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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force E. Grossman, Ed. 3 Internet-Draft DOLBY 4 Intended status: Informational C. Gunther 5 Expires: September 22, 2016 HARMAN 6 P. Thubert 7 P. Wetterwald 8 CISCO 9 J. Raymond 10 HYDRO-QUEBEC 11 J. Korhonen 12 BROADCOM 13 Y. Kaneko 14 Toshiba 15 S. Das 16 Applied Communication Sciences 17 Y. Zha 18 HUAWEI 19 B. Varga 20 J. Farkas 21 Ericsson 22 F. Goetz 23 J. Schmitt 24 Siemens 25 March 21, 2016 27 Deterministic Networking Use Cases 28 draft-ietf-detnet-use-cases-09 30 Abstract 32 This draft documents requirements in several diverse industries to 33 establish multi-hop paths for characterized flows with deterministic 34 properties. In this context deterministic implies that streams can 35 be established which provide guaranteed bandwidth and latency which 36 can be established from either a Layer 2 or Layer 3 (IP) interface, 37 and which can co-exist on an IP network with best-effort traffic. 39 Additional requirements include optional redundant paths, very high 40 reliability paths, time synchronization, and clock distribution. 41 Industries considered include wireless for industrial applications, 42 professional audio, electrical utilities, building automation 43 systems, radio/mobile access networks, automotive, and gaming. 45 For each case, this document will identify the application, identify 46 representative solutions used today, and what new uses an IETF DetNet 47 solution may enable. 49 Status of This Memo 51 This Internet-Draft is submitted in full conformance with the 52 provisions of BCP 78 and BCP 79. 54 Internet-Drafts are working documents of the Internet Engineering 55 Task Force (IETF). Note that other groups may also distribute 56 working documents as Internet-Drafts. The list of current Internet- 57 Drafts is at http://datatracker.ietf.org/drafts/current/. 59 Internet-Drafts are draft documents valid for a maximum of six months 60 and may be updated, replaced, or obsoleted by other documents at any 61 time. It is inappropriate to use Internet-Drafts as reference 62 material or to cite them other than as "work in progress." 64 This Internet-Draft will expire on September 22, 2016. 66 Copyright Notice 68 Copyright (c) 2016 IETF Trust and the persons identified as the 69 document authors. All rights reserved. 71 This document is subject to BCP 78 and the IETF Trust's Legal 72 Provisions Relating to IETF Documents 73 (http://trustee.ietf.org/license-info) in effect on the date of 74 publication of this document. Please review these documents 75 carefully, as they describe your rights and restrictions with respect 76 to this document. Code Components extracted from this document must 77 include Simplified BSD License text as described in Section 4.e of 78 the Trust Legal Provisions and are provided without warranty as 79 described in the Simplified BSD License. 81 Table of Contents 83 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 84 2. Pro Audio and Video . . . . . . . . . . . . . . . . . . . . . 5 85 2.1. Use Case Description . . . . . . . . . . . . . . . . . . 5 86 2.1.1. Uninterrupted Stream Playback . . . . . . . . . . . . 6 87 2.1.2. Synchronized Stream Playback . . . . . . . . . . . . 6 88 2.1.3. Sound Reinforcement . . . . . . . . . . . . . . . . . 7 89 2.1.4. Deterministic Time to Establish Streaming . . . . . . 7 90 2.1.5. Secure Transmission . . . . . . . . . . . . . . . . . 8 91 2.1.5.1. Safety . . . . . . . . . . . . . . . . . . . . . 8 92 2.1.5.2. Digital Rights Management (DRM) . . . . . . . . . 8 93 2.2. Pro Audio Today . . . . . . . . . . . . . . . . . . . . . 9 94 2.3. Pro Audio Future . . . . . . . . . . . . . . . . . . . . 9 95 2.3.1. Layer 3 Interconnecting Layer 2 Islands . . . . . . . 9 96 2.3.2. High Reliability Stream Paths . . . . . . . . . . . . 9 97 2.3.3. Link Aggregation . . . . . . . . . . . . . . . . . . 9 98 2.3.4. Integration of Reserved Streams into IT Networks . . 10 99 2.3.5. Use of Unused Reservations by Best-Effort Traffic . . 10 100 2.3.6. Traffic Segregation . . . . . . . . . . . . . . . . . 10 101 2.3.6.1. Packet Forwarding Rules, VLANs and Subnets . . . 11 102 2.3.6.2. Multicast Addressing (IPv4 and IPv6) . . . . . . 11 103 2.3.7. Latency Optimization by a Central Controller . . . . 11 104 2.3.8. Reduced Device Cost Due To Reduced Buffer Memory . . 12 105 2.4. Pro Audio Asks . . . . . . . . . . . . . . . . . . . . . 12 106 3. Electrical Utilities . . . . . . . . . . . . . . . . . . . . 12 107 3.1. Use Case Description . . . . . . . . . . . . . . . . . . 12 108 3.1.1. Transmission Use Cases . . . . . . . . . . . . . . . 13 109 3.1.1.1. Protection . . . . . . . . . . . . . . . . . . . 13 110 3.1.1.2. Intra-Substation Process Bus Communications . . . 18 111 3.1.1.3. Wide Area Monitoring and Control Systems . . . . 19 112 3.1.1.4. IEC 61850 WAN engineering guidelines requirement 113 classification . . . . . . . . . . . . . . . . . 20 114 3.1.2. Generation Use Case . . . . . . . . . . . . . . . . . 21 115 3.1.3. Distribution use case . . . . . . . . . . . . . . . . 22 116 3.1.3.1. Fault Location Isolation and Service Restoration 117 (FLISR) . . . . . . . . . . . . . . . . . . . . . 22 118 3.2. Electrical Utilities Today . . . . . . . . . . . . . . . 23 119 3.2.1. Security Current Practices and Limitations . . . . . 23 120 3.3. Electrical Utilities Future . . . . . . . . . . . . . . . 25 121 3.3.1. Migration to Packet-Switched Network . . . . . . . . 25 122 3.3.2. Telecommunications Trends . . . . . . . . . . . . . . 26 123 3.3.2.1. General Telecommunications Requirements . . . . . 26 124 3.3.2.2. Specific Network topologies of Smart Grid 125 Applications . . . . . . . . . . . . . . . . . . 27 126 3.3.2.3. Precision Time Protocol . . . . . . . . . . . . . 28 127 3.3.3. Security Trends in Utility Networks . . . . . . . . . 29 128 3.4. Electrical Utilities Asks . . . . . . . . . . . . . . . . 31 129 4. Building Automation Systems . . . . . . . . . . . . . . . . . 31 130 4.1. Use Case Description . . . . . . . . . . . . . . . . . . 31 131 4.2. Building Automation Systems Today . . . . . . . . . . . . 31 132 4.2.1. BAS Architecture . . . . . . . . . . . . . . . . . . 32 133 4.2.2. BAS Deployment Model . . . . . . . . . . . . . . . . 33 134 4.2.3. Use Cases for Field Networks . . . . . . . . . . . . 35 135 4.2.3.1. Environmental Monitoring . . . . . . . . . . . . 35 136 4.2.3.2. Fire Detection . . . . . . . . . . . . . . . . . 35 137 4.2.3.3. Feedback Control . . . . . . . . . . . . . . . . 36 138 4.2.4. Security Considerations . . . . . . . . . . . . . . . 36 139 4.3. BAS Future . . . . . . . . . . . . . . . . . . . . . . . 36 140 4.4. BAS Asks . . . . . . . . . . . . . . . . . . . . . . . . 37 141 5. Wireless for Industrial . . . . . . . . . . . . . . . . . . . 37 142 5.1. Use Case Description . . . . . . . . . . . . . . . . . . 37 143 5.1.1. Network Convergence using 6TiSCH . . . . . . . . . . 38 144 5.1.2. Common Protocol Development for 6TiSCH . . . . . . . 38 146 5.2. Wireless Industrial Today . . . . . . . . . . . . . . . . 39 147 5.3. Wireless Industrial Future . . . . . . . . . . . . . . . 39 148 5.3.1. Unified Wireless Network and Management . . . . . . . 39 149 5.3.1.1. PCE and 6TiSCH ARQ Retries . . . . . . . . . . . 41 150 5.3.2. Schedule Management by a PCE . . . . . . . . . . . . 42 151 5.3.2.1. PCE Commands and 6TiSCH CoAP Requests . . . . . . 42 152 5.3.2.2. 6TiSCH IP Interface . . . . . . . . . . . . . . . 43 153 5.3.3. 6TiSCH Security Considerations . . . . . . . . . . . 43 154 5.4. Wireless Industrial Asks . . . . . . . . . . . . . . . . 44 155 6. Cellular Radio . . . . . . . . . . . . . . . . . . . . . . . 44 156 6.1. Use Case Description . . . . . . . . . . . . . . . . . . 44 157 6.1.1. Network Architecture . . . . . . . . . . . . . . . . 44 158 6.1.2. Delay Constraints . . . . . . . . . . . . . . . . . . 45 159 6.1.3. Time Synchronization Constraints . . . . . . . . . . 46 160 6.1.4. Transport Loss Constraints . . . . . . . . . . . . . 48 161 6.1.5. Security Considerations . . . . . . . . . . . . . . . 48 162 6.2. Cellular Radio Networks Today . . . . . . . . . . . . . . 48 163 6.2.1. Fronthaul . . . . . . . . . . . . . . . . . . . . . . 48 164 6.2.2. Midhaul and Backhaul . . . . . . . . . . . . . . . . 49 165 6.3. Cellular Radio Networks Future . . . . . . . . . . . . . 49 166 6.4. Cellular Radio Networks Asks . . . . . . . . . . . . . . 51 167 7. Industrial M2M . . . . . . . . . . . . . . . . . . . . . . . 52 168 7.1. Use Case Description . . . . . . . . . . . . . . . . . . 52 169 7.2. Industrial M2M Communication Today . . . . . . . . . . . 53 170 7.2.1. Transport Parameters . . . . . . . . . . . . . . . . 53 171 7.2.2. Stream Creation and Destruction . . . . . . . . . . . 54 172 7.3. Industrial M2M Future . . . . . . . . . . . . . . . . . . 54 173 7.4. Industrial M2M Asks . . . . . . . . . . . . . . . . . . . 54 174 8. Internet-based Applications . . . . . . . . . . . . . . . . . 55 175 8.1. Use Case Description . . . . . . . . . . . . . . . . . . 55 176 8.1.1. Media Content Delivery . . . . . . . . . . . . . . . 55 177 8.1.2. Online Gaming . . . . . . . . . . . . . . . . . . . . 55 178 8.1.3. Virtual Reality . . . . . . . . . . . . . . . . . . . 55 179 8.2. Internet-Based Applications Today . . . . . . . . . . . . 55 180 8.3. Internet-Based Applications Future . . . . . . . . . . . 55 181 8.4. Internet-Based Applications Asks . . . . . . . . . . . . 56 182 9. Use Case Common Elements . . . . . . . . . . . . . . . . . . 56 183 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 57 184 10.1. Pro Audio . . . . . . . . . . . . . . . . . . . . . . . 57 185 10.2. Utility Telecom . . . . . . . . . . . . . . . . . . . . 57 186 10.3. Building Automation Systems . . . . . . . . . . . . . . 58 187 10.4. Wireless for Industrial . . . . . . . . . . . . . . . . 58 188 10.5. Cellular Radio . . . . . . . . . . . . . . . . . . . . . 58 189 10.6. Industrial M2M . . . . . . . . . . . . . . . . . . . . . 58 190 10.7. Internet Applications and CoMP . . . . . . . . . . . . . 58 191 11. Informative References . . . . . . . . . . . . . . . . . . . 58 192 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 68 194 1. Introduction 196 This draft presents use cases from diverse industries which have in 197 common a need for deterministic streams, but which also differ 198 notably in their network topologies and specific desired behavior. 199 Together, they provide broad industry context for DetNet and a 200 yardstick against which proposed DetNet designs can be measured (to 201 what extent does a proposed design satisfy these various use cases?) 203 For DetNet, use cases explicitly do not define requirements; The 204 DetNet WG will consider the use cases, decide which elements are in 205 scope for DetNet, and the results will be incorporated into future 206 drafts. Similarly, the DetNet use case draft explicitly does not 207 suggest any specific design, architecture or protocols, which will be 208 topics of future drafts. 210 We present for each use case the answers to the following questions: 212 o What is the use case? 214 o How is it addressed today? 216 o How would you like it to be addressed in the future? 218 o What do you want the IETF to deliver? 220 The level of detail in each use case should be sufficient to express 221 the relevant elements of the use case, but not more. 223 At the end we consider the use cases collectively, and examine the 224 most significant goals they have in common. 226 2. Pro Audio and Video 228 2.1. Use Case Description 230 The professional audio and video industry ("ProAV") includes: 232 o Music and film content creation 234 o Broadcast 236 o Cinema 238 o Live sound 240 o Public address, media and emergency systems at large venues 241 (airports, stadiums, churches, theme parks). 243 These industries have already transitioned audio and video signals 244 from analog to digital. However, the digital interconnect systems 245 remain primarily point-to-point with a single (or small number of) 246 signals per link, interconnected with purpose-built hardware. 248 These industries are now transitioning to packet-based infrastructure 249 to reduce cost, increase routing flexibility, and integrate with 250 existing IT infrastructure. 252 Today ProAV applications have no way to establish deterministic 253 streams from a standards-based Layer 3 (IP) interface, which is a 254 fundamental limitation to the use cases described here. Today 255 deterministic streams can be created within standards-based layer 2 256 LANs (e.g. using IEEE 802.1 AVB) however these are not routable via 257 IP and thus are not effective for distribution over wider areas (for 258 example broadcast events that span wide geographical areas). 260 It would be highly desirable if such streams could be routed over the 261 open Internet, however solutions with more limited scope (e.g. 262 enterprise networks) would still provide a substantial improvement. 264 The following sections describe specific ProAV use cases. 266 2.1.1. Uninterrupted Stream Playback 268 Transmitting audio and video streams for live playback is unlike 269 common file transfer because uninterrupted stream playback in the 270 presence of network errors cannot be achieved by re-trying the 271 transmission; by the time the missing or corrupt packet has been 272 identified it is too late to execute a re-try operation. Buffering 273 can be used to provide enough delay to allow time for one or more 274 retries, however this is not an effective solution in applications 275 where large delays (latencies) are not acceptable (as discussed 276 below). 278 Streams with guaranteed bandwidth can eliminate congestion on the 279 network as a cause of transmission errors that would lead to playback 280 interruption. Use of redundant paths can further mitigate 281 transmission errors to provide greater stream reliability. 283 2.1.2. Synchronized Stream Playback 285 Latency in this context is the time between when a signal is 286 initially sent over a stream and when it is received. A common 287 example in ProAV is time-synchronizing audio and video when they take 288 separate paths through the playback system. In this case the latency 289 of both the audio and video streams must be bounded and consistent if 290 the sound is to remain matched to the movement in the video. A 291 common tolerance for audio/video sync is one NTSC video frame (about 292 33ms) and to maintain the audience perception of correct lip sync the 293 latency needs to be consistent within some reasonable tolerance, for 294 example 10%. 296 A common architecture for synchronizing multiple streams that have 297 different paths through the network (and thus potentially different 298 latencies) is to enable measurement of the latency of each path, and 299 have the data sinks (for example speakers) delay (buffer) all packets 300 on all but the slowest path. Each packet of each stream is assigned 301 a presentation time which is based on the longest required delay. 302 This implies that all sinks must maintain a common time reference of 303 sufficient accuracy, which can be achieved by any of various 304 techniques. 306 This type of architecture is commonly implemented using a central 307 controller that determines path delays and arbitrates buffering 308 delays. 310 2.1.3. Sound Reinforcement 312 Consider the latency (delay) from when a person speaks into a 313 microphone to when their voice emerges from the speaker. If this 314 delay is longer than about 10-15 milliseconds it is noticeable and 315 can make a sound reinforcement system unusable (see slide 6 of 316 [SRP_LATENCY]). (If you have ever tried to speak in the presence of 317 a delayed echo of your voice you may know this experience). 319 Note that the 15ms latency bound includes all parts of the signal 320 path, not just the network, so the network latency must be 321 significantly less than 15ms. 323 In some cases local performers must perform in synchrony with a 324 remote broadcast. In such cases the latencies of the broadcast 325 stream and the local performer must be adjusted to match each other, 326 with a worst case of one video frame (33ms for NTSC video). 328 In cases where audio phase is a consideration, for example beam- 329 forming using multiple speakers, latency requirements can be in the 330 10 microsecond range (1 audio sample at 96kHz). 332 2.1.4. Deterministic Time to Establish Streaming 334 Some audio systems installed in public environments (airports, 335 hospitals) have unique requirements with regards to health, safety 336 and fire concerns. One such requirement is a maximum of 3 seconds 337 for a system to respond to an emergency detection and begin sending 338 appropriate warning signals and alarms without human intervention. 340 For this requirement to be met, the system must support a bounded and 341 acceptable time from a notification signal to specific stream 342 establishment. For further details see [ISO7240-16]. 344 Similar requirements apply when the system is restarted after a power 345 cycle, cable re-connection, or system reconfiguration. 347 In many cases such re-establishment of streaming state must be 348 achieved by the peer devices themselves, i.e. without a central 349 controller (since such a controller may only be present during 350 initial network configuration). 352 Video systems introduce related requirements, for example when 353 transitioning from one camera feed (video stream) to another (see 354 [STUDIO_IP] and [ESPN_DC2]). 356 2.1.5. Secure Transmission 358 2.1.5.1. Safety 360 Professional audio systems can include amplifiers that are capable of 361 generating hundreds or thousands of watts of audio power which if 362 used incorrectly can cause hearing damage to those in the vicinity. 363 Apart from the usual care required by the systems operators to 364 prevent such incidents, the network traffic that controls these 365 devices must be secured (as with any sensitive application traffic). 367 2.1.5.2. Digital Rights Management (DRM) 369 Digital Rights Management (DRM) is very important to the audio and 370 video industries. Any time protected content is introduced into a 371 network there are DRM concerns that must be maintained (see 372 [CONTENT_PROTECTION]). Many aspects of DRM are outside the scope of 373 network technology, however there are cases when a secure link 374 supporting authentication and encryption is required by content 375 owners to carry their audio or video content when it is outside their 376 own secure environment (for example see [DCI]). 378 As an example, two techniques are Digital Transmission Content 379 Protection (DTCP) and High-Bandwidth Digital Content Protection 380 (HDCP). HDCP content is not approved for retransmission within any 381 other type of DRM, while DTCP may be retransmitted under HDCP. 382 Therefore if the source of a stream is outside of the network and it 383 uses HDCP protection it is only allowed to be placed on the network 384 with that same HDCP protection. 386 2.2. Pro Audio Today 388 Some proprietary systems have been created which enable deterministic 389 streams at Layer 3 however they are "engineered networks" which 390 require careful configuration to operate, often require that the 391 system be over-provisioned, and it is implied that all devices on the 392 network voluntarily play by the rules of that network. To enable 393 these industries to successfully transition to an interoperable 394 multi-vendor packet-based infrastructure requires effective open 395 standards, and we believe that establishing relevant IETF standards 396 is a crucial factor. 398 2.3. Pro Audio Future 400 2.3.1. Layer 3 Interconnecting Layer 2 Islands 402 It would be valuable to enable IP to connect multiple Layer 2 LANs. 404 As an example, ESPN recently constructed a state-of-the-art 194,000 405 sq ft, $125 million broadcast studio called DC2. The DC2 network is 406 capable of handling 46 Tbps of throughput with 60,000 simultaneous 407 signals. Inside the facility are 1,100 miles of fiber feeding four 408 audio control rooms (see [ESPN_DC2] ). 410 In designing DC2 they replaced as much point-to-point technology as 411 they could with packet-based technology. They constructed seven 412 individual studios using layer 2 LANS (using IEEE 802.1 AVB) that 413 were entirely effective at routing audio within the LANs. However to 414 interconnect these layer 2 LAN islands together they ended up using 415 dedicated paths in a custom SDN (Software Defined Networking) router 416 because there is no standards-based routing solution available. 418 2.3.2. High Reliability Stream Paths 420 On-air and other live media streams are often backed up with 421 redundant links that seamlessly act to deliver the content when the 422 primary link fails for any reason. In point-to-point systems this is 423 provided by an additional point-to-point link; the analogous 424 requirement in a packet-based system is to provide an alternate path 425 through the network such that no individual link can bring down the 426 system. 428 2.3.3. Link Aggregation 430 For transmitting streams that require more bandwidth than a single 431 link in the target network can support, link aggregation is a 432 technique for combining (aggregating) the bandwidth available on 433 multiple physical links to create a single logical link of the 434 required bandwidth. However, if aggregation is to be used, the 435 network controller (or equivalent) must be able to determine the 436 maximum latency of any path through the aggregate link. 438 2.3.4. Integration of Reserved Streams into IT Networks 440 A commonly cited goal of moving to a packet based media 441 infrastructure is that costs can be reduced by using off the shelf, 442 commodity network hardware. In addition, economy of scale can be 443 realized by combining media infrastructure with IT infrastructure. 444 In keeping with these goals, stream reservation technology should be 445 compatible with existing protocols, and not compromise use of the 446 network for best effort (non-time-sensitive) traffic. 448 2.3.5. Use of Unused Reservations by Best-Effort Traffic 450 In cases where stream bandwidth is reserved but not currently used 451 (or is under-utilized) that bandwidth must be available to best- 452 effort (i.e. non-time-sensitive) traffic. For example a single 453 stream may be nailed up (reserved) for specific media content that 454 needs to be presented at different times of the day, ensuring timely 455 delivery of that content, yet in between those times the full 456 bandwidth of the network can be utilized for best-effort tasks such 457 as file transfers. 459 This also addresses a concern of IT network administrators that are 460 considering adding reserved bandwidth traffic to their networks that 461 ("users will reserve large quantities of bandwidth and then never un- 462 reserve it even though they are not using it, and soon the network 463 will have no bandwidth left"). 465 2.3.6. Traffic Segregation 467 Sink devices may be low cost devices with limited processing power. 468 In order to not overwhelm the CPUs in these devices it is important 469 to limit the amount of traffic that these devices must process. 471 As an example, consider the use of individual seat speakers in a 472 cinema. These speakers are typically required to be cost reduced 473 since the quantities in a single theater can reach hundreds of seats. 474 Discovery protocols alone in a one thousand seat theater can generate 475 enough broadcast traffic to overwhelm a low powered CPU. Thus an 476 installation like this will benefit greatly from some type of traffic 477 segregation that can define groups of seats to reduce traffic within 478 each group. All seats in the theater must still be able to 479 communicate with a central controller. 481 There are many techniques that can be used to support this 482 requirement including (but not limited to) the following examples. 484 2.3.6.1. Packet Forwarding Rules, VLANs and Subnets 486 Packet forwarding rules can be used to eliminate some extraneous 487 streaming traffic from reaching potentially low powered sink devices, 488 however there may be other types of broadcast traffic that should be 489 eliminated using other means for example VLANs or IP subnets. 491 2.3.6.2. Multicast Addressing (IPv4 and IPv6) 493 Multicast addressing is commonly used to keep bandwidth utilization 494 of shared links to a minimum. 496 Because of the MAC Address forwarding nature of Layer 2 bridges it is 497 important that a multicast MAC address is only associated with one 498 stream. This will prevent reservations from forwarding packets from 499 one stream down a path that has no interested sinks simply because 500 there is another stream on that same path that shares the same 501 multicast MAC address. 503 Since each multicast MAC Address can represent 32 different IPv4 504 multicast addresses there must be a process put in place to make sure 505 this does not occur. Requiring use of IPv6 address can achieve this, 506 however due to their continued prevalence, solutions that are 507 effective for IPv4 installations are also required. 509 2.3.7. Latency Optimization by a Central Controller 511 A central network controller might also perform optimizations based 512 on the individual path delays, for example sinks that are closer to 513 the source can inform the controller that they can accept greater 514 latency since they will be buffering packets to match presentation 515 times of farther away sinks. The controller might then move a stream 516 reservation on a short path to a longer path in order to free up 517 bandwidth for other critical streams on that short path. See slides 518 3-5 of [SRP_LATENCY]. 520 Additional optimization can be achieved in cases where sinks have 521 differing latency requirements, for example in a live outdoor concert 522 the speaker sinks have stricter latency requirements than the 523 recording hardware sinks. See slide 7 of [SRP_LATENCY]. 525 2.3.8. Reduced Device Cost Due To Reduced Buffer Memory 527 Device cost can be reduced in a system with guaranteed reservations 528 with a small bounded latency due to the reduced requirements for 529 buffering (i.e. memory) on sink devices. For example, a theme park 530 might broadcast a live event across the globe via a layer 3 protocol; 531 in such cases the size of the buffers required is proportional to the 532 latency bounds and jitter caused by delivery, which depends on the 533 worst case segment of the end-to-end network path. For example on 534 todays open internet the latency is typically unacceptable for audio 535 and video streaming without many seconds of buffering. In such 536 scenarios a single gateway device at the local network that receives 537 the feed from the remote site would provide the expensive buffering 538 required to mask the latency and jitter issues associated with long 539 distance delivery. Sink devices in the local location would have no 540 additional buffering requirements, and thus no additional costs, 541 beyond those required for delivery of local content. The sink device 542 would be receiving the identical packets as those sent by the source 543 and would be unaware that there were any latency or jitter issues 544 along the path. 546 2.4. Pro Audio Asks 548 o Layer 3 routing on top of AVB (and/or other high QoS networks) 550 o Content delivery with bounded, lowest possible latency 552 o IntServ and DiffServ integration with AVB (where practical) 554 o Single network for A/V and IT traffic 556 o Standards-based, interoperable, multi-vendor 558 o IT department friendly 560 o Enterprise-wide networks (e.g. size of San Francisco but not the 561 whole Internet (yet...)) 563 3. Electrical Utilities 565 3.1. Use Case Description 567 Many systems that an electrical utility deploys today rely on high 568 availability and deterministic behavior of the underlying networks. 569 Here we present use cases in Transmission, Generation and 570 Distribution, including key timing and reliability metrics. We also 571 discuss security issues and industry trends which affect the 572 architecture of next generation utility networks 574 3.1.1. Transmission Use Cases 576 3.1.1.1. Protection 578 Protection means not only the protection of human operators but also 579 the protection of the electrical equipment and the preservation of 580 the stability and frequency of the grid. If a fault occurs in the 581 transmission or distribution of electricity then severe damage can 582 occur to human operators, electrical equipment and the grid itself, 583 leading to blackouts. 585 Communication links in conjunction with protection relays are used to 586 selectively isolate faults on high voltage lines, transformers, 587 reactors and other important electrical equipment. The role of the 588 teleprotection system is to selectively disconnect a faulty part by 589 transferring command signals within the shortest possible time. 591 3.1.1.1.1. Key Criteria 593 The key criteria for measuring teleprotection performance are command 594 transmission time, dependability and security. These criteria are 595 defined by the IEC standard 60834 as follows: 597 o Transmission time (Speed): The time between the moment where state 598 changes at the transmitter input and the moment of the 599 corresponding change at the receiver output, including propagation 600 delay. Overall operating time for a teleprotection system 601 includes the time for initiating the command at the transmitting 602 end, the propagation delay over the network (including equipments) 603 and the selection and decision time at the receiving end, 604 including any additional delay due to a noisy environment. 606 o Dependability: The ability to issue and receive valid commands in 607 the presence of interference and/or noise, by minimizing the 608 probability of missing command (PMC). Dependability targets are 609 typically set for a specific bit error rate (BER) level. 611 o Security: The ability to prevent false tripping due to a noisy 612 environment, by minimizing the probability of unwanted commands 613 (PUC). Security targets are also set for a specific bit error 614 rate (BER) level. 616 Additional elements of the the teleprotection system that impact its 617 performance include: 619 o Network bandwidth 621 o Failure recovery capacity (aka resiliency) 623 3.1.1.1.2. Fault Detection and Clearance Timing 625 Most power line equipment can tolerate short circuits or faults for 626 up to approximately five power cycles before sustaining irreversible 627 damage or affecting other segments in the network. This translates 628 to total fault clearance time of 100ms. As a safety precaution, 629 however, actual operation time of protection systems is limited to 630 70- 80 percent of this period, including fault recognition time, 631 command transmission time and line breaker switching time. 633 Some system components, such as large electromechanical switches, 634 require particularly long time to operate and take up the majority of 635 the total clearance time, leaving only a 10ms window for the 636 telecommunications part of the protection scheme, independent of the 637 distance to travel. Given the sensitivity of the issue, new networks 638 impose requirements that are even more stringent: IEC standard 61850 639 limits the transfer time for protection messages to 1/4 - 1/2 cycle 640 or 4 - 8ms (for 60Hz lines) for the most critical messages. 642 3.1.1.1.3. Symmetric Channel Delay 644 Teleprotection channels which are differential must be synchronous, 645 which means that any delays on the transmit and receive paths must 646 match each other. Teleprotection systems ideally support zero 647 asymmetric delay; typical legacy relays can tolerate delay 648 discrepancies of up to 750us. 650 Some tools available for lowering delay variation below this 651 threshold are: 653 o For legacy systems using Time Division Multiplexing (TDM), jitter 654 buffers at the multiplexers on each end of the line can be used to 655 offset delay variation by queuing sent and received packets. The 656 length of the queues must balance the need to regulate the rate of 657 transmission with the need to limit overall delay, as larger 658 buffers result in increased latency. 660 o For jitter-prone IP packet networks, traffic management tools can 661 ensure that the teleprotection signals receive the highest 662 transmission priority to minimize jitter. 664 o Standard packet-based synchronization technologies, such as 665 1588-2008 Precision Time Protocol (PTP) and Synchronous Ethernet 666 (Sync-E), can help keep networks stable by maintaining a highly 667 accurate clock source on the various network devices. 669 3.1.1.1.4. Teleprotection Network Requirements (IEC 61850) 671 The following table captures the main network metrics as based on the 672 IEC 61850 standard. 674 +-----------------------------+-------------------------------------+ 675 | Teleprotection Requirement | Attribute | 676 +-----------------------------+-------------------------------------+ 677 | One way maximum delay | 4-10 ms | 678 | Asymetric delay required | Yes | 679 | Maximum jitter | less than 250 us (750 us for legacy | 680 | | IED) | 681 | Topology | Point to point, point to Multi- | 682 | | point | 683 | Availability | 99.9999 | 684 | precise timing required | Yes | 685 | Recovery time on node | less than 50ms - hitless | 686 | failure | | 687 | performance management | Yes, Mandatory | 688 | Redundancy | Yes | 689 | Packet loss | 0.1% to 1% | 690 +-----------------------------+-------------------------------------+ 692 Table 1: Teleprotection network requirements 694 3.1.1.1.5. Inter-Trip Protection scheme 696 "Inter-tripping" is the signal-controlled tripping of a circuit 697 breaker to complete the isolation of a circuit or piece of apparatus 698 in concert with the tripping of other circuit breakers. 700 +--------------------------------+----------------------------------+ 701 | Inter-Trip protection | Attribute | 702 | Requirement | | 703 +--------------------------------+----------------------------------+ 704 | One way maximum delay | 5 ms | 705 | Asymetric delay required | No | 706 | Maximum jitter | Not critical | 707 | Topology | Point to point, point to Multi- | 708 | | point | 709 | Bandwidth | 64 Kbps | 710 | Availability | 99.9999 | 711 | precise timing required | Yes | 712 | Recovery time on node failure | less than 50ms - hitless | 713 | performance management | Yes, Mandatory | 714 | Redundancy | Yes | 715 | Packet loss | 0.1% | 716 +--------------------------------+----------------------------------+ 718 Table 2: Inter-Trip protection network requirements 720 3.1.1.1.6. Current Differential Protection Scheme 722 Current differential protection is commonly used for line protection, 723 and is typical for protecting parallel circuits. At both end of the 724 lines the current is measured by the differential relays, and both 725 relays will trip the circuit breaker if the current going into the 726 line does not equal the current going out of the line. This type of 727 protection scheme assumes some form of communications being present 728 between the relays at both end of the line, to allow both relays to 729 compare measured current values. Line differential protection 730 schemes assume a very low telecommunications delay between both 731 relays, often as low as 5ms. Moreover, as those systems are often 732 not time-synchronized, they also assume symmetric telecommunications 733 paths with constant delay, which allows comparing current measurement 734 values taken at the exact same time. 736 +----------------------------------+--------------------------------+ 737 | Current Differential protection | Attribute | 738 | Requirement | | 739 +----------------------------------+--------------------------------+ 740 | One way maximum delay | 5 ms | 741 | Asymetric delay Required | Yes | 742 | Maximum jitter | less than 250 us (750us for | 743 | | legacy IED) | 744 | Topology | Point to point, point to | 745 | | Multi-point | 746 | Bandwidth | 64 Kbps | 747 | Availability | 99.9999 | 748 | precise timing required | Yes | 749 | Recovery time on node failure | less than 50ms - hitless | 750 | performance management | Yes, Mandatory | 751 | Redundancy | Yes | 752 | Packet loss | 0.1% | 753 +----------------------------------+--------------------------------+ 755 Table 3: Current Differential Protection metrics 757 3.1.1.1.7. Distance Protection Scheme 759 Distance (Impedance Relay) protection scheme is based on voltage and 760 current measurements. The network metrics are similar (but not 761 identical to) Current Differential protection. 763 +-------------------------------+-----------------------------------+ 764 | Distance protection | Attribute | 765 | Requirement | | 766 +-------------------------------+-----------------------------------+ 767 | One way maximum delay | 5 ms | 768 | Asymetric delay Required | No | 769 | Maximum jitter | Not critical | 770 | Topology | Point to point, point to Multi- | 771 | | point | 772 | Bandwidth | 64 Kbps | 773 | Availability | 99.9999 | 774 | precise timing required | Yes | 775 | Recovery time on node failure | less than 50ms - hitless | 776 | performance management | Yes, Mandatory | 777 | Redundancy | Yes | 778 | Packet loss | 0.1% | 779 +-------------------------------+-----------------------------------+ 781 Table 4: Distance Protection requirements 783 3.1.1.1.8. Inter-Substation Protection Signaling 785 This use case describes the exchange of Sampled Value and/or GOOSE 786 (Generic Object Oriented Substation Events) message between 787 Intelligent Electronic Devices (IED) in two substations for 788 protection and tripping coordination. The two IEDs are in a master- 789 slave mode. 791 The Current Transformer or Voltage Transformer (CT/VT) in one 792 substation sends the sampled analog voltage or current value to the 793 Merging Unit (MU) over hard wire. The MU sends the time-synchronized 794 61850-9-2 sampled values to the slave IED. The slave IED forwards 795 the information to the Master IED in the other substation. The 796 master IED makes the determination (for example based on sampled 797 value differentials) to send a trip command to the originating IED. 798 Once the slave IED/Relay receives the GOOSE trip for breaker 799 tripping, it opens the breaker. It then sends a confirmation message 800 back to the master. All data exchanges between IEDs are either 801 through Sampled Value and/or GOOSE messages. 803 +----------------------------------+--------------------------------+ 804 | Inter-Substation protection | Attribute | 805 | Requirement | | 806 +----------------------------------+--------------------------------+ 807 | One way maximum delay | 5 ms | 808 | Asymetric delay Required | No | 809 | Maximum jitter | Not critical | 810 | Topology | Point to point, point to | 811 | | Multi-point | 812 | Bandwidth | 64 Kbps | 813 | Availability | 99.9999 | 814 | precise timing required | Yes | 815 | Recovery time on node failure | less than 50ms - hitless | 816 | performance management | Yes, Mandatory | 817 | Redundancy | Yes | 818 | Packet loss | 1% | 819 +----------------------------------+--------------------------------+ 821 Table 5: Inter-Substation Protection requirements 823 3.1.1.2. Intra-Substation Process Bus Communications 825 This use case describes the data flow from the CT/VT to the IEDs in 826 the substation via the MU. The CT/VT in the substation send the 827 sampled value (analog voltage or current) to the MU over hard wire. 828 The MU sends the time-synchronized 61850-9-2 sampled values to the 829 IEDs in the substation in GOOSE message format. The GPS Master Clock 830 can send 1PPS or IRIG-B format to the MU through a serial port or 831 IEEE 1588 protocol via a network. Process bus communication using 832 61850 simplifies connectivity within the substation and removes the 833 requirement for multiple serial connections and removes the slow 834 serial bus architectures that are typically used. This also ensures 835 increased flexibility and increased speed with the use of multicast 836 messaging between multiple devices. 838 +----------------------------------+--------------------------------+ 839 | Intra-Substation protection | Attribute | 840 | Requirement | | 841 +----------------------------------+--------------------------------+ 842 | One way maximum delay | 5 ms | 843 | Asymetric delay Required | No | 844 | Maximum jitter | Not critical | 845 | Topology | Point to point, point to | 846 | | Multi-point | 847 | Bandwidth | 64 Kbps | 848 | Availability | 99.9999 | 849 | precise timing required | Yes | 850 | Recovery time on Node failure | less than 50ms - hitless | 851 | performance management | Yes, Mandatory | 852 | Redundancy | Yes - No | 853 | Packet loss | 0.1% | 854 +----------------------------------+--------------------------------+ 856 Table 6: Intra-Substation Protection requirements 858 3.1.1.3. Wide Area Monitoring and Control Systems 860 The application of synchrophasor measurement data from Phasor 861 Measurement Units (PMU) to Wide Area Monitoring and Control Systems 862 promises to provide important new capabilities for improving system 863 stability. Access to PMU data enables more timely situational 864 awareness over larger portions of the grid than what has been 865 possible historically with normal SCADA (Supervisory Control and Data 866 Acquisition) data. Handling the volume and real-time nature of 867 synchrophasor data presents unique challenges for existing 868 application architectures. Wide Area management System (WAMS) makes 869 it possible for the condition of the bulk power system to be observed 870 and understood in real-time so that protective, preventative, or 871 corrective action can be taken. Because of the very high sampling 872 rate of measurements and the strict requirement for time 873 synchronization of the samples, WAMS has stringent telecommunications 874 requirements in an IP network that are captured in the following 875 table: 877 +----------------------+--------------------------------------------+ 878 | WAMS Requirement | Attribute | 879 +----------------------+--------------------------------------------+ 880 | One way maximum | 50 ms | 881 | delay | | 882 | Asymetric delay | No | 883 | Required | | 884 | Maximum jitter | Not critical | 885 | Topology | Point to point, point to Multi-point, | 886 | | Multi-point to Multi-point | 887 | Bandwidth | 100 Kbps | 888 | Availability | 99.9999 | 889 | precise timing | Yes | 890 | required | | 891 | Recovery time on | less than 50ms - hitless | 892 | Node failure | | 893 | performance | Yes, Mandatory | 894 | management | | 895 | Redundancy | Yes | 896 | Packet loss | 1% | 897 +----------------------+--------------------------------------------+ 899 Table 7: WAMS Special Communication Requirements 901 3.1.1.4. IEC 61850 WAN engineering guidelines requirement 902 classification 904 The IEC (International Electrotechnical Commission) has recently 905 published a Technical Report which offers guidelines on how to define 906 and deploy Wide Area Networks for the interconnections of electric 907 substations, generation plants and SCADA operation centers. The IEC 908 61850-90-12 is providing a classification of WAN communication 909 requirements into 4 classes. Table 8 summarizes these requirements: 911 +----------------+------------+------------+------------+-----------+ 912 | WAN | Class WA | Class WB | Class WC | Class WD | 913 | Requirement | | | | | 914 +----------------+------------+------------+------------+-----------+ 915 | Application | EHV (Extra | HV (High | MV (Medium | General | 916 | field | High | Voltage) | Voltage) | purpose | 917 | | Voltage) | | | | 918 | Latency | 5 ms | 10 ms | 100 ms | > 100 ms | 919 | Jitter | 10 us | 100 us | 1 ms | 10 ms | 920 | Latency | 100 us | 1 ms | 10 ms | 100 ms | 921 | Asymetry | | | | | 922 | Time Accuracy | 1 us | 10 us | 100 us | 10 to 100 | 923 | | | | | ms | 924 | Bit Error rate | 10-7 to | 10-5 to | 10-3 | | 925 | | 10-6 | 10-4 | | | 926 | Unavailability | 10-7 to | 10-5 to | 10-3 | | 927 | | 10-6 | 10-4 | | | 928 | Recovery delay | Zero | 50 ms | 5 s | 50 s | 929 | Cyber security | extremely | High | Medium | Medium | 930 | | high | | | | 931 +----------------+------------+------------+------------+-----------+ 933 Table 8: 61850-90-12 Communication Requirements; Courtesy of IEC 935 3.1.2. Generation Use Case 937 The electrical power generation frequency should be maintained within 938 a very narrow band. Deviations from the acceptable frequency range 939 are detected and the required signals are sent to the power plants 940 for frequency regulation. 942 Automatic generation control (AGC) is a system for adjusting the 943 power output of generators at different power plants, in response to 944 changes in the load. 946 +---------------------------------------------------+---------------+ 947 | FCAG (Frequency Control Automatic Generation) | Attribute | 948 | Requirement | | 949 +---------------------------------------------------+---------------+ 950 | One way maximum delay | 500 ms | 951 | Asymetric delay Required | No | 952 | Maximum jitter | Not critical | 953 | Topology | Point to | 954 | | point | 955 | Bandwidth | 20 Kbps | 956 | Availability | 99.999 | 957 | precise timing required | Yes | 958 | Recovery time on Node failure | N/A | 959 | performance management | Yes, | 960 | | Mandatory | 961 | Redundancy | Yes | 962 | Packet loss | 1% | 963 +---------------------------------------------------+---------------+ 965 Table 9: FCAG Communication Requirements 967 3.1.3. Distribution use case 969 3.1.3.1. Fault Location Isolation and Service Restoration (FLISR) 971 Fault Location, Isolation, and Service Restoration (FLISR) refers to 972 the ability to automatically locate the fault, isolate the fault, and 973 restore service in the distribution network. This will likely be the 974 first widespread application of distributed intelligence in the grid. 976 Static power switch status (open/closed) in the network dictates the 977 power flow to secondary substations. Reconfiguring the network in 978 the event of a fault is typically done manually on site to energize/ 979 de-energize alternate paths. Automating the operation of substation 980 switchgear allows the flow of power to be altered automatically under 981 fault conditions. 983 FLISR can be managed centrally from a Distribution Management System 984 (DMS) or executed locally through distributed control via intelligent 985 switches and fault sensors. 987 +----------------------+--------------------------------------------+ 988 | FLISR Requirement | Attribute | 989 +----------------------+--------------------------------------------+ 990 | One way maximum | 80 ms | 991 | delay | | 992 | Asymetric delay | No | 993 | Required | | 994 | Maximum jitter | 40 ms | 995 | Topology | Point to point, point to Multi-point, | 996 | | Multi-point to Multi-point | 997 | Bandwidth | 64 Kbps | 998 | Availability | 99.9999 | 999 | precise timing | Yes | 1000 | required | | 1001 | Recovery time on | Depends on customer impact | 1002 | Node failure | | 1003 | performance | Yes, Mandatory | 1004 | management | | 1005 | Redundancy | Yes | 1006 | Packet loss | 0.1% | 1007 +----------------------+--------------------------------------------+ 1009 Table 10: FLISR Communication Requirements 1011 3.2. Electrical Utilities Today 1013 Many utilities still rely on complex environments formed of multiple 1014 application-specific proprietary networks, including TDM networks. 1016 In this kind of environment there is no mixing of OT and IT 1017 applications on the same network, and information is siloed between 1018 operational areas. 1020 Specific calibration of the full chain is required, which is costly. 1022 This kind of environment prevents utility operations from realizing 1023 the operational efficiency benefits, visibility, and functional 1024 integration of operational information across grid applications and 1025 data networks. 1027 In addition, there are many security-related issues as discussed in 1028 the following section. 1030 3.2.1. Security Current Practices and Limitations 1032 Grid monitoring and control devices are already targets for cyber 1033 attacks, and legacy telecommunications protocols have many intrinsic 1034 network-related vulnerabilities. For example, DNP3, Modbus, 1035 PROFIBUS/PROFINET, and other protocols are designed around a common 1036 paradigm of request and respond. Each protocol is designed for a 1037 master device such as an HMI (Human Machine Interface) system to send 1038 commands to subordinate slave devices to retrieve data (reading 1039 inputs) or control (writing to outputs). Because many of these 1040 protocols lack authentication, encryption, or other basic security 1041 measures, they are prone to network-based attacks, allowing a 1042 malicious actor or attacker to utilize the request-and-respond system 1043 as a mechanism for command-and-control like functionality. Specific 1044 security concerns common to most industrial control, including 1045 utility telecommunication protocols include the following: 1047 o Network or transport errors (e.g. malformed packets or excessive 1048 latency) can cause protocol failure. 1050 o Protocol commands may be available that are capable of forcing 1051 slave devices into inoperable states, including powering-off 1052 devices, forcing them into a listen-only state, disabling 1053 alarming. 1055 o Protocol commands may be available that are capable of restarting 1056 communications and otherwise interrupting processes. 1058 o Protocol commands may be available that are capable of clearing, 1059 erasing, or resetting diagnostic information such as counters and 1060 diagnostic registers. 1062 o Protocol commands may be available that are capable of requesting 1063 sensitive information about the controllers, their configurations, 1064 or other need-to-know information. 1066 o Most protocols are application layer protocols transported over 1067 TCP; therefore it is easy to transport commands over non-standard 1068 ports or inject commands into authorized traffic flows. 1070 o Protocol commands may be available that are capable of 1071 broadcasting messages to many devices at once (i.e. a potential 1072 DoS). 1074 o Protocol commands may be available to query the device network to 1075 obtain defined points and their values (i.e. a configuration 1076 scan). 1078 o Protocol commands may be available that will list all available 1079 function codes (i.e. a function scan). 1081 These inherent vulnerabilities, along with increasing connectivity 1082 between IT an OT networks, make network-based attacks very feasible. 1084 Simple injection of malicious protocol commands provides control over 1085 the target process. Altering legitimate protocol traffic can also 1086 alter information about a process and disrupt the legitimate controls 1087 that are in place over that process. A man-in-the-middle attack 1088 could provide both control over a process and misrepresentation of 1089 data back to operator consoles. 1091 3.3. Electrical Utilities Future 1093 The business and technology trends that are sweeping the utility 1094 industry will drastically transform the utility business from the way 1095 it has been for many decades. At the core of many of these changes 1096 is a drive to modernize the electrical grid with an integrated 1097 telecommunications infrastructure. However, interoperability 1098 concerns, legacy networks, disparate tools, and stringent security 1099 requirements all add complexity to the grid transformation. Given 1100 the range and diversity of the requirements that should be addressed 1101 by the next generation telecommunications infrastructure, utilities 1102 need to adopt a holistic architectural approach to integrate the 1103 electrical grid with digital telecommunications across the entire 1104 power delivery chain. 1106 The key to modernizing grid telecommunications is to provide a 1107 common, adaptable, multi-service network infrastructure for the 1108 entire utility organization. Such a network serves as the platform 1109 for current capabilities while enabling future expansion of the 1110 network to accommodate new applications and services. 1112 To meet this diverse set of requirements, both today and in the 1113 future, the next generation utility telecommunnications network will 1114 be based on open-standards-based IP architecture. An end-to-end IP 1115 architecture takes advantage of nearly three decades of IP technology 1116 development, facilitating interoperability across disparate networks 1117 and devices, as it has been already demonstrated in many mission- 1118 critical and highly secure networks. 1120 IPv6 is seen as a future telecommunications technology for the Smart 1121 Grid; the IEC (International Electrotechnical Commission) and 1122 different National Committees have mandated a specific adhoc group 1123 (AHG8) to define the migration strategy to IPv6 for all the IEC TC57 1124 power automation standards. 1126 3.3.1. Migration to Packet-Switched Network 1128 Throughout the world, utilities are increasingly planning for a 1129 future based on smart grid applications requiring advanced 1130 telecommunications systems. Many of these applications utilize 1131 packet connectivity for communicating information and control signals 1132 across the utility's Wide Area Network (WAN), made possible by 1133 technologies such as multiprotocol label switching (MPLS). The data 1134 that traverses the utility WAN includes: 1136 o Grid monitoring, control, and protection data 1138 o Non-control grid data (e.g. asset data for condition-based 1139 monitoring) 1141 o Physical safety and security data (e.g. voice and video) 1143 o Remote worker access to corporate applications (voice, maps, 1144 schematics, etc.) 1146 o Field area network backhaul for smart metering, and distribution 1147 grid management 1149 o Enterprise traffic (email, collaboration tools, business 1150 applications) 1152 WANs support this wide variety of traffic to and from substations, 1153 the transmission and distribution grid, generation sites, between 1154 control centers, and between work locations and data centers. To 1155 maintain this rapidly expanding set of applications, many utilities 1156 are taking steps to evolve present time-division multiplexing (TDM) 1157 based and frame relay infrastructures to packet systems. Packet- 1158 based networks are designed to provide greater functionalities and 1159 higher levels of service for applications, while continuing to 1160 deliver reliability and deterministic (real-time) traffic support. 1162 3.3.2. Telecommunications Trends 1164 These general telecommunications topics are in addition to the use 1165 cases that have been addressed so far. These include both current 1166 and future telecommunications related topics that should be factored 1167 into the network architecture and design. 1169 3.3.2.1. General Telecommunications Requirements 1171 o IP Connectivity everywhere 1173 o Monitoring services everywhere and from different remote centers 1175 o Move services to a virtual data center 1177 o Unify access to applications / information from the corporate 1178 network 1180 o Unify services 1182 o Unified Communications Solutions 1184 o Mix of fiber and microwave technologies - obsolescence of SONET/ 1185 SDH or TDM 1187 o Standardize grid telecommunications protocol to opened standard to 1188 ensure interoperability 1190 o Reliable Telecommunications for Transmission and Distribution 1191 Substations 1193 o IEEE 1588 time synchronization Client / Server Capabilities 1195 o Integration of Multicast Design 1197 o QoS Requirements Mapping 1199 o Enable Future Network Expansion 1201 o Substation Network Resilience 1203 o Fast Convergence Design 1205 o Scalable Headend Design 1207 o Define Service Level Agreements (SLA) and Enable SLA Monitoring 1209 o Integration of 3G/4G Technologies and future technologies 1211 o Ethernet Connectivity for Station Bus Architecture 1213 o Ethernet Connectivity for Process Bus Architecture 1215 o Protection, teleprotection and PMU (Phaser Measurement Unit) on IP 1217 3.3.2.2. Specific Network topologies of Smart Grid Applications 1219 Utilities often have very large private telecommunications networks. 1220 It covers an entire territory / country. The main purpose of the 1221 network, until now, has been to support transmission network 1222 monitoring, control, and automation, remote control of generation 1223 sites, and providing FCAPS (Fault, Configuration, Accounting, 1224 Performance, Security) services from centralized network operation 1225 centers. 1227 Going forward, one network will support operation and maintenance of 1228 electrical networks (generation, transmission, and distribution), 1229 voice and data services for ten of thousands of employees and for 1230 exchange with neighboring interconnections, and administrative 1231 services. To meet those requirements, utility may deploy several 1232 physical networks leveraging different technologies across the 1233 country: an optical network and a microwave network for instance. 1234 Each protection and automatism system between two points has two 1235 telecommunications circuits, one on each network. Path diversity 1236 between two substations is key. Regardless of the event type 1237 (hurricane, ice storm, etc.), one path shall stay available so the 1238 system can still operate. 1240 In the optical network, signals are transmitted over more than tens 1241 of thousands of circuits using fiber optic links, microwave and 1242 telephone cables. This network is the nervous system of the 1243 utility's power transmission operations. The optical network 1244 represents ten of thousands of km of cable deployed along the power 1245 lines, with individual runs as long as 280 km. 1247 3.3.2.3. Precision Time Protocol 1249 Some utilities do not use GPS clocks in generation substations. One 1250 of the main reasons is that some of the generation plants are 30 to 1251 50 meters deep under ground and the GPS signal can be weak and 1252 unreliable. Instead, atomic clocks are used. Clocks are 1253 synchronized amongst each other. Rubidium clocks provide clock and 1254 1ms timestamps for IRIG-B. 1256 Some companies plan to transition to the Precision Time Protocol 1257 (PTP, [IEEE1588]), distributing the synchronization signal over the 1258 IP/MPLS network. PTP provides a mechanism for synchronizing the 1259 clocks of participating nodes to a high degree of accuracy and 1260 precision. 1262 PTP operates based on the following assumptions: 1264 It is assumed that the network eliminates cyclic forwarding of PTP 1265 messages within each communication path (e.g. by using a spanning 1266 tree protocol). 1268 PTP is tolerant of an occasional missed message, duplicated 1269 message, or message that arrived out of order. However, PTP 1270 assumes that such impairments are relatively rare. 1272 PTP was designed assuming a multicast communication model, however 1273 PTP also supports a unicast communication model as long as the 1274 behavior of the protocol is preserved. 1276 Like all message-based time transfer protocols, PTP time accuracy 1277 is degraded by delay asymmetry in the paths taken by event 1278 messages. Asymmetry is not detectable by PTP, however, if such 1279 delays are known a priori, PTP can correct for asymmetry. 1281 IEC 61850 will recommend the use of the IEEE PTP 1588 Utility Profile 1282 (as defined in [IEC62439-3:2012] Annex B) which offers the support of 1283 redundant attachment of clocks to Parallel Redundancy Protcol (PRP) 1284 and High-availability Seamless Redundancy (HSR) networks. 1286 3.3.3. Security Trends in Utility Networks 1288 Although advanced telecommunications networks can assist in 1289 transforming the energy industry by playing a critical role in 1290 maintaining high levels of reliability, performance, and 1291 manageability, they also introduce the need for an integrated 1292 security infrastructure. Many of the technologies being deployed to 1293 support smart grid projects such as smart meters and sensors can 1294 increase the vulnerability of the grid to attack. Top security 1295 concerns for utilities migrating to an intelligent smart grid 1296 telecommunications platform center on the following trends: 1298 o Integration of distributed energy resources 1300 o Proliferation of digital devices to enable management, automation, 1301 protection, and control 1303 o Regulatory mandates to comply with standards for critical 1304 infrastructure protection 1306 o Migration to new systems for outage management, distribution 1307 automation, condition-based maintenance, load forecasting, and 1308 smart metering 1310 o Demand for new levels of customer service and energy management 1312 This development of a diverse set of networks to support the 1313 integration of microgrids, open-access energy competition, and the 1314 use of network-controlled devices is driving the need for a converged 1315 security infrastructure for all participants in the smart grid, 1316 including utilities, energy service providers, large commercial and 1317 industrial, as well as residential customers. Securing the assets of 1318 electric power delivery systems (from the control center to the 1319 substation, to the feeders and down to customer meters) requires an 1320 end-to-end security infrastructure that protects the myriad of 1321 telecommunications assets used to operate, monitor, and control power 1322 flow and measurement. 1324 "Cyber security" refers to all the security issues in automation and 1325 telecommunications that affect any functions related to the operation 1326 of the electric power systems. Specifically, it involves the 1327 concepts of: 1329 o Integrity : data cannot be altered undetectably 1331 o Authenticity : the telecommunications parties involved must be 1332 validated as genuine 1334 o Authorization : only requests and commands from the authorized 1335 users can be accepted by the system 1337 o Confidentiality : data must not be accessible to any 1338 unauthenticated users 1340 When designing and deploying new smart grid devices and 1341 telecommunications systems, it is imperative to understand the 1342 various impacts of these new components under a variety of attack 1343 situations on the power grid. Consequences of a cyber attack on the 1344 grid telecommunications network can be catastrophic. This is why 1345 security for smart grid is not just an ad hoc feature or product, 1346 it's a complete framework integrating both physical and Cyber 1347 security requirements and covering the entire smart grid networks 1348 from generation to distribution. Security has therefore become one 1349 of the main foundations of the utility telecom network architecture 1350 and must be considered at every layer with a defense-in-depth 1351 approach. Migrating to IP based protocols is key to address these 1352 challenges for two reasons: 1354 o IP enables a rich set of features and capabilities to enhance the 1355 security posture 1357 o IP is based on open standards, which allows interoperability 1358 between different vendors and products, driving down the costs 1359 associated with implementing security solutions in OT networks. 1361 Securing OT (Operation technology) telecommunications over packet- 1362 switched IP networks follow the same principles that are foundational 1363 for securing the IT infrastructure, i.e., consideration must be given 1364 to enforcing electronic access control for both person-to-machine and 1365 machine-to-machine communications, and providing the appropriate 1366 levels of data privacy, device and platform integrity, and threat 1367 detection and mitigation. 1369 3.4. Electrical Utilities Asks 1371 o Mixed L2 and L3 topologies 1373 o Deterministic behavior 1375 o Bounded latency and jitter 1377 o High availability, low recovery time 1379 o Redundancy, low packet loss 1381 o Precise timing 1383 o Centralized computing of deterministic paths 1385 o Distributed configuration may also be useful 1387 4. Building Automation Systems 1389 4.1. Use Case Description 1391 A Building Automation System (BAS) manages equipment and sensors in a 1392 building for improving residents' comfort, reducing energy 1393 consumption, and responding to failures and emergencies. For 1394 example, the BAS measures the temperature of a room using sensors and 1395 then controls the HVAC (heating, ventilating, and air conditioning) 1396 to maintain a set temperature and minimize energy consumption. 1398 A BAS primarily performs the following functions: 1400 o Periodically measures states of devices, for example humidity and 1401 illuminance of rooms, open/close state of doors, FAN speed, etc. 1403 o Stores the measured data. 1405 o Provides the measured data to BAS systems and operators. 1407 o Generates alarms for abnormal state of devices. 1409 o Controls devices (e.g. turn off room lights at 10:00 PM). 1411 4.2. Building Automation Systems Today 1412 4.2.1. BAS Architecture 1414 A typical BAS architecture of today is shown in Figure 1. 1416 +----------------------------+ 1417 | | 1418 | BMS HMI | 1419 | | | | 1420 | +----------------------+ | 1421 | | Management Network | | 1422 | +----------------------+ | 1423 | | | | 1424 | LC LC | 1425 | | | | 1426 | +----------------------+ | 1427 | | Field Network | | 1428 | +----------------------+ | 1429 | | | | | | 1430 | Dev Dev Dev Dev | 1431 | | 1432 +----------------------------+ 1434 BMS := Building Management Server 1435 HMI := Human Machine Interface 1436 LC := Local Controller 1438 Figure 1: BAS architecture 1440 There are typically two layers of network in a BAS. The upper one is 1441 called the Management Network and the lower one is called the Field 1442 Network. In management networks an IP-based communication protocol 1443 is used, while in field networks non-IP based communication protocols 1444 ("field protocols") are mainly used. Field networks have specific 1445 timing requirements, whereas management networks can be best-effort. 1447 A Human Machine Interface (HMI) is typically a desktop PC used by 1448 operators to monitor and display device states, send device control 1449 commands to Local Controllers (LCs), and configure building schedules 1450 (for example "turn off all room lights in the building at 10:00 PM"). 1452 A Building Management Server (BMS) performs the following operations. 1454 o Collect and store device states from LCs at regular intervals. 1456 o Send control values to LCs according to a building schedule. 1458 o Send an alarm signal to operators if it detects abnormal devices 1459 states. 1461 The BMS and HMI communicate with LCs via IP-based "management 1462 protocols" (see standards [bacnetip], [knx]). 1464 A LC is typically a Programmable Logic Controller (PLC) which is 1465 connected to several tens or hundreds of devices using "field 1466 protocols". An LC performs the following kinds of operations: 1468 o Measure device states and provide the information to BMS or HMI. 1470 o Send control values to devices, unilaterally or as part of a 1471 feedback control loop. 1473 There are many field protocols used today; some are standards-based 1474 and others are proprietary (see standards [lontalk], [modbus], 1475 [profibus] and [flnet]). The result is that BASs have multiple MAC/ 1476 PHY modules and interfaces. This makes BASs more expensive, slower 1477 to develop, and can result in "vendor lock-in" with multiple types of 1478 management applications. 1480 4.2.2. BAS Deployment Model 1482 An example BAS for medium or large buildings is shown in Figure 2. 1483 The physical layout spans multiple floors, and there is a monitoring 1484 room where the BAS management entities are located. Each floor will 1485 have one or more LCs depending upon the number of devices connected 1486 to the field network. 1488 +--------------------------------------------------+ 1489 | Floor 3 | 1490 | +----LC~~~~+~~~~~+~~~~~+ | 1491 | | | | | | 1492 | | Dev Dev Dev | 1493 | | | 1494 |--- | ------------------------------------------| 1495 | | Floor 2 | 1496 | +----LC~~~~+~~~~~+~~~~~+ Field Network | 1497 | | | | | | 1498 | | Dev Dev Dev | 1499 | | | 1500 |--- | ------------------------------------------| 1501 | | Floor 1 | 1502 | +----LC~~~~+~~~~~+~~~~~+ +-----------------| 1503 | | | | | | Monitoring Room | 1504 | | Dev Dev Dev | | 1505 | | | BMS HMI | 1506 | | Management Network | | | | 1507 | +--------------------------------+-----+ | 1508 | | | 1509 +--------------------------------------------------+ 1511 Figure 2: BAS Deployment model for Medium/Large Buildings 1513 Each LC is connected to the monitoring room via the Management 1514 network, and the management functions are performed within the 1515 building. In most cases, fast Ethernet (e.g. 100BASE-T) is used for 1516 the management network. Since the management network is non- 1517 realtime, use of Ethernet without quality of service is sufficient 1518 for today's deployment. 1520 In the field network a variety of physical interfaces such as RS232C 1521 and RS485 are used, which have specific timing requirements. Thus if 1522 a field network is to be replaced with an Ethernet or wireless 1523 network, such networks must support time-critical deterministic 1524 flows. 1526 In Figure 3, another deployment model is presented in which the 1527 management system is hosted remotely. This is becoming popular for 1528 small office and residential buildings in which a standalone 1529 monitoring system is not cost-effective. 1531 +---------------+ 1532 | Remote Center | 1533 | | 1534 | BMS HMI | 1535 +------------------------------------+ | | | | 1536 | Floor 2 | | +---+---+ | 1537 | +----LC~~~~+~~~~~+ Field Network| | | | 1538 | | | | | | Router | 1539 | | Dev Dev | +-------|-------+ 1540 | | | | 1541 |--- | ------------------------------| | 1542 | | Floor 1 | | 1543 | +----LC~~~~+~~~~~+ | | 1544 | | | | | | 1545 | | Dev Dev | | 1546 | | | | 1547 | | Management Network | WAN | 1548 | +------------------------Router-------------+ 1549 | | 1550 +------------------------------------+ 1552 Figure 3: Deployment model for Small Buildings 1554 Some interoperability is possible today in the Management Network, 1555 but not in today's field networks due to their non-IP-based design. 1557 4.2.3. Use Cases for Field Networks 1559 Below are use cases for Environmental Monitoring, Fire Detection, and 1560 Feedback Control, and their implications for field network 1561 performance. 1563 4.2.3.1. Environmental Monitoring 1565 The BMS polls each LC at a maximum measurement interval of 100ms (for 1566 example to draw a historical chart of 1 second granularity with a 10x 1567 sampling interval) and then performs the operations as specified by 1568 the operator. Each LC needs to measure each of its several hundred 1569 sensors once per measurement interval. Latency is not critical in 1570 this scenario as long as all sensor values are completed in the 1571 measurement interval. Availability is expected to be 99.999 %. 1573 4.2.3.2. Fire Detection 1575 On detection of a fire, the BMS must stop the HVAC, close the fire 1576 shutters, turn on the fire sprinklers, send an alarm, etc. There are 1577 typically ~10s of sensors per LC that BMS needs to manage. In this 1578 scenario the measurement interval is 10-50ms, the communication delay 1579 is 10ms, and the availability must be 99.9999 %. 1581 4.2.3.3. Feedback Control 1583 BAS systems utilize feedback control in various ways; the most time- 1584 critial is control of DC motors, which require a short feedback 1585 interval (1-5ms) with low communication delay (10ms) and jitter 1586 (1ms). The feedback interval depends on the characteristics of the 1587 device and a target quality of control value. There are typically 1588 ~10s of such devices per LC. 1590 Communication delay is expected to be less than 10 ms, jitter less 1591 than 1 sec while the availability must be 99.9999% . 1593 4.2.4. Security Considerations 1595 When BAS field networks were developed it was assumed that the field 1596 networks would always be physically isolated from external networks 1597 and therefore security was not a concern. In today's world many BASs 1598 are managed remotely and are thus connected to shared IP networks and 1599 so security is definitely a concern, yet security features are not 1600 available in the majority of BAS field network deployments . 1602 The management network, being an IP-based network, has the protocols 1603 available to enable network security, but in practice many BAS 1604 systems do not implement even the available security features such as 1605 device authentication or encryption for data in transit. 1607 4.3. BAS Future 1609 In the future we expect more fine-grained environmental monitoring 1610 and lower energy consumption, which will require more sensors and 1611 devices, thus requiring larger and more complex building networks. 1613 We expect building networks to be connected to or converged with 1614 other networks (Enterprise network, Home network, and Internet). 1616 Therefore better facilities for network management, control, 1617 reliability and security are critical in order to improve resident 1618 and operator convenience and comfort. For example the ability to 1619 monitor and control building devices via the internet would enable 1620 (for example) control of room lights or HVAC from a resident's 1621 desktop PC or phone application. 1623 4.4. BAS Asks 1625 The community would like to see an interoperable protocol 1626 specification that can satisfy the timing, security, availability and 1627 QoS constraints described above, such that the resulting converged 1628 network can replace the disparate field networks. Ideally this 1629 connectivity could extend to the open Internet. 1631 This would imply an architecture that can guarantee 1633 o Low communication delays (from <10ms to 100ms in a network of 1634 several hundred devices) 1636 o Low jitter (< 1 ms) 1638 o Tight feedback intervals (1ms - 10ms) 1640 o High network availability (up to 99.9999% ) 1642 o Availability of network data in disaster scenario 1644 o Authentication between management and field devices (both local 1645 and remote) 1647 o Integrity and data origin authentication of communication data 1648 between field and management devices 1650 o Confidentiality of data when communicated to a remote device 1652 5. Wireless for Industrial 1654 5.1. Use Case Description 1656 Wireless networks are useful for industrial applications, for example 1657 when portable, fast-moving or rotating objects are involved, and for 1658 the resource-constrained devices found in the Internet of Things 1659 (IoT). 1661 Such network-connected sensors, actuators, control loops (etc.) 1662 typically require that the underlying network support real-time 1663 quality of service (QoS), as well as specific classes of other 1664 network properties such as reliability, redundancy, and security. 1666 These networks may also contain very large numbers of devices, for 1667 example for factories, "big data" acquisition, and the IoT. Given 1668 the large numbers of devices installed, and the potential 1669 pervasiveness of the IoT, this is a huge and very cost-sensitive 1670 market. For example, a 1% cost reduction in some areas could save 1671 $100B 1673 5.1.1. Network Convergence using 6TiSCH 1675 Some wireless network technologies support real-time QoS, and are 1676 thus useful for these kinds of networks, but others do not. For 1677 example WiFi is pervasive but does not provide guaranteed timing or 1678 delivery of packets, and thus is not useful in this context. 1680 In this use case we focus on one specific wireless network technology 1681 which does provide the required deterministic QoS, which is "IPv6 1682 over the TSCH mode of IEEE 802.15.4e" (6TiSCH, where TSCH stands for 1683 "Time-Slotted Channel Hopping", see [I-D.ietf-6tisch-architecture], 1684 [IEEE802154], [IEEE802154e], and [RFC7554]). 1686 There are other deterministic wireless busses and networks available 1687 today, however they are imcompatible with each other, and 1688 incompatible with IP traffic (for example [ISA100], [WirelessHART]). 1690 Thus the primary goal of this use case is to apply 6TiSH as a 1691 converged IP- and standards-based wireless network for industrial 1692 applications, i.e. to replace multiple proprietary and/or 1693 incompatible wireless networking and wireless network management 1694 standards. 1696 5.1.2. Common Protocol Development for 6TiSCH 1698 Today there are a number of protocols required by 6TiSCH which are 1699 still in development, and a second intent of this use case is to 1700 highlight the ways in which these "missing" protocols share goals in 1701 common with DetNet. Thus it is possible that some of the protocol 1702 technology developed for DetNet will also be applicable to 6TiSCH. 1704 These protocol goals are identified here, along with their 1705 relationship to DetNet. It is likely that ultimately the resulting 1706 protocols will not be identical, but will share design principles 1707 which contribute to the eficiency of enabling both DetNet and 6TiSCH. 1709 One such commonality is that although at a different time scale, in 1710 both TSN [IEEE802.1TSNTG] and TSCH a packet crosses the network from 1711 node to node follows a precise schedule, as a train that leaves 1712 intermediate stations at precise times along its path. This kind of 1713 operation reduces collisions, saves energy, and enables engineering 1714 the network for deterministic properties. 1716 Another commonality is remote monitoring and scheduling management of 1717 a TSCH network by a Path Computation Element (PCE) and Network 1718 Management Entity (NME). The PCE/NME manage timeslots and device 1719 resources in a manner that minimizes the interaction with and the 1720 load placed on resource-constrained devices. For example, a tiny IoT 1721 device may have just enough buffers to store one or a few IPv6 1722 packets, and will have limited bandwidth between peers such that it 1723 can maintain only a small amount of peer information, and will not be 1724 able to store many packets waiting to be forwarded. It is 1725 advantageous then for it to only be required to carry out the 1726 specific behavior assigned to it by the PCE/NME (as opposed to 1727 maintaining its own IP stack, for example). 1729 6TiSCH depends on [PCE] and [I-D.finn-detnet-architecture], and we 1730 expect that DetNet will maintain consistency with [IEEE802.1TSNTG]. 1732 5.2. Wireless Industrial Today 1734 Today industrial wireless is accomplished using multiple 1735 deterministic wireless networks which are incompatible with each 1736 other and with IP traffic. 1738 6TiSCH is not yet fully specified, so it cannot be used in today's 1739 applications. 1741 5.3. Wireless Industrial Future 1743 5.3.1. Unified Wireless Network and Management 1745 We expect DetNet and 6TiSCH together to enable converged transport of 1746 deterministic and best-effort traffic flows between real-time 1747 industrial devices and wide area networks via IP routing. A high 1748 level view of a basic such network is shown in Figure 4. 1750 ---+-------- ............ ------------ 1751 | External Network | 1752 | +-----+ 1753 +-----+ | NME | 1754 | | LLN Border | | 1755 | | router +-----+ 1756 +-----+ 1757 o o o 1758 o o o o 1759 o o LLN o o o 1760 o o o o 1761 o 1763 Figure 4: Basic 6TiSCH Network 1765 Figure 5 shows a backbone router federating multiple synchronized 1766 6TiSCH subnets into a single subnet connected to the external 1767 network. 1769 ---+-------- ............ ------------ 1770 | External Network | 1771 | +-----+ 1772 | +-----+ | NME | 1773 +-----+ | +-----+ | | 1774 | | Router | | PCE | +-----+ 1775 | | +--| | 1776 +-----+ +-----+ 1777 | | 1778 | Subnet Backbone | 1779 +--------------------+------------------+ 1780 | | | 1781 +-----+ +-----+ +-----+ 1782 | | Backbone | | Backbone | | Backbone 1783 o | | router | | router | | router 1784 +-----+ +-----+ +-----+ 1785 o o o o o 1786 o o o o o o o o o o o 1787 o o o LLN o o o o 1788 o o o o o o o o o o o o 1790 Figure 5: Extended 6TiSCH Network 1792 The backbone router must ensure end-to-end deterministic behavior 1793 between the LLN and the backbone. We would like to see this 1794 accomplished in conformance with the work done in 1795 [I-D.finn-detnet-architecture] with respect to Layer-3 aspects of 1796 deterministic networks that span multiple Layer-2 domains. 1798 The PCE must compute a deterministic path end-to-end across the TSCH 1799 network and IEEE802.1 TSN Ethernet backbone, and DetNet protocols are 1800 expected to enable end-to-end deterministic forwarding. 1802 +-----+ 1803 | IoT | 1804 | G/W | 1805 +-----+ 1806 ^ <---- Elimination 1807 | | 1808 Track branch | | 1809 +-------+ +--------+ Subnet Backbone 1810 | | 1811 +--|--+ +--|--+ 1812 | | | Backbone | | | Backbone 1813 o | | | router | | | router 1814 +--/--+ +--|--+ 1815 o / o o---o----/ o 1816 o o---o--/ o o o o o 1817 o \ / o o LLN o 1818 o v <---- Replication 1819 o 1821 Figure 6: 6TiSCH Network with PRE 1823 5.3.1.1. PCE and 6TiSCH ARQ Retries 1825 6TiSCH uses the IEEE802.15.4 Automatic Repeat-reQuest (ARQ) mechanism 1826 to provide higher reliability of packet delivery. ARQ is related to 1827 packet replication and elimination because there are two independent 1828 paths for packets to arrive at the destination, and if an expected 1829 packed does not arrive on one path then it checks for the packet on 1830 the second path. 1832 Although to date this mechanism is only used by wireless networks, 1833 this may be a technique that would be appropriate for DetNet and so 1834 aspects of the enabling protocol could be co-developed. 1836 For example, in Figure 6, a Track is laid out from a field device in 1837 a 6TiSCH network to an IoT gateway that is located on a IEEE802.1 TSN 1838 backbone. 1840 The Replication function in the field device sends a copy of each 1841 packet over two different branches, and the PCE schedules each hop of 1842 both branches so that the two copies arrive in due time at the 1843 gateway. In case of a loss on one branch, hopefully the other copy 1844 of the packet still arrives within the allocated time. If two copies 1845 make it to the IoT gateway, the Elimination function in the gateway 1846 ignores the extra packet and presents only one copy to upper layers. 1848 At each 6TiSCH hop along the Track, the PCE may schedule more than 1849 one timeSlot for a packet, so as to support Layer-2 retries (ARQ). 1851 In current deployments, a TSCH Track does not necessarily support PRE 1852 but is systematically multi-path. This means that a Track is 1853 scheduled so as to ensure that each hop has at least two forwarding 1854 solutions, and the forwarding decision is to try the preferred one 1855 and use the other in case of Layer-2 transmission failure as detected 1856 by ARQ. 1858 5.3.2. Schedule Management by a PCE 1860 A common feature of 6TiSCH and DetNet is the action of a PCE to 1861 configure paths through the network. Specifically, what is needed is 1862 a protocol and data model that the PCE will use to get/set the 1863 relevant configuration from/to the devices, as well as perform 1864 operations on the devices. We expect that this protocol will be 1865 developed by DetNet with consideration for its reuse by 6TiSCH. The 1866 remainder of this section provides a bit more context from the 6TiSCH 1867 side. 1869 5.3.2.1. PCE Commands and 6TiSCH CoAP Requests 1871 The 6TiSCH device does not expect to place the request for bandwidth 1872 between itself and another device in the network. Rather, an 1873 operation control system invoked through a human interface specifies 1874 the required traffic specification and the end nodes (in terms of 1875 latency and reliability). Based on this information, the PCE must 1876 compute a path between the end nodes and provision the network with 1877 per-flow state that describes the per-hop operation for a given 1878 packet, the corresponding timeslots, and the flow identification that 1879 enables recognizing that a certain packet belongs to a certain path, 1880 etc. 1882 For a static configuration that serves a certain purpose for a long 1883 period of time, it is expected that a node will be provisioned in one 1884 shot with a full schedule, which incorporates the aggregation of its 1885 behavior for multiple paths. 6TiSCH expects that the programing of 1886 the schedule will be done over COAP as discussed in 1887 [I-D.ietf-6tisch-coap]. 1889 6TiSCH expects that the PCE commands will be issued directly as CoAP 1890 requests or be mapped back and forth into CoAP by a gateway function 1891 at the edge of the 6TiSCH network. For instance, it is possible that 1892 a mapping entity on the backbone transforms a non-CoAP protocol such 1893 as PCEP into the RESTful interfaces that the 6TiSCH devices support. 1894 This architecture will be refined to comply with DetNet 1895 [I-D.finn-detnet-architecture] when the work is formalized. Related 1896 information about 6TiSCH can be found at 1897 [I-D.ietf-6tisch-6top-interface] and RPL [RFC6550]. 1899 If it appears that a path through the network does not perform as 1900 expected, a protocol may be used to update the state in the devices, 1901 but in 6TiSCH that flow was not designed and no protocol was selected 1902 and it is expected that DetNet will determine the appropriate end-to- 1903 end protocols to be used in that case. 1905 A "slotFrame" is the base object that the PCE needs to manipulate to 1906 program a schedule into an LLN node ([I-D.ietf-6tisch-architecture]). 1908 The PCE should be able to read energy data from devices, and compute 1909 paths that will implement policies on how energy in devices is 1910 consumed, for instance to ensure that the spent energy does not 1911 exceeded the available energy over a period of time. 1913 6TiSCH devices can discover their neighbors over the radio using a 1914 mechanism such as beacons, but even though the neighbor information 1915 is available in the 6TiSCH interface data model, 6TiSCH does not 1916 describe a protocol to proactively push the neighborhood information 1917 to a PCE. DetNet should define this protocol, and it and should 1918 operate over CoAP. The protocol should be able to carry multiple 1919 metrics, in particular the same metrics as used for RPL operations 1920 [RFC6551] 1922 5.3.2.2. 6TiSCH IP Interface 1924 "6top" ([I-D.wang-6tisch-6top-sublayer]) is a logical link control 1925 sitting between the IP layer and the TSCH MAC layer which provides 1926 the link abstraction that is required for IP operations. The 6top 1927 data model and management interfaces are further discussed in 1928 [I-D.ietf-6tisch-6top-interface] and [I-D.ietf-6tisch-coap]. 1930 An IP packet that is sent along a 6TiSCH path uses the Differentiated 1931 Services Per-Hop-Behavior Group called Deterministic Forwarding, as 1932 described in [I-D.svshah-tsvwg-deterministic-forwarding]. 1934 5.3.3. 6TiSCH Security Considerations 1936 On top of the classical requirements for protection of control 1937 signaling, it must be noted that 6TiSCH networks operate on limited 1938 resources that can be depleted rapidly in a DoS attack on the system, 1939 for instance by placing a rogue device in the network, or by 1940 obtaining management control and setting up unexpected additional 1941 paths. 1943 5.4. Wireless Industrial Asks 1945 6TiSCH depends on DetNet to define: 1947 o Configuration (state) and operations for deterministic paths 1949 o End-to-end protocols for deterministic forwarding (tagging, IP) 1951 o Protocol for packet replication and elimination 1953 o Protocol for packet automatic retries (ARQ) (specific to wireless) 1955 6. Cellular Radio 1957 6.1. Use Case Description 1959 This use case describes the application of deterministic networking 1960 in the context of cellular telecom transport networks. Important 1961 elements include time synchronization, clock distribution, and ways 1962 of establishing time-sensitive streams for both Layer-2 and Layer-3 1963 user plane traffic. 1965 6.1.1. Network Architecture 1967 Figure 7 illustrates a typical 3GPP-defined cellular network 1968 architecture, which includes "Fronthaul" and "Midhaul" network 1969 segments. The "Fronthaul" is the network connecting base stations 1970 (baseband processing units) to the remote radio heads (antennas). 1971 The "Midhaul" is the network inter-connecting base stations (or small 1972 cell sites). 1974 In Figure 7 "eNB" ("E-UTRAN Node B") is the hardware that is 1975 connected to the mobile phone network which communicates directly 1976 with mobile handsets ([TS36300]). 1978 Y (remote radio heads (antennas)) 1979 \ 1980 Y__ \.--. .--. +------+ 1981 \_( `. +---+ _(Back`. | 3GPP | 1982 Y------( Front )----|eNB|----( Haul )----| core | 1983 ( ` .Haul ) +---+ ( ` . ) ) | netw | 1984 /`--(___.-' \ `--(___.-' +------+ 1985 Y_/ / \.--. \ 1986 Y_/ _( Mid`. \ 1987 ( Haul ) \ 1988 ( ` . ) ) \ 1989 `--(___.-'\_____+---+ (small cell sites) 1990 \ |SCe|__Y 1991 +---+ +---+ 1992 Y__|eNB|__Y 1993 +---+ 1994 Y_/ \_Y ("local" radios) 1996 Figure 7: Generic 3GPP-based Cellular Network Architecture 1998 6.1.2. Delay Constraints 2000 The available processing time for Fronthaul networking overhead is 2001 limited to the available time after the baseband processing of the 2002 radio frame has completed. For example in Long Term Evolution (LTE) 2003 radio, processing of a radio frame is allocated 3ms but typically the 2004 processing uses most of it, allowing only a small fraction to be used 2005 by the Fronthaul network (e.g. up to 250us one-way delay, though the 2006 existing spec ([NGMN-fronth]) supports delay only up to 100us). This 2007 ultimately determines the distance the remote radio heads can be 2008 located from the base stations (e.g., 100us equals roughly 20 km of 2009 optical fiber-based transport). Allocation options of the available 2010 time budget between processing and transport are under heavy 2011 discussions in the mobile industry. 2013 For packet-based transport the allocated transport time (e.g. CPRI 2014 would allow for 100us delay [CPRI]) is consumed by all nodes and 2015 buffering between the remote radio head and the baseband processing 2016 unit, plus the distance-incurred delay. 2018 The baseband processing time and the available "delay budget" for the 2019 fronthaul is likely to change in the forthcoming "5G" due to reduced 2020 radio round trip times and other architectural and service 2021 requirements [NGMN]. 2023 [METIS] documents the fundamental challenges as well as overall 2024 technical goals of the future 5G mobile and wireless system as the 2025 starting point. These future systems should support much higher data 2026 volumes and rates and significantly lower end-to-end latency for 100x 2027 more connected devices (at similar cost and energy consumption levels 2028 as today's system). 2030 For Midhaul connections, delay constraints are driven by Inter-Site 2031 radio functions like Coordinated Multipoint Processing (CoMP, see 2032 [CoMP]). CoMP reception and transmission is a framework in which 2033 multiple geographically distributed antenna nodes cooperate to 2034 improve the performance of the users served in the common cooperation 2035 area. The design principal of CoMP is to extend the current single- 2036 cell to multi-UE (User Equipment) transmission to a multi-cell-to- 2037 multi-UEs transmission by base station cooperation. 2039 CoMP has delay-sensitive performance parameters, which are "midhaul 2040 latency" and "CSI (Channel State Information) reporting and 2041 accuracy". The essential feature of CoMP is signaling between eNBs, 2042 so Midhaul latency is the dominating limitation of CoMP performance. 2043 Generally, CoMP can benefit from coordinated scheduling (either 2044 distributed or centralized) of different cells if the signaling delay 2045 between eNBs is within 1-10ms. This delay requirement is both rigid 2046 and absolute because any uncertainty in delay will degrade the 2047 performance significantly. 2049 Inter-site CoMP is one of the key requirements for 5G and is also a 2050 near-term goal for the current 4.5G network architecture. 2052 6.1.3. Time Synchronization Constraints 2054 Fronthaul time synchronization requirements are given by [TS25104], 2055 [TS36104], [TS36211], and [TS36133]. These can be summarized for the 2056 current 3GPP LTE-based networks as: 2058 Delay Accuracy: 2059 +-8ns (i.e. +-1/32 Tc, where Tc is the UMTS Chip time of 1/3.84 2060 MHz) resulting in a round trip accuracy of +-16ns. The value is 2061 this low to meet the 3GPP Timing Alignment Error (TAE) measurement 2062 requirements. 2064 Timing Alignment Error: 2065 Timing Alignment Error (TAE) is problematic to Fronthaul networks 2066 and must be minimized. If the transport network cannot guarantee 2067 low enough TAE then additional buffering has to be introduced at 2068 the edges of the network to buffer out the jitter. Buffering is 2069 not desirable as it reduces the total available delay budget. 2070 Packet Delay Variation (PDV) requirements can be derived from TAE 2071 for packet based Fronthaul networks. 2073 * For multiple input multiple output (MIMO) or TX diversity 2074 transmissions, at each carrier frequency, TAE shall not exceed 2075 65 ns (i.e. 1/4 Tc). 2077 * For intra-band contiguous carrier aggregation, with or without 2078 MIMO or TX diversity, TAE shall not exceed 130 ns (i.e. 1/2 2079 Tc). 2081 * For intra-band non-contiguous carrier aggregation, with or 2082 without MIMO or TX diversity, TAE shall not exceed 260 ns (i.e. 2083 one Tc). 2085 * For inter-band carrier aggregation, with or without MIMO or TX 2086 diversity, TAE shall not exceed 260 ns. 2088 Transport link contribution to radio frequency error: 2089 +-2 PPB. This value is considered to be "available" for the 2090 Fronthaul link out of the total 50 PPB budget reserved for the 2091 radio interface. Note: the reason that the transport link 2092 contributes to radio frequency error is as follows. The current 2093 way of doing Fronthaul is from the radio unit to remote radio head 2094 directly. The remote radio head is essentially a passive device 2095 (without buffering etc.) The transport drives the antenna 2096 directly by feeding it with samples and everything the transport 2097 adds will be introduced to radio as-is. So if the transport 2098 causes additional frequency error that shows immediately on the 2099 radio as well. 2101 The above listed time synchronization requirements are difficult to 2102 meet with point-to-point connected networks, and more difficult when 2103 the network includes multiple hops. It is expected that networks 2104 must include buffering at the ends of the connections as imposed by 2105 the jitter requirements, since trying to meet the jitter requirements 2106 in every intermediate node is likely to be too costly. However, 2107 every measure to reduce jitter and delay on the path makes it easier 2108 to meet the end-to-end requirements. 2110 In order to meet the timing requirements both senders and receivers 2111 must remain time synchronized, demanding very accurate clock 2112 distribution, for example support for IEEE 1588 transparent clocks in 2113 every intermediate node. 2115 In cellular networks from the LTE radio era onward, phase 2116 synchronization is needed in addition to frequency synchronization 2117 ([TS36300], [TS23401]). 2119 6.1.4. Transport Loss Constraints 2121 Fronthaul and Midhaul networks assume almost error-free transport. 2122 Errors can result in a reset of the radio interfaces, which can cause 2123 reduced throughput or broken radio connectivity for mobile customers. 2125 For packetized Fronthaul and Midhaul connections packet loss may be 2126 caused by BER, congestion, or network failure scenarios. Current 2127 tools for elminating packet loss for Fronthaul and Midhaul networks 2128 have serious challenges, for example retransmitting lost packets and/ 2129 or using forward error correction (FEC) to circumvent bit errors is 2130 practically impossible due to the additional delay incurred. Using 2131 redundant streams for better guarantees for delivery is also 2132 practically impossible in many cases due to high bandwidth 2133 requirements of Fronthaul and Midhaul networks. Protection switching 2134 is also a candidate but current technologies for the path switch are 2135 too slow to avoid reset of mobile interfaces. 2137 Fronthaul links are assumed to be symmetric, and all Fronthaul 2138 streams (i.e. those carrying radio data) have equal priority and 2139 cannot delay or pre-empt each other. This implies that the network 2140 must guarantee that each time-sensitive flow meets their schedule. 2142 6.1.5. Security Considerations 2144 Establishing time-sensitive streams in the network entails reserving 2145 networking resources for long periods of time. It is important that 2146 these reservation requests be authenticated to prevent malicious 2147 reservation attempts from hostile nodes (or accidental 2148 misconfiguration). This is particularly important in the case where 2149 the reservation requests span administrative domains. Furthermore, 2150 the reservation information itself should be digitally signed to 2151 reduce the risk of a legitimate node pushing a stale or hostile 2152 configuration into another networking node. 2154 6.2. Cellular Radio Networks Today 2156 6.2.1. Fronthaul 2158 Today's Fronthaul networks typically consist of: 2160 o Dedicated point-to-point fiber connection is common 2162 o Proprietary protocols and framings 2164 o Custom equipment and no real networking 2165 Current solutions for Fronthaul are direct optical cables or 2166 Wavelength-Division Multiplexing (WDM) connections. 2168 6.2.2. Midhaul and Backhaul 2170 Today's Midhaul and Backhaul networks typically consist of: 2172 o Mostly normal IP networks, MPLS-TP, etc. 2174 o Clock distribution and sync using 1588 and SyncE 2176 Telecommunication networks in the Mid- and Backhaul are already 2177 heading towards transport networks where precise time synchronization 2178 support is one of the basic building blocks. While the transport 2179 networks themselves have practically transitioned to all-IP packet- 2180 based networks to meet the bandwidth and cost requirements, highly 2181 accurate clock distribution has become a challenge. 2183 In the past, Mid- and Backhaul connections were typically based on 2184 Time Division Multiplexing (TDM-based) and provided frequency 2185 synchronization capabilities as a part of the transport media. 2186 Alternatively other technologies such as Global Positioning System 2187 (GPS) or Synchronous Ethernet (SyncE) are used [SyncE]. 2189 Both Ethernet and IP/MPLS [RFC3031] (and PseudoWires (PWE) [RFC3985] 2190 for legacy transport support) have become popular tools to build and 2191 manage new all-IP Radio Access Networks (RANs) 2192 [I-D.kh-spring-ip-ran-use-case]. Although various timing and 2193 synchronization optimizations have already been proposed and 2194 implemented including 1588 PTP enhancements 2195 [I-D.ietf-tictoc-1588overmpls] and [I-D.ietf-mpls-residence-time], 2196 these solution are not necessarily sufficient for the forthcoming RAN 2197 architectures nor do they guarantee the more stringent time- 2198 synchronization requirements such as [CPRI]. 2200 There are also existing solutions for TDM over IP such as [RFC5087] 2201 and [RFC4553], as well as TDM over Ethernet transports such as 2202 [RFC5086]. 2204 6.3. Cellular Radio Networks Future 2206 Future Cellular Radio Networks will be based on a mix of different 2207 xHaul networks (xHaul = front-, mid- and backhaul), and future 2208 transport networks should be able to support all of them 2209 simultaneously. It is already envisioned today that: 2211 o Not all "cellular radio network" traffic will be IP, for example 2212 some will remain at Layer 2 (e.g. Ethernet based). DetNet 2213 solutions must address all traffic types (Layer 2, Layer 3) with 2214 the same tools and allow their transport simultaneously. 2216 o All form of xHaul networks will need some form of DetNet 2217 solutions. For example with the advent of 5G some Backhaul 2218 traffic will also have DetNet requirements (e.g. traffic belonging 2219 to time-critical 5G applications). 2221 We would like to see the following in future Cellular Radio networks: 2223 o Unified standards-based transport protocols and standard 2224 networking equipment that can make use of underlying deterministic 2225 link-layer services 2227 o Unified and standards-based network management systems and 2228 protocols in all parts of the network (including Fronthaul) 2230 New radio access network deployment models and architectures may 2231 require time- sensitive networking services with strict requirements 2232 on other parts of the network that previously were not considered to 2233 be packetized at all. Time and synchronization support are already 2234 topical for Backhaul and Midhaul packet networks [MEF] and are 2235 becoming a real issue for Fronthaul networks also. Specifically in 2236 Fronthaul networks the timing and synchronization requirements can be 2237 extreme for packet based technologies, for example, on the order of 2238 sub +-20 ns packet delay variation (PDV) and frequency accuracy of 2239 +0.002 PPM [Fronthaul]. 2241 The actual transport protocols and/or solutions to establish required 2242 transport "circuits" (pinned-down paths) for Fronthaul traffic are 2243 still undefined. Those are likely to include (but are not limited 2244 to) solutions directly over Ethernet, over IP, and using MPLS/ 2245 PseudoWire transport. 2247 Even the current time-sensitive networking features may not be 2248 sufficient for Fronthaul traffic. Therefore, having specific 2249 profiles that take the requirements of Fronthaul into account is 2250 desirable [IEEE8021CM]. 2252 Interesting and important work for time-sensitive networking has been 2253 done for Ethernet [TSNTG], which specifies the use of IEEE 1588 time 2254 precision protocol (PTP) [IEEE1588] in the context of IEEE 802.1D and 2255 IEEE 802.1Q. [IEEE8021AS] specifies a Layer 2 time synchronizing 2256 service, and other specifications such as IEEE 1722 [IEEE1722] 2257 specify Ethernet-based Layer-2 transport for time-sensitive streams. 2259 New promising work seeks to enable the transport of time-sensitive 2260 fronthaul streams in Ethernet bridged networks [IEEE8021CM]. 2262 Analogous to IEEE 1722 there is an ongoing standardization effort to 2263 define the Layer-2 transport encapsulation format for transporting 2264 radio over Ethernet (RoE) in the IEEE 1904.3 Task Force [IEEE19043]. 2266 All-IP RANs and xHhaul networks would benefit from time 2267 synchronization and time-sensitive transport services. Although 2268 Ethernet appears to be the unifying technology for the transport, 2269 there is still a disconnect providing Layer 3 services. The protocol 2270 stack typically has a number of layers below the Ethernet Layer 2 2271 that shows up to the Layer 3 IP transport. It is not uncommon that 2272 on top of the lowest layer (optical) transport there is the first 2273 layer of Ethernet followed one or more layers of MPLS, PseudoWires 2274 and/or other tunneling protocols finally carrying the Ethernet layer 2275 visible to the user plane IP traffic. 2277 While there are existing technologies to establish circuits through 2278 the routed and switched networks (especially in MPLS/PWE space), 2279 there is still no way to signal the time synchronization and time- 2280 sensitive stream requirements/reservations for Layer-3 flows in a way 2281 that addresses the entire transport stack, including the Ethernet 2282 layers that need to be configured. 2284 Furthermore, not all "user plane" traffic will be IP. Therefore, the 2285 same solution also must address the use cases where the user plane 2286 traffic is a different layer, for example Ethernet frames. 2288 There is existing work describing the problem statement 2289 [I-D.finn-detnet-problem-statement] and the architecture 2290 [I-D.finn-detnet-architecture] for deterministic networking (DetNet) 2291 that targets solutions for time-sensitive (IP/transport) streams with 2292 deterministic properties over Ethernet-based switched networks. 2294 6.4. Cellular Radio Networks Asks 2296 A standard for data plane transport specification which is: 2298 o Unified among all xHauls 2300 o Deployed in a highly deterministic network environment 2302 A standard for data flow information models that are: 2304 o Aware of the time sensitivity and constraints of the target 2305 networking environment 2307 o Aware of underlying deterministic networking services (e.g., on 2308 the Ethernet layer) 2310 7. Industrial M2M 2312 7.1. Use Case Description 2314 Industrial Automation in general refers to automation of 2315 manufacturing, quality control and material processing. In this 2316 "machine to machine" (M2M) use case we consider machine units in a 2317 plant floor which periodically exchange data with upstream or 2318 downstream machine modules and/or a supervisory controller within a 2319 local area network. 2321 The actors of M2M communication are Programmable Logic Controllers 2322 (PLCs). Communication between PLCs and between PLCs and the 2323 supervisory PLC (S-PLC) is achieved via critical control/data streams 2324 Figure 8. 2326 S (Sensor) 2327 \ +-----+ 2328 PLC__ \.--. .--. ---| MES | 2329 \_( `. _( `./ +-----+ 2330 A------( Local )-------------( L2 ) 2331 ( Net ) ( Net ) +-------+ 2332 /`--(___.-' `--(___.-' ----| S-PLC | 2333 S_/ / PLC .--. / +-------+ 2334 A_/ \_( `. 2335 (Actuator) ( Local ) 2336 ( Net ) 2337 /`--(___.-'\ 2338 / \ A 2339 S A 2341 Figure 8: Current Generic Industrial M2M Network Architecture 2343 This use case focuses on PLC-related communications; communication to 2344 Manufacturing-Execution-Systems (MESs) are not addressed. 2346 This use case covers only critical control/data streams; non-critical 2347 traffic between industrial automation applications (such as 2348 communication of state, configuration, set-up, and database 2349 communication) are adequately served by currently available 2350 prioritizing techniques. Such traffic can use up to 80% of the total 2351 bandwidth required. There is also a subset of non-time-critical 2352 traffic that must be reliable even though it is not time sensitive. 2354 In this use case the primary need for deterministic networking is to 2355 provide end-to-end delivery of M2M messages within specific timing 2356 constraints, for example in closed loop automation control. Today 2357 this level of determinism is provided by proprietary networking 2358 technologies. In addition, standard networking technologies are used 2359 to connect the local network to remote industrial automation sites, 2360 e.g. over an enterprise or metro network which also carries other 2361 types of traffic. Therefore, flows that should be forwarded with 2362 deterministic guarantees need to be sustained regardless of the 2363 amount of other flows in those networks. 2365 7.2. Industrial M2M Communication Today 2367 Today, proprietary networks fulfill the needed timing and 2368 availability for M2M networks. 2370 The network topologies used today by industrial automation are 2371 similar to those used by telecom networks: Daisy Chain, Ring, Hub and 2372 Spoke, and Comb (a subset of Daisy Chain). 2374 PLC-related control/data streams are transmitted periodically and 2375 carry either a pre-configured payload or a payload configured during 2376 runtime. 2378 Some industrial applications require time synchronization at the end 2379 nodes. For such time-coordinated PLCs, accuracy of 1 microsecond is 2380 required. Even in the case of "non-time-coordinated" PLCs time sync 2381 may be needed e.g. for timestamping of sensor data. 2383 Industrial network scenarios require advanced security solutions. 2384 Many of the current industrial production networks are physically 2385 separated. Preventing critical flows from be leaked outside a domain 2386 is handled today by filtering policies that are typically enforced in 2387 firewalls. 2389 7.2.1. Transport Parameters 2391 The Cycle Time defines the frequency of message(s) between industrial 2392 actors. The Cycle Time is application dependent, in the range of 1ms 2393 - 100ms for critical control/data streams. 2395 Because industrial applications assume deterministic transport for 2396 critical Control-Data-Stream parameters (instead of defining latency 2397 and delay variation parameters) it is sufficient to fulfill the upper 2398 bound of latency (maximum latency). The underlying networking 2399 infrastructure must ensure a maximum end-to-end delivery time of 2400 messages in the range of 100 microseconds to 50 milliseconds 2401 depending on the control loop application. 2403 The bandwidth requirements of control/data streams are usually 2404 calculated directly from the bytes-per-cycle parameter of the control 2405 loop. For PLC-to-PLC communication one can expect 2 - 32 streams 2406 with packet size in the range of 100 - 700 bytes. For S-PLC to PLCs 2407 the number of streams is higher - up to 256 streams. Usually no more 2408 than 20% of available bandwidth is used for critical control/data 2409 streams. In today's networks 1Gbps links are commonly used. 2411 Most PLC control loops are rather tolerant of packet loss, however 2412 critical control/data streams accept no more than 1 packet loss per 2413 consecutive communication cycle (i.e. if a packet gets lost in cycle 2414 "n", then the next cycle ("n+1") must be lossless). After two or 2415 more consecutive packet losses the network may be considered to be 2416 "down" by the Application. 2418 As network downtime may impact the whole production system the 2419 required network availability is rather high (99,999%). 2421 Based on the above parameters we expect that some form of redundancy 2422 will be required for M2M communications, however any individual 2423 solution depends on several parameters including cycle time, delivery 2424 time, etc. 2426 7.2.2. Stream Creation and Destruction 2428 In an industrial environment, critical control/data streams are 2429 created rather infrequently, on the order of ~10 times per day / week 2430 / month. Most of these critical control/data streams get created at 2431 machine startup, however flexibility is also needed during runtime, 2432 for example when adding or removing a machine. Going forward as 2433 production systems become more flexible, we expect a significant 2434 increase in the rate at which streams are created, changed and 2435 destroyed. 2437 7.3. Industrial M2M Future 2439 We would like to see a converged IP-standards-based network with 2440 deterministic properties that can satisfy the timing, security and 2441 reliability constraints described above. Today's proprietary 2442 networks could then be interfaced to such a network via gateways or, 2443 in the case of new installations, devices could be connected directly 2444 to the converged network. 2446 7.4. Industrial M2M Asks 2448 o Converged IP-based network 2450 o Deterministic behavior (bounded latency and jitter ) 2452 o High availability (presumably through redundancy) (99.999 %) 2453 o Low message delivery time (100us - 50ms) 2455 o Low packet loss (burstless, 0.1-1 %) 2457 o Precise time synchronization accuracy (1us) 2459 o Security (e.g. prevent critical flows from being leaked between 2460 physically separated networks) 2462 8. Internet-based Applications 2464 8.1. Use Case Description 2466 There are many applications that communicate across the open Internet 2467 that could benefit from guaranteed delivery and bounded latency. The 2468 following are some representative examples. 2470 8.1.1. Media Content Delivery 2472 Media content delivery continues to be an important use of the 2473 Internet, yet users often experience poor quality audio and video due 2474 to the delay and jitter inherent in today's Internet. 2476 8.1.2. Online Gaming 2478 Online gaming is a significant part of the gaming market, however 2479 latency can degrade the end user experience. For example "First 2480 Person Shooter" (FPS) games are highly delay-sensitive. 2482 8.1.3. Virtual Reality 2484 Virtual reality (VR) has many commercial applications including real 2485 estate presentations, remote medical procedures, and so on. Low 2486 latency is critical to interacting with the virtual world because 2487 perceptual delays can cause motion sickness. 2489 8.2. Internet-Based Applications Today 2491 Internet service today is by definition "best effort", with no 2492 guarantees on delivery or bandwidth. 2494 8.3. Internet-Based Applications Future 2496 We imagine an Internet from which we will be able to play a video 2497 without glitches and play games without lag. 2499 For online gaming, the maximum round-trip delay can be 100ms and 2500 stricter for FPS gaming which can be 10-50ms. Transport delay is the 2501 dominate part with a 5-20ms budget. 2503 For VR, 1-10ms maximum delay is needed and total network budget is 2504 1-5ms if doing remote VR. 2506 Flow identification can be used for gaming and VR, i.e. it can 2507 recognize a critical flow and provide appropriate latency bounds. 2509 8.4. Internet-Based Applications Asks 2511 o Unified control and management protocols to handle time-critical 2512 data flow 2514 o Application-aware flow filtering mechanism to recognize the timing 2515 critical flow without doing 5-tuple matching 2517 o Unified control plane to provide low latency service on Layer-3 2518 without changing the data plane 2520 o OAM system and protocols which can help to provide E2E-delay 2521 sensitive service provisioning 2523 9. Use Case Common Elements 2525 Looking at the use cases collectively, the following common desires 2526 for the DetNet-based networks of the future emerge: 2528 o Open standards-based network (replace various proprietary 2529 networks, reduce cost, create multi-vendor market) 2531 o Centrally administered (though such administration may be 2532 distributed for scale and resiliency) 2534 o Integrates L2 (bridged) and L3 (routed) environments (independent 2535 of the Link layer, e.g. can be used with Ethernet, 6TiSCH, etc.) 2537 o Carries both deterministic and best-effort traffic (guaranteed 2538 end-to-end delivery of deterministic flows, deterministic flows 2539 isolated from each other and from best-effort traffic congestion, 2540 unused deterministic BW available to best-effort traffic) 2542 o Ability to add or remove systems from the network with minimal, 2543 bounded service interruption (applications include replacement of 2544 failed devices as well as plug and play) 2546 o Uses standardized data flow information models capable of 2547 expressing deterministic properties (models express device 2548 capabilities, flow properties. Protocols for pushing models from 2549 controller to devices, devices to controller) 2551 o Scalable size (long distances (many km) and short distances 2552 (within a single machine), many hops (radio repeaters, microwave 2553 links, fiber links...) and short hops (single machine)) 2555 o Scalable timing parameters and accuracy (bounded latency, 2556 guaranteed worst case maximum, minimum. Low latency, e.g. control 2557 loops may be less than 1ms, but larger for wide area networks) 2559 o High availability (99.9999 percent up time requested, but may be 2560 up to twelve 9s) 2562 o Reliability, redundancy (lives at stake) 2564 o Security (from failures, attackers, misbehaving devices - 2565 sensitive to both packet content and arrival time) 2567 10. Acknowledgments 2569 10.1. Pro Audio 2571 This section was derived from draft-gunther-detnet-proaudio-req-01. 2573 The editors would like to acknowledge the help of the following 2574 individuals and the companies they represent: 2576 Jeff Koftinoff, Meyer Sound 2578 Jouni Korhonen, Associate Technical Director, Broadcom 2580 Pascal Thubert, CTAO, Cisco 2582 Kieran Tyrrell, Sienda New Media Technologies GmbH 2584 10.2. Utility Telecom 2586 This section was derived from draft-wetterwald-detnet-utilities-reqs- 2587 02. 2589 Faramarz Maghsoodlou, Ph. D. IoT Connected Industries and Energy 2590 Practice Cisco 2592 Pascal Thubert, CTAO Cisco 2594 10.3. Building Automation Systems 2596 This section was derived from draft-bas-usecase-detnet-00. 2598 10.4. Wireless for Industrial 2600 This section was derived from draft-thubert-6tisch-4detnet-01. 2602 This specification derives from the 6TiSCH architecture, which is the 2603 result of multiple interactions, in particular during the 6TiSCH 2604 (bi)Weekly Interim call, relayed through the 6TiSCH mailing list at 2605 the IETF. 2607 The authors wish to thank: Kris Pister, Thomas Watteyne, Xavier 2608 Vilajosana, Qin Wang, Tom Phinney, Robert Assimiti, Michael 2609 Richardson, Zhuo Chen, Malisa Vucinic, Alfredo Grieco, Martin Turon, 2610 Dominique Barthel, Elvis Vogli, Guillaume Gaillard, Herman Storey, 2611 Maria Rita Palattella, Nicola Accettura, Patrick Wetterwald, Pouria 2612 Zand, Raghuram Sudhaakar, and Shitanshu Shah for their participation 2613 and various contributions. 2615 10.5. Cellular Radio 2617 This section was derived from draft-korhonen-detnet-telreq-00. 2619 10.6. Industrial M2M 2621 The authors would like to thank Feng Chen and Marcel Kiessling for 2622 their comments and suggestions. 2624 10.7. Internet Applications and CoMP 2626 This section was derived from draft-zha-detnet-use-case-00. 2628 This document has benefited from reviews, suggestions, comments and 2629 proposed text provided by the following members, listed in 2630 alphabetical order: Jing Huang, Junru Lin, Lehong Niu and Oilver 2631 Huang. 2633 11. Informative References 2635 [ACE] IETF, "Authentication and Authorization for Constrained 2636 Environments", . 2639 [bacnetip] 2640 ASHRAE, "Annex J to ANSI/ASHRAE 135-1995 - BACnet/IP", 2641 January 1999. 2643 [CCAMP] IETF, "Common Control and Measurement Plane", 2644 . 2646 [CoMP] NGMN Alliance, "RAN EVOLUTION PROJECT COMP EVALUATION AND 2647 ENHANCEMENT", NGMN Alliance NGMN_RANEV_D3_CoMP_Evaluation_ 2648 and_Enhancement_v2.0, March 2015, 2649 . 2652 [CONTENT_PROTECTION] 2653 Olsen, D., "1722a Content Protection", 2012, 2654 . 2657 [CPRI] CPRI Cooperation, "Common Public Radio Interface (CPRI); 2658 Interface Specification", CPRI Specification V6.1, July 2659 2014, . 2662 [CPRI-transp] 2663 CPRI TWG, "CPRI requirements for Ethernet Fronthaul", 2664 November 2015, 2665 . 2668 [DCI] Digital Cinema Initiatives, LLC, "DCI Specification, 2669 Version 1.2", 2012, . 2671 [DICE] IETF, "DTLS In Constrained Environments", 2672 . 2674 [EA12] Evans, P. and M. Annunziata, "Industrial Internet: Pushing 2675 the Boundaries of Minds and Machines", November 2012. 2677 [ESPN_DC2] 2678 Daley, D., "ESPN's DC2 Scales AVB Large", 2014, 2679 . 2682 [flnet] Japan Electrical Manufacturers' Association, "JEMA 1479 - 2683 English Edition", September 2012. 2685 [Fronthaul] 2686 Chen, D. and T. Mustala, "Ethernet Fronthaul 2687 Considerations", IEEE 1904.3, February 2015, 2688 . 2691 [HART] www.hartcomm.org, "Highway Addressable remote Transducer, 2692 a group of specifications for industrial process and 2693 control devices administered by the HART Foundation". 2695 [I-D.finn-detnet-architecture] 2696 Finn, N., Thubert, P., and M. Teener, "Deterministic 2697 Networking Architecture", draft-finn-detnet- 2698 architecture-03 (work in progress), March 2016. 2700 [I-D.finn-detnet-problem-statement] 2701 Finn, N. and P. Thubert, "Deterministic Networking Problem 2702 Statement", draft-finn-detnet-problem-statement-04 (work 2703 in progress), October 2015. 2705 [I-D.ietf-6tisch-6top-interface] 2706 Wang, Q. and X. Vilajosana, "6TiSCH Operation Sublayer 2707 (6top) Interface", draft-ietf-6tisch-6top-interface-04 2708 (work in progress), July 2015. 2710 [I-D.ietf-6tisch-architecture] 2711 Thubert, P., "An Architecture for IPv6 over the TSCH mode 2712 of IEEE 802.15.4", draft-ietf-6tisch-architecture-09 (work 2713 in progress), November 2015. 2715 [I-D.ietf-6tisch-coap] 2716 Sudhaakar, R. and P. Zand, "6TiSCH Resource Management and 2717 Interaction using CoAP", draft-ietf-6tisch-coap-03 (work 2718 in progress), March 2015. 2720 [I-D.ietf-6tisch-terminology] 2721 Palattella, M., Thubert, P., Watteyne, T., and Q. Wang, 2722 "Terminology in IPv6 over the TSCH mode of IEEE 2723 802.15.4e", draft-ietf-6tisch-terminology-06 (work in 2724 progress), November 2015. 2726 [I-D.ietf-ipv6-multilink-subnets] 2727 Thaler, D. and C. Huitema, "Multi-link Subnet Support in 2728 IPv6", draft-ietf-ipv6-multilink-subnets-00 (work in 2729 progress), July 2002. 2731 [I-D.ietf-mpls-residence-time] 2732 Mirsky, G., Ruffini, S., Gray, E., Drake, J., Bryant, S., 2733 and S. Sasha, "Residence Time Measurement in MPLS 2734 network", draft-ietf-mpls-residence-time-06 (work in 2735 progress), March 2016. 2737 [I-D.ietf-roll-rpl-industrial-applicability] 2738 Phinney, T., Thubert, P., and R. Assimiti, "RPL 2739 applicability in industrial networks", draft-ietf-roll- 2740 rpl-industrial-applicability-02 (work in progress), 2741 October 2013. 2743 [I-D.ietf-tictoc-1588overmpls] 2744 Davari, S., Oren, A., Bhatia, M., Roberts, P., and L. 2745 Montini, "Transporting Timing messages over MPLS 2746 Networks", draft-ietf-tictoc-1588overmpls-07 (work in 2747 progress), October 2015. 2749 [I-D.kh-spring-ip-ran-use-case] 2750 Khasnabish, B., hu, f., and L. Contreras, "Segment Routing 2751 in IP RAN use case", draft-kh-spring-ip-ran-use-case-02 2752 (work in progress), November 2014. 2754 [I-D.svshah-tsvwg-deterministic-forwarding] 2755 Shah, S. and P. Thubert, "Deterministic Forwarding PHB", 2756 draft-svshah-tsvwg-deterministic-forwarding-04 (work in 2757 progress), August 2015. 2759 [I-D.thubert-6lowpan-backbone-router] 2760 Thubert, P., "6LoWPAN Backbone Router", draft-thubert- 2761 6lowpan-backbone-router-03 (work in progress), February 2762 2013. 2764 [I-D.wang-6tisch-6top-sublayer] 2765 Wang, Q. and X. Vilajosana, "6TiSCH Operation Sublayer 2766 (6top)", draft-wang-6tisch-6top-sublayer-04 (work in 2767 progress), November 2015. 2769 [IEC61850-90-12] 2770 TC57 WG10, IEC., "IEC 61850-90-12 TR: Communication 2771 networks and systems for power utility automation - Part 2772 90-12: Wide area network engineering guidelines", 2015. 2774 [IEC62439-3:2012] 2775 TC65, IEC., "IEC 62439-3: Industrial communication 2776 networks - High availability automation networks - Part 3: 2777 Parallel Redundancy Protocol (PRP) and High-availability 2778 Seamless Redundancy (HSR)", 2012. 2780 [IEEE1588] 2781 IEEE, "IEEE Standard for a Precision Clock Synchronization 2782 Protocol for Networked Measurement and Control Systems", 2783 IEEE Std 1588-2008, 2008, 2784 . 2787 [IEEE1722] 2788 IEEE, "1722-2011 - IEEE Standard for Layer 2 Transport 2789 Protocol for Time Sensitive Applications in a Bridged 2790 Local Area Network", IEEE Std 1722-2011, 2011, 2791 . 2794 [IEEE19043] 2795 IEEE Standards Association, "IEEE 1904.3 TF", IEEE 1904.3, 2796 2015, . 2798 [IEEE802.1TSNTG] 2799 IEEE Standards Association, "IEEE 802.1 Time-Sensitive 2800 Networks Task Group", March 2013, 2801 . 2803 [IEEE802154] 2804 IEEE standard for Information Technology, "IEEE std. 2805 802.15.4, Part. 15.4: Wireless Medium Access Control (MAC) 2806 and Physical Layer (PHY) Specifications for Low-Rate 2807 Wireless Personal Area Networks". 2809 [IEEE802154e] 2810 IEEE standard for Information Technology, "IEEE standard 2811 for Information Technology, IEEE std. 802.15.4, Part. 2812 15.4: Wireless Medium Access Control (MAC) and Physical 2813 Layer (PHY) Specifications for Low-Rate Wireless Personal 2814 Area Networks, June 2011 as amended by IEEE std. 2815 802.15.4e, Part. 15.4: Low-Rate Wireless Personal Area 2816 Networks (LR-WPANs) Amendment 1: MAC sublayer", April 2817 2012. 2819 [IEEE8021AS] 2820 IEEE, "Timing and Synchronizations (IEEE 802.1AS-2011)", 2821 IEEE 802.1AS-2001, 2011, 2822 . 2825 [IEEE8021CM] 2826 Farkas, J., "Time-Sensitive Networking for Fronthaul", 2827 Unapproved PAR, PAR for a New IEEE Standard; 2828 IEEE P802.1CM, April 2015, 2829 . 2832 [IEEE8021TSN] 2833 IEEE 802.1, "The charter of the TG is to provide the 2834 specifications that will allow time-synchronized low 2835 latency streaming services through 802 networks.", 2016, 2836 . 2838 [IETFDetNet] 2839 IETF, "Charter for IETF DetNet Working Group", 2015, 2840 . 2842 [ISA100] ISA/ANSI, "ISA100, Wireless Systems for Automation", 2843 . 2845 [ISA100.11a] 2846 ISA/ANSI, "Wireless Systems for Industrial Automation: 2847 Process Control and Related Applications - ISA100.11a-2011 2848 - IEC 62734", 2011, . 2851 [ISO7240-16] 2852 ISO, "ISO 7240-16:2007 Fire detection and alarm systems -- 2853 Part 16: Sound system control and indicating equipment", 2854 2007, . 2857 [knx] KNX Association, "ISO/IEC 14543-3 - KNX", November 2006. 2859 [lontalk] ECHELON, "LonTalk(R) Protocol Specification Version 3.0", 2860 1994. 2862 [LTE-Latency] 2863 Johnston, S., "LTE Latency: How does it compare to other 2864 technologies", March 2014, 2865 . 2868 [MEF] MEF, "Mobile Backhaul Phase 2 Amendment 1 -- Small Cells", 2869 MEF 22.1.1, July 2014, 2870 . 2873 [METIS] METIS, "Scenarios, requirements and KPIs for 5G mobile and 2874 wireless system", ICT-317669-METIS/D1.1 ICT- 2875 317669-METIS/D1.1, April 2013, . 2878 [modbus] Modbus Organization, "MODBUS APPLICATION PROTOCOL 2879 SPECIFICATION V1.1b", December 2006. 2881 [net5G] Ericsson, "5G Radio Access, Challenges for 2020 and 2882 Beyond", Ericsson white paper wp-5g, June 2013, 2883 . 2885 [NGMN] NGMN Alliance, "5G White Paper", NGMN 5G White Paper v1.0, 2886 February 2015, . 2889 [NGMN-fronth] 2890 NGMN Alliance, "Fronthaul Requirements for C-RAN", March 2891 2015, . 2894 [PCE] IETF, "Path Computation Element", 2895 . 2897 [profibus] 2898 IEC, "IEC 61158 Type 3 - Profibus DP", January 2001. 2900 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2901 Requirement Levels", BCP 14, RFC 2119, 2902 DOI 10.17487/RFC2119, March 1997, 2903 . 2905 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 2906 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 2907 December 1998, . 2909 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 2910 "Definition of the Differentiated Services Field (DS 2911 Field) in the IPv4 and IPv6 Headers", RFC 2474, 2912 DOI 10.17487/RFC2474, December 1998, 2913 . 2915 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 2916 Label Switching Architecture", RFC 3031, 2917 DOI 10.17487/RFC3031, January 2001, 2918 . 2920 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 2921 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 2922 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 2923 . 2925 [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation 2926 Metric for IP Performance Metrics (IPPM)", RFC 3393, 2927 DOI 10.17487/RFC3393, November 2002, 2928 . 2930 [RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between 2931 Information Models and Data Models", RFC 3444, 2932 DOI 10.17487/RFC3444, January 2003, 2933 . 2935 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 2936 RFC 3972, DOI 10.17487/RFC3972, March 2005, 2937 . 2939 [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation 2940 Edge-to-Edge (PWE3) Architecture", RFC 3985, 2941 DOI 10.17487/RFC3985, March 2005, 2942 . 2944 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 2945 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2946 2006, . 2948 [RFC4553] Vainshtein, A., Ed. and YJ. Stein, Ed., "Structure- 2949 Agnostic Time Division Multiplexing (TDM) over Packet 2950 (SAToP)", RFC 4553, DOI 10.17487/RFC4553, June 2006, 2951 . 2953 [RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, 2954 DOI 10.17487/RFC4903, June 2007, 2955 . 2957 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 2958 over Low-Power Wireless Personal Area Networks (6LoWPANs): 2959 Overview, Assumptions, Problem Statement, and Goals", 2960 RFC 4919, DOI 10.17487/RFC4919, August 2007, 2961 . 2963 [RFC5086] Vainshtein, A., Ed., Sasson, I., Metz, E., Frost, T., and 2964 P. Pate, "Structure-Aware Time Division Multiplexed (TDM) 2965 Circuit Emulation Service over Packet Switched Network 2966 (CESoPSN)", RFC 5086, DOI 10.17487/RFC5086, December 2007, 2967 . 2969 [RFC5087] Stein, Y(J)., Shashoua, R., Insler, R., and M. Anavi, 2970 "Time Division Multiplexing over IP (TDMoIP)", RFC 5087, 2971 DOI 10.17487/RFC5087, December 2007, 2972 . 2974 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 2975 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 2976 DOI 10.17487/RFC6282, September 2011, 2977 . 2979 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 2980 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 2981 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 2982 Low-Power and Lossy Networks", RFC 6550, 2983 DOI 10.17487/RFC6550, March 2012, 2984 . 2986 [RFC6551] Vasseur, JP., Ed., Kim, M., Ed., Pister, K., Dejean, N., 2987 and D. Barthel, "Routing Metrics Used for Path Calculation 2988 in Low-Power and Lossy Networks", RFC 6551, 2989 DOI 10.17487/RFC6551, March 2012, 2990 . 2992 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 2993 Bormann, "Neighbor Discovery Optimization for IPv6 over 2994 Low-Power Wireless Personal Area Networks (6LoWPANs)", 2995 RFC 6775, DOI 10.17487/RFC6775, November 2012, 2996 . 2998 [RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using 2999 IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the 3000 Internet of Things (IoT): Problem Statement", RFC 7554, 3001 DOI 10.17487/RFC7554, May 2015, 3002 . 3004 [SRP_LATENCY] 3005 Gunther, C., "Specifying SRP Latency", 2014, 3006 . 3009 [STUDIO_IP] 3010 Mace, G., "IP Networked Studio Infrastructure for 3011 Synchronized & Real-Time Multimedia Transmissions", 2007, 3012 . 3015 [SyncE] ITU-T, "G.8261 : Timing and synchronization aspects in 3016 packet networks", Recommendation G.8261, August 2013, 3017 . 3019 [TEAS] IETF, "Traffic Engineering Architecture and Signaling", 3020 . 3022 [TS23401] 3GPP, "General Packet Radio Service (GPRS) enhancements 3023 for Evolved Universal Terrestrial Radio Access Network 3024 (E-UTRAN) access", 3GPP TS 23.401 10.10.0, March 2013. 3026 [TS25104] 3GPP, "Base Station (BS) radio transmission and reception 3027 (FDD)", 3GPP TS 25.104 3.14.0, March 2007. 3029 [TS36104] 3GPP, "Evolved Universal Terrestrial Radio Access 3030 (E-UTRA); Base Station (BS) radio transmission and 3031 reception", 3GPP TS 36.104 10.11.0, July 2013. 3033 [TS36133] 3GPP, "Evolved Universal Terrestrial Radio Access 3034 (E-UTRA); Requirements for support of radio resource 3035 management", 3GPP TS 36.133 12.7.0, April 2015. 3037 [TS36211] 3GPP, "Evolved Universal Terrestrial Radio Access 3038 (E-UTRA); Physical channels and modulation", 3GPP 3039 TS 36.211 10.7.0, March 2013. 3041 [TS36300] 3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA) 3042 and Evolved Universal Terrestrial Radio Access Network 3043 (E-UTRAN); Overall description; Stage 2", 3GPP TS 36.300 3044 10.11.0, September 2013. 3046 [TSNTG] IEEE Standards Association, "IEEE 802.1 Time-Sensitive 3047 Networks Task Group", 2013, 3048 . 3050 [UHD-video] 3051 Holub, P., "Ultra-High Definition Videos and Their 3052 Applications over the Network", The 7th International 3053 Symposium on VICTORIES Project PetrHolub_presentation, 3054 October 2014, . 3057 [WirelessHART] 3058 www.hartcomm.org, "Industrial Communication Networks - 3059 Wireless Communication Network and Communication Profiles 3060 - WirelessHART - IEC 62591", 2010. 3062 Authors' Addresses 3064 Ethan Grossman (editor) 3065 Dolby Laboratories, Inc. 3066 1275 Market Street 3067 San Francisco, CA 94103 3068 USA 3070 Phone: +1 415 645 4726 3071 Email: ethan.grossman@dolby.com 3072 URI: http://www.dolby.com 3074 Craig Gunther 3075 Harman International 3076 10653 South River Front Parkway 3077 South Jordan, UT 84095 3078 USA 3080 Phone: +1 801 568-7675 3081 Email: craig.gunther@harman.com 3082 URI: http://www.harman.com 3084 Pascal Thubert 3085 Cisco Systems, Inc 3086 Building D 3087 45 Allee des Ormes - BP1200 3088 MOUGINS - Sophia Antipolis 06254 3089 FRANCE 3091 Phone: +33 497 23 26 34 3092 Email: pthubert@cisco.com 3094 Patrick Wetterwald 3095 Cisco Systems 3096 45 Allees des Ormes 3097 Mougins 06250 3098 FRANCE 3100 Phone: +33 4 97 23 26 36 3101 Email: pwetterw@cisco.com 3102 Jean Raymond 3103 Hydro-Quebec 3104 1500 University 3105 Montreal H3A3S7 3106 Canada 3108 Phone: +1 514 840 3000 3109 Email: raymond.jean@hydro.qc.ca 3111 Jouni Korhonen 3112 Broadcom Corporation 3113 3151 Zanker Road 3114 San Jose, CA 95134 3115 USA 3117 Email: jouni.nospam@gmail.com 3119 Yu Kaneko 3120 Toshiba 3121 1 Komukai-Toshiba-cho, Saiwai-ku, Kasasaki-shi 3122 Kanagawa, Japan 3124 Email: yu1.kaneko@toshiba.co.jp 3126 Subir Das 3127 Applied Communication Sciences 3128 150 Mount Airy Road, Basking Ridge 3129 New Jersey, 07920, USA 3131 Email: sdas@appcomsci.com 3133 Yiyong Zha 3134 Huawei Technologies 3136 Email: zhayiyong@huawei.com 3138 Balazs Varga 3139 Ericsson 3140 Konyves Kalman krt. 11/B 3141 Budapest 1097 3142 Hungary 3144 Email: balazs.a.varga@ericsson.com 3145 Janos Farkas 3146 Ericsson 3147 Konyves Kalman krt. 11/B 3148 Budapest 1097 3149 Hungary 3151 Email: janos.farkas@ericsson.com 3153 Franz-Josef Goetz 3154 Siemens 3155 Gleiwitzerstr. 555 3156 Nurnberg 90475 3157 Germany 3159 Email: franz-josef.goetz@siemens.com 3161 Juergen Schmitt 3162 Siemens 3163 Gleiwitzerstr. 555 3164 Nurnberg 90475 3165 Germany 3167 Email: juergen.jues.schmitt@siemens.com