NETCONF A. Bierman Internet-Draft Netconf Central Intended status: Standards Track B. Lengyel Expires: October 8, 2009 Ericsson April 06, 2009 With-defaults capability for NETCONF draft-ietf-netconf-with-defaults-01 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 October 8, 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). 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 NETCONF agent. Part of this data is not set by the NETCONF manager, Bierman & Lengyel Expires October 8, 2009 [Page 1] Internet-Draft with-defaults April 2009 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 . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Other default handling methods in the real world? . . . . 10 7.2. XSD needed? . . . . . . . . . . . . . . . . . . . . . . . 10 8. Appendix A - Change Log . . . . . . . . . . . . . . . . . . 11 8.1. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.2. -00 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 10. Normative References . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Bierman & Lengyel Expires October 8, 2009 [Page 2] Internet-Draft with-defaults April 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 October 8, 2009 [Page 3] Internet-Draft with-defaults April 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 October 8, 2009 [Page 4] Internet-Draft with-defaults April 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:1.0 The identifier MUST have a 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 listed in Section 2.1.1. The identifier MAY have another parameter: "supported". This indicates what other default handling methods does the agent support. The value of the parameter is a colon separated list of one or two supported methods. Possible methods are taken from the list in Section 2.1.1. Example: urn:ietf:params:netconf:capability:with-defaults:1.0?basic=report-all urn:ietf:params:netconf:capability:with-defaults:1.0?basic=report- all&supported=trim:explicit 2.4. New Operations None 2.5. Modifications to Existing Operations A new XML child 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 taken from the list in Section 2.1.1. The allowed values are restricted to the values that the device indicates support for in the with-defaults capability. Bierman & Lengyel Expires October 8, 2009 [Page 5] Internet-Draft with-defaults April 2009 If the element is not present, the agent follows its basic behavior as indicated by the capability identifier's parameter see Section 2.3. Affected operations: 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 'report-all', the mtu is returned not just for eth0 but also for eth1. Bierman & Lengyel Expires October 8, 2009 [Page 6] Internet-Draft with-defaults April 2009 report-all eth0 8192 eth1 1500 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. Bierman & Lengyel Expires October 8, 2009 [Page 7] Internet-Draft with-defaults April 2009 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. +---------------+---------------------------------------------------+ | 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 October 8, 2009 [Page 8] Internet-Draft with-defaults April 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 October 8, 2009 [Page 9] Internet-Draft with-defaults April 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? Bierman & Lengyel Expires October 8, 2009 [Page 10] Internet-Draft with-defaults April 2009 8. Appendix A - Change Log 8.1. 00-01 Changed value set of with-default capability and element Added version to URI 8.2. -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 October 8, 2009 [Page 11] Internet-Draft with-defaults April 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 October 8, 2009 [Page 12] Internet-Draft with-defaults April 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 October 8, 2009 [Page 13] Internet-Draft with-defaults April 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 October 8, 2009 [Page 14]