System-defined Configuration
draft-ietf-netmod-system-config-00
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| Authors | Qiufang Ma , Qin Wu , Chong Feng | ||
| Last updated | 2022-11-29 | ||
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draft-ietf-netmod-system-config-00
NETMOD Q. Ma, Ed.
Internet-Draft Q. Wu
Updates: RFC8342, RFC6241, RFC8526, RFC8040 (if C. Feng
approved) Huawei
Intended status: Standards Track 28 November 2022
Expires: 1 June 2023
System-defined Configuration
draft-ietf-netmod-system-config-00
Abstract
This document updates NMDA to define a read-only conventional
configuration datastore called "system" to hold system-defined
configurations. To avoid clients' explicit copy/paste of referenced
system-defined configuration into the target configuration datastore
(e.g., <running>), a "resolve-system" parameter has been defined to
allow the server acting as a "system client" to copy referenced
system-defined nodes automatically. The solution enables clients
manipulating the target configuration datastore (e.g., <running>) to
overlay and reference nodes defined in <system>, override values of
configurations defined in <system>, and configure descendant nodes of
system-defined nodes.
Status of This Memo
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 https://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 1 June 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 5
1.3. Updates to RFC 8342 . . . . . . . . . . . . . . . . . . . 5
1.4. Updates to RFC 6241, RFC 8526 . . . . . . . . . . . . . . 5
1.5. Updates to RFC 8040 . . . . . . . . . . . . . . . . . . . 6
1.5.1. Query Parameter . . . . . . . . . . . . . . . . . . . 6
1.5.2. Query Parameter URI . . . . . . . . . . . . . . . . . 6
2. Kinds of System Configuration . . . . . . . . . . . . . . . . 6
2.1. Immediately-Active . . . . . . . . . . . . . . . . . . . 7
2.2. Conditionally-Active . . . . . . . . . . . . . . . . . . 7
2.3. Inactive-Until-Referenced . . . . . . . . . . . . . . . . 7
3. Static Characteristics . . . . . . . . . . . . . . . . . . . 7
3.1. Read-only to Clients . . . . . . . . . . . . . . . . . . 7
3.2. May Change via Software Upgrades . . . . . . . . . . . . 8
3.3. No Impact to <operational> . . . . . . . . . . . . . . . 8
4. Dynamic Behavior . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Conceptual Model . . . . . . . . . . . . . . . . . . . . 8
4.2. Explicit Declaration of System Configuration . . . . . . 9
4.3. Servers Auto-configuring Referenced System
Configuration . . . . . . . . . . . . . . . . . . . . . . 10
4.4. Modifying (overriding) System Configuration . . . . . . . 10
4.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 11
4.5.1. Server Configuring of <running> Automatically . . . . 11
4.5.2. Declaring a System-defined Node in <running>
Explicitly . . . . . . . . . . . . . . . . . . . . . 17
4.5.3. Modifying a System-instantiated Leaf's Value . . . . 20
4.5.4. Configuring Descendant Nodes of a System-defined
Node . . . . . . . . . . . . . . . . . . . . . . . . 22
5. The <system> Configuration Datastore . . . . . . . . . . . . 23
6. The "ietf-system-datastore" Module . . . . . . . . . . . . . 25
6.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 25
6.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 25
6.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 26
7. The "ietf-netconf-resolve-system" Module . . . . . . . . . . 28
7.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 28
7.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 29
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7.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 32
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
8.1. The "IETF XML" Registry . . . . . . . . . . . . . . . . . 35
8.2. The "YANG Module Names" Registry . . . . . . . . . . . . 35
8.3. RESTCONF Capability URN Registry . . . . . . . . . . . . 35
9. Security Considerations . . . . . . . . . . . . . . . . . . . 35
9.1. Regarding the "ietf-system-datastore" YANG Module . . . . 35
9.2. Regarding the "ietf-netconf-resolve-system" YANG
Module . . . . . . . . . . . . . . . . . . . . . . . . . 36
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 36
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 37
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Normative References . . . . . . . . . . . . . . . . . . . . . 37
Informative References . . . . . . . . . . . . . . . . . . . . 37
Appendix A. Key Use Cases . . . . . . . . . . . . . . . . . . . 38
A.1. Device Powers On . . . . . . . . . . . . . . . . . . . . 38
A.2. Client Commits Configuration . . . . . . . . . . . . . . 39
A.3. Operator Installs Card into a Chassis . . . . . . . . . . 40
Appendix B. Changes between Revisions . . . . . . . . . . . . . 41
Appendix C. Open Issues tracking . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 43
1. Introduction
NMDA [RFC8342] defines system configuration as the configuration that
is supplied by the device itself and appears in <operational> when it
is in use.
However, there is a desire to enable a server to better document the
system configuration. Clients can benefit from a standard mechanism
to see what system configuration is available in a server.
In some cases, the client references a system configuration which
isn't present in the target datastore (e.g., <running>). Having to
copy the entire contents of the system configuration into the target
datastore should be avoided or reduced when possible while ensuring
that all referential integrity constraints are satisfied.
In some other cases, configuration of descendant nodes of system-
defined configuration needs to be supported. For example, the system
configuration contains an almost empty physical interface, while the
client needs to be able to add, modify, remove a number of descendant
nodes. Some descendant nodes may not be modifiable (e.g., "name" and
"type" set by the system).
This document updates NMDA [RFC8342] to define a read-only
conventional configuration datastore called "system" to hold system-
defined configurations. To avoid clients' explicit copy/paste of
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referenced system-defined configuration into the target configuration
datastore (e.g., <running>), a "resolve-system" parameter has been
defined to allow the server acting as a "system client" to copy
referenced system-defined nodes automatically. The solution enables
clients manipulating the target configuration datastore (e.g.,
<running>) to overlay and reference nodes defined in <system>,
override values of configurations defined in <system>, and configure
descendant nodes of system-defined nodes.
Conformance to this document requires servers to implement the "ietf-
system-datastore" YANG module.
1.1. Terminology
This document assumes that the reader is familiar with the contents
of [RFC6241], [RFC7950], [RFC8342], [RFC8407], and [RFC8525] and uses
terminologies from those documents.
The following terms are defined in this document as follows:
System configuration: Configuration that is provided by the system
itself. System configuration is present in <system> once it's
created (regardless of being applied by the device), and appears
in <intended> which is subject to validation. Applied system
configuration also appears in <operational> with origin="system".
System configuration datastore: A configuration datastore holding
the complete configuration provided by the system itself. This
datastore is referred to as "<system>".
This document redefines the term "conventional configuration
datastore" from RFC 8342 to add "system" to the list of conventional
configuration datastores:
Conventional configuration datastore: One of the following set of
configuration datastores: <running>, <startup>, <candidate>,
<system>, and <intended>. These datastores share a common
datastore schema, and protocol operations allow copying data
between these datastores. The term "conventional" is chosen as a
generic umbrella term for these datastores.
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1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.3. Updates to RFC 8342
This document updates RFC 8342 to define a configuration datastore
called "system" to hold system configuration, it also redefines the
term "conventional configuration datastore" from RFC 8342 to add
"system" to the list of conventional configuration datastores. The
contents of <system> datastore are read-only to clients but may
change dynamically. The <system> aware client may retrieve all three
types of system configuration defined in Section 2, reference nodes
defined in <system>, override values of configurations defined in
<system>, and configure descendant nodes of system-defined nodes.
The server will merge <running> and <system> to create <intended>.
As always, system configuration will appear in <operational> with
origin="system" when it is in use.
The <system> datastore makes system configuration visible to clients
in order for being referenced or configurable prior to present in
<operational>.
1.4. Updates to RFC 6241, RFC 8526
This document augments <edit-config> and <edit-data> RPC operations
defined in [RFC6241] and [RFC8526] respectively, with a new
additional input parameter "resolve-system". The <copy-config> RPC
operation defined in [RFC6241] is also augmented to support "resolve-
system" parameter.
The "resolve-system" parameter is optional and has no value. When it
is provided and the server detects that there is a reference to a
system-defined node during the validation, the server will
automatically copy the referenced system configuration into the
validated datastore to make the configuration valid without the
client doing so explicitly. Legacy Clients interacting with servers
that support this parameter don't see any changes in <edit-
config>/<edit-data> and <copy-config> behaviors.
According to the NETCONF constraint enforcement model defined in the
section 8.3 of [RFC7950], if the target datastore of the <edit-
config>/<edit-data> or <copy-config> is "running" or "startup", the
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server's copy referenced nodes from <system> to the target datastore
MUST be enforced at the end of the <edit-config>/<edit-data> or
<copy-config> operations during the validation. If the target
datastore of the <edit-config>/<edit-data> or <copy-config> is
"candidate", the server's copy referenced nodes from <system> to the
target datastore is delayed until a <commit> or <validate> operation
takes place.
1.5. Updates to RFC 8040
This document extends Section 4.8 and Section 9.1.1 of [RFC8040] to
add a new query parameter "resolve-system" and corresponding query
parameter capability URI.
1.5.1. Query Parameter
The "resolve-system" parameter controls whether to allow a server
copy any referenced system-defined configuration automatically
without the client doing so explicitly. This parameter is only
allowed with no values carried. If this parameter has any unexpected
value, then a "400 Bad Request" status-line is returned.
+----------------+---------+-----------------------------------------+
| Name | Methods | Description |
+----------------+---------+-----------------------------------------+
|resolve-system | POST, | resolve any references not resolved by |
| | PUT | the client and copy referenced |
| | | system configuration into <running> |
| | | automatically. This parameter can be |
| | | given in any order. |
+----------------+---------+-----------------------------------------+
1.5.2. Query Parameter URI
To enable the RESTCONF client to discover if the "resolve-system"
query parameter is supported by the server, the following capability
URI is defined, which is advertised by the server if supported, using
the "ietf-restconf-monitoring" module defined in RFC 8040:
urn:ietf:params:restconf:capability:resolve-system:1.0
2. Kinds of System Configuration
There are three types of system configurations: immediately-active
system configuration, conditionally-active system configuration and
inactive-until-referenced system configuration.
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2.1. Immediately-Active
Immediately-active system configurations are those generated in
<system> and applied immediately when the device is powered on (e.g.,
a loop-back interface) , irrespective of physical resource present or
not, a special functionality enabled or not.
2.2. Conditionally-Active
System configurations which are generated in <system> and applied
based on specific conditions being met in a system, e.g., if a
physical resource is present (e.g., insert interface card), the
system will automatically detect it and load pre-provisioned
configuration; when the physical resource is not present( remove
interface card), the system configuration will be automatically
cleared. Another example is when a special functionality is enabled,
e.g., when QoS function is enabled, QoS policies are automatically
created by the system.
2.3. Inactive-Until-Referenced
There are some system configurations predefined (e.g., application
ids, anti-x signatures, trust anchor certs, etc.) as a convenience
for the clients, which must be referenced to be active. The clients
can also define their own configurations for their unique
requirements. Inactive-until-referenced system configurations are
generated in <system> immediately when the device is powered on, but
they are not applied and active until being referenced.
3. Static Characteristics
3.1. Read-only to Clients
The <system> configuration datastore is a read-only configuration
datastore (i.e., edits towards <system> directly MUST be denied),
though the client may be allowed to override the value of a system-
initialized data node (see Section 4.4). Configuration defined in
<system> is merged into <intended>, and present in <operational> if
it is actively in use by the device. Thus unless the resource is no
longer available (e.g., the interface removed physically), there is
no way to actually delete system configuration from a server, even if
a client may be allowed to delete the configuration copied from
<system> into <running>. Any deletable system-provided configuration
must be defined in <factory-default> [RFC8808], which is used to
initialize <running> when the device is first-time powered on or
reset to its factory default condition.
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3.2. May Change via Software Upgrades
System configuration MAY change dynamically, e.g., depending on
factors like device upgrade or if system-controlled resources(e.g.,
HW available) change. In some implementations, when QoS function is
enabled, QoS-related policies are created by system. If the system
configuration gets changed, YANG notification (e.g., "push-change-
update" notification) [RFC8641][RFC8639][RFC6470] can be used to
notify the client. Any update of the contents in <system> will not
cause the automatic update of <running>, even if some of the system
configuration has already been copied into <running> explicitly or
automatically before the update.
3.3. No Impact to <operational>
This work intends to have no impact to <operational>. As always,
system configuration will appear in <operational> with
"origin=system". This work enables a subset of those system
generated nodes to be defined like configuration, i.e., made visible
to clients in order for being referenced or configurable prior to
present in <operational>. "Config false" nodes are out of scope,
hence existing "config false" nodes are not impacted by this work.
4. Dynamic Behavior
4.1. Conceptual Model
This document introduces a mandatory datastore named "system" which
is used to hold all three types of system configurations defined in
Section 2.
When the device is powered on, immediately-active system
configuration will be generated in <system> and applied immediately
but inactive-until-referenced system configuration only becomes
active if it is referenced by client-defined configuration. While
conditionally-active system configuration will be created and
immediately applied if the condition on system resources is met when
the device is powered on or running.
All above three types of system configurations will appear in
<system>. Clients MAY reference nodes defined in <system>, override
values of configurations defined in <system>, and configure
descendant nodes of system-defined nodes, by copying or writing
intended configurations into the target configuration datastore
(e.g., <running>).
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The server will merge <running> and <system> to create <intended>, in
which process, the data node appears in <running> takes precedence
over the same node in <system> if the server allows the node to be
modifiable; additional nodes to a list entry or new list/leaf-list
entries appear in <running> extends the list entry or the whole list/
leaf-list defined in <system> if the server allows the list/leaf-list
to be updated. In addition, the <intended> configuration datastore
represents the configuration after all configuration transformation
to <system> are performed (e.g., system-defined template expansion,
removal of inactive system configuration). If a server implements
<intended>, <system> MUST be merged into <intended>.
Servers MUST enforce that configuration references in <running> are
resolved within the <running> datastore and ensure that <running>
contains any referenced system configuration. Clients MUST either
explicitly copy system-defined nodes into <running> or use the
"resolve-system" parameter. The server MUST enforce that the
referenced system nodes configured into <running> by the client is
consistent with <system>. Note that <system> aware clients know how
to discover what nodes exist in <system>. How clients unaware of the
<system> datastore can find appropriate configurations is beyond the
scope of this document.
No matter how the referenced system configurations are copied into
<running>, the nodes copied into <running> would always be returned
after a read of <running>, regardless if the client is <system>
aware.
4.2. Explicit Declaration of System Configuration
It is possible for a client to explicitly declare system
configuration nodes in the target datastore (e.g., <running>) with
the same values as in <system>, by configuring a node (list/leaf-list
entry, leaf, etc) in the target datastore (e.g., <running>) that
matches the same node and value in <system>.
This explicit configuration of system-defined nodes in <running> can
be useful, for example, when the client doesn't want a "system
client" to have a role or hasn't implemented the "resolve-system"
parameter. The client can explicitly declare (i.e. configure in
<running>) the list entries (with at least the keys) for any system
configuration list entries that are referenced elsewhere in
<running>. The client does not necessarily need to declare all the
contents of the list entry (i.e. the descendant nodes) - only the
parts that are required to make the <running> appear valid.
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4.3. Servers Auto-configuring Referenced System Configuration
This document defines a new parameter "resolve-system" to the input
for the <edit-config>, <edit-data> and <copy-config> operations.
Clients that are aware of the "resolve-system" parameter MAY use this
parameter to avoid the requirement to provide a referentially
complete configuration in <running>.
If the "resolve-system" is present, the server MUST copy relevant
referenced system-defined nodes into the target datastore (e.g.,
<running>) without the client doing the copy/paste explicitly, to
resolve any references not resolved by the client. The server acting
as a "system client" like any other remote clients copies the
referenced system-defined nodes when triggered by the "resolve-
system" parameter.
If the "resolve-system" parameter is not given by the client, the
server should not modify <running> in any way otherwise not specified
by the client. Not using capitalized "SHOULD NOT" in the previous
sentence is intentional. The intention is bring awareness to the
general need to not surprise clients with unexpected changes. It is
desirable for clients to always opt into using mechanisms having
server-side changes. This document enables a client to opt into this
behavior using the "resolve-system" parameter. RFC 7317 enables a
client to opt into its behavior using a "$0$" prefix (see
ianach:crypt-hash type defined in [RFC7317]).
The server may automatically configure the list entries (with at
least the keys) in the target datastore (e.g., <running>) for any
system configuration list entries that are referenced elsewhere by
the clients. Similarly, not all the contents of the list entry
(i.e., the descendant nodes) are necessarily copied by the server -
only the parts that are required to make the <running> valid. A read
back of <running> (i.e., <get>, <get-config> or <get-data> operation)
returns those automatically copied nodes.
4.4. Modifying (overriding) System Configuration
In some cases, a server may allow some parts of system configuration
to be modified. List keys in system configuration can't be changed
by a client, but other descendant nodes in a list entry may be
modifiable or non-modifiable. Leafs and leaf-lists outside of lists
may also be modifiable or non-modifiable. Even if some system
configuration has been copied into <running> earlier, whether it is
modifiable or not in <running> follows general YANG and NACM rules,
and other server-internal restrictions. If a system configuration
node is non-modifiable, then writing a different value for that node
in <running> MUST return an error. The immutability of system
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configuration is further defined in [I-D.ma-netmod-immutable-flag].
Modification of system configuration is achieved by the client
writing configuration to <running> that overrides the system
configuration. Configurations defined in <running> take precedence
over system configuration nodes in <system> if the server allows the
nodes to be modified.
A server may also allow a client to add data nodes to a list entry in
<system> by writing those additional nodes in <running>. Those
additional data nodes may not exist in <system> (i.e. an *addition*
rather than an override).
While modifying (overriding) system configuration nodes may be
supported by a server, there is no mechanism for deleting a system
configuration node in <system> unless the resource is no longer
available. For example, a "mandatory true" leaf may have a value in
<system> which can be modified (overridden) by a client setting that
leaf to a value in <running>. But the leaf could not be deleted.
Another example of this might be that system initializes a value for
a particular leaf which is overridden by the client with intended
value in <running>. The client may delete the leaf in <running>, but
system-initialized value defined in <system> will be in use and
appear in <operational>.
Comment 1: What if <system> contains a set of values for a leaf-list,
and a client configures another set of values for that leaf-list in
<running>, will the set of values in <running> completely replace the
set of values in <system>? Or the two sets of values are merged
together?
Comment 2: how "ordered-by user" lists and leaf-lists are merged? Do
the <running> values go before or after, or is this a case where a
full-replace is needed.
4.5. Examples
This section shows the examples of server-configuring of <running>
automatically, declaring a system-defined node in <running>
explicitly, modifying a system-instantiated leaf's value and
configuring descendant nodes of a system-defined node. For each
example, the corresponding XML snippets are provided.
4.5.1. Server Configuring of <running> Automatically
In this subsection, the following fictional module is used:
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module example-application {
yang-version 1.1;
namespace "urn:example:application";
prefix "app";
import ietf-inet-types {
prefix "inet";
}
container applications {
list application {
key "name";
leaf name {
type string;
}
leaf protocol {
type enumeration {
enum tcp;
enum udp;
}
}
leaf destination-port {
type inet:port-number;
}
}
}
}
The server may predefine some applications as a convenience for the
clients. These predefined configurations are applied only after
being referenced by other configurations, which fall into the
"inactive-until-referenced" system configuration as defined in
Section 2. The system-instantiated application entries may be
present in <system> as follows:
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<applications xmlns="urn:example:application">
<application>
<name>ftp</name>
<protocol>tcp</protocol>
<destination-port>21</destination-port>
</application>
<application>
<name>tftp</name>
<protocol>udp</protocol>
<destination-port>69</destination-port>
</application>
<application>
<name>smtp</name>
<protocol>tcp</protocol>
<destination-port>25</destination-port>
</application>
...
</applications>
The client may also define its customized applications. Suppose the
configuration of applications is present in <running> as follows:
<applications xmlns="urn:example:application">
<application>
<name>my-app-1</name>
<protocol>tcp</protocol>
<destination-port>2345</destination-port>
</application>
<application>
<name>my-app-2</name>
<protocol>udp</protocol>
<destination-port>69</destination-port>
</application>
</applications>
A fictional ACL YANG module is used as follows, which defines a
leafref for the leaf-list "application" data node to refer to an
existing application name.
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module example-acl {
yang-version 1.1;
namespace "urn:example:acl";
prefix "acl";
import example-application {
prefix "app";
}
import ietf-inet-types {
prefix "inet";
}
container acl {
list acl_rule {
key "name";
leaf name {
type string;
}
container matches {
choice l3 {
container ipv4 {
leaf source_address {
type inet:ipv4-prefix;
}
leaf dest_address {
type inet:ipv4-prefix;
}
}
}
choice applications {
leaf-list application {
type leafref {
path "/app:applications/app:application/app:name";
}
}
}
}
leaf packet_action {
type enumeration {
enum forward;
enum drop;
enum redirect;
}
}
}
}
}
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If a client configures an ACL rule referencing system predefined
nodes which are not present in <running>, the client MAY issue an
<edit-config> operation with the parameter "resolve-system" as
follows:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<config>
<acl xmlns="urn:example:acl">
<acl_rule>
<name>allow_access_to_ftp_tftp</name>
<matches>
<ipv4>
<source_address>198.51.100.0/24</source_address>
<dest_address>192.0.2.0/24</dest_address>
</ipv4>
<application>ftp</application>
<application>tftp</application>
<application>my-app-1</application>
</matches>
<packet_action>forward</packet_action>
</acl_rule>
</acl>
</config>
<resolve-system/>
</edit-config>
</rpc>
Then following gives the configuration of applications in <running>
which is returned in the response to a follow-up <get-config>
operation:
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<applications xmlns="urn:example:application">
<application>
<name>my-app-1</name>
<protocol>tcp</protocol>
<destination-port>2345</destination-port>
</application>
<application>
<name>my-app-2</name>
<protocol>udp</protocol>
<destination-port>69</destination-port>
</application>
<application>
<name>ftp</name>
</application>
<application>
<name>tftp</name>
</application>
</applications>
Then the configuration of applications is present in <operational> as
follows:
<applications xmlns="urn:example:application"
xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<application>
<name>my-app-1</name>
<protocol>tcp</protocol>
<destination-port>2345</destination-port>
</application>
<application>
<name>my-app-2</name>
<protocol>udp</protocol>
<destination-port>69</destination-port>
</application>
<application or:origin="or:system">
<name>ftp</name>
<protocol>tcp</protocol>
<destination-port>21</destination-port>
</application>
<application or:origin="or:system">
<name>tftp</name>
<protocol>udp</protocol>
<destination-port>69</destination-port>
</application>
</applications>
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Since the configuration of application "smtp" is not referenced by
the client, it does not appear in <operational> but only in <system>.
4.5.2. Declaring a System-defined Node in <running> Explicitly
It's also possible for a client to explicitly declare the system-
defined configurations that are referenced. For instance, in the
above example, the client MAY also explicitly configure the following
system defined applications "ftp" and "tftp" only with the list key
"name" before referencing:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<config>
<applications xmlns="urn:example:application">
<application>
<name>ftp</name>
</application>
<application>
<name>tftp</name>
</application>
</applications>
</config>
</edit-config>
</rpc>
Then the client issues an <edit-config> operation to configure an ACL
rule referencing applications "ftp" and "tftp" without the parameter
"resolve-system" as follows:
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<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<config>
<acl xmlns="urn:example:acl">
<acl_rule>
<name>allow_access_to_ftp_tftp</name>
<matches>
<ipv4>
<source_address>198.51.100.0/24</source_address>
<dest_address>192.0.2.0/24</dest_address>
</ipv4>
<application>ftp</application>
<application>tftp</application>
<application>my-app-1</application>
</matches>
<packet_action>forward</packet_action>
</acl_rule>
</acl>
</config>
</edit-config>
</rpc>
Then following gives the configuration of applications in <running>
which is returned in the response to a follow-up <get-config>
operation, all the configuration of applications are explicitly
configured by the client:
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<applications xmlns="urn:example:application">
<application>
<name>my-app-1</name>
<protocol>tcp</protocol>
<destination-port>2345</destination-port>
</application>
<application>
<name>my-app-2</name>
<protocol>udp</protocol>
<destination-port>69</destination-port>
</application>
<application>
<name>ftp</name>
</application>
<application>
<name>tftp</name>
</application>
</applications>
Then the configuration of applications is present in <operational> as
follows:
<applications xmlns="urn:example:application"
xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<application>
<name>my-app-1</name>
<protocol>tcp</protocol>
<destination-port>2345</destination-port>
</application>
<application>
<name>my-app-2</name>
<protocol>udp</protocol>
<destination-port>69</destination-port>
</application>
<application>
<name>ftp</name>
<protocol or:origin="or:system">tcp</protocol>
<destination-port or:origin="or:system">21</destination-port>
</application>
<application>
<name>tftp</name>
<protocol or:origin="or:system">udp</protocol>
<destination-port or:origin="or:system">69</destination-port>
</application>
</applications>
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Since the application names "ftp" and "tftp" are explicitly
configured by the client, they take precedence over the values in
<system>, the "origin" attribute will be set to "intended".
4.5.3. Modifying a System-instantiated Leaf's Value
In this subsection, we will use this fictional QoS data model:
module example-qos-policy {
yang-version 1.1;
namespace "urn:example:qos";
prefix "qos";
container qos-policies {
list policy {
key "name";
leaf name {
type string;
}
list queue {
key "queue-id";
leaf queue-id {
type int32 {
range "1..32";
}
}
leaf maximum-burst-size {
type int32 {
range "0..100";
}
}
}
}
}
}
Suppose a client creates a qos policy "my-policy" with 4 system
instantiated queues(1~4). The Configuration of qos-policies is
present in <system> as follows:
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<qos-policies xmlns="urn:example:qos">
<name>my-policy</name>
<queue>
<queue-id>1</queue-id>
<maximum-burst-size>50</maximum-burst-size>
</queue>
<queue>
<queue-id>2</queue-id>
<maximum-burst-size>60</maximum-burst-size>
</queue>
<queue>
<queue-id>3</queue-id>
<maximum-burst-size>70</maximum-burst-size>
</queue>
<queue>
<queue-id>4</queue-id>
<maximum-burst-size>80</maximum-burst-size>
</queue>
</qos-policies>
A client modifies the value of maximum-burst-size to 55 in queue-id
1:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<config>
<qos-policies xmlns="urn:example:qos">
<name>my-policy</name>
<queue>
<queue-id>1</queue-id>
<maximum-burst-size>55</maximum-burst-size>
</queue>
</qos-policies>
</config>
</edit-config>
</rpc>
Then the configuration of qos-policies is present in <operational> as
follows:
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<qos-policies xmlns="urn:example:qos"
xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<name>my-policy</name>
<queue>
<queue-id>1</queue-id>
<maximum-burst-size>55</maximum-burst-size>
</queue>
<queue or:origin="or:system">
<queue-id>2</queue-id>
<maximum-burst-size>60</maximum-burst-size>
</queue>
<queue or:origin="or:system">
<queue-id>3</queue-id>
<maximum-burst-size>70</maximum-burst-size>
</queue>
<queue or:origin="or:system">
<queue-id>4</queue-id>
<maximum-burst-size>80</maximum-burst-size>
</queue>
</qos-policies>
4.5.4. Configuring Descendant Nodes of a System-defined Node
This subsection also uses the fictional interface YANG module defined
in Appendix C.3 of [RFC8342]. Suppose the system provides a loopback
interface (named "lo0") with a default IPv4 address of "127.0.0.1"
and a default IPv6 address of "::1".
The configuration of "lo0" interface is present in <system> as
follows:
<interfaces>
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
</interfaces>
The configuration of "lo0" interface is present in <operational> as
follows:
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<interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:system">
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
</interfaces>
Later on, the client further configures the description node of a
"lo0" interface as follows:
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<running/>
</target>
<config>
<interfaces>
<interface>
<name>lo0</name>
<description>loopback</description>
</interface>
</interfaces>
</config>
</edit-config>
</rpc>
Then the configuration of interface "lo0" is present in <operational>
as follows:
<interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<interface>
<name>lo0</name>
<description>loopback</description>
<ip-address or:origin="or:system">127.0.0.1</ip-address>
<ip-address or:origin="or:system">::1</ip-address>
</interface>
</interfaces>
5. The <system> Configuration Datastore
NMDA servers claiming to support this document MUST implement a
<system> configuration datastore, and they SHOULD also implement the
<intended> datastore.
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Following guidelines for defining datastores in the appendix A of
[RFC8342], this document introduces a new datastore resource named
'system' that represents the system configuration. A device MAY
implement the mechanism defined in this document without implementing
the "system" datastore, which would only eliminate the ability to
programmatically determine the system configuration.
* Name: "system"
* YANG modules: all
* YANG nodes: all "config true" data nodes up to the root of the
tree, generated by the system
* Management operations: The content of the datastore is set by the
server in an implementation dependent manner. The content can not
be changed by management operations via NETCONF, RESTCONF, the
CLI, etc, but may change itself by upgrades and/or when resource-
conditions are met. The datastore can be read using the standard
NETCONF/RESTCONF protocol operations.
* Origin: This document does not define any new origin identity when
it interacts with <intended> datastore and flows into
<operational>. The "system" origin Metadata Annotation [RFC7952]
is used to indicate the origin of a data item is system.
* Protocols: YANG-driven management protocols, such as NETCONF and
RESTCONF.
* Defining YANG module: "ietf-system-datastore".
The datastore's content is defined by the server and read-only to
clients. Upon the content is created or changed, it will be merged
into <intended> datastore. Unlike <factory-default>[RFC8808], it MAY
change dynamically, e.g., depending on factors like device upgrade or
system-controlled resources change (e.g., HW available). The
<system> datastore doesn't persist across reboots; the contents of
<system> will be lost upon reboot and recreated by the system with
the same or changed contents. <factory-reset> RPC operation defined
in [RFC8808] can reset it to its factory default configuration
without including configuration generated due to the system update or
client-enabled functionality.
The <system> datastore is defined as a conventional configuration
datastore and shares a common datastore schema with other
conventional datastores. The <system> configuration datastore must
always be valid, as defined in Section 8.1 of [RFC7950].
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6. The "ietf-system-datastore" Module
6.1. Data Model Overview
This YANG module defines a new YANG identity named "system" that uses
the "ds:datastore" identity defined in [RFC8342]. A client can
discover the <system> datastore support on the server by reading the
YANG library information from the operational state datastore. Note
that no new origin identity is defined in this document, the
"or:system" origin Metadata Annotation [RFC7952] is used to indicate
the origin of a data item is system. Support for the "origin"
annotation is identified with the feature "origin" defined in
[RFC8526].
The following diagram illustrates the relationship amongst the
"identity" statements defined in the "ietf-system-datastore" and
"ietf-datastores" YANG modules:
Identities:
+--- datastore
| +--- conventional
| | +--- running
| | +--- candidate
| | +--- startup
| | +--- system
| | +--- intended
| +--- dynamic
| +--- operational
The diagram above uses syntax that is similar to but not defined in [RFC8340].
6.2. Example Usage
This section gives an example of data retrieval from <system>. The
YANG module used are shown in Appendix C.2 of [RFC8342]. All the
messages are presented in a protocol-independent manner. JSON is
used only for its conciseness.
Suppose the following data is added to <running>:
{
"bgp": {
"local-as": "64501",
"peer-as": "64502",
"peer": {
"name": "2001:db8::2:3"
}
}
}
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REQUEST (a <get-data> or GET request sent from the NETCONF or
RESTCONF client):
Datastore: <system>
Target:/bgp
An example of RESTCONF request:
GET /restconf/ds/system/bgp HTTP/1.1
Host: example.com
Accept: application/yang-data+xml
RESPONSE ("local-port" leaf value is supplied by the system):
{
"bgp": {
"peer": {
"name": "2001:db8::2:3",
"local-port": "60794"
}
}
}
6.3. YANG Module
<CODE BEGINS>
file="ietf-system-datastore@2022-08-09.yang"
module ietf-system-datastore {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-system-datastore";
prefix sysds;
import ietf-datastores {
prefix ds;
reference
"RFC 8342: Network Management Datastore Architecture(NMDA)";
}
organization
"IETF NETMDOD (Network Modeling) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
Author: Qiufang Ma
<mailto:maqiufang1@huawei.com>
Author: Qin Wu
<mailto:bill.wu@huawei.com>
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Author: Chong Feng
<mailto:frank.fengchong@huawei.com>";
description
"This module defines a new YANG identity that uses the
ds:datastore identity defined in [RFC8342].
Copyright (c) 2022 IETF Trust and the persons identified
as authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with
or without modification, is permitted pursuant to, and
subject to the license terms contained in, the Revised
BSD License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC HHHH
(https://www.rfc-editor.org/info/rfcHHHH); see the RFC
itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2022-08-09 {
description
"Initial version.";
reference
"RFC XXXX: System-defined Configuration";
}
identity system {
base ds:conventional;
description
"This read-only datastore contains the complete configuration
provided by the system itself.";
}
}
<CODE ENDS>
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7. The "ietf-netconf-resolve-system" Module
This YANG module is optional to implement.
7.1. Data Model Overview
This YANG module augments NETCONF <edit-config>, <edit-data> and
<copy-config> operations with a new parameter "resolve-system" in the
input parameters. If the "resolve-system" parameter is present, the
server will copy the referenced system configuration into target
datastore automatically. A NETCONF client can discover the "resolve-
system" parameter support on the server by checking the YANG library
information with "ietf-netconf-resolve-system" included from the
operational state datastore.
The following tree diagram [RFC8340] illustrates the "ietf-netconf-
resolve-system" module:
module: ietf-netconf-resolve-system
augment /nc:edit-config/nc:input:
+---w resolve-system? empty
augment /nc:copy-config/nc:input:
+---w resolve-system? empty
augment /ncds:edit-data/ncds:input:
+---w resolve-system? empty
The following tree diagram [RFC8340] illustrates "edit-config",
"copy-config" and "edit-data" rpcs defined in "ietf-netconf" and
"ietf-netconf-nmda" respectively, augmented by "ietf-netconf-resolve-
system" YANG module :
rpcs:
+---x edit-config
| +---w input
| +---w target
| | +---w (config-target)
| | +--:(candidate)
| | | +---w candidate? empty {candidate}?
| | +--:(running)
| | +---w running? empty {writable-running}?
| +---w default-operation? enumeration
| +---w test-option? enumeration {validate}?
| +---w error-option? enumeration
| +---w (edit-content)
| | +--:(config)
| | | +---w config? <anyxml>
| | +--:(url)
| | +---w url? inet:uri {url}?
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| +---w resolve-system? empty
+---x copy-config
| +---w input
| +---w target
| | +---w (config-target)
| | +--:(candidate)
| | | +---w candidate? empty {candidate}?
| | +--:(running)
| | | +---w running? empty {writable-running}?
| | +--:(startup)
| | | +---w startup? empty {startup}?
| | +--:(url)
| | +---w url? inet:uri {url}?
| +---w source
| | +---w (config-source)
| | +--:(candidate)
| | | +---w candidate? empty {candidate}?
| | +--:(running)
| | | +---w running? empty
| | +--:(startup)
| | | +---w startup? empty {startup}?
| | +--:(url)
| | | +---w url? inet:uri {url}?
| | +--:(config)
| | +---w config? <anyxml>
| +---w resolve-system? empty
+---x edit-data
+---w input
+---w datastore ds:datastore-ref
+---w default-operation? enumeration
+---w (edit-content)
| +--:(config)
| | +---w config? <anydata>
| +--:(url)
| +---w url? inet:uri {nc:url}?
+---w resolve-system? empty
7.2. Example Usage
This section gives an example of an <edit-config> request to
reference system-defined data nodes which are not present in
<running> with a "resolve-system" parameter. A retrieval of
<running> to show the auto-copied referenced system configurations
after the <edit-config> request is also given. The YANG module used
is shown as follows, leafrefs refer to an existing name and address
of an interface:
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module example-interface-management {
yang-version 1.1;
namespace "urn:example:interfacemgmt";
prefix "inm";
container interfaces {
list interface {
key name;
leaf name {
type string;
}
leaf description {
type string;
}
leaf mtu {
type uint16;
}
leaf ip-address {
type inet:ip-address;
}
}
}
container default-address {
leaf ifname {
type leafref {
path "../../interfaces/interface/name";
}
}
leaf address {
type leafref {
path "../../interfaces/interface[name = current()/../ifname]"
+ "/ip-address";
}
}
}
}
Image that the system provides a loopback interface (named "lo0")
with a predefined MTU value of "1500" and a predefined IP address of
"127.0.0.1". The <system> datastore shows the following
configuration of loopback interface:
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<interfaces xmlns="urn:example:interfacemgmt">
<interface>
<name>lo0</name>
<mtu>1500</mtu>
<ip-address>127.0.0.1</ip-address>
</interface>
</interfaces>
The client sends an <edit-config> operation to add the configuration
of default-address with a "resolve-system" parameter:
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="101">
<edit-config>
<target>
<running/>
</target>
<config>
<default-address xmlns="urn:example:interfacemgmt">
<if-name>lo0</if-name>
<address>127.0.0.1</address>
</default-address>
</config>
<resolve-system/>
</edit-config>
</rpc>
Since the "resolve-system" parameter is provided, the server will
resolve any leafrefs to system configurations and copy the referenced
system-defined nodes into <running> automatically with the same value
(i.e., the name and ip-address data nodes of lo0 interface) in
<system> at the end of <edit-config> operation constraint
enforcement. After the processing, a positive resonse is returned:
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<ok/>
</rpc-reply>
Then the client sends a <get-config> operation towards <running>:
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<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get-config>
<source>
<running/>
</source>
<filter type="subtree">
<interfaces xmlns="urn:example:interfacemgmt"/>
</filter>
</get-config>
</rpc>
Given that the referenced interface "name" and "ip-address" of lo0
are configured by the server, the following response is returned:
<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data>
<interfaces xmlns="urn:example:interfacemgmt">
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
</interface>
</interfaces>
</data>
</rpc-reply>
7.3. YANG Module
<CODE BEGINS>
file="ietf-netconf-resolve-system@2022-08-09.yang"
module ietf-netconf-resolve-system {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-resolve-system";
prefix ncrs;
import ietf-netconf {
prefix nc;
reference
"RFC 6241: Network Configuration Protocol (NETCONF)";
}
import ietf-netconf-nmda {
prefix ncds;
reference
"RFC 8526: NETCONF Extensions to Support the Network
Management Datastore Architecture";
}
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organization
"IETF NETMOD (Network Modeling) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
Author: Qiufang Ma
<mailto:maqiufang1@huawei.com>
Author: Qin Wu
<mailto:bill.wu@huawei.com>
Author: Chong Feng
<mailto:frank.fengchong@huawei.com>";
description
"This module defines an extension to the NETCONF protocol
that allows the NETCONF client to control whether the server
is allowed to copy referenced system configuration
automatically without the client doing so explicitly.
Copyright (c) 2022 IETF Trust and the persons identified
as authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with
or without modification, is permitted pursuant to, and
subject to the license terms contained in, the Revised
BSD License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC HHHH
(https://www.rfc-editor.org/info/rfcHHHH); see the RFC
itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2022-08-09 {
description
"Initial version.";
reference
"RFC XXXX: System-defined Configuration";
}
augment /nc:edit-config/nc:input {
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description
"Allows the server to automatically configure
referenced system configuration to make configuration
valid.";
leaf resolve-system {
type empty ;
description
"When present, the server is allowed to automatically
configure referenced system configuration into the
target configuration datastore.";
}
}
augment /nc:copy-config/nc:input {
description
"Allows the server to automatically configure
referenced system configuration to make configuration
valid.";
leaf resolve-system {
type empty ;
description
"When present, the server is allowed to automatically
configure referenced system configuration into the
target configuration datastore.";
}
}
augment /ncds:edit-data/ncds:input {
description
"Allows the server to automatically configure
referenced system configuration to make configuration
valid.";
leaf resolve-system {
type empty ;
description
"When present, the server is allowed to automatically
configure referenced system configuration into the
target configuration datastore.";
}
}
}
<CODE ENDS>
8. IANA Considerations
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8.1. The "IETF XML" Registry
This document registers two XML namespace URNs in the 'IETF XML
registry', following the format defined in [RFC3688].
URI: urn:ietf:params:xml:ns:yang:ietf-system-datastore
Registrant Contact: The IESG.
XML: N/A, the requested URIs are XML namespaces.
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-resolve-system
Registrant Contact: The IESG.
XML: N/A, the requested URIs are XML namespaces.
8.2. The "YANG Module Names" Registry
This document registers two module names in the 'YANG Module Names'
registry, defined in [RFC6020] .
name: ietf-system-datastore
prefix: sys
namespace: urn:ietf:params:xml:ns:yang:ietf-system-datatstore
RFC: XXXX // RFC Ed.: replace XXXX and remove this comment
name: ietf-netconf-resolve-system
prefix: ncrs
namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-resolve-system
RFC: XXXX // RFC Ed.: replace XXXX and remove this comment
8.3. RESTCONF Capability URN Registry
This document registers a capability in the "RESTCONF Capability
URNs" registry [RFC8040]:
Index Capability Identifier
-----------------------------------------------------------------------
:resolve-system urn:ietf:params:restconf:capability:resolve-system:1.0
9. Security Considerations
9.1. Regarding the "ietf-system-datastore" YANG Module
The YANG module defined in this document extends the base operations
for NETCONF [RFC6241] and RESTCONF [RFC8040]. The lowest NETCONF
layer is the secure transport layer, and the mandatory-to-implement
secure transport is Secure Shell (SSH) [RFC6242]. The lowest
RESTCONF layer is HTTPS, and the mandatory-to-implement secure
transport is TLS [RFC8446].
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The Network Configuration Access Control Model (NACM) [RFC8341]
provides the means to restrict access for particular NETCONF users to
a preconfigured subset of all available NETCONF protocol operations
and content.
9.2. Regarding the "ietf-netconf-resolve-system" YANG Module
The YANG module defined in this document extends the base operations
for NETCONF [RFC6241] and [RFC8526]. The lowest NETCONF layer is the
secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
The Network Configuration Access Control Model (NACM) [RFC8341]
provides the means to restrict access for particular NETCONF users to
a preconfigured subset of all available NETCONF protocol operations
and content.
The security considerations for the base NETCONF protocol operations
(see Section 9 of [RFC6241] apply to the new extended RPC operations
defined in this document.
10. Contributors
Kent Watsen
Watsen Networks
Email: kent+ietf@watsen.net
Jan Lindblad
Cisco Systems
Email: jlindbla@cisco.com
Chongfeng Xie
China Telecom
Beijing
China
Email: xiechf@chinatelecom.cn
Jason Sterne
Nokia
Email: jason.sterne@nokia.com
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Acknowledgements
Thanks to Robert Wilton, Balazs Lengyel, Andy Bierman, Juergen
Schoenwaelder, Alex Clemm, Martin Bjorklund, Timothy Carey for
reviewing, and providing important input to, this document.
References
Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
[RFC8526] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "NETCONF Extensions to Support the Network
Management Datastore Architecture", RFC 8526,
DOI 10.17487/RFC8526, March 2019,
<https://www.rfc-editor.org/info/rfc8526>.
Informative References
[I-D.ma-netmod-immutable-flag]
Ma, Q., Wu, Q., Lengyel, B., and H. Li, "YANG Extension
and Metadata Annotation for Immutable Flag", Work in
Progress, Internet-Draft, draft-ma-netmod-immutable-flag-
04, 20 October 2022, <https://www.ietf.org/archive/id/
draft-ma-netmod-immutable-flag-04.txt>.
[RFC7317] Bierman, A. and M. Bjorklund, "A YANG Data Model for
System Management", RFC 7317, DOI 10.17487/RFC7317, August
2014, <https://www.rfc-editor.org/info/rfc7317>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8407] Bierman, A., "Guidelines for Authors and Reviewers of
Documents Containing YANG Data Models", BCP 216, RFC 8407,
DOI 10.17487/RFC8407, October 2018,
<https://www.rfc-editor.org/info/rfc8407>.
[RFC8525] Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K.,
and R. Wilton, "YANG Library", RFC 8525,
DOI 10.17487/RFC8525, March 2019,
<https://www.rfc-editor.org/info/rfc8525>.
[RFC8808] Wu, Q., Lengyel, B., and Y. Niu, "A YANG Data Model for
Factory Default Settings", RFC 8808, DOI 10.17487/RFC8808,
August 2020, <https://www.rfc-editor.org/info/rfc8808>.
Appendix A. Key Use Cases
Following provides three use cases related to system-defined
configuration lifecycle management. The simple interface data model
defined in Appendix C.3 of [RFC8342] is used. For each use case,
snippets of <running>, <system>, <intended> and <operational> are
shown.
A.1. Device Powers On
<running>:
No configuration for "lo0" appears in <running>;
<system>:
<interfaces>
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
</interfaces>
<intended>:
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<interfaces>
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
</interfaces>
<operational>:
<interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:system">
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
</interfaces>
A.2. Client Commits Configuration
If a client creates an interface "et-0/0/0" but the interface does
not physically exist at this point:
<running>:
<interfaces>
<interface>
<name>et-0/0/0</name>
<description>Test interface</description>
</interface>
</interfaces>
<system>:
<interfaces>
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
</interfaces>
<intended>:
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<interfaces>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
<interface>
<name>et-0/0/0</name>
<description>Test interface</description>
</interface>
<interface>
</interfaces>
<operational>:
<interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<interface or:origin="or:system">
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
</interfaces>
A.3. Operator Installs Card into a Chassis
<running>:
<interfaces>
<interface>
<name>et-0/0/0</name>
<description>Test interface</description>
</interface>
</interfaces>
<system>:
<interfaces>
<interface>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
<interface>
<name>et-0/0/0</name>
<mtu>1500</mtu>
</interface>
</interfaces>
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<intended>:
<interfaces>
<name>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
<interface>
<name>et-0/0/0</name>
<description>Test interface</description>
<mtu>1500</mtu>
</interface>
<interface>
</interfaces>
<operational>:
<interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<interface or:origin="or:system">
<name or:origin>lo0</name>
<ip-address>127.0.0.1</ip-address>
<ip-address>::1</ip-address>
</interface>
<interface>
<name>et-0/0/0</name>
<description>Test interface</description>
<mtu or:origin="or:system">1500</mtu>
</interface>
<interface>
</interfaces>
Appendix B. Changes between Revisions
v03 - v04
* Clarify the "should not" statement;
* Editorial changes, like avoid using "object";
v02 - v03
* Define a RESTCONF capability URI for "resolve-system" RESTCONF
query parameter;
* Augment <copy-config> RPC operation to support "resolve-system"
for input parameter;
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* Editorial changes for clarification and explanation. E.g.,
definition of system configuration, is <system> always valid?
Will the update of <system> be reflected into <running>? Clarify
"read-only to clients" and "modifying system configuration", non-
deletable system configuration, etc
v00 - v02
* Remove the "with-system" parameter to retrieve <running> with
system configuration merged in.
* Add a new parameter named "resolve-system" to allow the server to
populate referenced system configuration into <running>
automatically in order to make <running> valid.
* Usage examples refinement.
v02 - v00
* Restructure the document content based on input in the system
defined configuration interim meeting.
* Updates NMDA to define a read-only conventional configuration
datastore called "system".
* Retrieval of implicit hidden system configuration via <get><get-
config> with "with-system" parameter to support non-NMDA servers.
* Provide system defined configuration classification.
* Define Static Characteristics and dynamic behavior for system
defined configuration.
* Separate "ietf-system-datastore" Module from "ietf-netconf-with-
system" Module.
* Provide usage examples for dynamic behaviors.
* Provide usage examples for two YANG modules.
* Provide three use cases related to system-defined configuration
lifecycle management.
* Classify the relation with <factory-default>.
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Appendix C. Open Issues tracking
* Should the "with-origin" parameter be supported for <intended>?
Authors' Addresses
Qiufang Ma (editor)
Huawei
101 Software Avenue, Yuhua District
Nanjing
Jiangsu, 210012
China
Email: maqiufang1@huawei.com
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing
Jiangsu, 210012
China
Email: bill.wu@huawei.com
Feng Chong
Huawei
101 Software Avenue, Yuhua District
Nanjing
Jiangsu, 210012
China
Email: frank.fengchong@huawei.com
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