Operations D. Voyer Internet-Draft Bell Canada Intended status: Standards Track S. Gopalakrishnan Expires: 3 August 2024 R. Johny Cisco Systems 31 January 2024 Export of GTP-U Information in IP Flow Information Export (IPFIX) draft-voyersriram-opsawg-ipfix-gtpu-00 Abstract This document introduces IP Flow Information Export Information Elements to identify informantion containted in the Generic Packet Radio Service Tunneling Protocol User Plane header such as Tunnel Endpoint Identifier, and data contained in its session container extension header. 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/. 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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 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. IPFIX GTP-U Information Elements . . . . . . . . . . . . . . 3 4. Sample Use Cases . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . 6 Appendix A. IPFIX Encoding Examples . . . . . . . . . . . . . . 7 A.1. Template Record . . . . . . . . . . . . . . . . . . . . . 7 A.1.1. Template Record and Data Set . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction A dedicated header, called GPRS Tunneling Protocol Header (GTP), is defined by 3GPP for use of GTP-C Control plane and GTP-U User Plane [TS.29281] traffic of mobile subscribers. This document specifies six IPFIX Information Elements (IEs) [RFC7012] for fields within a GTP-U header. These IEs are used to export the GTP-U Tunnel Endpoint Identifier (TEID), QoS Flow Identifier (QFI) and PDU Type from the PDU Session Container extension header. Some examples are provided in Appendix A. Voyer, et al. Expires 3 August 2024 [Page 2] Internet-Draft IPFIX support for GTP-U January 2024 2. Terminology 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. This document makes use of the terms defined in [RFC7011] * IPFIX * IPFIX Information Elements * Template * Template Record * Options Template * Options Template Record * Data Record * Data Set 3. IPFIX GTP-U Information Elements This section defines IPFIX IEs corresponding to various fields in the GTP-U. gtpuFlags 8-bit flags field defined in the GTP-U. gtpuMsgType 8-bit message type field defined in the GTP-U. gtpuTEid 32-bit tunnel endpoint identifier field defined in GTP-U. gtpuSequenceNum 16-bit sequence number field defined in the GTP-U. gtpuQFI 8-bit QoS flow identifier field defined in PDU Session Container extension header of GTP-U. Voyer, et al. Expires 3 August 2024 [Page 3] Internet-Draft IPFIX support for GTP-U January 2024 gtpuPduType 8-bit PDU Type field defined in PDU Session Container extension header of GTP-U. 4. Sample Use Cases In order to identify the transport performance of PDU Sessions with specific QoS within a slice or within a group of slices hosted on the same UPF the GTP User Plane related IEs would be much helpful. For example when in case of one or a couple of dedicated UPFs are deployed per 5G slice, the slice is identified first using list of gNodeB IPs composing the slice and list of IPs of User Plane Function dedicated for the slice. The gNodeB and the User Plane Function form the tunnel endpoints. Also the traffic for individual PDU session per direction is identified using the GTP-U TEID, GTP-U PDU Type together with above mentioned tunnel endpoints. Further the traffic for specific QoS within a PDU session per direction is identified using the combination of GTP-U TEid, GTP-U PDU Type and GTP-U QFI attributes. It is possible that there may be multiple IP flows having the same attributes. In another scenario when multiple 5G slices are served by the same User Plane Function, the slice is identified using a separated list of gNodeB IPv6 addresses per slice. If Intermediate User Plane Function or Uplink Classifier is deployed there is an addition of a GTP-U tunnel between the Intermediate/Uplink-Classifier UPF and the final UPF. These brings a challenge for identifying the end to end path for a certain PDU session - where the GTP-U PDU Type and GTP-U QFI attributes from the gNodeB and Intermediate/Uplink-Classifier UPF tunnel will be the same on the Intermediate/Uplink-Classifier and final UPF tunnel, however the GTP-U TEids will be different since this is a different tunnel. 5. IANA Considerations This document requests IANA to add the IEs listed in Table 1 below to the "IPFIX Information Elements" registry [RFC7012] available at [IANA-IPFIX]. Table 1 lists the GTP-U IEs: Voyer, et al. Expires 3 August 2024 [Page 4] Internet-Draft IPFIX support for GTP-U January 2024 +-------+-----------------+--------------------------------------+ |Element| Name | Abstract | | | | | Data Type | Description | | ID | | Data Type | | | | | Semantics | | +-------+-----------------+-------------|------------------------| | TBD1 | gtpuFlags | unsigned8 | 8-bit flags field | | | | flags | defined in GTP-U | +-------+-----------------+-------------|------------------------| | TBD2 | gtpuMsgType | unsigned8 | 8-bit message type | | | | identifier | field defined in GTP-U | +-------+-----------------+-------------|------------------------| | TBD3 | gtpuTEid | unsigned32 | 32-bit tunnel endpoint | | | | identifier | identifier field | | | | | defined in GTP-U | +-------+-----------------+-------------|------------------------| | TBD4 | gtpuSequenceNum | unsigned16 | 16-bit sequence number | | | | identifier | field defined in GTP-U | +-------+-----------------+-------------|------------------------| | TBD5 | gtpuQFI | unsigned8 | 8-bit QoS flow | | | | | identifier field | | | | identifier | defined in PDU Session | | | | | Container extension | | | | | header of GTP-U | +-------+-----------------+-------------|------------------------| | TBD6 | gtpuPduType | unsigned8 | 8-bit PDU Type field | | | | identifier | defined in PDU Session | | | | | Container extension | | | | | header of GTP-U | +-------+-----------------+-------------+------------------------+ Table 1: GTP-U IEs in the "IPFIX Information Elements" Registry 6. Acknowledgements The authors would like to thank Ketan Talaulikar and Dhananjay Patki for their reviews and valuable comments. 7. Contributors Cristian Staicu Bell Canada Email: cristian.staicu@bell.ca Kandhla Chandi Bell Canada Email: kandhla.chandi@bell.ca Voyer, et al. Expires 3 August 2024 [Page 5] Internet-Draft IPFIX support for GTP-U January 2024 8. Security Considerations There exists no extra security considerations regarding allocation of these IPFIX IEs compared to [RFC7012]. The IEs described in this document export provider plane data metrics on how packets are being forwarded in 5G network. Applications and operators using the IEs described in this document must evaluate the sensitivity of this information in their implementation context, and apply the data-at-rest storage guidance in Section 11.8 of [RFC7011] as appropriate. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [TS.29281] 3GPP, "General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U)", Version 17.4.0, 3GPP TS 29.281, September 2022. 9.2. Informative References [IANA-IPFIX] "IANA, "IP Flow Information Export (IPFIX) Entities"", . Voyer, et al. Expires 3 August 2024 [Page 6] Internet-Draft IPFIX support for GTP-U January 2024 Appendix A. IPFIX Encoding Examples In this section, an example is provided to show IPFIX encoding format for the GTP-U introduced IEs. Template definition and data set corresponding to an observed GTP-U header is illustrated below. Observed GTP-U Header: Flags = 0x36, Message Type = 0xff, TEID = 0x1, Sequence number = 0x0000, Next extension header type = 0x85 (PDU Session container), PDU Type = 0, QFI = 8 A.1. Template Record A.1.1. Template Record and Data Set Sample template consisting of the GTP-U IEs: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SET ID = 2 | Length = 32 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 256 | Field Count = 6 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| gtpuFlags = TBD1 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| gtpuMsgType = TBD2 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| gtpuTEid = TBD3 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| gtpuSequenceNum = TBD4 | Field Length = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| gtpuQFI = TBD5 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| gtpuPduType = TBD6 | Field Length = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Sample Template Record In this example, the Template ID is 256, which will be used in the Data Record. The data set is represented as follows: Voyer, et al. Expires 3 August 2024 [Page 7] Internet-Draft IPFIX support for GTP-U January 2024 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SET ID = 256 | Length = 14 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | gtpuFlags | gtpuMsgType | gtpuTEid = 0x1 | | = 0x36 | = 0xff | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | gtpuSequenceNum = 0x0000 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | gtpuQFI = 8 | gtpuPduType | | | = 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Data Set Encoding Format Authors' Addresses Daniel Voyer Bell Canada Email: daniel.voyer@bell.ca Sriram Gopalakrishnan Cisco Systems India Email: sriragop@cisco.com Ralu Johny Cisco Systems India Email: rjohny@cisco.com Voyer, et al. Expires 3 August 2024 [Page 8]