Internet DRAFT - draft-ietf-ippm-ioam-direct-export
draft-ietf-ippm-ioam-direct-export
IPPM H. Song
Internet-Draft Futurewei
Intended status: Standards Track B. Gafni
Expires: 27 March 2023 Nvidia
F. Brockners
Cisco
S. Bhandari
Thoughtspot
T. Mizrahi
Huawei
23 September 2022
In-situ OAM Direct Exporting
draft-ietf-ippm-ioam-direct-export-11
Abstract
In-situ Operations, Administration, and Maintenance (IOAM) is used
for recording and collecting operational and telemetry information.
Specifically, IOAM allows telemetry data to be pushed into data
packets while they traverse the network. This document introduces a
new IOAM option type (denoted IOAM-Option-Type) called the Direct
Export (DEX) Option-Type, which is used as a trigger for IOAM data to
be directly exported or locally aggregated without being pushed into
in-flight data packets. The exporting method and format are outside
the scope of this document.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 27 March 2023.
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Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirement Language . . . . . . . . . . . . . . . . . . 3
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. The Direct Exporting (DEX) IOAM-Option-Type . . . . . . . . . 3
3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. DEX Packet Selection . . . . . . . . . . . . . . . . 5
3.1.2. Responding to the DEX Trigger . . . . . . . . . . . . 6
3.2. The DEX Option-Type Format . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
4.1. IOAM Type . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. IOAM DEX Flags . . . . . . . . . . . . . . . . . . . . . 9
4.3. IOAM DEX Extension-Flags . . . . . . . . . . . . . . . . 9
5. Performance Considerations . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative References . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Notes About the History of this Document . . . . . . 14
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
IOAM [RFC9197] is used for monitoring traffic in the network, and for
incorporating IOAM data fields (denoted IOAM-Data-Fields) into in-
flight data packets.
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IOAM makes use of four possible IOAM-Option-Types, defined in
[RFC9197]: Pre-allocated Trace Option-Type, Incremental Trace Option-
Type, Proof of Transit (POT) Option-Type, and Edge-to-Edge Option-
Type.
This document defines a new IOAM-Option-Type called the Direct Export
(DEX) Option-Type. This Option-Type is used as a trigger for IOAM
nodes to locally aggregate and process IOAM data, and/or to export it
to a receiving entity (or entities). Throughout the document this
functionality is referred to as collection and/or exporting. A
"receiving entity" in this context is an entity that resides within
the IOAM domain such as a collector, analyzer, controller,
decapsulating node, or a software module in one of the IOAM nodes.
Note that even though the IOAM-Option-Type is called "Direct Export",
it depends on the deployment whether the receipt of a packet with DEX
Option-Type leads to the creation of another packet. Some
deployments might simply use the packet with the DEX Option-Type to
trigger local processing of OAM data. The functionality of this
local processing is not within the scope of this document.
2. Conventions
2.1. Requirement Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.2. Terminology
Abbreviations used in this document:
IOAM: In-situ Operations, Administration, and Maintenance
OAM: Operations, Administration, and Maintenance [RFC6291]
DEX: Direct EXporting
3. The Direct Exporting (DEX) IOAM-Option-Type
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3.1. Overview
The DEX Option-Type is used as a trigger for collecting IOAM data
locally or for exporting it to a receiving entity (or entities).
Specifically, the DEX Option-Type can be used as a trigger for
collecting IOAM data by an IOAM node and locally aggregating it;
thus, this aggregated data can be periodically pushed to a receiving
entity, or pulled by a receiving entity on-demand.
This Option-Type is incorporated into data packets by an IOAM
encapsulating node, and removed by an IOAM decapsulating node, as
illustrated in Figure 1. The Option-Type can be read but not
modified by transit nodes. Note: the terms IOAM encapsulating,
decapsulating and transit nodes are as defined in [RFC9197].
^
|Exported IOAM data
|
|
|
+--------------+------+-------+--------------+
| | | |
| | | |
User +---+----+ +---+----+ +---+----+ +---+----+
packets |Encapsu-| | Transit| | Transit| |Decapsu-|
--------->|lating |====>| Node |====>| Node |====>|lating |---->
|Node | | A | | B | |Node |
+--------+ +--------+ +--------+ +--------+
Insert DEX Export Export Remove DEX
option and IOAM data IOAM data option and
export data export data
Figure 1: DEX Architecture
The DEX Option-Type is used as a trigger to collect and/or export
IOAM data. The trigger applies to transit nodes, the decapsulating
node, and the encapsulating node:
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* An IOAM encapsulating node configured to incorporate the DEX
Option-Type encapsulates (possibly a subset of) the packets it
forwards with the DEX Option-Type, and MAY export and/or collect
the requested IOAM data immediately. Only IOAM encapsulating
nodes are allowed to add the DEX Option-Type to a packet. An IOAM
encapsulating node can generate probe packets that incorporate the
DEX Option-Type. These probe packets can be generated
periodically or on-demand (for example triggered by the management
plane). The specification of such probe packets is outside the
scope of this document.
* A transit node that processes a packet with the DEX Option-Type
MAY export and/or collect the requested IOAM data.
* An IOAM decapsulating node that processes a packet with the DEX
Option-Type MAY export and/or collect the requested IOAM data, and
MUST decapsulate the IOAM header.
As in [RFC9197], the DEX Option-Type can be incorporated into all or
a subset of the traffic that is forwarded by the encapsulating node,
as further discussed in Section 3.1.1 below. Moreover, IOAM nodes
respond to the DEX trigger by exporting and/or collecting IOAM data
either for all traversing packets that carry the DEX Option-Type, or
selectively only for a subset of these packets, as further discussed
in Section 3.1.2 below.
3.1.1. DEX Packet Selection
If an IOAM encapsulating node incorporates the DEX Option-Type into
all the traffic it forwards it may lead to an excessive amount of
exported data, which may overload the network and the receiving
entity. Therefore, an IOAM encapsulating node that supports the DEX
Option-Type MUST support the ability to incorporate the DEX Option-
Type selectively into a subset of the packets that are forwarded by
it.
Various methods of packet selection and sampling have been previously
defined, such as [RFC7014] and [RFC5475]. Similar techniques can be
applied by an IOAM encapsulating node to apply DEX to a subset of the
forwarded traffic.
The subset of traffic that is forwarded or transmitted with a DEX
Option-Type SHOULD NOT exceed 1/N of the interface capacity on any of
the IOAM encapsulating node's interfaces. It is noted that this
requirement applies to the total traffic that incorporates a DEX
Option-Type, including traffic that is forwarded by the IOAM
encapsulating node and probe packets that are generated by the IOAM
encapsulating node. In this context N is a parameter that can be
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configurable by network operators. If there is an upper bound, M, on
the number of IOAM transit nodes in any path in the network, then it
is RECOMMENDED to use an N such that N >> M (i.e., N is much greater
than M). The rationale is that a packet that includes a DEX Option-
Type may trigger an exported packet from each IOAM transit node along
the path for a total of M exported packets. Thus, if N >> M then the
number of exported packets is significantly lower than the number of
data packets forwarded by the IOAM encapsulating node. If there is
no prior knowledge about the network topology or size, it is
RECOMMENDED to use N>100.
3.1.2. Responding to the DEX Trigger
The DEX Option-Type specifies which IOAM-Data-Fields should be
exported and/or collected, as specified in Section 3.2. As mentioned
above, the data can be locally collected, and optionally can be
aggregated and exported to a receiving entity, either proactively or
on-demand. If IOAM data is exported, the format and encapsulation of
the packet that contains the exported data is not within the scope of
the current document. For example, the export format can be based on
[I-D.spiegel-ippm-ioam-rawexport].
An IOAM node that performs DEX-triggered exporting MUST support the
ability to limit the rate of the exported packets. The rate of
exported packets SHOULD be limited so that the number of exported
packets is significantly lower than the number of packets that are
forwarded by the device. The exported data rate SHOULD NOT exceed 1/
N of the interface capacity on any of the IOAM node's interfaces. It
is RECOMMENDED to use N>100. Depending on the IOAM node's
architecture considerations, the export rate may be limited to a
lower number in order to avoid loading the IOAM node. An IOAM node
MAY maintain a counter or a set of counters that count the events in
which the IOAM node receives a packet with the DEX Option-Type and
does not collect and/or export data due to the rate limits.
IOAM nodes SHOULD NOT be configured to export packets over a path or
a tunnel that is subject to IOAM direct exporting. Furthermore, IOAM
encapsulating nodes that can identify a packet as an IOAM exported
packet MUST NOT push a DEX Option-Type into such a packet. This
requirement is intended to prevent nested exporting and/or exporting
loops.
A transit or decapsulating IOAM node that receives an unknown IOAM-
Option-Type ignores it (as defined in [RFC9197]), and specifically
nodes that do not support the DEX Option-Type ignore it. Note that
as per [RFC9197] a decapsulating node removes the IOAM encapsulation
and all its IOAM-Option-Types. Specifically, this applies to the
case where one of these options is a (possibly unknown) DEX Option-
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Type. The ability to skip over a (possibly unknown) DEX Option-Type
in the parsing or in the decapsulation procedure is dependent on the
specific encapsulation, which is outside the scope of this document.
For example, when IOAM is encapsulated in IPv6
[I-D.ietf-ippm-ioam-ipv6-options] the DEX Option-Type is incorporated
either in a Hop-by-Hop options header or in a Destination options
header, and thus can be skipped using the length field in the options
header.
3.2. The DEX Option-Type Format
The format of the DEX Option-Type is depicted in Figure 2. The
length of the DEX Option-Type is at least 8 octets. The DEX Option-
Type MAY include one or more optional fields. The existence of the
optional fields is indicated by the corresponding flags in the
Extension-Flags field. Two optional fields are defined in this
document, the Flow ID and the Sequence Number fields. Every optional
field MUST be exactly 4 octets long. Thus, the Extension-Flags field
explicitly indicates the length of the DEX Option-Type. Defining a
new optional field requires an allocation of a corresponding flag in
the Extension-Flags field, as specified in Section 4.2.
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 | Flags |Extension-Flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IOAM-Trace-Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow ID (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: DEX Option-Type Format
Namespace-ID A 16-bit identifier of the IOAM namespace, as defined
in [RFC9197].
Flags An 8-bit field, comprised of 8 one-bit subfields.
Flags are allocated by IANA, as defined in
Section 4.2.
Extension-Flags An 8-bit field, comprised of 8 one-bit subfields.
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Extension-Flags are allocated by IANA, as defined in
Section 4.3. Every bit in the Extension-Flag field
that is set to 1 indicates the existence of a
corresponding optional 4-octet field. An IOAM node
that receives a DEX Option-Type with an unknown flag
set to 1 MUST ignore the corresponding optional
field.
IOAM-Trace-Type A 24-bit identifier which specifies which IOAM-Data-
Fields should be exported. The format of this field
is as defined in [RFC9197]. Specifically, the bit
that corresponds to the Checksum Complement IOAM-
Data-Field SHOULD be assigned to be zero by the IOAM
encapsulating node, and ignored by transit and
decapsulating nodes. The reason for this is that the
Checksum Complement is intended for in-flight packet
modifications and is not relevant for direct
exporting.
Reserved This field MUST be ignored by the receiver.
Optional fields The optional fields, if present, reside after the
Reserved field. The order of the optional fields is
according to the order of the respective bits,
starting from the most significant bit, that are
enabled in the Extension-Flags field. Each optional
field is 4 octets long.
Flow ID An optional 32-bit field representing the flow
identifier. If the actual Flow ID is shorter than 32
bits, it is zero padded in its most significant bits.
The field is set at the encapsulating node. The Flow
ID can be used to correlate the exported data of the
same flow from multiple nodes and from multiple
packets. Flow ID values are expected to be allocated
in a way that avoids collisions. For example, random
assignment of Flow ID values can be subject to
collisions, while centralized allocation can avoid
this problem. The specification of the Flow ID
allocation method is not within the scope of this
document.
Sequence Number An optional 32-bit sequence number starting from 0
and incremented by 1 for each packet from the same
flow at the encapsulating node that includes the DEX
option. The Sequence Number, when combined with the
Flow ID, provides a convenient approach to correlate
the exported data from the same user packet.
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4. IANA Considerations
4.1. IOAM Type
The "IOAM Option-Type Registry" was defined in Section 7.1 of
[RFC9197]. IANA is requested to allocate the following code point
from the "IOAM Option-Type Registry" as follows:
TBD-type IOAM Direct Export (DEX) Option-Type
If possible, IANA is requested to allocate code point 4 (TBD-type).
The "Description" for the new option should be "Direct exporting" and
the "Reference" should be the current document.
4.2. IOAM DEX Flags
IANA is requested to define an "IOAM DEX Flags" registry. This
registry includes 8 flag bits. Allocation is based on the "IETF
Review" procedure, as defined in [RFC8126].
New registration requests MUST use the following template:
Bit: Desired bit to be allocated in the 8 bit Flags field of the DEX
Option-Type.
Description: Brief description of the newly registered bit.
Reference: Reference to the document that defines the new bit.
4.3. IOAM DEX Extension-Flags
IANA is requested to define an "IOAM DEX Extension-Flags" registry.
This registry includes 8 flag bits. Bit 0 (the most significant bit)
and bit 1 in the registry are allocated by this document, and
described in Section 3.2. Allocation of the other bits should be
performed based on the "IETF Review" procedure, as defined in
[RFC8126].
Bit 0 "Flow ID [RFC XXXX] [RFC Editor: please replace with the RFC
number of the current document]"
Bit 1 "Sequence Number [RFC XXXX] [RFC Editor: please replace with
the RFC number of the current document]"
New registration requests MUST use the following template:
Bit: Desired bit to be allocated in the 8 bit Extension-Flags field
of the DEX Option-Type.
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Description: Brief description of the newly registered bit.
Reference: Reference to the document that defines the new bit.
5. Performance Considerations
The DEX Option-Type triggers IOAM data to be collected and/or
exported packets to be exported to a receiving entity (or entities).
In some cases this may impact the receiving entity's performance, or
the performance along the paths leading to it.
Therefore, the performance impact of these exported packets is
limited by taking two measures: at the encapsulating nodes, by
selective DEX encapsulation (Section 3.1.1), and at the transit
nodes, by limiting exporting rate (Section 3.1.2). These two
measures ensure that direct exporting is used at a rate that does not
significantly affect the network bandwidth, and does not overload the
receiving entity. Moreover, it is possible to load balance the
exported data among multiple receiving entities, although the
exporting method is not within the scope of this document.
It should be noted that in some networks DEX data may be exported
over an out-of-band network, in which a large volume of exported
traffic does not compromise user traffic. In this case an operator
may choose to disable the exporting rate limiting.
6. Security Considerations
The security considerations of IOAM in general are discussed in
[RFC9197]. Specifically, an attacker may try to use the
functionality that is defined in this document to attack the network.
An attacker may attempt to overload network devices by injecting
synthetic packets that include the DEX Option-Type. Similarly, an
on-path attacker may maliciously incorporate the DEX Option-Type into
transit packets, or maliciously remove it from packets in which it is
incorporated.
Forcing DEX, either in synthetic packets or in transit packets may
overload the IOAM nodes and/or the receiving entity (or entities).
Since this mechanism affects multiple devices along the network path,
it potentially amplifies the effect on the network bandwidth, on the
storage of the devices that collect the data, and on the receiving
entity's load.
The amplification effect of DEX may be worse in wide area networks in
which there are multiple IOAM domains. For example, if DEX is used
in IOAM domain 1 for exporting IOAM data to a receiving entity, then
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the exported packets of domain 1 can be forwarded through IOAM domain
2, in which they are subject to DEX. The exported packets of domain
2 may in turn be forwarded through another IOAM domain (or through
domain 1), and theoretically this recursive amplification may
continue infinitely.
In order to mitigate the attacks described above, the following
requirements (Section 3) have been defined:
* Selective DEX (Section 3.1.1) is applied by IOAM encapsulating
nodes in order to limit the potential impact of DEX attacks to a
small fraction of the traffic.
* Rate limiting of exported traffic (Section 3.1.2) is applied by
IOAM nodes in order to prevent overloading attacks and in order to
significantly limit the scale of amplification attacks.
* IOAM encapsulating nodes are required to avoid pushing the DEX
Option-Type into IOAM exported packets (Section 3.1.2), thus
preventing some of the amplification and export loop scenarios.
Although the exporting method is not within the scope of this
document, any exporting method MUST secure the exported data from the
IOAM node to the receiving entity, in order to protect the
confidentiality and guarantee the integrity of the exported data.
Specifically, an IOAM node that performs DEX exporting MUST send the
exported data to a pre-configured trusted receiving entity that is in
the same IOAM domain as the exporting IOAM node. Furthermore, an
IOAM node MUST gain explicit consent to export data to a receiving
entity before starting to send exported data.
An attacker may keep track of the information sent in DEX headers as
a means of reconnaissance. This form of recon can be mitigated to
some extent by careful allocation of the Flow ID and Sequence Number
space, in a way that does not compromise privacy aspects such as
customer identities.
The integrity of the DEX Option-Type can be protected through a
mechanism of the encapsulating protocol. While
[I-D.ietf-ippm-ioam-data-integrity] introduces an integrity
protection mechanism that protects the integrity of IOAM-Data-Fields,
the DEX Option-Type does not include IOAM-Data-Fields, and therefore
these integrity protection mechanisms are not applicable to the DEX
Option-Type. As discussed in the threat analysis of
[I-D.ietf-ippm-ioam-data-integrity], injection or modification of
IOAM-Option-Type headers are threats that are not addressed in IOAM.
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IOAM is assumed to be deployed in a restricted administrative domain,
thus limiting the scope of the threats above and their affect. This
is a fundamental assumption with respect to the security aspects of
IOAM, as further discussed in [RFC9197].
7. Acknowledgments
The authors thank Martin Duke, Tommy Pauly, Meral Shirazipour, Colin
Perkins, Stephen Farrell, Linda Dunbar, Justin Iurman, Greg Mirsky,
and other members of the IPPM working group for many helpful
comments.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi,
Ed., "Data Fields for In Situ Operations, Administration,
and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197,
May 2022, <https://www.rfc-editor.org/info/rfc9197>.
8.2. Informative References
[I-D.ietf-ippm-ioam-data-integrity]
Brockners, F., Bhandari, S., Mizrahi, T., and J. Iurman,
"Integrity of In-situ OAM Data Fields", Work in Progress,
Internet-Draft, draft-ietf-ippm-ioam-data-integrity-02, 5
July 2022, <https://www.ietf.org/archive/id/draft-ietf-
ippm-ioam-data-integrity-02.txt>.
[I-D.ietf-ippm-ioam-flags]
Mizrahi, T., Brockners, F., Bhandari, S., Gafni, B., and
M. Spiegel, "In-situ OAM Loopback and Active Flags", Work
in Progress, Internet-Draft, draft-ietf-ippm-ioam-flags-
10, 18 August 2022, <https://www.ietf.org/archive/id/
draft-ietf-ippm-ioam-flags-10.txt>.
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[I-D.ietf-ippm-ioam-ipv6-options]
Bhandari, S. and F. Brockners, "In-situ OAM IPv6 Options",
Work in Progress, Internet-Draft, draft-ietf-ippm-ioam-
ipv6-options-08, 16 June 2022,
<https://www.ietf.org/archive/id/draft-ietf-ippm-ioam-
ipv6-options-08.txt>.
[I-D.song-ippm-postcard-based-telemetry]
Song, H., Mirsky, G., Filsfils, C., Abdelsalam, A., Zhou,
T., Li, Z., Graf, T., Mishra, G., Shin, J., and K. Lee,
"Marking-based Direct Export for On-path Telemetry", Work
in Progress, Internet-Draft, draft-song-ippm-postcard-
based-telemetry-14, 7 September 2022,
<https://www.ietf.org/archive/id/draft-song-ippm-postcard-
based-telemetry-14.txt>.
[I-D.spiegel-ippm-ioam-rawexport]
Spiegel, M., Brockners, F., Bhandari, S., and R.
Sivakolundu, "In-situ OAM raw data export with IPFIX",
Work in Progress, Internet-Draft, draft-spiegel-ippm-ioam-
rawexport-06, 21 February 2022,
<https://www.ietf.org/archive/id/draft-spiegel-ippm-ioam-
rawexport-06.txt>.
[RFC5475] Zseby, T., Molina, M., Duffield, N., Niccolini, S., and F.
Raspall, "Sampling and Filtering Techniques for IP Packet
Selection", RFC 5475, DOI 10.17487/RFC5475, March 2009,
<https://www.rfc-editor.org/info/rfc5475>.
[RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
D., and S. Mansfield, "Guidelines for the Use of the "OAM"
Acronym in the IETF", BCP 161, RFC 6291,
DOI 10.17487/RFC6291, June 2011,
<https://www.rfc-editor.org/info/rfc6291>.
[RFC7014] D'Antonio, S., Zseby, T., Henke, C., and L. Peluso, "Flow
Selection Techniques", RFC 7014, DOI 10.17487/RFC7014,
September 2013, <https://www.rfc-editor.org/info/rfc7014>.
[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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Appendix A. Notes About the History of this Document
This document evolved from combining some of the concepts of PBT-I
from [I-D.song-ippm-postcard-based-telemetry] with immediate
exporting from early versions of [I-D.ietf-ippm-ioam-flags].
In order to help correlate and order the exported packets, it is
possible to include the Hop_Lim/Node_ID IOAM-Data-Field in exported
packets; if the IOAM-Trace-Type [RFC9197] has the Hop_Lim/Node_ID bit
set, then exported packets include the Hop_Lim/Node_ID IOAM-Data-
Field, which contains the TTL/Hop Limit value from a lower layer
protocol. An alternative approach was considered during the design
of this document, according to which a 1-octet Hop Count field would
be included in the DEX header (presumably by claiming some space from
the Flags field). The Hop Limit would starts from 0 at the
encapsulating node and be incremented by each IOAM transit node that
supports the DEX Option-Type. In this approach the Hop Count field
value would also be included in the exported packet.
Contributors
The Editors would like to recognize the contributions of the
following individuals to this document.
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Tianran Zhou
Huawei
156 Beiqing Rd.
Beijing 100095
China
Email: zhoutianran@huawei.com
Zhenbin Li
Huawei
156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Ramesh Sivakolundu
Cisco Systems, Inc.
170 West Tasman Dr.
SAN JOSE, CA 95134
U.S.A.
Email: sramesh@cisco.com
Authors' Addresses
Haoyu Song
Futurewei
2330 Central Expressway
Santa Clara, 95050
United States of America
Email: haoyu.song@futurewei.com
Barak Gafni
Nvidia
350 Oakmead Parkway, Suite 100
Sunnyvale, CA
Email: gbarak@nvidia.com
Frank Brockners
Cisco Systems, Inc.
Hansaallee 249, 3rd Floor
40549 DUESSELDORF
Germany
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Email: fbrockne@cisco.com
Shwetha Bhandari
Thoughtspot
3rd Floor, Indiqube Orion, 24th Main Rd, Garden Layout, HSR Layout
Bangalore, KARNATAKA 560 102
India
Email: shwetha.bhandari@thoughtspot.com
Tal Mizrahi
Huawei
8-2 Matam
Haifa 3190501
Israel
Email: tal.mizrahi.phd@gmail.com
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