NETCONF A. Gonzalez Prieto Internet-Draft VMWare Intended status: Standards Track A. Clemm Expires: December 9, 2017 Huawei E. Voit E. Nilsen-Nygaard A. Tripathy Cisco Systems June 7, 2017 NETCONF Support for Event Notifications draft-ietf-netconf-netconf-event-notifications-03 Abstract This document defines how to transport network subscriptions and event messages on top of the Network Configuration protocol (NETCONF). This includes the full set of RPCs, subscription state changes, and message payloads needing asynchronous delivery. The capabilities and operations defined in this document used in conjunction with [subscribe] are intended to obsolete [RFC5277]. In addition, the capabilities within those two documents along with [yang-push] are intended to enable an extract of a YANG datastore on a remote device. 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 http://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 December 9, 2017. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. Gonzalez Prieto, et al. Expires December 9, 2017 [Page 1] Internet-Draft NETCONF-notifications June 2017 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Event Stream Discovery . . . . . . . . . . . . . . . . . 3 3.2. Mandatory NETCONF support for Streams and Datastores . . 4 3.3. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 4 3.4. Configured Subscriptions . . . . . . . . . . . . . . . . 11 4. Security Considerations . . . . . . . . . . . . . . . . . . . 24 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1. Normative References . . . . . . . . . . . . . . . . . . 25 6.2. Informative References . . . . . . . . . . . . . . . . . 26 Appendix A. Changes between revisions . . . . . . . . . . . . . 26 A.1. v01 to v03 . . . . . . . . . . . . . . . . . . . . . . . 26 A.2. v00 to v01 . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 1. Introduction This document defines mechanisms that provide an asynchronous message notification delivery service for the NETCONF protocol [RFC6241] based on [subscribe]. This is an optional capability built on top of the base NETCONF definition. [subscribe] plus this transport specification document provides a superset of the capabilities previously defined in [RFC5277]. Newly introduced capabilities include the ability to have multiple subscriptions on a single NETCONF session, the ability to terminate subscriptions without terminating the client session, and the ability to modify existing subscriptions. In addition, [yang-push] plus the capabilities of this document provide a mechanism for a NETCONF client to maintain a subset/extract of an actively changing YANG datastore. Gonzalez Prieto, et al. Expires December 9, 2017 [Page 2] Internet-Draft NETCONF-notifications June 2017 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. The following terms are defined in [RFC6241]: client, server, operation, RPC. The following terms are defined in [subscribe]: event, event notification, stream, publisher, receiver, subscriber, subscription, configured subscription. Note that a publisher in [subscribe] corresponds to a server in [RFC6241]. Similarly, a subscriber corresponds to a client. A receiver is also a client. In the remainder of this document, we will use the terminology in [RFC6241] to simplify [subscribe]'s mental mappings to embedded NETCONF terminology. 3. Solution In this section, we describe and exemplify how [subscribe] is to be supported over NETCONF. 3.1. Event Stream Discovery In the context of [subscribe] 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 server using the "get" operation. The reply contains the elements defined in the YANG model under the container "/streams", which includes the stream identities supported on the NETCONF server. The following example illustrates the retrieval of the list of available event streams using the operation. Figure 1: Get streams Gonzalez Prieto, et al. Expires December 9, 2017 [Page 3] Internet-Draft NETCONF-notifications June 2017 The NETCONF server returns a list of event streams available. In this example, the list contains the NETCONF, SNMP, and SYSLOG streams. NETCONF SNMP SYSLOG Figure 2: Get streams response For [yang-push], a similar get is needed to retrieve available datastore names. 3.2. Mandatory NETCONF support for Streams and Datastores A NETCONF server implementation supporting [subscribe] must support the "NETCONF" notification event stream. A NETCONF server implementation supporting [yang-push] must support the "running" datastore. 3.3. Dynamic Subscriptions 3.3.1. Establishing Dynamic Subscriptions The dynamic subscription RFC and interactions operation is defined in [subscribe]. 3.3.1.1. Usage Example An example of interactions over NETCONF transport for one sample subscription is below: Gonzalez Prieto, et al. Expires December 9, 2017 [Page 4] Internet-Draft NETCONF-notifications June 2017 NETCONF xpath xmlns:ex="http://example.com/event/1.0" select="/ex:event[ex:eventClass='fault' and (ex:severity='minor' or ex:severity='major' or ex:severity='critical')]" Figure 3: establish-subscription over NETCONF 3.3.1.2. Positive Response If the NETCONF server can satisfy the request, the server sends a positive element, and the subscription-id of the accepted subscription. ok 52 Figure 4: Successful establish-subscription 3.3.1.3. Negative Response If the NETCONF server cannot satisfy the request, or client has no authorization to establish the subscription, the server will send a negative element. For instance: Gonzalez Prieto, et al. Expires December 9, 2017 [Page 5] Internet-Draft NETCONF-notifications June 2017 stream-unavailable Figure 5: Unsuccessful establish subscription If the client requests parameters the NETCONF server cannot serve, the negative may include additional information. For instance, consider the following subscription from [yang-push], which augments the establish-subscription with some additional parameters, including "period". If the client requests a which period the NETCONF server cannot serve, the back-and-forth exchange may be: push-update subtree xmlns:ex="http://example.com/sample-data/1.0" select="/ex:foo" 500 encode-xml error-insufficient-resources 2000 Figure 6: Subscription establishment negotiation Gonzalez Prieto, et al. Expires December 9, 2017 [Page 6] Internet-Draft NETCONF-notifications June 2017 3.3.1.4. Message Flow Examples +------------+ +-----------+ | Client | | Server | +------------+ +-----------+ | | | Capability Exchange | |<---------------------------->| | | | | | Establish Subscription | |----------------------------->| | RPC Reply: OK, id = 22 | |<-----------------------------| | | | Notification (id 22) | |<-----------------------------| | | | | | Establish Subscription | |----------------------------->| | RPC Reply: OK, id = 23 | |<-----------------------------| | | | | | Notification (id 22) | |<-----------------------------| | Notification (id 23) | |<-----------------------------| | | | | Figure 7: Multiple subscription establishments over a NETCONF session 3.3.2. Modifying a Subscription This operation is defined in [subscribe] and enhanced in [yang-push]. 3.3.2.1. Usage Example The following demonstrates modifying a subscription. Consider a subscription from [yang-push], which augments the establish- subscription with some additional parameters, including "period". A subscription may be established as follows. Gonzalez Prieto, et al. Expires December 9, 2017 [Page 7] Internet-Draft NETCONF-notifications June 2017 /* Question, shouldn't this be yang-push 1.0 as that is where the referenced augmentations are? */ running subtree xmlns:ex="http://example.com/sample-data/1.0" select="/ex:foo" 1000 ok 1922 Figure 8: Establish subscription to be modified The subscription may be modified with and RPC request such as: 1922 100 Figure 9: Modify subscription Gonzalez Prieto, et al. Expires December 9, 2017 [Page 8] Internet-Draft NETCONF-notifications June 2017 3.3.2.2. Positive Response If the NETCONF server can satisfy the request, the server sends a positive element. This response is like that to an establish-subscription request, but without the subscription identifier. ok Figure 10: Successful modify subscription 3.3.2.3. Negative Response If the NETCONF server cannot satisfy the request, the server sends a negative element. Its contents and semantics are identical to those in an establish-subscription request. For instance: *** why is the namespace not yang-push? period-unsupported 500 Figure 11: Unsuccessful modify subscription 3.3.2.4. Message Flow Example Gonzalez Prieto, et al. Expires December 9, 2017 [Page 9] Internet-Draft NETCONF-notifications June 2017 +------------+ +-----------+ | Client | | Server | +------------+ +-----------+ | | | Capability Exchange | |<---------------------------->| | | | Establish Subscription | |<---------------------------->| | | | Notification (id 22) | |<-----------------------------| | | | Modify Subscription | |----------------------------->| | RPC Reply: OK | |<-----------------------------| | | | Notification (id 22) | |<-----------------------------| | | Figure 12: Message flow for successful subscription modification 3.3.3. Deleting a Subscription This operation is defined in [subscribe] for events, and enhanced in [yang-push] for datastores. 3.3.3.1. Usage Example The following demonstrates deleting a subscription. 1922 Figure 13: Delete subscription 3.3.3.2. Positive Response If the NETCONF server can satisfy the request, the server sends an OK element. For example: Gonzalez Prieto, et al. Expires December 9, 2017 [Page 10] Internet-Draft NETCONF-notifications June 2017 Figure 14: Successful delete subscription 3.3.3.3. Negative Response If the NETCONF server cannot satisfy the request, the server sends an error-rpc element indicating the modification didn't work. For example: application invalid-value error /t:identifier no-such-subscription Figure 15: Unsuccessful delete subscription 3.4. Configured Subscriptions Configured subscriptions are established, modified, and deleted using configuration operations against the top-level subtree of [subscribe] or [yang-push] via normal NETCONF operations. In this section, we present examples of how to manage the configuration subscriptions using a NETCONF client. Key differences from dunamic subscriptions over NETCONF is that subscription lifetimes are decoupled from NETCONF sessions. 3.4.1. Establishing a Configured Subscription For subscription establishment, a NETCONF client may send: Gonzalez Prieto, et al. Expires December 9, 2017 [Page 11] Internet-Draft NETCONF-notifications June 2017 1922 foo
1.2.3.4
1234
Figure 16: Establish static subscription if the request is accepted, the server would reply: Figure 17: Response to a successful static subscription establishment if the request is not accepted because the server cannot serve it, no configuration is changed. Int this case the server may reply: Gonzalez Prieto, et al. Expires December 9, 2017 [Page 12] Internet-Draft NETCONF-notifications June 2017 application resource-denied error</error-severity> Temporarily the server cannot serve this subscription due to the current workload. Figure 18: Response to a failed static subscription establishment For every configured receiver, once NETCONF transport session between the server and the receiver is recognized as active, the server will issue a "subscription-started" notification. After that, the server will send notifications to the receiver as per the subscription notification. Note that the server assumes that the receiver is ready to accept notifications on the NETCONF session. This may require coordination between the client that configures the subscription and the clients for which the notifications are intended. This coordination is out of the scope of this document. 3.4.2. Call Home for Configured Subscriptions Once this configuration is active, if NETCONF transport is needed but does not exist to one or more target IP address plus port, the server initiates a transport session via [RFC8071] to those receiver(s) in the subscription using the address and port specified. 3.4.3. Full Establish Message Flow Gonzalez Prieto, et al. Expires December 9, 2017 [Page 13] Internet-Draft NETCONF-notifications June 2017 +----------+ +-----------+ +---------+ +---------+ | Client | | Server | | Rcver A | | Rcver B | +----------+ +-----------+ +---------+ +---------+ | | | | | Capability Exchange | | | |<-------------------------->| | | | | | | | | | | | Edit-config | | | |--------------------------->| | | | RPC Reply: OK | | | |<---------------------------| | | | | Call Home | | | |<-------------->| | | |<--------------------------->| | | | | | | Subscription | | | | Started | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | | | Notification | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | Figure 19: Message flow for configured subscription establishment 3.4.4. Modifying a Configured Subscription Configured subscriptions can be modified using configuration operations against the top-level subtree subscription-config. For example, the subscription established in the previous section could be modified as follows, choosing a different receiver: Gonzalez Prieto, et al. Expires December 9, 2017 [Page 14] Internet-Draft NETCONF-notifications June 2017 1922 foo
1.2.3.5
1234
Figure 20: Modify configured subscription if the request is accepted, the server would reply: Figure 21: A successful configured subscription modification 3.4.4.1. Message Flow Example Gonzalez Prieto, et al. Expires December 9, 2017 [Page 15] Internet-Draft NETCONF-notifications June 2017 +----------+ +-----------+ +---------+ +---------+ | Client | | Server | | Rcver A | | Rcver B | +----------+ +-----------+ +---------+ +---------+ | | | | | Capability Exchange | | | |<-------------------------->| | | | | | | | | | | | Edit-config | | | |--------------------------->| | | | RPC Reply: OK | | | |<---------------------------| | | | | Call Home | | | |<-------------->| | | |<--------------------------->| | | | | | | Subscription | | | | Started | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | | | Notification | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | | Edit-config | | | |--------------------------->| | | | RPC Reply: OK | | | |<---------------------------| | | | | Subscription | | | | Modified | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | | | Notification | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | Figure 22: Message flow for subscription modification (configured subscription) Gonzalez Prieto, et al. Expires December 9, 2017 [Page 16] Internet-Draft NETCONF-notifications June 2017 3.4.5. Deleting a Configured Subscription Subscriptions can be deleted using configuration operations against the top-level subtree subscription-config. For example: 1922 Figure 23: Deleting a configured subscription 3.4.5.1. Message Flow Example Gonzalez Prieto, et al. Expires December 9, 2017 [Page 17] Internet-Draft NETCONF-notifications June 2017 +----------+ +-----------+ +---------+ +---------+ | Client | | Server | | Rcver A | | Rcver B | +----------+ +-----------+ +---------+ +---------+ | | | | | Capability Exchange | | | |<-------------------------->| | | | | | | | | | | | Edit-config | | | |--------------------------->| | | | RPC Reply: OK | | | |<---------------------------| | | | | Call Home | | | |<-------------->| | | |<--------------------------->| | | | | | | Subscription | | | | Started | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | | | | | | | Notification | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | | Edit-config | | | |--------------------------->| | | | RPC Reply: OK | | | |<---------------------------| | | | | Subscription | | | | Terminated | | | | (id 22) | | | |--------------->| | | |---------------------------->| | | | | Figure 24: Message flow for subscription deletion (configured subscription) 3.4.6. Event (Data Plane) Notifications Once a dynamic or configured subscription has been created, the NETCONF server sends (asynchronously) event notifications from the subscribed stream to receiver(s) over NETCONF. We refer to these as data plane notifications. Gonzalez Prieto, et al. Expires December 9, 2017 [Page 18] Internet-Draft NETCONF-notifications June 2017 The following is an example of an event notification from [RFC6020]: notification link-failure { description "A link failure has been detected"; leaf if-name { type leafref { path "/interface/name"; } } leaf if-admin-status { type admin-status; } leaf if-oper-status { type oper-status; } } Figure 25: Definition of a data plane notification This notification might result in the following, prior to it being placed into NETCONF. Note that the mandatory eventTime and Subscription id have been added. 2007-09-01T10:00:00Z 39 so-1/2/3.0 up down Figure 26: Data plane notification The equivalent using JSON encoding would be Gonzalez Prieto, et al. Expires December 9, 2017 [Page 19] Internet-Draft NETCONF-notifications June 2017 2007-09-01T10:00:00Z 39 { "acme-system:link-failure": { "if-name": "so-1/2/3.0", "if-admin-status": "up", "if-oper-status": "down" } } Figure 27: Data plane notification using JSON encoding 3.4.7. Control Plane Notifications In addition to data plane notifications, a server may send control plane notifications (defined in [subscribe]) to indicate to receivers that an event related to the subscription management has occurred. Control plane notifications cannot be filtered out. Next we exemplify them using both XML, and JSON encodings for the notification-specific content: 3.4.7.1. subscription-started and subscription-modified A subscription-started would look like: 2007-09-01T10:00:00Z 39 xpath Figure 28: subscription-started control plane notification The equivalent using JSON encoding would be: Gonzalez Prieto, et al. Expires December 9, 2017 [Page 20] Internet-Draft NETCONF-notifications June 2017 2007-09-01T10:00:00Z { "notif-bis:subscription-started": { "identifier" : 39 ((Open Item: express everything including the filter in json)) } } Figure 29: subscription-started control plane notification (JSON) The subscription-modified is identical, with just the word "started" being replaced by "modified". 3.4.7.2. notification-complete, subscription-resumed, and replay- complete A notification-complete would look like: 2007-09-01T10:00:00Z 39 Figure 30: notification control plane notification XML The equivalent using JSON encoding would be: 2007-09-01T10:00:00Z { "netmod-notif:notification-complete": { "identifier" : 39 } Figure 31: notification control plane notification JSON Gonzalez Prieto, et al. Expires December 9, 2017 [Page 21] Internet-Draft NETCONF-notifications June 2017 The subscription-resumed and replay-complete are virutally identical, with "notification-complete" simply being replaced by "subscription- resumed" and "replay-complete" in both encodings. 3.4.7.3. subscription-terminated and subscription-suspended A subscription-terminated would look like: 2007-09-01T10:00:00Z 39 no-such-subscription Figure 32: subscription-modified control plane notification The above, and the subscription-suspended are virutally identical, with "subscription-terminated" simply being replaced by "subscription-suspended". 3.4.7.4. Notification Message Flow Examples Gonzalez Prieto, et al. Expires December 9, 2017 [Page 22] Internet-Draft NETCONF-notifications June 2017 +------------+ +-----------+ | Client | | Server | +------------+ +-----------+ | | | Capability Exchange | |<---------------------------->| | | | Establish Subscription | |<---------------------------->| | | | Notification | |<-----------------------------| | | | | | Subscription Suspended | |<-----------------------------| | | | | | | | Subscription Resumed | |<-----------------------------| | | | Notification | |<-----------------------------| | | Figure 33: subscription-suspended and Resumed Notifications Gonzalez Prieto, et al. Expires December 9, 2017 [Page 23] Internet-Draft NETCONF-notifications June 2017 +----------+ +-----------+ +---------+ +---------+ | Client | | Server | | Rcver A | | Rcver B | +----------+ +-----------+ +---------+ +---------+ | | | | | Capability Exchange | | | |<-------------------------->| | | | | | | | Edit-config | | | |--------------------------->| | | | RPC Reply: OK | | | |<---------------------------| | | | | Subscription | | | | Started | | | |--------------->| | | |---------------------------->| | | | | | | Notification | | | |--------------->| | | |---------------------------->| | | | | | | Subscription | | | | Suspended | | | |--------------->| | | | | | | | Notification | | | |---------------------------->| | | | | | | Subscription | | | | Resumed | | | |--------------->| | | | | | | | Notification | | | |--------------->| | | |---------------------------->| | | | | Figure 34: Suspended and resumed for a single configured receiver 4. Security Considerations The elements are never sent before the transport layer and the NETCONF layer, including capabilities exchange, have been established and the manager has been identified and authenticated. A secure transport must be used and the server must ensure that the user has sufficient authorization to perform the function they are requesting against the specific subset of content involved. Gonzalez Prieto, et al. Expires December 9, 2017 [Page 24] Internet-Draft NETCONF-notifications June 2017 The contents of notifications, as well as the names of event streams, may contain sensitive information and care should be taken to ensure that they are viewed only by authorized users. The NETCONF server MUST NOT include any content in a notification that the user is not authorized to view. If a malicious or buggy NETCONF client sends a number of requests, then these subscriptions accumulate and may use up system resources. In such a situation, subscriptions MAY be terminated by terminating the suspect underlying NETCONF sessions. The server MAY also suspend or terminate a subset of the active subscriptions on the NETCONF session . Configured subscriptions from one or more publishers could be used to overwhelm a receiver, which perhaps doesn't even support subscriptions. Clients that do not want pushed data need only terminate or refuse any transport sessions from the publisher. The NETCONF Authorization Control Model [RFC6536] SHOULD be used to control and restrict authorization of subscription configuration. This control models permits specifying per-user permissions to receive specific event notification types. The permissions are specified as a set of access control rules. 5. 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, Kent Watsen, and Guangying Zheng. 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . Gonzalez Prieto, et al. Expires December 9, 2017 [Page 25] Internet-Draft NETCONF-notifications June 2017 [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, . [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, DOI 10.17487/RFC6536, March 2012, . [RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home", RFC 8071, DOI 10.17487/RFC8071, February 2017, . 6.2. Informative References [subscribe] Voit, Eric., Clemm, A., Gonzalez Prieto, A., Nilsen- Nygaard, E., and A. Tripathy, "Subscribing to Event Notifications", April 2016, . [yang-push] Clemm, A., Gonzalez Prieto, A., Voit, Eric., Tripathy, A., and E. Nilsen-Nygaard, "Subscribing to YANG datastore push updates", April 2017, . Appendix A. Changes between revisions (To be removed by RFC editor prior to publication) A.1. v01 to v03 o Text simplifications throughout o v02 had no meaningful changes A.2. 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). Gonzalez Prieto, et al. Expires December 9, 2017 [Page 26] Internet-Draft NETCONF-notifications June 2017 o Editorial improvements. Authors' Addresses Alberto Gonzalez Prieto VMWare Email: alberto.gonzalezprieto@yahoo.com Alexander Clemm Huawei Email: ludwig@clemm.org Eric Voit Cisco Systems Email: evoit@cisco.com Einar Nilsen-Nygaard Cisco Systems Email: einarnn@cisco.com Ambika Prasad Tripathy Cisco Systems Email: ambtripa@cisco.com Gonzalez Prieto, et al. Expires December 9, 2017 [Page 27]