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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-15) exists of draft-ietf-i2rs-architecture-07 == Outdated reference: A later version (-13) exists of draft-ietf-idr-ls-distribution-07 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Atlas, Ed. 3 Internet-Draft Juniper Networks 4 Intended status: Informational T. Nadeau, Ed. 5 Expires: July 10, 2015 Brocade 6 D. Ward 7 Cisco Systems 8 January 6, 2015 10 Interface to the Routing System Problem Statement 11 draft-ietf-i2rs-problem-statement-05 13 Abstract 15 As modern networks grow in scale and complexity, the need for rapid 16 and dynamic control increases. With scale, the need to automate even 17 the simplest operations is important, but even more critical is the 18 ability to quickly interact with more complex operations such as 19 policy-based controls. 21 In order to enable network applications to have access to and control 22 over information in the Internet's routing system, we need a publicly 23 documented interface specification. The interface needs to support 24 real-time, asynchronous interactions using data models and encodings 25 that are efficient and potentially different from those available 26 today. Furthermore, the interface must be tailored to support a 27 variety of use cases. 29 This document expands upon these statements of requirements to 30 provide a detailed problem statement for an Interface to the Routing 31 System (I2RS). 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at http://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on July 10, 2015. 50 Copyright Notice 52 Copyright (c) 2015 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. I2RS Model and Problem Area for The IETF . . . . . . . . . . 3 69 3. Standard Data-Models of Routing State for Installation . . . 5 70 4. Learning Router Information . . . . . . . . . . . . . . . . . 6 71 5. Aspects to be Considered for an I2RS Protocol . . . . . . . . 6 72 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 73 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 74 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 75 9. Informative References . . . . . . . . . . . . . . . . . . . 8 76 Appendix A. Existing Management Interfaces . . . . . . . . . . . 9 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 79 1. Introduction 81 As modern networks grow in scale and complexity, the need for rapid, 82 flexible and dynamic control increases. With scale, the need to 83 automate even the simplest operation is important, but even more 84 critical is the ability for network operators to quickly interact 85 with these operations using mechanisms such as policy-based controls. 87 With complexity comes the need for more sophisticated automated 88 network applications and orchestration software that can process 89 large quantities of data, run complex algorithms, and adjust the 90 routing state as required in order to support the network 91 applications, their computations and their policies. Changes made to 92 the routing state of a network by external applications must be 93 verifiable by those applications to ensure that the correct state has 94 been installed in the correct places. 96 In the past, mechanisms to support the requirements outlined above 97 have been developed piecemeal as proprietary solutions to specific 98 situations and needs. Many routing elements have an external 99 interface to interact with routing - but since these vary between 100 vendors, it is difficult to integrate use of those interfaces into a 101 network. The existence of such proprietary interfaces demonstrates 102 both that the need for such an interface is understood and that 103 technology solutions are understood. What is needed are 104 technological solutions with clearly defined operations that an 105 application can initiate, and data-models to support such actions. 106 These would facilitate wide-scale deployment of interoperable 107 applications and routing systems. These solutions must be designed 108 to facilitate rapid, isolated, secure, and dynamic changes to a 109 device's routing system. In order to address these needs, the 110 creation of an Interface to the Routing System (I2RS) is needed. 112 It should be noted that during the course of this document, the term 113 "applications" is used. This is meant to refer to an executable 114 program of some sort that has access to a network, such as an IP or 115 MPLS network. 117 2. I2RS Model and Problem Area for The IETF 119 Managing a network of production devices running a variety of routing 120 protocols involves interactions between multiple components within a 121 device. Some of these components are virtual while some are 122 physical; it may be desirable for many, or even all of these 123 components to be made available to be managed and manipulated by 124 applications, given that appropriate access, authentication, and 125 policy hurdles have been crossed. The management of only some of 126 these components require standardization, as others have already been 127 standardized. The I2RS model is intended to incorporate existing 128 mechanisms where appropriate, and to build extensions and new 129 protocols where needed. The I2RS model and problem area for IETF 130 work is illustrated in Figure 1. The I2RS Agent is associated with a 131 routing element, which may or may not be co-located with a data- 132 plane. The I2RS Client is used and controlled by one or more network 133 applications; they may be co-located or the I2RS Client might be part 134 of a separate application, such as an orchestrator or controller. 135 The scope of the data-models used by I2RS extends across the entire 136 routing system and I2RS protocol. 138 +***************+ +***************+ +***************+ 139 * Application * * Application * * Application * 140 +***************+ +***************+ +***************+ 141 | I2RS Client | ^ ^ 142 +---------------+ * * 143 ^ * **************** 144 | * * 145 | v v 146 | +---------------+ +-------------+ 147 | | I2RS Client |<------->| Other I2RS | 148 | +---------------+ | Agents | 149 | ^ +-------------+ 150 |________________ | 151 | | <== I2RS Protocol 152 | | 153 ...........................|..|.................................. 154 . v v . 155 . +*************+ +---------------+ +****************+ . 156 . * Policy * | | * Routing & * . 157 . * Database *<***>| I2RS Agent |<****>* Signaling * . 158 . +*************+ | | * Protocols * . 159 . +---------------+ +****************+ . 160 . ^ ^ ^ ^ . 161 . +*************+ * * * * . 162 . * Topology * * * * * . 163 . * Database *<*******+ * * v . 164 . +*************+ * * +****************+ . 165 . * +********>* RIB Manager * . 166 . * +****************+ . 167 . * ^ . 168 . v * . 169 . +*******************+ * . 170 . * Subscription & * * . 171 . * Configuration * v . 172 . * Templates for * +****************+ . 173 . * Measurements, * * FIB Manager * . 174 . * Events, QoS, etc. * * & Data Plane * . 175 . +*******************+ +****************+ . 176 ................................................................. 178 <--> interfaces inside the scope of I2RS Protocol 179 +--+ objects inside the scope of I2RS-defined behavior 181 <**> interfaces NOT within the scope of I2RS Protocol 182 +**+ objects NOT within the scope of I2RS-defined behavior 184 .... boundary of a router supporting I2RS 186 Figure 1: I2RS model and Problem Area 188 A critical aspect of I2RS is defining a suitable protocol or 189 protocols to carry messages between the I2RS Clients and the I2RS 190 Agent, and defining the data-models for use with those I2RS 191 protocol(s). The protocol should provide the key features specified 192 in Section 5. The data models should translate into a concise 193 transfer syntax, sent via the I2RS protocol, that is straightforward 194 for applications to use (e.g., a Web Services design paradigm). The 195 information transfer should use existing transport protocols to 196 provide the reliability, security, and timeliness appropriate for the 197 particular data. 199 The second critical aspect of I2RS is a set of meaningful data-models 200 for information in the routing system and in a topology database. 201 The data-model should describe the meaning and relationships of the 202 modeled items. The data-models should be separable across different 203 features of the managed components, versioned, and extendable. As 204 shown in Figure 1, I2RS needs to interact with several logical 205 components of the routing element: policy database, topology 206 database, subscription and configuration for dynamic measurements/ 207 events, routing signaling protocols, and its RIB manager. This 208 interaction is both for writing (e.g. to policy databases or RIB 209 manager) as well as for reading (e.g. dynamic measurement or topology 210 database). An application should be able to combine data from 211 individual routing elements to provide network-wide data-model(s). 213 3. Standard Data-Models of Routing State for Installation 215 There is a need to be able to precisely control routing and signaling 216 state based upon policy or external measures. This can range from 217 simple static routes to policy-based routing to static multicast 218 replication and routing state. This means that, to usefully model 219 next-hops, the data model employed needs to handle next-hop 220 indirection and recursion (e.g. a prefix X is routed like prefix Y) 221 as well as different types of tunneling and encapsulation. The 222 relevant MIB modules (for example [RFC4292]) lack the necessary 223 generality and flexibility. In addition, by having I2RS focus 224 initially on interfaces to the RIB layer (e.g. RIB, LIB, multicast 225 RIB, policy-based routing), the ability to use routing indirection 226 allows flexibility and functionality that can't be as easily obtained 227 at the forwarding layer. 229 Efforts to provide this level of control have focused on 230 standardizing data models that describe the forwarding plane (e.g. 231 ForCES [RFC3746]). I2RS posits that the routing system and a 232 router's OS provide useful mechanisms that applications could 233 usefully harness to accomplish application-level goals. 235 In addition to interfaces to the RIB layer, there is a need to 236 configure the various routing and signaling protocols with differing 237 dynamic state based upon application-level policy decisions. The 238 range desired is not available via MIB modules at the present time. 240 Additionally, on March 2, 2014, the IESG issued a statement about 241 Writeable MIB Modules [IESG-Statement] which is expected to limit 242 creation of future writeable MIB modules. 244 4. Learning Router Information 246 A router has information that applications may require so that they 247 can understand the network, verify that programmed state is installed 248 in the forwarding plane, measure the behavior of various flows, and 249 understand the existing configuration and state of the router. I2RS 250 provides a framework so that applications can register for 251 asynchronous notifications and can make specific requests for 252 information. 254 Although there are efforts to extend the topological information 255 available, even the best of these (e.g., BGP-LS 256 [I-D.ietf-idr-ls-distribution]) still provide only the current active 257 state as seen at the IGP layer and above. Detailed topological state 258 that provides more information than the current functional status 259 (e.g. active paths and links) is needed by applications. Examples of 260 missing information include paths or link that are potentially 261 available (e.g. administratively down) or unknown (e.g. to peers or 262 customers) to the routing topology. 264 For applications to have a feedback loop that includes awareness of 265 the relevant traffic, an application must be able to request the 266 measurement and timely, scalable reporting of data. While a 267 mechanism such as IPFIX [RFC5470] may be the facilitator for 268 delivering the data, the need for an application to be able to 269 dynamically request that measurements be taken and data delivered is 270 critical. 272 There are a wide range of events that applications could use for 273 either verification of router state before other network state is 274 changed (e.g. that a route has been installed), to act upon changes 275 to relevant routes by others, or upon router events (e.g. link up/ 276 down). While a few of these (e.g. link up/down) may be available via 277 MIB notifications today, the full range is not - nor has there been 278 successfully deployed the standardized ability to set up the router 279 to trigger different actions upon an event's occurrence so that a 280 rapid reaction can be accomplished. 282 5. Aspects to be Considered for an I2RS Protocol 284 This section describes required aspects of a protocol that could 285 support I2RS. Whether such a protocol is built upon extending 286 existing mechanisms or requires a new mechanism requires further 287 investigation. 289 The key aspects needed in an interface to the routing system are: 291 Multiple Simultaneous Asynchronous Operations: A single application 292 should be able to send multiple independent atomic operations via 293 I2RS without being required to wait for each to complete before 294 sending the next. 296 Very Fine Granularity of Data Locking for Writing: When an I2RS 297 operation is processed, it is required that the data locked for 298 writing is very granular (e.g. a particular prefix and route) 299 rather than extremely coarse, as is done for writing 300 configuration. This should improve the number of concurrent I2RS 301 operations that are feasible and reduce blocking delays. 303 Multi-Headed Control: Multiple applications may communicate to the 304 same I2RS agent in a minimally coordinated fashion. It is 305 necessary that the I2RS agent can handle multiple requests in a 306 well-known policy-based fashion. Data written can be owned by 307 different I2RS clients at different times; data may even be 308 overwritten by a different I2RS client. The details of how this 309 should be handled are described in [I-D.ietf-i2rs-architecture]. 311 Duplex: Communications can be established by either the I2RS client 312 (i.e.: that resides within the application or is used by it to 313 communicate with the I2RS agent), or the I2RS agent. Similarly, 314 events, acknowledgements, failures, operations, etc. can be sent 315 at any time by both the router and the application. The I2RS is 316 not a pure pull-model where only the application queries to pull 317 responses. 319 High-Throughput: At a minimum, the I2RS Agent and associated router 320 should be able to handle a considerable number of operations per 321 second (for example 10,000 per second to handle many individual 322 subscriber routes changing simultaneously). 324 Low-Latency: Within a sub-second time-scale, it should be possible 325 to complete simple operations (e.g. reading or writing a single 326 prefix route). 328 Multi-Channel: It should be possible for information to be 329 communicated via the interface from different components in the 330 router without requiring going through a single channel. For 331 example, for scaling, some exported data or events may be better 332 sent directly from the forwarding plane, while other interactions 333 may come from the control-plane. Thus a single TCP session would 334 not be a good match. 336 Scalable, Filterable Information Access: To extract information in a 337 scalable fashion that is more easily used by applications, the 338 ability to specify filtering constructs in an operation requesting 339 data or requesting an asynchronous notification is very valuable. 341 Secure Control and Access: Any ability to manipulate routing state 342 must be subject to authentication and authorization. Sensitive 343 routing information may also need to be provided via secure access 344 back to the I2RS client. Such communications must be integrity 345 protected. Some communications will also require confidentiality. 347 Extensible and Interoperability: Both the I2RS protocol and models 348 must be extensible and interoperate between different versions of 349 protocols and models. 351 6. Acknowledgements 353 The authors would like to thank Ken Gray, Ed Crabbe, Nic Leymann, 354 Carlos Pignataro, Kwang-koog Lee, Linda Dunbar, Sue Hares, Russ 355 Housley, Eric Grey, Qin Wu, and Stephen Kent for their suggestions 356 and review. 358 7. IANA Considerations 360 This document includes no request to IANA. 362 8. Security Considerations 364 Security is a key aspect of any protocol that allows state 365 installation and extracting of detailed router state. The need for 366 secure control and access is mentioned in Section 5 More 367 architectural security considerations are discussed in 368 [I-D.ietf-i2rs-architecture]. Briefly, the I2RS Agent is assumed to 369 have a separate authentication and authorization channel by which it 370 can validate both the identity and the permissions associated with an 371 I2RS Client. Mutual authentication between the I2RS Agent and I2RS 372 Client is required. Different levels of integrity, confidentiality, 373 and replay protection are relevant for different aspects of I2RS. 375 9. Informative References 377 [I-D.ietf-i2rs-architecture] 378 Atlas, A., Halpern, J., Hares, S., Ward, D., and T. 379 Nadeau, "An Architecture for the Interface to the Routing 380 System", draft-ietf-i2rs-architecture-07 (work in 381 progress), December 2014. 383 [I-D.ietf-idr-ls-distribution] 384 Gredler, H., Medved, J., Previdi, S., Farrel, A., and S. 385 Ray, "North-Bound Distribution of Link-State and TE 386 Information using BGP", draft-ietf-idr-ls-distribution-07 387 (work in progress), November 2014. 389 [IESG-Statement] 390 IESG, "Writable MIB Module IESG Statement", March 2014, 391 . 394 [RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal, 395 "Forwarding and Control Element Separation (ForCES) 396 Framework", RFC 3746, April 2004. 398 [RFC4292] Haberman, B., "IP Forwarding Table MIB", RFC 4292, April 399 2006. 401 [RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek, 402 "Architecture for IP Flow Information Export", RFC 5470, 403 March 2009. 405 Appendix A. Existing Management Interfaces 407 This section discusses as a single entity the combination of the 408 abstract data models, their representation in a data language, and 409 the transfer protocol commonly used with them. While other 410 combinations of these existing standard technologies are possible, 411 the ways described are those that have significant deployment. 413 There are three basic ways that routers are managed. The most 414 popular is the command line interface (CLI), which allows both 415 configuration and learning of device state. This is a proprietary 416 interface resembling a UNIX shell that allows for very customized 417 control and observation of a device, and, specifically of interest in 418 this case, its routing system. Some form of this interface exists on 419 almost every device (virtual or otherwise). Processing of 420 information returned to the CLI (called "screen scraping") is a 421 burdensome activity because the data is normally formatted for use by 422 a human operator, and because the layout of the data can vary from 423 device to device, and between different software versions. Despite 424 its ubiquity, this interface has never been standardized and is 425 unlikely to ever be standardized. CLI standardization is not 426 considered as a candidate solution for the problems motivating I2RS. 428 The second most popular interface for interrogation of a device's 429 state, statistics, and configuration is The Simple Network Management 430 Protocol (SNMP) and a set of relevant standards-based and proprietary 431 Management Information Base (MIB) modules. SNMP has a strong history 432 of being used by network managers to gather statistical and state 433 information about devices, including their routing systems. However, 434 SNMP is very rarely used to configure a device or any of its systems 435 for reasons that vary depending upon the network operator. Some 436 example reasons include complexity, the lack of desired configuration 437 semantics (e.g., configuration "roll-back", "sandboxing" or 438 configuration versioning), and the difficulty of using the semantics 439 (or lack thereof) as defined in the MIB modules to configure device 440 features. Therefore, SNMP is not considered as a candidate solution 441 for the problems motivating I2RS. 443 Finally, the IETF's Network Configuration (or NETCONF) protocol has 444 made many strides at overcoming most of the limitations around 445 configuration that were just described. However, the initial lack of 446 standard data models have hampered the adoption of NETCONF. 447 Naturally, I2RS may help define needed information and data models. 448 Additional extensions to handle multi-headed control may need to be 449 added to NETCONF and/or appropriate data models. 451 Authors' Addresses 453 Alia Atlas (editor) 454 Juniper Networks 455 10 Technology Park Drive 456 Westford, MA 01886 457 USA 459 Email: akatlas@juniper.net 461 Thomas D. Nadeau (editor) 462 Brocade 464 Email: tnadeau@lucidvision.com 466 Dave Ward 467 Cisco Systems 468 Tasman Drive 469 San Jose, CA 95134 470 USA 472 Email: wardd@cisco.com