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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'I-D.rfernando-i2rs-yang-mods' is defined on line 375, but no explicit reference was found in the text == Unused Reference: 'RFC6242' is defined on line 388, but no explicit reference was found in the text == Outdated reference: A later version (-15) exists of draft-ietf-i2rs-architecture-05 == Outdated reference: A later version (-11) exists of draft-ietf-i2rs-traceability-02 == Outdated reference: A later version (-07) exists of draft-ietf-netmod-yang-metadata-00 ** Obsolete normative reference: RFC 6536 (Obsoleted by RFC 8341) Summary: 2 errors (**), 0 flaws (~~), 6 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force J. Haas 3 Internet-Draft Juniper Networks 4 Intended status: Informational May 26, 2015 5 Expires: November 27, 2015 7 I2RS Ephemeral State Requirements 8 draft-haas-i2rs-ephemeral-state-reqs-00 10 Abstract 12 This document covers requests to the netmod and netconf Working 13 Groups for functionality to support the ephemeral state requirements 14 to implement the I2RS architecture. 16 Status of This Memo 18 This Internet-Draft is submitted in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF). Note that other groups may also distribute 23 working documents as Internet-Drafts. The list of current Internet- 24 Drafts is at http://datatracker.ietf.org/drafts/current/. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 This Internet-Draft will expire on November 27, 2015. 33 Copyright Notice 35 Copyright (c) 2015 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents 40 (http://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. Code Components extracted from this document must 44 include Simplified BSD License text as described in Section 4.e of 45 the Trust Legal Provisions and are provided without warranty as 46 described in the Simplified BSD License. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 51 2. Ephemeral State Requirements . . . . . . . . . . . . . . . . 3 52 2.1. Persistence . . . . . . . . . . . . . . . . . . . . . . . 3 53 2.2. Constraints . . . . . . . . . . . . . . . . . . . . . . . 3 54 2.3. Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. Changes to YANG . . . . . . . . . . . . . . . . . . . . . . . 3 56 4. Changes to NETCONF . . . . . . . . . . . . . . . . . . . . . 4 57 5. Identity, Secondary-Identity Requirements; Priority 58 Requirements; Implications . . . . . . . . . . . . . . . . . 4 59 5.1. Identity Requirements . . . . . . . . . . . . . . . . . . 4 60 5.2. Priority Requirements . . . . . . . . . . . . . . . . . . 5 61 5.3. Representing I2RS Attributes in ephemeral 62 configuration state . . . . . . . . . . . . . . . . . . . 6 63 6. Subscriptions to Changed State Requirements . . . . . . . . . 6 64 7. Previously Considered Ideas . . . . . . . . . . . . . . . . . 7 65 7.1. A Separate Ephemeral Datastore . . . . . . . . . . . . . 7 66 7.2. Panes of Glass/Overlay . . . . . . . . . . . . . . . . . 7 67 8. Actions Required to Implement this Draft . . . . . . . . . . 8 68 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 69 10. Security Considerations . . . . . . . . . . . . . . . . . . . 8 70 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 71 12. Normative References . . . . . . . . . . . . . . . . . . . . 8 72 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9 74 1. Introduction 76 The Interface to the Routing System (I2RS) Working Group is chartered 77 with providing architecture and mechanisms to inject into and 78 retrieve information from the routing system. The I2RS Architecture 79 document [I-D.ietf-i2rs-architecture] abstractly documents a number 80 of requirements for implementing the I2RS requirements. 82 The I2RS Working Group has chosen to use the YANG data modeling 83 language [RFC6020] as the basis to implement its mechanisms. 85 Additionally, the I2RS Working group has chosen to use the NETCONF 86 [RFC6241] and its similar but lighter-weight relative RESTCONF 87 [I-D.bierman-netconf-restconf] as the protocols for carrying I2RS. 89 While YANG, NETCONF and RESTCONF are a good starting basis for I2RS, 90 there are some things needed from each of them in order for I2RS to 91 be implemented. 93 2. Ephemeral State Requirements 95 2.1. Persistence 97 I2RS requires ephemeral state; i.e. state that does not persist 98 across reboots. If state must be restored, it should be done solely 99 by replay actions from the I2RS client via the I2RS agent. 101 While at first glance this may seem equivalent to the writable- 102 running datastore in NETCONF, running-config can be copied to a 103 persistant data store, like startup config. I2RS ephemeral state 104 MUST NOT be persisted. 106 2.2. Constraints 108 Ephemeral state MAY refer to non-ephemeral state for purposes of 109 implementing constraints. The designer of ephemeral state modules 110 are advised that such constraints may impact the speed of processing 111 ephemeral state commits and should avoid them when speed is 112 essential. 114 Non-ephemeral state MUST NOT refer to ephemeral state for constraint 115 purposes; it SHALL be considered a validation error if it does. 117 2.3. Hierarchy 119 Similar to configuration state (config true, see [RFC6020], section 120 7.19.1), ephemeral state is not permitted to be configured underneath 121 nodes that are "config false" (state data). 123 Configuration of ephemeral state underneath "config true" is 124 permitted. This permits augmentation of configuration state with 125 ephemeral nodes. 127 Configuration of "config true" state underneath ephemeral state MUST 128 NOT be done. 130 State data, "config false", is permitted underneath ephemeral state. 131 (XXX JMH - should there be a requirement that such state data be part 132 of an ephemeral module and perhaps become similarly inaccessible if 133 the ephemeral module reboots?) 135 3. Changes to YANG 137 The YANG "config" keyword ([RFC6020], section 7.19.1) is extended to 138 support the keyword "ephemeral" in addition to "true" and "false". 139 "config ephemeral" declares the nodes underneath to be ephemeral 140 configuration. 142 4. Changes to NETCONF 144 A capability is registered declaring that the server supports 145 ephemeral configuration. E.g.: 147 :ephemeral-config 148 urn:ietf:params:netconf:capability:ephemeral-config:1.0 150 will normally return "config ephemeral" nodes as it is a 151 form of configuration. It is further extended to add a new 152 parameter, "filter-ephemeral". This parameter accepts the following 153 arguments: 155 o none (default): No filtering of persistent or ephemeral state is 156 done. 157 o ephemeral-only: Only nodes representing ephemeral state are 158 returned. 159 o exclude-ephemeral: Only persistent configuration is returned. 161 is similarly extended to support "filter-ephemeral". 163 When a is done, regardless of datastore, nodes that are 164 "config ephemeral" are excluded from the target output. 166 5. Identity, Secondary-Identity Requirements; Priority Requirements; 167 Implications 169 5.1. Identity Requirements 171 I2RS requires clients to have an identity. This identity will be 172 used by the Agent authentication mechanism over the appropriate 173 protocol. 175 I2RS also permits clients to have a secondary identity which may be 176 used for troubleshooting. This secondary identity is an opaque 177 value. [I-D.ietf-i2rs-traceability] provides an example of how the 178 secondary identity can be used for traceability. 180 The secondary identity is carried in the configuration operation 181 using a new parameter to . E.g.: 183 184 185 user1 186 187 188 189 190 191 192 Ethernet0/0 193 1500 194 195 196 197 198 200 "config ephemeral" nodes that are created or altered as part of the 201 config operation will carry the secondary-identity as read-only 202 metadata. 204 5.2. Priority Requirements 206 To support Multi-Headed Control, I2RS requires that there be a 207 decidable means of arbitrating the correct state of data when 208 multiple clients attempt to manipulate the same piece of data. This 209 is done via a priority mechanism with the highest priority winning. 210 This priority may vary on a per-node or sub-tree basis based for a 211 given identity. 213 This further implies that priority is an attribute that is stored in 214 the NETCONF Access Control Model [RFC6536] as part of a rule-list. 215 E.g.: 217 +--rw rule-list [name] 218 +--rw name string 219 +--rw group* union 220 +--rw rule [name] 221 +--rw name string 222 +--rw module-name? union 223 +--rw (rule-type)? 224 | +--:(protocol-operation) 225 | | +--rw rpc-name? union 226 | +--:(notification) 227 | | +--rw notification-name? union 228 | +--:(data-node) 229 | +--rw path node-instance-identifier 230 +--rw access-operations? union 231 +--rw action action-type 232 +--rw comment? string 233 +--rw i2rs:i2rs-priority i2rs-priority-type 235 Ephemeral configuration state nodes that are created or altered by 236 users that match a rule carrying i2rs-priority will have those nodes 237 annotated with metadata. Additionally, during commit processing, if 238 nodes are found where i2rs-priority is already present, and the 239 priority is better than the transaction's user's priority for that 240 node, the commit SHALL fail. An appropriate error should be returned 241 to the user stating the nodes where the user had insufficient 242 priority to override the state. 244 5.3. Representing I2RS Attributes in ephemeral configuration state 246 I2RS attributes may be modeled as meta-data, 247 [I-D.ietf-netmod-yang-metadata]. This meta-data MUST be read-only; 248 operations attempting to alter it MUST be silently ignored. An I2RS 249 module will be defined to document this meta data. An example of its 250 use: 252 254 ... 255 257 6. Subscriptions to Changed State Requirements 259 I2RS clients require the ability to monitor changes to ephemeral 260 state. While subscriptions are well defined for receiving 261 notifications, the need to create a notification set for all 262 ephemeral configuration state may be overly burdensome to the user. 264 There is thus a need for a general subscription mechanism that can 265 provide notification of changed state, with sufficient information to 266 permit the client to retrieve the impacted nodes. This should be 267 doable without requiring the notifications to be created as part of 268 every single I2RS module. 270 7. Previously Considered Ideas 272 7.1. A Separate Ephemeral Datastore 274 The primary advantage of a fully separate datastore is that the 275 semantics of its contents are always clearly ephemeral. It also 276 provides strong segregation of I2RS configuration and operational 277 state from the rest of the system within the network element. 279 The most obvious disadvantage of such a fully separate datastore is 280 that interaction with the network element's operational or 281 configuration state becomes significantly more difficult. As an 282 example, a BGP I2RS use case would be the dynamic instantiation of a 283 BGP peer. While it is readily possible to re-use any defined 284 groupings from an IETF-standardized BGP module in such an I2RS 285 ephemeral datastore's modules, one cannot currently reference state 286 from one datastore to another. 288 For example, XPath queries are done in the context document of the 289 datastore in question and thus it is impossible for an I2RS model to 290 fulfil a "must" or "when" requirement in the BGP module in the 291 standard data stores. To implement such a mechanism would require 292 appropriate semantics for XPath. 294 7.2. Panes of Glass/Overlay 296 I2RS ephemeral configuration state is generally expected to be 297 disjoint from persistent configuration. In some cases, extending 298 persistent configuration with ephemeral attributes is expected to be 299 useful. A case that is considered potentially useful but problematic 300 was explored was the ability to "overlay" persistent configuration 301 with ephemeral configuration. 303 In this overlay scenario, persistent configuration that was not 304 shadowed by ephemeral configuration could be "read through". 306 There were two perceived disadvantages to this mechanism: 308 1. The general complexity with managing the overlay mechanism 309 itself. 311 2. Consistency issues with validation should the ephemeral state be 312 lost, perhaps on reboot. In such a case, the previously shadowed 313 persistent state may no longer validate. 315 8. Actions Required to Implement this Draft 317 o Draft for adding "config ephemeral" to YANG. 318 o Draft defining NETCONF changes including capability, RPC operation 319 changes and support of secondary identity, RPC changes to support 320 priority. 321 o I2RS draft to define meta-data for priority and secondary- 322 identity. 324 9. IANA Considerations 326 TBD 328 10. Security Considerations 330 TBD 332 11. Acknowledgements 334 This document is an attempt to distill lengthy conversations on the 335 I2RS mailing list for an architecture that was for a long period of 336 time a moving target. Some individuals in particular warrant 337 specific mention for their extensive help in providing the basis for 338 this document: 340 o Alia Atlas 341 o Andy Bierman 342 o Martin Bjorklund 343 o Dean Bogdanavich 344 o Rex Fernando 345 o Joel Halpern 346 o Susan Hares 347 o Thomas Nadeau 348 o Juergen Schoenwaelder 349 o Kent Watsen 351 12. Normative References 353 [I-D.bierman-netconf-restconf] 354 Bierman, A., Bjorklund, M., Watsen, K., and R. Fernando, 355 "RESTCONF Protocol", draft-bierman-netconf-restconf-04 356 (work in progress), February 2014. 358 [I-D.ietf-i2rs-architecture] 359 Atlas, A., Halpern, J., Hares, S., Ward, D., and T. 360 Nadeau, "An Architecture for the Interface to the Routing 361 System", draft-ietf-i2rs-architecture-05 (work in 362 progress), July 2014. 364 [I-D.ietf-i2rs-traceability] 365 Clarke, J., Salgueiro, G., and C. Pignataro, "Interface to 366 the Routing System (I2RS) Traceability: Framework and 367 Information Model", draft-ietf-i2rs-traceability-02 (work 368 in progress), March 2015. 370 [I-D.ietf-netmod-yang-metadata] 371 Lhotka, L., "Defining and Using Metadata with YANG", 372 draft-ietf-netmod-yang-metadata-00 (work in progress), 373 April 2015. 375 [I-D.rfernando-i2rs-yang-mods] 376 Fernando, R., pals, p., Madhayyan, M., and A. Clemm, "YANG 377 modifications for I2RS", draft-rfernando-i2rs-yang-mods-00 378 (work in progress), February 2013. 380 [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the 381 Network Configuration Protocol (NETCONF)", RFC 6020, 382 October 2010. 384 [RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. 385 Bierman, "Network Configuration Protocol (NETCONF)", RFC 386 6241, June 2011. 388 [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure 389 Shell (SSH)", RFC 6242, June 2011. 391 [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration 392 Protocol (NETCONF) Access Control Model", RFC 6536, March 393 2012. 395 Author's Address 397 Jeffrey Haas 398 Juniper Networks 400 Email: jhaas@juniper.net