Data Fields for In Situ Operations, Administration, and Maintenance (IOAM)
draft-ietf-ippm-ioam-data-17
The information below is for an old version of the document that is already published as an RFC.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 9197.
|
|
|---|---|---|---|
| Authors | Frank Brockners , Shwetha Bhandari , Tal Mizrahi | ||
| Last updated | 2022-06-16 (Latest revision 2021-12-13) | ||
| Replaces | draft-brockners-inband-oam-data, draft-ippm-ioam-data | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Reviews |
GENART Last Call review
(of
-11)
by Dan Romascanu
Ready w/nits
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Al Morton | ||
| Shepherd write-up | Show Last changed 2020-05-30 | ||
| IESG | IESG state | Became RFC 9197 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Martin Duke | ||
| IESG note | |||
| Send notices to | Al Morton <acm@research.att.com> | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack |
draft-ietf-ippm-ioam-data-17
ippm F. Brockners, Ed.
Internet-Draft Cisco
Intended status: Standards Track S. Bhandari, Ed.
Expires: June 16, 2022 Thoughtspot
T. Mizrahi, Ed.
Huawei
December 13, 2021
Data Fields for In-situ OAM
draft-ietf-ippm-ioam-data-17
Abstract
In-situ Operations, Administration, and Maintenance (IOAM) records
operational and telemetry information in the packet while the packet
traverses a path 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, or IPv6. 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 June 16, 2022.
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 . . . . . . . . . . . . 7
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 . . . . . . . . . 19
5.4.2.3. timestamp seconds . . . . . . . . . . . . . . . . 19
5.4.2.4. timestamp fraction . . . . . . . . . . . . . . . 20
5.4.2.5. transit delay . . . . . . . . . . . . . . . . . . 20
5.4.2.6. namespace specific data . . . . . . . . . . . . . 20
5.4.2.7. queue depth . . . . . . . . . . . . . . . . . . . 21
5.4.2.8. Checksum Complement . . . . . . . . . . . . . . . 21
5.4.2.9. Hop_Lim and node_id wide . . . . . . . . . . . . 22
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 . . . . . . . . . . . . . . . . 23
5.4.2.13. Opaque State Snapshot . . . . . . . . . . . . . . 23
5.4.3. Examples of IOAM node data . . . . . . . . . . . . . 24
5.5. IOAM Proof of Transit Option-Type . . . . . . . . . . . . 26
5.5.1. IOAM Proof of Transit Type 0 . . . . . . . . . . . . 28
5.6. IOAM Edge-to-Edge Option-Type . . . . . . . . . . . . . . 28
6. Timestamp Formats . . . . . . . . . . . . . . . . . . . . . . 31
6.1. PTP Truncated Timestamp Format . . . . . . . . . . . . . 31
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 . . . . . . . . . . . . . . . . 37
8.4. IOAM POT-Type Registry . . . . . . . . . . . . . . . . . 37
8.5. IOAM POT-Flags Registry . . . . . . . . . . . . . . . . . 38
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8.6. IOAM E2E-Type Registry . . . . . . . . . . . . . . . . . 38
8.7. IOAM Namespace-ID Registry . . . . . . . . . . . . . . . 39
9. Management and Deployment Considerations . . . . . . . . . . 40
10. Security Considerations . . . . . . . . . . . . . . . . . . . 40
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 43
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 43
12.1. Normative References . . . . . . . . . . . . . . . . . . 43
12.2. Informative References . . . . . . . . . . . . . . . . . 44
Contributors' Addresses . . . . . . . . . . . . . . . . . . . . . 45
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 47
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 I. 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 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.
The term "in situ OAM" was originally motivated by the use of OAM
related mechanisms that add information into a packet. This document
uses IOAM as a term defining the IOAM technology. IOAM includes "in-
situ" mechanisms, but also mechanisms that could trigger the creation
of additional packets dedicated to OAM.
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", "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.
Abbreviations and definitions used in this document:
E2E: Edge to Edge
Geneve: Generic Network Virtualization Encapsulation [RFC8926]
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
Short format: "Short format" refers to an IOAM-Data-Field which
comprises 4 octets.
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SID: Segment Identifier
SR: Segment Routing
VXLAN-GPE: Virtual eXtensible Local Area Network, Generic Protocol
Extension [I-D.ietf-nvo3-vxlan-gpe]
Wide format: "Wide format" refers to an IOAM-Data-Field which
comprises 8 octets.
4. Scope, Applicability, and Assumptions
IOAM assumes a set of constraints as well as guiding principles and
concepts that go hand in hand with the definition of the IOAM data
fields. These constraints, guiding principles, and concepts are
described in this section. A discussion of how IOAM data fields and
the associated concepts are applied to an IOAM deployment are out of
scope for this document. Please refer to
[I-D.ietf-ippm-ioam-deployment] for IOAM deployment considerations.
Scope: This document defines the data fields and associated data
types for in-situ OAM. The in-situ OAM data fields can be
encapsulated in a variety of protocols, including NSH, Segment
Routing, Geneve, and IPv6. Specification details for these different
protocols are outside the scope of this document. It is expected
that each such encapsulation would be specified by an RFC, jointly
designed by the working group that develops or maintains the
encapsulation protocol and the IETF IPPM working group.
Deployment domain (or scope) of in-situ OAM deployment: IOAM is
focused on "limited domains" as defined in [RFC8799]. For IOAM, a
limited domain could for example be an enterprise campus using
physical connections between devices or an overlay network using
virtual connections / tunnels for connectivity between said devices.
A limited domain which uses IOAM may constitute one or multiple
"IOAM-domains", each disambiguated through separate namespace
identifiers. An IOAM-domain is bounded by its perimeter or edge.
IOAM-domains may overlap inside the limited domain. 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 SHOULD 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)
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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 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 user traffic. Using IOAM on a selected 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.
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.
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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.
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
Future IOAM-Option-Types can be allocated by IANA, as described in
Section 8.1.
5.2. IOAM-Domains and types of IOAM Nodes
Section 4 already mentioned that IOAM is expected to be deployed in a
limited domain [RFC8799]. One or more IOAM-Option-Types are added to
a packet upon entering an 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 an "IOAM encapsulating node", whereas a device which removes
an IOAM-Option-Type is referred to as an "IOAM decapsulating node".
Nodes within the domain which are aware of IOAM data and read and/or
write and/or process 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
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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" reads and/or writes and/or processes one or
more of the IOAM-Data-Fields. If both the Pre-allocated and the
Incremental Trace Option-Types are present in the packet, each IOAM
transit node based on configuration and available implementation of
IOAM might populate IOAM trace data in either Pre-allocated or
Incremental Trace Option-Type but not both. Note that not populating
any of the Trace Option-Types is also valid behavior for an IOAM
transit node. 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.
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
IOAM-Namespaces add further context to IOAM-Option-Types and
associated IOAM-Data-Fields. The IOAM-Option-Types and associated
IOAM-Data-Fields are interpreted as defined in this document,
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regardless of the value of the IOAM-Namespace. However, IOAM-
Namespaces provide a way to group nodes to support different
deployment approaches of IOAM (see a few example use-cases below).
IOAM-Namespaces also help to resolve potential 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. Given
that IOAM-Data-Fields are always interpreted the context of a
specific namespace, the namespace-id field always needs to be carried
along with the IOAM data-fields themselves.
An IOAM-Namespace is identified by a 16-bit namespace identifier
(Namespace-ID). The IOAM-Namespace field is included in all the
IOAM-Option-Types defined in this document, and MUST be included in
all future 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) have to be removed from the packet,
e.g., at a domain edge or domain boundary.
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IOAM-Namespaces support several different uses:
o IOAM-Namespaces can be used by an operator to distinguish
different IOAM-domains. Devices at edges of an IOAM-domain can
filter on Namespace-IDs to provide for proper IOAM-domain
isolation.
o IOAM-Namespaces provide additional context for IOAM-Data-Fields
and thus can be used to ensure that IOAM-Data-Fields are unique
and are interpreted properly by management stations or network
controllers. The node identifier field (node_id, see below) does
not need to be unique in a deployment. This could be the case 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, such as after a
merger of two formerly separated organizations. The Namespace-ID
can be used as a context identifier, such that the combination of
node_id and Namespace-ID will always be unique.
o 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.
o By 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
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captured IOAM-Data-Fields of the two IOAM-Namespaces need to be
correlated.
5.4. IOAM Trace Option-Types
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) can 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. A deployment can 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
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its node data immediately following the option header. This type
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 subject to any protocol constraints of
the encapsulating layer. They then decrease the remaining length
available to subsequent nodes and adjust the lengths and possibly
checksums in outer headers.
IOAM encapsulating nodes and IOAM decapsulating nodes which support
tracing MUST support both Trace-Option-Types. For IOAM transit nodes
it is sufficient to support one of the Trace-Option-Types. In the
event that both options are utilized in a deployment 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-
domain, 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
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feasible and expected, though it is important that all devices of
an IOAM-domain follow the same definition.
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.
It should be noted that the semantics of some of the node data fields
that are defined below, such as the queue depth and buffer occupancy,
are implementation specific. This approach is intended to allow IOAM
nodes with various different architectures.
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 in wide format, 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.
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). In case a
network element is supposed to add node data to a packet, but
detects that there are not enough octets left to record the
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.
The sender MUST assign the initial value of the RemainingLen
field. The sender MAY calculate the value of the RemainingLen
field by computing the number of node data bytes allowed before
exceeding the path MTU (PMTU), given that the PMTU is known to the
sender. 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 lower layer header
(which is not within the scope of this document), 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.
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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
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 fraction 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. These values are available for future
assignment in the IOAM Trace-Type Registry (Section 8.2).
Every future node data field corresponding to one of
these bits MUST be 4-octets long. An IOAM encapsulating
node MUST set the value of each undefined bit to 0. If
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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
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. This bit is reserved to allow for
future extensions of the IOAM-Trace-Type bit field.
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
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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". The use of "short format" or "wide format" is
not mutually exclusive. A deployment could choose to leverage both.
For example, ingress_if_id_(short 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. The definition of
IOAM-Data-Fields focuses on the syntax of the data-fields and avoids
specifying the semantics where feasible. This is why no units are
defined for data-fields like e.g., "buffer occupancy" or "queue
depth". With this approach, nodes can supply the information in
their native format and are not required to perform unit or format
conversions. Systems that further process IOAM information, like
e.g., a network management system are assumed to also handle unit
conversions as part of their IOAM data-fields processing. The
combination of a particular data-field and the namespace-id provides
for the context to interpret the provided data appropriately.
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 egress from 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
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IOAM-Domain. The procedure to allocate, manage and map the
node_ids is beyond the scope of this document. See
[I-D.ietf-ippm-ioam-deployment] for a discussion of deployment
related aspects of the node_id.
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.
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.
It contains the 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 (see e.g., [RFC8877]), 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.
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5.4.2.4. timestamp fraction
The "timestamp fraction" field is a 4-octet unsigned integer field.
Fraction specifies the fractional portion of the number of seconds
since the NTP epoch [RFC8877]. The field specifies the time at which
the packet was received by the node. This field has three possible
formats; based on either PTP (see e.g., [RFC8877]), NTP [RFC5905], or
POSIX [POSIX]. The three timestamp formats are specified in
Section 6. In all three cases, the Timestamp fraction 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
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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. See Section 5.4.2.1 for the
definition of the 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.
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.
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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
The format used for the entries in a packet's "node data list" array
can vary from packet to packet and deployment to deployment". Some
deployments might only be interested in recording the node
identifiers, whereas others might be interested in recording node
identifiers and timestamps. This section provides example entries of
the "node data list".
0xD40000: IOAM-Trace-Type is 0xD40000 (0b110101000000000000000000)
then the format of node data is:
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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 fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x940000: IOAM-Trace-Type is 0x940000 (0b100101000000000000000000)
then the format is:
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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 fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 used to support path or service
function chain [RFC7665] verification use cases, i.e., prove that
traffic transited a defined path. 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, proof of transit approaches share the need to uniquely
identify a packet as well as iteratively operate on a set of
information that is handed from node to node. Correspondingly, two
pieces of information are added as IOAM-Data-Fields to the packet:
o PktID: Unique identifier for the packet.
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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 to carry data associated to POT
procedures.
If a node receives an IOAM POT Type value that it does not
understand, the node MUST NOT change, add to, or remove the
contents of the OAM-Data-Fields.
IOAM POT flags: 8-bit. This document does not define any flags.
Bits 0-7 These bits are available for assignment, see Section 8.5.
Bits which have not been assigned MUST be set to zero upon
transmission and ignored upon receipt.
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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|R R R R R R R R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| PktID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ P
| PktID (contd) | O
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ T
| Cumulative | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Cumulative (contd) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
Namespace-ID: 16-bit identifier of an IOAM-Namespace (see
Section 5.5 above).
IOAM POT Type: 8-bit identifier of a particular POT variant that
specifies the POT data that is included (see Section 5.5 above).
For this case here, IOAM POT Type is set to the value 0.
Bit 0-7: Undefined (see Section 5.5 above).
PktID: 64-bit packet identifier.
Cumulative: 64-bit Cumulative that is updated at specific nodes by
processing per packet PktID field and configured parameters.
Note: Larger or smaller sizes of "PktID" 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
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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. When this bit is set, "Bit 1" (for 32-bit
sequence number, see below) MUST be zero.
Bit 1 When set indicates presence of a 32-bit sequence number
added to a specific "packet group" which is used to
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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. When this bit is set, "Bit 0" (for 64-bit
sequence number, see above) MUST be zero.
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 (see e.g., [RFC8877]), 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.
Bit 3 When set indicates presence of timestamp fraction,
representing the time at which the packet entered the
IOAM-domain. This 4-octet field has three possible
formats; based on either PTP (see e.g., [RFC8877]), NTP
[RFC5905], or POSIX [POSIX]. The three timestamp formats
are specified in Section 6. In all three cases, the
Timestamp fraction 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.
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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) 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.
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 Truncated Timestamp Format
Timestamp field format:
Seconds: specifies the integer portion of the number of seconds
since the PTP epoch.
+ Size: 32 bits.
+ Units: seconds.
Nanoseconds: specifies the fractional portion of the number of
seconds since the PTP epoch.
+ Size: 32 bits.
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+ Units: nanoseconds. The value of this field is in the range 0
to (10^9)-1.
Epoch:
PTP epoch. For details see e.g., [RFC8877].
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 is used for synchronization, the timestamp
MAY be derived from the PTP-synchronized clock, allowing the
timestamp to be measured with respect to the clock of an PTP
Grandmaster clock.
6.2. NTP 64-bit Timestamp Format
The Network Time Protocol (NTP) [RFC5905] timestamp format is 64 bits
long. This specification uses the NTP timestamp format that 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 NTP epoch.
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+ Size: 32 bits.
+ Units: seconds.
Fraction: specifies the fractional portion of the number of
seconds since the NTP epoch.
+ Size: 32 bits.
+ Units: the unit is 2^(-32) seconds, which is roughly equal to
233 picoseconds.
Epoch:
NTP Epoch. For details see [RFC5905].
Resolution:
The resolution is 2^(-32) seconds.
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.
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
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Timestamp field format:
Seconds: specifies the integer portion of the number of seconds
since the POSIX epoch.
+ Size: 32 bits.
+ Units: seconds.
Microseconds: specifies the fractional portion of the number of
seconds since the POSIX epoch.
+ Size: 32 bits.
+ Units: the unit is microseconds. The value of this field is in
the range 0 to (10^6)-1.
Epoch:
POSIX epoch. For details, see [POSIX], appendix A.4.16.
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.
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.
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A way to perform raw data export of IOAM data using IPFIX is
discussed in [I-D.spiegel-ippm-ioam-rawexport].
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
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 "IETF Review" process as per
[RFC8126].
New registration requests MUST use the following template:
Name: Name of the newly registered Option-Type.
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Code point: Desired value of the requested code point.
Description: Brief description of the newly registered Option-Type.
Reference: Reference to the document that defines the new Option-
Type.
The evaluation of a new registration request MUST also include
checking whether the new IOAM Option-Type includes an IOAM-Namespace
field and that the IOAM-Namespace field is the first field in the
newly defined header of the new Option-Type.
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-Type and Incremental
Trace-Option-Type defined in Section 5.4. The meaning of Bits 0 - 11
is 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 fraction
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
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The meaning for Bits 12 - 21 are available for assignment via "IETF
Review" process as per [RFC8126].
New registration requests MUST use the following template:
Bit: Desired bit to be allocated in the 24-bit IOAM Trace-Option-
Type field for Pre-allocated Trace-Option-Type and Incremental
Trace-Option-Type.
Description: Brief description of the newly registered bit.
Reference: Reference to the document that defines the new bit.
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)
Bit 1 - 3 are available for assignment via "IETF Review" process as
per [RFC8126].
New registration requests MUST use the following template:
Bit: Desired bit to be allocated in the 8 bit flags field of the
Pre-allocated Trace-Option-Type and for the Incremental Trace-
Option-Type.
Description: Brief description of the newly registered bit.
Reference: Reference to the document that defines the new bit.
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 "IETF Review" process as per
[RFC8126].
New registration requests MUST use the following template:
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Name: Name of the newly registered POT-Type.
Code point: Desired value of the requested code point.
Description: Brief description of the newly registered POT-Type.
Reference: Reference to the document that defines the new POT-Type.
8.5. IOAM POT-Flags Registry
This registry defines code points for each bit in the 8 bit flags for
IOAM POT Option-Type defined in Section 5.5.
The meaning for Bits 0 - 7 are available for assignment via "IETF
Review" process as per [RFC8126].
New registration requests MUST use the following template:
Bit: Desired bit to be allocated in the 8 bit flags field of the
IOAM POT Option-Type.
Description: Brief description of the newly registered bit.
Reference: Reference to the document that defines the new bit.
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 fraction
The meaning of Bits 4 - 15 are available for assignment via "IETF
Review" process as per [RFC8126].
New registration requests MUST use the following template:
Bit: Desired bit to be allocated in the 16 bit IOAM-E2E-Type field.
Description: Brief description of the newly registered bit.
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Reference: Reference to the document that defines the new bit.
8.7. IOAM Namespace-ID Registry
IANA is requested to set up an "IOAM Namespace-ID Registry",
containing 16-bit values and following the template for requests
shown below. The meaning of 0x0000 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 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 receiving a new allocation request, a designated expert will
perform the following:
o Review whether the request is complete, i.e., the registration
template has been filled in. The expert will send incomplete
requests back to the requestor.
o Check whether the request is neither a duplicate of nor
conflicting with either an already existing allocation or a
pending allocation. In case of duplicates or conflicts, the
expert will ask the requestor to update the allocation request
accordingly.
o Solicit feedback from relevant working groups and communities to
ensure that the new allocation request has been properly reviewed
and that rough consensus on the request exists. At a minimum, the
expert will solicit feedback from the IPPM working group in the
IETF by posting the request to the ippm@ietf.org mailing list.
The expert will allow for a 3-week review period on the mailing
lists. If the feedback received from the relevant working groups
and communities within the review period indicates rough consensus
on the request, the expert will approve the request and ask IANA
for allocating the new Namespace-ID. In case the expert senses a
lack of consensus from the feedback received, the expert will ask
the requestor to engage with the corresponding working groups and
communities to further review and refine the request.
It is intended that any allocation will be accompanied by a published
RFC. In order to allow for the allocation of code points prior to
the RFC being approved for publication, the designated expert can
approve allocations once it seems clear that an RFC will be
published.
0x0000: default namespace (known to all IOAM nodes)
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0x0001 - 0x7FFF: reserved for private use
0x8000 - 0xFFFF: unassigned
New registration requests MUST use the following template:
Name: Name of the newly registered Namespace-ID.
Code point: Desired value of the requested Namespace-ID.
Description: Brief description of the newly registered Namespace-ID.
Reference: Reference to the document that defines the new Namespace-
ID.
Status of the registration: Status can be either "permanent" or
"provisional". Namespace-ID registrations following a successful
expert review will have the status "provisional". Once the RFC,
which defines the new Namespace-ID is published, the status is
changed to "permanent".
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.ietf-ippm-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. All nodes in the path of a IOAM carrying
packet can perform such an attack.
The Proof of Transit Option-Type (see Section 5.5) is used for
verifying the path of data packets, i.e., proving that packets
transited through a defined set of nodes.
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In case an attacker gains access to several nodes in a network and
would be able to change the system software of these nodes, IOAM data
fields could be misused and repurposed for a use different from what
is specified in this document. One type of misuse is the
implementation of a covert channel between network nodes.
From a confidentiality perspective, although IOAM options are not
expected to 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. Moreover, if IOAM data leaks from the IOAM-domain it
could enable reconnaissance beyond the scope of the IOAM-domain. One
possible application of such reconnaissance is to gauge the
effectiveness of an ongoing attack, e.g., if buffers and queues are
overflowing.
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.
In case POT is used, an attacker could corrupt the POT data fields in
the packet, resulting in a verification failure of the POT data, even
if the packet followed the correct path.
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. IOAM configuration should only managed by authorized
processes or users.
IETF protocols require features to ensure their security. While IOAM
data fields don't represent a protocol by themselves, the IOAM data
fields add to the protocol that the IOAM data fields are encapsulated
into. Any specification that defines how IOAM data fields carried in
an encapsulating protocol MUST provide for a mechanism for
cryptographic integrity protection of the IOAM data fields.
Cryptographic integrity protection could be either achieved through a
mechanism of the encapsulating protocol or it could incorporate the
mechanisms specified in [I-D.ietf-ippm-ioam-data-integrity].
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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, IOAM is expected to be deployed in limited domains, thus
confining the potential attack vectors to within the limited 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 mentioned above to within the
current limited 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.
This document does not define the data contents of custom fields like
"Opaque State Snapshot" and "namespace specific data" IOAM data
fields. These custom data fields will have security considerations
corresponding to their defined data contents that need to be
described where those formats are defined.
IOAM deployments which leverage both IOAM Trace Option-Types, i.e.,
the Pre-allocated Trace Option-Type and Incremental Trace Option-Type
can suffer from incomplete visibility if the information gathered via
the two Trace Option-Types is not correlated and aggregated
appropriately. If IOAM transit nodes leverage the IOAM data fields
in the packet for further actions or insights, then IOAM transit
nodes which only support one IOAM Trace Option-Type in an IOAM
deployment which leverages both Trace Option-Types, have limited
visibility and thus can draw inappropriate conclusions or take wrong
actions.
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.ietf-ippm-ioam-deployment].
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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,
Carlos Bernardos, Haoyu Song, Mickey Spiegel, Roman Danyliw, Benjamin
Kaduk, Murray S. Kucherawy, Ian Swett, Martin Duke, Francesca
Palombini, Lars Eggert, Alvaro Retana, Erik Kline, Robert Wilton,
Zaheduzzaman Sarker, Dan Romascanu and Barak Gafni.
12. References
12.1. Normative References
[POSIX] Institute of Electrical and Electronics Engineers, "IEEE
Std 1003.1-2017 (Revision of IEEE Std 1003.1-2017) - IEEE
Standard for Information Technology - Portable Operating
System Interface (POSIX(TM) Base Specifications, Issue
7)", IEEE Std 1003.1-2017, 2017,
<https://standards.ieee.org/findstds/
standard/1003.1-2017.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>.
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[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>.
12.2. Informative References
[I-D.ietf-ippm-ioam-data-integrity]
Brockners, F., Bhandari, S., and T. Mizrahi, "Integrity of
In-situ OAM Data Fields", draft-ietf-ippm-ioam-data-
integrity-00 (work in progress), October 2021.
[I-D.ietf-ippm-ioam-deployment]
Brockners, F., Bhandari, S., Bernier, D., and T. Mizrahi,
"In-situ OAM Deployment", draft-ietf-ippm-ioam-
deployment-00 (work in progress), October 2021.
[I-D.ietf-nvo3-vxlan-gpe]
(Editor), F. M., (editor), L. K., and U. E. (editor),
"Generic Protocol Extension for VXLAN (VXLAN-GPE)", draft-
ietf-nvo3-vxlan-gpe-12 (work in progress), September 2021.
[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-05 (work in progress),
July 2021.
[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>.
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[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>.
[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>.
[RFC8799] Carpenter, B. and B. Liu, "Limited Domains and Internet
Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020,
<https://www.rfc-editor.org/info/rfc8799>.
[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>.
[RFC8926] Gross, J., Ed., Ganga, I., Ed., and T. Sridhar, Ed.,
"Geneve: Generic Network Virtualization Encapsulation",
RFC 8926, DOI 10.17487/RFC8926, November 2020,
<https://www.rfc-editor.org/info/rfc8926>.
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
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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
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
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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
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
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Tal Mizrahi (editor)
Huawei
8-2 Matam
Haifa 3190501
Israel
Email: tal.mizrahi.phd@gmail.com
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