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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Interface to the Routing System (i2rs) E. Voit 3 Internet-Draft A. Clemm 4 Intended status: Informational A. Gonzalez Prieto 5 Expires: October 17, 2016 Cisco Systems 6 April 15, 2016 8 Requirements for Subscription to YANG Datastores 9 draft-ietf-i2rs-pub-sub-requirements-06 11 Abstract 13 This document provides requirements for a service that allows client 14 applications to subscribe to updates of a YANG datastore. Based on 15 criteria negotiated as part of a subscription, updates will be pushed 16 to targeted recipients. Such a capability eliminates the need for 17 periodic polling of YANG datastores by applications and fills a 18 functional gap in existing YANG transports (i.e. Netconf and 19 Restconf). Such a service can be summarized as a "pub/sub" service 20 for YANG datastore updates. Beyond a set of basic requirements for 21 the service, various refinements are addressed. These refinements 22 include: periodicity of object updates, filtering out of objects 23 underneath a requested a subtree, and delivery QoS guarantees. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at http://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on October 17, 2016. 42 Copyright Notice 44 Copyright (c) 2016 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Business Drivers . . . . . . . . . . . . . . . . . . . . . . 3 61 2.1. Pub/Sub in I2RS . . . . . . . . . . . . . . . . . . . . . 3 62 2.2. Pub/Sub variants on Network Elements . . . . . . . . . . 5 63 2.3. Existing Generalized Pub/Sub Implementations . . . . . . 5 64 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7 66 4.1. Assumptions for Subscriber Behavior . . . . . . . . . . . 7 67 4.2. Subscription Service Requirements . . . . . . . . . . . . 7 68 4.2.1. General . . . . . . . . . . . . . . . . . . . . . . . 7 69 4.2.2. Negotiation . . . . . . . . . . . . . . . . . . . . . 9 70 4.2.3. Update Distribution . . . . . . . . . . . . . . . . . 9 71 4.2.4. Transport . . . . . . . . . . . . . . . . . . . . . . 10 72 4.2.5. Security Requirements . . . . . . . . . . . . . . . . 11 73 4.2.6. Subscription QoS . . . . . . . . . . . . . . . . . . 11 74 4.2.7. Filtering . . . . . . . . . . . . . . . . . . . . . . 13 75 4.2.8. Assurance and Monitoring . . . . . . . . . . . . . . 13 76 5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 77 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 78 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 79 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 80 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 81 8.2. Informative References . . . . . . . . . . . . . . . . . 15 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 84 1. Introduction 86 Applications interacting with YANG datastores require capabilities 87 beyond the traditional client-server configuration of network 88 elements. One class of such applications are service-assurance 89 applications which must maintain a continuous view of operational 90 data and state. Another class of applications are security 91 applications which must continuously track changes made upon network 92 elements to ensure compliance to corporate policy. 94 Periodic fetching of data is not an adequate solution for 95 applications requiring frequent or prompt updates of remote object 96 state. Applying polling-based solutions here imposes load on 97 networks, devices, and applications. Additionally, polling solutions 98 are brittle in the face of communication glitches, and have 99 limitations in their ability to synchronize and calibrate retrieval 100 intervals across a network. These limitations can be addressed by 101 including generic object subscription mechanisms within Network 102 Elements, and allowing these mechanisms to be applied in the context 103 of data that is conceptually contained in YANG datastores. 105 This document aggregates requirements for such subscription from a 106 variety of deployment scenarios. 108 2. Business Drivers 110 For decades, information delivery of current network state has been 111 accomplished either by fetching from operations interfaces, or via 112 dedicated, customized networking protocols. With the growth of 113 centralized orchestration infrastructures, imperative policy 114 distribution, and YANG's ascent as the dominant data modeling 115 language for use in programmatic interfaces to network elements, this 116 mixture of fetch plus custom networking protocols is no longer 117 sufficient. What is needed is a push mechanism that is able to 118 deliver object changes as they happen. 120 These push distribution mechanisms will not replace existing 121 networking protocols. Instead they will supplement these protocols, 122 providing different response time, peering, scale, and security 123 characteristics. 125 Push solutions will not displace all existing operations 126 infrastructure needs. And SNMP and MIBs will remain widely deployed 127 and the defacto choice for many monitoring solutions. But some 128 functions could be displaced. Arguably the biggest shortcoming of 129 SNMP for those applications concerns the need to rely on periodic 130 polling, because it introduces additional load on the network and 131 devices, because it is brittle in case polling cycles are missed, and 132 because is hard to synchronize and calibrate across a network. If 133 applications can only use polling type interaction patterns with YANG 134 datastores, similar issues can be expected. 136 2.1. Pub/Sub in I2RS 138 Various I2RS documents highlight the need to provide Pub/Sub 139 capabilities between network elements. From [i2rs-arch], there are 140 references throughout the document beginning in section 6.2. Some 141 specific examples include: 143 o section 7.6 provides high level pub/sub (notification) guidance 144 o section 6.4.2 identifies "subscribing to an information stream of 145 route changes receiving notifications about peers coming up or 146 going down" 148 o section 6.3 notes that when local config preempts I2RS, external 149 notification might be necessary 151 In addition [i2rs-usecase] has relevant requirements. A small subset 152 includes: 154 o L-Data-REQ-12: The I2RS interface should support user 155 subscriptions to data with the following parameters: push of data 156 synchronously or asynchronously via registered subscriptions... 158 o L-DATA-REQ-07: The I2RS interface (protocol and IMs) should allow 159 a subscriber to select portions of the data model. 161 o PI-REQ01: monitor the available routes installed in the RIB of 162 each forwarding device, including near real time notification of 163 route installation and removal. 165 o BGP-REQ10: I2RS client should be able to instruct the I2RS 166 agent(s) to notify the I2RS client when the BGP processes on an 167 associated routing system observe a route change to a specific set 168 of IP Prefixes and associated prefixes....The I2RS agent should be 169 able to notify the client via publish or subscribe mechanism. 171 o IGP-REQ-07: The I2RS interface (protocol and IMs) should support a 172 mechanism where the I2RS Clients can subscribe to the I2RS Agent's 173 notification of critical node IGP events. 175 o MPLS-LDP-REQ-03: The I2RS Agent notifications should allow an I2RS 176 client to subscribe to a stream of state changes regarding the LDP 177 sessions or LDP LSPs from the I2RS Agent. 179 o L-Data-REQ-01: I2rs must be able to collect large data set from 180 the network with high frequency and resolution with minimal impact 181 to the device's CPU and memory. 183 And [i2rs-traceability] has Pub/Sub requirements listed in 184 Section 7.4.3. 186 o I2RS Agents should support publishing I2RS trace log information 187 to that feed as described in [i2rs-arch]. Subscribers would then 188 receive a live stream of I2RS interactions in trace log format and 189 could flexibly choose to do a number of things with the log 190 messages 192 2.2. Pub/Sub variants on Network Elements 194 This document is intended to cover requirements beyond I2RS. Looking 195 at history, there are many examples of switching and routing 196 protocols which have done explicit or implicit pub/sub in the past. 197 In addition, new policy notification mechanisms which operate on 198 Switches and Routers are being specified now. A small subset of 199 current and past subscriptions includes: 201 o Multicast topology establishment is accomplished before any 202 content delivery is made to endpoints (IGMP, PIM, etc.) 204 o Secure Automation and Continuous Monitoring (SACM) allows 205 subscription into devices which then may push spontaneous changes 206 in their configured hardware and software[sacm-requirements] 208 o In MPLS VPNs [RFC6513] a Customer Edge router exchanges PIM 209 control messages before PE Routing Adjacencies are passed. 210 [RFC6513] 212 o After OSPF establishes its adjacencies, Link State Advertisement 213 will then commence [RFC2328] 215 Worthy of note in the examples above is the wide variety of 216 underlying transports. A generalized Pub/Sub mechanism therefore 217 should be structured to support alternative transports. Based on 218 current I2RS requirements, NETCONF should the initially supported 219 transport based on the need for connection-oriented/unicast 220 communication. Eventual support Multicast and Broadcast subscription 221 update distribution will be needed as well. 223 2.3. Existing Generalized Pub/Sub Implementations 225 TIBCO, RSS, CORBA, and other technologies all show precursor Pub/Sub 226 technologies. However there are new needs described in Section 4 227 below which these technologies do not serve. We need a new pub-sub 228 technology. 230 There are at least two widely deployed generalized pub/sub 231 implementations which come close to current needs: XMPP[XEP-0060] and 232 DDS[OMG-DDS]. Both serve as proof-points that a highly scalable 233 distributed datastore implementation connecting millions of edge 234 devices is possible. 236 Because of these proof points, we can be comfortable that the 237 underlying technologies can enable reusable generalized YANG object 238 distribution. Analysis will need to fully dimension the speed and 239 scale of such object distribution for various subtree sizes and 240 transport types. 242 3. Terminology 244 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 245 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 246 document are to be interpreted as described in [RFC2119]. 248 A Subscriber makes requests for set(s) of YANG object data. 250 A Publisher is responsible for distributing subscribed YANG object 251 data per the terms of a Subscription. In general, a Publisher is the 252 owner of the YANG datastore that is subjected to the Subscription. 254 A Receiver is the target to which a Publisher pushes updates. In 255 general, the Receiver and Subscriber will be the same entity. A 256 Subscription Service provides Subscriptions to Subscribers of YANG 257 data. 259 A Subscription Service interacts with the Publisher of the YANG data 260 as needed to provide the data per the terms of the Subscription. 262 A Subscription Request for one or more YANG subtrees (including 263 single leafs) is made by the Subscriber of a Publisher and is 264 targeted to a Receiver. A Subscription may include constraints which 265 dictate how often or under what conditions YANG information updates 266 might be sent. 268 A Subscription is a contract between a Subscription Service and a 269 Subscriber that stipulates the data to be pushed and the associated 270 terms. 272 A YANG datastore is a conceptual datastore that contains hierarchical 273 data defined in YANG data models. It is what is referred in existing 274 RFCs as "NETCONF datastore". However, as the same datastore is no 275 longer tied to NETCONF as a specific transport, the term "YANG 276 datastore" is deemed more appropriate. 278 An Update provides object changes which have occurred within 279 subscribed YANG subtree(s). An Update must include the current 280 status of (data) node instances which according to any filtering are 281 reportably different from the previously provided state. An Update 282 may include a bundled set of ordered/sequential changes for a given 283 object which have been made since the last update. 285 A Filter contains evaluation criteria which are evaluated against 286 YANG object(s) within a Subscription. There are two types of 287 Filters: Subtree Filters which identify selected objects/nodes 288 published under a target data node, and object Property Filters where 289 an object should only be published if it has propert(ies) meeting 290 specified Filter criteria. For "on-change" notifications, passing 291 through the Filter requires that a subscribed object is now different 292 that from the previous Push, AND at least one of the YANG objects 293 being evaluated has changed since the last Update. 295 4. Requirements 297 Many of the requirements within this section have been morphed from 298 XMPP[XEP-0060] and DDS[OMG-DDS] requirements specifications. 300 4.1. Assumptions for Subscriber Behavior 302 This document provides requirements for the Subscription Service. It 303 does not define all the requirements for the Subscriber/Receiver. 304 However in order to frame the desired behavior of the Subscription 305 Service, it is important to specify key input constraints. 307 A Subscriber SHOULD avoid attempting to establish multiple 308 Subscriptions pertaining to the same information, i.e. referring to 309 the same datastore YANG subtrees. 311 A Subscriber MAY provide Subscription QoS criteria to the 312 Subscription Service; if the Subscription Service is unable to meet 313 those criteria, the Subscription SHOULD NOT be established. 315 When a Subscriber needs to restart, the Subscriber MAY have to 316 resubscribe. There is no requirement for the life span of the 317 Subscription to extend beyond the life span of the Subscriber. 319 A Subscriber MUST be able to infer when a Subscription Service is no 320 longer active and when no more updates are being sent. 322 A Subscriber MAY check with a Subscription Service to validate the 323 existence and monitored subtrees of a Subscription. 325 A Subscriber MUST be able to periodically lease and extend the lease 326 a Subscription from a Subscription Service. 328 4.2. Subscription Service Requirements 330 4.2.1. General 332 A Subscription Service MUST support the ability to create, renew, 333 timeout, and terminate a Subscription. 335 A Subscription Service MUST be able to support and independently 336 track one or more Subscription Requests by the same Subscriber. 338 A Subscription Service MUST be able to support an add/change/delete 339 of one or more YANG subtrees as part of the same Subscription 340 Request. 342 A Subscription Service MUST support Subscriptions against operational 343 datastores, configuration datastores, or both. 345 A Subscription Service MUST be able support a Subtree Filter so that 346 subscribed updates under a target node might publish only operational 347 data, only configuration data, or both. 349 A Subscription MAY include filters as defined within a Subscription 350 Request, therefore the Subscription Service MUST publish only data 351 nodes that meet the filter criteria within a Subscription. 353 A Subscription Service MUST support the ability to subscribe to 354 periodic updates. The subscription period MUST be configurable as 355 part of the subscription request. 357 A Subscription Service SHOULD support the ability to subscribe to 358 updates "on-change", i.e., whenever values of subscribed data objects 359 change. 361 For "on-change" updates, the Subscription Service MUST support a 362 dampening period that needs to pass before the first or subsequent 363 "on-change" updates are sent. The dampening period SHOULD be 364 configurable as part of the subscription request. 366 A Subscription Service MUST allow Subscriptions to be monitored. 367 Specifically, a Subscription Service MUST at a minimum maintain 368 information about which Subscriptions are being serviced, the terms 369 of those subscriptions (e.g., what data is being subscribed, 370 associated filters, update policy - on change, periodic), and the 371 overall status of the Subscription - e.g., active or suspended. 373 A Subscription Service SHOULD be able to interpret Subscription QoS 374 parameters, and only establish a Subscription if it is possible to 375 meet the QoS needs of the provided QoS parameters. 377 A Subscription Service MUST support terminating of a Subscription 378 when requested by the Subscriber. 380 A Subscription Service SHOULD support the ability to suspend and to 381 resume a Subscription on request of a client. 383 A Subscription Service MAY at its discretion revoke or suspend an 384 existing subscription. Reasons may include transitory resource 385 limitation, credential expiry, failure to reconfirm a subscription, 386 loss of connectivity with the Receiver, operator CLI, and/or others. 387 When this occurs, the Subscription Service MUST notify the Subscriber 388 and update subscription status. 390 A Subscription Service MAY offer the ability to modify a subscription 391 filter. If such an ability is offered, the service MUST provide 392 subscribers with an indication telling at what point the modified 393 subscription goes into effect. 395 4.2.2. Negotiation 397 A Subscription Service MUST be able to negotiate the following terms 398 of a Subscription: 400 o The policy: i.e. whether updates are on-change or periodic 402 o The interval, for periodic publication policy 404 o The dampening period, for on-change update policy (if supported) 406 o Any filters associated with a subtree subscription 408 A Subscription Service SHOULD be able to negotiate QoS criteria for a 409 Subscription. Examples of Subscription QoS criteria may include 410 reliability of the Subscription Service, reaction time between a 411 monitored YANG subtree/object change and a corresponding notification 412 push, and the Subscription Service's ability to support certain 413 levels of object liveliness. 415 In cases where a Subscription Request cannot be fulfilled, the 416 Subscription Service MUST include in its decline a set of criteria 417 that would have been acceptable when the Subscription Request was 418 made. For example, if periodic updates were requested with too short 419 update intervals for the specified data set, an alternative 420 acceptable interval period might be returned from the Publisher. If 421 on-change updates were requested with too-aggressive a dampening 422 period, then an acceptable dampening period may be returned, or 423 alternatively an indication that only periodic updates are supported 424 for the requested object(s). 426 4.2.3. Update Distribution 428 For "on-change" updates, the Subscription Service MUST only send 429 deltas to the object data for which a change occurred. [Otherwise 430 the subscriber might not know what has actually undergone change.] 431 The updates for each object MUST include an indication whether it was 432 removed, added, or changed. 434 When a Subscription Service is not able to send updates per its 435 subscription contract, the Subscription MUST notify subscribers and 436 put the subscription into a state indicating the Subscription was 437 suspended by the service. When able to resume service, subscribers 438 need to be notified as well. If unable to resume service, the 439 Subscription Service MAY terminate the subscription and notify 440 Subscribers accordingly. 442 When a Subscription with "on-change" updates is suspended and then 443 resumed, the first update SHOULD include updates of any changes that 444 occurred while the Subscription was suspended, with the current 445 value. The Subscription Service MUST provide a clear indication when 446 this capability is not supported (because in this case a client 447 application may have to synchronize state separately). 449 Multiple objects being pushed to a Subscriber, perhaps from different 450 Subscriptions, SHOULD be bundled together into a single Update. 452 The sending of an Update MUST NOT be delayed beyond the Push Latency 453 of any enclosed object changes. 455 The sending of an Update MUST NOT be delayed beyond the dampening 456 period of any enclosed object changes. 458 The sending of an Update MUST NOT occur before the dampening period 459 expires for any enclosed object changes. 461 A Subscription Service MAY, as an option, support a persistence/ 462 replay capability. 464 4.2.4. Transport 466 A Subscription Service SHOULD support different transports. 468 A Subscription Service SHOULD support different encodings of payload. 470 It MUST be possible for Receivers to associate the update with a 471 specific Subscription. 473 In the case of connection-oriented transport, when a transport 474 connection drops, the associated Subscription SHOULD be terminated. 475 It is up the Subscriber to request a new Subscription. 477 4.2.5. Security Requirements 479 As part of the Subscription establishment, there MUST be mutual 480 authentication between the Subscriber and the Subscription Service. 482 When there are multiple Subscribers, it SHOULD be possible to provide 483 cryptographic authentication in such a way that no Subscriber can 484 pose as the original Subscription Service. 486 Versioning MUST be supported. 488 A Subscription could be used to attempt to retrieve information that 489 a client has not authorized access to. Therefore it is important 490 that data pushed based on Subscriptions is authorized in the same way 491 that regular data retrieval operations are authorized. Data being 492 pushed to a client MUST be filtered accordingly, just like if the 493 data were being retrieved on-demand. For Unicast transports, the 494 NETCONF Authorization Control Model applies. 496 Additions or changes within a subscribed subtree structure MUST be 497 validated against authorization methods before Subscription Updates 498 including new subtree information are pushed. 500 A loss of authenticated access to subtree or node SHOULD be 501 communicated to the Subscriber. 503 Subscription requests, including requests to create, terminate, 504 suspend, and resume Subscriptions MUST be properly authorized. 506 When the Subscriber and Receiver are different, the Receiver MUST be 507 able to terminate any Subscription to it where objects are being 508 delivered over a Unicast transport. 510 A Subscription Service SHOULD decline a Subscription Request if it is 511 likely to deplete its resources. It is preferable to decline a 512 Subscription when originally requested, rather than having to 513 terminate it prematurely later. 515 4.2.6. Subscription QoS 517 A Subscription Service SHOULD be able to negotiate the following 518 Subscription QoS parameters with a Subscriber: Dampening, 519 Reliability, Deadline, and Bundling. 521 4.2.6.1. Liveliness 523 A Subscription Service MUST be able to respond to requests to verify 524 the Liveliness of a subscription. 526 A Subscription Service MUST be able to report the currently monitored 527 Nodes of a Subscription. 529 4.2.6.2. Dampening 531 A Subscription Service MUST be able to negotiate the minimum time 532 separation since the previous update before transmitting a subsequent 533 update for Subscription. (Note: this is intended to confine the 534 visibility of volatility into something digestible by the receiver.) 536 4.2.6.3. Reliability 538 A Subscription Service MAY send Updates over Best Effort and Reliable 539 transports. 541 4.2.6.4. Coherence 543 For a particular Subscription, every update to a subscribed object 544 MUST be sent to the Receiver in sequential order. 546 4.2.6.5. Presentation 548 The Subscription Service MAY have the ability to bundle a set of 549 discrete object notifications into a single publishable update for a 550 Subscription. A bundle MAY include information on different Data 551 Nodes and/or multiple updates about a single Data Node. 553 For any bundled updates, the Subscription Service MUST provide 554 information for a Receiver to reconstruct the order and timing of 555 updates. 557 4.2.6.6. Deadline 559 The Subscription Service MUST be able to push updates at a regular 560 cadence that corresponds with Subscriber specified start and end 561 timestamps. (Note: the regular cadence can drive one, a discrete 562 quantity, or an unbounded set of periodic updates.) 564 4.2.6.7. Push Latency 566 The Subscription Service SHOULD be able to delay Updates on object 567 push for a configurable period per Subscriber. 569 It MUST be possible for an administrative entity to determine the 570 Push latency between object change in a monitored subtree and the 571 Subscription Service Push of the update transmission. 573 4.2.7. Filtering 575 If no filtering criteria are provided, or if filtering criteria are 576 met, updates for a subscribed object MUST be pushed, subject to the 577 QoS limits established for the subscription. 579 It MUST be possible for the Subscription Service to receive Filter(s) 580 from a Subscriber and apply them to corresponding object(s) within a 581 Subscription. 583 It MUST be possible to attach one or more Subtree and/or Property 584 Filters to a subscription. Mandatory Property Filter types include: 586 o For character-based object properties, filter values which are 587 exactly equal to a provided string, not equal to the string, or 588 containing a string. 590 o For numeric based object properties, filter values which are =, 591 !=, <, <=, >, >= a provided number. 593 It SHOULD be possible for Property Filtering criteria to evaluate 594 more than one property of a particular subscribed object as well as 595 apply multiple filters against a single property. 597 It SHOULD be possible to establish query match criteria on additional 598 objects to be used in conjunction with Property Filtering criteria on 599 a subscribed object. (For example: if A has changed AND B=1, then 600 Push A.) Query match capability may be done on objects within the 601 datastore even if those objects are not included within the 602 subscription. This of course assumes the subscriber has read access 603 to those objects. 605 4.2.8. Assurance and Monitoring 607 It MUST be possible to fetch the state of a single subscription from 608 a Subscription Service. 610 It MUST be possible to fetch the state of all subscriptions of a 611 particular Subscriber. 613 It MUST be possible to fetch a list and status of all Subscription 614 Requests over a period of time. If there us a failure, some failure 615 reasons MAY include: 617 o Improper security credentials provided to access the target node; 619 o Target node referenced does not exist; 621 o Subscription type requested is not available upon the target node; 623 o Out of resources, or resources not available; 625 o Incomplete negotiations with the Subscriber. 627 5. Security Considerations 629 There are no additional security considerations beyond the 630 requirements listed in Section 4.2.5. 632 6. IANA Considerations 634 This document has no actions for IANA. 636 7. Acknowledgements 638 We wish to acknowledge the helpful contributions, comments, and 639 suggestions that were received from Ambika Tripathy and Prabhakara 640 Yellai as well as the helpfulness of related end-to-end system 641 context info from Nancy Cam Winget, Ken Beck, and David McGrew. 643 8. References 645 8.1. Normative References 647 [i2rs-arch] 648 Atlas, A., "An Architecture for the Interface to the 649 Routing System", February 2016, 650 . 653 [i2rs-traceability] 654 Clarke, J., Salgueiro, G., and C. Pignataro, "Interface to 655 the Routing System (I2RS) Traceability: Framework and 656 Information Model", February 2016, 657 . 660 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 661 Requirement Levels", BCP 14, RFC 2119, 662 DOI 10.17487/RFC2119, March 1997, 663 . 665 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 666 DOI 10.17487/RFC2328, April 1998, 667 . 669 [RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/ 670 BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February 671 2012, . 673 8.2. Informative References 675 [i2rs-usecase] 676 Hares, S. and M. Chen, "Summary of I2RS Use Case 677 Requirements", March 2016, 678 . 681 [OMG-DDS] "Data Distribution Service for Real-time Systems, version 682 1.2", January 2007, . 684 [sacm-requirements] 685 Cam Winget, N., "Secure Automation and Continuous 686 Monitoring (SACM) Requirements", March 2016, 687 . 690 [XEP-0060] 691 Millard, P., "XEP-0060: Publish-Subscribe", July 2010, 692 . 694 Authors' Addresses 696 Eric Voit 697 Cisco Systems 699 Email: evoit@cisco.com 701 Alexander Clemm 702 Cisco Systems 704 Email: alex@cisco.com 706 Alberto Gonzalez Prieto 707 Cisco Systems 709 Email: albertgo@cisco.com