draft-ietf-detnet-problem-statement-04.txt   draft-ietf-detnet-problem-statement-05.txt 
detnet N. Finn detnet N. Finn
Internet-Draft Huawei Technologies Co. Ltd Internet-Draft Huawei Technologies Co. Ltd
Intended status: Informational P. Thubert Intended status: Informational P. Thubert
Expires: December 8, 2018 Cisco Expires: December 24, 2018 Cisco
June 6, 2018 June 22, 2018
Deterministic Networking Problem Statement Deterministic Networking Problem Statement
draft-ietf-detnet-problem-statement-04 draft-ietf-detnet-problem-statement-05
Abstract Abstract
This paper documents the needs in various industries to establish This paper documents the needs in various industries to establish
multi-hop paths for characterized flows with deterministic properties multi-hop paths for characterized flows with deterministic
. properties.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 8, 2018. This Internet-Draft will expire on December 24, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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flows. flows.
Once the abstract model is agreed upon, the IETF will need to specify Once the abstract model is agreed upon, the IETF will need to specify
the signaling elements to be used to establish a path and the tagging the signaling elements to be used to establish a path and the tagging
elements to be used identify the flows that are to be forwarded along elements to be used identify the flows that are to be forwarded along
that path. The IETF will also need to specify the necessary that path. The IETF will also need to specify the necessary
protocols, or protocol additions, based on relevant IETF protocols, or protocol additions, based on relevant IETF
technologies, to implement the selected model. technologies, to implement the selected model.
As a result of this work, it will be possible to establish a multi- As a result of this work, it will be possible to establish a multi-
hop path over the IP network, for a particular flow with given timing hop path over the IP or MPLS network, for a particular flow with
and precise throughput requirements, and carry this particular flow given timing and precise throughput requirements, and carry this
along the multi-hop path with such characteristics as low latency and particular flow along the multi-hop path with such characteristics as
ultra-low jitter, duplication and elimination of packets over non- low latency and ultra-low jitter, reordering and/or replication and
congruent paths for a higher delivery ratio, and/or zero congestion elimination of packets over non-congruent paths for a higher delivery
loss, regardless of the amount of other flows in the network. ratio, and/or zero congestion loss, regardless of the amount of other
flows in the network.
Depending on the network capabilities and on the current state, Depending on the network capabilities and on the current state,
requests to establish a path by an end-node or a network management requests to establish a path by an end-node or a network management
entity may be granted or rejected, an existing path may be moved or entity may be granted or rejected, an existing path may be moved or
removed, and DetNet flows exceeding their contract may face packet removed, and DetNet flows exceeding their contract may face packet
declassification and drop. declassification and drop.
2. On Deterministic Networking 2. On Deterministic Networking
The Internet is not the only digital network that has grown The Internet is not the only digital network that has grown
dramatically over the last 30-40 years. Video and audio dramatically over the last 30-40 years. Video and audio
entertainment, and control systems for machinery, manufacturing entertainment, and control systems for machinery, manufacturing
processes, and vehicles are also ubiquitous, and are now based almost processes, and vehicles are also ubiquitous, and are now based almost
entirely on digital technologies. Over the past 10 years, engineers entirely on digital technologies. Over the past 10 years, engineers
in these fields have come to realize that significant advantages in in these fields have come to realize that significant advantages in
both cost and in the ability to accelerate growth can be obtained by both cost and in the ability to accelerate growth can be obtained by
basing all of these disparate digital technologies on packet basing all of these disparate digital technologies on packet
networks. networks.
The goals of Deterministic Networking are to enable the migration of The goals of Deterministic Networking (DetNet) are to enable the
applications with critical timing and reliability issues that migration of applications with critical timing and reliability issues
currently use special-purpose fieldbus technologies (HDMI, CANbus, that currently use special-purpose fieldbus technologies (HDMI,
ProfiBus, etc... even RS-232!) to packet technologies in general, and CANbus, ProfiBus, etc... even RS-232!) to packet technologies in
the Internet Protocol in particular, and to support both these new general, and the Internet Protocol in particular, and to support both
applications, and existing packet network applications, over the same these new applications, and existing packet network applications,
physical network. over the same physical network.
Considerable experience ([ODVA]/[EIP],[AVnu], Considerable experience ([ODVA]/[EIP],[AVnu],
[Profinet],[HART],[IEC62439], [ISA100.11a] and [WirelessHART], [Profinet],[HART],[IEC62439], [ISA100.11a] and [WirelessHART],
etc...) has shown that these applications need a some or all of a etc...) has shown that these applications need a some or all of a
suite of features that includes: suite of features that includes:
1. Time synchronization of all host and network nodes (routers and/ 1. Time synchronization of all host and network nodes (routers and/
or bridges), accurate to something between 10 nanoseconds and 10 or bridges), accurate to something between 10 nanoseconds and 10
microseconds, depending on the application. microseconds, depending on the application.
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3.2. Flow Characterization 3.2. Flow Characterization
Deterministic forwarding can only apply on flows with well-defined Deterministic forwarding can only apply on flows with well-defined
characteristics such as periodicity and burstiness. Before a path characteristics such as periodicity and burstiness. Before a path
can be established to serve them, the expression of those can be established to serve them, the expression of those
characteristics, and how the network can serve them, for instance in characteristics, and how the network can serve them, for instance in
shaping and forwarding operations, must be specified. shaping and forwarding operations, must be specified.
3.3. Centralized Path Computation and Installation 3.3. Centralized Path Computation and Installation
A centralized routing model, such as provided with a PCE, enables A centralized routing model, such as provided with a Path Computation
global and per-flow optimizations. The model is attractive but a Element (PCE) (see [RFC4655]), enables global and per-flow
number of issues are left to be solved. In particular: optimizations. The model is attractive but a number of issues are
left to be solved. In particular:
o whether and how the path computation can be installed by 1) an end o whether and how the path computation can be installed by 1) an end
device or 2) a Network Management entity, device or 2) a Network Management entity,
o and how the path is set up, either by installing state at each hop o and how the path is set up, either by installing state at each hop
with a direct interaction between the forwarding device and the with a direct interaction between the forwarding device and the
PCE, or along a path by injecting a source-routed request at one PCE, or along a path by injecting a source-routed request at one
end of the path following classical Traffic Engineering (TE) end of the path following classical Traffic Engineering (TE)
models. models.
To enable a centralized model, DetNet should produce the complete SDN To enable a centralized model, DetNet should produce a description of
architecture with describes at a high level the interaction and data the high level interaction and data models to:
models to:
o report the topology and device capabilities to the central o report the topology and device capabilities to the central
controller; controller;
o establish a direct interface between the centralized PCE to each o establish a direct interface between the centralized PCE to each
device under its control in order to enable a vertical signaling device under its control in order to enable a vertical signaling
o request a path setup for a new flow with particular o request a path setup for a new flow with particular
characteristics over the service interface and control it through characteristics over the service interface and control it through
its life cycle; its life cycle;
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But the focus of the work should be to deliver the centralized But the focus of the work should be to deliver the centralized
approach first. approach first.
To enable a RSVP-TE like functionality, the following steps would To enable a RSVP-TE like functionality, the following steps would
take place: take place:
1. Neighbors and their capabilities are discovered and exposed to 1. Neighbors and their capabilities are discovered and exposed to
compute a path that fits the DetNet constraints, typically of compute a path that fits the DetNet constraints, typically of
latency, time precision and resource availability. latency, time precision and resource availability.
2. A constrained path is calculated with an improved version of CSPF 2. A constrained path is calculated with an improved version of
that is aware of DetNet. Constrained Shortest Path First (CSPF) that is aware of DetNet.
3. The path may be installed using a control protocol such as RSVP- 3. The path may be installed using a control protocol such as RSVP-
TE, associated with flow identification, per-hop behavior such as TE, associated with flow identification, per-hop behavior such as
Packet Replication and Elimination, blocked resources, and flow Packet Replication and Elimination, blocked resources, and flow
timing information. Alternatively, the routing and flow timing information. In that case, traffic flows can be
information may be placed in-band in the packet, e.g., using transported through an MPLS-TE tunnel, using the reserved
Segment Routing, in which case the packet is routed along a resources for this flow at each hop.
prescribed source route path following forwarding indications
that are present in the packet.
4. Traffic flows are transported through the MPLS-TE tunnel, using 4. Alternatively, the routing and flow information may be placed in-
the reserved resources for this flow at each hop. band in the IP packet, e.g., using Segment Routing and/or IPv6
Routing and Option Headers, in which case the packet is routed
along a prescribed source route path following forwarding
indications that are present in the packet.
3.5. Duplicated data format 3.5. Duplicated data format
In some cases the duplication and elimination of packets over non- In some cases the duplication and elimination of packets over non-
congruent paths is required to achieve a sufficiently high delivery congruent paths is required to achieve a sufficiently high delivery
ratio to meet application needs. In these cases, a small number of ratio to meet application needs. In these cases, a small number of
packet formats and supporting protocols are required (preferably, packet formats and supporting protocols are required (preferably,
just one) to serialize the packets of a DetNet stream at one point in just one) to serialize the packets of a DetNet stream at one point in
the network, replicate them at one or more points in the network, and the network, replicate them at one or more points in the network, and
discard duplicates at one or more other points in the network, discard duplicates at one or more other points in the network,
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associated with a given flow at a given point of time. In that associated with a given flow at a given point of time. In that
model, Time Sharing of physical resources becomes transparent to the model, Time Sharing of physical resources becomes transparent to the
individual flows which have no clue whether the resources are used by individual flows which have no clue whether the resources are used by
other flows at other times. other flows at other times.
The overall security of a deterministic system must cover: The overall security of a deterministic system must cover:
o the protection of the signaling protocol o the protection of the signaling protocol
o the authentication and authorization of the controlling nodes o the authentication and authorization of the controlling nodes
including plug-and-play participating end systems.
o the identification and shaping of the flows o the identification and shaping of the flows
o the isolation of flows from leakage and other influences from any o the isolation of flows from leakage and other influences from any
activity sharing physical resources. activity sharing physical resources.
5. IANA Considerations 5. IANA Considerations
This document does not require an action from IANA. This document does not require an action from IANA.
6. Acknowledgments 6. Acknowledgments
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[Profinet] [Profinet]
http://us.profinet.com/technology/profinet/, "PROFINET is http://us.profinet.com/technology/profinet/, "PROFINET is
a standard for industrial networking in automation.", a standard for industrial networking in automation.",
<http://us.profinet.com/technology/profinet/>. <http://us.profinet.com/technology/profinet/>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc3209>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in [RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384, Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
October 2014, <https://www.rfc-editor.org/info/rfc7384>. October 2014, <https://www.rfc-editor.org/info/rfc7384>.
[WirelessHART] [WirelessHART]
www.hartcomm.org, "Industrial Communication Networks - www.hartcomm.org, "Industrial Communication Networks -
Wireless Communication Network and Communication Profiles Wireless Communication Network and Communication Profiles
- WirelessHART - IEC 62591", 2010. - WirelessHART - IEC 62591", 2010.
Authors' Addresses Authors' Addresses
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