draft-ietf-detnet-architecture-13.txt   rfc8655.txt 
DetNet N. Finn Internet Engineering Task Force (IETF) N. Finn
Internet-Draft Huawei Request for Comments: 8655 Huawei
Intended status: Standards Track P. Thubert Category: Standards Track P. Thubert
Expires: November 7, 2019 Cisco ISSN: 2070-1721 Cisco
B. Varga B. Varga
J. Farkas J. Farkas
Ericsson Ericsson
May 6, 2019 October 2019
Deterministic Networking Architecture Deterministic Networking Architecture
draft-ietf-detnet-architecture-13
Abstract Abstract
This document provides the overall architecture for Deterministic This document provides the overall architecture for Deterministic
Networking (DetNet), which provides a capability to carry specified Networking (DetNet), which provides a capability to carry specified
unicast or multicast data flows for real-time applications with unicast or multicast data flows for real-time applications with
extremely low data loss rates and bounded latency within a network extremely low data loss rates and bounded latency within a network
domain. Techniques used include: 1) reserving data plane resources domain. Techniques used include 1) reserving data-plane resources
for individual (or aggregated) DetNet flows in some or all of the for individual (or aggregated) DetNet flows in some or all of the
intermediate nodes along the path of the flow; 2) providing explicit intermediate nodes along the path of the flow, 2) providing explicit
routes for DetNet flows that do not immediately change with the routes for DetNet flows that do not immediately change with the
network topology; and 3) distributing data from DetNet flow packets network topology, and 3) distributing data from DetNet flow packets
over time and/or space to ensure delivery of each packet's data in over time and/or space to ensure delivery of each packet's data in
spite of the loss of a path. DetNet operates at the IP layer and spite of the loss of a path. DetNet operates at the IP layer and
delivers service over lower layer technologies such as MPLS and IEEE delivers service over lower-layer technologies such as MPLS and Time-
802.1 Time-Sensitive Networking (TSN). Sensitive Networking (TSN) as defined by IEEE 802.1.
Status of This Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology
2.1. Terms used in this document . . . . . . . . . . . . . . . 4 2.1. Terms Used in This Document
2.2. IEEE 802.1 TSN to DetNet dictionary . . . . . . . . . . . 7 2.2. Dictionary of Terms Used by TSN and DetNet
3. Providing the DetNet Quality of Service . . . . . . . . . . . 7 3. Providing the DetNet Quality of Service
3.1. Primary goals defining the DetNet QoS . . . . . . . . . . 8 3.1. Primary Goals Defining the DetNet QoS
3.2. Mechanisms to achieve DetNet QoS . . . . . . . . . . . . 10 3.2. Mechanisms to Achieve DetNet QoS
3.2.1. Resource allocation . . . . . . . . . . . . . . . . . 10 3.2.1. Resource Allocation
3.2.1.1. Eliminate contention loss . . . . . . . . . . . . 10 3.2.2. Service Protection
3.2.1.2. Jitter Reduction . . . . . . . . . . . . . . . . 11 3.2.3. Explicit Routes
3.2.2. Service Protection . . . . . . . . . . . . . . . . . 11 3.3. Secondary Goals for DetNet
3.2.2.1. In-Order Delivery . . . . . . . . . . . . . . . . 12 3.3.1. Coexistence with Normal Traffic
3.2.2.2. Packet Replication and Elimination . . . . . . . 12 3.3.2. Fault Mitigation
3.2.2.3. Packet encoding for service protection . . . . . 14 4. DetNet Architecture
3.2.3. Explicit routes . . . . . . . . . . . . . . . . . . . 14 4.1. DetNet Stack Model
3.3. Secondary goals for DetNet . . . . . . . . . . . . . . . 15 4.1.1. Representative Protocol Stack Model
3.3.1. Coexistence with normal traffic . . . . . . . . . . . 15 4.1.2. DetNet Data-Plane Overview
3.3.2. Fault Mitigation . . . . . . . . . . . . . . . . . . 16 4.1.3. Network Reference Model
4. DetNet Architecture . . . . . . . . . . . . . . . . . . . . . 17 4.2. DetNet Systems
4.1. DetNet stack model . . . . . . . . . . . . . . . . . . . 17 4.2.1. End System
4.1.1. Representative Protocol Stack Model . . . . . . . . . 17 4.2.2. DetNet Edge, Relay, and Transit Nodes
4.1.2. DetNet Data Plane Overview . . . . . . . . . . . . . 20 4.3. DetNet Flows
4.1.3. Network reference model . . . . . . . . . . . . . . . 22 4.3.1. DetNet Flow Types
4.2. DetNet systems . . . . . . . . . . . . . . . . . . . . . 23 4.3.2. Source Transmission Behavior
4.2.1. End system . . . . . . . . . . . . . . . . . . . . . 23 4.3.3. Incomplete Networks
4.2.2. DetNet edge, relay, and transit nodes . . . . . . . . 24 4.4. Traffic Engineering for DetNet
4.3. DetNet flows . . . . . . . . . . . . . . . . . . . . . . 25 4.4.1. The Application Plane
4.3.1. DetNet flow types . . . . . . . . . . . . . . . . . . 25 4.4.2. The Controller Plane
4.3.2. Source transmission behavior . . . . . . . . . . . . 25 4.4.3. The Network Plane
4.3.3. Incomplete Networks . . . . . . . . . . . . . . . . . 27 4.5. Queuing, Shaping, Scheduling, and Preemption
4.4. Traffic Engineering for DetNet . . . . . . . . . . . . . 27 4.6. Service Instance
4.4.1. The Application Plane . . . . . . . . . . . . . . . . 28 4.7. Flow Identification at Technology Borders
4.4.2. The Controller Plane . . . . . . . . . . . . . . . . 28 4.7.1. Exporting Flow Identification
4.4.3. The Network Plane . . . . . . . . . . . . . . . . . . 29 4.7.2. Flow Attribute Mapping between Layers
4.5. Queuing, Shaping, Scheduling, and Preemption . . . . . . 30 4.7.3. Flow-ID Mapping Examples
4.6. Service instance . . . . . . . . . . . . . . . . . . . . 31 4.8. Advertising Resources, Capabilities, and Adjacencies
4.7. Flow identification at technology borders . . . . . . . . 32 4.9. Scaling to Larger Networks
4.7.1. Exporting flow identification . . . . . . . . . . . . 32 4.10. Compatibility with Layer 2
4.7.2. Flow attribute mapping between layers . . . . . . . . 34 5. Security Considerations
4.7.3. Flow-ID mapping examples . . . . . . . . . . . . . . 35 6. Privacy Considerations
4.8. Advertising resources, capabilities and adjacencies . . . 36 7. IANA Considerations
4.9. Scaling to larger networks . . . . . . . . . . . . . . . 37 8. Informative References
4.10. Compatibility with Layer-2 . . . . . . . . . . . . . . . 37 Acknowledgements
5. Security Considerations . . . . . . . . . . . . . . . . . . . 37 Authors' Addresses
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 39
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 39
9. Informative References . . . . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 44
1. Introduction 1. Introduction
This document provides the overall architecture for Deterministic This document provides the overall architecture for Deterministic
Networking (DetNet), which provides a capability for the delivery of Networking (DetNet), which provides a capability for the delivery of
data flows with extremely low packet loss rates and bounded end-to- data flows with extremely low packet loss rates and bounded end-to-
end delivery latency. DetNet is for networks that are under a single end delivery latency. DetNet is for networks that are under a single
administrative control or within a closed group of administrative administrative control or within a closed group of administrative
control; these include campus-wide networks and private WANs. DetNet control; these include campus-wide networks and private WANs. DetNet
is not for large groups of domains such as the Internet. is not for large groups of domains such as the Internet.
DetNet operates at the IP layer and delivers service over lower layer DetNet operates at the IP layer and delivers service over lower-layer
technologies such as MPLS and IEEE 802.1 Time-Sensitive Networking technologies such as MPLS and IEEE 802.1 Time-Sensitive Networking
(TSN). DetNet accomplishes these goals by dedicating network (TSN). DetNet provides a reliable and available service by
resources such as link bandwidth and buffer space to DetNet flows dedicating network resources such as link bandwidth and buffer space
and/or classes of DetNet flows, and by replicating packets along to DetNet flows and/or classes of DetNet flows, and by replicating
multiple paths. Unused reserved resources are available to non- packets along multiple paths. Unused reserved resources are
DetNet packets as long as all guarantees are fulfilled. available to non-DetNet packets as long as all guarantees are
fulfilled.
The Deterministic Networking Problem Statement The "Deterministic Networking Problem Statement" [RFC8557] introduces
[I-D.ietf-detnet-problem-statement] introduces Deterministic DetNet, and "Deterministic Networking Use Cases" [RFC8578] summarizes
Networking, and Deterministic Networking Use Cases the need for it. See [DETNET-FRAMEWORK] for specific techniques that
[I-D.ietf-detnet-use-cases] summarizes the need for it. See can be used to identify DetNet flows and assign them to specific
[I-D.ietf-detnet-dp-sol-mpls] and [I-D.ietf-detnet-dp-sol-ip] for paths through a network.
specific techniques that can be used to identify DetNet flows and
assign them to specific paths through a network.
A goal of DetNet is a converged network in all respects including the A goal of DetNet is a converged network in all respects, including
convergence of sensitive non-IP networks onto a common network the convergence of sensitive non-IP networks onto a common network
infrastructure. The presence of DetNet flows does not preclude non- infrastructure. The presence of DetNet flows does not preclude non-
DetNet flows, and the benefits offered DetNet flows should not, DetNet flows, and the benefits offered DetNet flows should not,
except in extreme cases, prevent existing Quality of Service (QoS) except in extreme cases, prevent existing Quality-of-Service (QoS)
mechanisms from operating in a normal fashion, subject to the mechanisms from operating in a normal fashion, subject to the
bandwidth required for the DetNet flows. A single source-destination bandwidth required for the DetNet flows. A single source-destination
pair can trade both DetNet and non-DetNet flows. End systems and pair can trade both DetNet and non-DetNet flows. End systems and
applications need not instantiate special interfaces for DetNet applications need not instantiate special interfaces for DetNet
flows. Networks are not restricted to certain topologies; flows. Networks are not restricted to certain topologies;
connectivity is not restricted. Any application that generates a connectivity is not restricted. Any application that generates a
data flow that can be usefully characterized as having a maximum data flow that can be usefully characterized as having a maximum
bandwidth should be able to take advantage of DetNet, as long as the bandwidth should be able to take advantage of DetNet, as long as the
necessary resources can be reserved. Reservations can be made by the necessary resources can be reserved. Reservations can be made by the
application itself, via network management, by an application's application itself, via network management, centrally by an
controller, or by other means, e.g., a dynamic control plane (e.g., application's controller, or by other means, for instance, by placing
[RFC2205]). QoS requirements of DetNet flows can be met if all on-demand reservation via a distributed Control Plane, e.g.,
network nodes in a DetNet domain implement DetNet capabilities. leveraging the Resource Reservation Protocol (RSVP) [RFC2205]. QoS
DetNet nodes can be interconnected with different sub-network requirements of DetNet flows can be met if all network nodes in a
technologies (Section 4.1.2), where the nodes of the subnet are not DetNet domain implement DetNet capabilities. DetNet nodes can be
DetNet aware (Section 4.1.3). interconnected with different sub-network technologies
(Section 4.1.2) where the nodes of the subnet are not DetNet aware
(Section 4.1.3).
Many applications that are intended to be served by Deterministic Many applications that are intended to be served by DetNet require
Networking require the ability to synchronize the clocks in end the ability to synchronize the clocks in end systems to a sub-
systems to a sub-microsecond accuracy. Some of the queue control microsecond accuracy. Some of the queue-control techniques defined
techniques defined in Section 4.5 also require time synchronization in Section 4.5 also require time synchronization among network nodes.
among network nodes. The means used to achieve time synchronization The means used to achieve time synchronization are not addressed in
are not addressed in this document. DetNet can accommodate various this document. DetNet can accommodate various time-synchronization
time synchronization techniques and profiles that are defined techniques and profiles that are defined elsewhere to address the
elsewhere to address the needs of different market segments. needs of different market segments.
2. Terminology 2. Terminology
2.1. Terms used in this document 2.1. Terms Used in This Document
The following terms are used in the context of DetNet in this The following terms are used in the context of DetNet in this
document: document:
allocation allocation
Resources are dedicated to support a DetNet flow. Depending The dedication of resources to support a DetNet flow. Depending
on an implementation, the resource may be reused by non- on an implementation, the resource may be reused by non-DetNet
DetNet flows when it is not used by the DetNet flow. flows when it is not used by the DetNet flow.
App-flow App-flow
The payload (data) carried over a DetNet service. The payload (data) carried over a DetNet service.
DetNet compound flow and DetNet member flow DetNet compound flow and DetNet member flow
A DetNet compound flow is a DetNet flow that has been A DetNet compound flow is a DetNet flow that has been separated
separated into multiple duplicate DetNet member flows for into multiple duplicate DetNet member flows for service protection
service protection at the DetNet service sub-layer. Member at the DetNet service sub-layer. Member flows are merged back
flows are merged back into a single DetNet compound flow such into a single DetNet compound flow such that there are no
that there are no duplicate packets. "Compound" and "member" duplicate packets. "Compound" and "member" are strictly relative
are strictly relative to each other, not absolutes; a DetNet to each other, not absolutes; a DetNet compound flow comprising
compound flow comprising multiple DetNet member flows can, in multiple DetNet member flows can, in turn, be a member of a
turn, be a member of a higher-order compound. higher-order compound.
DetNet destination DetNet destination
An end system capable of terminating a DetNet flow. An end system capable of terminating a DetNet flow.
DetNet domain DetNet domain
The portion of a network that is DetNet aware. It includes The portion of a network that is DetNet aware. It includes end
end systems and DetNet nodes. systems and DetNet nodes.
DetNet edge node DetNet edge node
An instance of a DetNet relay node that acts as a source and/ An instance of a DetNet relay node that acts as a source and/or
or destination at the DetNet service sub-layer. For example, destination at the DetNet service sub-layer. For example, it can
it can include a DetNet service sub-layer proxy function for include a DetNet service sub-layer proxy function for DetNet
DetNet service protection (e.g., the addition or removal of service protection (e.g., the addition or removal of packet
packet sequencing information) for one or more end systems, sequencing information) for one or more end systems, it can start
or starts or terminates resource allocation at the DetNet or terminate resource allocation at the DetNet forwarding sub-
forwarding sub-layer, or aggregates DetNet services into new layer, or it can aggregate DetNet services into new DetNet flows.
DetNet flows. It is analogous to a Label Edge Router (LER) It is analogous to a Label Edge Router (LER) or a Provider Edge
or a Provider Edge (PE) router. (PE) router.
DetNet flow DetNet flow
A DetNet flow is a sequence of packets which conform uniquely A sequence of packets that conforms uniquely to a flow identifier
to a flow identifier, and to which the DetNet service is to and to which the DetNet service is to be provided. It includes
be provided. It includes any DetNet headers added to support any DetNet headers added to support the DetNet service and
the DetNet service and forwarding sub-layers. forwarding sub-layers.
DetNet forwarding sub-layer DetNet forwarding sub-layer
DetNet functionality is divided into two sub-layers. One of DetNet functionality is divided into two sub-layers. One of them
them is the DetNet forwarding sub-layer, which optionally is the DetNet forwarding sub-layer, which optionally provides
provides resource allocation for DetNet flows over paths resource allocation for DetNet flows over paths provided by the
provided by the underlying network. underlying network.
DetNet intermediate node DetNet intermediate node
A DetNet relay node or DetNet transit node. A DetNet relay node or DetNet transit node.
DetNet node DetNet node
A DetNet edge node, a DetNet relay node, or a DetNet transit A DetNet edge node, a DetNet relay node, or a DetNet transit node.
node.
DetNet relay node DetNet relay node
A DetNet node including a service sub-layer function that A DetNet node that includes a service sub-layer function that
interconnects different DetNet forwarding sub-layer paths to interconnects different DetNet forwarding sub-layer paths to
provide service protection. A DetNet relay node participates provide service protection. A DetNet relay node participates in
in the DetNet service sub-layer. It typically incorporates the DetNet service sub-layer. It typically incorporates DetNet
DetNet forwarding sub-layer functions as well, in which case forwarding sub-layer functions as well, in which case it is
it is collocated with a transit node. collocated with a transit node.
DetNet service sub-layer DetNet service sub-layer
DetNet functionality is divided into two sub-layers. One of DetNet functionality is divided into two sub-layers. One of them
them is the DetNet service sub-layer, at which a DetNet is the DetNet service sub-layer, at which a DetNet service (e.g.,
service, e.g., service protection is provided. service protection) is provided.
DetNet service proxy DetNet service proxy
Maps between App-flows and DetNet flows. A proxy that maps between App-flows and DetNet flows.
DetNet source DetNet source
An end system capable of originating a DetNet flow. An end system capable of originating a DetNet flow.
DetNet system DetNet system
A DetNet aware end system, transit node, or relay node. A DetNet-aware end system, transit node, or relay node. "DetNet"
"DetNet" may be omitted in some text. may be omitted in some text.
DetNet transit node DetNet transit node
A DetNet node operating at the DetNet forwarding sub-layer, A DetNet node, operating at the DetNet forwarding sub-layer, that
that utilizes link layer and/or network layer switching utilizes link-layer and/or network-layer switching across multiple
across multiple links and/or sub-networks to provide paths links and/or sub-networks to provide paths for DetNet service sub-
for DetNet service sub-layer functions. Typically provides layer functions. It typically provides resource allocation over
resource allocation over those paths. An MPLS LSR is an those paths. An MPLS Label Switch Router (LSR) is an example of a
example of a DetNet transit node. DetNet transit node.
DetNet-UNI DetNet-UNI
User-to-Network Interface with DetNet specific A User-to-Network Interface (UNI) with DetNet-specific
functionalities. It is a packet-based reference point and functionalities. It is a packet-based reference point and may
may provide multiple functions like encapsulation, status, provide multiple functions like encapsulation, status,
synchronization, etc. synchronization, etc.
end system end system
Commonly called a "host" in IETF documents, and an "end Commonly called a "host" in the RFC series and an "end station" in
station" is IEEE 802 documents. End systems of interest to IEEE 802 standards. End systems of interest to this document are
this document are either sources or destinations of DetNet either sources or destinations of DetNet flows, and they may or
flows. And end system may or may not be DetNet forwarding may not be aware of DetNet forwarding sub-layers or DetNet service
sub-layer aware or DetNet service sub-layer aware. sub-layers.
link link
A connection between two DetNet nodes. It may be composed of A connection between two DetNet nodes. It may be composed of a
a physical link or a sub-network technology that can provide physical link or a sub-network technology that can provide
appropriate traffic delivery for DetNet flows. appropriate traffic delivery for DetNet flows.
PEF A Packet Elimination Function (PEF) eliminates duplicate Packet Elimination Function (PEF)
copies of packets to prevent excess packets flooding the A function that eliminates duplicate copies of packets to prevent
network or duplicate packets being sent out of the DetNet excess packets flooding the network or duplicate packets being
domain. PEF can be implemented by a DetNet edge node, a sent out of the DetNet domain. A PEF can be implemented by a
DetNet relay node, or an end system. DetNet edge node, a DetNet relay node, or an end system.
PRF A Packet Replication Function (PRF) replicates DetNet flow Packet Replication Function (PRF)
packets and forwards them to one or more next hops in the A function that replicates DetNet flow packets and forwards them
DetNet domain. The number of packet copies sent to the next to one or more next hops in the DetNet domain. The number of
hops is a DetNet flow specific parameter at the point of packet copies sent to the next hops is a parameter specific to the
replication. PRF can be implemented by a DetNet edge node, a DetNet flow at the point of replication. A PRF can be implemented
DetNet relay node, or an end system. by a DetNet edge node, a DetNet relay node, or an end system.
PREOF Collective name for Packet Replication, Elimination, and PREOF
Ordering Functions. A collective name for Packet Replication, Elimination, and
Ordering Functions.
POF A Packet Ordering Function (POF) re-orders packets within a Packet Ordering Function (POF)
DetNet flow that are received out of order. This function A function that reorders packets within a DetNet flow that are
can be implemented by a DetNet edge node, a DetNet relay received out of order. This function can be implemented by a
node, or an end system. DetNet edge node, a DetNet relay node, or an end system.
reservation reservation
The set of resources allocated between a source and one or The set of resources allocated between a source and one or more
more destinations through DetNet nodes and subnets associated destinations through DetNet nodes and subnets associated with a
with a DetNet flow, to provide the provisioned DetNet DetNet flow in order to provide the provisioned DetNet service.
service.
2.2. IEEE 802.1 TSN to DetNet dictionary 2.2. Dictionary of Terms Used by TSN and DetNet
This section also serves as a dictionary for translating from the This section serves as a dictionary for translating the terms used by
terms used by the Time-Sensitive Networking (TSN) Task Group the Time-Sensitive Networking (TSN) Task Group [IEEE802.1TSNTG] of
[IEEE802.1TSNTG] of the IEEE 802.1 WG to those of the DetNet WG. the IEEE 802.1 WG to those of the Deterministic Networking (detnet)
WG of the IETF.
Listener Listener
The IEEE 802.1 term for a destination of a DetNet flow. The term used by IEEE 802.1 for a destination of a DetNet flow.
relay system Relay system
The IEEE 802.1 term for a DetNet intermediate node. The term used by IEEE 802.1 for a DetNet intermediate node.
Stream Stream
The IEEE 802.1 term for a DetNet flow. The term used by IEEE 802.1 for a DetNet flow.
Talker Talker
The IEEE 802.1 term for the source of a DetNet flow. The term used by IEEE 802.1 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: 3.1. Primary Goals Defining the DetNet QoS
o Minimum and maximum end-to-end latency from source to destination; The DetNet QoS can be expressed in terms of:
* Minimum and maximum end-to-end latency from source to destination,
timely delivery, and bounded jitter (packet delay variation) timely delivery, and bounded jitter (packet delay variation)
derived from these constraints. derived from these constraints.
o Packet loss ratio, under various assumptions as to the operational * Packet loss ratio under various assumptions as to the operational
states of the nodes and links. states of the nodes and links.
o An upper bound on out-of-order packet delivery. It is worth * An upper bound on out-of-order packet delivery. It is worth
noting that some DetNet applications are unable to tolerate any noting that some DetNet applications are unable to tolerate any
out-of-order delivery. out-of-order delivery.
It is a distinction of DetNet that it is concerned solely with worst- It is a distinction of DetNet that it is concerned solely with worst-
case values for the end-to-end latency, jitter, and misordering. case values for the end-to-end latency, jitter, and misordering.
Average, mean, or typical values are of little interest, because they Average, mean, or typical values are of little interest, because they
do not affect the ability of a real-time system to perform its tasks. do not affect the ability of a real-time system to perform its tasks.
In general, a trivial priority-based queuing scheme will give better In general, a trivial priority-based queuing scheme will give better
average latency to a data flow than DetNet; however, it may not be a average latency to a data flow than DetNet; however, it may not be a
suitable option for DetNet because of its worst-case latency. suitable option for DetNet because of its worst-case latency.
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 Resource allocation (Section 3.2.1). * Resource allocation (Section 3.2.1)
o Service protection (Section 3.2.2). * Service protection (Section 3.2.2)
o Explicit routes (Section 3.2.3). * Explicit routes (Section 3.2.3)
Resource allocation operates by assigning resources, e.g., buffer Resource allocation operates by assigning resources, e.g., buffer
space or link bandwidth, to a DetNet flow (or flow aggregate) along space or link bandwidth, to a DetNet flow (or flow aggregate) along
its path. Resource allocation greatly reduces, or even eliminates its path. Resource allocation greatly reduces, or even eliminates
entirely, packet loss due to output packet contention within the entirely, packet loss due to output packet contention within the
network, but it can only be supplied to a DetNet flow that is limited network, but it can only be supplied to a DetNet flow that is limited
at the source to a maximum packet size and transmission rate. As at the source to a maximum packet size and transmission rate. As
DetNet flows are assumed to be rate-limited and DetNet is designed to DetNet flows are assumed to be rate limited and DetNet is designed to
provide sufficient allocated resources (including provisioned provide sufficient allocated resources (including provisioned
capacity), the use of transport layer congestion control [RFC2914] capacity), the use of transport-layer congestion control [RFC2914]
for App-flows is not required; however, if resources are allocated for App-flows is not required; however, if resources are allocated
appropriately, use of congestion control should not impact appropriately, use of congestion control should not impact
transmission negatively. transmission negatively.
Resource allocation addresses two of the DetNet QoS requirements: Resource allocation addresses two 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, resource allocation necessarily results in a amount of buffer space, resource allocation necessarily results in a
maximum end-to-end latency. It also addresses contention related maximum end-to-end latency. Resource allocation also addresses
packet loss. contention-related packet loss.
Other important contribution to packet loss are random media errors Other important contributions to packet loss are random media errors
and equipment failures. Service protection is the name for the and equipment failures. Service protection is the name for the
mechanisms used by DetNet to address these losses. The mechanisms mechanisms used by DetNet to address these losses. The mechanisms
employed are constrained by the requirement to meet the users' employed are constrained by the need to meet the users' latency
latency requirements. Packet replication and elimination requirements. Packet replication and elimination (Section 3.2.2.2)
(Section 3.2.2) and packet encoding (Section 3.2.2.3) are described and packet encoding (Section 3.2.2.3) are described in this document
in this document to provide service protection; others may be found. to provide service protection, but other mechanisms may also be
For instance, packet encoding can be used to provide service found. For instance, packet encoding can be used to provide service
protection against random media errors, packet replication and protection against random media errors, while packet replication and
elimination can be used to provide service protection against elimination can be used to provide service protection against
equipment failures. This mechanism distributes the contents of equipment failures. This mechanism distributes the contents of
DetNet flows over multiple paths in time and/or space, so that the DetNet flows over multiple paths in time and/or space, so that the
loss of some of the paths does need not cause the loss of any loss of some of the paths does need not cause the loss of any
packets. packets.
The paths are typically (but not necessarily) explicit routes, so The paths are typically (but not necessarily) explicit routes so that
that they do not normally suffer temporary interruptions caused by they do not normally suffer temporary interruptions caused by the
the convergence of routing or bridging protocols. convergence of routing or bridging protocols.
These three techniques can be applied independently, giving eight These three techniques can be applied individually or applied
possible combinations, including none (no DetNet), although some together; it results that eight combinations, including none (no
combinations are of wider utility than others. This separation keeps DetNet), are possible. Some combinations, however, are of wider
the protocol stack coherent and maximizes interoperability with utility than others. This separation keeps the protocol stack
existing and developing standards in this (IETF) and other Standards coherent and maximizes interoperability with existing and developing
Development Organizations. Some examples of typical expected standards in the IETF and other Standards Development Organizations.
combinations: The following are examples of typical expected combinations:
o Explicit routes plus service protection are exactly the techniques * The combination of explicit routes and service protection is the
employed by seamless redundancy mechanisms applied on a ring technique employed by seamless redundancy mechanisms applied on a
topology as described, e.g., in [IEC62439-3-2016]. In this ring topology, e.g., as described in [IEC-62439-3]. In this
example, explicit routes are achieved by limiting the physical example, explicit routes are achieved by limiting the physical
topology of the network to a ring. Sequentialization, topology of the network to a ring. Sequentialization,
replication, and duplicate elimination are facilitated by packet replication, and duplicate elimination are facilitated by packet
tags added at the front or the end of Ethernet frames. [RFC8227] tags added at the front or the end of Ethernet frames. [RFC8227]
provides another example in the context of MPLS. provides another example in the context of MPLS.
o Resource allocation alone was originally offered by IEEE 802.1 * Resource allocation alone was originally offered by Audio Video
Audio Video bridging [IEEE802.1BA]. As long as the network Bridging as defined by IEEE 802.1 [IEEE802.1BA]. As long as the
suffers no failures, packet loss due to output packet contention network suffers no failures, packet loss due to output packet
can be eliminated through the use of a reservation protocol (e.g., contention can be eliminated through the use of a reservation
Multiple Stream Registration Protocol [IEEE802.1Q-2018]), shapers protocol (e.g., the Multiple Stream Registration Protocol
in every bridge, and proper dimensioning. [IEEE802.1Q]), shapers in every bridge, and proper dimensioning.
o Using all three together gives maximum protection. * Using all three together gives maximum protection.
There are, of course, simpler methods available (and employed, today) There are, of course, simpler methods available (and employed today)
to achieve levels of latency and packet loss that are satisfactory to achieve levels of latency and packet loss that are satisfactory
for many applications. Prioritization and over-provisioning is one for many applications. Prioritization and over-provisioning is one
such technique. However, these methods generally work best in the such technique. However, these methods generally work best in the
absence of any significant amount of non-critical traffic in the absence of any significant amount of noncritical traffic in the
network (if, indeed, such traffic is supported at all), or work only network (if, indeed, such traffic is supported at all). They may
if the critical traffic constitutes only a small portion of the also work only if the critical traffic constitutes only a small
network's theoretical capacity, or work only if all systems are portion of the network's theoretical capacity, if all systems are
functioning properly, or in the absence of actions by end systems functioning properly, or if actions by end systems that disrupt the
that disrupt the network's operations. network's operations are absent.
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 the
DetNet Architecture will assist various vendors, users, and/or DetNet architecture defined in this document will assist various
"vertical" Standards Development Organizations (dedicated to a single vendors, users, and/or "vertical" Standards Development Organizations
industry) to make selections among the available means of (dedicated to a single industry) in making selections among the
implementing DetNet networks. available means of implementing DetNet networks.
3.2. Mechanisms to achieve DetNet QoS 3.2. Mechanisms to Achieve DetNet QoS
3.2.1. Resource allocation 3.2.1. Resource Allocation
3.2.1.1. Eliminate contention loss 3.2.1.1. Eliminate Contention Loss
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 packet loss due to output packet reduce, or even completely eliminate, packet loss due to output
contention within a DetNet node as a cause of packet loss. This can packet contention within a DetNet node as a cause of packet loss.
be achieved only by the provision of sufficient buffer storage at This can be achieved only by the provision of sufficient buffer
each node through the network to ensure that no packets are dropped storage at each node through the network to ensure that no packets
due to a lack of buffer storage. Note that App-flows are generally are dropped due to a lack of buffer storage. Note that App-flows are
not expected to be responsive to implicit [RFC2914] or explicit generally not expected to be responsive to implicit [RFC2914] or
congestion notification [RFC3168]. explicit congestion notification [RFC3168].
Ensuring adequate buffering requires, in turn, that the source, and Ensuring adequate buffering requires, in turn, that the source and
every DetNet node along the path to the destination (or nearly every every DetNet node along the path to the destination (or nearly every
node, see Section 4.3.3) be careful to regulate its output to not 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 periods exceed the data rate for any DetNet flow, except for brief periods
when making up for interfering traffic. Any packet sent ahead of its when making up for interfering traffic. Any packet sent ahead of its
time potentially adds to the number of buffers required by the next time potentially adds to the number of buffers required by the next-
hop DetNet node and may thus exceed the resources allocated for a hop DetNet node and may thus exceed the resources allocated for a
particular DetNet flow. Furthermore, rate limiting, e.g., using particular DetNet flow. Furthermore, rate limiting (e.g., using
traffic policing and shaping functions, e.g., [RFC2475], at the traffic policing) and shaping functions (e.g., shaping as defined in
ingress of the DetNet domain must be applied. This is needed for [RFC2475]) at the ingress of the DetNet domain must be applied. This
meeting the requirements of DetNet flows as well as for protecting is needed for meeting the requirements of DetNet flows as well as for
non-DetNet traffic from potentially misbehaving DetNet traffic protecting non-DetNet traffic from potentially misbehaving DetNet
sources. Note that large buffers have some issues, see, e.g., traffic sources. Note that large buffers have some issues (see,
[BUFFERBLOAT]. e.g., [BUFFERBLOAT]).
The low-level mechanisms described in Section 4.5 provide the The low-level mechanisms described in Section 4.5 provide the
necessary regulation of transmissions by an end system or DetNet node necessary regulation of transmissions by an end system or DetNet node
to provide resource allocation. The allocation of the bandwidth and to provide resource allocation. The allocation of the bandwidth and
buffers for a DetNet flow requires provisioning. A DetNet node may buffers for a DetNet flow requires provisioning. A DetNet node may
have other resources requiring allocation and/or scheduling, that have other resources requiring allocation and/or scheduling that
might otherwise be over-subscribed and trigger the rejection of a might otherwise be over-subscribed and trigger the rejection of a
reservation. reservation.
3.2.1.2. Jitter Reduction 3.2.1.2. Jitter Reduction
A core objective of DetNet is to enable the convergence of sensitive A core objective of DetNet is to enable the convergence of sensitive
non-IP networks onto a common network infrastructure. This requires non-IP networks onto a common network infrastructure. This requires
the accurate emulation of currently deployed mission-specific the accurate emulation of currently deployed mission-specific
networks, which for example rely on point-to-point analog (e.g., networks, which, for example, rely on point-to-point analog (e.g.,
4-20mA modulation) and serial-digital cables (or buses) for highly 4-20mA modulation) and serial-digital cables (or buses) for highly
reliable, synchronized and jitter-free communications. While the reliable, synchronized, and jitter-free communications. While the
latency of analog transmissions is basically the speed of light, latency of analog transmissions is basically the speed of light,
legacy serial links are usually slow (in the order of Kbps) compared legacy serial links are usually slow (in the order of Kbps) compared
to, say, Gigabit Ethernet, and some latency is usually acceptable. to, say, Gigabit Ethernet, and some latency is usually acceptable.
What is not acceptable is the introduction of excessive jitter, which What is not acceptable is the introduction of excessive jitter, which
may, for instance, affect the stability of control systems. may, for instance, affect the stability of control systems.
Applications that are designed to operate on serial links usually do Applications that are designed to operate on serial links usually do
not provide services to recover the jitter, because jitter simply not provide services to recover the jitter, because jitter simply
does not exist there. DetNet flows are generally expected to be does not exist there. DetNet flows are generally expected to be
delivered in-order and the precise time of reception influences the delivered in order, and the precise time of reception influences the
processes. In order to converge such existing applications, there is processes. In order to converge such existing applications, there is
a desire to emulate all properties of the serial cable, such as clock a desire to emulate all properties of the serial cable, such as clock
transportation, perfect flow isolation and fixed latency. While transportation, perfect flow isolation, and fixed latency. While
minimal jitter (in the form of specifying minimum, as well as minimal jitter (in the form of specifying minimum, as well as
maximum, end-to-end latency) is supported by DetNet, there are maximum, end-to-end latency) is supported by DetNet, there are
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 a combination of: general, users are encouraged to use a combination of:
o Sub-microsecond time synchronization among all source and * 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. * 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 4.5 that also provide resource allocation. Section 4.5 that also provide resource allocation.
3.2.2. Service Protection 3.2.2. Service Protection
Service protection aims to mitigate or eliminate packet loss due to Service protection aims to mitigate or eliminate packet loss due to
equipment failures, including random media and/or memory faults. equipment failures, including random media and/or memory faults.
These types of packet loss can be greatly reduced by spreading the These types of packet loss can be greatly reduced by spreading the
data over multiple disjoint forwarding paths. Various service data over multiple disjoint forwarding paths. Various service
protection methods are described in [RFC6372], e.g., 1+1 linear protection methods are described in [RFC6372], e.g., 1+1 linear
protection. This section describes the functional details of an protection. The functional details of an additional method are
additional method in Section 3.2.2.2, which can be implemented as described in Section 3.2.2.2, which can be implemented as described
described in Section 3.2.2.3 or as specified in in Section 3.2.2.3 or as specified in [DETNET-MPLS] in order to
[I-D.ietf-detnet-dp-sol-mpls] in order to provide 1+n hitless provide 1+n hitless protection. The appropriate service protection
protection. The appropriate service protection mechanism depends on mechanism depends on the scenario and the requirements.
the scenario and the requirements.
3.2.2.1. In-Order Delivery 3.2.2.1. In-Order Delivery
Out-of-order packet delivery can be a side effect of service Out-of-order packet delivery can be a side effect of service
protection. Packets delivered out-of-order impact the amount of protection. Packets delivered out of order impact the amount of
buffering needed at the destination to properly process the received buffering needed at the destination to properly process the received
data. Such packets also influence the jitter of a flow. The DetNet data. Such packets also influence the jitter of a flow. The
service includes maximum allowed misordering as a constraint. Zero guarantees of a DetNet service include a maximum amount of
misordering would be a valid service constraint to reflect that the misordering as a constraint. Zero misordering would be a valid
end system(s) of the flow cannot tolerate any out-of-order delivery. service constraint to reflect that the end system(s) of the flow
DetNet Packet Ordering Functionality (POF) (Section 3.2.2.2) can be cannot tolerate any out-of-order delivery. A DetNet Packet Ordering
used to provide in-order delivery. Function (POF) (Section 3.2.2.2) can be used to provide in-order
delivery.
3.2.2.2. Packet Replication and Elimination 3.2.2.2. Packet Replication and Elimination
This section describes a service protection method that sends copies This section describes a service protection method that sends copies
of the same packets over multiple paths. of the same packets over multiple paths.
The DetNet service sub-layer includes the packet replication (PRF), The DetNet service sub-layer includes the PRF, PEF, and POF for use
the packet elimination (PEF), and the packet ordering functionality in DetNet edge, relay node, and end-system packet processing. These
(POF) for use in DetNet edge, relay node, and end system packet functions can be enabled in a DetNet edge node, relay node, or end
processing. These functions can be enabled in a DetNet edge node, system. The collective name for all three functions is Packet
relay node or end system. The collective name for all three Replication, Elimination, and Ordering Functions (PREOF). The packet
functions is Packet Replication, Elimination, and Ordering Functions replication and elimination service protection method altogether
(PREOF). The packet replication and elimination service protection involves four capabilities:
method altogether involves four capabilities:
o Providing sequencing information to the packets of a DetNet * Sequencing information is provided to the packets of a DetNet
compound flow. This may be done by adding a sequence number or compound flow. This may be done by adding a sequence number or
time stamp as part of DetNet, or may be inherent in the packet, time stamp as part of DetNet, or it may be inherent in the packet,
e.g., in a higher layer protocol, or associated to other physical e.g., in a higher-layer protocol or associated to other physical
properties such as the precise time (and radio channel) of properties such as the precise time (and radio channel) of
reception of the packet. This is typically done once, at or near reception of the packet. This is typically done once, at or near
the source. the source.
o The Packet Replication Function (PRF) replicates these packets * The PRF replicates these packets into multiple DetNet member flows
into multiple DetNet member flows and typically sends them along and typically sends them along multiple different paths to the
multiple different paths to the destination(s), e.g., over the destination(s), e.g., over the explicit routes described in
explicit routes of Section 3.2.3. The location within a DetNet Section 3.2.3. The location within a DetNet node and the
node, and the mechanism used for the PRF is left open for mechanism used for the PRF are left open for implementations.
implementations.
o The Packet Elimination Function (PEF) eliminates duplicate packets * The PEF eliminates duplicate packets of a DetNet flow based on the
of a DetNet flow based on the sequencing information and a history sequencing information and a history of received packets. The
of received packets. The output of the PEF is always a single output of the PEF is always a single packet. This may be done at
packet. This may be done at any DetNet node along the path to any DetNet node along the path to save network resources further
save network resources further downstream, in particular if downstream, in particular if multiple replication points exist.
multiple Replication points exist. But the most common case is to But the most common case is to perform this operation at the very
perform this operation at the very edge of the DetNet network, edge of the DetNet network, preferably in or near the receiver.
preferably in or near the receiver. The location within a DetNet The location within a DetNet node and the mechanism used for the
node, and mechanism used for the PEF is left open for PEF is left open for implementations.
implementations.
o The Packet Ordering Function (POF) uses the sequencing information * The POF uses the sequencing information to reorder a DetNet flow's
to re-order a DetNet flow's packets that are received out of packets that are received out of order.
order.
The order in which a DetNet node applies PEF, POF, and PRF to a The order in which a DetNet node applies PEF, POF, and PRF to a
DetNet flow is left open for implementations. DetNet flow is left open for implementations.
Some service protection mechanisms rely on switching from one flow to Some service protection mechanisms rely on switching from one flow to
another when a failure of a flow is detected. Contrarily, packet another when a failure of a flow is detected. Contrarily, packet
replication and elimination combines the DetNet member flows sent replication and elimination combines the DetNet member flows sent
along multiple different paths, and performs a packet-by-packet along multiple different paths and performs a packet-by-packet
selection of which to discard, e.g., based on sequencing information. selection of which to discard, e.g., based on sequencing information.
In the simplest case, this amounts to replicating each packet in a In the simplest case, this amounts to 1) replicating each packet in a
source that has two interfaces, and conveying them through the source that has two interfaces and 2) conveying them through the
network, along separate (Shared Risk Link Group (SRLG) disjoint) network along separate (Shared Risk Link Group (SRLG) disjoint) paths
paths, to the similarly dual-homed destinations, that discard the to the similarly dual-homed destinations that 3) reorder the packets
extras. This ensures that one path remains, even if some DetNet and 4) discard the duplicates. This ensures that one path remains,
intermediate node fails. The sequencing information can also be used even if some DetNet intermediate node fails. The sequencing
for loss detection and for re-ordering. information can also be used for loss detection and for reordering.
DetNet relay nodes in the network can provide replication and DetNet relay nodes in the network can provide replication and
elimination facilities at various points in the network, so that elimination facilities at various points in the network so that
multiple failures can be accommodated. multiple failures can be accommodated.
This is shown in Figure 1, where the two relay nodes each replicate This is shown in Figure 1, where the two relay nodes each replicate
(R) the DetNet flow on input, sending the DetNet member flows to both (R) the DetNet flow on input, sending the DetNet member flows to both
the other relay node and to the end system, and eliminate duplicates the other relay node and to the end system, and eliminate duplicates
(E) on the output interface to the right-hand end system. Any one (E) on the output interface to the right-hand end system. Any one
link in the network can fail, and the DetNet compound flow can still link in the network can fail, and the DetNet compound flow can still
get through. Furthermore, two links can fail, as long as they are in get through. Furthermore, two links can fail, as long as they are in
different segments of the network. different segments of the network.
> > > > > > > > > relay > > > > > > > > > > > > > > > > > relay > > > > > > > >
> /------------+ R node E +------------\ > > /------------+ R node E +------------\ >
> / v + ^ \ > > / v + ^ \ >
end R + v | ^ + E end end R + v | ^ + E end
system + v | ^ + system system + v | ^ + system
> \ v + ^ / > > \ v + ^ / >
> \------------+ R relay E +-----------/ > > \------------+ R relay E +-----------/ >
> > > > > > > > > node > > > > > > > > > > > > > > > > > node > > > > > > > >
Figure 1: Packet replication and elimination Figure 1: Packet Replication and Elimination
Packet replication and elimination does not react to and correct Packet replication and elimination does not react to and correct
failures; it is entirely passive. Thus, intermittent failures, failures; it is entirely passive. Thus, intermittent failures,
mistakenly created packet filters, or misrouted data is handled just mistakenly created packet filters, or misrouted data is handled just
the same as the equipment failures that are handled by typical the same as the equipment failures that are handled by typical
routing and bridging protocols. routing and bridging protocols.
If member flows that take different-length paths through the network If member flows that take different-length paths through the network
are combined, a merge point may require extra buffering to equalize are combined, a merge point may require extra buffering to equalize
the delays over the different paths. This equalization ensures that the delays over the different paths. This equalization ensures that
the resultant compound flow will not exceed its contracted bandwidth the resultant compound flow will not exceed its contracted bandwidth
even after one or the other of the paths is restored after a failure. even after one of the paths is restored after a failure. The extra
The extra buffering can be also used to provide in-order delivery. buffering can be also used to provide in-order delivery.
3.2.2.3. Packet encoding for service protection 3.2.2.3. Packet Encoding for Service Protection
There are methods for using multiple paths to provide service There are methods for using multiple paths to provide service
protection that involve encoding the information in a packet protection that involve encoding the information in a packet
belonging to a DetNet flow into multiple transmission units, belonging to a DetNet flow into multiple transmission units,
combining information from multiple packets into any given combining information from multiple packets into any given
transmission unit. Such techniques, also known as "network coding", transmission unit. Such techniques, also known as "network coding",
can be used as a DetNet service protection technique. can be used as a DetNet service protection technique.
3.2.3. Explicit routes 3.2.3. Explicit Routes
In networks controlled by typical dynamic control protocols such as In networks controlled by typical dynamic control protocols such as
IS-IS or OSPF, a network topology event in one part of the network IS-IS or OSPF, a network topology event in one part of the network
can impact, at least briefly, the delivery of data in parts of the can impact, at least briefly, the delivery of data in parts of the
network remote from the failure or recovery event. Even the use of network remote from the failure or recovery event. Even the use of
redundant paths through a network, e.g., as defined by [RFC6372] do redundant paths through a network, e.g., as defined by [RFC6372],
not eliminate the chances of packet loss. Furthermore, out-of-order does not eliminate the chances of packet loss. Furthermore, out-of-
packet delivery can be a side effect of route changes. order packet delivery can be a side effect of route changes.
Many real-time networks rely on physical rings of two-port devices, Many real-time networks rely on physical rings of two-port devices,
with a relatively simple ring control protocol. This supports with a relatively simple ring control protocol. This supports
redundant paths for service protection with a minimum of wiring. As redundant paths for service protection with a minimum of wiring. As
an additional benefit, ring topologies can often utilize different an additional benefit, ring topologies can often utilize different
topology management protocols than those used for a mesh network, topology management protocols from those used for a mesh network,
with a consequent reduction in the response time to topology changes. with a consequent reduction in the response time to topology changes.
Of course, this comes at some cost in terms of increased hop count, Of course, this comes at some cost in terms of increased hop count,
and thus latency, for the typical path. 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 not immediately and likely not at all, in response
network topology events. Service protection (Section 3.2.2 or to network topology events. Service protection (see Sections 3.2.2
Section 3.2.2.3) over explicit routes provides a high likelihood of and 3.2.2.3) over explicit routes provides a high likelihood of
continuous connectivity. Explicit routes can be established in continuous connectivity. Explicit routes can be established in
various ways, e.g., with RSVP-TE [RFC3209], with Segment Routing (SR) various ways, e.g., with RSVP-TE [RFC3209], with Segment Routing (SR)
[RFC8402], via a Software Defined Networking approach [RFC8453], with [RFC8402], via a SDN approach [RFC8453], with IS-IS [RFC7813], etc.
IS-IS [RFC7813], etc. Explicit routes are typically used in MPLS TE Explicit routes are typically used in MPLS TE (Traffic Engineering)
LSPs. Label Switched Paths (LSPs).
Out-of-order packet delivery can be a side effect of distributing a Out-of-order packet delivery can be a side effect of distributing a
single flow over multiple paths, especially when there is a change single flow over multiple paths, especially when there is a change
from one path to another when combining the flow. This is from one path to another when combining the flow. This is
irrespective of the distribution method used, and also applies to irrespective of the distribution method used and also applies to
service protection over explicit routes. As described in service protection over explicit routes. As described in
Section 3.2.2.1, out-of-order packets influence the jitter of a flow Section 3.2.2.1, out-of-order packets influence the jitter of a flow
and impact the amount of buffering needed to process the data; and impact the amount of buffering needed to process the data;
therefore, DetNet service includes maximum allowed misordering as a therefore, the guarantees of a DetNet service include a maximum
constraint. The use of explicit routes helps to provide in-order amount of misordering as a constraint. The use of explicit routes
delivery because there is no immediate route change with the network helps to provide in-order delivery because there is no immediate
topology, but the changes are plannable as they are between the route change with the network topology, but the changes are plannable
different explicit routes. as they are between the different explicit routes.
3.3. Secondary goals for DetNet 3.3. Secondary Goals for DetNet
Many applications require DetNet to provide additional services, Many applications require DetNet to provide additional services,
including coexistence with other QoS mechanisms Section 3.3.1 and including coexistence with other QoS mechanisms (Section 3.3.1) and
protection against misbehaving transmitters Section 3.3.2. protection against misbehaving transmitters (Section 3.3.2).
3.3.1. Coexistence with normal traffic 3.3.1. Coexistence with Normal Traffic
A DetNet network supports the dedication of a high proportion of the A DetNet network supports the dedication of a high proportion of the
network bandwidth to DetNet flows. But, no matter how much is network bandwidth to DetNet flows. But, no matter how much is
dedicated for DetNet flows, it is a goal of DetNet to coexist with dedicated for DetNet flows, it is a goal of DetNet to coexist with
existing Class of Service schemes (e.g., DiffServ). It is also existing Class-of-Service schemes (e.g., DiffServ). It is also
important that non-DetNet traffic not disrupt the DetNet flow, of important that non-DetNet traffic not disrupt the DetNet flow, of
course (see Section 3.3.2 and Section 5). For these reasons: course (see Sections 3.3.2 and 5). For these reasons:
o Bandwidth (transmission opportunities) not utilized by a DetNet * Bandwidth (transmission opportunities) not utilized by a DetNet
flow is available to non-DetNet packets (though not to other flow is available to non-DetNet packets (though not to other
DetNet flows). DetNet flows).
o DetNet flows can be shaped or scheduled, in order to ensure that * DetNet flows can be shaped or scheduled, in order to ensure that
the highest-priority non-DetNet packet is also ensured a worst- the highest-priority non-DetNet packet is also ensured a worst-
case latency. case latency.
o When transmission opportunities for DetNet flows are scheduled in * When transmission opportunities for DetNet flows are scheduled in
detail, then the algorithm constructing the schedule should leave detail, the algorithm constructing the schedule should leave
sufficient opportunities for non-DetNet packets to satisfy the sufficient opportunities for non-DetNet packets to satisfy the
needs of the users of the network. Detailed scheduling can also needs of the users of the network. Detailed scheduling can also
permit the time-shared use of buffer resources by different DetNet permit the time-shared use of buffer resources by different DetNet
flows. flows.
Starvation of non-DetNet traffic must be avoided, e.g., by traffic Starvation of non-DetNet traffic must be avoided, for example, by
policing and shaping functions (e.g., [RFC2475]). Thus, the net traffic policing and shaping functions (e.g., [RFC2475]). Thus, the
effect of the presence of DetNet flows in a network on the non-DetNet net effect of the presence of DetNet flows in a network on the non-
flows is primarily a reduction in the available bandwidth. DetNet flows is primarily a reduction in the available bandwidth.
3.3.2. Fault Mitigation 3.3.2. Fault Mitigation
Robust real-time systems require reducing the number of possible Robust real-time systems require reducing the number of possible
failures. Filters and policers should be used in a DetNet network to failures. Filters and policers should be used in a DetNet network to
detect if DetNet packets are received on the wrong interface, or at detect if DetNet packets are received on the wrong interface, at the
the wrong time, or in too great a volume. Furthermore, filters and wrong time, or in too great a volume. Furthermore, filters and
policers can take actions to discard the offending packets or flows, policers can take actions to discard the offending packets or flows,
or trigger shutting down the offending flow or the offending or trigger shutting down the offending flow or the offending
interface. interface.
It is also essential that filters and service remarking be employed It is also essential that filters and service remarking be employed
at the network edge to prevent non-DetNet packets from being mistaken at the network edge to prevent non-DetNet packets from being mistaken
for DetNet packets, and thus impinging on the resources allocated to for DetNet packets and thus impinging on the resources allocated to
DetNet packets. In particular, sending DetNet traffic into networks DetNet packets. In particular, sending DetNet traffic into networks
that have not been provisioned in advance to handle that DetNet that have not been provisioned in advance to handle that DetNet
traffic has to be treated as a fault. The use of egress traffic traffic has to be treated as a fault. The use of egress traffic
filters, or equivalent mechanisms, to prevent this from happening are filters, or equivalent mechanisms, to prevent this from happening are
strongly recommended at the edges of a DetNet networks and DetNet strongly recommended at the edges of DetNet networks and DetNet
supporting networks. In this context, the term 'provisioned' has a supporting networks. In this context, the term 'provisioned' has a
broad meaning, e.g., provisioning could be performed via an broad meaning, e.g., provisioning could be performed via an
administrative decision that the downstream network has the available administrative decision that the downstream network has the available
capacity to carry the DetNet traffic that is being sent into it. capacity to carry the DetNet traffic that is being sent into it.
Note that the sending of App-flows that do not use transport layer Note that the sending of App-flows that do not use transport-layer
congestion control per [RFC2914] into a network that is not congestion control per [RFC2914] into a network that is not
provisioned to handle such DetNet traffic has to be treated as a provisioned to handle such traffic has to be treated as a fault and
fault and prevented. PRF generated DetNet member flows also need to prevented. PRF-generated DetNet member flows also need to be treated
be treated as not using transport layer congestion control even if as not using transport-layer congestion control even if the original
the original App-flow supports transport layer congestion control App-flow supports transport-layer congestion control because PREOF
because PREOF can remove congestion indications at the PEF and can remove congestion indications at the PEF and thereby hide such
thereby hide such indications (e.g., drops, ECN markings, increased indications (e.g., drops, ECN markings, increased latency) from end
latency) from end systems. systems.
The mechanisms to support these requirements are both data plane and The mechanisms to support these requirements are both Data Plane and
implementation specific. Data plane specific solutions will be implementation specific. Solutions that are data-plane specific will
specified in the relevant data plane solution document. There also be specified in the relevant data-plane solution document. There
exist techniques, at present and/or in various stages of also exist techniques, at present and/or in various stages of
standardization, that can support these fault mitigation tasks that standardization, that can support these fault-mitigation tasks that
deliver a high probability that misbehaving systems will have zero deliver a high probability that misbehaving systems will have zero
impact on well-behaved DetNet flows, except of course, for the impact on well-behaved DetNet flows with the exception, of course, of
receiving interface(s) immediately downstream of the misbehaving the receiving interface(s) immediately downstream from the
device. Examples of such techniques include traffic policing and misbehaving device. Examples of such techniques include traffic
shaping functions (e.g., [RFC2475]) and separating flows into per- policing and shaping functions (e.g., those described in [RFC2475]),
flow rate-limited queues, and potentially apply active queue separating flows into per-flow rate-limited queues, and potentially
management [RFC7567]. applying active queue management [RFC7567].
4. DetNet Architecture 4. DetNet Architecture
4.1. DetNet stack model 4.1. DetNet Stack Model
DetNet functionality (Section 3) is implemented in two adjacent sub- DetNet functionality (Section 3) is implemented in two adjacent sub-
layers in the protocol stack: the DetNet service sub-layer and the layers in the protocol stack: the DetNet service sub-layer and the
DetNet forwarding sub-layer. The DetNet service sub-layer provides DetNet forwarding sub-layer. The DetNet service sub-layer provides
DetNet service, e.g., service protection, to higher layers in the DetNet service, e.g., service protection, to higher layers in the
protocol stack and applications. The DetNet forwarding sub-layer protocol stack and applications. The DetNet forwarding sub-layer
supports DetNet service in the underlying network, e.g., by providing supports DetNet service in the underlying network, e.g., by providing
explicit routes and resource allocation to DetNet flows. explicit routes and resource allocation to DetNet flows.
4.1.1. Representative Protocol Stack Model 4.1.1. Representative Protocol Stack Model
Figure 2 illustrates a conceptual DetNet data plane layering model. Figure 2 illustrates a conceptual DetNet data-plane layering model.
One may compare it to that in [IEEE802.1CB], Annex C. One may compare it to that in [IEEE802.1CB], Annex C.
| packets going | ^ packets coming ^ | packets going | ^ packets coming ^
v down the stack v | up the stack | v down the stack v | up the stack |
+-----------------------+ +-----------------------+ +-----------------------+ +-----------------------+
| Source | | Destination | | Source | | Destination |
+-----------------------+ +-----------------------+ +-----------------------+ +-----------------------+
| Service sub-layer: | | Service sub-layer: | | Service sub-layer: | | Service sub-layer: |
| Packet sequencing | | Duplicate elimination | | Packet sequencing | | Duplicate elimination |
| Flow replication | | Flow merging | | Flow replication | | Flow merging |
skipping to change at page 18, line 24 skipping to change at line 796
+-----------------------+ +-----------------------+ +-----------------------+ +-----------------------+
| Forwarding sub-layer: | | Forwarding sub-layer: | | Forwarding sub-layer: | | Forwarding sub-layer: |
| Resource allocation | | Resource allocation | | Resource allocation | | Resource allocation |
| Explicit routes | | Explicit routes | | Explicit routes | | Explicit routes |
+-----------------------+ +-----------------------+ +-----------------------+ +-----------------------+
| Lower layers | | Lower layers | | Lower layers | | Lower layers |
+-----------------------+ +-----------------------+ +-----------------------+ +-----------------------+
v ^ v ^
\_________________________/ \_________________________/
Figure 2: DetNet data plane protocol stack Figure 2: DetNet Data-Plane Protocol Stack
Not all sub-layers are required for any given application, or even Not all sub-layers are required for any given application, or even
for any given network. The functionality shown in Figure 2 is: for any given network. The functionality shown in Figure 2 is:
Application Application
Shown as "source" and "destination" in the diagram. Shown as "source" and "destination" in the diagram.
Packet sequencing Packet sequencing
As part of DetNet service protection, supplies the sequence As part of the DetNet service sub-layer, the packet sequencing
number for packet replication and elimination function supplies the sequence number for packet replication and
(Section 3.2.2), thus peers with Duplicate elimination. This elimination for DetNet service protection (Section 3.2.2.2); thus,
sub-layer is not needed if a higher layer protocol is its peer is duplicate elimination. This sub-layer is not needed
expected to perform any packet sequencing and duplicate if a higher-layer protocol is expected to perform any packet
elimination required by the DetNet flow replication. sequencing and duplicate elimination required by the DetNet flow
replication.
Duplicate elimination Duplicate elimination
As part of the DetNet service sub-layer, based on the As part of the DetNet service sub-layer, based on the sequence
sequenced number supplied by its peer, packet sequencing, number supplied by its peer (packet sequencing), duplicate
Duplicate elimination discards any duplicate packets elimination discards any duplicate packets generated by DetNet
generated by DetNet flow replication. It can operate on flow replication. It can operate on member flows, compound flows,
member flows, compound flows, or both. The replication may or both. The replication may also be inferred from other
also be inferred from other information such as the precise information such as the precise time of reception in a scheduled
time of reception in a scheduled network. The duplicate network. The duplicate elimination sub-layer may also perform
elimination sub-layer may also perform resequencing of resequencing of packets to restore packet order in a flow that was
packets to restore packet order in a flow that was disrupted disrupted by the loss of packets on one or another of the multiple
by the loss of packets on one or another of the multiple paths taken.
paths taken.
Flow replication Flow replication
As part of DetNet service protection, packets that belong to As part of DetNet service protection, packets that belong to a
a DetNet compound flow are replicated into two or more DetNet DetNet compound flow are replicated into two or more DetNet member
member flows. This function is separate from packet flows. This function is separate from packet sequencing. Flow
sequencing. Flow replication can be an explicit replication replication can be an explicit replication and remarking of
and remarking of packets, or can be performed by, for packets or can be performed by, for example, techniques similar to
example, techniques similar to ordinary multicast ordinary multicast replication, albeit with resource allocation
replication, albeit with resource allocation implications. implications. Its peer is DetNet flow merging.
Peers with DetNet flow merging.
Flow merging Flow merging
As part of DetNet service protection, merges DetNet member As part of the DetNet service sub-layer, the flow merging function
flows together for packets coming up the stack belonging to a combines DetNet member flows together for packets coming up the
specific DetNet compound flow. Peers with DetNet flow stack belonging to a specific DetNet compound flow. DetNet flow
replication. DetNet flow merging, together with packet merging, together with packet sequencing, duplicate elimination,
sequencing, duplicate elimination, and DetNet flow and DetNet flow replication perform packet replication and
replication perform packet replication and elimination elimination (Section 3.2.2). Its peer is DetNet flow replication.
(Section 3.2.2).
Packet encoding Packet encoding
As part of DetNet service protection, as an alternative to As part of DetNet service protection, as an alternative to packet
packet sequencing and flow replication, packet encoding sequencing and flow replication, packet encoding combines the
combines the information in multiple DetNet packets, perhaps information in multiple DetNet packets, perhaps from different
from different DetNet compound flows, and transmits that DetNet compound flows, and transmits that information in packets
information in packets on different DetNet member Flows. on different DetNet member flows. Its peer is packet decoding.
Peers with Packet decoding.
Packet decoding Packet decoding
As part of DetNet service protection, as an alternative to As part of DetNet service protection, as an alternative to flow
flow merging and duplicate elimination, packet decoding takes merging and duplicate elimination, packet decoding takes packets
packets from different DetNet member flows, and computes from from different DetNet member flows and computes from those packets
those packets the original DetNet packets from the compound the original DetNet packets from the compound flows input to
flows input to packet encoding. Peers with Packet encoding. packet encoding. Its peer is packet encoding.
Resource allocation Resource allocation
The DetNet forwarding sub-layer provides resource allocation. The DetNet forwarding sub-layer provides resource allocation. See
See Section 4.5. The actual queuing and shaping mechanisms Section 4.5. The actual queuing and shaping mechanisms are
are typically provided by underlying subnet. These can be typically provided by the underlying subnet. These can be closely
closely associated with the means of providing paths for associated with the means of providing paths for DetNet flows.
DetNet flows. The path and the resource allocation are The path and the resource allocation are conflated in this figure.
conflated in this figure.
Explicit routes Explicit routes
The DetNet forwarding sub-layer provides mechanisms to ensure Explicit routes are arrangements of fixed paths operated at the
that fixed paths are provided for DetNet flows. These DetNet forwarding sub-layer that are determined in advance to
explicit paths avoid the impact of network convergence. avoid the impact of network convergence on DetNet flows.
Operations, Administration, and Maintenance (OAM) leverages in-band Operations, Administration, and Maintenance (OAM) leverages in-band
and out-of-band signaling that validates whether the service is and out-of-band signaling that validates whether the service is
effectively obtained within QoS constraints. OAM is not shown in effectively obtained within QoS constraints. OAM is not shown in
Figure 2; it may reside in any number of the layers. OAM can involve Figure 2; it may reside in any number of the layers. OAM can involve
specific tagging added in the packets for tracing implementation or specific tagging added in the packets for tracing implementation or
network configuration errors; traceability enables to find whether a network configuration errors; traceability enables finding whether a
packet is a replica, which DetNet relay node performed the packet is a replica, which DetNet relay node performed the
replication, and which segment was intended for the replica. Active replication, and which segment was intended for the replica. Active
and hybrid OAM methods require additional bandwidth to perform fault and hybrid OAM methods require additional bandwidth to perform fault
management and performance monitoring of the DetNet domain. OAM may, management and performance monitoring of the DetNet domain. OAM may,
for instance, generate special test probes or add OAM information for instance, generate special test probes or add OAM information
into the data packet. into the data packet.
The packet sequencing and replication elimination functions at the The packet replication and elimination functions may be performed
source and destination ends of a DetNet compound flow may be either at the source and destination ends of a DetNet compound flow
performed either in the end system or in a DetNet relay node. or in a DetNet relay node.
4.1.2. DetNet Data Plane Overview 4.1.2. DetNet Data-Plane Overview
A "Deterministic Network" will be composed of DetNet enabled end A "Deterministic Network" will be composed of DetNet-enabled end
systems, DetNet edge nodes, and DetNet relay nodes, which systems, DetNet edge nodes, and DetNet relay nodes, which
collectively deliver DetNet services. DetNet relay and edge nodes collectively deliver DetNet services. DetNet relay and edge nodes
are interconnected via DetNet transit nodes (e.g., LSRs) which are interconnected via DetNet transit nodes (e.g., LSRs), which
support DetNet, but are not DetNet service aware. All DetNet nodes support DetNet but are not DetNet service aware. All DetNet nodes
are connected to sub-networks, where a point-to-point link is also are connected to sub-networks, where a point-to-point link is also
considered as a simple sub-network. These sub-networks will provide considered a simple sub-network. These sub-networks provide DetNet-
DetNet compatible service for support of DetNet traffic. Examples of compatible service for support of DetNet traffic. Examples of sub-
sub-network technologies include MPLS TE, IEEE 802.1 TSN and OTN. Of network technologies include MPLS TE, TSN as defined by IEEE 802.1,
course, multi-layer DetNet systems may also be possible, where one and OTN (Optical Transport Network). Of course, multilayer DetNet
DetNet appears as a sub-network, and provides service to, a higher systems may also be possible, where one DetNet appears as a sub-
layer DetNet system. A simple DetNet concept network is shown in network and provides service to a higher-layer DetNet system. A
Figure 3. Note that in this and following figures "Forwarding" and simple DetNet concept network is shown in Figure 3. Note that in
"Fwd" refer to the DetNet forwarding sub-layer, "Service" and "Svc" this and following figures, "Forwarding" and "Fwd" refer to the
refer to the DetNet service sub-layer, which are described in detail DetNet forwarding sub-layer, and "Service" and "Svc" refer to the
in Section 4.1. DetNet service sub-layer; both of these sub-layers are described in
detail in Section 4.1.1.
TSN Edge Transit Relay DetNet TSN Edge Transit Relay DetNet
End System Node Node Node End System End System Node Node Node End System
+----------+ +.........+ +----------+ +----------+ +.........+ +----------+
| Appl. |<--:Svc Proxy:-- End to End Service -------->| Appl. | | Appl. |<--:Svc Proxy:-- End-to-End Service -------->| Appl. |
+----------+ +---------+ +---------+ +----------+ +----------+ +---------+ +---------+ +----------+
| TSN | |TSN| |Svc|<- DetNet flow --: Service :-->| Service | | TSN | |TSN| |Svc|<- DetNet flow --: Service :-->| Service |
+----------+ +---+ +---+ +--------+ +---------+ +----------+ +----------+ +---+ +---+ +--------+ +---------+ +----------+
|Forwarding| |Fwd| |Fwd| | Fwd | |Fwd| |Fwd| |Forwarding| |Forwarding| |Fwd| |Fwd| | Fwd | |Fwd| |Fwd| |Forwarding|
+-------.--+ +-.-+ +-.-+ +--.----.+ +-.-+ +-.-+ +---.------+ +-------.--+ +-.-+ +-.-+ +--.----.+ +-.-+ +-.-+ +---.------+
: Link : / ,-----. \ : Link : / ,-----. \ : Link : / ,-----. \ : Link : / ,-----. \
+........+ +-[ Sub ]-+ +.......+ +-[ Sub ]-+ +........+ +-[ Sub- ]-+ +.......+ +-[ Sub- ]-+
[Network] [Network] [network] [network]
`-----' `-----' `-----' `-----'
Figure 3: A Simple DetNet Enabled Network Figure 3: A Simple DetNet-Enabled Network
DetNet data plane is divided into two sub-layers: the DetNet service DetNet Data Plane is divided into two sub-layers: the DetNet service
sub-layer and the DetNet forwarding sub-layer. This helps to explore sub-layer and the DetNet forwarding sub-layer. This helps to explore
and evaluate various combinations of the data plane solutions and evaluate various combinations of the data-plane solutions
available. Some of them are illustrated in Figure 4. This available. Some of them are illustrated in Figure 4. This
separation of DetNet sub-layers, while helpful, should not be separation of DetNet sub-layers, while helpful, should not be
considered as formal requirement. For example, some technologies may considered a formal requirement. For example, some technologies may
violate these strict sub-layers and still be able to deliver a DetNet violate these strict sub-layers and still be able to deliver a DetNet
service. service.
. .
. .
+-----------------------------+ +-----------------------------+
| DetNet Service sub-layer | PW, UDP, GRE | DetNet Service sub-layer | PW, UDP, GRE
+-----------------------------+ +-----------------------------+
| DetNet Forwarding sub-layer | IPv6, IPv4, MPLS TE LSPs, MPLS SR | DetNet Forwarding sub-layer | IPv6, IPv4, MPLS TE LSPs, MPLS SR
+-----------------------------+ +-----------------------------+
. .
. .
Figure 4: DetNet adaptation to data plane Figure 4: DetNet Adaptation to Data Plane
In some networking scenarios, the end system initially provides a In some networking scenarios, the end system initially provides a
DetNet flow encapsulation, which contains all information needed by DetNet flow encapsulation, which contains all information needed by
DetNet nodes (e.g., Real-time Transport Protocol (RTP) [RFC3550] DetNet nodes (e.g., DetNet flow based on the Real-time Transport
based DetNet flow carried over a native UDP/IP network or Protocol (RTP) [RFC3550] that is carried over a native UDP/IP network
PseudoWire). In other scenarios, the encapsulation formats might or pseudowire (PW)). In other scenarios, the encapsulation formats
differ significantly. might differ significantly.
There are many valid options to create a data plane solution for There are many valid options to create a data-plane solution for
DetNet traffic by selecting a technology approach for the DetNet DetNet traffic by selecting a technology approach for the DetNet
service sub-layer and also selecting a technology approach for the service sub-layer and also selecting a technology approach for the
DetNet forwarding sub-layer. There are a large number of valid DetNet forwarding sub-layer. There are a large number of valid
combinations. combinations.
One of the most fundamental differences between different potential One of the most fundamental differences between different potential
data plane options is the basic headers used by DetNet nodes. For data-plane options is the basic headers used by DetNet nodes. For
example, the basic service can be delivered based on an MPLS label or example, the basic service can be delivered based on an MPLS label or
an IP header. This decision impacts the basic forwarding logic for an IP header. This decision impacts the basic forwarding logic for
the DetNet service sub-layer. Note that in both cases, IP addresses the DetNet service sub-layer. Note that in both cases, IP addresses
are used to address DetNet nodes. The selected DetNet forwarding are used to address DetNet nodes. The selected DetNet forwarding
sub-layer technology also needs to be mapped to the sub-net sub-layer technology also needs to be mapped to the subnet technology
technology used to interconnect DetNet nodes. For example, DetNet used to interconnect DetNet nodes. For example, DetNet flows will
flows will need to be mapped to TSN Streams. need to be mapped to TSN Streams.
4.1.3. Network reference model 4.1.3. Network Reference Model
Figure 5 shows another view of the DetNet service related reference Figure 5 shows another view of the DetNet service-related reference
points and main components. points and main components.
DetNet DetNet DetNet DetNet
end system end system End System End System
_ _ _ _
/ \ +----DetNet-UNI (U) / \ / \ +----DetNet-UNI (U) / \
/App\ | /App\ /App\ | /App\
/-----\ | /-----\ /-----\ | /-----\
| NIC | v ________ | NIC | | NIC | v ________ | NIC |
+--+--+ _____ / \ DetNet-UNI (U) --+ +--+--+ +--+--+ _____ / \ DetNet-UNI (U) --+ +--+--+
| / \__/ \ | | | / \__/ \ | |
| / +----+ +----+ \_____ | | | / +----+ +----+ \_____ | |
| / | | | | \_______ | | | / | | | | \_______ | |
+------U PE +----+ P +----+ \ _ v | +------U PE +----+ P +----+ \ _ v |
| | | | | | | ___/ \ | | | | | | | | ___/ \ |
| +--+-+ +----+ | +----+ | / \_ | | +--+-+ +----+ | +----+ | / \_ |
\ | | | | | / \ | \ | | | | | / \ |
\ | +----+ +--+-+ +--+PE |------ U-----+ \ | +----+ +--+-+ +--+PE |------ U-----+
\ | | | | | | | | | \_ _/ \ | | | | | | | | | \_ _/
\ +---+ P +----+ P +--+ +----+ | \____/ \ +---+ P +----+ P +--+ +----+ | \____/
\___ | | | | / \___ | | | | /
\ +----+__ +----+ DetNet-1 DetNet-2 \ +----+__ +----+ DetNet-1 DetNet-2
| \_____/ \___________/ | | \_____/ \___________/ |
| | | |
| | End-to-End service | | | | | | End-to-End Service | | | |
<-------------------------------------------------------------> <------------------------------------------------------------->
| | DetNet service | | | | | | DetNet Service | | | |
| <------------------------------------------------> | | <------------------------------------------------> |
| | | | | | | | | | | |
Figure 5: DetNet Service Reference Model (multi-domain) Figure 5: DetNet Service Reference Model (Multidomain)
DetNet User Network Interfaces (DetNet-UNIs) ("U" in Figure 5) are DetNet User-to-Network Interfaces (DetNet-UNIs) ("U" in Figure 5) are
assumed in this document to be packet-based reference points and assumed in this document to be packet-based reference points and
provide connectivity over the packet network. A DetNet-UNI may provide connectivity over the packet network. A DetNet-UNI may
provide multiple functions, e.g., it may add networking technology provide multiple functions. For example, it may:
specific encapsulation to the DetNet flows if necessary; it may
provide status of the availability of the resources associated with a
reservation; it may provide a synchronization service for the end
system; it may carry enough signaling to place the reservation in a
network without a controller, or if the controller only deals with
the network but not the end systems. Internal reference points of
end systems (between the application and the NIC) are more
challenging from control perspective and they may have extra
requirements (e.g., in-order delivery is expected in end system
internal reference points, whereas it is considered optional over the
DetNet-UNI).
4.2. DetNet systems * add encapsulation specific to networking technology to the DetNet
flows if necessary,
4.2.1. End system * provide status of the availability of the resources associated
with a reservation,
* provide a synchronization service for the end system, or
* carry enough signaling to place the reservation in a network
without a controller or in a network where the controller only
deals with the network but not the end systems.
Internal reference points of end systems (between the application and
the Network Interface Card (NIC)) are more challenging from the
control perspective, and they may have extra requirements (e.g., in-
order delivery is expected in end system internal reference points,
whereas it is considered optional over the DetNet-UNI).
4.2. DetNet Systems
4.2.1. End System
The traffic characteristics of an App-flow can be CBR (constant bit The traffic characteristics of an App-flow can be CBR (constant bit
rate) or VBR (variable bit rate) and can have Layer-1 or Layer-2 or rate) or VBR (variable bit rate) and can have Layer 1, Layer 2, or
Layer-3 encapsulation (e.g., TDM (time-division multiplexing), Layer 3 encapsulation (e.g., TDM (time-division multiplexing)
Ethernet, IP). These characteristics are considered as input for Ethernet, IP). These characteristics are considered as input for
resource reservation and might be simplified to ensure determinism resource reservation and might be simplified to ensure determinism
during packet forwarding (e.g., making reservations for the peak rate during packet forwarding (e.g., making reservations for the peak rate
of VBR traffic, etc.). of VBR traffic, etc.).
An end system may or may not be DetNet forwarding sub-layer aware or An end system may or may not be aware of the DetNet forwarding sub-
DetNet service sub-layer aware. That is, an end system may or may layer or DetNet service sub-layer. That is, an end system may or may
not contain DetNet specific functionality. End systems with DetNet not contain DetNet-specific functionality. End systems with DetNet
functionalities may have the same or different forwarding sub-layer functionalities may have the same or different forwarding sub-layer
as the connected DetNet domain. Categorization of end systems are as the connected DetNet domain. Categorization of end systems are
shown in Figure 6. shown in Figure 6.
End system End system
| |
| |
| DetNet aware ? | DetNet aware ?
/ \ / \
+------< >------+ +------< >------+
NO | \ / | YES NO | \ / | YES
| v | | v |
DetNet unaware | DetNet-unaware |
End system | End system |
| Service/Forwarding | Service/Forwarding
| sub-layer | sub-layer
/ \ aware ? / \ aware ?
+--------< >-------------+ +--------< >-------------+
f-aware | \ / | s-aware f-aware | \ / | s-aware
| v | | v |
| | both | | | both |
| | | | | |
DetNet f-aware | DetNet s-aware DetNet f-aware | DetNet s-aware
End system | End system End system | End system
v v
DetNet sf-aware DetNet sf-aware
End system End system
Figure 6: Categorization of end systems Figure 6: Categorization of End Systems
Note some known use case examples for end systems: The following are some known use case examples for end systems:
o DetNet unaware: The classic case requiring service proxies. DetNet unaware
The classic case requiring service proxies.
o DetNet f-aware: A DetNet forwarding sub-layer aware system. It DetNet f-aware
knows about some TSN functions (e.g., reservation), but not about A system that is aware of the DetNet forwarding sub-layer. It
knows about some TSN functions (e.g., reservation) but not about
service protection. service protection.
o DetNet s-aware: A DetNet service sub-layer aware system. It DetNet s-aware
supplies sequence numbers, but doesn't know about resource A system that is aware of the DetNet service sub-layer. It
supplies sequence numbers but doesn't know about resource
allocation. allocation.
o DetNet sf-aware: A full functioning DetNet end system, it has DetNet sf-aware
DetNet functionalities and usually the same forwarding paradigm as A fully functioning DetNet end system. It has DetNet
the connected DetNet domain. It can be treated as an integral functionalities and usually the same forwarding paradigm as the
part of the DetNet domain. connected DetNet domain. It can be treated as an integral part of
the DetNet domain.
4.2.2. DetNet edge, relay, and transit nodes 4.2.2. DetNet Edge, Relay, and Transit Nodes
As shown in Figure 3, DetNet edge nodes providing proxy service and As shown in Figure 3, DetNet edge nodes providing proxy service and
DetNet relay nodes providing the DetNet service sub-layer are DetNet- DetNet relay nodes providing the DetNet service sub-layer are DetNet
aware, and DetNet transit nodes need only be aware of the DetNet aware, and DetNet transit nodes need only be aware of the DetNet
forwarding sub-layer. forwarding sub-layer.
In general, if a DetNet flow passes through one or more DetNet- In general, if a DetNet flow passes through one or more DetNet-
unaware network nodes between two DetNet nodes providing the DetNet unaware network nodes between two DetNet nodes providing the DetNet
forwarding sub-layer for that flow, there is a potential for forwarding sub-layer for that flow, there is a potential for
disruption or failure of the DetNet QoS. A network administrator disruption or failure of the DetNet QoS. A network administrator
needs to ensure that the DetNet-unaware network nodes are configured needs to 1) ensure that the DetNet-unaware network nodes are
to minimize the chances of packet loss and delay, and provision configured to minimize the chances of packet loss and delay and 2)
enough extra buffer space in the DetNet transit node following the provision enough extra buffer space in the DetNet transit node
DetNet-unaware network nodes to absorb the induced latency following the DetNet-unaware network nodes to absorb the induced
variations. latency variations.
4.3. DetNet flows 4.3. DetNet Flows
4.3.1. DetNet flow types 4.3.1. DetNet Flow Types
A DetNet flow can have different formats while its packets are A DetNet flow can have different formats while its packets are
forwarded between the peer end systems depending on the type of the forwarded between the peer end systems depending on the type of the
end systems. Corresponding to the end system types, the following end systems. Corresponding to the end system types, the following
possible types / formats of a DetNet flow are distinguished in this possible types/formats of a DetNet flow are distinguished in this
document. The different flow types have different requirements to document. The different flow types have different requirements to
DetNet nodes. DetNet nodes.
o App-flow: the payload (data) carried over a DetNet flow between App-flow
DetNet unaware end systems. An app-flow does not contain any The payload (data) carried over a DetNet flow between DetNet-
DetNet related attributes and does not imply any specific unaware end systems. An App-flow does not contain any DetNet-
requirement on DetNet nodes. related attributes and does not imply any specific requirement on
DetNet nodes.
o DetNet-f-flow: specific format of a DetNet flow. It only requires DetNet-f-flow
the resource allocation features provided by the DetNet forwarding The specific format of a DetNet flow. It only requires the
resource allocation features provided by the DetNet forwarding
sub-layer. sub-layer.
o DetNet-s-flow: specific format of a DetNet flow. It only requires DetNet-s-flow
the service protection feature ensured by the DetNet service sub- The specific format of a DetNet flow. It only requires the
service protection feature ensured by the DetNet service sub-
layer. layer.
o DetNet-sf-flow: specific format of a DetNet flow. It requires DetNet-sf-flow
both DetNet service sub-layer and DetNet forwarding sub-layer The specific format of a DetNet flow. It requires both the DetNet
functions during forwarding. service sub-layer and the DetNet forwarding sub-layer functions
during forwarding.
4.3.2. Source transmission behavior 4.3.2. Source Transmission Behavior
For the purposes of resource allocation, DetNet flows can be For the purposes of resource allocation, DetNet flows can be
synchronous or asynchronous. In synchronous DetNet flows, at least synchronous or asynchronous. In synchronous DetNet flows, at least
the DetNet nodes (and possibly the end systems) are closely time the DetNet nodes (and possibly the end systems) are closely time
synchronized, typically to better than 1 microsecond. By synchronized, typically to better than 1 microsecond. By
transmitting packets from different DetNet flows or classes of DetNet transmitting packets from different DetNet flows or classes of DetNet
flows at different times, using repeating schedules synchronized flows at different times, using repeating schedules synchronized
among the DetNet nodes, resources such as buffers and link bandwidth among the DetNet nodes, resources such as buffers and link bandwidth
can be shared over the time domain among different DetNet flows. can be shared over the time domain among different DetNet flows.
There is a tradeoff among techniques for synchronous DetNet flows There is a trade-off among techniques for synchronous DetNet flows
between the burden of fine-grained scheduling and the benefit of between the burden of fine-grained scheduling and the benefit of
reducing the required resources, especially buffer space. reducing the required resources, especially buffer space.
In contrast, asynchronous DetNet flows are not coordinated with a In contrast, asynchronous DetNet flows are not coordinated with a
fine-grained schedule, so relay and end systems must assume worst- fine-grained schedule, so relay and end systems must assume worst-
case interference among DetNet flows contending for buffer resources. case interference among DetNet flows contending for buffer resources.
Asynchronous DetNet flows are characterized by: Asynchronous DetNet flows are characterized by:
o A maximum packet size; * A maximum packet size;
o An observation interval; and * An observation interval; and
o A maximum number of transmissions during that observation * A maximum number of transmissions during that observation
interval. interval.
These parameters, together with knowledge of the protocol stack used These parameters, together with knowledge of the protocol stack used
(and thus the size of the various headers added to a packet), provide (and thus the size of the various headers added to a packet), provide
the bandwidth that is needed for the DetNet flow. the bandwidth that is needed for the DetNet flow.
The source is required not to exceed these limits in order to obtain The source is required not to exceed these limits in order to obtain
DetNet service. If the source transmits less data than this limit DetNet service. If the source transmits less data than this limit
allows, the unused resource such as link bandwidth can be made allows, then the unused resource, such as link bandwidth, can be made
available by the DetNet system to non-DetNet packets as long as all available by the DetNet system to non-DetNet packets as long as all
guarantees are fulfilled. However, making those resources available guarantees are fulfilled. However, making those resources available
to DetNet packets in other DetNet flows would serve no purpose. to DetNet packets in other DetNet flows would serve no purpose.
Those other DetNet flows have their own dedicated resources, on the Those other DetNet flows have their own dedicated resources, on the
assumption that all DetNet flows can use all of their resources over assumption that all DetNet flows can use all of their resources over
a long period of time. a long period of time.
There is no expectation in DetNet for App-flows to be responsive to There is no expectation in DetNet for App-flows to be responsive to
congestion control [RFC2914] or explicit congestion notification congestion control [RFC2914] or explicit congestion notification
[RFC3168]. The assumption is that a DetNet flow, to be useful, must [RFC3168]. The assumption is that a DetNet flow, to be useful, must
skipping to change at page 27, line 8 skipping to change at line 1198
application to allow it to shift from a special-purpose digital application to allow it to shift from a special-purpose digital
network to an Internet Protocol network, one fundamental shift in the network to an Internet Protocol network, one fundamental shift in the
behavior of network applications is impossible to avoid: the behavior of network applications is impossible to avoid: the
reservation of resources before the application starts. In the first reservation of resources before the application starts. In the first
place, a network cannot deliver finite latency and practically zero place, a network cannot deliver finite latency and practically zero
packet loss to an arbitrarily high offered load. Secondly, achieving packet loss to an arbitrarily high offered load. Secondly, achieving
practically zero packet loss for DetNet flows means that DetNet nodes practically zero packet loss for DetNet flows means that DetNet nodes
have to dedicate buffer resources to specific DetNet flows or to have to dedicate buffer resources to specific DetNet flows or to
classes of DetNet flows. The requirements of each reservation have classes of DetNet flows. The requirements of each reservation have
to be translated into the parameters that control each DetNet to be translated into the parameters that control each DetNet
system's queuing, shaping, and scheduling functions and delivered to system's queuing, shaping, and scheduling functions, and they have to
the DetNet nodes and end systems. be delivered to the DetNet nodes and end systems.
All nodes in a DetNet domain are expected to support the data All nodes in a DetNet domain are expected to support the data
behavior required to deliver a particular DetNet service. If a node behavior required to deliver a particular DetNet service. If a node
itself is not DetNet service aware, the DetNet nodes that are itself is not DetNet service aware, the DetNet nodes that are
adjacent to such non-DetNet aware nodes must ensure that the non- adjacent to them must ensure that the node that is non-DetNet aware
DetNet aware node is provisioned to appropriately support the DetNet is provisioned to appropriately support the DetNet service. For
service. For example, an IEEE 802.1 TSN node may be used to example, a TSN node (as defined by IEEE 802.1) may be used to
interconnect DetNet aware nodes, and these DetNet nodes can map interconnect DetNet-aware nodes, and these DetNet nodes can map
DetNet flows to 802.1 TSN flows. Another example, an MPLS-TE or TP DetNet flows to 802.1 TSN flows. As another example, an MPLS-TE or
domain may be used to interconnect DetNet aware nodes, and these MPLS-TP (Transport Profile) domain may be used to interconnect
DetNet nodes can map DetNet flows to TE LSPs which can provide the DetNet-aware nodes, and these DetNet nodes can map DetNet flows to TE
QoS requirements of the DetNet service. LSPs, which can provide the QoS requirements of the DetNet service.
4.3.3. Incomplete Networks 4.3.3. Incomplete Networks
The presence in the network of intermediate nodes or subnets that are The presence in the network of intermediate nodes or subnets that are
not fully capable of offering DetNet services complicates the ability not fully capable of offering DetNet services complicates the ability
of the intermediate nodes and/or controller to allocate resources, as of the intermediate nodes and/or controller to allocate resources, as
extra buffering must be allocated at points downstream from the non- extra buffering must be allocated at points downstream from the non-
DetNet intermediate node for a DetNet flow. This extra buffering may DetNet intermediate node for a DetNet flow. This extra buffering may
increase latency and/or jitter. increase latency and/or jitter.
4.4. Traffic Engineering for DetNet 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 a TEAS perspective, Traffic packet and nonpacket networks. From a 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 of its very nature of establishing explicit optimized paths,
Deterministic Networking can be seen as a new, specialized branch of DetNet can be seen as a new, specialized branch of TE, and it
Traffic Engineering, and inherits its architecture with a separation inherits its architecture with a separation into planes.
into planes.
The Deterministic Networking architecture is thus composed of three The DetNet architecture is thus composed of three planes: a (User)
planes, a (User) Application Plane, a Controller Plane, and a Network Application Plane, a Controller Plane, and a Network Plane. This
Plane, which echoes that of Figure 1 of Software-Defined Networking echoes the composition of Figure 1 of "Software-Defined Networking
(SDN): Layers and Architecture Terminology [RFC7426], and the (SDN): Layers and Architecture Terminology" [RFC7426] and the
Controllers identified in [RFC8453] and [RFC7149]. controllers identified in [RFC8453] and [RFC7149].
4.4.1. 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 and
operator and performs requests for Deterministic Networking services operator and performs requests for DetNet services via an abstract
via an abstract Flow Management Entity, (FME) which may or may not be Flow Management Entity (FME), which may or may not be collocated with
collocated with (one of) the end systems. (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 possibly specify DetNet nodes. to identify the end systems and possibly specify DetNet nodes.
4.4.2. 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) (as defined by the CCAMP Working Group
between management and measurement. When the logical separation of [CCAMP]) makes an additional distinction between management and
the Control, Measurement and other Management entities is not measurement. When the logical separation of the Control,
relevant, the term Controller Plane is used for simplicity to Measurement, and other Management entities is not relevant, the term
represent them all, and the term Controller Plane Function (CPF) "Controller Plane" is used for simplicity to represent them all, and
refers to any device operating in that plane, whether is it a Path the term "Controller Plane Function (CPF)" refers to any device
Computation Element (PCE) [RFC4655], or a Network Management entity operating in that plane, whether it is a Path Computation Element
(NME), or a distributed control plane. The CPF is a core element of (PCE) [RFC4655], a Network Management Entity (NME), or a distributed
a controller, in charge of computing Deterministic paths to be control protocol. The CPF is a core element of a controller, in
applied in the Network Plane. charge of computing deterministic paths to be applied in the Network
Plane.
A (Northbound) Service Interface enables applications in the A (Northbound) Service Interface enables applications in the
Application Plane to communicate with the entities in the Controller Application Plane to communicate with the entities in the Controller
Plane as illustrated in Figure 7. Plane as illustrated in Figure 7.
One or more CPF(s) collaborate to implement the requests from the FME One or more CPFs collaborate to implement the requests from the FME
as Per-Flow Per-Hop Behaviors installed in the DetNet nodes for each as per-flow, per-hop behaviors installed in the DetNet nodes for each
individual flow. The CPFs place each flow along a deterministic individual flow. The CPFs place each flow along a deterministic
sequence of DetNet nodes so as to respect per-flow constraints such arrangement of DetNet nodes so as to respect per-flow constraints
as security and latency, and optimize the overall result for metrics such as security and latency, and to optimize the overall result for
such as an abstract aggregated cost. The deterministic sequence can metrics such as an abstract aggregated cost. The deterministic
typically be more complex than a direct sequence and include arrangement can typically be more complex than a direct arrangement
redundant paths, with one or more packet replication and elimination and include redundant paths with one or more packet replication and
points. Scaling to larger networks is discussed in Section 4.9. elimination points. Scaling to larger networks is discussed in
Section 4.9.
4.4.3. 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 the Data Plane and Operational Plane (e.g., OAM) aspects.
Operational Plane (e.g., OAM) aspects.
The network Plane comprises the Network Interface Cards (NIC) in the The Network Plane comprises the Network Interface Cards (NICs) in the
end systems, which are typically IP hosts, and DetNet nodes, which end systems, which are typically IP hosts, and DetNet nodes, which
are typically IP routers and MPLS switches. Network-to-Network are typically IP routers and MPLS switches.
Interfaces such as used for Traffic Engineering path reservation in
[RFC5921], as well as User-to-Network Interfaces (UNI) such as
provided by the Local Management Interface (LMI) between network and
end systems, are both part of the Network Plane, both in the control
plane and the data plane.
A Southbound (Network) Interface enables the entities in the A Southbound (Network) Interface enables the entities in the
Controller Plane to communicate with devices in the Network Plane as Controller Plane to communicate with devices in the Network Plane as
illustrated in Figure 7. This interface leverages and extends TEAS illustrated in Figure 7. This interface leverages and extends TEAS
to describe the physical topology and resources in the Network Plane. to describe the physical topology and resources in the Network Plane.
End End End End
System System System System
-+-+-+-+-+-+-+ Northbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+-+-+-+-+-+-+ Northbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
skipping to change at page 29, line 41 skipping to change at line 1318
CPF CPF CPF CPF CPF CPF CPF CPF
-+-+-+-+-+-+-+ Southbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+-+-+-+-+-+-+ Southbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
DetNet DetNet DetNet DetNet DetNet DetNet DetNet DetNet
Node Node Node Node Node Node Node Node
NIC NIC NIC NIC
DetNet DetNet DetNet DetNet DetNet DetNet DetNet DetNet
Node Node Node Node Node Node Node Node
Figure 7: Northbound and Southbound interfaces Figure 7: Northbound and Southbound Interfaces
The DetNet nodes (and possibly the end systems NIC) expose their The DetNet nodes (and possibly the end systems' NICs) expose their
capabilities and physical resources to the controller (the CPF), and capabilities and physical resources to the controller (the CPF) and
update the CPFs with their dynamic perception of the topology, across update the CPFs with their dynamic perception of the topology across
the Southbound Interface. In return, the CPFs set the per-flow paths the Southbound Interface. In return, the CPFs set the per-flow paths
up, providing a Flow Characterization that is more tightly coupled to up, providing a Flow Characterization that is more tightly coupled to
the DetNet node Operation than a TSpec. the DetNet node operation than a TSpec.
At the Network plane, DetNet nodes may exchange information regarding At the Network Plane, DetNet nodes may exchange information regarding
the state of the paths, between adjacent DetNet nodes and possibly the state of the paths, between adjacent DetNet nodes and possibly
with the end systems, and forward packets within constraints with the end systems, and forward packets within constraints
associated to each flow, or, when unable to do so, perform a last associated to each flow, or, when unable to do so, perform a last-
resort operation such as drop or declassify. resort operation such as drop or declassify.
This document focuses on the Southbound interface and the operation This document focuses on the Southbound interface and the operation
of the Network Plane. of the Network Plane.
4.5. Queuing, Shaping, Scheduling, and Preemption 4.5. Queuing, Shaping, Scheduling, and Preemption
DetNet achieves bounded delivery latency by reserving bandwidth and DetNet achieves bounded delivery latency by reserving bandwidth and
buffer resources at each DetNet node along the path of the DetNet buffer resources at each DetNet node along the path of the DetNet
flow. The reservation itself is not sufficient, however. flow. The reservation itself is not sufficient, however.
Implementors and users of a number of proprietary and standard real- Implementors and users of a number of proprietary and standard real-
time networks have found that standards for specific data plane time networks have found that standards for specific data-plane
techniques are required to enable these assurances to be made in a techniques are required to enable these assurances to be made in a
multi-vendor network. The fundamental reason is that latency multivendor network. The fundamental reason is that latency
variation in one DetNet system results in the need for extra buffer variation in one DetNet system results in the need for extra buffer
space in the next-hop DetNet system(s), which in turn, increases the space in the next-hop DetNet system(s), which in turn increases the
worst-case per-hop latency. worst-case per-hop latency.
Standard queuing and transmission selection algorithms allow traffic Standard queuing and transmission-selection algorithms allow TE
engineering Section 4.4 to compute the latency contribution of each (Section 4.4) to compute the latency contribution of each DetNet node
DetNet node to the end-to-end latency, to compute the amount of to the end-to-end latency, to compute the amount of buffer space
buffer space required in each DetNet node for each incremental DetNet required in each DetNet node for each incremental DetNet flow, and
flow, and most importantly, to translate from a flow specification to most importantly, to translate from a flow specification to a set of
a set of values for the managed objects that control each relay or values for the managed objects that control each relay or end system.
end system. For example, the IEEE 802.1 WG has specified (and is For example, the IEEE 802.1 WG has specified (and is specifying) a
specifying) a set of queuing, shaping, and scheduling algorithms that set of queuing, shaping, and scheduling algorithms that enable each
enable each DetNet node, and/or a central controller, to compute DetNet node, and/or a central controller, to compute these values.
these values. These algorithms include: These algorithms include:
o A credit-based shaper [IEEE802.1Qav] (superseded by * A credit-based shaper [IEEE802.1Qav] (incorporated to
[IEEE802.1Q-2018]). [IEEE802.1Q]).
o Time-gated queues governed by a rotating time schedule based on * Time-gated queues governed by a rotating time schedule based on
synchronized time [IEEE802.1Qbv] (superseded by synchronized time [IEEE802.1Qbv] (incorporated to [IEEE802.1Q]).
[IEEE802.1Q-2018]).
o Synchronized double (or triple) buffers driven by synchronized * Synchronized double (or triple) buffers driven by synchronized
time ticks. [IEEE802.1Qch] (superseded by [IEEE802.1Q-2018]). time ticks. [IEEE802.1Qch] (incorporated to [IEEE802.1Q]).
o Pre-emption of an Ethernet packet in transmission by a packet with * Preemption 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] (superseded by of the preempted packet [IEEE802.1Qbu] (incorporated to
[IEEE802.1Q-2018]), [IEEE802.3br] (superseded by [IEEE802.1Q]) [IEEE802.3br] (incorporated to [IEEE802.3]).
[IEEE802.3-2018]).
While these techniques are currently embedded in Ethernet While these techniques are currently embedded in Ethernet [IEEE802.3]
[IEEE802.3-2018] and bridging standards, we can note that they are and bridging standards, we can note that they are all, except perhaps
all, except perhaps for packet preemption, equally applicable to for packet preemption, equally applicable to media other than
other media than Ethernet, and to routers as well as bridges. Other Ethernet and to routers as well as bridges. Other media may have
media may have its own methods, see, e.g., their own methods (see, e.g., [TSCH-ARCH] and [RFC7554]). Further
[I-D.ietf-6tisch-architecture], [RFC7554]. Further techniques are techniques are defined by the IETF (e.g., [RFC8289] and [RFC8033]).
defined by the IETF, e.g., [RFC8289] and [RFC8033]. DetNet may DetNet may include such definitions in the future or may define how
include such definitions in the future, or may define how these these techniques can be used by DetNet nodes.
techniques can be used by DetNet nodes.
4.6. Service instance 4.6. Service Instance
A Service instance represents all the functions required on a DetNet A service instance represents all the functions required on a DetNet
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 general reference model is shown in Figure 8 for a The DetNet network general reference model is shown in Figure 8 for a
DetNet service scenario (i.e., between two DetNet-UNIs). In this DetNet service scenario (i.e., between two DetNet-UNIs). In this
figure, end systems ("A" and "B") are connected directly to the edge figure, end systems ("A" and "B") are connected directly to the edge
nodes of an IP/MPLS network ("PE1" and "PE2"). End systems nodes of an IP/MPLS network ("PE1" and "PE2"). End systems
participating in DetNet communication may require connectivity before participating in DetNet communication may require connectivity before
setting up an App-flow that requires the DetNet service. Such a setting up an App-flow that requires the DetNet service. Such a
connectivity related service instance and the one dedicated for connectivity-related service instance and the one dedicated for
DetNet service share the same access. Packets belonging to a DetNet DetNet service share the same access. Packets belonging to a DetNet
flow are selected by a filter configured on the access ("F1" and flow are selected by a filter configured on the access ("F1" and
"F2"). As a result, data flow specific access ("access-A + F1" and "F2"). As a result, data-flow-specific access ("access-A + F1" and
"access-B + F2") are terminated in the flow specific service instance "access-B + F2") is terminated in the flow-specific service instance
("SI-1" and "SI-2"). A tunnel is used to provide connectivity ("SI-1" and "SI-2"). A tunnel is used to provide connectivity
between the service instances. between the service instances.
The tunnel is exclusively used for the packets of the DetNet flow The tunnel is exclusively used for the packets of the DetNet flow
between "SI-1" and "SI-2". The service instances are configured to between "SI-1" and "SI-2". The service instances are configured to
implement DetNet functions and a flow specific DetNet forwarding. implement DetNet functions and a flow-specific DetNet forwarding.
The service instance and the tunnel may or may not be shared by The service instance and the tunnel may or may not be shared by
multiple DetNet flows. Sharing the service instance by multiple multiple DetNet flows. Sharing the service instance by multiple
DetNet flows requires properly populated forwarding tables of the DetNet flows requires properly populated forwarding tables of the
service instance. service instance.
access-A access-B access-A access-B
<-----> <-------- tunnel ----------> <-----> <-----> <-------- tunnel ----------> <----->
+---------+ ___ _ +---------+ +---------+ ___ _ +---------+
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 8: DetNet network general reference model Figure 8: DetNet Network General Reference Model
The tunnel between the service instances may have some special The tunnel between the service instances may have some special
characteristics. For example, in case of a DetNet L3 service, there characteristics. For example, in case of a DetNet L3 service, there
are differences in the usage of the PW for DetNet traffic compared to are differences in the usage of the PW for DetNet traffic compared to
the network model described in [RFC6658]. In the DetNet scenario, the network model described in [RFC6658]. In the DetNet scenario,
the PW is likely to be used exclusively by the DetNet flow, whereas the PW is likely to be used exclusively by the DetNet flow, whereas
[RFC6658] states: "The packet PW appears as a single point-to-point [RFC6658] states:
link to the client layer. Network-layer adjacency formation and
maintenance between the client equipment will follow the normal | The packet PW appears as a single point-to-point link to the
practice needed to support the required relationship in the client | client layer. Network-layer adjacency formation and maintenance
layer ... This packet PseudoWire is used to transport all of the | between the client equipments will follow the normal practice
required Layer-2 and Layer-3 protocols between LSR1 and LSR2". | needed to support the required relationship in the client layer.
and
| This packet pseudowire is used to transport all of the required
| layer 2 and layer 3 protocols between LSR1 and LSR2.
Further details are network technology specific and can be found in Further details are network technology specific and can be found in
[I-D.ietf-detnet-dp-sol-mpls] and [I-D.ietf-detnet-dp-sol-ip]. [DETNET-FRAMEWORK].
4.7. Flow identification at technology borders 4.7. Flow Identification at Technology Borders
This section discusses what needs to be done at technology borders This section discusses what needs to be done at technology borders
including Ethernet as one of the technologies. Flow identification including Ethernet as one of the technologies. Flow identification
for MPLS and IP data planes are described in for MPLS and IP Data Planes are described in [DETNET-MPLS] and
[I-D.ietf-detnet-dp-sol-mpls] and [I-D.ietf-detnet-dp-sol-ip], [DETNET-IP], respectively.
respectively.
4.7.1. Exporting flow identification 4.7.1. Exporting Flow Identification
A DetNet node may need to map specific flows to lower layer flows (or A DetNet node may need to map specific flows to lower-layer flows (or
Streams) in order to provide specific queuing and shaping services Streams) in order to provide specific queuing and shaping services
for specific flows. For example: for specific flows. For example:
o A non-IP, strictly L2 source end system X may be sending multiple * 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
include non-DetNet flows. include non-DetNet flows.
o A router may be sending any number of flows to another router. * A router may be sending any number of flows to another router.
Again, those flows may include DetNet flows with different QoS Again, those flows may include DetNet flows with different QoS
requirements, and may include non-DetNet flows. requirements and may include non-DetNet flows.
o Two routers may be separated by bridges. For these bridges to * Two routers may be separated by bridges. For these bridges to
perform any required per-flow queuing and shaping, they must be perform any required per-flow queuing and shaping, they must be
able to identify the individual flows. able to identify the individual flows.
o A Label Edge Router (LER) may have a Label Switched Path (LSP) set * A Label Edge Router (LER) may have a Label Switched Path (LSP) set
up for handling traffic destined for a particular IP address up for handling traffic destined for a particular IP address
carrying only non-DetNet flows. If a DetNet flow to that same carrying only non-DetNet flows. If a DetNet flow to that same
address is requested, a separate LSP may be needed, in order that address is requested, a separate LSP may be needed in order for
all of the Label Switch Routers (LSRs) along the path to the all of the Label Switch Routers (LSRs) along the path to the
destination give that flow special queuing and shaping. destination to give that flow special queuing and shaping.
The need for a lower-layer node to be aware of individual higher- The need for a lower-layer node to be aware of individual higher-
layer flows is not unique to DetNet. But, given the endless layer flows is not unique to DetNet. But, given the endless
complexity of layering and relayering over tunnels that is available complexity of layering and relayering over tunnels that is available
to network designers, DetNet needs to provide a model for flow to network designers, DetNet needs to provide a model for flow
identification that is better than packet inspection. That is not to identification that is better than packet inspection. That is not to
say that packet inspection to Layer-4 or Layer-5 addresses will not say that packet inspection to Layer 4 or Layer 5 addresses will not
be used, or the capability standardized; but, there are alternatives. be used or the capability standardized; however, there are
alternatives.
A DetNet relay node can connect DetNet flows on different paths using A DetNet relay node can connect DetNet flows on different paths using
different flow identification methods. For example: different flow identification methods. For example:
o A single unicast DetNet flow passing from router A through a * A single unicast DetNet flow passing from router A through a
bridged network to router B may be assigned a TSN Stream bridged network to router B may be assigned a TSN Stream
identifier that is unique within that bridged network. The identifier that is unique within that bridged network. The
bridges can then identify the flow without accessing higher-layer bridges can then identify the flow without accessing higher-layer
headers. Of course, the receiving router must recognize and headers. Of course, the receiving router must recognize and
accept that TSN Stream. accept that TSN Stream.
o A DetNet flow passing from LSR A to LSR B may be assigned a * A DetNet flow passing from LSR A to LSR B may be assigned a
different label than that used for other flows to the same IP different label than that used for other flows to the same IP
destination. destination.
In any of the above cases, it is possible that an existing DetNet In any of the above cases, it is possible that an existing DetNet
flow can be an aggregate carrying multiple other DetNet flows. (Not flow can be an aggregate carrying multiple other DetNet flows (not to
to be confused with DetNet compound vs. member flows.) Of course, be confused with DetNet compound vs. member flows). Of course, this
this requires that the aggregate DetNet flow be provisioned properly requires that the aggregate DetNet flow be provisioned properly to
to carry the aggregated flows. carry the aggregated 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
a complexity that is part of DetNet control models. a complexity that is part of DetNet control models.
4.7.2. Flow attribute mapping between layers 4.7.2. Flow Attribute Mapping between Layers
Forwarding of packets of DetNet flows over multiple technology Forwarding of packets of DetNet flows over multiple technology
domains may require that lower layers are aware of specific flows of domains may require that lower layers are aware of specific flows of
higher layers. Such an "exporting of flow identification" is needed higher layers. Such an "exporting of flow identification" is needed
each time when the forwarding paradigm is changed on the forwarding each time when the forwarding paradigm is changed on the forwarding
path (e.g., two LSRs are interconnected by a L2 bridged domain, path (e.g., two LSRs are interconnected by an L2 bridged domain,
etc.). The three representative forwarding methods considered for etc.). The three representative forwarding methods considered for
deterministic networking are: DetNet are:
o IP routing * IP routing
o MPLS label switching * MPLS label switching
o Ethernet bridging * Ethernet bridging
A packet with corresponding Flow-IDs is illustrated in Figure 9, A packet with corresponding Flow-IDs is illustrated in Figure 9,
which also indicates where each Flow-ID can be added or removed. which also indicates where each Flow-ID can be added or removed.
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 9: 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 * created by a domain-specific function or
o derived from the Flow-ID added to the App-flow. * derived from the Flow-ID added to the App-flow.
The Flow-ID must be unique inside a given domain. Note that the The Flow-ID must be unique inside a 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
some nodes may lack the function to recognize it; that's why the some nodes may lack the function to recognize it; that's why the
additional Flow-ID is added. additional Flow-ID is added.
4.7.3. 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 10 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
<----------------------------------------------- <-----------------------------------------------
+======+ +======+ +======+ +======+
skipping to change at page 35, line 39 skipping to change at line 1591
.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 10: 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 ("ETH-ID") before sending the packet Ethernet-domain-specific Flow-ID ("ETH-ID") before sending the packet
to "ETH-1" node. Ethernet switch "ETH-1" can recognize the data flow to "ETH-1". Ethernet switch "ETH-1" can recognize the data flow
based on the "ETH-ID" and it does forwarding toward "ETH-2". "ETH-2" based on the "ETH-ID", and it does forwarding toward "ETH-2". "ETH-
switches the packet toward the IP router. "IP-1" must be configured 2" switches the packet toward the IP router. "IP-1" must be
to receive the Ethernet Flow-ID specific multicast flow, but (as it configured to receive the Ethernet Flow-ID-specific multicast flow,
is an L3 node) it decodes the data flow ID based on the "L3-ID" but (as it is an L3 node) it decodes the data flow ID based on the
fields of the received packet. "L3-ID" fields of the received packet.
Figure 11 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|
+=======+ +-----+ +-----+ +=======+ +-----+ +=======+ +-----+ +-----+ +=======+ +-----+
skipping to change at page 36, line 29 skipping to change at line 1630
.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 11: 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 ("ETH-ID") before sending the packet to "ETH-1". Ethernet Flow-ID ("ETH-ID") before sending the packet to "ETH-1". Ethernet
switch "ETH-1" can recognize the data flow based on the "ETH-ID" and switch "ETH-1" can recognize the data flow based on the "ETH-ID", and
it does forwarding toward "ETH-2". "ETH-2" switches the packet it does forwarding toward "ETH-2". "ETH-2" switches the packet
toward the MPLS node ("P-2"). "P-2" must be configured to receive toward the MPLS node ("P-2"). "P-2" must be configured to receive
the Ethernet Flow-ID specific multicast flow, but (as it is an MPLS the Ethernet Flow-ID-specific multicast flow, but (as it is an MPLS
node) it decodes the data flow ID based on the "MPLS-ID" fields of node) it decodes the data flow ID based on the "MPLS-ID" fields of
the received packet. the received packet.
One can appreciate from the above example that, when the means used One can appreciate from the above example that, when the means used
for DetNet flow identification is altered or exported, the means for for DetNet flow identification is altered or exported, the means for
encoding the sequence number information must similarly be altered or encoding the sequence number information must similarly be altered or
exported. exported.
4.8. Advertising resources, capabilities and adjacencies 4.8. Advertising Resources, Capabilities, and Adjacencies
Provisioning of DetNet requires knowledge about: Provisioning of DetNet requires knowledge about:
o Details of the DetNet system's capabilities that are required in * Details of the DetNet system's capabilities that are required in
order to accurately allocate that DetNet system's resources, as order to accurately allocate that DetNet system's resources, as
well as other DetNet systems' resources. This includes, for well as other DetNet systems' resources. This includes, for
example, which specific queuing and shaping algorithms are example, which specific queuing and shaping algorithms are
implemented (Section 4.5), the number of buffers dedicated for implemented (Section 4.5), the number of buffers dedicated for
DetNet allocation, and the worst-case forwarding delay and DetNet allocation, and the worst-case forwarding delay and
misordering. misordering.
o The actual state of a DetNet node's DetNet resources. * The actual state of a DetNet node's DetNet resources.
o The identity of the DetNet system's neighbors, and the * The identity of the DetNet system's neighbors and the
characteristics of the link(s) between the DetNet systems, characteristics of the link(s) between the DetNet systems,
including the latency of the links (in nanoseconds). including the latency of the links (in nanoseconds).
4.9. Scaling to larger networks 4.9. Scaling to Larger Networks
Reservations for individual DetNet flows require considerable state Reservations for individual DetNet flows require considerable state
information in each DetNet node, especially when adequate fault information in each DetNet node, especially when adequate fault
mitigation (Section 3.3.2) 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. Such aggregated flows can be viewed by aggregation of DetNet flows. Such aggregated flows can be viewed by
the DetNet nodes' data plane largely as individual DetNet flows. the DetNet nodes' Data Plane largely as individual DetNet flows.
Without such aggregation, the per-relay system may limit the scale of Without such aggregation, the per-relay system may limit the scale of
DetNet networks. Example techniques that may be used include MPLS DetNet networks. Example techniques that may be used include MPLS
hierarchy and IP DiffServ Code Points (DSCPs). hierarchy and IP DiffServ Code Points (DSCPs).
4.10. Compatibility with Layer-2 4.10. 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. defined by IEEE 802.
DetNet enabled end systems and DetNet nodes can be interconnected by DetNet-enabled end systems and DetNet nodes can be interconnected by
sub-networks, i.e., Layer-2 technologies. These sub-networks will sub-networks, i.e., Layer 2 technologies. These sub-networks will
provide DetNet compatible service for support of DetNet traffic. provide DetNet compatible service for support of DetNet traffic.
Examples of sub-network technologies include MPLS TE, 802.1 TSN, and Examples of sub-network technologies include MPLS TE, TSN as defined
a point-to-point OTN link. Of course, multi-layer DetNet systems may by IEEE 802.1, and a point-to-point OTN link. Of course, multilayer
be possible too, where one DetNet appears as a sub-network, and DetNet systems may be possible too, where one DetNet appears as a
provides service to, a higher layer DetNet system. sub-network and provides service to a higher-layer DetNet system.
5. Security Considerations 5. Security Considerations
Security considerations for DetNet are described in detail in Security considerations for DetNet are described in detail in
[I-D.ietf-detnet-security]. This section considers exclusively [DETNET-SECURITY]. This section considers exclusively security
security considerations which are specific to the DetNet considerations that are specific to the DetNet architecture.
architecture.
Security aspects which are unique to DetNet are those whose aim is to Security aspects that are unique to DetNet are those whose aim is to
provide the specific quality of service aspects of DetNet, which are provide the specific QoS aspects of DetNet, which are primarily to
primarily to deliver data flows with extremely low packet loss rates deliver data flows with extremely low packet loss rates and bounded
and bounded end-to-end delivery latency. A DetNet may be implemented end-to-end delivery latency. A DetNet may be implemented using MPLS
using MPLS and/or IP (including both v4 and v6) technologies, and and/or IP (including both v4 and v6) technologies and thus inherits
thus inherits the security properties of those technologies at both the security properties of those technologies at both the Data Plane
the data plane and the control plane. and the Controller Plane.
Security considerations for DetNet are constrained (compared to, for Security considerations for DetNet are constrained (compared to, for
example, the open Internet) because DetNet is defined to operate only example, the open Internet) because DetNet is defined to operate only
within a single administrative domain (see Section 1). The primary within a single administrative domain (see Section 1). The primary
considerations are to secure the request and control of DetNet considerations are to secure the request and control of DetNet
resources, maintain confidentiality of data traversing the DetNet, resources, maintain confidentiality of data traversing the DetNet,
and provide the availability of the DetNet quality of service. and provide the availability of the DetNet QoS.
To secure the request and control of DetNet resources, authentication To secure the request and control of DetNet resources, authentication
and authorization can be used for each device connected to a DetNet and authorization can be used for each device connected to a DetNet
domain, most importantly to network controller devices. Control of a domain, most importantly to network controller devices. Control of a
DetNet network may be centralized or distributed (within a single DetNet network may be centralized or distributed (within a single
administrative domain). In the case of centralized control, administrative domain). In the case of centralized control,
precedent for security considerations as defined for Abstraction and precedent for security considerations as defined for Abstraction and
Control of Traffic Engineered Networks (ACTN) can be found in Control of Traffic Engineered Networks (ACTN) can be found in
[RFC8453], Section 9. In the case of distributed control protocols, Section 9 of [RFC8453]. In the case of distributed control
DetNet security is expected to be provided by the security properties protocols, DetNet security is expected to be provided by the security
of the protocols in use. In any case, the result is that properties of the protocols in use. In any case, the result is that
manipulation of administratively configurable parameters is limited manipulation of administratively configurable parameters is limited
to authorized entities. to authorized entities.
To maintain confidentiality of data traversing the DetNet, To maintain confidentiality of data traversing the DetNet,
application flows can be protected through whatever means is provided application flows can be protected through whatever means is provided
by the underlying technology. For example, encryption may be used, by the underlying technology. For example, encryption may be used,
such as that provided by IPSec [RFC4301] for IP flows and by MACSec such as that provided by IPsec [RFC4301], for IP flows and by MACSec
[IEEE802.1AE-2018] for Ethernet (Layer-2) flows. [IEEE802.1AE] for Ethernet (Layer 2) flows.
DetNet flows are identified on a per-flow basis, which may provide DetNet flows are identified on a per-flow basis, which may provide
attackers with additional information about the data flows (when attackers with additional information about the data flows (when
compared to networks that do not include per-flow identification). compared to networks that do not include per-flow identification).
This is an inherent property of DetNet which has security This is an inherent property of DetNet that has security implications
implications that should be considered when determining if DetNet is that should be considered when determining if DetNet is a suitable
a suitable technology for any given use case. technology for any given use case.
To provide uninterrupted availability of the DetNet quality of To provide uninterrupted availability of the DetNet QoS, provisions
service, provisions can be made against DOS attacks and delay can be made against DoS attacks and delay attacks. To protect
attacks. To protect against DOS attacks, excess traffic due to against DoS attacks, excess traffic due to malicious or
malicious or malfunctioning devices can be prevented or mitigated, malfunctioning devices can be prevented or mitigated, for example,
for example through the use of traffic admission control applied at through the use of traffic admission control applied at the input of
the input of a DetNet domain, as described in Section 3.2.1, and a DetNet domain as described in Section 3.2.1 and through the fault-
through the fault mitigation methods described in Section 3.3.2. To mitigation methods described in Section 3.3.2. To prevent DetNet
prevent DetNet packets from being delayed by an entity external to a packets from being delayed by an entity external to a DetNet domain,
DetNet domain, DetNet technology definition can allow for the DetNet technology definition can allow for the mitigation of man-in-
mitigation of Man-In-The-Middle attacks, for example through use of the-middle attacks, for example, through use of authentication and
authentication and authorization of devices within the DetNet domain. authorization of devices within the DetNet domain.
Because DetNet mechanisms or applications that rely on DetNet can Because DetNet mechanisms or applications that rely on DetNet can
make heavy use of methods that require precise time synchronization, make heavy use of methods that require precise time synchronization,
the accuracy, availability, and integrity of time synchronization is the accuracy, availability, and integrity of time synchronization is
of critical importance. Extensive discussion of this topic can be of critical importance. Extensive discussion of this topic can be
found in [RFC7384]. found in [RFC7384].
DetNet use cases are known to have widely divergent security DetNet use cases are known to have widely divergent security
requirements. The intent of this section is to provide a baseline requirements. The intent of this section is to provide a baseline
for security considerations which are common to all DetNet designs for security considerations that are common to all DetNet designs and
and implementations, without burdening individual designs with implementations, without burdening individual designs with specifics
specifics of security infrastructure which may not be germane to the of security infrastructure that may not be germane to the given use
given use case. Designers and implementers of DetNet systems are case. Designers and implementors of DetNet systems are expected to
expected to take use case specific considerations into account in take use-case-specific considerations into account in their DetNet
their DetNet designs and implementations. designs and implementations.
6. Privacy Considerations 6. Privacy Considerations
DetNet provides a Quality of Service (QoS), and the generic DetNet provides a QoS, and the generic considerations for such
considerations for such mechanisms apply. In particular, such mechanisms apply. In particular, such markings allow for an attacker
markings allow for an attacker to correlate flows or to select to correlate flows or to select particular types of flow for more
particular types of flow for more detailed inspection. detailed inspection.
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.
7. IANA Considerations 7. IANA Considerations
This document does not require an action from IANA. This document has no IANA actions.
8. Acknowledgements
The authors wish to thank Lou Berger, David Black, Stewart Bryant,
Rodney Cummings, Ethan Grossman, Craig Gunther, Marcel Kiessling,
Rudy Klecka, Jouni Korhonen, Erik Nordmark, Shitanshu Shah, Wilfried
Steiner, George Swallow, Michael Johas Teener, Pat Thaler, Thomas
Watteyne, Patrick Wetterwald, Karl Weber, Anca Zamfir, for their
various contributions to this work.
9. Informative References 8. Informative References
[BUFFERBLOAT] [BUFFERBLOAT]
Gettys, J. and K. Nichols, "Bufferbloat: Dark Buffers in Gettys, J. and K. Nichols, "Bufferbloat: Dark Buffers in
the Internet", January 2012. the Internet", DOI 10.1145/2063176.2063196, Communications
of the ACM, Volume 55, Issue 1, January 2012,
[CCAMP] IETF, "Common Control and Measurement Plane Working <https://doi.org/10.1145/2063176.2063196>.
Group",
<https://datatracker.ietf.org/doc/charter-ietf-ccamp/>.
[I-D.ietf-6tisch-architecture] [CCAMP] IETF, "Common Control and Measurement Plane (ccamp)",
Thubert, P., "An Architecture for IPv6 over the TSCH mode October 2019,
of IEEE 802.15.4", draft-ietf-6tisch-architecture-20 (work <https://datatracker.ietf.org/wg/ccamp/charter/>.
in progress), March 2019.
[I-D.ietf-detnet-dp-sol-ip] [DETNET-FRAMEWORK]
Korhonen, J. and B. Varga, "DetNet IP Data Plane Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
Encapsulation", draft-ietf-detnet-dp-sol-ip-02 (work in Bryant, S., and J. Korhonen, "DetNet Data Plane
progress), March 2019. Framework", Work in Progress, Internet-Draft, draft-ietf-
detnet-data-plane-framework-02, 13 September 2019,
<https://tools.ietf.org/html/draft-ietf-detnet-data-plane-
framework-02>.
[I-D.ietf-detnet-dp-sol-mpls] [DETNET-IP]
Korhonen, J. and B. Varga, "DetNet MPLS Data Plane Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
Encapsulation", draft-ietf-detnet-dp-sol-mpls-02 (work in Bryant, S., and J. Korhonen, "DetNet Data Plane: IP", Work
progress), March 2019. in Progress, Internet-Draft, draft-ietf-detnet-ip-01, 1
July 2019,
<https://tools.ietf.org/html/draft-ietf-detnet-ip-01>.
[I-D.ietf-detnet-problem-statement] [DETNET-MPLS]
Finn, N. and P. Thubert, "Deterministic Networking Problem Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
Statement", draft-ietf-detnet-problem-statement-09 (work Bryant, S., and J. Korhonen, "DetNet Data Plane: MPLS",
in progress), December 2018. Work in Progress, Internet-Draft, draft-ietf-detnet-mpls-
01, 1 July 2019,
<https://tools.ietf.org/html/draft-ietf-detnet-mpls-01>.
[I-D.ietf-detnet-security] [DETNET-SECURITY]
Mizrahi, T., Grossman, E., Hacker, A., Das, S., Dowdell, Mizrahi, T., Grossman, E., Hacker, A., Das, S., Dowdell,
J., Austad, H., Stanton, K., and N. Finn, "Deterministic J., Austad, H., Stanton, K., and N. Finn, "Deterministic
Networking (DetNet) Security Considerations", draft-ietf- Networking (DetNet) Security Considerations", Work in
detnet-security-04 (work in progress), March 2019. Progress, Internet-Draft, draft-ietf-detnet-security-05,
29 August 2019, <https://tools.ietf.org/html/draft-ietf-
[I-D.ietf-detnet-use-cases] detnet-security-05>.
Grossman, E., "Deterministic Networking Use Cases", draft-
ietf-detnet-use-cases-20 (work in progress), December
2018.
[IEC62439-3-2016] [IEC-62439-3]
International Electrotechnical Commission (IEC) TC 65/SC IEC, "Industrial communication networks - High
65C - Industrial networks, "IEC 62439-3:2016 Industrial availability automation networks - Part 3: Parallel
communication networks - High availability automation Redundancy Protocol (PRP) and High-availability Seamless
networks - Part 3: Parallel Redundancy Protocol (PRP) and Redundancy (HSR)", TC 65 / SC 65C, IEC 62439-3:2016, March
High-availability Seamless Redundancy (HSR)", 2016, 2016, <https://webstore.iec.ch/publication/24447>.
<https://webstore.iec.ch/publication/24447>.
[IEEE802.1AE-2018] [IEEE802.1AE]
IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC IEEE, "IEEE Standard for Local and metropolitan area
Security (MACsec)", 2018, networks-Media Access Control (MAC) Security", IEEE
802.1AE-2018,
<https://ieeexplore.ieee.org/document/8585421>. <https://ieeexplore.ieee.org/document/8585421>.
[IEEE802.1BA] [IEEE802.1BA]
IEEE Standards Association, "IEEE Std 802.1BA-2011 Audio IEEE, "IEEE Standard for Local and metropolitan area
Video Bridging (AVB) Systems", 2011, networks--Audio Video Bridging (AVB) Systems", IEEE
<https://ieeexplore.ieee.org/document/6032690/>. 802.1BA-2011,
<https://ieeexplore.ieee.org/document/6032690>.
[IEEE802.1CB] [IEEE802.1CB]
IEEE Standards Association, "IEEE Std 802.1CB-2017 Frame IEEE, "IEEE Standard for Local and metropolitan area
Replication and Elimination for Reliability", 2017, networks--Frame Replication and Elimination for
<https://ieeexplore.ieee.org/document/8091139/>. Reliability", DOI 10.1109/IEEESTD.2017.8091139, IEEE
802.1CB-2017, October 2019,
<https://ieeexplore.ieee.org/document/8091139>.
[IEEE802.1Q-2018] [IEEE802.1Q]
IEEE Standards Association, "IEEE Std 802.1Q-2018 Bridges IEEE, "IEEE Standard for Local and Metropolitan Area
and Bridged Networks", 2018, Network--Bridges and Bridged Networks", IEEE 802.1Q-2018,
<https://ieeexplore.ieee.org/document/8403927>. <https://ieeexplore.ieee.org/document/8403927>.
[IEEE802.1Qav] [IEEE802.1Qav]
IEEE Standards Association, "IEEE Std 802.1Qav-2009 IEEE, "IEEE Standard for Local and Metropolitan Area
Bridges and Bridged Networks - Amendment 12: Forwarding Networks - Virtual Bridged Local Area Networks Amendment
and Queuing Enhancements for Time-Sensitive Streams", 12: Forwarding and Queuing Enhancements for Time-Sensitive
2009, <https://ieeexplore.ieee.org/document/5375704/>. Streams", IEEE 802.1Qav-2009,
<https://ieeexplore.ieee.org/document/5375704>.
[IEEE802.1Qbu] [IEEE802.1Qbu]
IEEE Standards Association, "IEEE Std 802.1Qbu-2016 IEEE, "IEEE Standard for Local and metropolitan area
Bridges and Bridged Networks - Amendment 26: Frame networks -- Bridges and Bridged Networks -- Amendment 26:
Preemption", 2016, Frame Preemption", IEEE 802.1Qbu-2016,
<https://ieeexplore.ieee.org/document/7553415/>. <https://ieeexplore.ieee.org/document/7553415>.
[IEEE802.1Qbv] [IEEE802.1Qbv]
IEEE Standards Association, "IEEE Std 802.1Qbv-2015 IEEE, "IEEE Standard for Local and metropolitan area
Bridges and Bridged Networks - Amendment 25: Enhancements networks -- Bridges and Bridged Networks - Amendment 25:
for Scheduled Traffic", 2015, Enhancements for Scheduled Traffic", IEEE 802.1Qbv-2015,
<https://ieeexplore.ieee.org/document/7572858/>. <https://ieeexplore.ieee.org/document/7440741>.
[IEEE802.1Qch] [IEEE802.1Qch]
IEEE Standards Association, "IEEE Std 802.1Qch-2017 IEEE, "IEEE Standard for Local and metropolitan area
Bridges and Bridged Networks - Amendment 29: Cyclic networks--Bridges and Bridged Networks--Amendment 29:
Queuing and Forwarding", 2017, Cyclic Queuing and Forwarding", IEEE 802.1Qch-2017,
<https://ieeexplore.ieee.org/document/7961303/>. <https://ieeexplore.ieee.org/document/7961303>.
[IEEE802.1TSNTG] [IEEE802.1TSNTG]
IEEE Standards Association, "IEEE 802.1 Time-Sensitive IEEE, "Time-Sensitive Networking (TSN) Task Group",
Networking Task Group", <http://www.ieee802.org/1/tsn>. <https://1.ieee802.org/tsn/>.
[IEEE802.3-2018] [IEEE802.3]
IEEE Standards Association, "IEEE Std 802.3-2018 Standard IEEE, "IEEE Standard for Ethernet", IEEE 802.3-2018,
for Ethernet", 2018,
<https://ieeexplore.ieee.org/document/8457469>. <https://ieeexplore.ieee.org/document/8457469>.
[IEEE802.3br] [IEEE802.3br]
IEEE Standards Association, "IEEE Std 802.3br-2016 IEEE, "IEEE Standard for Ethernet Amendment 5:
Standard for Ethernet Amendment 5: Specification and Specification and Management Parameters for Interspersing
Management Parameters for Interspersing Express Traffic", Express Traffic", IEEE 802.3br,
2016, <http://ieeexplore.ieee.org/document/7900321/>. <https://ieeexplore.ieee.org/document/7900321>.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205, Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <https://www.rfc-editor.org/info/rfc2205>. September 1997, <https://www.rfc-editor.org/info/rfc2205>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998, Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<https://www.rfc-editor.org/info/rfc2475>. <https://www.rfc-editor.org/info/rfc2475>.
skipping to change at page 42, line 44 skipping to change at line 1928
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <https://www.rfc-editor.org/info/rfc3550>. July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <https://www.rfc-editor.org/info/rfc4301>. December 2005, <https://www.rfc-editor.org/info/rfc4301>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Element (PCE)-Based Architecture", RFC 4655, Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>. <https://www.rfc-editor.org/info/rfc4655>.
[RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau,
L., and L. Berger, "A Framework for MPLS in Transport
Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010,
<https://www.rfc-editor.org/info/rfc5921>.
[RFC6372] Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport [RFC6372] Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport
Profile (MPLS-TP) Survivability Framework", RFC 6372, Profile (MPLS-TP) Survivability Framework", RFC 6372,
DOI 10.17487/RFC6372, September 2011, DOI 10.17487/RFC6372, September 2011,
<https://www.rfc-editor.org/info/rfc6372>. <https://www.rfc-editor.org/info/rfc6372>.
[RFC6658] Bryant, S., Ed., Martini, L., Swallow, G., and A. Malis, [RFC6658] Bryant, S., Ed., Martini, L., Swallow, G., and A. Malis,
"Packet Pseudowire Encapsulation over an MPLS PSN", "Packet Pseudowire Encapsulation over an MPLS PSN",
RFC 6658, DOI 10.17487/RFC6658, July 2012, RFC 6658, DOI 10.17487/RFC6658, July 2012,
<https://www.rfc-editor.org/info/rfc6658>. <https://www.rfc-editor.org/info/rfc6658>.
skipping to change at page 44, line 25 skipping to change at line 2000
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>. July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for [RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Abstraction and Control of TE Networks (ACTN)", RFC 8453, Abstraction and Control of TE Networks (ACTN)", RFC 8453,
DOI 10.17487/RFC8453, August 2018, DOI 10.17487/RFC8453, August 2018,
<https://www.rfc-editor.org/info/rfc8453>. <https://www.rfc-editor.org/info/rfc8453>.
[RFC8557] Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", RFC 8557, DOI 10.17487/RFC8557, May 2019,
<https://www.rfc-editor.org/info/rfc8557>.
[RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases",
RFC 8578, DOI 10.17487/RFC8578, May 2019,
<https://www.rfc-editor.org/info/rfc8578>.
[TEAS] IETF, "Traffic Engineering Architecture and Signaling [TEAS] IETF, "Traffic Engineering Architecture and Signaling
Working Group", (teas)", October 2019,
<https://datatracker.ietf.org/doc/charter-ietf-teas/>. <https://datatracker.ietf.org/doc/charter-ietf-teas/>.
[TSCH-ARCH]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", Work in Progress, Internet-Draft,
draft-ietf-6tisch-architecture-26, 27 August 2019,
<https://tools.ietf.org/html/draft-ietf-6tisch-
architecture-26>.
Acknowledgements
The authors wish to thank Lou Berger, David Black, Stewart Bryant,
Rodney Cummings, Ethan Grossman, Craig Gunther, Marcel Kiessling,
Rudy Klecka, Jouni Korhonen, Erik Nordmark, Shitanshu Shah, Wilfried
Steiner, George Swallow, Michael Johas Teener, Pat Thaler, Thomas
Watteyne, Patrick Wetterwald, Karl Weber, and Anca Zamfir for their
various contributions to this work.
Authors' Addresses Authors' Addresses
Norman Finn Norman Finn
Huawei Huawei
3101 Rio Way 3101 Rio Way
Spring Valley, California 91977 Spring Valley, California 91977
US United States of America
Phone: +1 925 980 6430 Phone: +1 925 980 6430
Email: norman.finn@mail01.huawei.com Email: nfinn@nfinnconsulting.com
Pascal Thubert Pascal Thubert
Cisco Systems Cisco Systems
Village d'Entreprises Green Side
400, Avenue de Roumanille
Batiment T3 Batiment T3
Biot - Sophia Antipolis 06410 Village d'Entreprises Green Side, 400, Avenue de Roumanille
FRANCE 06410 Biot - Sophia Antipolis
France
Phone: +33 4 97 23 26 34 Phone: +33 4 97 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
Balazs Varga
Balázs Varga
Ericsson Ericsson
Budapest
Magyar tudosok korutja 11 Magyar tudosok korutja 11
Budapest 1117 1117
Hungary Hungary
Email: balazs.a.varga@ericsson.com Email: balazs.a.varga@ericsson.com
Janos Farkas János Farkas
Ericsson Ericsson
Budapest
Magyar tudosok korutja 11 Magyar tudosok korutja 11
Budapest 1117 1117
Hungary Hungary
Email: janos.farkas@ericsson.com Email: janos.farkas@ericsson.com
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