Deterministic Networking Architecture
draft-finn-detnet-architecture-06
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| Authors | Norman Finn , Pascal Thubert , Michael Johas Teener | ||
| Last updated | 2016-07-08 | ||
| Replaced by | draft-ietf-detnet-architecture, RFC 8655 | ||
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draft-finn-detnet-architecture-06
DetNet N. Finn
Internet-Draft P. Thubert
Intended status: Standards Track Cisco
Expires: January 9, 2017 M. Johas Teener
Broadcom
July 8, 2016
Deterministic Networking Architecture
draft-finn-detnet-architecture-06
Abstract
Deterministic Networking (DetNet) provides a capability to carry
specified unicast or multicast data flows for real-time applications
with extremely low data loss rates and bounded latency. Techniques
used include: 1) reserving data plane resources for individual (or
aggregated) DetNet flows in some or all of the intermediate nodes
(e.g. bridges or routers) along the path of the flow; 2) providing
fixed paths for DetNet flows that do not rapidly change with the
network topology; and 3) sequentializing, replicating, tracing and
eliminating duplicate packets at various points to ensure delivery of
each packet over at least one path. The capabilities can be managed
by configuration, or by manual or automatic network management.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 9, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Terms used in this document . . . . . . . . . . . . . . . 4
2.2. IEEE 802 TSN to DetNet dictionary . . . . . . . . . . . . 6
3. Providing the DetNet Quality of Service . . . . . . . . . . . 6
3.1. Zero Congestion Loss . . . . . . . . . . . . . . . . . . 8
3.2. Explicit routes . . . . . . . . . . . . . . . . . . . . . 8
3.3. Jitter Reduction . . . . . . . . . . . . . . . . . . . . 9
3.4. Packet Replication and Elimination . . . . . . . . . . . 10
4. DetNet Architecture . . . . . . . . . . . . . . . . . . . . . 11
4.1. Traffic Engineering for DetNet . . . . . . . . . . . . . 11
4.1.1. The Application Plane . . . . . . . . . . . . . . . . 12
4.1.2. The Controller Plane . . . . . . . . . . . . . . . . 12
4.1.3. The Network Plane . . . . . . . . . . . . . . . . . . 13
4.2. DetNet flows . . . . . . . . . . . . . . . . . . . . . . 14
4.2.1. Source guarantees . . . . . . . . . . . . . . . . . . 14
4.2.2. Incomplete Networks . . . . . . . . . . . . . . . . . 15
4.3. Queuing, Shaping, Scheduling, and Preemption . . . . . . 15
4.4. Coexistence with normal traffic . . . . . . . . . . . . . 16
4.5. Fault Mitigation . . . . . . . . . . . . . . . . . . . . 17
4.6. Representative Protocol Stack Model . . . . . . . . . . . 17
4.7. Exporting flow identification . . . . . . . . . . . . . . 19
4.8. Advertising resources, capabilities and adjacencies . . . 21
4.9. Provisioning model . . . . . . . . . . . . . . . . . . . 21
4.9.1. Centralized Path Computation and Installation . . . . 21
4.9.2. Distributed Path Setup . . . . . . . . . . . . . . . 22
4.10. Scaling to larger networks . . . . . . . . . . . . . . . 22
4.11. Connected islands vs. networks . . . . . . . . . . . . . 22
5. Compatibility with Layer-2 . . . . . . . . . . . . . . . . . 23
6. Open Questions . . . . . . . . . . . . . . . . . . . . . . . 23
6.1. DetNet flow identification and sequencing . . . . . . . . 23
6.2. Flat vs. hierarchical control . . . . . . . . . . . . . . 24
6.3. Peer-to-peer reservation protocol . . . . . . . . . . . . 24
6.4. Wireless media interactions . . . . . . . . . . . . . . . 25
6.5. Packet encoding for loss prevention . . . . . . . . . . . 25
7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
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8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 26
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
11. Access to IEEE 802.1 documents . . . . . . . . . . . . . . . 26
12. Informative References . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
1. Introduction
Deterministic Networking (DetNet) is a service that can be offered by
a network to data flows (DetNet flows) that that are limited, at
their source, to a maximum data rate specified by that source.
DetNet provides these flows extremely low packet loss rates and
assured maximum end-to-end delivery latency. This is accomplished by
dedicating network resources such as link bandwidth and buffer space
to DetNet flows and/or classes of DetNet flows, and by replicating
packets along multiple paths. Unused reserved resources are
available to non-DetNet packets.
The Deterministic Networking Problem Statement
[I-D.ietf-detnet-problem-statement] introduces Deterministic
Networking, and Deterministic Networking Use Cases
[I-D.ietf-detnet-use-cases] summarizes the need for it.
A goal of DetNet is a converged network in all respects. That is,
the presence of DetNet flows does not preclude non-DetNet flows, and
the benefits offered DetNet flows should not, except in extreme
cases, prevent existing QoS mechanisms from operating in a normal
fashion, subject to the bandwidth required for the DetNet flows. A
single source-destination pair can trade both DetNet and non-DetNet
flows. End systems and applications need not instantiate special
interfaces for DetNet flows. Networks are not restricted to certain
topologies; connectivity is not restricted. Any application that
generates a data flow that can be usefully characterized as having a
maximum bandwidth should be able to take advantage of DetNet, as long
as the necessary resources can be reserved. Reservations can be made
by the application itself, via network management, by an applications
controller, or by other means.
Many applications of interest to Deterministic Networking require the
ability to synchronize the clocks in end systems to a sub-microsecond
accuracy. Some of the queue control techniques defined in
Section 4.3 also require time synchronization among relay and transit
nodes. The means used to achieve time synchronization are not
addressed in this document. DetNet should accommodate various
synchronization techniques and profiles that are defined elsewhere to
solve exchange time in different market segments.
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The present document is an individual contribution, but it is
intended by the authors for adoption by the DetNet working group.
2. Terminology
2.1. Terms used in this document
The following special terms are used in this document in order to
avoid the assumption that a given element in the architecture does or
does not have Internet Protocol stack, functions as a router, bridge,
firewall, or otherwise plays a particular role at Layer-2 or higher.
destination
An end system capable of receiving a DetNet flow.
DetNet domain
The portion of a network that is DetNet aware. It includes
end systems and other DetNet nodes.
DetNet flow
A DetNet flow is a sequence of packets to which the DetNet
service is to be applied. It can be limited by the source in
its maximum packet size and transmission rate, and can thus
be provided congestion-free delivery by the network.
DetNet compound flow and DetNet member flow
A DetNet compound flow is a DetNet flow that has been
separated into multiple duplicate DetNet member flows, which
are eventually merged back into a single DetNet compound
flow, at the DetNet transport layer. "Compound" and "member"
are strictly relative to each other, not absolutes; a DetNet
compound flow comprising multiple DetNet member flows can, in
turn, be a member of a higher-order compound.
DetNet intermediate node
A DetNet relay node or transit node.
DetNet relay edge node
An instance of a DetNet relay node that includes a service
layer proxy function for DetNet loss prevention (e.g. packet
sequencing and/or elimination) for one or more end systems,
analogous to a Label Edge Router (LER).
end system
Commonly called a "host" or "node" in IETF documents, and an
"end station" is IEEE 802 documents. End systems of interest
to this document are either sources or destinations of DetNet
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flows. And end system may or may not be DetNet transport
layer aware or DetNet service layer aware.
link
A connection between two DetNet nodes. It may be composed of
a physical link or a sub-network technology that can provide
appropriate traffic delivery for DetNet flows.
DetNet node
A DetNet aware end system, transit node, or relay node.
"DetNet" may be omitted in some text.
Detnet relay node
A DetNet service layer function that interconnects different
DetNet transport layer protocols or networks (instances) to
perform packet replication and elimination (Section 3.4. A
DetNet relay node typically incorporates DetNet transport
layer functions as well, in which case it is collocated with
a transit node, such as a bridge, a router, a Label Switch
Router (LSR), a firewall, or any other system that
participates in the DetNet service layer.
reservation
A trail of configuration between source to destination(s)
through transit nodes and subnets associated with a DetNet
flow, required to deliver the benefits of DetNet.
DetNet service layer
The layer at which loss prevention services such as packet
sequencing and the elimination part of replication and
elimination (Section 3.4) are performed.
source
An end system capable of sourcing a DetNet flow.
DetNet transit node
A node operating at the DetNet transport layer, that utilizes
link layer and/or network layer switching across multiple
links and/or sub-networks to provide paths for DetNet service
layer functions. An MPLS LSR is an example of a DetNet
transit node.
DetNet transport layer
The layer that splits and merges Detnet flows for packet
replication and elimination (Section 3.4).
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2.2. IEEE 802 TSN to DetNet dictionary
This section also serves as a dictionary for translating from the
terms used by the IEEE 802 Time-Sensitive Networking (TSN) Task Group
to those of the DetNet WG.
Listener
The IEEE 802 term for a destination of a DetNet flow.
relay system
The IEEE 802 term for a DetNet intermediate node.
Stream
The IEEE 802 term for a DetNet flow.
Talker
The IEEE 802 term for the source of a DetNet flow.
3. Providing the DetNet Quality of Service
The DetNet Quality of Service can be expressed in terms of:
o Minimum and maximum end-to-end latency from source to destination;
timely delivery and jitter avoidance derive from these constraints
o Probability of loss of a packet, under various assumptions as to
the operational states of the nodes and links. A derived property
is whether it is acceptable to deliver a duplicate packet, which
is an inherent risk in highly reliable and/or broadcast
transmissions
It is a distinction of DetNet that it is concerned solely with worst-
case values for the end-to-end latency. Average, mean, or typical
values are of no interest, because they do not affect the ability of
a real-time system to perform its tasks. In general, a trivial
priority-based queuing scheme will give better average latency to a
data flow than DetNet, but of course, the worst-case latency can be
essentially unbounded.
Three techniques are used by DetNet to provide these qualities of
service:
o Bandwidth reservation and enforcement (Section 3.1).
o Explicit routes (Section 3.2).
o A DetNet loss protection mechanism.
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The DetNet techniques are meant to address both of the DetNet QoS
requirements (latency and packet loss). Given that DetNet nodes have
a finite amount of buffer space, zero congestion loss necessarily
results in a maximum end-to-end latency. It also addresses the
largest contribution to packet loss, which is buffer congestion.
After congestion, the most important contributions to packet loss are
typically from random media errors and equipment failures.
Additional mechanisms, such as encoding schemes and/or data
replication techniques are needed. The mechanisms employed are
constrained by the requirement to meet the users' latency
requirements. Packet replication and elimination (Section 3.4) is
one possible mechanism to provide DetNet loss protection.
These three techniques can be applied independently, giving eight
possible combinations, including none (no DetNet), although some
combinations are of wider utility than others. This separation keeps
the protocol stack coherent and maximizes interoperability with
existing and developing standards in this (IETF) and other Standards
Development Organizations. Some examples of typical expected
combinations:
o Explicit routes (a) plus packet replication (b) are exactly the
techniques employed by [HSR-PRP]. Explicit routes are achieved by
limiting the physical topology of the network, and the
sequentialization, replication, and duplicate elimination are
facilitated by packet tags added at the front or the end of
Ethernet frames.
o Zero congestion loss (a) alone is is offered by IEEE 802.1 Audio
Video bridging [IEEE802.1BA-2011]. As long as the network suffers
no failures, zero congestion loss can be achieved through the use
of a reservation protocol (MSRP), shapers in every bridge, and a
bit of network calculus.
o Using all three together gives maximum protection.
There are, of course, simpler methods available (and employed, today)
to achieve levels of latency and packet loss that are satisfactory
for many applications. Prioritization and over-provisioning is one
such technique. However, these methods generally work best in the
absence of any significant amount of non-critical traffic in the
network (if, indeed, such traffic is supported at all), or work only
if the critical traffic constitutes only a small portion of the
network's theoretical capacity, or work only if all systems are
functioning properly, or in the absence of actions by end systems
that disrupt the network's operations.
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There are any number of methods in use, defined, or in progress for
accomplishing each of the above techniques. It is expected that this
DetNet Architecture will assist various vendors, users, and/or
"vertical" Standards Development Organizations (dedicated to a single
industry) to make selections among the available means of
implementing DetNet networks.
3.1. Zero Congestion Loss
The primary means by which DetNet achieves its QoS assurances is to
completely eliminate congestion at an output port as a cause of
packet loss. Given that a DetNet flow cannot be throttled, this can
be achieved only by the provision of sufficient buffer storage at
each hop through the network to ensure that no packets are dropped
due to a lack of buffer storage.
Ensuring adequate buffering requires, in turn, that the source, and
every intermediate node along the path to the destination (or nearly
every node -- see Section 4.2.2) be careful to regulate its output to
not exceed the data rate for any DetNet flow, except for brief
periods when making up for interfering traffic. Any packet sent
ahead of its time potentially adds to the number of buffers required
by the next hop, and may thus exceed the resources allocated for a
particular DetNet flow.
The low-level mechanisms described in Section 4.3 provide the
necessary regulation of transmissions by an end system or
intermediate node to ensure zero congestion loss. The reservation of
the bandwidth and buffers for a DetNet flow requires the provisioning
described in Section 4.9. A DetNet node may have other resources
requiring allocation and/or scheduling, that might otherwise be over-
subscribed and trigger the rejection of a reservation.
3.2. Explicit routes
In networks controlled by typical peer-to-peer protocols such as IEEE
802.1 ISIS bridged networks or IETF OSPF routed networks, a network
topology event in one part of the network can impact, at least
briefly, the delivery of data in parts of the network remote from the
failure or recovery event. Thus, even redundant paths through a
network, if controlled by the typical peer-to-peer protocols, do not
eliminate the chances of brief losses of contact.
Many real-time networks rely on physical rings or chains of two-port
devices, with a relatively simple ring control protocol. This
supports redundant paths with a minimum of wiring. As an additional
benefit, ring topologies can often utilize different topology
management protocols than those used for a mesh network, with a
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consequent reduction in the response time to topology changes. Of
course, this comes at some cost in terms of increased hop count, and
thus latency, for the typical path.
In order to get the advantages of low hop count and still ensure
against even very brief losses of connectivity, DetNet employs
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
network topology events. When combined with a loss prevention
mechanism such as packet replication and elimination (Section 3.4),
this results in a high likelihood of continuous connectivity.
Explicit routes are commonly used in MPLS TE LSPs.
3.3. Jitter Reduction
A core objective of DetNet is to enable the convergence of Non-IP
networks onto a common network infrastructure. This requires the
accurate emulation of currently deployed mission-specific networks,
which typically rely on point-to-point analog (e.g. 4-20mA
modulation) and serial-digital cables (or buses) for highly reliable,
synchronized and jitter-free communications. While the latency of
analog transmissions is basically the speed of light, legacy serial
links are usually slow (in the order of Kbps) compared to, say, GigE,
and some latency is usually acceptable. What is not acceptable is
the introduction of excessive jitter, which may, for instance, affect
the stability of control systems.
Applications that are designed to operate on serial links usually do
not provide services to recover the jitter, because jitter simply
does not exists there. Streams of information are expected to be
delivered in-order and the precise time of reception influences the
processes. In order to converge such existing applications, there is
a desire to emulate all properties of the serial cable, such as clock
transportation, perfect flow isolation and fixed latency. While
minimal jitter (in the form of specifying minimum, as well as
maximum, end-to-end latency) is supported by DetNet, there are
practical limitations on packet-based networks in this regard. In
general, users are encouraged to use, instead of, "do this when you
get the packet," a combination of:
o Sub-microsecond time synchronization among all source and
destination end systems, and
o Time-of-execution fields in the application packets.
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3.4. Packet Replication and Elimination
After congestion loss has been eliminated, the most important causes
of packet loss are random media and/or memory faults, and equipment
failures. Both causes of packet loss can be greatly reduced by
apreading the data in a packet over multiple transmissions. One such
method is described in this section, which sends the same packets
over multiple paths. Other methods, such as ones that use encoding
methods to combine the information in multiple packets, may also be
applicable. See Section 6.5.
Packet replication and elimination, also known as seamless redundancy
[HSR-PRP], or 1+1 hitless protection, is a function of the DetNet
service layer. It involves three capabilities:
o Replicating these packets into multiple DetNet member flows and,
typically, sending them along at least two different paths to the
destination(s), e.g. over the explicit routes of Section 3.2.
o Providing sequencing information, once, at or near the source, to
the packets of a DetNet compound flow. This may be done by adding
a sequence number or time stamp as part of DetNet, or may be
inherent in the packet, e.g. in a transport protocol, or
associated to other physical properties such as the precise time
(and radio channel) of reception of the packet.
o Eliminating duplicated packets. This may be done at any step
along the path to save network resources further down, in
particular if multiple Replication points exist. But the most
common case is to perform this operation at the very edge of the
DetNet network, preferably in or near the receiver.
This function is a "hitless" version of, e.g., the 1+1 linear
protection in [RFC6372]. That is, instead of switching from one flow
to the other when a failure of a flow is detected, DetNet combines
both flows, and performs a packet-by-packet selection of which to
discard, based on sequence number.
In the simplest case, this amounts to replicating each packet in a
source that has two interfaces, and conveying them through the
network, along separate paths, to the similarly dual-homed
destinations, that discard the extras. This ensures that one path
(with zero congestion loss) remains, even if some intermediate node
fails. The sequence numbers can also be used for loss detection and
for re-ordering.
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Alternatively, Detnet relay nodes in the network can provide
replication and elimination facilities at various points in the
network, so that multiple failures can be accommodated.
This is shown in the following figure, where the two relay nodes each
replicate (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 (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 get through. Furthermore, two links can
fail, as long as they are in different segments of the network.
Packet replication and elimination
> > > > > > > > > relay > > > > > > > >
> /------------+ R node E +------------\ >
> / v + ^ \ >
end R + v | ^ + E end
system + v | ^ + system
> \ v + ^ / >
> \------------+ R relay E +-----------/ >
> > > > > > > > > node > > > > > > > >
Figure 1
Note that packet replication and elimination does not react to and
correct failures; it is entirely passive. Thus, intermittent
failures, mistakenly created packet filters, or misrouted data is
handled just the same as the equipment failures that are detected
handled by typical routing and bridging protocols.
When combining member flows that take different-length paths through
the network, and which are also guaranteed a worst-case latency by
packet shaping, a merge point may require extra buffering to equalize
the delays over the different paths. This equalization ensures that
the resultant compound flow will not exceed its contracted bandwidth
even after one or the other of the paths is restored after a failure.
4. DetNet Architecture
4.1. Traffic Engineering for DetNet
Traffic Engineering Architecture and Signaling (TEAS) [TEAS] defines
traffic-engineering architectures for generic applicability across
packet and non-packet networks. From TEAS perspective, Traffic
Engineering (TE) refers to techniques that enable operators to
control how specific traffic flows are treated within their networks.
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Because if its very nature of establishing explicit optimized paths,
Deterministic Networking can be seen as a new, specialized branch of
Traffic Engineering, and inherits its architecture with a separation
into planes.
The Deterministic Networking architecture is thus composed of three
planes, a (User) Application Plane, a Controller Plane, and a Network
Plane, which echoes that of Figure 1 of Software-Defined Networking
(SDN): Layers and Architecture Terminology [RFC7426].:
4.1.1. The Application Plane
Per [RFC7426], the Application Plane includes both applications and
services. In particular, the Application Plane incorporates the User
Agent, a specialized application that interacts with the end user /
operator and performs requests for Deterministic Networking services
via an abstract Flow Management Entity, (FME) which may or may not be
collocated with (one of) the end systems.
At the Application Plane, a management interface enables the
negotiation of flows between end systems. An abstraction of the flow
called a Traffic Specification (TSpec) provides the representation.
This abstraction is used to place a reservation over the (Northbound)
Service Interface and within the Application plane. It is associated
with an abstraction of location, such as IP addresses and DNS names,
to identify the end systems and eventually specify intermediate
nodes.
4.1.2. The Controller Plane
The Controller Plane corresponds to the aggregation of the Control
and Management Planes in [RFC7426], though Common Control and
Measurement Plane (CCAMP) [CCAMP] makes an additional distinction
between management and measurement. When the logical separation of
the Control, Measurement and other Management entities is not
relevant, the term Controller Plane is used for simplicity to
represent them all, and the term controller refers to any device
operating in that plane, whether is it a Path Computation entity or a
Network Management entity (NME). The Path Computation Element (PCE)
[PCE] is a core element of a controller, in charge of computing
Deterministic paths to be applied in the Network Plane.
A (Northbound) Service Interface enables applications in the
Application Plane to communicate with the entities in the Controller
Plane.
One or more PCE(s) collaborate to implement the requests from the FME
as Per-Flow Per-Hop Behaviors installed in the intermediate nodes for
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each individual flow. The PCEs place each flow along a deterministic
sequence of intermediate nodes so as to respect per-flow constraints
such as security and latency, and optimize the overall result for
metrics such as an abstract aggregated cost. The deterministic
sequence can typically be more complex than a direct sequence and
include redundancy path, with one or more packet replication and
elimination points.
4.1.3. The Network Plane
The Network Plane represents the network devices and protocols as a
whole, regardless of the Layer at which the network devices operate.
It includes Forwarding Plane (data plane), Application, and
Operational Plane (control plane) aspects.
The network Plane comprises the Network Interface Cards (NIC) in the
end systems, which are typically IP hosts, and intermediate nodes,
which are typically IP routers and switches. Network-to-Network
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
Controller Plane to communicate with devices in the Network Plane.
This interface leverages and extends TEAS to describe the physical
topology and resources in the Network Plane.
Flow Management Entity
End End
System System
-+-+-+-+-+-+-+ Northbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
PCE PCE PCE PCE
-+-+-+-+-+-+-+ Southbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
intermediate intermed. intermed. intermed.
Node Node Node Node
NIC NIC
intermediate intermed. intermed. intermed.
Node Node Node Node
Figure 2
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The intermediate nodes (and eventually the end systems NIC) expose
their capabilities and physical resources to the controller (the
PCE), and update the PCE with their dynamic perception of the
topology, across the Southbound Interface. In return, the PCE(s) set
the per-flow paths up, providing a Flow Characterization that is more
tightly coupled to the intermediate node Operation than a TSpec.
At the Network plane, intermediate nodes may exchange information
regarding the state of the paths, between adjacent systems and
eventually with the end systems, and forward packets within
constraints associated to each flow, or, when unable to do so,
perform a last resort operation such as drop or declassify.
This specification focuses on the Southbound interface and the
operation of the Network Plane.
4.2. DetNet flows
4.2.1. Source guarantees
DetNet flows can by synchronous or asynchronous. In synchronous
DetNet flows, at least the intermediate nodes (and possibly the end
systems) are closely time synchronized, typically to better than 1
microsecond. By transmitting packets from different DetNet flows or
classes of DetNet flows at different times, using repeating schedules
synchronized among the intermediate nodes, resources such as buffers
and link bandwidth can be shared over the time domain among different
DetNet flows. There is a tradeoff among techniques for synchronous
DetNet flows between the burden of fine-grained scheduling and the
benefit of reducing the required resources, especially buffer space.
In contrast, asynchronous DetNet flows are not coordinated with a
fine-grained schedule, so relay and end systems must assume worst-
case interference among DetNet flows contending for buffer resources.
Asynchronous DetNet flows are characterized by:
o A maximum packet size;
o An observation interval; and
o A maximum number of transmissions during that observation
interval.
These parameters, together with knowledge of the protocol stack used
(and thus the size of the various headers added to a packet), limit
the number of bit times per observation interval that the DetNet flow
can occupy the physical medium.
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The source promises that these limits will not be exceeded. If the
source transmits less data than this limit allows, the unused
resources such as link bandwidth can be made available by the system
to non-DetNet packets. However, making those resources available to
DetNet packets in other DetNet flows would serve no purpose. Those
other DetNet flows have their own dedicated resources, on the
assumption that all DetNet flows can use all of their resources over
a long period of time.
Note that there is no provision in DetNet for throttling DetNet flows
(reducing the transmission rate via feedback); the assumption is that
a DetNet flow, to be useful, must be delivered in its entirety. That
is, while any useful application is written to expect a certain
number of lost packets, the real-time applications of interest to
DetNet demand that the loss of data due to the network is
extraordinarily infrequent.
Although DetNet strives to minimize the changes required of an
application to allow it to shift from a special-purpose digital
network to an Internet Protocol network, one fundamental shift in the
behavior of network applications is impossible to avoid: the
reservation of resources before the application starts. In the first
place, a network cannot deliver finite latency and practically zero
packet loss to an arbitrarily high offered load. Secondly, achieving
practically zero packet loss for unthrottled (though bandwidth
limited) DetNet flows means that bridges and routers have to dedicate
buffer resources to specific DetNet flows or to classes of DetNet
flows. The requirements of each reservation have to be translated
into the parameters that control each system's queuing, shaping, and
scheduling functions and delivered to the hosts, bridges, and
routers.
4.2.2. Incomplete Networks
The presence in the network of transit nodes or subnets that are not
fully capable of offering DetNet services complicates the ability of
the intermediate nodes and/or controller to allocate resources, as
extra buffering, and thus extra latency, must be allocated at points
downstream from the non-DetNet intermediate node for a DetNet flow.
4.3. Queuing, Shaping, Scheduling, and Preemption
As described above, DetNet achieves its aims by reserving bandwidth
and buffer resources at every hop along the path of the DetNet flow.
The reservation itself is not sufficient, however. Implementors and
users of a number of proprietary and standard real-time networks have
found that standards for specific data plane techniques are required
to enable these assurances to be made in a multi-vendor network. The
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fundamental reason is that latency variation in one system results in
the need for extra buffer space in the next-hop system(s), which in
turn, increases the worst-case per-hop latency.
Standard queuing and transmission selection algorithms allow a
central controller to compute the latency contribution of each
transit node to the end-to-end latency, to compute the amount of
buffer space required in each transit node for each incremental
DetNet flow, and most importantly, to translate from a flow
specification to a set of values for the managed objects that control
each relay or end system. The IEEE 802 has specified (and is
specifying) a set of queuing, shaping, and scheduling algorithms that
enable each transit node (bridge or router), and/or a central
controller, to compute these values. These algorithms include:
o A credit-based shaper [IEEE802.1Q-2014] Clause 34.
o Time-gated queues governed by a rotating time schedule,
synchronized among all transit nodes [IEEE802.1Qbv].
o Synchronized double (or triple) buffers driven by synchronized
time ticks. [IEEE802.1Qch].
o Pre-emption of an Ethernet packet in transmission by a packet with
a more stringent latency requirement, followed by the resumption
of the preempted packet [IEEE802.1Qbu], [IEEE802.3br].
While these techniques are currently embedded in Ethernet and
bridging standards, we can note that they are all, except perhaps for
packet preemption, equally applicable to other media than Ethernet,
and to routers as well as bridges.
4.4. Coexistence with normal traffic
A DetNet network supports the dedication of a high proportion (e.g.
75%) of the network bandwidth to DetNet flows. But, no matter how
much is dedicated for DetNet flows, it is a goal of DetNet to coexist
with existing Class of Service schemes (e.g., DiffServ). It is also
important that non-DetNet traffic not disrupt the DetNet flow, of
course (see Section 4.5 and Section 7). For these reasons:
o Bandwidth (transmission opportunities) not utilized by a DetNet
flow are available to non-DetNet packets (though not to other
DetNet flows).
o DetNet flows can be shaped or scheduled, in order to ensure that
the highest-priority non-DetNet packet also is ensured a worst-
case latency (at any given hop).
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o When transmission opportunities for DetNet flows are scheduled in
detail, then the algorithm constructing the schedule should leave
sufficient opportunities for non-DetNet packets to satisfy the
needs of the users of the network. Detailed scheduling can also
permit the time-shared use of buffer resources by different DetNet
flows.
Ideally, the net effect of the presence of DetNet flows in a network
on the non-DetNet packets is primarily a reduction in the available
bandwidth.
4.5. Fault Mitigation
One key to building robust real-time systems is to reduce the
infinite variety of possible failures to a number that can be
analyzed with reasonable confidence. DetNet aids in the process by
providing filters and policers to detect DetNet packets received on
the wrong interface, or at the wrong time, or in too great a volume,
and to then take actions such as discarding the offending packet,
shutting down the offending DetNet flow, or shutting down the
offending interface.
It is also essential that filters and service remarking be employed
at the network edge to prevent non-DetNet packets from being mistaken
for DetNet packets, and thus impinging on the resources allocated to
DetNet packets.
There exist techniques, at present and/or in various stages of
standardization, that can perform these fault mitigation tasks that
deliver a high probability that misbehaving systems will have zero
impact on well-behaved DetNet flows, except of course, for the
receiving interface(s) immediately downstream of the misbehaving
device. Examples of such techniques include traffic policing
functions (e.g. [RFC2475]) and separating flows into per-flow rate-
limited queues.
4.6. Representative Protocol Stack Model
Figure 3 illustrates a conceptual DetNet data plane layering model.
One may compare it to that in [IEEE802.1CB], Annex C, a work in
progress.
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DetNet data plane protocol stack
| packets going | ^ packets coming ^
v down the stack v | up the stack |
+----------------------+ +-----------------------+
| source | | destination |
+----------------------+ +-----------------------+
| Service layer | | Service layer |
| Packet sequencing | | Duplicate elimination |
+----------------------+ +-----------------------+
| Transport layer | | Transport layer |
| flow duplication | | flow merging |
+----------------------+ +-----------------------+
| Subnet services | | Subnet services |
+----------------------+ +-----------------------+
| Lower layers | | Lower layers |
+----------------------+ +-----------------------+
v ^
\_________________________/
Figure 3
Not all layers are required for any given application, or even for
any given network. The layers are, from top to bottom:
Application
Shown as "source" and "destination" in the diagram.
OAM
Operations, Administration, and Maintenance leverages in-band
and out-of-and signaling that validates whether the service
is effectively obtained within QoS constraints. It is not
shown in Figure 3; OAM may reside in any number of the
layers. OAM can involve specific tagging added in the
packets for tracing implementation or network configuration
errors; traceability enables to find whether a packet is a
replica, which relay node performed the replication, and
which segment was intended for the replica.
Packet sequencing
As part of DetNet loss prevention, supplies the sequence
number for providing DetNet loss prevention via packet
replication and elimination (Section 3.4) for packets going
down the stack. Peers with Duplicate elimination. This
layer is not needed if a higher-layer transport protocol is
expected to perform any packet sequencing and duplicate
elimination required by the DetNet flow duplication.
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Duplicate elimination
As part of the DetNet service layer, based on the sequenced
number supplied by its peer, packet sequencing, Duplicate
elimination discards any duplicate packets generated by
DetNet flow duplication. It can operate on member flows,
compound flows, or both. The duplication may also be
inferred from other information such as the precise time of
reception in a scheduled network. The duplicate elimination
layer may also perform resequencing of packets to restore
packet order in a flow that was disrupted by the loss of
packets on one or another of the multiple paths taken.
Network flow duplication
As part of DetNet loss prevention, replicates packets going
down the stack, that belong to a DetNet compound flow, into
two or more DetNet member flows. Note that this function is
separate from packet sequencing. Flow duplication can be an
explicit duplication and remarking of packets, or can be
performed by, for example, techniques similar to ordinary
multicast replication. Peers with DetNet flow merging.
Network flow merging
As part of the DetNet network layer, merges DetNet member
flows together for packets coming up the stack belonging to a
specific DetNet compound flow. Peers with DetNet flow
duplication. DetNet flow merging, together with packet
sequencing, duplicate elimination, and DetNet flow
duplication, performs packet replication and elimination
(Section 3.4).
Queuing shaping scheduling
The subnet services layer provides the latency and congestion
loss parts of the DetNet QoS. See Section 4.3. Note that
additional shaping elements may be provided for DetNet edge
nodes in order to precondition potentially malformed DetNet
flows from a source end system. Note also that these subnet
services are typically required of DetNet intermediate nodes
that are connected by direct links, not just those connected
by subnets such as bridged LANs.
4.7. Exporting flow identification
An interesting feature of DetNet, and one that invites
implementations that can be accused of "layering violations", is the
need for lower layers to be aware of specific flows at higher layers,
in order to provide specific queuing and shaping services for
specific flows. For example:
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o A non-IP, strictly L2 source end system X may be sending multiple
flows to the same L2 destination end system Y. Those flows may
include DetNet flows with different QoS requirements, and may
include non-DetNet flows.
o A router may be sending any number of flows to another router.
Again, those flows may include DetNet flows with different QoS
requirements, and may include non-DetNet flows.
o Two routers may be separated by bridges. For these bridges to
perform any required per-flow queuing and shaping, they must be
able to identify the individual flows.
o A Label Edge Router (LERs) may have a Label Switched Path (LSP)
set up for handling traffic destined for a particular IP address
carrying only non-DetNet flows. If a DetNet flow to that same
address is requested, a separate LSP may be needed, in order that
all of the Label Switch Routers (LSRs) along the path to the
destination give that flow special queuing and shaping.
The need for a lower-level DetNet node to be aware of individual
higher-layer flows is not unique to DetNet. But, given the endless
complexity of layering and relayering over tunnels that is available
to network designers, DetNet needs to provide a model for flow
identification that is at least somewhat better than deep packet
inspection. That is not to say that deep inspection will not be
used, or the capability standardized; but, there are alternatives.
The main alternative is the sequence encode/decode and, particularly,
the DetNet flow encoding/decoding layers shown in Figure 3. In this
model, at the time a DetNet flow is established and the resources for
it reserved, an alternate encapsulation of the DetNet flow at the
lower layer is requested and established. For example:
o A single unicast DetNet flow passing from router A through a
bridged network to router B may be assigned a {VLAN, multicast
destination MAC address} pair that is unique within that bridged
network. The bridges can then identify the flow without accessing
higher-layer headers. Of course, the receiving router must
recognize and accept that multicast MAC address.
o 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
destination.
The DetNet flow encoding/decoding layers shown in Figure 3 perform
the required alternate encapsulations. For example, one could place
a DetNet flow encoding shim between the Address Resolution Protocol
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(ARP) layer and the MAC layer, which alters the {VLAN, MAC address}
pair to identify particular streams going up and down the stack, so
that the layers above the shim need no alteration to service DetNet
flows.
In any of the above cases, it is possible that an existing DetNet
flow can be used as a carrier for multiple DetNet sub-flows. (Not to
be confused with DetNet compound vs. member flows.) Of course, this
requires that the aggregate DetNet flow be provisioned properly to
carry the sub-flows.
Thus, rather than deep packet inspection, there is the option to
export higher-layer information to the lower layer. The requirement
to support one or the other method for flow identification (or both)
is the essential complexity that DetNet brings to existing control
plane models.
4.8. Advertising resources, capabilities and adjacencies
There are three classes of information that a central controller or
decentralized control plane needs to know that can only be obtained
from the end systems and/or transit nodes in the network. When using
a peer-to-peer control plane, some of this information may be
required by a system's neighbors in the network.
o Details of the system's capabilities that are required in order to
accurately allocate that system's resources, as well as other
systems' resources. This includes, for example, which specific
queuing and shaping algorithms are implemented (Section 4.3), the
number of buffers dedicated for DetNet allocation, and the worst-
case forwarding delay.
o The dynamic state of an end or transit node's DetNet resources.
o The identity of the system's neighbors, and the characteristics of
the link(s) between the systems, including the length (in
nanoseconds) of the link(s).
4.9. Provisioning model
4.9.1. Centralized Path Computation and Installation
A centralized routing model, such as provided with a PCE (RFC 4655
[RFC4655]), enables global and per-flow optimizations. (See
Section 4.1.) The model is attractive but a number of issues are
left to be solved. In particular:
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o Whether and how the path computation can be installed by 1) an end
device or 2) a Network Management entity,
o And how the path is set up, either by installing state at each hop
with a direct interaction between the forwarding device and the
PCE, or along a path by injecting a source-routed request at one
end of the path.
4.9.2. Distributed Path Setup
Significant work on distributed path setup can be leveraged from MPLS
Traffic Engineering, in both its GMPLS and non-GMPLS forms. The
protocols within scope are Resource ReSerVation Protocol [RFC3209]
[RFC3473](RSVP-TE), OSPF-TE [RFC4203] [RFC5392] and ISIS-TE [RFC5307]
[RFC5316]. These should be viewed as starting points as there are
feature specific extensions defined that may be applicable to DetNet.
In a Layer-2 only environment, or as part of a layered approach to a
mixed environment, IEEE 802.1 also has work, either completed or in
progress. [IEEE802.1Q-2014] Clause 35 describes SRP, a peer-to-peer
protocol for Layer-2 roughly analogous to RSVP [RFC2205].
[IEEE802.1Qca] defines how ISIS can provide multiple disjoint paths
or distribution trees. Also in progress is [IEEE802.1Qcc], which
expands the capabilities of SRP.
The integration/interaction of the DetNet control layer with an
underlying IEEE 802.1 sub-network control layer will need to be
defined.
4.10. Scaling to larger networks
Reservations for individual DetNet flows require considerable state
information in each transit node, especially when adequate fault
mitigation (Section 4.5) is required. The DetNet data plane, in
order to support larger numbers of DetNet flows, must support the
aggregation of DetNet flows into tunnels, which themselves can be
viewed by the transit nodes' data planes largely as individual DetNet
flows. Without such aggregation, the per-relay system may limit the
scale of DetNet networks.
4.11. Connected islands vs. networks
Given that users have deployed examples of the IEEE 802.1 TSN TG
standards, which provide capabilities similar to DetNet, it is
obvious to ask whether the IETF DetNet effort can be limited to
providing Layer-2 connections (VPNs) between islands of bridged TSN
networks. While this capability is certainly useful to some
applications, and must not be precluded by DetNet, tunneling alone is
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not a sufficient goal for the DetNet WG. As shown in the
Deterministic Networking Use Cases draft [I-D.ietf-detnet-use-cases],
there are already deployments of Layer-2 TSN networks that are
encountering the well-known problems of over-large broadcast domains.
Routed solutions, and combinations routed/bridged solutions, are both
required.
5. Compatibility with Layer-2
Standards providing similar capabilities for bridged networks (only)
have been and are being generated in the IEEE 802 LAN/MAN Standards
Committee. The present architecture describes an abstract model that
can be applicable both at Layer-2 and Layer-3, and over links not
defined by IEEE 802. It is the intention of the authors (and
hopefully, as this draft progresses, of the DetNet Working Group)
that IETF and IEEE 802 will coordinate their work, via the
participation of common individuals, liaisons, and other means, to
maximize the compatibility of their outputs.
DetNet enabled end systems and intermediate nodes can be
interconnected by sub-networks, i.e., Layer-2 technologies. These
sub-networks will provide DetNet compatible service for support of
DetNet traffic. Examples of sub-networks include 802.1TSN and a
point-to-point OTN link. Of course, multi-layer DetNet systems may
be possible too, where one DetNet appears as a sub-network, and
provides service to, a higher layer DetNet system.
6. Open Questions
There are a number of architectural questions that will have to be
resolved before this document can be submitted for publication.
Aside from the obvious fact that this present draft is subject to
change, there are specific questions to which the authors wish to
direct the readers' attention.
6.1. DetNet flow identification and sequencing
The techniques to be used for DetNet flow identification must be
settled. The following paragraphs provide a snapshot of the authors'
opinions at the time of writing. See [I-D.dt-detnet-dp-alt] for a
detailed analysis. See also Section 4.7
IEEE 802.1 TSN streams are identified by giving each stream (DetNet
flow) a {VLAN identifier, destination MAC address} pair that is
unique in the bridged network, and that the MAC address must be a
multicast address. If a source is generating, for example, two
unicast UDP flows to the same destination, one DetNet and one not,
the DetNet flow's packets must be transformed at some point to have a
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multicast destination MAC address, and perhaps, a different VLAN than
the non-DetNet flow's packets.
A similar provision would apply to DetNet packets that are identified
by MPLS labels; any bridges between the LSRs need a {VLAN identifier,
destination MAC address} pair uniquely identifying the DetNet flow in
the bridged network.
Provision is made in current draft of [IEEE802.1CB] to make these
transformations either in a Layer-2 shim in the source end system, on
the output side of a router or LSR, or in a proxy function in the
first-hop bridge. It remains to be seen whether this provision is
adequate and/or acceptable to the IETF DetNet WG.
There are also questions regarding the sequentialization of packets
for use with packet replication and elimination (Section 3.4).
[IEEE802.1CB] defines an EtherNet tag carrying a sequence number. If
MPLS Pseudowires are used with a control word containing a sequence
number, the relationship and interworking between these two formats
must be defined.
6.2. Flat vs. hierarchical control
Boxes that are solely routers or solely bridges are rare in today's
market. In a multi-tenant data center, multiple users' virtual
Layer-2/Layer-3 topologies exist simultaneously, implemented on a
network whose physical topology bears only accidental resemblance to
the virtual topologies.
While the forwarding topology (the bridges and routers) are an
important consideration for a DetNet Flow Management Entity
(Section 4.1.1), so is the purely physical topology. Ultimately, the
model used by the management entities is based on boxes, queues, and
links. The authors hope that the work of the TEAS WG will help to
clarify exactly what model parameters need to be traded between the
intermediate nodes and the controller(s).
6.3. Peer-to-peer reservation protocol
As described in Section 4.9.2, the DetNet WG needs to decide whether
to support a peer-to-peer protocol for a source and a destination to
reserve resources for a DetNet stream. Assuming that enabling the
involvement of the source and/or destination is desirable (see
Deterministic Networking Use Cases [I-D.ietf-detnet-use-cases]), it
remains to decide whether the DetNet WG will make it possible to
deploy at least some DetNet capabilities in a network using only a
peer-to-peer protocol, without a central controller.
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(Note that a UNI (see Section 4.1.3) between an end system and an
edge node, for sources and/or listeners to request DetNet services,
can be either the first hop of a per-to-peer reservation protocol, or
can be deflected by the edge node to a central controller for
resolution. Similarly, a decision by a central controller can be
effected by the controller instructing the end system or edge node to
initiate a per-to-peer protocol activity.)
6.4. Wireless media interactions
Deterministic Networking Use Cases [I-D.ietf-detnet-use-cases]
illustrates cases where wireless media are needed in a DetNet
network. Some wireless media in general use, such as IEEE 802.11
[IEEE802.1Q-2014], have significantly higher packet loss rates than
typical wired media, such as Ethernet [IEEE802.3-2012]. IEEE 802.11
includes support for such features as MAC-layer acknowledgements and
retransmissions.
The techniques described in Section 3 are likely to improve the
ability of a mixed wired/wireless network to offer the DetNet QoS
features. The interaction of these techniques with the features of
specific wireless media, although they may be significant, cannot be
addressed in this document. It remains to be decided to what extent
the DetNet WG will address them, and to what extent other WGs, e.g.
6TiSCH, will do so.
6.5. Packet encoding for loss prevention
There are other methods for reducing packet loss caused by random
hardware errors and/or equipment failues that involve encoding the
information in a packet belonging to a DetNet flow into multiple
transmission units, typically combining information from multiple
packets into any given transmission unit. Such techniques may be
applicable for use as a DetNet loss prevention technique, assuming
that the DetNet users' needs for timeliness of delivery and freedom
from interference with misbehaving DetNet flows can be met.
7. Security Considerations
Security in the context of Deterministic Networking has an added
dimension; the time of delivery of a packet can be just as important
as the contents of the packet, itself. A man-in-the-middle attack,
for example, can impose, and then systematically adjust, additional
delays into a link, and thus disrupt or subvert a real-time
application without having to crack any encryption methods employed.
See [RFC7384] for an exploration of this issue in a related context.
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Furthermore, in a control system where millions of dollars of
equipment, or even human lives, can be lost if the DetNet QoS is not
delivered, one must consider not only simple equipment failures,
where the box or wire instantly becomes perfectly silent, but bizarre
errors such as can be caused by software failures. Because there is
essential no limit to the kinds of failures that can occur,
protecting against realistic equipment failures is indistinguishable,
in most cases, from protecting against malicious behavior, whether
accidental or intentional. See also Section 4.5.
Security must cover:
o the protection of the signaling protocol
o the authentication and authorization of the controlling systems
o the identification and shaping of the DetNet flows
8. Privacy Considerations
DetNet is provides a Quality of Service (QoS), and as such, does not
directly raise any new privacy considerations.
However, the requirement for every (or almost every) node along the
path of a DetNet flow to identify DetNet flows may present an
additional attack surface for privacy, should the DetNet paradigm be
found useful in broader environments.
9. IANA Considerations
This document does not require an action from IANA.
10. Acknowledgements
The authors wish to thank Jouni Korhonen, Erik Nordmark, George
Swallow, Rudy Klecka, Anca Zamfir, David Black, Thomas Watteyne,
Shitanshu Shah, Craig Gunther, Rodney Cummings, Balazs Varga,
Wilfried Steiner, Marcel Kiessling, Karl Weber, Janos Farkas, Ethan
Grossman, Pat Thaler, and Lou Berger for their various contribution
with this work.
11. Access to IEEE 802.1 documents
To access password protected IEEE 802.1 drafts, see the IETF IEEE
802.1 information page at https://www.ietf.org/proceedings/52/slides/
bridge-0/tsld003.htm.
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12. Informative References
[AVnu] http://www.avnu.org/, "The AVnu Alliance tests and
certifies devices for interoperability, providing a simple
and reliable networking solution for AV network
implementation based on the Audio Video Bridging (AVB)
standards.".
[CCAMP] IETF, "Common Control and Measurement Plane",
<https://datatracker.ietf.org/doc/charter-ietf-ccamp/>.
[HART] www.hartcomm.org, "Highway Addressable Remote Transducer,
a group of specifications for industrial process and
control devices administered by the HART Foundation".
[HSR-PRP] IEC, "High availability seamless redundancy (HSR) is a
further development of the PRP approach, although HSR
functions primarily as a protocol for creating media
redundancy while PRP, as described in the previous
section, creates network redundancy. PRP and HSR are both
described in the IEC 62439 3 standard.",
<http://webstore.iec.ch/webstore/webstore.nsf/
artnum/046615!opendocument>.
[I-D.dt-detnet-dp-alt]
Korhonen, J., Farkas, J., Mirsky, G., Thubert, P.,
Zhuangyan, Z., and L. Berger, "DetNet Data Plane Protocol
and Solution Alternatives", draft-dt-detnet-dp-alt-01
(work in progress), July 2016.
[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 (work
in progress), June 2016.
[I-D.ietf-6tisch-tsch]
Watteyne, T., Palattella, M., and L. Grieco, "Using
IEEE802.15.4e TSCH in an IoT context: Overview, Problem
Statement and Goals", draft-ietf-6tisch-tsch-06 (work in
progress), March 2015.
[I-D.ietf-detnet-problem-statement]
Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", draft-ietf-detnet-problem-statement-00 (work
in progress), April 2016.
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[I-D.ietf-detnet-use-cases]
Grossman, E., Gunther, C., Thubert, P., Wetterwald, P.,
Raymond, J., Korhonen, J., Kaneko, Y., Das, S., Zha, Y.,
Varga, B., Farkas, J., Goetz, F., and J. Schmitt,
"Deterministic Networking Use Cases", draft-ietf-detnet-
use-cases-10 (work in progress), July 2016.
[I-D.ietf-roll-rpl-industrial-applicability]
Phinney, T., Thubert, P., and R. Assimiti, "RPL
applicability in industrial networks", draft-ietf-roll-
rpl-industrial-applicability-02 (work in progress),
October 2013.
[I-D.svshah-tsvwg-deterministic-forwarding]
Shah, S. and P. Thubert, "Deterministic Forwarding PHB",
draft-svshah-tsvwg-deterministic-forwarding-04 (work in
progress), August 2015.
[IEEE802.11-2012]
IEEE, "Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications", 2012,
<http://standards.ieee.org/getieee802/
download/802.11-2012.pdf>.
[IEEE802.1AS-2011]
IEEE, "Timing and Synchronizations (IEEE 802.1AS-2011)",
2011, <http://standards.ieee.org/getIEEE802/
download/802.1AS-2011.pdf>.
[IEEE802.1BA-2011]
IEEE, "AVB Systems (IEEE 802.1BA-2011)", 2011,
<http://standards.ieee.org/getIEEE802/
download/802.1BA-2011.pdf>.
[IEEE802.1CB]
IEEE, "Frame Replication and Elimination for Reliability
(IEEE Draft P802.1CB)", 2016,
<http://www.ieee802.org/1/files/private/cb-drafts/>.
[IEEE802.1Q-2014]
IEEE, "MAC Bridges and VLANs (IEEE 802.1Q-2014", 2014,
<http://standards.ieee.org/getieee802/
download/802-1Q-2014.pdf>.
[IEEE802.1Qbu]
IEEE, "Frame Preemption", 2016,
<http://www.ieee802.org/1/files/private/bu-drafts/>.
Finn, et al. Expires January 9, 2017 [Page 28]
Internet-Draft Deterministic Networking Architecture July 2016
[IEEE802.1Qbv]
IEEE, "Enhancements for Scheduled Traffic", 2016,
<http://www.ieee802.org/1/files/private/bv-drafts/>.
[IEEE802.1Qca]
IEEE 802.1, "IEEE 802.1Qca Bridges and Bridged Networks -
Amendment 24: Path Control and Reservation", IEEE
P802.1Qca/D2.1 P802.1Qca, June 2015,
<https://standards.ieee.org/findstds/standard/802.1Qca-
2015.html>.
[IEEE802.1Qcc]
IEEE, "Stream Reservation Protocol (SRP) Enhancements and
Performance Improvements", 2016,
<http://www.ieee802.org/1/files/private/cc-drafts/>.
[IEEE802.1Qch]
IEEE, "Cyclic Queuing and Forwarding", 2016,
<http://www.ieee802.org/1/files/private/ch-drafts/>.
[IEEE802.1TSNTG]
IEEE Standards Association, "IEEE 802.1 Time-Sensitive
Networks Task Group", 2013,
<http://www.IEEE802.org/1/pages/avbridges.html>.
[IEEE802.3-2012]
IEEE, "IEEE Stabdard for Ethernet", 2012,
<http://standards.ieee.org/getieee802/
download/802.3-2012.pdf>.
[IEEE802.3br]
IEEE, "Interspersed Express Traffic", 2016,
<http://www.ieee802.org/3/br/>.
[IEEE802154]
IEEE standard for Information Technology, "IEEE std.
802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
and Physical Layer (PHY) Specifications for Low-Rate
Wireless Personal Area Networks", June 2011.
[IEEE802154e]
IEEE standard for Information Technology, "IEEE std.
802.15.4e, Part. 15.4: Low-Rate Wireless Personal Area
Networks (LR-WPANs) Amendment 1: MAC sublayer", April
2012.
Finn, et al. Expires January 9, 2017 [Page 29]
Internet-Draft Deterministic Networking Architecture July 2016
[ISA100.11a]
ISA/IEC, "ISA100.11a, Wireless Systems for Automation,
also IEC 62734", 2011, < http://www.isa100wci.org/en-
US/Documents/PDF/3405-ISA100-WirelessSystems-Future-broch-
WEB-ETSI.aspx>.
[ISA95] ANSI/ISA, "Enterprise-Control System Integration Part 1:
Models and Terminology", 2000, <https://www.isa.org/
isa95/>.
[ODVA] http://www.odva.org/, "The organization that supports
network technologies built on the Common Industrial
Protocol (CIP) including EtherNet/IP.".
[PCE] IETF, "Path Computation Element",
<https://datatracker.ietf.org/doc/charter-ietf-pce/>.
[Profinet]
http://us.profinet.com/technology/profinet/, "PROFINET is
a standard for industrial networking in automation.",
<http://us.profinet.com/technology/profinet/>.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <http://www.rfc-editor.org/info/rfc2205>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<http://www.rfc-editor.org/info/rfc2475>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<http://www.rfc-editor.org/info/rfc3209>.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003,
<http://www.rfc-editor.org/info/rfc3473>.
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<http://www.rfc-editor.org/info/rfc4203>.
Finn, et al. Expires January 9, 2017 [Page 30]
Internet-Draft Deterministic Networking Architecture July 2016
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc4655>.
[RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
<http://www.rfc-editor.org/info/rfc5307>.
[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
December 2008, <http://www.rfc-editor.org/info/rfc5316>.
[RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392,
January 2009, <http://www.rfc-editor.org/info/rfc5392>.
[RFC5673] Pister, K., Ed., Thubert, P., Ed., Dwars, S., and T.
Phinney, "Industrial Routing Requirements in Low-Power and
Lossy Networks", RFC 5673, DOI 10.17487/RFC5673, October
2009, <http://www.rfc-editor.org/info/rfc5673>.
[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,
<http://www.rfc-editor.org/info/rfc5921>.
[RFC6372] Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport
Profile (MPLS-TP) Survivability Framework", RFC 6372,
DOI 10.17487/RFC6372, September 2011,
<http://www.rfc-editor.org/info/rfc6372>.
[RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
October 2014, <http://www.rfc-editor.org/info/rfc7384>.
[RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
Defined Networking (SDN): Layers and Architecture
Terminology", RFC 7426, DOI 10.17487/RFC7426, January
2015, <http://www.rfc-editor.org/info/rfc7426>.
[TEAS] IETF, "Traffic Engineering Architecture and Signaling",
<https://datatracker.ietf.org/doc/charter-ietf-teas/>.
Finn, et al. Expires January 9, 2017 [Page 31]
Internet-Draft Deterministic Networking Architecture July 2016
[WirelessHART]
www.hartcomm.org, "Industrial Communication Networks -
Wireless Communication Network and Communication Profiles
- WirelessHART - IEC 62591", 2010.
Authors' Addresses
Norman Finn
Cisco Systems
170 W Tasman Dr.
San Jose, California 95134
USA
Phone: +1 408 526 4495
Email: nfinn@cisco.com
Pascal Thubert
Cisco Systems
Village d'Entreprises Green Side
400, Avenue de Roumanille
Batiment T3
Biot - Sophia Antipolis 06410
FRANCE
Phone: +33 4 97 23 26 34
Email: pthubert@cisco.com
Michael Johas Teener
Broadcom Corp.
3151 Zanker Rd.
San Jose, California 95134
USA
Phone: +1 831 824 4228
Email: MikeJT@broadcom.com
Finn, et al. Expires January 9, 2017 [Page 32]