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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC6991' is defined on line 686, but no explicit reference was found in the text Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Clemm 3 Internet-Draft Y. Qu 4 Intended status: Standards Track Futurewei 5 Expires: November 25, 2021 J. Tantsura 6 Apstra 7 A. Bierman 8 YumaWorks 9 May 24, 2021 11 Comparison of NMDA datastores 12 draft-ietf-netmod-nmda-diff-08 14 Abstract 16 This document defines an RPC operation to compare management 17 datastores that comply with the NMDA architecture. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at https://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on November 25, 2021. 36 Copyright Notice 38 Copyright (c) 2021 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (https://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 3 56 4. Data Model Overview . . . . . . . . . . . . . . . . . . . . . 4 57 5. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . . 6 58 6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 59 7. Performance Considerations . . . . . . . . . . . . . . . . . 14 60 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 61 8.1. Updates to the IETF XML Registry . . . . . . . . . . . . 15 62 8.2. Updates to the YANG Module Names Registry . . . . . . . . 15 63 9. Security Considerations . . . . . . . . . . . . . . . . . . . 15 64 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 65 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 66 11.1. Normative References . . . . . . . . . . . . . . . . . . 16 67 11.2. Informative References . . . . . . . . . . . . . . . . . 17 68 Appendix A. Possible Future Extensions . . . . . . . . . . . . . 17 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 71 1. Introduction 73 The revised Network Management Datastore Architecture (NMDA) 74 [RFC8342] introduces a set of new datastores that each hold YANG- 75 defined data [RFC7950] and represent a different "viewpoint" on the 76 data that is maintained by a server. New YANG datastores that are 77 introduced include , which contains validated configuration 78 data that a client application intends to be in effect, and 79 , which contains operational state data (such as 80 statistics) as well as configuration data that is actually in effect. 82 NMDA introduces in effect a concept of "lifecycle" for management 83 data, distinguishing between data that is part of a configuration 84 that was supplied by a user, configuration data that has actually 85 been successfully applied and that is part of the operational state, 86 and overall operational state that includes both applied 87 configuration data as well as status and statistics 89 As a result, data from the same management model can be reflected in 90 multiple datastores. Clients need to specify the target datastore to 91 be specific about which viewpoint of the data they want to access. 92 For example, a client application can differentiate whether they are 93 interested in the configuration supplied to a server and that is 94 supposed to be in effect, or the configuration that has been applied 95 and is actually in effect on the server. 97 Due to the fact that data can propagate from one datastore to 98 another, it is possible for differences between datastores to occur. 99 Some of this is entirely expected, as there may be a time lag between 100 when a configuration is given to the device and reflected in 101 , until when it actually takes effect and is reflected in 102 . However, there may be cases when a configuration item 103 that was to be applied may not actually take effect at all or needs 104 an unusually long time to do so. This can be the case due to certain 105 conditions not being met, certain parts of the configuration not 106 propagating because considered inactive, resource dependencies not 107 being resolved, or even implementation errors in corner conditions. 109 When configuration that is in effect is different from configuration 110 that was applied, many issues can result. It becomes more difficult 111 to operate the network properly due to limited visibility of actual 112 operational status which makes it more difficult to analyze and 113 understand what is going on in the network. Services may be 114 negatively affected (for example, degrading or breaking a customer 115 service) and network resources may be misallocated. 117 Applications can potentially analyze any differences between two 118 datastores by retrieving the contents from both datastores and 119 comparing them. However, in many cases this will be at the same time 120 costly and extremely wasteful. 122 This document introduces a YANG data model which defines RPCs, 123 intended to be used in conjunction with NETCONF [RFC6241] or RESTCONF 124 [RFC8040], that allow a client to request a server to compare two 125 NMDA datastores and report any differences. 127 2. Key Words 129 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 130 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 131 "OPTIONAL" in this document are to be interpreted as described in BCP 132 14 [RFC2119] [RFC8174] when, and only when, they appear in all 133 capitals, as shown here. 135 3. Definitions and Acronyms 137 NMDA: Network Management Datastore Architecture 139 RPC: Remote Procedure Call 141 4. Data Model Overview 143 The core of the solution is a new management operation, , 144 that compares the data tree contents of two datastores. The 145 operation checks whether there are any differences in values or in 146 data nodes that are contained in either datastore, and returns any 147 differences as output. The output is returned in the format 148 specified in YANG-Patch [RFC8072]. 150 The YANG data model defines the operation as a new RPC. 151 The operation takes the following input parameters: 153 o source: The source identifies the datastore that will serve as the 154 reference for the comparison, for example . 156 o target: The target identifies the datastore to compare against the 157 source, for example . 159 o filter-spec: This is a choice between different filter constructs 160 to identify the parts of the datastore to be retrieved. It acts 161 as a node selector that specifies which data nodes are within the 162 scope of the comparison and which nodes are outside the scope. 163 This allows a comparison operation to be applied only to a 164 specific part of the datastore that is of interest, such as a 165 particular subtree. Note, the filter does not allow expressions 166 that match against data node values, since this may incure 167 implementation difficulties and is not required for normal use 168 cases. 170 o all: When set, this parameter indicates that all differences 171 should be included, including differences pertaining to schema 172 nodes that exist in only one of the datastores. When this 173 parameter is not included, a prefiltering step is automatically 174 applied to exclude data from the comparison that does not pertain 175 to both datastores: if the same schema node is not present in both 176 datastores, then all instances of that schema node and all its 177 descendants are excluded from the comparison. This allows client 178 applications to focus on the differences that constitute true 179 mismatches of instance data without needing to specify more 180 complex filter constructs. 182 o report-origin: When set, this parameter indicates that origin 183 metadata should be included as part of RPC output. When this 184 parameter is omitted, origin metadata in comparisons that involve 185 is by default omitted. 187 The operation provides the following output parameter: 189 o differences: This parameter contains the list of differences. 190 Those differences are encoded per YANG-Patch data model defined in 191 RFC8072. When a datastore node in the source of the comparison is 192 not present in the target of the comparison, this can be indicated 193 either as a "delete" or as a "remove" in the patch as there is no 194 differentiation between those operations for the purposes of the 195 comparison. The YANG-Patch data model is augmented to indicate 196 the value of source datastore nodes in addition to the patch 197 itself that would need to be applied to the source to produce the 198 target. When the target datastore is and the input 199 parameter "report-origin" is set, "origin" metadata is included as 200 part of the patch. Including origin metadata can help in some 201 cases explain the cause of a difference, for example when a data 202 node is part of but the origin of the same data node in 203 is reported as "system". 205 The data model is defined in the ietf-nmda-compare YANG module. Its 206 structure is shown in the following figure. The notation syntax 207 follows [RFC8340]. 209 module: ietf-nmda-compare 210 rpcs: 211 +---x compare 212 +---w input 213 | +---w source identityref 214 | +---w target identityref 215 | +---w all? empty 216 | +---w report-origin? empty 217 | +---w (filter-spec)? 218 | +--:(subtree-filter) 219 | | +---w subtree-filter? 220 | +--:(xpath-filter) 221 | +---w xpath-filter? yang:xpath1.0 {nc:xpath}? 222 +--ro output 223 +--ro (compare-response)? 224 +--:(no-matches) 225 | +--ro no-matches? empty 226 +--:(differences) 227 +--ro differences 228 +--ro yang-patch 229 +--ro patch-id string 230 +--ro comment? string 231 +--ro edit* [edit-id] 232 +--ro edit-id string 233 +--ro operation enumeration 234 +--ro target target-resource-offset 235 +--ro point? target-resource-offset 236 +--ro where? enumeration 237 +--ro value? 238 +--ro source-value? 240 Structure of ietf-nmda-compare 242 5. YANG Data Model 244 file "ietf-nmda-compare@2021-05-24.yang" 245 module ietf-nmda-compare { 247 yang-version 1.1; 248 namespace "urn:ietf:params:xml:ns:yang:ietf-nmda-compare"; 250 prefix cmp; 252 import ietf-yang-types { 253 prefix yang; 254 reference "RFC 6991: Common YANG Data Types"; 255 } 256 import ietf-datastores { 257 prefix ds; 258 reference "RFC 8342: Network Management Datastore 259 Architecture (NMDA)"; 260 } 261 import ietf-yang-patch { 262 prefix ypatch; 263 reference "RFC 8072: YANG Patch Media Type"; 264 } 265 import ietf-netconf { 266 prefix nc; 267 reference "RFC6241: Network Configuration Protocol (NETCONF)"; 268 } 270 organization "IETF"; 271 contact 272 "WG Web: 273 WG List: 275 Author: Alexander Clemm 276 278 Author: Yingzhen Qu 279 281 Author: Jeff Tantsura 282 284 Author: Andy Bierman 285 "; 287 description 288 "The YANG data model defines a new operation, , that 289 can be used to compare NMDA datastores. 291 Copyright (c) 2021 IETF Trust and the persons identified as 292 authors of the code. All rights reserved. 294 Redistribution and use in source and binary forms, with or 295 without modification, is permitted pursuant to, and subject to 296 the license terms contained in, the Simplified BSD License set 297 forth in Section 4.c of the IETF Trust's Legal Provisions 298 Relating to IETF Documents 299 (https://trustee.ietf.org/license-info). 301 This version of this YANG module is part of RFC XXXX; see the 302 RFC itself for full legal notices."; 304 revision 2021-05-24 { 305 description 306 "Initial revision"; 307 reference 308 "RFC XXXX: Comparison of NMDA datastores"; 309 } 311 /* RPC */ 312 rpc compare { 313 description 314 "NMDA datastore compare operation."; 315 input { 316 leaf source { 317 type identityref { 318 base ds:datastore; 319 } 320 mandatory true; 321 description 322 "The source datastore to be compared."; 323 } 324 leaf target { 325 type identityref { 326 base ds:datastore; 327 } 328 mandatory true; 329 description 330 "The target datastore to be compared."; 331 } 332 leaf all { 333 type empty; 334 description 335 "When this leaf is provided, all data nodes are compared, 336 whether their schema node pertains to both datastores or 337 not. When this leaf is omitted, a prefiltering step is 338 automatically applied that excludes data nodes from the 339 comparison that can occur in only one datastore but not 340 the other. Specifically, if one of the datastores 341 (source or target) contains only configuration data and 342 the other datastore is , data nodes for 343 which config is false are excluded from the comparison."; 344 } 345 leaf report-origin { 346 type empty; 347 description 348 "When this leaf is provided, origin metadata is 349 included as part of RPC output. When this leaf is 350 omitted, origin metadata in comparisons that involve 351 is by default omitted."; 352 } 353 choice filter-spec { 354 description 355 "Identifies the portions of the datastores to be 356 compared."; 357 anydata subtree-filter { 358 description 359 "This parameter identifies the portions of the 360 target datastore to retrieve."; 361 reference "RFC 6241, Section 6."; 362 } 363 leaf xpath-filter { 364 if-feature nc:xpath; 365 type yang:xpath1.0; 366 description 367 "This parameter contains an XPath expression 368 identifying the portions of the target 369 datastore to retrieve."; 370 reference "RFC 6991: Common YANG Data Types"; 371 } 372 } 373 } 374 output { 375 choice compare-response { 376 description 377 "Comparison results."; 378 leaf no-matches { 379 type empty; 380 description 381 "This leaf indicates that the filter did not match 382 anything and nothing was compared."; 383 } 384 container differences { 385 description 386 "The list of differences, encoded per RFC8072 with an 387 augmentation to include source values where applicable. 388 When a datastore node in the source is not present in 389 the target, this can be indicated either as a 'delete' 390 or as a 'remove' as there is no difference between 391 them for the purposes of the comparison."; 392 uses ypatch:yang-patch { 393 augment "yang-patch/edit" { 394 description 395 "Provide the value of the source of the patch, 396 respectively of the comparison, in addition to 397 the target value, where applicable."; 398 anydata source-value { 399 when "../operation = 'delete'" 400 + "or ../operation = 'merge'" 401 + "or ../operation = 'move'" 402 + "or ../operation = 'replace'" 403 + "or ../operation = 'remove'"; 404 description 405 "The anydata 'value' is only used for 'delete', 406 'move', 'merge', 'replace', and 'remove' 407 operations."; 408 } 409 reference "RFC 8072: YANG Patch Media Type"; 410 } 411 } 412 } 413 } 414 } 415 } 416 } 417 419 6. Example 421 The following example compares the difference between 422 and for a subtree under "interfaces". The subtree 423 contains a subset of objects that are defined in a YANG data model 424 for the management of interfaces defined in [RFC8343]. The excerpt 425 of the data model whose instantiation is the basis of the comparison 426 is as follows: 428 container interfaces { 429 description 430 "Interface parameters."; 431 list interface { 432 key "name"; 433 leaf name { 434 type string; 435 description 436 "The name of the interface". 437 } 438 leaf description { 439 type string; 440 description 441 "A textual description of the interface."; 442 } 443 leaf enabled { 444 type boolean; 445 default "true"; 446 description 447 "This leaf contains the configured, desired state of the 448 interface.";" 449 } 450 } 451 } 453 The contents of and datastores: 455 //INTENDED 456 457 458 eth0 459 false 460 ip interface 461 462 464 //OPERATIONAL 465 468 469 eth0 470 true 471 472 473 does not contain an instance for leaf "description" 474 that is contained in . Another leaf, "enabled", has 475 different values in the two datastores, being "true" in 476 and "false" in . A third leaf, "name", is the same in both 477 cases. The origin of the leaf instances in is 478 "learned", which may help explain the discrepancies. 480 RPC request to compare (source of the comparison) with 481 (target of the comparison): 483 485 487 ds:operational 488 ds:intended 489 490 492 /if:interfaces 493 494 495 497 RPC reply, when a difference is detected: 499 502 505 506 interface status 507 508 diff between operational (source) and intended (target) 509 510 511 1 512 replace 513 /ietf-interfaces:interface=eth0/enabled 514 515 false 516 517 518 true 519 520 521 522 2 523 create 524 /ietf-interfaces:interface=eth0/description 525 526 ip interface 527 528 529 530 531 533 The same request in RESTCONF (using JSON format): 535 POST /restconf/operations/ietf-nmda-compare:compare HTTP/1.1 536 Host: example.com 537 Content-Type: application/yang-data+json 538 Accept: application/yang-d 539 { "ietf-nmda-compare:input" { 540 "source" : "ietf-datastores:operational", 541 "target" : "ietf-datastores:intended", 542 "report-origin" : null, 543 "xpath-filter" : "/ietf-interfaces:interfaces" 544 } 545 } 546 The same response in RESTCONF (using JSON format): 548 HTTP/1.1 200 OK 549 Date: Thu, 26 Jan 2019 20:56:30 GMT 550 Server: example-server 551 Content-Type: application/yang-d 552 { "ietf-nmda-compare:output" : { 553 "differences" : { 554 "ietf-yang-patch:yang-patch" : { 555 "patch-id" : "interface status", 556 "comment" : "diff between intended (source) and operational", 557 "edit" : [ 558 { 559 "edit-id" : "1", 560 "operation" : "replace", 561 "target" : "/ietf-interfaces:interface=eth0/enabled", 562 "value" : { 563 "ietf-interfaces:interface/enabled" : "false" 564 }, 565 "source-value" : { 566 "ietf-interfaces:interface/enabled" : "true", 567 "@ietf-interfaces:interface/enabled" : { 568 "ietf-origin:origin" : "ietf-origin:learned" 569 } 570 } 571 }, 572 { 573 "edit-id" : "2", 574 "operation" : "create", 575 "target" : "/ietf-interfaces:interface=eth0/description", 576 "value" : { 577 "ietf-interface:interface/description" : "ip interface" 578 } 579 } 580 ] 581 } 582 } 583 } 584 } 586 7. Performance Considerations 588 The compare operation can be computationally expensive. While 589 responsible client applications are expected to use the operation 590 responsibly and sparingly only when warranted, implementations need 591 to be aware of the fact that excessive invocation of this operation 592 will burden system resources and need to ensure that system 593 performance will not be adversely impacted. One possibility for an 594 implementation to mitigate against such a possibility is to limit the 595 number of requests that is served to a client, or to any number of 596 clients, in any one time interval, rejecting requests made at a 597 higher frequency than the implementation can reasonably sustain. 599 8. IANA Considerations 601 8.1. Updates to the IETF XML Registry 603 This document registers one URI in the IETF XML registry [RFC3688]. 604 Following the format in [RFC3688], the following registration is 605 requested: 607 URI: urn:ietf:params:xml:ns:yang:ietf-nmda-compare 609 Registrant Contact: The IESG. 611 XML: N/A, the requested URI is an XML namespace. 613 8.2. Updates to the YANG Module Names Registry 615 This document registers a YANG module in the YANG Module Names 616 registry [RFC7950]. Following the format in [RFC7950], the following 617 registration is requested: 619 name: ietf-nmda-compare 621 namespace: urn:ietf:params:xml:ns:yang:ietf-nmda-compare 623 prefix: cmp 625 reference: RFC XXXX 627 9. Security Considerations 629 The YANG module specified in this document defines a schema for data 630 that is designed to be accessed via network management protocols such 631 as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer 632 is the secure transport layer, and the mandatory-to-implement secure 633 transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer 634 is HTTPS, and the mandatory-to-implement secure transport is TLS 635 [RFC8446]. 637 The NETCONF access control model [RFC8341] provides the means to 638 restrict access for particular NETCONF or RESTCONF users to a 639 preconfigured subset of all available NETCONF or RESTCONF protocol 640 operations and content. 642 The RPC operation defined in this YANG module, "compare", may be 643 considered sensitive or vulnerable in some network environments. It 644 is thus important to control access to this operation. This is the 645 sensitivity/vulnerability of RPC operation "compare": 647 Comparing datastores for differences requires a certain amount of 648 processing resources at the server. An attacker could attempt to 649 attack a server by making a high volume of comparison requests. 650 Server implementations can guard against such scenarios in several 651 ways. For one, they can implement the NETCONF access control model 652 in order to require proper authorization for requests to be made. 653 Second, server implementations can limit the number of requests that 654 they serve to a client in any one time interval, rejecting requests 655 made at a higher frequency than the implementation can reasonably 656 sustain. 658 10. Acknowledgments 660 We thank Rob Wilton, Martin Bjorklund, Mahesh Jethanandani, Lou 661 Berger, Kent Watsen, Phil Shafer, Ladislav Lhotka, Tim Carey, and 662 Reshad Rahman for valuable feedback and suggestions. 664 11. References 666 11.1. Normative References 668 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 669 Requirement Levels", BCP 14, RFC 2119, 670 DOI 10.17487/RFC2119, March 1997, 671 . 673 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 674 DOI 10.17487/RFC3688, January 2004, 675 . 677 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 678 and A. Bierman, Ed., "Network Configuration Protocol 679 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 680 . 682 [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure 683 Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, 684 . 686 [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", 687 RFC 6991, DOI 10.17487/RFC6991, July 2013, 688 . 690 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 691 RFC 7950, DOI 10.17487/RFC7950, August 2016, 692 . 694 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 695 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 696 . 698 [RFC8072] Bierman, A., Bjorklund, M., and K. Watsen, "YANG Patch 699 Media Type", RFC 8072, DOI 10.17487/RFC8072, February 700 2017, . 702 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 703 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 704 May 2017, . 706 [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", 707 BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, 708 . 710 [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration 711 Access Control Model", STD 91, RFC 8341, 712 DOI 10.17487/RFC8341, March 2018, 713 . 715 [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., 716 and R. Wilton, "Network Management Datastore Architecture 717 (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, 718 . 720 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 721 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 722 . 724 11.2. Informative References 726 [RFC8343] Bjorklund, M., "A YANG Data Model for Interface 727 Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, 728 . 730 Appendix A. Possible Future Extensions 732 It is conceivable to extend the compare operation with a number of 733 possible additional features in the future. 735 Specifically, it is possible to define an extension with an optional 736 feature for dampening. This will allow clients to specify a minimum 737 time period for which a difference must persist for it to be 738 reported. This will enable clients to distinguish between 739 differences that are only fleeting from ones that are not and that 740 may represent a real operational issue and inconsistency within the 741 device. 743 For this purpose, an additional input parameter can be added to 744 specify the dampening period. Only differences that pertain for at 745 least the dampening time are reported. A value of 0 or omission of 746 the parameter indicates no dampening. Reporting of differences MAY 747 correspondingly be delayed by the dampening period from the time the 748 request is received. 750 To implement this feature, a server implementation might run a 751 comparison when the RPC is first invoked and temporarily store the 752 result. Subsequently, it could wait until after the end of the 753 dampening period to check whether the same differences are still 754 observed. The differences that still persist are then returned. 756 Authors' Addresses 758 Alexander Clemm 759 Futurewei 760 2330 Central Expressway 761 Santa Clara, CA 95050 762 USA 764 Email: ludwig@clemm.org 766 Yingzhen Qu 767 Futurewei 768 2330 Central Expressway 769 Santa Clara, CA 95050 770 USA 772 Email: yqu@futurewei.com 774 Jeff Tantsura 775 Apstra 777 Email: jefftant.ietf@gmail.com 779 Andy Bierman 780 YumaWorks 782 Email: andy@yumaworks.com