|
Dear all, Here is my feedback. In preparation for this review, I read first the email from Paul and Gerhard. I will try not to repeat their feedback. Regards, Benoit. Add "Specifications" ? Messagedraft-ietf-ipfix-file-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 15, 2009. Abstract This document describes a file format for the storage of flow data based upon the IPFIX Message format. It proposes a set of requirements for flat-file, binary flow data file formats, then applies the IPFIX message format to these requirements to build a new
Specifications?
"IPFIX-based file format" in the abstract. " IPFIX File format" here. And new simply "file format". Maybe I should wait for the definition ;-)Files work in Section 3. It then explores the motivation for proposing a standardized flow file format and using IPFIX as the basis for this new file format in Section 4. It outlines a set of requirements for standardized flow storage in Section 5, and explores the applicability of such a format to various specific application areas in Section 6. The file format specification follows in Section 7, including <CR>?specifications of readers and writers of these files, and additional specifications that apply in specific use cases. This format makes use of the IPFIX Options mechanism for additional file metadata, in order to avoid requiring any protocol or message format extensions, and to minimize the effort required to adapt IPFIX implementations to use the file format; a detailed definition of the Options Templates used for storage metedata appears in Section 8. Section 9 and Section 10 provide specific recommendations for error resilience during long-term storage and integration of IPFIX File data with other formats. Appendix A contains a detailed example IPFIX File. 1.1. IPFIX Documents Overview "Specification of the IPFIX Protocol for the Exchange of IP Traffic Flow Information" [RFC5101] and its associated documents define the IPFIX Protocol, which provides network engineers and administrators with access to IP traffic flow information. "Architecture for IP Flow Information Export" [I-D.ietf-ipfix-arch] defines the architecture for the export of measured IP flow information out of an IPFIX Exporting Process to an IPFIX Collecting Process, and the basic terminology used to describe the elements of this architecture, per the requirements defined in "Requirements for IP Flow Information Export" [RFC3917]. [RFC5101] then covers the details of the method for transporting IPFIX Data Records and Templates via a congestion-aware transport protocol from an IPFIX Exporting Process to an IPFIX Collecting Process. "Information Model for IP Flow Information Export" [RFC5102] describes the Information Elements used by IPFIX, including details on Information Element naming, numbering, and data type encoding. Why start with "Finally" while the next section starts with "in addition"?Finally, "IPFIX Applicability" [I-D.ietf-ipfix-as] describes the I've seen several instances of "metadata". This is a confusing generic term to me. Maybe it's only me?Trammell, et al. Expires January 15, 2009 [Page 4] Internet-Draft IPFIX Files July 2008 various applications of the IPFIX protocol and their use of information exported via IPFIX, and relates the IPFIX architecture to other measurement architectures and frameworks. In addition, "Exporting Type Information for IPFIX Information Elements" [I-D.ietf-ipfix-exporting-type] specifies a method for encoding Information Model properties within an IPFIX Message stream. This document references [RFC5101] and the architecture document for terminology, defines IPFIX File Writer and IPFIX File Reader in terms of the IPFIX Exporting Processes and IPFIX Collecting Process definitions from [RFC5101], and extends the IPFIX Information Model defined in [RFC5102] to provide new Information Elements for IPFIX File metadata. Minor point. The last paragraphs contains interesting information. Maybe they're not at the right place in the section "IPFIX Documents Overview"It uses the method described in "Exporting Type Information for IPFIX Information Elements" [I-D.ietf-ipfix-exporting-type] document to support the self- description of IPFIX Files containing enterprise-specific Information Elements.
Your first sentence says: IPFIX file = stream of IPFIX Messages stored
on a filesystemYour second sentence says: IPFIX file = IPFIX Message stream There is a discrepancy.
Not sure if this is adequate to include sentences with MUST with a
definition.What about?
IPFIX File Reader: An IPFIX File Reader is a Process which reads
IPFIX Files from a filesystem. An IPFIX File Reader is analogous to an IPFIX
Collecting Process.
Ditto.remove "as defined by this document"The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this Trammell, et al. Expires January 15, 2009 [Page 5] Internet-Draft IPFIX Files July 2008 document are to be interpreted as described in [RFC2119]. 3. Design Overview An IPFIX File, as defined by this document, is simply a stream which format?containing one or more IPFIX Messages serialized to some filesystem. Though any set of valid IPFIX Messages can be serialized into an IPFIX File, the specification proposes guidelines designed to ease storage and retrieval of flow data using the format. I guess that your message is: any file metadata must be encoded in an IPFIX Message.IPFIX Files contain only IPFIX Messages; any file metadata such as checksums or export session details are stored using Options within the IPFIX Message. However, existing ones must be modified or new one created?
I had to search to see whether or not the IPFIX Message contains the
IPFIX Message Header.Maybe one extra sentence would be welcome... >From the definition only, it's not obvious. IPFIX Message
An IPFIX Message is a message originating at the Exporting Process
that carries the IPFIX records of this Exporting Process and whose
destination is a Collecting Process. An IPFIX Message is
encapsulated at the transport layer.
We have to look at figure B of RFC5101.I would remove this paragraph. Already covered.See Section 7 for details of the implementation of this design, including specific requirements and guidelines for File Readers and File Writers, and Information Elements and Options Templates used for file metadata. There is4. Motivation There are a wide variety of applications for the file-based storage Sets is confusing as it begins the sentence. Is this the definition from RFC 5101? I guess no.of IP flow data, across a continuum of time scales. Tools used in the analysis of flow data and creation of analysis products often use files as a convenient unit of work, with an ephemeral lifetime. A set of flows relevant to a security investigation may be stored in a file for the duration of that investigation, and further exchanged among incident handlers via email or within an external incident Trammell, et al. Expires January 15, 2009 [Page 7] Internet-Draft IPFIX Files July 2008 handling workflow application. Sets of flow data relevant to Data Sets?Internet measurement research may be published as files, much as libpcap packet trace files are, to provide common data sets for the or V8repeatability of research efforts; these files would have lifetimes measured in months or years. Operational flow measurement systems also have a need for long-term, archival storage of flow data, either as a primary flow data repository, or as a backing tier for online storage in a relational database management system (RDBMS). The variety of applications of flow data, and the variety of presently deployed storage approaches, would seem to indicate the need for a standard approach to flow storage with applicability across the continuum of time scales over which flow data is stored. A storage format based around flat files would best address the variety of storage requirements. While much work has been done on structured storage via RDBMS, relational database systems are not a good basis for format standardization owing to the fact that their internal data structures are generally private to a single implementation and subject to change for internal reasons. Also, there are a wide variety of operations available on flat files, and external tools and standards can be leveraged to meet file-based flow storage requirements. Further, flow data is often not very semantically complicated, and is managed in very high volume; therefore, an RDBMS-based flow storage system would not benefit much from the advantages of relational database technology. The simplest way to create a new file format is simply to serialize some internal data model to disk, with either textual or binary representation of data elements, and some framing strategy for delimiting fields and records. "Ad-hoc" file formats such as this have several important disadvantages. They impose the semantics of the data model from which they are derived on the file format, and as such, they are difficult to extend, describe, and standardize. Indeed, one de facto standard for the storage of flow data is one of these ad-hoc formats. A common method of storing data collected via Cisco NetFlow V5 or V7 is to serialize a stream of raw NetFlow and V8datagrams into files. These NetFlow PDU files consist of a collection of header-prefixed blocks (corresponding to the datagrams as received on the wire) containing fixed-length binary flow records. NetFlow V5 and V7 data may be mixed within a given file, as the Why is this important? The important message is that their format is fixed.header on each datagram defines the NetFlow version of the records following; there is indeed very little difference between the two record formats. data sets or Data Sets? What's a flow dataset?While this NetFlow PDU file format has all the disadvantages of an ad-hoc format, and is not extensible to data models other than that defined by Cisco NetFlow, it is at least reasonably well-understood due to its ubiquity. Trammell, et al. Expires January 15, 2009 [Page 8] Internet-Draft IPFIX Files July 2008 Over the past decade XML markup has emerged as a new "universal" representation format for structured data. It is intended to be human-readable; indeed, that is one reason for its rapid adoption. However XML has limited usefulness for representing network flow data. Network flow data has a simple, repetitive, non-hierarchical structure that does not benefit much from XML. An XML representation of flow data would be an essentially flat list of the attributes and their values for each flow record. The XML approach to data encoding is very heavyweight when compared to binary flow encoding. XML's use of start- and end-tags, and plain-text encoding of the actual values, leads to significant inefficiency in encoding size. Typical network flow datasets can Throughout the document, my impression is that there is a lack of consistency for some terms: data sets, flow data sets, Data Sets, .... flow, flow record, flow data, etc... file-based, IPFIX file, etc... Here is another example: flow data file formatcontain millions or billions of flows per hour of traffic represented. Any increase in storage size per record can have dramatic impact on flow data storage and transfer sizes. While data compression algorithms can partially remove the redundancy introduced by XML encoding, they introduce additional overhead of their own. A further problem is that XML processing tools require a full XML parser. XML parsers are fully general and therefore complex, resource-intensive and relatively slow, introducing significant processing time overhead for large network-flow datasets. In contrast, parsers for typical binary flow data encodings are simply structured, since they only need to parse a very small header and then have complete knowledge of all following fields for the particular flow. These can then be read in a very efficient linear fashion. This leads us to propose the IPFIX Message format as the basis for a new flow data file format. A generic comment.The IPFIX working group, in defining the IPFIX protocol, has already defined an information model and data formatting rules for representation of flow data. Especially at shorter time scales, when a file is a unit of data interchange, the filesystem may be viewed as simply another IPFIX Message transport between processes. This format is especially well suited to representing flow data, as it was designed specifically for flow data export; it is easily extensible unlike ad-hoc serialization, and compact unlike XML. In addition, IPFIX is an IETF standard for the export and collection of flow data; using a common format for storage and analysis at the collection side allows implementors to use substantially the same information model and data formatting implementation for transport as well as storage. 5. Requirements In this section, we outline a proposed set of requirements Trammell, et al. Expires January 15, 2009 [Page 9] Internet-Draft IPFIX Files July 2008 [SAINT2007] for any persistent storage format for flow data. First and foremost, a flow data file format should support storage across the continuum of time scales important to flow storage applications. Each of the requirements enumerated in the sections below is broadly applicable to flow storage applications, though each may be more important at certain time scales. For each, we first identify the requirement, then explain how the IPFIX Message format addresses it, or briefly outline the changes that must be made in order for an IPFIX-based file format to meet the requirement. 5.1. Record Format Flexibility Due to the wide variety of flow attributes collected by different network flow attribute measurement systems, the ideal flow storage format will not impose a single data model or a specific record type on the flows it stores. The file format must be flexible and extensible; that is, it must support the definition of multiple record types within the file itself, and must be able to support new field types for data within the records in a graceful way. So far in the document, you have chosen to use generic terms, not capitalized. I'm not too sure how it helps. I even think that this is confusing. What is a "field types for data" After all, you wrote a specification, which IMHO should reuse the terminology Something such as: Due to the wide variety of Flow attributes collected by different IPFIX Device, the ideal Flow storage format will not impose a single data model or a specific Record type on the flows it stores. The IPFIX File MUST be flexible and extensible; that is, it MUST support the definition of multiple Flow Records within the IPFIX File itself, and MUST be able to support new Information Elements.Now, the use of MUST versus must in the requirement section is debatable. Data Records by a Template.IPFIX provides record format flexibility through the use of Templates to describe each Data Record, through the use of an IANA Registry to define its Information Elements, and through the use of enterprise- specific Information Elements. 5.2. Self Description Archived data may be read at a time in the future where any external reference to the meaning of the data may be lost. The ideal flow storage format should be self-describing; that is, a process reading flow data from storage should be able to properly interpret the stored flows without reference to anything other than standard sources (e.g., the standards document describing the file format) and the stored flow data itself. The IPFIX Message format is partially self-describing; that is, IPFIX Templates containing only IANA-assigned Information Elements can be completely interpreted according to the IPFIX Information Model without additional external data. However, Templates containing private information elements lack detailed type and semantic information; a Collecting Process receiving data described by a template containing private Information Note: from now on, I won't make this "capitalization" comment again In this section you might want to develop on the "storage complexity"Elements it does not understand can only treat the data contained within those Information Elements as octet arrays. To be fully self- describing, enterprise-specific Information Elements must be additionally described via IPFIX Options according to the Information Element Type Options Template defined in "Exporting Type Information Trammell, et al. Expires January 15, 2009 [Page 10] Internet-Draft IPFIX Files July 2008 for IPFIX Information Elements" [I-D.ietf-ipfix-exporting-type]. 5.3. Data Compression Regardless of the representation format, flow data describing traffic on real networks tends to be highly compressible. Compression tends to improve the scalability of flow collection systems, by reducing the disk storage and I/O bandwidth requirement for a given workload. The ideal flow storage format should support applications which wish to leverage this fact by supporting compression of stored data. The IPFIX Message format has no support for data compression, as the IPFIX protocol was designed for speed and simplicity of export. Of course, any flat file is readily compressible using a wide variety of external data compression tools, formats, and algorithms; therefore, this requirement can be met externally. However, a couple of simple optimizations can be made by File Writers to increase the integrity and usability of compressed IPFIX data; these are outlined in Section 9.1. 5.4. Indexing and Searching Binary, record stream oriented file formats natively support only one form of searching, sequential scan in file order. By choosing the order of records in a file carefully (e.g., by flow start or flow end time), a file can be indexed by a single key. Beyond this, properly addressing indexing is an application-specific problem, as it inherently involves tradeoffs between storage complexity What I have in mind is the difficulty for an IPFIX Device to support the "order of records in a file" option. Based on the timeouts described in [IPFIX-ARCH], it's very difficult to do order by flow start without huge buffers or constantly inserting flow records at the right place in the file. Both options are not practical in real-time. Neither in an IPFIX device or a collector. the IPFIX specifications [RFC 5101] does not ...and retrieval speed, and requirements vary widely based on time scales and the types of queries used from site to site. However, a generic standard flow storage format may provide limited direct support for indexing and searching. The ideal flow storage format will support a limited table of contents facility noting that the records in a file contain data relating only to certain keys or values of keys, in order to keep multi-file search implementations from having to scan a file for data it does not contain. The IPFIX Message format has no direct support for indexing. However, its template mechanism and the technique described in "Reducing Redundancy in IPFIX and PSAMP Reports" [I-D.ietf-ipfix-reducing-redundancy] can be used to describe the contents of a file in a limited way. Additionally, as flow data is often sorted and divided by time, the start and end time of the flows in a file may be declared using the File Time Window Options Template Trammell, et al. Expires January 15, 2009 [Page 11] Internet-Draft IPFIX Files July 2008 defined in Section 8.1.2. 5.5. Data Integrity When storing flow data over long time scales, especially for archival purposes, it is important to ensure that hardware or software faults do not introduce errors into the data over time. The ideal flow storage format will support the detection and correction of encoding- level errors in the data. Note that more advanced error correction is almost certainly best handled at a layer below that addressed by this document. Error correction is a topic well addressed by the storage industry in general (e.g. by RAID and other technologies), and by specifying a flow storage format based upon files, we can leverage these features to meet this requirement. However, the ideal flow storage format will be resilient against errors, providing an internal facility for the detection of errors and the ability to isolate errors to as few data records as possible. Note that this requirement interacts with the choice of data compression or encryption algorithm. The use of block compression algorithms can serve to isolate errors to a single compression block, unlike stream compressors, which may fail to resynchronize after a single bit error, invalidating the entire message stream. Similarly, the use of a stream cipher can serve to isolate errors in the plaintext without amplifying them as, for example, a cipher in CBC mode can. See the "Recommended Compression Error Resilience Strategy" and "Recommended Encryption Error Resilience Strategy" sections below for more on this interaction. The IPFIX Message format does not support data integrity assurance. remove "long time scales"It is assumed that advanced error correction will be provided externally. For simple error detection support, checksums may be attached to messages via IPFIX Options according to the Message Checksum Options Template defined in Section 8.1.1. 5.6. Creator Authentication and Confidentiality Storage of flow data across long time scales may also require the IPFIX specifications [RFC 5101] does not ...assurance that no unauthorized entity can read or modify the stored data. Asymmetric-key cryptography can be applied to this problem, by signing flow data with the private key of the creator, and encrypting it with the public keys of those authorized to read it. The ideal flow storage format will support the encryption and signing of flow data. Trammell, et al. Expires January 15, 2009 [Page 12] Internet-Draft IPFIX Files July 2008 As with error correction, this problem has been addressed well at a layer below that addressed by this document. Instead of specifying a particular choice of encryption technology, we can leverage the fact that existing cryptographic technologies work quite well on data stored in files to meet this requirement. Beyond support for the use of TLS for transport over TCP or DTLS for transport over SCTP or UDP, both of which provide transient authentication and confidentiality, the IPFIX protocol does not support this requirement directly. It is assumed that this requirement will be met externally. 5.7. Anonymization and Obfuscation To ensure the privacy of individuals and organizations at the endpoints of communications represented by flow records, it is often necessary to obfuscate or anonymize stored and exported flow data. The ideal flow storage format will provide for a notation that a given information element on a given record type represents anonymized, rather than real, data. The IPFIX Message format presently has no support for anonymization notation. the IPFIX specifications [RFC 5101] does not ...It should be noted that anonymization is one of the requirements given for IPFIX in [RFC3917]. The decision to qualify this requirement with 'MAY' and not 'MUST' in the requirements document, and its subsequent lack of specification in the current version of the IPFIX protocol, is due to the fact that anonymization algorithms are still an open area of research, and that there currently exist no standardized methods for anonymization. No support is presently defined in [RFC5101] or this IPFIX-based File Format for anonymization, as anonymization notation is an area of open work for the IPFIX working group. 5.8. Session Auditability and Replayability Certain use cases for archival flow storage require the storage of collection infrastructure details alongside the data itself. These details include information about how and when data was received, and where it was received from, and are useful for auditing as well as for the replaying received data for testing purposes. The IPFIX Message format contains no direct support for auditability What is a static analysis?and replayability, though the IPFIX Information Model does define various Information Elements required to represent collection infrastructure details. These details may be stored in IPFIX Files using the Export Session Details Options Template defined in Section 8.1.3 and the Message Details Options Template defined in Trammell, et al. Expires January 15, 2009 [Page 13] Internet-Draft IPFIX Files July 2008 Section 8.1.4. 5.9. Performance Characteristics The ideal standard flow storage format will not have a significant negative impact on the performance of the application generating or processing flow data stored in the format. This is a non-functional requirement, but it is important to note that a standard that implies a significant performance penalty is unlikely to be widely implemented and adopted. A static analysis of the IPFIX Message format would seem to suggest that implementations of it are not particularly prone to slowness; Not prone to slowness... at the condition that there is no re-ordering of flow records, compression, or anonymization before you write into the file. In other words, at the condition that you write in sequence what you receive/want to export. I think the section order was discussed before. I don't remember the conclusionindeed, a template-based data representation is more easily subject to optimization for common cases than representations that embed structural information directly in the data stream (e.g. XML). However, a full analysis of the impact of using IPFIX Messages as a basis for flow data storage on read/write performance will require more implementation experience and performance measurement. Here I see the applicability after the requirements. Data Sets6. Applicability This section describes the specific applicability of IPFIX Files to various use cases. IPFIX Files are particularly useful in a flow collection and processing infrastructure using IPFIX for flow export. We explore the applicability and provide guidelines for using IPFIX files for the storage of flow data collected by IPFIX Collecting Processes and NetFlow V9 collectors, the testing of IPFIX Collecting Processes, and diagnostics of IPFIX Devices. 6.1. Storage of IPFIX-collected Flow Data IPFIX Files can naturally be used to store flow data collected by an IPFIX Collecting Process; indeed, this was one of the primary initial motivations behind the file format described within this document. Using IPFIX Files as such provides a single, standard, well- understood encoding to be used for flow data on disk and on the wire, and allows IPFIX implementations to leverage substantially the same code for flow export and flow storage. In addition, the storage of single Transport Sessions in IPFIX Files is particularly important for network measurement research, allowing repeatability of experiments by providing a format for the storage and exchange of IPFIX flow trace data much as the libpcap format is used for experiments on packet trace data. Trammell, et al. Expires January 15, 2009 [Page 14] Internet-Draft IPFIX Files July 2008 6.2. Storage of NetFlow V9-collected Flow Data Although the IPFIX protocol is based on the Cisco Netflow Services, Version 9 (NetFlow V9) protocol [RFC3954], the two have diverged since work began on IPFIX. However, since the NetFlow V9 information model is a compatible subset of the IPFIX information model, it is possible to use IPFIX files to store collected NetFlow V9 flow data. This approach may be particularly useful in multi-vendor, multi- protocol collection infrastructures using both NetFlow V9 and IPFIX to export flow data. The applicability of IPFIX Files to this use case is outlined in Appendix B. 6.3. Testing IPFIX Collecting Processes IPFIX Files can be used to store IPFIX Messages for the testing of IPFIX Collecting Processes. A variety of test cases may be stored in IPFIX Files. First, IPFIX data sets collected in real network IPFIX records -> IPFIX Messagesenvironments and stored in an IPFIX File can be used as input to check the behavior of new or extended implementations of IPFIX Collectors. Furthermore, IPFIX Files can be used to validate the operation of a given IPFIX Collecting Process in a new environment, i.e., to test with recorded IPFIX data from the target network before installing the Collecting Process in the network. The IPFIX File format can also be used to store artificial, non- compliant reference messages for specific Collecting Process test cases. Examples for such test cases are sets of IPFIX records with undefined Information Elements, Data Records described by missing Templates, or incorrectly framed messages or data sets. Representative error handling test cases are defined in "IPFIX Testing" [I-D.ietf-ipfix-testing]. Furthermore, fast replay of IPFIX records stored in a file can be Why re-explain the definition here?used for stress/load tests (e.g., high rate of incoming Data Records, large Templates with high Information Element counts), as described in "IPFIX Testing" [I-D.ietf-ipfix-testing]. The provisioning and use of a set of reference files for testing simplifies the performance of tests and increases the comparability of test results. 6.4. IPFIX Device Diagnostics As an IPFIX File can be used store any collection of flows, the format may also be used for dumping and storing various types of flow data for IPFIX Device diagnostics (e.g., the open flow cache of a Metering Process or the flow backlog of an Exporting or Collecting Process at the time of a process reset or crash). File-based storage Trammell, et al. Expires January 15, 2009 [Page 15] Internet-Draft IPFIX Files July 2008 is preferable to remote transmission in such error-recovery situations. 7. Detailed Description An IPFIX File, as introduced in Section 3 and elaborated below, is at its core simply an IPFIX Message stream serialized to some filesystem. what does it mean "normal IPFIX operation"?Any valid serialized IPFIX Message stream MUST be accepted by a File Reader as a valid IPFIX file. In this way, the filesystem is simply treated as another IPFIX transport alongside SCTP, TCP, and UDP. In contrast to normal IPFIX operation, Is this important, since the IPFIX Message contains the correct time anyway?the time between a File Writer writing an IPFIX Message stream to a File and a File Reader reading it can be extremely variable. In other words, this notional file transport has unusually high latency, as the File Reader and File Writer do not necessarily run at the same time. Or do you want to say: don't rely on the write time in the file? You explained that already a few paragraphs before.This section specifies the detailed actions of File Readers and File Writers in handling IPFIX Files, and further specifies actions of File Writers in specific use cases. Unless otherwise specified herein, where appropriate IPFIX File Writers MUST behave as IPFIX Exporting Processes, and IPFIX File Readers MUST behave as IPFIX Collecting Processes. 7.1. File Reader Specification An IPFIX File Reader MUST accept as valid any serialized IPFIX Message stream that would be considered valid by one or more of the other defined IPFIX transport layers. >From a spec. point of view, can we say that an IPFIX File Reader must comply to the Collecting Process specifications from RFC5101? I have a problem with "requirement" since the requirements were treated in the previous section.Practically, this means that the union of template management features supported by SCTP, TCP, and UDP MUST be supported in IPFIX Files. The following requirements I would remove this sentence.
TemplateIPFIX Filealready defined within the file, as may occur with template Template
What does the File Reader must do in that case?Replace or simply write in sequence? Btw, it depends on the transport. For SCTP, that's impossible: Template IDs are unique per SCTP association and per Observation Domain. If the Collecting Process receives a Template that has already been received but that has not previously been withdrawn (i.e., a Template Record from the same Exporter Observation Domain with the same Template ID received on the SCTP association), then the Collecting Process MUST shut down the association. What if the IPFIX Message is malformed? Write or not? Useful for diagnostic but ... So basically the answer is: it depends. If the Collecting Process receives a malformed IPFIX Message, it MUST reset the SCTP association, discard the IPFIX Message, and SHOULD log the error. Note that non-zero Set padding does not constitute a malformed IPFIX Message.
So the IPFIX Writer MUST write the TWM into the IPFIX File.I disagree. This was discussed already on the list.Trammell, et al. Expires January 15, 2009 [Page 16] Internet-Draft IPFIX Files July 2008 Note that some applications, particularly those storing large collections of data over long periods of time, may benefit from the ability to treat a collection of IPFIX Files as a single Transport Session. A File Reader MAY be configurable to treat a collection of Files (e.g., all the files in a directory) as a single Transport Session. However, a File Reader MUST NOT treat a single IPFIX File as containing multiple Transport Sessions. If the File Write is on a Collector,If an IPFIX File uses the technique described in "Reducing Redundancy in IPFIX and PSAMP Reports" [I-D.ietf-ipfix-reducing-redundancy] AND all of the non-Options Templates in the File contain the commonPropertiesId Information Element, a File Reader MAY assume the set of commonPropertiesId definitions provides a complete table of contents for the File for searching purposes. 7.2. File Writer Specification While any valid serialized IPFIX Message stream is a valid IPFIX File, the following recommendations will improve representation simplicity and read performance in the general case, where possible. File Writers SHOULD emit each Template Set or Options Template Set to appear in the file before any Data Set described by the Templates within that Set, to ensure the File Reader can decode every Data Set without waiting to process subsequent Templates or Options Templates. - Not possible with UDP. - Not possible with PR-SCTP without the [IPFIX-PER-STREAM] draft, which you should mention. Obviously, removing the restriction "one file = one stream" If the File Write is on a Collector,File Writers SHOULD emit Data Records described by Options Templates to appear in the file before any Data Records which depend on the scopes defined by those options. - Not possible with UDP. - Not possible with PR-SCTP without the [IPFIX-PER-STREAM] draft, which you should mention Obviously, removing the restriction "one file = one stream" If the File Write is on a Collector,File Writers SHOULD use Template Withdrawals to withdraw Templates if template IDs need to be reused. In this case, the new Templates reusing those IDs SHOULD appear directly in the file after the Template Withdrawals making the IDs available for reuse. - Not possible with UDP. - Not possible with PR-SCTP without the [IPFIX-PER-STREAM] draft, which you should mention Obviously, removing the restriction "one file = one stream" I don't understand what the File Writer should do with that statement? ... because I was assuming that the File Writer would simply write what it receives...Template Withdrawals SHOULD NOT be used unless necessary to reuse template IDs. So the IPFIX File should keep in memory the (Options) Template for that active Transport Session in case where it lasts a long time, where several IPFIX Files are required in order to insert the (Options) Template in the subsequent IPFIX Files?Each IPFIX File is generally synonymous with a single Transport Session. File Writers SHOULD store the Templates and Options required to decode the data within the File in the File itself, and File Readers SHOULD NOT use Templates or Options defined in one file to decode or interpret Data Sets in another. A simple example: [IPFIX-RED-RED] used across IPFIX Files Why not put this section as 7.2.1?File Writers SHOULD write IPFIX Messages within an IPFIX File in ascending Export Time order. File Writers MAY write Data Records to an IPFIX File in any order. However, File Writers that write flow records to an IPFIX File in Trammell, et al. Expires January 15, 2009 [Page 17] Internet-Draft IPFIX Files July 2008 flowStartTime or flowEndTime order SHOULD be consistent in this ordering within each File. 7.3. Specific File Writer Use Cases Some of my remarks above might be treated below... IPFIX FileThe specifications in this section apply to specific situations. Each section below extends or modifies the base File Writer specification in Section 7.2. Considerations for collocation of a File Writer with IPFIX Collecting Processes and Metering Processes are given, as are specific guidelines for using IPFIX Files for archival storage, or as documents. Also covered are the use of IPFIX Files in the testing and diagnostics of IPFIX Devices. 7.3.1. Collocating a File Writer with a Collecting Process When collocating a File Writer with an IPFIX Collecting Process for archival storage of collected data in IPFIX Files as described in Section 6.1, the following recommendations may improve the usefulness of the stored data. The simplest way for a to store the data collected in a single Transport Session is to simply write the incoming IPFIX Messages to an IPFIX File as they are collected. However, the resulting files per-message or per-Message (2 lines above)will lack information about the IPFIX Transport Session used to export them, such as the network addresses of the Exporting and Collecting Processes and the protocols used to transport them. In this case, if information about the Transport Session is required, the File Writer SHOULD store a single IPFIX Transport Session in an IPFIX File and SHOULD record information about the Transport Session using the Export Session Details Options Template described in Section 8.1.3. Additional per-Message information MAY be recorded by the File Writer using the Message Details Options Template described in Section 8.1.4. Per-message information includes the time at which That's very difficult without the [IPFIX-PER-STREAM] with PR-SCTPeach IPFIX Message was received at the Collecting Process, and can be used to resend IPFIX Messages while keeping the original measurement plane traffic profile. When collocating a File Writer with a Collecting Process, the Export Time of each Message SHOULD be the Export Time of the Message received by the Collecting Process containing the first Data Record in the Message. Note that File Writers storing IPFIX data collected from an IPFIX Collecting Process using SCTP as the transport protocol SHOULD interleave messages from multiple streams in order to preserve Export Time order, and SHOULD reorder the written messages as necessary to ensure that each Template Set or Options Template Set appears in the file before any Data Set described by the Templates >From the EP or MP.Trammell, et al. Expires January 15, 2009 [Page 18] Internet-Draft IPFIX Files July 2008 within that Set. 7.3.2. Collocating a File Writer with a Metering Process Note that File Writers may also be collocated directly with IPFIX Metering Processes, for writing measured information directly to disk without intermediate IPFIX Exporting or Collecting Processes. This arrangement may be particularly useful when providing data to an analysis environment with an IPFIX File based workflow, or when testing Metering Processes during development. When collocating a File Writer with a Metering Process, note that Information Elements associated with Exporting or Collecting Processes are meaningless, and SHOULD NOT appear in the Export Session Details Options Template described in Section 8.1.3 or the Message Details Options Template described in Section 8.1.4. When collocating a File Writer with an Exporting Process, the Export Time of each Message SHOULD be the time at which the first Data Record in the Message was received from the Exporting Process. I would say EP, but your first sentence in this section says "without intermediate IPFIX Exporting " I would use two sentences, otherwise it's confusing.7.3.3. Using IPFIX Files for Archival Storage While in the general case File Writers should store one Transport Session per IPFIX File, some applications storing large collections of data over long periods of time may benefit from the ability to treat a collection of IPFIX Files as a single Transport Session. A File Writer MAY be configurable to write data from a single Transport Session into multiple IPFIX Files; however, File Writers supporting such a configuration option MUST provide a configuration option to support one-file-per-session behavior for interoperability purposes. File Writers compressing or encrypting archival data and File Readers reading compressed or encrypted archival data SHOULD follow the recommendations in Section 9. 7.3.4. Using IPFIX Files as Documents When IPFIX Files are used as documents, to store a set of flows relevant to query, investigation, or other common context, or for the publication of flow data sets relevant to network research, each File MUST be readable as a single Transport Session, self-contained and making no reference to metadata stored in separate Files, in order to ensure interoperability. When writing Files to be used as documents, File Writers may emit the special Data Records described by Options Templates before any other Data Records in the File, in the following order, to ease the Trammell, et al. Expires January 15, 2009 [Page 19] Internet-Draft IPFIX Files July 2008 inspection and use of documents by File Readers: The may concerns "may emit" or "may emit in order". Btw isn't it MAY?
ofThere is a SHOULD here. See my comments about may versus MAY above.files MUST NOT be transmitted to Collecting Processes or given as input File Readers not under test. Note that an extremely simple IPFIX Exporting Process may be crafted for testing purposes by simply reading an IPFIX File and transmitting it directly to a Collecting Process. Similarly, an extremely simple Collecting Process may be crafted for testing purposes by simply accepting connections and/or IPFIX Messages from Exporting Processes Trammell, et al. Expires January 15, 2009 [Page 20] Internet-Draft IPFIX Files July 2008 and writing the session's message stream to an IPFIX File. 7.3.6. Writing IPFIX Files for Device Diagnostics IPFIX Files can be used in the debugging of devices which use flow data as internal state, as a common format for the representation of flow tables. In such situations, the opaueOctets information element can be used to store additional non-IPFIX encoded, non-flow information (e.g., stack backtraces, process state, etc.) within the IPFIX File as in Section 10.1; the IPFIX flow table information could also be embedded in a larger proprietary diagnostic format using delimiters as in Section 10.2 8. File Format Metadata Specification This section defines the Options Templates used for IPFIX File metadata, and the Information Elements they require. 8.1. Recommended Options Templates for IPFIX Files The following Options Templates allow IPFIX Message streams to meet the requirements outlined above without extension to the message format or protocol. They are defined in terms of existing Information Elements defined in [RFC5102], the Information Elements defined in "Exporting Type Information for IPFIX Information Elements" [I-D.ietf-ipfix-exporting-type], as well as Information Elements defined in Section 8.2. IPFIX File Readers and Writers SHOULD support these options templates as defined below. We observed an IPFIX Message, with its own length. Now, we have to add the Message Checksum Options Template.In addition, IPFIX File Readers and Writers SHOULD support the Options Templates defined in "Exporting Type Information for IPFIX Information Elements" [I-D.ietf-ipfix-exporting-type] in order to support self-description of enterprise-specific Information Elements. 8.1.1. Message Checksum Options Template The Message Checksum Options Template specifies the structure of a Data Record for attaching an MD5 message checksum to an IPFIX Message. An MD5 message checksum as described MAY be used if long- term data integrity is important to the application. The described Data Record MUST appear only once per IPFIX Message, but MAY appear anywhere within the Message. - Is this a new IPFIX Message? Then we have to say if this comes after or before the IPFIX Message it refers to. - Or we have to modify the observed IPFIX Message: changing the length of the IPFIX Message header. If this is the case (and I guess it is, but it's not clearly mentioned), then there is a problem. I export an IPFIX Message with the maximum length, the IPFIX Writer adds this Options Template before writing it into the file. Now, I transfer this file. Will the other IPFIX Reader reject it because it's not IPFIX compliant, i.e. too big? In other words, should the File Writer strictly follow RFC5101 or not? Where should we add this one?The template SHOULD contain the following Information Elements: Trammell, et al. Expires January 15, 2009 [Page 21] Internet-Draft IPFIX Files July 2008 +--------------------+----------------------------------------------+ | IE | Description | +--------------------+----------------------------------------------+ | messageScope | A marker denoting this Option applies to the | | [scope] | whole IPFIX Message; content is ignored. | | | This Information Element MUST be defined as | | | a Scope Field. | | messageMD5Checksum | The MD5 checksum of the containing IPFIX | | | Message. | +--------------------+----------------------------------------------+ 8.1.2. File Time Window Options Template The File Time Window Options Template specifies the structure of a Data Record for attaching a time window to an IPFIX File; this Data Record is referred to as a time window record. A time window record defines the earliest flow start time and the latest flow end time of the flow records within a File. One and only one time window record MAY appear within an IPFIX File if the time window information is available; a File Writer MUST NOT write more than one time window record to an IPFIX File. A File Writer that writes a time window record to a File MUST NOT write any Flow with a start time before the beginning of the window or an end time after the end of the window to that File. - in a new IPFIX Message? - in an existing one? If yes, which one? Why do you say: Transport Session and not IPFIX File?The template SHOULD contain the following Information Elements: +---------------------+---------------------------------------------+ | IE | Description | +---------------------+---------------------------------------------+ | sessionScope | A marker denoting this Option applies to | | [scope] | the whole IPFIX Transport Session (i.e., | | | IPFIX File); content is ignored. This | >From our email exchange:| | Information Element MUST be defined as a | | | Scope Field. | | minFlowStartSeconds | The start time of the earliest flow in the | | | Transport Session (i.e., File) in epoch | | | seconds. | | maxFlowEndSeconds | The end time of the latest flow in the | | | Transport Session (i.e., File) in epoch | | | seconds. | +---------------------+---------------------------------------------+ Benoit: - 7.1.2 and 7.1.3. Why
minFlowStartSeconds, maxFlowStartSeconds,
minExportSeconds, maxExportSeconds? Why not any of the time related
I.E.? Not to duplicate the I.Es?
Brian: Basically,
yes; the idea is that when you're using the first two IEs to attach
time windows to files, second resolution is sufficient, and there's no
need to get more precise than that. This may be an overly restrictive
assumption. The export time window information, however, is explicitly
in seconds, because it describes the IPFIX Export Time, which is also
in seconds.
My feedback is: - it's not specified that you meant the IPFIX Export Time. - "there's no need to get more precise than that". I disagree, the answer is: it depends. Same remark: where?8.1.3. Export Session Details Options Template The Export Session Details Options Template specifies the structure of a Data Record for recording the details of an IPFIX Transport Session in an IPFIX File. It is intended for use in storing a single Trammell, et al. Expires January 15, 2009 [Page 22] Internet-Draft IPFIX Files July 2008 complete IPFIX Transport Session in a single IPFIX File. The described Data Record SHOULD appear only once in a given IPFIX File. MAY contain more.The template SHOULD contain the following Information Elements, subject to applicability as noted on each Information Element: For example, new I.E. about SCTP streams number, or stream ID, or whatever in the future. IPFIX Message?+----------------------------+--------------------------------------+ | IE | Description | +----------------------------+--------------------------------------+ | sessionScope [scope] | A marker denoting this Option | | | applies to the whole IPFIX Transport | | | Session (i.e., IPFIX File); content | | | is ignored. This Information | | | Element MUST be defined as a Scope | | | Field. | | exporterIPv4Address | IPv4 address of the IPFIX Exporting | | | Process from which the Messages in | | | this Transport Session were | | | received. Present only for | | | Exporting Processes with an IPv4 | | | interface. For multi-homed SCTP | | | associations, this SHOULD be the | | | primary path endpoint address of the | | | Exporting Process. | | exporterIPv6Address | IPv6 address of the IPFIX Exporting | | | Process from which the Messages in | | | this Transport Session were | | | received. Present only for | | | Exporting Processes with an IPv6 | | | interface. For multi-homed SCTP | | | associations, this SHOULD be the | | | primary path endpoint address of the | | | Exporting Process. | | exporterTransportPort | The source port from which the | | | Messages in this Transport Session | | | were received. | | collectorIPv4Address | IPv4 address of the IPFIX Collecting | | | Process which received the Messages | | | in this Transport Session. Present | | | only for Collecting Processes with | | | an IPv4 interface. For multi-homed | | | SCTP associations, this SHOULD be | | | the primary path endpoint address of | | | the Collecting Process. | Trammell, et al. Expires January 15, 2009 [Page 23] Internet-Draft IPFIX Files July 2008 | collectorIPv6Address | IPv6 address of the IPFIX Collecting | | | Process which received the Messages | | | in this Transport Session. Present | | | only for Collecting Processes with | | | an IPv6 interface. For multi-homed | | | SCTP associations, this SHOULD be | | | the primary path endpoint address of | | | the Collecting Process. | | collectorTransportPort | The destination port on which the | | | Messages in this Transport Session | | | were received. | | collectorTransportProtocol | The IP Protocol Identifier of the | | | transport protocol used to transport | | | Messages within this Transport | | | Session. | | collectorProtocolVersion | The version of the IPFIX Protocol | | | used to transport Messages within | | | this Transport Session. | | minExportSeconds | The Export Time of the first Message | | | in the Transport Session. | | maxExportSeconds | The Export Time of the last Message | | | in the Transport Session. | +----------------------------+--------------------------------------+ 8.1.4. Message Details Options Template The Message Details Options Template specifies the structure of a Data Record for attaching additional export details to an IPFIX Message. These details include the time at which a message was same remark about the timing. Why not be flexible.received and information about the export and collection infrastructure used to transport the Message. This Options Template also allows the storage of the export session metadata provided the Export Session Details Options Template, for storing information from multiple Transport Sessions in the same IPFIX File. The template SHOULD contain the following Information Elements, subject to applicability as noted for each Information Element. Note that when used in conjunction with the Export Session Details Options Template, when storing a single complete IPFIX Transport Session in an IPFIX File, this template SHOULD contain only the messageScope and collectionTimeMilliseconds Information Elements, and the exportSctpStreamId Information Element for Messages transported via SCTP. Trammell, et al. Expires January 15, 2009 [Page 24] Internet-Draft IPFIX Files July 2008 +----------------------------+--------------------------------------+ | IE | Description | +----------------------------+--------------------------------------+ | messageScope [scope] | A marker denoting this Option | | | applies to the whole IPFIX message; | | | content is ignored. This | | | Information Element MUST be defined | | | as a Scope Field. | | collectionTimeMilliseconds | The absolute time at which this | | | Message was received by the IPFIX | | | Collecting Process. |
A new IPFIX Message is required or not?Each time a new IPFIX Message is required (maybe the case for your metadata cases), what do we do with the Sequence Number? Is the File Writer consider as a mediation function then? Is this a generic statement (see my remark above in the metadata section) or only applicable here?Processing the encapsulated non-IPFIX data is left to a separate processing mechanisms that can identify encapsulated non-IPFIX data in an IPFIX message stream, but need not have any other IPFIX handling capability, except the ability to skip over all IPFIX messages that do not encapsulate non-IPFIX data. The Message Checksum Options Template, described in Section 8.1.1 may be used as a uniform mechanism to identify errors within encapsulated data. Note that this mechanism can only encapsulate data objects up to 65,515 octets in length. If the space available in one IPFIX Message is not enough for the amount of data to be encapsulated, then the data must be broken into smaller segments that are encapsulated into consecutive IPFIX Messages. Any additional structuring or semantics of the raw data is outside the scope of IPFIX and must be implemented within the encapsulated binary data itself. Furthermore, the raw encapsulated data cannot be assumed by an IPFIX File Reader to have any specific format. 10.2. Encapsulation of IPFIX Files within Other File Formats Consequently, it may also be useful to reverse the encapsulation, that is, to export or store IPFIX data inline within a non-IPFIX file or data stream. This makes sense when the other file format is not compatible with the encapsulation described above in Section 10.1. Generally speaking, the encapsulation here will be specific to the format of the containing file. For example, IPFIX files may be embedded in XML elements using hex or Base64 encoding, or in raw binary files using start and end delimiters or some form of run- length encoding. As there are as many potential encapsulations here as there are potential file formats, the specifics of each are out of scope for this specification. 11. Security Considerations The IPFIX-based file format itself does not directly introduce security issues. Rather it is used to store information which may for privacy or business reasons be considered sensitive. The file format must therefore provide appropriate procedures to guarantee the integrity and confidentiality of the stored information. Trammell, et al. Expires January 15, 2009 [Page 33] Internet-Draft IPFIX Files July 2008 The underlying protocol used to exchange the information that will be stored using the format proposed in this document must as well apply appropriate procedures to guarantee the integrity and confidentiality of the exported information. Such issues are addressed in [RFC5101]. Implementors of IPFIX File Writers which store data taken from an IPFIX Collecting Process using TLS or DTLS for transport security should note that IPFIX Files may present a potential breach of confidentiality if IPFIX data collected using TLS or DTLS is stored in unencrypted files, and should consider providing an external file encryption option to mitigate this risk. 12. IANA Considerations This document specifies the creation of several new IPFIX Information Elements in the IPFIX Information Element registry located at http://www.iana.org/assignments/ipfix, as defined in Section 8.2 above. IANA has assigned the following Information Element numbers for their respective Information Elements as specified below: o Information Element number TBD1 for the collectionTimeMilliseconds Information Element. o Information Element number TBD2 for the exportSctpStreamId Information Element. o Information Element number TBD3 for the maxExportSeconds Information Element. o Information Element number TBD4 for the maxFlowEndSeconds Information Element. o Information Element number TBD5 for the messageMD5Checksum Information Element. o Information Element number TBD6 for the messageScope Information Element. o Information Element number TBD7 for the minExportSeconds Information Element. o Information Element number TBD8 for the minFlowStartSeconds Information Element. o Information Element number TBD9 for the opaqueOctets Information Element. Trammell, et al. Expires January 15, 2009 [Page 34] Internet-Draft IPFIX Files July 2008 o Information Element number TBD10 for the sessionScope Information Element. [NOTE for IANA: The text TBDn should be replaced with the respective assigned Information Element numbers where they appear in this document.] 13. Acknowledgements Thanks to Maurizio Molina, Tom Kosnar, and Andreas Kind for technical assistance with the requirements for a standard flow storage format. Thanks to Benoit Claise, Paul Aitken, and Andrew Johnson for their reviews and feedback. 14. References 14.1. Normative References [RFC5101] Claise, B., "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information", RFC 5101, January 2008. [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J. Meyer, "Information Model for IP Flow Information Export", RFC 5102, January 2008. [I-D.ietf-ipfix-reducing-redundancy] Boschi, E., "Reducing Redundancy in IP Flow Information Export (IPFIX) and Packet Sampling (PSAMP) Reports", draft-ietf-ipfix-reducing-redundancy-04 (work in progress), May 2007. [I-D.ietf-ipfix-exporting-type] Boschi, E., Trammell, B., Mark, L., and T. Zseby, "Exporting Type Information for IPFIX Information Elements", draft-ietf-ipfix-exporting-type-01 (work in progress), February 2008. [RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, April 1992. 14.2. Informative References [I-D.ietf-ipfix-arch] Sadasivan, G. and N. Brownlee, "Architecture Model for IP Flow Information Export", draft-ietf-ipfix-arch-02 (work Trammell, et al. Expires January 15, 2009 [Page 35] Internet-Draft IPFIX Files July 2008 in progress), October 2003. [I-D.ietf-ipfix-as] Zseby, T., "IPFIX Applicability", draft-ietf-ipfix-as-12 (work in progress), July 2007. [RFC5103] Trammell, B. and E. Boschi, "Bidirectional Flow Export Using IP Flow Information Export (IPFIX)", RFC 5103, January 2008. [I-D.ietf-ipfix-testing] Schmoll, C., Aitken, P., and B. Claise, "Guidelines for IP Flow Information eXport (IPFIX) Testing", draft-ietf-ipfix-testing-05 (work in progress), April 2008. [RFC3954] Claise, B., "Cisco Systems NetFlow Services Export Version 9", RFC 3954, October 2004. [RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander, "Requirements for IP Flow Information Export (IPFIX)", RFC 3917, October 2004. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [SAINT2007] Trammell, B., Boschi, E., Mark, L., and T. Zseby, "Requirements for a standardized flow storage solution", in Proceedings of the SAINT 2007 workshop on Internet Measurement Technology, Hiroshima, Japan, January 2007. Appendix A. Example IPFIX File In this section we will explore an example IPFIX File which demonstrates the various features of the IPFIX File format. This file contains flow records described by a single Template. This file also contains a File Time Window record to note the start and end time of the data, and an Export Session Details record to record collection infrastructure information. Each Message within this File also contains a Message Checksum record, as this file may be externally encrypted and/or stored as an archive. The structure of this file is shown in Figure 2. Trammell, et al. Expires January 15, 2009 [Page 36] Internet-Draft IPFIX Files July 2008 +=================================================+ | IPFIX Message seq. 0 | | +---------------------------------------------+ | | | Template Set (id 2) 1 rec | | | | Data Tmpl. id 256 | | | +---------------------------------------------+ | | | Options Template Set (id 3) 3 recs | | | | File Time Window Opt. Tmpl. id 257 | | | | Message Checksum Opt. Tmpl. id 259 | | | | Export Session Details Opt. Tmpl. id 258 | | | +---------------------------------------------+ | | | Data Set (id 259) [Message Checksum] 1 rec | | | +---------------------------------------------+ | +=================================================+ | IPFIX Message seq. 1 | | +---------------------------------------------+ | | | Data Set (id 257) [File Time Window] 1 rec | | | +---------------------------------------------+ | | | Data Set (id 258) [Export Session] 1 rec | | | +---------------------------------------------+ | | | Data Set (id 259) [Message Checksum] 1 rec | | | +---------------------------------------------+ | +=================================================+ | IPFIX Message seq. 4 | | +---------------------------------------------+ | | | Data Set (id 256) 50 recs | | | | contains flow data | | | +---------------------------------------------+ | | | Data Set (id 259) [Message Checksum] 1 rec | | | +---------------------------------------------+ | +=================================================+ | IPFIX Message seq. 55 | | . . . | Figure 2: File Example Structure The template describing the data records contains a flow start timestamp, an IPv4 5-tuple, and packet and octet total counts. The Template Set defining this is as shown in Figure 3 below: Trammell, et al. Expires January 15, 2009 [Page 37] Internet-Draft IPFIX Files July 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 2 | Length = 40 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 256 | Field Count = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| flowStartSeconds = 150 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceIPv4Address = 8 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| dest.IPv4Address = 12 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| sourceTransportPort = 7 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| dest.TransportPort = 11 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| protocolIdentifier = 4 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| octetTotalCount = 85 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| packetTotalCount = 86 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: File Example Data Template A.1. Example Options Templates This is followed by an Options Template Set containing the options templates required to read the File: the File Time Window Options Template defined in Section 8.1.2 above, the Export Session Details Options Template defined in Section 8.1.3 above, and the Message Checksum Options Template defined in Section 8.1.1 above. This Options Template Set is shown in Figure 4 and Figure 5 below: Trammell, et al. Expires January 15, 2009 [Page 38] Internet-Draft IPFIX Files July 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 3 | Length = 80 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 257 | Field Count = 3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Scope Field Count = 1 |0| sessionScope = TBD10 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 1 |0| minFlowStartSeconds = TBD8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 |0| maxFlowEndSeconds = TBD4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 | Template ID = 259 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Count = 2 | Scope Field Count = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| messageScope = TBD6 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| messageMD5Checksum = TBD5 | Field Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: File Example Options Templates (Time Window and Checksum) Trammell, et al. Expires January 15, 2009 [Page 39] Internet-Draft IPFIX Files July 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 258 | Field Count = 9 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Scope Field Count = 1 |0| sessionScope = TBD10 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 1 |0| exporterIPv4Address = 130 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 |0| collectorIPv4Address = 211 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 |0| exporterTransportPort = 217 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 2 |0| col.TransportPort = 216 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 2 |0| col.TransportProtocol = 215 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 1 |0| col.ProtocolVersion = 214 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 1 |0| minExportSeconds = TBD7 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 |0| maxExportSeconds = TBD3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Field Length = 4 | set padding (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: File Example Options Templates, Continued (Session Details) A.2. Example Supplemental Options Data Following the templates required to decode the file is the supplemental options information used to describe the file's contents and type information. First comes the File Time Window record; it notes that the file contains data from 9 October 2007 between 00:01:13 and 23:56:27 UTC, and appears as in Figure 6: Trammell, et al. Expires January 15, 2009 [Page 40] Internet-Draft IPFIX Files July 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 257 | Length = 13 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sessionScope | minFlowStartSeconds | 0 | 2007-10-09 00:01:13 UTC . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | maxFlowEndSeconds . . . | 2007-10-09 23:56:27 UTC . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . | +-+-+-+-+-+-+-+-+ Figure 6: File Example Time Window This is followed by information about how the data in the file was collected, in the Export Session Details record. This record notes that the session stored in this file was sent via SCTP from an exporter at 192.0.2.30 port 32769 to an collector at 192.0.2.40 port 4739, and contains messages exported between 00:01:57 and 23:57:12 UTC on 9 October 2007; it is represented in its Data Set as in Figure 7: Trammell, et al. Expires January 15, 2009 [Page 41] Internet-Draft IPFIX Files July 2008 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 258 | Length = 27 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sessionScope | exporterIPv4Address | 0 | 192.0.2.30 . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | collectorIPv4Address . . . | 192.0.2.31 . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | exporterTransportPort | cTPort . . . | 32769 | 4739 . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | cTProtocol | cPVersion | . . . | 132 | 10 | . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ minExportSeconds | . . . 2007-10-09 00:01:57 UTC | . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ maxExportSeconds | . . . 2007-10-09 23:57:12 UTC | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7: File Example Export Session Details A.3. Example Message Checksum Each IPFIX Message within the file is completed with a Message Checksum record; the structure of this record within its Data Set is as in Figure 8: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 259 | Length = 24 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | messageScope | | | 0 | | +-+-+-+-+-+-+-+-+ | | messageMD5Checksum | | (16 byte MD5 checksum of options message) | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | set padding (3 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8: File Example Message Checksum Trammell, et al. Expires January 15, 2009 [Page 42] Internet-Draft IPFIX Files July 2008 A.4. File Example Data Set After the templates and supplemental options information comes the data itself. The first record of an example Data Set is shown with its message and set headers in Figure 9: 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version = 10 | Length = 1296 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Export Time = 2007-10-09 00:01:57 UTC | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Observation Domain ID = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 256 | Length = 1254 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | flowStartSeconds | | 2007-10-09 00:01:13 UTC | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceIPv4Address | | 192.0.2.2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | destinationIPv4Address | | 192.0.2.3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sourceTransportPort | destinationTransportPort | | 32770 | 80 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | protocolId | totalOctetCount | 6 | 18000 . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | totalPacketCount . . . | 65 . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | (49 more records) . . . | +-+-+-+-+-+-+-+-+ Figure 9: File Example Data Set A.5. Complete File Example Bringing together the examples above and adding message headers as appropriate, a hex dump of the first 317 bytes of the example file constructed above would appear as in the annotated Figure 10 below. Trammell, et al. Expires January 15, 2009 [Page 43] Internet-Draft IPFIX Files July 2008 [EDITOR'S NOTE: In this figure, xx refers to unassigned IANA IE numbers as in the IANA Considerations section above; cs refers to message checksum bytes that depend on the rest of the message contents. These will have to be replaced if we keep this example once the IE numbers are assigned.] 0:|00 0A 00 A0 47 0A B6 E5 00 00 00 00 00 00 00 01 [^ first message header (length 160 bytes) --> 16:|00 02 00 28 01 00 00 08 00 96 00 04 00 08 00 04 [^ data template set --> 32: 00 0C 00 04 00 07 00 02 00 0B 00 02 00 04 00 01 48: 00 55 00 04 00 56 00 04|00 03 00 50 01 01 00 03 [^ opt template set --> 64: 00 01 xx xx 00 01 xx xx 00 04 xx xx 00 04 01 03 80: 00 02 00 01 xx xx 00 01 xx xx 00 10 01 02 00 09 96: 00 01 xx xx 00 01 00 82 00 04 00 D3 00 04 00 D9 112: 00 02 00 D8 00 02 00 D7 00 01 00 D0 00 01 xx xx 128: 00 04 xx xx 00 04 00 00|01 03 00 18 00 cs cs cs [^ checksum record --> 144: cs cs cs cs cs cs cs cs cs cs cs cs cs 00 00 00 176:|00 0A 00 50 47 0A B6 E5 00 00 00 01 00 00 00 01 [^ second message header (length 80 bytes) --> 192:|01 01 00 0E 00 47 0A B6 B9 47 0C 07 1B 00|01 02 [^ time window rec -> [ session detail rec ^ --> 208: 00 1C 00 C0 00 02 1E 0C 00 02 1F 80 01 12 83 84 224: 0A 47 0A B6 E5 47 0C 07 48 00|01 03 00 18 00 cs [ message checksum rec ^ --> 240: cs cs cs cs cs cs cs cs cs cs cs cs cs cs cs 00 256:|00 0A 05 10 47 0A B6 E5 00 00 00 06 00 00 00 01 [^ third message header (length 1296 bytes) --> 272:|01 00 04 E6|47 0A B6 B9 C0 00 02 02 C0 00 02 03 [^ set hdr ][^ first data rec --> 288: 80 02 00 50 06 00 00 46 50 00 00 00 41 Figure 10: File Example Hex Dump Trammell, et al. Expires January 15, 2009 [Page 44] Internet-Draft IPFIX Files July 2008 Appendix B. Applicability of IPFIX Files to NetFlow V9 flow storage As the IPFIX Message format is nearly a superset of the NetFlow V9 packet format, IPFIX Files can be used for store NetFlow V9 data relatively easily. This section describes a method for doing so. The differences between the two protocols are outlined in Appendix B.1 below. A simple, lightweight, message-for-message translation method for transforming V9 Packets into IPFIX Messages for storage within IPFIX Files is described in Appendix B.2. An example of this translation method is given in Appendix B.3. B.1. Comparing NetFlow V9 to IPFIX With a few caveats, the IPFIX Protocol is a superset of the NetFlow V9 protocol, having evolved from it largely through a process of feature addition to bring it into compliance with the IPFIX Requirements and the needs of stakeholders within the IPFIX Working Group. This appendix outlines the differences between the two protocols. It is informative only, and presented as an exploration of the two protocols to motivate the usage of IPFIX Files to store V9-collected flow data. B.1.1. Message Header Format Both NetFlow V9 and IPFIX use streams of messages prefixed by a message header, though the message header differs significantly between the two. Note that in |