RFC 6241
Network Configuration Protocol (NETCONF)
Pages: 113
Proposed Standard
→ Errata
Obsoletes: 4741
Updated by: 7803 8526
Proposed Standard
→ Errata
Obsoletes: 4741
Updated by: 7803 8526
Part 1 of 5 – Pages 1 to 13
Internet Engineering Task Force (IETF) R. Enns, Ed. Request for Comments: 6241 Juniper Networks Obsoletes: 4741 M. Bjorklund, Ed. Category: Standards Track Tail-f Systems ISSN: 2070-1721 J. Schoenwaelder, Ed. Jacobs University A. Bierman, Ed. Brocade June 2011 Network Configuration Protocol (NETCONF)Abstract
The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6241.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7 1.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 8 1.3. Capabilities . . . . . . . . . . . . . . . . . . . . . . 10 1.4. Separation of Configuration and State Data . . . . . . . 10 2. Transport Protocol Requirements . . . . . . . . . . . . . . . 11 2.1. Connection-Oriented Operation . . . . . . . . . . . . . . 11 2.2. Authentication, Integrity, and Confidentiality . . . . . 12 2.3. Mandatory Transport Protocol . . . . . . . . . . . . . . 12 3. XML Considerations . . . . . . . . . . . . . . . . . . . . . 13 3.1. Namespace . . . . . . . . . . . . . . . . . . . . . . . . 13 3.2. Document Type Declarations . . . . . . . . . . . . . . . 13 4. RPC Model . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.1. <rpc> Element . . . . . . . . . . . . . . . . . . . . . . 13 4.2. <rpc-reply> Element . . . . . . . . . . . . . . . . . . . 15 4.3. <rpc-error> Element . . . . . . . . . . . . . . . . . . . 16 4.4. <ok> Element . . . . . . . . . . . . . . . . . . . . . . 19 4.5. Pipelining . . . . . . . . . . . . . . . . . . . . . . . 19 5. Configuration Model . . . . . . . . . . . . . . . . . . . . . 19 5.1. Configuration Datastores . . . . . . . . . . . . . . . . 19 5.2. Data Modeling . . . . . . . . . . . . . . . . . . . . . . 20 6. Subtree Filtering . . . . . . . . . . . . . . . . . . . . . . 20 6.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 20 6.2. Subtree Filter Components . . . . . . . . . . . . . . . . 21 6.2.1. Namespace Selection . . . . . . . . . . . . . . . . . 21 6.2.2. Attribute Match Expressions . . . . . . . . . . . . . 22 6.2.3. Containment Nodes . . . . . . . . . . . . . . . . . . 23 6.2.4. Selection Nodes . . . . . . . . . . . . . . . . . . . 23 6.2.5. Content Match Nodes . . . . . . . . . . . . . . . . . 24 6.3. Subtree Filter Processing . . . . . . . . . . . . . . . . 25 6.4. Subtree Filtering Examples . . . . . . . . . . . . . . . 26 6.4.1. No Filter . . . . . . . . . . . . . . . . . . . . . . 26 6.4.2. Empty Filter . . . . . . . . . . . . . . . . . . . . 26 6.4.3. Select the Entire <users> Subtree . . . . . . . . . . 27 6.4.4. Select All <name> Elements within the <users> Subtree . . . . . . . . . . . . . . . . . . . . . . . 29 6.4.5. One Specific <user> Entry . . . . . . . . . . . . . . 30 6.4.6. Specific Elements from a Specific <user> Entry . . . 31 6.4.7. Multiple Subtrees . . . . . . . . . . . . . . . . . . 32 6.4.8. Elements with Attribute Naming . . . . . . . . . . . 33 7. Protocol Operations . . . . . . . . . . . . . . . . . . . . . 35 7.1. <get-config> . . . . . . . . . . . . . . . . . . . . . . 35 7.2. <edit-config> . . . . . . . . . . . . . . . . . . . . . . 37 7.3. <copy-config> . . . . . . . . . . . . . . . . . . . . . . 43 7.4. <delete-config> . . . . . . . . . . . . . . . . . . . . . 44 7.5. <lock> . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.6. <unlock> . . . . . . . . . . . . . . . . . . . . . . . . 47
7.7. <get> . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.8. <close-session> . . . . . . . . . . . . . . . . . . . . . 49
7.9. <kill-session> . . . . . . . . . . . . . . . . . . . . . 50
8. Capabilities . . . . . . . . . . . . . . . . . . . . . . . . 51
8.1. Capabilities Exchange . . . . . . . . . . . . . . . . . . 51
8.2. Writable-Running Capability . . . . . . . . . . . . . . . 53
8.2.1. Description . . . . . . . . . . . . . . . . . . . . . 53
8.2.2. Dependencies . . . . . . . . . . . . . . . . . . . . 53
8.2.3. Capability Identifier . . . . . . . . . . . . . . . . 53
8.2.4. New Operations . . . . . . . . . . . . . . . . . . . 53
8.2.5. Modifications to Existing Operations . . . . . . . . 53
8.3. Candidate Configuration Capability . . . . . . . . . . . 53
8.3.1. Description . . . . . . . . . . . . . . . . . . . . . 53
8.3.2. Dependencies . . . . . . . . . . . . . . . . . . . . 54
8.3.3. Capability Identifier . . . . . . . . . . . . . . . . 54
8.3.4. New Operations . . . . . . . . . . . . . . . . . . . 54
8.3.5. Modifications to Existing Operations . . . . . . . . 56
8.4. Confirmed Commit Capability . . . . . . . . . . . . . . . 57
8.4.1. Description . . . . . . . . . . . . . . . . . . . . . 57
8.4.2. Dependencies . . . . . . . . . . . . . . . . . . . . 58
8.4.3. Capability Identifier . . . . . . . . . . . . . . . . 58
8.4.4. New Operations . . . . . . . . . . . . . . . . . . . 59
8.4.5. Modifications to Existing Operations . . . . . . . . 60
8.5. Rollback-on-Error Capability . . . . . . . . . . . . . . 61
8.5.1. Description . . . . . . . . . . . . . . . . . . . . . 61
8.5.2. Dependencies . . . . . . . . . . . . . . . . . . . . 62
8.5.3. Capability Identifier . . . . . . . . . . . . . . . . 62
8.5.4. New Operations . . . . . . . . . . . . . . . . . . . 62
8.5.5. Modifications to Existing Operations . . . . . . . . 62
8.6. Validate Capability . . . . . . . . . . . . . . . . . . . 63
8.6.1. Description . . . . . . . . . . . . . . . . . . . . . 63
8.6.2. Dependencies . . . . . . . . . . . . . . . . . . . . 63
8.6.3. Capability Identifier . . . . . . . . . . . . . . . . 63
8.6.4. New Operations . . . . . . . . . . . . . . . . . . . 63
8.6.5. Modifications to Existing Operations . . . . . . . . 64
8.7. Distinct Startup Capability . . . . . . . . . . . . . . . 64
8.7.1. Description . . . . . . . . . . . . . . . . . . . . . 64
8.7.2. Dependencies . . . . . . . . . . . . . . . . . . . . 65
8.7.3. Capability Identifier . . . . . . . . . . . . . . . . 65
8.7.4. New Operations . . . . . . . . . . . . . . . . . . . 65
8.7.5. Modifications to Existing Operations . . . . . . . . 65
8.8. URL Capability . . . . . . . . . . . . . . . . . . . . . 66
8.8.1. Description . . . . . . . . . . . . . . . . . . . . . 66
8.8.2. Dependencies . . . . . . . . . . . . . . . . . . . . 66
8.8.3. Capability Identifier . . . . . . . . . . . . . . . . 66
8.8.4. New Operations . . . . . . . . . . . . . . . . . . . 66
8.8.5. Modifications to Existing Operations . . . . . . . . 66
8.9. XPath Capability . . . . . . . . . . . . . . . . . . . . 67
8.9.1. Description . . . . . . . . . . . . . . . . . . . . . 67
8.9.2. Dependencies . . . . . . . . . . . . . . . . . . . . 68
8.9.3. Capability Identifier . . . . . . . . . . . . . . . . 68
8.9.4. New Operations . . . . . . . . . . . . . . . . . . . 68
8.9.5. Modifications to Existing Operations . . . . . . . . 68
9. Security Considerations . . . . . . . . . . . . . . . . . . . 69
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 71
10.1. NETCONF XML Namespace . . . . . . . . . . . . . . . . . . 71
10.2. NETCONF XML Schema . . . . . . . . . . . . . . . . . . . 71
10.3. NETCONF YANG Module . . . . . . . . . . . . . . . . . . . 72
10.4. NETCONF Capability URNs . . . . . . . . . . . . . . . . . 72
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 73
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 73
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 74
13.1. Normative References . . . . . . . . . . . . . . . . . . 74
13.2. Informative References . . . . . . . . . . . . . . . . . 75
Appendix A. NETCONF Error List . . . . . . . . . . . . . . . . . 76
Appendix B. XML Schema for NETCONF Messages Layer . . . . . . . 80
Appendix C. YANG Module for NETCONF Protocol Operations . . . . 85
Appendix D. Capability Template . . . . . . . . . . . . . . . . 105
D.1. capability-name (template) . . . . . . . . . . . . . . . 105
D.1.1. Overview . . . . . . . . . . . . . . . . . . . . . . 105
D.1.2. Dependencies . . . . . . . . . . . . . . . . . . . . 105
D.1.3. Capability Identifier . . . . . . . . . . . . . . . . 105
D.1.4. New Operations . . . . . . . . . . . . . . . . . . . 105
D.1.5. Modifications to Existing Operations . . . . . . . . 105
D.1.6. Interactions with Other Capabilities . . . . . . . . 105
Appendix E. Configuring Multiple Devices with NETCONF . . . . . 106
E.1. Operations on Individual Devices . . . . . . . . . . . . 106
E.1.1. Acquiring the Configuration Lock . . . . . . . . . . 106
E.1.2. Checkpointing the Running Configuration . . . . . . . 107
E.1.3. Loading and Validating the Incoming Configuration . . 108
E.1.4. Changing the Running Configuration . . . . . . . . . 108
E.1.5. Testing the New Configuration . . . . . . . . . . . . 109
E.1.6. Making the Change Permanent . . . . . . . . . . . . . 109
E.1.7. Releasing the Configuration Lock . . . . . . . . . . 110
E.2. Operations on Multiple Devices . . . . . . . . . . . . . 111
Appendix F. Changes from RFC 4741 . . . . . . . . . . . . . . . 112
1. Introduction
The NETCONF protocol defines a simple mechanism through which a network device can be managed, configuration data information can be retrieved, and new configuration data can be uploaded and manipulated. The protocol allows the device to expose a full, formal application programming interface (API). Applications can use this straightforward API to send and receive full and partial configuration data sets. The NETCONF protocol uses a remote procedure call (RPC) paradigm. A client encodes an RPC in XML [W3C.REC-xml-20001006] and sends it to a server using a secure, connection-oriented session. The server responds with a reply encoded in XML. The contents of both the request and the response are fully described in XML DTDs or XML schemas, or both, allowing both parties to recognize the syntax constraints imposed on the exchange. A key aspect of NETCONF is that it allows the functionality of the management protocol to closely mirror the native functionality of the device. This reduces implementation costs and allows timely access to new features. In addition, applications can access both the syntactic and semantic content of the device's native user interface. NETCONF allows a client to discover the set of protocol extensions supported by a server. These "capabilities" permit the client to adjust its behavior to take advantage of the features exposed by the device. The capability definitions can be easily extended in a noncentralized manner. Standard and non-standard capabilities can be defined with semantic and syntactic rigor. Capabilities are discussed in Section 8. The NETCONF protocol is a building block in a system of automated configuration. XML is the lingua franca of interchange, providing a flexible but fully specified encoding mechanism for hierarchical content. NETCONF can be used in concert with XML-based transformation technologies, such as XSLT [W3C.REC-xslt-19991116], to provide a system for automated generation of full and partial configurations. The system can query one or more databases for data about networking topologies, links, policies, customers, and services. This data can be transformed using one or more XSLT scripts from a task-oriented, vendor-independent data schema into a form that is specific to the vendor, product, operating system, and software release. The resulting data can be passed to the device using the NETCONF protocol.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].1.1. Terminology
o candidate configuration datastore: A configuration datastore that can be manipulated without impacting the device's current configuration and that can be committed to the running configuration datastore. Not all devices support a candidate configuration datastore. o capability: A functionality that supplements the base NETCONF specification. o client: Invokes protocol operations on a server. In addition, a client can subscribe to receive notifications from a server. o configuration data: The set of writable data that is required to transform a system from its initial default state into its current state. o datastore: A conceptual place to store and access information. A datastore might be implemented, for example, using files, a database, flash memory locations, or combinations thereof. o configuration datastore: The datastore holding the complete set of configuration data that is required to get a device from its initial default state into a desired operational state. o message: A protocol element sent over a session. Messages are well-formed XML documents. o notification: A server-initiated message indicating that a certain event has been recognized by the server. o protocol operation: A specific remote procedure call, as used within the NETCONF protocol. o remote procedure call (RPC): Realized by exchanging <rpc> and <rpc-reply> messages. o running configuration datastore: A configuration datastore holding the complete configuration currently active on the device. The running configuration datastore always exists. o server: Executes protocol operations invoked by a client. In addition, a server can send notifications to a client.
o session: Client and server exchange messages using a secure,
connection-oriented session.
o startup configuration datastore: The configuration datastore
holding the configuration loaded by the device when it boots.
Only present on devices that separate the startup configuration
datastore from the running configuration datastore.
o state data: The additional data on a system that is not
configuration data such as read-only status information and
collected statistics.
o user: The authenticated identity of the client. The authenticated
identity of a client is commonly referred to as the NETCONF
username.
1.2. Protocol Overview
NETCONF uses a simple RPC-based mechanism to facilitate communication
between a client and a server. The client can be a script or
application typically running as part of a network manager. The
server is typically a network device. The terms "device" and
"server" are used interchangeably in this document, as are "client"
and "application".
A NETCONF session is the logical connection between a network
administrator or network configuration application and a network
device. A device MUST support at least one NETCONF session and
SHOULD support multiple sessions. Global configuration attributes
can be changed during any authorized session, and the effects are
visible in all sessions. Session-specific attributes affect only the
session in which they are changed.
NETCONF can be conceptually partitioned into four layers as shown in
Figure 1.
Layer Example +-------------+ +-----------------+ +----------------+ (4) | Content | | Configuration | | Notification | | | | data | | data | +-------------+ +-----------------+ +----------------+ | | | +-------------+ +-----------------+ | (3) | Operations | | <edit-config> | | | | | | | +-------------+ +-----------------+ | | | | +-------------+ +-----------------+ +----------------+ (2) | Messages | | <rpc>, | | <notification> | | | | <rpc-reply> | | | +-------------+ +-----------------+ +----------------+ | | | +-------------+ +-----------------------------------------+ (1) | Secure | | SSH, TLS, BEEP/TLS, SOAP/HTTP/TLS, ... | | Transport | | | +-------------+ +-----------------------------------------+ Figure 1: NETCONF Protocol Layers (1) The Secure Transport layer provides a communication path between the client and server. NETCONF can be layered over any transport protocol that provides a set of basic requirements. Section 2 discusses these requirements. (2) The Messages layer provides a simple, transport-independent framing mechanism for encoding RPCs and notifications. Section 4 documents the RPC messages, and [RFC5717] documents notifications. (3) The Operations layer defines a set of base protocol operations invoked as RPC methods with XML-encoded parameters. Section 7 details the list of base protocol operations. (4) The Content layer is outside the scope of this document. It is expected that separate efforts to standardize NETCONF data models will be undertaken. The YANG data modeling language [RFC6020] has been developed for specifying NETCONF data models and protocol operations, covering the Operations and the Content layers of Figure 1.
1.3. Capabilities
A NETCONF capability is a set of functionality that supplements the base NETCONF specification. The capability is identified by a uniform resource identifier (URI) [RFC3986]. Capabilities augment the base operations of the device, describing both additional operations and the content allowed inside operations. The client can discover the server's capabilities and use any additional operations, parameters, and content defined by those capabilities. The capability definition might name one or more dependent capabilities. To support a capability, the server MUST support any capabilities upon which it depends. Section 8 defines the capabilities exchange that allows the client to discover the server's capabilities. Section 8 also lists the set of capabilities defined in this document. Additional capabilities can be defined at any time in external documents, allowing the set of capabilities to expand over time. Standards bodies can define standardized capabilities, and implementations can define proprietary ones. A capability URI MUST sufficiently distinguish the naming authority to avoid naming collisions.1.4. Separation of Configuration and State Data
The information that can be retrieved from a running system is separated into two classes, configuration data and state data. Configuration data is the set of writable data that is required to transform a system from its initial default state into its current state. State data is the additional data on a system that is not configuration data such as read-only status information and collected statistics. When a device is performing configuration operations, a number of problems would arise if state data were included: o Comparisons of configuration data sets would be dominated by irrelevant entries such as different statistics. o Incoming data could contain nonsensical requests, such as attempts to write read-only data. o The data sets would be large. o Archived data could contain values for read-only data items, complicating the processing required to restore archived data.
To account for these issues, the NETCONF protocol recognizes the difference between configuration data and state data and provides operations for each. The <get-config> operation retrieves configuration data only, while the <get> operation retrieves configuration and state data. Note that the NETCONF protocol is focused on the information required to get the device into its desired running state. The inclusion of other important, persistent data is implementation specific. For example, user files and databases are not treated as configuration data by the NETCONF protocol. For example, if a local database of user authentication data is stored on the device, it is an implementation-dependent matter whether it is included in configuration data.2. Transport Protocol Requirements
NETCONF uses an RPC-based communication paradigm. A client sends a series of one or more RPC request messages, which cause the server to respond with a corresponding series of RPC reply messages. The NETCONF protocol can be layered on any transport protocol that provides the required set of functionality. It is not bound to any particular transport protocol, but allows a mapping to define how it can be implemented over any specific protocol. The transport protocol MUST provide a mechanism to indicate the session type (client or server) to the NETCONF protocol layer. This section details the characteristics that NETCONF requires from the underlying transport protocol.2.1. Connection-Oriented Operation
NETCONF is connection-oriented, requiring a persistent connection between peers. This connection MUST provide reliable, sequenced data delivery. NETCONF connections are long-lived, persisting between protocol operations. In addition, resources requested from the server for a particular connection MUST be automatically released when the connection closes, making failure recovery simpler and more robust. For example, when a lock is acquired by a client, the lock persists until either it is explicitly released or the server determines that the connection has been terminated. If a connection is terminated while the client holds a lock, the server can perform any appropriate recovery. The <lock> operation is further discussed in Section 7.5.
2.2. Authentication, Integrity, and Confidentiality
NETCONF connections MUST provide authentication, data integrity, confidentiality, and replay protection. NETCONF depends on the transport protocol for this capability. A NETCONF peer assumes that appropriate levels of security and confidentiality are provided independently of this document. For example, connections could be encrypted using Transport Layer Security (TLS) [RFC5246] or Secure Shell (SSH) [RFC4251], depending on the underlying protocol. NETCONF connections MUST be authenticated. The transport protocol is responsible for authentication of the server to the client and authentication of the client to the server. A NETCONF peer assumes that the connection's authentication information has been validated by the underlying transport protocol using sufficiently trustworthy mechanisms and that the peer's identity has been sufficiently proven. One goal of NETCONF is to provide a programmatic interface to the device that closely follows the functionality of the device's native interface. Therefore, it is expected that the underlying protocol uses existing authentication mechanisms available on the device. For example, a NETCONF server on a device that supports RADIUS [RFC2865] might allow the use of RADIUS to authenticate NETCONF sessions. The authentication process MUST result in an authenticated client identity whose permissions are known to the server. The authenticated identity of a client is commonly referred to as the NETCONF username. The username is a string of characters that match the "Char" production from Section 2.2 of [W3C.REC-xml-20001006]. The algorithm used to derive the username is transport protocol specific and in addition specific to the authentication mechanism used by the transport protocol. The transport protocol MUST provide a username to be used by the other NETCONF layers. The access permissions of a given client, identified by its NETCONF username, are part of the configuration of the NETCONF server. These permissions MUST be enforced during the remainder of the NETCONF session. The details of how access control is configured is outside the scope of this document.2.3. Mandatory Transport Protocol
A NETCONF implementation MUST support the SSH transport protocol mapping [RFC6242].
3. XML Considerations
XML serves as the encoding format for NETCONF, allowing complex hierarchical data to be expressed in a text format that can be read, saved, and manipulated with both traditional text tools and tools specific to XML. All NETCONF messages MUST be well-formed XML, encoded in UTF-8 [RFC3629]. If a peer receives an <rpc> message that is not well- formed XML or not encoded in UTF-8, it SHOULD reply with a "malformed-message" error. If a reply cannot be sent for any reason, the server MUST terminate the session. A NETCONF message MAY begin with an XML declaration (see Section 2.8 of [W3C.REC-xml-20001006]). This section discusses a small number of XML-related considerations pertaining to NETCONF.3.1. Namespace
All NETCONF protocol elements are defined in the following namespace: urn:ietf:params:xml:ns:netconf:base:1.0 NETCONF capability names MUST be URIs [RFC3986]. NETCONF capabilities are discussed in Section 8.3.2. Document Type Declarations
Document type declarations (see Section 2.8 of [W3C.REC-xml-20001006]) MUST NOT appear in NETCONF content.
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