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2 DetNet N. Finn
3 Internet-Draft Huawei Technologies Co. Ltd
4 Intended status: Standards Track P. Thubert
5 Expires: May 3, 2018 Cisco
6 B. Varga
7 J. Farkas
8 Ericsson
9 October 30, 2017
11 Deterministic Networking Architecture
12 draft-ietf-detnet-architecture-04
14 Abstract
16 Deterministic Networking (DetNet) provides a capability to carry
17 specified unicast or multicast data flows for real-time applications
18 with extremely low data loss rates and bounded latency. Techniques
19 used include: 1) reserving data plane resources for individual (or
20 aggregated) DetNet flows in some or all of the intermediate nodes
21 (e.g. bridges or routers) along the path of the flow; 2) providing
22 explicit routes for DetNet flows that do not rapidly change with the
23 network topology; and 3) distributing data from DetNet flow packets
24 over time and/or space to ensure delivery of each packet's data' in
25 spite of the loss of a path. The capabilities can be managed by
26 configuration, or by manual or automatic network management.
28 Status of This Memo
30 This Internet-Draft is submitted in full conformance with the
31 provisions of BCP 78 and BCP 79.
33 Internet-Drafts are working documents of the Internet Engineering
34 Task Force (IETF). Note that other groups may also distribute
35 working documents as Internet-Drafts. The list of current Internet-
36 Drafts is at https://datatracker.ietf.org/drafts/current/.
38 Internet-Drafts are draft documents valid for a maximum of six months
39 and may be updated, replaced, or obsoleted by other documents at any
40 time. It is inappropriate to use Internet-Drafts as reference
41 material or to cite them other than as "work in progress."
43 This Internet-Draft will expire on May 3, 2018.
45 Copyright Notice
47 Copyright (c) 2017 IETF Trust and the persons identified as the
48 document authors. All rights reserved.
50 This document is subject to BCP 78 and the IETF Trust's Legal
51 Provisions Relating to IETF Documents
52 (https://trustee.ietf.org/license-info) in effect on the date of
53 publication of this document. Please review these documents
54 carefully, as they describe your rights and restrictions with respect
55 to this document. Code Components extracted from this document must
56 include Simplified BSD License text as described in Section 4.e of
57 the Trust Legal Provisions and are provided without warranty as
58 described in the Simplified BSD License.
60 Table of Contents
62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
63 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
64 2.1. Terms used in this document . . . . . . . . . . . . . . . 4
65 2.2. IEEE 802 TSN to DetNet dictionary . . . . . . . . . . . . 6
66 3. Providing the DetNet Quality of Service . . . . . . . . . . . 7
67 3.1. Primary goals defining the DetNet QoS . . . . . . . . . . 7
68 3.2. Mechanisms to achieve DetNet Qos . . . . . . . . . . . . 9
69 3.2.1. Congestion protection . . . . . . . . . . . . . . . . 9
70 3.2.2. Explicit routes . . . . . . . . . . . . . . . . . . . 9
71 3.2.3. Jitter Reduction . . . . . . . . . . . . . . . . . . 10
72 3.2.4. Packet Replication and Elimination . . . . . . . . . 11
73 3.3. Secondary goals for DetNet . . . . . . . . . . . . . . . 12
74 3.3.1. Coexistence with normal traffic . . . . . . . . . . . 12
75 3.3.2. Fault Mitigation . . . . . . . . . . . . . . . . . . 13
76 4. DetNet Architecture . . . . . . . . . . . . . . . . . . . . . 14
77 4.1. DetNet stack model . . . . . . . . . . . . . . . . . . . 14
78 4.1.1. Representative Protocol Stack Model . . . . . . . . . 14
79 4.1.2. DetNet Data Plane Overview . . . . . . . . . . . . . 16
80 4.1.3. Network reference model . . . . . . . . . . . . . . . 18
81 4.2. DetNet systems . . . . . . . . . . . . . . . . . . . . . 19
82 4.2.1. End system . . . . . . . . . . . . . . . . . . . . . 19
83 4.2.2. DetNet edge, relay, and transit nodes . . . . . . . . 20
84 4.3. DetNet flows . . . . . . . . . . . . . . . . . . . . . . 21
85 4.3.1. DetNet flow types . . . . . . . . . . . . . . . . . . 21
86 4.3.2. Source guarantees . . . . . . . . . . . . . . . . . . 21
87 4.3.3. Incomplete Networks . . . . . . . . . . . . . . . . . 23
88 4.4. Traffic Engineering for DetNet . . . . . . . . . . . . . 23
89 4.4.1. The Application Plane . . . . . . . . . . . . . . . . 23
90 4.4.2. The Controller Plane . . . . . . . . . . . . . . . . 24
91 4.4.3. The Network Plane . . . . . . . . . . . . . . . . . . 24
92 4.5. Queuing, Shaping, Scheduling, and Preemption . . . . . . 25
93 4.6. Service instance . . . . . . . . . . . . . . . . . . . . 26
94 4.7. Flow identification at technology borders . . . . . . . . 27
95 4.7.1. Exporting flow identification . . . . . . . . . . . . 27
96 4.7.2. Flow attribute mapping between layers . . . . . . . . 29
97 4.7.3. Flow-ID mapping examples . . . . . . . . . . . . . . 30
98 4.8. Advertising resources, capabilities and adjacencies . . . 32
99 4.9. Provisioning model . . . . . . . . . . . . . . . . . . . 32
100 4.9.1. Centralized Path Computation and Installation . . . . 32
101 4.9.2. Distributed Path Setup . . . . . . . . . . . . . . . 32
102 4.10. Scaling to larger networks . . . . . . . . . . . . . . . 33
103 4.11. Connected islands vs. networks . . . . . . . . . . . . . 33
104 4.12. Compatibility with Layer-2 . . . . . . . . . . . . . . . 33
105 5. Security Considerations . . . . . . . . . . . . . . . . . . . 34
106 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 34
107 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
108 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 35
109 9. Access to IEEE 802.1 documents . . . . . . . . . . . . . . . 35
110 10. Informative References . . . . . . . . . . . . . . . . . . . 35
111 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
113 1. Introduction
115 Deterministic Networking (DetNet) is a service that can be offered by
116 a network to DetNet flows. DetNet provides these flows extremely low
117 packet loss rates and assured maximum end-to-end delivery latency.
118 This is accomplished by dedicating network resources such as link
119 bandwidth and buffer space to DetNet flows and/or classes of DetNet
120 flows, and by replicating packets along multiple paths. Unused
121 reserved resources are available to non-DetNet packets.
123 The Deterministic Networking Problem Statement
124 [I-D.ietf-detnet-problem-statement] introduces Deterministic
125 Networking, and Deterministic Networking Use Cases
126 [I-D.ietf-detnet-use-cases] summarizes the need for it. See
127 [I-D.dt-detnet-dp-alt] for a discussion of specific techniques that
128 can be used to identify DetNet Flows and assign them to specific
129 paths through a network.
131 A goal of DetNet is a converged network in all respects. That is,
132 the presence of DetNet flows does not preclude non-DetNet flows, and
133 the benefits offered DetNet flows should not, except in extreme
134 cases, prevent existing QoS mechanisms from operating in a normal
135 fashion, subject to the bandwidth required for the DetNet flows. A
136 single source-destination pair can trade both DetNet and non-DetNet
137 flows. End systems and applications need not instantiate special
138 interfaces for DetNet flows. Networks are not restricted to certain
139 topologies; connectivity is not restricted. Any application that
140 generates a data flow that can be usefully characterized as having a
141 maximum bandwidth should be able to take advantage of DetNet, as long
142 as the necessary resources can be reserved. Reservations can be made
143 by the application itself, via network management, by an applications
144 controller, or by other means.
146 Many applications of interest to Deterministic Networking require the
147 ability to synchronize the clocks in end systems to a sub-microsecond
148 accuracy. Some of the queue control techniques defined in
149 Section 4.5 also require time synchronization among relay and transit
150 nodes. The means used to achieve time synchronization are not
151 addressed in this document. DetNet should accommodate various
152 synchronization techniques and profiles that are defined elsewhere to
153 solve exchange time in different market segments.
155 Wired and wireless media differ greatly in a number of ways,
156 including connectivity possibilities and the reliability of packet
157 transmission. While some of the techniques described in this
158 document may be applicable to wireless media, the DetNet architecture
159 assumes the use of links with characteristics typical of wired, and
160 not wireless, media.
162 2. Terminology
164 2.1. Terms used in this document
166 The following special terms are used in this document in order to
167 avoid the assumption that a given element in the architecture does or
168 does not have Internet Protocol stack, functions as a router, bridge,
169 firewall, or otherwise plays a particular role at Layer-2 or higher.
171 App-flow
172 The native format of a DetNet flow.
174 destination
175 An end system capable of receiving a DetNet flow.
177 DetNet domain
178 The portion of a network that is DetNet aware. It includes
179 end systems and other DetNet nodes.
181 DetNet flow
182 A DetNet flow is a sequence of packets to which the DetNet
183 service is to be provided.
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, which
188 are eventually merged back into a single DetNet compound
189 flow, at the DetNet transport layer. "Compound" and "member"
190 are strictly relative to each other, not absolutes; a DetNet
191 compound flow comprising multiple DetNet member flows can, in
192 turn, be a member of a higher-order compound.
194 DetNet intermediate node
195 A DetNet relay node or transit node.
197 DetNet edge node
198 An instance of a DetNet relay node that includes either a
199 DetNet service layer proxy function for DetNet service
200 protection (e.g. the addition or removal of packet sequencing
201 information) for one or more end systems, or starts or
202 terminates congestion protection at the DetNet transport
203 layer, analogous to a Label Edge Router (LER).
205 DetNet-UNI
206 User-to-Network Interface with DetNet specific
207 functionalities. It is a packet-based reference point and
208 may provide multiple functions like encapsulation, status,
209 synchronization, etc.
211 end system
212 Commonly called a "host" or "node" in IETF documents, and an
213 "end station" is IEEE 802 documents. End systems of interest
214 to this document are either sources or destinations of DetNet
215 flows. And end system may or may not be DetNet transport
216 layer aware or DetNet service layer aware.
218 link
219 A connection between two DetNet nodes. It may be composed of
220 a physical link or a sub-network technology that can provide
221 appropriate traffic delivery for DetNet flows.
223 DetNet node
224 A DetNet aware end system, transit node, or relay node.
225 "DetNet" may be omitted in some text.
227 Detnet relay node
228 A DetNet node including a service layer function that
229 interconnects different DetNet transport layer paths to
230 provide service protection. A DetNet relay node can be a
231 bridge, a router, a firewall, or any other system that
232 participates in the DetNet service layer. It typically
233 incorporates DetNet transport layer functions as well, in
234 which case it is collocated with a transit node.
236 reservation
237 A trail of configuration between source to destination(s)
238 through transit nodes and subnets associated with a DetNet
239 flow, to provide congestion protection.
241 DetNet service layer
242 The layer at which service protection is provided, packet
243 sequencing, replication, and elimination (Section 3.2.4) or
244 packet encoding.
246 source
247 An end system capable of sourcing a DetNet flow.
249 DetNet transit node
250 A node operating at the DetNet transport layer, that utilizes
251 link layer and/or network layer switching across multiple
252 links and/or sub-networks to provide paths for DetNet service
253 layer functions. Optionally provides congestion protection
254 over those paths. An MPLS LSR is an example of a DetNet
255 transit node.
257 DetNet transport layer
258 The layer that optionally provides congestion protection for
259 DetNet flows over paths provided by the underlying network.
261 TSN
262 Time-Sensitive Networking, TSN is a Task Group of the IEEE
263 802.1 Working Group.
265 2.2. IEEE 802 TSN to DetNet dictionary
267 This section also serves as a dictionary for translating from the
268 terms used by the IEEE 802 Time-Sensitive Networking (TSN) Task Group
269 to those of the DetNet WG.
271 Listener
272 The IEEE 802 term for a destination of a DetNet flow.
274 relay system
275 The IEEE 802 term for a DetNet intermediate node.
277 Stream
278 The IEEE 802 term for a DetNet flow.
280 Talker
281 The IEEE 802 term for the source of a DetNet flow.
283 3. Providing the DetNet Quality of Service
285 3.1. Primary goals defining the DetNet QoS
287 The DetNet Quality of Service can be expressed in terms of:
289 o Minimum and maximum end-to-end latency from source to destination;
290 timely delivery and jitter avoidance derive from these constraints
292 o Probability of loss of a packet, under various assumptions as to
293 the operational states of the nodes and links. A derived property
294 is whether it is acceptable to deliver a duplicate packet, which
295 is an inherent risk in highly reliable and/or broadcast
296 transmissions
298 It is a distinction of DetNet that it is concerned solely with worst-
299 case values for the end-to-end latency. Average, mean, or typical
300 values are of no interest, because they do not affect the ability of
301 a real-time system to perform its tasks. In general, a trivial
302 priority-based queuing scheme will give better average latency to a
303 data flow than DetNet, but of course, the worst-case latency can be
304 essentially unbounded.
306 Three techniques are used by DetNet to provide these qualities of
307 service:
309 o Congestion protection (Section 3.2.1).
311 o Explicit routes (Section 3.2.2).
313 o Service protection (Section 3.2.4).
315 Congestion protection operates by reserving resources along the path
316 of a DetNet Flow, e.g. buffer space or link bandwidth. Congestion
317 protection greatly reduces, or even eliminates entirely, packet loss
318 due to output packet congestion within the network, but it can only
319 be supplied to a DetNet flow that is limited at the source to a
320 maximum packet size and transmission rate.
322 Congestion protection addresses both of the DetNet QoS requirements
323 (latency and packet loss). Given that DetNet nodes have a finite
324 amount of buffer space, congestion protection necessarily results in
325 a maximum end-to-end latency. It also addresses the largest
326 contribution to packet loss, which is buffer congestion.
328 After congestion, the most important contributions to packet loss are
329 typically from random media errors and equipment failures. Service
330 protection is the name for the mechanisms used by DetNet to address
331 these losses. The mechanisms employed are constrained by the
332 requirement to meet the users' latency requirements. Packet
333 replication and elimination (Section 3.2.4) is described in this
334 document to provide service protection; others may be found. This
335 mechanism distributes the contents of DetNet flows over multiple
336 paths in time and/or space, so that the loss of some of the paths
337 does need not cause the loss of any packets. The paths are typically
338 (but not necessarily) explicit routes, so that they cannot suffer
339 temporary interruptions caused by the reconvergence of routing or
340 bridging protocols.
342 These three techniques can be applied independently, giving eight
343 possible combinations, including none (no DetNet), although some
344 combinations are of wider utility than others. This separation keeps
345 the protocol stack coherent and maximizes interoperability with
346 existing and developing standards in this (IETF) and other Standards
347 Development Organizations. Some examples of typical expected
348 combinations:
350 o Explicit routes plus service protection are exactly the techniques
351 employed by [HSR-PRP]. Explicit routes are achieved by limiting
352 the physical topology of the network, and the sequentialization,
353 replication, and duplicate elimination are facilitated by packet
354 tags added at the front or the end of Ethernet frames.
356 o Congestion protection alone is is offered by IEEE 802.1 Audio
357 Video bridging [IEEE802.1BA-2011]. As long as the network suffers
358 no failures, zero congestion loss can be achieved through the use
359 of a reservation protocol (MSRP), shapers in every bridge, and a
360 bit of network calculus.
362 o Using all three together gives maximum protection.
364 There are, of course, simpler methods available (and employed, today)
365 to achieve levels of latency and packet loss that are satisfactory
366 for many applications. Prioritization and over-provisioning is one
367 such technique. However, these methods generally work best in the
368 absence of any significant amount of non-critical traffic in the
369 network (if, indeed, such traffic is supported at all), or work only
370 if the critical traffic constitutes only a small portion of the
371 network's theoretical capacity, or work only if all systems are
372 functioning properly, or in the absence of actions by end systems
373 that disrupt the network's operations.
375 There are any number of methods in use, defined, or in progress for
376 accomplishing each of the above techniques. It is expected that this
377 DetNet Architecture will assist various vendors, users, and/or
378 "vertical" Standards Development Organizations (dedicated to a single
379 industry) to make selections among the available means of
380 implementing DetNet networks.
382 3.2. Mechanisms to achieve DetNet Qos
384 3.2.1. Congestion protection
386 The primary means by which DetNet achieves its QoS assurances is to
387 reduce, or even completely eliminate, congestion at an output port as
388 a cause of packet loss. Given that a DetNet flow cannot be
389 throttled, this can be achieved only by the provision of sufficient
390 buffer storage at each hop through the network to ensure that no
391 packets are dropped due to a lack of buffer storage.
393 Ensuring adequate buffering requires, in turn, that the source, and
394 every intermediate node along the path to the destination (or nearly
395 every node -- see Section 4.3.3) be careful to regulate its output to
396 not exceed the data rate for any DetNet flow, except for brief
397 periods when making up for interfering traffic. Any packet sent
398 ahead of its time potentially adds to the number of buffers required
399 by the next hop, and may thus exceed the resources allocated for a
400 particular DetNet flow.
402 The low-level mechanisms described in Section 4.5 provide the
403 necessary regulation of transmissions by an end system or
404 intermediate node to provide congestion protection. The reservation
405 of the bandwidth and buffers for a DetNet flow requires the
406 provisioning described in Section 4.9. A DetNet node may have other
407 resources requiring allocation and/or scheduling, that might
408 otherwise be over-subscribed and trigger the rejection of a
409 reservation.
411 3.2.2. Explicit routes
413 In networks controlled by typical peer-to-peer protocols such as IEEE
414 802.1 ISIS bridged networks or IETF OSPF routed networks, a network
415 topology event in one part of the network can impact, at least
416 briefly, the delivery of data in parts of the network remote from the
417 failure or recovery event. Thus, even redundant paths through a
418 network, if controlled by the typical peer-to-peer protocols, do not
419 eliminate the chances of brief losses of contact.
421 Many real-time networks rely on physical rings or chains of two-port
422 devices, with a relatively simple ring control protocol. This
423 supports redundant paths for service protection with a minimum of
424 wiring. As an additional benefit, ring topologies can often utilize
425 different topology management protocols than those used for a mesh
426 network, with a consequent reduction in the response time to topology
427 changes. Of course, this comes at some cost in terms of increased
428 hop count, and thus latency, for the typical path.
430 In order to get the advantages of low hop count and still ensure
431 against even very brief losses of connectivity, DetNet employs
432 explicit routes, where the path taken by a given DetNet flow does not
433 change, at least immediately, and likely not at all, in response to
434 network topology events. Service protection (Section 3.2.4) over
435 explicit routes provides a high likelihood of continuous
436 connectivity. Explicit routes are commonly used in MPLS TE LSPs.
438 3.2.3. Jitter Reduction
440 A core objective of DetNet is to enable the convergence of Non-IP
441 networks onto a common network infrastructure. This requires the
442 accurate emulation of currently deployed mission-specific networks,
443 which typically rely on point-to-point analog (e.g. 4-20mA
444 modulation) and serial-digital cables (or buses) for highly reliable,
445 synchronized and jitter-free communications. While the latency of
446 analog transmissions is basically the speed of light, legacy serial
447 links are usually slow (in the order of Kbps) compared to, say, GigE,
448 and some latency is usually acceptable. What is not acceptable is
449 the introduction of excessive jitter, which may, for instance, affect
450 the stability of control systems.
452 Applications that are designed to operate on serial links usually do
453 not provide services to recover the jitter, because jitter simply
454 does not exists there. Streams of information are expected to be
455 delivered in-order and the precise time of reception influences the
456 processes. In order to converge such existing applications, there is
457 a desire to emulate all properties of the serial cable, such as clock
458 transportation, perfect flow isolation and fixed latency. While
459 minimal jitter (in the form of specifying minimum, as well as
460 maximum, end-to-end latency) is supported by DetNet, there are
461 practical limitations on packet-based networks in this regard. In
462 general, users are encouraged to use, instead of, "do this when you
463 get the packet," a combination of:
465 o Sub-microsecond time synchronization among all source and
466 destination end systems, and
468 o Time-of-execution fields in the application packets.
470 Jitter reduction is provided by the mechanisms described in
471 Section 4.5 that also provide congestion protection.
473 3.2.4. Packet Replication and Elimination
475 After congestion loss has been eliminated, the most important causes
476 of packet loss are random media and/or memory faults, and equipment
477 failures. Both causes of packet loss can be greatly reduced by
478 spreading the data in a packet over multiple transmissions. One such
479 method for service protection is described in this section, which
480 sends the same packets over multiple paths.
482 Packet replication and elimination, also known as seamless redundancy
483 [HSR-PRP], or 1+1 hitless protection, is a function of the DetNet
484 service layer. It involves three capabilities:
486 o Providing sequencing information, once, at or near the source, to
487 the packets of a DetNet compound flow. This may be done by adding
488 a sequence number or time stamp as part of DetNet, or may be
489 inherent in the packet, e.g. in a transport protocol, or
490 associated to other physical properties such as the precise time
491 (and radio channel) of reception of the packet. Section 3.2.2.
493 o Replicating these packets into multiple DetNet member flows and,
494 typically, sending them along at least two different paths to the
495 destination(s), e.g. over the explicit routes of
497 o Eliminating duplicated packets. This may be done at any step
498 along the path to save network resources further down, in
499 particular if multiple Replication points exist. But the most
500 common case is to perform this operation at the very edge of the
501 DetNet network, preferably in or near the receiver.
503 This function is a "hitless" version of, e.g., the 1+1 linear
504 protection in [RFC6372]. That is, instead of switching from one flow
505 to the other when a failure of a flow is detected, DetNet combines
506 both flows, and performs a packet-by-packet selection of which to
507 discard, based on sequence number.
509 In the simplest case, this amounts to replicating each packet in a
510 source that has two interfaces, and conveying them through the
511 network, along separate paths, to the similarly dual-homed
512 destinations, that discard the extras. This ensures that one path
513 (with zero congestion loss) remains, even if some intermediate node
514 fails. The sequence numbers can also be used for loss detection and
515 for re-ordering.
517 Detnet relay nodes in the network can provide replication and
518 elimination facilities at various points in the network, so that
519 multiple failures can be accommodated.
521 This is shown in the following figure, where the two relay nodes each
522 replicate (R) the DetNet flow on input, sending the DetNet member
523 flows to both the other relay node and to the end system, and
524 eliminate duplicates (E) on the output interface to the right-hand
525 end system. Any one link in the network can fail, and the Detnet
526 compound flow can still get through. Furthermore, two links can
527 fail, as long as they are in different segments of the network.
529 Packet replication and elimination
531 > > > > > > > > > relay > > > > > > > >
532 > /------------+ R node E +------------\ >
533 > / v + ^ \ >
534 end R + v | ^ + E end
535 system + v | ^ + system
536 > \ v + ^ / >
537 > \------------+ R relay E +-----------/ >
538 > > > > > > > > > node > > > > > > > >
540 Figure 1
542 Packet replication and elimination does not react to and correct
543 failures; it is entirely passive. Thus, intermittent failures,
544 mistakenly created packet filters, or misrouted data is handled just
545 the same as the equipment failures that are detected handled by
546 typical routing and bridging protocols.
548 If packet replication and elimination is used over paths providing
549 congestion protection (Section 3.2.1), and member flows that take
550 different-length paths through the network are combined, a merge
551 point may require extra buffering to equalize the delays over the
552 different paths. This equalization ensures that the resultant
553 compound flow will not exceed its contracted bandwidth even after one
554 or the other of the paths is restored after a failure.
556 3.3. Secondary goals for DetNet
558 Many applications require DetNet to provide additional services,
559 including coesistence with other QoS mechanisms Section 3.3.1 and
560 protection against misbehaving transmitters Section 3.3.2.
562 3.3.1. Coexistence with normal traffic
564 A DetNet network supports the dedication of a high proportion (e.g.
565 75%) of the network bandwidth to DetNet flows. But, no matter how
566 much is dedicated for DetNet flows, it is a goal of DetNet to coexist
567 with existing Class of Service schemes (e.g., DiffServ). It is also
568 important that non-DetNet traffic not disrupt the DetNet flow, of
569 course (see Section 3.3.2 and Section 5). For these reasons:
571 o Bandwidth (transmission opportunities) not utilized by a DetNet
572 flow are available to non-DetNet packets (though not to other
573 DetNet flows).
575 o DetNet flows can be shaped or scheduled, in order to ensure that
576 the highest-priority non-DetNet packet also is ensured a worst-
577 case latency (at any given hop).
579 o When transmission opportunities for DetNet flows are scheduled in
580 detail, then the algorithm constructing the schedule should leave
581 sufficient opportunities for non-DetNet packets to satisfy the
582 needs of the users of the network. Detailed scheduling can also
583 permit the time-shared use of buffer resources by different DetNet
584 flows.
586 Ideally, the net effect of the presence of DetNet flows in a network
587 on the non-DetNet packets is primarily a reduction in the available
588 bandwidth.
590 3.3.2. Fault Mitigation
592 One key to building robust real-time systems is to reduce the
593 infinite variety of possible failures to a number that can be
594 analyzed with reasonable confidence. DetNet aids in the process by
595 providing filters and policers to detect DetNet packets received on
596 the wrong interface, or at the wrong time, or in too great a volume,
597 and to then take actions such as discarding the offending packet,
598 shutting down the offending DetNet flow, or shutting down the
599 offending interface.
601 It is also essential that filters and service remarking be employed
602 at the network edge to prevent non-DetNet packets from being mistaken
603 for DetNet packets, and thus impinging on the resources allocated to
604 DetNet packets.
606 There exist techniques, at present and/or in various stages of
607 standardization, that can perform these fault mitigation tasks that
608 deliver a high probability that misbehaving systems will have zero
609 impact on well-behaved DetNet flows, except of course, for the
610 receiving interface(s) immediately downstream of the misbehaving
611 device. Examples of such techniques include traffic policing
612 functions (e.g. [RFC2475]) and separating flows into per-flow rate-
613 limited queues.
615 4. DetNet Architecture
617 4.1. DetNet stack model
619 4.1.1. Representative Protocol Stack Model
621 Figure 2 illustrates a conceptual DetNet data plane layering model.
622 One may compare it to that in [IEEE802.1CB], Annex C, a work in
623 progress.
625 DetNet data plane protocol stack
627 | packets going | ^ packets coming ^
628 v down the stack v | up the stack |
629 +----------------------+ +-----------------------+
630 | Source | | Destination |
631 +----------------------+ +-----------------------+
632 | Service layer | | Service layer |
633 | Packet sequencing | | Duplicate elimination |
634 | Flow duplication | | Flow merging |
635 | Packet encoding | | Packet decoding |
636 +----------------------+ +-----------------------+
637 | Transport layer | | Transport layer |
638 | Congestion prot. | | Congestion prot. |
639 +----------------------+ +-----------------------+
640 | Lower layers | | Lower layers |
641 +----------------------+ +-----------------------+
642 v ^
643 \_________________________/
645 Figure 2
647 Not all layers are required for any given application, or even for
648 any given network. The layers are, from top to bottom:
650 Application
651 Shown as "source" and "destination" in the diagram.
653 OAM
654 Operations, Administration, and Maintenance leverages in-band
655 and out-of-and signaling that validates whether the service
656 is effectively obtained within QoS constraints. OAM is not
657 shown in Figure 2; it may reside in any number of the layers.
658 OAM can involve specific tagging added in the packets for
659 tracing implementation or network configuration errors;
660 traceability enables to find whether a packet is a replica,
661 which relay node performed the replication, and which segment
662 was intended for the replica.
664 Packet sequencing
665 As part of DetNet service protection, supplies the sequence
666 number for packet replication and elimination
667 (Section 3.2.4). Peers with Duplicate elimination. This
668 layer is not needed if a higher-layer transport protocol is
669 expected to perform any packet sequencing and duplicate
670 elimination required by the DetNet flow duplication.
672 Duplicate elimination
673 As part of the DetNet service layer, based on the sequenced
674 number supplied by its peer, packet sequencing, Duplicate
675 elimination discards any duplicate packets generated by
676 DetNet flow duplication. It can operate on member flows,
677 compound flows, or both. The duplication may also be
678 inferred from other information such as the precise time of
679 reception in a scheduled network. The duplicate elimination
680 layer may also perform resequencing of packets to restore
681 packet order in a flow that was disrupted by the loss of
682 packets on one or another of the multiple paths taken.
684 Flow duplication
685 As part of DetNet service protection, packets that belong to
686 a DetNet compound flow are replicated into two or more DetNet
687 member flows. This function is separate from packet
688 sequencing. Flow duplication can be an explicit duplication
689 and remarking of packets, or can be performed by, for
690 example, techniques similar to ordinary multicast
691 replication. Peers with DetNet flow merging.
693 Network flow merging
694 As part of DetNet service protection, merges DetNet member
695 flows together for packets coming up the stack belonging to a
696 specific DetNet compound flow. Peers with DetNet flow
697 duplication. DetNet flow merging, together with packet
698 sequencing, duplicate elimination, and DetNet flow
699 duplication, performs packet replication and elimination
700 (Section 3.2.4).
702 Packet encoding
703 As part of DetNet service protection, as an alternative to
704 packet sequencing and flow duplication, packet encoding
705 combines the information in multiple DetNet packets, perhaps
706 from different DetNet compound flows, and transmits that
707 information in packets on different DetNet member Flows.
708 Peers with Packet decoding.
710 Packet decoding
711 As part of DetNet service protection, as an alternative to
712 flow merging and duplicate elimination, packet decoding takes
713 packets from different DetNet member flows, and computes from
714 those packets the original DetNet packets from the compound
715 flows input to packet encoding. Peers with Packet encoding.
717 Congestion protection
718 The DetNet transport layer provides congestion protection.
719 See Section 4.5. The actual queuing and shaping mechanisms
720 are typically provided by underlying subnet layers, but since
721 these are can be closely associated with the means of
722 providing paths for DetNet flows (e.g. MPLS LSPs or {VLAN,
723 multicast destination MAC address} pairs), the path and the
724 congestion protection are conflated in this figure.
726 The packet sequencing and duplication elimination functions at the
727 source and destination ends of a DetNet compound flow may be
728 performed either in the end system or in a DetNet edge node. The
729 reader must not confuse a DetNet edge function with other kinds of
730 edge functions, e.g. an Label Edge Router, although the two functions
731 may be performed together. The DetNet edge function is concerned
732 with sequencing packets belonging to DetNet flows. The LER with
733 encapsulating/decapsulating packets for transport, and is considered
734 part of the network underlying the DetNet transport layer.
736 4.1.2. DetNet Data Plane Overview
738 A "Deterministic Network" will be composed of DetNet enabled nodes
739 i.e., End Systems, Edge Nodes, Relay Nodes and collectively deliver
740 DetNet services. DetNet enabled nodes are interconnected via Transit
741 Nodes (i.e., routers) which support DetNet, but are not DetNet
742 service aware. Transit nodes see DetNet nodes as end points. All
743 DetNet enabled nodes are connect to sub-networks, where a point-to-
744 point link is also considered as a simple sub-network. These sub-
745 networks will provide DetNet compatible service for support of DetNet
746 traffic. Examples of sub-networks include IEEE 802.1 TSN and OTN.
747 Of course, multi-layer DetNet systems may also be possible, where one
748 DetNet appears as a sub-network, and provides service to, a higher
749 layer DetNet system. A simple DetNet concept network is shown in
750 Figure 3.
752 TSN Edge Transit Relay DetNet
753 End System Node Node Node End System
755 +---------+ +.........+ +---------+
756 | Appl. |<---:Svc Proxy:-- End to End Service ---------->| Appl. |
757 +---------+ +---------+ +---------+ +---------+
758 | TSN | |TSN| |Svc|<-- DetNet flow ---: Service :-->| Service |
759 +---------+ +---+ +---+ +---------+ +---------+ +---------+
760 |Transport| |Trp| |Trp| |Transport| |Trp| |Trp| |Transport|
761 +-------.-+ +-.-+ +-.-+ +--.----.-+ +-.-+ +-.-+ +---.-----+
762 : Link : / ,-----. \ : Link : / ,-----. \
763 +........+ +-[ Sub ]-+ +........+ +-[ Sub ]-+
764 [Network] [Network]
765 `-----' `-----'
767 Figure 3: A Simple DetNet Enabled Network
769 Distinguishing the function of these two DetNet data plane layers,
770 the DetNet service layer and the DetNet transport layer, helps to
771 explore and evaluate various combinations of the data plane solutions
772 available. This separation of DetNet layers, while helpful, should
773 not be considered as formal requirement. For example, some
774 technologies may violate these strict layers and still be able to
775 deliver a DetNet service.
777 .
778 .
779 +-----------+
780 | Service | PW, RTP/(UDP), GRE
781 +-----------+
782 | Transport | (UDP)/IPv6, (UDP)/IPv4, MPLS LSPs, BIER
783 +-----------+
784 .
785 .
787 Figure 4: DetNet adaptation to data plane
789 In some networking scenarios, the end system initially provides a
790 DetNet flow encapsulation, which contains all information needed by
791 DetNet nodes (e.g., Real-time Transport Protocol (RTP) [RFC3550]
792 based DetNet flow transported over a native UDP/IP network or
793 PseudoWire). In other scenarios, the encapsulation formats might
794 differ significantly. As an example, a CPRI "application's" I/Q data
795 mapped directly to Ethernet frames may have to be transported over an
796 MPLS-based packet switched network (PSN).
798 There are many valid options to create a data plane solution for
799 DetNet traffic by selecting a technology approach for the DetNet
800 service layer and also selecting a technology approach for the DetNet
801 transport layer. There are a high number of valid combinations.
803 One of the most fundamental differences between different potential
804 data plane options is the basic addressing and headers used by DetNet
805 end systems. For example, is the basic service a Layer 2 (e.g.,
806 Ethernet) or Layer 3 (i.e., IP) service. This decision impacts how
807 DetNet end systems are addressed, and the basic forwarding logic for
808 the DetNet service layer.
810 4.1.3. Network reference model
812 The figure below shows another view of the DetNet service related
813 reference points and main components (Figure 5).
815 DetNet DetNet
816 end system end system
817 _ _
818 / \ +----DetNet-UNI (U) / \
819 /App\ | /App\
820 /-----\ | /-----\
821 | NIC | v ________ | NIC |
822 +--+--+ _____ / \ DetNet-UNI (U) --+ +--+--+
823 | / \__/ \ | |
824 | / +----+ +----+ \_____ | |
825 | / | | | | \_______ | |
826 +------U PE +----+ P +----+ \ _ v |
827 | | | | | | | ___/ \ |
828 | +--+-+ +----+ | +----+ | / \_ |
829 \ | | | | | / \ |
830 \ | +----+ +--+-+ +--+PE |-------- U------+
831 \ | | | | | | | | | \_ _/
832 \ +---+ P +----+ P +--+ +----+ | \____/
833 \___ | | | | /
834 \ +----+__ +----+ DetNet-1 DetNet-2
835 | \_____/ \___________/ |
836 | |
837 | | End-to-End-Service | | | |
838 <---------------------------------------------------------------->
839 | | DetNet-Service | | | |
840 | <--------------------------------------------------> |
841 | | | | | |
843 Figure 5: DetNet Service Reference Model (multi-domain)
845 DetNet-UNIs ("U" in Figure 5) are assumed in this document to be
846 packet-based reference points and provide connectivity over the
847 packet network. A DetNet-UNI may provide multiple functions, e.g.,
848 it may add networking technology specific encapsulation to the DetNet
849 flows if necessary; it may provide status of the availability of the
850 connection associated to a reservation; it may provide a
851 synchronization service for the end system; it may carry enough
852 signaling to place the reservation in a network without a controller,
853 or if the controller only deals with the network but not the end
854 points. Internal reference points of end systems (between the
855 application and the NIC) are more challenging from control
856 perspective and they may have extra requirements (e.g., in-order
857 delivery is expected in end system internal reference points, whereas
858 it is considered optional over the DetNet-UNI), therefore not covered
859 in this document.
861 4.2. DetNet systems
863 4.2.1. End system
865 The native data flow between the source/destination end systems is
866 referred to as application-flow (App-flow). The traffic
867 characteristics of an App-flow can be CBR (constant bit rate) or VBR
868 (variable bit rate) and can have L1 or L2 or L3 encapsulation (e.g.,
869 TDM (time-division multiplexing), Ethernet, IP). These
870 characteristics are considered as input for resource reservation and
871 might be simplified to ensure determinism during transport (e.g.,
872 making reservations for the peak rate of VBR traffic, etc.).
874 An end system may or may not be DetNet transport layer aware or
875 DetNet service layer aware. That is, an end system may or may not
876 contain DetNet specific functionality. End systems with DetNet
877 functionalities may have the same or different transport layer as the
878 connected DetNet domain. Grouping of end systems are shown in
879 Figure 6.
881 End system
882 |
883 |
884 | DetNet aware ?
885 / \
886 +------< >------+
887 NO | \ / | YES
888 | v |
889 DetNet unaware |
890 End system |
891 | Service/
892 | Transport
893 / \ aware ?
894 +--------< >-------------+
895 t-aware | \ / | s-aware
896 | v |
897 | | both |
898 | | |
899 DetNet t-aware | DetNet s-aware
900 End system | End system
901 v
902 DetNet st-aware
903 End system
905 Figure 6: Grouping of end systems
907 Note some known use cases for end systems:
909 o DetNet unaware: The classic case requiring network proxies.
911 o DetNet t-aware: An extant TSN system. It knows about some TSN
912 functions (e.g., reservation), but not about replication/
913 elimination.
915 o DetNet s-aware: An extant IEC 62439-3 system. It supplies
916 sequence numbers, but doesn't know about zero congestion loss.
918 o DetNet st-aware: A full functioning DetNet end station, it has
919 DetNet functionalities and usually the same forwarding paradigm as
920 the connected DetNet domain. It can be treated as an integral
921 part of the DetNet domain .
923 4.2.2. DetNet edge, relay, and transit nodes
925 As shown in Figure 3, DetNet edge nodes providing proxy service and
926 DetNet relay nodes providing the DetNet service layer are DetNet-
927 aware, and DetNet transit nodes need only be aware of the DetNet
928 transport layer.
930 In general, if a DetNet flow passes through one or more DetNet-
931 unaware network node between two DetNet nodes providing the DetNet
932 transport layer for that flow, there is a potential for disruption or
933 failure of the DetNet QoS. A network administrator needs to ensure
934 that the DetNet-unaware network nodes are configured to minimize the
935 chances of packet loss and delay, and provision enough exra buffer
936 space in the DetNet transit node following the DetNet-unaware network
937 nodes to absorb the induced latency variations.
939 4.3. DetNet flows
941 4.3.1. DetNet flow types
943 A DetNet flow can have different formats during while it is
944 transported between the peer end systems. Therefore, the following
945 possible types / formats of a DetNet flow are distinguished in this
946 document:
948 o App-flow: native format of a DetNet flow. It does not contain any
949 DetNet related attributes.
951 o DetNet-t-flow: specific format of a DetNet flow. Only requires
952 the congestion / latency features provided by the Detnet transport
953 layer.
955 o DetNet-s-flow: specific format of a DetNet flow. Only requires
956 the replication/elimination feature ensured by the DetNet service
957 layer.
959 o DetNet-st-flow: specific format of a DetNet flow. It requires
960 both DetNet service layer and DetNet transport layer functions
961 during forwarding.
963 4.3.2. Source guarantees
965 For the purposes of congestion protection, DetNet flows can be
966 synchronous or asynchronous. In synchronous DetNet flows, at least
967 the intermediate nodes (and possibly the end systems) are closely
968 time synchronized, typically to better than 1 microsecond. By
969 transmitting packets from different DetNet flows or classes of DetNet
970 flows at different times, using repeating schedules synchronized
971 among the intermediate nodes, resources such as buffers and link
972 bandwidth can be shared over the time domain among different DetNet
973 flows. There is a tradeoff among techniques for synchronous DetNet
974 flows between the burden of fine-grained scheduling and the benefit
975 of reducing the required resources, especially buffer space.
977 In contrast, asynchronous DetNet flows are not coordinated with a
978 fine-grained schedule, so relay and end systems must assume worst-
979 case interference among DetNet flows contending for buffer resources.
980 Asynchronous DetNet flows are characterized by:
982 o A maximum packet size;
984 o An observation interval; and
986 o A maximum number of transmissions during that observation
987 interval.
989 These parameters, together with knowledge of the protocol stack used
990 (and thus the size of the various headers added to a packet), limit
991 the number of bit times per observation interval that the DetNet flow
992 can occupy the physical medium.
994 The source promises that these limits will not be exceeded. If the
995 source transmits less data than this limit allows, the unused
996 resources such as link bandwidth can be made available by the system
997 to non-DetNet packets. However, making those resources available to
998 DetNet packets in other DetNet flows would serve no purpose. Those
999 other DetNet flows have their own dedicated resources, on the
1000 assumption that all DetNet flows can use all of their resources over
1001 a long period of time.
1003 There is no provision in DetNet for throttling DetNet flows (reducing
1004 the transmission rate via feedback); the assumption is that a DetNet
1005 flow, to be useful, must be delivered in its entirety. That is,
1006 while any useful application is written to expect a certain number of
1007 lost packets, the real-time applications of interest to DetNet demand
1008 that the loss of data due to the network is extraordinarily
1009 infrequent.
1011 Although DetNet strives to minimize the changes required of an
1012 application to allow it to shift from a special-purpose digital
1013 network to an Internet Protocol network, one fundamental shift in the
1014 behavior of network applications is impossible to avoid: the
1015 reservation of resources before the application starts. In the first
1016 place, a network cannot deliver finite latency and practically zero
1017 packet loss to an arbitrarily high offered load. Secondly, achieving
1018 practically zero packet loss for unthrottled (though bandwidth
1019 limited) DetNet flows means that bridges and routers have to dedicate
1020 buffer resources to specific DetNet flows or to classes of DetNet
1021 flows. The requirements of each reservation have to be translated
1022 into the parameters that control each system's queuing, shaping, and
1023 scheduling functions and delivered to the hosts, bridges, and
1024 routers.
1026 4.3.3. Incomplete Networks
1028 The presence in the network of transit nodes or subnets that are not
1029 fully capable of offering DetNet services complicates the ability of
1030 the intermediate nodes and/or controller to allocate resources, as
1031 extra buffering, and thus extra latency, must be allocated at points
1032 downstream from the non-DetNet intermediate node for a DetNet flow.
1034 4.4. Traffic Engineering for DetNet
1036 Traffic Engineering Architecture and Signaling (TEAS) [TEAS] defines
1037 traffic-engineering architectures for generic applicability across
1038 packet and non-packet networks. From TEAS perspective, Traffic
1039 Engineering (TE) refers to techniques that enable operators to
1040 control how specific traffic flows are treated within their networks.
1042 Because if its very nature of establishing explicit optimized paths,
1043 Deterministic Networking can be seen as a new, specialized branch of
1044 Traffic Engineering, and inherits its architecture with a separation
1045 into planes.
1047 The Deterministic Networking architecture is thus composed of three
1048 planes, a (User) Application Plane, a Controller Plane, and a Network
1049 Plane, which echoes that of Figure 1 of Software-Defined Networking
1050 (SDN): Layers and Architecture Terminology [RFC7426].:
1052 4.4.1. The Application Plane
1054 Per [RFC7426], the Application Plane includes both applications and
1055 services. In particular, the Application Plane incorporates the User
1056 Agent, a specialized application that interacts with the end user /
1057 operator and performs requests for Deterministic Networking services
1058 via an abstract Flow Management Entity, (FME) which may or may not be
1059 collocated with (one of) the end systems.
1061 At the Application Plane, a management interface enables the
1062 negotiation of flows between end systems. An abstraction of the flow
1063 called a Traffic Specification (TSpec) provides the representation.
1064 This abstraction is used to place a reservation over the (Northbound)
1065 Service Interface and within the Application plane. It is associated
1066 with an abstraction of location, such as IP addresses and DNS names,
1067 to identify the end systems and eventually specify intermediate
1068 nodes.
1070 4.4.2. The Controller Plane
1072 The Controller Plane corresponds to the aggregation of the Control
1073 and Management Planes in [RFC7426], though Common Control and
1074 Measurement Plane (CCAMP) [CCAMP] makes an additional distinction
1075 between management and measurement. When the logical separation of
1076 the Control, Measurement and other Management entities is not
1077 relevant, the term Controller Plane is used for simplicity to
1078 represent them all, and the term controller refers to any device
1079 operating in that plane, whether is it a Path Computation entity or a
1080 Network Management entity (NME). The Path Computation Element (PCE)
1081 [PCE] is a core element of a controller, in charge of computing
1082 Deterministic paths to be applied in the Network Plane.
1084 A (Northbound) Service Interface enables applications in the
1085 Application Plane to communicate with the entities in the Controller
1086 Plane.
1088 One or more PCE(s) collaborate to implement the requests from the FME
1089 as Per-Flow Per-Hop Behaviors installed in the intermediate nodes for
1090 each individual flow. The PCEs place each flow along a deterministic
1091 sequence of intermediate nodes so as to respect per-flow constraints
1092 such as security and latency, and optimize the overall result for
1093 metrics such as an abstract aggregated cost. The deterministic
1094 sequence can typically be more complex than a direct sequence and
1095 include redundancy path, with one or more packet replication and
1096 elimination points.
1098 4.4.3. The Network Plane
1100 The Network Plane represents the network devices and protocols as a
1101 whole, regardless of the Layer at which the network devices operate.
1102 It includes Forwarding Plane (data plane), Application, and
1103 Operational Plane (control plane) aspects.
1105 The network Plane comprises the Network Interface Cards (NIC) in the
1106 end systems, which are typically IP hosts, and intermediate nodes,
1107 which are typically IP routers and switches. Network-to-Network
1108 Interfaces such as used for Traffic Engineering path reservation in
1109 [RFC5921], as well as User-to-Network Interfaces (UNI) such as
1110 provided by the Local Management Interface (LMI) between network and
1111 end systems, are both part of the Network Plane, both in the control
1112 plane and the data plane.
1114 A Southbound (Network) Interface enables the entities in the
1115 Controller Plane to communicate with devices in the Network Plane.
1116 This interface leverages and extends TEAS to describe the physical
1117 topology and resources in the Network Plane.
1119 Flow Management Entity
1121 End End
1122 System System
1124 -+-+-+-+-+-+-+ Northbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
1126 PCE PCE PCE PCE
1128 -+-+-+-+-+-+-+ Southbound -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
1130 intermediate intermed. intermed. intermed.
1131 Node Node Node Node
1132 NIC NIC
1133 intermediate intermed. intermed. intermed.
1134 Node Node Node Node
1136 Figure 7
1138 The intermediate nodes (and eventually the end systems NIC) expose
1139 their capabilities and physical resources to the controller (the
1140 PCE), and update the PCE with their dynamic perception of the
1141 topology, across the Southbound Interface. In return, the PCE(s) set
1142 the per-flow paths up, providing a Flow Characterization that is more
1143 tightly coupled to the intermediate node Operation than a TSpec.
1145 At the Network plane, intermediate nodes may exchange information
1146 regarding the state of the paths, between adjacent systems and
1147 eventually with the end systems, and forward packets within
1148 constraints associated to each flow, or, when unable to do so,
1149 perform a last resort operation such as drop or declassify.
1151 This specification focuses on the Southbound interface and the
1152 operation of the Network Plane.
1154 4.5. Queuing, Shaping, Scheduling, and Preemption
1156 DetNet achieves congestion protection and bounded delivery latency by
1157 reserving bandwidth and buffer resources at every hop along the path
1158 of the DetNet flow. The reservation itself is not sufficient,
1159 however. Implementors and users of a number of proprietary and
1160 standard real-time networks have found that standards for specific
1161 data plane techniques are required to enable these assurances to be
1162 made in a multi-vendor network. The fundamental reason is that
1163 latency variation in one system results in the need for extra buffer
1164 space in the next-hop system(s), which in turn, increases the worst-
1165 case per-hop latency.
1167 Standard queuing and transmission selection algorithms allow a
1168 central controller to compute the latency contribution of each
1169 transit node to the end-to-end latency, to compute the amount of
1170 buffer space required in each transit node for each incremental
1171 DetNet flow, and most importantly, to translate from a flow
1172 specification to a set of values for the managed objects that control
1173 each relay or end system. The IEEE 802 has specified (and is
1174 specifying) a set of queuing, shaping, and scheduling algorithms that
1175 enable each transit node (bridge or router), and/or a central
1176 controller, to compute these values. These algorithms include:
1178 o A credit-based shaper [IEEE802.1Q-2014] Clause 34.
1180 o Time-gated queues governed by a rotating time schedule,
1181 synchronized among all transit nodes [IEEE802.1Qbv].
1183 o Synchronized double (or triple) buffers driven by synchronized
1184 time ticks. [IEEE802.1Qch].
1186 o Pre-emption of an Ethernet packet in transmission by a packet with
1187 a more stringent latency requirement, followed by the resumption
1188 of the preempted packet [IEEE802.1Qbu], [IEEE802.3br].
1190 While these techniques are currently embedded in Ethernet and
1191 bridging standards, we can note that they are all, except perhaps for
1192 packet preemption, equally applicable to other media than Ethernet,
1193 and to routers as well as bridges.
1195 4.6. Service instance
1197 A Service instance represents all the functions required on a node to
1198 allow the end-to-end service between the UNIs.
1200 The DetNet network reference model is shown in Figure 8 for a DetNet-
1201 Service scenario (i.e. between two DetNet-UNIs). In this figure, the
1202 end systems ("A" and "B") are connected directly to the edge nodes of
1203 the IP/MPLS network ("PE1" and "PE2"). End-systems participating
1204 DetNet communication may require connectivity before setting up an
1205 App-flow that requires the DetNet service. Such a connectivity
1206 related service instance and the one dedicated for DetNet service
1207 share the same access. Packets belonging to a DetNet flow are
1208 selected by a filter configured on the access ("F1" and "F2"). As a
1209 result, data flow specific access ("access-A + F1" and "access-B +
1210 F2") are terminated in the flow specific service instance ("SI-1" and
1211 "SI-2"). A tunnel is used to provide connectivity between the
1212 service instances.
1214 The tunnel is used to transport exclusively the packets of the DetNet
1215 flow between "SI-1" and "SI-2". The service instances are configured
1216 to implement DetNet functions and a flow specific routing or bridging
1217 function depending on what connectivity the participating end systems
1218 require (L3 or L2). The service instance and the tunnel may or may
1219 not be shared by multiple DetNet flows. Sharing the service instance
1220 by multiple DetNet flows requires properly populated forwarding
1221 tables of the service instance.
1223 access-A access-B
1224 <-----> <---------- tunnel ----------> <----->
1226 +---------+ ___ _ +---------+
1227 End system | +----+ | / \/ \_ | +----+ | End system
1228 "A" -------F1+ | | / \ | | +F2----- "B"
1229 | | +==========+ IP/MPLS +========+ | |
1230 | |SI-1| | \__ Net._/ | |SI-2| |
1231 | +----+ | \____/ | +----+ |
1232 |PE1 | | PE2|
1233 +---------+ +---------+
1235 Figure 8: DetNet network reference model
1237 The tunnel between the service instances may have some special
1238 characteristics. For example, in case of a "packet PW" based tunnel,
1239 there are differences in the usage of the packet PW for DetNet
1240 traffic compared to the network model described in [RFC6658]. In the
1241 DetNet scenario, the packet PW is used exclusively by the DetNet
1242 flow, whereas [RFC6658] states: "The packet PW appears as a single
1243 point-to-point link to the client layer. Network-layer adjacency
1244 formation and maintenance between the client equipments will follow
1245 the normal practice needed to support the required relationship in
1246 the client layer ... This packet pseudowire is used to transport all
1247 of the required layer 2 and layer 3 protocols between LSR1 and LSR2".
1249 4.7. Flow identification at technology borders
1251 4.7.1. Exporting flow identification
1253 An interesting feature of DetNet, and one that invites
1254 implementations that can be accused of "layering violations", is the
1255 need for lower layers to be aware of specific flows at higher layers,
1256 in order to provide specific queuing and shaping services for
1257 specific flows. For example:
1259 o A non-IP, strictly L2 source end system X may be sending multiple
1260 flows to the same L2 destination end system Y. Those flows may
1261 include DetNet flows with different QoS requirements, and may
1262 include non-DetNet flows.
1264 o A router may be sending any number of flows to another router.
1265 Again, those flows may include DetNet flows with different QoS
1266 requirements, and may include non-DetNet flows.
1268 o Two routers may be separated by bridges. For these bridges to
1269 perform any required per-flow queuing and shaping, they must be
1270 able to identify the individual flows.
1272 o A Label Edge Router (LERs) may have a Label Switched Path (LSP)
1273 set up for handling traffic destined for a particular IP address
1274 carrying only non-DetNet flows. If a DetNet flow to that same
1275 address is requested, a separate LSP may be needed, in order that
1276 all of the Label Switch Routers (LSRs) along the path to the
1277 destination give that flow special queuing and shaping.
1279 The need for a lower-level DetNet node to be aware of individual
1280 higher-layer flows is not unique to DetNet. But, given the endless
1281 complexity of layering and relayering over tunnels that is available
1282 to network designers, DetNet needs to provide a model for flow
1283 identification that is at least somewhat better than packet
1284 inspection. That is not to say that packet inspection to layer 4 or
1285 5 addresses will not be used, or the capability standardized; but,
1286 there are alternatives.
1288 A DetNet relay node can connect DetNet flows on different paths using
1289 different flow identification methods. For example:
1291 o A single unicast DetNet flow passing from router A through a
1292 bridged network to router B may be assigned a {VLAN, multicast
1293 destination MAC address} pair that is unique within that bridged
1294 network. The bridges can then identify the flow without accessing
1295 higher-layer headers. Of course, the receiving router must
1296 recognize and accept that multicast MAC address.
1298 o A DetNet flow passing from LSR A to LSR B may be assigned a
1299 different label than that used for other flows to the same IP
1300 destination.
1302 In any of the above cases, it is possible that an existing DetNet
1303 flow can be used as a carrier for multiple DetNet sub-flows. (Not to
1304 be confused with DetNet compound vs. member flows.) Of course, this
1305 requires that the aggregate DetNet flow be provisioned properly to
1306 carry the sub-flows.
1308 Thus, rather than packet inspection, there is the option to export
1309 higher-layer information to the lower layer. The requirement to
1310 support one or the other method for flow identification (or both) is
1311 the essential complexity that DetNet brings to existing control plane
1312 models.
1314 4.7.2. Flow attribute mapping between layers
1316 Transport of DetNet flows over multiple technology domains may
1317 require that lower layers are aware of specific flows of higher
1318 layers. Such an "exporting of flow identification" is needed each
1319 time when the forwarding paradigm is changed on the transport path
1320 (e.g., two LSRs are interconnected by a L2 bridged domain, etc.).
1321 The three main forwarding methods considered for deterministic
1322 networking are:
1324 o IP routing
1326 o MPLS label switching
1328 o Ethernet bridging
1330 add/remove add/remove
1331 Eth Flow-ID IP Flow-ID
1332 | |
1333 v v
1334 +-----------------------------------------------------------+
1335 | | | | |
1336 | Eth | MPLS | IP | Application data |
1337 | | | | |
1338 +-----------------------------------------------------------+
1339 ^
1340 |
1341 add/remove
1342 MPLS Flow-ID
1344 Figure 9: Packet with multiple Flow-IDs
1346 The additional (domain specific) Flow-ID can be
1348 o created by a domain specific function or
1350 o derived from the Flow-ID added to the App-flow,
1352 so that it must be unique inside the given domain. Note that the
1353 Flow-ID added to the App-flow is still present in the packet, but
1354 transport nodes may lack the function to recognize it; that's why the
1355 additional Flow-ID is added (pushed).
1357 4.7.3. Flow-ID mapping examples
1359 IP nodes and MPLS nodes are assumed to be configured to push such an
1360 additional (domain specific) Flow-ID when sending traffic to an
1361 Ethernet switch (as shown in the examples below).
1363 Figure 10 shows a scenario where an IP end system ("IP-A") is
1364 connected via two Ethernet switches ("ETH-n") to an IP router ("IP-
1365 1").
1367 IP domain
1368 <-----------------------------------------------
1370 +======+ +======+
1371 |L3-ID | |L3-ID |
1372 +======+ /\ +-----+ +======+
1373 / \ Forward as | |
1374 /IP-A\ per ETH-ID |IP-1 | Recognize
1375 Push ------> +-+----+ | +---+-+ <----- ETH-ID
1376 ETH-ID | +----+-----+ |
1377 | v v |
1378 | +-----+ +-----+ |
1379 +------+ | | +---------+
1380 +......+ |ETH-1+----+ETH-2| +======+
1381 .L3-ID . +-----+ +-----+ |L3-ID |
1382 +======+ +......+ +======+
1383 |ETH-ID| .L3-ID . |ETH-ID|
1384 +======+ +======+ +------+
1385 |ETH-ID|
1386 +======+
1388 Ethernet domain
1389 <---------------->
1391 Figure 10: IP nodes interconnected by an Ethernet domain
1393 End system "IP-A" uses the original App-flow specific ID ("L3-ID"),
1394 but as it is connected to an Ethernet domain it has to push an
1395 Ethernet-domain specific flow-ID ("VID + multicast MAC address",
1396 referred as "ETH-ID") before sending the packet to "ETH-1" node.
1397 Ethernet switch "ETH-1" can recognize the data flow based on the
1398 "ETH-ID" and it does forwarding toward "ETH-2". "ETH-2" switches the
1399 packet toward the IP router. "IP-1" must be configured to receive
1400 the Ethernet Flow-ID specific multicast stream, but (as it is an L3
1401 node) it decodes the data flow ID based on the "L3-ID" fields of the
1402 received packet.
1404 Figure 11 shows a scenario where MPLS domain nodes ("PE-n" and "P-m")
1405 are connected via two Ethernet switches ("ETH-n").
1407 MPLS domain
1408 <----------------------------------------------->
1410 +=======+ +=======+
1411 |MPLS-ID| |MPLS-ID|
1412 +=======+ +-----+ +-----+ +=======+ +-----+
1413 | | Forward as | | | |
1414 |PE-1 | per ETH-ID | P-2 +-----------+ PE-2|
1415 Push -----> +-+---+ | +---+-+ +-----+
1416 ETH-ID | +-----+----+ | \ Recognize
1417 | v v | +-- ETH-ID
1418 | +-----+ +-----+ |
1419 +---+ | | +----+
1420 +.......+ |ETH-1+----+ETH-2| +=======+
1421 .MPLS-ID. +-----+ +-----+ |MPLS-ID|
1422 +=======+ +=======+
1423 |ETH-ID | +.......+ |ETH-ID |
1424 +=======+ .MPLS-ID. +-------+
1425 +=======+
1426 |ETH-ID |
1427 +=======+
1428 Ethernet domain
1429 <---------------->
1431 Figure 11: MPLS nodes interconnected by an Ethernet domain
1433 "PE-1" uses the MPLS specific ID ("MPLS-ID"), but as it is connected
1434 to an Ethernet domain it has to push an Ethernet-domain specific
1435 flow-ID ("VID + multicast MAC address", referred as "ETH-ID") before
1436 sending the packet to "ETH-1". Ethernet switch "ETH-1" can recognize
1437 the data flow based on the "ETH-ID" and it does forwarding toward
1438 "ETH-2". "ETH-2" switches the packet toward the MPLS node ("P-2").
1439 "P-2" must be configured to receive the Ethernet Flow-ID specific
1440 multicast stream, but (as it is an MPLS node) it decodes the data
1441 flow ID based on the "MPLS-ID" fields of the received packet.
1443 One can appreciate from the above example that, when the means used
1444 for DetNet flow identifcation is altered or exported, the means for
1445 encoding the sequence number information must similarly be altered or
1446 exported.
1448 4.8. Advertising resources, capabilities and adjacencies
1450 There are three classes of information that a central controller or
1451 decentralized control plane needs to know that can only be obtained
1452 from the end systems and/or transit nodes in the network. When using
1453 a peer-to-peer control plane, some of this information may be
1454 required by a system's neighbors in the network.
1456 o Details of the system's capabilities that are required in order to
1457 accurately allocate that system's resources, as well as other
1458 systems' resources. This includes, for example, which specific
1459 queuing and shaping algorithms are implemented (Section 4.5), the
1460 number of buffers dedicated for DetNet allocation, and the worst-
1461 case forwarding delay.
1463 o The dynamic state of an end or transit node's DetNet resources.
1465 o The identity of the system's neighbors, and the characteristics of
1466 the link(s) between the systems, including the length (in
1467 nanoseconds) of the link(s).
1469 4.9. Provisioning model
1471 4.9.1. Centralized Path Computation and Installation
1473 A centralized routing model, such as provided with a PCE (RFC 4655
1474 [RFC4655]), enables global and per-flow optimizations. (See
1475 Section 4.4.) The model is attractive but a number of issues are
1476 left to be solved. In particular:
1478 o Whether and how the path computation can be installed by 1) an end
1479 device or 2) a Network Management entity,
1481 o And how the path is set up, either by installing state at each hop
1482 with a direct interaction between the forwarding device and the
1483 PCE, or along a path by injecting a source-routed request at one
1484 end of the path.
1486 4.9.2. Distributed Path Setup
1488 Significant work on distributed path setup can be leveraged from MPLS
1489 Traffic Engineering, in both its GMPLS and non-GMPLS forms. The
1490 protocols within scope are Resource ReSerVation Protocol [RFC3209]
1491 [RFC3473](RSVP-TE), OSPF-TE [RFC4203] [RFC5392] and ISIS-TE [RFC5307]
1492 [RFC5316]. These should be viewed as starting points as there are
1493 feature specific extensions defined that may be applicable to DetNet.
1495 In a Layer-2 only environment, or as part of a layered approach to a
1496 mixed environment, IEEE 802.1 also has work, either completed or in
1497 progress. [IEEE802.1Q-2014] Clause 35 describes SRP, a peer-to-peer
1498 protocol for Layer-2 roughly analogous to RSVP [RFC2205].
1499 [IEEE802.1Qca] defines how ISIS can provide multiple disjoint paths
1500 or distribution trees. Also in progress is [IEEE802.1Qcc], which
1501 expands the capabilities of SRP.
1503 The integration/interaction of the DetNet control layer with an
1504 underlying IEEE 802.1 sub-network control layer will need to be
1505 defined.
1507 4.10. Scaling to larger networks
1509 Reservations for individual DetNet flows require considerable state
1510 information in each transit node, especially when adequate fault
1511 mitigation (Section 3.3.2) is required. The DetNet data plane, in
1512 order to support larger numbers of DetNet flows, must support the
1513 aggregation of DetNet flows into tunnels, which themselves can be
1514 viewed by the transit nodes' data planes largely as individual DetNet
1515 flows. Without such aggregation, the per-relay system may limit the
1516 scale of DetNet networks.
1518 4.11. Connected islands vs. networks
1520 Given that users have deployed examples of the IEEE 802.1 TSN TG
1521 standards, which provide capabilities similar to DetNet, it is
1522 obvious to ask whether the IETF DetNet effort can be limited to
1523 providing Layer-2 connections (VPNs) between islands of bridged TSN
1524 networks. While this capability is certainly useful to some
1525 applications, and must not be precluded by DetNet, tunneling alone is
1526 not a sufficient goal for the DetNet WG. As shown in the
1527 Deterministic Networking Use Cases draft [I-D.ietf-detnet-use-cases],
1528 there are already deployments of Layer-2 TSN networks that are
1529 encountering the well-known problems of over-large broadcast domains.
1530 Routed solutions, and combinations routed/bridged solutions, are both
1531 required.
1533 4.12. Compatibility with Layer-2
1535 Standards providing similar capabilities for bridged networks (only)
1536 have been and are being generated in the IEEE 802 LAN/MAN Standards
1537 Committee. The present architecture describes an abstract model that
1538 can be applicable both at Layer-2 and Layer-3, and over links not
1539 defined by IEEE 802. It is the intention of the authors (and
1540 hopefully, as this draft progresses, of the DetNet Working Group)
1541 that IETF and IEEE 802 will coordinate their work, via the
1542 participation of common individuals, liaisons, and other means, to
1543 maximize the compatibility of their outputs.
1545 DetNet enabled end systems and intermediate nodes can be
1546 interconnected by sub-networks, i.e., Layer-2 technologies. These
1547 sub-networks will provide DetNet compatible service for support of
1548 DetNet traffic. Examples of sub-networks include 802.1TSN and a
1549 point-to-point OTN link. Of course, multi-layer DetNet systems may
1550 be possible too, where one DetNet appears as a sub-network, and
1551 provides service to, a higher layer DetNet system.
1553 5. Security Considerations
1555 Security in the context of Deterministic Networking has an added
1556 dimension; the time of delivery of a packet can be just as important
1557 as the contents of the packet, itself. A man-in-the-middle attack,
1558 for example, can impose, and then systematically adjust, additional
1559 delays into a link, and thus disrupt or subvert a real-time
1560 application without having to crack any encryption methods employed.
1561 See [RFC7384] for an exploration of this issue in a related context.
1563 Furthermore, in a control system where millions of dollars of
1564 equipment, or even human lives, can be lost if the DetNet QoS is not
1565 delivered, one must consider not only simple equipment failures,
1566 where the box or wire instantly becomes perfectly silent, but bizarre
1567 errors such as can be caused by software failures. Because there is
1568 essential no limit to the kinds of failures that can occur,
1569 protecting against realistic equipment failures is indistinguishable,
1570 in most cases, from protecting against malicious behavior, whether
1571 accidental or intentional. See also Section 3.3.2.
1573 Security must cover:
1575 o the protection of the signaling protocol
1577 o the authentication and authorization of the controlling systems
1579 o the identification and shaping of the DetNet flows
1581 6. Privacy Considerations
1583 DetNet is provides a Quality of Service (QoS), and as such, does not
1584 directly raise any new privacy considerations.
1586 However, the requirement for every (or almost every) node along the
1587 path of a DetNet flow to identify DetNet flows may present an
1588 additional attack surface for privacy, should the DetNet paradigm be
1589 found useful in broader environments.
1591 7. IANA Considerations
1593 This document does not require an action from IANA.
1595 8. Acknowledgements
1597 The authors wish to thank Jouni Korhonen, Erik Nordmark, George
1598 Swallow, Rudy Klecka, Anca Zamfir, David Black, Thomas Watteyne,
1599 Shitanshu Shah, Craig Gunther, Rodney Cummings, Balazs Varga,
1600 Wilfried Steiner, Marcel Kiessling, Karl Weber, Janos Farkas, Ethan
1601 Grossman, Pat Thaler, Lou Berger, and especially Michael Johas
1602 Teener, for their various contribution with this work.
1604 9. Access to IEEE 802.1 documents
1606 To access password protected IEEE 802.1 drafts, see the IETF IEEE
1607 802.1 information page at https://www.ietf.org/proceedings/52/slides/
1608 bridge-0/tsld003.htm.
1610 10. Informative References
1612 [AVnu] http://www.avnu.org/, "The AVnu Alliance tests and
1613 certifies devices for interoperability, providing a simple
1614 and reliable networking solution for AV network
1615 implementation based on the Audio Video Bridging (AVB)
1616 standards.".
1618 [CCAMP] IETF, "Common Control and Measurement Plane",
1619 .
1621 [HSR-PRP] IEC, "High availability seamless redundancy (HSR) is a
1622 further development of the PRP approach, although HSR
1623 functions primarily as a protocol for creating media
1624 redundancy while PRP, as described in the previous
1625 section, creates network redundancy. PRP and HSR are both
1626 described in the IEC 62439 3 standard.",
1627 .
1630 [I-D.dt-detnet-dp-alt]
1631 Korhonen, J., Farkas, J., Mirsky, G., Thubert, P.,
1632 Zhuangyan, Z., and L. Berger, "DetNet Data Plane Protocol
1633 and Solution Alternatives", draft-dt-detnet-dp-alt-04
1634 (work in progress), September 2016.
1636 [I-D.ietf-6tisch-architecture]
1637 Thubert, P., "An Architecture for IPv6 over the TSCH mode
1638 of IEEE 802.15.4", draft-ietf-6tisch-architecture-12 (work
1639 in progress), August 2017.
1641 [I-D.ietf-6tisch-tsch]
1642 Watteyne, T., Palattella, M., and L. Grieco, "Using
1643 IEEE802.15.4e TSCH in an IoT context: Overview, Problem
1644 Statement and Goals", draft-ietf-6tisch-tsch-06 (work in
1645 progress), March 2015.
1647 [I-D.ietf-detnet-problem-statement]
1648 Finn, N. and P. Thubert, "Deterministic Networking Problem
1649 Statement", draft-ietf-detnet-problem-statement-02 (work
1650 in progress), September 2017.
1652 [I-D.ietf-detnet-use-cases]
1653 Grossman, E., Gunther, C., Thubert, P., Wetterwald, P.,
1654 Raymond, J., Korhonen, J., Kaneko, Y., Das, S., Zha, Y.,
1655 Varga, B., Farkas, J., Goetz, F., Schmitt, J., Vilajosana,
1656 X., Mahmoodi, T., Spirou, S., Vizarreta, P., Huang, D.,
1657 Geng, X., Dujovne, D., and M. Seewald, "Deterministic
1658 Networking Use Cases", draft-ietf-detnet-use-cases-13
1659 (work in progress), September 2017.
1661 [I-D.ietf-roll-rpl-industrial-applicability]
1662 Phinney, T., Thubert, P., and R. Assimiti, "RPL
1663 applicability in industrial networks", draft-ietf-roll-
1664 rpl-industrial-applicability-02 (work in progress),
1665 October 2013.
1667 [I-D.svshah-tsvwg-deterministic-forwarding]
1668 Shah, S. and P. Thubert, "Deterministic Forwarding PHB",
1669 draft-svshah-tsvwg-deterministic-forwarding-04 (work in
1670 progress), August 2015.
1672 [I-D.varga-detnet-service-model]
1673 Varga, B. and J. Farkas, "DetNet Service Model", draft-
1674 varga-detnet-service-model-02 (work in progress), May
1675 2017.
1677 [IEEE802.1AS-2011]
1678 IEEE, "IEEE Std 802.1AS Timing and Synchronization for
1679 Time-Sensitive Applications in Bridged Local Area
1680 Networks", 2011,
1681 .
1683 [IEEE802.1BA-2011]
1684 IEEE, "IEEE Std 802.1BA Audio Video Bridging (AVB)
1685 Systems", 2011,
1686 .
1688 [IEEE802.1CB]
1689 IEEE, "Frame Replication and Elimination for Reliability
1690 (IEEE Draft P802.1CB)", 2017,
1691 .
1693 [IEEE802.1Q-2014]
1694 IEEE, "IEEE Std 802.1Q Bridges and Bridged Networks",
1695 2014, .
1697 [IEEE802.1Qbu]
1698 IEEE, "IEEEE Std 802.1Qbu Bridges and Bridged Networks -
1699 Amendment 26: Frame Preemption", 2016,
1700 .
1702 [IEEE802.1Qbv]
1703 IEEE, "IEEEE Std 802.1Qbu Bridges and Bridged Networks -
1704 Amendment 25: Enhancements for Scheduled Traffic", 2015,
1705 .
1707 [IEEE802.1Qca]
1708 IEEE, "IEEE Std 802.1Qca Bridges and Bridged Networks -
1709 Amendment 24: Path Control and Reservation", June 2015,
1710 .
1712 [IEEE802.1Qcc]
1713 IEEE, "Stream Reservation Protocol (SRP) Enhancements and
1714 Performance Improvements (IEEE Draft P802.1Qcc)", 2017,
1715 .
1717 [IEEE802.1Qch]
1718 IEEE, "Cyclic Queuing and Forwarding (IEEE Draft
1719 P802.1Qch)", 2017,
1720 .
1722 [IEEE802.1TSNTG]
1723 IEEE Standards Association, "IEEE 802.1 Time-Sensitive
1724 Networks Task Group", 2013,
1725 .
1727 [IEEE802.3-2015]
1728 IEEE, "IEEE Std 802.3 Standard for Ethernet", 2015,
1729 .
1731 [IEEE802.3br]
1732 IEEE, "IEEE Std 802.3br Standard for Ethernet Amendment 5:
1733 Specification and Management Parameters for Interspersing
1734 Express Traffic", 2016,
1735 .
1737 [ISA95] ANSI/ISA, "Enterprise-Control System Integration Part 1:
1738 Models and Terminology", 2000,
1739 .
1741 [ODVA] http://www.odva.org/, "The organization that supports
1742 network technologies built on the Common Industrial
1743 Protocol (CIP) including EtherNet/IP.".
1745 [PCE] IETF, "Path Computation Element",
1746 .
1748 [Profinet]
1749 http://us.profinet.com/technology/profinet/, "PROFINET is
1750 a standard for industrial networking in automation.",
1751 .
1753 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
1754 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
1755 Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
1756 September 1997, .
1758 [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
1759 and W. Weiss, "An Architecture for Differentiated
1760 Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
1761 .
1763 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
1764 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
1765 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
1766 .
1768 [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
1769 Switching (GMPLS) Signaling Resource ReserVation Protocol-
1770 Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
1771 DOI 10.17487/RFC3473, January 2003,
1772 .
1774 [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
1775 Jacobson, "RTP: A Transport Protocol for Real-Time
1776 Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
1777 July 2003, .
1779 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
1780 Support of Generalized Multi-Protocol Label Switching
1781 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
1782 .
1784 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
1785 Element (PCE)-Based Architecture", RFC 4655,
1786 DOI 10.17487/RFC4655, August 2006,
1787 .
1789 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions
1790 in Support of Generalized Multi-Protocol Label Switching
1791 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
1792 .
1794 [RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
1795 Support of Inter-Autonomous System (AS) MPLS and GMPLS
1796 Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
1797 December 2008, .
1799 [RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
1800 Support of Inter-Autonomous System (AS) MPLS and GMPLS
1801 Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392,
1802 January 2009, .
1804 [RFC5673] Pister, K., Ed., Thubert, P., Ed., Dwars, S., and T.
1805 Phinney, "Industrial Routing Requirements in Low-Power and
1806 Lossy Networks", RFC 5673, DOI 10.17487/RFC5673, October
1807 2009, .
1809 [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau,
1810 L., and L. Berger, "A Framework for MPLS in Transport
1811 Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010,
1812 .
1814 [RFC6372] Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport
1815 Profile (MPLS-TP) Survivability Framework", RFC 6372,
1816 DOI 10.17487/RFC6372, September 2011,
1817 .
1819 [RFC6658] Bryant, S., Ed., Martini, L., Swallow, G., and A. Malis,
1820 "Packet Pseudowire Encapsulation over an MPLS PSN",
1821 RFC 6658, DOI 10.17487/RFC6658, July 2012,
1822 .
1824 [RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
1825 Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
1826 October 2014, .
1828 [RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
1829 Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
1830 Defined Networking (SDN): Layers and Architecture
1831 Terminology", RFC 7426, DOI 10.17487/RFC7426, January
1832 2015, .
1834 [TEAS] IETF, "Traffic Engineering Architecture and Signaling",
1835 .
1837 Authors' Addresses
1839 Norman Finn
1840 Huawei Technologies Co. Ltd
1841 3755 Avocado Blvd.
1842 PMB 436
1843 La Mesa, California 91941
1844 US
1846 Phone: +1 925 980 6430
1847 Email: norman.finn@mail01.huawei.com
1849 Pascal Thubert
1850 Cisco Systems
1851 Village d'Entreprises Green Side
1852 400, Avenue de Roumanille
1853 Batiment T3
1854 Biot - Sophia Antipolis 06410
1855 FRANCE
1857 Phone: +33 4 97 23 26 34
1858 Email: pthubert@cisco.com
1860 Balazs Varga
1861 Ericsson
1862 Konyves Kalman krt. 11/B
1863 Budapest 1097
1864 Hungary
1866 Email: balazs.a.varga@ericsson.com
1867 Janos Farkas
1868 Ericsson
1869 Konyves Kalman krt. 11/B
1870 Budapest 1097
1871 Hungary
1873 Email: janos.farkas@ericsson.com