IPv6 IOAM options: IPv6 Options for In Situ Operations, Administration, and Maintenance (IOAM)
How IPv6 packets carry in-band telemetry notes in hop-by-hop and destination options.
Bhandari, S., Ed. and F. Brockners, Ed., "IPv6 Options for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9486, DOI 10.17487/RFC9486, September 2023, <https://www.rfc-editor.org/info/rfc9486>.
@misc{rfc9486,
series = {Request for Comments},
number = 9486,
howpublished = {RFC 9486},
publisher = {RFC Editor},
doi = {10.17487/RFC9486},
url = {https://www.rfc-editor.org/info/rfc9486},
author = {S. Bhandari and F. Brockners},
title = {{IPv6 Options for In Situ Operations, Administration, and Maintenance (IOAM)}},
pagetotal = 10,
year = 2023,
month = sep,
} RFC text
Contents
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
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. 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: cpignata@cisco.com
Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
John Leddy
Email: john@leddy.net
Stephen Youell
JP Morgan Chase
25 Bank Street
London
E14 5JP
United Kingdom
Email: stephen.youell@jpmorgan.com
Tal Mizrahi
Huawei Network.IO Innovation Lab
Israel
Email: tal.mizrahi.phd@gmail.com
Aviv Kfir
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
United States of America
Email: avivk@mellanox.com
Barak Gafni
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
United States of America
Email: gbarak@mellanox.com
Petr Lapukhov
Facebook
1 Hacker Way
Menlo Park, CA 94025
United States of America
Email: petr@fb.com
Mickey Spiegel
Barefoot Networks, an Intel company
4750 Patrick Henry Drive
Santa Clara, CA 95054
United States of America
Email: mickey.spiegel@intel.com
Suresh Krishnan
Kaloom
Email: suresh@kaloom.com
Rajiv Asati
Cisco Systems, Inc.
7200 Kit Creek Road
Research Triangle Park, NC 27709
United States of America
Email: rajiva@cisco.com
Mark Smith
PO BOX 521
Heidelberg VIC 3084
Australia
Email: markzzzsmith+id@gmail.com
Authors' Addresses
Shwetha Bhandari (editor)
Thoughtspot
3rd Floor, Indiqube Orion
24th Main Rd, Garden Layout, HSR Layout
Bangalore 560 102
Karnataka
India
Email: shwetha.bhandari@thoughtspot.com
Frank Brockners (editor)
Cisco Systems, Inc.
Hansaallee 249, 3rd Floor
40549 Duesseldorf
Germany
Email: fbrockne@cisco.com
AI ELI5
On this page
§1What This RFC Adds to IOAM
In situ Operations, Administration, and Maintenance (IOAM) records operational and telemetry information in the packet while it travels between two points in the network. The concepts and the IOAM Data-Fields themselves are defined in RFC 9197.
RFC 9486 covers one narrow job: how those data fields are encapsulated in IPv6 (RFC 8200), and what a network must do to deploy IPv6-encapsulated IOAM safely. It says IOAM in IPv6 is used to enhance diagnostics and complements other mechanisms such as the IPv6 Performance and Diagnostic Metrics (PDM) Destination Option in RFC 8250.
The big rulebook already says what notes a packet can carry. This short RFC only says where in an IPv6 packet those notes get pinned.
§2The IOAM Option Format
IOAM data is carried in IPv6 extension headers, either the hop-by-hop options header or the destination options header. Several options with the same option type MAY appear in one such header, as long as their content is distinct. A packet with IOAM can also carry other extension headers that comply with RFC 8200.
The option has an 8-bit Option-Type, an 8-bit Opt Data Len (the option length in octets, not counting the first 2 octets), an 8-bit Reserved field that MUST be zero when sent by the source, an 8-bit IOAM Opt-Type taken from RFC 9197, and then variable-length Option Data specific to the option type.
All of these options must be aligned on multiples of 4 bytes, so the fields from RFC 9197 sit at a multiple-of-4 offset from the start of the options header. Because an IPv6 option can be at most 255 octets long, the total IOAM data in one option is also limited to 255 octets.
The note area has a label that says what kind of note it is and how long it is. The notes must start on neat boundaries, and the whole pile cannot be longer than 255 bytes.
| Field | Name | Size | Value | Description |
|---|---|---|---|---|
OPTION-TYPE | Option-Type | 1 byte | IPv6 option type identifier for IOAM. | |
OPT-DATA-LEN | Opt Data Len | 1 byte | Length of the option in octets, not including the first 2 octets. | |
RESERVED | Reserved | 1 byte | MUST be set to zero by the source. | |
IOAM-OPT-TYPE | IOAM Opt-Type | 1 byte | Which IOAM option this is, as defined in RFC 9197. |
§3Which IOAM Option Types Map Where
Four IOAM option types are mapped onto IPv6. The Pre-allocated Trace Option (RFC 9197 Section 4.4) and the Proof of Transit (POT) option (Section 4.5) are carried as IPv6 options in the hop-by-hop header, with Option-Type 0x31.
The Edge-to-Edge (E2E) option (RFC 9197 Section 4.6) is carried in the destination options header, with Option-Type 0x11. The Direct Export (DEX) option from RFC 9326 is described as a hop-by-hop option, also written with Option-Type 0x11 in the text. In each case, the IOAM Opt-Type field says which of the four options it is.
There are four kinds of notes. Some are read by every stop along the way, and one kind is only read at the very end of the trip.
| IOAM option | Option-Type | Header |
|---|---|---|
| Pre-allocated Trace | 0x31 | Hop-by-hop |
| Proof of Transit (POT) | 0x31 | Hop-by-hop |
| Edge-to-Edge (E2E) | 0x11 | Destination |
| Direct Export (DEX) | 0x11 | Hop-by-hop |
§4Deployment Rules for IOAM-Domains
Four numbered considerations (C1 to C4) apply. C1: IOAM MUST be deployed in an IOAM-Domain, a set of nodes that use IOAM, bounded by its edge and expected to be managed by one administrative entity. C2: adding IOAM data MUST NOT change how routers forward packets, including under Equal-Cost Multipath (ECMP). IOAM MUST be explicitly enabled per interface on every node in the domain, and a router MUST ignore IOAM options on an interface that is not enabled.
C3: the MTU of transit routers and switches must be set so that adding IOAM data never triggers an ICMP Packet Too Big message and a dropped packet, and IOAM must not grow packets beyond the path MTU tolerance. C4: RFC 8200 precludes inserting IOAM data into the original IPv6 header of in-flight packets, so a transit node that adds IOAM MUST add an additional IPv6 header and put the IOAM data there.
Telemetry stickers may only be used inside your own club. Adding them must not send the packet down a different road, and the packet must not become too big to fit through the doors.
§5Domains Bounded by Hosts or by Routers
Where the IOAM-Domain edge is at the hosts, the hosts themselves add and remove the IOAM data fields, placing them directly in the IPv6 packet as hop-by-hop or destination options.
Where the edge is at network devices such as routers, those devices add and remove the data. They encapsulate the IOAM Data-Fields in an additional, outer IPv6 header, which fits the C4 rule above.
Either the sender and receiver themselves put on and take off the stickers, or the post offices at the edge wrap the letter in an extra envelope and put the stickers on that.
§6Security and Trust
The RFC assumes a trust model: any node that adds, removes or modifies IOAM data is assumed to be allowed to. By default, packets with IOAM extension headers MUST NOT leak across the domain boundary, and boundary routers MUST filter both incoming and outgoing traffic that carries IPv6 extension headers with IOAM information. A node should only change IOAM headers on a validated directive from a trusted source.
The security considerations of RFC 9197, RFC 8200, RFC 8250 and RFC 9098 also apply. The IOAM-Domain does not rely on the IP Authentication Header (RFC 4302) to protect IOAM options, and using IOAM with AH is not defined here; future documents may define it.
Everyone inside the club is trusted to write on the stickers, so guards at the door must stop sticker-covered packets from going out or coming in.
§7IANA Option-Type Assignments
IANA assigned two IPv6 Option-Types in the "Destination Options and Hop-by-Hop Options" subregistry. Both are described as "IOAM Destination Option and IOAM Hop-by-Hop Option".
Value 0x11 has act bits 00, chg bit 0 and rest 10001. Value 0x31 has act bits 00, chg bit 1 and rest 10001.
The official numbering office handed out two ID numbers so that routers can recognise IOAM notes.