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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETCONF T. Zhou 3 Internet-Draft G. Zheng 4 Intended status: Standards Track Huawei 5 Expires: April 21, 2019 E. Voit 6 Cisco Systems 7 A. Clemm 8 Huawei 9 A. Bierman 10 YumaWorks 11 October 18, 2018 13 Subscription to Multiple Stream Originators 14 draft-zhou-netconf-multi-stream-originators-03 16 Abstract 18 This document describes the distributed data collection mechanism 19 that allows multiple data streams to be managed using a single 20 subscription. Specifically, multiple data streams are pushed 21 directly to the collector without passing through a broker for 22 internal consolidation. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 28 document are to be interpreted as described in RFC 2119 [RFC2119]. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on April 21, 2019. 47 Copyright Notice 49 Copyright (c) 2018 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3 66 2.1. Use Case 1: Data Collection from Devices with Main-board 67 and Line-cards . . . . . . . . . . . . . . . . . . . . . 3 68 2.2. Use Case 2: IoT Data Collection . . . . . . . . . . . . . 4 69 3. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 5 70 4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 6 71 5. Subscription Decomposition . . . . . . . . . . . . . . . . . 8 72 6. Publication Composition . . . . . . . . . . . . . . . . . . . 9 73 7. Subscription State Change Notifications . . . . . . . . . . . 10 74 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 75 9. Security Considerations . . . . . . . . . . . . . . . . . . . 10 76 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 77 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 78 11.1. Normative References . . . . . . . . . . . . . . . . . . 11 79 11.2. Informative References . . . . . . . . . . . . . . . . . 11 80 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 12 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 83 1. Introduction 85 Streaming telemetry refers to sending a continuous stream of 86 operational data from a device to a remote receiver. This provides 87 an ability to monitor a network from remote and to provide network 88 analytics. Devices generate telemetry data and push that data to a 89 collector for further analysis. By streaming the data, much better 90 performance, finer-grained sampling, monitoring accuracy, and 91 bandwidth utilization can be achieved than with polling-based 92 alternatives. 94 YANG-Push [I-D.ietf-netconf-yang-push] defines a transport- 95 independent subscription mechanism for datastore updates, in which a 96 subscriber can subscribe to a stream of datastore updates from a 97 server, or update provider. The current design involves subscription 98 to a single push server. This conceptually centralized model 99 encounters efficiency limitations in cases where the data sources are 100 themselves distributed, such as line cards in a piece of network 101 equipment. In such cases, it will be a lot more efficient to have 102 each data source (e.g., each line card) originate its own stream of 103 updates, rather than requiring updates to be tunneled through a 104 central server where they are combined. What is needed is a 105 distributed mechanism that allows to directly push multiple 106 individual data substreams, without needing to first pass them 107 through an additional processing stage for internal consolidation, 108 but still allowing those substreams to be managed and controlled via 109 a single subscription. 111 This document will describe such distributed data collection 112 mechanism and how it can work by extending existing YANG-Push 113 mechanism. The proposal is general enough to fit many scenarios. 115 2. Use Cases 117 2.1. Use Case 1: Data Collection from Devices with Main-board and Line- 118 cards 120 For data collection from devices with main-board and line-cards, 121 existing YANG-Push solutions consider only one push server typically 122 reside in the main board. As shown in the following figure, data are 123 collected from line cards and aggregate to the main board as one 124 consolidated stream. So the main board can easily become the 125 performance bottle-neck. The optimization is to apply the 126 distributed data collection mechanism which can directly push data 127 from line cards to a collector. On one hand, this will reduce the 128 cost of scarce compute and memory resources on the main board for 129 data processing and assembling. On the other hand, distributed data 130 push can off-load the streaming traffic to multiple interfaces. 132 +-------------------------------------+ 133 | collector | 134 +------^-----------^-----------^------+ 135 | | | 136 | | | 137 +-------------------------------------+ 138 | | | | | 139 | | +-----+------+ | | 140 | | | main board | | | 141 | | +--^-----^---+ | | 142 | | | | | | 143 | | +---+ +---+ | | 144 | | | | | | 145 | +----+----+---+ +---+----+----+ | 146 | | line card 1 | | line card 2 | | 147 | +-------------+ +-------------+ | 148 | device | 149 +-------------------------------------+ 151 Fig. 1 Data Collection from Devices with Main-board and Line-cards 153 2.2. Use Case 2: IoT Data Collection 155 In the IoT data collection scenario, as shown in the following 156 figure, collector usually cannot access to IoT nodes directly, but is 157 isolated by the border router. So the collector subscribes data from 158 the border router, and let the border router to disassemble the 159 subscription to corresponding IoT nodes. The border router is 160 typically the traffic convergence point. It's intuitive to treat the 161 border router as a broker assembling the data collected from the IoT 162 nodes and forwarding to the collector[I-D.ietf-core-coap-pubsub]. 163 However, the border router is not so powerful on data assembling as a 164 network device. It's more efficient for the collector, which may be 165 a server or even a cluster, to assemble the subscribed data if 166 possible. In this case, push servers that reside in IoT nodes can 167 stream data to the collector directly while traffic only passes 168 through the border router. 170 +-------------------------------+ 171 | collector | 172 +---^-----------^------------^--+ 173 | | | 174 | | | 175 | | | 176 | +-------+--------+ | 177 | | border router | | 178 | +----^------^----+ | 179 | | | | 180 | | | | 181 | +---+ +---+ | 182 | | | | 183 +---+----+---+ +---+----+---+ 184 | IoT node 1 | | IoT node 2 | 185 +------------+ +------------+ 187 Fig. 2 IoT Data Collection 189 3. Terminologies 191 Subscriber: generates the subscription instructions to express what 192 and how the collector want to receive the data 194 Receiver: is the target for the data publication. 196 Publisher: pushes data to the receiver according to the subscription 197 information. 199 Subscription Server: which manages capabilities that it can provide 200 to the subscriber. 202 Global Subscription: the subscription requested by the subscriber. 203 It may be decomposed into multiple Component Subscriptions. 205 Component Subscription: is the subscription that defines the data 206 from each individual telemetry source which is managed and controlled 207 by a single Subscription Server. 209 Global Capability: is the overall subscription capability that the 210 group of Publishers can expose to the Subscriber. 212 Component Capability: is the subscription capability that each 213 Publisher can expose to the Subscriber. 215 Master Publication Channel: the session between the Master Publisher 216 and the Receiver. 218 Agent Publication Channel: the session between the Agent Publisher 219 and the Receiver. 221 4. Solution Overview 223 All the use cases described in the previous section are very similar 224 on the data subscription and publication mode, hence can be 225 abstracted to the following generic distributed data collection 226 framework, as shown in the following figure. 228 A Collector usually includes two components, 230 o the Subscriber generates the subscription instructions to express 231 what and how the collector want to receive the data; 233 o the Receiver is the target for the data publication. 235 For one subscription, there may be one to many receivers. And the 236 subscriber does not necessarily share the same address with the 237 receivers. 239 In this framework, the Publisher pushes data to the receiver 240 according to the subscription information. The Publisher has the 241 Master role and the Agent role. Both the Master and the Agent 242 include the Subscription Server which actually manages capabilities 243 that it can provide to the subscriber. 245 The Master knows all the capabilities that the attached Agents and 246 itself can provide, and exposes the Global Capability to the 247 Collector. The Collector cannot see the Agents directly, so it will 248 only send the Global Subscription information to the Master. The 249 Master disassembles the Global Subscription to multiple Component 250 Subscriptions, each involving data from a separate telemetry source. 251 The Component Subscriptions are then distributed to the corresponding 252 Agents. 254 When data streaming, the Publisher collects and encapsulates the 255 packets per the Component Subscription, and pushes the piece of data 256 which can serve directly to the designated data Collector. The 257 Collector is able to assemble many pieces of data associated with one 258 Global Subscription, and can also deduce the missing pieces of data. 260 +-------------------------------------+ 261 | Collector |-------------+ | 262 | +------------+ | | 263 | +------------+ || Receiver | | | 264 | | Subscriber | |--------------+ | 265 | +-^----+-----+ +---^--------^ | 266 | | | | | | 267 +-------------------------------------+ 268 Global | |Global |Push | 269 Capability | |Subscription | | 270 +------------------------+-----+ | 271 | | | Publisher(Master) | | 272 | +--+----v------+ | | 273 | | Subscription | | | 274 | | Server | | | 275 | +--^----+------+ | | 276 | | | | | 277 +------------------------------+ | 278 Component | | Component |Push 279 Capability | | Subscription | 280 +------------------------------+ | 281 | | | Publisher(Agent) | | 282 | +--+----v------+ | | 283 | | Component | | | 284 | | Subscription | +--+ 285 | | Server | | 286 | +--------------+ | 287 +------------------------------+ 289 Fig. 3 The Generic Distributed Data Collection Framework 291 Master and Agents may interact with each other in several ways: 293 o Agents need to have a registration or announcement handshake with 294 the Master, so the Master is aware of them and of life-cycle 295 events (such as Agent appearing and disappearing). 297 o Contracts are needed between the Master and each Agent on the 298 Component Capability, and the format for streaming data structure. 300 o The Master relays the component subscriptions to the Agents. 302 o The Agents indicate status of Component Subscriptions to the 303 Master. The status of the overall subscription is maintained by 304 the Master. The Master is also responsible for notifying the 305 subscriber in case of any problems of Component Subscriptions. 307 Any technical mechanisms or protocols used for the coordination of 308 operational information between Master and Agent is out-of-scope of 309 the solution. We will need to instrument the results of this 310 coordination on the Master Node. 312 5. Subscription Decomposition 314 Since Agents are invisible to the Collector, the Collector can only 315 subscribe to the Master. This requires the Master to: 317 1. expose the Global Capability that can be served by multiple 318 Publishers; 320 2. disassemble the Global Subscription to multiple Component 321 Subscriptions, and distribute them to the corresponding telemetry 322 sources; 324 3. notify on changes when portions of a subscription moving between 325 different Agents over time. 327 To achieve the above requirements, the Master need a Global 328 Capability description which is typically the YANG [RFC7950] data 329 model. This global YANG model is provided as the contract between 330 the Master and the Collector. Each Agent associating with the Master 331 owns a local YANG model to describe the Component Capabilities which 332 it can serve as part of the Global Capability. All the Agents need 333 to know the namespace associated with the Master. 335 The Master also need a data structure, typically a Resource-Location 336 Table, to keep track of the mapping between the resource and the 337 corresponding location of the Subscription Server which commits to 338 serve the data. When a Global Subscription request arrives, the 339 Master will firstly extract the filter information from the request. 340 Consequently, according to the Resource-Location Table, the Global 341 Subscription can be disassembled into multiple Component 342 Subscriptions, and the corresponding location can be associated. 344 The decision whether to decompose a Global Subscription into multiple 345 Component Subscriptions rests with the Resource-Location Table. A 346 Master can decide to not decompose a Global Subscription at all and 347 push a single stream to the receiver, because the location 348 information indicates the Global Subscription can be served locally 349 by the Master. Similarly, it can decide to entirely decompose a 350 Global Subscription into multiple Component Subscriptions that each 351 push their own streams, but not from the Master. It can also decide 352 to decompose the Global Subscription into several Component 353 Subscriptions and retain some aspects of the Global Subscription 354 itself, also pushing its own stream. 356 Component Subscriptions belonging to the same Global Subscription 357 MUST NOT overlap. The combination of all Component Subscriptions 358 MUST cover the same range of nodes as the Global Subscription. Also, 359 the same subscription settings apply to each Component Subscription, 360 i.e., the same receivers, the same time periods, the same encodings 361 are applied to each Component Subscription per the settings of the 362 Global Subscription. 364 Each Component Subscription in effect constitutes a full-fledged 365 subscription, with the following constraints: 367 o Component subscriptions are system-controlled, i.e. managed by the 368 Master, not by the subscriber. 370 o Component subscription settings such as time periods, dampening 371 periods, encodings, receivers adopt the settings of their Global 372 Subscription. 374 o The life-cycle of the Component Subscription is tied to the life- 375 cycle of the Global Subscription. Specifically, terminating/ 376 removing the Global Subscription results in termination/removal of 377 Component Subscriptions. 379 o The Component Subscriptions share the same Subscription ID as the 380 Global Subscription. 382 6. Publication Composition 384 The Publisher collects data and encapsulates the packets per the 385 Component Subscription. There are several potential encodings, 386 including XML, JSON, CBOR and GPB. The format and structure of the 387 data records are defined by the YANG schema, so that the composition 388 at the Receiver can benefit from the structured and hierarchical data 389 instance. 391 The Receiver is able to assemble many pieces of data associated with 392 one subscription, and can also deduce the missing pieces of data. 393 The Receiver recognizes data records associated with one subscription 394 according the Subscription ID. Data records generated per one 395 subscription are assigned with the same Subscription ID. 397 For the time series data stream, records are produced periodically 398 from each stream originator. The message arrival time varies because 399 of the distributed nature of the publication. The Receiver assembles 400 data generated at the same time period based on the recording time 401 consisted in each data record. In this case, time synchronization is 402 required for all the Publishers. 404 To check the integrity of the data generated from different 405 Publishers at the same time period, the Message Generator ID 406 [I-D.ietf-netconf-notification-messages]is helpful. This requires 407 the Subscriber to know the number of Component Subscriptions which 408 the Global Subscription is decomposed to. For the dynamic 409 subscription, the reponse of the "establish-subscription" and 410 "modify-subscription" RPC defined in 411 [I-D.ietf-netconf-subscribed-notifications] can include a list of 412 Message Generator IDs to indicate how the Global Subscription is 413 decomposed into several Component Subscriptions. The "subscription- 414 started" and "subscription-modified" notification defined in 415 [I-D.ietf-netconf-subscribed-notifications] can also include a list 416 of Message Generator IDs to notify the current Publishers for the 417 corresponding Global Subscription. 419 7. Subscription State Change Notifications 421 In addition to sending event records to receivers, the Master MUST 422 also send subscription state change 423 notifications[I-D.ietf-netconf-subscribed-notifications] when events 424 related to subscription management have occurred. All the 425 subscription state change notifications MUST be delivered by the 426 Master Publication Channel which is the session between the Master 427 Publisher and the Receiver. 429 When the subscription decomposition result changed, the 430 "subscription-modified" notification will be sent to indicate the new 431 a list of Publishers. 433 8. IANA Considerations 435 TBD 437 9. Security Considerations 439 It's expected to reuse the existing secure transport layer protocols, 440 such as TLS [RFC5246] and DTLS [RFC6347], to secure the telemetry 441 stream. 443 10. Acknowledgements 445 TBD 447 11. References 448 11.1. Normative References 450 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 451 Requirement Levels", BCP 14, RFC 2119, 452 DOI 10.17487/RFC2119, March 1997, 453 . 455 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 456 (TLS) Protocol Version 1.2", RFC 5246, 457 DOI 10.17487/RFC5246, August 2008, 458 . 460 [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 461 Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, 462 January 2012, . 464 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 465 RFC 7950, DOI 10.17487/RFC7950, August 2016, 466 . 468 11.2. Informative References 470 [I-D.ietf-core-coap-pubsub] 471 Koster, M., Keranen, A., and J. Jimenez, "Publish- 472 Subscribe Broker for the Constrained Application Protocol 473 (CoAP)", draft-ietf-core-coap-pubsub-05 (work in 474 progress), July 2018. 476 [I-D.ietf-netconf-notification-messages] 477 Voit, E., Birkholz, H., Bierman, A., Clemm, A., and T. 478 Jenkins, "Notification Message Headers and Bundles", 479 draft-ietf-netconf-notification-messages-04 (work in 480 progress), August 2018. 482 [I-D.ietf-netconf-subscribed-notifications] 483 Voit, E., Clemm, A., Prieto, A., Nilsen-Nygaard, E., and 484 A. Tripathy, "Customized Subscriptions to a Publisher's 485 Event Streams", draft-ietf-netconf-subscribed- 486 notifications-17 (work in progress), September 2018. 488 [I-D.ietf-netconf-yang-push] 489 Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen- 490 Nygaard, E., Bierman, A., and B. Lengyel, "YANG Datastore 491 Subscription", draft-ietf-netconf-yang-push-19 (work in 492 progress), September 2018. 494 Appendix A. Change Log 496 (To be removed by RFC editor prior to publication) 498 v01 500 o Minor revision on Subscription Decomposition 502 o Revised terminologies 504 o Removed most implementation related text 506 o Place holder of two sections: Subscription Management, and 507 Notifications on Subscription State Changes 509 v02 511 o Revised section 4 and 5. Moved them from apendix to the main 512 text. 514 v03 516 o Added a section for Terminologies. 518 o Added a section for Subscription State Change Notifications. 520 o Improved the Publication Composition section by adding a methed to 521 check the integrity of the data generated from different 522 Publishers at the same time period. 524 o Revised the solution overview for a more clear description. 526 Authors' Addresses 528 Tianran Zhou 529 Huawei 530 156 Beiqing Rd., Haidian District 531 Beijing 532 China 534 Email: zhoutianran@huawei.com 535 Guangying Zheng 536 Huawei 537 101 Yu-Hua-Tai Software Road 538 Nanjing, Jiangsu 539 China 541 Email: zhengguangying@huawei.com 543 Eric Voit 544 Cisco Systems 545 United States of America 547 Email: evoit@cisco.com 549 Alexander Clemm 550 Huawei 551 2330 Central Expressway 552 Santa Clara, California 553 United States of America 555 Email: alexander.clemm@huawei.com 557 Andy Bierman 558 YumaWorks 559 United States of America 561 Email: andy@yumaworks.com