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2 DetNet N. Finn
3 Internet-Draft Huawei
4 Intended status: Standards Track P. Thubert
5 Expires: June 22, 2019 Cisco
6 B. Varga
7 J. Farkas
8 Ericsson
9 December 19, 2018
11 Deterministic Networking Architecture
12 draft-ietf-detnet-architecture-10
14 Abstract
16 This document provides the overall architecture for Deterministic
17 Networking (DetNet), which provides a capability to carry specified
18 unicast or multicast data flows for real-time applications with
19 extremely low data loss rates and bounded latency within a network
20 domain. Techniques used include: 1) reserving data plane resources
21 for individual (or aggregated) DetNet flows in some or all of the
22 intermediate nodes along the path of the flow; 2) providing explicit
23 routes for DetNet flows that do not immediately change with the
24 network topology; and 3) distributing data from DetNet flow packets
25 over time and/or space to ensure delivery of each packet's data in
26 spite of the loss of a path. DetNet operates at the IP layer and
27 delivers service over sub-network technologies such as MPLS and IEEE
28 802.1 Time-Sensitive Networking (TSN).
30 Status of This Memo
32 This Internet-Draft is submitted in full conformance with the
33 provisions of BCP 78 and BCP 79.
35 Internet-Drafts are working documents of the Internet Engineering
36 Task Force (IETF). Note that other groups may also distribute
37 working documents as Internet-Drafts. The list of current Internet-
38 Drafts is at https://datatracker.ietf.org/drafts/current/.
40 Internet-Drafts are draft documents valid for a maximum of six months
41 and may be updated, replaced, or obsoleted by other documents at any
42 time. It is inappropriate to use Internet-Drafts as reference
43 material or to cite them other than as "work in progress."
45 This Internet-Draft will expire on June 22, 2019.
47 Copyright Notice
49 Copyright (c) 2018 IETF Trust and the persons identified as the
50 document authors. All rights reserved.
52 This document is subject to BCP 78 and the IETF Trust's Legal
53 Provisions Relating to IETF Documents
54 (https://trustee.ietf.org/license-info) in effect on the date of
55 publication of this document. Please review these documents
56 carefully, as they describe your rights and restrictions with respect
57 to this document. Code Components extracted from this document must
58 include Simplified BSD License text as described in Section 4.e of
59 the Trust Legal Provisions and are provided without warranty as
60 described in the Simplified BSD License.
62 Table of Contents
64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
65 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
66 2.1. Terms used in this document . . . . . . . . . . . . . . . 4
67 2.2. IEEE 802.1 TSN to DetNet dictionary . . . . . . . . . . . 7
68 3. Providing the DetNet Quality of Service . . . . . . . . . . . 7
69 3.1. Primary goals defining the DetNet QoS . . . . . . . . . . 7
70 3.2. Mechanisms to achieve DetNet QoS . . . . . . . . . . . . 10
71 3.2.1. Resource allocation . . . . . . . . . . . . . . . . . 10
72 3.2.1.1. Eliminate contention loss . . . . . . . . . . . . 10
73 3.2.1.2. Jitter Reduction . . . . . . . . . . . . . . . . 10
74 3.2.2. Service Protection . . . . . . . . . . . . . . . . . 11
75 3.2.2.1. In-Order Delivery . . . . . . . . . . . . . . . . 11
76 3.2.2.2. Packet Replication and Elimination . . . . . . . 12
77 3.2.2.3. Packet encoding for service protection . . . . . 14
78 3.2.3. Explicit routes . . . . . . . . . . . . . . . . . . . 14
79 3.3. Secondary goals for DetNet . . . . . . . . . . . . . . . 15
80 3.3.1. Coexistence with normal traffic . . . . . . . . . . . 15
81 3.3.2. Fault Mitigation . . . . . . . . . . . . . . . . . . 16
82 4. DetNet Architecture . . . . . . . . . . . . . . . . . . . . . 16
83 4.1. DetNet stack model . . . . . . . . . . . . . . . . . . . 16
84 4.1.1. Representative Protocol Stack Model . . . . . . . . . 16
85 4.1.2. DetNet Data Plane Overview . . . . . . . . . . . . . 19
86 4.1.3. Network reference model . . . . . . . . . . . . . . . 21
87 4.2. DetNet systems . . . . . . . . . . . . . . . . . . . . . 22
88 4.2.1. End system . . . . . . . . . . . . . . . . . . . . . 22
89 4.2.2. DetNet edge, relay, and transit nodes . . . . . . . . 23
90 4.3. DetNet flows . . . . . . . . . . . . . . . . . . . . . . 24
91 4.3.1. DetNet flow types . . . . . . . . . . . . . . . . . . 24
92 4.3.2. Source transmission behavior . . . . . . . . . . . . 24
93 4.3.3. Incomplete Networks . . . . . . . . . . . . . . . . . 26
94 4.4. Traffic Engineering for DetNet . . . . . . . . . . . . . 26
95 4.4.1. The Application Plane . . . . . . . . . . . . . . . . 27
96 4.4.2. The Controller Plane . . . . . . . . . . . . . . . . 27
97 4.4.3. The Network Plane . . . . . . . . . . . . . . . . . . 28
98 4.5. Queuing, Shaping, Scheduling, and Preemption . . . . . . 29
99 4.6. Service instance . . . . . . . . . . . . . . . . . . . . 30
100 4.7. Flow identification at technology borders . . . . . . . . 31
101 4.7.1. Exporting flow identification . . . . . . . . . . . . 31
102 4.7.2. Flow attribute mapping between layers . . . . . . . . 33
103 4.7.3. Flow-ID mapping examples . . . . . . . . . . . . . . 34
104 4.8. Advertising resources, capabilities and adjacencies . . . 35
105 4.9. Scaling to larger networks . . . . . . . . . . . . . . . 36
106 4.10. Compatibility with Layer-2 . . . . . . . . . . . . . . . 36
107 5. Security Considerations . . . . . . . . . . . . . . . . . . . 36
108 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 37
109 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
110 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 37
111 9. Informative References . . . . . . . . . . . . . . . . . . . 38
112 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
114 1. Introduction
116 This document provides the overall architecture for Deterministic
117 Networking (DetNet), which provides a capability for the delivery of
118 data flows with extremely low packet loss rates and bounded end-to-
119 end delivery latency. DetNet is for networks that are under a single
120 administrative control or within a closed group of administrative
121 control; these include campus-wide networks and private WANs. DetNet
122 is not for large groups of domains such as the Internet.
124 DetNet operates at the IP layer and delivers service over sub-network
125 technologies such as MPLS and IEEE 802.1 Time-Sensitive Networking
126 (TSN). DetNet accomplishes these goals by dedicating network
127 resources such as link bandwidth and buffer space to DetNet flows
128 and/or classes of DetNet flows, and by replicating packets along
129 multiple paths. Unused reserved resources are available to non-
130 DetNet packets as long as all guarantees are fulfilled.
132 The Deterministic Networking Problem Statement
133 [I-D.ietf-detnet-problem-statement] introduces Deterministic
134 Networking, and Deterministic Networking Use Cases
135 [I-D.ietf-detnet-use-cases] summarizes the need for it. See
136 [I-D.ietf-detnet-dp-sol-mpls] and [I-D.ietf-detnet-dp-sol-ip] for
137 specific techniques that can be used to identify DetNet flows and
138 assign them to specific paths through a network.
140 A goal of DetNet is a converged network in all respects. That is,
141 the presence of DetNet flows does not preclude non-DetNet flows, and
142 the benefits offered DetNet flows should not, except in extreme
143 cases, prevent existing Quality of Service (QoS) mechanisms from
144 operating in a normal fashion, subject to the bandwidth required for
145 the DetNet flows. A single source-destination pair can trade both
146 DetNet and non-DetNet flows. End systems and applications need not
147 instantiate special interfaces for DetNet flows. Networks are not
148 restricted to certain topologies; connectivity is not restricted.
149 Any application that generates a data flow that can be usefully
150 characterized as having a maximum bandwidth should be able to take
151 advantage of DetNet, as long as the necessary resources can be
152 reserved. Reservations can be made by the application itself, via
153 network management, by an application's controller, or by other
154 means, e.g., a dynamic control plane (e.g., [RFC2205]). QoS
155 requirements of DetNet flows can be met if all network nodes in a
156 DetNet domain implement DetNet capabilities. DetNet nodes can be
157 interconnected with different sub-network technologies
158 (Section 4.1.2), where the nodes of the subnet are not DetNet aware
159 (Section 4.1.3).
161 Many applications that are intended to be served by Deterministic
162 Networking require the ability to synchronize the clocks in end
163 systems to a sub-microsecond accuracy. Some of the queue control
164 techniques defined in Section 4.5 also require time synchronization
165 among network nodes. The means used to achieve time synchronization
166 are not addressed in this document. DetNet can accommodate various
167 time synchronization techniques and profiles that are defined
168 elsewhere to address the needs of different market segments.
170 2. Terminology
172 2.1. Terms used in this document
174 The following terms are used in the context of DetNet in this
175 document:
177 allocation
178 Resources are dedicated to support a DetNet flow. Depending
179 on an implementation, the resource may be reused by non-
180 DetNet flows when it is not used by the DetNet flow.
182 App-flow
183 The native format of a DetNet flow.
185 DetNet compound flow and DetNet member flow
186 A DetNet compound flow is a DetNet flow that has been
187 separated into multiple duplicate DetNet member flows for
188 service protection at the DetNet service sub-layer. Member
189 flows are merged back into a single DetNet compound flow such
190 that there are no duplicate packets. "Compound" and "member"
191 are strictly relative to each other, not absolutes; a DetNet
192 compound flow comprising multiple DetNet member flows can, in
193 turn, be a member of a higher-order compound.
195 DetNet destination
196 An end system capable of terminating a DetNet flow.
198 DetNet domain
199 The portion of a network that is DetNet aware. It includes
200 end systems and DetNet nodes.
202 DetNet edge node
203 An instance of a DetNet relay node that acts as a source and/
204 or destination at the DetNet service sub-layer. For example,
205 it can include a DetNet service sub-layer proxy function for
206 DetNet service protection (e.g., the addition or removal of
207 packet sequencing information) for one or more end systems,
208 or starts or terminates resource allocation at the DetNet
209 forwarding sub-layer, or aggregates DetNet services into new
210 DetNet flows. It is analogous to a Label Edge Router (LER)
211 or a Provider Edge (PE) router.
213 DetNet flow
214 A DetNet flow is a sequence of packets from one source to one
215 or more destinations, which conform uniquely to a flow
216 identifier, and to which the DetNet service is to be
217 provided.
219 DetNet forwarding sub-layer
220 The DetNet layer that optionally provides resource allocation
221 for DetNet flows over paths provided by the underlying
222 network.
224 DetNet intermediate node
225 A DetNet relay node or DetNet transit node.
227 DetNet node
228 A DetNet edge node, a DetNet relay node, or a DetNet transit
229 node.
231 DetNet relay node
232 A DetNet node including a service sub-layer function that
233 interconnects different DetNet forwarding sub-layer paths to
234 provide service protection. A DetNet relay node participates
235 in the DetNet service sub-layer. It typically incorporates
236 DetNet forwarding sub-layer functions as well, in which case
237 it is collocated with a transit node.
239 DetNet service sub-layer
240 The DetNet sub-layer at which A DetNet service, e.g., service
241 protection is provided.
243 DetNet service proxy
244 Maps between App-flows and DetNet flows.
246 DetNet source
247 An end system capable of originating a DetNet flow.
249 DetNet system
250 A DetNet aware end system, transit node, or relay node.
251 "DetNet" may be omitted in some text.
253 DetNet transit node
254 A DetNet node operating at the DetNet forwarding sub-layer,
255 that utilizes link layer and/or network layer switching
256 across multiple links and/or sub-networks to provide paths
257 for DetNet service sub-layer functions. Typically provides
258 resource allocation over those paths. An MPLS LSR is an
259 example of a DetNet transit node.
261 DetNet-UNI
262 User-to-Network Interface with DetNet specific
263 functionalities. It is a packet-based reference point and
264 may provide multiple functions like encapsulation, status,
265 synchronization, etc.
267 end system
268 Commonly called a "host" in IETF documents, and an "end
269 station" is IEEE 802 documents. End systems of interest to
270 this document are either sources or destinations of DetNet
271 flows. And end system may or may not be DetNet forwarding
272 sub-layer aware or DetNet service sub-layer aware.
274 link
275 A connection between two DetNet nodes. It may be composed of
276 a physical link or a sub-network technology that can provide
277 appropriate traffic delivery for DetNet flows.
279 PEF A Packet Elimination Function (PEF) eliminates duplicate
280 copies of packets to prevent excess packets flooding the
281 network or duplicate packets being sent out of the DetNet
282 domain. PEF can be implemented by a DetNet edge node, a
283 DetNet relay node, or an end system.
285 PRF A Packet Replication Function (PRF) replicates DetNet flow
286 packets and forwards them to one or more next hops in the
287 DetNet domain. The number of packet copies sent to the next
288 hops is a DetNet flow specific parameter at the point of
289 replication. PRF can be implemented by a DetNet edge node, a
290 DetNet relay node, or an end system.
292 PREOF Collective name for Packet Replication, Elimination, and
293 Ordering Functions.
295 POF A Packet Ordering Function (POF) re-orders packets within a
296 DetNet flow that are received out of order. This function
297 can be implemented by a DetNet edge node, a DetNet relay
298 node, or an end system.
300 reservation
301 The set of resources allocated between a source and one or
302 more destinations through DetNet nodes and subnets associated
303 with a DetNet flow, to provide the provisioned DetNet
304 service.
306 2.2. IEEE 802.1 TSN to DetNet dictionary
308 This section also serves as a dictionary for translating from the
309 terms used by the Time-Sensitive Networking (TSN) Task Group
310 [IEEE802.1TSNTG] of the IEEE 802.1 WG to those of the DetNet WG.
312 Listener
313 The IEEE 802.1 term for a destination of a DetNet flow.
315 relay system
316 The IEEE 802.1 term for a DetNet intermediate node.
318 Stream
319 The IEEE 802.1 term for a DetNet flow.
321 Talker
322 The IEEE 802.1 term for the source of a DetNet flow.
324 3. Providing the DetNet Quality of Service
326 3.1. Primary goals defining the DetNet QoS
328 The DetNet Quality of Service can be expressed in terms of:
330 o Minimum and maximum end-to-end latency from source to destination;
331 timely delivery, and bounded jitter (packet delay variation)
332 derived from these constraints.
334 o Packet loss ratio, under various assumptions as to the operational
335 states of the nodes and links.
337 o An upper bound on out-of-order packet delivery. It is worth
338 noting that some DetNet applications are unable to tolerate any
339 out-of-order delivery.
341 It is a distinction of DetNet that it is concerned solely with worst-
342 case values for the end-to-end latency, jitter, and misordering.
343 Average, mean, or typical values are of little interest, because they
344 do not affect the ability of a real-time system to perform its tasks.
345 In general, a trivial priority-based queuing scheme will give better
346 average latency to a data flow than DetNet; however, it may not be a
347 suitable option for DetNet because of its worst-case latency.
349 Three techniques are used by DetNet to provide these qualities of
350 service:
352 o Resource allocation (Section 3.2.1).
354 o Service protection (Section 3.2.2).
356 o Explicit routes (Section 3.2.3).
358 Resource allocation operates by assigning resources, e.g., buffer
359 space or link bandwidth, to a DetNet flow (or flow aggregate) along
360 its path. Resource allocation greatly reduces, or even eliminates
361 entirely, packet loss due to output packet contention within the
362 network, but it can only be supplied to a DetNet flow that is limited
363 at the source to a maximum packet size and transmission rate. Note
364 that congestion control provided via congestion detection and
365 notification [RFC3168] is explicitly excluded from consideration in
366 DetNet, as it serves a different set of applications.
368 Resource allocation addresses two of the DetNet QoS requirements:
369 latency and packet loss. Given that DetNet nodes have a finite
370 amount of buffer space, resource allocation necessarily results in a
371 maximum end-to-end latency. It also addresses contention related
372 packet loss.
374 Other important contribution to packet loss are random media errors
375 and equipment failures. Service protection is the name for the
376 mechanisms used by DetNet to address these losses. The mechanisms
377 employed are constrained by the requirement to meet the users'
378 latency requirements. Packet replication and elimination
379 (Section 3.2.2) and packet encoding (Section 3.2.2.3) are described
380 in this document to provide service protection; others may be found.
381 For instance, packet encoding can be used to provide service
382 protection against random media errors, packet replication and
383 elimination can be used to provide service protection against
384 equipment failures. This mechanism distributes the contents of
385 DetNet flows over multiple paths in time and/or space, so that the
386 loss of some of the paths does need not cause the loss of any
387 packets.
389 The paths are typically (but not necessarily) explicit routes, so
390 that they do not normally suffer temporary interruptions caused by
391 the convergence of routing or bridging protocols.
393 These three techniques can be applied independently, giving eight
394 possible combinations, including none (no DetNet), although some
395 combinations are of wider utility than others. This separation keeps
396 the protocol stack coherent and maximizes interoperability with
397 existing and developing standards in this (IETF) and other Standards
398 Development Organizations. Some examples of typical expected
399 combinations:
401 o Explicit routes plus service protection are exactly the techniques
402 employed by seamless redundancy mechanisms applied on a ring
403 topology as described, e.g., in [IEC62439-3-2016]. In this
404 example, explicit routes are achieved by limiting the physical
405 topology of the network to a ring. Sequentialization,
406 replication, and duplicate elimination are facilitated by packet
407 tags added at the front or the end of Ethernet frames. [RFC8227]
408 provides another example in the context of MPLS.
410 o Resource allocation alone was originally offered by IEEE 802.1
411 Audio Video bridging [IEEE802.1BA]. As long as the network
412 suffers no failures, packet loss due to output packet contention
413 can be eliminated through the use of a reservation protocol (e.g.,
414 Multiple Stream Registration Protocol [IEEE802.1Q-2018]), shapers
415 in every bridge, and proper dimensioning.
417 o Using all three together gives maximum protection.
419 There are, of course, simpler methods available (and employed, today)
420 to achieve levels of latency and packet loss that are satisfactory
421 for many applications. Prioritization and over-provisioning is one
422 such technique. However, these methods generally work best in the
423 absence of any significant amount of non-critical traffic in the
424 network (if, indeed, such traffic is supported at all), or work only
425 if the critical traffic constitutes only a small portion of the
426 network's theoretical capacity, or work only if all systems are
427 functioning properly, or in the absence of actions by end systems
428 that disrupt the network's operations.
430 There are any number of methods in use, defined, or in progress for
431 accomplishing each of the above techniques. It is expected that this
432 DetNet Architecture will assist various vendors, users, and/or
433 "vertical" Standards Development Organizations (dedicated to a single
434 industry) to make selections among the available means of
435 implementing DetNet networks.
437 3.2. Mechanisms to achieve DetNet QoS
439 3.2.1. Resource allocation
441 3.2.1.1. Eliminate contention loss
443 The primary means by which DetNet achieves its QoS assurances is to
444 reduce, or even completely eliminate packet loss due to output packet
445 contention within a DetNet node as a cause of packet loss. This can
446 be achieved only by the provision of sufficient buffer storage at
447 each node through the network to ensure that no packets are dropped
448 due to a lack of buffer storage. Note that a DetNet flow cannot be
449 throttled, i.e., its transmission rate cannot be reduced via explicit
450 congestion notification [RFC3168].
452 Ensuring adequate buffering requires, in turn, that the source, and
453 every DetNet node along the path to the destination (or nearly every
454 node, see Section 4.3.3) be careful to regulate its output to not
455 exceed the data rate for any DetNet flow, except for brief periods
456 when making up for interfering traffic. Any packet sent ahead of its
457 time potentially adds to the number of buffers required by the next
458 hop DetNet node and may thus exceed the resources allocated for a
459 particular DetNet flow.
461 The low-level mechanisms described in Section 4.5 provide the
462 necessary regulation of transmissions by an end system or DetNet node
463 to provide resource allocation. The allocation of the bandwidth and
464 buffers for a DetNet flow requires provisioning. A DetNet node may
465 have other resources requiring allocation and/or scheduling, that
466 might otherwise be over-subscribed and trigger the rejection of a
467 reservation.
469 3.2.1.2. Jitter Reduction
471 A core objective of DetNet is to enable the convergence of sensitive
472 non-IP networks onto a common network infrastructure. This requires
473 the accurate emulation of currently deployed mission-specific
474 networks, which for example rely on point-to-point analog (e.g.,
475 4-20mA modulation) and serial-digital cables (or buses) for highly
476 reliable, synchronized and jitter-free communications. While the
477 latency of analog transmissions is basically the speed of light,
478 legacy serial links are usually slow (in the order of Kbps) compared
479 to, say, GigE, and some latency is usually acceptable. What is not
480 acceptable is the introduction of excessive jitter, which may, for
481 instance, affect the stability of control systems.
483 Applications that are designed to operate on serial links usually do
484 not provide services to recover the jitter, because jitter simply
485 does not exist there. DetNet flows are generally expected to be
486 delivered in-order and the precise time of reception influences the
487 processes. In order to converge such existing applications, there is
488 a desire to emulate all properties of the serial cable, such as clock
489 transportation, perfect flow isolation and fixed latency. While
490 minimal jitter (in the form of specifying minimum, as well as
491 maximum, end-to-end latency) is supported by DetNet, there are
492 practical limitations on packet-based networks in this regard. In
493 general, users are encouraged to use, instead of, "do this when you
494 get the packet," a combination of:
496 o Sub-microsecond time synchronization among all source and
497 destination end systems, and
499 o Time-of-execution fields in the application packets.
501 Jitter reduction is provided by the mechanisms described in
502 Section 4.5 that also provide resource allocation.
504 3.2.2. Service Protection
506 Service protection aims to mitigate or eliminate packet loss due to
507 equipment failures, random media and/or memory faults. These types
508 of packet loss can be greatly reduced by spreading the data over
509 multiple disjoint forwarding paths. Various service protection
510 methods are described in [RFC6372], e.g., 1+1 linear protection.
511 This section describes the functional details of an additional method
512 in Section 3.2.2.2, which can be implemented as described in
513 Section 3.2.2.3 or as specified in [I-D.ietf-detnet-dp-sol-mpls] in
514 order to provide 1+n hitless protection. The appropriate service
515 protection mechanism depends on the scenario and the requirements.
517 3.2.2.1. In-Order Delivery
519 Out-of-order packet delivery can be a side effect of service
520 protection. Packets delivered out-of-order impact the amount of
521 buffering needed at the destination to properly process the received
522 data. Such packets also influence the jitter of a flow. The DetNet
523 service includes maximum allowed misordering as a constraint. Zero
524 misordering would be a valid service constraint to reflect that the
525 end system(s) of the flow cannot tolerate any out-of-order delivery.
527 DetNet Packet Ordering Functionality (POF) (Section 3.2.2.2) can be
528 used to provide in-order delivery.
530 3.2.2.2. Packet Replication and Elimination
532 This section describes a service protection method that sends copies
533 of the same packets over multiple paths.
535 The DetNet service sub-layer includes the packet replication (PRF),
536 the packet elimination (PEF), and the packet ordering functionality
537 (POF) for use in DetNet edge, relay node, and end system packet
538 processing. Either of these functions can be enabled in a DetNet
539 edge node, relay node or end system. The collective name for all
540 three functions is PREOF. The packet replication and elimination
541 service protection method altogether involves four capabilities:
543 o Providing sequencing information to the packets of a DetNet
544 compound flow. This may be done by adding a sequence number or
545 time stamp as part of DetNet, or may be inherent in the packet,
546 e.g., in a higher layer protocol, or associated to other physical
547 properties such as the precise time (and radio channel) of
548 reception of the packet. This is typically done once, at or near
549 the source.
551 o The Packet Replication Function (PRF) replicates these packets
552 into multiple DetNet member flows and typically sends them along
553 multiple different paths to the destination(s), e.g., over the
554 explicit routes of Section 3.2.3. The location within a DetNet
555 node, and the mechanism used for the PRF is implementation
556 specific.
558 o The Packet Elimination Function (PEF) eliminates duplicate packets
559 of a DetNet flow based on the sequencing information and a history
560 of received packets. The output of the PEF is always a single
561 packet. This may be done at any DetNet node along the path to
562 save network resources further downstream, in particular if
563 multiple Replication points exist. But the most common case is to
564 perform this operation at the very edge of the DetNet network,
565 preferably in or near the receiver. The location within a DetNet
566 node, and mechanism used for the PEF is implementation specific.
568 o The Packet Ordering Function (POF) uses the sequencing information
569 to re-order a DetNet flow's packets that are received out of
570 order.
572 The order in which a DetNet node applies PEF, POF, and PRF to a
573 DetNet flow is implementation specific.
575 Some service protection mechanisms rely on switching from one flow to
576 another when a failure of a flow is detected. Contrarily, packet
577 replication and elimination combines the DetNet member flows sent
578 along multiple different paths, and performs a packet-by-packet
579 selection of which to discard, e.g., based on sequencing information.
581 In the simplest case, this amounts to replicating each packet in a
582 source that has two interfaces, and conveying them through the
583 network, along separate (SRLG disjoint) paths, to the similarly dual-
584 homed destinations, that discard the extras. This ensures that one
585 path remains, even if some DetNet intermediate node fails. The
586 sequencing information can also be used for loss detection and for
587 re-ordering.
589 DetNet relay nodes in the network can provide replication and
590 elimination facilities at various points in the network, so that
591 multiple failures can be accommodated.
593 This is shown in Figure 1, where the two relay nodes each replicate
594 (R) the DetNet flow on input, sending the DetNet member flows to both
595 the other relay node and to the end system, and eliminate duplicates
596 (E) on the output interface to the right-hand end system. Any one
597 link in the network can fail, and the DetNet compound flow can still
598 get through. Furthermore, two links can fail, as long as they are in
599 different segments of the network.
601 > > > > > > > > > relay > > > > > > > >
602 > /------------+ R node E +------------\ >
603 > / v + ^ \ >
604 end R + v | ^ + E end
605 system + v | ^ + system
606 > \ v + ^ / >
607 > \------------+ R relay E +-----------/ >
608 > > > > > > > > > node > > > > > > > >
610 Figure 1: Packet replication and elimination
612 Packet replication and elimination does not react to and correct
613 failures; it is entirely passive. Thus, intermittent failures,
614 mistakenly created packet filters, or misrouted data is handled just
615 the same as the equipment failures that are handled by typical
616 routing and bridging protocols.
618 If packet replication and elimination is used over paths with
619 resource allocation (Section 3.2.1), and member flows that take
620 different-length paths through the network are combined, a merge
621 point may require extra buffering to equalize the delays over the
622 different paths. This equalization ensures that the resultant
623 compound flow will not exceed its contracted bandwidth even after one
624 or the other of the paths is restored after a failure. The extra
625 buffering can be also used to provide in-order delivery.
627 3.2.2.3. Packet encoding for service protection
629 There are methods for using multiple paths to provide service
630 protection that involve encoding the information in a packet
631 belonging to a DetNet flow into multiple transmission units,
632 combining information from multiple packets into any given
633 transmission unit. Such techniques, also known as "network coding",
634 can be used as a DetNet service protection technique.
636 3.2.3. Explicit routes
638 In networks controlled by typical dynamic control protocols such as
639 IS-IS or OSPF, a network topology event in one part of the network
640 can impact, at least briefly, the delivery of data in parts of the
641 network remote from the failure or recovery event. Even the use of
642 redundant paths through a network, e.g., as defined by [RFC6372] do
643 not eliminate the chances of packet loss. Furthermore, out-of-order
644 packet delivery can be a side effect of route changes.
646 Many real-time networks rely on physical rings of two-port devices,
647 with a relatively simple ring control protocol. This supports
648 redundant paths for service protection with a minimum of wiring. As
649 an additional benefit, ring topologies can often utilize different
650 topology management protocols than those used for a mesh network,
651 with a consequent reduction in the response time to topology changes.
652 Of course, this comes at some cost in terms of increased hop count,
653 and thus latency, for the typical path.
655 In order to get the advantages of low hop count and still ensure
656 against even very brief losses of connectivity, DetNet employs
657 explicit routes, where the path taken by a given DetNet flow does not
658 change, at least immediately, and likely not at all, in response to
659 network topology events. Service protection (Section 3.2.2 or
660 Section 3.2.2.3) over explicit routes provides a high likelihood of
661 continuous connectivity. Explicit routes can be established in
662 various ways, e.g., with RSVP-TE [RFC3209], with Segment Routing (SR)
663 [RFC8402], via a Software Defined Networking approach [RFC7426],
664 [RFC8453], and [RFC8453], with IS-IS [RFC7813], etc. Explicit routes
665 are typically used in MPLS TE LSPs.
667 Out-of-order packet delivery can be a side effect of distributing a
668 single flow over multiple paths especially when there is a change
669 from one path to another when combining the flow. This is
670 irrespective of the distribution method used, and also applies to
671 service protection over explicit routes. As described in
672 Section 3.2.2.1, out-of-order packets influence the jitter of a flow
673 and impact the amount of buffering needed to process the data;
674 therefore, DetNet service includes maximum allowed misordering as a
675 constraint. The use of explicit routes helps to provide in-order
676 delivery because there is no immediate route change with the network
677 topology, but the changes are plannable as they are between the
678 different explicit routes.
680 3.3. Secondary goals for DetNet
682 Many applications require DetNet to provide additional services,
683 including coexistence with other QoS mechanisms Section 3.3.1 and
684 protection against misbehaving transmitters Section 3.3.2.
686 3.3.1. Coexistence with normal traffic
688 A DetNet network supports the dedication of a high proportion of the
689 network bandwidth to DetNet flows. But, no matter how much is
690 dedicated for DetNet flows, it is a goal of DetNet to coexist with
691 existing Class of Service schemes (e.g., DiffServ). It is also
692 important that non-DetNet traffic not disrupt the DetNet flow, of
693 course (see Section 3.3.2 and Section 5). For these reasons:
695 o Bandwidth (transmission opportunities) not utilized by a DetNet
696 flow is available to non-DetNet packets (though not to other
697 DetNet flows).
699 o DetNet flows can be shaped or scheduled, in order to ensure that
700 the highest-priority non-DetNet packet is also ensured a worst-
701 case latency.
703 o When transmission opportunities for DetNet flows are scheduled in
704 detail, then the algorithm constructing the schedule should leave
705 sufficient opportunities for non-DetNet packets to satisfy the
706 needs of the users of the network. Detailed scheduling can also
707 permit the time-shared use of buffer resources by different DetNet
708 flows.
710 Starvation of non-DetNet traffic must be avoided, e.g., by traffic
711 policing functions (e.g., [RFC2475]). Thus, the net effect of the
712 presence of DetNet flows in a network on the non-DetNet flows is
713 primarily a reduction in the available bandwidth.
715 3.3.2. Fault Mitigation
717 Robust real-time systems require to reduce the number of possible
718 failures. Filters and policers should be used in a DetNet network to
719 detect if DetNet packets are received on the wrong interface, or at
720 the wrong time, or in too great a volume. Furthermore, filters and
721 policers can take actions to discard the offending packets or flows,
722 or trigger shutting down the offending flow or the offending
723 interface.
725 It is also essential that filters and service remarking be employed
726 at the network edge to prevent non-DetNet packets from being mistaken
727 for DetNet packets, and thus impinging on the resources allocated to
728 DetNet packets.
730 There exist techniques, at present and/or in various stages of
731 standardization, that can perform these fault mitigation tasks that
732 deliver a high probability that misbehaving systems will have zero
733 impact on well-behaved DetNet flows, except of course, for the
734 receiving interface(s) immediately downstream of the misbehaving
735 device. Examples of such techniques include traffic policing
736 functions (e.g., [RFC2475]) and separating flows into per-flow rate-
737 limited queues.
739 4. DetNet Architecture
741 4.1. DetNet stack model
743 DetNet functionality (Section 3) is implemented in two adjacent sub-
744 layers in the protocol stack: the DetNet service sub-layer and the
745 DetNet forwarding sub-layer. The DetNet service sub-layer provides
746 DetNet service, e.g., service protection, to higher layers in the
747 protocol stack and applications. The DetNet forwarding sub-layer
748 supports DetNet service in the underlying network, e.g., by providing
749 explicit routes and resource allocation to DetNet flows.
751 4.1.1. Representative Protocol Stack Model
753 Figure 2 illustrates a conceptual DetNet data plane layering model.
754 One may compare it to that in [IEEE802.1CB], Annex C.
756 | packets going | ^ packets coming ^
757 v down the stack v | up the stack |
758 +-----------------------+ +-----------------------+
759 | Source | | Destination |
760 +-----------------------+ +-----------------------+
761 | Service sub-layer: | | Service sub-layer: |
762 | Packet sequencing | | Duplicate elimination |
763 | Flow replication | | Flow merging |
764 | Packet encoding | | Packet decoding |
765 +-----------------------+ +-----------------------+
766 | Forwarding sub-layer: | | Forwarding sub-layer: |
767 | Resource allocation | | Resource allocation |
768 | Explicit routes | | Explicit routes |
769 +-----------------------+ +-----------------------+
770 | Lower layers | | Lower layers |
771 +-----------------------+ +-----------------------+
772 v ^
773 \_________________________/
775 Figure 2: DetNet data plane protocol stack
777 Not all sub-layers are required for any given application, or even
778 for any given network. The functionality shown in Figure 2 is:
780 Application
781 Shown as "source" and "destination" in the diagram.
783 Packet sequencing
784 As part of DetNet service protection, supplies the sequence
785 number for packet replication and elimination
786 (Section 3.2.2). Peers with Duplicate elimination. This
787 sub-layer is not needed if a higher layer protocol is
788 expected to perform any packet sequencing and duplicate
789 elimination required by the DetNet flow replication.
791 Duplicate elimination
792 As part of the DetNet service sub-layer, based on the
793 sequenced number supplied by its peer, packet sequencing,
794 Duplicate elimination discards any duplicate packets
795 generated by DetNet flow replication. It can operate on
796 member flows, compound flows, or both. The replication may
797 also be inferred from other information such as the precise
798 time of reception in a scheduled network. The duplicate
799 elimination sub-layer may also perform resequencing of
800 packets to restore packet order in a flow that was disrupted
801 by the loss of packets on one or another of the multiple
802 paths taken.
804 Flow replication
805 As part of DetNet service protection, packets that belong to
806 a DetNet compound flow are replicated into two or more DetNet
807 member flows. This function is separate from packet
808 sequencing. Flow replication can be an explicit replication
809 and remarking of packets, or can be performed by, for
810 example, techniques similar to ordinary multicast
811 replication, albeit with resource allocation implications.
812 Peers with DetNet flow merging.
814 Flow merging
815 As part of DetNet service protection, merges DetNet member
816 flows together for packets coming up the stack belonging to a
817 specific DetNet compound flow. Peers with DetNet flow
818 replication. DetNet flow merging, together with packet
819 sequencing, duplicate elimination, and DetNet flow
820 replication perform packet replication and elimination
821 (Section 3.2.2).
823 Packet encoding
824 As part of DetNet service protection, as an alternative to
825 packet sequencing and flow replication, packet encoding
826 combines the information in multiple DetNet packets, perhaps
827 from different DetNet compound flows, and transmits that
828 information in packets on different DetNet member Flows.
829 Peers with Packet decoding.
831 Packet decoding
832 As part of DetNet service protection, as an alternative to
833 flow merging and duplicate elimination, packet decoding takes
834 packets from different DetNet member flows, and computes from
835 those packets the original DetNet packets from the compound
836 flows input to packet encoding. Peers with Packet encoding.
838 Resource allocation
839 The DetNet forwarding sub-layer provides resource allocation.
840 See Section 4.5. The actual queuing and shaping mechanisms
841 are typically provided by underlying subnet, these can be
842 closely associated with the means of providing paths for
843 DetNet flows, the path and the resource allocation are
844 conflated in this figure.
846 Explicit routes
847 The DetNet forwarding sub-layer provides mechanisms to ensure
848 that fixed paths are provided for DetNet flows. These
849 explicit paths avoid the impact of network convergence.
851 Operations, Administration, and Maintenance (OAM) leverages in-band
852 and out-of-band signaling that validates whether the service is
853 effectively obtained within QoS constraints. OAM is not shown in
854 Figure 2; it may reside in any number of the layers. OAM can involve
855 specific tagging added in the packets for tracing implementation or
856 network configuration errors; traceability enables to find whether a
857 packet is a replica, which DetNet relay node performed the
858 replication, and which segment was intended for the replica. Active
859 and hybrid OAM methods require additional bandwidth to perform fault
860 management and performance monitoring of the DetNet domain. OAM may,
861 for instance, generate special test probes or add OAM information
862 into the data packet.
864 The packet sequencing and replication elimination functions at the
865 source and destination ends of a DetNet compound flow may be
866 performed either in the end system or in a DetNet relay node.
868 4.1.2. DetNet Data Plane Overview
870 A "Deterministic Network" will be composed of DetNet enabled end
871 systems, DetNet edge nodes, DetNet relay nodes and collectively
872 deliver DetNet services. DetNet relay and edge nodes are
873 interconnected via DetNet transit nodes (e.g., LSRs) which support
874 DetNet, but are not DetNet service aware. All DetNet nodes are
875 connected to sub-networks, where a point-to-point link is also
876 considered as a simple sub-network. These sub-networks will provide
877 DetNet compatible service for support of DetNet traffic. Examples of
878 sub-networks include MPLS TE, IEEE 802.1 TSN and OTN. Of course,
879 multi-layer DetNet systems may also be possible, where one DetNet
880 appears as a sub-network, and provides service to, a higher layer
881 DetNet system. A simple DetNet concept network is shown in Figure 3.
882 Note that in this and following figures "Forwarding" and "Fwd" refer
883 to the DetNet forwarding sub-layer, "Service" and "Svc" refer to the
884 DetNet service sub-layer, which are described in detail in
885 Section 4.1.
887 TSN Edge Transit Relay DetNet
888 End System Node Node Node End System
890 +----------+ +.........+ +----------+
891 | Appl. |<--:Svc Proxy:-- End to End Service -------->| Appl. |
892 +----------+ +---------+ +---------+ +----------+
893 | TSN | |TSN| |Svc|<- DetNet flow --: Service :-->| Service |
894 +----------+ +---+ +---+ +--------+ +---------+ +----------+
895 |Forwarding| |Fwd| |Fwd| | Fwd | |Fwd| |Fwd| |Forwarding|
896 +-------.--+ +-.-+ +-.-+ +--.----.+ +-.-+ +-.-+ +---.------+
897 : Link : / ,-----. \ : Link : / ,-----. \
898 +........+ +-[ Sub ]-+ +.......+ +-[ Sub ]-+
899 [Network] [Network]
900 `-----' `-----'
902 Figure 3: A Simple DetNet Enabled Network
904 Distinguishing the function of two DetNet data plane sub-layers, the
905 DetNet service sub-layer and the DetNet forwarding sub-layer, helps
906 to explore and evaluate various combinations of the data plane
907 solutions available, some are illustrated in Figure 4. This
908 separation of DetNet sub-layers, while helpful, should not be
909 considered as formal requirement. For example, some technologies may
910 violate these strict sub-layers and still be able to deliver a DetNet
911 service.
913 .
914 .
915 +-----------------------------+
916 | DetNet Service sub-layer | PW, UDP, GRE
917 +-----------------------------+
918 | DetNet Forwarding sub-layer | IPv6, IPv4, MPLS TE LSPs, MPLS SR
919 +-----------------------------+
920 .
921 .
923 Figure 4: DetNet adaptation to data plane
925 In some networking scenarios, the end system initially provides a
926 DetNet flow encapsulation, which contains all information needed by
927 DetNet nodes (e.g., Real-time Transport Protocol (RTP) [RFC3550]
928 based DetNet flow carried over a native UDP/IP network or
929 PseudoWire). In other scenarios, the encapsulation formats might
930 differ significantly.
932 There are many valid options to create a data plane solution for
933 DetNet traffic by selecting a technology approach for the DetNet
934 service sub-layer and also selecting a technology approach for the
935 DetNet forwarding sub-layer. There are a high number of valid
936 combinations.
938 One of the most fundamental differences between different potential
939 data plane options is the basic headers used by DetNet nodes. For
940 example, the basic service can be delivered based on an MPLS label or
941 an IP header. This decision impacts the basic forwarding logic for
942 the DetNet service sub-layer. Note that in both cases, IP addresses
943 are used to address DetNet nodes. The selected DetNet forwarding
944 sub-layer technology also needs to be mapped to the sub-net
945 technology used to interconnect DetNet nodes. For example, DetNet
946 flows will need to be mapped to TSN Streams.
948 4.1.3. Network reference model
950 Figure 5 shows another view of the DetNet service related reference
951 points and main components.
953 DetNet DetNet
954 end system end system
955 _ _
956 / \ +----DetNet-UNI (U) / \
957 /App\ | /App\
958 /-----\ | /-----\
959 | NIC | v ________ | NIC |
960 +--+--+ _____ / \ DetNet-UNI (U) --+ +--+--+
961 | / \__/ \ | |
962 | / +----+ +----+ \_____ | |
963 | / | | | | \_______ | |
964 +------U PE +----+ P +----+ \ _ v |
965 | | | | | | | ___/ \ |
966 | +--+-+ +----+ | +----+ | / \_ |
967 \ | | | | | / \ |
968 \ | +----+ +--+-+ +--+PE |------ U-----+
969 \ | | | | | | | | | \_ _/
970 \ +---+ P +----+ P +--+ +----+ | \____/
971 \___ | | | | /
972 \ +----+__ +----+ DetNet-1 DetNet-2
973 | \_____/ \___________/ |
974 | |
975 | | End-to-End service | | | |
976 <------------------------------------------------------------->
977 | | DetNet service | | | |
978 | <------------------------------------------------> |
979 | | | | | |
981 Figure 5: DetNet Service Reference Model (multi-domain)
983 DetNet-UNIs ("U" in Figure 5) are assumed in this document to be
984 packet-based reference points and provide connectivity over the
985 packet network. A DetNet-UNI may provide multiple functions, e.g.,
986 it may add networking technology specific encapsulation to the DetNet
987 flows if necessary; it may provide status of the availability of the
988 resources associated with a reservation; it may provide a
989 synchronization service for the end system; it may carry enough
990 signaling to place the reservation in a network without a controller,
991 or if the controller only deals with the network but not the end
992 systems. Internal reference points of end systems (between the
993 application and the NIC) are more challenging from control
994 perspective and they may have extra requirements (e.g., in-order
995 delivery is expected in end system internal reference points, whereas
996 it is considered optional over the DetNet-UNI).
998 4.2. DetNet systems
1000 4.2.1. End system
1002 The native data flow between the source/destination end systems is
1003 referred to as application-flow (App-flow). The traffic
1004 characteristics of an App-flow can be CBR (constant bit rate) or VBR
1005 (variable bit rate) and can have L1 or L2 or L3 encapsulation (e.g.,
1006 TDM (time-division multiplexing), Ethernet, IP). These
1007 characteristics are considered as input for resource reservation and
1008 might be simplified to ensure determinism during packet forwarding
1009 (e.g., making reservations for the peak rate of VBR traffic, etc.).
1011 An end system may or may not be DetNet forwarding sub-layer aware or
1012 DetNet service sub-layer aware. That is, an end system may or may
1013 not contain DetNet specific functionality. End systems with DetNet
1014 functionalities may have the same or different forwarding sub-layer
1015 as the connected DetNet domain. Categorization of end systems are
1016 shown in Figure 6.
1018 End system
1019 |
1020 |
1021 | DetNet aware ?
1022 / \
1023 +------< >------+
1024 NO | \ / | YES
1025 | v |
1026 DetNet unaware |
1027 End system |
1028 | Service/Forwarding
1029 | sub-layer
1030 / \ aware ?
1031 +--------< >-------------+
1032 f-aware | \ / | s-aware
1033 | v |
1034 | | both |
1035 | | |
1036 DetNet f-aware | DetNet s-aware
1037 End system | End system
1038 v
1039 DetNet sf-aware
1040 End system
1042 Figure 6: Categorization of end systems
1044 Note some known use case examples for end systems:
1046 o DetNet unaware: The classic case requiring service proxies.
1048 o DetNet f-aware: A DetNet forwarding sub-layer aware system. It
1049 knows about some TSN functions (e.g., reservation), but not about
1050 service protection.
1052 o DetNet s-aware: A DetNet service sub-layer aware system. It
1053 supplies sequence numbers, but doesn't know about resource
1054 allocation.
1056 o DetNet sf-aware: A full functioning DetNet end system, it has
1057 DetNet functionalities and usually the same forwarding paradigm as
1058 the connected DetNet domain. It can be treated as an integral
1059 part of the DetNet domain.
1061 4.2.2. DetNet edge, relay, and transit nodes
1063 As shown in Figure 3, DetNet edge nodes providing proxy service and
1064 DetNet relay nodes providing the DetNet service sub-layer are DetNet-
1065 aware, and DetNet transit nodes need only be aware of the DetNet
1066 forwarding sub-layer.
1068 In general, if a DetNet flow passes through one or more DetNet-
1069 unaware network nodes between two DetNet nodes providing the DetNet
1070 forwarding sub-layer for that flow, there is a potential for
1071 disruption or failure of the DetNet QoS. A network administrator
1072 needs to ensure that the DetNet-unaware network nodes are configured
1073 to minimize the chances of packet loss and delay, and provision
1074 enough extra buffer space in the DetNet transit node following the
1075 DetNet-unaware network nodes to absorb the induced latency
1076 variations.
1078 4.3. DetNet flows
1080 4.3.1. DetNet flow types
1082 A DetNet flow can have different formats while its packets are
1083 forwarded between the peer end systems. Therefore, the following
1084 possible types / formats of a DetNet flow are distinguished in this
1085 document:
1087 o App-flow: native format of the data carried over a DetNet flow.
1088 It does not contain any DetNet related attributes.
1090 o DetNet-f-flow: specific format of a DetNet flow. It only requires
1091 the resource allocation features provided by the DetNet forwarding
1092 sub-layer.
1094 o DetNet-s-flow: specific format of a DetNet flow. It only requires
1095 the service protection feature ensured by the DetNet service sub-
1096 layer.
1098 o DetNet-sf-flow: specific format of a DetNet flow. It requires
1099 both DetNet service sub-layer and DetNet forwarding sub-layer
1100 functions during forwarding.
1102 4.3.2. Source transmission behavior
1104 For the purposes of resource allocation, DetNet flows can be
1105 synchronous or asynchronous. In synchronous DetNet flows, at least
1106 the DetNet nodes (and possibly the end systems) are closely time
1107 synchronized, typically to better than 1 microsecond. By
1108 transmitting packets from different DetNet flows or classes of DetNet
1109 flows at different times, using repeating schedules synchronized
1110 among the DetNet nodes, resources such as buffers and link bandwidth
1111 can be shared over the time domain among different DetNet flows.
1112 There is a tradeoff among techniques for synchronous DetNet flows
1113 between the burden of fine-grained scheduling and the benefit of
1114 reducing the required resources, especially buffer space.
1116 In contrast, asynchronous DetNet flows are not coordinated with a
1117 fine-grained schedule, so relay and end systems must assume worst-
1118 case interference among DetNet flows contending for buffer resources.
1119 Asynchronous DetNet flows are characterized by:
1121 o A maximum packet size;
1123 o An observation interval; and
1125 o A maximum number of transmissions during that observation
1126 interval.
1128 These parameters, together with knowledge of the protocol stack used
1129 (and thus the size of the various headers added to a packet), limit
1130 the number of bit times per observation interval that the DetNet flow
1131 can occupy the physical medium.
1133 The source is required not to exceed these limits in order to obtain
1134 DetNet service. If the source transmits less data than this limit
1135 allows, the unused resource such as link bandwidth can be made
1136 available by the DetNet system to non-DetNet packets as long as all
1137 guarantees are fulfilled. However, making those resources available
1138 to DetNet packets in other DetNet flows would serve no purpose.
1139 Those other DetNet flows have their own dedicated resources, on the
1140 assumption that all DetNet flows can use all of their resources over
1141 a long period of time.
1143 There is no provision in DetNet for throttling DetNet flows, i.e.,
1144 the transmission rate cannot be reduced via explicit congestion
1145 notification [RFC3168]. The assumption is that a DetNet flow, to be
1146 useful, must be delivered in its entirety. That is, while any useful
1147 application is written to expect a certain number of lost packets,
1148 the real-time applications of interest to DetNet demand that the loss
1149 of data due to the network is a rare event.
1151 Although DetNet strives to minimize the changes required of an
1152 application to allow it to shift from a special-purpose digital
1153 network to an Internet Protocol network, one fundamental shift in the
1154 behavior of network applications is impossible to avoid: the
1155 reservation of resources before the application starts. In the first
1156 place, a network cannot deliver finite latency and practically zero
1157 packet loss to an arbitrarily high offered load. Secondly, achieving
1158 practically zero packet loss for unthrottled (though bandwidth
1159 limited) DetNet flows means that DetNet nodes have to dedicate buffer
1160 resources to specific DetNet flows or to classes of DetNet flows.
1162 The requirements of each reservation have to be translated into the
1163 parameters that control each DetNet system's queuing, shaping, and
1164 scheduling functions and delivered to the DetNet nodes and end
1165 systems.
1167 All nodes in a DetNet domain are expected to support the data
1168 behavior required to deliver a particular DetNet service. If a node
1169 itself is not DetNet service aware, the DetNet nodes that are
1170 adjacent to such non-DetNet aware nodes must ensure that the non-
1171 DetNet aware node is provisioned to appropriately support the DetNet
1172 service. For example, an IEEE 802.1 TSN node may be used to
1173 interconnect DetNet aware nodes, and these DetNet nodes can map
1174 DetNet flows to 802.1 TSN flows. Another example, an MPLS-TE or TP
1175 domain may be used to interconnect DetNet aware nodes, and these
1176 DetNet nodes can map DetNet flows to TE LSPs which can provide the
1177 QoS requirements of the DetNet service.
1179 4.3.3. Incomplete Networks
1181 The presence in the network of intermediate nodes or subnets that are
1182 not fully capable of offering DetNet services complicates the ability
1183 of the intermediate nodes and/or controller to allocate resources, as
1184 extra buffering must be allocated at points downstream from the non-
1185 DetNet intermediate node for a DetNet flow. This extra buffering may
1186 increase latency and/or jitter.
1188 4.4. Traffic Engineering for DetNet
1190 Traffic Engineering Architecture and Signaling (TEAS) [TEAS] defines
1191 traffic-engineering architectures for generic applicability across
1192 packet and non-packet networks. From a TEAS perspective, Traffic
1193 Engineering (TE) refers to techniques that enable operators to
1194 control how specific traffic flows are treated within their networks.
1196 Because if its very nature of establishing explicit optimized paths,
1197 Deterministic Networking can be seen as a new, specialized branch of
1198 Traffic Engineering, and inherits its architecture with a separation
1199 into planes.
1201 The Deterministic Networking architecture is thus composed of three
1202 planes, a (User) Application Plane, a Controller Plane, and a Network
1203 Plane, which echoes that of Figure 1 of Software-Defined Networking
1204 (SDN): Layers and Architecture Terminology [RFC7426], and the
1205 Controllers identified in [RFC8453] and [RFC7149].
1207 4.4.1. The Application Plane
1209 Per [RFC7426], the Application Plane includes both applications and
1210 services. In particular, the Application Plane incorporates the User
1211 Agent, a specialized application that interacts with the end user /
1212 operator and performs requests for Deterministic Networking services
1213 via an abstract Flow Management Entity, (FME) which may or may not be
1214 collocated with (one of) the end systems.
1216 At the Application Plane, a management interface enables the
1217 negotiation of flows between end systems. An abstraction of the flow
1218 called a Traffic Specification (TSpec) provides the representation.
1219 This abstraction is used to place a reservation over the (Northbound)
1220 Service Interface and within the Application plane. It is associated
1221 with an abstraction of location, such as IP addresses and DNS names,
1222 to identify the end systems and possibly specify DetNet nodes.
1224 4.4.2. The Controller Plane
1226 The Controller Plane corresponds to the aggregation of the Control
1227 and Management Planes in [RFC7426], though Common Control and
1228 Measurement Plane (CCAMP) [CCAMP] makes an additional distinction
1229 between management and measurement. When the logical separation of
1230 the Control, Measurement and other Management entities is not
1231 relevant, the term Controller Plane is used for simplicity to
1232 represent them all, and the term Controller Plane Function (CPF)
1233 refers to any device operating in that plane, whether is it a Path
1234 Computation Element (PCE) [RFC4655], or a Network Management entity
1235 (NME), or a distributed control plane. The CPF is a core element of
1236 a controller, in charge of computing Deterministic paths to be
1237 applied in the Network Plane.
1239 A (Northbound) Service Interface enables applications in the
1240 Application Plane to communicate with the entities in the Controller
1241 Plane as illustrated in Figure 7.
1243 One or more CPF(s) collaborate to implement the requests from the FME
1244 as Per-Flow Per-Hop Behaviors installed in the DetNet nodes for each
1245 individual flow. The CPFs place each flow along a deterministic
1246 sequence of DetNet nodes so as to respect per-flow constraints such
1247 as security and latency, and optimize the overall result for metrics
1248 such as an abstract aggregated cost. The deterministic sequence can
1249 typically be more complex than a direct sequence and include
1250 redundancy path, with one or more packet replication and elimination
1251 points. Scaling to larger networks is discussed in Section 4.9.
1253 4.4.3. The Network Plane
1255 The Network Plane represents the network devices and protocols as a
1256 whole, regardless of the Layer at which the network devices operate.
1257 It includes Forwarding Plane (data plane), Application, and
1258 Operational Plane (e.g., OAM) aspects.
1260 The network Plane comprises the Network Interface Cards (NIC) in the
1261 end systems, which are typically IP hosts, and DetNet nodes, which
1262 are typically IP routers and MPLS switches. Network-to-Network
1263 Interfaces such as used for Traffic Engineering path reservation in
1264 [RFC5921], as well as User-to-Network Interfaces (UNI) such as
1265 provided by the Local Management Interface (LMI) between network and
1266 end systems, are both part of the Network Plane, both in the control
1267 plane and the data plane.
1269 A Southbound (Network) Interface enables the entities in the
1270 Controller Plane to communicate with devices in the Network Plane as
1271 illustrated in Figure 7. This interface leverages and extends TEAS
1272 to describe the physical topology and resources in the Network Plane.
1274 End End
1275 System System
1277 -+-+-+-+-+-+-+ Northbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
1279 CPF CPF CPF CPF
1281 -+-+-+-+-+-+-+ Southbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
1283 DetNet DetNet DetNet DetNet
1284 Node Node Node Node
1285 NIC NIC
1286 DetNet DetNet DetNet DetNet
1287 Node Node Node Node
1289 Figure 7: Northbound and Southbound interfaces
1291 The DetNet nodes (and possibly the end systems NIC) expose their
1292 capabilities and physical resources to the controller (the CPF), and
1293 update the CPFs with their dynamic perception of the topology, across
1294 the Southbound Interface. In return, the CPFs set the per-flow paths
1295 up, providing a Flow Characterization that is more tightly coupled to
1296 the DetNet node Operation than a TSpec.
1298 At the Network plane, DetNet nodes may exchange information regarding
1299 the state of the paths, between adjacent DetNet nodes and possibly
1300 with the end systems, and forward packets within constraints
1301 associated to each flow, or, when unable to do so, perform a last
1302 resort operation such as drop or declassify.
1304 This document focuses on the Southbound interface and the operation
1305 of the Network Plane.
1307 4.5. Queuing, Shaping, Scheduling, and Preemption
1309 DetNet achieves bounded delivery latency by reserving bandwidth and
1310 buffer resources at each DetNet node along the path of the DetNet
1311 flow. The reservation itself is not sufficient, however.
1312 Implementors and users of a number of proprietary and standard real-
1313 time networks have found that standards for specific data plane
1314 techniques are required to enable these assurances to be made in a
1315 multi-vendor network. The fundamental reason is that latency
1316 variation in one DetNet system results in the need for extra buffer
1317 space in the next-hop DetNet system(s), which in turn, increases the
1318 worst-case per-hop latency.
1320 Standard queuing and transmission selection algorithms allow traffic
1321 engineering Section 4.4 to compute the latency contribution of each
1322 DetNet node to the end-to-end latency, to compute the amount of
1323 buffer space required in each DetNet node for each incremental DetNet
1324 flow, and most importantly, to translate from a flow specification to
1325 a set of values for the managed objects that control each relay or
1326 end system. For example, the IEEE 802.1 WG has specified (and is
1327 specifying) a set of queuing, shaping, and scheduling algorithms that
1328 enable each DetNet node, and/or a central controller, to compute
1329 these values. These algorithms include:
1331 o A credit-based shaper [IEEE802.1Qav] (superseded by
1332 [IEEE802.1Q-2018]).
1334 o Time-gated queues governed by a rotating time schedule based on
1335 synchronized time [IEEE802.1Qbv] (superseded by
1336 [IEEE802.1Q-2018]).
1338 o Synchronized double (or triple) buffers driven by synchronized
1339 time ticks. [IEEE802.1Qch] (superseded by [IEEE802.1Q-2018]).
1341 o Pre-emption of an Ethernet packet in transmission by a packet with
1342 a more stringent latency requirement, followed by the resumption
1343 of the preempted packet [IEEE802.1Qbu] (superseded by
1344 [IEEE802.1Q-2018]), [IEEE802.3br] (superseded by
1345 [IEEE802.3-2018]).
1347 While these techniques are currently embedded in Ethernet
1348 [IEEE802.3-2018] and bridging standards, we can note that they are
1349 all, except perhaps for packet preemption, equally applicable to
1350 other media than Ethernet, and to routers as well as bridges. Other
1351 media may have its own methods, see, e.g.,
1352 [I-D.ietf-6tisch-architecture], [RFC7554]. DetNet may include such
1353 definitions in the future, or may define how these techniques can be
1354 used by DetNet nodes.
1356 4.6. Service instance
1358 A Service instance represents all the functions required on a DetNet
1359 node to allow the end-to-end service between the UNIs.
1361 The DetNet network general reference model is shown in Figure 8 for a
1362 DetNet service scenario (i.e., between two DetNet-UNIs). In this
1363 figure, end systems ("A" and "B") are connected directly to the edge
1364 nodes of an IP/MPLS network ("PE1" and "PE2"). End systems
1365 participating in DetNet communication may require connectivity before
1366 setting up an App-flow that requires the DetNet service. Such a
1367 connectivity related service instance and the one dedicated for
1368 DetNet service share the same access. Packets belonging to a DetNet
1369 flow are selected by a filter configured on the access ("F1" and
1370 "F2"). As a result, data flow specific access ("access-A + F1" and
1371 "access-B + F2") are terminated in the flow specific service instance
1372 ("SI-1" and "SI-2"). A tunnel is used to provide connectivity
1373 between the service instances.
1375 The tunnel is exclusively used for the packets of the DetNet flow
1376 between "SI-1" and "SI-2". The service instances are configured to
1377 implement DetNet functions and a flow specific DetNet forwarding.
1378 The service instance and the tunnel may or may not be shared by
1379 multiple DetNet flows. Sharing the service instance by multiple
1380 DetNet flows requires properly populated forwarding tables of the
1381 service instance.
1383 access-A access-B
1384 <-----> <-------- tunnel ----------> <----->
1386 +---------+ ___ _ +---------+
1387 End system | +----+ | / \/ \_ | +----+ | End system
1388 "A" -------F1+ | | / \ | | +F2----- "B"
1389 | | +========+ IP/MPLS +=======+ | |
1390 | |SI-1| | \__ Net._/ | |SI-2| |
1391 | +----+ | \____/ | +----+ |
1392 |PE1 | | PE2|
1393 +---------+ +---------+
1395 Figure 8: DetNet network general reference model
1397 The tunnel between the service instances may have some special
1398 characteristics. For example, in case of a DetNet L3 service, there
1399 are differences in the usage of the PW for DetNet traffic compared to
1400 the network model described in [RFC6658]. In the DetNet scenario,
1401 the PW is likely to be used exclusively by the DetNet flow, whereas
1402 [RFC6658] states: "The packet PW appears as a single point-to-point
1403 link to the client layer. Network-layer adjacency formation and
1404 maintenance between the client equipment will follow the normal
1405 practice needed to support the required relationship in the client
1406 layer ... This packet PseudoWire is used to transport all of the
1407 required Layer-2 and Layer-3 protocols between LSR1 and LSR2".
1408 Further details are network technology specific and can be found in
1409 [I-D.ietf-detnet-dp-sol-mpls] and [I-D.ietf-detnet-dp-sol-ip].
1411 4.7. Flow identification at technology borders
1413 4.7.1. Exporting flow identification
1415 A DetNet node may need to map specific flows to lower layer flows (or
1416 Streams) in order to provide specific queuing and shaping services
1417 for specific flows. For example:
1419 o A non-IP, strictly L2 source end system X may be sending multiple
1420 flows to the same L2 destination end system Y. Those flows may
1421 include DetNet flows with different QoS requirements, and may
1422 include non-DetNet flows.
1424 o A router may be sending any number of flows to another router.
1425 Again, those flows may include DetNet flows with different QoS
1426 requirements, and may include non-DetNet flows.
1428 o Two routers may be separated by bridges. For these bridges to
1429 perform any required per-flow queuing and shaping, they must be
1430 able to identify the individual flows.
1432 o A Label Edge Router (LER) may have a Label Switched Path (LSP) set
1433 up for handling traffic destined for a particular IP address
1434 carrying only non-DetNet flows. If a DetNet flow to that same
1435 address is requested, a separate LSP may be needed, in order that
1436 all of the Label Switch Routers (LSRs) along the path to the
1437 destination give that flow special queuing and shaping.
1439 The need for a lower-layer node to be aware of individual higher-
1440 layer flows is not unique to DetNet. But, given the endless
1441 complexity of layering and relayering over tunnels that is available
1442 to network designers, DetNet needs to provide a model for flow
1443 identification that is better than packet inspection. That is not to
1444 say that packet inspection to Layer-4 or Layer-5 addresses will not
1445 be used, or the capability standardized; but, there are alternatives.
1447 A DetNet relay node can connect DetNet flows on different paths using
1448 different flow identification methods. For example:
1450 o A single unicast DetNet flow passing from router A through a
1451 bridged network to router B may be assigned a TSN Stream
1452 identifier that is unique within that bridged network. The
1453 bridges can then identify the flow without accessing higher-layer
1454 headers. Of course, the receiving router must recognize and
1455 accept that TSN Stream.
1457 o A DetNet flow passing from LSR A to LSR B may be assigned a
1458 different label than that used for other flows to the same IP
1459 destination.
1461 In any of the above cases, it is possible that an existing DetNet
1462 flow can be an aggregate carrying multiple other DetNet flows. (Not
1463 to be confused with DetNet compound vs. member flows.) Of course,
1464 this requires that the aggregate DetNet flow be provisioned properly
1465 to carry the aggregated flows.
1467 Thus, rather than packet inspection, there is the option to export
1468 higher-layer information to the lower layer. The requirement to
1469 support one or the other method for flow identification (or both) is
1470 a complexity that is part of DetNet control models.
1472 4.7.2. Flow attribute mapping between layers
1474 Forwarding of packets of DetNet flows over multiple technology
1475 domains may require that lower layers are aware of specific flows of
1476 higher layers. Such an "exporting of flow identification" is needed
1477 each time when the forwarding paradigm is changed on the forwarding
1478 path (e.g., two LSRs are interconnected by a L2 bridged domain,
1479 etc.). The three representative forwarding methods considered for
1480 deterministic networking are:
1482 o IP routing
1484 o MPLS label switching
1486 o Ethernet bridging
1488 A packet with corresponding Flow-IDs is illustrated in Figure 9,
1489 which also indicates where each Flow-ID can be added or removed.
1491 add/remove add/remove
1492 Eth Flow-ID IP Flow-ID
1493 | |
1494 v v
1495 +-----------------------------------------------------------+
1496 | | | | |
1497 | Eth | MPLS | IP | Application data |
1498 | | | | |
1499 +-----------------------------------------------------------+
1500 ^
1501 |
1502 add/remove
1503 MPLS Flow-ID
1505 Figure 9: Packet with multiple Flow-IDs
1507 The additional (domain specific) Flow-ID can be
1509 o created by a domain specific function or
1511 o derived from the Flow-ID added to the App-flow.
1513 The Flow-ID must be unique inside a given domain. Note that the
1514 Flow-ID added to the App-flow is still present in the packet, but
1515 some nodes may lack the function to recognize it; that's why the
1516 additional Flow-ID is added.
1518 4.7.3. Flow-ID mapping examples
1520 IP nodes and MPLS nodes are assumed to be configured to push such an
1521 additional (domain specific) Flow-ID when sending traffic to an
1522 Ethernet switch (as shown in the examples below).
1524 Figure 10 shows a scenario where an IP end system ("IP-A") is
1525 connected via two Ethernet switches ("ETH-n") to an IP router ("IP-
1526 1").
1528 IP domain
1529 <-----------------------------------------------
1531 +======+ +======+
1532 |L3-ID | |L3-ID |
1533 +======+ /\ +-----+ +======+
1534 / \ Forward as | |
1535 /IP-A\ per ETH-ID |IP-1 | Recognize
1536 Push ------> +-+----+ | +---+-+ <----- ETH-ID
1537 ETH-ID | +----+-----+ |
1538 | v v |
1539 | +-----+ +-----+ |
1540 +------+ | | +---------+
1541 +......+ |ETH-1+----+ETH-2| +======+
1542 .L3-ID . +-----+ +-----+ |L3-ID |
1543 +======+ +......+ +======+
1544 |ETH-ID| .L3-ID . |ETH-ID|
1545 +======+ +======+ +------+
1546 |ETH-ID|
1547 +======+
1549 Ethernet domain
1550 <---------------->
1552 Figure 10: IP nodes interconnected by an Ethernet domain
1554 End system "IP-A" uses the original App-flow specific ID ("L3-ID"),
1555 but as it is connected to an Ethernet domain it has to push an
1556 Ethernet-domain specific flow-ID ("ETH-ID") before sending the packet
1557 to "ETH-1" node. Ethernet switch "ETH-1" can recognize the data flow
1558 based on the "ETH-ID" and it does forwarding toward "ETH-2". "ETH-2"
1559 switches the packet toward the IP router. "IP-1" must be configured
1560 to receive the Ethernet Flow-ID specific multicast flow, but (as it
1561 is an L3 node) it decodes the data flow ID based on the "L3-ID"
1562 fields of the received packet.
1564 Figure 11 shows a scenario where MPLS domain nodes ("PE-n" and "P-m")
1565 are connected via two Ethernet switches ("ETH-n").
1567 MPLS domain
1568 <----------------------------------------------->
1570 +=======+ +=======+
1571 |MPLS-ID| |MPLS-ID|
1572 +=======+ +-----+ +-----+ +=======+ +-----+
1573 | | Forward as | | | |
1574 |PE-1 | per ETH-ID | P-2 +-----------+ PE-2|
1575 Push -----> +-+---+ | +---+-+ +-----+
1576 ETH-ID | +-----+----+ | \ Recognize
1577 | v v | +-- ETH-ID
1578 | +-----+ +-----+ |
1579 +---+ | | +----+
1580 +.......+ |ETH-1+----+ETH-2| +=======+
1581 .MPLS-ID. +-----+ +-----+ |MPLS-ID|
1582 +=======+ +=======+
1583 |ETH-ID | +.......+ |ETH-ID |
1584 +=======+ .MPLS-ID. +-------+
1585 +=======+
1586 |ETH-ID |
1587 +=======+
1588 Ethernet domain
1589 <---------------->
1591 Figure 11: MPLS nodes interconnected by an Ethernet domain
1593 "PE-1" uses the MPLS specific ID ("MPLS-ID"), but as it is connected
1594 to an Ethernet domain it has to push an Ethernet-domain specific
1595 flow-ID ("ETH-ID") before sending the packet to "ETH-1". Ethernet
1596 switch "ETH-1" can recognize the data flow based on the "ETH-ID" and
1597 it does forwarding toward "ETH-2". "ETH-2" switches the packet
1598 toward the MPLS node ("P-2"). "P-2" must be configured to receive
1599 the Ethernet Flow-ID specific multicast flow, but (as it is an MPLS
1600 node) it decodes the data flow ID based on the "MPLS-ID" fields of
1601 the received packet.
1603 One can appreciate from the above example that, when the means used
1604 for DetNet flow identification is altered or exported, the means for
1605 encoding the sequence number information must similarly be altered or
1606 exported.
1608 4.8. Advertising resources, capabilities and adjacencies
1610 Provisioning of DetNet requires knowledge about:
1612 o Details of the DetNet system's capabilities that are required in
1613 order to accurately allocate that DetNet system's resources, as
1614 well as other DetNet systems' resources. This includes, for
1615 example, which specific queuing and shaping algorithms are
1616 implemented (Section 4.5), the number of buffers dedicated for
1617 DetNet allocation, and the worst-case forwarding delay and
1618 misordering.
1620 o The dynamic state of a DetNet node's DetNet resources.
1622 o The identity of the DetNet system's neighbors, and the
1623 characteristics of the link(s) between the DetNet systems,
1624 including the latency of the links (in nanoseconds).
1626 4.9. Scaling to larger networks
1628 Reservations for individual DetNet flows require considerable state
1629 information in each DetNet node, especially when adequate fault
1630 mitigation (Section 3.3.2) is required. The DetNet data plane, in
1631 order to support larger numbers of DetNet flows, must support the
1632 aggregation of DetNet flows. Such aggregated flows can be viewed by
1633 the DetNet nodes' data plane largely as individual DetNet flows.
1634 Without such aggregation, the per-relay system may limit the scale of
1635 DetNet networks. Example techniques that may be used include MPLS
1636 hierarchy and IP DiffServ Code Points (DSCPs).
1638 4.10. Compatibility with Layer-2
1640 Standards providing similar capabilities for bridged networks (only)
1641 have been and are being generated in the IEEE 802 LAN/MAN Standards
1642 Committee. The present architecture describes an abstract model that
1643 can be applicable both at Layer-2 and Layer-3, and over links not
1644 defined by IEEE 802.
1646 DetNet enabled end systems and DetNet nodes can be interconnected by
1647 sub-networks, i.e., Layer-2 technologies. These sub-networks will
1648 provide DetNet compatible service for support of DetNet traffic.
1649 Examples of sub-networks include MPLS TE, 802.1 TSN, and a point-to-
1650 point OTN link. Of course, multi-layer DetNet systems may be
1651 possible too, where one DetNet appears as a sub-network, and provides
1652 service to, a higher layer DetNet system.
1654 5. Security Considerations
1656 Security in the context of Deterministic Networking has an added
1657 dimension; the time of delivery of a packet can be just as important
1658 as the contents of the packet, itself. A man-in-the-middle attack,
1659 for example, can impose, and then systematically adjust, additional
1660 delays into a link, and thus disrupt or subvert a real-time
1661 application without having to crack any encryption methods employed.
1662 See [RFC7384] for an exploration of this issue in a related context.
1664 Furthermore, in a control system where millions of dollars of
1665 equipment, or even human lives, can be lost if the DetNet QoS is not
1666 delivered, one must consider not only simple equipment failures,
1667 where the box or wire instantly becomes perfectly silent, but complex
1668 errors such as can be caused by software failures. Because there is
1669 essential no limit to the kinds of failures that can occur,
1670 protecting against realistic equipment failures is indistinguishable,
1671 in most cases, from protecting against malicious behavior, whether
1672 accidental or intentional. See also Section 3.3.2.
1674 Security must cover:
1676 o the protection of the signaling protocol
1678 o the authentication and authorization of the controlling systems
1680 o the identification and shaping of the DetNet flows
1682 Security considerations for DetNet are described in detail in
1683 [I-D.ietf-detnet-security].
1685 6. Privacy Considerations
1687 DetNet is provides a Quality of Service (QoS), and as such, does not
1688 directly raise any new privacy considerations.
1690 However, the requirement for every (or almost every) node along the
1691 path of a DetNet flow to identify DetNet flows may present an
1692 additional attack surface for privacy, should the DetNet paradigm be
1693 found useful in broader environments.
1695 7. IANA Considerations
1697 This document does not require an action from IANA.
1699 8. Acknowledgements
1701 The authors wish to thank Lou Berger, David Black, Stewart Bryant,
1702 Rodney Cummings, Ethan Grossman, Craig Gunther, Marcel Kiessling,
1703 Rudy Klecka, Jouni Korhonen, Erik Nordmark, Shitanshu Shah, Wilfried
1704 Steiner, George Swallow, Michael Johas Teener, Pat Thaler, Thomas
1705 Watteyne, Patrick Wetterwald, Karl Weber, Anca Zamfir, for their
1706 various contribution with this work.
1708 9. Informative References
1710 [CCAMP] IETF, "Common Control and Measurement Plane Working
1711 Group",
1712 .
1714 [I-D.ietf-6tisch-architecture]
1715 Thubert, P., "An Architecture for IPv6 over the TSCH mode
1716 of IEEE 802.15.4", draft-ietf-6tisch-architecture-19 (work
1717 in progress), December 2018.
1719 [I-D.ietf-detnet-dp-sol-ip]
1720 Korhonen, J. and B. Varga, "DetNet IP Data Plane
1721 Encapsulation", draft-ietf-detnet-dp-sol-ip-01 (work in
1722 progress), October 2018.
1724 [I-D.ietf-detnet-dp-sol-mpls]
1725 Korhonen, J. and B. Varga, "DetNet MPLS Data Plane
1726 Encapsulation", draft-ietf-detnet-dp-sol-mpls-01 (work in
1727 progress), October 2018.
1729 [I-D.ietf-detnet-problem-statement]
1730 Finn, N. and P. Thubert, "Deterministic Networking Problem
1731 Statement", draft-ietf-detnet-problem-statement-08 (work
1732 in progress), December 2018.
1734 [I-D.ietf-detnet-security]
1735 Mizrahi, T., Grossman, E., Hacker, A., Das, S., Dowdell,
1736 J., Austad, H., Stanton, K., and N. Finn, "Deterministic
1737 Networking (DetNet) Security Considerations", draft-ietf-
1738 detnet-security-03 (work in progress), October 2018.
1740 [I-D.ietf-detnet-use-cases]
1741 Grossman, E., "Deterministic Networking Use Cases", draft-
1742 ietf-detnet-use-cases-19 (work in progress), October 2018.
1744 [IEC62439-3-2016]
1745 International Electrotechnical Commission (IEC) TC 65/SC
1746 65C - Industrial networks, "IEC 62439-3:2016 Industrial
1747 communication networks - High availability automation
1748 networks - Part 3: Parallel Redundancy Protocol (PRP) and
1749 High-availability Seamless Redundancy (HSR)", 2016,
1750 .
1752 [IEEE802.1BA]
1753 IEEE Standards Association, "IEEE Std 802.1BA-2011 Audio
1754 Video Bridging (AVB) Systems", 2011,
1755 .
1757 [IEEE802.1CB]
1758 IEEE Standards Association, "IEEE Std 802.1CB-2017 Frame
1759 Replication and Elimination for Reliability", 2017,
1760 .
1762 [IEEE802.1Q-2018]
1763 IEEE Standards Association, "IEEE Std 802.1Q-2018 Bridges
1764 and Bridged Networks", 2018,
1765 .
1767 [IEEE802.1Qav]
1768 IEEE Standards Association, "IEEE Std 802.1Qav-2009
1769 Bridges and Bridged Networks - Amendment 12: Forwarding
1770 and Queuing Enhancements for Time-Sensitive Streams",
1771 2009, .
1773 [IEEE802.1Qbu]
1774 IEEE Standards Association, "IEEE Std 802.1Qbu-2016
1775 Bridges and Bridged Networks - Amendment 26: Frame
1776 Preemption", 2016,
1777 .
1779 [IEEE802.1Qbv]
1780 IEEE Standards Association, "IEEE Std 802.1Qbv-2015
1781 Bridges and Bridged Networks - Amendment 25: Enhancements
1782 for Scheduled Traffic", 2015,
1783 .
1785 [IEEE802.1Qch]
1786 IEEE Standards Association, "IEEE Std 802.1Qch-2017
1787 Bridges and Bridged Networks - Amendment 29: Cyclic
1788 Queuing and Forwarding", 2017,
1789 .
1791 [IEEE802.1TSNTG]
1792 IEEE Standards Association, "IEEE 802.1 Time-Sensitive
1793 Networking Task Group", 2013,
1794 .
1796 [IEEE802.3-2018]
1797 IEEE Standards Association, "IEEE Std 802.3-2018 Standard
1798 for Ethernet", 2018,
1799 .
1801 [IEEE802.3br]
1802 IEEE Standards Association, "IEEE Std 802.3br-2016
1803 Standard for Ethernet Amendment 5: Specification and
1804 Management Parameters for Interspersing Express Traffic",
1805 2016, .
1807 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
1808 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
1809 Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
1810 September 1997, .
1812 [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
1813 and W. Weiss, "An Architecture for Differentiated
1814 Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
1815 .
1817 [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
1818 of Explicit Congestion Notification (ECN) to IP",
1819 RFC 3168, DOI 10.17487/RFC3168, September 2001,
1820 .
1822 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
1823 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
1824 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
1825 .
1827 [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
1828 Jacobson, "RTP: A Transport Protocol for Real-Time
1829 Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
1830 July 2003, .
1832 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
1833 Element (PCE)-Based Architecture", RFC 4655,
1834 DOI 10.17487/RFC4655, August 2006,
1835 .
1837 [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau,
1838 L., and L. Berger, "A Framework for MPLS in Transport
1839 Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010,
1840 .
1842 [RFC6372] Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport
1843 Profile (MPLS-TP) Survivability Framework", RFC 6372,
1844 DOI 10.17487/RFC6372, September 2011,
1845 .
1847 [RFC6658] Bryant, S., Ed., Martini, L., Swallow, G., and A. Malis,
1848 "Packet Pseudowire Encapsulation over an MPLS PSN",
1849 RFC 6658, DOI 10.17487/RFC6658, July 2012,
1850 .
1852 [RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined
1853 Networking: A Perspective from within a Service Provider
1854 Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014,
1855 .
1857 [RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
1858 Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
1859 October 2014, .
1861 [RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
1862 Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
1863 Defined Networking (SDN): Layers and Architecture
1864 Terminology", RFC 7426, DOI 10.17487/RFC7426, January
1865 2015, .
1867 [RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
1868 IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
1869 Internet of Things (IoT): Problem Statement", RFC 7554,
1870 DOI 10.17487/RFC7554, May 2015,
1871 .
1873 [RFC7813] Farkas, J., Ed., Bragg, N., Unbehagen, P., Parsons, G.,
1874 Ashwood-Smith, P., and C. Bowers, "IS-IS Path Control and
1875 Reservation", RFC 7813, DOI 10.17487/RFC7813, June 2016,
1876 .
1878 [RFC8227] Cheng, W., Wang, L., Li, H., van Helvoort, H., and J.
1879 Dong, "MPLS-TP Shared-Ring Protection (MSRP) Mechanism for
1880 Ring Topology", RFC 8227, DOI 10.17487/RFC8227, August
1881 2017, .
1883 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
1884 Decraene, B., Litkowski, S., and R. Shakir, "Segment
1885 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
1886 July 2018, .
1888 [RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
1889 Abstraction and Control of TE Networks (ACTN)", RFC 8453,
1890 DOI 10.17487/RFC8453, August 2018,
1891 .
1893 [TEAS] IETF, "Traffic Engineering Architecture and Signaling
1894 Working Group",
1895 .
1897 Authors' Addresses
1899 Norman Finn
1900 Huawei
1901 3101 Rio Way
1902 Spring Valley, California 91977
1903 US
1905 Phone: +1 925 980 6430
1906 Email: norman.finn@mail01.huawei.com
1908 Pascal Thubert
1909 Cisco Systems
1910 Village d'Entreprises Green Side
1911 400, Avenue de Roumanille
1912 Batiment T3
1913 Biot - Sophia Antipolis 06410
1914 FRANCE
1916 Phone: +33 4 97 23 26 34
1917 Email: pthubert@cisco.com
1919 Balazs Varga
1920 Ericsson
1921 Magyar tudosok korutja 11
1922 Budapest 1117
1923 Hungary
1925 Email: balazs.a.varga@ericsson.com
1927 Janos Farkas
1928 Ericsson
1929 Magyar tudosok korutja 11
1930 Budapest 1117
1931 Hungary
1933 Email: janos.farkas@ericsson.com