NETCONF A. Bierman Internet-Draft Netconf Central Intended status: Standards Track B. Lengyel Expires: August 21, 2009 Ericsson February 17, 2009 With-defaults capability for NETCONF draft-ietf-netconf-with-defaults-00 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 21, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract The NETCONF protocol defines ways to read configuration data from a Bierman & Lengyel Expires August 21, 2009 [Page 1] Internet-Draft with-defaults February 2009 NETCONF agent. Part of this data is not set by the NETCONF manager, but rather a default value is used. In many situations the NETCONF manager has a priori knowledge about default data, so the NETCONF agent does not need to send it to the manager. In other situations the NETCONF manger will need this data as part of the NETCONF messages. This document defines a capability-based extension to the NETCONF protocol that allows the NETCONF manager to control whether default values are part of NETCONF messages. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1.1. Requirements Notation . . . . . . . . . . . . . . . . 3 1.1.2. NETCONF Terms . . . . . . . . . . . . . . . . . . . . 3 2. With-defaults Capability . . . . . . . . . . . . . . . . . . . 4 2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.1. Basic handling of default data . . . . . . . . . . . . 4 2.2. Dependencies . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Capability Identifier . . . . . . . . . . . . . . . . . . 5 2.4. New Operations . . . . . . . . . . . . . . . . . . . . . . 5 2.5. Modifications to Existing Operations . . . . . . . . . . . 5 3. Interactions with Other Capabilities . . . . . . . . . . . . . 7 4. Data Model XSD . . . . . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Other default handling methods in the real world? . . . . 10 7.2. XSD needed? . . . . . . . . . . . . . . . . . . . . . . . 10 7.3. Use the NETCONF namespace? . . . . . . . . . . . . . . . . 10 8. Appendix A - Change Log . . . . . . . . . . . . . . . . . . 11 8.1. -00 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 10. Normative References . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Bierman & Lengyel Expires August 21, 2009 [Page 2] Internet-Draft with-defaults February 2009 1. Introduction The NETCONF protocol defines ways to read configuration data from a NETCONF agent. Part of this data is not set by the NETCONF manager, but rather a default value is used. In many situations the NETCONF manager has a priori knowledge about default data, so the NETCONF agent does not need to send it to the manager. A priori knowledge can be e.g. a document formally describing the data models supported by the NETCONF agent. A networking device may have a large number of default values. Often the default values are not interesting or specifically defined with a "reasonable" value, so that the management user does not have to handle them. For these reasons it is quite common for networking devices to suppress the output of parameters having the default value. However there are use-cases when a NETCONF manager will need the default data from the node: o Documentation about default values can be unreliable or unavailable. o Some management applications might not have the capabilities to correctly parse and interpret formal data models. o Human users might want to understand the received data without consultation of the documentation. In all theses cases the NETCONF manager will need default data as part of the NETCONF messages. This document defines a capability-based extension to the NETCONF protocol that allows the NETCONF manager to control whether default data is part of NETCONF messages. 1.1. Terminology 1.1.1. Requirements Notation 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 [RFC2119]. 1.1.2. NETCONF Terms o Default data: Data that is set or used by the NETCONF agent whenever the NETCONF manager does not provide a specific value for the relevant data item. Default values are often specified in documents describing the data models supported by the NETCONF Bierman & Lengyel Expires August 21, 2009 [Page 3] Internet-Draft with-defaults February 2009 agent. In the context of this document only configuration data is considered, state data is excluded. o Explicitly set default data: Data that is explicitly set by the NETCONF manager to it's default value. Some agents MIGHT treat explicitly set default data as simple default data, as they MIGHT not be able to differentiate between them. In addition the following terms are defined in RFC 4741 and are not redefined here: o agent o application o manager o operation o RPC o RPC request o RPC response 2. With-defaults Capability 2.1. Overview The :with-defaults capability indicates that the NETCONF agent makes it possible for the NETCONF manager to control whether default data is part of NETCONF messages. The capability only affects configuration data not state data. Sending of default data is controlled for each individual operation separately. The NETCONF agent MUST also indicate its basic behavior, whether it sends default data in the absence of any specific request from the NETCONF manager. 2.1.1. Basic handling of default data It is not defined in [RFC4741], whether default data is part of the datastore/data model, or if it is meta data, that influences the behavior of the NETCONF server, device but is not actually part of the datastore. This document intentionally avoids deciding this question. As a consequence of this issue, NETCONF servers that do not implement the :with-defaults capability may or may not return default data in NETCONF messages. Different NETCONF agents report default data in different ways. This document specifies the following three basic methods: Bierman & Lengyel Expires August 21, 2009 [Page 4] Internet-Draft with-defaults February 2009 o Report all: All default data is always reported. o Trim: Values are not reported if they match the default. o Explicit: Report values if they are explicitly set. 2.2. Dependencies None 2.3. Capability Identifier urn:ietf:params:netconf:capability:with-defaults The identifier MUST have an additional parameter: "basic". This indicates how the agent reports default data in messages, in the case the manager does not specify the required behavior in the request. The allowed values of this parameter are report-all, trim, explicit as defined in Section 2.1.1. E.g.: urn:ietf:params:netconf:capability:with-defaults?basic=report-all 2.4. New Operations None 2.5. Modifications to Existing Operations A new XML element is added to the 'method-name' element. This is the element that indicates the type of the operation e.g. , or . If the element is present, it controls the reporting of default data. The agent MUST return default data in the NETCONF messages according to the value of the element. Allowed values of the with-defaults element are: o false: default data SHOULD NOT be returned. o true: all default data MUST be returned. If the element is not present, the agent follows its basic behavior as indicated by the capability identifier's parameter see Section 2.3. The 'with-defaults' element is defined in the namespace specified as the 'targetNamespace' in Section 4. However, an agent MUST accept it even if no namespace is used. Affected operations: Bierman & Lengyel Expires August 21, 2009 [Page 5] Internet-Draft with-defaults February 2009 o o o Other operations that return configuration data SHOULD also handle default data according to the rules set in this document, and explicitly state this in their documentation. If this is not specified in the document defining the respective operation, the default handling rules described herein do not affect these operations. The following example shows a operation which is using the 'with-defaults' element. The manager is retrieving the 'interfaces' object, defined in the example.com data model. (In this simple example, the 'name' field is defined as the key, and the 'mtu' field is the only other data in the element). The default value of mtu is '1500'. The basic default handling for the agent is "trim". As the 'with-defaults' element has the value 'true', the mtu is returned not just for eth0 but also for eth1. true eth0 8192 eth1 1500 Bierman & Lengyel Expires August 21, 2009 [Page 6] Internet-Draft with-defaults February 2009 Figure 1 3. Interactions with Other Capabilities None 4. Data Model XSD This section contains an XML Schema Definition [W3C.REC-xmlschema-2-20041028] which defines the XML syntax associated for the with-defaults XML element. Schema defining the with-defaults element. Organization: "IETF NETCONF Working Group" Contact Info: balazs.lengyel@ericsson.com 5. IANA Considerations This document registers two URIs for the NETCONF XML namespace in the IETF XML registry [RFC3688]. Note that the capability URN is compliant to [RFC4741] section 10.3. Bierman & Lengyel Expires August 21, 2009 [Page 7] Internet-Draft with-defaults February 2009 +---------------+---------------------------------------------------+ | Index | Capability Identifier | +---------------+---------------------------------------------------+ | :with-default | urn:ietf:params:netconf:capability:with-defaults: | | s | 1.0 | +---------------+---------------------------------------------------+ URI: urn:ietf:params:xml:ns:netconf:with-defaults:1.0 Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. Bierman & Lengyel Expires August 21, 2009 [Page 8] Internet-Draft with-defaults February 2009 6. Security Considerations This document defines a minor extension to existing NETCONF protocol operations. it does not introduce any new or increased security risks into the management system. The 'with-defaults' capability provides manager controls over the retrieval of particular types of XML data from a configuration database. They only suppress data that can already be retrieved with the standard protocol operations, and do not add any data to the configuration database. Bierman & Lengyel Expires August 21, 2009 [Page 9] Internet-Draft with-defaults February 2009 7. Open Issues 7.1. Other default handling methods in the real world? Are there any other basic default handling methods out there we need to include? 7.2. XSD needed? Is the XSD needed? Does it add any value, any clarity to the document? 7.3. Use the NETCONF namespace? Would it be possible to put the with-defaults element into the NETCONF namespace? Is the current statement: "However, an agent MUST accept it even if no namespace is used." acceptable? Bierman & Lengyel Expires August 21, 2009 [Page 10] Internet-Draft with-defaults February 2009 8. Appendix A - Change Log 8.1. -00 Created from draft-bierman-netconf-with-defaults-01.txt It was decided by the NETCONF mailing list, that with-defaults should be a sub-element of each affected operation. While this violates the XSD of RFC4741 this is acceptable and follows the ideas behind NETCONF and YANG. Hopefully it will be clarified in the 4741bis RFC whether such extensions are allowed. Bierman & Lengyel Expires August 21, 2009 [Page 11] Internet-Draft with-defaults February 2009 9. Acknowledgements Thanks to Martin Bjorklund, Sharon Chisholm, Phil Shafer, Juergen Schoenwaelder and many other members of the NETCONF WG for providing important input to this document. Bierman & Lengyel Expires August 21, 2009 [Page 12] Internet-Draft with-defaults February 2009 10. Normative References [W3C.REC-xmlschema-2-20041028] Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes Second Edition", World Wide Web Consortium Recommendation REC-xmlschema-2-20041028, October 2004, . [RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741, December 2006. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. Bierman & Lengyel Expires August 21, 2009 [Page 13] Internet-Draft with-defaults February 2009 Authors' Addresses Andy Bierman Netconf Central Simi Valley, CA USA Email: andy@netconfcentral.com Balazs Lengyel Ericsson Budapest, Hungary Email: balazs.lengyel@ericsson.com Bierman & Lengyel Expires August 21, 2009 [Page 14]