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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (April 06, 2009) is 5498 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4741 (Obsoleted by RFC 6241) Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETCONF A. Bierman 3 Internet-Draft Netconf Central 4 Intended status: Standards Track B. Lengyel 5 Expires: October 8, 2009 Ericsson 6 April 06, 2009 8 With-defaults capability for NETCONF 9 draft-ietf-netconf-with-defaults-01 11 Status of this Memo 13 This Internet-Draft is submitted to IETF in full conformance with the 14 provisions of BCP 78 and BCP 79. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt. 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 This Internet-Draft will expire on October 8, 2009. 34 Copyright Notice 36 Copyright (c) 2009 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents in effect on the date of 41 publication of this document (http://trustee.ietf.org/license-info). 42 Please review these documents carefully, as they describe your rights 43 and restrictions with respect to this document. 45 Abstract 47 The NETCONF protocol defines ways to read configuration data from a 48 NETCONF agent. Part of this data is not set by the NETCONF manager, 49 but rather a default value is used. In many situations the NETCONF 50 manager has a priori knowledge about default data, so the NETCONF 51 agent does not need to send it to the manager. In other situations 52 the NETCONF manger will need this data as part of the NETCONF messages. This document defines a capability-based extension 54 to the NETCONF protocol that allows the NETCONF manager to control 55 whether default values are part of NETCONF messages. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 61 1.1.1. Requirements Notation . . . . . . . . . . . . . . . . 3 62 1.1.2. NETCONF Terms . . . . . . . . . . . . . . . . . . . . 3 63 2. With-defaults Capability . . . . . . . . . . . . . . . . . . . 4 64 2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 2.1.1. Basic handling of default data . . . . . . . . . . . . 4 66 2.2. Dependencies . . . . . . . . . . . . . . . . . . . . . . . 5 67 2.3. Capability Identifier . . . . . . . . . . . . . . . . . . 5 68 2.4. New Operations . . . . . . . . . . . . . . . . . . . . . . 5 69 2.5. Modifications to Existing Operations . . . . . . . . . . . 5 70 3. Interactions with Other Capabilities . . . . . . . . . . . . . 7 71 4. Data Model XSD . . . . . . . . . . . . . . . . . . . . . . . . 7 72 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 73 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 74 7. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 10 75 7.1. Other default handling methods in the real world? . . . . 10 76 7.2. XSD needed? . . . . . . . . . . . . . . . . . . . . . . . 10 77 8. Appendix A - Change Log . . . . . . . . . . . . . . . . . . 11 78 8.1. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 11 79 8.2. -00 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 80 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 81 10. Normative References . . . . . . . . . . . . . . . . . . . . . 13 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 84 1. Introduction 86 The NETCONF protocol defines ways to read configuration data from a 87 NETCONF agent. Part of this data is not set by the NETCONF manager, 88 but rather a default value is used. In many situations the NETCONF 89 manager has a priori knowledge about default data, so the NETCONF 90 agent does not need to send it to the manager. A priori knowledge 91 can be e.g. a document formally describing the data models supported 92 by the NETCONF agent. 94 A networking device may have a large number of default values. Often 95 the default values are not interesting or specifically defined with a 96 "reasonable" value, so that the management user does not have to 97 handle them. For these reasons it is quite common for networking 98 devices to suppress the output of parameters having the default 99 value. 101 However there are use-cases when a NETCONF manager will need the 102 default data from the node: 104 o Documentation about default values can be unreliable or 105 unavailable. 106 o Some management applications might not have the capabilities to 107 correctly parse and interpret formal data models. 108 o Human users might want to understand the received data without 109 consultation of the documentation. 111 In all theses cases the NETCONF manager will need default data as 112 part of the NETCONF messages. 114 This document defines a capability-based extension to the NETCONF 115 protocol that allows the NETCONF manager to control whether default 116 data is part of NETCONF messages. 118 1.1. Terminology 120 1.1.1. Requirements Notation 122 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 123 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 124 document are to be interpreted as described in [RFC2119]. 126 1.1.2. NETCONF Terms 128 o Default data: Data that is set or used by the NETCONF agent 129 whenever the NETCONF manager does not provide a specific value for 130 the relevant data item. Default values are often specified in 131 documents describing the data models supported by the NETCONF 132 agent. In the context of this document only configuration data is 133 considered, state data is excluded. 135 o Explicitly set default data: Data that is explicitly set by the 136 NETCONF manager to it's default value. Some agents MIGHT treat 137 explicitly set default data as simple default data, as they MIGHT 138 not be able to differentiate between them. 140 In addition the following terms are defined in RFC 4741 and are not 141 redefined here: 142 o agent 143 o application 144 o manager 145 o operation 146 o RPC 147 o RPC request 148 o RPC response 150 2. With-defaults Capability 152 2.1. Overview 154 The :with-defaults capability indicates that the NETCONF agent makes 155 it possible for the NETCONF manager to control whether default data 156 is part of NETCONF messages. The capability only affects 157 configuration data not state data. Sending of default data is 158 controlled for each individual operation separately. The NETCONF 159 agent MUST also indicate its basic behavior, whether it sends default 160 data in the absence of any specific request from the NETCONF manager. 162 2.1.1. Basic handling of default data 164 It is not defined in [RFC4741], whether default data is part of the 165 datastore/data model, or if it is meta data, that influences the 166 behavior of the NETCONF server, device but is not actually part of 167 the datastore. This document intentionally avoids deciding this 168 question. 170 As a consequence of this issue, NETCONF servers that do not implement 171 the :with-defaults capability may or may not return default data in 172 NETCONF messages. 174 Different NETCONF agents report default data in different ways. This 175 document specifies the following three basic methods: 177 o Report all: All default data is always reported. 178 o Trim: Values are not reported if they match the default. 179 o Explicit: Report values if they are explicitly set. 181 2.2. Dependencies 183 None 185 2.3. Capability Identifier 187 urn:ietf:params:netconf:capability:with-defaults:1.0 189 The identifier MUST have a parameter: "basic". This indicates how 190 the agent reports default data in messages, in the case 191 the manager does not specify the required behavior in the 192 request. The allowed values of this parameter are report-all, trim, 193 explicit as listed in Section 2.1.1. 195 The identifier MAY have another parameter: "supported". This 196 indicates what other default handling methods does the agent support. 197 The value of the parameter is a colon separated list of one or two 198 supported methods. Possible methods are taken from the list in 199 Section 2.1.1. 201 Example: 203 urn:ietf:params:netconf:capability:with-defaults:1.0?basic=report-all 205 urn:ietf:params:netconf:capability:with-defaults:1.0?basic=report- 206 all&supported=trim:explicit 208 2.4. New Operations 210 None 212 2.5. Modifications to Existing Operations 214 A new XML child element is added to the 'method-name' 215 element. This is the element that indicates the type of the 216 operation e.g. , or . If the element is present, it controls the reporting of default 218 data. The agent MUST return default data in the NETCONF 219 messages according to the value of the element. 221 Allowed values of the with-defaults element are taken from the list 222 in Section 2.1.1. The allowed values are restricted to the values 223 that the device indicates support for in the with-defaults 224 capability. 226 If the element is not present, the agent follows its 227 basic behavior as indicated by the capability identifier's parameter 228 see Section 2.3. 230 Affected operations: 231 o 232 o 233 o 235 Other operations that return configuration data SHOULD also handle 236 default data according to the rules set in this document, and 237 explicitly state this in their documentation. If this is not 238 specified in the document defining the respective operation, the 239 default handling rules described herein do not affect these 240 operations. 242 The following example shows a operation which is using the 243 'with-defaults' element. The manager is retrieving the 'interfaces' 244 object, defined in the example.com data model. (In this simple 245 example, the 'name' field is defined as the key, and the 'mtu' field 246 is the only other data in the element). The default 247 value of mtu is '1500'. The basic default handling for the agent is 248 "trim". As the 'with-defaults' element has the value 'report-all', 249 the mtu is returned not just for eth0 but also for eth1. 251 253 254 report-all 255 256 257 258 259 261 263 264 265 266 eth0 267 8192 268 269 270 eth1 271 1500 272 273 274 275 277 Figure 1 279 3. Interactions with Other Capabilities 281 None 283 4. Data Model XSD 285 This section contains an XML Schema Definition 286 [W3C.REC-xmlschema-2-20041028] which defines the XML syntax 287 associated for the with-defaults XML element. 289 290 296 297 298 Schema defining the with-defaults element. 300 Organization: "IETF NETCONF Working Group" 301 Contact Info: balazs.lengyel@ericsson.com 302 303 305 306 307 308 309 310 311 312 313 315 317 5. IANA Considerations 319 This document registers two URIs for the NETCONF XML namespace in the 320 IETF XML registry [RFC3688]. Note that the capability URN is 321 compliant to [RFC4741] section 10.3. 323 +---------------+---------------------------------------------------+ 324 | Index | Capability Identifier | 325 +---------------+---------------------------------------------------+ 326 | :with-default | urn:ietf:params:netconf:capability:with-defaults: | 327 | s | 1.0 | 328 +---------------+---------------------------------------------------+ 330 URI: urn:ietf:params:xml:ns:netconf:with-defaults:1.0 332 Registrant Contact: The IESG. 334 XML: N/A, the requested URI is an XML namespace. 336 6. Security Considerations 338 This document defines a minor extension to existing NETCONF protocol 339 operations. it does not introduce any new or increased security risks 340 into the management system. 342 The 'with-defaults' capability provides manager controls over the 343 retrieval of particular types of XML data from a configuration 344 database. They only suppress data that can already be retrieved with 345 the standard protocol operations, and do not add any data to the 346 configuration database. 348 7. Open Issues 350 7.1. Other default handling methods in the real world? 352 Are there any other basic default handling methods out there we need 353 to include? 355 7.2. XSD needed? 357 Is the XSD needed? Does it add any value, any clarity to the 358 document? 360 8. Appendix A - Change Log 362 8.1. 00-01 364 Changed value set of with-default capability and element 366 Added version to URI 368 8.2. -00 370 Created from draft-bierman-netconf-with-defaults-01.txt 372 It was decided by the NETCONF mailing list, that with-defaults should 373 be a sub-element of each affected operation. While this violates the 374 XSD of RFC4741 this is acceptable and follows the ideas behind 375 NETCONF and YANG. 377 Hopefully it will be clarified in the 4741bis RFC whether such 378 extensions are allowed. 380 9. Acknowledgements 382 Thanks to Martin Bjorklund, Sharon Chisholm, Phil Shafer, Juergen 383 Schoenwaelder and many other members of the NETCONF WG for providing 384 important input to this document. 386 10. Normative References 388 [W3C.REC-xmlschema-2-20041028] 389 Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes 390 Second Edition", World Wide Web Consortium 391 Recommendation REC-xmlschema-2-20041028, October 2004, 392 . 394 [RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741, 395 December 2006. 397 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 398 Requirement Levels", BCP 14, RFC 2119, March 1997. 400 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 401 January 2004. 403 Authors' Addresses 405 Andy Bierman 406 Netconf Central 407 Simi Valley, CA 408 USA 410 Email: andy@netconfcentral.com 412 Balazs Lengyel 413 Ericsson 414 Budapest, 415 Hungary 417 Email: balazs.lengyel@ericsson.com