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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 450 has weird spacing: '...ter-ref eve...' == Line 459 has weird spacing: '...-result sub...' == Line 465 has weird spacing: '...ntifier sub...' == Line 467 has weird spacing: '...-result sub...' == Line 470 has weird spacing: '...ntifier sub...' == (4 more instances...) -- The document date (October 2, 2017) is 1692 days in the past. Is this intentional? 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: draft-ietf-netconf-rfc6536bis has been published as RFC 8341 -- Possible downref: Normative reference to a draft: ref. 'RFC6536bis' -- Possible downref: Non-RFC (?) normative reference: ref. 'XPATH' == Outdated reference: draft-ietf-netconf-netconf-event-notifications has been published as RFC 8640 == Outdated reference: draft-ietf-netconf-restconf-notif has been published as RFC 8650 == Outdated reference: draft-ietf-netconf-yang-push has been published as RFC 8641 Summary: 2 errors (**), 0 flaws (~~), 11 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETCONF E. Voit 3 Internet-Draft Cisco Systems 4 Intended status: Standards Track A. Clemm 5 Expires: April 5, 2018 Huawei 6 A. Gonzalez Prieto 7 VMWare 8 E. Nilsen-Nygaard 9 A. Tripathy 10 Cisco Systems 11 October 2, 2017 13 Custom Subscription to Event Notifications 14 draft-ietf-netconf-subscribed-notifications-05 16 Abstract 18 This document defines capabilities and operations for the customized 19 establishment of subscriptions upon a publisher's event streams. 20 Also defined are delivery mechanisms for instances of the resulting 21 events. Effectively this allows a subscriber to request and receive 22 a continuous, custom influx of publisher generated information. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at https://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on April 5, 2018. 41 Copyright Notice 43 Copyright (c) 2017 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (https://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 59 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3 60 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 61 1.3. Solution Overview . . . . . . . . . . . . . . . . . . . . 5 62 2. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 6 63 2.1. Event Streams . . . . . . . . . . . . . . . . . . . . . . 6 64 2.2. Event Filters . . . . . . . . . . . . . . . . . . . . . . 6 65 2.3. Subscription State Model at the Publisher . . . . . . . . 7 66 3. Data Model Trees . . . . . . . . . . . . . . . . . . . . . . 8 67 4. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . . . 12 68 4.1. Establishing a Subscription . . . . . . . . . . . . . . . 12 69 4.2. Modifying a Subscription . . . . . . . . . . . . . . . . 14 70 4.3. Deleting a Subscription . . . . . . . . . . . . . . . . . 14 71 4.4. Killing a Subscription . . . . . . . . . . . . . . . . . 14 72 5. Configured Subscriptions . . . . . . . . . . . . . . . . . . 15 73 5.1. Establishing a Configured Subscription . . . . . . . . . 15 74 5.2. Modifying a Configured Subscription . . . . . . . . . . . 17 75 5.3. Deleting a Configured Subscription . . . . . . . . . . . 17 76 6. Deleting a Configured Subscription . . . . . . . . . . . . . 18 77 7. Asynchronous Subscribed Content Delivery . . . . . . . . . . 18 78 8. Subscription State Notifications . . . . . . . . . . . . . . 19 79 8.1. subscription-started . . . . . . . . . . . . . . . . . . 19 80 8.2. subscription-modified . . . . . . . . . . . . . . . . . . 19 81 8.3. subscription-terminated . . . . . . . . . . . . . . . . . 20 82 8.4. subscription-suspended . . . . . . . . . . . . . . . . . 20 83 8.5. subscription-resumed . . . . . . . . . . . . . . . . . . 20 84 8.6. subscription-completed . . . . . . . . . . . . . . . . . 20 85 8.7. replay-completed . . . . . . . . . . . . . . . . . . . . 20 86 9. Administrative Functions . . . . . . . . . . . . . . . . . . 21 87 9.1. Subscription Monitoring . . . . . . . . . . . . . . . . . 21 88 9.2. Capability Advertisement . . . . . . . . . . . . . . . . 21 89 9.3. Event Stream Discovery . . . . . . . . . . . . . . . . . 22 90 10. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 22 91 11. Considerations . . . . . . . . . . . . . . . . . . . . . . . 44 92 11.1. Implementation Considerations . . . . . . . . . . . . . 44 93 11.2. Security Considerations . . . . . . . . . . . . . . . . 44 94 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 45 95 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 45 96 13.1. Normative References . . . . . . . . . . . . . . . . . . 45 97 13.2. Informative References . . . . . . . . . . . . . . . . . 46 98 Appendix A. Changes between revisions . . . . . . . . . . . . . 47 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 49 101 1. Introduction 103 This document defines capabilities and operations for the customized 104 establishment of subscriptions upon system generated event streams. 105 Effectively this enables a "Subscribe then Publish" capability where 106 the customized information needs of each target receiver are 107 understood by the publisher before events are marshalled and pushed. 108 The receiver then gets a continuous, custom influx of publisher 109 generated events. 111 While the functionality defined in this document is transport- 112 agnostic, subscription control plane operations bindings exist for 113 both NETCONF [RFC6241] and RESTCONF [RFC8040]. In addition, bindings 114 for the pushed event instances have been defined for protocols such 115 as NETCONF and HTTP2 [RFC7540]. For specifics on these bindings see 116 [I-D.ietf-netconf-event-notif]) and 117 [I-D.ietf-netconf-restconf-notif]. 119 1.1. Motivation 121 There are various [RFC5277] limitations, many of which have been 122 exposed in [RFC7923] which needed to be solved. Key capabilities 123 supported by this document include: 125 o multiple subscriptions on a single transport session 127 o support for dynamic and statically configured subscriptions 129 o modification of an existing subscription 131 o operational counters and instrumentation 133 o negotiation of subscription parameters 135 o promise theory based interaction model 137 o state change notifications (e.g., publisher driven suspension, 138 parameter modification) 140 o independence from transport protocol 142 1.2. Terminology 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 146 document are to be interpreted as described in RFC 2119 [RFC2119]. 148 Configured subscription: A subscription installed via a configuration 149 interface which persists across reboots. 151 Dynamic subscription: A subscription agreed between subscriber and 152 publisher created via RPC subscription state signaling messages. 154 Event: An occurrence of something that may be of interest. (e.g., a 155 configuration change, a fault, a change in status, crossing a 156 threshold, or an external input to the system.) 158 Filter: Evaluation and/or selection criteria, which may be applied 159 against a targeted set of objects or events in a subscription. 160 Information traverses the filter only if specified filter criteria 161 are met. 163 NACM: NETCONF Access Control Model. 165 Notification message: A set of information intended for a Receiver 166 indicating that one or more Event(s) have occurred. Details of the 167 Event(s) may be included within the Notification. 169 Publisher: An entity responsible for streaming notification messages 170 per the terms of a Subscription. 172 Receiver: A target to which a publisher pushes subscribed content. 173 For dynamic subscriptions, the receiver and subscriber are the same 174 entity. 176 Stream (also referred to as "event stream"): A continuous ordered set 177 of events aggregated under some context. 179 Subscriber: An entity able to request and negotiate a contract for 180 the generation and push of event notifications from a publisher. 182 Subscription: A contract with a publisher, stipulating which 183 information one or more receivers wish to have pushed from the 184 publisher without the need for further solicitation. 186 1.3. Solution Overview 188 This document describes a transport protocol-agnostic mechanism for 189 subscribing to and receiving content from a stream instantiated 190 within an event publisher. This mechanism is through the use of a 191 subscription. 193 Two types of subscriptions are supported: 195 1. Dynamic subscriptions, where a subscriber initiates a 196 subscription negotiation with a publisher via RPC. If the 197 publisher wants to serve this request, it accepts it, and then 198 starts pushing notification messages. If the publisher does not 199 wish to serve it as requested, then an error response is 200 returned. This response MAY include hints at subscription 201 parameters which would have been accepted. 203 2. Configured subscriptions, which allow the management of 204 subscriptions via a configuration interface so that a publisher 205 can send notification messages to configured receiver(s). 206 Support for this capability is optional. 208 Additional characteristics differentiating configured from dynamic 209 subscriptions include: 211 o The lifetime of a dynamic subscription is bounded by the transport 212 session used to establish it. For connection-oriented stateful 213 transport like NETCONF, the loss of the transport session will 214 result in the immediate termination of associated dynamic 215 subscriptions. For connectionless or stateless transports like 216 HTTP, it is the lack of receipt acknowledgement of a sequential 217 set of notification messages and/or keep-alives which will 218 terminate dynamic subscriptions. The lifetime of a configured 219 subscription is driven by relevant configuration being present on 220 the running configuration. This implies configured subscriptions 221 persist across reboots, and persist even when transport is 222 unavailable. 224 o Configured subscriptions can be modified by any configuration 225 client with write permission on the configuration of the 226 subscription. Dynamic subscriptions can only be modified via an 227 RPC request made upon the original subscribing transport session. 229 Note that there is no mixing-and-matching of dynamic and configured 230 subscriptions. Specifically, a configured subscription cannot be 231 modified or deleted using RPC. Similarly, a subscription established 232 via RPC cannot be modified through configuration operations (if 233 needed, an operator may use a kill RPC however). 235 The publisher MAY decide to terminate a dynamic subscription at any 236 time. Similarly, it MAY decide to temporarily suspend the sending of 237 notification messages for either configured or dynamic subscriptions. 238 Such termination or suspension MAY be driven by the publisher running 239 out of resources to serve the subscription, or by internal errors on 240 the publisher. 242 2. Solution 244 2.1. Event Streams 246 An event stream is a named entity on a publisher which exposes a 247 continuously updating set of events. Each event stream is available 248 for subscription. It is out of the scope of this document to 249 identify a) how streams are defined, b) how events are defined/ 250 generated, and c) how events are assigned to streams. 252 There are two standardized event streams within this document: 253 NETCONF and SYSLOG. The NETCONF event stream contains all NETCONF 254 XML event information supported by the publisher, except for where it 255 has been explicitly indicated that this the event MUST be excluded 256 from the NETCONF stream. The SYSLOG event stream mirrors the 257 discrete set entries which are concurrently being placed into a 258 device's local Syslog. Beyond these two, additional streams can be 259 added via model augmentation. 261 As events are raised by a system, they may be assigned to one or more 262 streams. The event is distributed to receivers where: (1) a 263 subscription includes the identified stream, and (2) subscription 264 filtering allows the event to traverse. 266 If access control permissions are in use to secure publisher content, 267 then for notifications to be sent to a receiver, that receiver MUST 268 be allowed access to all the events on the stream. If subscriber 269 permissions change during the lifecycle of a subscription, then the 270 subscription MUST be continued or terminated accordingly. 272 2.2. Event Filters 274 A publisher implementation MUST support the ability to perform 275 filtering of events within a stream. Two filtering syntaxes 276 supported are [XPATH] and subtree [RFC6241]. The subsets of these 277 filtering syntaxes supported are left to each implementation. Events 278 which evaluate to "true", or return a non-null selection as a result 279 of the evaluation by the event filter MUST traverse the filter in 280 their entirety. A subset of information is never stripped from 281 within the event. 283 If no event filter is provided, all events on a stream are to be 284 sent. 286 2.3. Subscription State Model at the Publisher 288 Below is the state machine of a subscription for the publisher for a 289 dynamic subscription. It is important to note that such a 290 subscription doesn't exist at the publisher until it is accepted and 291 made active. The mere request by a subscriber to establish a 292 subscription is insufficient for that asserted subscription to be 293 externally visible via this state machine. 295 .-------. 296 | start | 297 '-------' 298 | 299 establish 300 | 301 | .----------modify------------. 302 v v ' 303 .-----------. .-----------. 304 .--------. | |-----suspend------->| | 305 modify '| active | | suspended | 306 '--------->| |<----resume---------| | 307 '-----------' '-----------' 308 | | 309 delete/kill delete/kill 310 | | 311 v | 312 .-------. | 313 | end |<---------------------------' 314 '-------' 316 Figure 1: Subscription states at publisher 318 Of interest in this state machine are the following: 320 o Successful establish or modify RPCs put the subscription into an 321 active state. 323 o Failed modify RPCs will leave the subscription in its previous 324 state, with no visible change to any streaming updates. 326 o A delete or kill RPC will end the subscription. 328 o Suspend and resume state changes are driven by internal process 329 and prioritization. There are no external controls over suspend 330 and resume. 332 An equivalent state machine exists for configured subscriptions. 333 However the transition between states is via configuration operations 334 rather than via RPC. 336 3. Data Model Trees 338 module: ietf-subscribed-notifications 339 +--ro streams 340 | +--ro stream* [name] 341 | +--ro name stream 342 | +--ro description string 343 | +--ro replay-support? empty {replay}? 344 | +--ro replay-log-creation-time? yang:date-and-time {replay}? 345 | +--ro replay-log-aged-time? yang:date-and-time {replay}? 346 +--rw filters 347 | +--rw event-filter* [identifier] 348 | +--rw identifier filter-id 349 | +--rw (filter-spec)? 350 | +--:(subtree-filter) 351 | | +--rw subtree-filter? 352 | +--:(xpath-filter) 353 | +--rw xpath-filter? yang:xpath1.0 354 +--rw subscription-config {configured-subscriptions}? 355 | +--rw subscription* [identifier] 356 | +--rw identifier subscription-id 357 | +--rw encoding? encoding 358 | +--rw (target) 359 | | +--:(stream) 360 | | +--rw (event-filter)? 361 | | | +--:(by-reference) 362 | | | | +--rw event-filter-ref event-filter-ref 363 | | | +--:(within-subscription) 364 | | | +--rw (filter-spec)? 365 | | | +--:(subtree-filter) 366 | | | | +--rw subtree-filter? 367 | | | +--:(xpath-filter) 368 | | | +--rw xpath-filter? yang:xpath1.0 369 | | +--rw stream stream 370 | | +--rw replay-start-time? yang:date-and-time {replay}? 371 | +--rw stop-time? yang:date-and-time 372 | +--rw receivers 373 | | +--rw receiver* [address port] 374 | | +--rw address inet:host 375 | | +--rw port inet:port-number 376 | | +--rw protocol? transport-protocol 377 | +--rw (notification-origin)? 378 | +--:(interface-originated) 379 | | +--rw source-interface? if:interface-ref 380 | +--:(address-originated) 381 | +--rw source-vrf? string 382 | +--rw source-address? inet:ip-address-no-zone 383 +--ro subscriptions 384 +--ro subscription* [identifier] 385 +--ro identifier subscription-id 386 +--ro configured-subscription? empty {configured-subscriptions}? 387 +--ro encoding? encoding 388 +--ro (target) 389 | +--:(stream) 390 | +--ro (event-filter)? 391 | | +--:(by-reference) 392 | | | +--ro event-filter-ref event-filter-ref 393 | | +--:(within-subscription) 394 | | +--ro (filter-spec)? 395 | | +--:(subtree-filter) 396 | | | +--ro subtree-filter? 397 | | +--:(xpath-filter) 398 | | +--ro xpath-filter? yang:xpath1.0 399 | +--ro stream stream 400 | +--ro replay-start-time? yang:date-and-time {replay}? 401 +--ro stop-time? yang:date-and-time 402 +--ro (notification-origin)? 403 | +--:(interface-originated) 404 | | +--ro source-interface? if:interface-ref 405 | +--:(address-originated) 406 | +--ro source-vrf? string 407 | +--ro source-address? inet:ip-address-no-zone 408 +--ro receivers 409 +--ro receiver* [address port] 410 +--ro address inet:host 411 +--ro port inet:port-number 412 +--ro protocol? transport-protocol 413 +--ro pushed-notifications? yang:counter64 414 +--ro excluded-notifications? yang:counter64 415 +--ro status subscription-status 417 rpcs: 418 +---x establish-subscription 419 | +---w input 420 | | +---w encoding? encoding 421 | | +---w (target) 422 | | | +--:(stream) 423 | | | +---w (event-filter)? 424 | | | | +--:(by-reference) 425 | | | | | +---w event-filter-ref event-filter-ref 426 | | | | +--:(within-subscription) 427 | | | | +---w (filter-spec)? 428 | | | | +--:(subtree-filter) 429 | | | | | +---w subtree-filter? 430 | | | | +--:(xpath-filter) 431 | | | | +---w xpath-filter? yang:xpath1.0 432 | | | +---w stream stream 433 | | | +---w replay-start-time? yang:date-and-time {replay}? 434 | | +---w stop-time? yang:date-and-time 435 | +--ro output 436 | +--ro subscription-result subscription-result 437 | +--ro (result)? 438 | +--:(no-success) 439 | | +--ro filter-failure? string 440 | | +--ro replay-start-time-hint? yang:date-and-time 441 | +--:(success) 442 | +--ro identifier subscription-id 443 +---x modify-subscription 444 | +---w input 445 | | +---w identifier? subscription-id 446 | | +---w (target) 447 | | | +--:(stream) 448 | | | +---w (event-filter)? 449 | | | +--:(by-reference) 450 | | | | +---w event-filter-ref event-filter-ref 451 | | | +--:(within-subscription) 452 | | | +---w (filter-spec)? 453 | | | +--:(subtree-filter) 454 | | | | +---w subtree-filter? 455 | | | +--:(xpath-filter) 456 | | | +---w xpath-filter? yang:xpath1.0 457 | | +---w stop-time? yang:date-and-time 458 | +--ro output 459 | +--ro subscription-result subscription-result 460 | +--ro (result)? 461 | +--:(no-success) 462 | +--ro filter-failure? string 463 +---x delete-subscription 464 | +---w input 465 | | +---w identifier subscription-id 466 | +--ro output 467 | +--ro subscription-result subscription-result 468 +---x kill-subscription 469 +---w input 470 | +---w identifier subscription-id 471 +--ro output 472 +--ro subscription-result subscription-result 474 notifications: 475 +---n replay-completed 476 | +--ro identifier subscription-id 477 +---n subscription-completed 478 | +--ro identifier subscription-id 479 +---n subscription-started 480 | +--ro identifier subscription-id 481 | +--ro encoding? encoding 482 | +--ro (target) 483 | | +--:(stream) 484 | | +--ro (event-filter)? 485 | | | +--:(by-reference) 486 | | | | +--ro event-filter-ref event-filter-ref 487 | | | +--:(within-subscription) 488 | | | +--ro (filter-spec)? 489 | | | +--:(subtree-filter) 490 | | | | +--ro subtree-filter? 491 | | | +--:(xpath-filter) 492 | | | +--ro xpath-filter? yang:xpath1.0 493 | | +--ro stream stream 494 | | +--ro replay-start-time? yang:date-and-time {replay}? 495 | +--ro stop-time? yang:date-and-time 496 +---n subscription-resumed 497 | +--ro identifier subscription-id 498 +---n subscription-modified 499 | +--ro identifier subscription-id 500 | +--ro encoding? encoding 501 | +--ro (target) 502 | | +--:(stream) 503 | | +--ro (event-filter)? 504 | | | +--:(by-reference) 505 | | | | +--ro event-filter-ref event-filter-ref 506 | | | +--:(within-subscription) 507 | | | +--ro (filter-spec)? 508 | | | +--:(subtree-filter) 509 | | | | +--ro subtree-filter? 510 | | | +--:(xpath-filter) 511 | | | +--ro xpath-filter? yang:xpath1.0 512 | | +--ro stream stream 513 | | +--ro replay-start-time? yang:date-and-time {replay}? 514 | +--ro stop-time? yang:date-and-time 515 +---n subscription-terminated 516 | +--ro identifier subscription-id 517 | +--ro error-id subscription-errors 518 | +--ro filter-failure? string 519 +---n subscription-suspended 520 +--ro identifier subscription-id 521 +--ro error-id subscription-errors 522 +--ro filter-failure? string 524 The top-level decompositions of data model are as follows: 526 o "Streams" contains a list of event streams that are supported by 527 the publisher and against which subscription is allowed. 529 o "Filters" contains a configurable list of filters that can be 530 applied to a subscription. This allows users to reference an 531 existing filter definition as an alternative to defining a filter 532 inline for each subscription. 534 o "Subscription-config" contains the configuration of configured 535 subscriptions. The parameters of each configured subscription are 536 a superset of the parameters of a dynamic subscription and use the 537 same groupings. In addition, the configured subscriptions MUST 538 also specify intended receivers and MAY specify the push source 539 from which to send the stream of notification messages. 541 o "Subscriptions" contains a list of all subscriptions on a 542 publisher, both configured and dynamic. It can be used to 543 retrieve information about the subscriptions which a publisher is 544 serving. 546 The data model also contains a number of notifications that allow a 547 publisher to signal information about a subscription. Finally, the 548 data model contains a number of RPC definitions that are used to 549 manage dynamic subscriptions. 551 4. Dynamic Subscriptions 553 Dynamic subscriptions are managed via RPC. 555 4.1. Establishing a Subscription 557 The operation allows a subscriber to request 558 the creation of a subscription via RPC. 560 The input parameters of the operation are: 562 o A stream which identifies the domain of events against which the 563 subscription is applied. 565 o A filter which may reduce the set of events pushed. 567 o The desired encoding for the returned events. By default, updates 568 are encoded using XML. Other encodings MAY be supported, such as 569 JSON. 571 o An optional stop time for the subscription. 573 o An optional start time which indicates that this subscription is 574 requesting a replay push of events previously generated. 576 If the publisher cannot satisfy the request, 577 it sends a negative element. If the subscriber 578 has no authorization to establish the subscription, the 579 indicates an authorization error. Optionally, 580 the MAY include one or more hints on 581 alternative input parameters and value which would have resulted in 582 an accepted subscription. 584 Subscription requests MUST fail if a filter with invalid syntax is 585 provided or if a non-existent stream is referenced. 587 4.1.1. Replay Subscription 589 Replay provides the ability to establish an event subscription which 590 is also capable of passing along recently generated events. In other 591 words, as the subscription initializes itself, it sends any 592 previously generated notifications for the target event stream which 593 meet the filter and timeframe criteria. These historical events 594 would then be followed by events generated after the subscription has 595 been established. All events will be delivered in the order 596 generated. Replay is only viable for dynamic subscriptions. Replay 597 is an optional feature. Replay is dependent on a notification stream 598 supporting some form of notification logging, although it puts no 599 restrictions on the size or form of the log, or where it resides 600 within the device. 602 The presence of a replay-start-time within an RPC is the way a replay may be been requested. The 604 provided start time MUST be earlier than the current time. If the 605 start time points earlier than the maintained history of Publisher's 606 event buffer, then the subscription MUST be rejected. In this case 607 the error response to the request SHOULD 608 include a start time supportable by the Publisher. An end time MAY 609 be specified using the optional stop-time parameter, which MAY also 610 be earlier than the current time. If no stop-time is present, 611 notifications will continue to be sent until the subscription is 612 terminated. 614 Not all streams will support replay. Those that do MUST include the 615 flag. In addition, a notification stream that 616 does support replay is not expected to have an unlimited supply of 617 saved notifications available to accommodate any given replay 618 request. Subscribers MAY do a get on and 619 to assess the availability of notifications 620 for replay. The actual number of stored notifications available for 621 retrieval at any given time is a publisher specific matter. Control 622 parameters for this aspect of the feature are outside the scope of 623 this document. 625 4.2. Modifying a Subscription 627 The operation permits changing the terms of an 628 existing dynamic subscription previously established on that 629 transport session. Subscriptions created by configuration operations 630 cannot be modified via this RPC. Dynamic subscriptions can be 631 modified one or multiple times. If the publisher accepts the 632 requested modifications, it immediately starts sending events based 633 on the new terms, completely ignoring the previous ones. If the 634 publisher rejects the request, the subscription remains as prior to 635 the request. That is, the request has no impact whatsoever. The 636 contents of a such a rejected modification MAY include one or more 637 hints on alternative input parameters and value which would have 638 resulted in a successfully modified subscription. 640 Dynamic subscriptions established via RPC can only be modified via 641 RPC using the same transport session used to establish that 642 subscription. 644 4.3. Deleting a Subscription 646 The operation permits canceling an existing 647 subscription previously established on that transport session. If 648 the publisher accepts the request, it immediately stops sending 649 events for the subscription. If the publisher rejects the request, 650 all subscriptions remain as prior to the request. That is, the 651 request has no impact whatsoever. 653 Subscriptions established via RPC can only be deleted via RPC using 654 the same transport session used for subscription establishment. 655 Configured subscriptions cannot be deleted using RPCs. 657 4.4. Killing a Subscription 659 The operation permits an operator to end any 660 dynamic subscription. A publisher MUST terminate any dynamic 661 subscription identified within a properly authenticated RPC request. 663 Configured subscriptions cannot be killed using this RPC. Instead, 664 configured subscriptions are deleted as part of regular configuration 665 operations. Publishers MUST reject any RPC attempt to kill a 666 configured subscription. 668 5. Configured Subscriptions 670 A configured subscription is a subscription installed via a 671 configuration interface. 673 Configured subscriptions persist across reboots, and persist even 674 when transport is unavailable. 676 Configured subscriptions can be modified by any configuration client 677 with write permissions for the configuration of the subscription. 678 Subscriptions can be modified or terminated via the configuration 679 interface at any point of their lifetime. 681 Supporting configured subscriptions is optional and advertised using 682 the "configured-subscriptions" feature. 684 In addition to subscription parameters that apply to dynamic 685 subscriptions, the following additional parameters apply to 686 configured subscriptions: 688 o One or more receiver IP addresses (and corresponding ports) 689 intended as the destination for push updates for each 690 subscription. In addition, the transport protocol for each 691 destination MAY be defined. 693 o Optional parameters to identify an egress interface or IP address 694 plus VRF out of which subscription updates should be pushed from 695 the publisher. Where these are not explicitly included, or where 696 just the VRF is provided, push updates MUST egress the publisher's 697 default interface towards a receiver. 699 5.1. Establishing a Configured Subscription 701 Configured subscriptions are established using configuration 702 operations against the top-level subtree subscription-config. There 703 are two key differences between RPC and RPC operations 704 for subscription establishment. Firstly, operations 705 install a subscription without question, while RPCs are designed to 706 the support negotiation and rejection of requests. Secondly, while 707 RPCs mandate that the subscriber establishing the subscription is the 708 only receiver of the notifications, operations permit 709 specifying receivers independent of any tracked subscriber. Because 710 there is no explicit association with an existing transport session, 711 operations require additional parameters beyond those 712 of dynamic subscriptions to indicate the receivers of the 713 notifications and possibly the source of the notifications such as a 714 specific egress interface. 716 Immediately after a subscription is successfully established, the 717 publisher sends to identified receivers a state change notification 718 stating the subscription has been established (i.e., subscription- 719 started). 721 It is quite possible that upon configuration, reboot, or even steady- 722 state operations, a transport session may not be currently available 723 to the receiver. In this case, when there is something to transport 724 for an active subscription, transport protocol specific call-home 725 operations will be used to establish the connection. 727 As an example at subscription establishment using over 728 NETCONF, a client might send: 730 733 734 735 736 737 740 741 1922 742 743 NETCONF 744 745
1.2.3.4
746 1234 747 748 749 750 751 752 754 Figure 2: Configured subscription creation via NETCONF 756 if the request is accepted, the publisher would reply: 758 760 761 763 Figure 3: Successful NETCONF configured subscription response 765 if the request is not accepted because the publisher cannot serve it, 766 the publisher may reply: 768 769 770 application 771 resource-denied 772 error 773 774 Temporarily the publisher cannot serve this 775 subscription due to the current workload. 776 777 778 780 Figure 4: A NETCONF response for a failed configured subscription 781 creation 783 5.2. Modifying a Configured Subscription 785 Configured subscriptions can be modified using configuration 786 operations against the top-level subtree subscription-config. 788 Immediately after a subscription is successfully modified, the 789 publisher sends to the existing receivers a state change notification 790 stating the subscription has been modified (i.e., subscription- 791 modified). 793 If the modification involved adding and/or removing receivers, those 794 modified receivers are sent state change notifications, indicating 795 they have been added (i.e, subscription-started to a specific 796 receiver) or removed (i.e., subscription-terminated to a specific 797 receiver.) 799 5.3. Deleting a Configured Subscription 801 Subscriptions can be deleted using configuration operations against 802 the top-level subtree subscription-config. For example, in RESTCONF: 804 DELETE /subscription-config/subscription=1922 HTTP/1.1 805 Host: example.com 807 HTTP/1.1 204 No Content 808 Date: Sun, 24 Jul 2016 11:23:40 GMT 809 Server: example-server 811 Figure 5: Deleting a configured subscription 813 Immediately after a subscription is successfully deleted, the 814 publisher sends to all receivers of that subscription a state change 815 notification stating the subscription has been terminated (i.e., 816 subscription-terminated). 818 6. Deleting a Configured Subscription 820 Configured subscriptions can be deleted using configuration 821 operations against the top-level subtree subscription-config. 823 Immediately after a subscription is successfully deleted, the 824 publisher sends to the existing receivers a state change notification 825 stating the subscription has been terminated (i.e., subscription- 826 terminated). 828 7. Asynchronous Subscribed Content Delivery 830 Once a subscription has been set up, the publisher streams 831 asynchronously push subscribed content via notification messages per 832 the terms of the subscription. For dynamic subscriptions set up via 833 RPC operations, notification messages are sent over the session used 834 to establish the subscription. For configured subscriptions, 835 notification messages are sent over the specified connections. 837 A notification message is sent to a receiver when something of 838 interest occurs which is able to traverse all specified filtering and 839 access control criteria. 841 This notification message MAY be encoded as one-way notification 842 element of [RFC5277], Section 4. The following example within 843 [RFC7950] section 7.16.3 is an example of a compliant message: 845 847 2007-09-01T10:00:00Z 848 849 so-1/2/3.0 850 up 851 down 852 853 855 Figure 6: subscribed content notification 857 This [RFC5277] section 4 has the drawback of not including useful 858 header information such as subscription-ID. When using this 859 mechanism, it is left up to implementations to determine which events 860 belong to which subscription. 862 In addition [RFC5277] section 4 does not provide a mechanism to for 863 JSON encoding of notifications. 865 These drawbacks, along with other useful common headers and the 866 ability to bundle multiple event notifications together is being 867 explored within [I-D.notification-messages]. When this draft is 868 supported, it will be possible to support the encoding of YANG 869 modeled notification messages with JSON via [RFC7951]. 871 8. Subscription State Notifications 873 In addition to subscribed content, a publisher will send subscription 874 state notifications to indicate to receivers that an event related to 875 the subscription management has occurred. 877 Subscription state notifications are unlike other notifications in 878 that they are not general-purpose notifications. They cannot be 879 filtered out, and they are delivered only to directly impacted 880 receiver(s) of a subscription. The definition of subscription state 881 notifications is distinct from other notifications by making use of a 882 YANG extension tagging them as subscription state notification. 884 Subscription state notifications include indications that a replay of 885 events has been completed, that a subscription is done because an end 886 time has been reached, and that a subscription has started, been 887 modified, been terminated, or been suspended. They are described in 888 the following subsections. 890 8.1. subscription-started 892 This notification indicates that a configured subscription has 893 started and data updates are beginning to be sent. This notification 894 includes the parameters of the subscription, except for the 895 receiver(s) addressing information and push-source information. Note 896 that for RPC-based subscriptions, no such notifications are sent. 898 8.2. subscription-modified 900 This notification indicates that a configured subscription has been 901 modified successfully. This notification includes the parameters of 902 the subscription, except for the receiver(s) addressing information 903 and push-source information. Note that for RPC-based subscriptions, 904 no such notifications are sent. 906 8.3. subscription-terminated 908 This notification indicates that a subscription has been terminated 909 by the publisher. The notification includes the reason for the 910 termination. The publisher MAY decide to terminate a subscription 911 when it is running out of resources for serving it, an internal error 912 occurs, etc. Publisher-driven terminations are notified to all 913 receivers. Northbound systems MAY also terminate configured 914 subscriptions using configuration operations. 916 Subscribers can terminate via RPC subscriptions established via a 917 delete-subscription RPC. In such cases, no subscription-terminated 918 notifications are sent. However if a kill-subscription RPC is sent, 919 or some other event results in the end of a subscription, then there 920 MUST be a notification that the subscription has been ended. 922 8.4. subscription-suspended 924 This notification indicates that a publisher has suspended a 925 subscription. The notification includes the reason for the 926 suspension. A possible reason is the lack of resources to serve it. 927 No further subscribed content will be sent until the subscription 928 resumes. Suspensions are notified to the subscriber (in the case of 929 dynamic subscriptions) and all receivers (in the case of configured 930 subscriptions). 932 8.5. subscription-resumed 934 This notification indicates that a previously suspended subscription 935 has been resumed. Subscribed content generated after the generation 936 of this state change notification will be sent. These notifications 937 go to the subscriber (in the case of dynamic subscriptions) and all 938 receivers (in the case of configured subscriptions). 940 8.6. subscription-completed 942 This notification is sent to indicate that a subscription, which 943 includes a stop time, has successfully finished passing events upon 944 the reaching of that stop time. 946 8.7. replay-completed 948 This notification indicates that all of the events prior to the 949 current time have been sent. This includes new events generated 950 since the start of the subscription. This notification MUST NOT be 951 sent for any other reason. 953 If subscription contains no stop time, or has a stop time which has 954 not been reached, then after the replay-completed notification has 955 been sent events will be sent in sequence as they arise naturally 956 within the system. 958 9. Administrative Functions 960 9.1. Subscription Monitoring 962 Container "subscriptions" in the YANG module below contains the state 963 of all known subscriptions. This includes subscriptions that were 964 established (and have not yet been deleted) using RPCs, as well as 965 subscriptions that have been configured as part of configuration. 966 Using the operation with NETCONF, or subscribing to this 967 information via [I-D.ietf-netconf-yang-push] allows the status of 968 subscriptions to be monitored. 970 Each subscription is represented as a list element. The associated 971 information includes an identifier for the subscription, receiver 972 counter information, the status of the subscription, as well as the 973 various subscription parameters that are in effect. The subscription 974 status indicates the subscription's state with each receiver (e.g., 975 is currently active or suspended). Leaf "configured-subscription" 976 indicates whether the subscription came into being via configuration 977 or via RPC. 979 Subscriptions that were established by RPC are removed from the list 980 once they expire (reaching stop-time) or when they are terminated. 981 Subscriptions that were established by configuration need to be 982 deleted from the configuration by a configuration editing operation 983 even if the stop time has been passed. 985 9.2. Capability Advertisement 987 Capabilities are advertised in messages sent by each peer during 988 session establishment [RFC6241]. Publishers supporting the RPCs and 989 Notifications in this document MUST advertise the capability 990 "urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications:1.0". In 991 addition support for optional features: json, configured- 992 subscriptions, and replay MAY also be advertised. 994 If a subscriber only supports [RFC5277] and not this specification, 995 then they will recognize the capability 996 "urn:ietf:params:netconf:capability:notification:1.0" and ignore any 997 new subscription capabilities defined in this document. 999 If a publisher supports this specification but not [RFC5277], the 1000 publisher MUST support the one-way notification element of [RFC5277] 1001 Section 4 or [I-D.notification-messages]. 1003 9.3. Event Stream Discovery 1005 A publisher maintains a list of available event streams as 1006 operational data. This list contains both standardized and vendor- 1007 specific event streams. A client can retrieve this list like any 1008 other YANG-defined data, for example using the operation when 1009 using NETCONF. 1011 10. Data Model 1013 file "ietf-subscribed-notifications.yang" 1014 module ietf-subscribed-notifications { 1015 yang-version 1.1; 1016 namespace 1017 "urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"; 1019 prefix sn; 1021 import ietf-yang-types { 1022 prefix yang; 1023 } 1024 import ietf-inet-types { 1025 prefix inet; 1026 } 1027 import ietf-interfaces { 1028 prefix if; 1029 } 1031 organization "IETF"; 1032 contact 1033 "WG Web: 1034 WG List: 1036 Editor: Alexander Clemm 1037 1039 Editor: Eric Voit 1040 1042 Editor: Alberto Gonzalez Prieto 1043 1045 Editor: Einar Nilsen-Nygaard 1046 1048 Editor: Ambika Prasad Tripathy 1049 "; 1051 description 1052 "Contains a conceptual YANG specification for subscribing to events 1053 and receiving matching content within notification messages."; 1055 revision 2017-10-02 { 1056 description 1057 "Filtering and stream structures updated, replay a feature."; 1058 reference 1059 "draft-ietf-netconf-subscribed-notifications-05"; 1060 } 1062 /* 1063 * FEATURES 1064 */ 1066 feature json { 1067 description 1068 "This feature indicates that JSON encoding of notifications 1069 is supported."; 1070 } 1072 feature configured-subscriptions { 1073 description 1074 "This feature indicates that management plane configuration 1075 of subscription is supported."; 1076 } 1078 feature replay { 1079 description 1080 "This feature indicates that historical event replay is 1081 supported. With replay, it is possible for past events to be 1082 will be streamed in chronological order."; 1083 } 1085 /* 1086 * EXTENSIONS 1087 */ 1089 extension subscription-state-notif { 1090 description 1091 "This statement applies only to notifications. It indicates that 1092 the notification is a subscription state notification. Therefore 1093 it does not participate in a regular event stream and does not 1094 need to be specifically subscribed to in order to receive 1095 notifications."; 1097 } 1099 /* 1100 * IDENTITIES 1101 */ 1103 /* Identities for streams */ 1104 identity stream { 1105 description 1106 "Base identity to represent a generic stream of event 1107 notifications exposed for subscription by a system."; 1108 } 1110 identity NETCONF { 1111 base stream; 1112 description 1113 "Default NETCONF event stream, containing events based on 1114 notifications defined as YANG modules that are supported by the 1115 system. As a historical reference, this contains the same set 1116 of events in a default RFC-5277 NETCONF stream."; 1117 } 1119 identity SYSLOG { 1120 base stream; 1121 description 1122 "A stream of events mirroring the discrete set entries 1123 concurrently being placed into a device's local Syslog."; 1124 } 1126 identity custom-stream { 1127 base stream; 1128 description 1129 "A supported stream not defined via an identity in this model"; 1130 } 1132 /* Identities for subscription results */ 1133 identity subscription-result { 1134 description 1135 "Base identity for RPC responses and State Change Notifications 1136 providing information on the creation, modification, deletion of 1137 subscriptions."; 1138 } 1140 identity ok { 1141 base subscription-result; 1142 description 1143 "OK - RPC was successful and was performed as requested."; 1144 } 1145 identity error { 1146 base subscription-result; 1147 description 1148 "Problem with subscription. Base identity for error return 1149 codes for RPCs and State Change Notifications."; 1150 } 1152 /* Identities for subscription stream status */ 1153 identity subscription-status { 1154 description 1155 "Base identity for the status of a subscription. This status 1156 indicates whether a subscriber is actively generating 1157 notifications intended for a particular receiver."; 1158 } 1160 identity active { 1161 base subscription-status; 1162 description 1163 "Status is active and healthy."; 1164 } 1166 identity inactive { 1167 base subscription-status; 1168 description 1169 "Status is inactive, for example after the stop time, but not 1170 yet deleted from the configuration."; 1171 } 1173 identity suspended { 1174 base subscription-status; 1175 description 1176 "The status is suspended, meaning that the publisher is currently 1177 unable to provide the negotiated updates for the subscription."; 1178 } 1180 identity in-error { 1181 base subscription-status; 1182 description 1183 "The status is in error or degraded, meaning that stream and/or 1184 subscription is currently unable to provide the negotiated 1185 notifications."; 1186 } 1188 /* Identities for subscription errors */ 1190 identity internal-error { 1191 base error; 1192 description 1193 "Error within publisher prohibits operation."; 1194 } 1196 identity suspension-timeout { 1197 base error; 1198 description 1199 "Termination of previously suspended subscription. The publisher 1200 has eliminated the subscription as it exceeded a time limit for 1201 suspension."; 1202 } 1204 identity stream-unavailable { 1205 base error; 1206 description 1207 "Stream does not exist or is not available to the receiver."; 1208 } 1210 identity encoding-unavailable { 1211 base error; 1212 description 1213 "Encoding not supported"; 1214 } 1216 identity replay-unsupported { 1217 base error; 1218 description 1219 "Replay cannot be performed for this subscription. The publisher 1220 does not provide the requested historic information via replay."; 1221 } 1223 identity history-unavailable { 1224 base error; 1225 description 1226 "Replay request too far into the past. The publisher does store 1227 historic information for all parts of requested subscription, but 1228 not back to the requested timestamp."; 1229 } 1231 identity filter-unavailable { 1232 base error; 1233 description 1234 "Referenced filter does not exist"; 1235 } 1237 identity filter-type-unsupported { 1238 base error; 1239 description 1240 "Publisher does not support filters constructed using this 1241 filtering technology syntax."; 1242 } 1244 identity filter-unsupported { 1245 base error; 1246 description 1247 "Failure can be from a syntax error, or a syntax too complex to be 1248 processed by the platform. The supplemental info should include 1249 the invalid part of the filter."; 1250 } 1252 identity namespace-unavailable { 1253 base error; 1254 description 1255 "Referenced namespace doesn't exist or is unavailable 1256 to the receiver."; 1257 } 1259 identity no-such-subscription { 1260 base error; 1261 description 1262 "Referenced subscription doesn't exist. This may be as a result of 1263 a non-existent subscription ID, an ID which belongs to another 1264 subscriber, or an ID for acceptable subscription which has been 1265 statically configured."; 1266 } 1268 identity error-insufficient-resources { 1269 base error; 1270 description 1271 "The server has insufficient resources to support the 1272 subscription as requested by an RPC."; 1273 } 1275 identity unsupportable-volume { 1276 base error; 1277 description 1278 "The publisher cannot support the volume of information intended 1279 to be sent for an existing subscription."; 1280 } 1282 identity error-no-such-option { 1283 base error; 1284 description 1285 "A requested parameter setting is not supported."; 1286 } 1288 /* Identities for encodings */ 1289 identity encodings { 1290 description 1291 "Base identity to represent data encodings"; 1292 } 1294 identity encode-xml { 1295 base encodings; 1296 description 1297 "Encode data using XML"; 1298 } 1300 identity encode-json { 1301 base encodings; 1302 description 1303 "Encode data using JSON"; 1304 } 1306 /* Identities for transports */ 1307 identity transport { 1308 description 1309 "An identity that represents a transport protocol for event 1310 notifications"; 1311 } 1313 identity netconf { 1314 base transport; 1315 description 1316 "Netconf notifications as a transport."; 1317 } 1319 identity http2 { 1320 base transport; 1321 description 1322 "HTTP2 notifications as a transport"; 1323 } 1325 /* 1326 * TYPEDEFs 1327 */ 1329 typedef subscription-id { 1330 type uint32; 1331 description 1332 "A type for subscription identifiers."; 1333 } 1335 typedef filter-id { 1336 type uint32; 1337 description 1338 "A type to identify filters which can be associated with a 1339 subscription."; 1340 } 1342 typedef subscription-result { 1343 type identityref { 1344 base subscription-result; 1345 } 1346 description 1347 "The result of a subscription operation"; 1348 } 1350 typedef subscription-errors { 1351 type identityref { 1352 base error; 1353 } 1354 description 1355 "The reason for the failure of an RPC request or the sending 1356 of a subscription suspension or termination notification"; 1357 } 1359 typedef encoding { 1360 type identityref { 1361 base encodings; 1362 } 1363 description 1364 "Specifies a data encoding, e.g. for a data subscription."; 1365 } 1367 typedef subscription-status { 1368 type identityref { 1369 base subscription-status; 1370 } 1371 description 1372 "Specifies the status of a subscription."; 1373 } 1375 typedef transport-protocol { 1376 type identityref { 1377 base transport; 1378 } 1379 description 1380 "Specifies transport protocol used to send notifications to a 1381 receiver."; 1382 } 1384 typedef egressing-from { 1385 type enumeration { 1386 enum "interface-originated" { 1387 description 1388 "Notifications will be sent from a specific interface on a 1389 publisher"; 1390 } 1391 enum "address-originated" { 1392 description 1393 "Notifications will be sent from a specific address on a 1394 publisher"; 1395 } 1396 } 1397 description 1398 "Specifies from where notifications will be sourced when 1399 being sent by the publisher."; 1400 } 1402 typedef stream { 1403 type identityref { 1404 base stream; 1405 } 1406 description 1407 "Specifies a system-provided datastream."; 1408 } 1410 typedef event-filter-ref { 1411 type leafref { 1412 path "/sn:filters/sn:event-filter/sn:identifier"; 1413 } 1414 description 1415 "This type is used to reference an event filter."; 1416 } 1418 /* 1419 * GROUPINGS 1420 */ 1422 grouping event-filter-elements { 1423 description 1424 "This grouping defines the base for filters for notification 1425 events."; 1426 choice filter-spec { 1427 description 1428 "The content filter specification for this request."; 1429 anydata subtree-filter { 1430 description 1431 "Event stream evaluation criteria encoded in a syntax of a 1432 supported type of an RFC 6241, Section 6 filter. When 1433 applied against an event stream and there is a non-empty or 1434 positive result, the event is passed along."; 1435 reference "RFC 6241, Section 6."; 1436 } 1437 leaf xpath-filter { 1438 type yang:xpath1.0; 1439 description 1440 "Event stream evaluation criteria encoded in a syntax of xpath 1441 1.0 When applied against an event stream and there is a 1442 non-empty or positive result, the event is passed along."; 1443 reference "http://www.w3.org/TR/1999/REC-xpath-19991116"; 1444 } 1445 } 1446 } 1448 grouping subscription-policy-modifiable { 1449 description 1450 "This grouping describes all objects which may be changed 1451 in a subscription via an RPC."; 1452 choice target { 1453 mandatory true; 1454 description 1455 "A filter must be applied against some source of information. 1456 This identifies the target for the filter."; 1457 case stream { 1458 choice event-filter { 1459 description 1460 "A filter can be applied to a subscription. And that filter 1461 will come either referenced from a global list, or be 1462 provided within the subscription itself."; 1463 case by-reference { 1464 description 1465 "Apply a filter that has been configured separately."; 1466 leaf event-filter-ref { 1467 type event-filter-ref; 1468 mandatory true; 1469 description 1470 "References an existing filter which is to be applied to 1471 the subscription."; 1472 } 1473 } 1474 case within-subscription { 1475 description 1476 "Local definition allows a filter to have the same 1477 lifecycle as the subscription."; 1478 uses event-filter-elements; 1479 } 1480 } 1482 } 1483 } 1484 leaf stop-time { 1485 type yang:date-and-time; 1486 description 1487 "Identifies a time after which notification events should not 1488 be sent. If stop-time is not present, the notifications will 1489 continue until the subscription is terminated. If 1490 replay-start-time exists, stop-time must for a subsequent time. 1491 If replay-start-time doesn't exist, stop-time must for a future 1492 time."; 1493 } 1494 } 1496 grouping subscription-policy { 1497 description 1498 "This grouping describes information concerning a subscription."; 1499 leaf encoding { 1500 type encoding; 1501 default "encode-xml"; 1502 description 1503 "The type of encoding for the subscribed data. Default is XML"; 1504 } 1505 uses subscription-policy-modifiable { 1506 augment target/stream { 1507 description 1508 "Adds additional objects which must be set just by RPC."; 1509 leaf stream { 1510 type stream; 1511 mandatory true; 1512 description 1513 "Indicates a stream of events against which to apply 1514 an event filter."; 1515 } 1516 leaf replay-start-time { 1517 if-feature "replay"; 1518 type yang:date-and-time; 1519 description 1520 "Used to trigger the replay feature and indicate that the 1521 replay should start at the time specified. If 1522 replay-start-time is not present, this is not a replay 1523 subscription and event pushes should start immediately. It 1524 is never valid to specify start times that are later than 1525 or equal to the current time."; 1526 } 1527 } 1528 } 1529 } 1530 grouping notification-origin-info { 1531 description 1532 "Defines the sender source from which notifications for a 1533 configured subscription are sent."; 1534 choice notification-origin { 1535 description 1536 "Identifies the egress interface on the Publisher from which 1537 notifications will or are being sent."; 1538 case interface-originated { 1539 description 1540 "When the push source is out of an interface on the 1541 Publisher established via static configuration."; 1542 leaf source-interface { 1543 type if:interface-ref; 1544 description 1545 "References the interface for notifications."; 1546 } 1547 } 1548 case address-originated { 1549 description 1550 "When the push source is out of an IP address on the 1551 Publisher established via static configuration."; 1552 leaf source-vrf { 1553 type string; 1554 description 1555 "Network instance name for the VRF. This could also have 1556 been a leafref to draft-ietf-rtgwg-ni-model, but that model 1557 is not complete, and might not be implemented on a box."; 1558 } 1559 leaf source-address { 1560 type inet:ip-address-no-zone; 1561 description 1562 "The source address for the notifications. If a source VRF 1563 exists, but this object doesn't, a default address for the 1564 VRF can be used."; 1565 } 1566 } 1567 } 1568 } 1570 grouping receiver-info { 1571 description 1572 "Defines where and how to get notifications for a configured 1573 subscriptions to one or more targeted recipient. This includes 1574 specifying the destination addressing as well as a transport 1575 protocol acceptable to the receiver."; 1576 container receivers { 1577 description 1578 "Set of receivers in a subscription."; 1579 list receiver { 1580 key "address port"; 1581 min-elements 1; 1582 description 1583 "A single host or multipoint address intended as a target 1584 for the notifications for a subscription."; 1585 leaf address { 1586 type inet:host; 1587 description 1588 "Specifies the address for the traffic to reach a remote 1589 host. One of the following must be specified: an ipv4 1590 address, an ipv6 address, or a host name."; 1591 } 1592 leaf port { 1593 type inet:port-number; 1594 description 1595 "This leaf specifies the port number to use for messages 1596 destined for a receiver."; 1597 } 1598 leaf protocol { 1599 type transport-protocol; 1600 default "netconf"; 1601 description 1602 "This leaf specifies the transport protocol used 1603 to deliver messages destined for the receiver. Each 1604 protocol may use the address and port information 1605 differently as applicable."; 1606 } 1607 } 1608 } 1609 } 1611 grouping error-identifier { 1612 description 1613 "A code passed back within an RPC response to describe why the RFC 1614 has failed, or within a state change notification to describe why 1615 the change has occurred."; 1616 leaf error-id { 1617 type subscription-errors; 1618 mandatory true; 1619 description 1620 "Identifies the subscription error condition."; 1621 } 1622 } 1624 grouping hints { 1625 description 1626 "Objects passed back within an RPC response to describe why the 1627 RFC has failed, or within a state change notification to 1628 describe why the change has occurred."; 1629 leaf filter-failure { 1630 type string; 1631 description 1632 "Information describing where and/or why a provided filter was 1633 unsupportable for a subscription."; 1634 } 1635 } 1637 grouping subscription-response-with-hints { 1638 description 1639 "Defines the output for the establish-subscription and 1640 modify-subscription RPCs."; 1641 leaf subscription-result { 1642 type subscription-result; 1643 mandatory true; 1644 description 1645 "Indicates whether subscription is operational, or if a problem 1646 was encountered."; 1647 } 1648 choice result { 1649 description 1650 "Depending on the subscription result, different data is 1651 returned."; 1652 case no-success { 1653 description 1654 "This case applies when a subscription request was not 1655 successful and no subscription was created (or modified) as a 1656 result. In this case, information MAY be returned that 1657 indicates suggested parameter settings that would have a 1658 high likelihood of succeeding in a subsequent establish- 1659 subscription or modify-subscription request."; 1660 uses hints; 1661 } 1662 } 1663 } 1665 /* 1666 * RPCs 1667 */ 1669 rpc establish-subscription { 1670 description 1671 "This RPC allows a subscriber to create (and possibly negotiate) 1672 a subscription on its own behalf. If successful, the 1673 subscription remains in effect for the duration of the 1674 subscriber's association with the publisher, or until the 1675 subscription is terminated. In case an error (as indicated by 1676 subscription-result) is returned, the subscription is not 1677 created. In that case, the RPC reply MAY include suggested 1678 parameter settings that would have a higher likelihood of 1679 succeeding in a subsequent establish-subscription request."; 1680 input { 1681 uses subscription-policy; 1682 } 1683 output { 1684 uses subscription-response-with-hints { 1685 augment "result" { 1686 description 1687 "Allows information to be passed back as part of a 1688 successful subscription establishment."; 1689 case success { 1690 description 1691 "This case is used when the subscription request was 1692 successful."; 1693 leaf identifier { 1694 type subscription-id; 1695 mandatory true; 1696 description 1697 "Identifier used for this subscription."; 1698 } 1699 } 1700 } 1701 augment "result/no-success" { 1702 description 1703 "Contains establish RPC specific objects which can be 1704 returned as hints for future attempts."; 1705 leaf replay-start-time-hint { 1706 type yang:date-and-time; 1707 description 1708 "If a replay has been requested, but the requested replay 1709 time cannot be honored, this may provide a hint at an 1710 alternate time which may be supportable."; 1711 } 1712 } 1713 } 1714 } 1715 } 1717 rpc modify-subscription { 1718 description 1719 "This RPC allows a subscriber to modify a subscription that was 1720 previously created using establish-subscription. If successful, 1721 the changed subscription remains in effect for the duration of 1722 the subscriber's association with the publisher, or until the 1723 subscription is again modified or terminated. In case an error 1724 is returned (as indicated by subscription-result), the 1725 subscription is not modified and the original subscription 1726 parameters remain in effect. In that case, the rpc error 1727 response MAY include suggested parameter hints that would have 1728 a high likelihood of succeeding in a subsequent 1729 modify-subscription request."; 1730 input { 1731 leaf identifier { 1732 type subscription-id; 1733 description 1734 "Identifier to use for this subscription."; 1735 } 1736 uses subscription-policy-modifiable; 1737 } 1738 output { 1739 uses subscription-response-with-hints; 1740 } 1741 } 1743 rpc delete-subscription { 1744 description 1745 "This RPC allows a subscriber to delete a subscription that 1746 was previously created from by that same subscriber using the 1747 establish-subscription RPC."; 1748 input { 1749 leaf identifier { 1750 type subscription-id; 1751 mandatory true; 1752 description 1753 "Identifier of the subscription that is to be deleted. 1754 Only subscriptions that were created using 1755 establish-subscription can be deleted via this RPC."; 1756 } 1757 } 1758 output { 1759 leaf subscription-result { 1760 type subscription-result; 1761 mandatory true; 1762 description 1763 "Indicates whether subscription has been deleted, or if a 1764 problem was encountered."; 1765 } 1766 } 1767 } 1769 rpc kill-subscription { 1770 description 1771 "This RPC allows an operator to delete a dynamic subscription 1772 without restrictions on the originating subscriber or underlying 1773 transport session."; 1774 input { 1775 leaf identifier { 1776 type subscription-id; 1777 mandatory true; 1778 description 1779 "Identifier of the subscription that is to be deleted. Only 1780 subscriptions that were created using establish-subscription 1781 can be deleted via this RPC."; 1782 } 1783 } 1784 output { 1785 leaf subscription-result { 1786 type subscription-result; 1787 mandatory true; 1788 description 1789 "Indicates whether subscription has been killed, or if a 1790 problem was encountered."; 1791 } 1792 } 1793 } 1795 /* 1796 * NOTIFICATIONS 1797 */ 1799 notification replay-completed { 1800 sn:subscription-state-notif; 1801 description 1802 "This notification is sent to indicate that all of the replay 1803 notifications have been sent. It must not be sent for any other 1804 reason."; 1805 leaf identifier { 1806 type subscription-id; 1807 mandatory true; 1808 description 1809 "This references the affected subscription."; 1810 } 1811 } 1813 notification subscription-completed { 1814 sn:subscription-state-notif; 1815 description 1816 "This notification is sent to indicate that a subscription has 1817 finished passing events."; 1819 leaf identifier { 1820 type subscription-id; 1821 mandatory true; 1822 description 1823 "This references the gracefully completed subscription."; 1824 } 1825 } 1827 notification subscription-started { 1828 sn:subscription-state-notif; 1829 description 1830 "This notification indicates that a subscription has started and 1831 notifications are beginning to be sent. This notification shall 1832 only be sent to receivers of a subscription; it does not 1833 constitute a general-purpose notification."; 1834 leaf identifier { 1835 type subscription-id; 1836 mandatory true; 1837 description 1838 "This references the affected subscription."; 1839 } 1840 uses subscription-policy; 1841 } 1843 notification subscription-resumed { 1844 sn:subscription-state-notif; 1845 description 1846 "This notification indicates that a subscription that had 1847 previously been suspended has resumed. Notifications will once 1848 again be sent."; 1849 leaf identifier { 1850 type subscription-id; 1851 mandatory true; 1852 description 1853 "This references the affected subscription."; 1854 } 1855 } 1857 notification subscription-modified { 1858 sn:subscription-state-notif; 1859 description 1860 "This notification indicates that a subscription has been 1861 modified. Notifications sent from this point on will conform to 1862 the modified terms of the subscription. For completeness, this 1863 notification includes both modified and non-modified aspects of 1864 a subscription "; 1865 leaf identifier { 1866 type subscription-id; 1867 mandatory true; 1868 description 1869 "This references the affected subscription."; 1870 } 1871 uses subscription-policy; 1872 } 1874 notification subscription-terminated { 1875 sn:subscription-state-notif; 1876 description 1877 "This notification indicates that a subscription has been 1878 terminated."; 1879 leaf identifier { 1880 type subscription-id; 1881 mandatory true; 1882 description 1883 "This references the affected subscription."; 1884 } 1885 uses error-identifier; 1886 uses hints; 1887 } 1889 notification subscription-suspended { 1890 sn:subscription-state-notif; 1891 description 1892 "This notification indicates that a suspension of the 1893 subscription by the publisher has occurred. No further 1894 notifications will be sent until the subscription resumes. 1895 This notification shall only be sent to receivers of a 1896 subscription; it does not constitute a general-purpose 1897 notification."; 1898 leaf identifier { 1899 type subscription-id; 1900 mandatory true; 1901 description 1902 "This references the affected subscription."; 1903 } 1904 uses error-identifier; 1905 uses hints; 1906 } 1908 /* 1909 * DATA NODES 1910 */ 1912 container streams { 1913 config false; 1914 description 1915 "This container contains information on the built-in streams 1916 provided by the publisher."; 1917 list stream { 1918 key "name"; 1919 description 1920 "Identifies the built-in streams that are supported by the 1921 publisher."; 1922 leaf name { 1923 type stream; 1924 description 1925 "A handle for a sequential set of events, each of which 1926 is characterized by its own domain and semantics. 1927 In case configurable custom streams are supported, 1928 as indicated by the custom-stream identity, the configuration 1929 of those custom streams is provided separately."; 1930 } 1931 leaf description { 1932 type string; 1933 mandatory true; 1934 description 1935 "A description of the event stream, including such information 1936 as the type of events that are sent over this stream."; 1937 } 1938 leaf replay-support { 1939 if-feature "replay"; 1940 type empty; 1941 description 1942 "Indicates that event replay is available on this stream."; 1943 } 1944 leaf replay-log-creation-time { 1945 if-feature "replay"; 1946 type yang:date-and-time; 1947 description 1948 "The timestamp of the creation of the log used to support the 1949 replay function on this stream. Note that this might be 1950 earlier then the earliest available notification in the log. 1951 This object is updated if the log resets for some reason. 1952 This object MUST be present if replay is supported."; 1953 } 1954 leaf replay-log-aged-time { 1955 if-feature "replay"; 1956 type yang:date-and-time; 1957 description 1958 "The timestamp of the last notification aged out of the log. 1959 This object MUST be present if replay is supported and any 1960 notifications have been aged out of the log."; 1961 } 1962 } 1964 } 1966 container filters { 1967 description 1968 "This container contains a list of configurable filters 1969 that can be applied to subscriptions. This facilitates 1970 the reuse of complex filters once defined."; 1971 list event-filter { 1972 key "identifier"; 1973 description 1974 "A list of pre-positioned filters that can be applied to 1975 event subscriptions."; 1976 leaf identifier { 1977 type filter-id; 1978 description 1979 "An identifier to differentiate between filters."; 1980 } 1981 uses event-filter-elements; 1982 } 1983 } 1985 container subscription-config { 1986 if-feature "configured-subscriptions"; 1987 description 1988 "Contains the list of subscriptions that are configured, 1989 as opposed to established via RPC or other means."; 1990 list subscription { 1991 key "identifier"; 1992 description 1993 "Content of a subscription."; 1994 leaf identifier { 1995 type subscription-id; 1996 description 1997 "Identifier to use for this subscription."; 1998 } 1999 uses subscription-policy; 2000 uses receiver-info; 2001 uses notification-origin-info; 2002 } 2003 } 2004 container subscriptions { 2005 config false; 2006 description 2007 "Contains the list of currently active subscriptions, i.e. 2008 subscriptions that are currently in effect, used for subscription 2009 management and monitoring purposes. This includes subscriptions 2010 that have been setup via RPC primitives as well as subscriptions 2011 that have been established via configuration."; 2013 list subscription { 2014 key "identifier"; 2015 description 2016 "Content of a subscription. Subscriptions can be created using 2017 a control channel or RPC, or be established through 2018 configuration."; 2019 leaf identifier { 2020 type subscription-id; 2021 description 2022 "Identifier of a subscription; unique within a publisher"; 2023 } 2024 leaf configured-subscription { 2025 if-feature "configured-subscriptions"; 2026 type empty; 2027 description 2028 "The presence of this leaf indicates that the subscription 2029 originated from configuration, not through a control channel 2030 or RPC."; 2031 } 2032 uses subscription-policy; 2033 uses notification-origin-info { 2034 if-feature "configured-subscriptions"; 2035 } 2036 uses receiver-info { 2037 augment receivers/receiver { 2038 description 2039 "include operational data for receivers."; 2040 leaf pushed-notifications { 2041 type yang:counter64; 2042 description 2043 "Operational data which provides the number of update 2044 notifications pushed to a receiver."; 2045 } 2046 leaf excluded-notifications { 2047 type yang:counter64; 2048 description 2049 "Operational data which provides the number of events 2050 from a stream explicitly removed via filtering so that 2051 they are not sent to a receiver."; 2052 } 2053 leaf status { 2054 type subscription-status; 2055 mandatory true; 2056 description 2057 "The status of the subscription."; 2058 } 2059 } 2060 } 2062 } 2063 } 2064 } 2065 2067 11. Considerations 2069 11.1. Implementation Considerations 2071 For a deployment including both configured and dynamic subscriptions, 2072 split subscription identifiers into static and dynamic halves. That 2073 way it is unlikely there will be collisions if the configured 2074 subscriptions attempt to set a subscription-id which might have 2075 already been dynamically allocated. The lower half SHOULD be used 2076 for configured subscriptions and upper half for dynamic. 2078 The elements are never sent before the transport 2079 layer, including capabilities exchange, has been established. 2081 It is left to an implementation to determine when to transition 2082 between active and suspended subscription states. However if a 2083 subscription is unable to marshal all intended updates into a 2084 transmittable message in multiple successive intervals, the 2085 subscription SHOULD be suspended with the reason "unsupportable- 2086 volume". 2088 11.2. Security Considerations 2090 For dynamic subscriptions the publisher MUST authenticate and 2091 authorize all RPC requests. 2093 Subscriptions could overload a publisher's CPU. For this reason, the 2094 publisher MUST have the ability to decline a dynamic subscription 2095 request, and provide the appropriate RPC error response to a 2096 subscriber should the proposed subscription overly deplete the 2097 publisher's resources. 2099 A publisher needs to be able to suspend an existing dynamic or 2100 configured subscription based on capacity constraints. When this 2101 occurs, the subscription status MUST be updated accordingly and the 2102 receivers notified with subscription state notifications. 2104 If a malicious or buggy subscriber sends an unexpectedly large number 2105 of RPCs, the result might be an exessive use of system resources. In 2106 such a situation, subscription interactions MAY be terminated by 2107 terminating the transport session. 2109 For both configured and dynamic subscriptions the publisher MUST 2110 authenticate and authorize a receiver via some transport level 2111 mechanism before sending any updates. 2113 A secure transport is highly recommended and the publisher MUST 2114 ensure that the user has sufficient authorization to perform the 2115 function they are requesting against the specific subset of content 2116 involved. 2118 A publisher MUST NOT include any content in a notification for which 2119 the user has not been authorized. 2121 With configured subscriptions, one or more publishers could be used 2122 to overwhelm a receiver. No push updates SHOULD be sent to any 2123 receiver which doesn't even support subscriptions. Subscribers that 2124 do not want pushed data need only terminate or refuse any transport 2125 sessions from the publisher. 2127 The NETCONF Authorization Control Model [RFC6536bis] SHOULD be used 2128 to control and restrict authorization of subscription configuration. 2129 This control models permits specifying per-user permissions to 2130 receive events from specific streams. 2132 Where NACM is available, the NACM "very-secure" tag MUST be placed on 2133 the RPC so that only administrators have access 2134 to use this. 2136 One subscription id can be used for two or more receivers of the same 2137 configured subscription. But due to the possibility of different 2138 access control permissions per receiver, it SHOULD NOT be assumed 2139 that each receiver is getting identical updates. 2141 12. Acknowledgments 2143 For their valuable comments, discussions, and feedback, we wish to 2144 acknowledge Andy Bierman, Tim Jenkins, Martin Bjorklund, Balazs 2145 Lengyel, Sharon Chisholm, Hector Trevino, Susan Hares, Kent Watsen, 2146 Michael Scharf, and Guangying Zheng. 2148 13. References 2150 13.1. Normative References 2152 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2153 Requirement Levels", BCP 14, RFC 2119, 2154 DOI 10.17487/RFC2119, March 1997, 2155 . 2157 [RFC6536bis] 2158 Bierman, A. and M. Bjorklund, "Network Configuration 2159 Protocol (NETCONF) Access Control Model", draft-ietf- 2160 netconf-rfc6536bis-01 (work in progress), September 2017. 2162 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 2163 RFC 7950, DOI 10.17487/RFC7950, August 2016, 2164 . 2166 [XPATH] Clark, J. and S. DeRose, "XML Path Language (XPath) 2167 Version 1.0", November 1999, 2168 . 2170 13.2. Informative References 2172 [I-D.ietf-netconf-event-notif] 2173 Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto., 2174 Nilsen-Nygaard, E., Tripathy, A., Chisholm, S., and H. 2175 Trevino, "NETCONF support for event notifications", August 2176 2016, . 2179 [I-D.ietf-netconf-restconf-notif] 2180 Voit, Eric., Clemm, Alexander., Tripathy, A., Nilsen- 2181 Nygaard, E., and Alberto. Gonzalez Prieto, "Restconf and 2182 HTTP transport for event notifications", August 2016, 2183 . 2186 [I-D.ietf-netconf-yang-push] 2187 Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto., 2188 Tripathy, A., Nilsen-Nygaard, E., Bierman, A., and B. 2189 Lengyel, "Subscribing to YANG datastore push updates", 2190 June 2017, . 2193 [I-D.notification-messages] 2194 Voit, Eric., Clemm, Alexander., Bierman, A., and T. 2195 Jenkins, "YANG Notification Headers and Bundles", 2196 September 2017, . 2199 [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event 2200 Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008, 2201 . 2203 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 2204 and A. Bierman, Ed., "Network Configuration Protocol 2205 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 2206 . 2208 [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext 2209 Transfer Protocol Version 2 (HTTP/2)", RFC 7540, 2210 DOI 10.17487/RFC7540, May 2015, 2211 . 2213 [RFC7923] Voit, E., Clemm, A., and A. Gonzalez Prieto, "Requirements 2214 for Subscription to YANG Datastores", RFC 7923, 2215 DOI 10.17487/RFC7923, June 2016, 2216 . 2218 [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", 2219 RFC 7951, DOI 10.17487/RFC7951, August 2016, 2220 . 2222 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 2223 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 2224 . 2226 Appendix A. Changes between revisions 2228 (To be removed by RFC editor prior to publication) 2230 v09 - v10 2232 o Returned to the explicit filter subtyping of v00 2234 o stream object changed to 'name' from 'stream' 2236 o Cleaned up examples 2238 o Clarified that JSON support needs notification-messages draft. 2240 v03 - v04 2242 o Moved back to the use of RFC5277 one-way notifications and 2243 encodings. 2245 v03 - v04 2247 o Replay updated 2249 v02 - v03 2250 o RPCs and Notification support is identified by the Notification 2251 2.0 capability. 2253 o Updates to filtering identities and text 2255 o New error type for unsupportable volume of updates 2257 o Text tweaks. 2259 v01 - v02 2261 o Subscription status moved under receiver. 2263 v00 - v01 2265 o Security considerations updated 2267 o Intro rewrite, as well as scattered text changes 2269 o Added Appendix A, to help match this to related drafts in progress 2271 o Updated filtering definitions, and filter types in yang file, and 2272 moved to identities for filter types 2274 o Added Syslog as a stream 2276 o HTTP2 moved in from YANG-Push as a transport option 2278 o Replay made an optional feature for events. Won't apply to 2279 datastores 2281 o Enabled notification timestamp to have different formats. 2283 o Two error codes added. 2285 v01 5277bis - v00 subscribed notifications 2287 o Kill subscription RPC added. 2289 o Renamed from 5277bis to Subscribed Notifications. 2291 o Changed the notification capabilities version from 1.1 to 2.0. 2293 o Extracted create-subscription and other elements of RFC5277. 2295 o Error conditions added, and made specific in return codes. 2297 o Simplified yang model structure for removal of 'basic' grouping. 2299 o Added a grouping for items which cannot be statically configured. 2301 o Operational counters per receiver. 2303 o Subscription-id and filter-id renamed to identifier 2305 o Section for replay added. Replay now cannot be configured. 2307 o Control plane notification renamed to subscription state 2308 notification 2310 o Source address: Source-vrf changed to string, default address 2311 option added 2313 o In yang model: 'info' changed to 'policy' 2315 o Scattered text clarifications 2317 v00 - v01 of 5277bis 2319 o YANG Model changes. New groupings for subscription info to allow 2320 restriction of what is changeable via RPC. Removed notifications 2321 for adding and removing receivers of configured subscriptions. 2323 o Expanded/renamed definitions from event server to publisher, and 2324 client to subscriber as applicable. Updated the definitions to 2325 include and expand on RFC 5277. 2327 o Removal of redundancy with other drafts 2329 o Many other clean-ups of wording and terminology 2331 Authors' Addresses 2333 Eric Voit 2334 Cisco Systems 2336 Email: evoit@cisco.com 2338 Alexander Clemm 2339 Huawei 2341 Email: ludwig@clemm.org 2342 Alberto Gonzalez Prieto 2343 VMWare 2345 Email: agonzalezpri@vmware.com 2347 Einar Nilsen-Nygaard 2348 Cisco Systems 2350 Email: einarnn@cisco.com 2352 Ambika Prasad Tripathy 2353 Cisco Systems 2355 Email: ambtripa@cisco.com