Export of GTP-U Information in IP Flow Information Export (IPFIX)
draft-voyersriram-opsawg-ipfix-gtpu-06
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Daniel Voyer , Sriram Gopalakrishnan , Thomas Graf , Benoît Claise , Vyasraj Satyanarayana | ||
| Last updated | 2024-04-25 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-voyersriram-opsawg-ipfix-gtpu-06
Operations D. Voyer
Internet-Draft Bell Canada
Intended status: Standards Track S. Gopalakrishnan
Expires: 27 October 2024 Cisco Systems
T. Graf
Swisscom
B. Claise
Huawei
V. Satyanarayana
Juniper Networks
25 April 2024
Export of GTP-U Information in IP Flow Information Export (IPFIX)
draft-voyersriram-opsawg-ipfix-gtpu-06
Abstract
This document introduces IP Flow Information Export Information
Elements to identify information contained 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/.
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 27 October 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
Voyer, et al. Expires 27 October 2024 [Page 1]
Internet-Draft IPFIX support for GTP-U April 2024
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
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IPFIX GTP-U Information Elements . . . . . . . . . . . . . . 3
4. Sample Use Cases . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5.1. gtpuFlags . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2. gtpuMsgType . . . . . . . . . . . . . . . . . . . . . . . 6
5.3. gtpuTEid . . . . . . . . . . . . . . . . . . . . . . . . 6
5.4. gtpuSequenceNum . . . . . . . . . . . . . . . . . . . . . 7
5.5. gtpuQFI . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.6. gtpuPduType . . . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
8. Implementation Status . . . . . . . . . . . . . . . . . . . . 9
8.1. Cisco IOS XR . . . . . . . . . . . . . . . . . . . . . . 9
9. Security Considerations . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. IPFIX Encoding Examples . . . . . . . . . . . . . . 11
A.1. Template Record . . . . . . . . . . . . . . . . . . . . . 11
A.1.1. Template Record and Data Set . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
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.
Voyer, et al. Expires 27 October 2024 [Page 2]
Internet-Draft IPFIX support for GTP-U April 2024
Some examples are provided in Appendix A.
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 which
unambiguously identifies a tunnel endpoint in the receiving GTP-U
protocol entity for a given UDP/IP endpoint.
gtpuSequenceNum
16-bit sequence number field defined in the GTP-U. This field is
interpreted based on the corresponding flag value from gtpuFlags.
Voyer, et al. Expires 27 October 2024 [Page 3]
Internet-Draft IPFIX support for GTP-U April 2024
gtpuQFI
6-bit QoS flow identifier field defined in PDU Session Container
extension header of GTP-U.
gtpuPduType
4-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
IANA has added the following new IEs to the "IPFIX Information
Elements" registry [RFC7012] available at [IANA-IPFIX].
Table 1 lists the GTP-U IEs:
Voyer, et al. Expires 27 October 2024 [Page 4]
Internet-Draft IPFIX support for GTP-U April 2024
+-------+-----------------+
|Element| Name |
| | |
| ID | |
| | |
+-------+-----------------+
| 505 | gtpuFlags |
| | |
+-------+-----------------+
| 506 | gtpuMsgType |
| | |
+-------+-----------------+
| 507 | gtpuTEid |
| | |
| | |
+-------+-----------------+
| 508 | gtpuSequenceNum |
| | |
+-------+-----------------+
| 509 | gtpuQFI |
| | |
| | |
| | |
| | |
+-------+-----------------+
| 510 | gtpuPduType |
| | |
| | |
| | |
+-------+-----------------+
Table 1: GTP-U IEs in the "IPFIX Information Elements" Registry
5.1. gtpuFlags
Name: gtpuFlags
ElementID: 505
Description: 8-bit flags field indicating the version of GTP-U
protocol, protocol type and presence of extension header, sequence
number and N-PDU number defined in section 5.1 of the 3GPP
specification [TS.29281].
Abstract Data Type: unsigned8
Data Type Semantics: flags
Voyer, et al. Expires 27 October 2024 [Page 5]
Internet-Draft IPFIX support for GTP-U April 2024
Additional Information: Refer to section 5.1 of the 3GPP
specification [TS.29281].
Reference: [RFC-to-be]
5.2. gtpuMsgType
Name: gtpuMsgType
ElementID: 506
Description: 8-bit Message type field indicating the type of GTP-U
message defined in section 5.1 of the 3GPP specification
[TS.29281].
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Additional Information: Refer to section 5.1 of the 3GPP
specification [TS.29281].
Reference: [RFC-to-be]
5.3. gtpuTEid
Name: gtpuTEid
ElementID: 507
Description: 32-bit tunnel endpoint identifier field defined in
section 5.1 of the 3GPP specification [TS.29281]. This field
unambiguously identifies a tunnel endpoint in the receiving GTP-U
protocol entity for a given UDP/IP endpoint. The receiving side
of a GTP tunnel locally assigns the TEID value the transmitting
side has to use. The TEID values are exchanged between tunnel
endpoints using control plane messages.
Abstract Data Type: unsigned32
Data Type Semantics: identifier
Additional Information: Refer to section 5.1 of the 3GPP
specification [TS.29281].
Reference: [RFC-to-be]
Voyer, et al. Expires 27 October 2024 [Page 6]
Internet-Draft IPFIX support for GTP-U April 2024
5.4. gtpuSequenceNum
Name: gtpuSequenceNum
ElementID: 508
Description: 16-bit sequence number field defined in section 5.1
(Optional Fields) of the 3GPP specification [TS.29281].
Abstract Data Type: unsigned16
Data Type Semantics: identifier
Additional Information: Refer to section 5.1 of the 3GPP
specification [TS.29281].
Reference: [RFC-to-be]
5.5. gtpuQFI
Name: gtpuQFI
ElementID: 509
Description: 6-bit QoS flow identifier field defined in PDU Session
Container extension header of GTP-U. This is defined in section
5.5.3.3 of the 3GPP specification [TS.38415]. This is used to
determine the QoS flow and QoS profile which are associated with
the received packet.
The basic encoding is 8 bits. The layout of basic encoding is as
follows:
MSB - 0 1 2 3 4 5 6 7 - LSB
+----+----+----+----+----+----+----+----+
|Reserved | 6 bit QFI value |
+----+----+----+----+----+----+----+----+
Examples:
value : 0x08
binary: 00001000
decode: 001000 - QFI value
Voyer, et al. Expires 27 October 2024 [Page 7]
Internet-Draft IPFIX support for GTP-U April 2024
value : 0x3e
binary: 00111110
decode: 111110 - QFI value
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Additional Information: Refer to section 5.5.3.3 of the 3GPP
specification [TS.38415] and section 5.7.1.1 from 3GPP
specification [TS.23501] for additional details.
Reference: [RFC-to-be]
5.6. gtpuPduType
Name: gtpuPduType
ElementID: 510
Description: 4-bit PDU type field defined in PDU Session Container
extension header of GTP-U. This is defined in section 5.5.3 of
the 3GPP specification [TS.38415]. This field indicates the
structure of the PDU session user plane frame.
The basic encoding is 8 bits. The layout of basic encoding is as
follows:
MSB - 0 1 2 3 4 5 6 7 - LSB
+----+----+----+----+----+----+----+----+
| Reserved | 4 bit PDU Type |
+----+----+----+----+----+----+----+----+
Examples:
value : 0x01
binary: 00000001
decode: 0001 - PDU Type value
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Voyer, et al. Expires 27 October 2024 [Page 8]
Internet-Draft IPFIX support for GTP-U April 2024
Additional Information: Refer to section 5.5.3 of the 3GPP
specification [TS.38415].
Reference: [RFC-to-be]
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
Ralu Johny
Cisco
Email: rjohny@cisco.com
8. Implementation Status
Note to the RFC-Editor: Please remove this section before publishing.
8.1. Cisco IOS XR
Cisco implemented the following IEs as part of a test implementation
in the IOS XR platform:
* gtpuFlags
* gtpuMsgType
* gtpuTEid
* gtpuSequenceNum
* gtpuQFI
* gtpuPduType
Voyer, et al. Expires 27 October 2024 [Page 9]
Internet-Draft IPFIX support for GTP-U April 2024
9. Security Considerations
There exists no extra security considerations regarding allocation of
these IPFIX IEs compared to [RFC7012].
The IEs described in this document export GTP user 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.
10. References
10.1. 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,
<https://www.rfc-editor.org/info/rfc2119>.
[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,
<https://www.rfc-editor.org/info/rfc7011>.
[RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model
for IP Flow Information Export (IPFIX)", RFC 7012,
DOI 10.17487/RFC7012, September 2013,
<https://www.rfc-editor.org/info/rfc7012>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[TS.23501] 3GPP, "5G; System architecture for the 5G System (5GS)",
Version 17.11.0, 3GPP TS 23.501, January 2024.
[TS.29281] 3GPP, "General Packet Radio System (GPRS) Tunnelling
Protocol User Plane (GTPv1-U)", Version 17.4.0, 3GPP
TS 29.281, October 2022.
Voyer, et al. Expires 27 October 2024 [Page 10]
Internet-Draft IPFIX support for GTP-U April 2024
[TS.38415] 3GPP, "NG-RAN; PDU Session User Plane Protocol)", Version
17.1.0, 3GPP TS 38.415, February 2024.
10.2. Informative References
[IANA-IPFIX]
"IANA, "IP Flow Information Export (IPFIX) Entities"",
<https://www.iana.org/assignments/ipfix/ipfix.xhtml>.
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:
Voyer, et al. Expires 27 October 2024 [Page 11]
Internet-Draft IPFIX support for GTP-U April 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 = 2 | Length = 32 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 256 | Field Count = 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| gtpuFlags = 505 | Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| gtpuMsgType = 506 | Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| gtpuTEid = 507 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| gtpuSequenceNum = 508 | Field Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| gtpuQFI = 509 | Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| gtpuPduType = 510 | 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:
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
Voyer, et al. Expires 27 October 2024 [Page 12]
Internet-Draft IPFIX support for GTP-U April 2024
Authors' Addresses
Daniel Voyer
Bell Canada
Email: daniel.voyer@bell.ca
Sriram Gopalakrishnan
Cisco Systems
India
Email: sriragop@cisco.com
Thomas Graf
Swisscom
Email: thomas.graf@swisscom.com
Benoit Claise
Huawei
Email: benoit.claise@huawei.com
Vyasraj Satyanarayana
Juniper Networks
Email: vyasraj@juniper.net
Voyer, et al. Expires 27 October 2024 [Page 13]