System-defined Configuration

4.1. Read-only to Clients

The system datastore is a read-only configuration datastore (i.e., edits towards <system> directly MUST be denied), though the client may be allowed to override the value of a system-initialized data node (see Section 5.4).¶

4.2. May Change via Software Upgrades or Resource Changes

System configuration may change dynamically, e.g., depending on factors like device upgrade or if system-controlled resources (e.g., HW available) change. In some implementations, when a QoS feature is enabled, QoS-related policies are created by the system.¶

If the system configuration gets changed, YANG notifications (e.g., "push-change-update" notification) [RFC6470][RFC8639][RFC8641] can be used to notify the client. Any update of the contents in <system> will not cause the automatic update of <running>, even if some of the system configuration has already been copied into <running> explicitly or automatically before the update.¶

4.3. No Impact to <operational>

This work intends to have no impact to <operational>. System configuration appears in <operational> with "origin=system". This document enables a subset of those system generated nodes to be defined like configuration, i.e., made visible to clients in order for being referenced or configurable prior to present in <operational>. "Config false" nodes are out of scope, hence existing "config false" nodes are not impacted by this work.¶

5.1. Conceptual Model of Datastores

This document introduces a datastore named "system" which is used to hold all three types of system configurations defined in Section 2.¶

When the device is powered on, immediately-active system configuration will be generated in <system> and active immediately, but inactive-until-referenced system configuration only becomes active if it is referenced by client-defined configuration. While conditionally-active system configuration will only be created and active if the condition on system resources is met when the device is powered on or running.¶

All above three types of system configurations will appear in <system>. Clients MAY reference nodes defined in <system>, override values of configurations defined in <system>, and configure descendant nodes of system-defined nodes, by copying or writing intended configurations into the target configuration datastore (e.g., <running>).¶

Configuration in <system> is merged with the current configuration of the device in <running> after the configuration transformations (e.g., template expansion, removal of inactive configuration defined in [RFC8342]) to create the contents of <intended>, in which process, the data node appearing in <running> takes precedence over the same node in <system> if the server allows the node to be modifiable; additional nodes to a list entry or new list/leaf-list entries appearing in <running> extends the list entry or the whole list/leaf-list defined in <system> if the server allows the list/leaf-list to be updated. In addition, the intended configuration datastore represents the configuration after all configuration transformation to <system> are performed (e.g., system-defined template expansion, removal of inactive system configuration). If a server implements <intended>, <system> MUST be merged into <intended>.¶

As a result, Figure 2 in Section 5 of RFC 8342 is updated with the below conceptual model of datastores which incorporates the system configuration datastore.¶

             +-------------+                 +-----------+
             | <candidate> |                 | <startup> |
             |  (ct, rw)   |<---+       +--->| (ct, rw)  |
             +-------------+    |       |    +-----------+
                    |           |       |           |
      +-----------+ |         +-----------+         |
      | <system>  | +-------->| <running> |<--------+
      | (ct, ro)  |           | (ct, rw)  |
      +-----+-----+           +----+------+
            |                      |
            +--------+      +------+  // configuration transformations,
                     |      |         // e.g., removal of nodes marked
                     |      |         // as "inactive", expansion of
                     |      |         // templates
                     V      V
                  +------------+
                  | <intended> | // subject to validation
                  | (ct, ro)   |
                  +------------+
                        |        // changes applied, subject to
                        |        // local factors, e.g., missing
                        |        // resources, delays
                        |
   dynamic              |
   configuration        |   +-------- learned configuration
   datastores -----+    |   +-------- default configuration
                   |    |   |
                   v    v   v
                +---------------+
                | <operational> | <-- system state
                | (ct + cf, ro) |
                +---------------+

  ct = config true; cf = config false
  rw = read-write; ro = read-only
  boxes denote named datastores

Servers MUST enforce that configuration references in <running> are resolved within <running> and ensure that <running> contains any referenced system configuration. Clients MUST either explicitly copy system-defined nodes into <running> or use the "resolve-system" parameter. The server MUST enforce that the referenced system nodes configured into <running> by the client is consistent with <system>. Note that <system> aware clients know how to discover what nodes exist in <system>. How clients unaware of the system datastore can find appropriate configurations is beyond the scope of this document.¶

No matter how the referenced system configurations are copied into <running>, the nodes copied into <running> would always be returned as the result of a read of <running>, regardless if the client is <system> aware.¶

Configuration defined in <system> is merged into <intended>. It is also present in <operational> if it is in use by the device, even if a client may delete the configuration which is copied from <system> into <running>. For example, system initializes a value for a particular leaf which is overridden by the client with a different value in <running>. The client may delete that node in <running>, in which case system-initialized value defined in <system> can be still in use and appear in <operational>.¶

Applied system configuration regardless of explicitly or automatically being copied into <running>, appears in <operational> with origin="system".¶

Comment: this might need further discussion: should the origin="system" be required for system configuration copied/pasted into <running>?¶

Any deletable system-provided configuration that is populated as part of <running> by the system at boot up, without being part of the contents of a <startup> datastore, must be defined in <factory-default> [RFC8808], which is used to initialize <running> when the device is first-time powered on or reset to its factory default condition.¶

5.2. Explicit Declaration of System Configuration

It is possible for a client to explicitly declare system configuration nodes in the target datastore (e.g., <running>) with the same values as in <system>, by configuring a node (list/leaf-list entry, leaf, etc.) in the target datastore (e.g., <running>) that matches the same node and value in <system>.¶

The explicit configuration of system-defined nodes in the target datastore (e.g., <running>) can be useful, for example, when the client doesn't want a "system client" to have a role or hasn't implemented the "resolve-system" parameter but need the datastore to be valid. The client can explicitly declare (i.e., configure in the datastore like <running>) the list entries (with at least the keys) for any system configuration list entries that are referenced elsewhere in <running>. The client does not necessarily need to declare all the contents of the list entry (i.e. the descendant nodes) , only the parts that are required to make the datastore appear valid.¶

5.3. Servers Auto-configuring Referenced System Configuration ("resolve-system" parameter)

This document defines a new parameter "resolve-system" to the input for the <edit-config>, <edit-data>, and <copy-config> operations. Clients that are aware of the "resolve-system" parameter MAY use this parameter to avoid the requirement to provide a referentially complete configuration in <running>.¶

If the "resolve-system" is present, and the server supports this capability, the server MUST copy relevant referenced system-defined nodes into the target datastore (e.g., <running>) without the client doing the copy/paste explicitly, to resolve any references not resolved by the client. The server acting as a "system client" like any other remote clients copies the referenced system-defined nodes when triggered by the "resolve-system" parameter.¶

The server may automatically configure the list entries (with at least the keys) in the target datastore (e.g., <running>) for any system configuration list entries that are referenced elsewhere by the clients. Similarly, not all the contents of the list entry (i.e., the descendant nodes) are necessarily copied by the server - only the parts that are required to make <running> valid.¶

There is no distinction between the configuration in the target datastore (e.g., <running>) which is automatically configured by the server and the one explicitly declared by the client, e.g., a read back of the datastore (i.e., <get>, <get-config> or <get-data> operation) returns automatically configured nodes. Note that even an auto-configured node is allowed to be deleted from the target datastore by the client, the operation request (e.g., <edit-config>) may not succeed due to incomplete referential integrity, it is also possible that the system automatically configures the deleted node again to make configuration valid, when a "resolve-system" parameter is carried.¶

Once copied into <running>, system-instantiated node will not be removed or updated automatically even all references to it are deleted or system configuration no longer appears in <system> due to factors like system-controlled resources change (e.g., HW unavailable). That said, servers MAY upgrade system configuration as well as any copied system nodes in <running> when licensing change or device upgrade.¶

If the "resolve-system" parameter is not given by the client, the server should not modify <running> in any way otherwise not specified by the client. Not using capitalized "SHOULD NOT" in the previous sentence is intentional. The intention is to bring awareness to the general need to not surprise clients with unexpected changes. It is desirable for clients to always opt into using mechanisms having server-side changes. This document enables a client to opt into this behavior using the "resolve-system" parameter. An example of this type of opt-in behavior can also be found in RFC 7317, which enables a client to opt into its behavior using a "$0$" prefix (see ianach:crypt-hash type defined in [RFC7317]).¶

Support for the "resolve-system" parameter is OPTIONAL. Servers not supporting NMDA [RFC8342] MAY also implement this parameter without implementing the system configuration datastore, which would only eliminate the ability to expose the system configuration via protocol operations. If a server implements <system>, referenced system configuration is copied from <system> into the target datastore (e.g., <running>) when the "resolve-system" parameter is used; otherwise it is an implementation decision where to copy referenced system configuration into the target datastore (e.g., <running>).¶

Implementation specifics are beyond the scope of this document, however, due to the extra complexity brought by the "resolve-system" parameter, clients should be aware that it would cost a reasonable amount of time for the server to resolve reference, retrieve and copy the referenced system configuration from <system>, which could take multiple rounds since some errors may depend on the resolution of previous ones. Clients need to ensure that connections are alive during the server processing until a response is received.¶

5.5. Examples

This section shows some examples of server-configuring of <running> automatically, declaring a system-defined node in <running> explicitly, modifying a system-instantiated leaf's value and configuring descendant nodes of a system-defined node. For each example, the corresponding XML snippets are provided.¶

         module example-application {
           yang-version 1.1;
           namespace "urn:example:application";
           prefix "app";

           import ietf-inet-types {
             prefix "inet";
           }
           container applications {
             list application {
               key "name";
               leaf name {
                 type string;
               }
               leaf protocol {
                 type enumeration {
                   enum tcp;
                   enum udp;
                 }
               }
               leaf destination-port {
                 type inet:port-number;
               }
             }
           }
         }

        <applications xmlns="urn:example:application">
          <application>
            <name>ftp</name>
            <protocol>tcp</protocol>
            <destination-port>21</destination-port>
          </application>
          <application>
            <name>tftp</name>
            <protocol>udp</protocol>
            <destination-port>69</destination-port>
          </application>
          <application>
            <name>smtp</name>
            <protocol>tcp</protocol>
            <destination-port>25</destination-port>
          </application>
          ...
        </applications>

        <applications xmlns="urn:example:application">
          <application>
            <name>my-app-1</name>
            <protocol>tcp</protocol>
            <destination-port>2345</destination-port>
          </application>
          <application>
            <name>my-app-2</name>
            <protocol>udp</protocol>
            <destination-port>69</destination-port>
          </application>
        </applications>

         module example-acl {
           yang-version 1.1;
           namespace "urn:example:acl";
           prefix "acl";

           import example-application {
             prefix "app";
           }
           import ietf-inet-types {
             prefix "inet";
           }

           container acl {
             list acl_rule {
               key "name";
               leaf name {
                 type string;
               }
               container matches {
                 choice l3 {
                   container ipv4 {
                     leaf source_address {
                       type inet:ipv4-prefix;
                     }
                     leaf dest_address {
                       type inet:ipv4-prefix;
                     }
                   }
                 }
                 choice applications {
                   leaf-list application {
                     type leafref {
                     path "/app:applications/app:application/app:name";
                     }
                   }
                 }
               }
               leaf packet_action {
                 type enumeration {
                   enum forward;
                   enum drop;
                   enum redirect;
                 }
               }
             }
           }
         }

        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
          <edit-config>
            <target>
              <running/>
            </target>
            <config>
              <acl xmlns="urn:example:acl">
                <acl_rule>
                  <name>allow_access_to_ftp_tftp</name>
                  <matches>
                    <ipv4>
                      <source_address>198.51.100.0/24</source_address>
                      <dest_address>192.0.2.0/24</dest_address>
                    </ipv4>
                    <application>ftp</application>
                    <application>tftp</application>
                    <application>my-app-1</application>
                  </matches>
                  <packet_action>forward</packet_action>
                </acl_rule>
              </acl>
            </config>
            <resolve-system/>
          </edit-config>
        </rpc>

        <applications xmlns="urn:example:application">
          <application>
            <name>my-app-1</name>
            <protocol>tcp</protocol>
            <destination-port>2345</destination-port>
          </application>
          <application>
            <name>my-app-2</name>
            <protocol>udp</protocol>
            <destination-port>69</destination-port>
          </application>
          <application>
            <name>ftp</name>
          </application>
          <application>
            <name>tftp</name>
          </application>
        </applications>

        <applications xmlns="urn:example:application"
                      xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                      or:origin="or:intended">
          <application>
            <name>my-app-1</name>
            <protocol>tcp</protocol>
            <destination-port>2345</destination-port>
          </application>
          <application>
            <name>my-app-2</name>
            <protocol>udp</protocol>
            <destination-port>69</destination-port>
          </application>
          <application or:origin="or:system">
            <name>ftp</name>
            <protocol>tcp</protocol>
            <destination-port>21</destination-port>
          </application>
          <application or:origin="or:system">
            <name>tftp</name>
            <protocol>udp</protocol>
            <destination-port>69</destination-port>
          </application>
        </applications>

          <rpc message-id="101"
               xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
             <edit-config>
               <target>
                 <running/>
               </target>
               <config>
                 <applications xmlns="urn:example:application">
                   <application>
                     <name>ftp</name>
                   </application>
                   <application>
                     <name>tftp</name>
                   </application>
                 </applications>
               </config>
             </edit-config>
           </rpc>

        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
          <edit-config>
            <target>
              <running/>
            </target>
            <config>
              <acl xmlns="urn:example:acl">
                <acl_rule>
                  <name>allow_access_to_ftp_tftp</name>
                  <matches>
                    <ipv4>
                      <source_address>198.51.100.0/24</source_address>
                      <dest_address>192.0.2.0/24</dest_address>
                    </ipv4>
                    <application>ftp</application>
                    <application>tftp</application>
                    <application>my-app-1</application>
                  </matches>
                  <packet_action>forward</packet_action>
                </acl_rule>
              </acl>
            </config>
          </edit-config>
        </rpc>

        <applications xmlns="urn:example:application">
          <application>
            <name>my-app-1</name>
            <protocol>tcp</protocol>
            <destination-port>2345</destination-port>
          </application>
          <application>
            <name>my-app-2</name>
            <protocol>udp</protocol>
            <destination-port>69</destination-port>
          </application>
          <application>
            <name>ftp</name>
          </application>
          <application>
            <name>tftp</name>
          </application>
        </applications>

        <applications xmlns="urn:example:application"
                      xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                      or:origin="or:intended">
          <application>
            <name>my-app-1</name>
            <protocol>tcp</protocol>
            <destination-port>2345</destination-port>
          </application>
          <application>
            <name>my-app-2</name>
            <protocol>udp</protocol>
            <destination-port>69</destination-port>
          </application>
          <application>
            <name>ftp</name>
            <protocol or:origin="or:system">tcp</protocol>
            <destination-port or:origin="or:system">21</destination-port>
          </application>
          <application>
            <name>tftp</name>
            <protocol or:origin="or:system">udp</protocol>
            <destination-port or:origin="or:system">69</destination-port>
          </application>
        </applications>

       module example-qos-policy {
         yang-version 1.1;
         namespace "urn:example:qos";
         prefix "qos";

         container qos-policies {
            list policy {
              key "name";
              leaf name {
              type string;
            }
              list queue {
                key "queue-id";
                  leaf queue-id {
                    type int32 {
                      range "1..32";
                    }
                  }
                  leaf maximum-burst-size {
                    type int32 {
                      range "0..100";
                    }
                  }
                }
              }
            }
          }

        <qos-policies xmlns="urn:example:qos">
          <name>my-policy</name>
          <queue>
            <queue-id>1</queue-id>
            <maximum-burst-size>50</maximum-burst-size>
          </queue>
          <queue>
            <queue-id>2</queue-id>
            <maximum-burst-size>60</maximum-burst-size>
          </queue>
          <queue>
            <queue-id>3</queue-id>
            <maximum-burst-size>70</maximum-burst-size>
          </queue>
          <queue>
            <queue-id>4</queue-id>
            <maximum-burst-size>80</maximum-burst-size>
          </queue>
        </qos-policies>

        <rpc message-id="101"
             xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
          <edit-config>
            <target>
              <running/>
            </target>
            <config>
              <qos-policies xmlns="urn:example:qos">
                <name>my-policy</name>
                <queue>
                  <queue-id>1</queue-id>
                  <maximum-burst-size>55</maximum-burst-size>
                </queue>
              </qos-policies>
            </config>
          </edit-config>
        </rpc>

        <qos-policies  xmlns="urn:example:qos"
                       xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                       or:origin="or:intended">
          <name>my-policy</name>
          <queue>
            <queue-id>1</queue-id>
            <maximum-burst-size>55</maximum-burst-size>
          </queue>
          <queue or:origin="or:system">
            <queue-id>2</queue-id>
            <maximum-burst-size>60</maximum-burst-size>
          </queue>
           <queue or:origin="or:system">
            <queue-id>3</queue-id>
            <maximum-burst-size>70</maximum-burst-size>
          </queue>
           <queue or:origin="or:system">
            <queue-id>4</queue-id>
            <maximum-burst-size>80</maximum-burst-size>
          </queue>
        </qos-policies>

      <interfaces>
        <interface>
          <name>lo0</name>
          <ip-address>127.0.0.1</ip-address>
          <ip-address>::1</ip-address>
        </interface>
      </interfaces>

     <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                 or:origin="or:system">
       <interface>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
     </interfaces>

     <rpc message-id="101"
          xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <edit-config>
         <target>
           <running/>
         </target>
         <config>
           <interfaces>
             <interface>
               <name>lo0</name>
               <description>loopback</description>
             </interface>
           </interfaces>
         </config>
       </edit-config>
     </rpc>

        <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                    or:origin="or:intended">
          <interface>
            <name>lo0</name>
            <description>loopback</description>
            <ip-address or:origin="or:system">127.0.0.1</ip-address>
            <ip-address or:origin="or:system">::1</ip-address>
          </interface>
        </interfaces>

7.1. Data Model Overview

This YANG module augments NETCONF <edit-config>, <edit-data> and <copy-config> operations with a new parameter "resolve-system" in the input parameters. If the "resolve-system" parameter is present, the server will copy the referenced system configuration into target datastore automatically. A NETCONF client can discover the "resolve-system" parameter support on the server by checking the server's capabilities included in the <hello> message.¶

The following tree diagram [RFC8340] illustrates the "ietf-netconf-resolve-system" module:¶

module: ietf-netconf-resolve-system
  augment /nc:edit-config/nc:input:
    +---w resolve-system?   empty
  augment /nc:copy-config/nc:input:
    +---w resolve-system?   empty
  augment /ncds:edit-data/ncds:input:
    +---w resolve-system?   empty

The following tree diagram [RFC8340] illustrates "edit-config", "copy-config" and "edit-data" rpcs defined in "ietf-netconf" and "ietf-netconf-nmda" respectively, augmented by "ietf-netconf-resolve-system" YANG module:¶

  rpcs:
    +---x edit-config
    |  +---w input
    |     +---w target
    |     |  +---w (config-target)
    |     |     +--:(candidate)
    |     |     |  +---w candidate?   empty {candidate}?
    |     |     +--:(running)
    |     |        +---w running?     empty {writable-running}?
    |     +---w default-operation?   enumeration
    |     +---w test-option?         enumeration {validate}?
    |     +---w error-option?        enumeration
    |     +---w (edit-content)
    |     |   +--:(config)
    |     |   |  +---w config?        <anyxml>
    |     |   +--:(url)
    |     |     +---w url?           inet:uri {url}?
    |     +---w resolve-system?      empty
    +---x copy-config
    |  +---w input
    |     +---w target
    |     |  +---w (config-target)
    |     |     +--:(candidate)
    |     |     |  +---w candidate?   empty {candidate}?
    |     |     +--:(running)
    |     |     |  +---w running?     empty {writable-running}?
    |     |     +--:(startup)
    |     |     |  +---w startup?     empty {startup}?
    |     |     +--:(url)
    |     |        +---w url?         inet:uri {url}?
    |     +---w source
    |     |  +---w (config-source)
    |     |     +--:(candidate)
    |     |     |  +---w candidate?   empty {candidate}?
    |     |     +--:(running)
    |     |     |  +---w running?     empty
    |     |     +--:(startup)
    |     |     |  +---w startup?     empty {startup}?
    |     |     +--:(url)
    |     |     |  +---w url?         inet:uri {url}?
    |     |     +--:(config)
    |     |        +---w config?      <anyxml>
    |     +---w resolve-system?       empty
    +---x edit-data
       +---w input
          +---w datastore            ds:datastore-ref
          +---w default-operation?   enumeration
          +---w (edit-content)
          |  +--:(config)
          |  |  +---w config?        <anydata>
          |  +--:(url)
          |     +---w url?           inet:uri {nc:url}?
          +---w resolve-system?      empty

7.2. Example Usage

This section gives an example of an <edit-config> request to reference system-defined data nodes which are not present in <running> with a "resolve-system" parameter. A retrieval of <running> to show the auto-copied referenced system configurations after the <edit-config> request is also given. The YANG module used is shown as follows, leafrefs refer to an existing name and address of an interface:¶

    module example-interface-management {
      yang-version 1.1;
      namespace "urn:example:interfacemgmt";
      prefix "inm";

      container interfaces {
        list interface {
          key name;
          leaf name {
            type string;
          }
          leaf description {
            type string;
          }
          leaf mtu {
            type uint16;
          }
          leaf ip-address {
            type inet:ip-address;
          }
        }
      }
      container default-address {
        leaf ifname {
          type leafref {
            path "../../interfaces/interface/name";
          }
        }
        leaf address {
          type leafref {
            path "../../interfaces/interface[name = current()/../ifname]"
               + "/ip-address";
          }
        }
      }
    }

Image that the system provides a loopback interface (named "lo0") with a predefined MTU value of "1500" and a predefined IP address of "127.0.0.1", <system> shows the following configuration of loopback interface:¶

<interfaces xmlns="urn:example:interfacemgmt">
  <interface>
    <name>lo0</name>
    <mtu>1500</mtu>
    <ip-address>127.0.0.1</ip-address>
  </interface>
</interfaces>

The client sends an <edit-config> operation to add the configuration of default-address with a "resolve-system" parameter:¶

<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="101">
  <edit-config>
    <target>
      <running/>
    </target>
    <config>
      <default-address xmlns="urn:example:interfacemgmt">
        <if-name>lo0</if-name>
        <address>127.0.0.1</address>
      </default-address>
    </config>
   <resolve-system/>
  </edit-config>
</rpc>

Since the "resolve-system" parameter is provided, the server will resolve any leafrefs to system configurations and copy the referenced system-defined nodes into <running> automatically with the same value (i.e., the name and ip-address data nodes of lo0 interface) in <system> at the end of <edit-config> operation constraint enforcement. After the processing, a positive response is returned:¶

<rpc-reply message-id="101"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <ok/>
</rpc-reply>

Then the client sends a <get-config> operation towards <running>:¶

<rpc message-id="101"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <get-config>
    <source>
      <running/>
    </source>
    <filter type="subtree">
      <interfaces xmlns="urn:example:interfacemgmt"/>
    </filter>
  </get-config>
</rpc>

Given that the referenced interface "name" and "ip-address" of lo0 are configured by the server, the following response is returned:¶

<rpc-reply message-id="101"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
  <data>
    <interfaces xmlns="urn:example:interfacemgmt">
      <interface>
        <name>lo0</name>
        <ip-address>127.0.0.1</ip-address>
      </interface>
    </interfaces>
  </data>
</rpc-reply>

7.3. YANG Module

<CODE BEGINS> file "ietf-netconf-resolve-system@2023-11-05.yang"¶

module ietf-netconf-resolve-system {
  yang-version 1.1;
  namespace
    "urn:ietf:params:xml:ns:yang:ietf-netconf-resolve-system";
  prefix ncrs;

  import ietf-netconf {
    prefix nc;
    reference
      "RFC 6241: Network Configuration Protocol (NETCONF)";
  }
  import ietf-netconf-nmda {
    prefix ncds;
    reference
      "RFC 8526: NETCONF Extensions to Support the Network
       Management Datastore Architecture";
  }

  organization
    "IETF NETMOD (Network Modeling) Working Group";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/netmod/>
     WG List:  <mailto:netmod@ietf.org>

     Author: Qiufang Ma
             <mailto:maqiufang1@huawei.com>
     Author: Qin Wu
             <mailto:bill.wu@huawei.com>
     Author: Chong Feng
             <mailto:fengchonglly@gmail.com>";
  description
    "This module defines an extension to the NETCONF protocol
     that allows the NETCONF client to control whether the server
     is allowed to copy referenced system configuration
     automatically without the client doing so explicitly.

      Copyright (c) 2023 IETF Trust and the persons identified
      as authors of the code. All rights reserved.

      Redistribution and use in source and binary forms, with
      or without modification, is permitted pursuant to, and
      subject to the license terms contained in, the Revised
      BSD License set forth in Section 4.c of the IETF Trust's
      Legal Provisions Relating to IETF Documents
      (https://trustee.ietf.org/license-info).

      This version of this YANG module is part of RFC HHHH
      (https://www.rfc-editor.org/info/rfcHHHH); see the RFC
      itself for full legal notices.

      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 (RFC 2119)
      (RFC 8174) when, and only when, they appear in all
      capitals, as shown here.";

  revision 2023-11-05 {
    description
      "Initial version.";
    reference
      "RFC XXXX: System-defined Configuration";
  }

  grouping resolve-system-grouping {
    description
      "Define the resolve-system parameter grouping.";
    leaf resolve-system {
      type empty;
      description
        "When present, the server is allowed to automatically
         configure referenced system configuration into the
         target configuration datastore.";
    }
  }

  augment "/nc:edit-config/nc:input" {
    description
      "Allows the server to automatically configure
       referenced system configuration to make configuration
       valid.";
    uses resolve-system-grouping;
  }

  augment "/nc:copy-config/nc:input" {
    description
      "Allows the server to automatically configure
       referenced system configuration to make configuration
       valid.";
    uses resolve-system-grouping;
  }

  augment "/ncds:edit-data/ncds:input" {
    description
      "Allows the server to automatically configure
       referenced system configuration to make configuration
       valid.";
    uses resolve-system-grouping;
  }
}

<CODE ENDS>¶

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, <https://www.rfc-editor.org/info/rfc2119>.

[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>.

[RFC6470]

Bierman, A., "Network Configuration Protocol (NETCONF) Base Notifications", RFC 6470, DOI 10.17487/RFC6470, February 2012, <https://www.rfc-editor.org/info/rfc6470>.

[RFC7950]

Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, <https://www.rfc-editor.org/info/rfc7950>.

[RFC8040]

Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, <https://www.rfc-editor.org/info/rfc8040>.

[RFC8341]

Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, <https://www.rfc-editor.org/info/rfc8341>.

[RFC8342]

Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, <https://www.rfc-editor.org/info/rfc8342>.

[RFC8526]

Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "NETCONF Extensions to Support the Network Management Datastore Architecture", RFC 8526, DOI 10.17487/RFC8526, March 2019, <https://www.rfc-editor.org/info/rfc8526>.

[RFC8639]

Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, E., and A. Tripathy, "Subscription to YANG Notifications", RFC 8639, DOI 10.17487/RFC8639, September 2019, <https://www.rfc-editor.org/info/rfc8639>.

[RFC8641]

Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, September 2019, <https://www.rfc-editor.org/info/rfc8641>.

Informative References

[I-D.ma-netmod-immutable-flag]

Ma, Q., Wu, Q., Lengyel, B., and H. Li, "YANG Metadata Annotation for Immutable Flag", Work in Progress, Internet-Draft, draft-ma-netmod-immutable-flag-09, 22 October 2023, <https://datatracker.ietf.org/doc/html/draft-ma-netmod-immutable-flag-09>.

[RFC3688]

Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, <https://www.rfc-editor.org/info/rfc3688>.

[RFC6020]

Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, <https://www.rfc-editor.org/info/rfc6020>.

[RFC6242]

Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, <https://www.rfc-editor.org/info/rfc6242>.

[RFC7317]

Bierman, A. and M. Bjorklund, "A YANG Data Model for System Management", RFC 7317, DOI 10.17487/RFC7317, August 2014, <https://www.rfc-editor.org/info/rfc7317>.

[RFC7952]

Lhotka, L., "Defining and Using Metadata with YANG", RFC 7952, DOI 10.17487/RFC7952, August 2016, <https://www.rfc-editor.org/info/rfc7952>.

[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>.

[RFC8340]

Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, <https://www.rfc-editor.org/info/rfc8340>.

[RFC8407]

Bierman, A., "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", BCP 216, RFC 8407, DOI 10.17487/RFC8407, October 2018, <https://www.rfc-editor.org/info/rfc8407>.

[RFC8446]

Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, <https://www.rfc-editor.org/info/rfc8446>.

[RFC8525]

Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K., and R. Wilton, "YANG Library", RFC 8525, DOI 10.17487/RFC8525, March 2019, <https://www.rfc-editor.org/info/rfc8525>.

[RFC8808]

Wu, Q., Lengyel, B., and Y. Niu, "A YANG Data Model for Factory Default Settings", RFC 8808, DOI 10.17487/RFC8808, August 2020, <https://www.rfc-editor.org/info/rfc8808>.

A.1. Device Powers On

<running>:¶

No configuration for "lo0" appears in <running>;

<system>:¶

     <interfaces>
       <interface>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
     </interfaces>

<intended>:¶

     <interfaces>
       <interface>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
     </interfaces>

<operational>:¶

     <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                 or:origin="or:system">
       <interface>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
     </interfaces>

A.2. Client Commits Configuration

If a client creates an interface "et-0/0/0" but the interface does not physically exist at this point:¶

<running>:¶

     <interfaces>
       <interface>
         <name>et-0/0/0</name>
         <description>Test interface</description>
       </interface>
     </interfaces>

<system>:¶

     <interfaces>
       <interface>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
     </interfaces>

<intended>:¶

     <interfaces>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
       <interface>
         <name>et-0/0/0</name>
         <description>Test interface</description>
       </interface>
       <interface>
     </interfaces>

<operational>:¶

     <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                 or:origin="or:intended">
       <interface or:origin="or:system">
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
     </interfaces>

A.3. Operator Installs Card into a Chassis

<running>:¶

     <interfaces>
       <interface>
         <name>et-0/0/0</name>
         <description>Test interface</description>
       </interface>
     </interfaces>

<system>:¶

     <interfaces>
       <interface>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
       <interface>
         <name>et-0/0/0</name>
         <mtu>1500</mtu>
       </interface>
     </interfaces>

<intended>:¶

     <interfaces>
         <name>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
       <interface>
         <name>et-0/0/0</name>
         <description>Test interface</description>
         <mtu>1500</mtu>
       </interface>
       <interface>
     </interfaces>

<operational>:¶

     <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
                 or:origin="or:intended">
       <interface or:origin="or:system">
         <name or:origin>lo0</name>
         <ip-address>127.0.0.1</ip-address>
         <ip-address>::1</ip-address>
       </interface>
      <interface>
         <name>et-0/0/0</name>
         <description>Test interface</description>
         <mtu or:origin="or:system">1500</mtu>
       </interface>
       <interface>
     </interfaces>