IPv6 Hop-by-Hop Options for DetNet
draft-pthubert-detnet-ipv6-hbh-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Pascal Thubert | ||
| Last updated | 2021-06-08 | ||
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draft-pthubert-detnet-ipv6-hbh-00
DetNet P. Thubert, Ed.
Internet-Draft Cisco Systems
Intended status: Standards Track 8 June 2021
Expires: 10 December 2021
IPv6 Hop-by-Hop Options for DetNet
draft-pthubert-detnet-ipv6-hbh-00
Abstract
RFC 8938, the Deterministic Networking Data Plane Framework relies on
the 6-tuple to identify an IPv6 flow. But the full DetNet operations
require also the capabilities to signal meta-information such as a
sequence within that flow, and to transport different types of
packets along the same path with the same treatment, e.g.,
Operations, Administration, and Maintenance packets and/or multiple
flows with fate and resource sharing. This document introduces new
Hop-by-Hop header option that can signal that information to the
intermediate relays.
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 10 December 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of 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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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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. The DetNet Options . . . . . . . . . . . . . . . . . . . . . 4
3.1. Sequencing Option . . . . . . . . . . . . . . . . . . . . 4
3.2. RPL Packet Information . . . . . . . . . . . . . . . . . 6
3.3. DetNet Local Path Option . . . . . . . . . . . . . . . . 7
3.4. DetNet Global Path Option . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Section 2 of the Deterministic Networking Problem Statement
[DetNet-PS] introduces the concept of Deterministic Networking
(DetNet) to the IETF. DetNet extends the reach of lower layer
technologies such as Time-Sensitive Networking (TSN) [IEEE 802.1 TSN]
and Timeslotted Channel Hopping (TSCH) [IEEE Std. 802.15.4] over IPv6
and MPLS [RFC8938].
The "Deterministic Networking Architecture" [DetNet-ARCHI] details
the contribution of layer-3 protocols, and defines three planes: the
Application (User) Plane, the Controller Plane, and the Network
Plane. [DetNet-ARCHI] places an emphasis on the centralized model
whereby a controller instantiates per-flow state in the routers to
perform adequate forwading operations so as to provide end-to-end
reliability and bounded latency guarantees.
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The "6TiSCH Architecture" [6TiSCH-ARCHI] leverages RPL, the "Routing
Protocol for Low Power and Lossy Networks" [RFC6550] and introduces
concept of a Track as a highly redundant RPL Destination Oriented
Directed Acyclic Graph (DODAG) rooted at the Track Ingress node, that
can be installed using so-called projected routes [RPL-PDAO]. In
that case, the TrackId is an index from a namespace associated to one
IPv6 address of the Track Ingress node, and the Track that an IPv6
packet follows is signaled by the combination of the source address
(of the Track Ingress node), and the TrackID placed in a RPL Option
[RFC6553] located in an IPv6 Hop-by-Hop (HbH) Options Header [IPv6]
in the IPv6 packet.
The "Reliable and Available Wireless (RAW) Architecture/Framework"
[RAW-ARCHI], extends the DetNet Network Plane to accomodate one or
multiple hops of homogeneous or heterogeneous wireless technologies,
e.g. a Wi-Fi6 Mesh or parallel radio access links combining Wi-Fi and
5G. The RAW Architecture reuses the concept of Track and introduces
a new dataplane component, the Path Selection Engine (PSE), to
dynamically select a subpath and maintain the required quality of
service within a Track in the face of the rapid evolution of the
medium properties.
With [IPv6], the behavior of a router upon an IPv6 packet with a HbH
Options Header has evolved, making the examination of the header by
routers along the path optional, as opposed to previously mandatory.
Additionally, the Option Type for any option in a HbH Options Header
encodes in the leftmost bits whether a router that inspects the
header should drop the packet or ignore the option when encountering
an unknown option. Combined, these capabilities enable a larger use
of the header beyond the boundaries of a limited domain, as
examplified by the change of behavior of the RPL data plane, that was
changed to allow a packet with a RPL option to escape the RPL domain
in the larger Internet [RFC9008].
"IPv6 Hop-by-Hop Options Processing Procedures" [HbH-PROCESS] further
specifies the procedures for how IPv6 Hop-by-Hop options are
processed to make their processing even more practical and increase
their use in the Internet. In that context, it makes sense to
consider the Hop-by-Hop Options to transport the information that is
relevant to DetNet, making it independant of the transport and
placing it early in the header chain.
The "Deterministic Networking Data Plane Framework" [RFC8938]relies
on the 6-tuple to identify an IPv6 flow. But the full DetNet
*operations require also the capabilities to signal meta-information
such as a sequence within that flow, and to transport different types
of packets along the same path with the same treatment. For
instance, it is required that Operations, Administration, and
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Maintenance (OAM) [RFC6291] packets and/or multiple flows share the
same fate and resource sharing over the same Track or the same
Traffic Engineered (TE) [RFC3272] DetNet path.
This document introduces new Hop-by-Hop options that can signal path
and sequencing information to the intermediate relays early in the
packet and independantly of the transport layer.
2. Terminology
Timestamp semantics and timestamp formats used in this document are
defined in "Guidelines for Defining Packet Timestamps" [RFC8877].
The Deterministic Networking terms used in this document are defined
in the "Deterministic Networking Architecture" [DetNet-ARCHI].
The terms Track and TrackID are defined in the "6TiSCH Architecture"
[6TiSCH-ARCHI].
3. The DetNet Options
This document defines a number of IPv6 options to be placed in a HbH
Options Header; the format of these options follow the generic
definition in section 4.2 of [IPv6].
3.1. Sequencing Option
A typical packet sequence can be expressed uniquely as a wrapping
counter, represented as an unsigned integer in the option. In that
case, the size of the representation MUST be large enough to cover
several times the upper bound on out-of-order packet delivery in
terms of number of packets.
This specification also allows to use a time stamp for the packet
sequencing following the recommendations in [RFC8877]. This can be
accomplished by utilizing the Precision Time Protocol (PTP) format
defined in IEEE Std. 1588 [IEEE Std. 1588] or Network Time Protocol
(NTP) [RFC5905] formats. In that case, the timestamp resolution at
the node that builds the option MUST be fine enough to ensure that
two consecutive packets are never stamped with the same value.
This specification also allows for an hybrid model with a coarse
grained packet sequence within a coarse grained time stamp. In that
case, both a time stamp option and a wrapping counter options are
found, and the counter is used to compare packets with the same time
stamp.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Seq. Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Sequencing Information (variable Size) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Sequencing Option Format
Sequencing Option fields:
Option Type: 8-bit identifier of the type of option. Value TBD by
IANA.
Sequence Type: 8-bit identifier of the type of sequencing
information. Value to be confirmed by IANA.
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+=======+============+===============+===========================+
| Seq. | Sequencing | Commin Name | Sequencing |
| Type | Type | | Information Format |
| Value | | | |
+=======+============+===============+===========================+
| 1 | Wrapping | Basic | 32-bit unsigned |
| | Counter | Sequence | integer |
| | | Counter | |
+-------+============+---------------+---------------------------+
| 2 | Wrapping | Zero-avoiding | 32-bit unsigned |
| | Counter | Sequence | integer, wraps to 1 |
| | | Counter | |
+-------+============+---------------+---------------------------+
| 3 | Wrapping | RPL Sequence | 8-bit RPL sequence, |
| | Counter | Counter | see section 7. of |
| | | | [RFC6550] |
+-------+============+---------------+---------------------------+
| 11 | Time Stamp | Fractional | NTP 64-bit Timestamp |
| | | NTP | Format, see section |
| | | | 4.2.1. of [RFC8877] |
+-------+============+---------------+---------------------------+
| 12 | Time Stamp | Short NTP | NTP 32-bit Timestamp |
| | | | Format, see section |
| | | | 4.2.2. of [RFC8877] |
+-------+============+---------------+---------------------------+
| 13 | Time Stamp | PTP | PTP 80-bit Timestamp |
| | | | Format, see [IEEE |
| | | | Std. 1588] |
+-------+============+---------------+---------------------------+
| 13 | Time Stamp | Short PTP | PTP 64-bit Truncated |
| | | | Timestamp Format, |
| | | | see section 4.3. of |
| | | | [RFC8877] |
+-------+============+---------------+---------------------------+
Table 1: Sequence Type values (suggested)
3.2. RPL Packet Information
6TiSCH [6TiSCH-ARCHI] and RAW [RAW-ARCHI] signal a Track using a RPL
Option [RFC6553] with a RPLInstanceID used as TrackID. This
specification reuses the RPL option as a method to signal a DetNet
path. In that case, the Projected-Route 'P' flag [RPL-PDAO] MUST be
set to 1, and the O, R, F flags, as well as the Sender Rank field,
MUST be set to 0 by the originator, forwarded as-is, and ignored on
reception.
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3.3. DetNet Local Path Option
This specification also allows for an hybrid model with a coarse
grained packet sequence within a coarse grained time stamp. In that
case, both a time stamp option and a wrapping counter options are
found, and the counter is used to compare packets with the same time
stamp.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Local Path ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: DetNet Local Path Option Format
Sequencing Option fields:
Option Type: 8-bit identifier of the type of option. Value TBD by
IANA.
Opt Data Len: 8-bit length of the option data, set to 2.
Local Path ID: 16-bit identifier of the DetNet Path, taken from a
local namespace associated with the IPv6 source address of the
packet.
3.4. DetNet Global Path Option
This specification also allows for an hybrid model with a coarse
grained packet sequence within a coarse grained time stamp. In that
case, both a time stamp option and a wrapping counter options are
found, and the counter is used to compare packets with the same time
stamp.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Origin Autonomous System |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global Path ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: DetNet Glocal Path Option Format
Sequencing Option fields:
Option Type: 8-bit identifier of the type of option. Value TBD by
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IANA.
Opt Data Len: 8-bit length of the option data, set to 6.
Origin Autonomous System: 16-bit identifier of the Autonomous
Systems (AS) that originates the path.
Global Path ID: 32-bit identifier of the DetNet Path, taken from a
local namespace associated with the origin AS of the DetNet path.
The value of 0 signals a DetNet path that is constrained within
the local AS or the local administrative DetNet domain.
4. Security Considerations
5. IANA Considerations
This document has no IANA actions.
6. Acknowledgments
TBD
7. References
7.1. Normative References
[IPv6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[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>.
[HbH-PROCESS]
Hinden, R. M. and G. Fairhurst, "IPv6 Hop-by-Hop Options
Processing Procedures", Work in Progress, Internet-Draft,
draft-hinden-6man-hbh-processing-00, 3 December 2020,
<https://tools.ietf.org/html/draft-hinden-6man-hbh-
processing-00>.
[DetNet-ARCHI]
Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
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7.2. Informative References
[RPL-PDAO] Thubert, P., Jadhav, R. A., and M. Gillmore, "Root
initiated routing state in RPL", Work in Progress,
Internet-Draft, draft-ietf-roll-dao-projection-16, 15
January 2021, <https://tools.ietf.org/html/draft-ietf-
roll-dao-projection-16>.
[RAW-ARCHI]
Thubert, P., Papadopoulos, G. Z., and R. Buddenberg,
"Reliable and Available Wireless Architecture/Framework",
Work in Progress, Internet-Draft, draft-pthubert-raw-
architecture-05, 15 November 2020,
<https://tools.ietf.org/html/draft-pthubert-raw-
architecture-05>.
[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>.
[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>.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553,
DOI 10.17487/RFC6553, March 2012,
<https://www.rfc-editor.org/info/rfc6553>.
[DetNet-PS]
Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", RFC 8557, DOI 10.17487/RFC8557, May 2019,
<https://www.rfc-editor.org/info/rfc8557>.
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[RFC9008] Robles, M.I., Richardson, M., and P. Thubert, "Using RPI
Option Type, Routing Header for Source Routes, and IPv6-
in-IPv6 Encapsulation in the RPL Data Plane", RFC 9008,
DOI 10.17487/RFC9008, April 2021,
<https://www.rfc-editor.org/info/rfc9008>.
[6TiSCH-ARCHI]
Thubert, P., Ed., "An Architecture for IPv6 over the Time-
Slotted Channel Hopping Mode of IEEE 802.15.4 (6TiSCH)",
RFC 9030, DOI 10.17487/RFC9030, May 2021,
<https://www.rfc-editor.org/info/rfc9030>.
[RFC3272] Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X.
Xiao, "Overview and Principles of Internet Traffic
Engineering", RFC 3272, DOI 10.17487/RFC3272, May 2002,
<https://www.rfc-editor.org/info/rfc3272>.
[RFC8938] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane
Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020,
<https://www.rfc-editor.org/info/rfc8938>.
[IEEE Std. 802.15.4]
IEEE standard for Information Technology, "IEEE Std.
802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
and Physical Layer (PHY) Specifications for Low-Rate
Wireless Personal Area Networks".
[IEEE 802.1 TSN]
IEEE 802.1, "Time-Sensitive Networking (TSN) Task Group",
<http://www.ieee802.org/1/pages/tsn.html>.
[IEEE Std. 1588]
IEEE, "IEEE Standard for a Precision Clock Synchronization
Protocol for Networked Measurement and Control Systems",
IEEE Standard 1588,
<https://ieeexplore.ieee.org/document/4579760/>.
Author's Address
Pascal Thubert (editor)
Cisco Systems, Inc
France
Phone: +33 497 23 26 34
Email: pthubert@cisco.com
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