OPSAWG M. Boucadair Internet-Draft Orange Intended status: Standards Track B. Claise Expires: 19 April 2024 Huawei 17 October 2023 Extended TCP Options and IPv6 Extension Headers IPFIX Information Elements draft-ietf-opsawg-ipfix-tcpo-v6eh-02 Abstract This document specifies new IP Flow Information Export (IPFIX) Information Elements (IEs) to solve some issues with existing ipv6ExtensionHeaders and tcpOptions IPFIX IEs, especially the ability to export any observed IPv6 extension headers or TCP options. Discussion Venues This note is to be removed before publishing as an RFC. Discussion of this document takes place on the Operations and Management Area Working Group Working Group mailing list (opsawg@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/opsawg/. Source for this draft and an issue tracker can be found at https://github.com/boucadair/ipfix-tcpoptions-and-v6eh. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 19 April 2024. Boucadair & Claise Expires 19 April 2024 [Page 1] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Issues with ipv6ExtensionHeaders Information Element . . 3 1.2. Issues with tcpOptions Information Element . . . . . . . 3 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 3. Information Elements for IPv6 Extension Headers . . . . . . . 4 3.1. ipv6ExtensionHeadersFull Information Element . . . . . . 4 3.2. ipv6ExtensionHeaderCount Information Element . . . . . . 5 3.3. ipv6ExtensionHeadersLimit Information Element . . . . . . 6 3.4. ipv6ExtensionHeadersChainLength Information Element . . . 7 3.5. Operational Considerations . . . . . . . . . . . . . . . 8 4. Information Elements for TCP Options . . . . . . . . . . . . 8 4.1. tcpOptionsFull Information Element . . . . . . . . . . . 8 4.1.1. tcpSharedOptionExID Information Element . . . . . . . 9 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.1. IPv6 Extension Headers . . . . . . . . . . . . . . . . . 10 5.2. TCP Options . . . . . . . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1. Normative References . . . . . . . . . . . . . . . . . . 11 8.2. Informative References . . . . . . . . . . . . . . . . . 13 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 1. Introduction This document specifies new IP Flow Information Export (IPFIX) Information Elements (IEs) to solve a set of issues encountered with the specifications of ipv6ExtensionHeaders (to export IPv6 extension headers) and tcpOptions (to export TCP options) IEs. More details about these issues are provided in the following sub-sections. Boucadair & Claise Expires 19 April 2024 [Page 2] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 1.1. Issues with ipv6ExtensionHeaders Information Element The specification of ipv6ExtensionHeaders IPFIX IE does not: * Cover the full extension headers range (Section 4 of [RFC8200]). * Specify the procedure to follow when all bits are exhausted. * Specify a means to export the order and the number of occurences of a given extension header. * Specify how to automatically update the IANA IPFIX registry ([IANA-IPFIX]) when a new value is assigned in [IANA-EH]. * Specify whether the exported values match the full enclosed values or only up to a limit imposed by hardware or software (e.g., Section 1.1 of [RFC8883]). * Specify how to report the length of IPv6 extension headers. Section 3 addresses these issues. 1.2. Issues with tcpOptions Information Element The specification of tcpOptions IPFIX IE does not: * Describe how any observed TCP option in a Flow can be exported using IPFIX. Only TCP options having a kind =< 63 can be exported in a tcpOptions IPFIX IE. * Support means to report the observed Experimental Identifiers (ExIDs) that are carried in shared TCP options (kind=253 or 254) [RFC6994]. Section 4 addresses these issues. 2. Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Boucadair & Claise Expires 19 April 2024 [Page 3] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 This document uses the IPFIX-specific terminology (Information Element, Template, Collector, Data Record, Flow, Flow Record, Exporting Process, Collecting Process, etc.) defined in Section 2 of [RFC7011]. As in [RFC7011], these IPFIX-specific terms have the first letter of a word capitalized. Also, the document uses the terms defined in [RFC8200] and [RFC9293]. In addition, the document makes use of the following term: Extension header chain: Refers to the chain of extension headers that are present in an IPv6 packet. This term should not be confused with the IPv6 header chain, which includes the IPv6 header, zero or more IPv6 extension headers, and zero or a single Upper-Layer Header. 3. Information Elements for IPv6 Extension Headers The definition of the ipv6ExtensionHeaders IE is updated in [I-D.ietf-opsawg-ipfix-fixes] to address some of the issues listed in Section 1.1. Because some of these limitations can't be addressed by simple updates to ipv6ExtensionHeaders, this section specifies a set of new Information Elements to address all the ipv6ExtensionHeaders limitations. 3.1. ipv6ExtensionHeadersFull Information Element Name: ipv6ExtensionHeadersFull ElementID: TBD1 Description: IPv6 extension headers observed in packets of this Flow. The information is encoded in a set of bit fields. For each IPv6 extension header, there is a bit in this set. The bit is set to 1 if any observed packet of this Flow contains the corresponding IPv6 extension header. Otherwise, if no observed packet of this Flow contained the respective IPv6 extension header, the value of the corresponding bit is 0. The IPv6 extension header associated with each bit is provided in [NEW_IPFIX_IPv6EH_SUBREGISTRY]. Bit 0 corresponds to the least- significant bit in the ipv6ExtensionHeadersFull IE while bit 254 corresponds to the most-significant bit of the IE. In doing so, few octets will be needed to encode common IPv6 extension headers when observed in a Flow. The "No Next Header" (59) value is used if there is no upper-layer Boucadair & Claise Expires 19 April 2024 [Page 4] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 header in an IPv6 packet. Even if the value is not considered as an extension header as such, the corresponding bit is set in the ipv6ExtensionHeadersFull IE whenever that value is encountered in the Flow. Several extension header chains may be observed in a Flow. These extension headers may be aggregated in one single ipv6ExtensionHeadersFull Information Element or be exported in separate ipv6ExtensionHeadersFull IEs, one for each extension header chain. This Information Element SHOULD NOT be exported if ipv6ExtensionHeaderCount Information Element is also present. The value should be encoded in fewer octets as per the guidelines in Section 6.2 of [RFC7011]. Abstract Data Type: unsigned Data Type Semantics: flags Additional Information: See [IANA-EH] for assigned extension header types. See Section 4 of [RFC8200] for the general definition of IPv6 extension headers. Reference: This-Document Note to the RFC Editor: Please replace [NEW_IPFIX_IPv6EH_SUBREGISTRY] with the link to the "ipv6ExtensionHeaders Bits" registry created by [I-D.ietf-opsawg-ipfix-fixes]. 3.2. ipv6ExtensionHeaderCount Information Element Name: ipv6ExtensionHeaderCount ElementID: TBD2 Description: As per Section 4.1 of [RFC8200], IPv6 nodes must accept and attempt to process extension headers in occurring any number of times in the same packet. This Information Element echoes the order of extension headers and number of consecutive occurrences of the same extension header type in a Flow. If several extension header chains are observed in a Flow, each Boucadair & Claise Expires 19 April 2024 [Page 5] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 header chain MUST be exported in a separate ipv6ExtensionHeaderCount IE. The same extension header type may appear several times in an ipv6ExtensionHeaderCount Information Element. For example, if an IPv6 packet of a Flow includes a Hop-by-Hop Options header, a Destination Options header, a Fragment header, and Destination Options header, the ipv6ExtensionHeaderCount Information Element will report two counts of the Destination Options header: the occurrences that are observed before the Fragment header and the occurrences right after the Fragment header. IPFIX reduced-size encoding as per Section 6.2 of [RFC7011] is used as required. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | EH Type#1 | Count |...| EH Type#n | Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Abstract Data Type: unsigned64 Data Type Semantics: identifier Additional Information: See the assigned IPv6 extension header types in [IANA-EH]. See [RFC8200] for the general definition of IPv6 extension headers. Reference: This-Document 3.3. ipv6ExtensionHeadersLimit Information Element Name: ipv6ExtensionHeadersLimit ElementID: TBD3 Description: When set to "true", this Information Element indicates that the exported extension headers information (e.g., ipv6ExtensionHeaderFull or ipv6ExtensionHeaderCount) does not match the full enclosed extension headers, but only up to a limit that is typically set by hardware or software. When set to "false", this Information Element indicates that the exported extension header information matches the full enclosed extension headers. Boucadair & Claise Expires 19 April 2024 [Page 6] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 When this Information Element is absent, this is equivalent to returning an ipv6ExtensionHeadersLimit Information Element with a value set to "false". Abstract Data Type: boolean Data Type Semantics: default Additional Information: See Section 4 of [RFC8200] for the general definition of IPv6 extension headers. See [RFC8883] for an example of IPv6 packets processing due to limits on extension headers. Reference: This-Document 3.4. ipv6ExtensionHeadersChainLength Information Element Name: ipv6ExtensionHeadersChainLength ElementID: TBD4 Description: In theory, there are no limits on the number of IPv6 extension headers that may be present in a packet other than the path MTU. However, it was regularly reported that IPv6 packets with extension headers are often dropped in the Internet. As discussed in Section 1.2 of [RFC8883], some hardware devices implement a parsing buffer of a fixed size to process packets, including all the headers. When the aggregate length of headers of an IPv6 packet exceeds that size, the packet will be discarded or deferred to a slow path. The ipv6ExtensionHeadersChainLength IE is used to report, in octets, the length of an extension header chain observed in a Flow. The length is the sum of the length of all extension headers of the chain. Exporting such information may help identifying root causes of performance degradation, including packet drops. Abstract Data Type: unsigned Data Type Semantics: identifier Units: octets Additional Information: See Section 4 of [RFC8200] for the general definition of IPv6 extension headers. Boucadair & Claise Expires 19 April 2024 [Page 7] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 See [RFC9098] for an overview of operational implications of IPv6 packets with extension headerss. Reference: This-Document 3.5. Operational Considerations If an implementation determines that it includes an extension header that it does no support, then the exact observed code of that extension header will be echoed in the ipv6ExtensionHeaderCount IE (Section 3.2). How an implementation disambiguates between unknown upper-layer protocols vs. extension headers is not IPFIX-specific. Readers may refer, for example, to Section 2.2 of [RFC8883] for a behavior of an intermediate nodes that encounters an unknown Next Header type. It is out of the scope of this document to discuss those considerations. The ipv6ExtensionHeadersLimit IE (Section 3.3) may or may not be present when the ipv6ExtensionHeadersChainLength IE (Section 3.4) is also present as these IEs are targeting distinct properties of extension headers handling. 4. Information Elements for TCP Options The definition of the tcpOptions IE is updated in [I-D.ietf-opsawg-ipfix-fixes] to address some of the issues listed in Section 1.2. Because some of these limitations can't be addressed by simple updates to tcpOptions, this section specifies a set of new Information Elements to address all the tcpOptions limitations. 4.1. tcpOptionsFull Information Element This section specifies a new Information Element to cover the full TCP options range. Name: tcpOptionsFull ElementID: TBD5 Description: TCP options in packets of this Flow. The information is encoded in a set of bit fields. For each TCP option, there is a bit in this set. The bit is set to 1 if any observed packet of this Flow contains the corresponding TCP option. Otherwise, if no observed packet of this Flow contained the respective TCP option, the value of the corresponding bit is 0. Options are mapped to bits according to their option numbers. Boucadair & Claise Expires 19 April 2024 [Page 8] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 Option number X is mapped to bit position "254 - X". This approach allows an observer to export any observed TCP option even if it does support that option and without requiring updating a mapping table. The value should be encoded in fewer octets as per the guidelines in Section 6.2 of [RFC7011]. Abstract Data Type: unsigned Data Type Semantics: flags Additional Information: See the assigned TCP option kinds at [IANA-TCP]. See [RFC9293] for the general definition of TCP options. Reference: This-Document 4.1.1. tcpSharedOptionExID Information Element Name: tcpSharedOptionExID ElementID: TBD6 Description: Observed 2-byte (or 4-byte) Expermients IDs (ExIDs) in a shared TCP option (Kind=253 or 254) in a Flow. The information is encoded in a set of 16-bit (or 32-bit) fields. Each 16-bit (or 32-bit) field carries the observed 2-byte (or 4-bute) ExID in a shared option. The value should be encoded in fewer octets as per the guidelines in Section 6.2 of [RFC7011]. Abstract Data Type: octetArray Data Type Semantics: identifier Additional Information: See assigned ExIDs at [IANA-TCP-EXIDs]. See [RFC9293] for the general definition of TCP options. See [RFC6964] for the shared use of experimental TCP Options. Reference: This-Document 5. Examples Boucadair & Claise Expires 19 April 2024 [Page 9] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 5.1. IPv6 Extension Headers This section provides few examples to illustrate the use of some IEs defined in the document. Figure 1 provides an example of reported values in an ipv6ExtensionHeadersFull Information Element for an IPv6 Flow in which only the IPv6 Destination Options header is observed. One octet is sufficient to report these observed options. Concretely, the ipv6ExtensionHeadersFull IE will be set to 1. MSB LSB 1 20 … 25 0 1 2 3 4 5 6 7 8 9 0 1 2 3 … 6 7 8 9 0 1 2 … 9 0 1 2 3 4 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+…+-+-+-+-+-+-+-+…+-+-+-+-+-+-+ |0|0|0|0|0|0|0|0|0|0|0|0|0|0| |0|0|0|0|0|0|0| |0|0|0|0|0|1| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+…+-+-+-+-+-+-+-+…+-+-+-+-+-+-+ Figure 1: A First Example of Extension Headers Figure 2 provides another example of reported values in an ipv6ExtensionHeadersFull Information Element for an IPv6 Flow in which the IPv6 Hop-by-Hop Options, Routing, and Destination Options headers are observed. One octet is sufficient to report these observed options. Concretely, the ipv6ExtensionHeadersFull IE will be set to 19. MSB LSB 1 20 … 25 0 1 2 3 4 5 6 7 8 9 0 1 2 3 … 6 7 8 9 0 1 2 … 9 0 1 2 3 4 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+…+-+-+-+-+-+-+-+…+-+-+-+-+-+-+ |0|0|0|0|0|0|0|0|0|0|0|0|0|0| |0|0|0|0|0|0|0| |0|1|0|0|1|1| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+…+-+-+-+-+-+-+-+…+-+-+-+-+-+-+ Figure 2: A Second Example of Extension Headers 5.2. TCP Options Given TCP kind allocation practices and the option mapping defined in Section 4.1, fewer octers are likely to be used for Flows with common TCP options. Figure 3 shows an example of reported values in a tcpOptionsFull IE for a TCP Flow in which End of Option List, Maximum Segment Size, and Window Scale options are observed. One octet is sufficient to report these observed options. Concretely, the tcpOptionsFull IE will be set to 15. Boucadair & Claise Expires 19 April 2024 [Page 10] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 MSB LSB 1 2 … 25 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 … 9 0 1 2 3 4 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+…+-+-+-+-+-+-+ |0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0| |0|0|1|1|0|1| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+…+-+-+-+-+-+-+ Figure 3: First Example of TCP Options 6. Security Considerations IPFIX security considerations are discussed in Section 11 of [RFC7011]. This document does not add new security considerations for exporting IEs other than those already discussed in Section 8 of [RFC7012]. 7. IANA Considerations This document requests IANA to add the following new IPFIX IEs to the IANA IPFIX registry [IANA-IPFIX]: +=======+=================================+==================+ | Value | Name | Reference | +=======+=================================+==================+ | TBD1 | ipv6ExtensionHeadersFull | Section 3.1 of | | | | This-Document | +-------+---------------------------------+------------------+ | TBD2 | ipv6ExtensionHeaderCount | Section 3.2 of | | | | This-Document | +-------+---------------------------------+------------------+ | TBD3 | ipv6ExtensionHeaderLimit | Section 3.3 of | | | | This-Document | +-------+---------------------------------+------------------+ | TBD4 | ipv6ExtensionHeadersChainLength | Section 3.4 of | | | | This-Document | +-------+---------------------------------+------------------+ | TBD5 | tcpOptionsFull | Section 4.1 of | | | | This-Document | +-------+---------------------------------+------------------+ | TBD6 | tcpSharedOptionExID | Section 4.1.1 of | | | | This-Document | +-------+---------------------------------+------------------+ Table 1: New IPFIX Information Elements 8. References 8.1. Normative References Boucadair & Claise Expires 19 April 2024 [Page 11] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 [IANA-EH] IANA, "Internet Protocol Version 6 (IPv6) Parameters, IPv6 Extension Header Types", . [IANA-IPFIX] IANA, "IP Flow Information Export (IPFIX) Entities", . [IANA-TCP] IANA, "Transmission Control Protocol (TCP) Parameters, TCP Option Kind Numbers", . [IANA-TCP-EXIDs] IANA, "Transmission Control Protocol (TCP) Parameters, TCP Experimental Option Experiment Identifiers (TCP ExIDs)", . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6964] Templin, F., "Operational Guidance for IPv6 Deployment in IPv4 Sites Using the Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 6964, DOI 10.17487/RFC6964, May 2013, . [RFC6994] Touch, J., "Shared Use of Experimental TCP Options", RFC 6994, DOI 10.17487/RFC6994, August 2013, . [RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information", STD 77, RFC 7011, DOI 10.17487/RFC7011, September 2013, . [RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model for IP Flow Information Export (IPFIX)", RFC 7012, DOI 10.17487/RFC7012, September 2013, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Boucadair & Claise Expires 19 April 2024 [Page 12] Internet-Draft New TCP and IPv6 EH IPFIX IEs October 2023 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . [RFC9293] Eddy, W., Ed., "Transmission Control Protocol (TCP)", STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022, . 8.2. Informative References [I-D.ietf-opsawg-ipfix-fixes] Boucadair, M. and B. Claise, "Simple Fixes to the IP Flow Information Export (IPFIX) IANA Registry", Work in Progress, Internet-Draft, draft-ietf-opsawg-ipfix-fixes- 02, 20 September 2023, . [RFC8883] Herbert, T., "ICMPv6 Errors for Discarding Packets Due to Processing Limits", RFC 8883, DOI 10.17487/RFC8883, September 2020, . [RFC9098] Gont, F., Hilliard, N., Doering, G., Kumari, W., Huston, G., and W. Liu, "Operational Implications of IPv6 Packets with Extension Headers", RFC 9098, DOI 10.17487/RFC9098, September 2021, . Acknowledgments Thanks to Paul Aitken and Eric Vyncke for the review and comments. Authors' Addresses Mohamed Boucadair Orange Email: mohamed.boucadair@orange.com Benoit Claise Huawei Email: benoit.claise@huawei.com Boucadair & Claise Expires 19 April 2024 [Page 13]