System-defined Configuration
draft-ietf-netmod-system-config-04
The information below is for an old version of the document.
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|---|---|---|---|
| Authors | Qiufang Ma , Qin Wu , Chong Feng | ||
| Last updated | 2023-11-05 (Latest revision 2023-10-19) | ||
| Replaces | draft-ma-netmod-with-system | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-netmod-system-config-04
NETMOD Q. Ma, Ed.
Internet-Draft Q. Wu
Updates: 8342, 6241, 8526, 8040 (if approved) Huawei
Intended status: Standards Track C. Feng
Expires: 8 May 2024 5 November 2023
System-defined Configuration
draft-ietf-netmod-system-config-04
Abstract
This document describes how a management client and server handle
YANG-modeled configuration data that is defined by the server itself.
The system-defined configuration can be referenced (e.g. leafref) by
configuration explicitly created by a client.
The Network Management Datastore Architecture (NMDA) defined in RFC
8342 is updated with a read-only conventional configuration datastore
called "system" to hold system-defined configuration. As an
alternative to clients explicitly copying referenced system-defined
configuration into the target configuration datastore (e.g.,
<running>) so that the datastore is valid, a "resolve-system"
parameter is defined to allow the server acting as a "system client"
to copy referenced system-defined nodes automatically. This solution
enables clients manipulating the target configuration datastore
(e.g., <running>) to overlay (e.g., copy system configuration using
the same key value as in <system>) and reference nodes defined in
<system>, override values of configurations defined in <system>, and
configure descendant nodes of system-defined nodes.
This document updates RFC 8342, RFC 6241, RFC 8526 and RFC 8040.
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."
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This Internet-Draft will expire on 8 May 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 5
1.3. Updates to RFC 8342 . . . . . . . . . . . . . . . . . . . 6
1.4. Updates to RFC 6241 and RFC 8526 . . . . . . . . . . . . 6
1.5. Updates to RFC 8040 . . . . . . . . . . . . . . . . . . . 7
1.5.1. Query Parameter . . . . . . . . . . . . . . . . . . . 7
1.5.2. Query Parameter URI . . . . . . . . . . . . . . . . . 7
2. Kinds of System Configuration . . . . . . . . . . . . . . . . 7
2.1. Immediately-Active . . . . . . . . . . . . . . . . . . . 8
2.2. Conditionally-Active . . . . . . . . . . . . . . . . . . 8
2.3. Inactive-Until-Referenced . . . . . . . . . . . . . . . . 8
3. The System Configuration Datastore (<system>) . . . . . . . . 8
4. Static Characteristics of <system> . . . . . . . . . . . . . 9
4.1. Read-only to Clients . . . . . . . . . . . . . . . . . . 9
4.2. May Change via Software Upgrades or Resource Changes . . 10
4.3. No Impact to <operational> . . . . . . . . . . . . . . . 10
5. Dynamic Behavior . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Conceptual Model of Datastores . . . . . . . . . . . . . 10
5.2. Explicit Declaration of System Configuration . . . . . . 13
5.3. Servers Auto-configuring Referenced System Configuration
("resolve-system" parameter) . . . . . . . . . . . . . . 14
5.4. Modifying (Overriding) System Configuration . . . . . . . 15
5.5. Examples . . . . . . . . . . . . . . . . . . . . . . . . 16
5.5.1. Server Configuring of <running> Automatically . . . . 16
5.5.2. Declaring a System-defined Node in <running>
Explicitly . . . . . . . . . . . . . . . . . . . . . 21
5.5.3. Modifying a System-instantiated Leaf's Value . . . . 24
5.5.4. Configuring Descendant Nodes of a System-defined
Node . . . . . . . . . . . . . . . . . . . . . . . . 26
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6. The "ietf-system-datastore" Module . . . . . . . . . . . . . 27
6.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 28
6.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 28
6.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 29
7. The "ietf-netconf-resolve-system" Module . . . . . . . . . . 30
7.1. Data Model Overview . . . . . . . . . . . . . . . . . . . 31
7.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 32
7.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 35
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
8.1. The "IETF XML" Registry . . . . . . . . . . . . . . . . . 37
8.2. The "YANG Module Names" Registry . . . . . . . . . . . . 38
8.3. NETCONF Capability URN Registry . . . . . . . . . . . . . 38
8.4. RESTCONF Capability URN Registry . . . . . . . . . . . . 38
9. Security Considerations . . . . . . . . . . . . . . . . . . . 38
9.1. Regarding the "ietf-system-datastore" YANG Module . . . . 39
9.2. Regarding the "ietf-netconf-resolve-system" YANG
Module . . . . . . . . . . . . . . . . . . . . . . . . . 39
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 39
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 40
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Normative References . . . . . . . . . . . . . . . . . . . . . 40
Informative References . . . . . . . . . . . . . . . . . . . . 41
Appendix A. Key Use Cases . . . . . . . . . . . . . . . . . . . 43
A.1. Device Powers On . . . . . . . . . . . . . . . . . . . . 43
A.2. Client Commits Configuration . . . . . . . . . . . . . . 44
A.3. Operator Installs Card into a Chassis . . . . . . . . . . 45
Appendix B. Changes between Revisions . . . . . . . . . . . . . 46
Appendix C. Open Issues tracking . . . . . . . . . . . . . . . . 47
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 47
1. Introduction
The Network Management Datastore Architecture (NMDA) [RFC8342]
defines system configuration as the configuration that is supplied by
the device itself and appears in <operational> when it is in use
(Figure 2 in [RFC8342]).
However, there is a desire to enable a server to better structure and
expose the system configuration. NETCONF/RESTCONF clients can
benefit from a standard mechanism to retrieve what system
configuration is available on a server.
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Some servers allow the NETCONF/RESTCONF client to reference a system-
defined node which isn't present in the target datastore (e.g.,
<running>). The absence of the system configuration in the datastore
can render the datastore invalid from the perspective of a client or
offline tools (e.g., missing leafref targets). This document
describes several approaches to bring the datastore to a valid state
and ensuring that all referential integrity constraints are
satisfied.
Some servers allow the descendant nodes of system-defined
configuration to be configured or modified. For example, the system
configuration may contain an almost empty physical interface, while
the client needs to be able to add, modify, or remove a number of
descendant nodes. Some descendant nodes may not be modifiable (e.g.,
the interface "name" and "type" set by the system).
This document updates the Network Management Datastore Architecture
(NMDA) defined in RFC 8342 with a read-only conventional
configuration datastore called "system" to hold system-defined
configuration. As an alternative to clients explicitly copying
referenced system-defined configuration into the target configuration
datastore (e.g., <running>) so that the datastore is valid, a
"resolve-system" parameter is defined to allow the server acting as a
"system client" to copy referenced system-defined nodes
automatically. This solution enables clients manipulating the target
configuration datastore (e.g., <running>) to overlay (e.g., copy
system configuration using the same key value as in <system>) and
reference nodes defined in <system>, override values of
configurations defined in <system>, and configure descendant nodes of
system-defined nodes.
If a system-defined node is referenced, it refers to one of the
following cases throughout this document:
* It is present in a leafref "path" statement and referred as the
leafref value
* It is used as an "instance-identifier" type value
* It is present in an Xpath expression of "when" or "must"
constraints
* It is defined to satisfy the "mandatory" constraints
* It is defined to exactly satisfy the "min-element" constraints
Conformance to this document requires the NMDA servers to implement
the "ietf-system-datastore" YANG module (Section 6).
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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:
System configuration: Configuration that is provided by the system
itself. System configuration is present in the system
configuration datastore (regardless of being applied by the device
or referenced by other configuration nodes), and appears in the
intended configuration datastore. System configuration that is
considered active (according to the NMDA defined in RFC 8342)
appears in <operational> with origin="system". It is a different
and separate concept from factory default configuration defined in
RFC 8808 (which represents a preset initial configuration that is
used to initialize the configuration of a server).
System configuration datastore: A configuration datastore holding
configuration provided by the system itself. This datastore is
referred to as "<system>".
This document redefines the term "conventional configuration
datastore" in Section 3 of [RFC8342] 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.
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.
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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> are read-only to clients but may change
dynamically itself. <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.
Configuration in <system> is merged with the current configuration of
the device in <running> after the configuration transformations
(e.g., template expansion, removal of inactive configuration defined
in [RFC8342]) to create the contents of <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 and 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.
The 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 processing,
regardless of which target datastore it is.
NETCONF server that supports this parameter MUST advertise the
capability identifier:
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urn:ietf:params:netconf:capability:resolve-system:1.0
1.5. Updates to RFC 8040
This document extends Sections 4.8 and 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 |
| | PATCH | system configuration into <running> |
| | | automatically. This parameter can be |
| | | given in any order. |
+----------------+---------+-----------------------------------------+
Figure 1: RESTCONF "resolve-system" Query Parameter
1.5.2. Query Parameter URI
To enable a 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 defined in this
document: immediately-active system configuration, conditionally-
active system configuration, and inactive-until-referenced system
configuration.
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Active system configuration refers to configuration that is in use by
a device. As per definition of the operational state datastore in
[RFC8342], if system configuration is inactive, it should not appear
in <operational>. However, system configuration is present in
<system> once it is generated, regardless of whether it is active or
not.
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 loopback 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 a QoS feature is enabled, related 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 active until being referenced.
3. The System Configuration Datastore (<system>)
NMDA servers compliant with this document MUST implement a system
configuration datastore, and they SHOULD also implement <intended>.
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.
* Name: "system"
* YANG modules: all
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* 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 protocols such as NETCONF,
RESTCONF, but may change itself by upgrades and/or when resource-
conditions are met. The datastore can be read using the standard
network management protocols such as NETCONF and RESCTCONF.
* Origin: This document does not define any new origin identity when
it interacts with <intended> 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>. 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
configuration 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.
4. Static Characteristics of <system>
4.1. Read-only to Clients
The system 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 5.4).
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4.2. May Change via Software Upgrades or Resource Changes
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 a QoS feature is
enabled, QoS-related policies are created by the system.
If the system configuration gets changed, YANG notifications (e.g.,
"push-change-update" notification) [RFC6470][RFC8639][RFC8641] 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.
4.3. No Impact to <operational>
This work intends to have no impact to <operational>. System
configuration appears in <operational> with "origin=system". This
document 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.
5. Dynamic Behavior
5.1. Conceptual Model of Datastores
This document introduces a 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 active immediately,
but inactive-until-referenced system configuration only becomes
active if it is referenced by client-defined configuration. While
conditionally-active system configuration will only be created and
active 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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Configuration in <system> is merged with the current configuration of
the device in <running> after the configuration transformations
(e.g., template expansion, removal of inactive configuration defined
in [RFC8342]) to create the contents of <intended>, in which process,
the data node appearing 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
appearing 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>.
As a result, Figure 2 in Section 5 of RFC 8342 is updated with the
below conceptual model of datastores which incorporates the system
configuration datastore.
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+-------------+ +-----------+
| <candidate> | | <startup> |
| (ct, rw) |<---+ +--->| (ct, rw) |
+-------------+ | | +-----------+
| | | |
+-----------+ | +-----------+ |
| <system> | +-------->| <running> |<--------+
| (ct, ro) | | (ct, rw) |
+-----+-----+ +----+------+
| |
+--------+ +------+ // configuration transformations,
| | // e.g., removal of nodes marked
| | // as "inactive", expansion of
| | // templates
V V
+------------+
| <intended> | // subject to validation
| (ct, ro) |
+------------+
| // changes applied, subject to
| // local factors, e.g., missing
| // resources, delays
|
dynamic |
configuration | +-------- learned configuration
datastores -----+ | +-------- default configuration
| | |
v v v
+---------------+
| <operational> | <-- system state
| (ct + cf, ro) |
+---------------+
ct = config true; cf = config false
rw = read-write; ro = read-only
boxes denote named datastores
Figure 2: Architectural Model of Datastores
Servers MUST enforce that configuration references in <running> are
resolved within <running> 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.
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No matter how the referenced system configurations are copied into
<running>, the nodes copied into <running> would always be returned
as the result of a read of <running>, regardless if the client is
<system> aware.
Configuration defined in <system> is merged into <intended>. It is
also present in <operational> if it is in use by the device, even if
a client may delete the configuration which is copied from <system>
into <running>. For example, system initializes a value for a
particular leaf which is overridden by the client with a different
value in <running>. The client may delete that node in <running>, in
which case system-initialized value defined in <system> can be still
in use and appear in <operational>.
Applied system configuration regardless of explicitly or
automatically being copied into <running>, appears in <operational>
with origin="system".
Comment: this might need further discussion: should the
origin="system" be required for system configuration copied/pasted
into <running>?
Any deletable system-provided configuration that is populated as part
of <running> by the system at boot up, without being part of the
contents of a <startup> datastore, 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.
5.2. 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>.
The explicit configuration of system-defined nodes in the target
datastore (e.g., <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 but need the datastore to
be valid. The client can explicitly declare (i.e., configure in the
datastore like <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 datastore
appear valid.
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5.3. Servers Auto-configuring Referenced System Configuration
("resolve-system" parameter)
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, and the server supports this
capability, 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.
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 <running> valid.
There is no distinction between the configuration in the target
datastore (e.g., <running>) which is automatically configured by the
server and the one explicitly declared by the client, e.g., a read
back of the datastore (i.e., <get>, <get-config> or <get-data>
operation) returns automatically configured nodes. Note that even an
auto-configured node is allowed to be deleted from the target
datastore by the client, the operation request (e.g., <edit-config>)
may not succeed due to incomplete referential integrity, it is also
possible that the system automatically configures the deleted node
again to make configuration valid, when a "resolve-system" parameter
is carried.
Once copied into <running>, system-instantiated node will not be
removed or updated automatically even all references to it are
deleted or system configuration no longer appears in <system> due to
factors like system-controlled resources change (e.g., HW
unavailable). That said, servers MAY upgrade system configuration as
well as any copied system nodes in <running> when licensing change or
device upgrade.
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 to bring awareness to the
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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. An example of this
type of opt-in behavior can also be found in RFC 7317, which enables
a client to opt into its behavior using a "$0$" prefix (see
ianach:crypt-hash type defined in [RFC7317]).
Support for the "resolve-system" parameter is OPTIONAL. Servers not
supporting NMDA [RFC8342] MAY also implement this parameter without
implementing the system configuration datastore, which would only
eliminate the ability to expose the system configuration via protocol
operations. If a server implements <system>, referenced system
configuration is copied from <system> into the target datastore
(e.g., <running>) when the "resolve-system" parameter is used;
otherwise it is an implementation decision where to copy referenced
system configuration into the target datastore (e.g., <running>).
Implementation specifics are beyond the scope of this document,
however, due to the extra complexity brought by the "resolve-system"
parameter, clients should be aware that it would cost a reasonable
amount of time for the server to resolve reference, retrieve and copy
the referenced system configuration from <system>, which could take
multiple rounds since some errors may depend on the resolution of
previous ones. Clients need to ensure that connections are alive
during the server processing until a response is received.
5.4. Modifying (Overriding) System Configuration
In some cases, a server may allow some parts of system configuration
to be modified. 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.
For instance, descendant nodes in a system-defined list entry may be
modifiable or not, even if some system configuration has been copied
into <running> earlier. If a system node is non-modifiable, then
writing a different value for that node MUST return an error. The
immutability of system configuration is further defined in
[I-D.ma-netmod-immutable-flag].
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).
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5.5. Examples
This section shows some 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.
5.5.1. Server Configuring of <running> Automatically
In this subsection, the following fictional module is used:
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 active 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, and the server treats application "smtp" configuration as
"inactive-until-referenced", it does not appear in <operational> but
only in <system>.
5.5.2. 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".
5.5.3. 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>
5.5.4. 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>
6. The "ietf-system-datastore" Module
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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 configuration 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@2023-11-05.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 NETDOD (Network Modeling) Working Group";
contact
"WG Web: https://datatracker.ietf.org/wg/netmod/
WG List: 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:fengchonglly@gmail.com>";
description
"This module defines a new YANG identity that uses the
ds:datastore identity defined in [RFC8342].
Copyright (c) 2023 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 2023-11-05 {
description
"Initial version.";
reference
"RFC XXXX: System-defined Configuration";
}
identity system {
base ds:conventional;
description
"This read-only datastore contains the configuration
provided by the system itself.";
}
}
<CODE ENDS>
7. The "ietf-netconf-resolve-system" Module
This YANG module is optional to implement.
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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 server's
capabilities included in the <hello> message.
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}?
| +---w resolve-system? empty
+---x copy-config
| +---w input
| +---w target
| | +---w (config-target)
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| | +--:(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", <system> 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 response 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@2023-11-05.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: <https://datatracker.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:fengchonglly@gmail.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) 2023 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 2023-11-05 {
description
"Initial version.";
reference
"RFC XXXX: System-defined Configuration";
}
grouping resolve-system-grouping {
description
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"Define the resolve-system parameter grouping.";
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:edit-config/nc:input" {
description
"Allows the server to automatically configure
referenced system configuration to make configuration
valid.";
uses resolve-system-grouping;
}
augment "/nc:copy-config/nc:input" {
description
"Allows the server to automatically configure
referenced system configuration to make configuration
valid.";
uses resolve-system-grouping;
}
augment "/ncds:edit-data/ncds:input" {
description
"Allows the server to automatically configure
referenced system configuration to make configuration
valid.";
uses resolve-system-grouping;
}
}
<CODE ENDS>
8. IANA Considerations
8.1. The "IETF XML" Registry
This document registers two XML namespace URNs in the 'IETF XML
registry', following the format defined in [RFC3688].
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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
maintained by IANA: N
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
maintained by IANA: N
RFC: XXXX // RFC Ed.: replace XXXX and remove this comment
8.3. NETCONF Capability URN Registry
This document registers the following capability identifier URN in
the 'Network Configuration Protocol (NETCONF) Capability URNs'
registry:
urn:ietf:params:netconf:capability:resolve-system:1.0
8.4. 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
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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].
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
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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
Acknowledgements
The authors would like to thank for following for discussions and
providing input to this document (ordered by first name): Alex Clemm,
Andy Bierman, Balazs Lengyel, Juergen Schoenwaelder, Martin
Bjorklund, Mohamed Boucadair, Robert Wilton and Timothy Carey.
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>.
[RFC6470] Bierman, A., "Network Configuration Protocol (NETCONF)
Base Notifications", RFC 6470, DOI 10.17487/RFC6470,
February 2012, <https://www.rfc-editor.org/info/rfc6470>.
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[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>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[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>.
[RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard,
E., and A. Tripathy, "Subscription to YANG Notifications",
RFC 8639, DOI 10.17487/RFC8639, September 2019,
<https://www.rfc-editor.org/info/rfc8639>.
[RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications
for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
September 2019, <https://www.rfc-editor.org/info/rfc8641>.
Informative References
[I-D.ma-netmod-immutable-flag]
Ma, Q., Wu, Q., Lengyel, B., and H. Li, "YANG Metadata
Annotation for Immutable Flag", Work in Progress,
Internet-Draft, draft-ma-netmod-immutable-flag-09, 22
October 2023, <https://datatracker.ietf.org/doc/html/
draft-ma-netmod-immutable-flag-09>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
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[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[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>.
[RFC7952] Lhotka, L., "Defining and Using Metadata with YANG",
RFC 7952, DOI 10.17487/RFC7952, August 2016,
<https://www.rfc-editor.org/info/rfc7952>.
[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>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[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>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[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>.
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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>:
<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>
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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>:
<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>
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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>
<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>:
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<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
* Add some implementation consideration for "resolve-system"
parameter
* Define a NETCONF capability identifier for "resolve-system"
parameter so that the client can discover if it is supported by
the server.
* state servers may upgrade copied system configuration in <running>
as well during device upgrade or licensing change.
v02 - v03
* remove the merge mechanism related comments, as discussed in
https://github.com/netconf-wg/netconf-next/issues/19
* Editorial changes
v01 - v02
* Define referenced system configuration
* better clarify "resolve-system" parameter
* update Figure 2 in NMDA RFC
* Editorial changes
v00 - v01
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* Clarify why client's explicit copy is not preferred but cannot be
avoided if resolve-system parameter is not defined
* Clarify active system configuration
* Update the timing when the server's auto copy should be enforced
if a resolve-system parameter is used
* Editorial changes
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
Email: fengchongllly@gmail.com
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