Data Fields for In-situ OAM
draft-ietf-ippm-ioam-data-12
| Document | Type | Active Internet-Draft (ippm WG) | |
|---|---|---|---|
| Authors | Frank Brockners , Shwetha Bhandari , Tal Mizrahi | ||
| Last updated | 2021-03-25 (latest revision 2021-02-21) | ||
| Replaces | draft-ippm-ioam-data, draft-brockners-inband-oam-data | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | plain text xml pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Al Morton | ||
| Shepherd write-up | Show (last changed 2020-05-30) | ||
| IESG | IESG state | IESG Evaluation::Revised I-D Needed | |
| Action Holders |
|
||
| Consensus Boilerplate | Yes | ||
| Telechat date |
Has 5 DISCUSSes. Needs 4 more YES or NO OBJECTION positions to pass. |
||
| Responsible AD | Martin Duke | ||
| IESG note | In last call, the concern arose that there is no integrity protection for IOAM. While the normal use case is controlled networks where this is not a concern, the authors have created draft-brockners-ippm-ioam-data-integrity-01 to develop a design to enable integrity checks should IOAM be used over less secure networks. | ||
| Send notices to | Al Morton <acm@research.att.com> | ||
| IANA | IANA review state | IANA OK - Actions Needed | |
ippm F. Brockners, Ed.
Internet-Draft Cisco
Intended status: Standards Track S. Bhandari, Ed.
Expires: August 25, 2021 Thoughtspot
T. Mizrahi, Ed.
Huawei
February 21, 2021
Data Fields for In-situ OAM
draft-ietf-ippm-ioam-data-12
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
discusses the data fields and associated data types for in-situ OAM.
In-situ OAM data fields can be encapsulated into a variety of
protocols such as NSH, Segment Routing, Geneve, IPv6 (via extension
header), or IPv4. In-situ OAM can be used to complement OAM
mechanisms based on e.g. ICMP or other types of probe packets.
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 August 25, 2021.
Copyright Notice
Copyright (c) 2021 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
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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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Scope, Applicability, and Assumptions . . . . . . . . . . . . 5
5. IOAM Data-Fields, Types, Nodes . . . . . . . . . . . . . . . 6
5.1. IOAM Data-Fields and Option-Types . . . . . . . . . . . . 6
5.2. IOAM-Domains and types of IOAM Nodes . . . . . . . . . . 7
5.3. IOAM-Namespaces . . . . . . . . . . . . . . . . . . . . . 8
5.4. IOAM Trace Option-Types . . . . . . . . . . . . . . . . . 11
5.4.1. Pre-allocated and Incremental Trace Option-Types . . 13
5.4.2. IOAM node data fields and associated formats . . . . 17
5.4.2.1. Hop_Lim and node_id short format . . . . . . . . 18
5.4.2.2. ingress_if_id and egress_if_id . . . . . . . . . 18
5.4.2.3. timestamp seconds . . . . . . . . . . . . . . . . 19
5.4.2.4. timestamp subseconds . . . . . . . . . . . . . . 19
5.4.2.5. transit delay . . . . . . . . . . . . . . . . . . 19
5.4.2.6. namespace specific data . . . . . . . . . . . . . 20
5.4.2.7. queue depth . . . . . . . . . . . . . . . . . . . 20
5.4.2.8. Checksum Complement . . . . . . . . . . . . . . . 20
5.4.2.9. Hop_Lim and node_id wide . . . . . . . . . . . . 21
5.4.2.10. ingress_if_id and egress_if_id wide . . . . . . . 22
5.4.2.11. namespace specific data wide . . . . . . . . . . 22
5.4.2.12. buffer occupancy . . . . . . . . . . . . . . . . 22
5.4.2.13. Opaque State Snapshot . . . . . . . . . . . . . . 23
5.4.3. Examples of IOAM node data . . . . . . . . . . . . . 23
5.5. IOAM Proof of Transit Option-Type . . . . . . . . . . . . 25
5.5.1. IOAM Proof of Transit Type 0 . . . . . . . . . . . . 27
5.6. IOAM Edge-to-Edge Option-Type . . . . . . . . . . . . . . 28
6. Timestamp Formats . . . . . . . . . . . . . . . . . . . . . . 30
6.1. PTP Truncated Timestamp Format . . . . . . . . . . . . . 30
6.2. NTP 64-bit Timestamp Format . . . . . . . . . . . . . . . 32
6.3. POSIX-based Timestamp Format . . . . . . . . . . . . . . 33
7. IOAM Data Export . . . . . . . . . . . . . . . . . . . . . . 34
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
8.1. IOAM Option-Type Registry . . . . . . . . . . . . . . . . 35
8.2. IOAM Trace-Type Registry . . . . . . . . . . . . . . . . 36
8.3. IOAM Trace-Flags Registry . . . . . . . . . . . . . . . . 36
8.4. IOAM POT-Type Registry . . . . . . . . . . . . . . . . . 37
8.5. IOAM POT-Flags Registry . . . . . . . . . . . . . . . . . 37
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8.6. IOAM E2E-Type Registry . . . . . . . . . . . . . . . . . 37
8.7. IOAM Namespace-ID Registry . . . . . . . . . . . . . . . 37
9. Management and Deployment Considerations . . . . . . . . . . 38
10. Security Considerations . . . . . . . . . . . . . . . . . . . 38
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 40
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 40
12.1. Normative References . . . . . . . . . . . . . . . . . . 40
12.2. Informative References . . . . . . . . . . . . . . . . . 41
Contributors' Addresses . . . . . . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45
1. Introduction
This document defines data fields for "in-situ" Operations,
Administration, and Maintenance (IOAM). In-situ OAM records OAM
information within the packet while the packet traverses a particular
network domain. The term "in-situ" refers to the fact that the OAM
data is added to the data packets rather than being sent within
packets specifically dedicated to OAM. IOAM is to complement
mechanisms such as Ping or Traceroute. In terms of "active" or
"passive" OAM, "in-situ" OAM can be considered a hybrid OAM type.
"In-situ" mechanisms do not require extra packets to be sent. IOAM
adds information to the already available data packets and therefore
cannot be considered passive. In terms of the classification given
in [RFC7799] IOAM could be portrayed as Hybrid Type 1. IOAM
mechanisms can be leveraged where mechanisms using e.g. ICMP do not
apply or do not offer the desired results, such as proving that a
certain traffic flow takes a pre-defined path, SLA verification for
the live data traffic, detailed statistics on traffic distribution
paths in networks that distribute traffic across multiple paths, or
scenarios in which probe traffic is potentially handled differently
from regular data traffic by the network devices.
IOAM use cases and mechanisms have expanded as this document matured,
resulting in additional flags and options that could trigger creation
of additional packets dedicated to OAM. The term IOAM continues to
be used for such mechanisms, in addition to the "in-situ" mechanisms
that motivated this terminology.
2. Contributors
This document was the collective effort of several authors. The text
and content were contributed by the editors and the co-authors listed
below. The contact information of the co-authors appears at the end
of this document.
o Carlos Pignataro
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o Mickey Spiegel
o Barak Gafni
o Jennifer Lemon
o Hannes Gredler
o John Leddy
o Stephen Youell
o David Mozes
o Petr Lapukhov
o Remy Chang
o Daniel Bernier
3. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Abbreviations used in this document:
E2E Edge to Edge
Geneve: Generic Network Virtualization Encapsulation
[I-D.ietf-nvo3-geneve]
IOAM: In-situ Operations, Administration, and Maintenance
MTU: Maximum Transmit Unit
NSH: Network Service Header [RFC8300]
OAM: Operations, Administration, and Maintenance
PMTU Path MTU
POT: Proof of Transit
SFC: Service Function Chain
SID: Segment Identifier
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SR: Segment Routing
VXLAN-GPE: Virtual eXtensible Local Area Network, Generic Protocol
Extension [I-D.ietf-nvo3-vxlan-gpe]
4. Scope, Applicability, and Assumptions
IOAM deployment assumes a set of constraints, requirements, and
guiding principles which are described in this section.
Scope: This document defines the data fields and associated data
types for in-situ OAM. The in-situ OAM data field can be
encapsulated in a variety of protocols, including NSH, Segment
Routing, Geneve, IPv6, or IPv4. Specification details for these
different protocols are outside the scope of this document. It is
expected that each such encapsulation will be defined in the relevant
working group in the IETF.
Deployment domain (or scope) of in-situ OAM deployment: IOAM is a
network domain focused feature, with "network domain" being a set of
network devices or entities within a single administration. For
example, a network domain can include an enterprise campus using
physical connections between devices or an overlay network using
virtual connections / tunnels for connectivity between said devices.
A network domain is defined by its perimeter or edge. Designers of
protocol encapsulations for IOAM specify mechanisms to ensure that
IOAM data stays within an IOAM domain. In addition, the operator of
such a domain is expected to put provisions in place to ensure that
IOAM data does not leak beyond the edge of an IOAM domain using,for
example, packet filtering methods. The operator has to consider the
potential operational impact of IOAM to mechanisms such as ECMP
processing (e.g. load-balancing schemes based on packet length could
be impacted by the increased packet size due to IOAM), path MTU (i.e.
ensure that the MTU of all links within a domain is sufficiently
large to support the increased packet size due to IOAM) and ICMP
message handling (i.e. in case of IPv6, IOAM support for ICMPv6 Echo
Request/Reply is desired which would translate into ICMPv6 extensions
to enable IOAM-Data-Fields to be copied from an Echo Request message
to an Echo Reply message).
IOAM control points: IOAM-Data-Fields are added to or removed from
the live user traffic by the devices which form the edge of a domain.
Devices which form an IOAM-Domain can add, update or remove IOAM-
Data-Fields. Edge devices of an IOAM-Domain can be hosts or network
devices.
Traffic-sets that IOAM is applied to: IOAM can be deployed on all or
only on subsets of the live user traffic. Using IOAM on a selected
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set of traffic (e.g., per interface, based on an access control list
or flow specification defining a specific set of traffic, etc.) could
be useful in deployments where the cost of processing IOAM-Data-
Fields by encapsulating, transit, or decapsulating node(s) might be a
concern from a performance or operational perspective. Thus limiting
the amount of traffic IOAM is applied to could be beneficial in some
deployments.
Encapsulation independence: The definition of IOAM-Data-Fields is
independent from the protocols the IOAM-Data-Fields are encapsulated
into. IOAM-Data-Fields can be encapsulated into several
encapsulating protocols. The specification of how IOAM-Data-Fields
are encapsulated into "parent" protocols, like e.g., NSH or IPv6 is
outside the scope of this document.
Layering: If several encapsulation protocols (e.g., in case of
tunneling) are stacked on top of each other, IOAM-Data-Fields could
be present at multiple layers. The behavior follows the ships-in-
the-night model, i.e. IOAM-Data-Fields in one layer are independent
from IOAM-Data-Fields in another layer. Layering allows operators to
instrument the protocol layer they want to measure. The different
layers could, but do not have to, share the same IOAM encapsulation
mechanisms.
IOAM implementation: The definition of the IOAM-Data-Fields take the
specifics of devices with hardware data planes and software data
planes into account.
5. IOAM Data-Fields, Types, Nodes
This section details IOAM-related nomenclature and describes data
types such as IOAM-Data-Fields, IOAM-Types, IOAM-Namespaces as well
as the different types of IOAM nodes.
5.1. IOAM Data-Fields and Option-Types
An IOAM-Data-Field is a set of bits with a defined format and
meaning, which can be stored at a certain place in a packet for the
purpose of IOAM.
To accommodate the different uses of IOAM, IOAM-Data-Fields fall into
different categories. In IOAM these categories are referred to as
IOAM-Option-Types. A common registry is maintained for IOAM-Option-
Types, see Section 8.1 for details. Corresponding to these IOAM-
Option-Types, different IOAM-Data-Fields are defined. IOAM-Data-
Fields can be encapsulated into a variety of protocols, such as NSH,
Geneve, IPv6, etc. The definition of how IOAM-Data-Fields are
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encapsulated into other protocols is outside the scope of this
document.
This document defines four IOAM-Option-Types:
o Pre-allocated Trace Option-Type
o Incremental Trace Option-Type
o Proof of Transit (POT) Option-Type
o Edge-to-Edge (E2E) Option-Type
5.2. IOAM-Domains and types of IOAM Nodes
IOAM is expected to be deployed in a specific domain. The part of
the network which employs IOAM is referred to as the "IOAM-Domain".
One or more IOAM-Option-Types are added to a packet upon entering the
IOAM-Domain and are removed from the packet when exiting the domain.
Within the IOAM-Domain, the IOAM-Data-Fields MAY be updated by
network nodes that the packet traverses. An IOAM-Domain consists of
"IOAM encapsulating nodes", "IOAM decapsulating nodes" and "IOAM
transit nodes". The role of a node (i.e. encapsulating, transit,
decapsulating) is defined within an IOAM-Namespace (see below). A
node can have different roles in different IOAM-Namespaces.
A device which adds at least one IOAM-Option-Type to the packet is
called the "IOAM encapsulating node", whereas a device which removes
an IOAM-Option-Type is referred to as the "IOAM decapsulating node".
Nodes within the domain which are aware of IOAM data and read and/or
write or process the IOAM data are called "IOAM transit nodes". IOAM
nodes which add or remove the IOAM-Data-Fields can also update the
IOAM-Data-Fields at the same time. Or in other words, IOAM
encapsulating or decapsulating nodes can also serve as IOAM transit
nodes at the same time. Note that not every node in an IOAM domain
needs to be an IOAM transit node. For example, a deployment might
require that packets traverse a set of firewalls which support IOAM.
In that case, only the set of firewall nodes would be IOAM transit
nodes rather than all nodes.
An "IOAM encapsulating node" incorporates one or more IOAM-Option-
Types (from the list of IOAM-Types, see Section 8.1) into packets
that IOAM is enabled for. If IOAM is enabled for a selected subset
of the traffic, the IOAM encapsulating node is responsible for
applying the IOAM functionality to the selected subset.
An "IOAM transit node" updates one or more of the IOAM-Data-Fields.
If both the Pre-allocated and the Incremental Trace Option-Types are
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present in the packet, each IOAM transit node based on configuration
and available implementation of IOAM populates IOAM trace data in
either Pre-allocated or Incremental Trace Option-Type but not both.
A transit node MUST ignore IOAM-Option-Types that it does not
understand. A transit node MUST NOT add new IOAM-Option-Types to a
packet, MUST NOT remove IOAM-Option-Types from a packet, and MUST NOT
change the IOAM-Data-Fields of an IOAM Edge-to-Edge Option-Type.
An "IOAM decapsulating node" removes IOAM-Option-Type(s) from
packets.
The role of an IOAM-encapsulating, IOAM-transit or IOAM-decapsulating
node is always performed within a specific IOAM-Namespace. This
means that an IOAM node which is e.g. an IOAM-decapsulating node for
IOAM-Namespace "A" but not for IOAM-Namespace "B" will only remove
the IOAM-Option-Types for IOAM-Namespace "A" from the packet. Note
that this applies even for IOAM-Option-Types that the node does not
understand, for example an IOAM-Option-Type other than the four
described above, that is added in a future revision. An IOAM
decapsulating node situated at the edge of an IOAM domain MUST remove
all IOAM-Option-Types and associated encapsulation headers for all
IOAM-Namespaces from the packet.
IOAM-Namespaces allow for a namespace-specific definition and
interpretation of IOAM-Data-Fields. An interface-id could for
example point to a physical interface (e.g., to understand which
physical interface of an aggregated link is used when receiving or
transmitting a packet) whereas in another case it could refer to a
logical interface (e.g., in case of tunnels). Please refer to
Section 5.3 for details on IOAM-Namespaces.
5.3. IOAM-Namespaces
A subset or all of the IOAM-Option-Types and their corresponding
IOAM-Data-Fields can be associated to an IOAM-Namespace. IOAM-
Namespaces add further context to IOAM-Option-Types and associated
IOAM-Data-Fields. Any IOAM-Namespace MUST interpret the IOAM-Option-
Types and associated IOAM-Data-Fields per the definition in this
document. IOAM-Namespaces group nodes to support different
deployment approaches of IOAM (see a few example use-cases below) as
well as resolve issues which can occur due to IOAM-Data-Fields not
being globally unique (e.g. IOAM node identifiers do not have to be
globally unique). IOAM-Data-Fields significance is always within a
particular IOAM-Namespace.
An IOAM-Namespace is identified by a 16-bit namespace identifier
(Namespace-ID). IOAM-Namespace identifiers MUST be present and
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populated in all IOAM-Option-Types. The Namespace-ID value is
divided into two sub-ranges:
o An operator-assigned range from 0x0001 to 0x7FFF
o An IANA-assigned range from 0x8000 to 0xFFFF
The IANA-assigned range is intended to allow future extensions to
have new and interoperable IOAM functionality, while the operator-
assigned range is intended to be domain specific, and managed by the
network operator. The Namespace-ID value of 0x0000 is the "Default-
Namespace-ID". The Default-Namespace-ID indicates that no specific
namespace is associated with the IOAM data fields in the packet. The
Default-Namespace-ID MUST be supported by all nodes implementing
IOAM. A use-case for the Default-Namespace-ID are deployments which
do not leverage specific namespaces for some or all of their packets
that carry IOAM data fields.
Namespace identifiers allow devices which are IOAM capable to
determine:
o whether IOAM-Option-Type(s) need to be processed by a device: If
the Namespace-ID contained in a packet does not match any
Namespace-ID the node is configured to operate on, then the node
MUST NOT change the contents of the IOAM-Data-Fields.
o which IOAM-Option-Type needs to be processed/updated in case there
are multiple IOAM-Option-Types present in the packet. Multiple
IOAM-Option-Types can be present in a packet in case of
overlapping IOAM-Domains or in case of a layered IOAM deployment.
o whether IOAM-Option-Type(s) has to be removed from the packet,
e.g. at a domain edge or domain boundary.
IOAM-Namespaces support several different uses:
o IOAM-Namespaces can be used by an operator to distinguish
different operational domains. Devices at domain edges can filter
on Namespace-IDs to provide for proper IOAM-Domain isolation.
o IOAM-Namespaces provide additional context for IOAM-Data-Fields
and thus ensure that IOAM-Data-Fields are unique and can be
interpreted properly by management stations or network
controllers. While, for example, the node identifier field
(node_id, see below) does not need to be unique in a deployment
(e.g. if an operator wishes to use different node identifiers for
different IOAM layers, even within the same device; or node
identifiers might not be unique for other organizational reasons,
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such as after a merger of two formerly separated organizations),
the combination of node_id and Namespace-ID will always be unique.
Similarly, IOAM-Namespaces can be used to define how certain IOAM-
Data-Fields are interpreted: IOAM offers three different timestamp
format options. The Namespace-ID can be used to determine the
timestamp format. IOAM-Data-Fields (e.g. buffer occupancy) which
do not have a unit associated are to be interpreted within the
context of a IOAM-Namespace.
o IOAM-Namespaces can be used to identify different sets of devices
(e.g., different types of devices) in a deployment: If an operator
desires to insert different IOAM-Data-Fields based on the device,
the devices could be grouped into multiple IOAM-Namespaces. This
could be due to the fact that the IOAM feature set differs between
different sets of devices, or it could be for reasons of optimized
space usage in the packet header. It could also stem from
hardware or operational limitations on the size of the trace data
that can be added and processed, preventing collection of a full
trace for a flow.
* Assigning different IOAM Namespace-IDs to different sets of
nodes or network partitions and using the Namespace-ID as a
selector at the IOAM encapsulating node, a full trace for a
flow could be collected and constructed via partial traces in
different packets of the same flow. Example: An operator could
choose to group the devices of a domain into two IOAM-
Namespaces, in a way that on average, only every second hop
would be recorded by any device. To retrieve a full view of
the deployment, the captured IOAM-Data-Fields of the two IOAM-
Namespaces need to be correlated.
* Assigning different IOAM Namespace-IDs to different sets of
nodes or network partitions and using a separate instance of an
IOAM-Option-Type for each Namespace-ID, a full trace for a flow
could be collected and constructed via partial traces from each
IOAM-Option-Type in each of the packets in the flow. Example:
An operator could choose to group the devices of a domain into
two IOAM-Namespaces, in a way that each IOAM-Namespace is
represented by one of two IOAM-Option-Types in the packet.
Each node would record data only for the IOAM-Namespace that it
belongs to, ignoring the other IOAM-Option-Type with a IOAM-
Namespace to which it doesn't belong. To retrieve a full view
of the deployment, the captured IOAM-Data-Fields of the two
IOAM-Namespaces need to be correlated.
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5.4. IOAM Trace Option-Types
"IOAM tracing data" is expected to be collected at every IOAM transit
node that a packet traverses to ensure visibility into the entire
path a packet takes within an IOAM-Domain. I.e., in a typical
deployment all nodes in an IOAM-Domain would participate in IOAM and
thus be IOAM transit nodes, IOAM encapsulating or IOAM decapsulating
nodes. If not all nodes within a domain support IOAM functionality
as defined in this document, IOAM tracing information (i.e., node
data, see below) will only be collected on those nodes which support
IOAM functionality as defined in this document. Nodes which do not
support IOAM functionality as defined in this document will forward
the packet without any changes to the IOAM-Data-Fields. The maximum
number of hops and the minimum path MTU of the IOAM domain is assumed
to be known. An overflow indicator (O-bit) is defined as one of the
ways to deal with situations where the PMTU was underestimated, i.e.
where the number of hops which are IOAM capable exceeds the available
space in the packet.
To optimize hardware and software implementations, IOAM tracing is
defined as two separate options. Any deployment MAY choose to
configure and support one or both of the following options.
Pre-allocated Trace-Option: This trace option is defined as a
container of node data fields (see below) with pre-allocated space
for each node to populate its information. This option is useful
for implementations where it is efficient to allocate the space
once and index into the array to populate the data during transit
(e.g., software forwarders often fall into this class). The IOAM
encapsulating node allocates space for Pre-allocated Trace Option-
Type in the packet and sets corresponding fields in this IOAM-
Option-Type. The IOAM encapsulating node allocates an array which
is used to store operational data retrieved from every node while
the packet traverses the domain. IOAM transit nodes update the
content of the array, and possibly update the checksums of outer
headers. A pointer which is part of the IOAM trace data, points
to the next empty slot in the array. An IOAM transit node that
updates the content of the pre-allocated option also updates the
value of the pointer, which specifies where the next IOAM transit
node fills in its data. The "node data list" array (see below) in
the packet is populated iteratively as the packet traverses the
network, starting with the last entry of the array, i.e., "node
data list [n]" is the first entry to be populated, "node data list
[n-1]" is the second one, etc.
Incremental Trace-Option: This trace option is defined as a
container of node data fields where each node allocates and pushes
its node data immediately following the option header. This type
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of trace recording is useful for some of the hardware
implementations as it eliminates the need for the transit network
elements to read the full array in the option and allows for
arbitrarily long packets as the MTU allows. The IOAM
encapsulating node allocates space for the Incremental Trace
Option-Type. Based on operational state and configuration, the
IOAM encapsulating node sets the fields in the Option-Type that
control what IOAM-Data-Fields have to be collected and how large
the node data list can grow. IOAM transit nodes push their node
data to the node data list, decrease the remaining length
available to subsequent nodes and adjust the lengths and possibly
checksums in outer headers.
A particular implementation of IOAM MAY choose to support only one of
the two trace option types. In the event that both options are
utilized at the same time, the Incremental Trace-Option MUST be
placed before the Pre-allocated Trace-Option. Deployments which mix
devices with either the Incremental Trace-Option or the Pre-allocated
Trace-Option could result in both Option-Types being present in a
packet. Given that the operator knows which equipment is deployed in
a particular IOAM, the operator will decide by means of configuration
which type(s) of trace options will be used for a particular domain.
Every node data entry holds information for a particular IOAM transit
node that is traversed by a packet. The IOAM decapsulating node
removes the IOAM-Option-Type(s) and processes and/or exports the
associated data. Like all IOAM-Data-Fields, the IOAM-Data-Fields of
the IOAM-Trace-Option-Types are defined in the context of an IOAM-
Namespace.
IOAM tracing can collect the following types of information:
o Identification of the IOAM node. An IOAM node identifier can
match to a device identifier or a particular control point or
subsystem within a device.
o Identification of the interface that a packet was received on,
i.e. ingress interface.
o Identification of the interface that a packet was sent out on,
i.e. egress interface.
o Time of day when the packet was processed by the node as well as
the transit delay. Different definitions of processing time are
feasible and expected, though it is important that all devices of
an in-situ OAM domain follow the same definition.
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o Generic data: Format-free information where syntax and semantic of
the information is defined by the operator in a specific
deployment. For a specific IOAM-Namespace, all IOAM nodes have to
interpret the generic data the same way. Examples for generic
IOAM data include geo-location information (location of the node
at the time the packet was processed), buffer queue fill level or
cache fill level at the time the packet was processed, or even a
battery charge level.
o Information to detect whether IOAM trace data was added at every
hop or whether certain hops in the domain weren't IOAM transit
nodes.
5.4.1. Pre-allocated and Incremental Trace Option-Types
The IOAM Pre-allocated Trace-Option and the IOAM Incremental Trace-
Option have similar formats. Except where noted below, the internal
formats and fields of the two trace options are identical. Both
Trace-Options consist of a fixed size "trace option header" and a
variable data space to store gathered data, the "node data list". An
IOAM transit node (that is not an IOAM encapsulating node or IOAM
decapsulating node) MUST NOT modify any of the fields in the fixed
size "trace option header", other than "flags" and "RemainingLen",
i.e. an IOAM transit node MUST NOT modify the Namespace-ID, NodeLen,
IOAM-Trace-Type, or Reserved fields.
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Pre-allocated and incremental trace option headers:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Namespace-ID |NodeLen | Flags | RemainingLen|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IOAM-Trace-Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The trace option data MUST be 4-octet aligned:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| | |
| node data list [0] | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ D
| | a
| node data list [1] | t
| | a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~ S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ p
| | a
| node data list [n-1] | c
| | e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | |
| node data list [n] | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
Namespace-ID: 16-bit identifier of an IOAM-Namespace. The
Namespace-ID value of 0x0000 is defined as the "Default-Namespace-
ID" (see Section 5.3) and MUST be known to all the nodes
implementing IOAM. For any other Namespace-ID value that does not
match any Namespace-ID the node is configured to operate on, the
node MUST NOT change the contents of the IOAM-Data-Fields.
NodeLen: 5-bit unsigned integer. This field specifies the length of
data added by each node in multiples of 4-octets, excluding the
length of the "Opaque State Snapshot" field.
If IOAM-Trace-Type bit 22 is not set, then NodeLen specifies the
actual length added by each node. If IOAM-Trace-Type bit 22 is
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set, then the actual length added by a node would be (NodeLen +
length of the "Opaque State Snapshot" field) in 4 octet units.
For example, if 3 IOAM-Trace-Type bits are set and none of them
are wide, then NodeLen would be 3. If 3 IOAM-Trace-Type bits are
set and 2 of them are wide, then NodeLen would be 5.
An IOAM encapsulating node MUST set NodeLen.
A node receiving an IOAM Pre-allocated or Incremental Trace-Option
relies on the NodeLen value, or it can ignore the NodeLen value
and calculate the node length from the IOAM-Trace-Type bits (see
below).
Flags 4-bit field. Flags are allocated by IANA, as specified in
Section 8.3. This document allocates a single flag as follows:
Bit 0 "Overflow" (O-bit) (most significant bit). If there are
not enough octets left to record node data, the network element
MUST NOT add any fields and MUST set the overflow "O-bit" to
"1" in the IOAM-Trace-Option header. This is useful for
transit nodes to ignore further processing of the option.
RemainingLen: 7-bit unsigned integer. This field specifies the data
space in multiples of 4-octets remaining for recording the node
data, before the node data list is considered to have overflowed.
Given that the sender knows the path MTU (PMTU), the sender MAY
set the initial value of RemainingLen according to the number of
node data bytes allowed before exceeding the MTU. Subsequent
nodes can carry out a simple comparison between RemainingLen and
NodeLen, along with the length of the "Opaque State Snapshot" if
applicable, to determine whether or not data can be added by this
node. When node data is added, the node MUST decrease
RemainingLen by the amount of data added. In the pre-allocated
trace option, RemainingLen is used to derive the offset in data
space to record the node data element. Specifically, the
recording of the node data element would start from RemainingLen -
NodeLen - sizeof(opaque snapshot) in 4 octet units. If
RemainingLen in a pre-allocated trace option exceeds the length of
the option, as specified in the preceding header, then the node
MUST NOT add any fields.
IOAM-Trace-Type: A 24-bit identifier which specifies which data
types are used in this node data list.
The IOAM-Trace-Type value is a bit field. The following bits are
defined in this document, with details on each bit described in
the Section 5.4.2. The order of packing the data fields in each
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node data element follows the bit order of the IOAM-Trace-Type
field, as follows:
Bit 0 (Most significant bit) When set, indicates presence of
Hop_Lim and node_id (short format) in the node data.
Bit 1 When set, indicates presence of ingress_if_id and
egress_if_id (short format) in the node data.
Bit 2 When set, indicates presence of timestamp seconds in the
node data.
Bit 3 When set, indicates presence of timestamp subseconds in
the node data.
Bit 4 When set, indicates presence of transit delay in the node
data.
Bit 5 When set, indicates presence of IOAM-Namespace specific
data (short format) in the node data.
Bit 6 When set, indicates presence of queue depth in the node
data.
Bit 7 When set, indicates presence of the Checksum Complement
node data.
Bit 8 When set, indicates presence of Hop_Lim and node_id in
wide format in the node data.
Bit 9 When set, indicates presence of ingress_if_id and
egress_if_id in wide format in the node data.
Bit 10 When set, indicates presence of IOAM-Namespace specific
data in wide format in the node data.
Bit 11 When set, indicates presence of buffer occupancy in the
node data.
Bit 12-21 Undefined. An IOAM encapsulating node MUST set the
value of each of these bits to 0. If an IOAM transit
node receives a packet with one or more of these bits set
to 1, it MUST either:
1. Add corresponding node data filled with the reserved
value 0xFFFFFFFF, after the node data fields for the
IOAM-Trace-Type bits defined above, such that the
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total node data added by this node in units of
4-octets is equal to NodeLen, or
2. Not add any node data fields to the packet, even for
the IOAM-Trace-Type bits defined above.
Bit 22 When set, indicates presence of variable length Opaque
State Snapshot field.
Bit 23 Reserved: MUST be set to zero upon transmission and
ignored upon receipt.
Section 5.4.2 describes the IOAM-Data-Types and their formats.
Within an IOAM-Domain possible combinations of these bits making
the IOAM-Trace-Type can be restricted by configuration knobs.
Reserved: 8-bits. An IOAM encapsulating node MUST set the value to
zero upon transmission. IOAM transit nodes MUST ignore the
received value.
Node data List [n]: Variable-length field. This is a list of node
data elements where the content of each node data element is
determined by the IOAM-Trace-Type. The order of packing the data
fields in each node data element follows the bit order of the
IOAM-Trace-Type field. Each node MUST prepend its node data
element in front of the node data elements that it received, such
that the transmitted node data list begins with this node's data
element as the first populated element in the list. The last node
data element in this list is the node data of the first IOAM
capable node in the path. Populating the node data list in this
way ensures that the order of node data list is the same for
incremental and pre-allocated trace options. In the pre-allocated
trace option, the index contained in RemainingLen identifies the
offset for current active node data to be populated.
5.4.2. IOAM node data fields and associated formats
All the IOAM-Data-Fields MUST be 4-octet aligned. If a node which is
supposed to update an IOAM-Data-Field is not capable of populating
the value of a field set in the IOAM-Trace-Type, the field value MUST
be set to 0xFFFFFFFF for 4-octet fields or 0xFFFFFFFFFFFFFFFF for
8-octet fields, indicating that the value is not populated, except
when explicitly specified in the field description below.
Some IOAM-Data-Fields defined below, such as interface identifiers or
IOAM-Namespace specific data, are defined in both "short format" as
well as "wide format". Their use is not exclusive. A deployment
could choose to leverage both. For example, ingress_if_id_(short
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format) could be an identifier for the physical interface, whereas
ingress_if_id_(wide format) could be an identifier for a logical sub-
interface of that physical interface.
Data fields and associated data types for each of the IOAM-Data-
Fields are specified in the following sections.
5.4.2.1. Hop_Lim and node_id short format
The "Hop_Lim and node_id short format" field is a 4-octet field that
is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Hop_Lim: 1-octet unsigned integer. It is set to the Hop Limit value
in the packet at the node that records this data. Hop Limit
information is used to identify the location of the node in the
communication path. This is copied from the lower layer, e.g.,
TTL value in IPv4 header or hop limit field from IPv6 header of
the packet when the packet is ready for transmission. The
semantics of the Hop_Lim field depend on the lower layer protocol
that IOAM is encapsulated into, and therefore its specific
semantics are outside the scope of this memo. The value of this
field MUST be set to 0xff when the lower level does not have a
TTL/Hop limit equivalent field.
node_id: 3-octet unsigned integer. Node identifier field to
uniquely identify a node within the IOAM-Namespace and associated
IOAM-Domain. The procedure to allocate, manage and map the
node_ids is beyond the scope of this document.
5.4.2.2. ingress_if_id and egress_if_id
The "ingress_if_id and egress_if_id" field is a 4-octet field that is
defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id | egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ingress_if_id: 2-octet unsigned integer. Interface identifier to
record the ingress interface the packet was received on.
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egress_if_id: 2-octet unsigned integer. Interface identifier to
record the egress interface the packet is forwarded out of.
Note that due to the fact that IOAM uses its own IOAM-Namespaces for
IOAM-Data-Fields, data fields like interface identifiers can be used
in a flexible way to represent system resources that are associated
with ingressing or egressing packets, i.e. ingress_if_id could
represent a physical interface, a virtual or logical interface, or
even a queue.
5.4.2.3. timestamp seconds
The "timestamp seconds" field is a 4-octet unsigned integer field.
Absolute timestamp in seconds that specifies the time at which the
packet was received by the node. This field has three possible
formats; based on either PTP [IEEE1588v2], NTP [RFC5905], or POSIX
[POSIX]. The three timestamp formats are specified in Section 6. In
all three cases, the Timestamp Seconds field contains the 32 most
significant bits of the timestamp format that is specified in
Section 6. If a node is not capable of populating this field, it
assigns the value 0xFFFFFFFF. Note that this is a legitimate value
that is valid for 1 second in approximately 136 years; the analyzer
has to correlate several packets or compare the timestamp value to
its own time-of-day in order to detect the error indication.
5.4.2.4. timestamp subseconds
The "timestamp subseconds" field is a 4-octet unsigned integer field.
Absolute timestamp in subseconds that specifies the time at which the
packet was received by the node. This field has three possible
formats; based on either PTP [IEEE1588v2], NTP [RFC5905], or POSIX
[POSIX]. The three timestamp formats are specified in Section 6. In
all three cases, the Timestamp Subseconds field contains the 32 least
significant bits of the timestamp format that is specified in
Section 6. If a node is not capable of populating this field, it
assigns the value 0xFFFFFFFF. Note that this is a legitimate value
in the NTP format, valid for approximately 233 picoseconds in every
second. If the NTP format is used the analyzer has to correlate
several packets in order to detect the error indication.
5.4.2.5. transit delay
The "transit delay" field is a 4-octet unsigned integer in the range
0 to 2^31-1. It is the time in nanoseconds the packet spent in the
transit node. This can serve as an indication of the queuing delay
at the node. If the transit delay exceeds 2^31-1 nanoseconds then
the top bit 'O' is set to indicate overflow and value set to
0x80000000. When this field is part of the data field but a node
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populating the field is not able to fill it, the field position in
the field MUST be filled with value 0xFFFFFFFF to mean not populated.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O| transit delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.4.2.6. namespace specific data
The "namespace specific data" field is a 4-octet field which can be
used by the node to add IOAM-Namespace specific data. This
represents a "free-format" 4-octet bit field with its semantics
defined in the context of a specific IOAM-Namespace.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.4.2.7. queue depth
The "queue depth" field is a 4-octet unsigned integer field. This
field indicates the current length of the egress interface queue of
the interface from where the packet is forwarded out. The queue
depth is expressed as the current amount of memory buffers used by
the queue (a packet could consume one or more memory buffers,
depending on its size).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| queue depth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.4.2.8. Checksum Complement
The "Checksum Complement" field is a 4-octet node data which contains
a 4-octet Checksum Complement field. The Checksum Complement is
useful when IOAM is transported over encapsulations that make use of
a UDP transport, such as VXLAN-GPE or Geneve. Without the Checksum
Complement, nodes adding IOAM node data update the UDP Checksum field
following the recommendation of the encapsulation protocols. When
the Checksum Complement is present, an IOAM encapsulating node or
IOAM transit node adding node data MUST carry out one of the
following two alternatives in order to maintain the correctness of
the UDP Checksum value:
1. Recompute the UDP Checksum field.
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2. Use the Checksum Complement to make a checksum-neutral update in
the UDP payload; the Checksum Complement is assigned a value that
complements the rest of the node data fields that were added by
the current node, causing the existing UDP Checksum field to
remain correct.
IOAM decapsulating nodes MUST recompute the UDP Checksum field, since
they do not know whether previous hops modified the UDP Checksum
field or the Checksum Complement field.
Checksum Complement fields are used in a similar manner in [RFC7820]
and [RFC7821].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum Complement |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.4.2.9. Hop_Lim and node_id wide
The "Hop_Lim and node_id wide" field is an 8-octet field defined as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ node_id (contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Hop_Lim: 1-octet unsigned integer. It is set to the Hop Limit value
in the packet at the node that records this data. Hop Limit
information is used to identify the location of the node in the
communication path. This is copied from the lower layer for e.g.
TTL value in IPv4 header or hop limit field from IPv6 header of
the packet. The semantics of the Hop_Lim field depend on the
lower layer protocol that IOAM is encapsulated into, and therefore
its specific semantics are outside the scope of this memo. The
value of this field MUST be set to 0xff when the lower level does
not have a TTL/Hop limit equivalent field.
node_id: 7-octet unsigned integer. Node identifier field to
uniquely identify a node within the IOAM-Namespace and associated
IOAM-Domain. The procedure to allocate, manage and map the
node_ids is beyond the scope of this document.
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5.4.2.10. ingress_if_id and egress_if_id wide
The "ingress_if_id and egress_if_id wide" field is an 8-octet field
which is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ingress_if_id: 4-octet unsigned integer. Interface identifier to
record the ingress interface the packet was received on.
egress_if_id: 4-octet unsigned integer. Interface identifier to
record the egress interface the packet is forwarded out of.
5.4.2.11. namespace specific data wide
The "namespace specific data wide" field is an 8-octet field which
can be used by the node to add IOAM-Namespace specific data. This
represents a "free-format" 8-octet bit field with its semantics
defined in the context of a specific IOAM-Namespace.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ namespace specific data (contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.4.2.12. buffer occupancy
The "buffer occupancy" field is a 4-octet unsigned integer field.
This field indicates the current status of the occupancy of the
common buffer pool used by a set of queues. The units of this field
are implementation specific. Hence, the units are interpreted within
the context of an IOAM-Namespace and/or node-id if used. The authors
acknowledge that in some operational cases there is a need for the
units to be consistent across a packet path through the network,
hence it is RECOMMENDED for implementations to use standard units
such as Bytes.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| buffer occupancy |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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5.4.2.13. Opaque State Snapshot
The "Opaque State Snapshot" is a variable length field and follows
the fixed length IOAM-Data-Fields defined above. It allows the
network element to store an arbitrary state in the node data field,
without a pre-defined schema. The schema is to be defined within the
context of an IOAM-Namespace. The schema needs to be made known to
the analyzer by some out-of-band mechanism. The specification of
this mechanism is beyond the scope of this document. A 24-bit
"Schema Id" field, interpreted within the context of an IOAM-
Namespace, indicates which particular schema is used, and has to be
configured on the network element by the operator.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Schema ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Opaque data |
~ ~
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Length: 1-octet unsigned integer. It is the length in multiples of
4-octets of the Opaque data field that follows Schema Id.
Schema ID: 3-octet unsigned integer identifying the schema of Opaque
data.
Opaque data: Variable length field. This field is interpreted as
specified by the schema identified by the Schema ID.
When this field is part of the data field but a node populating the
field has no opaque state data to report, the Length MUST be set to 0
and the Schema ID MUST be set to 0xFFFFFF to mean no schema.
5.4.3. Examples of IOAM node data
An entry in the "node data list" array can have different formats,
following the needs of the deployment. Some deployments might only
be interested in recording the node identifiers, whereas others might
be interested in recording node identifier and timestamp. The
section provides example entries of the "node data list".
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0xD40000: IOAM-Trace-Type is 0xD40000 (0b110101000000000000000000)
then the format of node data is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id | egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0xC00000: IOAM-Trace-Type is 0xC00000 (0b110000000000000000000000)
then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id | egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x900000: IOAM-Trace-Type is 0x900000 (0b100100000000000000000000)
then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x840000: IOAM-Trace-Type is 0x840000 (0b100001000000000000000000)
then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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0x940000: IOAM-Trace-Type is 0x940000 (0b100101000000000000000000)
then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x308002: IOAM-Trace-Type is 0x308002 (0b001100001000000000000010)
then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| node_id(contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Schema Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Opaque data |
~ ~
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.5. IOAM Proof of Transit Option-Type
IOAM Proof of Transit Option-Type is to support path or service
function chain [RFC7665] verification use cases. Proof-of-transit
leverages mechanisms like Shamir's Secret Sharing Schema (SSSS)
[SSS]. For further information on Proof-of-transit, please refer to
[I-D.ietf-sfc-proof-of-transit]. While details on how the IOAM data
for the Proof-of-transit option is processed at IOAM encapsulating,
decapsulating and transit nodes are outside the scope of the
document, all of these approaches share the need to uniquely identify
a packet as well as iteratively operate on a set of information that
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is handed from node to node. Correspondingly, two pieces of
information are added as IOAM-Data-Fields to the packet:
o Random: Unique identifier for the packet (e.g., 64-bits allow for
the unique identification of 2^64 packets).
o Cumulative: Information which is handed from node to node and
updated by every node according to a verification algorithm.
The IOAM Proof-of-Transit Option-Type consist of a fixed size "IOAM
proof of transit option header" and "IOAM proof of transit option
data fields":
IOAM proof of transit option header:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Namespace-ID |IOAM POT Type | IOAM POT flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IOAM proof of transit Option-Type IOAM-Data-Fields MUST be
4-octet aligned:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| POT Option data field determined by IOAM-POT-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Namespace-ID: 16-bit identifier of an IOAM-Namespace. The
Namespace-ID value of 0x0000 is defined as the "Default-Namespace-
ID" (see Section 5.3) and MUST be known to all the nodes
implementing IOAM. For any other Namespace-ID value that does not
match any Namespace-ID the node is configured to operate on, the
node MUST NOT change the contents of the IOAM-Data-Fields.
IOAM POT Type: 8-bit identifier of a particular POT variant that
specifies the POT data that is included. This document defines
POT Type 0:
0: POT data is a 16 Octet field as described below.
If a node receives an IOAM POT Type value that it does not
understand, the node MUST NOT change the contents of the IOAM-
Data-Fields.
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IOAM POT flags: 8-bit. Following flags are defined:
Bit 0 "Profile-to-use" (P-bit) (most significant bit). For IOAM
POT types that use a maximum of two profiles to drive
computation, indicates which POT-profile is used. The two
profiles are numbered 0, 1.
Bit 1-7 Reserved: MUST be set to zero upon transmission and
ignored upon receipt.
POT Option data: Variable-length field. The type of which is
determined by the IOAM-POT-Type.
5.5.1. IOAM Proof of Transit Type 0
IOAM proof of transit option of IOAM POT Type 0:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Namespace-ID |IOAM POT Type=0|P|R R R R R R R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| Random | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ P
| Random(contd) | O
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ T
| Cumulative | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Cumulative (contd) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
Namespace-ID: 16-bit identifier of an IOAM-Namespace. The
Namespace-ID value of 0x0000 is defined as the "Default-Namespace-
ID" (see Section 5.3) and MUST be known to all the nodes
implementing IOAM. For any other Namespace-ID value that does not
match any Namespace-ID the node is configured to operate on, the
node MUST NOT change the contents of the IOAM-Data-Fields.
IOAM POT Type: 8-bit identifier of a particular POT variant that
specifies the POT data that is included. This section defines the
POT data when the IOAM POT Type is set to the value 0.
P bit: 1-bit. "Profile-to-use" (P-bit) (most significant bit).
Indicates which POT-profile is used to generate the Cumulative.
Any node participating in POT will have a maximum of 2 profiles
configured that drive the computation of cumulative. The two
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profiles are numbered 0, 1. This bit conveys whether profile 0 or
profile 1 is used to compute the Cumulative.
R (7 bits): 7-bit IOAM POT flags for future use. MUST be set to
zero upon transmission and ignored upon receipt.
Random: 64-bit Per packet Random number.
Cumulative: 64-bit Cumulative that is updated at specific nodes by
processing per packet Random number field and configured
parameters.
Note: Larger or smaller sizes of "Random" and "Cumulative" data are
feasible and could be required for certain deployments (e.g. in case
of space constraints in the encapsulation protocols used). Future
documents could introduce different sizes of data for "proof of
transit".
5.6. IOAM Edge-to-Edge Option-Type
The IOAM Edge-to-Edge Option-Type is to carry data that is added by
the IOAM encapsulating node and interpreted by IOAM decapsulating
node. The IOAM transit nodes MAY process the data but MUST NOT
modify it.
The IOAM Edge-to-Edge Option-Type consist of a fixed size "IOAM Edge-
to-Edge Option-Type header" and "IOAM Edge-to-Edge Option-Type data
fields":
IOAM Edge-to-Edge Option-Type header:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Namespace-ID | IOAM-E2E-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IOAM Edge-to-Edge Option-Type IOAM-Data-Fields MUST
be 4-octet aligned:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| E2E Option data field determined by IOAM-E2E-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Namespace-ID: 16-bit identifier of an IOAM-Namespace. The
Namespace-ID value of 0x0000 is defined as the "Default-Namespace-
ID" (see Section 5.3) and MUST be known to all the nodes
implementing IOAM. For any other Namespace-ID value that does not
match any Namespace-ID the node is configured to operate on, then
the node MUST NOT change the contents of the IOAM-Data-Fields.
IOAM-E2E-Type: A 16-bit identifier which specifies which data types
are used in the E2E option data. The IOAM-E2E-Type value is a bit
field. The order of packing the E2E option data field elements
follows the bit order of the IOAM-E2E-Type field, as follows:
Bit 0 (Most significant bit) When set indicates presence of a
64-bit sequence number added to a specific "packet group"
which is used to detect packet loss, packet reordering,
or packet duplication within the group. The "packet
group" is deployment dependent and defined at the IOAM
encapsulating node e.g. by n-tuple based classification
of packets.
Bit 1 When set indicates presence of a 32-bit sequence number
added to a specific "packet group" which is used to
detect packet loss, packet reordering, or packet
duplication within that group. The "packet group" is
deployment dependent and defined at the IOAM
encapsulating node e.g. by n-tuple based classification
of packets.
Bit 2 When set indicates presence of timestamp seconds,
representing the time at which the packet entered the
IOAM domain. Within the IOAM encapsulating node, the
time that the timestamp is retrieved can depend on the
implementation. Some possibilities are: 1) the time at
which the packet was received by the node, 2) the time at
which the packet was transmitted by the node, 3) when a
tunnel encapsulation is used, the point at which the
packet is encapsulated into the tunnel. Each
implementation has to document when the E2E timestamp
that is going to be put in the packet is retrieved. This
4-octet field has three possible formats; based on either
PTP [IEEE1588v2], NTP [RFC5905], or POSIX [POSIX]. The
three timestamp formats are specified in Section 6. In
all three cases, the Timestamp Seconds field contains the
32 most significant bits of the timestamp format that is
specified in Section 6. If a node is not capable of
populating this field, it assigns the value 0xFFFFFFFF.
Note that this is a legitimate value that is valid for 1
second in approximately 136 years; the analyzer has to
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correlate several packets or compare the timestamp value
to its own time-of-day in order to detect the error
indication.
Bit 3 When set indicates presence of timestamp subseconds,
representing the time at which the packet entered the
IOAM domain. This 4-octet field has three possible
formats; based on either PTP [IEEE1588v2], NTP [RFC5905],
or POSIX [POSIX]. The three timestamp formats are
specified in Section 6. In all three cases, the
Timestamp Subseconds field contains the 32 least
significant bits of the timestamp format that is
specified in Section 6. If a node is not capable of
populating this field, it assigns the value 0xFFFFFFFF.
Note that this is a legitimate value in the NTP format,
valid for approximately 233 picoseconds in every second.
If the NTP format is used the analyzer has to correlate
several packets in order to detect the error indication.
Bit 4-15 Undefined. An IOAM encapsulating node MUST set the value
of these bits to zero upon transmission and ignore upon
receipt.
E2E Option data: Variable-length field. The type of which is
determined by the IOAM-E2E-Type.
6. Timestamp Formats
The IOAM-Data-Fields include a timestamp field which is represented
in one of three possible timestamp formats. It is assumed that the
management plane is responsible for determining which timestamp
format is used.
6.1. PTP Truncated Timestamp Format
The Precision Time Protocol (PTP) [IEEE1588v2] uses an 80-bit
timestamp format. The truncated timestamp format is a 64-bit field,
which is the 64 least significant bits of the 80-bit PTP timestamp.
The PTP truncated format is specified in Section 4.3 of [RFC8877],
and the details are presented below for the sake of completeness.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nanoseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: PTP [IEEE1588v2] Truncated Timestamp Format
Timestamp field format:
Seconds: specifies the integer portion of the number of seconds
since the epoch.
+ Size: 32 bits.
+ Units: seconds.
Nanoseconds: specifies the fractional portion of the number of
seconds since the epoch.
+ Size: 32 bits.
+ Units: nanoseconds. The value of this field is in the range 0
to (10^9)-1.
Epoch:
The PTP [IEEE1588v2] epoch is 1 January 1970 00:00:00 TAI, which
is 31 December 1969 23:59:51.999918 UTC.
Resolution:
The resolution is 1 nanosecond.
Wraparound:
This time format wraps around every 2^32 seconds, which is roughly
136 years. The next wraparound will occur in the year 2106.
Synchronization Aspects:
It is assumed that nodes that run this protocol are synchronized
among themselves. Nodes MAY be synchronized to a global reference
time. Note that if PTP [IEEE1588v2] is used for synchronization,
the timestamp MAY be derived from the PTP-synchronized clock,
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allowing the timestamp to be measured with respect to the clock of
an PTP Grandmaster clock.
The PTP truncated timestamp format is not affected by leap
seconds.
6.2. NTP 64-bit Timestamp Format
The Network Time Protocol (NTP) [RFC5905] timestamp format is 64 bits
long. This format is specified in Section 4.2.1 of [RFC8877], and
the details are presented below for the sake of completeness.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NTP [RFC5905] 64-bit Timestamp Format
Timestamp field format:
Seconds: specifies the integer portion of the number of seconds
since the epoch.
+ Size: 32 bits.
+ Units: seconds.
Fraction: specifies the fractional portion of the number of
seconds since the epoch.
+ Size: 32 bits.
+ Units: the unit is 2^(-32) seconds, which is roughly equal to
233 picoseconds.
Epoch:
The epoch is 1 January 1900 at 00:00 UTC.
Resolution:
The resolution is 2^(-32) seconds.
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Wraparound:
This time format wraps around every 2^32 seconds, which is roughly
136 years. The next wraparound will occur in the year 2036.
Synchronization Aspects:
Nodes that use this timestamp format will typically be
synchronized to UTC using NTP [RFC5905]. Thus, the timestamp MAY
be derived from the NTP-synchronized clock, allowing the timestamp
to be measured with respect to the clock of an NTP server.
The NTP timestamp format is affected by leap seconds; it
represents the number of seconds since the epoch minus the number
of leap seconds that have occurred since the epoch. The value of
a timestamp during or slightly after a leap second could be
temporarily inaccurate.
6.3. POSIX-based Timestamp Format
This timestamp format is based on the POSIX time format [POSIX]. The
detailed specification of the timestamp format used in this document
is presented below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Microseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: POSIX-based Timestamp Format
Timestamp field format:
Seconds: specifies the integer portion of the number of seconds
since the epoch.
+ Size: 32 bits.
+ Units: seconds.
Microseconds: specifies the fractional portion of the number of
seconds since the epoch.
+ Size: 32 bits.
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+ Units: the unit is microseconds. The value of this field is in
the range 0 to (10^6)-1.
Epoch:
The epoch is 1 January 1970 00:00:00 TAI, which is 31 December
1969 23:59:51.999918 UTC.
Resolution:
The resolution is 1 microsecond.
Wraparound:
This time format wraps around every 2^32 seconds, which is roughly
136 years. The next wraparound will occur in the year 2106.
Synchronization Aspects:
It is assumed that nodes that use this timestamp format run the
Linux operating system, and hence use the POSIX time. In some
cases nodes MAY be synchronized to UTC using a synchronization
mechanism that is outside the scope of this document, such as NTP
[RFC5905]. Thus, the timestamp MAY be derived from the NTP-
synchronized clock, allowing the timestamp to be measured with
respect to the clock of an NTP server.
The POSIX-based timestamp format is affected by leap seconds; it
represents the number of seconds since the epoch minus the number
of leap seconds that have occurred since the epoch. The value of
a timestamp during or slightly after a leap second could be
temporarily inaccurate.
7. IOAM Data Export
IOAM nodes collect information for packets traversing a domain that
supports IOAM. IOAM decapsulating nodes as well as IOAM transit
nodes can choose to retrieve IOAM information from the packet,
process the information further and export the information using
e.g., IPFIX. The mechanisms and associated data formats for
exporting IOAM data is outside the scope of this document.
Raw data export of IOAM data using IPFIX is discussed in
[I-D.spiegel-ippm-ioam-rawexport].
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8. IANA Considerations
This document requests the following IANA Actions.
IANA is requested to define a registry group named "In-Situ OAM
(IOAM) Protocol Parameters".
This group will include the following registries:
IOAM Option-Type
IOAM Trace-Type
IOAM Trace-Flags
IOAM POT-Type
IOAM POT-Flags
IOAM E2E-Type
IOAM Namespace-ID
New registries in this group can be created via RFC Required process
as per [RFC8126].
The subsequent sub-sections detail the registries herein contained.
8.1. IOAM Option-Type Registry
This registry defines 128 code points for the IOAM Option-Type field
for identifying IOAM Option-Types as explained in Section 5. The
following code points are defined in this draft:
0 IOAM Pre-allocated Trace Option-Type
1 IOAM Incremental Trace Option-Type
2 IOAM POT Option-Type
3 IOAM E2E Option-Type
4 - 127 are available for assignment via RFC Required process as per
[RFC8126].
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8.2. IOAM Trace-Type Registry
This registry defines code point for each bit in the 24-bit IOAM-
Trace-Type field for Pre-allocated trace option and Incremental trace
option defined in Section 5.4. The meaning of Bits 0 - 11 for trace
type are defined in this document in Paragraph 5 of Section 5.4.1:
Bit 0 hop_Lim and node_id in short format
Bit 1 ingress_if_id and egress_if_id in short format
Bit 2 timestamp seconds
Bit 3 timestamp subseconds
Bit 4 transit delay
Bit 5 namespace specific data in short format
Bit 6 queue depth
Bit 7 checksum complement
Bit 8 hop_Lim and node_id in wide format
Bit 9 ingress_if_id and egress_if_id in wide format
Bit 10 namespace specific data in wide format
Bit 11 buffer occupancy
Bit 22 variable length Opaque State Snapshot
Bit 23 reserved
The meaning for Bits 12 - 21 are available for assignment via RFC
Required process as per [RFC8126].
8.3. IOAM Trace-Flags Registry
This registry defines code points for each bit in the 4 bit flags for
the Pre-allocated trace option and for the Incremental trace option
defined in Section 5.4. The meaning of Bit 0 (the most significant
bit) for trace flags is defined in this document in Paragraph 3 of
Section 5.4.1:
Bit 0 "Overflow" (O-bit)
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Bit 1 - 3 are available for assignment via RFC Required process as
per [RFC8126].
8.4. IOAM POT-Type Registry
This registry defines 256 code points to define IOAM POT Type for
IOAM proof of transit option Section 5.5. The code point value 0 is
defined in this document:
0: 16 Octet POT data
1 - 255 are available for assignment via RFC Required process as per
[RFC8126].
8.5. IOAM POT-Flags Registry
This registry defines code points for each bit in the 8 bit flags for
IOAM POT option defined in Section 5.5. The meaning of Bit 0 for
IOAM POT flags is defined in this document in Section 5.5:
Bit 0 "Profile-to-use" (P-bit)
The meaning for Bits 1 - 7 are available for assignment via RFC
Required process as per [RFC8126].
8.6. IOAM E2E-Type Registry
This registry defines code points for each bit in the 16 bit IOAM-
E2E-Type field for IOAM E2E option Section 5.6. The meaning of Bit 0
- 3 are defined in this document:
Bit 0 64-bit sequence number
Bit 1 32-bit sequence number
Bit 2 timestamp seconds
Bit 3 timestamp subseconds
The meaning of Bits 4 - 15 are available for assignment via RFC
Required process as per [RFC8126].
8.7. IOAM Namespace-ID Registry
IANA is requested to set up an "IOAM Namespace-ID Registry",
containing 16-bit values. The meaning of Bit 0 is defined in this
document. IANA is requested to reserve the values 0x0001 to 0x7FFF
for private use (managed by operators), as specified in Section 5.3
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of the current document. Registry entries for the values 0x8000 to
0xFFFF are to be assigned via the "Expert Review" policy defined in
[RFC8126]. Upon a new allocation request, the responsible AD will
appoint a designated expert, who will review the allocation request.
The expert will post the request on the mailing list of the IPPM
working group in the IETF (ippm@ietf.org), and possibly on other
relevant mailing lists, to allow for community feedback. Based on
the review, the expert will either approve or deny the request. The
intention is that any allocation will be accompanied by a published
RFC. But in order to allow for the allocation of values prior to the
RFC being approved for publication, the designated expert can approve
allocations once it seems clear that an RFC will be published.
0: default namespace (known to all IOAM nodes)
0x0001 - 0x7FFF: reserved for private use
0x8000 - 0xFFFF: unassigned
9. Management and Deployment Considerations
This document defines the structure and use of IOAM data fields.
This document does not define the encapsulation of IOAM data fields
into different protocols. Management and deployment aspects for IOAM
have to be considered within the context of the protocol IOAM data
fields are encapsulated into and as such, are out of scope for this
document. For a discussion of IOAM deployment, please also refer to
[I-D.brockners-opsawg-ioam-deployment], which outlines a framework
for IOAM deployment and provides best current practices.
10. Security Considerations
As discussed in [RFC7276], a successful attack on an OAM protocol in
general, and specifically on IOAM, can prevent the detection of
failures or anomalies, or create a false illusion of nonexistent
ones. In particular, these threats are applicable by compromising
the integrity of IOAM data, either by maliciously modifying IOAM
options in transit, or by injecting packets with maliciously
generated IOAM options
The Proof of Transit Option-Type (Section Section 5.5) is used for
verifying the path of data packets. The security considerations of
POT are further discussed in [I-D.ietf-sfc-proof-of-transit].
From a confidentiality perspective, although IOAM options do not
contain user data, they can be used for network reconnaissance,
allowing attackers to collect information about network paths,
performance, queue states, buffer occupancy and other information.
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Moreover, if IOAM data leaks from the IOAM domain it could enable
reconnaissance beyond the scope of the IOAM domain. Note that in
case IOAM is used in "Direct Exporting" mode
[I-D.ioamteam-ippm-ioam-direct-export], the IOAM related trace
information would not be available in the customer data packets, but
would trigger export of packet related IOAM information at every
node, thus restricting the potential threat to the management plane
and mitigating the leakage threat. IOAM data exporting and the way
it is secured is outside the scope of this document.
IOAM can be used as a means for implementing Denial of Service (DoS)
attacks, or for amplifying them. For example, a malicious attacker
can add an IOAM header to packets in order to consume the resources
of network devices that take part in IOAM or entities that receive,
collect or analyze the IOAM data. Another example is a packet length
attack, in which an attacker pushes headers associated with IOAM
Option-Types into data packets, causing these packets to be increased
beyond the MTU size, resulting in fragmentation or in packet drops.
Since IOAM options can include timestamps, if network devices use
synchronization protocols then any attack on the time protocol
[RFC7384] can compromise the integrity of the timestamp-related data
fields.
At the management plane, attacks can be set up by misconfiguring or
by maliciously configuring IOAM-enabled nodes in a way that enables
other attacks. Thus, IOAM configuration has to be secured in a way
that authenticates authorized users and verifies the integrity of
configuration procedures.
Solutions to ensure the integrity of IOAM data fields are outside the
scope of this document. [I-D.brockners-ippm-ioam-data-integrity]
discusses several methods to ensure the integrity of IOAM data fields
for those deployments that have a need to protect the integrity of
IOAM data fields.
The current document does not define a specific IOAM encapsulation.
It has to be noted that some IOAM encapsulation types can introduce
specific security considerations. A specification that defines an
IOAM encapsulation is expected to address the respective
encapsulation-specific security considerations.
Notably, in most cases IOAM is expected to be deployed in specific
network domains, thus confining the potential attack vectors to
within the network domain. A limited administrative domain provides
the operator with the means to select, monitor, and control the
access of all the network devices, making these devices trusted by
the operator. Indeed, in order to limit the scope of threats
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mentioned above to within the current network domain the network
operator is expected to enforce policies that prevent IOAM traffic
from leaking outside of the IOAM domain, and prevent IOAM data from
outside the domain to be processed and used within the domain.
The security considerations of a system that deploys IOAM, much like
any system, has to be reviewed on a per-deployment-scenario basis,
based on a systems-specific threat analysis, which can lead to
specific security solutions that are beyond the scope of the current
document. Specifically, in an IOAM deployment that is not confined
to a single LAN, but spans multiple inter-connected sites (for
example, using an overlay network), the inter-site links can be
secured (e.g., by IPsec) in order to avoid external threats.
IOAM deployment considerations, including approaches to mitigate the
above discussed threads and potential attacks are outside the scope
of this document. IOAM deployment considerations are discussed in
[I-D.brockners-opsawg-ioam-deployment].
11. Acknowledgements
The authors would like to thank Eric Vyncke, Nalini Elkins, Srihari
Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya
Nadahalli, LJ Wobker, Erik Nordmark, Vengada Prasad Govindan, Andrew
Yourtchenko, Aviv Kfir, Tianran Zhou, Zhenbin (Robin) and Greg Mirsky
for the comments and advice.
This document leverages and builds on top of several concepts
described in [I-D.kitamura-ipv6-record-route]. The authors would
like to acknowledge the work done by the author Hiroshi Kitamura and
people involved in writing it.
The authors would like to gracefully acknowledge useful review and
insightful comments received from Joe Clarke, Al Morton, Tom Herbert,
Haoyu Song, Mickey Spiegel and Barak Gafni.
12. References
12.1. Normative References
[IEEE1588v2]
Institute of Electrical and Electronics Engineers, "IEEE
Std 1588-2008 - IEEE Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", IEEE Std 1588-2008, 2008,
<http://standards.ieee.org/findstds/
standard/1588-2008.html>.
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[POSIX] Institute of Electrical and Electronics Engineers, "IEEE
Std 1003.1-2008 (Revision of IEEE Std 1003.1-2004) - IEEE
Standard for Information Technology - Portable Operating
System Interface (POSIX(R))", IEEE Std 1003.1-2008, 2008,
<https://standards.ieee.org/findstds/
standard/1003.1-2008.html>.
[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>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<https://www.rfc-editor.org/info/rfc5905>.
[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>.
12.2. Informative References
[I-D.brockners-ippm-ioam-data-integrity]
Brockners, F., Bhandari, S., and T. Mizrahi, "Integrity of
In-situ OAM Data Fields", draft-brockners-ippm-ioam-data-
integrity-00 (work in progress), January 2021.
[I-D.brockners-opsawg-ioam-deployment]
Brockners, F., Bhandari, S., and d.
daniel.bernier@bell.ca, "In-situ OAM Deployment", draft-
brockners-opsawg-ioam-deployment-02 (work in progress),
September 2020.
[I-D.ietf-nvo3-geneve]
Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
Network Virtualization Encapsulation", draft-ietf-
nvo3-geneve-16 (work in progress), March 2020.
[I-D.ietf-nvo3-vxlan-gpe]
Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol
Extension for VXLAN (VXLAN-GPE)", draft-ietf-nvo3-vxlan-
gpe-10 (work in progress), July 2020.
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[I-D.ietf-sfc-proof-of-transit]
Brockners, F., Bhandari, S., Mizrahi, T., Dara, S., and S.
Youell, "Proof of Transit", draft-ietf-sfc-proof-of-
transit-08 (work in progress), November 2020.
[I-D.ioamteam-ippm-ioam-direct-export]
Song, H., Gafni, B., Zhou, T., Li, Z., Brockners, F.,
Bhandari, S., Sivakolundu, R., and T. Mizrahi, "In-situ
OAM Direct Exporting", draft-ioamteam-ippm-ioam-direct-
export-00 (work in progress), October 2019.
[I-D.kitamura-ipv6-record-route]
Kitamura, H., "Record Route for IPv6 (PR6) Hop-by-Hop
Option Extension", draft-kitamura-ipv6-record-route-00
(work in progress), November 2000.
[I-D.spiegel-ippm-ioam-rawexport]
Spiegel, M., Brockners, F., Bhandari, S., and R.
Sivakolundu, "In-situ OAM raw data export with IPFIX",
draft-spiegel-ippm-ioam-rawexport-04 (work in progress),
November 2020.
[RFC7276] Mizrahi, T., Sprecher, N., Bellagamba, E., and Y.
Weingarten, "An Overview of Operations, Administration,
and Maintenance (OAM) Tools", RFC 7276,
DOI 10.17487/RFC7276, June 2014,
<https://www.rfc-editor.org/info/rfc7276>.
[RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
October 2014, <https://www.rfc-editor.org/info/rfc7384>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
[RFC7820] Mizrahi, T., "UDP Checksum Complement in the One-Way
Active Measurement Protocol (OWAMP) and Two-Way Active
Measurement Protocol (TWAMP)", RFC 7820,
DOI 10.17487/RFC7820, March 2016,
<https://www.rfc-editor.org/info/rfc7820>.
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[RFC7821] Mizrahi, T., "UDP Checksum Complement in the Network Time
Protocol (NTP)", RFC 7821, DOI 10.17487/RFC7821, March
2016, <https://www.rfc-editor.org/info/rfc7821>.
[RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed.,
"Network Service Header (NSH)", RFC 8300,
DOI 10.17487/RFC8300, January 2018,
<https://www.rfc-editor.org/info/rfc8300>.
[RFC8877] Mizrahi, T., Fabini, J., and A. Morton, "Guidelines for
Defining Packet Timestamps", RFC 8877,
DOI 10.17487/RFC8877, September 2020,
<https://www.rfc-editor.org/info/rfc8877>.
[SSS] "Shamir's Secret Sharing",
<https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing>.
Contributors' Addresses
Carlos Pignataro
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
United States
Email: cpignata@cisco.com
Mickey Spiegel
Barefoot Networks, an Intel company
4750 Patrick Henry Drive
Santa Clara, CA 95054
US
Email: mickey.spiegel@intel.com
Barak Gafni
Nvidia
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
U.S.A.
Email: gbarak@nvidia.com
Jennifer Lemon
Broadcom
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270 Innovation Drive
San Jose, CA 95134
US
Email: jennifer.lemon@broadcom.com
Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
John Leddy
United States
Email: john@leddy.net
Stephen Youell
JP Morgan Chase
25 Bank Street
London E14 5JP
United Kingdom
Email: stephen.youell@jpmorgan.com
David Mozes
Email: mosesster@gmail.com
Petr Lapukhov
Facebook
1 Hacker Way
Menlo Park, CA 94025
US
Email: petr@fb.com
Remy Chang
Barefoot Networks
4750 Patrick Henry Drive
Santa Clara, CA 95054
US
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Email: remy@barefootnetworks.com
Daniel Bernier
Bell Canada
Canada
Email: daniel.bernier@bell.ca
Authors' Addresses
Frank Brockners (editor)
Cisco Systems, Inc.
Hansaallee 249, 3rd Floor
DUESSELDORF, NORDRHEIN-WESTFALEN 40549
Germany
Email: fbrockne@cisco.com
Shwetha Bhandari (editor)
Thoughtspot
3rd Floor, Indiqube Orion, 24th Main Rd, Garden Layout, HSR Layout
Bangalore, KARNATAKA 560 102
India
Email: shwetha.bhandari@thoughtspot.com
Tal Mizrahi (editor)
Huawei
8-2 Matam
Haifa 3190501
Israel
Email: tal.mizrahi.phd@gmail.com
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