IPFIX Working Group A. Kobayashi Internet-Draft NTT PF Lab. Intended status: Informational B. Claise Expires: January 14, 2010 Cisco Systems, Inc. K. Ishibashi NTT PF Lab. July 13, 2009 IPFIX Mediation: Framework draft-ietf-ipfix-mediators-framework-03 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. 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The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 14, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the Kobayashi, et al. Expires January 14, 2010 [Page 1] Internet-Draft IPFIX Mediation Framework July 2009 document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Kobayashi, et al. Expires January 14, 2010 [Page 2] Internet-Draft IPFIX Mediation Framework July 2009 Abstract This document describes a framework for IPFIX Mediation. This framework details the IPFIX Mediation reference model and the components of an IPFIX Mediator. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology and Definitions . . . . . . . . . . . . . . . . . 5 3. IPFIX/PSAMP Documents Overview . . . . . . . . . . . . . . . . 8 3.1. IPFIX Documents Overview . . . . . . . . . . . . . . . . . 8 3.2. PSAMP Documents Overview . . . . . . . . . . . . . . . . . 8 4. IPFIX Mediation Reference Model . . . . . . . . . . . . . . . 9 5. IPFIX Mediator Components . . . . . . . . . . . . . . . . . . 14 5.1. Collecting Process . . . . . . . . . . . . . . . . . . . . 14 5.2. Exporting Process . . . . . . . . . . . . . . . . . . . . 14 5.3. Intermediate Process . . . . . . . . . . . . . . . . . . . 14 5.3.1. Intermediate Selection Process . . . . . . . . . . . . 14 5.3.2. Intermediate Aggregation Process . . . . . . . . . . . 15 5.3.3. Intermediate Anonymization Process . . . . . . . . . . 16 5.3.4. Intermediate Correlation Process . . . . . . . . . . . 17 5.3.5. Data Record Expiration . . . . . . . . . . . . . . . . 18 5.4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.4.1. Component Combination Examples . . . . . . . . . . . . 19 5.4.2. Overview Example . . . . . . . . . . . . . . . . . . . 21 6. Specific IPFIX Mediators . . . . . . . . . . . . . . . . . . . 23 7. Encoding for IPFIX Message Header . . . . . . . . . . . . . . 25 8. Information Model . . . . . . . . . . . . . . . . . . . . . . 26 9. Security Considerations . . . . . . . . . . . . . . . . . . . 27 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 11.1. Normative References . . . . . . . . . . . . . . . . . . . 29 11.2. Informative References . . . . . . . . . . . . . . . . . . 29 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 32 Kobayashi, et al. Expires January 14, 2010 [Page 3] Internet-Draft IPFIX Mediation Framework July 2009 1. Introduction IPFIX Mediation covers two classes of mediation: content mediation for traffic data and transport mediation for transport protocols. Content mediation has several manipulations for a sequence of records, e.g., aggregation, correlation, filtering, or modification. Transport mediation converts other transmitting protocols into IPFIX. The motivation for the IPFIX Mediation standard comes from the need for a countermeasure to IP traffic growth, a multipurpose traffic measurement, and a heterogeneous environment, as described in detail in [IPFIX-MD-PS]. This document provides a high-level description of an IPFIX Mediator's key components and their functions. This document is structured as follows: section 2 describes the terminology used in this document, section 3 gives an IPFIX/PSAMP document overview, section 4 describes a high-level reference model, section 5 describes components and functional features located in an IPFIX Mediator, section 6 describes the component models in specific IPFIX Mediator types, section 7 describes consideration points of encoding for IPFIX Message Headers, and section 8 describes the Information Elements used in an IPFIX Mediator. Kobayashi, et al. Expires January 14, 2010 [Page 4] Internet-Draft IPFIX Mediation Framework July 2009 2. Terminology and Definitions The terms in this section are in line with those in the IPFIX Protocol specifications [RFC5101] and the PSAMP specification document [RFC5476]. The terms Observation Point, Observation Domain, Flow Key, Flow Record, Data Record, Exporting Process, Exporter, IPFIX Device, Collecting Process, Collector, IPFIX Message, Metering Process, Transport Session, Information Element, and Template Withdrawal Message are defined in the IPFIX protocol specifications [RFC5101]. The terms Packet Report, Sampling, Filtering, PSAMP Device, and Configured Selection Fraction are defined in the PSAMP specification document [RFC5476]. Furthermore, new terminology to be used in the context of IPFIX Mediation is defined in this section. All the words in these terms are started with a capital letter in this document. In this document, we use the generic term "Data Records" for IPFIX Flow Records, PSAMP Packet Reports, and Data Records defined by Options Templates, unless an explicit distinction is required. Transport Session Information The Transport Session is specified in [RFC5101]. In SCTP, the Transport Session Information is the SCTP association. In TCP and UDP, the Transport Session Information corresponds to a 5-tuple {Exporter IP address, Collector IP address, Exporter transport port, Collector transport port, and transport protocol}. Original Exporter An Original Exporter is an IPFIX Device that hosts the Observation Points where the metered IP packets are observed. IPFIX Mediation IPFIX Mediation is the manipulation and conversion of records for subsequent export using IPFIX, by applying mediation functions to a stream of records. The following terms are used in this document to describe the architectural entities used by IPFIX Mediation. Intermediate Process An Intermediate Process takes a sequence of records from a Collecting Process, Metering Process, IPFIX File Reader, or another Intermediate Process; performs some transformation on these records based upon the content of the records themselves, Kobayashi, et al. Expires January 14, 2010 [Page 5] Internet-Draft IPFIX Mediation Framework July 2009 keeps state across multiple records, configuration parameters, or other data; and passes a sequence of transformed records on to an Exporting Process, IPFIX File Writer, or another Intermediate Process. Typically, an Intermediate Process is hosted by an IPFIX Mediator. Alternatively, an Intermediate Process may be hosted by an Original Exporter. This document describes specific Intermediate Processes below. However, this is not an exhaustive list. Intermediate Aggregation Process An Intermediate Aggregation Process is an Intermediate Process that aggregates records based upon a set of Flow Keys or functions applied to fields from the record (e.g., binning, subnet aggregation). Intermediate Correlation Process An Intermediate Correlation Process is an Intermediate Process which adds information to records, noting correlations among them, or generates new records with correlated data from multiple records (e.g., the production of bidirectional flow records from unidirectional flow records). Intermediate Selection Process An Intermediate Selection Process is an Intermediate Process that selects records from a sequence based upon criteria evaluated record values and passes only those records that match the criteria (e.g., filtering only records from a given network to a given Collector). Intermediate Anonymization Process An Intermediate Anonymization Process is an Intermediate Process that transforms records in order to anonymize them, to protect the identity of the entities described by the records (e.g., by applying prefix-preserving pseudonymization of IP addresses). IPFIX Mediator An IPFIX Mediator is an IPFIX Device that provides mediation capabilities by receiving records from some data source, hosting zero or more Intermediate Processes to transform those records, and exporting those records in IPFIX Messages via an Exporting Process. In the common case, an IPFIX Mediator receives records from a Collecting Process but could also receive records from data Kobayashi, et al. Expires January 14, 2010 [Page 6] Internet-Draft IPFIX Mediation Framework July 2009 sources not encoded using IPFIX, e.g., in the case of NetFlow V9 protocol translation. Specific types of IPFIX Mediators are defined below. IPFIX Proxy An IPFIX Proxy is an IPFIX Mediator that relays incoming IPFIX Messages or messages in other protocols to one or more Collectors. It can provide transport protocol mediation and re-encoding. IPFIX Concentrator An IPFIX Concentrator is an IPFIX Mediator that receives data from one or more Exporters and sends them to a single Collector, optionally transforming the records using zero or more Intermediate Processes on the way. IPFIX Distributor An IPFIX Distributor is an IPFIX Mediator that receives data from one or more Exporters and sends them to one or more Collectors, deciding which Collector(s) to send each record to based upon the decision of an Intermediate Process. IPFIX Masquerading Proxy An IPFIX Masquerading Proxy is an IPFIX Mediator that receives data from one or more Exporters and sends them to a single Collector, using one or more Intermediate Processes to screen out parts of records according to configured policies, in order to protect the privacy of the network's end users or sensitive data of the exporting organization. Kobayashi, et al. Expires January 14, 2010 [Page 7] Internet-Draft IPFIX Mediation Framework July 2009 3. IPFIX/PSAMP Documents Overview 3.1. 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 from an IPFIX Exporting Process to a Collecting Process is defined in [RFC5470], per the requirements defined in [RFC3917]. The IPFIX protocol [RFC5101] specifies how IPFIX Data Records and Templates are carried via a number of transport protocols from IPFIX Exporting Processes to IPFIX Collecting Processes. IPFIX has a formal description of IPFIX Information Elements, their names, types, and additional semantic information, as specified in [RFC5102]. [IPFIX-MIB] specifies the IPFIX Management Information Base. Finally, [RFC5472] describes what types of applications can use the IPFIX protocol and how they can use the information provided. It furthermore shows how the IPFIX framework relates to other architectures and frameworks. The storage of IPFIX Messages in a file is specified in [IPFIX-FILE]. 3.2. PSAMP Documents Overview The framework for packet selection and reporting [RFC5474] enables network elements to select subsets of packets by statistical and other methods and to export a stream of reports on the selected packets to a Collector. The set of packet selection techniques (sampling, filtering, and hashing) standardized by PSAMP is described in [RFC5475]. The PSAMP protocol [RFC5476] specifies the export of packet information from a PSAMP Exporting Process to a Collector. Like IPFIX, PSAMP has a formal description of its Information Elements, their names, types, and additional semantic information. The PSAMP information model is defined in [RFC5477]. [PSAMP-MIB] describes the PSAMP Management Information Base. Kobayashi, et al. Expires January 14, 2010 [Page 8] Internet-Draft IPFIX Mediation Framework July 2009 4. IPFIX Mediation Reference Model The figure below shows the high-level IPFIX Mediation component model based on [RFC5470]. This figure covers the various possible scenarios that can exist in an IPFIX measurement system. +---------------------------+ +---------------------------+ | Collector 1 | | Collector N | |[Collecting Process(es)] |....|[Collecting Process(es)] | +---------------------------+ +---------------------------+ ^ ^ ^ ^ | | | | | +------....----+ | | | | IPFIX (Data Records) | | | +----------------+----+-----+ +-------+-------------------+ |IPFIX Mediator 1 | |IPFIX Mediator N | |[Exporting Process(es)] | |[Exporting Process(es)] | |[Intermediate Process(es)] |....|[Intermediate Process(es)] | |[Collecting Process(es)] | |[Collecting Process(es)] | +---------------------------+ +---------------------------+ ^ ^ ^ | | | | +------....-----+ | | IPFIX (Data Records) | | +----------------+----------+ +----+----------------------+ |IPFIX Original Exporter 1 | |IPFIX Original Exporter N | |[Exporting Process(es)] | |[Exporting Process(es)] | |[Metering Process(es)] |....|[Metering Process(es)] | |[Observation Point(s)] | |[Observation Point(s)] | +---------------------------+ +---------------------------+ ^ ^ ^ ^ | | | | Packets coming to Observation Points Figure A: IPFIX Mediation Component Model Overview. The functional components within each device are indicated within brackets []. Kobayashi, et al. Expires January 14, 2010 [Page 9] Internet-Draft IPFIX Mediation Framework July 2009 The figure below shows the basic IPFIX Mediator component model. An IPFIX Mediator is defined as consisting of one or more Collecting Processes, zero or more Intermediate Processes, and one or more Exporting Processes. Basically, an IPFIX Mediator, i.e., IPFIX Proxy, IPFIX Masquerading Proxy, IPFIX Distributor, and IPFIX Concentrator, are composed of these components. IPFIX (Data Records) ^ ^ | +------------------------|-|---------------------+ | IPFIX Mediator | | | | | | | | .---------------------|-+-------------------. | | .----------------------+--------------------.| | | | Exporting Process(es) |' | | '----------------------^--------------------' | | | | | | .---------------------|-+-------------------. | | .----------------------+--------------------.| | | | Intermediate Process(es) |' | | '----------------------^--------------------' | | | | | | .---------------------|-+-------------------. | | .----------------------+--------------------.| | | | Collecting Process(es) |' | | '----------------------^--------------------' | +------------------------|-|---------------------+ | IPFIX (Data Records) Figure B: Basic IPFIX Mediator Component Model. Kobayashi, et al. Expires January 14, 2010 [Page 10] Internet-Draft IPFIX Mediation Framework July 2009 In another case, an IPFIX Mediator, i.e., IPFIX Proxy, receives traffic records from other transmitting protocols, e.g., NetFlow. This document does not make any particular assumption on how traffic records are transferred to an IPFIX Mediator regardless of whether the traffic record is flow-based or packet-based. The figure below shows the IPFIX Mediator component model in the case of IPFIX protocol conversion. IPFIX (Data Records) ^ ^ | +------------------------|-|---------------------+ | IPFIX Mediator | | | | .---------------------|-+-------------------. | | .----------------------+--------------------.| | | | Exporting Process(es) |' | | '----------------------^--------------------' | +------------------------|-----------------------+ | Traffic record +------------------------|-----------------------+ | +-------------+----------+ | |.---------+-----------. .---------+-----------.| || Observation Point 1 |..| Observation Point N || |'---------^-----------' '---------^-----------'| +----------|------------------------|------------+ | | Packets coming to Observation Points Figure C: IPFIX Mediator Component Model in IPFIX Protocol Conversion. Kobayashi, et al. Expires January 14, 2010 [Page 11] Internet-Draft IPFIX Mediation Framework July 2009 An Intermediate Process hosted in an Original Exporter receives Data Records from IPFIX Metering Processes or PSAMP Metering Processes. An Original Exporter with IPFIX Mediation is modeled as follows. IPFIX (Data Records) ^ ^ +---------------------------|-|------------------------+ | Original Exporter | | | | | | | | .---------------------|-+-------------------. | | .----------------------+--------------------.| | | | Exporting Process(es) |' | | '----------------------^--------------------' | | | | | | .---------------------|-+-------------------. | | .----------------------+--------------------.| | | | Intermediate Process(es) |' | | '---------^-----------------------^---------' | | | Data Records | | | .----------+---------. .---------+----------. | | | Metering Process 1 |...| Metering Process N | | | '----------^---------' '---------^----------' | | | | | | .------------+--------. .---------+-----------. | | | Observation Point 1 |...| Observation Point N | | | '------------^--------' '---------^-----------' | +--------------|-----------------------|---------------+ | | Packets coming to Observation Points Figure D: IPFIX Mediation Component Model at Original Exporter. Kobayashi, et al. Expires January 14, 2010 [Page 12] Internet-Draft IPFIX Mediation Framework July 2009 An Intermediate Process may be hosted with an IPFIX File Reader and/or Writer. The following figure shows an IPFIX Mediation component model with an IPFIX File Writer and/or Reader. IPFIX (Data Records) ^ ^ | .----------------------|-+--------------------. .-----------------------+---------------------.| | Exporting Process(es) / IPFIX File Writer |' '-----------------------^---------------------' | | .----------------------|-+--------------------. .-----------------------+---------------------.| | Intermediate Process(es) |' '-----------------------^---------------------' | | .----------------------|-+--------------------. .-----------------------+---------------------.| | Collecting Process(es) / IPFIX File Reader |' '-----------------------^---------------------' | IPFIX (Data Records) Figure E: IPFIX Mediation Component Model with IPFIX File Writer/ Reader. Kobayashi, et al. Expires January 14, 2010 [Page 13] Internet-Draft IPFIX Mediation Framework July 2009 5. IPFIX Mediator Components This section describes IPFIX Mediator Components along with examples. 5.1. Collecting Process A Collecting Process, described in [RFC5101], receives Data Records with information relating to their treatment in the Metering Process and the Exporting Process in an Original Exporter, e.g., sampling parameters, IPFIX Message header information, and Transport Session Information. The Collecting Process transmits the set of data to one or more components: Intermediate Processes, Exporting Process, and some applications. In other words, a Collecting Process may duplicate received Data Records and transmit them to one or more components in sequence or in parallel. 5.2. Exporting Process An Exporting Process, described in [RFC5101], sends Data Records in the form of IPFIX Messages to one or more Collectors. The Exporting Process also needs to send subsidiary information (e.g., sampling parameters and a set of Flow Keys) in the form of a Data Record when receiving records from other transmitting protocols as well. 5.3. Intermediate Process An Intermediate Process is a key process for content mediation and generates new sets of Data Records or entire IPFIX Messages from input records with context information (e.g., "Export Time" and "Observation Domain ID"). In the case of a combination of Intermediate Processes, the output data from one Intermediate Process forms the input data for the succeeding Intermediate Process. The following subsections show the different specific Intermediate Process details. 5.3.1. Intermediate Selection Process An Intermediate Selection Process selects records; this is analogous to the PSAMP Selection Process described in [RFC5475]. The difference is that the Intermediate Selection Process takes received records, regardless of whether they are Flow Records or Packet Reports, rather than observed packets. In the case of filtering, an Intermediate Selection Process determines which input records are selected by matching them under a filtering policy and then transmits them to other components. Kobayashi, et al. Expires January 14, 2010 [Page 14] Internet-Draft IPFIX Mediation Framework July 2009 5.3.2. Intermediate Aggregation Process An Intermediate Aggregation Process creates aggregated Flow Records from input records and then transmits them to other components. There are three types of aggregation into this process. Flow Key Field Selection The Intermediate Aggregation Process gathers records within a given interval time and then merges records that have the same values of given Flow Key fields. Decreasing the number of Flow Key fields in aggregation results in more aggregated Flow Records being created. If the input Flow Records include the "flowKeyIndicator" field described in [RFC5102], the Intermediate Aggregation Process needs to modify its value. In addition, the Intermediate Aggregation Process can create statistical data and subsidiary information related to a set of aggregated Flow Records. Examples include the given interval time, a new set of Flow Keys, and the number of input Data Records belonging to an aggregated Flow Record. Time Composition Time composition is defined as aggregation of Data Records within a given interval time without changing their Flow Key(s). The Intermediate Aggregation Process may also compute Data Records statistics, such as maximum and minimum values of per-flow counters. The Time Composition provides some advantages. * reducing the number of Flow Records for long-running Flows * computing the active time period for long-running Flows * revealing the time series behavior of traffic volume within an active time Short period Flow Records created at a Metering Process by configuring a short active time, e.g., 1 or 10 sec, are merged at an Intermediate Aggregation Process within a certain time period, e.g., 60 or 300 sec. While merging, the Intermediate Aggregation Process computes new metrics such as the maximum and minimum. It produces more precise maximum and minimum values without increasing the number of Flow Records on a Collector. When some traffic requires timely traffic monitoring and other traffic does not, a combination of the Intermediate Selection Process and Intermediate Aggregation Process is useful, as described in section 5.4. Kobayashi, et al. Expires January 14, 2010 [Page 15] Internet-Draft IPFIX Mediation Framework July 2009 Space Composition Space composition is defined as aggregation on a larger Observation Domain or across a set of Observation Points or Observation Domains. Generally, Flow Key fields are included in a Data Record. In that case, other properties that are not included in a Data Record, such as the Exporter IP address or Observation Domain ID, may be Flow Key fields. As another approach, an identifier indicating a spatial Observation Domain can also become a new Flow Key. For example, an identifier indicates an area on an ISP network or a link aggregation interface composed of some physical interfaces. The identifier also makes a relation to a set of values of a specified field in the input Data Records by the configuring rule. After converting the values of the specified field to the identifier, the Intermediate Aggregation Process can create aggregated Flow Records by a general aggregation process by using the identifier as a Flow Key field. 5.3.3. Intermediate Anonymization Process An Intermediate Anonymization Process modifies the value of specified fields or screens out specified fields without changing their Flow Key(s). The Intermediate Anonymization Process also needs to modify the value of the "flowKeyIndicator" when modifying the data structure of an incoming Template. Deleting specified fields The Intermediate Anonymization Process deletes existing fields in accordance with instruction rules, which indicate whether a specified Information Element should be deleted. Applicable examples include hiding network topology information and private information. In the case of feeding Data Records to end customers, the Intermediate Anonymization Process avoids disclosing vulnerabilities by deleting fields, e.g., "ipNextHopIP{v4|v6}Address", "bgpNextHopIP{v4|v6}Address", "bgp{Next|Prev}AdjacentAsNumber", and "mplsLabelStackSection", described in [RFC5102]. Anonymizing value of specified fields The Intermediate Anonymization Process modifies the value of specified fields. Kobayashi, et al. Expires January 14, 2010 [Page 16] Internet-Draft IPFIX Mediation Framework July 2009 Applicable examples include anonymizing customers' private information, such as IP address and port number, in accordance with a privacy protection policy. The Intermediate Anonymization Process may also report anonymized fields and the anonymization method as subsidiary information. 5.3.4. Intermediate Correlation Process An Intermediate Correlation Process creates new metrics, counters, attributes, or packet property parameters by evaluating the correlation among sets of Data Records or among Data Records and other meta data after gathering sets of Data Records during a given interval time. After producing new values, the Intermediate Correlation Process adds new fields to the Data Records or creates a new Data Record. The Intermediate Correlation Process also needs to modify the value of the "flowKeyIndicator" when modifying the data structure of an incoming Template. The Intermediate Correlation Process indicates a special case of the Intermediate Aggregation Process. Typical examples are as follows: o One-to-one correlation between Data Records * One way delay, Packet delay variation in [RFC5481] The Intermediate Correlation Process gathers a pair of Packet Reports exported from different Exporters indicating the same packet. The metrics follow from the correlation of the timestamp value on both of the Packet Reports. * Packet inter-arrival time or jitter The Intermediate Correlation Process gathers consecutive Packet Reports exported from an Exporter. * Rate-limiting ratio, compression ratio, optimization ratio, etc. The data values follow from the correlation of Data Records within a single Flow observed on the incoming/outgoing points of a WAN interface. o Correlation amongst Data Records * Average/maximum/minimum packets, bytes, one way delay, packet loss, etc. The data values follow from the correlation of multiple Data Records while the Intermediate Aggregation Process executes. o Correlation between Data Record and other meta data Typical examples are derived packet property parameters described Kobayashi, et al. Expires January 14, 2010 [Page 17] Internet-Draft IPFIX Mediation Framework July 2009 in [RFC5102]. The parameters are retrieved from a database etc. based on the value of the specified field in an input Data Record. Doing that can compensate for traditional exporting devices or probes that are unable to add packet property parameters. Therefore, Collectors do not need to recognize the difference among implementations of routers from several vendors or among Exporter types, such as router, switch, or probe. Typical derived packet property parameters are as follows: * "bgpNextHop{IPv4|IPv6}Address" described in [RFC5102] The address indicates the egress router of a network domain. That is useful for making a traffic matrix that covers the whole network domain. * BGP Communities attribute The attribute indicates tagging for routes of geographical and topological information and source type (e.g., transit, peer, or customer) as described in [RFC4384]. Therefore, network administrators can monitor the geographically-based or source type-based traffic volume by correlating the attribute. * "mplsVpnRouteDistinguisher" described in [RFC5102] The value indicates the VPN customer's identification, which cannot be extracted from the core router in MPLS networks. Therefore, network administrators can monitor the customer- based traffic volume on even core routers. 5.3.5. Data Record Expiration An Intermediate Aggregation Process and an Intermediate Correlation Process need to have expiration conditions to export cached Data Records. In the case of the Metering Process in an Original Exporter, these conditions are described in [RFC5470]. In the case of the Intermediate Process, these conditions are as follows. o If there are no input Data Records belonging to a cached Flow for a certain time period, aggregated Flow Records will expire. This time period should be configurable at the Intermediate Process. o If the Intermediate Process experiences resource constraints, aggregated Flow Records may prematurely expire (e.g., lack of memory to store Flow Records). o For long-running Flows, the Intermediate Process should cause the Flow to expire on a regular basis or on the basis of an expiration policy. This periodicity or expiration policy should be configurable at the Intermediate Process. Kobayashi, et al. Expires January 14, 2010 [Page 18] Internet-Draft IPFIX Mediation Framework July 2009 The Intermediate Correlation Process has special cases. Cached Data Records may be discarded when they prematurely expire and the Intermediate Correlation Process cannot compute their correlation. For example, an Intermediate Correlation Process computing one way delay may discard the cached Packet Report due to computation failure when receiving one Packet Report and not receiving another Packet Report until expiration of the cached Data Record. 5.4. Examples 5.4.1. Component Combination Examples The combination of some components (Intermediate Process, Exporting Process, Collecting Process, IPFIX File Writer and Reader) provides useful applications. This subsection describes examples as follows. Data-based Collector Selection The combination of one or more Intermediate Selection Processes and Exporting Processes can determine to which Collector input Data Records are exported. Applicable examples include exporting Data Records to a dedicated Collector on the basis of customer or organization peering. For example, an Intermediate Selection Process selects Data Records on the basis of the peering autonomous system number, and an Exporting Process sends them to a dedicated Collector, as shown in the following figure. .----------------------. .------------. | Intermediate | | Exporting | | Selection Process 1 | | Process 1 | +--+--- Peering AS #10 ---+-->| +--> Collector 1 | '----------------------' '------------' | .----------------------. .------------. Data | | Intermediate | | Exporting | Record | | Selection Process 2 | | Process 2 | -------+--+--- Peering AS #20 ---+-->| +--> Collector 2 | '----------------------' '------------' | .----------------------. .------------. | | Intermediate | | Exporting | | | Selection Process 3 | | Process 3 | +--+--- Peering AS #30 ---+-->| +--> Collector 3 '----------------------' '------------' Figure F: Data-based Collector Selection Example. Kobayashi, et al. Expires January 14, 2010 [Page 19] Internet-Draft IPFIX Mediation Framework July 2009 Flow Selection and Aggregation The combination of one or more Intermediate Selection Processes and Intermediate Aggregation Processes can efficiently reduce the amount of Flow Records. For example, an Intermediate Selection Process selects small Flows consisting of a small number of packets and then transmits them to an Intermediate Aggregation Process. Another Intermediate Selection Process selects other Flow Records and then transmits them to an Exporting Process, as shown in the following figure. This results in aggregation on the basis of the distribution of the number of packets per Flow. .------------------. .--------------. .------------. | Intermediate | | Intermediate | | Exporting | | Selection | | Aggregation | | Process | | Process 1 | | Process | | | +-+ packetDeltaCount +->| +->| | | | <= 5 | | | | | Data | '------------------' '--------------' | | Record | .------------------. | | -------+ | Intermediate | | | | | Selection | | | | | Process 2 | | | +-+ packetDeltaCount +------------------->| | | > 5 | | | '------------------' '------------' Figure G: Flow Selection and Aggregation Example. IPFIX File Writer/Reader The IPFIX File Writer/Reader on an IPFIX Mediator also complies with [IPFIX-FILE]. The IPFIX File Writer stores input Data Records from any process in a file system. When input Data Records include irrelevant Information Elements, an Intermediate Anonymization Process can delete these fields before the IPFIX File Writer handles them, as shown in the following figure. .---------------. .---------------. .-------------. | Collecting | | Intermediate | | IPFIX | IPFIX | Process | | Anonymization | | File | ----->| +->| Process +->| Writer | '---------------' '---------------' '-------------' Figure H: IPFIX Mediation Example with IPFIX File Writer. In contrast, the IPFIX File Reader retrieves stored Data Records when administrators want to retrieve past Data Records from a given time period. If the data structure of output Data Records from Kobayashi, et al. Expires January 14, 2010 [Page 20] Internet-Draft IPFIX Mediation Framework July 2009 the IPFIX File Reader is different from what administrators want, an Intermediate Anonymization Process and Intermediate Correlation Process can modify the data structure, as shown in the following figure. .-------------. .---------------. .---------------. .-----------. | IPFIX | | Intermediate | | Intermediate | | Exporting | | File | | Anonymization | | Correlation | | Process | | Reader +->| Process +->| Process +->| | '-------------' '---------------' '---------------' '-----------' Figure I: IPFIX Mediation Example with IPFIX File Reader. 5.4.2. Overview Example As an example in the case of the IPFIX Mediator having different Intermediate Process types, a Collecting Process/IPFIX File Reader replicates Data Records, if necessary, and transmits them to a suitable Intermediate Process/Exporting Process. An example figure is shown below. Kobayashi, et al. Expires January 14, 2010 [Page 21] Internet-Draft IPFIX Mediation Framework July 2009 IPFIX IPFIX IPFIX ^ ^ ^ | | | .------------. .-----+-------. .-----+-------. .------+------. | IPFIX File | | Exporting | | Exporting | | Exporting | | Writer | | Process 1 | | Process 2 |....| Process N | '-----^-^----' '-----^-------' '-----^-------' '------^------' | | | | | | +-------------+ | | : Flow Records / Packet Reports : .------+-------. .-----+--------. .----+---------. | | Intermediate | | Intermediate | | Intermediate | | | Anonymization| | Correlation | | Aggregation | | | Process N | | Process N | | Process N | | '------|-------' '------|-------' '-----|-|------' | | +---------------+ | | : : : : .------+-------. .------+-------. .-------+------. | | Intermediate | | Intermediate | | Intermediate | | | Selection | | Selection | | Selection | | | Process 1 | | Process 2 | | Process 3 | | '------|-|-----' '------|-------' '-----|--------' | | +--------------+ | +----------------+ | | | | | : Flow Records / Packet Reports : .------+------. .-------+-----. .-----+-+-----. .-----+------. | Collecting | | Collecting | | Collecting | | IPFIX File | | Process 1 | | Process 2 |...| Process N | | Reader | '------^------' '------^------' '------^------' '------------' | | | IPFIX IPFIX IPFIX Figure J: IPFIX Mediation Functional Block Examples. Kobayashi, et al. Expires January 14, 2010 [Page 22] Internet-Draft IPFIX Mediation Framework July 2009 6. Specific IPFIX Mediators This document intends to avoid constraining the component models of IPFIX Mediators. However, typical component models of specific IPFIX Mediators can be expected. This section describes the component models of the specific types to elaborate the framework of IPFIX Mediation. The figure below shows the component models in each specific type. Specific IPFIX Mediators are composed of the following components: Collecting Process (C), Intermediate Process (I), and Exporting Process (E). The components within brackets [] indicate that there are zero or more hosted. The components without brackets indicate one or more. +------> --->-----+ +------> +----------+--+ +--+-------+--+ --->--+-[C]------E--+---> --->--+--C---I---E--+---> +----------+--+ +--+-------+--+ +------> --->-----+ +------> IPFIX Proxy IPFIX Distributor --->-----+ --->-----+ +--+----------+ +--+----------+ --->--+--C--[I]--E--+---> --->--+--C---I---E--+---> +--+----------+ +--+----------+ --->-----+ --->-----+ IPFIX Concentrator IPFIX Masquerading Proxy Figure K: Component Models in Specific IPFIX Mediators. Kobayashi, et al. Expires January 14, 2010 [Page 23] Internet-Draft IPFIX Mediation Framework July 2009 Below is a summary table for specific IPFIX Mediator types. The abbreviation "IP" stands for Intermediate Process. +--------------+------------+---------------+---------------------+ Mediator Type Number of IP Type Number of IPFIX hosted IPs Transport Sessions +==============+============+===============+=====================+ Proxy zero incoming: zero(*) or one outgoing: one or more +--------------+------------+---------------+---------------------+ Distributor one or more Selection incoming: one or more outgoing: one or more +--------------+------------+---------------+---------------------+ Concentrator zero or more Aggregation incoming: one or more Correlation outgoing: one +--------------+------------+---------------+---------------------+ Masquerading one or more Anonymization incoming: one or more Proxy outgoing: one +--------------+------------+---------------+---------------------+ (*) When an IPFIX Proxy converts IPFIX from other protocols. Figure L: IPFIX Mediator Type Summary Table. An IPFIX Proxy or an IPFIX Concentrator manipulates incoming IPFIX Messages without hosting an Intermediate Process when executing transport mediation (e.g., converting NetFlow into IPFIX). In that case, IPFIX Mediators manage the mapping information about Transport Sessions, Observation Domain IDs, and Template IDs on the incoming/ outgoing sides. Kobayashi, et al. Expires January 14, 2010 [Page 24] Internet-Draft IPFIX Mediation Framework July 2009 7. Encoding for IPFIX Message Header This section describes consideration points of encoding for the IPFIX Message Header. The IPFIX Message Header described in [RFC5101] includes Export Time, Sequence Number, and Observation Domain ID fields. Following are some consideration points: Export Time An IPFIX Mediator sets the Export Time in two ways: * Case 1: keeping the field value of incoming Transport Sessions * Case 2: setting the time at which an IPFIX Message leaves the IPFIX Mediator In case 2, the IPFIX Mediator needs to handle any delta time stamp fields, such as "flowStartDeltaMicroseconds" and "flowEndDeltaMicroseconds", described in [RFC5102]. Sequence Number In the case of an IPFIX Proxy relaying a one-to-one Transport Session, the IPFIX Proxy needs to handle the Sequence Number value when the incoming Transport Session shuts down and starts. Observation Domain ID An IPFIX Mediator can set the Observation Domain ID independently of the incoming Observation Domain ID. There are two consideration points: * Case 1: relaying an IPFIX Message after replacing each incoming Observation Domain ID with a new value in case of an IPFIX Proxy and an IPFIX Concentrator * Case 2: aggregating incoming Flow Records in case of an IPFIX Concentrator In case 1, an IPFIX Mediator needs to set the appropriate scope fields in Data Records defined in Options Template Records when the incoming Observation Domain IDs used as the scope fields. In case 2, according to the description of [RFC5101], an IPFIX Concentrator needs to set a value of 0 for the Observation Domain ID. In that case, the IPFIX Concentrator can add new field to Flow Record instead of the Observation Domain ID. The field indicates the largest set of Observation Points for aggregated Flow Record. Kobayashi, et al. Expires January 14, 2010 [Page 25] Internet-Draft IPFIX Mediation Framework July 2009 8. Information Model IPFIX Mediation reuses the general information models from [RFC5102] and [RFC5477]. However, several Intermediate Processes would require additional Information Elements as follows: o Number of input Data Records belonging to output aggregated Flow Records o New observation domain information instead of Observation Domain ID in IPFIX Concentrator o Maximum and minimum values for packet count and octet count o Some metrics related to network performance, e.g., one way delay, and packet inter-arrival time, etc. o Anonymization method and report on the anonymized fields o Report on the applied treatment items in IPFIX Mediation Kobayashi, et al. Expires January 14, 2010 [Page 26] Internet-Draft IPFIX Mediation Framework July 2009 9. Security Considerations An IPFIX measurement system must also prevent the security threats related to IPFIX Mediation that follow as well as the security threats described in the security consideration section in [RFC5101]. o Attacks against IPFIX Mediators IPFIX Mediators need to prevent unauthorized access or denial-of- service (DoS) attacks from untrusted public networks. One solution is for IPFIX Mediators to host the packet filter function to reject malicious packets at an outside interface. o Man-in-the-middle attacks by untrusted IPFIX Mediators The Collector-Mediator-Exporter structure model would increase the risk of man-in-the-middle attacks. One solution is that IPFIX Collectors and Exporters must verify trusted IPFIX Mediators to prevent connection to untrusted IPFIX Mediators. o Configuration of IPFIX Mediation In the case of IPFIX Distributors and IPFIX Masquerading Proxies, an accidental misconfiguration and unauthorized access to configuration data could lead to the crucial problem of disclosure of confidential traffic data. To eliminate these risks, IPFIX Mediators must provide the authentication function for authorized administrators and the facilities to help in tracing configuration changes to their origins. Kobayashi, et al. Expires January 14, 2010 [Page 27] Internet-Draft IPFIX Mediation Framework July 2009 10. IANA Considerations This document has no actions for IANA. Kobayashi, et al. Expires January 14, 2010 [Page 28] Internet-Draft IPFIX Mediation Framework July 2009 11. References 11.1. Normative References [RFC5101] Claise, B., "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information", January 2008. [RFC5476] Claise, B., Quittek, J., and A. Johnson, "Packet Sampling (PSAMP) Protocol Specifications", March 2009. 11.2. Informative References [IPFIX-FILE] Trammell, B., Boschi, E., Mark, L., Zseby, T., and A. Wagner, "An IPFIX-Based File Format", draft-ietf-ipfix-file-04 (work in progress) , July 2009. [IPFIX-MD-PS] Kobayashi, A., Claise, B., Nishida, H., Sommer, C., Dressler, F., and E. Stephan, "IPFIX Mediation: Problem Statement", draft-ietf-ipfix-mediation-problem-statement-03 (work in progress) , April 2009. [IPFIX-MIB] Dietz, T., Claise, B., and A. Kobayashi, "Definitions of Managed Objects for IP Flow Information Export", draft-ietf-ipfix-mib-06 (work in progress) , March 2009. [PSAMP-MIB] Dietz, T. and B. Claise, "Definitions of Managed Objects for Packet Sampling", draft-ietf-psamp-mib-06 (work in progress) , June 2006. [RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander, "Requirements for IP Flow Information Export(IPFIX)", October 2004. [RFC4384] Meyer, D., "BGP Communities for Data Collection", February 2006. [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J. Meyer, "Information Model for IP Flow Information Export", January 2008. [RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek, "Architecture for IP Flow Information Export", March 2009. Kobayashi, et al. Expires January 14, 2010 [Page 29] Internet-Draft IPFIX Mediation Framework July 2009 [RFC5472] Zseby, T., Boschi, E., Brownlee, N., and B. Claise, "IPFIX Applicability", March 2009. [RFC5474] Duffield, N., "A Framework for Packet Selection and Reporting", March 2009. [RFC5475] Zseby, T., Molina, M., Duffield, N., Niccolini, S., and F. Raspall, "Sampling and Filtering Techniques for IP Packet Selection", March 2009. [RFC5477] Dietz, T., Claise, B., Aitken, P., Dressler, F., and G. Carle, "Information Model for Packet Sampling Exports", March 2009. [RFC5481] Morton, A. and B. Claise, "Packet Delay Variation Applicability Statement", March 2009. Kobayashi, et al. Expires January 14, 2010 [Page 30] Internet-Draft IPFIX Mediation Framework July 2009 Appendix A. Acknowledgements We would like to thank the following persons: Gerhard Muenz for the thorough detail review and significant contribution regarding the improvement of whole sections; Daisuke Matsubara, Tsuyoshi Kondoh, Hiroshi Kurakami, Haruhiko Nishida for contribution during the initial phases of the document; Brian Trammel for contribution regarding the improvement of terminologies section; Nevil Brownlee, Juergen Quittek for the technical reviews and feedback. Kobayashi, et al. Expires January 14, 2010 [Page 31] Internet-Draft IPFIX Mediation Framework July 2009 Authors' Addresses Atsushi Kobayashi NTT Information Sharing Platform Laboratories 3-9-11 Midori-cho Musashino-shi, Tokyo 180-8585 Japan Phone: +81-422-59-3978 Email: akoba@nttv6.net Benoit Claise Cisco Systems, Inc. De Kleetlaan 6a b1 Diegem 1831 Belgium Phone: +32 2 704 5622 Email: bclaise@cisco.com Keisuke Ishibashi NTT Information Sharing Platform Laboratories 3-9-11 Midori-cho Musashino-shi 180-8585 Japan Phone: +81-422-59-3978 Email: ishibashi.keisuke@lab.ntt.co.jp Kobayashi, et al. Expires January 14, 2010 [Page 32]