I2RS working group S. Hares
Internet-Draft Huawei
Intended status: Standards Track March 15, 2016
Expires: September 16, 2016

I2RS protocol strawman


This document provides a strawman proposal for the I2RS protocol covering the ephemeral data store and data flow requirements not covered by i2rs publication/subscription service or traceability. It also proposes additions to YANG for the ephemeral data store and for additional data flow requirements. It proposes additions to the NETCONF and RESTCONF for these additions. Future versions of this document will propose changes to support the I2RS protocol security requirements.

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Table of Contents

1. Introduction

This documents is a strawman for I2RS higher level protocol. The I2RS protocol is a higher level protocol is comprised of a set existing protocols which have been extended to work together to support a new interface to the routing system.

This draft is input to a NETCONF review and design team.

This strawman proposal for the I2RS protocol covers the ephemeral data store and data flow requirements not covered by I2RS publication/subscription service or traceability. It also proposes additions to YANG for the ephemeral data store and for these additional data flow requirements. It also proposes extensions to NETCONF and RESTCONF to support ephemeral state and I2RS.

draft-hares-i2rs-protocol-strawman-examples (pending) provides examples of this strawman protocol use for I2RS. This draft uses a simple thermostat model to illustrate commands.

1.1. Ephemeral Changes

This document proposes additions to support ephemeral state in the datastores supported by NETCONF and RESTCONF, and in the YANG modules that define these data stores. The requirements for the I2RS ephemeral state are covered in [I-D.ietf-i2rs-ephemeral-state]

This draft provides suggests the following additions to support the I2RS ephemeral state:

1.2. Data Flow Changes

This document proposes additions to support data flows from different data models for large data flows, traffic monitoring, actions and OAM interaction, and flows during outages or attacks. The requirements for these changes are define in [I-D.hares-i2rs-dataflow-req].

Most large data flows will be handled utilizing the publication/subscription service define in the I2RS publication/subscription service requirements specified in [I-D.ietf-i2rs-pub-sub-requirements]. Extensions to NETCONF to support a push publication/subscription service have been defined in [I-D.ietf-netconf-yang-push]. This document does not propose a pull publication/subscription (pull pub-sub) service for the first set of component protocols for the I2RS higher level protocol. If deployments require the pull pub-sub service, then an expansion of the push service can provide one mechanism.

This document does provide support for the I2RS protocol to:

2. Definitions Related to Ephemeral Configuration

Currently the configuration systems managed by NETCONF ([RFC6241]) or RESTCONF ([I-D.ietf-netconf-restconf]) have three types of configuration: candidate, running, and startup running under the config=true flag.

The config=false flag has operational data which exists alongside the config=true data. However, at this point there is no datastored defined for configuration false.

 ...........      ...........     ...........
 :Candidate : --> : running : --> :start-up  :
 ...........      ...........     ...........
 config true
 config false    

 Figure 1 				

The [I-D.ietf-netmod-opstate-reqs] defines new terms to clarify how this works. In reality, the running configuration becomes the intended configuration that is intended to be loaded into a device. The loading of the update into the system can be either asynchronous or synchronous. In the asynchronous case, the netconf server responds to the client after the intended has been updated, but the applied configuration is only updated later when the configuration change has full impacted all components on the device. The synchronous configuration operation occurs when both the intent configuration has been updated and the actual configuration has been loaded after resolving the necessary things to load in a box.

This document will use the terms defined in [I-D.ietf-netmod-opstate-reqs].

 ...........      ...........     ...........
 :Candidate : --> : running : --> :start-up :
 ...........      ......||...     ...........
                 | Intended      |   
                 | configuration |   
 config true           ||
 config false          ||
      | operational    ||      |
      | state          ||      | 
      |       =========||==    |
      |       | Applied   |    |
      |       | config    |    |
      |       =============    |
      |       _____________    |
      |       |  derived  |    |
      |       |  state    |    |
      |       |___________|    |
 Figure 2 				

3. Definition of ephemeral datastore for NETCONF/RESTCONF

This section describes the properties of the ephemeral datastore. The ephemeral datastore is not unique to I2RS. This approach to the ephemeral datastore is a panes-of-glass model. This definition of I2RS does not support caching in the I2RS Agents. Future I2RS work may reconsidered supporting caching.

 ............    ...............   ...........
 :Candidate :-->: running      :-->:start-up :
 ............    ..|............   ...........
 :ephemeral :      | :ephemeral:
 : candidate:      | : running :
 ............      | ........|..
                   |         | 
                   |         |
        | Intended         Ephemeral   | 
        | configuration   Intended     |  
        |                 Configuration| 
 config true        ||            
 config false       ||
      | operational ||                    |
      | state       ||                    |
      |       ======||=================== |
      |       | Applied  Configuration  | |
      |       |(from normal + ephemeral)| |
      |       |                         | | 
      |       ==========================  |
      |       _________________________   |
      |       |  derived  state        |  |
      |       |from normal + ephemeral)|  |  
      |       |  RIB and protocols     |  | 
      |       |________________________|  | 
 Figure 3 				

The ephemeral data store has the following qualities:

  1. Ephemeral state is not unique to I2RS work.
  2. The ephemeral datastore is never locked.
  3. The ephemeral datastore is really a portion of the candidate, running, and intended configuration that does not persist over a reboot.

  4. The applied configuration is the result of the the intent configuration (normal and ephemeral). Similarly, the derived data is a result of the applied configuration.
  5. Ephemeral portions (node, tree, or data model) need to be signalled in the conformance portions of the NETCONF and RESTCONF work. Conformance is signalled in the following ways:

  6. The ephemeral data store is treated as one pane of glass that an I2RS client(s) may read/write which has the following implications:

4. Error handling

Ephemeral nodes level of validation/error handling in the I2RS protocol has three following three types:

The default error handling is "no referential checking".

Normal error handling of I2RS Agent for an I2RS client's information examines the following:

The full error handling status includes all checks included for any normal YANG data module uses by NETCONF/RESTCONF. This includes referential checks for leafref checks, MUST clauses, and instance identifiers.

The I2RS Data model sets permissible range of error handling for writes on a data model (none, I2RS normal, full), and this may be further restricted by an operator applied policy. If an I2RS client requests a lower level of error handling that permissible, the I2RS Agent will return an error.

Multiple I2RS clients writing to the same variable is considered an "error condition" in the I2RS architecture [I-D.ietf-i2rs-architecture], but the I2RS Agent must handle this error condition. Upon multiple I2RS clients writing, the ephemeral data store allows for priority pre-emption of the write operation. Priority pre-emption means each I2RS client of the ephemeral I2RS agent (netconf server) is associated with a priority. Priority pre-emption occurs when a I2RS client with a higher priority writes a node which has been written by an I2RS client (with the lower priority). At this point, the I2RS agent (netconf server) allows the write and provides a notification indication to the notification publication/subscription service.

This section describes the ephemeral data stores handling of each of these error functions.

4.1. Syntax validation

Syntax validation of the message should be done according to the NETCONF or RESTCONF protocol features. New features for ephemeral datastore should provide the error handling with the feature. Message syntax validation can be for read, write, or rpc functions.

Syntax validation of the data model included in the ephemeral data store should be done by I2RS Agent.

4.2. Referential validation

The ephemeral data store normal processing does not do the following referencial checks: leafref, MUST, instance identifier. The removal of these validations allows for intelligent I2RS clients to rapidly read or write data, and handle error conditions at a higher level.

4.3. Grouping and Error handling

Yang 1.0 and Yang 1.1 provide the ability to group data in groupings, leafref lists, lists, and containers. Data model group data in order to group data that is logically associated with one another. Data models may logical group data across groupings. One example of such an association is the association of a static route with an interface. The concepts of groupings apply to both ephemeral and non-ephemeral nodes within a data model.

4.3.1. Initial Support of Parital Writes

The initial releases of I2RS will only require "all-or-nothing" in the I2RS Agent.

4.3.2. Future Scope of multiple message writes

Error handling on writes of the ephemeral datastore is different for nodes that are grouped versus orthogonal. Group nodes may need to be all changed or all removed (all-or-nothing). In contrast, writing orthogonal data nodes in the same data module or between data models need to be added or deleted in sync.

The [I-D.ietf-i2rs-architecture] specifies three types of error handling for a partial write operation: "all-or-nothing", "stop-on-error", or "continue-on-error". Partial write operations of "stop-on-error" or "continue-on-error" are allowed only for data writes which are not a part of a grouping within a data model. The definition of the I2RS error conditions are: NETCONF Support of Partial Writes

NETCONF does not support a mandated sequencing of edit functions or write functions. Without this mandated sequences, NETCONF cannot support partial edits. RESTCONF Support of Partial Writes

RESTCONF has a complete set of operations per message. The RESTCONF patch can support write functions per messages.

4.4. priority preemption

I2RS protocol uses priority to resolve two I2RS clients having permissions to write the same pieces of data in an I2RS agent (NETCONF server). If two (or more) I2RS clients attempt to write the same data, the the one with the highest priority is enable to write the data. In the case of two clients with teh sample priority attempting to write data, the the first one to request write wins.

Each client has a unique priority. Client identities and priorities are assigned outside of I2RS by exterior mechanisms such as AAA or adminstrative interfaces. A valid I2RS client must have both an identity and a priority.

A client-id and priority must be saved per node.

   container i2rs-clients {
       leaf max-clients {
          config false;
          mandatory true;
          type uint32 {
            range "1 .. max";
       list i2rs-client {
          key name;
          unique priority;
          leaf name { ... }
          leaf priority { ... }
 Figure 4 				

A sample container for I2RS client information is shown below.

4.4.1. Andy Bierman Priority Comment

(Andy)The priority is not required to be densely numbered. Whether there are 1 pane per client or 1 pane per priority or 1 giant blob full of everything, the code will be the same. The goal of "unique priority" is to require that only priority be saved in the meta-data for the ephemeral datastore. Without that, client-id and priority must be saved (per data node).

5. transport protocol

5.1. Secure Protocols

NETCONF's XML-based protocol ([RFC6241]) can operate over the following secure and encrypted transport layer protocols:

RESTCONF's XML-based or JSON [RFC7158] data encodings of Yang functions are passed over http with (GET, POST, PUT, PATCH, DELETE, OPTIONS, and HEAD).

5.2. Insecure Protocol

The ephemeral database may support insecure protocols for information which is ephemeral state which does not engage in configuration. The insecure protocol must be defined in conjunction with a data model or a subdata model.

6. Yang Library Use by Ephemeral

The data modules supporting the ephemeral datastore can use the Yang module library to describe their datastore. Figure 5 shows the module library data structure as found [I-D.ietf-netconf-yang-library]. The I2RS modules will provide features for I2RS ephemeral state and protocol of:

  +--ro modules 
     +--ro module*[name revision] 
        +--ro name  yang: yang-identifier
        +--ro revision  union; 
        +--ro schema?   inet:uri
        +--ro namespace   inet:uri
        +--ro feature*    yang:yang-identifier			
        +--ro deviation* [name revision] 
        |  +-- ro name   yang:yang-identifier
        |  +-- ro revision union
        +--ro conformance enumeration 
        +--ro submodules
           +--ro submodule*[name revision]
              +--ro name yang:yang-identifier 
              +--ro revision  union
              +--ro schema?  inet:uri 
			  Figure 5 

7. Simple Thermostat Model

In this discussion of ephemeral configuration, this draft utilizes a simple thermostat model with the YANG configuration found in figure 6.

module thermostat {
  leaf desired-temp {
     type int32;
	 units "degrees Celsius";
	 description "The desired temperature";
  leaf actual-temp {
     type int32;
	 config false;
	 units "degrees Celsius";
	 description "The measured temperature
	 (operational state).";

Figure 6 - Simple thermostat model yabng

 ...........     ...................    ...........
 :Candidate :---:running config    :--: start-up  :
 :          :   :desired-temp (cfg):  :           :
 ...........     ..................    ...........
                       |  :ephemeral : 
                       |  :config    -----|
                       |  :          :    |
                       |  ..|....|....    |
                       |    |    |   =============
                       |    |    |   |I2rs Client|
                       |    |     \  |scheduler  |
                       V    V      \ ============
              ..................    \
 Intended     . '''''''''''''''      ==============
   Config     . 'desired-temp'       |I2RS Client |
              . '''''''''^'''' .     | hold temp  |   
              .          |     .     ==============
 config true             |                     
 config false            | (config down,
                         V  status of config up)     
                 | Actual    |============ I2RS clients 
                 | config    |
                 | actual temp  |========== I2RS Clients 
                 | (op-state)   |
Figure 6 - Two I2RS clients 

Figure 6 shows two I2RS clients talking to this model: scheduler and hold-temp. Scheduler has a schedule set of temperatures to put in the thermostat. Hold-temp holds the temperature at the same value. The hold-temp I2RS client has a higher priority than the scheduler client.

7.1. Yang changes

Yang needs to adds key word ephemeral with the following key words:

module thermostat {
  leaf desired-temp {
     type int32;
	 units "degrees Celsius";
	 ephemeral true;
	 ephemeral-validation full-check;
	 description "The desired temperature";
  leaf actual-temp {
     type int32;
	 config false;
	 units "degrees Celsius";
	 description "The measured temperature";

Figure 7 - Simple Thermostat Yang with ephemeral 

7.2. RESTCONF sequence

RESTCONF running data store

PUT /restconf/data/thermostat:desired-temp

RESTCONF ephemeral datastore 

PUT /restconf/data/thermostat:desired-temp?datastore=ephemeral
{"desired-temp":19 }

Figure 8 - RESTCONF setting of ephemeral state 

Figure 7 shows the thermostat model has ephemeral variable desired-temp in the running configuration and the ephemeral data store. The RESTCONF way of addressing is below:

7.3. NETCONF messages

     <ephemeral >
	 </ephemeral >
      <top xmlsns="http:://example.com/schema/1.0/thermostat/config>
       <desired-temp> 18 </desired-temp>

Note: config=TRUE; datastore = ephemeral

figure 8 NETCONF setting of desired-temp     

The NETCONF way of transmitting this data would be

8. NETCONF protocol extensions for the ephemeral datastore

capability-name: ephemeral-datastore

8.1. Overview

This capability defines the NETCONF protocol extensions for the ephemeral state. The ephemeral state has the following features:

8.2. Dependencies

The following are the dependencies for ephemeral support:

8.3. Capability identifier

The ephemeral-datastore capability is identified by the following capability string: (capability uri)

8.4. New Operations

8.4.1. link-ephemeral

The <link-ephemeral> allows the ephemeral datastore to be a pane of glass that impacts either the running-config configuration pane of glass or the candidate configuration pane of glass.

<link-ephemeral> target-config 

where target config is: 
writable-running or candidate config. 

8.4.2. Bulk-Write

Bulk Write allows for large scale writes with error handling that is specified as syntax or reduced or full. Alternatively, the data modules can utilize an RPC to do bulk reads/writes. The bulk write will be first check for other I2RS clients having a higher priority write value for any of the values.

Editor: Do we need something beyond rpc for bulk data writes?

8.5. Modification to existing operations

The capability for :ephemeral-datastore modifies the target for existing operations.

8.5.1. <get-config>

The :ephemeral-datastore capability modifies the <edit-config> to accept the <ephemeral> as a target for source, and allows the filters focused on a particular module, submodule, or node.

The positive and negative responses remain the same.

Example - retrieve users subtree from 
          ephemeral database

 <rpc message-id="101"
      <filter type="subtree">
        <top xmlns="http://example.com/schema/1.0/thermostat/config">

8.5.2. <edit-config>

The :ephemeral-datastore capability modifies the <edit-config> to accept the <ephemeral> as a target for source with filters. The operations of merge, replace, create, delete, and remove are available, but each of these operations is modified by the priority write as follows:

The existing parameters are modified as follows:

8.5.3. <copy-config>

Copy config allows for the complete replacement of all the ephemeral nodes within a target. The alternation is that source is the :ephemeral datastore with the filtering to match the datastore. The following existing parameters are modified as follows:

8.5.4. <delete-config>

The delete will delete all ephemeral nodes out of a datastore. The target parameter must be changed to allow :ephemeral-datastore. and filters.

8.5.5. <lock> and <unlock>

Lock and unlock are not supported with a target of :ephemeral-datastore.

8.5.6. <get>

The <get> is altered to allow a target of :ephemeral-datastore and with the filters.

8.5.7. <close-session> and <kill-session>

The close session is modified to take a target of :ephemeral-datastore Since no locks are set, none should be released.

The kill session is modified to take a target of "ephemeral-datastore. Since no locks are set, none should be released.

8.6. Interactions with Capabilities

[RFC6241] defines NETCONF capabilities for writeable-running datastore, candidate config data store, confirmed commit, rollback-on-error, validate, distinct start-up, URL capability, and XPATH capability.

8.6.1. writable-running and candidate datastore

The writeable-running and the candidate datastore can be used in conjunction with the ephemeral data store. Ephemeral database overlays an intended configuration, and may overlay candidate and running configuration data store. The <link-ephemeral> operation links to these two databases.

8.6.2. confirmed commmit

Confirmed commit capability is not supported for the ephemeral datastore.

8.6.3. rollback-on-error

The rollback-on-error when included with ephemeral state allows the error handling to be "all-or-nothing" (roll-back-on-error).

8.6.4. validate

The <validate> key word is expanded to support the following:

8.6.5. Distinct Startup Capability

This NETCONF capability appears to operate to load write-able running config, running-config, or candidate datastore. The ephemeral state does not change the environment based on this command.

8.6.6. URL capability and XPATH capability

The URL capabilities specify a <url> in the <source> and <target>. The initial suggestion to allow both of these features to work with ephemeral operation.

9. RESTCONF protocol extensions for the ephemeral datastore

capability-name: ephemeral-datastore

9.1. Overview

This capability defines the RESTCONF protocol extensions for the ephemeral state. The ephemeral state has the features described in the previous section on NETCONF.

9.2. Dependencies

The ephemeral capabilities have the following dependencies:

9.3. Capability identifier

The ephemeral-datastore capability is identified by the following capability string: (capability uri)

9.4. New Operations


9.5. modification to data resources

RESTCONF must be able to support the ephemeral datstore with its rules as part of the "{+restconf}/data" subtree. The "edit collision" features in RESTCONF must be able to provide notification to I2RS read functions or to rpc functions. The "timestamp" with a last modified features must support the traceability function.

The "Entity Tag" could support saving a client-priority tuple as a opaque string, but it is important that that additions be made to restore client-priority so it can be compared with stromgs to be added.

9.6. Modification to existing operations

The current operations in RESTCONF are: OPTIONS, HEAD, GET, POST, PUT, PATCH, and DELETE. This section describes the modification to these exiting operations.

9.6.1. OPTIONS changes

The options methods should be augmented by the [I-D.ietf-netconf-yang-library] information that will provide an indication of what ephemeral state exists in a data modules, or a data modules sub-modules or nodes.

9.6.2. HEAD changes

The HEAD in retrieving the headers of a resources. It would be useful to changes these headers to indicate the datastore a node or submodule or module is in (ephemeral or normal), and allow filtering on ephemeral nodes or trees, submodules or module.

9.6.3. GET changes

GET must be able to read from the URL and a particular datastore. Similarly, it is important the Get be able to determine if it is a ephemeral data store.

9.6.4. POST changes

POST must simply be able to create resources in ephemeral datastores ("=datastore=ephemeral") and invoke operations defined in ephemeral data models using the rules of the ephemeral database.

9.6.5. PUT changes

PUT must be able to reference an ephemeral module, sub-module, and nodes ("?datastore=ephemeral").

9.6.6. PATCH changes

Plain PATCH must be able to update or create child resources in an ephemeral datastore ("?datstore=ephemeral") The PATCH for the ephemeral state must be change to provide a merge or update of the original data only if the client's using the patch has a higher priority than an existing datastore's client, or if PATCH requests to create a new node, sub-module or module in the datastore.

9.6.7. DELETE changes

The phrase "?datastore=ephemeral" following an element will specify the ephemeral data store when deleting entry.

9.6.8. Query Parameters

The query parameters (content, depth, fields, insert, point, start-time, stop-time, and with-defaults (report-all, trim, explicit, report-all-tagged) must support ephemeral datastores ("?datastore=ephemeral") described above.

9.7. Interactions with Notifications

The ephemeral database must support subscribing to receiving notifications as Event stream. The event error stream processing should support the publication/subscription mechanisms for ephemeral state defined in [I-D.ietf-netconf-yang-push].

9.8. Interactions with Error Reporting

The ephemeral database] support in RESTCONF must also support passing error information regarding ephemeral data access over to RESTCONF equivalent of the and traceability client.

10. IANA Considerations

This is a protocol strawman - nothing is going to IANA.

11. Security Considerations

The security requirements for the I2RS protocol are covered in [I-D.ietf-i2rs-protocol-security-requirements]. The security environment the I2RS protocol is covered in [I-D.ietf-i2rs-security-environment-reqs]. Any person implementing or deploying the I2RS protocol should consider both security requirements.

12. Acknowledgements

This document is an attempt to distill lengthy conversations on the I2RS proto design team from August

Here's the list of the I2RS protocol design team members

13. Major Contributors

14. References

14.1. Normative References:

[I-D.hares-i2rs-dataflow-req] Hares, S., "I2RS Data Flow Requirements", Internet-Draft draft-hares-i2rs-dataflow-req-01, March 2016.
[I-D.ietf-i2rs-architecture] Atlas, A., Halpern, J., Hares, S., Ward, D. and T. Nadeau, "An Architecture for the Interface to the Routing System", Internet-Draft draft-ietf-i2rs-architecture-13, February 2016.
[I-D.ietf-i2rs-ephemeral-state] Haas, J. and S. Hares, "I2RS Ephemeral State Requirements", Internet-Draft draft-ietf-i2rs-ephemeral-state-02, September 2015.
[I-D.ietf-i2rs-protocol-security-requirements] Hares, S., Migault, D. and J. Halpern, "I2RS Security Related Requirements", Internet-Draft draft-ietf-i2rs-protocol-security-requirements-03, March 2016.
[I-D.ietf-i2rs-pub-sub-requirements] Voit, E., Clemm, A. and A. Prieto, "Requirements for Subscription to YANG Datastores", Internet-Draft draft-ietf-i2rs-pub-sub-requirements-05, February 2016.
[I-D.ietf-i2rs-rib-data-model] Wang, L., Ananthakrishnan, H., Chen, M., amit.dass@ericsson.com, a., Kini, S. and N. Bahadur, "A YANG Data Model for Routing Information Base (RIB)", Internet-Draft draft-ietf-i2rs-rib-data-model-04, November 2015.
[I-D.ietf-i2rs-rib-info-model] Bahadur, N., Kini, S. and J. Medved, "Routing Information Base Info Model", Internet-Draft draft-ietf-i2rs-rib-info-model-08, October 2015.
[I-D.ietf-i2rs-security-environment-reqs] Migault, D., Halpern, J. and S. Hares, "I2RS Environment Security Requirements", Internet-Draft draft-ietf-i2rs-security-environment-reqs-00, October 2015.
[I-D.ietf-i2rs-traceability] Clarke, J., Salgueiro, G. and C. Pignataro, "Interface to the Routing System (I2RS) Traceability: Framework and Information Model", Internet-Draft draft-ietf-i2rs-traceability-07, February 2016.
[I-D.ietf-netconf-restconf] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", Internet-Draft draft-ietf-netconf-restconf-09, December 2015.
[I-D.ietf-netconf-yang-library] Bierman, A., Bjorklund, M. and K. Watsen, "YANG Module Library", Internet-Draft draft-ietf-netconf-yang-library-04, February 2016.
[I-D.ietf-netconf-yang-patch] Bierman, A., Bjorklund, M. and K. Watsen, "YANG Patch Media Type", Internet-Draft draft-ietf-netconf-yang-patch-07, December 2015.
[I-D.ietf-netconf-yang-push] Clemm, A., Prieto, A., Voit, E., Tripathy, A. and E. Einar, "Subscribing to YANG datastore push updates", Internet-Draft draft-ietf-netconf-yang-push-01, February 2016.
[I-D.ietf-netmod-opstate-reqs] Watsen, K. and T. Nadeau, "Terminology and Requirements for Enhanced Handling of Operational State", Internet-Draft draft-ietf-netmod-opstate-reqs-04, January 2016.
[I-D.ietf-netmod-yang-metadata] Lhotka, L., "Defining and Using Metadata with YANG", Internet-Draft draft-ietf-netmod-yang-metadata-04, February 2016.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011.
[RFC7158] Bray, T., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7158, DOI 10.17487/RFC7158, March 2014.
[RFC7589] Badra, M., Luchuk, A. and J. Schoenwaelder, "Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication", RFC 7589, DOI 10.17487/RFC7589, June 2015.

14.2. Informative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "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.

Author's Address

Susan Hares Huawei Saline, US EMail: shares@ndzh.com