Dynamic subscription to YANG Events and Datastores over NETCONF
draft-ietf-netconf-netconf-event-notifications-19
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8640.
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Authors | Eric Voit , Alexander Clemm , Alberto Gonzalez Prieto , Einar Nilsen-Nygaard , Ambika Tripathy | ||
Last updated | 2019-04-29 | ||
Replaces | draft-gonzalez-netconf-event-notifications | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Reviews |
TSVART Last Call review
(of
-17)
by Wesley Eddy
Ready w/issues
YANGDOCTORS Last Call review
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-16)
by Reshad Rahman
Ready w/issues
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Additional resources | Mailing list discussion | ||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Kent Watsen | ||
Shepherd write-up | Show Last changed 2019-02-26 | ||
IESG | IESG state | Became RFC 8640 (Proposed Standard) | |
Consensus boilerplate | Yes | ||
Telechat date |
(None)
Needs a YES. Needs 8 more YES or NO OBJECTION positions to pass. |
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Responsible AD | Ignas Bagdonas | ||
Send notices to | Kent Watsen <kent+ietf@watsen.net> | ||
IANA | IANA review state | Version Changed - Review Needed |
draft-ietf-netconf-netconf-event-notifications-19
NETCONF E. Voit Internet-Draft Cisco Systems Intended status: Standards Track A. Clemm Expires: October 31, 2019 Huawei A. Gonzalez Prieto Microsoft E. Nilsen-Nygaard A. Tripathy Cisco Systems April 29, 2019 Dynamic subscription to YANG Events and Datastores over NETCONF draft-ietf-netconf-netconf-event-notifications-19 Abstract This document provides a NETCONF binding to the dynamic subscription capability of both subscribed notifications and YANG-Push. RFC Editor note: please replace the four references to pre-RFC normative drafts with the actual assigned RFC numbers. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on October 31, 2019. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of Voit, et al. Expires October 31, 2019 [Page 1] Internet-Draft NETCONF-notif April 2019 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Compatibility with RFC-5277's create-subscription . . . . . . 3 4. Mandatory XML, event stream and datastore support . . . . . . 4 5. NETCONF connectivity and the Dynamic Subscriptions . . . . . 4 6. Notification Messages . . . . . . . . . . . . . . . . . . . . 4 7. Dynamic Subscriptions and RPC Error Responses . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 11. Notes to the RFC Editor . . . . . . . . . . . . . . . . . . . 7 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 12.1. Normative References . . . . . . . . . . . . . . . . . . 7 12.2. Informative References . . . . . . . . . . . . . . . . . 8 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 8 A.1. Event Stream Discovery . . . . . . . . . . . . . . . . . 8 A.2. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 9 A.3. Subscription State Notifications . . . . . . . . . . . . 14 A.4. Filter Examples . . . . . . . . . . . . . . . . . . . . . 15 Appendix B. Changes between revisions . . . . . . . . . . . . . 17 B.1. v17 to v19 . . . . . . . . . . . . . . . . . . . . . . . 17 B.2. v16 to v17 . . . . . . . . . . . . . . . . . . . . . . . 17 B.3. v15 to v16 . . . . . . . . . . . . . . . . . . . . . . . 17 B.4. v14 to v15 . . . . . . . . . . . . . . . . . . . . . . . 17 B.5. v13 to v14 . . . . . . . . . . . . . . . . . . . . . . . 18 B.6. v11 to v13 . . . . . . . . . . . . . . . . . . . . . . . 18 B.7. v10 to v11 . . . . . . . . . . . . . . . . . . . . . . . 18 Voit, et al. Expires October 31, 2019 [Page 2] Internet-Draft NETCONF-notif April 2019 B.8. v09 to v10 . . . . . . . . . . . . . . . . . . . . . . . 18 B.9. v08 to v09 . . . . . . . . . . . . . . . . . . . . . . . 18 B.10. v07 to v08 . . . . . . . . . . . . . . . . . . . . . . . 18 B.11. v06 to v07 . . . . . . . . . . . . . . . . . . . . . . . 18 B.12. v05 to v06 . . . . . . . . . . . . . . . . . . . . . . . 18 B.13. v03 to v04 . . . . . . . . . . . . . . . . . . . . . . . 19 B.14. v01 to v03 . . . . . . . . . . . . . . . . . . . . . . . 19 B.15. v00 to v01 . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 1. Introduction This document provides a binding for events streamed over the NETCONF protocol [RFC6241] for dynamic subscriptions as defined in [I-D.draft-ietf-netconf-subscribed-notifications]. In addition, as [I-D.ietf-netconf-yang-push] is itself built upon [I-D.draft-ietf-netconf-subscribed-notifications], this document enables a NETCONF client to request via a dynamic subscription and receive updates from a YANG datastore located on a NETCONF server. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. The following terms are defined in [I-D.draft-ietf-netconf-subscribed-notifications]: dynamic subscription, event stream, notification message, publisher, receiver, subscriber, subscription. No additional terms are defined. 3. Compatibility with RFC-5277's create-subscription A publisher is allowed to concurrently support dynamic subscription RPCs of [I-D.draft-ietf-netconf-subscribed-notifications] at the same time as [RFC5277]'s "create-subscription" RPC. However a single NETCONF transport session cannot support both this specification and a subscription established by [RFC5277]'s "create-subscription" RPC. To protect against any attempts to use a single NETCONF transport session in this way: o A solution MUST reply with the [RFC6241] "rpc-error" element containing the "error-tag" value of "operation-not-supported" if a "create-subscription" RPC is received on a NETCONF session where an [I-D.draft-ietf-netconf-subscribed-notifications] established subscription exists. Voit, et al. Expires October 31, 2019 [Page 3] Internet-Draft NETCONF-notif April 2019 o A solution MUST reply with the [RFC6241] "rpc-error" element containing the "error-tag" value of "operation-not-supported" if an "establish-subscription" request has been received on a NETCONF session where the "create-subscription" RPC has successfully [RFC5277] created a subscription. If a publisher supports this specification but not subscriptions via [RFC5277], the publisher MUST NOT advertise "urn:ietf:params:netconf:capability:notification:1.0". 4. Mandatory XML, event stream and datastore support The "encode-xml" feature of [I-D.draft-ietf-netconf-subscribed-notifications] MUST be supported. This indicates that XML is a valid encoding for RPCs, state change notifications, and subscribed content. A NETCONF publisher supporting event stream subscription via [I-D.draft-ietf-netconf-subscribed-notifications] MUST support the "NETCONF" event stream identified in that document. 5. NETCONF connectivity and the Dynamic Subscriptions Management of dynamic subscriptions occurs via RPCs as defined in [I-D.ietf-netconf-yang-push] and [I-D.draft-ietf-netconf-subscribed-notifications]. For a dynamic subscription, if the NETCONF session involved with the "establish- subscription" terminates, the subscription MUST be terminated. For a dynamic subscription, any "modify-subscription", "delete- subscription", or "resync-subscription" RPCs MUST be sent using the same NETCONF session upon which the referenced subscription was established. 6. Notification Messages Notification messages transported over the NETCONF protocol MUST be encoded in a <notification> message as defined within [RFC5277], Section 4. And per [RFC5277]'s "eventTime" object definition, the "eventTime" MUST be populated with the event occurrence time. For dynamic subscriptions, all notification messages MUST use the NETCONF transport session used by the "establish-subscription" RPC. Voit, et al. Expires October 31, 2019 [Page 4] Internet-Draft NETCONF-notif April 2019 7. Dynamic Subscriptions and RPC Error Responses When an RPC error occurs as defined in [I-D.draft-ietf-netconf-subscribed-notifications] Section 2.4.6 and [I-D.ietf-netconf-yang-push] Appendix A, the NETCONF RPC reply MUST include an "rpc-error" element per [RFC6241] with the error information populated as follows: o An "error-type" node of "application". o An "error-tag" node with the value being a string that corresponds to an identity associated with the error. This "error-tag" will come from one of two places. Either it will correspond to the error identities within [I-D.draft-ietf-netconf-subscribed-notifications] section 2.4.6 for general subscription errors: error identity uses error-tag ---------------------- -------------- dscp-unavailable invalid-value encoding-unsupported invalid-value filter-unsupported invalid-value insufficient-resources resource-denied no-such-subscription invalid-value replay-unsupported operation-not-supported Or this "error-tag" will correspond to the error identities within [I-D.ietf-netconf-yang-push] Appendix A.1 for subscription errors specific to YANG datastores: error identity uses error-tag ---------------------- -------------- cant-exclude operation-not-supported datastore-not-subscribable invalid-value no-such-subscription-resync invalid-value on-change-unsupported operation-not-supported on-change-sync-unsupported operation-not-supported period-unsupported invalid-value update-too-big too-big sync-too-big too-big unchanging-selection operation-failed o an "error-severity" of "error" (this MAY be included). o an "error-app-tag" node with the value being a string that corresponds to an identity associated with the error, as defined in [I-D.draft-ietf-netconf-subscribed-notifications] section 2.4.6 for general subscriptions, and [I-D.ietf-netconf-yang-push] Appendix A.1, for datastore subscriptions. The specific identity to use depends on the RPC for which the error occurred. Each Voit, et al. Expires October 31, 2019 [Page 5] Internet-Draft NETCONF-notif April 2019 error identity will be inserted as the "error-app-tag" following the form <modulename>:<identityname>. An example of such as valid encoding would be "ietf-subscribed-notifications:no-such- subscription". Viable errors for different RPCs are as follows: RPC use base identity ---------------------- ---------------------------- establish-subscription establish-subscription-error modify-subscription modify-subscription-error delete-subscription delete-subscription-error kill-subscription delete-subscription-error resync-subscription resync-subscription-error o In case of error responses to an "establish-subscription" or "modify-subscription" request there is the option of including an "error-info" node. This node may contain XML-encoded data with hints for parameter settings that might lead to successful RPC requests in the future. Following are the yang-data structures from [I-D.draft-ietf-netconf-subscribed-notifications] and [I-D.ietf-netconf-yang-push] which may be returned: establish-subscription returns hints in yang-data structure ---------------------- ------------------------------------ target: event stream establish-subscription-stream-error-info target: datastore establish-subscription-datastore-error-info modify-subscription returns hints in yang-data structure ---------------------- ------------------------------------ target: event stream modify-subscription-stream-error-info target: datastore modify-subscription-datastore-error-info The yang-data included within "error-info" SHOULD NOT include the optional leaf "error-reason", as such a leaf would be redundant with information that is already placed within the "error-app-tag". In case of an rpc error resulting from a "delete-subscription", "kill-subscription", or "resync-subscription" request, no "error- info" needs to be included, as the "subscription-id" is the only RPC input parameter and no hints regarding this RPC input parameters need to be provided. 8. Security Considerations If a malicious or buggy NETCONF subscriber sends a number of establish-subscription requests, then these subscriptions accumulate and may use up system resources. In such a situation, subscriptions MAY be terminated by terminating the underlying NETCONF session. The Voit, et al. Expires October 31, 2019 [Page 6] Internet-Draft NETCONF-notif April 2019 publisher MAY also suspend or terminate a subset of the active subscriptions on that NETCONF session. 9. IANA Considerations This document has no actions for IANA. 10. Acknowledgments We wish to acknowledge the helpful contributions, comments, and suggestions that were received from: Andy Bierman, Yan Gang, Sharon Chisholm, Hector Trevino, Peipei Guo, Susan Hares, Tim Jenkins, Balazs Lengyel, Martin Bjorklund, Mahesh Jethanandani, Kent Watsen, Qin Wu, and Guangying Zheng. 11. Notes to the RFC Editor This section can be removed by the RFC editor after the requests have been performed. RFC 6241 needs to be updated based on the needs of this draft. RFC-6241 section 1.2 bullet "(2)" targets RFC-5277 (actually it identifies RFC 5717, but that was an error fixed after RFC publication). Anyway the current phrasing in RFC-5277 says that a notification message can only be sent after a successful "create- subscription". Therefore the reference text must be modified to also allow notification messages be sent after a successful "establish- subscription". Proposed text for bullet (2) of RFC-6241 would be: (2) The Messages layer provides a simple, transport-independent framing mechanism for encoding RPCs and notifications. Section 4 documents the RPC messages, [RFC5277] documents Notifications sent as a result of a <create-subscription> RPC, and [RFC xxxx] documents Notifications sent as a result of an <establish-subscription> RPC. (where xxxx is replaced with this RFC number) 12. References 12.1. Normative References [I-D.draft-ietf-netconf-subscribed-notifications] Voit, E., Clemm, A., Gonzalez Prieto, A., Tripathy, A., and E. Nilsen-Nygaard, "Customized Subscriptions to a Publisher's Event Streams", September 2018, <https://datatracker.ietf.org/doc/ draft-ietf-netconf-subscribed-notifications/>. Voit, et al. Expires October 31, 2019 [Page 7] Internet-Draft NETCONF-notif April 2019 [I-D.ietf-netconf-yang-push] Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto., Tripathy, A., Nilsen-Nygaard, E., Bierman, A., and B. Lengyel, "YANG Datastore Subscription", September 2018, <https://datatracker.ietf.org/doc/ draft-ietf-netconf-yang-push/>. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008, <https://www.rfc-editor.org/info/rfc5277>. [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, <https://www.rfc-editor.org/info/rfc6241>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. 12.2. Informative References [RFC8347] Liu, X., Ed., Kyparlis, A., Parikh, R., Lindem, A., and M. Zhang, "A YANG Data Model for the Virtual Router Redundancy Protocol (VRRP)", RFC 8347, DOI 10.17487/RFC8347, March 2018, <https://www.rfc-editor.org/info/rfc8347>. [XPATH] Clark, J. and S. DeRose, "XML Path Language (XPath) Version 1.0", November 1999, <http://www.w3.org/TR/1999/REC-xpath-19991116>. Appendix A. Examples This section is non-normative. A.1. Event Stream Discovery As defined in [I-D.draft-ietf-netconf-subscribed-notifications] an event stream exposes a continuous set of events available for subscription. A NETCONF client can retrieve the list of available event streams from a NETCONF publisher using the "get" operation Voit, et al. Expires October 31, 2019 [Page 8] Internet-Draft NETCONF-notif April 2019 against the top-level container "/streams" defined in [I-D.draft-ietf-netconf-subscribed-notifications] Section 3.1. The following example illustrates the retrieval of the list of available event streams: <rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <get> <filter type="subtree"> <streams xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"/> </filter> </get> </rpc> Figure 1: Get streams request After such a request, the NETCONF publisher returns a list of event streams available, as well as additional information which might exist in the container. A.2. Dynamic Subscriptions A.2.1. Establishing Dynamic Subscriptions The following figure shows two successful "establish-subscription" RPC requests as per [I-D.draft-ietf-netconf-subscribed-notifications]. The first request is given a subscription "id" of 22, the second, an "id" of 23. Voit, et al. Expires October 31, 2019 [Page 9] Internet-Draft NETCONF-notif April 2019 +------------+ +-----------+ | Subscriber | | Publisher | +------------+ +-----------+ | | | Capability Exchange | |<---------------------------->| | | | | | establish-subscription | |----------------------------->| (a) | RPC Reply: OK, id = 22 | |<-----------------------------| (b) | | | notification message (for 22)| |<-----------------------------| | | | | | establish-subscription | |----------------------------->| | notification message (for 22)| |<-----------------------------| | RPC Reply: OK, id = 23 | |<-----------------------------| | | | | | notification message (for 22)| |<-----------------------------| | notification message (for 23)| |<-----------------------------| | | Figure 2: Multiple subscriptions over a NETCONF session To provide examples of the information being transported, example messages for interactions (a) and (b) in Figure 2 are detailed below: <rpc message-id="102" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <establish-subscription xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> <stream-xpath-filter xmlns:ex="http://example.com/events"> /ex:foo/ </stream-xpath-filter> <stream>NETCONF</stream> <dscp>10</dscp> </establish-subscription> </rpc> Figure 3: establish-subscription request (a) Voit, et al. Expires October 31, 2019 [Page 10] Internet-Draft NETCONF-notif April 2019 As NETCONF publisher was able to fully satisfy the request (a), the publisher sends the subscription "id" of the accepted subscription within message (b): <rpc-reply message-id="102" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <id xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> 22 </id> </rpc-reply> Figure 4: establish-subscription success (b) If the NETCONF publisher had not been able to fully satisfy the request, or subscriber has no authorization to establish the subscription, the publisher would have sent an RPC error response. For instance, if the "dscp" value of 10 asserted by the subscriber in Figure 3 proved unacceptable, the publisher may have returned: <rpc-reply message-id="102" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <rpc-error> <error-type>application</error-type> <error-tag>invalid-value</error-tag> <error-severity>error</error-severity> <error-app-tag> ietf-subscribed-notifications:dscp-unavailable </error-app-tag> </rpc-error> </rpc-reply> Figure 5: an unsuccessful establish subscription The subscriber can use this information in future attempts to establish a subscription. A.2.2. Modifying Dynamic Subscriptions An existing subscription may be modified. The following exchange shows a negotiation of such a modification via several exchanges between a subscriber and a publisher. This negotiation consists of a failed RPC modification request/response, followed by a successful one. Voit, et al. Expires October 31, 2019 [Page 11] Internet-Draft NETCONF-notif April 2019 +------------+ +-----------+ | Subscriber | | Publisher | +------------+ +-----------+ | | | notification message (for 23)| |<-----------------------------| | | | modify-subscription (id = 23)| |----------------------------->| (c) | RPC error (with hint) | |<-----------------------------| (d) | | | modify-subscription (id = 23)| |----------------------------->| | RPC Reply: OK | |<-----------------------------| | | | notification message (for 23)| |<-----------------------------| | | Figure 6: Interaction model for successful subscription modification If the subscription being modified in Figure 6 is a datastore subscription as per [I-D.ietf-netconf-yang-push], the modification request made in (c) may look like that shown in Figure 7. As can be seen, the modifications being attempted are the application of a new XPath filter as well as the setting of a new periodic time interval. <rpc message-id="303" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <modify-subscription xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications" xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push"> <id>23</id> <yp:datastore-xpath-filter xmlns:ex="http://example.com/datastore"> /ex:foo/ex:bar </yp:datastore-xpath-filter> <yp:periodic> <yp:period>500</yp:period> </yp:periodic> </modify-subscription> </rpc> Figure 7: Subscription modification request (c) If the NETCONF publisher can satisfy both changes, the publisher sends a positive result for the RPC. If the NETCONF publisher cannot Voit, et al. Expires October 31, 2019 [Page 12] Internet-Draft NETCONF-notif April 2019 satisfy either of the proposed changes, the publisher sends an RPC error response (d). The following is an example RPC error response for (d) which includes a hint. This hint is an alternative time period value which might have resulted in a successful modification: <rpc-reply message-id="303" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <rpc-error> <error-type>application</error-type> <error-tag>invalid-value</error-tag> <error-severity>error</error-severity> <error-app-tag> ietf-yang-push:period-unsupported </error-app-tag> <error-info> <modify-subscription-datastore-error-info xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push"> <period-hint> 3000 </period-hint> </modify-subscription-datastore-error-info> </error-info> </rpc-error> </rpc-reply> Figure 8: Modify subscription failure with hint (d) A.2.3. Deleting Dynamic Subscriptions The following demonstrates deleting a subscription. This subscription may have been to either a stream or a datastore. <rpc message-id="103" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <delete-subscription xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> <id>22</id> </delete-subscription> </rpc> Figure 9: Delete subscription If the NETCONF publisher can satisfy the request, the publisher replies with success to the RPC request. If the NETCONF publisher cannot satisfy the request, the publisher sends an error-rpc element indicating the modification didn't work. Figure 10 shows a valid response for existing valid subscription Voit, et al. Expires October 31, 2019 [Page 13] Internet-Draft NETCONF-notif April 2019 "id", but that subscription "id" was created on a different NETCONF transport session: <rpc-reply message-id="103" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <rpc-error> <error-type>application</error-type> <error-tag>invalid-value</error-tag> <error-severity>error</error-severity> <error-app-tag> ietf-subscribed-notifications:no-such-subscription </error-app-tag> </rpc-error> </rpc-reply> Figure 10: Unsuccessful delete subscription A.3. Subscription State Notifications A publisher will send subscription state notifications for dynamic subscriptions according to the definitions within [I-D.draft-ietf-netconf-subscribed-notifications]. A.3.1. subscription-modified As per Section 2.7.2 of [I-D.draft-ietf-netconf-subscribed-notifications], a "subscription- modified" might be sent over NETCONF if the definition of a configured filter changes. A subscription state notification encoded in XML would look like: <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"> <eventTime>2007-09-01T10:00:00Z</eventTime> <subscription-modified xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> <id>39</id> <stream-xpath-filter xmlns:ex="http://example.com/events"> /ex:foo </stream-xpath-filter> <stream>NETCONF</stream> </subscription-modified> </notification> Figure 11: subscription-modified subscription state notification Voit, et al. Expires October 31, 2019 [Page 14] Internet-Draft NETCONF-notif April 2019 A.3.2. subscription-resumed, and replay-complete A "subscription-resumed" would look like: <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"> <eventTime>2007-09-01T10:00:00Z</eventTime> <subscription-resumed xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> <id>39</id> </subscription-resumed> </notification> Figure 12: subscription-resumed notification in XML The "replay-complete" is virtually identical, with "subscription- resumed" simply being replaced by "replay-complete". A.3.3. subscription-terminated and subscription-suspended A "subscription-terminated" would look like: <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"> <eventTime>2007-09-01T10:00:00Z</eventTime> <subscription-terminated xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> <id>39</id> <reason> suspension-timeout </reason> </subscription-terminated> </notification> Figure 13: subscription-terminated subscription state notification The "subscription-suspended" is virtually identical, with "subscription-terminated" simply being replaced by "subscription- suspended". A.4. Filter Examples This section provides examples which illustrate both XPath and subtree methods of filtering event record contents. The examples are based on the YANG notification "vrrp-protocol-error-event" as defined per the ietf-vrrp.yang model within [RFC8347]. Event records based on this specification which are generated by the publisher might appear as: Voit, et al. Expires October 31, 2019 [Page 15] Internet-Draft NETCONF-notif April 2019 <notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"> <eventTime>2018-09-14T08:22:33.44Z</eventTime> <vrrp-protocol-error-event xmlns="urn:ietf:params:xml:ns:yang:ietf-vrrp"> <protocol-error-reason>checksum-error</protocol-error-reason> </vrrp-protocol-error-event> </notification> Figure 14: RFC 8347 (VRRP) - Example Notification Suppose a subscriber wanted to establish a subscription which only passes instances of event records where there is a "checksum-error" as part of a VRRP protocol event. Also assume the publisher places such event records into the NETCONF stream. To get a continuous series of matching event records, the subscriber might request the application of an XPath filter against the NETCONF stream. An "establish-subscription" RPC to meet this objective might be: <rpc message-id="601" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <establish-subscription xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> <stream>NETCONF</stream> <stream-xpath-filter xmlns="urn:ietf:params:xml:ns:yang:ietf-vrrp"> /vrrp-protocol-error-event[ vrrp:protocol-error-reason="vrrp:checksum-error"] </stream-xpath-filter> </establish-subscription> </rpc> Figure 15: Establishing a subscription error reason via XPath For more examples of XPath filters, see [XPATH]. Suppose the "establish-subscription" in Figure 15 was accepted. And suppose later a subscriber decided they wanted to broaden this subscription cover to all VRRP protocol events (i.e., not just those with a "checksum error"). The subscriber might attempt to modify the subscription in a way which replaces the XPath filter with a subtree filter which sends all VRRP protocol events to a subscriber. Such a "modify-subscription" RPC might look like: Voit, et al. Expires October 31, 2019 [Page 16] Internet-Draft NETCONF-notif April 2019 <rpc message-id="602" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <modify-subscription xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"> <id>99</id> <stream-subtree-filter> <vrrp-protocol-error-event xmlns="urn:ietf:params:xml:ns:yang:ietf-vrrp"/> </stream-subtree-filter> </modify-subscription> </rpc> Figure 16 For more examples of subtree filters, see [RFC6241], section 6.4. Appendix B. Changes between revisions (To be removed by RFC editor prior to publication) B.1. v17 to v19 o Per Benjamin Kaduk's discuss on SN, adjusted IPR to pre5378Trust200902 B.2. v16 to v17 o During the SN YANG Doctor review, a suggestion was made to update the error-tags to make the mechanism work with embedded NETCONF and RESTCONF error reporting. o Minor text tweaks from review. B.3. v15 to v16 o During the shepherd review, two clarifications were requested which do not impact the technical details of this document. These clarifications were: (a) further describing that dynamic subscriptions can have state change notifications, and (b) more details about the recommended text refinement desired for RFC6241. B.4. v14 to v15 o Per Kent's request, added name attribute to artwork. This would be needed for an automated extraction. Voit, et al. Expires October 31, 2019 [Page 17] Internet-Draft NETCONF-notif April 2019 B.5. v13 to v14 o Title change. B.6. v11 to v13 o Subscription identifier renamed to id. o Appendix A.4 for filter examples o for v13, Tweak of example to /foo/bar B.7. v10 to v11 o Configured removed. B.8. v09 to v10 o Tweaks to examples and text. o Downshifted state names. o Removed address from examples. B.9. v08 to v09 o Tweaks based on Kent's comments. o Updated examples in Appendix A. And updates to some object names based on changes in the subscribed-notifications draft. o Added a YANG model for the NETCONF identity. B.10. v07 to v08 o Tweaks and clarification on :interleave. B.11. v06 to v07 o XML encoding and operational datastore mandatory. o Error mechanisms and examples updated. B.12. v05 to v06 o Moved examples to appendices o All examples rewritten based on namespace learnings o Normative text consolidated in front o Removed all mention of JSON o Call home process detailed o Note: this is a major revision attempting to cover those comments received from two week review. Voit, et al. Expires October 31, 2019 [Page 18] Internet-Draft NETCONF-notif April 2019 B.13. v03 to v04 o Added additional detail to "configured subscriptions" o Added interleave capability o Adjusted terminology to that in draft-ietf-netconf-subscribed- notifications o Corrected namespaces in examples B.14. v01 to v03 o Text simplifications throughout o v02 had no meaningful changes B.15. v00 to v01 o Added Call Home in solution for configured subscriptions. o Clarified support for multiple subscription on a single session. No need to support multiple create-subscription. o Added mapping between terminology in yang-push and [RFC6241] (the one followed in this document). o Editorial improvements. Authors' Addresses Eric Voit Cisco Systems Email: evoit@cisco.com Alexander Clemm Huawei Email: ludwig@clemm.org Alberto Gonzalez Prieto Microsoft Email: alberto.gonzalez@microsoft.com Einar Nilsen-Nygaard Cisco Systems Email: einarnn@cisco.com Voit, et al. Expires October 31, 2019 [Page 19] Internet-Draft NETCONF-notif April 2019 Ambika Prasad Tripathy Cisco Systems Email: ambtripa@cisco.com Voit, et al. Expires October 31, 2019 [Page 20]