process can possibly deduce that some relationship exists among (A1, A2, T1) and (A3, T2, T3) but cannot understand what it is exactly. So, there is a need for the Exporting Process to explicitly define the relationship between the attackers and targets and the top level semantic of the subTemplateMultiList is not sufficient. The only proper encoding for the previous semantic (i.e. attacker A1 or A2 attack target T1, attacker A3 attacks targets T2 and T3) uses a basicList of subTemplateLists and is represented as follows: Attacker Template Record = (src IP address, src port) Expires January 10 2011 [Page 31] Internet-Draft July 2010 Target Template Record = (dst IP address, dst port) Participant P1: (basicList, allOf, (subTemplateList, exactlyOneOf, attacker A1, A2) (subTemplateList, undefined, target T1) ) Participant P2: (basicList, allOf, (subTemplateList, undefined, attacker A3, (subTemplateList, allOf, targets T2, T3) ) The security alert is represented as a subTemplateList of participants. Alert (subTemplateList, allOf, Participant P1, Participant P2) Note that, in the particular case of a single element in a Structured Data Information Element, the semantic field is actually not very useful since it specifies the relationship among multiple elements. Any choice of allOf, exactlyOneOr, or OneOrMoreOf would provide the same result semantically. Therefore, in case of a single element in a Structured Data Information Element, the default "undefined" semantic SHOULD be used. 6. Template Management This section introduces some more specific Template Management and Template Withdrawal Message-related specifications compared to the IPFIX protocol specification [RFC5101]. First of all, the Template ID uniqueness is unchanged compared to [RFC5101]; the uniqueness is local to the Transport Session and Expires January 10 2011 [Page 32] Internet-Draft July 2010 Observation Domain that generated the Template ID. In other words, the Set ID used to export the Template Record does not influence the Template ID uniqueness. While [RFC5101] mentions that: "If an Information Element is required more than once in a Template, the different occurrences of this Information Element SHOULD follow the logical order of their treatments by the Metering Process.", this rule MAY not be followed for the Structured Data Information Elements. As specified in [RFC5101], Templates that are not used anymore SHOULD be deleted. Before reusing a Template ID, the Template MUST be deleted. In order to delete an allocated Template, the Template is withdrawn through the use of a Template Withdrawal Message. 7. The Collecting Process's Side This section introduces some more specific specifications to the Collection Process compared to Section 9 in the IPFIX Protocol [RFC5101]. As described in [RFC5101], a Collecting Process MUST note the Information Element identifier of any Information Element that it does not understand and MAY discard that Information Element from the Flow Record. Therefore a Collection Process that does not support the extension specified in this document can ignore the Structured Data Information Elements in a Data Record, or it can ignore Data Records containing these new Structured Data Information Elements while continuing to process other Data Records. If the Structured Data contains the "undefined" Structured Data type semantic, the Collecting Process MAY attempt to draw its own conclusion in terms of the semantic contained in the Data Record, exactly as it would have done before the introduction of this specification. 8. Structured Data Encoding Examples The following examples are created solely for the purpose of illustrating how the extensions proposed in this document are encoded. Expires January 10 2011 [Page 33] Internet-Draft July 2010 8.1. Encoding a Multicast Data Record with BasicList Consider encoding a multicast Data Record containing the following data: --------------------------------------------------------------- Ingress If | Source IP | Destination IP | Egress Interfaces --------------------------------------------------------------- 9 192.0.2.201 233.252.0.1 1, 4, 8 --------------------------------------------------------------- Template Record for the multicast Flows, with the Template ID 256: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 24 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 256 | Field Count = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| ingressInterface = 10 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceIPv4Address = 8 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| DestinationIPv4Address = 12 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| basicList = XXX | Field Length = 0xFFFF | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure K: Encoding basicList, Template Record The list of outgoing interfaces is represented as a basicList with semantic allOf, and the Length of the list is chosen to be encoded in three bytes even though it may be less than 255 octets. The Data Set is represented as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 256 | Length = 36 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ingressInterface = 9 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceIPv4Address = 192.0.2.201 | Expires January 10 2011 [Page 34] Internet-Draft July 2010 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DestinationIPv4Address = 233.252.0.1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | List Length = 17 | semantic=allOf| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface FieldId = 14 |egressInterface Field Length=4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface value 1 = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface value 2 = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface value 3 = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure L: Encoding basicList, Data Record, Semantic allOf In the example above, the BasicList contains fixed-length elements. To illustrate how variable-length elements would be encoded, the same example is shown below with variable-length interface names in the BasicList instead: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 256 | Length = 44 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ingressInterface = 9 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceIPv4Address = 192.0.2.201 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DestinationIPv4Address = 233.252.0.1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | List Length = 25 | semantic=allOf| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| InterfaceName FieldId = 82 | InterfaceName Field Len=0xFFFF| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length = 5 | 'F' | 'E' | '0' | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | '/' | '0' | Length = 7 | 'F' | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 'E' | '1' | '0' | '/' | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | '1' | '0' | Length = 5 | 'F' | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 'E' | '2' | '/' | '2' | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires January 10 2011 [Page 35] Internet-Draft July 2010 Figure M: Encoding basicList, Data Record with Variable-Length Elements, Semantic allOf 8.2. Encoding a Load-balanced Data Record with a BasicList Consider encoding a load-balanced Data Record containing the following data: --------------------------------------------------------------- Ingress If | Source IP | Destination IP | Egress Interfaces --------------------------------------------------------------- 9 192.0.2.201 233.252.0.1 1, 4, 8 --------------------------------------------------------------- So the Data Record egressed from either interface 1, 4, or 8. The Data Set is represented as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 256 | Length = 36 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ingressInterface = 9 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceIPv4Address = 192.0.2.201 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DestinationIPv4Address = 233.252.0.1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | List Length = 17 |sem=exactlyOne | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface FieldId = 14 |egressInterface Field Length=4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface value 1 = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface value 2 = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | egressInterface value 3 = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires January 10 2011 [Page 36] Internet-Draft July 2010 Figure N: Encoding basicList, Data Record, Semantic ExactlyOneOf 8.3. Encoding subTemplateList As explained in Section 3.2. , multiple pairs of (observationTimeMicroseconds, digestHashValue) must be collected from two different Observation Points to passively compute the one-way delay across the network. This data can be exported with an optimized Data Record that consists of the following attributes: 5 tuple { observationTimeMicroseconds 1, digestHashValue 1 } { observationTimeMicroseconds 2, digestHashValue 2 } { observationTimeMicroseconds 3, digestHashValue 3 } { ... , ... } A subTemplateList is best suited for exporting the list of (observationTimeMicroseconds, digestHashValue). For illustration purposes, the number of elements in the list is 5; in practice, it could be more. ------------------------------------------------------------------ srcIP | dstIP | src | dst |proto| one-way delay | | Port | Port | | metrics ------------------------------------------------------------------ 192.0.2.1 192.0.2.105 1025 80 6 Time1, 0x0x91230613 Time2, 0x0x91230650 Time3, 0x0x91230725 Time4, 0x0x91230844 Time5, 0x0x91230978 ------------------------------------------------------------------ The following Template is defined for exporting the one-way delay metrics: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 16 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 257 | Field Count = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires January 10 2011 [Page 37] Internet-Draft July 2010 |0| observationTimeMicroSec=324 | Field Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| digestHashValue = 326 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure O: Encoding subTemplateList, Template for One-Way Delay Metrics The Template Record for the Optimized Data Record is as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 32 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 258 | Field Count = 6 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceIPv4Address = 8 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationIPv4Address = 12 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceTransportPort = 7 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationTransportPort= 11| Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| protocolIdentifier = 4 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| subTemplateList = YYY | Field Length = 0xFFFF | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure P: Encoding subTemplateList, Template Record The list of (observationTimeMicroseconds, digestHashValue) is exported as a subTemplateList with semantic allOf. The Length of the subTemplatelist is chosen to be encoded in three bytes even though it may be less than 255 octets. The Data Record is represented as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 258 | Length = 83 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceIPv4Address = 192.0.2.1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires January 10 2011 [Page 38] Internet-Draft July 2010 | destinationIPV4Address = 192.0.2.105 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceTransportPort = 1025 | destinationTransportPort = 80 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Protocol = 6 | 255 | one-way metrics list len = 63 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | semantic=allOf| TemplateID = 257 | TimeValue1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 2-5 of TimeValue1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 6-8 of TimeValue1 |digestHashVal1=| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 0x0x91230613 | TimeValue2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 2-5 of TimeValue2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 6-8 of TimeValue2 |digestHashVal2=| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 0x0x91230650 | TimeValue3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 2-5 of TimeValue3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 6-8 of TimeValue3 |digestHashVal3=| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 0x0x91230725 | TimeValue4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 2-5 of TimeValue4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 6-8 of TimeValue4 |digestHashVal4=| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 0x0x91230844 | TimeValue5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 2-5 of TimeValue5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... octets 6-8 of TimeValue5 |digestHashVal5=| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 0x0x91230978 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure Q: Encoding subTemplateList, Data Set Expires January 10 2011 [Page 39] Internet-Draft July 2010 8.4. Encoding subTemplateMultiList As explained in Section 4.4.3., a subTemplateMultiList is used to export a list of mixed-type content where each top level element corresponds to a different Template Record. To illustrate this, consider the Data Record with the following attributes: 5 tuple (Flow Keys), octetCount, packetCount attributes for classification selectorId, selectorAlgorithm attributes for sampling selectorId, selectorAlgorithm, samplingPacketInterval, samplingPacketSpace This example demonstrates that the Selector Report Interpretation [RFC5476] can be encoded with the subTemplateMultiList. More specifically, the example describes Property Match Filtering Selector Report Interpretation [RFC5476] used for classification purposes, and the Systemic Count-Based Sampling as described in Section 6.5.2.1 of [RFC5476]. Some traffic will be filtered according to match properties configured, some will be sampled, some will be filtered and sampled, and some will not be filtered or be sampled. A subTemplateMultiList is best suited for exporting this variable data. A Template is defined for classification attributes and another Template is defined for sampling attributes. A Data Record can contain data corresponding to either of the Templates, both of them, or neither of them. Consider the example below where the following Data Record contains both classification and sampling attributes. Key attributes of the Data Record: ------------------------------------------------------------------ srcIP | dstIP | src | dst | proto | octetCount | packet | | Port | Port | | | Count ------------------------------------------------------------------ 192.0.2.1 192.0.2.105 1025 80 6 108000 120 Expires January 10 2011 [Page 40] Internet-Draft July 2010 ------------------------------------------------------------------ Classification attributes: ------------------------------------------- selectorId | selectorAlgorithm ------------------------------------------- 100 5 (Property Match Filtering) ------------------------------------------- Sampling attributes: For Systemic Count-Based Sampling as defined in Section 6.5.2.1 of [RFC5476] the required algorithm-specific Information Elements are: samplingPacketInterval: number of packets selected in a row samplingPacketSpace: number of packets between selections Example of a simple 1 out-of 100 systematic count-based Selector definition, where the samplingPacketInterval is 1 and the samplingPacketSpace is 99. -------------------------------------------------------------- selectorId | selectorAlgorithm | sampling | sampling | | Packet | Packet | | Interval | Space -------------------------------------------------------------- 15 1 (Count-Based Sampling) 1 99 -------------------------------------------------------------- To represent the Data Record, the following Template Records are defined: Template for classification attributes: 259 Template for sampling attributes: 260 Template for Flow Record: 261 Flow record (261) | (sourceIPv4Address) | (destinationIPv4Address) | (sourceTransportPort) | (destinationTransportPort) | (protocolIdentifier) Expires January 10 2011 [Page 41] Internet-Draft July 2010 | (octetTotalCount) | (packetTotalCount) | +------ classification attributes (259) | (selectorId) | (selectorAlgorithm) | +------ sampling attributes (260) | (selectorId) | (selectorAlgorithm) | (samplingPacketInterval) | (samplingPacketSpace) The following Template Record is defined for classification attributes: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 259 | Field Count = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| selectorId = 302 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| selectorAlgorithm = 304 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure R: Encoding subTemplateMultiList, Template for Classification Attributes The Template for sampling attributes is defined as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 24 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 260 | Field Count = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| selectorId = 302 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| selectorAlgorithm = 304 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| samplingPacketInteval = 305 | Field Length = 1 | Expires January 10 2011 [Page 42] Internet-Draft July 2010 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| samplingPacketSpace = 306 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure S: Encoding subTemplateMultiList, Template for Sampling Attributes Note that while selectorId is defined as unsigned64, it is compressed down to 4 octet here as allowed by Reduced Size Encoding in Section 6.2 of the IPFIX protocol specifications [RFC5101]. Note that while selectorAlgorithm is defined as unsigned16, and samplingPacketInterval and samplingPacketSpace are defined as unsigned32, they are compressed down to 1 octet here as allowed by Reduced Size Encoding in Section 6.2 of the IPFIX protocol specifications [RFC5101]. Template for the Flow Record is defined as shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 40 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 261 | Field Count = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceIPv4Address = 8 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationIPv4Address = 12 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceTransportPort = 7 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationTransportPort=11 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| protocolIdentifier = 4 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| octetTotalCount = 85 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| packetTotalCount = 86 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| subTemplateMultiList = ZZZ | Field Length = 0XFFFF | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure T: Encoding subTemplateMultiList, Template for Flow Record Expires January 10 2011 [Page 43] Internet-Draft July 2010 A subTemplateMultiList with semantic allOf is used to export the classification and sampling attributes. The Length of the subTemplateMultilist is chosen to be encoded in three bytes even though it may be less than 255 octets. The Data Record is encoded as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 261 | Length = 49 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceIPv4Address = 192.0.2.1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | destinationIPv4Address = 192.0.2.105 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceTransportPort = 1025 | destinationTransportPort = 80 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | protocol = 6 | octetTotalCount = 108000 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | packetTotalCount = 120 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | 255 | Attributes List Length = 21 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |semantic=allOf | Classif. Template ID = 259 | Classif. Attr | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ...Length = 9 | selectorId = ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 100 |selectorAlg = 5| Sampling Template ID = 260 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sampling Attributes Length=11 | selectorId = ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 15 |selectorAlg = 1| Interval = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Space = 99 | +-+-+-+-+-+-+-+-+ Figure U: Encoding subTemplateMultiList, Data Set 8.5. Encoding an Options Template Set using Structured Data As described in Section 5.3. , consider a mediation function that must aggregate Data Records from multiple different Observation Points. Expires January 10 2011 [Page 44] Internet-Draft July 2010 Say Observation Point 1 consists of one or more interfaces, Observation Points 2 and 3 consist of one or more line cards, and Observation Point 4 consists of one or more interfaces and one or more line cards. Without structured data, a template would have to be defined for every possible combination to interpret the data corresponding to each of the Observation Points. However, with structured data, a basicList can be used to encode the list of interfaces and another basicList can be used to encode the list of line cards. For the sake of simplicity, each Observation Point shown below has an or or . This can very well be extended to include a list of interfaces and a list of linecards using basicLists as explained above. Observation Point 1: Router 1, (interface 1) Observation Point 2: Router 2, (line card A) Observation Point 3: Router 3, (line card B) Observation Point 4: Router 4, (line card C, interface 2) The mediation function wishes to express this as a single Observation Point, in order to encode the PSAMP Selection Sequence Report Interpretation (SSRI). Recall from [RFC5476] that the PSAMP Selection Sequence Report Interpretation consists of the following fields: Scope: selectionSequenceId Non-Scope: one Information Element mapping the Observation Point selectorId (one or more) For example, the Observation Point detailed above may be encoded in a PSAMP Selection Sequence Report Interpretation as shown below: Selection Sequence 7 (Filter->Sampling): observation point: subTemplateMultiList. Router 1, (interface 1) Router 2, (line card A) Router 3, (line card B) Router 4, (line card C, interface 2) selectorId: 5 (Filter, match IPV4SourceAddress 192.0.2.1) selectorId: 10 (Sampler, Random 1 out-of ten) The following Templates are defined to represent the PSAMP SSRI: Template for representing PSAMP SSRI: 262 Template for representing interface: 263 Expires January 10 2011 [Page 45] Internet-Draft July 2010 Template for representing linecard: 264 Template for representing linecard and interface: 265 PSAMP SSRI (262) | (SelectionSequenceId) | +--- Observation Point 1 (263) | (Interface Id) | +--- Observation Point 2 and 3 (264) | (line card) | +--- Observation Point 4 (265) | (line card) | (Interface Id) | | (selectorId 1) | (selectorId 2) Figure V: PSAMP SSRI to be encoded 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 3 | Length = 26 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 262 | Field Count = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Scope Field Count = 1 |0| selectionSequenceId = 301 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Scope 1 Length = 4 |0| subTemplateMultiList = ZZZ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 0xFFFF |0| selectorId = 302 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 |0| selectorId = 302 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure W: Options Template Record for PSAMP SSRI using subTemplateMultiList A subTemplateMultiList with semantic allOf is used to encode the list of Observation Points. Expires January 10 2011 [Page 46] Internet-Draft July 2010 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 12 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 263 | Field Count = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| ingressInterface = 10 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure X: PSAMP SSRI, Template Record for interface 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 12 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 264 | Field Count = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| lineCardId = 141 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure Y: PSAMP SSRI, Template Record for linecard 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 265 | Field Count = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| lineCardId = 141 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| ingressInterface = 10 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure Z: PSAMP SSRI, Template Record for linecard and interface The PSAMP SSRI Data Set is represented as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 262 | Length = 52 | Expires January 10 2011 [Page 47] Internet-Draft July 2010 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | selectionSequenceId = 7 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | Observation Point List Len=33 |semantic=allOf | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP1 Template ID = 263 | OP1 Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP1 ingressInterface = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP2&3 Template ID = 264 | OP2&3 Length = 12 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP2 lineCardId = A | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP3 lineCardId = B | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP4 Template ID = 265 | OP4 Length = 12 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP4 lineCardId = C | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP4 ingressInterface = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | selectorId = 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | selectorId = 10 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure ZA: Example of a PSAMP SSRI Data Record, Encoded using a subTemplateMultiList Note that the Data Record above contains multiple instances of Template 264 to represent Observation Point 2 (line card A) and Observation Point 3 (line card B). Instead, if a single Observation Point had both line card A and line card B, a basicList would be used to represent the list of line cards. 9. Relationship with the Other IFPIX Documents 9.1. Relationship with Reducing Redundancy "Reducing Redundancy in IP Flow Information Export (IPFIX) and Packet Sampling (PSAMP) Reports" [RFC5473] describes a bandwidth saving method for exporting Flow or packet information using the IP Flow Information eXport (IPFIX) protocol. Expires January 10 2011 [Page 48] Internet-Draft July 2010 It defines the commonPropertiesID Information Element for exporting Common Properties. 9.1.1. Encoding Structured Data Element using Common Properties. When Structured Data Information Elements contain repeated elements, these elements may be replaced with a commonPropertiesID Information Element as specified in [RFC5473]. The replaced elements may include the basicList, subTemplateList and subTemplateMultiList Information Elements. This technique might help reducing the bandwidth requirements for the export. However, a detailed analysis of the gain has not been done; refer to Section 8.3 of [RFC5473] for further considerations. 9.1.2. Encoding Common Properties elements With Structured Data Element. Structured Data Information Element MAY be used to define a list of commonPropertiesID, as a replacement for the specifications in [RFC5473]. Indeed, the example in figures 1 and 2 of [RFC5473] can be encoded with the specifications in this document. +----------------+-------------+---------------------------+ | sourceAddressA | sourcePortA | | +----------------+-------------+---------------------------+ | sourceAddressA | sourcePortA | | +----------------+-------------+---------------------------+ | sourceAddressA | sourcePortA | | +----------------+-------------+---------------------------+ | sourceAddressA | sourcePortA | | +----------------+-------------+---------------------------+ | ... | ... | ... | +----------------+-------------+---------------------------+ Figure ZB: Common and Specific Properties Exported Together [RFC5473] Expires January 10 2011 [Page 49] Internet-Draft July 2010 +------------------------+-----------------+-------------+ | index for properties A | sourceAddressA | sourcePortA | +------------------------+-----------------+-------------+ | ... | ... | ... | +------------------------+-----------------+-------------+ +------------------------+---------------------------+ | index for properties A | | +------------------------+---------------------------+ | index for properties A | | +------------------------+---------------------------+ | index for properties A | | +------------------------+---------------------------+ | index for properties A | | +------------------------+---------------------------+ Figure ZC: Common and Specific Properties Exported Separately according to [RFC5473] +----------------+-------------+---------------------------+ | sourceAddressA | sourcePortA | | +----------------+-------------+---------------------------+ | | +---------------------------+ | | +---------------------------+ | | +---------------------------+ | ... | +---------------------------+ Figure ZD: Common and Specific Properties Exported with Structured Data Information Element The example in figure ZC could be encoded with a basicList if the represents a single Information Element, with a subTemplateList if the represents a Template Record, or with a subTemplateMultiList if the is composed of different Template Records. Using Structured Data Information Elements as a replacement for the techniques specified in "Reducing Redundancy in IP Flow Information Export (IPFIX) and Packet Sampling (PSAMP) Reports" [RFC5473] offers the advantage that a single Template Record is defined. Hence the Collectors job is simplified in terms of Expires January 10 2011 [Page 50] Internet-Draft July 2010 Template management and combining Template/Options Template Records. However, it must be noted that using Structured Data Information Elements as a replacement for the techniques specified in "Reducing Redundancy in IP Flow Information Export (IPFIX) and Packet Sampling (PSAMP) Reports" only applies to simplified cases. For example, the "Multiple Data Reduction" (Section 7.1 [RFC5473]) might be too complex to encode with Structured Data Information Elements. 9.2. Relationship with Guidelines for IPFIX Testing [RFC5471] presents a list of tests for implementers of IP Flow Information eXport (IPFIX) compliant Exporting Processes and Collecting Processes. Although [RFC5471] doesn't define any structured data element specific tests, the Structured Data Information Elements can be used in many of the [RFC5471] tests. The [RFC5471] series of test could be useful because the document specifies that every Information Element type should be tested. However, not all cases from this document are tested in [RFC5471]. The following sections are especially noteworthy: . 3.2.1. Transmission of Template with fixed size Information Elements - each data type should be used in at least one test. The new data types specified in Section 4.1. should be included in this test. . 3.2.2. Transmission of Template with variable length Information Elements - this test should be expanded to include Data Records containing variable length basicList, subTemplateList, and subTemplateMultiList Information Elements. . 3.3.1. Enterprise-specific Information Elements Expires January 10 2011 [Page 51] Internet-Draft July 2010 - this test should include the export of basicList, subTemplateList, and subTemplateMultiList Information Elements containing Enterprise-specific Information Elements. e.g., see the example in figure B. . 3.3.3. Multiple instances of the same Information Element in one Template - this test should verify that multiple instances of the basicList, subTemplateList and subTemplateMultiList Information Elements are accepted. . 3.5 Stress/Load tests - since the structured data types defined here allow modeling of complex data structures, they may be useful for stress testing both Exporting Processes and Collecting Processes. 9.3. Relationship with Bidirectional Flow Export [RFC5103] describes a method for exporting bidirectional flow information, and defines the biflowDirection Information Element for this purpose. [RFC5103] Biflows may be encoded in a subTemplateList or subTemplateMultiList. The basicList requires recurrence of a single element, so is not suitable for Biflows. Encoding Biflows with subTemplateList or subTemplateMultiList provides a more logical division of the information in both directions, although this encoding incurs a small additional bandwidth penalty. An example of Biflow encoding using Structure Data Information Elements and comparison with the [RFC5103] Biflow encoding is shown in Appendix B. 9.4. Relationship with IPFIX Mediation Function The Structured Data Information Elements would be beneficial for the export of aggregated Data Records in mediation function, as was demonstrated with the example of the aggregated Observation Point in Section 5.3. Expires January 10 2011 [Page 52] Internet-Draft July 2010 10. IANA Considerations This document specifies several new IPFIX abstract data types, a new IPFIX Data Type Semantic, and several new Information Elements. These require the creation of two new IPFIX registries and updating the existing IPFIX Information Element registry as detailed below. 10.1. New Abstract Data Types Section 4.1. of this document specifies several new IPFIX abstract data types. Per Section 6 of the IPFIX information model [RFC5102], new abstract data types can be added to the IPFIX information model. This requires creation of a new IPFIX "abstract data types" registry at http://www.iana.org/assignments/ipfix. This registry should include all the abstract data types from Section 3.1 of [RFC5102]. Abstract data types to be added to the IPFIX "abstract data types" registry are listed below. 10.1.1. basicList The type "basicList" represents a list of any Information Element used for single-valued data types. 10.1.2. subTemplateList The type "subTemplateList" represents a list of a structured data type, where the data type of each list element is the same and corresponds with a single Template Record. 10.1.3. subTemplateMultiList The type "subTemplateMultiList" represents a list of structured data types, where the data types of the list elements can be different and correspond with different template definitions. Expires January 10 2011 [Page 53] Internet-Draft July 2010 10.2. New Data Type Semantics Section 4.2. of this document specifies a new IPFIX Data Type Semantic. Per Section 3.2 of the IPFIX information model [RFC5102], new data type semantics can be added to the IPFIX information model. Therefore, the IANA IPFIX informationElementSemantics registry [IANA-IPFIX], which contains all the data type semantics from Section 3.2 of [RFC5102], must be augmented with the "list" value below. 10.2.1. list A list is a structured data type, being composed of a sequence of elements e.g. Information Element, Template Record, etc. 10.3. New Information Elements Section 4.3. of this document specifies several new Information Elements which are to be created in the IPFIX Information Element registry [IANA-IPFIX]. New Information Elements to be added to the IPFIX Information Element registry are listed below. EDITOR'S NOTE: the XML specification in Appendix A must be updated with the elementID values allocated below. 10.3.1. basicList Name: basicList Description: Specifies a generic Information Element with a basicList abstract data type. For example, a list of port numbers, a list of interface indexes, etc. Abstract Data Type: basicList Data Type Semantics: list ElementId: XXX (to be specified by IANA) Status: current 10.3.2. subTemplateList Name: subTemplateList Description: Specifies a generic Information Element with a subTemplateList abstract data type. Expires January 10 2011 [Page 54] Internet-Draft July 2010 Abstract Data Type: subTemplateList Data Type Semantics: list ElementId: YYY (to be specified by IANA) Status: current 10.3.3. subTemplateMultiList Name: subTemplateMultiList Description: Specifies a generic Information Element with a subTemplateMultiList abstract data type. Abstract Data Type: subTemplateMultiList Data Type Semantics: list ElementId: ZZZ (to be specified by IANA) Status: current 10.4. New Structured Data Semantics Section 4.4. of this document specifies a series of new IPFIX structured data type semantics, which is expressed as an 8-bit value. This requires the creation of a new IPFIX "structured data types semantics" IPFIX subregistry [IANA-IPFIX]. Entries may be added to this subregistry subject to a Standards Action [RFC5226]. Initially, this registry should include all the structured data type semantics listed below. 10.4.1. undefined A list is a structured data type, being composed of a sequence of elements e.g. Information Element, Template Record, etc. Value: 0xFF Description: undefined Reference: 10.4.2. noneOf A list is a structured data type, being composed of a sequence of elements e.g. Information Element, Template Record, etc. Value: 0x00 Description: noneOf Reference: Expires January 10 2011 [Page 55] Internet-Draft July 2010 10.4.3. exactlyOneOf A list is a structured data type, being composed of a sequence of elements e.g. Information Element, Template Record, etc. Value: 0x01 Description: exactlyOneOf Reference: 10.4.4. oneOrMoreOf A list is a structured data type, being composed of a sequence of elements e.g. Information Element, Template Record, etc. Value: 0x02 Description: oneOrMoreOf Reference: 10.4.5. allOf A list is a structured data type, being composed of a sequence of elements e.g. Information Element, Template Record, etc. Value: 0x03 Description: allOf Reference: 10.4.6. ordered A list is a structured data type, being composed of a sequence of elements e.g. Information Element, Template Record, etc. Value: 0x04 Description: ordered Reference: 11. Security Considerations The same security considerations as for the IPFIX Protocol [RFC5101] apply. 12. References 12.1. Normative References [RFC2119] S. Bradner, Key words for use in RFCs to Indicate Requirement Levels, BCP 14, RFC 2119, March 1997. Expires January 10 2011 [Page 56] Internet-Draft July 2010 [RFC5101] Claise, B., Ed., "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information", RFC 5101, January 2008. [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J. Meyer, "Information Model for IP Flow Information Export", RFC 5102, January 2008. [RFC5226] T. Narten, T., Alverstrand, H. , "Guidelines for Writing an IANA Considerations Section in RFCs", RFC5226, May 2008. 12.2. Informative References [RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander, Requirements for IP Flow Information Export, RFC 3917, October 2004. [RFC5103] Trammell, B., and E. Boschi, "Bidirectional Flow Export Using IP Flow Information Export (IPFIX)", RFC 5103, January 2008. [RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek, "Architecture for IP Flow Information Export", RFC 5470, March 2009. [RFC5471] Schmoll, C., Aitken, P., and B. Claise, "Guidelines for IP Flow Information Export (IPFIX) Testing", RFC 5471, March 2009. [RFC5472] Zseby, T., Boschi, E., Brownlee, N., and B. Claise, "IP Flow Information Export (IPFIX) Applicability", RFC 5472, March 2009. [RFC5473] Boschi, E., Mark, L., and B. Claise, "Reducing Redundancy in IP Flow Information Export (IPFIX) and Packet Sampling (PSAMP) Reports", RFC 5473, March 2009. [RFC5475] Zseby, T., Molina, M., Duffield, N., Niccolini, S., and F. Raspall, "Sampling and Filtering Techniques for IP Packet Selection", RFC 5475, March 2009. [RFC5476] Claise, B., Ed., "Packet Sampling (PSAMP) Protocol Specifications", RFC 5476, March 2009. Expires January 10 2011 [Page 57] Internet-Draft July 2010 [RFC5477] Dietz, T., Claise, B., Aitken, P., Dressler, F., and G. Carle, "Information Model for Packet Sampling Exports", RFC 5477, March 2009. [IANA-IPFIX] http://www.iana.org/assignments/ipfix/ipfix.xhtml 13. Acknowledgement The authors would like to thank Zhipu Jin, Nagaraj Varadharajan, Brian Trammel, and Atsushi Kobayashi for their feedback. 14. Authors' Addresses Benoit Claise Cisco Systems Inc. De Kleetlaan 6a b1 Diegem 1813 Belgium Phone: +32 2 704 5622 EMail: bclaise@cisco.com Gowri Dhandapani Cisco Systems Inc. 13615 Dulles Technology Drive Herndon, Virigina 20171 United States Phone: +1 408 853 0480 EMail: gowri@cisco.com Stan Yates Cisco Systems Inc. 7100-8 Kit Creek Road PO Box 14987 Research Triangle Park North Carolina, 27709-4987 United States Phone: +1 919 392 8044 EMail: syates@cisco.com Expires January 10 2011 [Page 58] Internet-Draft July 2010 Paul Aitken Cisco Systems (Scotland) Ltd. 96 Commercial Quay Commercial Street Edinburgh, EH6 6LX, United Kingdom Phone: +44 131 561 3616 EMail: paitken@cisco.com Appendix A. Additions to XML Specification of IPFIX Information Elements and Abstract Data Types This appendix contains additions to the machine-readable description of the IPFIX information model coded in XML in Appendix A and Appendix B in [RFC5102]. Note that this appendix is of informational nature, while the text in section 4. (generated from this appendix) is normative. The following field definitions are appended to the IPFIX information model in Appendix A of [RFC5102]. Represents a list of zero or more instances of any single Information Element, primarily used for single-valued data types. For example, a list of port numbers, list of interface indexes, list of AS in a BGP AS-PATH, etc. Expires January 10 2011 [Page 59] Internet-Draft July 2010 Represents a list of zero or more instances of a structured data type, where the data type of each list element is the same and corresponds with a single Template Record. For example, a structured data type composed of multiple pairs of ("MPLS label stack entry position", "MPLS label stack value"), a structured data type composed of performance metrics, a structured data type composed of multiple pairs of IP address, etc. Represents a list of zero or more instances of structured data types, where the data type of each list element can be different and corresponds with different template definitions. For example, a structured data type composed of multiple access-list entries, where entries can be composed of different criteria types. The following structured data type semantic definitions are appended to the the IPFIX information model in Appendix A of [RFC5102]. Specifies that the semantic of list elements is not specified, and that, if a semantic exists, then it is up to the Collecting Process to draw its own conclusions. The "undefined" structured data type semantic is the default Structured Data type semantic. Expires January 10 2011 [Page 60] Internet-Draft July 2010 Specifies that none of the elements are actual properties of the Data Record. Specifies that only a single element from the Structured Data is an actual property of the Data Record. This is equivalent to a logical XOR operation. Specifies that one or more element(s) from the list in the Structured Data is/are actual propertie(s) of the Data Record. This is equivalent to a logical OR operation. Specifies that all of the list elements from the Structured Data are actual properties of the Data Record. Expires January 10 2011 [Page 61] Internet-Draft July 2010 Specifies that elements from the list in the Structured Data are ordered. The following schema definitions are appended to the abstract data types defined in Appendix B of [RFC5102]. Represents a list of zero or more instances of any single Information Element, primarily used for single-valued data types. For example, a list of port numbers, list of interface indexes, list of AS in a BGP AS-PATH, etc. Represents a list of zero or more instances of a structured data type, where the data type of each list element is the same and corresponds with a single Template Record. For example, a structured data type composed of multiple pairs of ("MPLS label stack entry position", "MPLS label stack value"), a structured data type composed of performance metrics, a structured data type composed of multiple pairs of IP address, etc. Represents a list of zero or more instances of structured data types, where the data type of each list element can be different and corresponds with Expires January 10 2011 [Page 62] Internet-Draft July 2010 different template definitions. For example, a structured data type composed of multiple access-list entries, where entries can be composed of different criteria types. Represents an arbitrary-length sequence of structured data elements, either composed of regular Information Elements or composed of data conforming to a Template Record. Structured Data type semantics express the relationship among multiple list elements in a Structured Data Expires January 10 2011 [Page 63] Internet-Draft July 2010 Information Element. Appendix B. Example of Biflow Encoding using Structured Data Information Elements Referring to [RFC5103] figure 1, a Biflow consists of two parts: some "key" fields such as src/dst information (IP addresses, ports), followed by a set of forward/reverse pairs. Then looking at [RFC5103] figure 7, we see that the Reverse PEN is repeated many times to indicate fields which were observed in the reverse direction. Clearly that repetition is wasteful. Looking back at [RFC5103] figure 1, it's clear that the encoding can use a Template Record consisting of the Flow Keys followed by a subTemplateList consisting of two elements: one for the forward direction, the other for the reverse direction. The subTemplateList uses a single Template Record to describe the fields in both lists since they are a set of forward/reverse pairs. Uniflow Uniflow +-------+-------+-----------------+ +-------+-------+-----------------+ | src A | dst B | counters/values | | src B | dst A | counters/values | +-------+-------+-----------------+ +-------+-------+-----------------+ | | | | V V V V +-------+-------+---------------------+---------------------+ | src A | dst B | fwd counters/values | rev counters/values | +-------+-------+---------------------+---------------------+ | | | V V V key fields fwd element rev element Figure B0: Using a subTemplateList to represent a Biflow. The following example shows the example from Appendix A of [RFC5103] encoded using a subTemplateList: Expires January 10 2011 [Page 64] Internet-Draft July 2010 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 24 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 266 | Field Count = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| flowDirection 61 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| flowStartSeconds 150 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| octetTotalCount 85 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| packetTotalCount 86 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure B1: Template for the Biflow Fields 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 32 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 267 | Field Count = 6 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceIPv4Address 8 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationIPv4Address 12 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceTransportPort 7 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationTransportPort 11 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| protocolIdentifier 4 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| subTemplateList = YYY | Field Length = 29 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure B2: Template for the Key Fields The Template Record includes a subTemplateList with semantic allOf for encoding the BiFlow fields for the forward and reverse direction. Note that the subTemplateList is encoded using Fixed Length, as shown in the above template definition. Expires January 10 2011 [Page 65] Internet-Draft July 2010 Also, note that the overall template size is 24 + 32 = 56 octets, compared with 64 octets in the [RFC5103] example - so a small saving is achieved. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 267 | Length = 46 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceIPv4Address = 192.0.2.2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | destinationIPv4Address = 192.0.2.3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceTransportPort = 32770 | destinationTransportPort = 80 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | protocol = 6 |semantic=allOf | Template ID = 266 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | dir = forward | flowStartSeconds = 2006-02-01 17:00:00 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | octetTotalCount = 18000 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | packetTotalCount = 65 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | dir = reverse | flowStartSeconds = ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 2006-02-01 17:00:01 | octetTotalCount = 128000 ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | packetTotalCount = 110 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure B3: Biflow Data Set Encoded using Structured Data Note that the Data Set length is 46, compared with 41 in RFC5103. The five additional octets are due to the inclusion of the 8-bit semantic, 16-bit Template ID and two, 8-bit direction indicators. Clearly structured data offers an alternative way to encode Biflows. Although this may not be best suited if the number of elements is small as in this example, it does offer a more robust and scalable solution if multiple elements need to be encoded. Expires January 10 2011 [Page 66] Internet-Draft July 2010 Appendix C. Encoding IPS Alert using Structured Data Information Elements In this section, an IPS alert example is used to demonstrate how complex data and multiple levels of hierarchy can be encoded using Structured Data Information Elements. Also, this example demonstrates how a basicList of subTemplateLists can be used to represent semantics at multiple levels in the hierarchy. An IPS alert consists of the following mandatory attributes: signatureId, protocolIdentifier and riskRating. It can also contain zero or more participants, each participant can contain zero or more attackers and zero or more targets. An attacker contains the attributes sourceIPv4Address and applicationId, and a target contains the attributes destinationIPv4Address and applicationId. Note that the signatureId and riskRating Information Element fields are created for these examples only; the Field IDs are shown as N/A. The signatureId helps to uniquely identify the IPS signature that triggered the alert. The riskRating identifies the potential risk, on a scale of 0-100 (100 being most serious), of the traffic that triggered the alert. Consider the example described in case study 2 of Section 5.6. The IPS alert contains participants encoded as a subTemplateList with semantic allOf. Each participant uses a basicList of subTemplateLists to represent attackers and targets. For the sake of simplicity, the alert has two participants P1 and P2. In participant P1, attacker A1 or A2 attack target T1. In participant P2, attacker A3 attacks targets T2 and T3. Participant P1: (basicList, allof, (subTemplateList, exactlyOneOf, attacker A1, A2) (subTemplateList, undefined, target T1) ) Participant P2: (basicList, allOf, (subTemplateList, undefined, attacker A3, Expires January 10 2011 [Page 67] Internet-Draft July 2010 (subTemplateList, allOf, targets T2, T3) ) Alert : (subTemplateList, allOf, Participant P1, Participant P2) ------------------------------------------------------------------ | | | participant sigId |protocol| risk | attacker | target | Id | Rating | IP | appId | IP | appId ------------------------------------------------------------------ 1003 17 10 192.0.2.3 103 192.0.2.103 3001 192.0.2.4 104 192.0.2.5 105 192.0.2.104 4001 192.0.2.105 5001 ------------------------------------------------------------------ Participant P1 contains: Attacker A1: (IP, appID)=(192.0.2.3, 103) Attacker A2: (IP, appID)=(192.0.2.4, 104) Target T1: (IP, appID)= (192.0.2.103, 3001) Participant P2 contains: Attacker A3: (IP, appID) = (192.0.2.5, 105) Target T2: (IP, appID)= (192.0.2.104, 4001) Target T3: (IP, appID)= (192.0.2.105, 5001) To represent an alert, the following Templates are defined: Template for target (268) Template for attacker (269) Template for participant (270) Template for alert (271) alert (271) | (signatureId) | (protocolIdentifier) | (riskRating) | +------- participant (270) | +------- attacker (269) | (sourceIPv4Address) Expires January 10 2011 [Page 68] Internet-Draft July 2010 | (applicationId) | +------- target (268) | (destinationIPv4Address) | (applicationId) Note that the attackers are always composed of a single applicationId, while the targets typically have multiple applicationId, for the sake of simplicity this example shows only one applicationId in the target. Template Record for target, with the Template ID 268: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 16 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 268 | Field Count = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| destinationIPv4Address = 12 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| applicationId = 95 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure C0: Encoding IPS Alert, Template for Target Template Record for attacker, with the Template ID 269: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 16 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 269 | Field Count = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceIPv4Address = 8 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| applicationId = 95 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure C1: Encoding IPS Alert, Template for Attacker Template Record for participant, with the Template ID 270: Expires January 10 2011 [Page 69] Internet-Draft July 2010 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 12 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 270 | Field Count = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| basicList = XXX | Field Length = 0xFFFF | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure C2: Encoding IPS Alert, Template for Participant The Template Record for the participant has one basicList Information Element, which is a list of subTemplateLists of attackers and targets. Template Record for IPS alert, with the Template ID 271: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 24 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 271 | Field Count = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| signatureId = N/A | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| protocolIdentifier = 4 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| riskRating = N/A | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| subTemplateList = YYY | Field Length = 0xFFFF | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure C3: Encoding IPS Alert, Template for IPS Alert The subTemplateList in the alert Template Record contains a list of participants. The Length of basicList and subTemplateList are encoded in three bytes even though they may be less than 255 octets. The Data Set is represented as follows: Expires January 10 2011 [Page 70] Internet-Draft July 2010 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 271 | Length = 102 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | signatureId = 1003 | protocolId=17 | riskRating=10 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 |participant List Length = 91 |semantic=allOf | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | participant Template ID = 270 | 255 | P1 List Len = | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 41 | semantic=allOf| P1 List Field ID = YYY | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P1 List Field ID Len = 0xFFFF | 255 |P1 attacker ...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | List Len = 19 |sem=exactlyOne | P1 attacker Template ID = 269 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P1 attacker A1 sourceIPv4Address = 192.0.2.3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P1 attacker A1 applicationId = 103 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P1 attacker A2 sourceIPv4Address = 192.0.2.4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P1 attacker A2 applicationId = 104 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | P1 target List Len = 11 | sem=undefined | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P1 target Template ID = 268 | P1 target T1 destinationIPv4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... Address = 192.0.2.103 |P1 target T1 applicationId =...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 3001 | 255 | P2 List Len = | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 41 | semantic=allOf| P2 List Field ID = YYY | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P2 List Field ID Len = 0xFFFF | 255 |P2 attacker ...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | List Len = 11 | sem=undefined | P2 attacker Template ID = 269 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P2 attacker A3 sourceIPv4Address = 192.0.2.5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P2 attacker A3 applicationId = 105 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 255 | P2 target List Len = 19 |semantic=allOf | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | P2 target Template ID = 268 | P2 target T2 destinationIPv4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Expires January 10 2011 [Page 71] Internet-Draft July 2010 | ... Address = 192.0.2.104 |P2 target T2 applicationId =...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 4001 | P2 target T3 destinationIPv4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... Address = 192.0.2.105 |P2 target T3 applicationId =...| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... 5001 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure C4: Encoding IPS Alert, Data Set Expires January 10 2011 [Page 72]