Export of UDP Options Information in IP Flow Information Export (IPFIX)

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 July 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

IP Flow Information Export (IPFIX) [RFC7011] is a protocol that is widely deployed in operators networks for traffic management purposes. The protocol specifies the encoding of a set of basic data types and how the various Information Elements (IEs) are transmitted. In order to support the export of new flow-related measurement data, new IEs can be defined and registered in a dedicated IANA registry [IANA-IPFIX] for interoperability.¶

This document specifies new IPFIX Information Elements for UDP options (Section 5). A brief overview of UDP option is provided in Section 3.¶

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.¶

This document uses the terms defined in Section 3 of [I-D.ietf-tsvwg-udp-options] and [RFC7011].¶

3. UDP Options at a Glance

UDP [RFC0768] does not support an extension mechanism similar to the options supported by other transport protocols, such as TCP [RFC9293], SCTP [RFC9260], or DCCP [RFC4340]. Such a mechanism can be useful for various applications, e.g., discover a path MTU or share timestamps. To fill that void, [I-D.ietf-tsvwg-udp-options] extends UDP with a mechanism to insert extensions in datagrams. To do so, and unlike the conventional approach that relies upon transport headers, [I-D.ietf-tsvwg-udp-options] uses trailers. Concretely, UDP options are placed in the surplus area (that is, the area of an IP payload that follows a UDP packet). See Figure 1. An example of the use of UDP options is described in [I-D.ietf-tsvwg-udp-options-dplpmtud].¶

                       IP transport payload
          <------------------------------------------------->
+--------+---------+----------------------+------------------+
| IP Hdr | UDP Hdr |     UDP user data    |   surplus area   |
+--------+---------+----------------------+------------------+
          <------------------------------>
                     UDP Length

Section 5.1 introduces a new IE to export the observed UDP options.¶

Options indicated by Kind values in the range 0-191 are called SAFE options because they do not alter the UDP data payload. Such options can be silently ignored by receivers without affecting the meaning of the UDP user data (Section 9 of [I-D.ietf-tsvwg-udp-options]).¶

Options indicated by Kind values in the range 192-255 are called UNSAFE options. Such options are not safe to ignore (Section 10 of [I-D.ietf-tsvwg-udp-options]).¶

[I-D.ietf-tsvwg-udp-options] reserves two options for experiements: the Experimental option (EXP, Kind=127) for SAFE options and the UNSAFE Experimental option (UEXP, Kind=254). For both options, Experimental ID (ExIDs) are used to differentiate concurrent use of these options. Known ExIDs are expected to be registered within IANA. Section 5.2 specifies a new IPFIX to export observed ExIDs in the EXP options. Also, Section 5.3 specifies a new IPFIX to export observed ExIDs in the UEXP options. Only 16-bits ExIDs are supported.¶

This document does not intend to elaborate operational guidance/implications of UDP options. The document focuses exclusively on exporting observed UDP options in datagrams. The motivation for exporting such data is similar to the one for exporting TCP options (tcpOptions IE) or IPv6 Extension Headers (ipv6ExtensionHeaders).¶

4. Security Considerations

This document does not introduce new security considerations other than those already discussed in [RFC7012].¶

5. IANA Considerations

This document requests IANA to add the following new IEs to the IANA registry entitled "IP Flow Information Export (IPFIX) Entities" [IANA-IPFIX].¶

+----------+----------+----------+----------+
|udpOptions|udpOptions|udpOptions|udpOptions|
|Instance#1|Instance#2|Instance#3|Instance#4|
+----------+----------+----------+----------+
    0-63      64-127    128-191    192-255
    Range      Range     Range       Range

Acknowledgments

TODO acknowledge.¶

Authors' Addresses