Internet Engineering Task Force (IETF) S. Bhandari, Ed.

Internet Engineering Task Force (IETF) S. Bhandari, Ed.
Request for Comments: 9486 Thoughtspot
Category: Standards Track F. Brockners, Ed.
ISSN: 2070-1721 Cisco
September 2023

IPv6 Options for In Situ Operations, Administration, and Maintenance
(IOAM)

Abstract

In situ Operations, Administration, and Maintenance (IOAM) records
operational and telemetry information in the packet while the packet
traverses a path between two points in the network. This document
outlines how IOAM Data-Fields are encapsulated in IPv6.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9486.

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
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Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.

Table of Contents

1. Introduction
2. Conventions
2.1. Requirements Language
2.2. Abbreviations
3. In situ OAM Metadata Transport in IPv6
4. IOAM Deployment in IPv6 Networks
4.1. Considerations for IOAM Deployment and Implementation in
IPv6 Networks
4.2. IOAM-Domains Bounded by Hosts
4.3. IOAM-Domains Bounded by Network Devices
5. Security Considerations
5.1. Applicability of Authentication Header (AH)
6. IANA Considerations
7. References
7.1. Normative References
7.2. Informative References
Acknowledgements
Contributors
Authors' Addresses

1. Introduction

In situ Operations, Administration, and Maintenance (IOAM) records
operational and telemetry information in the packet while the packet
traverses a path between two points in the network. IOAM concepts
and associated nomenclature as well as IOAM Data-Fields are defined
in [RFC9197]. This document outlines how IOAM Data-Fields are
encapsulated in IPv6 [RFC8200] and discusses deployment requirements
for networks that use IPv6-encapsulated IOAM Data-Fields.

The terms "encapsulation" and "decapsulation" are used in this
document in the same way as in [RFC9197]: An IOAM encapsulating node
incorporates one or more IOAM Option-Types into packets that IOAM is
enabled for.

2. Conventions

2.1. Requirements Language

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.

2.2. Abbreviations

Abbreviations used in this document:

E2E: Edge-to-Edge

IOAM: In situ Operations, Administration, and Maintenance as
defined in [RFC9197]

OAM: Operations, Administration, and Maintenance

POT: Proof of Transit

3. In situ OAM Metadata Transport in IPv6

IOAM in IPv6 is used to enhance diagnostics of IPv6 networks. It
complements other mechanisms designed to enhance diagnostics of IPv6
networks, such as the "IPv6 Performance and Diagnostic Metrics (PDM)
Destination Option" described in [RFC8250].

At the time this document was written, several implementations of
IOAM for IPv6 exist, e.g., IOAM for IPv6 in the Linux Kernel
(supported from Kernel version 5.15 onward, IPv6 IOAM in Linux Kernel
(https://github.com/torvalds/linux/
commit/7c804e91df523a37c29e183ea2b10ac73c3a4f3d)) and IOAM for IPv6
in Vector Packet Processing (VPP) (https://docs.fd.io/vpp/17.04/
ioam_ipv6_doc.html).

IOAM Data-Fields can be encapsulated with two types of extension
headers in IPv6 packets -- either the hop-by-hop options header or
the destination options header. Multiple options with the same
option type MAY appear in the same hop-by-hop options or destination
options header with distinct content.

An IPv6 packet carrying IOAM data in an extension header can have
other extension headers, compliant with [RFC8200].

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option-Type | Opt Data Len | Reserved | IOAM Opt-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| | |
. . I
. . O
. . A
. . M
. . .
. Option Data . O
. . P
. . T
. . I
. . O
. . N
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+

Figure 1: IPv6 Hop-by-Hop and Destination Option Format for
Carrying IOAM Data- Fields

Option-Type: 8-bit option type identifier as defined in Section 6.

Opt Data Len: 8-bit unsigned integer. Length of this option, in
octets, not including the first 2 octets.

Reserved: 8-bit field MUST be set to zero by the source.

IOAM Option-Type: Abbreviated to "IOAM Opt-Type" in the diagram
above: 8-bit field as defined in Section 4.1 of [RFC9197].

Option Data: Variable-length field. The data is specific to the
Option-Type, as detailed below.

Pre-allocated Trace Option: The IOAM Pre-allocated Trace Option-
Type, defined in Section 4.4 of [RFC9197], is represented as an
IPv6 option in the hop-by-hop extension header:

Option-Type: 0x31 (8-bit identifier of the IPv6 Option-Type
for IOAM).

IOAM Type: IOAM Pre-allocated Trace Option-Type.

Proof of Transit Option-Type: The IOAM POT Option-Type, defined
in Section 4.5 of [RFC9197], is represented as an IPv6 option
in the hop-by-hop extension header:

Option-Type: 0x31 (8-bit identifier of the IPv6 Option-Type
for IOAM).

IOAM Type: IOAM POT Option-Type.

Edge-to-Edge Option: The IOAM E2E Option, defined in Section 4.6
of [RFC9197], is represented as an IPv6 option in destination
extension header:

Option-Type: 0x11 (8-bit identifier of the IPv6 Option-Type
for IOAM).

IOAM Type: IOAM E2E Option-Type.

Direct Export (DEX) Option: The IOAM Direct Export Option-Type,
defined in Section 3.2 of [RFC9326], is represented as an IPv6
option in the hop-by-hop extension header:

Option-Type: 0x11 (8-bit identifier of the IPv6 Option-Type
for IOAM).

IOAM Type: IOAM Direct Export (DEX) Option-Type.

All the IOAM IPv6 options defined here have alignment requirements.
Specifically, they all require alignment on multiples of 4 bytes.
This ensures that fields specified in [RFC9197] are aligned at a
multiple-of-4 offset from the start of the hop-by-hop and destination
options header.

IPv6 options can have a maximum length of 255 octets. Consequently,
the total length of IOAM Option-Types including all data fields is
also limited to 255 octets when encapsulated into IPv6.

4. IOAM Deployment in IPv6 Networks

4.1. Considerations for IOAM Deployment and Implementation in IPv6
Networks

IOAM deployments in IPv6 networks MUST take the following
considerations and requirements into account.

C1: IOAM MUST be deployed in an IOAM-Domain. An IOAM-Domain is a
set of nodes that use IOAM. An IOAM-Domain is bounded by its
perimeter or edge. The set of nodes forming an IOAM-Domain may
be connected to the same physical infrastructure (e.g., a
service provider's network). They may also be remotely
connected to each other (e.g., an enterprise VPN or an overlay).
It is expected that all nodes in an IOAM-Domain are managed by
the same administrative entity. Please refer to [RFC9197] for
more details on IOAM-Domains.

C2: Implementations of IOAM MUST ensure that the addition of IOAM
Data-Fields does not alter the way routers forward packets or
the forwarding decisions they make. Packets with added IOAM
information must follow the same path within the domain as an
identical packet without IOAM information would, even in the
presence of Equal-Cost Multipath (ECMP). This behavior is
important for deployments where IOAM Data-Fields are only added
"on-demand". Implementations of IOAM MUST ensure that ECMP
behavior for packets with and without IOAM Data-Fields is the
same. In order for IOAM to work in IPv6 networks, IOAM MUST be
explicitly enabled per interface on every node within the IOAM-
Domain. Unless a particular interface is explicitly enabled
(i.e., explicitly configured) for IOAM, a router MUST ignore
IOAM Options.

C3: In order to maintain the integrity of packets in an IOAM-Domain,
the Maximum Transmission Unit (MTU) of transit routers and
switches must be configured to a value that does not lead to an
"ICMP Packet Too Big" error message being sent to the originator
and the packet being dropped. The PMTU tolerance range must be
identified, and IOAM encapsulation operations or data field
insertion must not exceed this range. Control of the MTU is
critical to the proper operation of IOAM. The PMTU tolerance
must be identified through configuration, and IOAM operations
must not exceed the packet size beyond PMTU.

C4: [RFC8200] precludes insertion of IOAM data directly into the
original IPv6 header of in-flight packets. IOAM deployments
that do not encapsulate/decapsulate IOAM on the host but desire
to encapsulate/decapsulate IOAM on transit nodes MUST add an
additional IPv6 header to the original packet. IOAM data is
added to this additional IPv6 header.

4.2. IOAM-Domains Bounded by Hosts

For deployments where the IOAM-Domain is bounded by hosts, hosts will
perform the operation of IOAM Data-Field encapsulation and
decapsulation, i.e., hosts will place the IOAM Data-Fields directly
in the IPv6 header or remove the IOAM Data-Fields directly from the
IPv6 header. IOAM data is carried in IPv6 packets as hop-by-hop or
destination options as specified in this document.

4.3. IOAM-Domains Bounded by Network Devices

For deployments where the IOAM-Domain is bounded by network devices,
network devices such as routers form the edge of an IOAM-Domain.
Network devices will perform the operation of IOAM Data-Field
encapsulation and decapsulation. Network devices will encapsulate
IOAM Data-Fields in an additional, outer, IPv6 header that carries
the IOAM Data-Fields.

5. Security Considerations

This document describes the encapsulation of IOAM Data-Fields in
IPv6. For general IOAM security considerations, see [RFC9197].
Security considerations of the specific IOAM Data-Fields for each
case (i.e., Trace, POT, and E2E) are also described and defined in
[RFC9197].

As this document describes new options for IPv6, the security
considerations of [RFC8200] and [RFC8250] apply.

From a network-protection perspective, there is an assumed trust
model such that any node that adds IOAM to a packet, removes IOAM
from a packet, or modifies IOAM Data-Fields of a packet is assumed to
be allowed to do so. By default, packets that include IPv6 extension
headers with IOAM information MUST NOT be leaked through the
boundaries of the IOAM-Domain.

IOAM-Domain boundary routers MUST filter any incoming traffic from
outside the IOAM-Domain that contains IPv6 extension headers with
IOAM information. IOAM-Domain boundary routers MUST also filter any
outgoing traffic leaving the IOAM-Domain that contains IPv6 extension
headers with IOAM information.

In the general case, an IOAM node only adds, removes, or modifies an
IPv6 extension header with IOAM information, if the directive to do
so comes from a trusted source and the directive is validated.

Problems may occur if the above behaviors are not implemented or if
the assumed trust model is violated (e.g., through a security
breach). In addition to the security considerations discussed in
[RFC9197], the security considerations associated with IPv6 extension
headers listed in [RFC9098] apply.

5.1. Applicability of Authentication Header (AH)

The network devices in an IOAM-Domain are trusted to add, update, and
remove IOAM options according to the constraints specified in
[RFC8200]. IOAM-Domain does not rely on the AH as defined in
[RFC4302] to secure IOAM options. The use of IOAM options with AH
and its processing are not defined in this document. Future
documents may define the use of IOAM with AH and its processing.

6. IANA Considerations

IANA has assigned the IPv6 Option-Types from the "Destination Options
and Hop-by-Hop Options" subregistry of "Internet Protocol Version 6
(IPv6) Parameters" <https://www.iana.org/assignments/
ipv6-parameters/>.

+=======+===================+===================+===========+
| Hex | Binary Value | Description | Reference |
| Value +=====+=====+=======+ | |
| | act | chg | rest | | |
+=======+=====+=====+=======+===================+===========+
| 0x11 | 00 | 0 | 10001 | IOAM Destination | RFC 9486 |
| | | | | Option and IOAM | |
| | | | | Hop-by-Hop Option | |
+-------+-----+-----+-------+-------------------+-----------+
| 0x31 | 00 | 1 | 10001 | IOAM Destination | RFC 9486 |
| | | | | Option and IOAM | |
| | | | | Hop-by-Hop Option | |
+-------+-----+-----+-------+-------------------+-----------+

Table 1

7. References

7.1. 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>.

[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>.

[RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi,
Ed., "Data Fields for In Situ Operations, Administration,
and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197,
May 2022, <https://www.rfc-editor.org/info/rfc9197>.

[RFC9326] Song, H., Gafni, B., Brockners, F., Bhandari, S., and T.
Mizrahi, "In Situ Operations, Administration, and
Maintenance (IOAM) Direct Exporting", RFC 9326,
DOI 10.17487/RFC9326, November 2022,
<https://www.rfc-editor.org/info/rfc9326>.

7.2. Informative References

[IPV6-RECORD-ROUTE]
Kitamura, H., "Record Route for IPv6 (RR6) Hop-by-Hop
Option Extension", Work in Progress, Internet-Draft,
draft-kitamura-ipv6-record-route-00, 17 November 2000,
<https://datatracker.ietf.org/doc/html/draft-kitamura-
ipv6-record-route-00>.

[RFC4302] Kent, S., "IP Authentication Header", RFC 4302,
DOI 10.17487/RFC4302, December 2005,
<https://www.rfc-editor.org/info/rfc4302>.

[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.

[RFC8250] Elkins, N., Hamilton, R., and M. Ackermann, "IPv6
Performance and Diagnostic Metrics (PDM) Destination
Option", RFC 8250, DOI 10.17487/RFC8250, September 2017,
<https://www.rfc-editor.org/info/rfc8250>.

[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, <https://www.rfc-editor.org/info/rfc9098>.

Acknowledgements

The authors would like to thank Tom Herbert, Éric Vyncke, Nalini
Elkins, Srihari Raghavan, Ranganathan T S, Karthik Babu Harichandra
Babu, Akshaya Nadahalli, Stefano Previdi, Hemant Singh, Erik
Nordmark, LJ Wobker, Mark Smith, Andrew Yourtchenko, and Justin
Iurman for the comments and advice. For the IPv6 encapsulation, this
document leverages concepts described in [IPV6-RECORD-ROUTE]. The
authors would like to acknowledge the work done by the author Hiroshi
Kitamura and people involved in writing it.

Contributors

This document was the collective effort of several authors. The text
and content were contributed by the editors and the coauthors listed
below.

Carlos Pignataro
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
United States of America
Email: [email protected]

Hannes Gredler
RtBrick Inc.
Email: [email protected]

John Leddy
Email: [email protected]

Stephen Youell
JP Morgan Chase
25 Bank Street
London
E14 5JP
United Kingdom
Email: [email protected]

Tal Mizrahi
Huawei Network.IO Innovation Lab
Israel
Email: [email protected]

Aviv Kfir
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
United States of America
Email: [email protected]

Barak Gafni
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
United States of America
Email: [email protected]

Petr Lapukhov
Facebook
1 Hacker Way
Menlo Park, CA 94025
United States of America
Email: [email protected]

Mickey Spiegel
Barefoot Networks, an Intel company
4750 Patrick Henry Drive
Santa Clara, CA 95054
United States of America
Email: [email protected]

Suresh Krishnan
Kaloom
Email: [email protected]

Rajiv Asati
Cisco Systems, Inc.
7200 Kit Creek Road
Research Triangle Park, NC 27709
United States of America
Email: [email protected]

Mark Smith
PO BOX 521
Heidelberg VIC 3084
Australia
Email: [email protected]

Authors' Addresses

Shwetha Bhandari (editor)
Thoughtspot
3rd Floor, Indiqube Orion
24th Main Rd, Garden Layout, HSR Layout
Bangalore 560 102
Karnataka
India
Email: [email protected]

Frank Brockners (editor)
Cisco Systems, Inc.
Hansaallee 249, 3rd Floor
40549 Duesseldorf
Germany
Email: [email protected]