draft-ietf-detnet-architecture-01.txt   draft-ietf-detnet-architecture-02.txt 
DetNet N. Finn DetNet N. Finn
Internet-Draft Huawei Technologies Co. Ltd Internet-Draft Huawei Technologies Co. Ltd
Intended status: Standards Track P. Thubert Intended status: Standards Track P. Thubert
Expires: September 14, 2017 Cisco Expires: December 31, 2017 Cisco
B. Varga B. Varga
J. Farkas J. Farkas
Ericsson Ericsson
March 13, 2017 June 29, 2017
Deterministic Networking Architecture Deterministic Networking Architecture
draft-ietf-detnet-architecture-01 draft-ietf-detnet-architecture-02
Abstract Abstract
Deterministic Networking (DetNet) provides a capability to carry Deterministic Networking (DetNet) provides a capability to carry
specified unicast or multicast data flows for real-time applications specified unicast or multicast data flows for real-time applications
with extremely low data loss rates and bounded latency. Techniques with extremely low data loss rates and bounded latency. Techniques
used include: 1) reserving data plane resources for individual (or used include: 1) reserving data plane resources for individual (or
aggregated) DetNet flows in some or all of the intermediate nodes aggregated) DetNet flows in some or all of the intermediate nodes
(e.g. bridges or routers) along the path of the flow; 2) providing (e.g. bridges or routers) along the path of the flow; 2) providing
explicit routes for DetNet flows that do not rapidly change with the explicit routes for DetNet flows that do not rapidly change with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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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 September 14, 2017. This Internet-Draft will expire on December 31, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Terms used in this document . . . . . . . . . . . . . . . 4 2.1. Terms used in this document . . . . . . . . . . . . . . . 4
2.2. IEEE 802 TSN to DetNet dictionary . . . . . . . . . . . . 6 2.2. IEEE 802 TSN to DetNet dictionary . . . . . . . . . . . . 6
3. Providing the DetNet Quality of Service . . . . . . . . . . . 6 3. Providing the DetNet Quality of Service . . . . . . . . . . . 7
3.1. Congestion protection . . . . . . . . . . . . . . . . . . 8 3.1. Primary goals defining the DetNet QoS . . . . . . . . . . 7
3.2. Explicit routes . . . . . . . . . . . . . . . . . . . . . 9 3.2. Mechanisms to achieve DetNet Qos . . . . . . . . . . . . 9
3.3. Jitter Reduction . . . . . . . . . . . . . . . . . . . . 10 3.2.1. Congestion protection . . . . . . . . . . . . . . . . 9
3.4. Packet Replication and Elimination . . . . . . . . . . . 10 3.2.2. Explicit routes . . . . . . . . . . . . . . . . . . . 9
3.5. Packet encoding for service protection . . . . . . . . . 12 3.2.3. Jitter Reduction . . . . . . . . . . . . . . . . . . 10
4. DetNet Architecture . . . . . . . . . . . . . . . . . . . . . 12 3.2.4. Packet Replication and Elimination . . . . . . . . . 11
4.1. DetNet systems . . . . . . . . . . . . . . . . . . . . . 12 3.3. Secondary goals for DetNet . . . . . . . . . . . . . . . 12
4.1.1. Network reference model . . . . . . . . . . . . . . . 13 3.3.1. Coexistence with normal traffic . . . . . . . . . . . 12
4.1.2. End system . . . . . . . . . . . . . . . . . . . . . 14 3.3.2. Fault Mitigation . . . . . . . . . . . . . . . . . . 13
4.2. Traffic Engineering for DetNet . . . . . . . . . . . . . 15 4. DetNet Architecture . . . . . . . . . . . . . . . . . . . . . 14
4.2.1. The Application Plane . . . . . . . . . . . . . . . . 16 4.1. DetNet stack model . . . . . . . . . . . . . . . . . . . 14
4.2.2. The Controller Plane . . . . . . . . . . . . . . . . 16 4.1.1. Representative Protocol Stack Model . . . . . . . . . 14
4.2.3. The Network Plane . . . . . . . . . . . . . . . . . . 17 4.1.2. DetNet Data Plane Overview . . . . . . . . . . . . . 16
4.3. DetNet flows . . . . . . . . . . . . . . . . . . . . . . 18 4.1.3. Network reference model . . . . . . . . . . . . . . . 18
4.3.1. DetNet flow types . . . . . . . . . . . . . . . . . . 18 4.2. DetNet systems . . . . . . . . . . . . . . . . . . . . . 19
4.3.2. Source guarantees . . . . . . . . . . . . . . . . . . 19 4.2.1. End system . . . . . . . . . . . . . . . . . . . . . 19
4.3.3. Incomplete Networks . . . . . . . . . . . . . . . . . 20 4.2.2. DetNet edge, relay, and transit nodes . . . . . . . . 20
4.4. Queuing, Shaping, Scheduling, and Preemption . . . . . . 20 4.3. DetNet flows . . . . . . . . . . . . . . . . . . . . . . 21
4.5. Service instance . . . . . . . . . . . . . . . . . . . . 21 4.3.1. DetNet flow types . . . . . . . . . . . . . . . . . . 21
4.6. Coexistence with normal traffic . . . . . . . . . . . . . 22 4.3.2. Source guarantees . . . . . . . . . . . . . . . . . . 21
4.7. Fault Mitigation . . . . . . . . . . . . . . . . . . . . 23 4.3.3. Incomplete Networks . . . . . . . . . . . . . . . . . 23
4.8. Representative Protocol Stack Model . . . . . . . . . . . 24 4.4. Traffic Engineering for DetNet . . . . . . . . . . . . . 23
4.9. Flow identification at technology borders . . . . . . . . 26 4.4.1. The Application Plane . . . . . . . . . . . . . . . . 23
4.9.1. Exporting flow identification . . . . . . . . . . . . 26 4.4.2. The Controller Plane . . . . . . . . . . . . . . . . 24
4.9.2. Flow attribute mapping between layers . . . . . . . . 27 4.4.3. The Network Plane . . . . . . . . . . . . . . . . . . 24
4.9.3. Flow-ID mapping examples . . . . . . . . . . . . . . 28 4.5. Queuing, Shaping, Scheduling, and Preemption . . . . . . 25
4.6. Service instance . . . . . . . . . . . . . . . . . . . . 26
4.10. Advertising resources, capabilities and adjacencies . . . 30 4.7. Flow identification at technology borders . . . . . . . . 27
4.11. Provisioning model . . . . . . . . . . . . . . . . . . . 31 4.7.1. Exporting flow identification . . . . . . . . . . . . 27
4.11.1. Centralized Path Computation and Installation . . . 31 4.7.2. Flow attribute mapping between layers . . . . . . . . 29
4.11.2. Distributed Path Setup . . . . . . . . . . . . . . . 31 4.7.3. Flow-ID mapping examples . . . . . . . . . . . . . . 30
4.12. Scaling to larger networks . . . . . . . . . . . . . . . 32 4.8. Advertising resources, capabilities and adjacencies . . . 32
4.13. Connected islands vs. networks . . . . . . . . . . . . . 32 4.9. Provisioning model . . . . . . . . . . . . . . . . . . . 32
5. Compatibility with Layer-2 . . . . . . . . . . . . . . . . . 32 4.9.1. Centralized Path Computation and Installation . . . . 32
6. Open Questions . . . . . . . . . . . . . . . . . . . . . . . 33 4.9.2. Distributed Path Setup . . . . . . . . . . . . . . . 32
6.1. Flat vs. hierarchical control . . . . . . . . . . . . . . 33 4.10. Scaling to larger networks . . . . . . . . . . . . . . . 33
6.2. Peer-to-peer reservation protocol . . . . . . . . . . . . 33 4.11. Connected islands vs. networks . . . . . . . . . . . . . 33
6.3. Wireless media interactions . . . . . . . . . . . . . . . 34 4.12. Compatibility with Layer-2 . . . . . . . . . . . . . . . 33
7. Security Considerations . . . . . . . . . . . . . . . . . . . 34 5. Open Questions . . . . . . . . . . . . . . . . . . . . . . . 34
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 35 5.1. Flat vs. hierarchical control . . . . . . . . . . . . . . 34
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 5.2. Peer-to-peer reservation protocol . . . . . . . . . . . . 34
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 35 5.3. Wireless media interactions . . . . . . . . . . . . . . . 35
11. Access to IEEE 802.1 documents . . . . . . . . . . . . . . . 35 5.4. Packet encoding for service protection . . . . . . . . . 35
12. Informative References . . . . . . . . . . . . . . . . . . . 35 6. Security Considerations . . . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 36
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 36
10. Access to IEEE 802.1 documents . . . . . . . . . . . . . . . 37
11. Informative References . . . . . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
1. Introduction 1. Introduction
Deterministic Networking (DetNet) is a service that can be offered by Deterministic Networking (DetNet) is a service that can be offered by
a network to DetNet flows. DetNet provides these flows extremely low a network to DetNet flows. DetNet provides these flows extremely low
packet loss rates and assured maximum end-to-end delivery latency. packet loss rates and assured maximum end-to-end delivery latency.
This is accomplished by dedicating network resources such as link This is accomplished by dedicating network resources such as link
bandwidth and buffer space to DetNet flows and/or classes of DetNet bandwidth and buffer space to DetNet flows and/or classes of DetNet
flows, and by replicating packets along multiple paths. Unused flows, and by replicating packets along multiple paths. Unused
reserved resources are available to non-DetNet packets. reserved resources are available to non-DetNet packets.
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topologies; connectivity is not restricted. Any application that topologies; connectivity is not restricted. Any application that
generates a data flow that can be usefully characterized as having a generates a data flow that can be usefully characterized as having a
maximum bandwidth should be able to take advantage of DetNet, as long maximum bandwidth should be able to take advantage of DetNet, as long
as the necessary resources can be reserved. Reservations can be made as the necessary resources can be reserved. Reservations can be made
by the application itself, via network management, by an applications by the application itself, via network management, by an applications
controller, or by other means. controller, or by other means.
Many applications of interest to Deterministic Networking require the Many applications of interest to Deterministic Networking require the
ability to synchronize the clocks in end systems to a sub-microsecond ability to synchronize the clocks in end systems to a sub-microsecond
accuracy. Some of the queue control techniques defined in accuracy. Some of the queue control techniques defined in
Section 4.4 also require time synchronization among relay and transit Section 4.5 also require time synchronization among relay and transit
nodes. The means used to achieve time synchronization are not nodes. The means used to achieve time synchronization are not
addressed in this document. DetNet should accommodate various addressed in this document. DetNet should accommodate various
synchronization techniques and profiles that are defined elsewhere to synchronization techniques and profiles that are defined elsewhere to
solve exchange time in different market segments. solve exchange time in different market segments.
The present document is an individual contribution, but it is The present document is an individual contribution, but it is
intended by the authors for adoption by the DetNet working group. intended by the authors for adoption by the DetNet working group.
2. Terminology 2. Terminology
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incorporates DetNet transport layer functions as well, in incorporates DetNet transport layer functions as well, in
which case it is collocated with a transit node. which case it is collocated with a transit node.
reservation reservation
A trail of configuration between source to destination(s) A trail of configuration between source to destination(s)
through transit nodes and subnets associated with a DetNet through transit nodes and subnets associated with a DetNet
flow, to provide congestion protection. flow, to provide congestion protection.
DetNet service layer DetNet service layer
The layer at which service protection is provided, either The layer at which service protection is provided, either
packet sequencing, replication, and elimination (Section 3.4) packet sequencing, replication, and elimination
or network coding (Section 3.5). (Section 3.2.4) or network coding (Section 5.4).
source source
An end system capable of sourcing a DetNet flow. An end system capable of sourcing a DetNet flow.
DetNet transit node DetNet transit node
A node operating at the DetNet transport layer, that utilizes A node operating at the DetNet transport layer, that utilizes
link layer and/or network layer switching across multiple link layer and/or network layer switching across multiple
links and/or sub-networks to provide paths for DetNet service links and/or sub-networks to provide paths for DetNet service
layer functions. Optionally provides congestion protection layer functions. Optionally provides congestion protection
over those paths. An MPLS LSR is an example of a DetNet over those paths. An MPLS LSR is an example of a DetNet
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The IEEE 802 term for a DetNet intermediate node. The IEEE 802 term for a DetNet intermediate node.
Stream Stream
The IEEE 802 term for a DetNet flow. The IEEE 802 term for a DetNet flow.
Talker Talker
The IEEE 802 term for the source of a DetNet flow. The IEEE 802 term for the source of a DetNet flow.
3. Providing the DetNet Quality of Service 3. Providing the DetNet Quality of Service
3.1. Primary goals defining the DetNet QoS
The DetNet Quality of Service can be expressed in terms of: The DetNet Quality of Service can be expressed in terms of:
o Minimum and maximum end-to-end latency from source to destination; o Minimum and maximum end-to-end latency from source to destination;
timely delivery and jitter avoidance derive from these constraints timely delivery and jitter avoidance derive from these constraints
o Probability of loss of a packet, under various assumptions as to o Probability of loss of a packet, under various assumptions as to
the operational states of the nodes and links. A derived property the operational states of the nodes and links. A derived property
is whether it is acceptable to deliver a duplicate packet, which is whether it is acceptable to deliver a duplicate packet, which
is an inherent risk in highly reliable and/or broadcast is an inherent risk in highly reliable and/or broadcast
transmissions transmissions
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case values for the end-to-end latency. Average, mean, or typical case values for the end-to-end latency. Average, mean, or typical
values are of no interest, because they do not affect the ability of values are of no interest, because they do not affect the ability of
a real-time system to perform its tasks. In general, a trivial a real-time system to perform its tasks. In general, a trivial
priority-based queuing scheme will give better average latency to a priority-based queuing scheme will give better average latency to a
data flow than DetNet, but of course, the worst-case latency can be data flow than DetNet, but of course, the worst-case latency can be
essentially unbounded. essentially unbounded.
Three techniques are used by DetNet to provide these qualities of Three techniques are used by DetNet to provide these qualities of
service: service:
o Congestion protection (Section 3.1). o Congestion protection (Section 3.2.1).
o Explicit routes (Section 3.2). o Explicit routes (Section 3.2.2).
o Service protection. o Service protection (Section 3.2.4).
Congestion protection operates by reserving resources along the path Congestion protection operates by reserving resources along the path
of a DetNet Flow, e.g. buffer space or link bandwidth. Congestion of a DetNet Flow, e.g. buffer space or link bandwidth. Congestion
protection greatly reduces, or even eliminates entirely, packet loss protection greatly reduces, or even eliminates entirely, packet loss
due to output packet congestion within the network, but it can only due to output packet congestion within the network, but it can only
be supplied to a DetNet flow that is limited at the source to a be supplied to a DetNet flow that is limited at the source to a
maximum packet size and transmission rate. maximum packet size and transmission rate.
Congestion protection addresses both of the DetNet QoS requirements Congestion protection addresses both of the DetNet QoS requirements
(latency and packet loss). Given that DetNet nodes have a finite (latency and packet loss). Given that DetNet nodes have a finite
amount of buffer space, congestion protection necessarily results in amount of buffer space, congestion protection necessarily results in
a maximum end-to-end latency. It also addresses the largest a maximum end-to-end latency. It also addresses the largest
contribution to packet loss, which is buffer congestion. contribution to packet loss, which is buffer congestion.
After congestion, the most important contributions to packet loss are After congestion, the most important contributions to packet loss are
typically from random media errors and equipment failures. Service typically from random media errors and equipment failures. Service
protection is the name for the mechanisms used by DetNet to address protection is the name for the mechanisms used by DetNet to address
these losses. The mechanisms employed are constrained by the these losses. The mechanisms employed are constrained by the
requirement to meet the users' latency requirements. Packet requirement to meet the users' latency requirements. Packet
replication and elimination (Section 3.4) packet encoding Section 3.5 replication and elimination (Section 3.2.4) packet encoding
are described in this document to provide service protection; others Section 5.4 are described in this document to provide service
may be found. Both mechanisms distribute the contents of DetNet protection; others may be found. Both mechanisms distribute the
flows over multiple paths in time and/or space, so that the loss of contents of DetNet flows over multiple paths in time and/or space, so
some of the paths does need not cause the loss of any packets. The that the loss of some of the paths does need not cause the loss of
paths are typically (but not necessarily) explicit routes, so that any packets. The paths are typically (but not necessarily) explicit
they cannot suffer temporary interruptions caused by the routes, so that they cannot suffer temporary interruptions caused by
reconvergence of routing or bridging protocols. the reconvergence of routing or bridging protocols.
These three techniques can be applied independently, giving eight These three techniques can be applied independently, giving eight
possible combinations, including none (no DetNet), although some possible combinations, including none (no DetNet), although some
combinations are of wider utility than others. This separation keeps combinations are of wider utility than others. This separation keeps
the protocol stack coherent and maximizes interoperability with the protocol stack coherent and maximizes interoperability with
existing and developing standards in this (IETF) and other Standards existing and developing standards in this (IETF) and other Standards
Development Organizations. Some examples of typical expected Development Organizations. Some examples of typical expected
combinations: combinations:
o Explicit routes plus service protection are exactly the techniques o Explicit routes plus service protection are exactly the techniques
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functioning properly, or in the absence of actions by end systems functioning properly, or in the absence of actions by end systems
that disrupt the network's operations. that disrupt the network's operations.
There are any number of methods in use, defined, or in progress for There are any number of methods in use, defined, or in progress for
accomplishing each of the above techniques. It is expected that this accomplishing each of the above techniques. It is expected that this
DetNet Architecture will assist various vendors, users, and/or DetNet Architecture will assist various vendors, users, and/or
"vertical" Standards Development Organizations (dedicated to a single "vertical" Standards Development Organizations (dedicated to a single
industry) to make selections among the available means of industry) to make selections among the available means of
implementing DetNet networks. implementing DetNet networks.
3.1. Congestion protection 3.2. Mechanisms to achieve DetNet Qos
3.2.1. Congestion protection
The primary means by which DetNet achieves its QoS assurances is to The primary means by which DetNet achieves its QoS assurances is to
reduce, or even completely eliminate, congestion at an output port as reduce, or even completely eliminate, congestion at an output port as
a cause of packet loss. Given that a DetNet flow cannot be a cause of packet loss. Given that a DetNet flow cannot be
throttled, this can be achieved only by the provision of sufficient throttled, this can be achieved only by the provision of sufficient
buffer storage at each hop through the network to ensure that no buffer storage at each hop through the network to ensure that no
packets are dropped due to a lack of buffer storage. packets are dropped due to a lack of buffer storage.
Ensuring adequate buffering requires, in turn, that the source, and Ensuring adequate buffering requires, in turn, that the source, and
every intermediate node along the path to the destination (or nearly every intermediate node along the path to the destination (or nearly
every node -- see Section 4.3.3) be careful to regulate its output to every node -- see Section 4.3.3) be careful to regulate its output to
not exceed the data rate for any DetNet flow, except for brief not exceed the data rate for any DetNet flow, except for brief
periods when making up for interfering traffic. Any packet sent periods when making up for interfering traffic. Any packet sent
ahead of its time potentially adds to the number of buffers required ahead of its time potentially adds to the number of buffers required
by the next hop, and may thus exceed the resources allocated for a by the next hop, and may thus exceed the resources allocated for a
particular DetNet flow. particular DetNet flow.
The low-level mechanisms described in Section 4.4 provide the The low-level mechanisms described in Section 4.5 provide the
necessary regulation of transmissions by an end system or necessary regulation of transmissions by an end system or
intermediate node to provide congestion protection. The reservation intermediate node to provide congestion protection. The reservation
of the bandwidth and buffers for a DetNet flow requires the of the bandwidth and buffers for a DetNet flow requires the
provisioning described in Section 4.11. A DetNet node may have other provisioning described in Section 4.9. A DetNet node may have other
resources requiring allocation and/or scheduling, that might resources requiring allocation and/or scheduling, that might
otherwise be over-subscribed and trigger the rejection of a otherwise be over-subscribed and trigger the rejection of a
reservation. reservation.
3.2. Explicit routes 3.2.2. Explicit routes
In networks controlled by typical peer-to-peer protocols such as IEEE In networks controlled by typical peer-to-peer protocols such as IEEE
802.1 ISIS bridged networks or IETF OSPF routed networks, a network 802.1 ISIS bridged networks or IETF OSPF routed networks, a network
topology event in one part of the network can impact, at least topology event in one part of the network can impact, at least
briefly, the delivery of data in parts of the network remote from the briefly, the delivery of data in parts of the network remote from the
failure or recovery event. Thus, even redundant paths through a failure or recovery event. Thus, even redundant paths through a
network, if controlled by the typical peer-to-peer protocols, do not network, if controlled by the typical peer-to-peer protocols, do not
eliminate the chances of brief losses of contact. eliminate the chances of brief losses of contact.
Many real-time networks rely on physical rings or chains of two-port Many real-time networks rely on physical rings or chains of two-port
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wiring. As an additional benefit, ring topologies can often utilize wiring. As an additional benefit, ring topologies can often utilize
different topology management protocols than those used for a mesh different topology management protocols than those used for a mesh
network, with a consequent reduction in the response time to topology network, with a consequent reduction in the response time to topology
changes. Of course, this comes at some cost in terms of increased changes. Of course, this comes at some cost in terms of increased
hop count, and thus latency, for the typical path. hop count, and thus latency, for the typical path.
In order to get the advantages of low hop count and still ensure In order to get the advantages of low hop count and still ensure
against even very brief losses of connectivity, DetNet employs against even very brief losses of connectivity, DetNet employs
explicit routes, where the path taken by a given DetNet flow does not explicit routes, where the path taken by a given DetNet flow does not
change, at least immediately, and likely not at all, in response to change, at least immediately, and likely not at all, in response to
network topology events. Service protection (Section 3.4 or network topology events. Service protection (Section 3.2.4 or
Section 3.5) over explicit routes provides a high likelihood of Section 5.4) over explicit routes provides a high likelihood of
continuous connectivity. Explicit routes are commonly used in MPLS continuous connectivity. Explicit routes are commonly used in MPLS
TE LSPs. TE LSPs.
3.3. Jitter Reduction 3.2.3. Jitter Reduction
A core objective of DetNet is to enable the convergence of Non-IP A core objective of DetNet is to enable the convergence of Non-IP
networks onto a common network infrastructure. This requires the networks onto a common network infrastructure. This requires the
accurate emulation of currently deployed mission-specific networks, accurate emulation of currently deployed mission-specific networks,
which typically rely on point-to-point analog (e.g. 4-20mA which typically rely on point-to-point analog (e.g. 4-20mA
modulation) and serial-digital cables (or buses) for highly reliable, modulation) and serial-digital cables (or buses) for highly reliable,
synchronized and jitter-free communications. While the latency of synchronized and jitter-free communications. While the latency of
analog transmissions is basically the speed of light, legacy serial analog transmissions is basically the speed of light, legacy serial
links are usually slow (in the order of Kbps) compared to, say, GigE, links are usually slow (in the order of Kbps) compared to, say, GigE,
and some latency is usually acceptable. What is not acceptable is and some latency is usually acceptable. What is not acceptable is
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practical limitations on packet-based networks in this regard. In practical limitations on packet-based networks in this regard. In
general, users are encouraged to use, instead of, "do this when you general, users are encouraged to use, instead of, "do this when you
get the packet," a combination of: get the packet," a combination of:
o Sub-microsecond time synchronization among all source and o Sub-microsecond time synchronization among all source and
destination end systems, and destination end systems, and
o Time-of-execution fields in the application packets. o Time-of-execution fields in the application packets.
Jitter reduction is provided by the mechanisms described in Jitter reduction is provided by the mechanisms described in
Section 4.4 that also provide congestion protection. Section 4.5 that also provide congestion protection.
3.4. Packet Replication and Elimination 3.2.4. Packet Replication and Elimination
After congestion loss has been eliminated, the most important causes After congestion loss has been eliminated, the most important causes
of packet loss are random media and/or memory faults, and equipment of packet loss are random media and/or memory faults, and equipment
failures. Both causes of packet loss can be greatly reduced by failures. Both causes of packet loss can be greatly reduced by
spreading the data in a packet over multiple transmissions. One such spreading the data in a packet over multiple transmissions. One such
method for service protection is described in this section, which method for service protection is described in this section, which
sends the same packets over multiple paths. See also Section 3.5. sends the same packets over multiple paths. See also Section 5.4.
Packet replication and elimination, also known as seamless redundancy Packet replication and elimination, also known as seamless redundancy
[HSR-PRP], or 1+1 hitless protection, is a function of the DetNet [HSR-PRP], or 1+1 hitless protection, is a function of the DetNet
service layer. It involves three capabilities: service layer. It involves three capabilities:
o Providing sequencing information, once, at or near the source, to o Providing sequencing information, once, at or near the source, to
the packets of a DetNet compound flow. This may be done by adding the packets of a DetNet compound flow. This may be done by adding
a sequence number or time stamp as part of DetNet, or may be a sequence number or time stamp as part of DetNet, or may be
inherent in the packet, e.g. in a transport protocol, or inherent in the packet, e.g. in a transport protocol, or
associated to other physical properties such as the precise time associated to other physical properties such as the precise time
(and radio channel) of reception of the packet. Section 3.2. (and radio channel) of reception of the packet. Section 3.2.2.
o Replicating these packets into multiple DetNet member flows and, o Replicating these packets into multiple DetNet member flows and,
typically, sending them along at least two different paths to the typically, sending them along at least two different paths to the
destination(s), e.g. over the explicit routes of destination(s), e.g. over the explicit routes of
o Eliminating duplicated packets. This may be done at any step o Eliminating duplicated packets. This may be done at any step
along the path to save network resources further down, in along the path to save network resources further down, in
particular if multiple Replication points exist. But the most particular if multiple Replication points exist. But the most
common case is to perform this operation at the very edge of the common case is to perform this operation at the very edge of the
DetNet network, preferably in or near the receiver. DetNet network, preferably in or near the receiver.
skipping to change at page 12, line 25 skipping to change at page 12, line 33
Figure 1 Figure 1
Note that packet replication and elimination does not react to and Note that packet replication and elimination does not react to and
correct failures; it is entirely passive. Thus, intermittent correct failures; it is entirely passive. Thus, intermittent
failures, mistakenly created packet filters, or misrouted data is failures, mistakenly created packet filters, or misrouted data is
handled just the same as the equipment failures that are detected handled just the same as the equipment failures that are detected
handled by typical routing and bridging protocols. handled by typical routing and bridging protocols.
If packet replication and elimination is used over paths providing If packet replication and elimination is used over paths providing
congestion protection (Section 3.1), and member flows that take congestion protection (Section 3.2.1), and member flows that take
different-length paths through the network are combined, a merge different-length paths through the network are combined, a merge
point may require extra buffering to equalize the delays over the point may require extra buffering to equalize the delays over the
different paths. This equalization ensures that the resultant different paths. This equalization ensures that the resultant
compound flow will not exceed its contracted bandwidth even after one compound flow will not exceed its contracted bandwidth even after one
or the other of the paths is restored after a failure. or the other of the paths is restored after a failure.
3.5. Packet encoding for service protection 3.3. Secondary goals for DetNet
There are methods for using multiple paths to provide service Many applications require DetNet to provide additional services,
protection that involve encoding the information in a packet including coesistence with other QoS mechanisms Section 3.3.1 and
belonging to a DetNet flow into multiple transmission units, protection against misbehaving transmitters Section 3.3.2.
typically combining information from multiple packets into any given
transmission unit. Such techniques may be applicable for use as a
DetNet service protection technique, assuming that the DetNet users'
needs for timeliness of delivery and freedom from interference with
misbehaving DetNet flows can be met.
No specific mechanisms are defined here, at this time. This section 3.3.1. Coexistence with normal traffic
will either be enhanced or removed. Contributions are invited.
A DetNet network supports the dedication of a high proportion (e.g.
75%) of the network bandwidth to DetNet flows. But, no matter how
much is dedicated for DetNet flows, it is a goal of DetNet to coexist
with existing Class of Service schemes (e.g., DiffServ). It is also
important that non-DetNet traffic not disrupt the DetNet flow, of
course (see Section 3.3.2 and Section 6). For these reasons:
o Bandwidth (transmission opportunities) not utilized by a DetNet
flow are available to non-DetNet packets (though not to other
DetNet flows).
o DetNet flows can be shaped or scheduled, in order to ensure that
the highest-priority non-DetNet packet also is ensured a worst-
case latency (at any given hop).
o When transmission opportunities for DetNet flows are scheduled in
detail, then the algorithm constructing the schedule should leave
sufficient opportunities for non-DetNet packets to satisfy the
needs of the users of the network. Detailed scheduling can also
permit the time-shared use of buffer resources by different DetNet
flows.
Ideally, the net effect of the presence of DetNet flows in a network
on the non-DetNet packets is primarily a reduction in the available
bandwidth.
3.3.2. Fault Mitigation
One key to building robust real-time systems is to reduce the
infinite variety of possible failures to a number that can be
analyzed with reasonable confidence. DetNet aids in the process by
providing filters and policers to detect DetNet packets received on
the wrong interface, or at the wrong time, or in too great a volume,
and to then take actions such as discarding the offending packet,
shutting down the offending DetNet flow, or shutting down the
offending interface.
It is also essential that filters and service remarking be employed
at the network edge to prevent non-DetNet packets from being mistaken
for DetNet packets, and thus impinging on the resources allocated to
DetNet packets.
There exist techniques, at present and/or in various stages of
standardization, that can perform these fault mitigation tasks that
deliver a high probability that misbehaving systems will have zero
impact on well-behaved DetNet flows, except of course, for the
receiving interface(s) immediately downstream of the misbehaving
device. Examples of such techniques include traffic policing
functions (e.g. [RFC2475]) and separating flows into per-flow rate-
limited queues.
4. DetNet Architecture 4. DetNet Architecture
4.1. DetNet systems 4.1. DetNet stack model
4.1.1. Network reference model
The figure below shows the DetNet service related reference points 4.1.1. Representative Protocol Stack Model
and main components (Figure 2).
DetNet DetNet Figure 2 illustrates a conceptual DetNet data plane layering model.
end system end system One may compare it to that in [IEEE802.1CB], Annex C, a work in
_ _ progress.
/ \ +----DetNet-UNI (U) / \
/App\ | /App\
/-----\ | /-----\
| NIC | v ________ | NIC |
+--+--+ _____ / \ DetNet-UNI (U) --+ +--+--+
| / \__/ \ | |
| / +----+ +----+ \_____ | |
| / | | | | \_______ | |
+--------U PE +----+ P +----+ \ _ v |
| | | | | | | ___/ \ |
| +--+-+ +----+ | +----+ | / \_ |
\ | | | | | / \ |
\ | +----+ +--+-+ +--+PE |---------- U------+
\ | | | | | | | | | \_ _/
\ +---+ P +----+ P +--+ +----+ | \____/
\___ | | | | /
\ +----+__ +----+ DetNet-1 DetNet-2
| \_____/ \___________/ |
| |
| | End-to-End-Service | | | |
<-------------------------------------------------------------------->
| | DetNet-Service | | | |
| <----------------------------------------------------> |
| | | | | |
Figure 2: DetNet Service Reference Model (multi-domain) DetNet data plane protocol stack
DetNet-UNIs ("U" in Figure 2) are assumed in this document to be | packets going | ^ packets coming ^
v down the stack v | up the stack |
+----------------------+ +-----------------------+
| Source | | Destination |
+----------------------+ +-----------------------+
| Service layer | | Service layer |
| Packet sequencing | | Duplicate elimination |
| Flow duplication | | Flow merging |
| Packet encoding | | Packet decoding |
+----------------------+ +-----------------------+
| Transport layer | | Transport layer |
| Congestion prot. | | Congestion prot. |
+----------------------+ +-----------------------+
| Lower layers | | Lower layers |
+----------------------+ +-----------------------+
v ^
\_________________________/
Figure 2
Not all layers are required for any given application, or even for
any given network. The layers are, from top to bottom:
Application
Shown as "source" and "destination" in the diagram.
OAM
Operations, Administration, and Maintenance leverages in-band
and out-of-and signaling that validates whether the service
is effectively obtained within QoS constraints. OAM is not
shown in Figure 2; it may reside in any number of the layers.
OAM can involve specific tagging added in the packets for
tracing implementation or network configuration errors;
traceability enables to find whether a packet is a replica,
which relay node performed the replication, and which segment
was intended for the replica.
Packet sequencing
As part of DetNet service protection, supplies the sequence
number for packet replication and elimination
(Section 3.2.4). Peers with Duplicate elimination. This
layer is not needed if a higher-layer transport protocol is
expected to perform any packet sequencing and duplicate
elimination required by the DetNet flow duplication.
Duplicate elimination
As part of the DetNet service layer, based on the sequenced
number supplied by its peer, packet sequencing, Duplicate
elimination discards any duplicate packets generated by
DetNet flow duplication. It can operate on member flows,
compound flows, or both. The duplication may also be
inferred from other information such as the precise time of
reception in a scheduled network. The duplicate elimination
layer may also perform resequencing of packets to restore
packet order in a flow that was disrupted by the loss of
packets on one or another of the multiple paths taken.
Flow duplication
As part of DetNet service protection, replicates packets that
belong to a DetNet compound flow into two or more DetNet
member flows. Note that this function is separate from
packet sequencing. Flow duplication can be an explicit
duplication and remarking of packets, or can be performed by,
for example, techniques similar to ordinary multicast
replication. Peers with DetNet flow merging.
Network flow merging
As part of DetNet service protection, merges DetNet member
flows together for packets coming up the stack belonging to a
specific DetNet compound flow. Peers with DetNet flow
duplication. DetNet flow merging, together with packet
sequencing, duplicate elimination, and DetNet flow
duplication, performs packet replication and elimination
(Section 3.2.4).
Packet encoding
As part of DetNet service protection, as an alternative to
packet sequencing and flow duplication, packet encoding
combines the information in multiple DetNet packets, perhaps
from different DetNet compound flows, and transmits that
information in packets on different DetNet member Flows.
Peers with Packet decoding.
Packet decoding
As part of DetNet service protection, as an alternative to
flow merging and duplicate elimination, packet decoding takes
packets from different DetNet member flows, and computes from
those packets the original DetNet packets from the compound
flows input to packet encoding. Peers with Packet encoding.
Congestion protection
The DetNet transport layer provides congestion protection.
See Section 4.5. The actual queuing and shaping mechanisms
are typically provided by underlying subnet layers, but since
these are can be closely associated with the means of
providing paths for DetNet flows (e.g. MPLS LSPs or {VLAN,
multicast destination MAC address} pairs), the path and the
congestion protection are conflated in this figure.
Note that the packet sequencing and duplication elimination functions
at the source and destination ends of a DetNet compound flow may be
performed either in the end system or in a DetNet edge node. The
reader must not confuse a DetNet edge function with other kinds of
edge functions, e.g. an Label Edge Router, although the two functions
may be performed together. The DetNet edge function is concerned
with sequencing packets belonging to DetNet flows. The LER with
encapsulating/decapsulating packets for transport, and is considered
part of the network underlying the DetNet transport layer.
4.1.2. DetNet Data Plane Overview
A "Deterministic Network" will be composed of DetNet enabled nodes
i.e., End Systems, Edge Nodes, Relay Nodes and collectively deliver
DetNet services. DetNet enabled nodes are interconnected via Transit
Nodes (i.e., routers) which support DetNet, but are not DetNet
service aware. Transit nodes see DetNet nodes as end points. All
DetNet enabled nodes are connect to sub-networks, where a point-to-
point link is also considered as a simple sub-network. These sub-
networks will provide DetNet compatible service for support of DetNet
traffic. Examples of sub-networks include IEEE 802.1 TSN and OTN.
Of course, multi-layer DetNet systems may also be possible, where one
DetNet appears as a sub-network, and provides service to, a higher
layer DetNet system. A simple DetNet concept network is shown in
Figure 3.
TSN Edge Transit Relay DetNet
End System Node Node Node End System
+---------+ +.........+ +---------+
| Appl. |<---:Svc Proxy:-- End to End Service ---------->| Appl. |
+---------+ +---------+ +---------+ +---------+
| TSN | |TSN| |Svc|<-- DetNet flow ---: Service :-->| Service |
+---------+ +---+ +---+ +---------+ +---------+ +---------+
|Transport| |Trp| |Trp| |Transport| |Trp| |Trp| |Transport|
+-------.-+ +-.-+ +-.-+ +--.----.-+ +-.-+ +-.-+ +---.-----+
: Link : / ,-----. \ : Link : / ,-----. \
+........+ +-[ Sub ]-+ +........+ +-[ Sub ]-+
[Network] [Network]
`-----' `-----'
Figure 3: A Simple DetNet Enabled Network
Distinguishing the function of these two DetNet data plane layers,
the DetNet service layer and the DetNet transport layer, helps to
explore and evaluate various combinations of the data plane solutions
available. This separation of DetNet layers, while helpful, should
not be considered as formal requirement. For example, some
technologies may violate these strict layers and still be able to
deliver a DetNet service.
.
.
+-----------+
| Service | PW, RTP/(UDP), GRE
+-----------+
| Transport | (UDP)/IPv6, (UDP)/IPv4, MPLS LSPs, BIER
+-----------+
.
.
Figure 4: DetNet adaptation to data plane
In some networking scenarios, the end system initially provides a
DetNet flow encapsulation, which contains all information needed by
DetNet nodes (e.g., Real-time Transport Protocol (RTP) [RFC3550]
based DetNet flow transported over a native UDP/IP network or
PseudoWire). In other scenarios, the encapsulation formats might
differ significantly. As an example, a CPRI "application's" I/Q data
mapped directly to Ethernet frames may have to be transported over an
MPLS-based packet switched network (PSN).
There are many valid options to create a data plane solution for
DetNet traffic by selecting a technology approach for the DetNet
service layer and also selecting a technology approach for the DetNet
transport layer. There are a high number of valid combinations.
One of the most fundamental differences between different potential
data plane options is the basic addressing and headers used by DetNet
end systems. For example, is the basic service a Layer 2 (e.g.,
Ethernet) or Layer 3 (i.e., IP) service. This decision impacts how
DetNet end systems are addressed, and the basic forwarding logic for
the DetNet service layer.
4.1.3. Network reference model
The figure below shows another view of the DetNet service related
reference points and main components (Figure 5).
DetNet DetNet
end system end system
_ _
/ \ +----DetNet-UNI (U) / \
/App\ | /App\
/-----\ | /-----\
| NIC | v ________ | NIC |
+--+--+ _____ / \ DetNet-UNI (U) --+ +--+--+
| / \__/ \ | |
| / +----+ +----+ \_____ | |
| / | | | | \_______ | |
+------U PE +----+ P +----+ \ _ v |
| | | | | | | ___/ \ |
| +--+-+ +----+ | +----+ | / \_ |
\ | | | | | / \ |
\ | +----+ +--+-+ +--+PE |-------- U------+
\ | | | | | | | | | \_ _/
\ +---+ P +----+ P +--+ +----+ | \____/
\___ | | | | /
\ +----+__ +----+ DetNet-1 DetNet-2
| \_____/ \___________/ |
| |
| | End-to-End-Service | | | |
<---------------------------------------------------------------->
| | DetNet-Service | | | |
| <--------------------------------------------------> |
| | | | | |
Figure 5: DetNet Service Reference Model (multi-domain)
DetNet-UNIs ("U" in Figure 5) are assumed in this document to be
packet-based reference points and provide connectivity over the packet-based reference points and provide connectivity over the
packet network. A DetNet-UNI may provide multiple functions, e.g., packet network. A DetNet-UNI may provide multiple functions, e.g.,
it may add networking technology specific encapsulation to the DetNet it may add networking technology specific encapsulation to the DetNet
flows if necessary; it may provide status of the availability of the flows if necessary; it may provide status of the availability of the
connection associated to a reservation; it may provide a connection associated to a reservation; it may provide a
synchronization service for the end system; it may carry enough synchronization service for the end system; it may carry enough
signaling to place the reservation in a network without a controller, signaling to place the reservation in a network without a controller,
or if the controller only deals with the network but not the end or if the controller only deals with the network but not the end
points. Internal reference points of end systems (between the points. Internal reference points of end systems (between the
application and the NIC) are more challenging from control application and the NIC) are more challenging from control
perspective and they may have extra requirements (e.g., in-order perspective and they may have extra requirements (e.g., in-order
delivery is expected in end system internal reference points, whereas delivery is expected in end system internal reference points, whereas
it is considered optional over the DetNet-UNI), therefore not covered it is considered optional over the DetNet-UNI), therefore not covered
in this document. in this document.
4.1.2. End system 4.2. DetNet systems
4.2.1. End system
The native data flow between the source/destination end systems is The native data flow between the source/destination end systems is
referred to as application-flow (App-flow). The traffic referred to as application-flow (App-flow). The traffic
characteristics of an App-flow can be CBR (constant bit rate) or VBR characteristics of an App-flow can be CBR (constant bit rate) or VBR
(variable bit rate) and can have L1 or L2 or L3 encapsulation (e.g., (variable bit rate) and can have L1 or L2 or L3 encapsulation (e.g.,
TDM (time-division multiplexing), Ethernet, IP). These TDM (time-division multiplexing), Ethernet, IP). These
characteristics are considered as input for resource reservation and characteristics are considered as input for resource reservation and
might be simplified to ensure determinism during transport (e.g., might be simplified to ensure determinism during transport (e.g.,
making reservations for the peak rate of VBR traffic, etc.). making reservations for the peak rate of VBR traffic, etc.).
An end system may or may not be DetNet transport layer aware or An end system may or may not be DetNet transport layer aware or
DetNet service layer aware. That is, an end system may or may not DetNet service layer aware. That is, an end system may or may not
contain DetNet specific functionality. End systems with DetNet contain DetNet specific functionality. End systems with DetNet
functionalities may have the same or different transport layer as the functionalities may have the same or different transport layer as the
connected DetNet domain. Grouping of end systems are shown in connected DetNet domain. Grouping of end systems are shown in
Figure 3. Figure 6.
End system End system
| |
| |
| DetNet aware ? | DetNet aware ?
/ \ / \
+------< >------+ +------< >------+
NO | \ / | YES NO | \ / | YES
| v | | v |
DetNet unaware | DetNet unaware |
skipping to change at page 15, line 29 skipping to change at page 20, line 29
t-aware | \ / | s-aware t-aware | \ / | s-aware
| v | | v |
| | both | | | both |
| | | | | |
DetNet t-aware | DetNet s-aware DetNet t-aware | DetNet s-aware
End system | End system End system | End system
v v
DetNet st-aware DetNet st-aware
End system End system
Figure 3: Grouping of end systems Figure 6: Grouping of end systems
Note some known use cases for end systems: Note some known use cases for end systems:
o DetNet unaware: The classic case requiring network proxies. o DetNet unaware: The classic case requiring network proxies.
o DetNet t-aware: An extant TSN system. It knows about some TSN o DetNet t-aware: An extant TSN system. It knows about some TSN
functions (e.g., reservation), but not about replication/ functions (e.g., reservation), but not about replication/
elimination. elimination.
o DetNet s-aware: An extant IEC 62439-3 system. It supplies o DetNet s-aware: An extant IEC 62439-3 system. It supplies
sequence numbers, but doesn't know about zero congestion loss. sequence numbers, but doesn't know about zero congestion loss.
o DetNet st-aware: A full functioning DetNet end station, it has o DetNet st-aware: A full functioning DetNet end station, it has
DetNet functionalities and usually the same forwarding paradigm as DetNet functionalities and usually the same forwarding paradigm as
the connected DetNet domain. It can be treated as an integral the connected DetNet domain. It can be treated as an integral
part of the DetNet domain . part of the DetNet domain .
4.2. Traffic Engineering for DetNet 4.2.2. DetNet edge, relay, and transit nodes
As shown in Figure 3, DetNet edge nodes providing proxy service and
DetNet relay nodes providing the DetNet service layer are DetNet-
aware, and DetNet transit nodes need only be aware of the DetNet
transport layer.
In general, if a DetNet flow passes through one or more DetNet-
unaware network node between two DetNet nodes providing the DetNet
transport layer for that flow, there is a potential for disruption or
failure of the DetNet QoS. A network administrator needs to ensure
that the DetNet-unaware network nodes are configured to minimize the
chances of packet loss and delay, and provision enough exra buffer
space in the DetNet transit node following the DetNet-unaware network
nodes to absorb the induced latency variations.
4.3. DetNet flows
4.3.1. DetNet flow types
A DetNet flow can have different formats during while it is
transported between the peer end systems. Therefore, the following
possible types / formats of a DetNet flow are distinguished in this
document:
o App-flow: native format of a DetNet flow. It does not contain any
DetNet related attributes.
o DetNet-t-flow: specific format of a DetNet flow. Only requires
the congestion / latency features provided by the Detnet transport
layer.
o DetNet-s-flow: specific format of a DetNet flow. Only requires
the replication/elimination feature ensured by the DetNet service
layer.
o DetNet-st-flow: specific format of a DetNet flow. It requires
both DetNet service layer and DetNet transport layer functions
during forwarding.
4.3.2. Source guarantees
For the purposes of congestion protection, DetNet flows can be
synchronous or asynchronous. In synchronous DetNet flows, at least
the intermediate nodes (and possibly the end systems) are closely
time synchronized, typically to better than 1 microsecond. By
transmitting packets from different DetNet flows or classes of DetNet
flows at different times, using repeating schedules synchronized
among the intermediate nodes, resources such as buffers and link
bandwidth can be shared over the time domain among different DetNet
flows. There is a tradeoff among techniques for synchronous DetNet
flows between the burden of fine-grained scheduling and the benefit
of reducing the required resources, especially buffer space.
In contrast, asynchronous DetNet flows are not coordinated with a
fine-grained schedule, so relay and end systems must assume worst-
case interference among DetNet flows contending for buffer resources.
Asynchronous DetNet flows are characterized by:
o A maximum packet size;
o An observation interval; and
o A maximum number of transmissions during that observation
interval.
These parameters, together with knowledge of the protocol stack used
(and thus the size of the various headers added to a packet), limit
the number of bit times per observation interval that the DetNet flow
can occupy the physical medium.
The source promises that these limits will not be exceeded. If the
source transmits less data than this limit allows, the unused
resources such as link bandwidth can be made available by the system
to non-DetNet packets. However, making those resources available to
DetNet packets in other DetNet flows would serve no purpose. Those
other DetNet flows have their own dedicated resources, on the
assumption that all DetNet flows can use all of their resources over
a long period of time.
Note that there is no provision in DetNet for throttling DetNet flows
(reducing the transmission rate via feedback); the assumption is that
a DetNet flow, to be useful, must be delivered in its entirety. That
is, while any useful application is written to expect a certain
number of lost packets, the real-time applications of interest to
DetNet demand that the loss of data due to the network is
extraordinarily infrequent.
Although DetNet strives to minimize the changes required of an
application to allow it to shift from a special-purpose digital
network to an Internet Protocol network, one fundamental shift in the
behavior of network applications is impossible to avoid: the
reservation of resources before the application starts. In the first
place, a network cannot deliver finite latency and practically zero
packet loss to an arbitrarily high offered load. Secondly, achieving
practically zero packet loss for unthrottled (though bandwidth
limited) DetNet flows means that bridges and routers have to dedicate
buffer resources to specific DetNet flows or to classes of DetNet
flows. The requirements of each reservation have to be translated
into the parameters that control each system's queuing, shaping, and
scheduling functions and delivered to the hosts, bridges, and
routers.
4.3.3. Incomplete Networks
The presence in the network of transit nodes or subnets that are not
fully capable of offering DetNet services complicates the ability of
the intermediate nodes and/or controller to allocate resources, as
extra buffering, and thus extra latency, must be allocated at points
downstream from the non-DetNet intermediate node for a DetNet flow.
4.4. Traffic Engineering for DetNet
Traffic Engineering Architecture and Signaling (TEAS) [TEAS] defines Traffic Engineering Architecture and Signaling (TEAS) [TEAS] defines
traffic-engineering architectures for generic applicability across traffic-engineering architectures for generic applicability across
packet and non-packet networks. From TEAS perspective, Traffic packet and non-packet networks. From TEAS perspective, Traffic
Engineering (TE) refers to techniques that enable operators to Engineering (TE) refers to techniques that enable operators to
control how specific traffic flows are treated within their networks. control how specific traffic flows are treated within their networks.
Because if its very nature of establishing explicit optimized paths, Because if its very nature of establishing explicit optimized paths,
Deterministic Networking can be seen as a new, specialized branch of Deterministic Networking can be seen as a new, specialized branch of
Traffic Engineering, and inherits its architecture with a separation Traffic Engineering, and inherits its architecture with a separation
into planes. into planes.
The Deterministic Networking architecture is thus composed of three The Deterministic Networking architecture is thus composed of three
planes, a (User) Application Plane, a Controller Plane, and a Network planes, a (User) Application Plane, a Controller Plane, and a Network
Plane, which echoes that of Figure 1 of Software-Defined Networking Plane, which echoes that of Figure 1 of Software-Defined Networking
(SDN): Layers and Architecture Terminology [RFC7426].: (SDN): Layers and Architecture Terminology [RFC7426].:
4.2.1. The Application Plane 4.4.1. The Application Plane
Per [RFC7426], the Application Plane includes both applications and Per [RFC7426], the Application Plane includes both applications and
services. In particular, the Application Plane incorporates the User services. In particular, the Application Plane incorporates the User
Agent, a specialized application that interacts with the end user / Agent, a specialized application that interacts with the end user /
operator and performs requests for Deterministic Networking services operator and performs requests for Deterministic Networking services
via an abstract Flow Management Entity, (FME) which may or may not be via an abstract Flow Management Entity, (FME) which may or may not be
collocated with (one of) the end systems. collocated with (one of) the end systems.
At the Application Plane, a management interface enables the At the Application Plane, a management interface enables the
negotiation of flows between end systems. An abstraction of the flow negotiation of flows between end systems. An abstraction of the flow
called a Traffic Specification (TSpec) provides the representation. called a Traffic Specification (TSpec) provides the representation.
This abstraction is used to place a reservation over the (Northbound) This abstraction is used to place a reservation over the (Northbound)
Service Interface and within the Application plane. It is associated Service Interface and within the Application plane. It is associated
with an abstraction of location, such as IP addresses and DNS names, with an abstraction of location, such as IP addresses and DNS names,
to identify the end systems and eventually specify intermediate to identify the end systems and eventually specify intermediate
nodes. nodes.
4.2.2. The Controller Plane 4.4.2. The Controller Plane
The Controller Plane corresponds to the aggregation of the Control The Controller Plane corresponds to the aggregation of the Control
and Management Planes in [RFC7426], though Common Control and and Management Planes in [RFC7426], though Common Control and
Measurement Plane (CCAMP) [CCAMP] makes an additional distinction Measurement Plane (CCAMP) [CCAMP] makes an additional distinction
between management and measurement. When the logical separation of between management and measurement. When the logical separation of
the Control, Measurement and other Management entities is not the Control, Measurement and other Management entities is not
relevant, the term Controller Plane is used for simplicity to relevant, the term Controller Plane is used for simplicity to
represent them all, and the term controller refers to any device represent them all, and the term controller refers to any device
operating in that plane, whether is it a Path Computation entity or a operating in that plane, whether is it a Path Computation entity or a
Network Management entity (NME). The Path Computation Element (PCE) Network Management entity (NME). The Path Computation Element (PCE)
skipping to change at page 17, line 15 skipping to change at page 24, line 33
One or more PCE(s) collaborate to implement the requests from the FME One or more PCE(s) collaborate to implement the requests from the FME
as Per-Flow Per-Hop Behaviors installed in the intermediate nodes for as Per-Flow Per-Hop Behaviors installed in the intermediate nodes for
each individual flow. The PCEs place each flow along a deterministic each individual flow. The PCEs place each flow along a deterministic
sequence of intermediate nodes so as to respect per-flow constraints sequence of intermediate nodes so as to respect per-flow constraints
such as security and latency, and optimize the overall result for such as security and latency, and optimize the overall result for
metrics such as an abstract aggregated cost. The deterministic metrics such as an abstract aggregated cost. The deterministic
sequence can typically be more complex than a direct sequence and sequence can typically be more complex than a direct sequence and
include redundancy path, with one or more packet replication and include redundancy path, with one or more packet replication and
elimination points. elimination points.
4.2.3. The Network Plane 4.4.3. The Network Plane
The Network Plane represents the network devices and protocols as a The Network Plane represents the network devices and protocols as a
whole, regardless of the Layer at which the network devices operate. whole, regardless of the Layer at which the network devices operate.
It includes Forwarding Plane (data plane), Application, and It includes Forwarding Plane (data plane), Application, and
Operational Plane (control plane) aspects. Operational Plane (control plane) aspects.
The network Plane comprises the Network Interface Cards (NIC) in the The network Plane comprises the Network Interface Cards (NIC) in the
end systems, which are typically IP hosts, and intermediate nodes, end systems, which are typically IP hosts, and intermediate nodes,
which are typically IP routers and switches. Network-to-Network which are typically IP routers and switches. Network-to-Network
Interfaces such as used for Traffic Engineering path reservation in Interfaces such as used for Traffic Engineering path reservation in
skipping to change at page 18, line 22 skipping to change at page 25, line 22
PCE PCE PCE PCE PCE PCE PCE PCE
-+-+-+-+-+-+-+ Southbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+-+-+-+-+-+-+ Southbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
intermediate intermed. intermed. intermed. intermediate intermed. intermed. intermed.
Node Node Node Node Node Node Node Node
NIC NIC NIC NIC
intermediate intermed. intermed. intermed. intermediate intermed. intermed. intermed.
Node Node Node Node Node Node Node Node
Figure 4 Figure 7
The intermediate nodes (and eventually the end systems NIC) expose The intermediate nodes (and eventually the end systems NIC) expose
their capabilities and physical resources to the controller (the their capabilities and physical resources to the controller (the
PCE), and update the PCE with their dynamic perception of the PCE), and update the PCE with their dynamic perception of the
topology, across the Southbound Interface. In return, the PCE(s) set topology, across the Southbound Interface. In return, the PCE(s) set
the per-flow paths up, providing a Flow Characterization that is more the per-flow paths up, providing a Flow Characterization that is more
tightly coupled to the intermediate node Operation than a TSpec. tightly coupled to the intermediate node Operation than a TSpec.
At the Network plane, intermediate nodes may exchange information At the Network plane, intermediate nodes may exchange information
regarding the state of the paths, between adjacent systems and regarding the state of the paths, between adjacent systems and
eventually with the end systems, and forward packets within eventually with the end systems, and forward packets within
constraints associated to each flow, or, when unable to do so, constraints associated to each flow, or, when unable to do so,
perform a last resort operation such as drop or declassify. perform a last resort operation such as drop or declassify.
This specification focuses on the Southbound interface and the This specification focuses on the Southbound interface and the
operation of the Network Plane. operation of the Network Plane.
4.3. DetNet flows 4.5. Queuing, Shaping, Scheduling, and Preemption
4.3.1. DetNet flow types
A DetNet flow can have different formats during while it is
transported between the peer end systems. Therefore, the following
possible types / formats of a DetNet flow are distinguished in this
document:
o App-flow: native format of a DetNet flow. It does not contain any
DetNet related attributes.
o DetNet-t-flow: specific format of a DetNet flow. Only requires
the congestion / latency features provided by the Detnet transport
layer.
o DetNet-s-flow: specific format of a DetNet flow. Only requires
the replication/elimination feature ensured by the DetNet service
layer.
o DetNet-st-flow: specific format of a DetNet flow. It requires
both DetNet Service and Transport layer functions during
forwarding.
4.3.2. Source guarantees
For the purposes of congestion protection, DetNet flows can be
synchronous or asynchronous. In synchronous DetNet flows, at least
the intermediate nodes (and possibly the end systems) are closely
time synchronized, typically to better than 1 microsecond. By
transmitting packets from different DetNet flows or classes of DetNet
flows at different times, using repeating schedules synchronized
among the intermediate nodes, resources such as buffers and link
bandwidth can be shared over the time domain among different DetNet
flows. There is a tradeoff among techniques for synchronous DetNet
flows between the burden of fine-grained scheduling and the benefit
of reducing the required resources, especially buffer space.
In contrast, asynchronous DetNet flows are not coordinated with a
fine-grained schedule, so relay and end systems must assume worst-
case interference among DetNet flows contending for buffer resources.
Asynchronous DetNet flows are characterized by:
o A maximum packet size;
o An observation interval; and
o A maximum number of transmissions during that observation
interval.
These parameters, together with knowledge of the protocol stack used
(and thus the size of the various headers added to a packet), limit
the number of bit times per observation interval that the DetNet flow
can occupy the physical medium.
The source promises that these limits will not be exceeded. If the
source transmits less data than this limit allows, the unused
resources such as link bandwidth can be made available by the system
to non-DetNet packets. However, making those resources available to
DetNet packets in other DetNet flows would serve no purpose. Those
other DetNet flows have their own dedicated resources, on the
assumption that all DetNet flows can use all of their resources over
a long period of time.
Note that there is no provision in DetNet for throttling DetNet flows
(reducing the transmission rate via feedback); the assumption is that
a DetNet flow, to be useful, must be delivered in its entirety. That
is, while any useful application is written to expect a certain
number of lost packets, the real-time applications of interest to
DetNet demand that the loss of data due to the network is
extraordinarily infrequent.
Although DetNet strives to minimize the changes required of an
application to allow it to shift from a special-purpose digital
network to an Internet Protocol network, one fundamental shift in the
behavior of network applications is impossible to avoid: the
reservation of resources before the application starts. In the first
place, a network cannot deliver finite latency and practically zero
packet loss to an arbitrarily high offered load. Secondly, achieving
practically zero packet loss for unthrottled (though bandwidth
limited) DetNet flows means that bridges and routers have to dedicate
buffer resources to specific DetNet flows or to classes of DetNet
flows. The requirements of each reservation have to be translated
into the parameters that control each system's queuing, shaping, and
scheduling functions and delivered to the hosts, bridges, and
routers.
4.3.3. Incomplete Networks
The presence in the network of transit nodes or subnets that are not
fully capable of offering DetNet services complicates the ability of
the intermediate nodes and/or controller to allocate resources, as
extra buffering, and thus extra latency, must be allocated at points
downstream from the non-DetNet intermediate node for a DetNet flow.
4.4. Queuing, Shaping, Scheduling, and Preemption
DetNet achieves congestion protection and bounded delivery latency by DetNet achieves congestion protection and bounded delivery latency by
reserving bandwidth and buffer resources at every hop along the path reserving bandwidth and buffer resources at every hop along the path
of the DetNet flow. The reservation itself is not sufficient, of the DetNet flow. The reservation itself is not sufficient,
however. Implementors and users of a number of proprietary and however. Implementors and users of a number of proprietary and
standard real-time networks have found that standards for specific standard real-time networks have found that standards for specific
data plane techniques are required to enable these assurances to be data plane techniques are required to enable these assurances to be
made in a multi-vendor network. The fundamental reason is that made in a multi-vendor network. The fundamental reason is that
latency variation in one system results in the need for extra buffer latency variation in one system results in the need for extra buffer
space in the next-hop system(s), which in turn, increases the worst- space in the next-hop system(s), which in turn, increases the worst-
skipping to change at page 21, line 33 skipping to change at page 26, line 33
o Pre-emption of an Ethernet packet in transmission by a packet with o Pre-emption of an Ethernet packet in transmission by a packet with
a more stringent latency requirement, followed by the resumption a more stringent latency requirement, followed by the resumption
of the preempted packet [IEEE802.1Qbu], [IEEE802.3br]. of the preempted packet [IEEE802.1Qbu], [IEEE802.3br].
While these techniques are currently embedded in Ethernet and While these techniques are currently embedded in Ethernet and
bridging standards, we can note that they are all, except perhaps for bridging standards, we can note that they are all, except perhaps for
packet preemption, equally applicable to other media than Ethernet, packet preemption, equally applicable to other media than Ethernet,
and to routers as well as bridges. and to routers as well as bridges.
4.5. Service instance 4.6. Service instance
[Note: Service instance represents all the functions required on a [Note: Service instance represents all the functions required on a
node to allow the end-to-end service between the UNIs.] node to allow the end-to-end service between the UNIs.]
The DetNet network reference model is shown in Figure 5 for a DetNet- The DetNet network reference model is shown in Figure 8 for a DetNet-
Service scenario (i.e. between two DetNet-UNIs). In this figure, the Service scenario (i.e. between two DetNet-UNIs). In this figure, the
end systems ("A" and "B") are connected directly to the edge nodes of end systems ("A" and "B") are connected directly to the edge nodes of
the IP/MPLS network ("PE1" and "PE2"). End-systems participating the IP/MPLS network ("PE1" and "PE2"). End-systems participating
DetNet communication may require connectivity before setting up an DetNet communication may require connectivity before setting up an
App-flow that requires the DetNet service. Such a connectivity App-flow that requires the DetNet service. Such a connectivity
related service instance and the one dedicated for DetNet service related service instance and the one dedicated for DetNet service
share the same access. Packets belonging to a DetNet flow are share the same access. Packets belonging to a DetNet flow are
selected by a filter configured on the access ("F1" and "F2"). As a selected by a filter configured on the access ("F1" and "F2"). As a
result, data flow specific access ("access-A + F1" and "access-B + result, data flow specific access ("access-A + F1" and "access-B +
F2") are terminated in the flow specific service instance ("SI-1" and F2") are terminated in the flow specific service instance ("SI-1" and
skipping to change at page 22, line 26 skipping to change at page 27, line 26
+---------+ ___ _ +---------+ +---------+ ___ _ +---------+
End system | +----+ | / \/ \_ | +----+ | End system End system | +----+ | / \/ \_ | +----+ | End system
"A" -------F1+ | | / \ | | +F2----- "B" "A" -------F1+ | | / \ | | +F2----- "B"
| | +==========+ IP/MPLS +========+ | | | | +==========+ IP/MPLS +========+ | |
| |SI-1| | \__ Net._/ | |SI-2| | | |SI-1| | \__ Net._/ | |SI-2| |
| +----+ | \____/ | +----+ | | +----+ | \____/ | +----+ |
|PE1 | | PE2| |PE1 | | PE2|
+---------+ +---------+ +---------+ +---------+
Figure 5: DetNet network reference model Figure 8: DetNet network reference model
[Note: The tunnel between the service instances may have some special [Note: The tunnel between the service instances may have some special
characteristics. For example, in case of a "packet PW" based tunnel, characteristics. For example, in case of a "packet PW" based tunnel,
there are differences in the usage of the packet PW for DetNet there are differences in the usage of the packet PW for DetNet
traffic compared to the network model described in [RFC6658]. In the traffic compared to the network model described in [RFC6658]. In the
DetNet scenario, the packet PW is used exclusively by the DetNet DetNet scenario, the packet PW is used exclusively by the DetNet
flow, whereas [RFC6658] states: "The packet PW appears as a single flow, whereas [RFC6658] states: "The packet PW appears as a single
point-to-point link to the client layer. Network-layer adjacency point-to-point link to the client layer. Network-layer adjacency
formation and maintenance between the client equipments will follow formation and maintenance between the client equipments will follow
the normal practice needed to support the required relationship in the normal practice needed to support the required relationship in
the client layer ... This packet pseudowire is used to transport all the client layer ... This packet pseudowire is used to transport all
of the required layer 2 and layer 3 protocols between LSR1 and of the required layer 2 and layer 3 protocols between LSR1 and
LSR2".] LSR2".]
[Note: Examples are provided in Annex 1 of [Note: Examples are provided in Annex 1 of
[I-D.varga-detnet-service-model].] [I-D.varga-detnet-service-model].]
4.6. Coexistence with normal traffic 4.7. Flow identification at technology borders
A DetNet network supports the dedication of a high proportion (e.g.
75%) of the network bandwidth to DetNet flows. But, no matter how
much is dedicated for DetNet flows, it is a goal of DetNet to coexist
with existing Class of Service schemes (e.g., DiffServ). It is also
important that non-DetNet traffic not disrupt the DetNet flow, of
course (see Section 4.7 and Section 7). For these reasons:
o Bandwidth (transmission opportunities) not utilized by a DetNet
flow are available to non-DetNet packets (though not to other
DetNet flows).
o DetNet flows can be shaped or scheduled, in order to ensure that
the highest-priority non-DetNet packet also is ensured a worst-
case latency (at any given hop).
o When transmission opportunities for DetNet flows are scheduled in
detail, then the algorithm constructing the schedule should leave
sufficient opportunities for non-DetNet packets to satisfy the
needs of the users of the network. Detailed scheduling can also
permit the time-shared use of buffer resources by different DetNet
flows.
Ideally, the net effect of the presence of DetNet flows in a network
on the non-DetNet packets is primarily a reduction in the available
bandwidth.
4.7. Fault Mitigation
One key to building robust real-time systems is to reduce the
infinite variety of possible failures to a number that can be
analyzed with reasonable confidence. DetNet aids in the process by
providing filters and policers to detect DetNet packets received on
the wrong interface, or at the wrong time, or in too great a volume,
and to then take actions such as discarding the offending packet,
shutting down the offending DetNet flow, or shutting down the
offending interface.
It is also essential that filters and service remarking be employed
at the network edge to prevent non-DetNet packets from being mistaken
for DetNet packets, and thus impinging on the resources allocated to
DetNet packets.
There exist techniques, at present and/or in various stages of
standardization, that can perform these fault mitigation tasks that
deliver a high probability that misbehaving systems will have zero
impact on well-behaved DetNet flows, except of course, for the
receiving interface(s) immediately downstream of the misbehaving
device. Examples of such techniques include traffic policing
functions (e.g. [RFC2475]) and separating flows into per-flow rate-
limited queues.
4.8. Representative Protocol Stack Model
Figure 6 illustrates a conceptual DetNet data plane layering model.
One may compare it to that in [IEEE802.1CB], Annex C, a work in
progress.
DetNet data plane protocol stack
| packets going | ^ packets coming ^
v down the stack v | up the stack |
+----------------------+ +-----------------------+
| Source | | Destination |
+----------------------+ +-----------------------+
| Service layer | | Service layer |
| Packet sequencing | | Duplicate elimination |
| Flow duplication | | Flow merging |
| Packet encoding | | Packet decoding |
+----------------------+ +-----------------------+
| Transport layer | | Transport layer |
| Congestion prot. | | Congestion prot. |
+----------------------+ +-----------------------+
| Lower layers | | Lower layers |
+----------------------+ +-----------------------+
v ^
\_________________________/
Figure 6
Not all layers are required for any given application, or even for
any given network. The layers are, from top to bottom:
Application
Shown as "source" and "destination" in the diagram.
OAM
Operations, Administration, and Maintenance leverages in-band
and out-of-and signaling that validates whether the service
is effectively obtained within QoS constraints. OAM is not
shown in Figure 6; it may reside in any number of the layers.
OAM can involve specific tagging added in the packets for
tracing implementation or network configuration errors;
traceability enables to find whether a packet is a replica,
which relay node performed the replication, and which segment
was intended for the replica.
Packet sequencing
As part of DetNet service protection, supplies the sequence
number for packet replication and elimination (Section 3.4).
Peers with Duplicate elimination. This layer is not needed
if a higher-layer transport protocol is expected to perform
any packet sequencing and duplicate elimination required by
the DetNet flow duplication.
Duplicate elimination
As part of the DetNet service layer, based on the sequenced
number supplied by its peer, packet sequencing, Duplicate
elimination discards any duplicate packets generated by
DetNet flow duplication. It can operate on member flows,
compound flows, or both. The duplication may also be
inferred from other information such as the precise time of
reception in a scheduled network. The duplicate elimination
layer may also perform resequencing of packets to restore
packet order in a flow that was disrupted by the loss of
packets on one or another of the multiple paths taken.
Flow duplication
As part of DetNet service protection, replicates packets that
belong to a DetNet compound flow into two or more DetNet
member flows. Note that this function is separate from
packet sequencing. Flow duplication can be an explicit
duplication and remarking of packets, or can be performed by,
for example, techniques similar to ordinary multicast
replication. Peers with DetNet flow merging.
Network flow merging
As part of DetNet service protection, merges DetNet member
flows together for packets coming up the stack belonging to a
specific DetNet compound flow. Peers with DetNet flow
duplication. DetNet flow merging, together with packet
sequencing, duplicate elimination, and DetNet flow
duplication, performs packet replication and elimination
(Section 3.4).
Packet encoding
As part of DetNet service protection, as an alternative to
packet sequencing and flow duplication, packet encoding
combines the information in multiple DetNet packets, perhaps
from different DetNet compound flows, and transmits that
information in packets on different DetNet member Flows.
Peers with Packet decoding.
Packet decoding
As part of DetNet service protection, as an alternative to
flow merging and duplicate elimination, packet decoding takes
packets from different DetNet member flows, and computes from
those packets the original DetNet packets from the compound
flows input to packet encoding. Peers with Packet encoding.
Congestio protection
The DetNet transport layer provides congestion protection.
See Section 4.4. The actual queuing and shaping mechanisms
are typically provided by underlying subnet layers, but since
these are can be closely associated with the means of
providing paths for DetNet flows (e.g. MPLS LSPs or {VLAN,
multicast destination MAC address} pairs), the path and the
congestion protection are conflated in this figure.
Note that the packet sequencing and duplication elimination functions
at the source and destination ends of a DetNet compound flow may be
performed either in the end system or in a DetNet edge node. The
reader must not confuse a DetNet edge function with other kinds of
edge functions, e.g. an Label Edge Router, although the two functions
may be performed together. The DetNet edge function is concerned
with sequencing packets belonging to DetNet flows. The LER with
encapsulating/decapsulating packets for transport, and is considered
part of the network underlying the DetNet transport layer.
4.9. Flow identification at technology borders
4.9.1. Exporting flow identification 4.7.1. Exporting flow identification
An interesting feature of DetNet, and one that invites An interesting feature of DetNet, and one that invites
implementations that can be accused of "layering violations", is the implementations that can be accused of "layering violations", is the
need for lower layers to be aware of specific flows at higher layers, need for lower layers to be aware of specific flows at higher layers,
in order to provide specific queuing and shaping services for in order to provide specific queuing and shaping services for
specific flows. For example: specific flows. For example:
o A non-IP, strictly L2 source end system X may be sending multiple o A non-IP, strictly L2 source end system X may be sending multiple
flows to the same L2 destination end system Y. Those flows may flows to the same L2 destination end system Y. Those flows may
include DetNet flows with different QoS requirements, and may include DetNet flows with different QoS requirements, and may
skipping to change at page 27, line 43 skipping to change at page 29, line 14
be confused with DetNet compound vs. member flows.) Of course, this be confused with DetNet compound vs. member flows.) Of course, this
requires that the aggregate DetNet flow be provisioned properly to requires that the aggregate DetNet flow be provisioned properly to
carry the sub-flows. carry the sub-flows.
Thus, rather than packet inspection, there is the option to export Thus, rather than packet inspection, there is the option to export
higher-layer information to the lower layer. The requirement to higher-layer information to the lower layer. The requirement to
support one or the other method for flow identification (or both) is support one or the other method for flow identification (or both) is
the essential complexity that DetNet brings to existing control plane the essential complexity that DetNet brings to existing control plane
models. models.
4.9.2. Flow attribute mapping between layers 4.7.2. Flow attribute mapping between layers
Transport of DetNet flows over multiple technology domains may Transport of DetNet flows over multiple technology domains may
require that lower layers are aware of specific flows of higher require that lower layers are aware of specific flows of higher
layers. Such an "exporting of flow identification" is needed each layers. Such an "exporting of flow identification" is needed each
time when the forwarding paradigm is changed on the transport path time when the forwarding paradigm is changed on the transport path
(e.g., two LSRs are interconnected by a L2 bridged domain, etc.). (e.g., two LSRs are interconnected by a L2 bridged domain, etc.).
The three main forwarding methods considered for deterministic The three main forwarding methods considered for deterministic
networking are: networking are:
o IP routing o IP routing
skipping to change at page 28, line 17 skipping to change at page 29, line 36
o MPLS label switching o MPLS label switching
o Ethernet bridging o Ethernet bridging
Note: at the time of this publication, the exact format of flow Note: at the time of this publication, the exact format of flow
identification is still WIP. identification is still WIP.
[Note: Seq-num attribute may require a similar functionality at [Note: Seq-num attribute may require a similar functionality at
technology border nodes.] technology border nodes.]
add/remove add/remove add/remove add/remove
Eth Flow-ID IP Flow-ID Eth Flow-ID IP Flow-ID
| | | |
v v v v
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| | | | | | | | | |
| Eth | MPLS | IP | Application data | | Eth | MPLS | IP | Application data |
| | | | | | | | | |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
^ ^
| |
add/remove add/remove
MPLS Flow-ID MPLS Flow-ID
Figure 7: Packet with multiple Flow-IDs Figure 9: Packet with multiple Flow-IDs
The additional (domain specific) Flow-ID can be The additional (domain specific) Flow-ID can be
o created by a domain specific function or o created by a domain specific function or
o derived from the Flow-ID added to the App-flow, o derived from the Flow-ID added to the App-flow,
so that it must be unique inside the given domain. Note, that the so that it must be unique inside the given domain. Note, that the
Flow-ID added to the App-flow is still present in the packet, but Flow-ID added to the App-flow is still present in the packet, but
transport nodes may lack the function to recognize it; that's why the transport nodes may lack the function to recognize it; that's why the
additional Flow-ID is added (pushed). additional Flow-ID is added (pushed).
4.9.3. Flow-ID mapping examples 4.7.3. Flow-ID mapping examples
IP nodes and MPLS nodes are assumed to be configured to push such an IP nodes and MPLS nodes are assumed to be configured to push such an
additional (domain specific) Flow-ID when sending traffic to an additional (domain specific) Flow-ID when sending traffic to an
Ethernet switch (as shown in the examples below). Ethernet switch (as shown in the examples below).
Figure 8 shows a scenario where an IP end system ("IP-A") is Figure 10 shows a scenario where an IP end system ("IP-A") is
connected via two Ethernet switches ("ETH-n") to an IP router ("IP- connected via two Ethernet switches ("ETH-n") to an IP router ("IP-
1"). 1").
IP domain IP domain
<----------------------------------------------- <-----------------------------------------------
+======+ +======+ +======+ +======+
|L3-ID | |L3-ID | |L3-ID | |L3-ID |
+======+ /\ +-----+ +======+ +======+ /\ +-----+ +======+
/ \ Forward as | | / \ Forward as | |
skipping to change at page 29, line 33 skipping to change at page 30, line 50
.L3-ID . +-----+ +-----+ |L3-ID | .L3-ID . +-----+ +-----+ |L3-ID |
+======+ +......+ +======+ +======+ +......+ +======+
|ETH-ID| .L3-ID . |ETH-ID| |ETH-ID| .L3-ID . |ETH-ID|
+======+ +======+ +------+ +======+ +======+ +------+
|ETH-ID| |ETH-ID|
+======+ +======+
Ethernet domain Ethernet domain
<----------------> <---------------->
Figure 8: IP nodes interconnected by an Ethernet domain Figure 10: IP nodes interconnected by an Ethernet domain
End system "IP-A" uses the original App-flow specific ID ("L3-ID"), End system "IP-A" uses the original App-flow specific ID ("L3-ID"),
but as it is connected to an Ethernet domain it has to push an but as it is connected to an Ethernet domain it has to push an
Ethernet-domain specific flow-ID ("VID + multicast MAC address", Ethernet-domain specific flow-ID ("VID + multicast MAC address",
referred as "ETH-ID") before sending the packet to "ETH-1" node. referred as "ETH-ID") before sending the packet to "ETH-1" node.
Ethernet switch "ETH-1" can recognize the data flow based on the Ethernet switch "ETH-1" can recognize the data flow based on the
"ETH-ID" and it does forwarding toward "ETH-2". "ETH-2" switches the "ETH-ID" and it does forwarding toward "ETH-2". "ETH-2" switches the
packet toward the IP router. "IP-1" must be configured to receive packet toward the IP router. "IP-1" must be configured to receive
the Ethernet Flow-ID specific multicast stream, but (as it is an L3 the Ethernet Flow-ID specific multicast stream, but (as it is an L3
node) it decodes the data flow ID based on the "L3-ID" fields of the node) it decodes the data flow ID based on the "L3-ID" fields of the
received packet. received packet.
Figure 9 shows a scenario where MPLS domain nodes ("PE-n" and "P-m") Figure 11 shows a scenario where MPLS domain nodes ("PE-n" and "P-m")
are connected via two Ethernet switches ("ETH-n"). are connected via two Ethernet switches ("ETH-n").
MPLS domain MPLS domain
<-----------------------------------------------> <----------------------------------------------->
+=======+ +=======+ +=======+ +=======+
|MPLS-ID| |MPLS-ID| |MPLS-ID| |MPLS-ID|
+=======+ +-----+ +-----+ +=======+ +-----+ +=======+ +-----+ +-----+ +=======+ +-----+
| | Forward as | | | | | | Forward as | | | |
|PE-1 | per ETH-ID | P-2 +-----------+ PE-2| |PE-1 | per ETH-ID | P-2 +-----------+ PE-2|
skipping to change at page 30, line 29 skipping to change at page 31, line 43
.MPLS-ID. +-----+ +-----+ |MPLS-ID| .MPLS-ID. +-----+ +-----+ |MPLS-ID|
+=======+ +=======+ +=======+ +=======+
|ETH-ID | +.......+ |ETH-ID | |ETH-ID | +.......+ |ETH-ID |
+=======+ .MPLS-ID. +-------+ +=======+ .MPLS-ID. +-------+
+=======+ +=======+
|ETH-ID | |ETH-ID |
+=======+ +=======+
Ethernet domain Ethernet domain
<----------------> <---------------->
Figure 9: MPLS nodes interconnected by an Ethernet domain Figure 11: MPLS nodes interconnected by an Ethernet domain
"PE-1" uses the MPLS specific ID ("MPLS-ID"), but as it is connected "PE-1" uses the MPLS specific ID ("MPLS-ID"), but as it is connected
to an Ethernet domain it has to push an Ethernet-domain specific to an Ethernet domain it has to push an Ethernet-domain specific
flow-ID ("VID + multicast MAC address", referred as "ETH-ID") before flow-ID ("VID + multicast MAC address", referred as "ETH-ID") before
sending the packet to "ETH-1". Ethernet switch "ETH-1" can recognize sending the packet to "ETH-1". Ethernet switch "ETH-1" can recognize
the data flow based on the "ETH-ID" and it does forwarding toward the data flow based on the "ETH-ID" and it does forwarding toward
"ETH-2". "ETH-2" switches the packet toward the MPLS node ("P-2"). "ETH-2". "ETH-2" switches the packet toward the MPLS node ("P-2").
"P-2" must be configured to receive the Ethernet Flow-ID specific "P-2" must be configured to receive the Ethernet Flow-ID specific
multicast stream, but (as it is an MPLS node) it decodes the data multicast stream, but (as it is an MPLS node) it decodes the data
flow ID based on the "MPLS-ID" fields of the received packet. flow ID based on the "MPLS-ID" fields of the received packet.
4.10. Advertising resources, capabilities and adjacencies 4.8. Advertising resources, capabilities and adjacencies
There are three classes of information that a central controller or There are three classes of information that a central controller or
decentralized control plane needs to know that can only be obtained decentralized control plane needs to know that can only be obtained
from the end systems and/or transit nodes in the network. When using from the end systems and/or transit nodes in the network. When using
a peer-to-peer control plane, some of this information may be a peer-to-peer control plane, some of this information may be
required by a system's neighbors in the network. required by a system's neighbors in the network.
o Details of the system's capabilities that are required in order to o Details of the system's capabilities that are required in order to
accurately allocate that system's resources, as well as other accurately allocate that system's resources, as well as other
systems' resources. This includes, for example, which specific systems' resources. This includes, for example, which specific
queuing and shaping algorithms are implemented (Section 4.4), the queuing and shaping algorithms are implemented (Section 4.5), the
number of buffers dedicated for DetNet allocation, and the worst- number of buffers dedicated for DetNet allocation, and the worst-
case forwarding delay. case forwarding delay.
o The dynamic state of an end or transit node's DetNet resources. o The dynamic state of an end or transit node's DetNet resources.
o The identity of the system's neighbors, and the characteristics of o The identity of the system's neighbors, and the characteristics of
the link(s) between the systems, including the length (in the link(s) between the systems, including the length (in
nanoseconds) of the link(s). nanoseconds) of the link(s).
4.11. Provisioning model 4.9. Provisioning model
4.11.1. Centralized Path Computation and Installation 4.9.1. Centralized Path Computation and Installation
A centralized routing model, such as provided with a PCE (RFC 4655 A centralized routing model, such as provided with a PCE (RFC 4655
[RFC4655]), enables global and per-flow optimizations. (See [RFC4655]), enables global and per-flow optimizations. (See
Section 4.2.) The model is attractive but a number of issues are Section 4.4.) The model is attractive but a number of issues are
left to be solved. In particular: 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. end of the path.
4.11.2. Distributed Path Setup 4.9.2. Distributed Path Setup
Significant work on distributed path setup can be leveraged from MPLS Significant work on distributed path setup can be leveraged from MPLS
Traffic Engineering, in both its GMPLS and non-GMPLS forms. The Traffic Engineering, in both its GMPLS and non-GMPLS forms. The
protocols within scope are Resource ReSerVation Protocol [RFC3209] protocols within scope are Resource ReSerVation Protocol [RFC3209]
[RFC3473](RSVP-TE), OSPF-TE [RFC4203] [RFC5392] and ISIS-TE [RFC5307] [RFC3473](RSVP-TE), OSPF-TE [RFC4203] [RFC5392] and ISIS-TE [RFC5307]
[RFC5316]. These should be viewed as starting points as there are [RFC5316]. These should be viewed as starting points as there are
feature specific extensions defined that may be applicable to DetNet. feature specific extensions defined that may be applicable to DetNet.
In a Layer-2 only environment, or as part of a layered approach to a In a Layer-2 only environment, or as part of a layered approach to a
mixed environment, IEEE 802.1 also has work, either completed or in mixed environment, IEEE 802.1 also has work, either completed or in
progress. [IEEE802.1Q-2014] Clause 35 describes SRP, a peer-to-peer progress. [IEEE802.1Q-2014] Clause 35 describes SRP, a peer-to-peer
protocol for Layer-2 roughly analogous to RSVP [RFC2205]. protocol for Layer-2 roughly analogous to RSVP [RFC2205].
[IEEE802.1Qca] defines how ISIS can provide multiple disjoint paths [IEEE802.1Qca] defines how ISIS can provide multiple disjoint paths
or distribution trees. Also in progress is [IEEE802.1Qcc], which or distribution trees. Also in progress is [IEEE802.1Qcc], which
expands the capabilities of SRP. expands the capabilities of SRP.
skipping to change at page 32, line 5 skipping to change at page 33, line 20
progress. [IEEE802.1Q-2014] Clause 35 describes SRP, a peer-to-peer progress. [IEEE802.1Q-2014] Clause 35 describes SRP, a peer-to-peer
protocol for Layer-2 roughly analogous to RSVP [RFC2205]. protocol for Layer-2 roughly analogous to RSVP [RFC2205].
[IEEE802.1Qca] defines how ISIS can provide multiple disjoint paths [IEEE802.1Qca] defines how ISIS can provide multiple disjoint paths
or distribution trees. Also in progress is [IEEE802.1Qcc], which or distribution trees. Also in progress is [IEEE802.1Qcc], which
expands the capabilities of SRP. expands the capabilities of SRP.
The integration/interaction of the DetNet control layer with an The integration/interaction of the DetNet control layer with an
underlying IEEE 802.1 sub-network control layer will need to be underlying IEEE 802.1 sub-network control layer will need to be
defined. defined.
4.12. Scaling to larger networks 4.10. Scaling to larger networks
Reservations for individual DetNet flows require considerable state Reservations for individual DetNet flows require considerable state
information in each transit node, especially when adequate fault information in each transit node, especially when adequate fault
mitigation (Section 4.7) is required. The DetNet data plane, in mitigation (Section 3.3.2) is required. The DetNet data plane, in
order to support larger numbers of DetNet flows, must support the order to support larger numbers of DetNet flows, must support the
aggregation of DetNet flows into tunnels, which themselves can be aggregation of DetNet flows into tunnels, which themselves can be
viewed by the transit nodes' data planes largely as individual DetNet viewed by the transit nodes' data planes largely as individual DetNet
flows. Without such aggregation, the per-relay system may limit the flows. Without such aggregation, the per-relay system may limit the
scale of DetNet networks. scale of DetNet networks.
4.13. Connected islands vs. networks 4.11. Connected islands vs. networks
Given that users have deployed examples of the IEEE 802.1 TSN TG Given that users have deployed examples of the IEEE 802.1 TSN TG
standards, which provide capabilities similar to DetNet, it is standards, which provide capabilities similar to DetNet, it is
obvious to ask whether the IETF DetNet effort can be limited to obvious to ask whether the IETF DetNet effort can be limited to
providing Layer-2 connections (VPNs) between islands of bridged TSN providing Layer-2 connections (VPNs) between islands of bridged TSN
networks. While this capability is certainly useful to some networks. While this capability is certainly useful to some
applications, and must not be precluded by DetNet, tunneling alone is applications, and must not be precluded by DetNet, tunneling alone is
not a sufficient goal for the DetNet WG. As shown in the not a sufficient goal for the DetNet WG. As shown in the
Deterministic Networking Use Cases draft [I-D.ietf-detnet-use-cases], Deterministic Networking Use Cases draft [I-D.ietf-detnet-use-cases],
there are already deployments of Layer-2 TSN networks that are there are already deployments of Layer-2 TSN networks that are
encountering the well-known problems of over-large broadcast domains. encountering the well-known problems of over-large broadcast domains.
Routed solutions, and combinations routed/bridged solutions, are both Routed solutions, and combinations routed/bridged solutions, are both
required. required.
5. Compatibility with Layer-2 4.12. Compatibility with Layer-2
Standards providing similar capabilities for bridged networks (only) Standards providing similar capabilities for bridged networks (only)
have been and are being generated in the IEEE 802 LAN/MAN Standards have been and are being generated in the IEEE 802 LAN/MAN Standards
Committee. The present architecture describes an abstract model that Committee. The present architecture describes an abstract model that
can be applicable both at Layer-2 and Layer-3, and over links not can be applicable both at Layer-2 and Layer-3, and over links not
defined by IEEE 802. It is the intention of the authors (and defined by IEEE 802. It is the intention of the authors (and
hopefully, as this draft progresses, of the DetNet Working Group) hopefully, as this draft progresses, of the DetNet Working Group)
that IETF and IEEE 802 will coordinate their work, via the that IETF and IEEE 802 will coordinate their work, via the
participation of common individuals, liaisons, and other means, to participation of common individuals, liaisons, and other means, to
maximize the compatibility of their outputs. maximize the compatibility of their outputs.
DetNet enabled end systems and intermediate nodes can be DetNet enabled end systems and intermediate nodes can be
interconnected by sub-networks, i.e., Layer-2 technologies. These interconnected by sub-networks, i.e., Layer-2 technologies. These
sub-networks will provide DetNet compatible service for support of sub-networks will provide DetNet compatible service for support of
DetNet traffic. Examples of sub-networks include 802.1TSN and a DetNet traffic. Examples of sub-networks include 802.1TSN and a
point-to-point OTN link. Of course, multi-layer DetNet systems may point-to-point OTN link. Of course, multi-layer DetNet systems may
be possible too, where one DetNet appears as a sub-network, and be possible too, where one DetNet appears as a sub-network, and
provides service to, a higher layer DetNet system. provides service to, a higher layer DetNet system.
6. Open Questions 5. Open Questions
There are a number of architectural questions that will have to be There are a number of architectural questions that will have to be
resolved before this document can be submitted for publication. resolved before this document can be submitted for publication.
Aside from the obvious fact that this present draft is subject to Aside from the obvious fact that this present draft is subject to
change, there are specific questions to which the authors wish to change, there are specific questions to which the authors wish to
direct the readers' attention. direct the readers' attention.
6.1. Flat vs. hierarchical control 5.1. Flat vs. hierarchical control
Boxes that are solely routers or solely bridges are rare in today's Boxes that are solely routers or solely bridges are rare in today's
market. In a multi-tenant data center, multiple users' virtual market. In a multi-tenant data center, multiple users' virtual
Layer-2/Layer-3 topologies exist simultaneously, implemented on a Layer-2/Layer-3 topologies exist simultaneously, implemented on a
network whose physical topology bears only accidental resemblance to network whose physical topology bears only accidental resemblance to
the virtual topologies. the virtual topologies.
While the forwarding topology (the bridges and routers) are an While the forwarding topology (the bridges and routers) are an
important consideration for a DetNet Flow Management Entity important consideration for a DetNet Flow Management Entity
(Section 4.2.1), so is the purely physical topology. Ultimately, the (Section 4.4.1), so is the purely physical topology. Ultimately, the
model used by the management entities is based on boxes, queues, and model used by the management entities is based on boxes, queues, and
links. The authors hope that the work of the TEAS WG will help to links. The authors hope that the work of the TEAS WG will help to
clarify exactly what model parameters need to be traded between the clarify exactly what model parameters need to be traded between the
intermediate nodes and the controller(s). intermediate nodes and the controller(s).
6.2. Peer-to-peer reservation protocol 5.2. Peer-to-peer reservation protocol
As described in Section 4.11.2, the DetNet WG needs to decide whether As described in Section 4.9.2, the DetNet WG needs to decide whether
to support a peer-to-peer protocol for a source and a destination to to support a peer-to-peer protocol for a source and a destination to
reserve resources for a DetNet stream. Assuming that enabling the reserve resources for a DetNet stream. Assuming that enabling the
involvement of the source and/or destination is desirable (see involvement of the source and/or destination is desirable (see
Deterministic Networking Use Cases [I-D.ietf-detnet-use-cases]), it Deterministic Networking Use Cases [I-D.ietf-detnet-use-cases]), it
remains to decide whether the DetNet WG will make it possible to remains to decide whether the DetNet WG will make it possible to
deploy at least some DetNet capabilities in a network using only a deploy at least some DetNet capabilities in a network using only a
peer-to-peer protocol, without a central controller. peer-to-peer protocol, without a central controller.
(Note that a UNI (see Section 4.2.3) between an end system and a (Note that a UNI (see Section 4.4.3) between an end system and a
DetNet edge node, for sources and/or listeners to request DetNet DetNet edge node, for sources and/or listeners to request DetNet
services, can be either the first hop of a per-to-peer reservation services, can be either the first hop of a per-to-peer reservation
protocol, or can be deflected by the DetNet edge node to a central protocol, or can be deflected by the DetNet edge node to a central
controller for resolution. Similarly, a decision by a central controller for resolution. Similarly, a decision by a central
controller can be effected by the controller instructing the end controller can be effected by the controller instructing the end
system or DetNet edge node to initiate a per-to-peer protocol system or DetNet edge node to initiate a per-to-peer protocol
activity.) activity.)
6.3. Wireless media interactions 5.3. Wireless media interactions
Deterministic Networking Use Cases [I-D.ietf-detnet-use-cases] Deterministic Networking Use Cases [I-D.ietf-detnet-use-cases]
illustrates cases where wireless media are needed in a DetNet illustrates cases where wireless media are needed in a DetNet
network. Some wireless media in general use, such as IEEE 802.11 network. Some wireless media in general use, such as IEEE 802.11
[IEEE802.1Q-2014], have significantly higher packet loss rates than [IEEE802.1Q-2014], have significantly higher packet loss rates than
typical wired media, such as Ethernet [IEEE802.3-2012]. IEEE 802.11 typical wired media, such as Ethernet [IEEE802.3-2012]. IEEE 802.11
includes support for such features as MAC-layer acknowledgements and includes support for such features as MAC-layer acknowledgements and
retransmissions. retransmissions.
The techniques described in Section 3 are likely to improve the The techniques described in Section 3 are likely to improve the
ability of a mixed wired/wireless network to offer the DetNet QoS ability of a mixed wired/wireless network to offer the DetNet QoS
features. The interaction of these techniques with the features of features. The interaction of these techniques with the features of
specific wireless media, although they may be significant, cannot be specific wireless media, although they may be significant, cannot be
addressed in this document. It remains to be decided to what extent addressed in this document. It remains to be decided to what extent
the DetNet WG will address them, and to what extent other WGs, e.g. the DetNet WG will address them, and to what extent other WGs, e.g.
6TiSCH, will do so. 6TiSCH, will do so.
7. Security Considerations 5.4. Packet encoding for service protection
There are methods for using multiple paths to provide service
protection that involve encoding the information in a packet
belonging to a DetNet flow into multiple transmission units,
typically combining information from multiple packets into any given
transmission unit. Such techniques may be applicable for use as a
DetNet service protection technique, assuming that the DetNet users'
needs for timeliness of delivery and freedom from interference with
misbehaving DetNet flows can be met.
No specific mechanisms are defined here, at this time. This section
will either be enhanced or removed. Contributions are invited.
6. Security Considerations
Security in the context of Deterministic Networking has an added Security in the context of Deterministic Networking has an added
dimension; the time of delivery of a packet can be just as important dimension; the time of delivery of a packet can be just as important
as the contents of the packet, itself. A man-in-the-middle attack, as the contents of the packet, itself. A man-in-the-middle attack,
for example, can impose, and then systematically adjust, additional for example, can impose, and then systematically adjust, additional
delays into a link, and thus disrupt or subvert a real-time delays into a link, and thus disrupt or subvert a real-time
application without having to crack any encryption methods employed. application without having to crack any encryption methods employed.
See [RFC7384] for an exploration of this issue in a related context. See [RFC7384] for an exploration of this issue in a related context.
Furthermore, in a control system where millions of dollars of Furthermore, in a control system where millions of dollars of
equipment, or even human lives, can be lost if the DetNet QoS is not equipment, or even human lives, can be lost if the DetNet QoS is not
delivered, one must consider not only simple equipment failures, delivered, one must consider not only simple equipment failures,
where the box or wire instantly becomes perfectly silent, but bizarre where the box or wire instantly becomes perfectly silent, but bizarre
errors such as can be caused by software failures. Because there is errors such as can be caused by software failures. Because there is
essential no limit to the kinds of failures that can occur, essential no limit to the kinds of failures that can occur,
protecting against realistic equipment failures is indistinguishable, protecting against realistic equipment failures is indistinguishable,
in most cases, from protecting against malicious behavior, whether in most cases, from protecting against malicious behavior, whether
accidental or intentional. See also Section 4.7. accidental or intentional. See also Section 3.3.2.
Security must cover: Security must cover:
o the protection of the signaling protocol o the protection of the signaling protocol
o the authentication and authorization of the controlling systems o the authentication and authorization of the controlling systems
o the identification and shaping of the DetNet flows o the identification and shaping of the DetNet flows
8. Privacy Considerations 7. Privacy Considerations
DetNet is provides a Quality of Service (QoS), and as such, does not DetNet is provides a Quality of Service (QoS), and as such, does not
directly raise any new privacy considerations. directly raise any new privacy considerations.
However, the requirement for every (or almost every) node along the However, the requirement for every (or almost every) node along the
path of a DetNet flow to identify DetNet flows may present an path of a DetNet flow to identify DetNet flows may present an
additional attack surface for privacy, should the DetNet paradigm be additional attack surface for privacy, should the DetNet paradigm be
found useful in broader environments. found useful in broader environments.
9. IANA Considerations 8. IANA Considerations
This document does not require an action from IANA. This document does not require an action from IANA.
10. Acknowledgements 9. Acknowledgements
The authors wish to thank Jouni Korhonen, Erik Nordmark, George The authors wish to thank Jouni Korhonen, Erik Nordmark, George
Swallow, Rudy Klecka, Anca Zamfir, David Black, Thomas Watteyne, Swallow, Rudy Klecka, Anca Zamfir, David Black, Thomas Watteyne,
Shitanshu Shah, Craig Gunther, Rodney Cummings, Balazs Varga, Shitanshu Shah, Craig Gunther, Rodney Cummings, Balazs Varga,
Wilfried Steiner, Marcel Kiessling, Karl Weber, Janos Farkas, Ethan Wilfried Steiner, Marcel Kiessling, Karl Weber, Janos Farkas, Ethan
Grossman, Pat Thaler, Lou Berger, and especially Michael Johas Grossman, Pat Thaler, Lou Berger, and especially Michael Johas
Teener, for their various contribution with this work. Teener, for their various contribution with this work.
11. Access to IEEE 802.1 documents 10. Access to IEEE 802.1 documents
To access password protected IEEE 802.1 drafts, see the IETF IEEE To access password protected IEEE 802.1 drafts, see the IETF IEEE
802.1 information page at https://www.ietf.org/proceedings/52/slides/ 802.1 information page at https://www.ietf.org/proceedings/52/slides/
bridge-0/tsld003.htm. bridge-0/tsld003.htm.
12. Informative References 11. Informative References
[AVnu] http://www.avnu.org/, "The AVnu Alliance tests and [AVnu] http://www.avnu.org/, "The AVnu Alliance tests and
certifies devices for interoperability, providing a simple certifies devices for interoperability, providing a simple
and reliable networking solution for AV network and reliable networking solution for AV network
implementation based on the Audio Video Bridging (AVB) implementation based on the Audio Video Bridging (AVB)
standards.". standards.".
[CCAMP] IETF, "Common Control and Measurement Plane", [CCAMP] IETF, "Common Control and Measurement Plane",
<https://datatracker.ietf.org/doc/charter-ietf-ccamp/>. <https://datatracker.ietf.org/doc/charter-ietf-ccamp/>.
skipping to change at page 36, line 42 skipping to change at page 38, line 16
Finn, N. and P. Thubert, "Deterministic Networking Problem Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", draft-ietf-detnet-problem-statement-01 (work Statement", draft-ietf-detnet-problem-statement-01 (work
in progress), September 2016. in progress), September 2016.
[I-D.ietf-detnet-use-cases] [I-D.ietf-detnet-use-cases]
Grossman, E., Gunther, C., Thubert, P., Wetterwald, P., Grossman, E., Gunther, C., Thubert, P., Wetterwald, P.,
Raymond, J., Korhonen, J., Kaneko, Y., Das, S., Zha, Y., Raymond, J., Korhonen, J., Kaneko, Y., Das, S., Zha, Y.,
Varga, B., Farkas, J., Goetz, F., Schmitt, J., Vilajosana, Varga, B., Farkas, J., Goetz, F., Schmitt, J., Vilajosana,
X., Mahmoodi, T., Spirou, S., and P. Vizarreta, X., Mahmoodi, T., Spirou, S., and P. Vizarreta,
"Deterministic Networking Use Cases", draft-ietf-detnet- "Deterministic Networking Use Cases", draft-ietf-detnet-
use-cases-11 (work in progress), October 2016. use-cases-12 (work in progress), April 2017.
[I-D.ietf-roll-rpl-industrial-applicability] [I-D.ietf-roll-rpl-industrial-applicability]
Phinney, T., Thubert, P., and R. Assimiti, "RPL Phinney, T., Thubert, P., and R. Assimiti, "RPL
applicability in industrial networks", draft-ietf-roll- applicability in industrial networks", draft-ietf-roll-
rpl-industrial-applicability-02 (work in progress), rpl-industrial-applicability-02 (work in progress),
October 2013. October 2013.
[I-D.svshah-tsvwg-deterministic-forwarding] [I-D.svshah-tsvwg-deterministic-forwarding]
Shah, S. and P. Thubert, "Deterministic Forwarding PHB", Shah, S. and P. Thubert, "Deterministic Forwarding PHB",
draft-svshah-tsvwg-deterministic-forwarding-04 (work in draft-svshah-tsvwg-deterministic-forwarding-04 (work in
progress), August 2015. progress), August 2015.
[I-D.varga-detnet-service-model] [I-D.varga-detnet-service-model]
Varga, B. and J. Farkas, "DetNet Service Model", draft- Varga, B. and J. Farkas, "DetNet Service Model", draft-
varga-detnet-service-model-01 (work in progress), October varga-detnet-service-model-02 (work in progress), May
2016. 2017.
[IEEE802.11-2012] [IEEE802.11-2012]
IEEE, "Wireless LAN Medium Access Control (MAC) and IEEE, "Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications", 2012, Physical Layer (PHY) Specifications", 2012,
<http://standards.ieee.org/getieee802/ <http://standards.ieee.org/getieee802/
download/802.11-2012.pdf>. download/802.11-2012.pdf>.
[IEEE802.1AS-2011] [IEEE802.1AS-2011]
IEEE, "Timing and Synchronizations (IEEE 802.1AS-2011)", IEEE, "Timing and Synchronizations (IEEE 802.1AS-2011)",
2011, <http://standards.ieee.org/getIEEE802/ 2011, <http://standards.ieee.org/getIEEE802/
skipping to change at page 39, line 42 skipping to change at page 41, line 11
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,
<http://www.rfc-editor.org/info/rfc3209>. <http://www.rfc-editor.org/info/rfc3209>.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol- Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473, Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003, DOI 10.17487/RFC3473, January 2003,
<http://www.rfc-editor.org/info/rfc3473>. <http://www.rfc-editor.org/info/rfc3473>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>.
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<http://www.rfc-editor.org/info/rfc4203>. <http://www.rfc-editor.org/info/rfc4203>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc4655>. <http://www.rfc-editor.org/info/rfc4655>.
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