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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) ** Obsolete normative reference: RFC 6536 (Obsoleted by RFC 8341) == Outdated reference: A later version (-15) exists of draft-ietf-netconf-https-notif-01 == Outdated reference: A later version (-08) exists of draft-ietf-netconf-notification-messages-07 Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). 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: May 7, 2020 E. Voit 6 Cisco Systems 7 A. Clemm 8 Futurewai 9 November 4, 2019 11 Subscription to Multiple Stream Originators 12 draft-zhou-netconf-multi-stream-originators-10 14 Abstract 16 This document describes the distributed data export mechanism that 17 allows multiple data streams to be managed by using a single 18 subscription. Specifically, device can decide to decompse one 19 subscription into multiple subscriptions to the line-cards. So that 20 each line-card can directly push data to the collector without 21 passing through a broker for internal consolidation. And the device 22 can indicate the subscription decomposition result to the receiver to 23 check the data integrity. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in RFC 2119 [RFC2119]. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at https://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on May 7, 2020. 48 Copyright Notice 50 Copyright (c) 2019 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (https://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 2. Data Collection from Devices with Main-board and Line-cards . 3 67 3. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 4 68 4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 5 69 5. Subscription Decomposition . . . . . . . . . . . . . . . . . 7 70 6. Publication Composition . . . . . . . . . . . . . . . . . . . 8 71 7. Subscription State Change Notifications . . . . . . . . . . . 9 72 8. Publisher Configurations . . . . . . . . . . . . . . . . . . 9 73 9. YANG Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 9 74 10. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 10 75 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 76 12. Transport Considerations . . . . . . . . . . . . . . . . . . 12 77 13. Security Considerations . . . . . . . . . . . . . . . . . . . 12 78 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 79 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 80 15.1. Normative References . . . . . . . . . . . . . . . . . . 13 81 15.2. Informative References . . . . . . . . . . . . . . . . . 14 82 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 15 83 A.1. Dynamic Subscription . . . . . . . . . . . . . . . . . . 15 84 A.2. Configured Subscription . . . . . . . . . . . . . . . . . 18 85 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 20 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 88 1. Introduction 90 Streaming telemetry refers to sending a continuous stream of 91 operational data from a device to a remote receiver. This provides 92 an ability to monitor a network from remote and to provide network 93 analytics. Devices generate telemetry data and push that data to a 94 collector for further analysis. By streaming the data, much better 95 performance, finer-grained sampling, monitoring accuracy, and 96 bandwidth utilization can be achieved than with polling-based 97 alternatives. 99 Mechanisms to support subscription to event notifications have been 100 defined in[RFC8639] and [RFC8641]. The current design involves 101 subscription to a single push server. This conceptually centralized 102 model encounters efficiency limitations in cases where the data 103 sources are themselves distributed, such as line cards in a piece of 104 network equipment. In such cases, it will be a lot more efficient to 105 have each data source (e.g., each line card) originate its own stream 106 of updates, rather than requiring updates to be tunneled through a 107 central server where they are combined. What is needed is a 108 distributed mechanism that allows to directly push multiple 109 individual data substreams, without needing to first pass them 110 through an additional processing stage for internal consolidation, 111 but still allowing those substreams to be managed and controlled via 112 a single subscription. 114 This document will describe such distributed data export mechanism 115 and how it can work by extending existing push mechanism. 116 Specifically, device can decide to decompse one subscription into 117 multiple subscriptions to the line-cards. So that each line-card can 118 directly push data to the collector without passing through a broker 119 for internal consolidation. And the device can indicate the 120 subscription decomposition result to the receiver to check the data 121 integrity. The proposal will focus on the scenario when data 122 collection from devices with main-board and line-cards. It could be 123 generalized to other distributed data export scenarios. 125 2. Data Collection from Devices with Main-board and Line-cards 127 For data collection from devices with main-board and line-cards, 128 existing push solutions consider only one push server typically 129 reside in the main board. As shown in the following figure, data are 130 collected from line cards and aggregate to the main board as one 131 consolidated stream. So the main board can easily become the 132 performance bottle-neck. The optimization is to apply the 133 distributed data export mechanism which can directly push data from 134 line cards to a collector. On one hand, this will reduce the cost of 135 scarce compute and memory resources on the main board for data 136 processing and assembling. On the other hand, distributed data push 137 can off-load the streaming traffic to multiple interfaces. 139 +-------------------------------------+ 140 | collector | 141 +------^-----------^-----------^------+ 142 | | | 143 | | | 144 +-------------------------------------+ 145 | | | | | 146 | | +-----+------+ | | 147 | | | main board | | | 148 | | +--^-----^---+ | | 149 | | | | | | 150 | | +---+ +---+ | | 151 | | | | | | 152 | +----+----+---+ +---+----+----+ | 153 | | line card 1 | | line card 2 | | 154 | +-------------+ +-------------+ | 155 | device | 156 +-------------------------------------+ 158 Fig. 1 Data Collection from Devices with Main-board and Line-cards 160 3. Terminologies 162 The following terms are defined in [RFC8639] and are not redefined 163 here: 165 Subscriber 167 Publisher 169 Receiver 171 Subscription 173 In addition, this document defines the following terms: 175 Global Subscription: the Subscription requested by the subscriber. 176 It may be decomposed into multiple Component Subscriptions. 178 Component Subscription: is the Subscription that defines the data 179 from each individual telemetry source which is managed and controlled 180 by a single Publisher. 182 Global Capability: is the overall subscription capability that the 183 group of Publishers can expose to the Subscriber. 185 Component Capability: is the subscription capability that each 186 Publisher can expose to the Subscriber. 188 Master: is the Publisher that interacts with the Subscriber to deal 189 with the Global Subscription. It decomposes the Global Subscription 190 to multiple Component Subscriptions and interacts with the Agents. 192 Agent: is the Publisher that interacts with the Master to deal with 193 the Component Subscription. 195 4. Solution Overview 197 Figure 2 below shows the distributed data export framework. 199 A collector usually includes two components, 201 o the Subscriber generates the subscription instructions to express 202 what and how the collector want to receive the data; 204 o the Receiver is the target for the data publication. 206 For one subscription, there may be one to many Receivers. And the 207 Subscriber does not necessarily share the same address with the 208 Receivers. 210 In this framework, the Publisher pushes data to the Receiver 211 according to the subscription information. The Publisher has the 212 Master role and the Agent role. The Master knows all the 213 capabilities that the attached Agents and itself can provide, and 214 exposes the Global Capability to the collector. The collector cannot 215 see the Agents directly, so it will only send the Global Subscription 216 information to the Master. The Master disassembles the Global 217 Subscription to multiple Component Subscriptions, each involving data 218 from a separate telemetry source. The Component Subscriptions are 219 then distributed to the corresponding Agents. 221 When data streaming, the Publisher collects and encapsulates the 222 packets per the Component Subscription, and pushes the piece of data 223 which can serve directly to the designated data collector. The 224 collector is able to assemble many pieces of data associated with one 225 Global Subscription, and can also deduce the missing pieces of data. 227 +-----------------------------------------+ 228 | Collector |-------------+ | 229 | +------------+ | | 230 | +------------+ || Receiver | | | 231 | | Subscriber | |--------------+ | 232 | +-----^-+----+ +-----^------^ | 233 | | | | | | 234 +-----------------------------------------+ 235 Global | | Global | | 236 Capability| | Subscription | | 237 +-----------------------------------------+ 238 | | | Push | | | 239 | +--------+-v---------------+---+ | | 240 | | Publisher(Master) | | | 241 | +--------^-+-------------------+ | | 242 | | | | | 243 | | | | | 244 | Component | | Component Push | | 245 | Capability| | Subscription | | 246 | +--------+-v-------------------+ | | 247 | | Publisher(Agent) +--+ | 248 | +------------------------------+ | 249 | | 250 | Device | 251 +-----------------------------------------+ 253 Fig. 2 The Distributed Data Export Framework 255 Master and Agents may interact with each other in several ways: 257 o Agents need to have a registration or announcement handshake with 258 the Master, so the Master is aware of them and of life-cycle 259 events (such as Agent appearing and disappearing). 261 o Contracts are needed between the Master and each Agent on the 262 Component Capability, and the format for streaming data structure. 264 o The Master relays the component subscriptions to the Agents. 266 o The Agents indicate status of Component Subscriptions to the 267 Master. The status of the overall subscription is maintained by 268 the Master. The Master is also responsible for notifying the 269 subscriber in case of any problems of Component Subscriptions. 271 Any technical mechanisms or protocols used for the coordination of 272 operational information between Master and Agent is out-of-scope of 273 this document. We will need to instrument the results of this 274 coordination on the Master. 276 5. Subscription Decomposition 278 The Collector can only subscribe to the Master. This requires the 279 Master to: 281 1. expose the Global Capability that can be served by multiple 282 Publishers; 284 2. disassemble the Global Subscription to multiple Component 285 Subscriptions, and distribute them to the corresponding telemetry 286 sources; 288 3. notify on changes when portions of a subscription moving between 289 different Agents over time. 291 The Master can keep track of the mapping between the resource and the 292 corresponding location of the Publisher which commits to serve the 293 data. If a Publisher does not have external connectivity or 294 permission to export, the master MUST NOT decompose a component 295 subscription to that Publisher. In some implementations, the Global 296 Subscription can be disassembled into multiple Component 297 Subscriptions according to the Resource-Location Table, and the 298 corresponding location can be associated. The decision whether to 299 decompose a Global Subscription into multiple Component Subscriptions 300 rests with the Resource-Location Table. A Master can decide to not 301 decompose a Global Subscription at all and push a single stream to 302 the receiver, because the location information indicates the Global 303 Subscription can be served locally by the Master. Similarly, it can 304 decide to entirely decompose a Global Subscription into multiple 305 Component Subscriptions that each push their own streams, but not 306 from the Master. It can also decide to decompose the Global 307 Subscription into several Component Subscriptions and retain some 308 aspects of the Global Subscription itself, also pushing its own 309 stream. 311 Component Subscriptions belonging to the same Global Subscription 312 MUST NOT overlap. The combination of all Component Subscriptions 313 MUST cover the same range of nodes as the Global Subscription. Also, 314 the same subscription settings apply to each Component Subscription, 315 i.e., the same receivers, the same time periods, the same encodings 316 are applied to each Component Subscription per the settings of the 317 Global Subscription. 319 Each Component Subscription in effect constitutes a full-fledged 320 subscription, with the following constraints: 322 o Component subscriptions are system-controlled, i.e. managed by the 323 Master, not by the subscriber. 325 o Component subscription settings such as time periods, dampening 326 periods, encodings, receivers adopt the settings of their Global 327 Subscription. 329 o The life-cycle of the Component Subscription is tied to the life- 330 cycle of the Global Subscription. Specifically, terminating/ 331 removing the Global Subscription results in termination/removal of 332 Component Subscriptions. 334 o The Component Subscriptions share the same Subscription ID as the 335 Global Subscription. 337 6. Publication Composition 339 The Publisher collects data and encapsulates the packets per the 340 Component Subscription. There are several potential encodings, 341 including XML, JSON, CBOR and GPB. The format and structure of the 342 data records are defined by the YANG schema, so that the composition 343 at the Receiver can benefit from the structured and hierarchical data 344 instance. 346 The Receiver is able to assemble many pieces of data associated with 347 one subscription, and can also deduce the missing pieces of data. 348 The Receiver recognizes data records associated with one subscription 349 according the Subscription ID [RFC8639]. Data records generated per 350 one subscription are assigned with the same Subscription ID. 352 For the periodic updates, records are produced periodically from each 353 Publisher. The message arrival time varies because of the 354 distributed nature of the publication. The Receiver assembles data 355 generated at the same time period based on the recording time 356 consisted in each data record. In this case, time synchronization is 357 required for all the Publishers. 359 Message Generator ID [I-D.ietf-netconf-notification-messages] is the 360 identifier for the process which created the notification message. 361 It's contained in every notification messages, and allows 362 disambiguation of different line cards sending the messages. This 363 document, in addition, requires the device to notify collector the 364 set of Message Generator IDs standing for the Publishers serving for 365 one Global Subscription. So that the collector can easily check the 366 integrity of the data collected from different Publishers at the same 367 time period. And the collector can deduce the Publishers which are 368 responsible for the missing pieces of data. 370 For the dynamic subscription, the output of the "establish- 371 subscription" RPC defined in [RFC8639] MUST include a list of Message 372 Generator IDs to indicate how the Global Subscription is decomposed 373 into several Component Subscriptions. 375 The "subscription-started" and "subscription-modified" notification 376 defined in [RFC8639] MUST also include a list of Message Generator 377 IDs to notify the current Publishers for the corresponding Global 378 Subscription. 380 7. Subscription State Change Notifications 382 In addition to sending event records to receivers, the Master MUST 383 also send subscription state change notifications [RFC8639] when 384 events related to subscription management have occurred. All the 385 subscription state change notifications MUST be delivered by the 386 Master. 388 When the subscription decomposition result changed, the 389 "subscription-modified" notification MUST be sent to indicate the new 390 list of Publishers. 392 8. Publisher Configurations 394 This document assumes all the Publishers are preconfigured to be able 395 to push data. The actual working Publishers are selected dynamically 396 based on the subscription decomposition result. For UDP Publishers, 397 the virtual IP address could be assigned for the publication. So all 398 the UDP Publishers on the device can use the same source IP address 399 configured, which may even not routeable. For connection based 400 Publishers, e.g., HTTPS-based transport 401 [I-D.ietf-netconf-https-notif], each Publisher MUST be able to 402 receive packets from the receivers. This document does not restrict 403 the way how the Publishers are accessible. 405 The specific configuration on transports is out of the scope of this 406 document. 408 9. YANG Tree 409 module: ietf-multiple-stream-originators 410 augment /sn:subscriptions/sn:subscription: 411 +--ro message-generator-id* string 412 augment /sn:subscription-started: 413 +--ro message-generator-id* string 414 augment /sn:subscription-modified: 415 +--ro message-generator-id* string 416 augment /sn:establish-subscription/sn:output: 417 +--ro message-generator-id* string 419 10. YANG Module 421 file "ietf-multiple-stream-originators@2019-10-12.yang" 422 module ietf-multiple-stream-originators { 423 yang-version 1.1; 424 namespace 425 "urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators"; 426 prefix mso; 427 import ietf-subscribed-notifications { 428 prefix sn; 429 } 431 organization "IETF NETCONF (Network Configuration) Working Group"; 432 contact 433 "WG Web: 434 WG List: 436 Editor: Tianran Zhou 437 439 Editor: Guangying Zheng 440 "; 442 description 443 "Defines augmentation for ietf-subscribed-notifications to enable 444 the distributed publication with single subscription. 446 Copyright (c) 2018 IETF Trust and the persons identified as authors 447 of the code. All rights reserved. 449 Redistribution and use in source and binary forms, with or without 450 modification, is permitted pursuant to, and subject to the license 451 terms contained in, the Simplified BSD License set forth in Section 452 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents 453 (https://trustee.ietf.org/license-info). 455 This version of this YANG module is part of RFC XXXX; see the RFC 456 itself for full legal notices."; 458 revision 2019-10-12 { 459 description 460 "Initial version"; 461 reference 462 "RFC XXXX: Subscription to Multiple Stream Originators"; 463 } 465 grouping message-generator-ids { 466 description 467 "Provides a reusable list of message-generator-ids."; 469 leaf-list message-generator-id { 470 type string; 471 config false; 472 ordered-by user; 473 description 474 "Software entity which created the message (e.g., 475 linecard 1). This field is used to notify the 476 collector the working originator."; 477 } 478 } 480 augment "/sn:subscriptions/sn:subscription" { 481 description 482 "This augmentation allows the message generators to be exposed 483 for a subscription."; 485 uses message-generator-ids; 486 } 488 augment "/sn:subscription-started" { 489 description 490 "This augmentation allows MSO specific parameters to be 491 exposed for a subscription."; 493 uses message-generator-ids; 494 } 496 augment "/sn:subscription-modified" { 497 description 498 "This augmentation allows MSO specific parameters to be 499 exposed for a subscription."; 501 uses message-generator-ids; 502 } 503 augment "/sn:establish-subscription/sn:output" { 504 description 505 "This augmentation allows MSO specific parameters to be 506 exposed for a subscription."; 508 uses message-generator-ids; 509 } 510 } 511 513 11. IANA Considerations 515 This document registers the following namespace URI in the IETF XML 516 Registry [RFC3688]: 518 URI: urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators 520 Registrant Contact: The IESG. 522 XML: N/A; the requested URI is an XML namespace. 524 This document registers the following YANG module in the YANG Module 525 Names registry [RFC3688]: 527 Name: ietf-multiple-stream-originators 529 Namespace: urn:ietf:params:xml:ns:yang:ietf-multiple-stream- 530 originators 532 Prefix: mso 534 Reference: RFC XXXX 536 12. Transport Considerations 538 The distributed data export mechanism enabled by this draft is 539 expected to generate more data than YANG-Push [RFC8641]. The large 540 amount of data may congest the network and impact other network 541 business. In this case, the collector may also not be able to accept 542 all the data. So the congestion control method is required for any 543 transport that is going to implement the solution proposed in this 544 document. 546 13. Security Considerations 548 The YANG module specified in this document defines a schema for data 549 that is designed to be accessed via network management protocols such 550 as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer 551 is the secure transport layer, and the mandatory-to-implement secure 552 transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer 553 is HTTPS, and the mandatory-to-implement secure transport is TLS 554 [RFC5246]. 556 The NETCONF Access Control Model (NACM) [RFC6536] provides the means 557 to restrict access for particular NETCONF or RESTCONF users to a 558 preconfigured subset of all available NETCONF or RESTCONF protocol 559 operations and content. 561 The new data nodes introduced in this YANG module may be considered 562 sensitive or vulnerable in some network environments. It is thus 563 important to control read access (e.g., via get-config or 564 notification) to this data nodes. These are the subtrees and data 565 nodes and their sensitivity/vulnerability: 567 o /subscriptions/subscription/message-generator-ids 569 The entries in the two lists above will show where subscribed 570 resources might be located on the publishers. Access control MUST be 571 set so that only someone with proper access permissions has the 572 ability to access this resource. 574 Other Security Considerations is the same as those discussed in YANG- 575 Push [RFC8641]. 577 14. Acknowledgements 579 We thank Kent Watsen, Mahesh Jethanandani, Martin Bjorklund, Tim 580 Carey and Qin Wu for their constructive suggestions for improving 581 this document. 583 15. References 585 15.1. Normative References 587 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 588 Requirement Levels", BCP 14, RFC 2119, 589 DOI 10.17487/RFC2119, March 1997, 590 . 592 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 593 DOI 10.17487/RFC3688, January 2004, 594 . 596 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 597 (TLS) Protocol Version 1.2", RFC 5246, 598 DOI 10.17487/RFC5246, August 2008, 599 . 601 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 602 and A. Bierman, Ed., "Network Configuration Protocol 603 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 604 . 606 [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure 607 Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, 608 . 610 [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration 611 Protocol (NETCONF) Access Control Model", RFC 6536, 612 DOI 10.17487/RFC6536, March 2012, 613 . 615 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 616 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 617 . 619 [RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, 620 E., and A. Tripathy, "Subscription to YANG Notifications", 621 RFC 8639, DOI 10.17487/RFC8639, September 2019, 622 . 624 [RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications 625 for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, 626 September 2019, . 628 15.2. Informative References 630 [I-D.ietf-netconf-https-notif] 631 Jethanandani, M. and K. Watsen, "An HTTPS-based Transport 632 for Configured Subscriptions", draft-ietf-netconf-https- 633 notif-01 (work in progress), October 2019. 635 [I-D.ietf-netconf-notification-messages] 636 Voit, E., Birkholz, H., Bierman, A., Clemm, A., and T. 637 Jenkins, "Notification Message Headers and Bundles", 638 draft-ietf-netconf-notification-messages-07 (work in 639 progress), August 2019. 641 Appendix A. Examples 643 This appendix is non-normative. 645 A.1. Dynamic Subscription 647 Figure 3 shows a typical dynamic subscription to the device with 648 distributed data export capability. 650 +-------------+ +-------------+ +-------------+ 651 | Subscriber/ | | Publisher | | Publisher | 652 | Receiver | | (Master) | | (Agent) | 653 +-------------+ +------+------+ +------+------+ 654 | | | 655 | establish-subscription | | 656 +------------------------------>+ component | 657 | | subscription | 658 | RPC Reply: OK, id #22 +-------------->+ 659 | message generator ID [#1, #2] | | 660 +<------------------------------+ | 661 | | | 662 | notif-mesg, id #22 | | 663 | message generator ID #1 | | 664 +<------------------------------+ | 665 | | | 666 | notif-mesg, id#22 | | 667 | message generator ID #2 | | 668 +<----------------------------------------------+ 669 | | | 670 | modify-subscription (id#22) | | 671 +------------------------------>+ component | 672 | | subscription | 673 | RPC Reply: OK, id #22 +-------------->+ 674 +<------------------------------+ | 675 | | | 676 | subscription-modified, id#22 | | 677 | message generator ID [#1] | | 678 +<------------------------------+ | 679 | | | 680 | notif-mesg, id #22 | | 681 | message generator ID #1 | | 682 +<------------------------------+ | 683 | | | 684 | | | 685 + + + 687 Fig. 3 Call Flow for Dynamic Subscription 689 A "establish-subscription" RPC request as per [RFC8641] is sent to 690 the Master with a successful response. An example of using NETCONF 691 might look like: 693 695 698 700 ds:operational 701 702 704 /ex:foo 705 706 707 500 708 709 710 712 Fig. 4 "establish-subscription" Request 714 As the device is able to fully satisfy the request, the request is 715 given a subscription ID of 22. The response as in Figure 5 indicates 716 that the subscription is decomposed into two component subscriptions 717 which will be published by two message generators: #1 and #2. 719 721 723 22 724 725 731 2 732 733 735 Fig. 5 "establish-subscription" Positive RPC Response 737 Then, both Publishers send notifications with the corresponding piece 738 of data to the receiver. 740 The subscriber may invoke the "modify-subscription" RPC for a 741 subscription it previously established. The RPC has no difference to 742 the single publisher case as in [RFC8641]. Figure 6 provides an 743 example where a subscriber attempts to modify the period and 744 datastore XPath filter of a subscription using NETCONF. 746 748 752 22 753 755 ds:operational 756 757 759 /ex:bar 760 761 762 250 763 764 765 767 Fig. 6 "modify-subscription" Request 769 If the modification is successfully accepted, the "subscription- 770 modified" subscription state notification is sent to the subscriber 771 by the Master. The notification, Figure 7 for example, indicates the 772 modified subscription is decomposed into one component subscription 773 which will be published by message generator #1. 775 776 2007-09-01T10:00:00Z 777 780 22 781 783 ds:operational 784 785 787 /ex:bar 788 789 790 250 791 792 836 2007-09-01T10:00:00Z 837 840 39 841 843 ds:operational 844 845 847 /ex:foo 848 849 850 250 851 852 858 2 859 860 861 863 Fig. 9 "subscription-started" Subscription State Notification 865 Then, both Publishers send notifications with the corresponding piece 866 of data to the receiver. 868 Appendix B. Change Log 870 (To be removed by RFC editor prior to publication) 872 v01 874 o Minor revision on Subscription Decomposition 876 o Revised terminologies 878 o Removed most implementation related text 880 o Place holder of two sections: Subscription Management, and 881 Notifications on Subscription State Changes 883 v02 885 o Revised section 4 and 5. Moved them from apendix to the main 886 text. 888 v03 890 o Added a section for Terminologies. 892 o Added a section for Subscription State Change Notifications. 894 o Improved the Publication Composition section by adding a method to 895 check the integrity of the data generated from different 896 Publishers at the same time period. 898 o Revised the solution overview for a more clear description. 900 v04 902 o Added the YANG data model for the proposed augment. 904 v05 906 o Added the IANA considerations, transport considerations and 907 security considerations. 909 v06 911 o Added examples. 913 v07 915 o Removed the IoT use case. 917 o Revised examples. 919 o Add discussion on Publisher Configurations in section 8. 921 v08 923 o Cleared up the document to fix Terms, nits. 925 o Reduced internal implementation descriptions. 927 o Clarified Message Generator ID. 929 Authors' Addresses 931 Tianran Zhou 932 Huawei 933 156 Beiqing Rd., Haidian District 934 Beijing 935 China 937 Email: zhoutianran@huawei.com 939 Guangying Zheng 940 Huawei 941 101 Yu-Hua-Tai Software Road 942 Nanjing, Jiangsu 943 China 945 Email: zhengguangying@huawei.com 947 Eric Voit 948 Cisco Systems 949 United States of America 951 Email: evoit@cisco.com 953 Alexander Clemm 954 Futurewai 955 2330 Central Expressway 956 Santa Clara, California 957 United States of America 959 Email: ludwig@clemm.org