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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-21) exists of draft-ietf-netmod-yang-instance-file-format-06 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETCONF B. Lengyel 3 Internet-Draft Ericsson 4 Intended status: Standards Track A. Clemm 5 Expires: August 17, 2020 Futurewei 6 B. Claise 7 Cisco Systems, Inc. 8 February 14, 2020 10 Generic YANG-related System Capabilities and YANG-Push Notification 11 Capabilities 12 draft-ietf-netconf-notification-capabilities-11 14 Abstract 16 This document proposes two YANG modules. The module ietf-system- 17 capabilities provides a structure that can be used to specify any 18 YANG related system capability. 20 The module ietf-notification-capabilities allows a publisher to 21 specify capabilities related to "Subscription to YANG Datastores" 22 (YANG-Push). It proposes to use YANG Instance Data to document this 23 information and make it already available at implementation-time, but 24 also allow it to be reported at run-time. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on August 17, 2020. 43 Copyright Notice 45 Copyright (c) 2020 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 62 2.1. YANG-Push Notification Capabilities . . . . . . . . . . . 3 63 3. Providing System Capability Information . . . . . . . . . . . 5 64 4. System Capabilities Model . . . . . . . . . . . . . . . . . . 6 65 4.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 6 66 4.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 7 67 5. Notification Capabilities Model . . . . . . . . . . . . . . . 10 68 5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 10 69 5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 11 70 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 71 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 72 7.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 16 73 7.2. The YANG Module Names Registry . . . . . . . . . . . . . 16 74 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 75 8.1. Normative References . . . . . . . . . . . . . . . . . . 16 76 8.2. Informative References . . . . . . . . . . . . . . . . . 17 77 Appendix A. Instance data examples . . . . . . . . . . . . . . . 18 78 Appendix B. Changes between revisions . . . . . . . . . . . . . 21 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 81 1. Terminology 83 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 84 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 85 "OPTIONAL" in this document are to be interpreted as described in BCP 86 14 [RFC2119] [RFC8174] when, and only when, they appear in all 87 capitals, as shown here. 89 The terms YANG-Push, On-change subscription and Periodic subscription 90 are used as defined in [RFC8641] 92 The terms Subscriber, Publisher and Receiver are used as defined in 93 [RFC8639] 95 The term Server is used as defined in [RFC8342] 96 On-change Notification Capability: The capability of the publisher to 97 send on-change notifications for a specific datastore or a specific 98 data node. 100 Implementation-time information: Information about the publisher's or 101 server's behavior that is made available during the implementation of 102 the publisher/server, available from a source other then a running 103 server. 105 Run-time information: Information about the publisher's or server's 106 behavior that is available from the running server via management 107 protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. 109 2. Introduction 111 Systems implementing a server and/or a publisher often have 112 capabilities that are not defined by the YANG model itself. There is 113 a need to publish this capability information as it part of the 114 contract between the server and client. Examples include: maximum 115 size of data that can be stored or transferred, information about 116 counters (whether a node supports on-change telemetry), etc. Such 117 capabilities are often dependent on a vendor's implementation or the 118 available resources at deployment. Many such capabilities are 119 specific to either the complete system, individual YANG datastores or 120 specific parts of the YANG schema, or even to individual data nodes. 121 It is a goal of this document to provide a common way of representing 122 such capabilities in a format that is: 124 o vendor independent 126 o machine readable 128 o available in identical format both in implementation-time and run- 129 time 131 2.1. YANG-Push Notification Capabilities 133 A specific case where we need to specify capabilities is the YANG- 134 Push functionality. As defined in [RFC8641] a publisher may allow 135 subscribers to subscribe to updates from a datastore and subsequently 136 push such update notifications to the receiver. Notifications may be 137 sent periodically or on-change (more or less immediately after each 138 change). 140 A publisher supporting YANG-Push has a number of capabilities defined 141 in [RFC8641] that are often determined during the implementation of 142 the publisher. These include: 144 o Supported (reporting) periods for periodic subscriptions 146 o Maximum number of objects that can be sent in an update 148 o The set of datastores or data nodes for which periodic 149 notification is supported 151 Additional capabilities if the optional on-change feature is 152 supported include: 154 o Supported dampening periods for on-change subscriptions 156 o The set of datastores or data nodes for which on-change 157 notification is supported 159 Publishers have limitations in how many update notifications and how 160 many datastore node updates they can send out in a certain time- 161 period. 163 Publishers might not support periodic subscriptions to all 164 datastores. 166 In some cases, a publisher supporting on-change notifications will 167 not be able to push updates for some object types on-change. Reasons 168 for this might be that the value of the datastore node changes 169 frequently (e.g., in-octets counter), that small object changes are 170 frequent and irrelevant to the receiver (e.g., a temperature gauge 171 changing 0.1 degrees within a predetermined and acceptable range), or 172 that the implementation is not capable of on-change notification for 173 a particular object. In those cases, it will be important for 174 subscriber applications to have a way to identify which objects on- 175 change notifications are supported and for which ones not. 177 Faced with the reality that support for on-change notification does 178 not mean that such notifications will be sent for any specific data 179 node, subscriber/management applications can not rely on the on- 180 change functionality unless the subscriber has some means to identify 181 which objects on-change notifications are supported. YANG models are 182 meant to be used as an interface contract. Without identification of 183 the data nodes actually supporting on-change, this contract would be 184 incomplete. 186 Clients of a server, subscribers to a publisher need a method to 187 gather capability information. 189 Implementation-time information is needed by Network Management 190 System (NMS) implementers. A NMS implementation that wants to 191 support notifications, needs the information about on-change 192 notification capability. If the information is not documented in a 193 way available to the NMS designer, but only as instance data from the 194 network node once it is deployed, the NMS implementation will be 195 delayed, because it has to wait for the network node to be ready. In 196 addition, the assumption that all NMS implementers will have a 197 correctly configured network node available to retrieve data from is 198 an expensive proposition and may not always hold. (An NMS may need 199 to be able to handle many dozens of network node types.) Often a 200 fully functional NMS is a requirement for introducing a new network 201 node type into a network, so delaying NMS readiness effectively also 202 delays the time at which a new network node type can be introduced 203 into the network. 205 Implementation-time information is needed by system integrators. 206 When introducing a network node type into their network, operators 207 often need to integrate the node type into their own management 208 system. The NMS may have management functions that depend on on- 209 change notifications. The network operator needs to plan his 210 management practices and NMS implementation before he even decides to 211 buy the specific network node type. Moreover the decision to buy the 212 node type sometimes depends on these management possibilities. 214 Run-time information is needed: 216 o for any "purely model driven" application, e.g., a NETCONF- 217 browser. Such applications depend on reading models and 218 capabilities in run-time to support all the publisher's available 219 functionality. 221 o in case the capability might change during run-time e.g., due to 222 licensing, HW constraints etc. 224 o to check that capability information provided early, already in 225 implementation-time is indeed what the publisher implements (is 226 the supplied documentation correct?) 228 3. Providing System Capability Information 230 Capability information is represented by instance-data based on one 231 or more "capability defining YANG modules". This allows a user to 232 discover capabilities both at implementation-time and run-time. 234 o For the implementation-time use-case: Capabilities SHOULD be 235 provided by the implementer as YANG instance data files complying 236 to [I-D.ietf-netmod-yang-instance-file-format]. The file SHALL be 237 available already in implementation-time retrievable in a way that 238 does not depend on a live network node. E.g., download from 239 product website. 241 o For the run-time use-case: Capabilities SHOULD be available via 242 NETCONF [RFC6241] or RESTCONF [RFC8040] from the live server 243 (implementing the publisher) during run-time. Implementations 244 which support changing these capabilities at run-time SHOULD 245 support on-change notifications about the system-capabilities 246 container. 248 The module ietf-system-capabilities is defined to provide a structure 249 that can be used to specify any YANG related system capability. 251 The module ietf-notification-capabilities is defined to allow a 252 publisher to specify capabilities related to "Subscription to YANG 253 Datastores" (YANG-Push) augmenting ietf-system-capabilities. 255 4. System Capabilities Model 257 The module ietf-system-capabilities is defined to provide a structure 258 that can be used to specify any YANG related system capability. 260 Capability values can be specified on system/publisher level, 261 datastore level (by selecting all nodes in the datastore) or for 262 specific data nodes of a specific datastore (and their contained sub- 263 trees). Capability values specified for a specific datastore or 264 node-set override values specified on the system/publisher level. 266 This module itself does not contain any capabilities. It SHOULD be 267 used by other modules to augment-in specific capability information. 268 Every set of such capabilities SHOULD be wrapped in a container under 269 the augment statement to cleanly separate different groups of 270 capabilities. These "wrapper containers" SHALL be augmented in at 271 /sysc:system-capabilities and /sysc:system-capabilities/ 272 sysc:datastore-capabilities/sysc:per-node-capabilities. 274 Note: The solution is usable for both NMDA and non-NMDA systems. For 275 non-NMDA servers/publishers config=false data is considered as if it 276 was part of the running datastore. 278 4.1. Tree Diagram 280 The following tree diagram [RFC8340] provides an overview of the data 281 model. 283 module: ietf-system-capabilities 284 +--ro system-capabilities 285 +--ro datastore-capabilities* [datastore] 286 +--ro datastore -> /yanglib:yang-library/datastore/name 287 +--ro per-node-capabilities* [] 288 +--ro (node-selection)? 289 +--:(node-selector) 290 +--ro node-selector? nacm:node-instance-identifier 292 4.2. YANG Module 294 file "ietf-system-capabilities@2020-02-14.yang" 296 module ietf-system-capabilities { 297 yang-version 1.1; 298 namespace 299 "urn:ietf:params:xml:ns:yang:ietf-system-capabilities"; 300 prefix sysc; 302 import ietf-netconf-acm { prefix nacm; } 304 import ietf-yang-library { 305 prefix yanglib; 306 description "Revision 2019-01-04 or a 307 revision derived from it is REQUIRED."; 308 } 310 organization 311 "IETF NETCONF (Network Configuration) Working Group"; 312 contact 313 "WG Web: 314 WG List: 316 Editor: Balazs Lengyel 317 "; 318 description 319 "This module specifies a module intended to contain system 320 capabilities. System capabilities may include capabilities of a 321 NETCONF or RESTCONF server or a notification publisher. 323 This module does not contain any specific capabilities it only 324 provides a structure where containers containing the actual 325 capabilities should be augmented in. 327 Capability values can be specified on system level, 328 datastore level (by selecting all nodes in the datastore) or 329 for specific data nodes of a specific datastore (and their 330 contained sub-trees). 332 Capability values specified for a specific datastore or 333 node-set override values specified on the system/publisher level. 335 To find a capability value for a specific data node in a 336 specific datastore the user SHALL 337 1) search for a datastore-capabilities list entry for 338 the specific datastore. 339 2) If the datastore entry is found within that entry process all 340 per-node-capabilities entries in the order they appear in the list. 341 The first entry that specifies the specific capability and has a 342 node-selector selecting the specific data node defines the 343 capability value. 344 3) If the capability value is not found above and the specific 345 capability is specified under the system-capabilities container 346 (outside the datastore-capabilities list) this value shall be used. 347 4) If no values are found in the previous steps the 348 system/publisher is not capable of providing a value because 349 it is unknown, the capability is changing for some reason, 350 there is no specified limit etc. In this case the 351 system's behavior is unspecified. 353 The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 354 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 355 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document 356 are to be interpreted as described in BCP 14 (RFC 2119) 357 (RFC 8174) when, and only when, they appear in all 358 capitals, as shown here. 360 Copyright (c) 2020 IETF Trust and the persons identified as 361 authors of the code. All rights reserved. 363 Redistribution and use in source and binary forms, with or 364 without modification, is permitted pursuant to, and subject 365 to the license terms contained in, the Simplified BSD License 366 set forth in Section 4.c of the IETF Trust's Legal Provisions 367 Relating to IETF Documents 368 (http://trustee.ietf.org/license-info). 370 This version of this YANG module is part of RFC XXXX 371 (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself 372 for full legal notices."; 374 revision 2020-02-14 { 375 description 376 "Initial version"; 377 reference 378 "RFC XXX: YANG-Push Notification Capabilities"; 379 } 380 container system-capabilities { 381 config false; 382 description "System capabilities. 383 Capability values specified here at the system level 384 are valid for all datastores and 385 are used when the capability is not specified on the 386 datastore level or for specific data nodes."; 388 // augmentation point for system level capabilities 390 list datastore-capabilities { 391 key datastore; 393 description "Capabilities values per datastore. 394 For non-NMDA servers/publishers config=false data is 395 considered as if it was part of the running datastore."; 397 leaf datastore { 398 type leafref { 399 path /yanglib:yang-library/yanglib:datastore/yanglib:name; 400 } 401 description "The datastore for which capabilities are defined. 402 Only individual datastores can be specified 403 e.g., ds:conventional is not allowed."; 404 } 406 list per-node-capabilities { 407 description 408 "Each list entry specifies capabilities for the selected 409 data nodes. The same capabilities apply for the data nodes 410 in the subtree below the selected nodes. 411 The system SHALL order the entries according to their 412 precedence. The order of the entries MUST NOT change unless 413 the underlying capabilities also change."; 415 choice node-selection { 416 description 417 "A method to select all or some nodes within a datastore."; 419 leaf node-selector { 420 type nacm:node-instance-identifier; 421 description 422 "Selects the data nodes for which capabilities are 423 specified. The special value '/' denotes all data nodes 424 in the datastore."; 425 } 426 } 427 // augmentation point for datastore or data node level 428 // capabilities 429 } 430 } 431 } 432 } 434 436 5. Notification Capabilities Model 438 The YANG module ietf-notification-capabilities is defined to provide 439 YANG-Push related capability information. 441 5.1. Tree Diagram 443 The following tree diagram [RFC8340] provides an overview of the data 444 model. 446 module: ietf-notification-capabilities 447 augment /sysc:system-capabilities: 448 +--ro subscription-capabilities 449 +--ro (update-period)? 450 | +--:(minimum-update-period) 451 | | +--ro minimum-update-period? uint32 452 | +--:(supported-update-period) 453 | +--ro supported-update-period* uint32 454 +--ro max-nodes-per-update? uint32 455 +--ro minimum-dampening-period? uint32 {yp:on-change}? 456 +--ro on-change-supported? notification-support 457 | {yp:on-change}? 458 +--ro periodic-notifications-supported? notification-support 459 +--ro supported-excluded-change-type* union {yp:on-change}? 460 augment /sysc:system-capabilities/sysc:datastore-capabilities/ + 461 | sysc:per-node-capabilities: 462 +--ro subscription-capabilities 463 +--ro (update-period)? 464 | +--:(minimum-update-period) 465 | | +--ro minimum-update-period? uint32 466 | +--:(supported-update-period) 467 | +--ro supported-update-period* uint32 468 +--ro max-nodes-per-update? uint32 469 +--ro minimum-dampening-period? uint32 {yp:on-change}? 470 +--ro on-change-supported? notification-support 471 | {yp:on-change}? 472 +--ro periodic-notifications-supported? notification-support 473 +--ro supported-excluded-change-type* union {yp:on-change}? 475 5.2. YANG Module 477 file "ietf-notification-capabilities@2020-02-14.yang" 479 module ietf-notification-capabilities { 480 yang-version 1.1; 481 namespace 482 "urn:ietf:params:xml:ns:yang:ietf-notification-capabilities"; 483 prefix inc; 485 import ietf-yang-push { prefix yp; } 486 import ietf-system-capabilities { prefix sysc; } 488 organization 489 "IETF NETCONF (Network Configuration) Working Group"; 490 contact 491 "WG Web: 492 WG List: 494 Editor: Balazs Lengyel 495 "; 496 description 497 "This module specifies YANG-Push related publisher capabilities. 499 The module contains 500 - specification of which data nodes support on-change or periodic 501 notifications. 502 - capabilities related to the throughput of notification data the 503 publisher can support. (Note that for a specific subscription 504 the publisher MAY still allow only longer periods or smaller 505 updates depending on e.g., actual load conditions.) 507 Capability values can be specified on system/publisher level, 508 datastore level or for specific data nodes of a specific datastore 509 (and their contained sub-trees), as defined in the 510 ietf-system-capabilities module. 512 If, different data nodes covered by a single subscription 513 have different values for a specific capability, then using values 514 that are only acceptable for some of these data nodes, but not for 515 others, may result in the rejection of the subscription. 517 The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 518 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 519 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document 520 are to be interpreted as described in BCP 14 (RFC 2119) 521 (RFC 8174) when, and only when, they appear in all 522 capitals, as shown here. 524 Copyright (c) 2020 IETF Trust and the persons identified as 525 authors of the code. All rights reserved. 527 Redistribution and use in source and binary forms, with or 528 without modification, is permitted pursuant to, and subject 529 to the license terms contained in, the Simplified BSD License 530 set forth in Section 4.c of the IETF Trust's Legal Provisions 531 Relating to IETF Documents 532 (http://trustee.ietf.org/license-info). 534 This version of this YANG module is part of RFC XXXX 535 (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself 536 for full legal notices."; 538 revision 2020-02-14 { 539 description 540 "Initial version"; 541 reference 542 "RFC XXX: YANG-Push Notification Capabilities"; 543 } 545 grouping subscription-capabilities { 546 description "Capabilities related to YANG-Push subscriptions 547 and notifications"; 549 container subscription-capabilities { 550 description "Capabilities related to YANG-Push subscriptions 551 and notifications"; 553 typedef notification-support { 554 type bits { 555 bit config-changes { 556 description "The publisher is capable of sending 557 notifications for config=true nodes for the relevant 558 scope and subscription type." ; 559 } 560 bit state-changes { 561 description "The publisher is capable of sending 562 notifications for config=false nodes for the relevant 563 scope and subscription type." ; 564 } 565 } 566 description "Type for defining whether on-change or 567 periodic notifications are supported for none, only 568 config=true, only config=false or all data nodes. 570 If the bit config-changes or state-changes is set 571 for a datastore or a set of nodes that does not contain 572 nodes with the indicated config value, 573 this has no effect, as if no support was declared. 574 E.g. indicating support for state-changes for 575 a candidate datastore has no effect."; 576 } 578 choice update-period { 579 description "Supported update period value or values for 580 periodic subscriptions."; 581 leaf minimum-update-period { 582 type uint32; 583 units "centiseconds"; 584 description "Indicates the minimal update period that is 585 supported for a periodic subscription. 586 A subscription request to the selected data 587 nodes with a smaller period than what this leaf specifies 588 will result in a 'period-unsupported' error."; 589 reference 590 "The period leaf in RFC 8641 ietf-yang-push YANG module"; 591 } 593 leaf-list supported-update-period { 594 type uint32; 595 units "centiseconds"; 596 description "Supported update period values for a 597 periodic subscription. 598 A subscription request to the selected data nodes with a 599 period not included in the leaf-list will result in a 600 'period-unsupported' error."; 601 reference 602 "The period leaf in RFC 8641 ietf-yang-push YANG module"; 603 } 604 } 606 leaf max-nodes-per-update { 607 type uint32 { 608 range "1..max"; 609 } 610 description 611 "Maximum number of data nodes that can be sent 612 in an update. The publisher MAY support more data nodes, 613 but SHOULD support at least this number."; 614 } 616 leaf minimum-dampening-period { 617 if-feature yp:on-change; 618 type uint32; 619 units "centiseconds"; 620 description 621 "The minimum dampening period supported for on-change 622 subscriptions for the selected data nodes."; 623 } 625 leaf on-change-supported { 626 if-feature yp:on-change; 627 type notification-support; 628 description 629 "Specifies whether the publisher is capable of 630 sending on-change notifications for the selected 631 data store or data nodes and the subtree below them."; 632 } 634 leaf periodic-notifications-supported { 635 type notification-support; 636 description 637 "Specifies whether the publisher is capable of 638 sending periodic notifications for the selected 639 data store or data nodes and the subtree below them."; 640 } 642 leaf-list supported-excluded-change-type { 643 if-feature yp:on-change; 644 type union { 645 type enumeration { 646 enum none { 647 value -2 ; 648 description "None of the change types can be excluded."; 649 } 650 enum all { 651 value -1 ; 652 description 653 "Any combination of change types can be excluded."; 654 } 655 } 656 type yp:change-type; 657 } 658 description "The change types that can be excluded in 659 YANG-Push subscriptions."; 660 } 661 } 662 } 664 augment /sysc:system-capabilities { 665 description "Add system level capabilities"; 666 uses subscription-capabilities { 667 refine subscription-capabilities/supported-excluded-change-type { 668 default none; 669 } 670 } 671 } 673 augment "/sysc:system-capabilities/sysc:datastore-capabilities" + 674 "/sysc:per-node-capabilities" { 675 description "Add datastore and node level capabilities"; 676 uses subscription-capabilities { 677 refine subscription-capabilities/supported-excluded-change-type { 678 default none; 679 } 680 } 681 } 682 } 684 686 6. Security Considerations 688 The YANG modules specified in this document define a schema for data 689 that is designed to be accessed via network management protocols such 690 as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer 691 is the secure transport layer, and the mandatory-to-implement secure 692 transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer 693 is HTTPS, and the mandatory-to-implement secure transport is TLS 694 [RFC8446]. 696 The Network Configuration Access Control Model (NACM) [RFC8341] 697 provides the means to restrict access for particular NETCONF or 698 RESTCONF users to a preconfigured subset of all available NETCONF or 699 RESTCONF protocol operations and content. 701 All protocol-accessible data nodes are read-only and cannot be 702 modified. The data in these modules is not security sensitive. 703 Access control may be configured, to avoid exposing the read-only 704 data. 706 When that data is in file format, data should be protected against 707 modification or unauthorized access using normal file handling 708 mechanisms. 710 7. IANA Considerations 711 7.1. The IETF XML Registry 713 This document registers two URIs in the IETF XML registry [RFC3688]. 714 Following the format in [RFC3688], the following registrations are 715 requested: 717 URI: urn:ietf:params:xml:ns:yang:ietf-system-capabilities 718 Registrant Contact: The NETCONF WG of the IETF. 719 XML: N/A, the requested URI is an XML namespace. 721 URI: urn:ietf:params:xml:ns:yang:ietf-notification-capabilities 722 Registrant Contact: The NETCONF WG of the IETF. 723 XML: N/A, the requested URI is an XML namespace. 725 7.2. The YANG Module Names Registry 727 This document registers two YANG modules in the YANG Module Names 728 registry. Following the format in [RFC7950], the the following 729 registrations are requested: 731 name: ietf-system-capabilities 732 namespace: urn:ietf:params:xml:ns:yang:ietf-system-capabilities 733 prefix: sysc 734 reference: RFC XXXX 736 name: ietf-notification-capabilities 737 namespace: urn:ietf:params:xml:ns:yang:ietf-notification-capabilities 738 prefix: inc 739 reference: RFC XXXX 741 8. References 743 8.1. Normative References 745 [I-D.ietf-netmod-yang-instance-file-format] 746 Lengyel, B. and B. Claise, "YANG Instance Data File 747 Format", draft-ietf-netmod-yang-instance-file-format-06 748 (work in progress), December 2019. 750 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 751 and A. Bierman, Ed., "Network Configuration Protocol 752 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 753 . 755 [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure 756 Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, 757 . 759 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 760 RFC 7950, DOI 10.17487/RFC7950, August 2016, 761 . 763 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 764 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 765 . 767 [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., 768 and R. Wilton, "Network Management Datastore Architecture 769 (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, 770 . 772 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 773 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 774 . 776 [RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, 777 E., and A. Tripathy, "Subscription to YANG Notifications", 778 RFC 8639, DOI 10.17487/RFC8639, September 2019, 779 . 781 [RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications 782 for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, 783 September 2019, . 785 8.2. Informative References 787 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 788 Requirement Levels", BCP 14, RFC 2119, 789 DOI 10.17487/RFC2119, March 1997, 790 . 792 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 793 DOI 10.17487/RFC3688, January 2004, 794 . 796 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 797 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 798 May 2017, . 800 [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", 801 BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, 802 . 804 [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration 805 Access Control Model", STD 91, RFC 8341, 806 DOI 10.17487/RFC8341, March 2018, 807 . 809 Appendix A. Instance data examples 811 The following example is instance-data describing the notification 812 capabilities of a hypothetical "acme-switch". The switch implements 813 the running, candidate and operational datastores. Every change can 814 be reported on-change from running, nothing from candidate and all 815 config=false data from operational. Periodic subscriptions are 816 supported for running and operational, but not for candidate. 818 819 821 acme-switch-notification-capabilities 822 1 823 824 ietf-system-capabilities@2020-02-14 825 ietf-notification-capabilities@2020-02-14 826 827 828 Notification capabilities of acme-switch. 829 Acme-switch implements the running, candidate and operational 830 datastores. Every change can be reported on-change from running, 831 nothing from candidate and all config=false data from operational. 832 Periodic subscriptions are supported for running and 833 operational, but not for candidate. 834 835 836 841 842 500 843 2000 844 100 845 846 config-changes state-changes 847 848 849 850 ds:operational 851 852 / 853 854 855 state-changes 856 857 858 859 860 861 ds:candidate 862 863 / 864 865 866 867 868 869 870 871 ds:running 872 873 / 874 875 876 config-changes 877 878 879 880 881 882 883 885 Figure 1: Notification Capabilities with datastore level settings 887 The following is the instance-data describing the notification 888 capabilities of a hypothetical "acme-router". The router implements 889 the running, and operational datastores. Every change can be 890 reported on-change from running, but only config=true nodes and some 891 config=false data from operational. Interface statistics are not 892 reported on-change only 2 important counters. Datastore subscription 893 capabilities are not reported on-change as they never change on the 894 acme-router during run-time. 896 897 899 acme-router-notification-capabilities 900 1 901 902 ietf-system-capabilities@2020-02-14 903 ietf-notification-capabilities@2020-02-14 904 905 906 Defines the notification capabilities of an acme-router. 907 The router only has running, and operational datastores. 908 Every change can be reported on-change from running, but 909 only config=true nodes and some config=false data from operational. 910 Statistics are not reported on-change only 2 important counters, 911 for these a smaller dampening period is possible. 912 913 914 919 920 500 921 2000 922 100 923 924 config-changes state-changes 925 926 927 config-changes state-changes 928 929 930 all 931 932 933 934 ds:operational 935 936 937 /if:interfaces/if:interface[if:name='lo'] 938 939 940 941 942 943 944 945 946 /if:interfaces/if:interface/if:statistics/if:in-octets 947 948 949 10 950 951 952 state-changes 953 954 955 956 957 958 /if:interfaces/if:interface/if:statistics/if:out-octets 959 960 961 10 962 963 964 state-changes 965 966 967 968 969 970 /if:interfaces/if:interface/if:statistics 971 972 973 974 975 976 977 978 979 981 Figure 2: Notification Capabilities with data node specific settings 983 Appendix B. Changes between revisions 985 v10 - v11 987 o Updated examples 989 o Updated typedef notification-support 991 v09 - v10 993 o Removed description text from imports about the need for 994 implementing the imported module. 996 o Changed notification-support to bits with shorter names 998 o Assigned enum values to supported-excluded-change-type 1000 o Made node-selector a choice to allow for future alternative 1001 selection methods. 1003 o Changed precedence of per-node-capabilities entries. Precedence 1004 is now according to the position of entries in the list. 1006 v08 - v09 1008 o Split the YANG module into two: ietf-system-capabilities and ietf- 1009 notification-capabilities. Restructured/updated the draft 1010 accordingly. 1012 v07 - v08 1014 o Prepared the YANG model to include other non-YANG-Push related 1015 capabilities. 1017 o Renamed the top level container to system-capabilities 1019 o Added a container subscription-capabilities to the grouping 1020 subscription-capabilities to contain all subscription related 1021 capabilities 1023 o Updated examples according to draft-ietf-netmod-yang-instance- 1024 file-format-06. 1026 v06 - v07 1028 o Updated examples according to draft-ietf-netmod-yang-instance- 1029 file-format-05. 1031 v05 - v06 1033 o Providing the capability data is only a "SHOULD" recommendation. 1034 Some reviewers wanted MUST some wanted much less. 1036 o The YANG module import statements now indicate the imported 1037 modules that must be implemented not just available as import as 1038 requested by the YangDoctors review. 1040 v04 - v05 1042 o Added new capabilities periodic-notifications-supported and 1043 supported-excluded-change-type. 1045 o Restructured YANG module to make the node-selector's usage similar 1046 to how NACM uses it: "/" means the whole datastore. 1048 o Small corrections, spelling, rewording 1050 o Replaced the term server with the term publisher except in cases 1051 where we speak about datastores and functionality based on get, 1052 getconfig operations. In this latter case it is really the server 1053 functionality that is discussed 1055 v03 - v04 1057 o Clarified recommended support for on-change notifications about 1058 the datastore-subscription-capabilities. 1060 v02 - v03 1062 o Allow throughput related capabilities to be defined on top, 1063 datastore or data node level. Described that specific capability 1064 values always override generic ones. 1066 o Indicate that non-NMDA servers can also use this model. 1068 o Updated according to draft-ietf-netmod-yang-instance-file- 1069 format-04 1071 v01 - v02 1073 o Added instance data examples 1075 o On-change capability can be defined per datastore 1077 o Added "if-feature yp:on-change" where relevant 1079 o Unified units used 1081 v00 - v01 1083 o Add more capabilities: minimum period, supported period max-number 1084 of objects, min dampening period, dampening supported 1086 Authors' Addresses 1087 Balazs Lengyel 1088 Ericsson 1089 Magyar Tudosok korutja 11 1090 1117 Budapest 1091 Hungary 1093 Email: balazs.lengyel@ericsson.com 1095 Alexander Clemm 1096 Futurewei 1097 2330 Central Expressway 1098 Santa Clara, CA 95050 1099 USA 1101 Email: ludwig@clemm.org 1103 Benoit Claise 1104 Cisco Systems, Inc. 1105 De Kleetlaan 6a b1 1106 1831 Diegem 1107 Belgium 1109 Email: bclaise@cisco.com