| NETMOD Working Group | K. Watsen |
| Internet-Draft | Juniper Networks |
| Intended status: Standards Track | A. Bierman |
| Expires: September 7, 2016 | Yumaworks |
| M. Bjorklund | |
| Tail-f Systems | |
| J. Schoenwaelder | |
| Jacobs University Bremen | |
| March 6, 2016 |
Operational State Enhancements for YANG, NETCONF, and RESTCONF
draft-kwatsen-netmod-opstate-02
This document presents enhancements to YANG, NETCONF, and RESTCONF satisfying the requirements set forth in Terminology and Requirements for Enhanced Handling of Operational State.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 7, 2016.
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
This document presents enhancements to YANG [RFC6020], NETCONF [RFC6241], and RESTCONF [draft-ietf-netconf-restconf] satisfying the requirements set forth in Terminology and Requirements for Enhanced Handling of Operational State [draft-ietf-netmod-opstate-reqs-04].
A traceability matrix illustrating how each requirement is satisfied is provided in Appendix A.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
The following terms are defined in [RFC6241]:
The following terms are defined in [draft-ietf-netmod-opstate-reqs-04]:
The following diagram illustrates the conceptual model presented in this document:
+
intended | operational
state | state
|
+----------+ | +---------+
config true | intended | | | applied |
YANG nodes | config | | | config |
+----------+ | +---------+
|
+-------------------------------------------------------+
|
| +---------+
config false | | derived |
YANG nodes | | state |
| +---------+
|
+
Key aspects illustrated in the above diagram include:
To support the opstate requirements, one modification to YANG is necessary. This modification can be introduced as a YANG extension, as described next.
The "related-state" statement designates where related derived state nodes for a config true node can be found. This association is not needed for any descendant config false nodes, as they are already implicitly associated to the parent config true node.
The "related-state" statement takes as an argument a string that is used to specify the path to a config false node holding the associated operational state. The format of the argument is the same as for the leafref's "path" statement, Section 9.9.2 in [RFC6020].
The following example illustrates the related-state statement in use:
module ex-interfaces {
namespace "http://example.com/interfaces";
prefix xif;
import ietf-yang-related-state {
prefix yrs;
}
container interfaces {
list interface {
key name;
yrs:related-state
"/interfaces-state/interface[name=current()/name]";
leaf name { type string }
leaf mtu { type uint16; }
...
}
}
container interfaces-state {
config false;
list interface {
key name;
leaf name { type string; }
...
}
}
}
Note: there is no tree diagram for this YANG module since it does not contain any protocol accessible nodes.
<CODE BEGINS> file "ietf-yang-related-state@2016-02-02.yang"
module ietf-yang-related-state {
namespace urn:ietf:params:xml:ns:yang:ietf-yang-related-state;
prefix yrs;
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <netmod@ietf.org>
WG Chair: Tom Nadeau
<tnadeau@brocade.com>
WG Chair: Kent Watsen
<kwatsen@juniper.net>
WG Chair: Juergen Schoenwaelder
<j.schoenwaelder@jacobs-university.de>";
description
"This YANG module defines the YANG statement 'related-state'.";
revision 2016-02-02 {
description
"Initial revision";
reference
"RFC XXXXX: Terminology and Requirements for Enhanced Handling
of Operational State";
}
extension related-state {
argument path;
description
"The related-state statement is used to identify a node that
contains additional operational state associated for a config
true node.
The format of the argument is the same as for a leafref's
'path' statement.
The related-state statement can be specified in the following
YANG statements:
o leaf
o leaf-list
o container
o list
The related-state statement allows the following YANG
substatements:
o description
Multiple related-state statements can be given in a
specific node.";
}
}
<CODE ENDS>
The following sections describe enhancements to NETCONF provided by the "ietf-netconf-opstate" YANG module.
The "ietf-netconf-opstate" YANG module enables NETCONF clients to access the contents of the applied configuration datastore by passing the value 'applied' for the <source> parameter in the <get-config> and <copy-config> operations.
To retrieve the "/interfaces" subtree from the applied configuration datastore:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get-config>
<source>
<applied xmlns="urn:example:ietf-netconf-applied-config"/>
</source>
<filter type="subtree">
<interfaces xmlns="http://example.com/example-app"/>
</filter>
</get-config>
</rpc>
The "ietf-netconf-opstate" YANG module enables NETCONF clients to control if operations that affect the intended configuration are executed synchronously or asynchronously. The operations that support this ability include:
In order to control how an operation is executed, clients must pass the <sync-behavior> parameter with a value 'sync' or 'async', for synchronous or asynchronous execution respectively.
When synchronous execution is requested (i.e., 'sync' is passed), the <rpc-reply> will not return until the server has fully attempted to update both the intended and applied configurations. When no errors or warnings are generated, the <rpc-reply> will only contain <ok>. When only warnings are generated, the <rpc-reply> will contain <ok> and also the <apply-warnings> flag. If any errors are generated, the <rpc-reply> will contain the standard <rpc-error>.
When asynchronous execution is requested (i.e., 'async' is passed), the <rpc-reply> will return immediately, and contain an additional <sync-id> value that clients can use to correlate a subsequent 'sync-complete' notification (Section 5.5) to determine when the asynchronous request has completed and with what result.
For either synchronous or asynchronous requests, any processing semantics associated with the operation are preserved and extended to also include applying the configuration to internal server components. Notably are the <edit-config> operation's <error-option> parameter and the <commit> operation's atomic update semantic. Any rollback that may occur will restore both the intended and the applied configurations to their previous states.
In order to implement the rollback behavior for <edit-config> or <commit>, it is necessary for the server to maintain a global lock until the processing is complete. That is, either a 'sync' request returns or an 'async' request's 'sync-complete' notification has been sent. Any attempts to read or write either intended or applied configuration will be blocked until the request completes.
To edit the "/interfaces" subtree from the applied configuration datastore:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<sync-behavior>async</sync-behavior>
<target>
<running/>
</target>
<config>
<top xmlns="http://example.com/schema/1.2/config">
<interface>
<name>Ethernet0/0</name>
<mtu>1500</mtu>
</interface>
</top>
</config>
</edit-config>
</rpc>
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
<sync-id>4123</sync-id>
</rpc-reply>
The "ietf-netconf-opstate" YANG module enables NETCONF clients to request a server to return the difference between any two datastores (e.g., running, startup, candidate, and applied).
The <get-diff> RPC takes two 'source' parameters as input and, based on the value of the 'format' paramter, returns either an <edit-config> document (Section 7.2 in [RFC6241]) or a YANG-patch document ([draft-ietf-netconf-yang-patch]), that transforms the first datastore into the second datastore.
This example assumes a YANG module has a data model like:
module example-module {
namespace "http://example.com/ns/example-module";
container system {
leaf hostname {
type string;
}
}
}
With a value in the candidate datastore of 'us-east-dc-fw-1' and value in the running datastore 'us-eass-dc-fw-1' (notice the typo):
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get-diff>
<format>yang-patch</format>
<source1>candidate</source1>
<source2>running</source2>
</rpc>
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<yang-patch xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-patch">
<patch-id>202</patch-id>
<edit>
<edit-id>edit1</edit-id>
<operation>replace</operation>
<target>/example-module:system/hostname</target>
<value>
<hostname xmlns="http://example.com/ns/example-module">
us-east-dc-fw-1
</hostname>
</value>
</edit>
</yang-patch>
</rpc-reply>
The "ietf-netconf-opstate" YANG module enables NETCONF clients to request a server to return operational state data. This RPC is similar to the <get-config> RPC (Section 7.1 in [RFC6241]), but for operational state instead of configuration.
The <get-state> RPC takes two optional parameters. The first parameter is a choice between the values <applied/> and <derived/>, which selects if only these types of nodes should be returned. The second parameter is a filter just like the one used by the <get-config> RPC, including the optional support for XPath expressions.
The following example depicts a request that returns all the derived state (i.e. config false) nodes under the "users" subtree.
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get-state>
<derived/>
<filter type="subtree">
<top xmlns="http://example.com/schema/1.2/config">
<users/>
</top>
</filter>
</get-state>
</rpc>
The <sync-complete> notification notifies clients when an asynchronous request has completed. This notification includes the 'sync-id' value that was returned to the client that originally executed the asynchronous request, as well as any errors or warnings that the request may have been generated while processing the request.
The following example depicts a notification indicating that sync-id "4123" completed with warnings.
<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-07-08T00:02:00Z</eventTime>
<sync-complete
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-opstate">
<sync-id>4123</sync-id>
<rpc-warning/>
</sync-complete>
</notification>
The tree diagram for the "ietf-netconf-opstate" YANG module:
module: ietf-netconf-opstate
augment /nc:get-config/nc:input/nc:source/nc:config-source:
+--rw applied? empty
augment /nc:copy-config/nc:input/nc:source/nc:config-source:
+--rw applied? empty
augment /nc:edit-config/nc:input:
+---- sync-behavior? enumeration
augment /nc:edit-config/nc:output:
+---- (request-type)?
+--:(sync)
| +---- apply-warning? empty
+--:(async)
+---- sync-id? string
augment /nc:copy-config/nc:input:
+---- sync-behavior? enumeration
augment /nc:copy-config/nc:output:
+---- (request-type)?
+--:(sync)
| +---- apply-warning? empty
+--:(async)
+---- sync-id? string
augment /nc:commit/nc:input:
+---- sync-behavior? enumeration
augment /nc:commit/nc:output:
+---- (request-type)?
+--:(sync)
| +---- apply-warning? empty
+--:(async)
+---- sync-id? string
rpcs:
+---x get-diff
| +---w input
| | +---w format? enumeration
| | +---w source1
| | | +---w (config-source)
| | | +--:(candidate)
| | | | +---w candidate? empty {nc:candidate}?
| | | +--:(running)
| | | | +---w running? empty
| | | +--:(startup)
| | | | +---w startup? empty {nc:startup}?
| | | +--:(applied)
| | | +---w applied? empty
| | +---w source2
| | +---w (config-source)
| | +--:(candidate)
| | | +---w candidate? empty {nc:candidate}?
| | +--:(running)
| | | +---w running? empty
| | +--:(startup)
| | | +---w startup? empty {nc:startup}?
| | +--:(applied)
| | +---w applied? empty
| +--ro output
| +--ro (format)?
| +--:(edit-config)
| | +--ro data
| +--:(yang-patch)
| +--ro yang-patch
| +--ro patch-id? string
| +--ro comment? string
| +--ro edit* [edit-id]
| +--ro edit-id string
| +--ro operation enumeration
| +--ro target target-resource-offset
| +--ro point? target-resource-offset
| +--ro where? enumeration
| +--ro value
+---x get-state
+---w input
| +---w (type)?
| | +--:(applied)
| | | +---w applied? empty
| | +--:(derived)
| | +---w derived? empty
| +---w filter
+--ro output
+--ro data
notifications:
+---n sync-complete
+--ro sync-id string
+--ro (response)
+--:(ok)
| +--ro ok? empty
+--:(apply-warning)
| +--ro apply-warning? empty
+--:(rpc-error)
+--ro rpc-error
+--ro error-type enumeration
+--ro error-tag nc:error-tag-type
+--ro error-severity nc:error-severity-type
+--ro error-app-tag? string
+--ro error-path? string
+--ro error-message? string
+--ro error-info
+--ro session-id? uint32
+--ro bad-attribute? string
+--ro bad-element? string
+--ro ok-element? string
+--ro err-element? string
+--ro noop-element? string
+--ro bad-namespace? string
The "ietf-netconf-opstate" YANG module:
<CODE BEGINS> file "ietf-netconf-opstate@2016-02-02.yang"
module ietf-netconf-opstate {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-opstate";
prefix ncos;
import ietf-netconf { // RFC 6241
prefix nc;
}
import ietf-yang-patch { // RFC YYYY
prefix yp;
}
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <netmod@ietf.org>
WG Chair: Tom Nadeau
<tnadeau@brocade.com>
WG Chair: Kent Watsen
<kwatsen@juniper.net>
WG Chair: Juergen Schoenwaelder
<j.schoenwaelder@jacobs-university.de>";
description
"This YANG module does the following:
- enables get-config and copy-config to access applied datastore
- enables edit-config, copy-config, and commit to be executed
either synchronously or asynchronously
- defines 'get-diff' operation to diff datastores
- defines 'get-state' operation to return just state data
- defines 'sync-complete' notification for async requests";
revision 2016-02-02 {
description
"Initial revision";
reference
"RFC XXXXX: Terminology and Requirements for Enhanced Handling
of Operational State";
}
// features
feature sync {
description
"Indicates the server supports the 'sync' value for the
<sync-behavior> parameter in the operations <edit-config>,
<copy-config>, and <commit>.";
}
feature async {
description
"Indicates the server supports the 'async' value for the
<sync-behavior> parameter in the operations <edit-config>,
<copy-config>, and <commit>.";
}
// The following two augmentations enable 'applied' to be passed as a
// <source> argument in the <get-config> and <copy-config> operations.
augment /nc:get-config/nc:input/nc:source/nc:config-source {
description
"Allows 'applied' to be passed in <get-config>";
leaf applied {
type empty;
description
"Indicates that the applied configuration should be returned";
}
}
augment /nc:copy-config/nc:input/nc:source/nc:config-source {
description
"Allows 'applied' to be passed in <copy-config>";
leaf applied {
type empty;
description
"Indicates that the applied configuration should be returned";
}
}
// The following two groupings define input and output parameters that
// are subsequently augmented into the edit-config, copy-config, and
// commit operations.
grouping sync-behavior-input {
description
"This grouping is augmented into the edit-config, copy-config,
and commit operations";
leaf sync-behavior {
type enumeration {
enum "sync" {
if-feature sync;
description
"Request the server to not return a response until both the
intended and applied configurations have been updated.";
}
enum "async" {
if-feature async;
description
"Request the server to not wait for the configuration to be
applied before returning a response. The response will
contain the 'sync-id' leaf. Later, after both the intended
and applied configurations have been updated, the server
will send the 'sync-complete' notification using the same
sync-id value.";
}
}
description
"This value specifies whether the server should process the
request synchronously or asynchronously.";
}
}
grouping sync-behavior-output {
description
"This grouping is augmented into the edit-config, copy-config,
and commit operations. The additional output is only returned
when 'sync-behavior' is specified, and thus does not alter
legacy behavior.";
choice request-type {
description
"This choice makes it explicit which content is possibly
returned for the two 'sync-behavior' values.";
case sync {
leaf apply-warning {
type empty;
description
"Indicates that a warning was generated when applying the
intended configuration to internal server components
(e.g., due to missing hardware) and hence the applied
configuration differs from the intended configuration.";
}
}
case async {
leaf sync-id {
type string;
description
"A server-specified value to identify the asynchronous
request. This value is returned whenever 'async' is
passed in the request. The server must ensure that it
is a unique value over some reasonable amount of time.";
}
}
}
}
// The following six augmentations are used to insert the
// sync-behavior-input and sync-behavior-output nodes into
// the edit-config, copy-config, and commit operations.
augment /nc:edit-config/nc:input {
description
"Allows 'sync-behavior' to be passed in <edit-config>.
When specified, the 'error-option' value is interpreted
as spanning both the updating of the intended and
applied configurations. Notably, when rollback-on-error
is set, both the intended and applied configurations
are restored to their initial states on error.";
uses sync-behavior-input {
when "nc:target/nc:running" {
description "only available when target is 'running'";
}
}
}
augment /nc:edit-config/nc:output {
description
"Allows 'apply-warning' and 'sync-id' to be returned
for <edit-config> operations.";
uses sync-behavior-output;
}
augment /nc:copy-config/nc:input {
description
"Allows 'sync-behavior' to be passed in <copy-config>";
uses sync-behavior-input {
when "nc:target/nc:running" {
description "only available when target is 'running'";
}
}
}
augment /nc:copy-config/nc:output {
description
"Allows 'apply-warning' and 'sync-id' to be returned
for <copy-config> operations.";
uses sync-behavior-output;
}
augment /nc:commit/nc:input {
description
"Allows 'sync-behavior' to be passed in the <commit>
operation. The <commit> operation's atomic behavior
is extended to include both the updating of the
intended and applied configurations.";
uses sync-behavior-input;
}
augment /nc:commit/nc:output {
description
"Allows 'apply-warning' and 'sync-id' to be returned
for <commit> operations.";
uses sync-behavior-output;
}
// The following grouping is used by the get-diff RPC
grouping get-diff-source {
description
"This grouping is used by the 'get-diff' RPC's two
input parameters.";
choice config-source {
mandatory true;
description
"The configuration datastore to use as a source.";
leaf candidate {
if-feature nc:candidate;
type empty;
description
"The candidate configuration is the config source.";
}
leaf running {
type empty;
description
"The running configuration is the config source.";
}
leaf startup {
if-feature nc:startup;
type empty;
description
"The startup configuration is the config source.";
}
leaf applied {
type empty;
description
"The applied configuration is the config source.";
}
}
}
// The following RPC returns the diff between two datastores
rpc get-diff {
description
"Get the difference between two datastores in the form
of a YANG Patch (see RFC YYYY) that transforms 'source1'
into 'source2'. Specifying the same datastore for both
sources always returns an empty diff.";
input {
leaf format {
type enumeration {
enum edit-config { description ""; }
enum yang-patch { description ""; }
}
description "Selects output format";
}
container source1 {
description "the first of two datastores to compare";
uses get-diff-source;
}
container source2 {
description "the second of two datastores to compare";
uses get-diff-source;
}
}
output {
choice format {
case edit-config {
anyxml data {description "";}
}
case yang-patch {
uses yp:yang-patch;
}
description "";
}
}
}
// The following RPC returns just operational state nodes from
// the server.
rpc get-state {
description
"Retrieve operational state from the server. Operational state
is composed of both applied configuration and derived state.
Applied configuration is the subset of config true nodes that
is operational. Derived state is composed of just the config
false nodes.";
reference "RFC 6241, Section 7.7";
input {
choice type {
description
"An optional parameter to select if only applied configuration
or derived state nodes should be returned. If not specified,
then all node types are returned.";
leaf applied {
type empty;
description
"Only return matching applied configuration nodes";
}
leaf derived {
type empty;
description
"Only return matching derived state nodes";
}
}
anyxml filter {
mandatory true;
description
"This parameter specifies the portion of the applied
configuration and derived state data to retrieve.
";
nc:get-filter-element-attributes;
}
}
output {
anyxml data {
description
"Copy of the running datastore subset and/or state
data that matched the filter criteria (if any).
An empty data container indicates that the request
did not produce any results.";
}
}
}
// This following notification is used to alert clients when
// an asynchronous operation request has completed.
notification sync-complete {
description
"Sent by the server when an asynchronous operation
request has completed.";
leaf sync-id {
type string;
mandatory true;
description
"The server-specified unique identifier returned
to the client that requested the asynchronous
operation.";
}
choice response {
mandatory true;
leaf ok {
type empty;
description
"Indicates that the request processed successfully.";
}
leaf apply-warning {
type empty;
description
"Indicates that a warning was generated when applying the
intended configuration to internal server components
(e.g., due to missing hardware) and hence the applied
configuration differs from the intended configuration.";
}
container rpc-error {
leaf error-type {
type enumeration {
enum transport { description "transport"; }
enum rpc { description "rpc"; }
enum protocol { description "protocol"; }
enum application { description "application"; }
}
mandatory true;
description "error-type";
}
leaf error-tag {
type nc:error-tag-type;
mandatory true;
description "error-tag";
}
leaf error-severity {
type nc:error-severity-type;
mandatory true;
description "error-severity";
}
leaf error-app-tag {
type string;
description "error-app-tag";
}
leaf error-path {
type string;
description "error-path";
}
leaf error-message {
type string;
description "error-message";
}
container error-info {
leaf session-id {
type uint32;
description "session-id";
}
leaf bad-attribute {
type string;
description "bad-attribute";
}
leaf bad-element {
type string;
description "bad-element";
}
leaf ok-element {
type string;
description "ok-element";
}
leaf err-element {
type string;
description "err-element";
}
leaf noop-element {
type string;
description "noop-element";
}
leaf bad-namespace {
type string;
description "bad-namespace";
}
description "error-info";
}
description "rpc-error";
}
description "response";
}
}
}
<CODE ENDS>
TBD
TBD
TBD
TBD
| [draft-ietf-netconf-restconf] | Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", Internet-Draft draft-ieft-netconf-restconf-04, 2014. |
| [draft-ietf-netconf-yang-patch] | Bierman, A., Bjorklund, M. and K. Watsen, "YANG Patch Media Type", Internet-Draft draft-ieft-netconf-yang-patch-07, 2014. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC6020] | Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010. |
| [RFC6241] | Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011. |
| [draft-ietf-netmod-opstate-reqs-04] | Watsen, K., Bierman, A., Bjorklund, M. and J. Schoenwaelder, "Terminology and Requirements for Operational State and Model Structure", Internet-Draft draft-ietf-opstate-reqs-04, January 2016. |
This section explains how the requirements specified in [draft-ietf-netmod-opstate-reqs-04] are satisfied by the solution presented in this document.
The following outline mimics the outline in the requirements draft: