| Network Working Group | A. Bierman |
| Internet-Draft | YumaWorks, Inc. |
| Intended status: Standards Track | April 21, 2014 |
| Expires: October 23, 2014 |
NETCONF Efficiency Extensions
draft-bierman-netconf-efficiency-extensions-01
This document describes protocol extensions to improve the efficiency of the Network Configuration Protocol (NETCONF). Protocol capabilities and operations are defined to reduce network usage and transaction complexity.
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There is a need for standard mechanisms to allow NETCONF [RFC6241] application designers to manage NETCONF servers more efficiently when used in network environments with poor connectivity, low bandwidth, and/or high latency. In such conditions, it is desirable to minimize network usage wrt/ the size of protocol messages and the number of protocol operations required to perform a network management function.
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, [RFC2119].
The following terms are defined in [RFC6241]:
The following terms are defined in [RFC6020]:
The following terms are defined in [RESTCONF]:
The following term is defined in [YANG-Patch]:
The following terms are defined:
A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is as follows:
This document attempts to address the following problems with NETCONF protocol procedures.
A client application often needs to retrieve the entire running configuration datastore contents, usually at the start of an editing session. The <rpc‑reply> for this <get‑config> request can be very large (e.g., greater than 250,000 bytes).
If a large number of server connections are lost and then restarted, the quantity of large <rpc‑reply> messages from every server could severely impact network performance.
It would be useful if the <hello> message exchange could be enhanced so an entity-tag value for the current running datastore configuration is included in the server <hello> message. A client can cache the server configuration identifier and omit an initial <get‑config> operation if the value from the server <hello> message matches the cached value.
NETCONF uses a hard-wired message encoding format, namely XML. However, XML tends to be verbose, especially for YANG data models that have long data node identifiers.
There is no reason for the NETCONF message encoding to be hardwired, except for the <hello> message. It would be useful if the NETCONF protocol could support other message encoding formats, such as JSON [JSON]. The <hello> message exchange could be enhanced so the client and server negotiated the message encoding to use for all other messages via an capability exchange included in both <hello> messages.
There are several deficiencies with the NETCONF editing procedures that could be improved.
Multi-operation functions can be required. A single edit can take up to 9 operations. Several operations are required to complete a set of 1 or more edits on a NETCONF server. Each operation uses 1 request and 1 response message. If the candidate datastore is used, then 1 extra operation is required (for the <commit> operation) to activate the edit(s). If the startup datastore is used then 1 extra operation is required (for the <copy‑config> operation) to save the running datastore contents in non-volatile storage. If global locking is used, then 2 extra operations are required for each datastore involved (candidate, running, startup) Since the datastore is locked at the start and unlocked at the end of the entire edit operation, these extra roundtrip times are intervals in which the datastore is being locked, but no datastore access is being done.
Obtaining locks can be expensive. If the server has more than 1 datastore (e.g., candidate + running or running + startup), then multiple lock requests are required, since the <lock> and <unlock> operations on affect 1 datastore at a time. This can cause a long delay or even deadlock if multiple clients are attempting to obtain global locks at once. E.g., client 1 holds a lock on the candidate datastore and is trying to lock the running datastore. At the same time, client 2 holds a lock on the running datastore and is trying to lock the candidate datastore.
Using locks can be brittle. NETCONF clients are intended to be programmatic, so is not likely that locks will be long-lived. Global locks are designed to be short-lived since they block write access to the entire datastore. If lock collisions do occur, they are likely to be cleared very quickly. It would be useful if the client could request how long to wait for locks to clear instead of immediately rejecting an edit request due to an 'in‑use' error.
Edit operations are implied by <config> content. NETCONF uses a default operation and explicit operation attribute within an arbitrarily complete XML subtree to represent a configuration datastore. There are several corner-cases that are not standardized, and very implementation-dependent:
- interpretation of implied operations vs. explicit operations
- order the edits are processed
- handling of nested operation attributes
- handling of duplicate subtrees
- error handling (code points, number of errors, etc.)
- move operations are not explicit and can interpreted as
a request to remove and re-add an entry, not just move
user-ordered data
Edit operations are not protected against multi-client alterations. It is a simple and common practice to retrieve a configuration data resource, changing 1 or more fields, and then update the resource on the server. Since retrieval and edit operations are separate there is always a chance that another client has altered the resource after the <get‑config> operation, but before the <edit‑config> operation, by the first client. Each client could be protected if there was an entity tag associated with each data resource, and an edit request could be rejected if the client attempted to edit a different version of the data resource than expected.
There is no bulk-edit support. If the same edit is needed in multiple instances of a particular data resource, then the data must be repeated for each instance in the <edit‑config> or <copy‑config> request. The request message size could be minimized if there was a way to apply a set of edits to multiple target nodes at once.
There is no confirmed commit support for the running datastore. The ability to backup the running datastore, change it, and revert it unless the client confirms the changes has nothing to do with the candidate datastore. A NETCONF server with limited memory is not likely to support the candidate datastore. This feature is useful for any type of network-wide configuration change, regardless of device size.
NETCONF data retrieval via the <get> and <get‑config> operations can be very inefficient. Some vendors do not even support <get> because it can be such a resource-intensive operation and return an enormous amount of data, especially if all server data is requested at once.
A client cannot retrieve just the non-configuration data. The NETCONF <get> operation allows a client to retrieve data from the server but it returns all data, including configuration datastore nodes. The <get‑config> operation already returns all configuration datastore nodes.
It was originally thought that <get> should return all nodes so the client would not have to correlate configuration and non-configuration data nodes, since they would be mixed together in the reply. Operational experience has shown that the <get> operation without reasonable filters to reduce the returned data can significantly degrade device performance and return enormous XML instance documents in the <rpc‑reply>.
There is no "last‑modified" indication or time filtering. The NETCONF protocol has no standard mechanisms to indicate to a client when a datastore was last modified, or to allow a client to retrieve data only if it has been modified since a specified time. This makes polling applications very inefficient because they will regularly burden the server and the network and themselves with retrieval and processing requests for data that has not changed.
There is no simple list instance discovery mechanism. Sometimes the client application wants to discover what data exists on the server, particularly list entries. There is a need for a simple mechanism to retrieve just the key leaf nodes within a subtree. The NETCONF subtree filtering mechanism does provide a very complex way for the client to request just key leafs for specific list entries. A simpler mechanism is needed which will allow the client to discover the list instances present.
There is no subtree depth control. NETCONF filters allow the client to select specific sub-trees within the conceptual datastore on the server. However, sometimes the client does not really need the entire subtree, which may contain many nested list entries, and be very large. There is sometimes a need to limit the depth of the sub-trees retrieved from the server. A consistent and simple algorithm for determining what data nodes start a new level is needed.
The content filter specification is not extensible. The NETCONF <get> and <get‑config> operations use a hard-coded content filtering mechanism. They use a "type" XML attribute to indicate which of two filter specification types they support, and a "select" XML attribute if the :xpath capability is supported and an XPath [XPATH] expression filter specification is provided.
This design does not allow additional content filter specification types to be supported by an implementation. It does not allow the standard to be easily extended in a modular fashion. In addition, this design does not allow YANG statements to be used to properly describe the protocol operation. The special "get‑filter‑element‑attributes" YANG extension in the ietf-netconf module is not extensible, and it does not really count as proper YANG, since this extension is outside the YANG language definition.
There is no standard metadata or standard way to retrieve metadata. The <with‑defaults> parameter allows 1 specific type of metadata to be returned (i.e., 'report‑all‑tagged' mode). This ad-hoc approach does not scale well and is not extensible. It would be useful if standard and vendor-specific metadata could be identified and retrieved with standard operations.
This document defines some NETCONF protocol operations and new capabilities to reduce network usage and increase functionality at the same time.
All NETCONF efficiency extensions are completely backward-compatible with the current definitions in [RFC6241]. An old client will ignore any new <capability> URIs sent by the server, and will not use the new operations. No existing operations are affected by the new operations, so the extensions will be transparent to an existing NETCONF client.
A new capability called "config‑id" is defined to identify the current running datastore configuration contents with an opaque string. A client can cache this value for each server that supports this capability, along with a copy of its running configuration. When a new session is started, the client can examine the "config‑id" <capability> URI sent by the server. If it is the same as the cached value then the client can use the cached running datastore copy instead of sending an initial <get‑config> operation to the server. The :config-id capability is ignored in the calculation of the :capability-id capability. Refer to Section 2.1 for details on configuration ID advertisement.
A new capability called "encoding" is defined to allow a client to request that an alternate message encoding be used for the NETCONF session. The capability is encoded as a comma-separated list of media types. This list is ordered by the client in the order of highest preference first. The server list is unordered. The first match (done in client priority) is the message encoding used for the rest of session. Refer to Section 2.2 for details on message encoding negotiation.
A new NETCONF protocol operation called <edit2> is defined to address the deficiencies described in Section 1.2.3. This operation allows the entire NETCONF edit procedure to be accomplished with 1 request message. The editing procedures are aligned with the resource model defined in [RESTCONF]. Refer to Section 2.3 for details on <edit2> operation.
The "confirmed‑commit" procedure has been integrated into the <edit2> operation, and can be supported by any server without requiring support for the candidate datastore. It is optional to implement, based on the "confirmed‑edit" capability defined in Section 2.7.
Refer to Section 2.4 for details on the <complete‑commit> operation and Section 2.5 for details on the <revert‑commit> operation.
A new NETCONF protocol operation called <get2> is defined to address the deficiencies described in Section 1.2.4. This operation allows several filter types to be combined to control the data that is returned in the <rpc‑reply> message, and an extensible framework for retrieving metadata associated with datastore or data resources. Refer to Section 2.6 for details on <get2> operation.
This section defines the NETCONF efficiency extensions:
- :config-id Capability - :encoding Capability - <edit2> Operation - <complete-commit> Operation - <revert-commit> Operation - <get2> Operation
The :config-id capability indicates that the server maintains a config ID for the running configuration datastore. This identifier value is selected by the server and treated as an opaque string by the client.
1) Client keeps a cache of server configurations.
2) Server always sends its current config-id value
in the "config-id" <capability> URI.
Client Server X <hello> message
+---------------+ +------------------+
| | | config-id=1234 |
| Server Config | <------- | <capability> |
| Cache | | ... |
+---------------+ +------------------+
3) Client checks cache for server X, config-id=1234.
If found, then OK to use the cached configuration copy.
If not found, then send a <get-config> for the running
configuration to create or update the cached copy.
The server SHOULD save the config ID for the running datastore in non-volatile storage. When the server boots or restarts, the initial configuration ID SHOULD be the same as the last instantiation, if the server does not support the :startup capability (so the non-volatile stored version mirrors the running datastore). If the server does support the :startup capability, then the initial configuration ID SHOULD be the same as the version last saved to non-volatile storage.
The :config-id capability is sent in every server <hello> message. The "id" parameter for the :config-id capability is set to the current config ID for the running datastore on the server:
# Server starts session 3 with an abbreviated <hello>
<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<capabilities>
<capability>
urn:ietf:params:netconf:capability:config-id?id=4284
</capability>
// ... rest of <capability> elements
<capabilities>
<session-id>3</session-id>
</hello>
The :config-id capability is not dependent on any other capabilities.
The :config-id capability is identified by the following capability string:
urn:ietf:params:netconf:capability:config-id:1.0
This capability MUST be advertised in every server <hello> message. The :config-id capability URI MUST contain an "id" argument assigned an opaque string value indicating the current config ID value for the running datastore. For example:
urn:ietf:params:netconf:capability:config-id:1.0?id=6882391
The current config ID value MUST be updated any time a "netconf‑config‑change" event would be generated by the server.
If [RFC6470] is supported, then the "config‑id" leaf defined in Section 2.7 MUST be included in <netconf‑config‑change> event notifications.
If the "with‑metadata" parameter in the <get2> operation specifies the "config‑id" identity, then the server MUST return the current config ID for the running datastore, if the "source" parameter identifies the running datastore. The server MAY maintain config IDs for other datastores as well.
The :config-id capability does not introduce any new protocol operations.
The :config-id capability does not modify any existing protocol operations.
The :config-id capability does not interact with any other capabilities.
The :encoding capability is used by the client to request an alternate message encoding be used instead of XML. The client and server both send a list of media types for the message encodings they support, encoded as a comma-separated list (with no whitespace). The client list is an ordered by preference. The server list is unordered.
+-----------+ +-----------+ +--------------+ | | Client and | | | | | <hello> | server select | <rpc> | | <rpc-reply> | | | protocol base | | | | +-----------+ and encoding +-----------+ +--------------+
Always encoded --- > Start encoding all messages in XML w/base:1.0 in the selected encoding message framing and message framing
Both the client and server will examine the others <hello> message for the "encoding" <capability> URI. If not present, then the default encoding is used, which is XML.
The client list is compared against the server list, checked in the client specified order. If the same media type appears in the server list, then that is the encoding that will be active for the remainder of the session (i.e., starting with the first <rpc> request). All <rpc>, <rpc‑reply>, and <notification> messages MUST be encoded in the negotiated encoding.
Both the client and server MUST support the "application/xml" media type to be backward-compatible with [RFC6241].
If "application/json" encoding is used, then the encoding defined in [I-D.lhotka-netmod-json] MUST be used so namespaces will be properly identified. Any metadata that needs to encoded MUST be encoded according to the procedure defined in [RESTCONF], section 4.4.
The message framing used for the session is unaffected by this capability. The "base1.0" vs. "base1.1" negotiation defined in [RFC6241] determines the message framing that is used for the entire session.
In this example, the client supports the following message encodings, shown in the preferred order.
- Efficient XML Interchange (EXI) - JSON - XML
Some extra whitespace has been added for display purposes only.
# Client requests a new session with alternate encoding
# also requesting an abbreviated hello
<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<capabilities>
<capability>urn:ietf:params:netconf:base:1.0</capability>
<capability>urn:ietf:params:netconf:base:1.1</capability>
<capability>
urn:ietf:params:netconf:capability:encoding:1.0?
types=application/exi,application/json,application/xml
</capability>
</hello>
The server supports the following encodings:
- XML - JSON
Since the most preferred media type in common is "application/json", the JSON encoding used for the remainder of the session.
In this example, the server sends an full <hello> message to the client, truncated for brevity. Extra whitespace has been added for display purposes only.
# Server starts session 4 with JSON encoding
<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<capabilities>
<capability>urn:ietf:params:netconf:base:1.0</capability>
<capability>urn:ietf:params:netconf:base:1.1</capability>
<capability>
urn:ietf:params:netconf:capability:encoding:1.0?
types=application/xml,application/json
</capability>
<capability>
urn:ietf:params:netconf:capability:config-id?id=2130
</capability>
<!-- rest of URIs ... -->
<capabilities>
<session-id>4</session-id>
</hello>
At this point, both the client and server switch to JSON encoding:
# client send a <kill-session> request
{ "ietf-netconf:rpc" : {
"@@message-id" : "201",
"kill-session" : {
"session-id" : 42
}
}
}
# server sends an <ok/> reply
{ "ietf-netconf:rpc-reply" : {
"@@message-id" : "201",
"ok" : [null]
}
}
The :encoding capability is not dependent on any other capabilities.
The :encoding capability is identified by the following capability string:
urn:ietf:params:netconf:capability:encoding:1.0
This capability MUST be advertised in every server <hello> message. The "encoding" capability URI MUST contain a "types" argument containing a comma-separated list of media types that represent the message encoding formats supported by the server.
If the client supports the :encoding capability, it SHOULD include an "encoding" <capability> URI in its <hello> message. The client MAY omit this capability if XML encoding is desired.
For example (line wrapped for display purposes only)
urn:ietf:params:netconf:capability:encoding:1.0? types=application/json,application/xml
The :encoding capability does not introduce any new protocol operations.
The :encoding capability does not modify any existing protocol operations.
The :encoding capability does not interact with any other capabilities.
The <edit2> operation is specified with a YANG "rpc" statement, defined in Section 2.7. This operation allows the entire NETCONF transaction procedure to be performed in a single operation or multiple operations, depending on the input parameters used.
There are no XML attributes used (e.g., "operation" from RFC 6241, "insert", "value" from RFC 6020). Instead, configuration edits are specified with an edit list, using the YANG Patch mechanism defined in [RESTCONF]. This is used instead of a complete XML instance document, e.g. <config> element, to represent an unordered patch list inferred from the diffs. (Although YANG Patch can be used in this mode if client wants to merge or replace the entire configuration datastore).
Positive Response:
This operation returns data containing a "yang‑patch‑status" report (defined in [RESTCONF]) instead of an "ok" element. This report contains an "ok" element that is present if the entire operation succeeded.
Error Response:
The <rpc‑error> element can be returned, e.g., if the message contains invalid parameter syntax. The server MUST report editing errors in the "edit" list within the "yang‑patch‑status" container.
Key: DRI = data-resource-identifier
+---x edit2
+--ro input
| +--ro target
| | +--ro (datastore-target)
| | +--:(candidate)
| | | +--ro candidate? empty
| | +--:(running)
| | +--ro running? empty
| +--ro target-resource? yang:xpath1.0
| +--ro yang-patch
| | +--ro patch-id? string
| | +--ro comment? string
| | +--ro edit [edit-id]
| | +--ro edit-id string
| | +--ro operation enumeration
| | +--ro target data-resource-identifier
| | +--ro point? data-resource-identifier
| | +--ro where? enumeration
| | +--ro value
| +--ro test-only? empty
| +--ro if-match? yang-entity-tag
| +--ro with-locking? empty
| +--ro max-lock-wait? uint32
| +--ro activate-now? empty
| +--ro nvstore-now? empty
| +--ro confirmed? empty
| +--ro confirm-timeout? uint32
| +--ro persist? string
| +--ro persist-id? string
+--ro output
+--ro yang-patch-status
+--ro patch-id? string
+--ro (global-status)?
| +--:(global-errors)
| | +--ro errors
| | +--ro error
| | +--ro error-type enumeration
| | +--ro error-tag string
| | +--ro error-app-tag? string
| | +--ro error-path? DRI
| | +--ro error-message? string
| | +--ro error-info
| |
| +--:(ok)
| +--ro ok? empty
+--ro edit-status
+--ro edit [edit-id]
+--ro edit-id string
+--ro (edit-status-choice)?
+--:(ok)
| +--ro ok? empty
+--:(errors)
+--ro errors
+--ro error
+--ro error-type enumeration
+--ro error-tag string
+--ro error-app-tag? string
+--ro error-path? DRI
+--ro error-message? string
+--ro error-info
In this example, an "all‑in‑one" YANG Patch edit is shown. the following conditions apply:
- The server supports the :candidate and :startup capabilities - The "example-ex" YANG module is supported by the server
The starting state of the "/forests" data structure is described in Appendix B.2. The client is adding an "oak" tree and changing the location of the "birch" tree in the "north" forest.
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<target><candidate/></target>
<target-resource>
/ex:forests/ex:forest[ex:name='north']
</target-resource>
<yang-patch>
<patch-id>north-forest-patch</patch-id>
<comment>
Add an oak tree and change location of the birch tree
</comment>
<edit>
<edit-id>oak</edit-id>
<operation>create</operation>
<target>/ex:trees</target>
<value>
<ex:tree>
<ex:name>oak</ex:name>
<ex:location>hillside</ex:location>
</ex:tree>
</value>
</edit>
<edit>
<edit-id>birch</edit-id>
<operation>merge</operation>
<target>/ex:trees/ex:tree/birch</target>
<value>
<ex:location>west valley</ex:location>
</value>
</edit>
</yang-patch>
<activate-now/>
<nvstore-now/>
</edit2>
</rpc>
The edit succeeds, and the "yang‑patch‑status" container is returned to the client with the <ok/> status for both tree edits:
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<yang-patch-status
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<patch-id>north-forest patch</patch-id>
<ok/>
<edit-status>
<edit>
<edit-id>oak</edit-id>
<ok/>
</edit>
<edit>
<edit-id>birch</edit-id>
<ok/>
</edit>
</edit-status>
</yang-patch-status>
</rpc-reply>
Refer to Appendix B.3 for additional <edit2> protocol operation examples.
A new NETCONF protocol operation called <complete‑commit> is defined to complete a confirmed commit procedure.
There is one optional parameter for this protocol operation:
Positive Response:
The there is a confirmed-commit procedure in progress and it is successfully completed, then an <ok/> element is returned.
Negative Response: An <rpc‑error> response is sent if the request cannot be completed for any reason.
+---x complete-commit
+--ro input
+--ro persist-id? string
In this example, the client has previously started a confirmed commit procedure using the "persist" parameter set to the value "abcdef".
<rpc message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<complete-commit
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<persist-id>abcdef</persist-id>
</complete-commit>
</rpc>
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
A new NETCONF protocol operation called <revert‑commit> is defined to cancel a confirmed commit procedure and revert the running datastore. The <cancel‑commit> operation in [RFC6241] cannot be used because it requires the implementation of the candidate capability.
There is one optional parameter for this protocol operation:
Positive Response:
If there is a confirmed-commit procedure in progress and it is successfully cancelled, and the running datastore successfully reverted, then an <ok/> element is returned.
Negative Response: An <rpc‑error> response is sent if the request cannot be completed for any reason.
+---x revert-commit
+--ro input
+--ro persist-id? string
In this example, the client has previously started a confirmed commit procedure using the "persist" parameter set to the value "abcdef".
<rpc message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<revert-commit
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<persist-id>abcdef</persist-id>
</revert-commit>
</rpc>
<rpc-reply message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
The <get2> operation is specified with a YANG "rpc" statement, defined in Section 2.7. A specific datastore is selected for the source of the retrieval operation. Several different types of filters are provided. Filters are combined in a conceptual "logical‑AND" operation, and are optional to use by the client. Not all filtering mechanisms are mandatory-to-implement for the server.
A depth filter indicates how many subtree levels should be returned in the <rpc‑reply>. This filter is specified with the "depth" input parameter for the <get2> protocol operation. The default "0" indicates that all levels from the requested subtrees should be returned.
A new level is started for each YANG data node within the requested subtree. All top level data nodes are considered to be child nodes (level 1) of a conceptual <config> root.
If no content filters are provided, then level 1 is considered to include all top-level data nodes within the source datastore. Otherwise only the levels in selected subtrees will be considered, and not any additional top-level data nodes.
If the depth requested is equal to "1", then only the requested data nodes (or top-level data nodes) will be returned. This mechanism can be used to detect the existence of containers and list entries within a particular subtree, without returning any of the descendant nodes.
Higher depth values indicates the number of descendant nodes to include in the response. For example, if the depth requested is equal to "2", then only the requested data nodes (or top-level data nodes) and their immediate child data nodes will be returned.
A time filter specifies that data should only be returned if the last-modified timestamp for the target datastore is more recent than the timestamp specified in the "if‑modified‑since" parameter.
If this feature is supported, then the server will maintain a "last‑modified" timestamp for the running datastore. The server MAY support additional nested timestamps for data nodes within the datastore. The server MAY support timestamps for other datastores.
When a request containing the "if‑modified‑since" parameter is received, the server will compare that timestamp to the "last‑modified" timestamp for the source datastore. If it is greater than the specified value then data may be returned (depending on other filters). If the datastore timestamp value is less than or equal to the specified value, then an empty <data> element will be returned in the <rpc‑reply>.
If the "full‑delta" parameter is present, and the server maintains "last‑modified" timestamps for any data nodes within the source datastore, then the same type of comparison will be done for the data node to determine if it should be included in the response. If no "last‑modified" timestamp is maintained for a data node, then the server will use the "last‑modified" timestamp for its nearest ancestor, or for the datastore itself if there are none.
Positive Response: A <data> element is returned which contains the data corresponding to the input parameters specified in the request. The child nodes of the <data> container correspond to top-level YANG data nodes.
If the server supports the "timestamps" YANG feature, and the target is the running datastore, then a "last‑modified" attribute SHOULD be included in the <rpc‑reply> element.
Negative Response: An <rpc‑error> response is sent if the request cannot be completed for any reason.
+---x get2
+--ro input
| +--ro source
| | +--ro (datastore-source)?
| | +--:(candidate)
| | | +--ro candidate? empty
| | +--:(running)
| | | +--ro running? empty
| | +--:(startup)
| | | +--ro startup? empty
| | +--:(url)
| | | +--ro url? inet:uri
| | +--:(operational)
| | +--ro operational? empty
| +--ro (filter-spec)?
| | +--:(subtree-filter)
| | | +--ro subtree-filter
| | +--:(xpath-filter)
| | +--ro xpath-filter? yang:xpath1.0
| +--ro keys-only? empty
| +--ro if-modified-since? yang:date-and-time
| +--ro full-delta? empty
| +--ro depth? uint32
| +--ro with-defaults? with-defaults-mode
| +--ro with-metadata* identityref
| +--ro with-locking? empty
| +--ro max-lock-wait? uint32
+--ro output
+--ro data
In this example, the retrieval the "forests" resource is shown. the following conditions apply:
- The server supports the :candidate and :startup capabilities - The "example-ex" YANG module is supported by the server
The starting state of the "/forests" data structure is described in Appendix B.2. The client is retrieving just the "forests" node, along with the "last‑modified" and "etag" metadata for that node. The "config‑id" for the datastore is also requested. Locking is requested (with a maximum lock wait time of 5 seconds), just to make sure the metadata does not change during the request.
<rpc message-id="104"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ncex="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<subtree-filter>
<forests xmlns="http://example.com/ns/example-ex" />
</subtree-filter>
<depth>1</depth>
<with-metadata>ncex:timestamps</with-metadata>
<with-metadata>ncex:etags</with-metadata>
<with-metadata>ncex:config-id</with-metadata>
<with-locking />
<max-lock-wait>5</max-lock-wait>
</get2>
</rpc>
The server has a "forests" node so this node is returned along with the requested metadata for the node. Note that the XML namespace for the "ncex" metadata is the XSD target namespace defined in Section 2.8, not the YANG namespace URI defined in Section 2.7.
<rpc-reply message-id="104"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:m="urn:ietf:params:xml:ns:netconf:netconf-ex:1.0"
m:last-modified="2012-09-09T02:00:00Z"
m:config-id="3aee5601">
<forests xmlns="http://example.com/ns/example-ex"
m:last-modified="2012-09-09T02:00:00Z"
m:etag="3aee5601" />
</data>
</rpc-reply>
Refer to Appendix B.4 for additional <get2> protocol operation examples.
This module imports the "with‑defaults‑parameters" grouping from [RFC6243].
Several YANG features are imported from [RFC6241]. These correspond to the NETCONF capabilities (e.g., candidate, url, startup, xpath) but defined as YANG features instead of URIs.
Some data types are imported from [RFC6991]:
- date-and-time - uri - xpath1.0
Two YANG groupings are imported from [YANG-Patch]:
- yang-patch - yang-patch-status
One notification is augmented from [RFC6470].
- netconf-configuration-change
RFC Ed.: update the date below with the date of RFC publication and remove this note.
<CODE BEGINS> file "ietf-netconf-ex@2014-04-21.yang"
module ietf-netconf-ex {
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-ex";
prefix ncex;
import ietf-inet-types {
prefix inet;
}
import ietf-netconf {
prefix nc;
}
import ietf-netconf-notifications {
prefix ncn;
}
import ietf-netconf-with-defaults {
prefix ncwd;
}
import ietf-yang-patch {
prefix yp;
}
import ietf-yang-types {
prefix yang;
}
organization
"IETF NETCONF (Network Configuration Protocol) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nsn.com>
WG Chair: Bert Wijnen
<mailto:bertietf@bwijnen.net>
Editor: Andy Bierman
<mailto:andy@yumaworks.com>";
description
"This module contains a collection of YANG definitions for the
efficient operation of a NETCONF server. Protocol operations
are defined to reduce network usage and transaction complexity.
Copyright (c) 2014 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 Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
// RFC Ed.: remove this note
// Note: extracted from
// draft-bierman-netconf-efficiency-extensions-01.txt
// RFC Ed.: update the date below with the date of RFC publication
// and remove this note.
revision "2014-04-21" {
description
"Initial revision. <get2> operation originally published
in draft-bierman-netconf-get2-03.txt";
reference
"RFC XXXX: NETCONF Efficiency Extensions";
}
/* Features */
feature timestamps {
description
"This feature indicates that the server implements
the <get2> operations parameters which require
last modification timestamps to be maintained by
the server.
If this feature is advertised then one global
'last-modified' timestamp for the entire
running configuration datastore MUST be supported.
The server MAY support additional timestamps
for additional datastores and data nodes
within a datastore. The 'with-metadata'
parameter can be used to identify
which data nodes support a 'last-modified'
timestamp.";
}
feature with-defaults {
description
"This feature indicates that the server supports the
'with-defaults' parameter for the <get2> operation.
A NETCONF server SHOULD support this feature.";
reference
"RFC 6243: With-defaults Capability for NETCONF";
}
feature confirmed-edit {
description
"This feature indicates that the server supports the
confirmed commit procedure for the <edit2> protocol
operation.";
}
/* Identities */
identity metadata {
description
"Base for all metadata identifiers used by the
'with-metadata' parameter in the <get2> operation.";
}
identity timestamps {
base metadata;
description
"Describes metadata identifying the last modification
time of the associated datastore or data resource.";
}
identity etags {
base metadata;
description
"Describes metadata identifying the entity tag value
of the associated datastore or data resource.";
}
identity config-id {
base metadata;
description
"Describes metadata identifying the config ID
of the associated datastore or data resource.";
}
/* Typedefs */
typedef yang-entity-tag {
type string;
description
"Contains an opaque string representing a specific instance
of a datastore or data resource. A client can use this
string for equality comparisons between yang-entity-tag
values.
If any configuration data node values changes, or the
relative order of any user-ordered data changes, then
the server MUST change the entity tag value for the
running datastore to a different value. If the server
maintains entity-tag values for configuration data nodes,
then the server MUST change the yang-entity-tag value for
any affected data node.
Only yang-entity-tag values for the same target resource
instance can be compared. Only the 'strong entity tag'
form is required. A server MAY support the 'weak
entity tag' form. If so, then 2 YANG data node resource
instances are considered to be equivalent if they
contain the same value subtrees and all user-ordered
data nodes share the same relative order.";
reference
"RFC 2616, section 3.11.";
}
/* Groupings */
grouping lock-parms {
description
"Common parameters to control datastore locking.";
leaf with-locking {
type empty;
description
"If this parameter is present then the request MUST be
performed with exclusive write access to all datastores
involved in the operation. An 'operation-not-supported'
error-tag value is returned if the target datastore for
the operation does not support locking (e.g., 'url' or
'operational').
If the server cannot provide exclusive write access
for the entire requested operation then an 'in-use'
error-tag value is returned.
If the 'max-lock-wait' parameter is also present then
the server MAY choose to wait up to that amount of
time attempting to obtain exclusive write access,
before returning an error.";
}
leaf max-lock-wait {
when "../with-locking" {
description
"Only relevant if locking is requested.";
}
type uint32 {
range "1 .. 600";
}
units seconds;
description
"If this parameter is present and the 'with-locking'
parameter is also present, then the server MAY wait
up to the specified number of seconds attempting
to obtain exclusive write access for the requested
operation.";
}
}
/* Protocol Operations */
rpc get2 {
description
"Retrieve NETCONF datastore information";
input {
container source {
description
"The datastore (or non-configuration data)
to use for the source for the retrieval operation.";
choice datastore-source {
default running;
description
"The configuration source for the retrieval operation.
The running configuration is the default choice if
this parameter is not present.";
leaf candidate {
if-feature nc:candidate;
type empty;
description
"The candidate configuration datastore is the
retrieval source.";
}
leaf running {
type empty;
description
"The running configuration datastore is the
retrieval source.";
}
leaf startup {
if-feature nc:startup;
type empty;
description
"The startup configuration datastore is the
retrieval source.";
}
leaf url {
if-feature nc:url;
type inet:uri;
description
"The URL-based configuration is the
retrieval source.";
}
leaf operational {
type empty;
description
"The retrieval source is the collection of all
operational (non-configuration) data nodes supported
by the server.
Any ancestor container and/or list and list key nodes
are also returned. No other leafs or leaf-lists will
be included in the reply.
The server MAY return ancestor container, and/or list
and list key nodes that do not contain any
non-configuration nodes. This can occur for several
reasons, e.g., the implementation streams replies
and cannot defer instrumentation or access control
filtering of descendant data nodes.";
}
}
}
choice filter-spec {
description
"The content filter specification for this request";
anyxml subtree-filter {
description
"This parameter identifies the portions of the
target datastore to retrieve.";
reference "RFC 6241, Section 6.";
}
leaf xpath-filter {
if-feature nc:xpath;
type yang:xpath1.0;
description
"This parameter contains an XPath expression
identifying the portions of the target
datastore to retrieve.";
}
}
leaf keys-only {
type empty;
description
"This parameter selects only data nodes which
are key leaf nodes. Parent container and
list nodes are also returned, but no other leafs,
or any leaf-lists will be included in the reply.";
}
leaf if-modified-since {
if-feature timestamps;
type yang:date-and-time;
description
"This parameter selects the target datastore
only if the last-modified timestamp for the
datastore is more recent than the specified time.
If not, then an empty <data> element is returned.
If the target datastore does not maintain a
last-modified timestamp, then this parameter is
ignored.";
}
leaf full-delta {
if-feature timestamps;
type empty;
description
"This parameter selects only data nodes which
have been modified since the specified time.
It is ignored unless the 'if-modified-since'
parameter is also provided and the target datastore
supports a last-modified timestamp.";
}
leaf depth {
type uint32;
default 0;
description
"This parameter selects how many conceptual
sub-tree levels should be returned in the
<rpc-reply>.
If this parameter is equal to '0', then entire
subtrees will be returned.
If this parameter is greater than '0', then
only the specified number of subtree levels will
be returned.";
}
uses ncwd:with-defaults-parameters {
if-feature with-defaults;
description
"This parameter controls the retrieval of
default values.";
reference
"RFC 6243: With-defaults Capability for NETCONF";
}
leaf-list with-metadata {
type identityref {
base metadata;
}
description
"This parameter will cause the server to return
metadata in the <rpc-reply> (e.g. as XML attributes
in XML encoding) associated with the specified
metadata identity. If the server does not support
any specified metadata identifier, then the
operation fails with an 'invalid-value' error.";
}
uses lock-parms {
description
"Exclusive write access can be requested to
ensure that no other sessions modify the
configuration data during the retrieval operation";
}
}
output {
anyxml data {
description
"Copy of the requested datastore subset which
matched the filter criteria (if any).
An empty data container indicates that the
request did not produce any results.";
}
}
}
rpc edit2 {
description
"Edit NETCONF datastore contents.
All operations requested in the yang-patch edit list
are applied, or the target datastore is left unchanged.";
input {
container target {
description
"The datastore to use as the target for this
edit operation.";
choice datastore-target {
mandatory true;
description
"The configuration target for the edit operation.";
leaf candidate {
if-feature nc:candidate;
type empty;
description
"The candidate configuration datastore is the
edit target.";
}
leaf running {
if-feature nc:writable-running;
type empty;
description
"The running configuration datastore is the
edit target.";
}
}
}
leaf target-resource {
if-feature nc:xpath;
type yang:xpath1.0;
description
"This parameter identifies 1 or more data node
instances for which the yang-patch edits
will be applied. The target-resource expression
MUST evaluate to a node-set result.
Each operation in the yang-patch edit list will
be applied to each target-resource instance, as if
it were the document root for the operation.
If multiple instances are represented by the
target-resource value, then the server will apply
all edits to all instances. If any errors occur,
then all edits from this request will be undone
from the target datastore.
The user MUST have appropriate write permissions for
all data accessed by every operation within the edit
list.
If this parameter is not present or not supported
then the target resource is the root node of the
datastore identified by the 'target' parameter.";
}
uses yp:yang-patch {
description
"The yang-patch parameter contains the ordered list
of edits to perform on the target resource(s).
The conceptual document root for the 'target'
parameter is defined to be the value of a data node
represented by the 'target-resource' parameter or the
target datastore conceptual root node if that parameter
is not present.";
}
leaf test-only {
type empty;
description
"If this parameter is present the server will not
actually perform the requested edits. Instead the
edit request will be validated as if it were going
to be applied. Any parameter errors or datastore
validation errors SHOULD be reported in the response.
No attempt to apply, activate the edits or save them
in non-volatile storage will be made if this parameter
is present.";
}
leaf if-match {
type yang-entity-tag;
description
"If this parameter is set, then the entire edit request
will be rejected unless the entity tag for the target
resource matches this value. An rpc-error with
an 'operation-failed' error-tag value MUST returned,
and the edit operation MUST NOT be attempted.
The 'error-app-tag' field SHOULD be set to
'precondition-failed'.
If the target datastore does not maintain a
last-modified timestamp, then this parameter is
ignored.";
}
uses lock-parms {
description
"Exclusive write access can be requested to
ensure that no other sessions modify the
configuration data during the edit operation
and possibly the entire confirmed commit procedure.
If the 'with-locking' parameter is used to start or
extend a confirmed commit procedure, then the
exclusive write access will be maintained until the
confirmed commit procedure terminates somehow.
If the 'with-locking' parameter is used for a
plain edit operation, then exclusive write access
will be maintained until this operation has completed.";
}
leaf activate-now {
type empty;
description
"If present and the edit operation succeeds,
then the server will activate the configuration
changes right away. The server will conceptually
perform a <commit> operation after the edit
operation. The user MUST have execute
permission for the <commit> operation or
the operation fails with an 'access-denied' error.
This parameter has no affect unless the
'datasource-target' choice is the 'candidate' leaf.";
}
leaf nvstore-now {
type empty;
description
"If present and the edit operation succeeds,
and the configuration changes are activated
in the running datastore, then the server
will persist the configuration changes right away
in non-volatile store. The server will conceptually
perform a <copy-config> operation from the running
to the startup datastore. The user MUST have execute
permission for the <copy-config> operation or
the operation fails with an 'access-denied' error.
This parameter has no affect unless the
'startup' capability is supported by the server.";
}
leaf confirmed {
if-feature confirmed-edit;
type empty;
description
"If the requested edit operation succeeds and the
configuration changes are applied to the running
datastore, then a confirmed commit procedure is
requested by the client.
A confirmed commit procedure is an <edit2> operation
that contains this parameter. The <complete-commit>
operation is used to complete the confirmed commit
procedure. The <revert-commit> operation is used
to cancel the confirmed commit procedure and
revert the running datastore back to the contents
before the first confirmed commit operation.
If no <complete-commit> or <revert-commit> operation
is invoked within the timeout interval then
the server will revert the running datastore
back to the contents before the first confirmed
edit operation.
This is the same as the confirmed commit procedure
in RFC 6241 except the candidate capability is
not required.
The server will save the running datastore contents
before the edit operation is activated, if there
is no confirmed edit already in progress.
If the 'with-locking' parameter is present then
the server will maintain exclusive write access
for the specified session until the confirmed
edit procedure is completed somehow.";
reference
"RFC 6241, Section 8.3.4.1";
}
leaf confirm-timeout {
when "../confirmed" {
description
"Only relevant if the <confirmed>parameter is present";
}
if-feature confirmed-edit;
type uint32 {
range "1..max";
}
units "seconds";
default "600"; // 10 minutes
description
"The timeout interval for a confirmed edit procedure.
If exclusive write access was granted for this confirmed
commit procedure, then it is removed if the timeout
occurs and the confirmed commit procedure is terminated.";
reference "RFC 6241, Section 8.3.4.1";
}
leaf persist {
if-feature confirmed-edit;
type string;
description
"This parameter is used to make a confirmed commit
procedure persistent. A persistent confirmed commit
is not aborted if the NETCONF session terminates.
The only way to abort a persistent confirmed commit
is to let the timer expire, or to use the
<revert-commit> operation.
The value of this parameter is a token that MUST be
given in the 'persist-id' parameter of the <edit2>,
<complete-commit>, or <revert-commit> operations in
order to extend, confirm, or cancel the persistent
confirmed commit procedure.
The token SHOULD be a random string.";
reference "RFC 6241, Section 8.3.4.1";
}
leaf persist-id {
if-feature confirmed-edit;
type string;
description
"This parameter is given in order to extend a persistent
confirmed edit. The value must be equal to the value
given in the 'persist' parameter to the <commit>
operation. If it does not match, the operation fails
with an 'invalid-value' error.";
reference "RFC 6241, Section 8.3.4.1";
}
}
output {
uses yp:yang-patch-status;
}
}
rpc complete-commit {
if-feature confirmed-edit;
description
"This operation is used to complete an ongoing confirmed
commit procedure. If exclusive write access was granted
for this confirmed commit procedure, then it is removed
if this operation is successfully completed.
If the confirmed commit is persistent, the parameter
'persist-id' MUST be given, and it MUST match the value of
the 'persist' parameter given in the <edit2> operation.
If not confirmed commit procedure is in progress then
the operation fails with an 'operation-failed' error.";
reference "RFC 6241, Section 8.4.5.1";
input {
leaf persist-id {
type string;
description
"This parameter is given in order to complete a
persistent confirmed commit procedure. The
value MUST be equal to the value given in the
'persist' parameter to the <edit2> operation.
If it does not match, the operation fails with
an 'invalid-value' error.";
}
}
}
rpc revert-commit {
if-feature confirmed-edit;
description
"This operation is used to cancel an ongoing confirmed commit.
If exclusive write access was granted for this confirmed
commit procedure, then it is removed if this operation
is successfully completed.
If the confirmed commit is persistent, the parameter
'persist-id' MUST be given, and it MUST match the value of
the 'persist' parameter. If not confirmed commit
procedure is in progress then the operation fails
with an 'operation-failed' error.";
reference "RFC 6241, Section 8.4.4.1";
input {
leaf persist-id {
type string;
description
"This parameter is given in order to cancel a persistent
confirmed commit and revert the running configuration
datastore to its state before the confirmed commit
procedure started. The value MUST be equal to the value
given in the 'persist' parameter to the <edit2>
operation.
If it does not match, the operation fails with an
'invalid-value' error.";
}
}
}
/* Notifications */
augment /ncn:netconf-config-change {
description
"Add the updated config-id capability value
to a configuration change event.";
leaf config-id {
type string;
description
"Contains the new configuration ID for the
running datastore on the server, representing
the datastore after the configuration changes.";
}
}
}
<CODE ENDS>
The following XML Schema document [XSD] defines the "last‑modified" and "etag" attributes, described within this document. The "last‑modified" attribute is only relevant if the server supports the "timestamps" YANG feature within the "ietf‑netconf‑ex" YANG module.
The "last‑modified" attribute uses the XSD data type "dateTime", in accordance with Section 3.2.7.1 of XML Schema Part 2: Datatypes. This is equivalent to the YANG data type "date‑and‑time".
The "etag" attribute uses the XSD data type "string", in accordance with the "yang‑entity‑tag" YANG typedef defined in Section 2.7.
The "config‑id" attribute uses the XSD data type "string".
<CODE BEGINS> file "netconf‑ex.xsd"
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:netconf:netconf-ex:1.0"
targetNamespace="urn:ietf:params:xml:ns:netconf:netconf-ex:1.0"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
xml:lang="en">
<xs:annotation>
<xs:documentation>
This schema defines the syntax for the "last-modified"
and "etag" attributes described within this document.
</xs:documentation>
</xs:annotation>
<!--
config-id attribute
-->
<xs:attribute name="config-id" type="xs:string">
<xs:annotation>
<xs:documentation>
This attribute indicates the current config ID
for the running configuration datastore,
corresponding to the XML element containing this attribute.
</xs:documentation>
</xs:annotation>
</xs:attribute>
<!--
last-modified attribute
-->
<xs:attribute name="last-modified" type="xs:dateTime">
<xs:annotation>
<xs:documentation>
This attribute indicates the date and time when
a modification was last detected by the server
for the datastore or data node corresponding to
the XML element containing this attribute.
</xs:documentation>
</xs:annotation>
</xs:attribute>
<!--
etag attribute
-->
<xs:attribute name="etag" type="xs:string">
<xs:annotation>
<xs:documentation>
This attribute indicates the entity tag
for the datastore or data node corresponding to
the XML element containing this attribute.
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:schema>
<CODE ENDS>
This document registers a URI in the IETF XML registry [RFC3688]. Following the format in RFC 3688, the following registration is requested:
URI: urn:ietf:params:xml:ns:netconf:netconf-ex:1.0
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
This document registers a URI for the NETCONF XML schema in the IETF XML registry [RFC3688].
// RFC Ed. remove this line and uncomment next line when published //IANA has updated the following URI to reference this document. URI: urn:ietf:params:xml:schema:netconf-ex
This document registers 1 YANG module in the YANG Module Names registry [RFC6020].
name: ietf-netconf-ex namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-ex prefix: ncex // RFC Ed. remove this line and replace XXXX in next line reference: RFC XXXX
This document does not introduce any new security concerns in addition to those specified in [RFC6241], section 9.
-- RFC Ed.: remove this section before publication.
The :capability-id URI exchange was removed because the NETCONF protocol does not allow the server to delay its <hello> message so the client cannot choose the full or abbreviated <hello>.
This makes the :capability-id URI exchange unworkable for several reasons:
The YANG module was updated to align with new RESTCONF and YANG Patch drafts. The "location" leaf has been removed from the "yang‑patch‑status" grouping.
| [I-D.lhotka-netmod-json] | Lhotka, L., "Modeling JSON Text with YANG", Internet-Draft draft-lhotka-netmod-yang-json-02, September 2013. |
| [RESTCONF] | Bierman, A., Bjorklund, M., Watsen, K. and R. Fernando, "RESTCONF Protocol", Internet-Draft draft-ietf-netconf-restconf-00, March 2014. |
| [YANG-Patch] | Bierman, A., Bjorklund, M., Watsen, K. and R. Fernando, "YANG Patch Media Type", Internet-Draft draft-ietf-netconf-yang-patch-00, March 2014. |
| [JSON] | Bray, T., "The JSON Data Interchange Format", Internet-Draft draft-ietf-json-rfc4627bis-03, September 2013. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. |
| [RFC3688] | Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. |
| [RFC6020] | Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. |
| [RFC6241] | Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, June 2011. |
| [RFC6243] | Bierman, A. and B. Lengyel, "With-defaults Capability for NETCONF", RFC 6243, June 2011. |
| [RFC6470] | Bierman, A., "Network Configuration Protocol (NETCONF) Base Notifications ", RFC 6470, February 2012. |
| [RFC6991] | Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013. |
| [XPATH] | Clark, J. and S. DeRose, "XML Path Language (XPath) Version 1.0", World Wide Web Consortium Recommendation REC-xpath-19991116, November 1999. |
| [XSD] | Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes Second Edition", World Wide Web Consortium Recommendation REC-xmlschema-2-20041028, October 2004. |
The resource-identifier-type typedef from yang-patch is a RESTCONF path expression, not an XPath path expression. The error-path parameter also uses RESTCONF path strings. Should either or both of these be XPath instead?
The YANG module of the node is needed for JSON encoding, but there is no YANG schema definition for the <rpc>, <rpc‑reply>, or <notification> elements. The namespace for <rpc> and <rpc‑reply> is "ietf‑netconf", but no module name at all exists for the <notification> element.
Should the "config‑id" (etag for the running datastore root) be returned in every <get2> response or only if requested? (Currently only if requested.)
Should there be a retrieval mode for <get2> where only the nodes in an XPath node-set are returned? NETCONF returns all ancestor nodes and all ancestor or sibling key leafs as well. Sometime the XPath designer knows the context of the result node-set (e.g. path expression for 1 instance of a nested list). The XML scaffolding can add a lot of extra bytes to the <rpc‑reply>.
The "example‑ex" YANG module models a collection of forests. Each forest has a collection of trees. For simplicity, only 1 tree of each type is allowed in a forest.
+--rw forests
+--rw forest [name]
+--rw name string
+--ro tree-count? uint32
+--rw trees
+--rw tree [name]
+--rw name string
+--rw location? string
+--ro height? decimal64
module example-ex {
namespace "http://example.com/ns/example-ex";
prefix ex;
organization "Example, Inc.";
contact "support@example.com";
description "Module used in NETCONF-EX examples.";
revision 2013-10-19 {
description "Initial version";
reference "Example Spec 12.44";
}
container forests {
description "A collection of forests";
list forest {
key name;
description "A single forest";
leaf name {
type string;
description "The forest name";
}
leaf tree-count {
type uint32;
config false;
description "The number of trees in this forest";
}
container trees {
description "A collection of trees";
list tree {
key name;
description "A single tree";
leaf name {
type string;
description "The tree name";
}
leaf location {
type string;
description "The tree location";
}
leaf height {
type decimal64 {
fraction-digits 3;
}
units meters;
config false;
description "The tree height";
}
} // list tree
} // container trees
} // list forest
} // container forests
}
The follow instances are assumed in the following examples.
list forest: "north":
list tree: "birch", "ash", "maple"
list forest: "south":
list tree: "banyan", "palm"
leaf "location": "hillside", "west valley", "southwest pasture",
"east meadow", "greenhouse"
The forests and trees are configured, which represent trees the company has planted and growing over time.
The operational data (tree height) represents the data that the company monitors for each tree over time.
In this example, the server supports the :writable-running and :startup capabilities:
<rpc message-id="105"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<target><running/></target>
<target-resource>
/ex:forests/ex:forest[ex:name='north']
</target-resource>
<yang-patch>
<patch-id>oak-tree-patch</patch-id>
<comment>Create an oak tree</comment>
<edit>
<edit-id>oak</edit-id>
<operation>create</operation>
<target>/ex:trees</target>
<value>
<ex:tree>
<ex:name>oak</ex:name>
<ex:location>hillside</ex:location>
</ex:tree>
</value>
</edit>
</yang-patch>
<with-locking/>
<max-lock-wait>10</max-lock-wait>
<confirmed/>
<confirm-timeout>60</confirm-timeout>
<persist>24ef8829a4</persist>
</edit2>
</rpc>
The edit succeeds, and the "yang‑patch‑status" container is returned to the client with the <location> path expression of the new oak tree resource. The candidate and running datastores remain locked after this operation because a confirmed commit procedure is in progress. The startup datastore was not locked during this operation because the "nvstore‑now" parameter was not provided.
<rpc-reply message-id="105"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<yang-patch-status
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<patch-id>oak-tree-patch</patch-id>
<ok/>
<edit-status>
<edit>
<edit-id>oak</edit-id>
<ok/>
</edit>
</edit-status>
</yang-patch-status>
</rpc-reply>
After configuration verification (e.g., 20 seconds), the client decides to keep these configuration changes and sends a <complete‑commit> request.
<rpc message-id="106"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<complete-commit
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<persist>24ef8829a4</persist>
</complete-commit>
</rpc>
The server completes the confirmed commit procedure and returns an "ok" element to indicate success:
<rpc-reply message-id="106"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
After the operation succeeds, the server releases all locks that were being held to allow exclusive write access for the entire confirmed commit procedure.
The client can now save the activated configuration changes to the startup configuration using the <copy‑config> protocol operation, as described in RFC 6241, section 8.7.5.1.
In this example the client is going to change the location of the "palm" tree is the "south" forest. The entity tag for the tree resource is retrieved with the resource:
<rpc message-id="107"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ncex="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<xpath-filter> <!-- wrapped for display -->
/ex:forests/ex:forest[ex:name='south']/ex:trees/
ex:tree[ex:name='palm']
</xpath-filter>
<depth>1</depth>
<with-metadata>ncex:etags</with-metadata>
</get2>
</rpc>
The server returns a subtree containing data nodes representing the "palm" tree. The "etag" attribute is returned for this resource and its ancestors. Only the "tree" node itself, as requested with the "depth parameter.
<rpc-reply message-id="107"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:lm="urn:ietf:params:xml:ns:netconf:netconf-ex:1.0">
<data xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
lm:last-modified="2012-09-09T02:00:00Z">
<forests xmlns="http://example.com/ns/example-ex"
lm:etag="34ef6892">
<forest lm:etag="ef11eb99">
<name>south</name>
<trees lm:etag="ef11eb99">
<tree lm:etag="3477cc82" />
</trees>
</forest>
</forests>
</data>
</rpc-reply>
The client then edits the list entry (e.g, reassigns tree location) but submits an "if‑match" parameter with the "etag" value it received for the tree resource being edited:
<rpc message-id="108"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<target><candidate/></target>
<target-resource> <!-- wrapped for display -->
/ex:forests/ex:forest[ex:name='south']/ex:trees
/ex:tree[ex:name='palm']
</target-resource>
<yang-patch>
<patch-id>move-palm-tree</patch-id>
<comment>Move the palm tree</comment>
<edit>
<edit-id>palm</edit-id>
<operation>merge</operation>
<target>/</target>
<value>
<ex:location>greenhouse</ex:location>
</value>
</edit>
</yang-patch>
<if-match>3477cc82</if-match>
<with-locking/>
<max-lock-wait>10</max-lock-wait>
<activate-now/>
<nvstore-now/>
</edit2>
</rpc>
In this example the tree resource has been edited by another client since the <get2> reply for this client, so the edit request is not even attempted. Instead an "operation‑failed" is returned:
<rpc-reply message-id="108"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<yang-patch-status
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<patch-id>move-palm-tree</patch-id>
<errors>
<error>
<error-type>protocol</error-type>
<error-tag>operation-failed</error-tag>
<error-app-tag>precondition-failed</error-app-tag>
<error-path> <!-- wrapped for display -->
/ex:forests/ex:forest[ex:name='south']/ex:trees/
ex:tree[ex:name='palm']
</error-path>
<error-message xml:lang="en">
if-match precondition failed
</error-message>
</error>
</errors>
</yang-patch-status>
</rpc-reply>
In this example, the server supports the :candidate and :startup capabilities, so all 3 datastores (including running) are locked for the <edit2> operation. There is a new pine tree for each forest that is being created and sent to the greenhouse.
<rpc message-id="109"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<target><candidate/></target>
<target-resource>
/ex:forests/ex:forest
</target-resource>
<yang-patch>
<patch-id>pine-tree-patch</patch-id>
<comment>Add 2 new pine trees to greenhouse</comment>
<edit>
<edit-id>pine</edit-id>
<operation>create</operation>
<target>/ex:trees</target>
<value>
<ex:tree>
<ex:name>pine</ex:name>
<ex:location>greenhouse</ex:location>
</ex:tree>
</value>
</edit>
</yang-patch>
<with-locking/>
<max-lock-wait>10</max-lock-wait>
<activate-now/>
<nvstore-now/>
</edit2>
</rpc>
The edit succeeds, and the "yang‑patch‑status" container is returned to the client with the status information.
<rpc-reply message-id="109"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<yang-patch-status
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<patch-id>pine-tree-patch</patch-id>
<ok/>
<edit-status>
<edit>
<edit-id>pine</edit-id>
<ok/>
</edit>
</edit-status>
</yang-patch-status>
</rpc-reply>
In this example, the client is checking if it can change the location field in the "palm" tree list entry by using the "test‑only" parameter:
<rpc message-id="110"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<target><candidate/></target>
<target-resource>
/ex:forests/ex:forest[ex:name='south']/ex:trees
</target-resource>
<yang-patch>
<patch-id>palm-tree-move</patch-id>
<comment>Move the palm tree to riverside</comment>
<edit>
<edit-id>palm</edit-id>
<operation>merge</operation>
<target>/ex:tree/palm</target>
<value>
<ex:location>riverside</ex:location>
</value>
</edit>
</yang-patch>
<test-only/>
</edit2>
</rpc>
Since "riverside" is not a supported location, an "invalid‑value" error is returned for the requested edit operation:
<rpc-reply message-id="110"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<yang-patch-status
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ex="http://example.com/ns/example-ex">
<patch-id>palm-tree-move</patch-id>
<edit-status>
<edit>
<edit-id>palm</edit-id>
<errors>
<error>
<error-type>protocol</error-type>
<error-tag>invalid-value</error-tag>
<error-path> <!-- wrapped for display -->
/ex:forests/ex:forest[ex:name='south']/ex:trees/
ex:tree[ex:name='palm']
</error-path>
<error-message xml:lang="en">
value is invalid
</error-message>
</error>
</errors>
</edit>
</edit-status>
</yang-patch-status>
</rpc-reply>
In this example, the running datastore was last modified at "2012‑09‑09T01:43:27Z" because the forest named "north" was modified at this time.
<rpc message-id="111"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ncex="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<subtree-filter>
<forests xmlns="http://example.com/ns/example-ex" />
</subtree-filter>
<if-modified-since>2012-09-09T01:43:27Z</if-modified-since>
<full-delta/>
<with-metadata>ncex:timestamps</with-metadata>
</get2>
</rpc>
<rpc-reply message-id="111"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:lm="urn:ietf:params:xml:ns:netconf:netconf-ex:1.0">
<data xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
lm:last-modified="2012-09-09T02:00:00Z">
<forests xmlns="http://example.com/ns/example-ex">
<forest lm:last-modified="2012-09-09T02:00:00Z">
<name>north</name>
<trees>
<tree>
<name>birch</name>
<location>hillside</location>
</tree>
<tree>
<name>ash</name>
<location>southwest pasture</location>
</tree>
<tree>
<name>maple</name>
<location>east meadow</location>
</tree>
</trees>
</forest>
</forests>
</data>
</rpc-reply>
In this example the client has changed the "if‑modified‑since" timestamp to a time in the future.
<rpc message-id="112"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
xmlns:ncex="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<subtree-filter>
<forests xmlns="http://example.com/ns/example-ex" />
</subtree-filter>
<if-modified-since>2012-09-09T03:43:27Z</if-modified-since>
<with-metadata>ncex:timestamps</with-metadata>
</get2>
</rpc>
<rpc-reply message-id="112"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:lm="urn:ietf:params:xml:ns:netconf:netconf-ex:1.0">
<data xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex"
lm:last-modified="2012-09-09T02:00:00Z" />
</rpc-reply>
This example retrieves only the names from the "forests" subtree in the running datastore.
<rpc message-id="113"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<xpath-filter xmlns:ex=http://example.com/ns/example-ex">
/ex:forests
</xpath-filter>
<keys-only />
</get2>
</rpc>
<rpc-reply message-id="113"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<forests xmlns="http://example.com/ns/example-ex">
<forest>
<name>north</name>
<trees>
<tree>
<name>birch</name>
</tree>
<tree>
<name>ash</name>
</tree>
<tree>
<name>maple</name>
</tree>
</trees>
</forest>
<forest>
<name>south</name>
<trees>
<tree>
<name>banyan</name>
</tree>
<tree>
<name>palm</name>
</tree>
</trees>
</forest>
</forests>
</data>
</rpc-reply>
This example retrieves the "trees" node to determine which forests have any trees.
<rpc message-id="114"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<subtree-filter>
<forests xmlns="http://example.com/ns/example-ex">
<forest>
<trees />
</forest>
</forests>
</subtree-filter>
<depth>1</depth>
</get2>
</rpc>
<rpc-reply message-id="114"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<forests xmlns="http://example.com/ns/example-ex">
<forest>
<name>north</name>
<trees />
</forest>
<forest>
<name>south</name>
<trees />
</forest>
</forests>
</data>
</rpc-reply>
This example retrieves only the name leafs from the "forest" list within the "forests" subtree, in the running datastore.
<rpc message-id="115"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get2 xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<source><operational/></source>
<subtree-filter>
<forests xmlns="http://example.com/ns/example-ex" />
</subtree-filter>
</get2>
</rpc>
<rpc-reply message-id="115"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-ex">
<forests xmlns="http://example.com/ns/example-ex">
<forest>
<name>north</name>
<trees>
<tree>
<name>birch</name>
<height>41.013</height>
</tree>
<tree>
<name>ash</name>
<height>16.523</height>
</tree>
<tree>
<name>maple</name>
<height>51.204</height>
</tree>
</trees>
</forest>
<forest>
<name>south</name>
<trees>
<tree>
<name>banyan</name>
<height>91.433</height>
</tree>
<tree>
<name>palm</name>
<height>83.439</height>
</tree>
</trees>
</forest>
</forests>
</data>
</rpc-reply>