]> Brocade Communications Systems, Inc.

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Cisco Systems, Inc.

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Mojo Networks, Inc.

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Jacobs University Bremen

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IPFIX MIB SNMP This document specifies a way to complement IP Flow Information Export (IPFIX) Data Records with Management Information Base (MIB) objects, avoiding the need to define new IPFIX Information Elements for existing MIB objects that are already fully specified. Two IPFIX Options Templates, as well as a method for creating IPFIX Options Templates that are used to export the extra data required to fully describe Simple Network Management Protocol (SNMP) MIB objects in IPFIX, are specified herein.

There is growing interest in using IP Flow Information Export (IPFIX) as a push mechanism for exporting management information. Using a push protocol such as IPFIX instead of a polling protocol like SNMP is especially interesting in situations where large chunks of repetitive data need to be exported periodically. While initially targeted at different problems, there is a large parallel between the information transported via IPFIX and SNMP. Furthermore, certain Management Information Base (MIB) objects are highly relevant to Flows as they are understood today. For example, in the IPFIX Information Model , Information Elements coming from the SNMP world have already been specified, e.g., ingressInterface and egressInterface both refer to the ifIndex object as defined in . In particular, the Management Information Base was designed as a separate system of definitions; this opens up the possibility of exporting objects defined via the MIB over other protocols. Rather than mapping existing MIB objects to IPFIX Information Elements on a case-by-case basis, it would be advantageous to enable the export of any existing or future MIB objects as part of an IPFIX Data Record. This way, the duplication of Data Models , both as SMIv2 MIB objects and IPFIX Information Elements, out of the same Information Model would be avoided. Therefore, the primary goals of this document are: to specify a way to complement IPFIX Data Records with MIB objects; to avoid the need to define new IPFIX Information Elements for existing MIB objects that are already fully specified; to allow the correlation of SNMP and IPFIX sourced data by exporting them together; and to allow SNMP push data from SNMP-only devices to be more easily integrated into IPFIX-based collection infrastructures.

The intended scope of this work is the addition of MIB variable(s) to IPFIX Information Elements in Data Records, in order to complement the Data Records with useful and already&nbhy;standardized information. Special consideration is given to the case of an existing Template Record that needs to be augmented with some MIB variables whose index is already present in the Template Record as an IPFIX Information Element -- for example, a 7&nbhy;tuple Data Record containing the ingressInterface Information Element, which needs to be augmented by interface counters that are indexed by the respective ingressInterface values already contained in the Data Records. See for terminology definitions. Many Data Records contain the ingressInterface and/or the egressInterface Information Elements. These Information Elements carry an ifIndex value, a MIB object defined in . In order to retrieve additional information about the identified interface, a Collector could simply poll relevant objects from the device running the Exporter via SNMP. However, that approach has several problems: It requires implementing a mediation function between two Data Models, i.e., MIB objects and IPFIX Information Elements. Confirming the validity of simple mappings (e.g., ifIndex to ifName) requires either checking on a regular basis that the Exporter's network management system did not reload or imposing ifIndex persistence across an Exporter's reload. Synchronization problems occur because counters carried in Data Records and counters carried in SNMP messages are retrieved from the Exporter at different points in time and thus cannot be correlated. In the best case, assuming very tight integration of an IPFIX Collector with an SNMP polling engine, SNMP data is retrieved shortly after Data Records have been received, which implies a delay of the sum of the active or idle timeouts (if not null) plus the time to export the Data Record to the Collector. If, however, the SNMP data is retrieved by a generic Network Management Station (NMS) polling interface statistics, then the time lag between IPFIX counters and SNMP counters can be significantly higher. See for details regarding active and idle timeouts. This document does not specify how to carry SNMP notifications in IPFIX, even if the specifications in this document could potentially allow this. Since IPFIX is a push mechanism, initiated from the Exporter with no acknowledgment method, this specification does not provide the ability to execute configuration changes. The Distributed Management Expression MIB , which is a mechanism to create new MIB variables based on the content of existing ones, could also be advantageous in the context of this specification. Indeed, newly created MIB objects (for example, the link utilization MIB variable), created with the Distributed Management Expression MIB , could nicely complement Data Records. Another advantage of exporting MIB objects via IPFIX is that IPFIX would benefit from an extended series of types to be exported. The simple and application-wide data types specified in SMIv2 , along with new textual conventions, can be exported within IPFIX and then decoded in the Collector. However, since a textual convention can contain almost any name, this document does not extend the existing "IPFIX Information Elements" subregistry that contains informationElementDataType. The overall architectural model is depicted in . The IPFIX Exporter accesses the device's instrumentation, which follows the specifications contained in MIB modules. Other management interfaces, such as the Network Configuration Protocol (NETCONF) or the device's Command Line Interface (CLI), may provide access to the same instrumentation.

+------+ +-------+ +.........+ +.....+ | SNMP | | IPFIX | : NETCONF : : CLI : +------+ +-------+ +.........+ +.....+ | | | | +--------------------------------------------+ | Instrumentation (specified in MIB modules) | +--------------------------------------------+

IPFIX-specific terminology (Information Element, Template, Template Record, Options Template Record, Template Set, Collector, Exporter, Data Record, Transport Session, Exporting Process, Collecting Process, etc.) used in this document is defined in Section 2 of . As in , these IPFIX-specific terms have the first letter of a word capitalized. This document prefers the more generic term "Data Record" (as opposed to "Flow Record") in relation to the export of MIB objects. Object Identifier (MIB OID) An Object Identifier value is an ordered list of non-negative numbers. For SMIv2, each number in the list is referred to as a sub-identifier. There are at most 128 sub-identifiers in a value, and each sub-identifier has a maximum value of 2^32 - 1 (4294967295 decimal). See , Section 3.5. MIB Object Identifier Information Element An IPFIX Information Element ("mibObjectIdentifier") that denotes that a MIB Object Identifier (MIB OID) is exported in the (Options) Data Record. See . SMIv2 Terminology The key words "MIB module", "MIB object", "INDEX", "AUGMENTS", "textual convention", "columnar object", "conceptual row", and "conceptual table" in this document are to be interpreted as described in SMIv2 . SMIv2 SYNTAX The SYNTAX key words "INTEGER", "Integer32", "OCTET STRING", "OBJECT IDENTIFIER", "BITS", "IpAddress", "Counter32", "Gauge32", "TimeTicks", "Opaque", "Counter64", "Unsigned32", "SEQUENCE", and "SEQUENCE OF" in this document are to be interpreted as described in SMIv2 . SNMP Context Terminology The key words "snmpEngineID", "contextEngineID", and "contextName" in this document are to be interpreted as described in . mibObjectValue Information Elements "mibObjectValue Information Elements" refers to any and all of the mibObjectValue Information Elements generically. Any restriction or requirement in this document that refers to "mibObjectValue" applies to the following Information Elements as defined in : mibObjectValueInteger, mibObjectValueOctetString, mibObjectValueOID, mibObjectValueBits, mibObjectValueIPAddress, mibObjectValueCounter, mibObjectValueGauge, mibObjectValueTimeTicks, mibObjectValueUnsigned, mibObjectValueTable, and mibObjectValueRow. Abstract Data Type Abstract Data Types for IPFIX are defined in Section 3.1 of . This specification uses the Abstract Data Types "unsigned8", "unsigned32", "unsigned64", "signed32", "octetArray", "string", "ipv4Address", and "subTemplateList". IE Used as shorthand for "Information Element" in the figures. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in .

This document specifies a method for creating IPFIX Options Templates that are used to export the extra data required to describe MIB variables (see ). This allows IPFIX Templates to contain any combination of fields defined by traditional IPFIX Information Element(s) and/or MIB Object Identifier(s). The MIB Object Identifiers can reference either non&nbhy;columnar or columnar MIB object(s). Enterprise-specific MIB Object Identifiers are also supported. This document also defines two standard IPFIX Options Templates (see ) that are used as part of the mechanism to export MIB object metadata: MIB Field Options Template () MIB Type Options Template () This document defines three classes of new IPFIX Information Elements. These are used to export values from the MIB, export required Object Identifier information, and optionally export type data from a MIB module: MIB Object Value Information Elements () MIB Field Options Information Elements () MIB Type Information Elements () Additionally, this document defines two new IPFIX semantics that are required for the new Information Elements: snmpCounter () snmpGauge () Two common types defined in SMIv2 are conceptual rows and conceptual tables. It is desirable that exporting a complete or partial conceptual row be simple and efficient. This is accomplished by using IPFIX Structured Data to reduce repetition of Object Identifier and indexing data. To allow the use of individual columnar objects that make up a conceptual row, a method is also specified to explain that a MIB object is indexed by other fields in the same Data Flow. For an individually indexed mibObjectValue, the index fields are sent in the same way as any of the other fields in the same Data Record and may be mibObjectValue Information Element(s) or other existing Information Element(s). Also, in some cases Exporters may not want (or be able) to export the full information on how the MIB objects being exported are indexed. This may be because the MIB object is being used purely as type information or the Exporting Process may not have knowledge of the indexing required. Therefore, providing index information for columnar objects is optional.

This document defines new mibObjectValue Information Elements (in ). These are used to export MIB objects as part of standard IPFIX Templates. The mibObjectValue Information Elements contain the actual data values. The Metering Process or Exporting Process may extract the data values for mibObjectValue Information Elements from a Process that resides on the same device or may capture or create the data required to match the definition of the MIB object. In particular, exporting a value of a MIB object defined in a certain MIB module does not imply that the SNMP process on the device supports that MIB module. The main issue that arises from exporting values of MIB objects in IPFIX is that MIB Object Identifiers do not fit into the standard IPFIX Template format , as this only provides a 16-bit Information Element identifier. The values of a MIB object could be exported using a MIB-specific Information Element, without providing any Object Identifiers. However, without exporting the actual MIB OID, the full type of the data would be unknown, and every field containing MIB object data would appear identical. Without knowing which OID the contents of a field map to, the data would be incomprehensible to a Collector. For the values in the mibObjectValue Information Elements to be understandable, more meta&nbhy;information about the mibObjectValue Information Elements must be sent as part of the IPFIX export. The required minimum information to understand each field that is being exported is provided in . One approach to this problem would be to extend the IPFIX standard to allow extended Field Specifiers so that metadata about fields can be included in Data Templates. This would, however, require a new version of the IPFIX standard that may not be backward compatible. However, future versions of IPFIX may export the required MIB metadata as part of newly defined IPFIX Set versions. This document defines a MIB Field Options Template to export the extra meta&nbhy;information required for mibObjectValue Information Elements. This is a standard IPFIX Options Template Set that includes a minimum set of required fields (see ) and may include extra fields to provide more meta&nbhy;information about one of the mibObjectValue Information Elements. The MIB Field Options export tells the Collecting Process the OID for the MIB object type definition for the following (Template, field).

Four IPFIX Sets are used together to export a Flow that contains mibObjectValue Information Elements. These are: A Template Set that includes the mibObjectValue Information Element. The Template Set informs the Collector that a MIB object value of length N will be exported. This Set may also be an Options Template Set. A MIB Field Options Template Set. The MIB Field Options Template describes which metadata will be sent for each mibObjectValue Information Element being exported. A MIB Field Options Data Set. The MIB Field Options Data Set includes the metadata for each MIB object (i.e., the mibObjectIdentifier or mibSubIdentifier). The metadata about the mibObjectValue Information Elements only needs to be resent as per normal Template refreshes or resends. A Data Set. The Data Set contains only the actual data extracted from the MIB or described by the MIB module. shows the IPFIX Message structure for a MIB field in a Template Set.

The MIB Field Options Template defines MIB Field Options Data Records. The MIB Field Options Data Records annotate the Data Template with mibObjectValue metadata. Together, the Data Template and MIB Field Options Data Records define the Data Records that will be exported. The Data Records (A) have a dependency on the two Templates and the MIB Field Options Data Records. More Data Sets that use the same mibObjectValue Information Element can then be sent in subsequent packets. shows the relationships between the Sets discussed above.

, Section 7.1 specifies that the SYNTAX clause for a MIB object defines the abstract data structure of an object and what it must contain: "The data structure must be one of the following: a base type, BITS, or a textual convention. (SEQUENCE OF and SEQUENCE are also possible for conceptual tables, see section 7.1.12)." For each of the SYNTAX clause options, this document specifies exactly which mibObjectValue Information Element to use. If a MIB object to be exported is a textual convention, the definition of the textual convention must be consulted and the SYNTAX clause used to determine the correct base type. This may recurse if the textual convention is defined in terms of another textual convention, but this should end at a base type. If the SYNTAX clause contains a textual convention or sub&nbhy;typing (e.g., integerSubType, octetStringSubType) , the mibObjectSyntax Information Element SHOULD be used to export this detail to the Collecting Process. The options for the SYNTAX clause are then mapped as follows: Section in RFC 2578 SYNTAX mibObjectValue Information Element 7.1.1 INTEGER/Integer32 mibObjectValueInteger 7.1.2 OCTET STRING mibObjectValueOctetString 7.1.3 OBJECT IDENTIFIER mibObjectValueOID 7.1.4 BITS mibObjectValueBits 7.1.5 IpAddress mibObjectValueIPAddress 7.1.6 Counter32 mibObjectValueCounter 7.1.7 Gauge32 mibObjectValueGauge 7.1.8 TimeTicks mibObjectValueTimeTicks 7.1.9 Opaque mibObjectValueOctetString 7.1.10 Counter64 mibObjectValueCounter 7.1.11 Unsigned32 mibObjectValueUnsigned 7.1.12 SEQUENCE mibObjectValueRow 7.1.12 SEQUENCE OF mibObjectValueTable Values are encoded as per the standard IPFIX encoding of Abstract Data Types. The only new encoding reference in this document is that Object Identifiers (OIDs) will be encoded as per ASN.1/BER in an octetArray. The mibObjectValue and mibObjectIdentifier Information Elements are standard IPFIX fields. Therefore, the E bit of the mibObjectValue or mibObjectIdentifier Information Elements is set to 0. The MIB object being exported may be defined in an enterprise-specific MIB module, but the Information Elements defined in this standard are still exported with the E bit set to 0. The OID being exported indicates that the MIB object was defined in an enterprise&nbhy;specific MIB module.

For each mibObjectValue Information Element that is defined in an IPFIX Template, a MIB Field Options Data Record will be exported that provides the required minimum information to define the MIB object that is being exported (see ). The MIB Field Options Data Records are defined in a Template referred to in this document as a MIB Field Options Template with the format specified in . The MIB Field Options Template and MIB Field Options Data Records MUST be exported in the same IPFIX Message as any Template that is using a mibObjectValue Information Element. Note that this places an implicit size constraint on the export. This whole set of Templates and MIB Field Options Data Records MUST all be exported prior to the corresponding Data Records that depend upon them. That is, the export order MUST be: Data Template for mibObjectValue Information Elements (Set ID 2) MIB Field Options Template (Set ID 3) MIB Field Options Data Records (Set ID >= 256) MIB Object Value Data Records (Set ID >= 256) Note that the ID of an identical MIB Field Options Template that has already been exported MAY be reused without exporting the Template again. IPFIX Set IDs are defined in Section 3.3.2 of . A value of 2 indicates a Template Set, a value of 3 indicates an Options Template Set, and values 256 and above indicate Data Sets.

Three fields are REQUIRED to unambiguously export a standalone mibObjectValue Information Element with a MIB Field Options Template: (scope) templateId (scope) informationElementIndex mibObjectIdentifier () or mibSubIdentifier () These are the minimum fields required in a MIB Field Options Template (see ). The mibObjectIdentifier is used to provide the OID for all mibObjectValue Information Elements exported, except when IPFIX Structured Data is being used to export a conceptual row (see ). While the following are optional, they are nevertheless RECOMMENDED in certain circumstances, as described in the referenced sections: mibCaptureTimeSemantics (discussed in ; Information Element defined in ) mibIndexIndicator (discussed in ; Information Element defined in ) mibContextEngineID (discussed in ; Information Element defined in ) mibContextName (discussed in ; Information Element defined in )

There are also fields that provide type information from a MIB object definition that MAY be exported to a Collecting Process. Type information is statically defined in a MIB module; it is not expected to change. However, the additional information about the MIB object may help a Collecting Process that does not have access to the MIB module. To export a MIB Type Options Template, the mibObjectIdentifier is RECOMMENDED as a Scope Field so that it matches the MIB Field Options Template. Any combination of the other MIB Type fields may be included. (scope) mibObjectIdentifier (see ) mibObjectName (see ) mibObjectDescription (see ) mibObjectSyntax (see ) mibModuleName (see )

The Template Record format of a Template that uses a mibObjectValue Information Element is identical to the standard IPFIX format as defined in , so a field using a mibObjectValue Information Element is specified using standard IPFIX Field Specifiers per . The only extra requirement on a Template Record using one or more mibObjectValue Information Elements is that it MUST export the required metadata specified in for EACH mibObjectValue Information Element. If multiple MIB Field Options Data Records that refer to a mibObjectValue are received, the latest MUST be used. This matches the expected behavior of IPFIX Templates. There is a one-to-one mapping between each mibObjectValue Information Element and a MIB Field Options Data Record. A MIB Field Options Template and corresponding Data Record MUST be exported to provide the minimum required metadata. shows an IPFIX Template Set using a mibObjectValue Information Element.

| Field Length (MIB) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]>

Where: <mibObjectValue> One of the mibObjectValue IPFIX Information Elements that denotes that MIB object data (i.e., the value of a MIB object) will be exported in the (Options) Data Record. This could be any one of the mibObjectValue Information Elements defined in : mibObjectValueInteger, mibObjectValueOctetString, mibObjectValueOID, mibObjectValueBits, mibObjectValueIPAddress, mibObjectValueCounter, mibObjectValueGauge, mibObjectValueTimeTicks, mibObjectValueUnsigned, mibObjectValueTable, and mibObjectValueRow. When a mibObjectValue Information Element is used, the MIB Object Identifier ("mibObjectIdentifier") MUST be exported via a MIB Field Options Template and MIB Field Options Data Record. See . Field Length (MIB) The length of the encoded MIB object data in the corresponding Data Records, in octets. See for a detailed definition. Note that the Field Length can be expressed using reduced&nbhy;size encoding per . Note that the Field Length may be encoded using variable-length encoding per .

The MIB Field Options Template is a standard Options Template that defines the fields that will be exported to provide enough metadata about a mibObjectValue Information Element so that the Collector can tie the data values in the mibObjectValue Information Element back to the definition of the MIB object. All MIB Field Options Templates contain the fields specified in . shows the required fields to export a mibObjectIdentifier for the MIB Field Options Template format.

Where: templateId The first Scope Field is an IPFIX Information Element that denotes that a Template Identifier will be exported as part of the MIB Field Options Data Record. This Template Identifier, paired with an index into that Template (the "informationElementIndex" field), uniquely references one mibObjectValue Information Element being exported. informationElementIndex The second Scope Field is an IPFIX Information Element that denotes a zero-based index into the fields defined by a Template. When paired with a "templateId", this uniquely references one mibObjectValue Information Element being exported. mibObjectIdentifier An IPFIX Information Element that denotes the MIB Object Identifier for the mibObjectValue Information Element exported in the (Options) Template Record. When a MIB Object Value Information Element is used, the MIB Object Identifier MUST be specified in the MIB Field Options Template Record or specified by other means. The Object Identifier is encoded in the IPFIX Data Record in ASN.1/BER format. Variable-length encoding SHOULD be used with the mibObjectIdentifier so that multiple MIB OIDs of different lengths can be exported efficiently. This will also allow reuse of the MIB Field Options Template. Variable-length encoding is indicated by the Field Length value of 65535, per Sections 3.2 and 7 of . The RECOMMENDED use of variable-length encoding for mibObjectIdentifier fields is indicated in subsequent figures by placing 65535 in the relevant length fields.

The MIB Field Options Data Records conform to the Template Specification in the MIB Field Options Template. There may be multiple MIB Field Options Data Records exported. The Collecting Process MUST store all received MIB Field Options Data information for the duration of each Transport Session, because the Collecting Process will need to refer to the extra meta&nbhy;information to fully decode each mibObjectValue Information Element. shows the format of the exported MIB Field Options Data Record, detailing the metadata that will be exported to match the Template in .

VLEN contains the variable length of the mibObjectIdentifier per Section 7 of .

The Options Template Record format of a Template that uses a mibObjectValue Information Element is identical to the standard format as defined in . The mibObjectValue Information Element is specified using standard Field Specifiers per . A mibObjectValue Information Element can be either a Scope Field or a non-Scope Field in an Options Template Record. The only extra requirement on an Options Template Record using one or more mibObjectValue Information Elements is that it MUST export the required metadata specified in for EACH mibObjectValue Information Element. An IPFIX Options Template Record MUST export a MIB Field Options Template and Data Record to provide the minimum required metadata for each mibObjectValue Information Element. shows an IPFIX Options Template Set using an existing IPFIX field as a Scope Field and with a mibObjectValueInteger Information Element as a non&nbhy;Scope Field, while shows an IPFIX Options Template Set using a mibObjectValueInteger Information Element as a Scope Field with an existing IPFIX field as a non-Scope Field.

A MIB Field Options Template MAY specify that extra Information Elements will be exported to record how the mibObjectValue was collected. Alternatively, one of the existing IPFIX observationTime* elements may be exported to specify exactly when the value was collected. shows the MIB Field Options Template for a non-columnar field with Semantic Data.

Where: mibObjectIdentifier Note the use of variable-length encoding for this field. mibCaptureTimeSemantics The MIB Capture Time Semantics IPFIX Information Element, as defined in . It is RECOMMENDED to include this field when exporting a mibObjectValue Information Element that specifies counters or statistics, particularly for situations with long-lived Flows.

The OID exported within the mibObjectIdentifier IPFIX Information Element provides an OID reference to a MIB object type definition that will fully describe the MIB object data being exported. However, an Exporting Process MAY decide to include some extra fields to more fully describe the MIB object that is being exported with a mibObjectValue Information Element. This can be helpful if the Collecting Process may not have access to the MIB module. The Exporting Process can either include the fields with extra object details as part of the MIB Field Options Template or export a separate Options Template and a Data Record that maps MIB OIDs in mibObjectIdentifier fields to the object details. If only a few fields are being exported, then including extra type data in the MIB Field Options export will be more efficient. The MIB Field Options Template for a non-columnar field with extra MIB object details is shown in .

Where: mibObjectSyntax The MIB object syntax string as defined in . Note that a separate mibObjectSyntax Information Element is required (rather than extend the existing "IPFIX Information Elements" subregistry that contains informationElementDataType) because the SYNTAX clause could contain almost any name. mibObjectName The textual name of a mibObjectIdentifier object. mibObjectDescription The textual description for a mibObjectIdentifier. mibModuleName The textual name of the MIB module that defines a MIB object. Note the use of variable-length encoding for the mibObjectIdentifier, mibObjectSyntax, mibObjectName, mibObjectDescription, and mibModuleName, since these are all string fields. The MIB details can be exported in Data Records specified using a regular IPFIX Options Template Record , as shown in . This may be more efficient, as the bulk of this data is text based and SHOULD be exported only once to the Collecting Process if there are many MIB objects being exported. This prevents this large textual data from being included for every use of a mibObjectValue Information Element.

The MIB Field Options Template export makes use of the informationElementIndex to specify which field in the Template the metadata relates to; this avoids any ordering constraints on the Data Template. The mibObjectValue Information Elements in an IPFIX export can be in any order in the export packet. However, fields used as an INDEX MUST be in the same order as the order specified in the INDEX clause of the conceptual row MIB object. The informationElementIndex specifies which field in the Template extra information is being provided for. This is analogous to standard IPFIX Template Sets, which also specify the order of the fields and provide their type and size. If the Template changes such that the order is different, then the MIB Field Options Data MUST be resent to reflect the new ordering. A new Template ID MUST be used to reflect that the ordering has changed. Older MIB Field Options Data may refer to the incorrect field. A templateId is only locally unique within a combination of an Observation Domain and Transport Session. As such, each MIB Field Options Data Record can only refer to templateIds within the same Observation Domain and session.

Each MIB OID is looked up in a specific context, usually the default context. If exporting a MIB OID value that isn't in the default context, then the context MUST be identified by including the mibContextEngineID (see ) and mibContextName (see ) fields in the MIB Field Options Template and associated MIB Field Options Data Records, or be included in the same Template as the mibObjectValue field. This context data MUST be included for each field that is not in the default context. The context information MAY be exported as part of the Template that includes the mibObjectValue Information Element, or the context information MAY be exported in the MIB Field Options Data Record that refers to the field. Context fields exported in the same Template MUST take precedence over those that refer to the Template. Context fields MUST apply to all mibObjectValue Information Elements in the same Template, and there MUST NOT be duplicates of mibContextName or mibContextEngineID in a Template. So, a MIB Field Options Template MAY specify no context information, just the context engine ID or both the context engine and context name. This allows the Exporter to export the bulk of data in the default context and only tag those items that are required. Since the MIB Field Options Template applies for all the Data Records of a Template, using context fields in the MIB Field Options Data Template requires that each mibContextEngineID / mibContextName pair have its own Template.

Templates are managed as per Section 8 of , with the additional constraint that the MIB Field Options Template and MIB Field Options Data Records MUST be exported in the same IPFIX Message as any (Options) Template Record that uses a mibObjectValue Information Element. When exporting over a Stream Control Transmission Protocol (SCTP) transport , the MIB Field Options Data Records MUST be exported reliably and in the same SCTP stream as their associated Templates per . If a Template using a mibObjectValue Information Element is resent for any reason, the Data Records it depends on MUST be sent as well. If a Template is replaced with a new (Options) Template, then a new MIB Field Options Data Record MUST be sent with the replacement referencing the new Template ID. An Exporting Process SHOULD reuse MIB Field Options Template IDs when the Templates are identical. Each (Options) Template Record MUST still be accompanied by a copy of the MIB Field Options Template.

The requirement to export the MIB Field Options Template and MIB Field Options Data Records in the same IPFIX Message as any (Options) Template Record that uses a mibObjectValue Information Element may result in very large IPFIX Messages. In environments with restricted Message sizes, and only when a reliable SCTP transport is being used, the MIB Field Options Template, MIB Field Options Data, Data Template, and Data Records MAY be exported in separate Messages in the same SCTP stream, provided that their order is maintained.

Data Records containing mibObjectValue Information Elements MUST NOT be exported if their corresponding Data Template or MIB Field Options Template has been withdrawn, since the MIB Field Options Template MUST be exported in the same IPFIX Message as the Data Template that it annotates, except as allowed by the caveat mentioned in . MIB Field Options Template IDs MUST NOT be reused while they are required by any existing Data Templates.

There are three approaches for an IPFIX Exporting Process to export the values of columnar objects: Ignoring the indexing of columnar objects Exporting conceptual rows / table objects using IPFIX Structured Data Exporting individual indexed columnar objects Firstly, a subordinate columnar object may be used purely as a data type. In this case, there is no index information or relation to a conceptual row object provided by the Exporting Process. Secondly, mibObjectValueRow or mibObjectValueTable can be used to export partial or complete conceptual rows, using IPFIX Structured Data . Thirdly, in a mixed option/data IPFIX/MIB Template, the mibObjectValue Information Element can have the values of the INDEX clause of the conceptual row provided by other fields in the Data Record. In this case, each mibObjectValue Information Element must specify which other field(s) in the Template is providing the index information.

This document defines two forms of indexing that can be used for conceptual row MIB objects: Indexing based on IPFIX Structured Data is used solely by the mibObjectValueRow Information Element. Each conceptual row of the MIB object corresponds to a single Data Record exported. The index fields defined in the INDEX clause of the MIB object MUST all be present in the same order as the Scope Fields. This allows a simple table export of a conceptual row MIB object without any extra fields required to indicate which fields make up the conceptual row INDEX. Field-based indexing is used by giving each mibObjectValue Information Element a mibIndexIndicator to flag the required index fields. This allows complex indexing or mixing of existing IPFIX Information Elements with MIB fields, with minimum overhead. It also allows multiple columnar MIB objects from different conceptual rows to be exported with complete indexing in one IPFIX Template.

The simplest approach to exporting a complete or partial conceptual row object is done with the mibObjectValueRow Information Element. This is an IPFIX Structured Data subTemplateList Information Element as detailed in . The Template specified MUST be an Options Template. It also MUST have the fields specified in the INDEX clause of the conceptual row object as the Scope Fields in the MIB Field Options Template and Data Set. An overview of this architecture is given in . This shows that the full MIB object type definition OID is exported for the mibObjectValueRow conceptual row field but that the individual columnar objects only require the sub&nbhy;identifier to be exported. To make the diagram clearer, the Templates for the MIB Field Options Templates are not shown.

The mibIndexIndicator is not required for each individual mibObjectValue Information Element, as mibObjectValueRow provides a structure that includes the index details. When indexing based on IPFIX Structured Data is used, all Scope Fields MUST be the INDEX objects in the same order as defined in the INDEX clause of the conceptual row being exported. Each conceptual table MIB object has two related OIDs. There is an OID that refers to the table with the syntax of SEQUENCE OF and an OID that refers to each entry or conceptual row with the syntax of SEQUENCE. The OID for the SEQUENCE of a conceptual row MUST be exported. For example, in the IF-MIB , the OID for ifEntry should be exported rather than the OID for ifTable. The OID for the table (in this case, ifTable) can be derived by removing one sub&nbhy;identifier from the ifEntry OID. The full OID for the conceptual row MIB object type definition being exported with the mibObjectValueRow Information Element MUST be exported. However, the fields that are members of the conceptual row need not have the full OID of their MIB object type definition exported. Instead, the mibSubIdentifier Information Element can be used to document which entry in the conceptual row the field is. In this case, the exported Flow will contain a single complete or partial row from a table inside a single field of the Data Record. There may be MIB objects that are specified in the INDEX of the conceptual row but not columnar objects of the same conceptual row; for these, the Exporter MUST provide the full OID in a mibObjectIdentifier field. So, for a conceptual row object with the OID "1.2.3.4.5.6" the OID of the type definitions for columnar objects "1.2.3.4.5.6.1" "1.2.3.4.5.6.2" can be exported with just a mibSubIdentifier of "1" and "2", respectively. The mibObjectValue Information Elements exported using the mibObjectValueRow export MUST all either be objects defined in the INDEX clause, columnar objects of the same conceptual row object, or columnar objects that augment the same conceptual row. The IPFIX Structured Data subTemplateList format requires the Structured Data Type Semantics to be specified. Unless there is a more appropriate option in the "IPFIX Structured Data Types Semantics" subregistry , the "undefined" Structured Data Type Semantics can be used. shows an IPFIX Template for an IPFIX Structured Data export of a conceptual row, while shows an IPFIX Options Template for a complete conceptual row with five columns and two index fields. shows the MIB Field Options Template for a conceptual row field. shows the MIB Field Options Template for the columns inside the conceptual row. shows the OID Data for the conceptual row that will be exported.

Where: templateId The templateId for the MIB option that will be exported. mibObjectIdentifier The MIB OID for the conceptual row that is being exported. Note the use of variable-length encoding for this field.

Where: templateId The templateId used will be for the Template referred to in the subTemplateList of the mibObjectValueRow that will be exported. mibSubIdentifier The sub-identifier that specifies the columnar object's ID within the conceptual row.

Where: mibObjectIdentifier Will contain the OID for the conceptual row as a whole. mibSubIdentifier The mibSubIdentifier fields will contain the extra sub&nbhy;identifier that, when added to the OID for the conceptual row, gives the full OID for the object.

SMIv2 defines conceptual rows as having either an INDEX clause or an AUGMENTS clause. Conceptual row definitions with an AUGMENTS clause extend an existing base conceptual row with an INDEX clause. It is not possible in SMIv2 to augment a conceptual row that itself has an AUGMENTS clause. The base table and the augmentation have an identical INDEX. Since augmentations allow adding extra columns to existing tables, it is beneficial to be able to support them easily in IPFIX exports of conceptual rows. The mibObjectValueRow OID MAY refer to either the base table with the INDEX clause or a conceptual row with an AUGMENTS clause. The mibSubIdentifier in any MIB Field Options Data Record MUST always refer to the OID exported for the mibObjectValueRow Information Element. If the mibObjectValueRow OID refers to a base table, then any extra columns from conceptual rows with an AUGMENTS clause MUST have their full OID exported. If the mibObjectValueRow OID refers to a conceptual row that augments another conceptual row using the AUGMENTS clause, then any MIB fields from the original table's INDEX or columnar objects MUST NOT use the mibSubIdentifier and MUST instead export the full OID in a mibObjectIdentifier. If the mibObjectValueRow refers to an augmenting conceptual row, the Scope Fields of the Template used in the subTemplateList MUST have the index fields from the base table, in the same order as its scope. This is identical to the Scope Field requirements for conceptual rows with an INDEX clause. This flexibility is provided so that the conceptual rows with the most columns can be exported using the more efficient mibSubIdentifier. For example, exporting a complete set of augmentation columns would only require the full OIDs for the MIB objects in the INDEX. It is possible to export MIB object columns from multiple augmenting conceptual rows. If this is done, then the base table SHOULD be used as the main OID for the mibObjectValueRow.

Multiple rows of a conceptual table can be exported in the mibObjectValueTable Information Element (). This allows a set of conceptual rows corresponding to a conceptual table to be exported as a single field. Therefore, a complete set of rows can be exported as a single field with other Information Elements in a Template. In this fashion, several complete conceptual tables could be exported in one packet. As also specified for mibObjectValueRow (), the more specific (i.e., full) OID of the SEQUENCE entity MUST be exported. The format of mibObjectValueTable is identical to mibObjectValueRow, except that the length of the subTemplateList may be zero or more entries. All the other, i.e., non-length, requirements for mibObjectValueRow in apply to mibObjectValueTable. An overview of this architecture is given in . This architecture is similar to the architecture shown in .

The other option for indexing a columnar object that is part of a conceptual table is explicit indexing. In this case, the Options Template Set scope may contain either non&nbhy;index fields or columnar MIB objects from multiple conceptual rows being exported. In this case, each mibObjectValue Information Element requires the mibIndexIndicator with the bits set for the fields that are used to index that individual columnar object. The index fields MUST be in the "correct" order as defined in the conceptual row that each columnar object is a member of. If a mibObjectValue Information Element that is being indexed using mibIndexIndicator is being used as an Options Template Scope Field, then all fields used to index that field MUST also be Scope Fields. shows the MIB Field Options Template for an indexed MIB columnar object.

Where: mibIndexIndicator The MIB Index Indicator IPFIX Information Element that marks which fields in the Data Record will act as INDEX values for the exported MIB object. The index data for a mibObjectValue will be other fields contained in the same Data Record. The mibIndexIndicator marks the fields whose value(s) should be added to the OID for the MIB object type definition exported in mibObjectIdentifier to get the OID for the instance of the MIB object. Elements used to index MIB objects MUST be exported in the same order as they are specified in the index field of the conceptual table they belong to. mibObjectIdentifier Note the use of variable-length encoding for this field.

The number of established TCP connections of a remote network device could be monitored by configuring it to periodically export the number of established TCP connections to a centralized Collector. In this example, the Exporter would export an IPFIX Message every 30 minutes that contained Data Records detailing the number of established TCP connections. The table of data that is to be exported looks like: TIMESTAMP ESTABLISHED TCP CONN. StartTime + 0 seconds10 StartTime + 60 seconds14 StartTime + 120 seconds19 StartTime + 180 seconds16 StartTime + 240 seconds23 StartTime + 300 seconds29 The Template Record for such a Data Record will provide details for the following two Information Elements: flowStartSeconds from , Information Element 150: The absolute timestamp of the first packet of this Flow. tcpCurrEstab from , Object ID "1.3.6.1.2.1.6.9": The number of TCP connections for which the current state is either ESTABLISHED or CLOSE-WAIT. shows the exported Template Set detailing the Template Record for exporting the number of established TCP connections.

shows the exported MIB Field Options Template Set detailing the metadata that will be exported about the mibObjectValueGauge Information Element in Template 400 in Template Record.

shows the exported MIB Field Options Data Set detailing the metadata that will be exported about the mibObjectValueGauge Information Element in Template 400 in Template Record. The OID for the MIB object tcpCurrEstab from , Object ID "1.3.6.1.2.1.6.9", will be encoded in ASN.1/BER as "06072B060102010609" in the Data Record, which takes 9 octets.

shows the start of the Data Set for exporting the number of established TCP connections (see ).

For the sake of demonstration, an enterprise-specific MIB object from the CISCO-PROCESS-MIB is chosen. This example would be valid with any enterprise-specific MIB module. The CPU usage of a remote network device with one CPU could be monitored by configuring it to periodically export CPU usage information, i.e., the cpmCPUTotal1minRev from the proprietary CISCO&nbhy;PROCESS&nbhy;MIB, Object ID "1.3.6.1.4.1.9.9.109.1.1.1.1.7", to a centralized Collector. Although the cpmCPUTotal1minRev MIB object is a columnar object in a conceptual row, if there is only one CPU no extra information is conveyed by providing the index field. So, in this case, it is acceptable to not export the cpmCPUTotalIndex MIB object. If there were multiple CPUs, it would be appropriate to include the cpmCPUTotalIndex field and specify the relationship. In this example, the Exporter would export an IPFIX Message every 30 minutes that contained Data Records detailing the CPU 1&nbhy;minute busy average at 1&nbhy;minute intervals. The table of data that is to be exported looks like: TIMESTAMP CPU BUSY PERCENTAGE StartTime + 0 seconds10% StartTime + 60 seconds14% StartTime + 120 seconds19% StartTime + 180 seconds16% StartTime + 240 seconds23% StartTime + 300 seconds29% The Template Record for such a Data Record will provide details for the following two Information Elements: flowStartSeconds from , Information Element 150: The absolute timestamp of the first packet of this Flow. A mibObjectValueGauge for cpmCPUTotal1minRev, the overall CPU busy percentage in the last 1&nbhy;minute period. shows the exported Template Set detailing the Template Record for exporting CPU Load (see ).

shows the exported Template Set detailing the MIB Field Options Template for exporting CPU Load (see ). Note: This is identical to the MIB Field Options Template given in , so the same Template could have been reused.

shows the exported MIB Field Options Data Set detailing the metadata that will be exported about the mibObjectValueGauge Information Element in Template 402 in Template Record (see ). The OID for the cpmCPUTotal1minRev has been encoded using ASN.1/BER to "060D2B0601040109096D0101010107" at 15 octets long.

Note that although cpmCPUTotal1minRev is 32 bits long, reduced&nbhy;size encoding has been used to encode it within a single octet. The encoding size was specified by setting the length for the mibObjectValueGauge field to 1 octet in the main Data Template; see . This example stresses that, even though the OID cpmCPUTotal1minRev is enterprise-specific, the E bit for the mibObjectValueGauge and mibObjectIdentifier is set to 0, because the mibObjectValueGauge and mibObjectIdentifier Information Elements are not enterprise-specific. That this data is from an Enterprise MIB is included in the OID that includes an Enterprise ID. The corresponding Data Set does not add any value for this example and is therefore not displayed.

Many conceptual tables are already defined in standard and proprietary MIBs. These can be exported with a minimum of overhead by using the mibObjectValueRow. This allows the Exporting Process to unambiguously define the INDEX for the entire conceptual row as the Scope Fields of an Options Template Set. The use of a MIB Field Options Template with mibSubIdentifier being used means that each individual columnar object does not need to have its OID exported to the Collector. The ospfNbrTable, defined in the OSPF MIB , consists of ospfNbrEntry, which has the OID "1.3.6.1.2.1.14.10.1". Each mibObjectValueRow Data Record will therefore correspond to an ospfNbrEntry. The following fields will be exported: Object ID mibObjectValue Len ospfNbrIpAddr ospfNbrEntry 1 mibObjectValueIPAddress4 ospfNbrAddress- ospfNbrEntry 2 mibObjectValueInteger 4 -LessIndex ospfNbrRtrId ospfNbrEntry 3 mibObjectValueIPAddress4 ospfNbrState ospfNbrEntry 6 mibObjectValueInteger 1 The OIDs that will be used to export this table are shown in . Entity Full OID Exported as ospfNbrEntry 1.3.6.1.2.1.14.10.1 1.3.6.1.2.1.14.10.1 ospfNbrIpAddr 1.3.6.1.2.1.14.10.1.1 1 ospfNbrAddress- 1.3.6.1.2.1.14.10.1.2 2 -LessIndex ospfNbrRtrId 1.3.6.1.2.1.14.10.1.3 3 ospfNbrState 1.3.6.1.2.1.14.10.1.6 6 shows the Templates exported to support the mibObjectValueRow. shows the example OID Data for the conceptual row exported in mibObjectValueRow. shows the example data export for a few neighbors in the table; also shows a Data Record formatted as per IPFIX Structured Data and using the "undefined" (= 0xFF) semantic from the "IPFIX Structured Data Types Semantics" subregistry . Note that the OID for ospfNbrEntry has been encoded using ASN.1/BER to "06082B060102010E0A01" at 10 octets long.

The ifTable, defined in the IF-MIB , is augmented by the ifXTable (defined in the same MIB module). The OID of the ifEntry is 1.3.6.1.2.1.2.2.1, which is encoded using ASN.1/BER to "06082B06010201020201" at 10 octets long, while the OID of the augmenting ifXEntry is 1.3.6.1.2.1.31.1.1.1, which is encoded using ASN.1/BER to "060A2B060102011F01010101" at 12 octets long. This example demonstrates how columnar objects from the base conceptual row and the augmenting row can be exported in a single mibObjectValueRow Information Element. shows the fields that will be exported. ifIndex ifType ifMtu ifName 1 ethernetCsmacd:6 1500Ethernet 10 2 ethernetCsmacd:6 1500Ethernet 20 3 ethernetCsmacd:6 1500FastEthernet 30 The OIDs that will be used to export this table are shown in . Entity Full OID Exported as ifEntry1.3.6.1.2.1.2.2.1 OID = 1.3.6.1.2.1.2.2.1 ifIndex1.3.6.1.2.1.2.2.1.1 subID = 1 ifType 1.3.6.1.2.1.2.2.1.3 subID = 3 ifMtu 1.3.6.1.2.1.2.2.1.4 subID = 4 ifName 1.3.6.1.2.1.31.1.1.1.1 OID = 1.3.6.1.2.1.31.1.1.1.1 shows the Templates exported to support the mibObjectValueRow Information Element. shows the example OID Data for the conceptual row exported in mibObjectValueRow to match . shows the example data export as per .

It may be that the full set of columnar objects that are supported by a conceptual row are not required to be exported. Rather than use the IPFIX Structured Data method, the mibIndexIndicator method can be used to provide the relationship between fields. This example shows the MIB objects that are part of the INDEX of the conceptual row being exported in the correct order and then being referred to by using mibIndexIndicator. This example shows the export of ipIfStatsInForwDatagrams from the IP-MIB . ipIfStatsInForwDatagrams is a columnar object that is part of the ipIfStatsTable conceptual table. This is comprised of ipIfStatsEntry conceptual rows. The ipIfStatsTable conceptual table is indexed by ipIfStatsIPVersion and ipIfStatsIfIndex. The Options Template Record for the example Data Record contains the following Information Elements: ipIfStatsIPVersion (1.3.6.1.2.1.4.31.3.1.1) (Scope Field) (encoded using ASN.1/BER to "060A2B06010201041F030101" at 12 octets long) ipIfStatsIfIndex (1.3.6.1.2.1.4.31.3.1.2) (Scope Field) (encoded using ASN.1/BER to "060A2B06010201041F030102" at 12 octets long) ipIfStatsInForwDatagrams (1.3.6.1.2.1.4.31.3.1.12) (non-Scope Field) (encoded using ASN.1/BER to "060A2B06010201041F03010C" at 12 octets long) Note that ipIfStatsIfIndex has been reduced-size encoded to 2 octets in the following example. An exporting device with more interfaces would use the full length. shows the exported Options Template Set.

shows the exported MIB Field Options Template used to export the required mibObjectValue Information Element metadata. This example of the MIB Field Options Template includes the mibIndexIndicator to indicate that some of the other fields in the Data Records are index objects.

shows the exported MIB Field Options Data used to export the required mibObjectValue Information Element metadata. Note that the first two Data Records have all their mibIndexIndicator bits set to 0. The third mibIndexIndicator has the value "00000011" to show that the first two fields in the Data Record are the INDEXes for this columnar object.

shows the Data Records that export the values of the three mibObjectValue Information Elements.

If a Packet Sampling (PSAMP) Packet Report was generated on any dropped packets on an interface, then it may be desirable to know if the send queue on the output interface was full. This could be done by exporting the size of the send queue (ifOutQLen) in the same Data Record as the PSAMP Packet Report. The exported data looks like: SRC ADDR DST ADDR PKT LEN OUTPUT INTERFACE OUTPUT QUEUE LEN (ifOutQLen) 192.0.2.1 192.0.2.3 150 Eth 1/0 (15) 45 192.0.2.4 192.0.2.9 350 Eth 1/0 (15) 45 192.0.2.3 192.0.2.9 650 Eth 1/0 (15) 23 192.0.2.4 192.0.2.6 350 Eth 1/1 (16) 0 The ifOutQLen MIB object, defined in the IF-MIB , provides the length of the output packet queue. This columnar object is part of the ifEntry conceptual row and indexed by the interface index (ifIndex). This relationship between the ifOutQLen field and the index field is exported using mibIndexIndicator in the MIB Field Options Template. The value of "00001000" flags the index fields concisely. The Template Record for the example Data Record contains the following Information Elements: sourceIPv4Address destinationIPv4Address totalLengthIPv4 egressInterface ifOutQLen (indexed by egressInterface) shows the exported Template Set detailing the Template for exporting a PSAMP Report with ifOutQLen. Figures and show the MIB Field Options Template and Data Record.

The corresponding IPFIX Data Record is shown in . For the sake of the example, the interface index of "Eth 1/0" is 15 and the interface index of "Eth 1/1" is 16.

If the context used to export the MIB objects is the default one, no extra context fields are required. This example demonstrates how to handle the case when the context needs to be specified. It is based on the previous example (). The OSPF details of the conceptual row that was exported per would be suitable if there were only one OSPF process running at the Observation Point. If multiple OSPF processes are present, then they can be differentiated by also exporting the mibContextEngineID and mibContextName. The following fields will be exported: Object ID mibObjectValue Len ospfNbrIpAddr ospfNbrEntry 1 mibObjectValueIPAddress4 ospfNbrAddress- ospfNbrEntry 2 mibObjectValueInteger 4 -LessIndex ospfNbrRtrId ospfNbrEntry 3 mibObjectValueIPAddress4 ospfNbrState ospfNbrEntry 6 mibObjectValueInteger 1 The example contextEngineID matches the example from for Acme Networks: "'800002B804616263'H (enterprise 696, string "abc")". shows the Templates exported to support a mibObjectValueRow that is defined within a context. shows the example OID Data for the conceptual row exported in mibObjectValueRow. These are unchanged from the previous example (). shows the example data for two OSPF neighbors. Although these have identical INDEX&wj;/scope values, the context information indicates that they come from different OSPF processes. Note that the OID for ospfNbrEntry has been encoded using ASN.1/BER to "06082B060102010E0A01" at 10 octets long.

When configuring a MIB OID for export, consideration should be given to whether the SNMP context should also be configurable. If a non-default context is used, then it should be associated with the fields as per .

The specifications in Section 9 of also apply to Collectors that implement this specification. In addition, the following specifications should be noted: A Collecting Process that implements this specification MUST store the Data Records containing the OID object type definitions with the same retention policy as Templates. A Collecting Process that implements this specification SHOULD have access to MIB modules in order to look up the received MIB Object Identifiers and find the full type definition and name of MIB OID fields used in received Templates. It should be noted that, because reduced&nbhy;size encoding MAY be used by the Exporting Process, the Collecting Process cannot assume that a received size for a field is the maximum size it should expect for that field. If a Collecting Process receives a MIB Object Identifier that it cannot decode, it MAY log a warning. A Collecting Process MUST support the three options for handling columnar objects detailed in .

Making available the many and varied items from MIB modules opens up a wide range of possible applications for the IPFIX protocol, some quite different from the usual Flow information. Some monitoring applications periodically export a mapping of interface ID to interface name using IPFIX Options Templates. This could be expanded to include the ifInUcastPkts MIB object as defined in the IF&nbhy;MIB , indexed using the ingressInterface Information Element. This would provide the input statistics for each interface; these statistics can be compared to the Flow information to ensure that the sampling rate is as expected, or, in the absence of sampling, to ensure that all expected packets are being monitored.

For this extension to the IPFIX protocol, the same security considerations as those for the IPFIX protocol apply . If the Exporter is generating or capturing the field values itself, e.g., using the MIB objects only as an encoding or type mechanism, there are no extra security considerations beyond standard IPFIX. However, if the Exporter is implemented as an SNMP manager accessing an SNMP agent, it MUST authenticate itself to the SNMP agent , and the SNMP agent MUST enforce SNMP access control rules as required by the SNMP architecture . Access to particular MIB objects is controlled by the configuration of the IPFIX Exporter. This is consistent with the way IPFIX controls access to other Information Elements in general. The configuration of an IPFIX Exporter determines which MIB objects are included in IPFIX Data Records sent to certain Collectors. Network operators should take care that the only MIB objects that are included in IPFIX Data Records are objects that the receiving Collector is allowed to receive. Note that multiple users may have access to the data from the Collector. When exporting MIB objects that may be considered sensitive or vulnerable in some network environments (as mentioned in the Security Considerations section of the RFC containing the MIB module), the Exporter should consider using anonymization techniques per if the information is anonymizable. Consumers of exported data should therefore be able to handle the kinds of data modifications that are described in .

New IPFIX semantics have been allocated in IANA's IPFIX registry per Section 6 of , as defined in the subsections below.

An integral value reporting the value of a counter, identical to the Counter32 and Counter64 semantics in , as determined by the Field Length. This is similar to IPFIX's totalCounter semantic, except that total counters have an initial value of 0 but SNMP counters do not. IANA has assigned value 7 to snmpCounter.

An integral value identical to the Gauge32 semantic in and the Gauge64 semantic in , as determined by the Field Length. IANA has assigned value 8 to snmpGauge.

The new Information Elements in have been allocated in IANA's IPFIX registry , as defined in the subsections below. In each case, the "Units" and "Range" have been left blank, since these are not applicable. ElementId Name 434mibObjectValueInteger 435mibObjectValueOctetString 436mibObjectValueOID 437mibObjectValueBits 438mibObjectValueIPAddress 439mibObjectValueCounter 440mibObjectValueGauge 441mibObjectValueTimeTicks 442mibObjectValueUnsigned 443mibObjectValueTable 444mibObjectValueRow 445mibObjectIdentifier 446mibSubIdentifier 447mibIndexIndicator 448mibCaptureTimeSemantics 449mibContextEngineID 450mibContextName 451mibObjectName 452mibObjectDescription 453mibObjectSyntax 454mibModuleName

A new Information Element "mibObjectValueInteger" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that the integer value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of Integer32 and INTEGER with IPFIX reduced&nbhy;size encoding used as required. The value is encoded as per the standard IPFIX Abstract Data Type of signed32. Abstract Data Type: signed32 Data Type Semantics: quantity ElementId: 434 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueOctetString" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that an Octet String or Opaque value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of OCTET STRING and Opaque. The value is encoded as per the standard IPFIX Abstract Data Type of octetArray. Abstract Data Type: octetArray Data Type Semantics: default ElementId: 435 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueOID" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that an Object Identifier or OID value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of OBJECT IDENTIFIER. Note: In this case, the "mibObjectIdentifier" defines which MIB object is being exported, and the "mibObjectValueOID" field will contain the OID value of that MIB object. The mibObjectValueOID Information Element is encoded as ASN.1/BER in an octetArray. Abstract Data Type: octetArray Data Type Semantics: default ElementId: 436 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueBits" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that a set of Enumerated flags or bits from a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of BITS. The flags or bits are encoded as per the standard IPFIX Abstract Data Type of octetArray, with sufficient length to accommodate the required number of bits. If the number of bits is not an integer multiple of octets, then the most significant bits at the end of the octetArray MUST be set to 0. Abstract Data Type: octetArray Data Type Semantics: flags ElementId: 437 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueIPAddress" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that the IPv4 address value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of IpAddress. The value is encoded as per the standard IPFIX Abstract Data Type of ipv4Address. Abstract Data Type: ipv4Address Data Type Semantics: default ElementId: 438 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueCounter" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that the counter value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of Counter32 or Counter64 with IPFIX reduced&nbhy;size encoding used as required. The value is encoded as per the standard IPFIX Abstract Data Type of unsigned64. Abstract Data Type: unsigned64 Data Type Semantics: snmpCounter ElementId: 439 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueGauge" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that the Gauge value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of Gauge32. The value is encoded as per the standard IPFIX Abstract Data Type of unsigned32. This value represents a non-negative integer that may increase or decrease but that shall never exceed a maximum value or fall below a minimum value. Abstract Data Type: unsigned32 Data Type Semantics: snmpGauge ElementId: 440 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueTimeTicks" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that the TimeTicks value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of TimeTicks. The value is encoded as per the standard IPFIX Abstract Data Type of unsigned32. Abstract Data Type: unsigned32 Data Type Semantics: quantity ElementId: 441 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueUnsigned" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that an unsigned integer value of a MIB object will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with the Base syntax of unsigned32 with IPFIX reduced&nbhy;size encoding used as required. The value is encoded as per the standard IPFIX Abstract Data Type of unsigned32. Abstract Data Type: unsigned32 Data Type Semantics: quantity ElementId: 442 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueTable" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that a complete or partial conceptual table will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with a syntax of SEQUENCE OF. This is encoded as a subTemplateList of mibObjectValue Information Elements. The Template specified in the subTemplateList MUST be an Options Template and MUST include all the objects listed in the INDEX clause as Scope Fields. Abstract Data Type: subTemplateList Data Type Semantics: list ElementId: 443 Status: current Reference: RFC 8038

A new Information Element "mibObjectValueRow" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that a single row of a conceptual table will be exported. The MIB Object Identifier ("mibObjectIdentifier") for this field MUST be exported in a MIB Field Option or via another means. This Information Element is used for MIB objects with a syntax of SEQUENCE. This is encoded as a subTemplateList of mibObjectValue Information Elements. The subTemplateList exported MUST contain exactly one row (i.e., one instance of the subTemplate). The Template specified in the subTemplateList MUST be an Options Template and MUST include all the objects listed in the INDEX clause as Scope Fields. Abstract Data Type: subTemplateList Data Type Semantics: list ElementId: 444 Status: current Reference: RFC 8038

A new Information Element "mibObjectIdentifier" has been allocated in IANA's IPFIX registry , with the following definition: Description: An IPFIX Information Element that denotes that a MIB Object Identifier (MIB OID) is exported in the (Options) Template Record. The mibObjectIdentifier Information Element contains the OID assigned to the MIB object type definition encoded as ASN.1/&wj;BER . Abstract Data Type: octetArray Data Type Semantics: default ElementId: 445 Status: current Reference: RFC 8038

A new Information Element "mibSubIdentifier" has been allocated in IANA's IPFIX registry , with the following definition: Description: A non-negative sub-identifier of an Object Identifier (OID). Abstract Data Type: unsigned32 Data Type Semantics: identifier ElementId: 446 Status: current Reference: RFC 8038

A new Information Element "mibIndexIndicator" has been allocated in IANA's IPFIX registry , with the following definition: Description: A set of bit fields that is used for marking the Information Elements of a Data Record that serve as INDEX MIB objects for an indexed columnar MIB object. Each bit represents an Information Element in the Data Record, with the n&nbhy;th least significant bit representing the n&nbhy;th Information Element. A bit set to 1 indicates that the corresponding Information Element is an index of the columnar object represented by the mibObjectValue. A bit set to 0 indicates that this is not the case. If the Data Record contains more than 64 Information Elements, the corresponding Template SHOULD be designed such that all index fields are among the first 64 Information Elements, because the mibIndexIndicator only contains 64 bits. If the Data Record contains less than 64 Information Elements, then the extra bits in the mibIndexIndicator for which no corresponding Information Element exists MUST have the value 0 and must be disregarded by the Collector. This Information Element may be exported with IPFIX reduced&nbhy;size encoding. Abstract Data Type: unsigned64 Data Type Semantics: flags ElementId: 447 Status: current Reference: RFC 8038

A new Information Element "mibCaptureTimeSemantics" has been allocated in IANA's IPFIX registry , with the following definition: Description: Indicates when in the lifetime of the Flow the MIB value was retrieved from the MIB for a mibObjectIdentifier. This is used to indicate if the value exported was collected from the MIB closer to Flow creation or Flow export time and refers to the Timestamp fields included in the same Data Record. This field SHOULD be used when exporting a mibObjectValue that specifies counters or statistics. If the MIB value was sampled by SNMP prior to the IPFIX Metering Process or Exporting Process retrieving the value (i.e., the data is already stale) and it is important to know the exact sampling time, then an additional observationTime* element should be paired with the OID using IPFIX Structured Data . Similarly, if different MIB capture times apply to different mibObjectValue elements within the Data Record, then individual mibCaptureTimeSemantics Information Elements should be paired with each OID using IPFIX Structured Data. Values: 0  undefined 1  begin - The value for the MIB object is captured from the    MIB when the Flow is first observed 2  end - The value for the MIB object is captured from the MIB    when the Flow ends 3  export - The value for the MIB object is captured from the    MIB at export time 4  average - The value for the MIB object is an average of    multiple captures from the MIB over the observed life of    the Flow Abstract Data Type: unsigned8 Data Type Semantics: identifier ElementId: 448 Status: current Reference: RFC 8038

A new Information Element "mibContextEngineID" has been allocated in IANA's IPFIX registry , with the following definition: Description: A mibContextEngineID that specifies the SNMP engine ID for a MIB field being exported over IPFIX. Definition as per , Section 3.3. Abstract Data Type: octetArray Data Type Semantics: default ElementId: 449 Status: current Reference: RFC 8038

A new Information Element "mibContextName" has been allocated in IANA's IPFIX registry , with the following definition: Description: An Information Element that denotes that a MIB context name is specified for a MIB field being exported over IPFIX. Reference , Section 3.3. Abstract Data Type: string Data Type Semantics: default ElementId: 450 Status: current Reference: RFC 8038

A new Information Element "mibObjectName" has been allocated in IANA's IPFIX registry , with the following definition: Description: The name (called a descriptor in ) of an object type definition. Abstract Data Type: string Data Type Semantics: default ElementId: 451 Status: current Reference: RFC 8038

A new Information Element "mibObjectDescription" has been allocated in IANA's IPFIX registry , with the following definition: Description: The value of the DESCRIPTION clause of a MIB object type definition. Abstract Data Type: string Data Type Semantics: default ElementId: 452 Status: current Reference: RFC 8038

A new Information Element "mibObjectSyntax" has been allocated in IANA's IPFIX registry , with the following definition: Description: The value of the SYNTAX clause of a MIB object type definition, which may include a textual convention or sub&nbhy;typing. See . Abstract Data Type: string Data Type Semantics: default ElementId: 453 Status: current Reference: RFC 8038

A new Information Element "mibModuleName" has been allocated in IANA's IPFIX registry , with the following definition: Description: The textual name of the MIB module that defines a MIB object. Abstract Data Type: string Data Type Semantics: default ElementId: 454 Status: current Reference: RFC 8038

&RFC2119; &RFC2578; &RFC2856; &RFC3411; &RFC6526; &RFC7011; &RFC7012; IANA International Telecommunication Union &RFC2863; &RFC2982; &RFC3414; &RFC3415; &RFC3444; &RFC4022; &RFC4293; &RFC4750; &RFC4960; &RFC5102; &RFC5476; &RFC5591; &RFC5592; &RFC6235; &RFC6313; &RFC6353; Cisco Systems Inc.

The authors would like to thank Andrew Johnson for his collaboration on the first draft version of this document, and to thank Andrew Feren and Brian Trammell for their detailed reviews. Juergen Schoenwaelder was partly funded by Flamingo, a Network of Excellence project (ICT-318488) supported by the European Commission under its Seventh Framework Programme.