Changing Individual Configuration Elements

You change individual configuration elements within a candidate configuration using the <edit-config> tag element within the <rpc> tag. By default, the NETCONF server merges new configuration data into the existing candidate configuration. However, a client application can also replace, create, or delete individual configuration elements (hierarchy levels or configuration objects). The same basic tag elements are emitted for all operations: <config>, <config-text>, or <url> tag sub-elements within the <edit-config> tag element:

<rpc>
    <edit-config>
        <target>
            <candidate/>
        </target>
    
    <!-- EITHER -->
        <config>
            <configuration>
                <!-- tag elements representing the configuration elements to change -->
            </configuration>
        </config>
    <!-- OR -->
        <config-text>
            <configuration-text>
                <!-- tag elements representing the configuration elements to change -->
            </configuration-text>
        </config-text>
    <!-- OR -->
        <url>
            <!-- location specifier for file containing changes -->
        </url>
    
    </edit-config>
</rpc>
]]>]]>

Using configuration data within the <config> or <config-text> tag elements or the file specified within the <url> tag element, the application defines a configuration element by including the tag elements representing all levels of the configuration hierarchy from the root (represented by the <configuration> tag element) down to the immediate parent level for the element. To represent the element, the application includes its container tag element. The child tag elements included within the container tag element depend on the operation, and are described in the following sections:

For more information about the tag elements that represent configuration statements, see Mapping Configuration Statements to Junos XML Tag Elements. For information about the tag elements for a specific configuration element, see the Junos XML API Configuration Reference.

The NETCONF server indicates that it changed the configuration in the requested way by enclosing the <ok/> tag in the <rpc-reply> tag element:

<rpc-reply xmlns="URN" xmlns:junos="URL">
    <ok/>
</rpc-reply>
]]>]]>

For more information, see the following sections:

Merging Configuration Elements

To merge configuration elements (hierarchy levels or configuration objects) into the candidate configuration, a client application emits the basic tag elements described in Changing Individual Configuration Elements.

To represent each element to merge in (either within the <config> tag element or in the file named by the <url> tag element), the application includes the tag elements representing its parent hierarchy levels and its container tag element, as described in Changing Individual Configuration Elements. Within the container tag, the application includes each of the element’s identifier tag elements (if it has them) and the tag element for each child to add or for which to set a different value. In the following, the identifier tag element is called <name>:

<configuration>
    <!-- opening tags for each parent of the element -->
        <element> 
            <name>identifier</name>
            <!-- - child tag elements to add or change -->
        </element> 
    <!-- closing tags for each parent of the element -->
</configuration>

The NETCONF server merges in the new configuration element according to the rules specified in Setting the Edit Configuration Mode. As described in that section, the application can explicitly specify merge mode by including the <default-operation> tag element with the value merge in the <edit-config> tag element.

The following example shows how to merge information for a new interface called so-3/0/0 into the [edit interfaces] hierarchy level in the candidate configuration:

Replacing Configuration Elements

To replace configuration elements (hierarchy levels or configuration objects) in the candidate configuration, a client application emits the basic tag elements described in Changing Individual Configuration Elements.

To represent the new definition for each configuration element being replaced (either within the <config> tag element or in the file named by the <url> tag element), the application emits the tag elements representing its parent hierarchy levels and its container tag element, as described in Changing Individual Configuration Elements. Within the container tag, the application includes each of the element’s identifier tag elements (if it has them) and all child tag elements (with values, if appropriate) that are being defined for the new version of the element. In the following, the identifier tag element is called <name>. The application includes the operation="replace" attribute in the opening container tag:

<configuration>
    <!-- opening tags for each parent of the element -->
        <container-tag operation="replace"> 
            <name>identifier</name> 
            <!-- other child tag elements -->
        </container-tag> 
    <!-- closing tags for each parent of the element -->
</configuration>

The NETCONF server removes the existing element that has the specified identifiers and inserts the new element.

The application can also replace all objects in the configuration in one operation. For instructions, see Replacing the Candidate Configuration.

The following example shows how to grant new permissions for the object named operator at the [edit system login class] hierarchy level.

Creating New Configuration Elements

To create configuration elements (hierarchy levels or configuration objects) in the candidate configuration only if the elements do not already exist, a client application emits the basic tag elements described in Changing Individual Configuration Elements.

To represent each configuration element being created (either within the <config> tag element or in the file named by the <url> tag element), the application emits the tag elements representing its parent hierarchy levels and its container tag element, as described in Changing Individual Configuration Elements. Within the container tag, the application includes each of the element’s identifier tag elements (if it has them) and all child tag elements (with values, if appropriate) that are being defined for the element. In the following, the identifier tag element is called <name>. The application includes the operation="create" attribute in the opening container tag:

<configuration>
    <!-- opening tags for each parent of the element -->
        <element operation="create"> 
            <name>identifier</name> <!-- if the element has an identifier -->
            <!-- other child tag elements -->
        </element> 
    <!-- closing tags for each parent of the element -->
</configuration>

The NETCONF server adds the new element to the candidate configuration only if there is no existing element with that name (for a hierarchy level) or with the same identifiers (for a configuration object).

The following example shows how to enable OSPF on a device if it is not already configured:

Deleting Configuration Elements

To delete a configuration element (hierarchy level or configuration object) from the candidate configuration, a client application emits the basic tag elements described in Changing Individual Configuration Elements. It also emits the <default-operation> tag element with the value none to change the default mode to no-change.

<rpc>
    <edit-config>
        <target>
            <candidate/>
        </target>
        <default-operation>none</default-operation> 
  
   <!-- EITHER -->
        <config>
            <configuration>
                <!-- tag elements representing the configuration elements to delete -->
            </configuration>
        </config>
   <!-- OR -->
        <url>
            <!-- location specifier for file containing elements to delete -->
        </url>
  
    </edit-config>
</rpc>
]]>]]>

In no-change mode, existing configuration elements remain unchanged unless the corresponding element in the new configuration has the operation="delete" attribute in its opening tag. This mode prevents the NETCONF server from creating parent hierarchy levels for an element that is being deleted. We recommend that the only operation performed in no-change mode be deletion. When merging, replacing, or creating configuration elements, client applications use merge mode.

To represent each configuration element being deleted (either within the <config> tag element or in the file named by the <url> tag element), the application emits the tag elements representing its parent hierarchy levels, as described in Changing Individual Configuration Elements. The tag element in which the operation="delete" attribute is included depends on the element type, as described in the following sections:

Deleting a Hierarchy Level or Container Object

To delete a hierarchy level and all of its children (or a container object that has children but no identifier), a client application includes the operation="delete" attribute in the empty tag that represents the level:

<configuration>
    <!-- opening tags for each parent level -->
        <level-to-delete operation="delete"/> 
    <!-- closing tags for each parent level -->
</configuration>

We recommend that the application set the default mode to no-change by including the <default-operation> tag element with the value none, as described in Deleting Configuration Elements. For more information about hierarchy levels and container objects, see Mapping Configuration Statements to Junos XML Tag Elements.

The following example shows how to remove the [edit protocols ospf] hierarchy level of the candidate configuration:

Deleting a Configuration Object That Has an Identifier

To delete a configuration object that has an identifier, a client application includes the operation="delete" attribute in the container tag element for the object. Inside the container tag element, it includes the identifier tag element only, not any tag elements that represent other characteristics. In the following, the identifier tag element is called <name>:

<configuration>
    <!-- opening tags for each parent of the object -->
        <object operation="delete"> 
            <name>identifier</name> 
        </object> 
    <!-- closing tags for each parent of the object -->
</configuration>

Note: The delete attribute appears in the opening container tag, not in the identifier tag element. The presence of the identifier tag element results in the removal of the specified object, not in the removal of the entire hierarchy level represented by the container tag element.

We recommend that the application set the default mode to no-change by including the <default-operation> tag element with the value none, as described in Deleting Configuration Elements. For more information about identifiers, see Mapping Configuration Statements to Junos XML Tag Elements.

The following example shows how to remove the user object barbara from the [edit system login user] hierarchy level in the candidate configuration:

Deleting a Single-Value or Fixed-Form Option from a Configuration Object

To delete from a configuration object either a fixed-form option or an option that takes just one value, a client application includes the operation="delete" attribute in the tag element for the option. In the following, the identifier tag element for the object is called <name>. (For information about deleting an option that can take multiple values, see Deleting Values from a Multivalue Option of a Configuration Object .)

<configuration>
    <!-- opening tags for each parent of the object -->
        <object> 
            <name>identifier</name> <!-- if object has an identifier -->
            <option1 operation="delete"> 
            <option2 operation="delete"> 
            <!-- tag elements for other options to delete -->
        </object> 
    <!-- closing tags for each parent of the object -->
</configuration>

We recommend that the application set the default mode to no-change by including the <default-operation> tag element with the value none, as described in Deleting Configuration Elements. For more information about options, see Mapping Configuration Statements to Junos XML Tag Elements.

The following example shows how to remove the fixed-form disable option at the [edit forwarding-options sampling] hierarchy level:

Deleting Values from a Multivalue Option of a Configuration Object

As described in Mapping Configuration Statements to Junos XML Tag Elements, some Junos OS configuration objects are leaf statements that have multiple values. In the formatted ASCII CLI representation, the values are enclosed in square brackets following the name of the object:

object[value1 value2 value3 ...];

The Junos XML representation does not use a parent tag for the object, but instead uses a separate instance of the object tag element for each value. In the following, the identifier tag element is called <name>:

<parent-object>
    <name>identifier</name>
    <object>value1</object>
    <object>value2</object>
    <object>value3</object>
</parent-object>

To remove one or more values for such an object, a client application includes the operation="delete" attribute in the opening tag for each value. It does not include tag elements that represent values to be retained. The identifier tag element in the following is called <name>:

<configuration>
    <!-- opening tags for each parent of the parent object -->
        <parent-object> 
            <name>identifier</name> 
            <object operation="delete">value1</object> 
            <object operation="delete">value2</object> 
        </parent-object> 
    <!-- closing tags for each parent of the parent object -->
</configuration>

We recommend that the application set the default mode to no-change by including the <default-operation> tag element with the value none, as described in Deleting Configuration Elements. For more information about leaf statements with multiple values, see Mapping Configuration Statements to Junos XML Tag Elements.

The following example shows how to remove two of the permissions granted to the user-accounts login class: