Path Tracing in SRv6 networks
draft-filsfils-spring-path-tracing-03
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Clarence Filsfils , Ahmed Abdelsalam , Pablo Camarillo , Mark Yufit , Thomas Graf , Yuanchao Su , Satoru Matsushima , Mike Valentine , Amit Dhamija | ||
| Last updated | 2023-02-13 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
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| Send notices to | (None) |
draft-filsfils-spring-path-tracing-03
SPRING C. Filsfils
Internet-Draft A. Abdelsalam, Ed.
Intended status: Standards Track P. Camarillo, Ed.
Expires: 17 August 2023 Cisco Systems, Inc.
M. Yufit
Broadcom
T. Graf
Swisscom
Y. Su
Alibaba, Inc
S. Matsushima
SoftBank
M. Valentine
Goldman Sachs
A. Dhamija
Rakuten
13 February 2023
Path Tracing in SRv6 networks
draft-filsfils-spring-path-tracing-03
Abstract
Path Tracing provides a record of the packet path as a sequence of
interface ids. In addition, it provides a record of end-to-end
delay, per-hop delay, and load on each egress interface along the
packet delivery path.
Path Tracing allows to trace 14 hops with only a 40-bytes IPv6 Hop-
by-Hop extension header.
Path Tracing supports fine grained timestamp. It has been designed
for linerate hardware implementation in the base pipeline.
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/.
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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 17 August 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Midpoint Compressed Data . . . . . . . . . . . . . . . . . . 4
4. Timestamp requirements . . . . . . . . . . . . . . . . . . . 5
4.1. Timestamp format . . . . . . . . . . . . . . . . . . . . 5
4.2. Time synchronization . . . . . . . . . . . . . . . . . . 5
5. PT Probing Instance . . . . . . . . . . . . . . . . . . . . . 6
6. PT Source Node Dataplane Behavior . . . . . . . . . . . . . . 6
7. PT Midpoint Node Dataplane Behavior . . . . . . . . . . . . . 7
8. PT Sink Node Dataplane Behavior . . . . . . . . . . . . . . . 8
9. PT Headers . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. IPv6 Hop-by-Hop Path Tracing Option . . . . . . . . . . . 9
9.2. SRH Path Tracing TLV . . . . . . . . . . . . . . . . . . 10
10. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 11
11. Implementation Status . . . . . . . . . . . . . . . . . . . . 11
12. Security Considerations . . . . . . . . . . . . . . . . . . . 12
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
13.1. Destination Options and Hop-by-Hop Options . . . . . . . 13
13.2. Segment Routing Header TLV . . . . . . . . . . . . . . . 13
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
15.1. Normative References . . . . . . . . . . . . . . . . . . 14
15.2. Informative References . . . . . . . . . . . . . . . . . 14
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
Path Tracing provides a record of the packet path as a sequence of
interface ids. In addition, it provides a record of end-to-end
delay, per-hop delay, and load on each egress interface along the
packet delivery path.
Path Tracing allows to trace 14 hops with only a 40 bytes IPv6 Hop-
by-Hop header. The overhead is lower than [INT], [RFC9197],
[I-D.song-opsawg-ifit-framework], and [I-D.kumar-ippm-ifa].
Path Tracing supports fine-grained timestamps. It has been designed
for linerate hardware implementation in the base pipeline.
Path Tracing is applicable to both SR-MPLS [RFC8660], as well as SRv6
[RFC8986]. This document defines the Path Tracing specification for
the SRv6 dataplane. The SR-MPLS dataplane will be detailed in a
separate document.
The specification proposed in this document has been implemented
successfully in different interoperable hardware platforms at
linerate (Section 11).
2. Terminology
The following terms used within this document are defined in
[RFC8402], [RFC8754] and [RFC8986]: Segment Routing (SR), SR Domain,
Segment ID (SID), SRv6, SRv6 SID, SR Policy, Segment Routing Header
(SRH), SR source node, transit node, SR Endpoint, SA, DA.
The following terms are used in this document as defined below:
PT: Path Tracing
MCD: Midpoint Compressed Data (MCD). Information that every transit
router adds to the packet for PT purposes. Defined in Section 3 of
this document.
HbH-PT: IPv6 Hop-by-Hop [RFC8200] Path Tracing Option used for PT.
It contains a stack of MCDs. It is defined in Section 9.1 of this
document
SRH PT-TLV: SRH TLV defined in Section 9.2 of this document.
PT Source: A Source node that starts a PT Probing Instance (defined
in Section 5) and generates PT probes.
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PT Midpoint: A transit node that performs plain IPv6 forwarding (or
SR Endpoint processing) and in addition records PT information in the
HbH-PT.
PT Sink: A node that receives PT probes sent from the SRC containing
the information recorded by every PT Midpoint along the path, and
forwards them to a regional collector after recording its PT
information.
RC: Regional collector that receives PT probes, parses, and stores
them in TimeSeries Database. It uses the information in the HBH-PT
and the SRH PT-TLV to construct the packet delivery path as well as
the timestamp at each node.
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Midpoint Compressed Data
Every PT Midpoint along the packet delivery path -from Source to
Sink- records its PT information into the HbH-PT header. This
information is known as Midpoint Compressed Data (MCD). It contains
the following information:
* MCD.OIF (Outgoing Interface ID): An 8-bit or 12-bit interface ID
associated with the egress physical interface of the router
- The interface ID is assigned by an operator. The Interface IDs
are not globally unique across the entire network. Indeed the
same Interface ID may be repeated multiple times in the network
as long as the end-to-end path can be deterministically
inferred based on the chain of Interface IDs.
- The programming of the Interface ID in the device may be done
by CLI/NETCONF or any other means, and it is out of the scope
of this document.
- The usage of an 8-bit or 12-bit Interface ID is an operator
choice, but the Interface ID size MUST be consistent across the
entire network.
- In case of Link Aggregation Groups (LAG/bundle) [LAG], each one
of the members is configured with a different interface ID.
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* MCD.OIL (Outgoing Interface Load): A 4-bit representation of the
egress interface load (i.e., current throughout relative to the
interface bandwidth).
- The load is represented using a 4-bit value in logarithmic
scale. This allows more granular information as the load is
higher.
* MCD.TTS (Truncated Timestamp): An 8-bit timestamp encoding the
time at which the packet egress the router.
- Each egress interface in the device is configured with a TTS
template.
- The TTS template defines the position of 8-bits to be selected
from the egress timestamp. Section 4 of this document
discusses the timestamp format used in path tracing.
- A Path Tracing Midpoint implementation MAY support one or more
TTS templates. Each TTS template provides a different time
precision.
- An operator configures an egress interface with a single TTS
template. The choice of the TTS template for a given interface
is based on the type of the link connected to that interface.
For example, an interface connected to DC link will have a
different TTS Template from an interface connected to
intercontinental or WAN link, as they have different precision
requirements.
4. Timestamp requirements
4.1. Timestamp format
Path Tracing uses a 64-bit timestamp format. [RFC8877] recommends
two 64-bit timestamp formats: 64-bit Truncated PTP timestamp format
and NTP 64-bit timestamp format. Path Tracing can work with both
formats indifferently.
4.2. Time synchronization
All routers across the network MUST have time-synchronization. PTP
[IEEE1588] and NTP [RFC5905] are example protocols that can be used
for time-synchronization.
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5. PT Probing Instance
The controller configures a PT Probing Instance at the source node.
A PT Probing Instance is configured with the following parameters:
* SA: the source address of the PT probe. Typically, it is the
loopback address of the PT SRC.
* Session ID: A 16-bit value.
* Probe-rate: Number of probes per second to generate as part of
this PT Probing Instance. The probe-rate is the aggregate of the
probes generated across all the sweeping ranges.
* SRv6 SID List: The SRv6 SID list associated with the packet. The
last SID is the Sink node.
* DSCP value
* Hop-limit Value
* IPv6 Flow-Label sweeping range:
- If set, different Flow-Label values must be used in the probe
packets. It may be specified as a range of specific Flow-Label
values to enumerate, or it may be specified as the number of
different random Flow-Label values to use in a round-robin.
* HbH-PT size
* MTU sweeping range:
- If set, payload must be included at the end of the packet to
test different packet sizes.
6. PT Source Node Dataplane Behavior
For each configured PT Probing Instance, according to the probe-rate,
the PT SRC generates a PT probe packet as follows:
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S01. Generate a new IPv6 packet
S02. Set the IPv6 SA as per PT Probing Instance configuration
S03. Set the IPv6 DA to the first SID from the SRv6 SID List
S04. Set the IPv6 Next Header field to zero (HbH)
S05. Set the DSCP and Flow Label values as per
PT Probing Instance configuration
S06. Append an IPv6 Hop-by-Hop header with the Hop-by-Hop
Path Tracing option (HbH-PT)
S07. Set all bits of the HbH-PT MCD Stack to zero
S08. Append an SRH
S09. Set the SRH Next Header field to 59 (IPv6 No Next Header)
S10. Write the SID list in the SRH
S11. Append the SRH PT-TLV
S12. Add padding bytes after the SRH to reach the desired
packet size as per the MTU sweeping range configuration
S13. Set the session ID field of the SRH PT-TLV as per
PT Probing Instance configuration
S14. Set the Sequence Number field of SRH PT-TLV and
increase local counter
S15. Perform an IPv6 FIB lookup to determine the Outgoing
Interface (IFACE-OUT) on which packet will be forwarded
S16. Record Transmit 64-bit timestamp (SRC.T64) in the T64 field
of the SRH PT-TLV
S17. Record IFACE-OUT ID (SRC.OIF) in the IF_ID field
of the SRH PT-TLV
S18. Record IFACE-OUT Load (SRC.OIL) in the IF_LD field
of the SRH PT-TLV
S19. Forward the packet via IFACE-OUT
Notes:
* The pseudocode describes local processing at a node. An
implementation of the pseudocode is compliant as long as the
externally observable wire protocol is as described in the
pseudocode.
7. PT Midpoint Node Dataplane Behavior
When a midpoint node receives an IPv6 packet that contains an IPv6
HbH-PT option, the node processes the HbH-PT as follows:
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S01. When processing HbH-PT option {
S02. Compute the MCD information as per Section 3
S03. HbH-PT.MCD_Stack[MCD_Size:HbH-PT.OPT_Data_Len-1] =
HbH-PT.MCD_Stack[0:HbH-PT.OPT_Data_Len-(MCD_Size+1)]
//Shift HbH-PT MCD Stack to the right by MCD_Size bytes
S04. HbH-PT.MCD_Stack[0:MCD_Size-1] = MCD[0:MCD_Size-1]
//Push the MCD at the beginning of the Stack
S05. }
Notes:
* The PT Midpoint behavior MUST be implemented in the normal
pipeline to experience the regular datapath (i.e., linerate with
full PPS and full BW). Offloading the processing of this option
to either the slow-path or a co-processors is not acceptable and
yields invalid results.
8. PT Sink Node Dataplane Behavior
We define a new SRv6 Endpoint Behavior called "Endpoint Behavior
bound to an SRv6 Policy with Timestamp, Encapsulation and Forward"
("End.B6.TEF" for short).
It is a Binding SID instantiated, at Sink nodes, that encapsulates
the packet with a new IPv6 header, an SRH that contains the SID list
associated to End.B6.TEF SID and an SRH PT-TLV that is used to carry
Path Tracing information of Sink node.
When N receives a packet whose IPv6 DA is S and S is a local
End.B6.TEF SID, N does the following:
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S01. Record Rx 64-bit timestamp (SNK.T64)
S02. Record incoming interface ID (SNK.IIF)
S03. Record incoming interface Load (SNK.IIL)
S04. Push a new IPv6 header
S05. Set the IPv6 SA to the Sink node loopback
S06. Set the IPv6 DA to the first SID in the SRv6 SID List
S07. Set the IPv6 Next Header field to 43 (SRH)
S08. Append an SRH
S09. Set the SRH Next Header field to 41 (IPv6)
S10. Write the SID list in the SRH
S11. Append the SRH PT-TLV
S12. Set the session ID field of the SRH PT-TLV to zero
S13. Set the Sequence Number field of the SRH PT-TLV to zero
S14. Write SNK.T64 in the T64 field of the SRH PT-TLV
S15. Write SNK.IIF in the IF_ID field of the SRH PT-TLV
S16. Write SNK.IIL in the IF_LD field of the SRH PT-TLV
S17. Submit the packet to the egress IPv6 FIB lookup for
transmission to the new destination
Notes:
* The pseudocode describes local processing at a node. An
implementation of the pseudocode is compliant as long as the
externally observable wire protocol is as described in the
pseudocode.
9. PT Headers
9.1. IPv6 Hop-by-Hop Path Tracing Option
This document defines a new IPv6 Path Tracing option to be carried in
the IPv6 Hop-by-Hop Header. The option has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ MCD Stack ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: IPv6 Hop-by-Hop Path Tracing Option Format
Where:
* Option Type: TBA1-1
- The 3 high-order bits of the option must be set to 001
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o 00: Skip HbH for nodes that don't support the HbH-PT Option
Type
o 1: update HbH-PT for nodes that support the HbH-PT Option
Type
- Opt Data Len: the length of the MCD stack in bytes.
Note: The IPv6 Path Tracing Option has a variable length. It is
RECOMMENDED that implementations support a 38-octet HbH-PT Option.
The operator, upon configuring the Source node behavior, MUST select
an option length that is supported by all the routers in the network.
9.2. SRH Path Tracing TLV
We define a new SRH TLV, called "Path Tracing TLV" ("SRH PT-TLV" for
short). It has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | IF_ID | IF_LD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ T64 +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session ID | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SRH Path Tracing TLV Format
Where:
* Type: TBA2-1
* Length: 14
* IF_ID: 12-bit Interface ID
* IF_LD: 4-bit Interface Load
* T64: 64-bit Timestamp
* Session ID: Session identifier set by SRC node generating the
probes. Used to co-relate probes of the same session. Value of
zero means unset.
* Sequence Number: the sequence number of the probe set by SRC node
generating the probes. Value of zero means unset.
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Note: The SRH PT-TLV is generated by both the PT SRC and the PT SNK.
When used at the PT SNK node, the Session ID, and Sequence Number
fields MUST be set to zero.
10. Benefits
* Low overhead:
- A 40Byte Hop-By-Hop header allows for 14 hops path
measurements: 1 at the PT SRC, 12 at PT Midpoint routers and 1
at the PT SNK
- PT has the lowest MTU overhead compared to alternative
solutions such as [INT], [RFC9197],
[I-D.song-opsawg-ifit-framework], and [I-D.kumar-ippm-ifa].
* Linerate and HW friendliness:
- Implemented at linerate in current hardware, using the regular
forwarding pipeline. No offloading to co-processors or slow-
path whose databases might defer from forwarding pipeline.
- Leverages mature hardware capabilities (basic shift operation);
no packet resizing at every node along the path
- High number of diverse linerate interoperable hardware
Implementations (see Section 11)
* Scalable Fine-grained Timestamp:
- 64bit at PT SRC and PT SNK
- 8bit at PT Midpoint leveraging flexible per-outgoing-link
template allowing diverse link types in the same measurement
(e.g., DC, metro, WAN)
* Scalable Load measurement
11. Implementation Status
Editorial note: Please remove this section prior publication.
The following routing platforms have participated in an interop
testing:
* Cisco 8802 (based Cisco Silicon One Q200)
* Cisco ASR9904 with Lightspeed linecard
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* Cisco NCS5508 (based on Broadcom Jericho2 platform)
* Cisco Nexus N3K-C3464C (based on Barefoot Tofino)
* Marvell Prestera Falcon
* Keysight IxNetwork
The following open-source software networking stacks have also
participated in the interop:
* FD.io VPP
* Linux Kernel
The following opensource applications also have extensions to support
Path Tracing:
* Wireshark
* Tcpdump
* P4 implementation for software switch
12. Security Considerations
The security considerations for Segment Routing are discussed in
[RFC8402]. Section 5 of [RFC8754] describes the SR Deployment Model
and the requirements for securing the SR Domain. The security
considerations of [RFC8754] also cover topics such as attack vectors
and their mitigation mechanisms that also apply to the behaviors
introduced in this document. Together, they describe the required
security mechanisms that allow establishment of an SR domain of
trust. Having such a well-defined trust boundary is necessary in
order to operate SRv6-based services for internal traffic while
preventing any external traffic from accessing or exploiting the
SRv6-based services.
This document defines the Path Tracing architecture, which is
deployed on a secured SRv6-domain. As such, all the security
considerations defined in [RFC8754], [RFC8402], and [RFC8986] are
applicable.
In addition, any border router in an SR Domain network where Path
Tracing is enabled, MUST support the configuration of the following
ACLs:
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* If there is a packet coming from an external interface destined
towards an internal interface that contains an IPv6 Hop-by-Hop
header with a Path Tracing option, then such packet is silently
dropped.
* If there is a packet coming from an internal interface destined
towards an external interface that contains an IPv6 Hop-by-Hop
header with a Path Tracing option, then such packet is silently
dropped.
These ACLs SHOULD be enabled by default. An operator MAY disable
them individually based on local configuration.
The processing of IPv6 Hop-by-Hop headers could sometimes be used as
an attack vector to overload the CPU of the router. As defined in
Section 7 of this document, the HBH-PT option MUST be processed in
the router's fast path. Therefore, there is no impact on the
router's CPU.
13. IANA Considerations
This document has two actions for IANA:
13.1. Destination Options and Hop-by-Hop Options
This I-D requests IANA to allocate a new entry in the "Destination
Options and Hop-by-Hop Options" sub-registry under the top-level
registry "Internet Protocol Version 6 (IPv6) Parameters":
Value Description Reference
----------------------------------------------
TBA1-1 Path Tracing [This.ID]
Note: The 3 high-order bits must be 001.
13.2. Segment Routing Header TLV
This I-D requests IANA to allocate a new entry in the "Segment
Routing Header TLVs" sub-registry under the top-level registry
"Internet Protocol Version 6 (IPv6) Parameters":
Value Description Reference
----------------------------------------------
TBA2-1 Path Tracing TLV [This.ID]
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14. Acknowledgements
The authors of this document would like to thank the team that has
collaborated on the design and implementation of the Path Tracing
framework at Cisco, Broadcom, Marvel, Keysight, Swisscom, Alibaba,
Softbank, University of Rome "Tor Vergata", and ETH Zurich. In
particular: Eyal Dagan, Guy Caspary, Elad Naor, Aviran Kadosh, Eli
Stein, Oren Yabo, Aviad Behar, Anand Sridharan, Anju Dey, John
Bettink, Kamran Raza, Asif Islam, Yue Gao, Jakub Horn, Sam
Kheirallah, Shelly Cadora, Kris Michielsen, Francois Clad, Stefano
Salsano, Andrea Mayer, Paolo Lungaroni, Giulio Sidoretti, Leonardo
Rodoni, Marco Tollini, Yuanwen Sun, Anirban Bhattacharya, Ajay
Ramamurthy.
15. References
15.1. 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>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/rfc/rfc8200>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/rfc/rfc8754>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/rfc/rfc8986>.
15.2. Informative References
[I-D.kumar-ippm-ifa]
Kumar, J., Anubolu, S., Lemon, J., Manur, R., Holbrook,
H., Ghanwani, A., Cai, D., Ou, H., Li, Y., and X. Wang,
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"Inband Flow Analyzer", Work in Progress, Internet-Draft,
draft-kumar-ippm-ifa-05, 12 August 2022,
<https://datatracker.ietf.org/doc/html/draft-kumar-ippm-
ifa-05>.
[I-D.song-opsawg-ifit-framework]
Song, H., Qin, F., Chen, H., Jin, J., and J. Shin, "A
Framework for In-situ Flow Information Telemetry", Work in
Progress, Internet-Draft, draft-song-opsawg-ifit-
framework-19, 24 October 2022,
<https://datatracker.ietf.org/doc/html/draft-song-opsawg-
ifit-framework-19>.
[IEEE1588] "IEEE Standard for a Precision Clock Synchronization
Protocol for Networked Measurement and Control Systems",
IEEE , 2008,
<https://doi.org/10.1109/IEEESTD.2008.4579760>.
[INT] "In-band Network Telemetry (INT) Dataplane Specification",
2020, <https://github.com/p4lang/p4-
applications/blob/master/docs/INT_v2_1.pdf>.
[LAG] "802.1AX-2014 - IEEE Standard for Local and metropolitan
area networks -- Link Aggregation", IEEE , 2014,
<https://doi.org/10.1109/IEEESTD.2014.7055197>.
[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/rfc/rfc5905>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/rfc/rfc8402>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/rfc/rfc8660>.
[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/rfc/rfc8877>.
Filsfils, et al. Expires 17 August 2023 [Page 15]
Internet-Draft Path Tracing February 2023
[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/rfc/rfc9197>.
Contributors
Jisu Bhattacharya
Cisco Systems, Inc.
United States of America
Email: jisu@cisco.com
Rakesh Gandhi
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Serguei Bezverkhi
Cisco Systems, Inc.
Italy
Email: sbezverk@cisco.com
Sonia Ben Ayed
Cisco Systems, Inc.
France
Email: sbenayed@cisco.com
Israel Meilik
Broadcom
Israel
Email: israel.meilik@broadcom.com
Shay Zadok
Broadcom
Israel
Email: shay.zadok@broadcom.com
Weiqiang Cheng
China Mobile
China
Email: chengweiqiang@chinamobile.com
Filsfils, et al. Expires 17 August 2023 [Page 16]
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Authors' Addresses
Clarence Filsfils
Cisco Systems, Inc.
Belgium
Email: cf@cisco.com
Ahmed Abdelsalam (editor)
Cisco Systems, Inc.
Italy
Email: ahabdels@cisco.com
Pablo Camarillo Garvia (editor)
Cisco Systems, Inc.
Spain
Email: pcamaril@cisco.com
Mark Yufit
Broadcom
Israel
Email: mark.yufit@broadcom.com
Thomas Graf
Swisscom
Switzerland
Email: thomas.graf@swisscom.com
Yuanchao Su
Alibaba, Inc
China
Email: yitai.syc@alibaba-inc.com
Satoru Matsushima
SoftBank
Japan
Email: satoru.matsushima@g.softbank.co.jp
Mike Valentine
Goldman Sachs
United States of America
Email: michael.j.valentine@gs.com
Filsfils, et al. Expires 17 August 2023 [Page 17]
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Amit Dhamija
Rakuten
India
Email: amit.dhamija@rakuten.com
Filsfils, et al. Expires 17 August 2023 [Page 18]