One document matched: draft-ietf-netconf-with-defaults-11.xml
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category="std"
docName="draft-ietf-netconf-with-defaults-11"
ipr="trust200902">
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<front>
<title abbrev="with-defaults">
With-defaults capability for NETCONF
</title>
<author fullname="Andy Bierman"
initials="A.B."
surname="Bierman">
<organization>Brocade</organization>
<address>
<email>andy.bierman@brocade.com</email>
</address>
</author>
<author fullname="Balazs Lengyel" initials="B. L."
surname="Lengyel">
<organization>Ericsson</organization>
<address>
<postal>
<street></street>
<city>Budapest</city>
<region></region>
<code></code>
<country>Hungary</country>
</postal>
<email>balazs.lengyel@ericsson.com</email>
</address>
</author>
<date />
<area>OPS</area>
<workgroup>NETCONF</workgroup>
<keyword>with-defaults</keyword>
<keyword>XML</keyword>
<abstract>
<t>
The NETCONF protocol defines ways to read and edit configuration data
from a NETCONF server. In some cases, part of this data may not be set
by the NETCONF client, but rather a default value known to the server
is used instead. In many situations the
NETCONF client has a priori knowledge about default data, so the NETCONF
server does not need to save it in a NETCONF configuration datastore or
send it to the client in a retrieval operation reply. In other situations the
NETCONF client will need this data from the server.
Not all server implementations treat this default data the same way.
This document defines a capability-based extension to
the NETCONF protocol that allows the NETCONF client to
identify how defaults are processed by the server, and
also defines new mechanisms for client control of
server processing of default data.
</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>
The NETCONF protocol <xref target="RFC4741"/> defines ways to read
configuration and state data from a NETCONF server.
Part of the configuration data may not be set by the NETCONF client,
but rather by a default value from the data model. In many situations the
NETCONF client has a priori knowledge about default data, so the NETCONF
server does not need to send it to the client. A priori knowledge can be
obtained, e.g., a document formally describing the data models supported by
the NETCONF server.
</t>
<t>
It can be important for a client to know exactly how a server
implementation will handle default data. There are subtle
differences in some protocol operations where the defaults
handling behavior of the server will affect the outcome
of the operation.
</t>
<section title="Terminology">
<t>
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 <xref target="RFC2119"/>.
</t>
<t>
<list style="hanging">
<t hangText="Data model schema:">
A document or set of documents describing the
data models supported by the NETCONF server.
</t>
<t hangText="Management Application:">
A computer program running outside the NETCONF server
that configures or supervises the NETCONF server.
A management application can reach the device e.g.
via NETCONF, CLI or SNMP.
</t>
<t hangText="Schema default data:">
Data specified in the data model schema as default,
that is set or used by the device whenever the NETCONF client or
other management application/user does not provide a specific
value for the relevant data node.
Schema default data MAY or may not be stored as part of a
configuration datastore, depending on the basic mode
used by a particular server.
</t>
<t hangText="Default data:">
Conceptual data containing a default value.
Default data is not kept in
a datastore. Not all servers use the
same criteria to decide if a data node is actually
instantiated in a datastore. If a data node is not
present in a datastore, and a schema default definition
is in use by the server instead, then it is considered
to be a default data node.
</t>
<t hangText="Default value:">
A default value is a value for
a data node instance that is conceptually in use
by the server, when the data node instance does not exist.
</t>
<t hangText="Explicitly set data:">
Data that is set to any value by a NETCONF client or
other management application by the way of an explicit
management operation,
including any data model schema default value.
Any value set by the NETCONF server which is not
the schema defined default value
is also considered explicitly set data.
</t>
<t hangText="<with-defaults> retrieval:">
Refers to a protocol operation which includes the
<with-default> parameter to control the handling
of default data.
</t>
<t hangText=":with-defaults:">
The shorthand notation for the with-defaults capability identifier.
</t>
</list>
</t>
<t>
The following terms are defined in <xref target="RFC4741"/>:
<list style="symbols">
<t>client</t>
<t>datastore</t>
<t>operation</t>
<t>server</t>
</list>
</t>
<t>
The following term is defined in <xref target="I-D.ietf-netmod-yang"/>:
<list style="symbols">
<t>data node</t>
</list>
</t>
</section>
<section title="Defaults Handling Behavior">
<t>
The defaults handling behavior used by a server will
impact NETCONF protocol operations in two ways:
<vspace blankLines="1"/>
<list style="numbers">
<t>
Data retrieval: A server is normally allowed to
exclude data nodes which it considers to contain
the default value. The actual nodes omitted depends
on the defaults handling behavior used by the server.
<vspace blankLines="1"/>
</t>
<t>
Create and delete operations: The <edit-config>
'operation' attribute can be used to create
and/or delete specific data nodes. These
operations depend on whether the target node
currently exists or not. The server's
defaults handling behavior will determine whether the
requested node currently exists in the configuration datastore or not.
<vspace blankLines="1"/>
</t>
</list>
</t>
</section>
<section title="Client Controlled Retrieval of Default Data">
<t>
A networking device may have a large number of default values.
Often the default values are not interesting or specifically defined
with a "reasonable" value, so that the management user does not
have to handle them.
For these reasons it is quite common for networking devices to
suppress the output of parameters having the default value.
</t>
<t>
However, there are use-cases when a NETCONF client
will need the default data from the server:
<vspace blankLines="1"/>
<list style="symbols">
<t>
The management application often needs a single, definitive
and complete set of configuration values that determine
how the a networking device works.
</t>
<t>
Documentation about default values can be unreliable or unavailable.
</t>
<t>
Some management applications might not have the capabilities to
correctly parse and interpret formal data models.
</t>
<t>
Human users might want to understand the received
data without consultation of the documentation.
</t>
</list>
</t>
<t>
In all these cases, the NETCONF client will need a mechanism
to retrieve default data from a NETCONF server.
<vspace blankLines="1"/>
This document defines a NETCONF protocol capability to identify
the server defaults handling behavior, an XML attribute to identify
default data, and a YANG module extension to
the NETCONF protocol that allows the NETCONF client to control whether
default data is returned by the server.
</t>
</section>
</section>
<section title="Defaults Handling Basic Modes" anchor="basicHandling">
<t>
Not all server implementations treat default data in the same way.
Instead of forcing a single implementation strategy, this
document allows a server to advertise a particular
style of defaults handling, and the client can adjust
accordingly.
</t>
<t>
NETCONF servers report default data in different ways. This
document specifies three standard defaults handling
basic modes that a server implementor may choose from:
<vspace blankLines="1"/>
<list style="symbols">
<t>report-all</t>
<t>trim</t>
<t>explicit</t>
</list>
</t>
<t>
A server MUST select one of the three basic modes defined
in this section for handling default data.
</t>
<section title="'report-all' Basic Mode">
<t>
A server which uses the 'report-all' basic mode
does not consider any data node to
be default data, even schema default data.
</t>
<section title="'report-all' Basic Mode Retrieval">
<t>
When data is retrieved from a server using the 'report-all' basic
mode, and the <with-defaults> parameter is not present, all data
nodes MUST be reported.
</t>
</section>
<section title="'report-all' <with-defaults> Retrieval">
<t>
The server MUST support the <with-defaults> parameter
with a value equal to 'report-all', as specified in
<xref target="reportAllRetrievalMode"/>.
</t>
</section>
<section title="'report-all' <edit-config> and <copy-config> Behavior">
<t>
The server MUST consider every data node to exist,
even those containing a schema default value.
A valid 'create' operation attribute for a data node that contains its
schema default value MUST fail with a 'data-exists' error-tag.
A valid 'delete' operation attribute for a data node that contains
its schema default value MUST succeed, even though the data node is
immediately replaced by the server with the default value.
</t>
<t>
A server which uses the 'report-all' basic-mode has no
concept of a default node, so the 'report-all-tagged' <with-defaults>
retrieval mode is not relevant. There will never be any tagged nodes,
since there are no nodes which are omitted in a basic-mode retrieval
operation. If the wd:default attribute is present in any
configuration data, the server MUST return an <rpc-error> response
with an 'unknown-attribute' error-tag.
</t>
</section>
</section>
<section title="'trim' Basic Mode">
<t>
A server which uses the 'trim' basic mode MUST consider
any data node set to its schema default value to
be default data.
</t>
<section title="'trim' Basic Mode Retrieval">
<t>
When data is retrieved from a server using the 'trim' basic
mode, and the <with-defaults> parameter is not present,
data nodes MUST NOT be reported if they contain the schema default value.
Non-configuration data nodes containing the
schema default value MUST NOT be reported.
</t>
</section>
<section title="'trim' <with-defaults> Retrieval">
<t>
The server MUST support the <with-defaults> parameter
with a value equal to 'trim', as specified in
<xref target="reportAllRetrievalMode"/>.
</t>
</section>
<section title="'trim' <edit-config> and <copy-config> Behavior">
<t>
The server MUST consider any data node
that does not contain its schema default value to exist.
A valid 'create' operation attribute for a data node that has a schema default
value defined MUST succeed.
A valid 'delete' operation attribute for a missing data node that has a schema default
value MUST fail. The server MUST return an <rpc-error>
response with a 'data-missing' error-tag.
</t>
<t>
If a client sets a data node to its schema default value, using any valid
operation, it MUST succeed, although the data node MUST NOT be saved
in the NETCONF configuration datastore. This has the same effect as removing the
data node and treating it as default data.
</t>
<t>
If the server supports the 'report-all-tagged' value for the
<with-defaults> parameter, then the 'wd:default' attribute MUST be
accepted in configuration input, as described in
<xref target="copyConfigOperation"/> and
<xref target="editConfigOperation"/>.
</t>
</section>
</section>
<section title="'explicit' Basic Mode">
<t>
A server which uses the 'explicit' basic mode MUST consider
any data node that is not explicitly set data to be default data.
</t>
<section title="'explicit' Basic Mode Retrieval">
<t>
If a client sets a data node to its schema default value,
it MUST always be reported.
If the server sets a data node to its schema default value,
it MUST NOT be reported.
Non-configuration data nodes containing the
schema default value MUST be reported.
</t>
</section>
<section title="'explicit' <with-defaults> Retrieval">
<t>
The server MUST support the <with-defaults> parameter
with a value equal to 'explicit', as specified in
<xref target="explicitRetrievalMode"/>.
</t>
</section>
<section title="'explicit' <edit-config> and <copy-config> Behavior">
<t>
The server considers any data node
that is explicitly set data to exist.
A valid 'create' operation attribute for a data node that has been set by
a client to its schema default value MUST fail
with a 'data-exists' error-tag.
A valid 'create' operation attribute for a data node that has been set by
the server to its schema default value MUST succeed.
A valid 'delete' operation attribute for a data node that has been set
by a client to its schema default value MUST succeed.
A valid 'delete' operation attribute for a data node that has been set
by the server to its schema default value MUST
fail with a 'data-missing' error-tag.
</t>
<t>
If the server supports the 'report-all-tagged' retrieval mode in
its :with-defaults capability, then the 'wd:default' attribute MUST be
accepted in configuration input. If all NETCONF <edit-config>
or <copy-config> parameters are valid, then the server
will treat a wd:default="true" tagged data node
as a request to return that node to default data. If this request
is valid within the context of the requested NETCONF operation,
then the data node is removed and returned to its default value.
The data node within the NETCONF message MUST contain a
value in this case, which MUST be equal to the schema default value.
If not, the server MUST return an <rpc-error> response
with a 'invalid-value' error-tag.
</t>
</section>
</section>
</section>
<section title="Retrieval of Default Data" anchor="retrievalHandling">
<t>
This document defines a new parameter, called <with-defaults>,
which can be added to specific NETCONF operation request
messages to control how retrieval of default data is
treated by the server.
</t>
<t>
A server which implements this specification MUST
accept the <with-defaults> parameter
containing the enumeration for any of the defaults
handling modes it supports.
The <with-defaults> parameter contains one of the four
enumerations defined in this section.
</t>
<section title="'report-all' Retrieval Mode" anchor="reportAllRetrievalMode">
<t>
When data is retrieved with a <with-defaults> parameter equal to
'report-all', all data nodes MUST be reported, including any data
nodes considered to be default data by the server.
</t>
</section>
<section title="'trim' Retrieval Mode" anchor="trimRetrievalMode">
<t>
When data is retrieved with a <with-defaults> parameter equal to
'trim', data nodes MUST NOT be reported if they contain the schema default value.
Non-configuration data nodes containing the
schema default value MUST NOT be reported.
</t>
</section>
<section title="'explicit' Retrieval Mode" anchor="explicitRetrievalMode">
<t>
When data is retrieved with a <with-defaults> parameter equal to
'explicit', a data node which was set by a client to its schema default value
MUST be reported. A conceptual data node which would be set by the
server to the schema default value MUST NOT be reported.
Non-configuration data nodes containing the
schema default value MUST be reported.
</t>
</section>
<section title="'report-all-tagged' Retrieval Mode"
anchor="reportAllTaggedRetrievalMode">
<t>
In addition to the basic modes, a special variant
of the 'report-all' basic mode is available
called 'report-all-tagged'. This mode MUST be supported
on a server if the 'also-supported'
parameter in the :with-defaults capability
contains the 'report-all-tagged' option.
Refer to <xref target="WDCAP"/> for encoding details
for this capability.
</t>
<t>
In this mode the server returns all data nodes,
just like the 'report-all' mode, except
a data node that is considered by the server to contain
default data will include an XML attribute to indicate
this condition. This is useful
for an application to determine which nodes are considered
to contain default data by the server, within a single
retrieval operation.
</t>
<t>
A server which supports 'report-all-tagged' MUST also
accept the 'wd:default' XML attribute within configuration
input to the <edit-config> or <copy-config> operations.
Refer to <xref target="ATTRXSD" /> for XML encoding details
of the 'wd:default' XML attribute.
</t>
</section>
</section>
<section anchor="WDCAP" title="With-defaults Capability">
<section title="Overview">
<t>
The :with-defaults capability indicates which
defaults handling basic mode is supported by the server. It may
also indicate support for additional defaults retrieval modes.
These retrieval modes allow a NETCONF client to control whether
default data is returned by the server.
The capability affects both configuration and state data
(while acknowledging that the usage of default
values for state data is less prevalent).
Sending of default data is controlled for each individual
operation separately.
</t>
<t>
A NETCONF server implementing the :with-defaults capability:
<vspace blankLines="1"/>
<list style="symbols">
<t>
MUST indicate its basic mode behavior by including the
'basic-mode' parameter in the capability URI, as defined
in <xref target="capabilityIdChapter"/>.
</t>
<t>
MUST support the YANG module defined in
<xref target="YANGMOD"/>.
</t>
<t>
SHOULD support the 'report-all' or 'report-all-tagged'
defaults handling mode.
</t>
<t>
MAY support additional defaults handling modes.
</t>
</list>
</t>
</section>
<section title="Dependencies">
<t>None</t>
</section>
<section title="Conformance">
<t>Every NETCONF server SHOULD implement this capability.</t>
</section>
<section title="Capability Identifier" anchor="capabilityIdChapter">
<t>
urn:ietf:params:netconf:capability:with-defaults:1.0
<vspace blankLines="1"/>
The identifier MUST have a parameter: "basic-mode". This indicates how
the server will treat default data, as defined in
<xref target="basicHandling"/>.
The allowed values of this parameter are
'report-all', 'trim', and
'explicit', as defined in <xref target="basicHandling"/>.
</t>
<t>
The identifier MAY have another parameter: "also-supported".
This parameter
indicates which additional default handling modes the server supports.
The value of the parameter is a comma separated list of one or more modes
that are supported beside the mode indicated in the 'basic-mode' parameter.
Possible modes are 'report-all', 'report-all-tagged', 'trim', and
'explicit', as defined in <xref target="retrievalHandling"/>.
</t>
<t>
Note that this protocol capability URI is separate from the
YANG module capability URI
for the YANG module in <xref target="YANGMOD" />. A server which
implements this module MUST also advertise a YANG module
capability URI according to the rules specified in
<xref target="I-D.ietf-netmod-yang"/>.
</t>
<t>Examples:
<vspace blankLines="1"/>
urn:ietf:params:netconf:capability:with-defaults:1.0?basic-mode=explicit
<vspace blankLines="1"/>
urn:ietf:params:netconf:capability:with-defaults:1.0?basic-mode=explicit&also-supported=report-all,report-all-tagged
</t>
</section>
<section title="New Operations">
<t>None</t>
</section>
<section title="Modifications to Existing Operations">
<section anchor="copyConfigOperation"
title="<get>, <get-config>, and <copy-config> Operations">
<t>
A new <with-defaults> XML
element is added to the input for the
<get>, <get-config> and <copy-config> operations.
If the <with-defaults> element is present, it controls the
reporting of default data. The server MUST return
default data in the NETCONF <rpc-reply> messages
according to the value of this element, if the server
supports the specified retrieval mode.
</t>
<t>
This parameter only controls these specified
retrieval operations, and does not impact any other
operations or the non-volatile storage of
configuration data.
</t>
<t>
The <with-defaults> element is defined in the XML namespace for the
ietf-netconf-with-defaults.yang module in <xref target="YANGMOD" />,
not the XML namespace for the <get>, <get-config> and
<copy-config> operations.
</t>
<t>
Allowed values of the with-defaults element are taken from
the 'with-defaults-type' typedef in <xref target="YANGMOD"/>.
The allowed values for a particular server are restricted to the
values that the server indicates it supports within the :with-defaults
capability, in the 'basic-mode' and 'also-supported' parameters.
</t>
<t>
If an unsupported value is used, the NETCONF server MUST
return an <rpc-error> response with an 'invalid-value' error-tag.
</t>
<t>
If the <with-defaults> element is not present,
the server MUST follow its basic mode behavior as indicated
by the :with-defaults capability identifier's 'basic-mode' parameter,
defined in <xref target="capabilityIdChapter"/>.
</t>
<t>
The <get> and <get-config> operations support a separate
filtering mechanism, using the <filter> parameter. The
defaults filtering is conceptually done before the <filter> parameter
is processed. For example, if the <with-defaults>
parameter is equal to 'report-all', then the <filter> parameter
is conceptually applied to all data nodes and all default data.
</t>
<t>
The <copy-config> operation is only affected by the
<with-defaults> parameter if the target
of the operation is specified with the <url> parameter.
If the target is a NETCONF configuration datastore (i.e., running, candidate or startup), the
<with-defaults> parameter has no effect. The server MUST use its basic mode
when copying data to a NETCONF configuration datastore.
If the <with-defaults> parameter is present in this case,
it MUST be silently ignored by the server.
</t>
<t>
If the server supports the 'report-all-tagged' mode,
then the 'wd:default' attribute defined in
<xref target="ATTRXSD" /> also impacts the <copy-config>
operation. If the wd:default attribute is present
and set to 'true', then the server MUST treat the
new data node as a request to return that node to its
default value (i.e., remove it from the configuration datastore).
The data node within the NETCONF message MUST contain a
value in this case, which MUST be equal to the schema default value.
If not, the server MUST return an <rpc-error> response
with a 'invalid-value' error-tag.
</t>
</section>
<section anchor="editConfigOperation" title="<edit-config> Operation">
<t>
The <edit-config> operation has several editing modes.
The 'create' and 'delete' editing operations are affected
by the defaults handling basic mode. The other enumeration values
for the NETCONF operation attribute are not affected.
</t>
<t>
If the operation attribute contains the value 'create',
and the data node already exists in the target configuration datastore,
then the server MUST return an <rpc-error> response
with a 'invalid-value' error-tag.
</t>
<t>
If the client sets a data node to its schema default value,
the server MUST accept the request if it is valid.
The server MUST keep or discard the new value based on
its defaults handling basic mode. For the 'trim' basic mode,
all schema default values are discarded, otherwise a
client-provided schema default value is saved in
a NETCONF configuration datastore.
</t>
<t>
If the server supports the 'report-all-tagged' mode,
then the 'wd:default' attribute defined in
<xref target="ATTRXSD" /> also impacts the <edit-config>
operation. If the wd:default attribute is present
and set to 'true', then the server MUST treat the
new data node as a request to return that node to its
default value (i.e., remove it from the configuration datastore).
The data node within the NETCONF message MUST contain a
value in this case, which MUST be equal to the schema default value.
If not, the server MUST return an <rpc-error> response
with a 'invalid-value' error-tag.
</t>
<t>
If the wd:default attribute is present, then the effective
operation for the target data node MUST be
'create', 'merge' or 'replace'. If not, then
the server MUST return an <rpc-error> response
with an 'invalid-value' error-tag. For example,
if 'create' is the
effective operation, then the create request must
be valid on its own (e.g., current data node MUST NOT exist).
The procedure for determining the effective operation
is defined in <xref target="I-D.ietf-netconf-4741bis"/>.
It is derived from the 'default-operation' parameter and/or
any operation attributes that
are present in the data node or any of its ancestor nodes,
within the <edit-config> request.
</t>
</section>
<section title="Other Operations">
<t>
Other operations that return configuration data SHOULD
also handle default data according to the rules set in
this document, and explicitly state this in their documentation.
If this is not specified in the document defining the
respective operation, the default handling rules described
herein do not affect these operations.
</t>
</section>
</section>
<section title="Interactions with Other Capabilities">
<t>None</t>
</section>
</section>
<section anchor="YANGMOD"
title="YANG Module for the <with-defaults> Parameter">
<t>
The following YANG module defines the addition of the with-defaults element
to the <get>, <get-config>, and <copy-config> operations.
The YANG language is defined in <xref target="I-D.ietf-netmod-yang"/>.
The above operations are defined in YANG in
<xref target="I-D.ietf-netconf-4741bis"/>.
Every NETCONF server which supports the :with-defaults capability
MUST implement this YANG module.
</t>
<t>
<figure>
<artwork><![CDATA[
<CODE BEGINS> file="ietf-netconf-with-defaults@2010-06-09.yang"
module ietf-netconf-with-defaults {
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults";
prefix ncwd;
import ietf-netconf { prefix nc; }
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: Bert Wijnen
<mailto:bertietf@bwijnen.net>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nsn.com>
Editor: Andy Bierman
<mailto:andy.bierman@brocade.com>
Editor: Balazs Lengyel
<mailto:balazs.lengyel@ericsson.com>";
description
"This module defines an extension to the NETCONF protocol
that allows the NETCONF client to control how default
values are handled by the server in particular NETCONF operations.
Copyright (c) 2010 IETF Trust and the persons identified as
the document authors. 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-ietf-netmod-with-defaults-10.txt
revision 2010-06-09 {
description
"Initial version.";
reference
"RFC XXXX: With-defaults capability for NETCONF";
}
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
typedef with-defaults-mode {
description
"Possible modes to report default data.";
reference
"RFC XXXX; section 3.";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
type enumeration {
enum report-all {
description
"All default data is reported.";
reference
"RFC XXXX; section 3.1";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
}
enum report-all-tagged {
description
"All default data is reported.
Any nodes considered to be default data
will contain a 'wd:default' XML attribute,
set to 'true'.";
reference
"RFC XXXX; section 3.4";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
}
enum trim {
description
"Values are not reported if they contain the default.";
reference
"RFC XXXX; section 3.2";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
}
enum explicit {
description
"Report values that contain the definition of
explicitly set data.";
reference
"RFC XXXX; section 3.3";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
}
}
}
grouping with-defaults-parameters {
description
"Contains the <with-defaults> parameter for control
of defaults in NETCONF retrieval operations.";
leaf with-defaults {
description
"The explicit defaults processing mode requested.";
reference
"RFC XXXX; section 4.6.1";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
type with-defaults-mode;
}
}
// extending the get-config operation
augment /nc:get-config/nc:input {
description
"Adds the <with-defaults> parameter to the
input of the NETCONF <get-config> operation.";
reference
"RFC XXXX; section 4.6.1";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
uses with-defaults-parameters;
}
// extending the get operation
augment /nc:get/nc:input {
description
"Adds the <with-defaults> parameter to
the input of the NETCONF <get> operation.";
reference
"RFC XXXX; section 4.6.1";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
uses with-defaults-parameters;
}
// extending the copy-config operation
augment /nc:copy-config/nc:input {
description
"Adds the <with-defaults> parameter to
the input of the NETCONF <copy-config> operation.";
reference
"RFC XXXX; section 4.6.1";
// RFC Ed.: replace XXXX with actual
// RFC number and remove this note
uses with-defaults-parameters;
}
}
<CODE ENDS>
]]></artwork>
</figure>
<vspace blankLines="1"/>
</t>
</section>
<section anchor="ATTRXSD"
title="XSD for the 'wd:default' Attribute">
<t>
The following XML Schema document defines the 'default' attribute,
described within this document. This XSD is only relevant if
the server supports the 'report-all-tagged' defaults retrieval mode.
</t>
<t>
<figure>
<artwork><![CDATA[
<CODE BEGINS> file="defaults.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:default:1.0"
targetNamespace="urn:ietf:params:xml:ns:netconf:default:1.0"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
xml:lang="en">
<xs:annotation>
<xs:documentation>
This schema defines the syntax for the 'default' attribute
described within this document.
</xs:documentation>
</xs:annotation>
<!--
default attribute
-->
<xs:attribute name="default" type="xs:boolean" default="false">
<xs:annotation>
<xs:documentation>
This attribute indicates whether the data node represented
by the XML element containing this attribute is considered
by the server to be default data. If set to 'true' then
the data node is default data. If 'false', then the
data node is not default data.
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:schema>
<CODE ENDS>
]]></artwork>
</figure>
</t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>
This document registers the following capability identifier
URN in the 'Network Configuration Protocol
Capability URNs registry':
<vspace blankLines="1"/>
<list>
<t>
urn:ietf:params:netconf:capability:with-defaults:1.0
</t>
</list>
<vspace blankLines="1"/>
Note that the capability URN is compliant to
<xref target="RFC4741"></xref> section 10.3.
</t>
<t>
This document registers two XML namespace URNs
in the 'IETF XML registry', following the format
defined in <xref target="RFC3688"/>.
<vspace blankLines="1"/>
<list>
<t>URI: urn:ietf:params:xml:ns:netconf:default:1.0</t>
<t>URI: urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults</t>
</list>
<vspace blankLines="1"/>
Registrant Contact: The NETCONF WG of the IETF.
<vspace blankLines="1"/>
XML: N/A, the requested URIs are XML namespaces.
</t>
<t>
This document registers one module name
in the 'YANG Module Names' registry,
defined in <xref target="I-D.ietf-netmod-yang" /> .
<vspace blankLines="1"/>
<list>
<t>name: ietf-netconf-with-defaults</t>
<t>prefix: ncwd</t>
<t>namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults</t>
<t>RFC: XXXX // RFC Ed.: replace XXXX and remove this comment</t>
</list>
</t>
</section>
<section anchor="Security" title="Security Considerations">
<t>
This document defines an extension to existing
NETCONF protocol operations. It does not introduce
any new or increased security risks into the management system.
</t>
<t>
The 'with-defaults' capability gives clients control over the
retrieval of default data from a NETCONF datastore. The
security consideration of <xref target="I-D.ietf-netconf-4741bis"/> apply
to this document as well.
</t>
</section>
<section title="Acknowledgements">
<t>
Thanks to Martin Bjorklund, Sharon Chisholm, Phil Shafer,
Juergen Schoenwaelder, Washam Fan and
many other members of the NETCONF WG for providing important
input to this document.
</t>
</section>
</middle>
<back>
<references title="Normative References">
&rfc2119;
&rfc3688;
&rfc4741;
&netconfspec;
&yangspec;
&xmlspec;
</references>
<section title="Usage Examples">
<section anchor="EXAMPLEMOD" title="Example YANG Module">
<t>
The following YANG module defines an example interfaces table
to demonstrate how the <with-defaults> parameter behaves
for a specific data model.
</t>
<t>
Note that this is not a real module, and implementation
of this module is not required for conformance to the
:with-defaults capability, defined in <xref target="WDCAP" />.
This module is not to be registered with IANA, and is not
considered to be a code component. It is
intentionally very terse, and includes few descriptive statements.
</t>
<t>
<figure>
<artwork><![CDATA[
module example {
namespace "http://example.com/ns/interfaces";
prefix exam;
typedef status-type {
description "Interface status";
type enumeration {
enum ok;
enum 'waking up';
enum 'not feeling so good';
enum 'better check it out';
enum 'better call for help';
}
default ok;
}
container interfaces {
description "Example interfaces group";
list interface {
description "Example interface entry";
key name;
leaf name {
description
"The administrative name of the interface.
This is an identifier which is only unique
within the scope of this list, and only
within a specific server.";
type string {
length "1 .. max";
}
}
leaf mtu {
description
"The maximum transmission unit (MTU) value assigned to
this interface.";
type uint32;
default 1500;
}
leaf status {
description
"The current status of this interface.";
type status-type;
config false;
}
}
}
}
]]>
</artwork>
</figure>
<vspace blankLines="1"/>
</t>
</section>
<section anchor="DATASET" title="Example Data Set">
<t>
The following data element shows the conceptual contents of the
example server for the protocol operation examples in the
next section. This includes all the configuration data nodes,
non-configuration data nodes, and default leafs.
</t>
<t>
<figure>
<artwork>
<![CDATA[
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<interfaces xmlns="http://example.com/ns/interfaces">
<interface>
<name>eth0</name>
<mtu>8192</mtu>
<status>up</status>
</interface>
<interface>
<name>eth1</name>
<mtu>1500</mtu>
<status>up</status>
</interface>
<interface>
<name>eth2</name>
<mtu>9000</mtu>
<status>not feeling so good</status>
</interface>
<interface>
<name>eth3</name>
<mtu>1500</mtu>
<status>waking up</status>
</interface>
</interfaces>
</data>
]]>
</artwork>
</figure>
</t>
<t>
In this example, the 'mtu' field for each interface entry
is set in the following manner:
</t>
<texttable>
<ttcol align="left" width="20%">name</ttcol>
<ttcol align="left" width="20%">set by</ttcol>
<ttcol align="left" width="20%">mtu</ttcol>
<c>eth0</c>
<c>client</c>
<c>8192</c>
<c>eth1</c>
<c>server</c>
<c>1500</c>
<c>eth2</c>
<c>client</c>
<c>9000</c>
<c>eth3</c>
<c>client</c>
<c>1500</c>
</texttable>
</section>
<section title="Protocol Operation Examples">
<t>
The following examples shows some <get> operations
using the 'with-defaults' element.
The data model used for these examples is defined in
<xref target="EXAMPLEMOD" />.
</t>
<t>
The client is retrieving all the data nodes within the 'interfaces' object,
filtered with the <with-defaults> parameter.
</t>
<section title="<with-defaults> = 'report-all'">
<t>
The behavior of the <with-defaults>
parameter handling for the value 'report-all'
is demonstrated in this example.
</t>
<t>
<figure>
<artwork>
<![CDATA[
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get>
<filter type="subtree">
<interfaces xmlns="http://example.com/ns/interfaces"/>
</filter>
<with-defaults
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults">
report-all
</with-defaults>
</get>
</rpc>
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data>
<interfaces xmlns="http://example.com/ns/interfaces">
<interface>
<name>eth0</name>
<mtu>8192</mtu>
<status>up</status>
</interface>
<interface>
<name>eth1</name>
<mtu>1500</mtu>
<status>up</status>
</interface>
<interface>
<name>eth2</name>
<mtu>9000</mtu>
<status>not feeling so good</status>
</interface>
<interface>
<name>eth3</name>
<mtu>1500</mtu>
<status>waking up</status>
</interface>
</interfaces>
</data>
</rpc-reply>
]]>
</artwork>
</figure>
</t>
</section>
<section title="<with-defaults> = 'report-all-tagged'">
<t>
The behavior of the <with-defaults>
parameter handling for the value 'report-all-tagged'
is demonstrated in this example. A 'tagged' data node
is an element that contains the wd:default
XML attribute, set to 'true'.
</t>
<t>
The actual data nodes tagged by the server depends on the
defaults handling basic mode used by the server.
Only the data nodes that are considered to be default data
will be tagged.
</t>
<t>
In this example, the server's basic mode is equal to 'trim',
so all data nodes that would contain the schema default value
are tagged. If the server's basic mode is 'explicit',
then only data nodes that are not explicitly set data
are tagged. If the server's basic mode is 'report-all',
then no data nodes are tagged.
</t>
<t>
<figure>
<artwork>
<![CDATA[
<rpc message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get>
<filter type="subtree">
<interfaces xmlns="http://example.com/ns/interfaces"/>
</filter>
<with-defaults
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults">
report-all-tagged
</with-defaults>
</get>
</rpc>
<rpc-reply message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:wd="urn:ietf:params:xml:ns:netconf:default:1.0">
<data>
<interfaces xmlns="http://example.com/ns/interfaces">
<interface>
<name>eth0</name>
<mtu>8192</mtu>
<status wd:default="true">up</status>
</interface>
<interface>
<name>eth1</name>
<mtu wd:default="true">1500</mtu>
<status wd:default="true">up</status>
</interface>
<interface>
<name>eth2</name>
<mtu>9000</mtu>
<status>not feeling so good</status>
</interface>
<interface>
<name>eth3</name>
<mtu wd:default="true">1500</mtu>
<status>waking up</status>
</interface>
</interfaces>
</data>
</rpc-reply>
]]>
</artwork>
</figure>
</t>
</section>
<section title="<with-defaults> = 'trim'">
<t>
The behavior of the <with-defaults>
parameter handling for the value 'trim'
is demonstrated in this example.
</t>
<t>
<figure>
<artwork>
<![CDATA[
<rpc message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get>
<filter type="subtree">
<interfaces xmlns="http://example.com/ns/interfaces"/>
</filter>
<with-defaults
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults">
trim
</with-defaults>
</get>
</rpc>
<rpc-reply message-id="103"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data>
<interfaces xmlns="http://example.com/ns/interfaces">
<interface>
<name>eth0</name>
<mtu>8192</mtu>
</interface>
<interface>
<name>eth1</name>
</interface>
<interface>
<name>eth2</name>
<mtu>9000</mtu>
<status>not feeling so good</status>
</interface>
<interface>
<name>eth3</name>
<status>waking up</status>
</interface>
</interfaces>
</data>
</rpc-reply>
]]>
</artwork>
</figure>
</t>
</section>
<section title="<with-defaults> = 'explicit'">
<t>
The behavior of the <with-defaults>
parameter handling for the value 'explicit'
is demonstrated in this example.
</t>
<t>
<figure>
<artwork>
<![CDATA[
<rpc message-id="104"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get>
<filter type="subtree">
<interfaces xmlns="http://example.com/ns/interfaces"/>
</filter>
<with-defaults
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults">
explicit
</with-defaults>
</get>
</rpc>
<rpc-reply message-id="104"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data>
<interfaces xmlns="http://example.com/ns/interfaces">
<interface>
<name>eth0</name>
<mtu>8192</mtu>
<status>up</status>
</interface>
<interface>
<name>eth1</name>
<status>up</status>
</interface>
<interface>
<name>eth2</name>
<mtu>9000</mtu>
<status>not feeling so good</status>
</interface>
<interface>
<name>eth3</name>
<mtu>1500</mtu>
<status>waking up</status>
</interface>
</interfaces>
</data>
</rpc-reply>
]]>
</artwork>
</figure>
</t>
</section>
</section>
</section>
<section title="Change Log">
<t>
-- RFC Ed.: remove this section before publication.
</t>
<section title="10-11">
<t>
Changed term 'database' to 'configuration datastore' or generic 'datastore'.
</t>
</section>
<section title="09-10">
<t>
Changed term 'datastore' to 'database'.
</t>
<t>
Added term 'default value'.
</t>
<t>
Clarified verbage for data node containing a default value.
</t>
</section>
<section title="08-09">
<t>
Removed non-volatile server requirements.
</t>
<t>
Moved some text from basic-mode section into
the the retrieval modes section.
</t>
<t>
Added description and reference statements to the YANG module.
</t>
<t>
Many bugfixes and clarifications, based on WGLC review comments.
</t>
</section>
<section title="07-08">
<t>
Added report-all-tagged mode.
</t>
<t>
Changed conformance so report-all or
report-all-tagged mode SHOULD be supported.
</t>
<t>
Clarified capability requirements for each mode,
for edit-config and NV storage requirements.
</t>
<t>
Changed rpc-error details for unsupported with-defaults
value.
</t>
<t>
Added XSD for wd:default attribute
</t>
<t>
Expanded example to show report-all-tagged for
a basic-mode=trim server.
</t>
</section>
<section title="06-07">
<t>
Removed text in capability identifier section about adding
YANG module capability URI parameters.
</t>
<t>Changed YANG module namespace to match YANG format,
and updated examples to use this new namespace.</t>
<t>Fixed some typos.</t>
</section>
<section title="05-06">
<t>Removed ':1.0' from capability URI.</t>
<t>Removed open issues section because all known issues are closed.</t>
<t>Moved examples to a separate appendix, and expanded them.</t>
<t>Added example.yang as an appendix to properly explain
the examples used within the document.
</t>
<t>Replaced normative term 'SHALL' with 'MUST' to be consistent within
this document.
</t>
<t>Clarified <with-defaults> behavior for non-configuration data nodes.</t>
<t>Clarified various sections based on WGLC comments on mailing list.</t>
<t>Removed some unused terms.</t>
<t>Reversed the order of the change log sections so the
most recent changes are shown first.
</t>
</section>
<section title="04-05">
<t>Updated I-D and YANG module boiler-plate.</t>
<t>Removed redundant 'with-defaults' YANG feature.</t>
<t>Changed definition of 'explicit' mode to match the YANG definition</t>
<t>Removed XSD because the YANG is normative and the XSD is unconstrained,
and does not properly extend the 3 affected NETCONF operations.
</t>
<t>Made the YANG module a normative section instead of non-normative appendix.</t>
<t>Changed YANG from an informative to a normative reference,</t>
<t>Changed 4741bis from an informative to a normative reference because the YANG
module imports the ietf-netconf module in order to augment some operations.</t>
<t>Updated capability requirements to include YANG module capability parameters.</t>
<t>Added a description statement to the with-defaults leaf definition.</t>
<t>Update open issues section; ready to close all open issues.</t>
</section>
<section title="03-04">
<t>Clarifications</t>
<t>Added non-netconf interfaces to the definition of explicitly set default data</t>
</section>
<section title="02-03">
<t>Clarifications</t>
<t>YAM added</t>
<t>Use the same URN for the capability and the XML namespace to
accommodate YANG, and avoid two separate URN/URIs being advertised
in the HELLO message, for such a small function.</t>
</section>
<section title="01-02">
<t>report-all made mandatory</t>
<t>Placeholder for YAM added, XSD will be removed when 4741 provides the NETCONF YAM</t>
<t>with-defaults is valid for state data as well
(if state data has a defined default which might not be so frequent).
The definition of explicit was modified for state data.
</t>
</section>
<section title="00-01">
<t>Changed value set of with-default capability and element</t>
<t>Added version to URI</t>
</section>
<section title="-00">
<t>Created from draft-bierman-netconf-with-defaults-01.txt</t>
<t>
It was decided by the NETCONF mailing list, that with-defaults should be a
sub-element of each affected operation.
While this violates the XSD of RFC4741 this is acceptable and follows
the ideas behind NETCONF and YANG.
<vspace blankLines="1"/>
Hopefully it will be clarified in the 4741bis RFC whether such extensions are allowed.
</t>
</section>
</section>
</back>
</rfc>
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