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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-12) exists of draft-ietf-rtgwg-enterprise-pa-multihoming-00 == Outdated reference: A later version (-15) exists of draft-ietf-spring-segment-routing-11 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-mpls-08 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Spring J. Brzozowski 3 Internet-Draft J. Leddy 4 Intended status: Informational Comcast 5 Expires: October 15, 2017 C. Filsfils 6 R. Maglione, Ed. 7 M. Townsley 8 Cisco Systems 9 April 13, 2017 11 IPv6 SPRING Use Cases 12 draft-ietf-spring-ipv6-use-cases-10 14 Abstract 16 The objective of this document is to illustrate some use cases that 17 need to be taken into account by the Source Packet Routing in 18 Networking (SPRING) architecture in the context of an IPv6 19 environment. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on October 15, 2017. 38 Copyright Notice 40 Copyright (c) 2017 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. IPv6 SPRING use cases . . . . . . . . . . . . . . . . . . . . 4 57 2.1. SPRING in the Home Network . . . . . . . . . . . . . . . 4 58 2.2. SPRING in the Access Network . . . . . . . . . . . . . . 5 59 2.3. SPRING in the Data Center . . . . . . . . . . . . . . . . 6 60 2.4. SPRING in the Content Delivery Networks . . . . . . . . . 6 61 2.5. SPRING in the Core networks . . . . . . . . . . . . . . . 7 62 3. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8 63 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 64 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 65 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 66 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 67 7.1. Informative References . . . . . . . . . . . . . . . . . 9 68 7.2. Normative References . . . . . . . . . . . . . . . . . . 10 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 71 1. Introduction 73 Source Packet Routing in Networking (SPRING) architecture leverages 74 the source routing paradigm. An ingress node steers a packet through 75 a controlled set of instructions, called segments, by prepending the 76 packet with SPRING header. The SPRING architecture is described in 77 [I-D.ietf-spring-segment-routing]. 79 In today's networks, source routing is typically accomplished by 80 encapsulating IP packets in MPLS LSPs that are signaled via RSVP-TE. 81 Therefore, there are scenarios where it may be possible to run IPv6 82 on top of MPLS, and as such, the MPLS Segment Routing architecture 83 described in [I-D.ietf-spring-segment-routing-mpls] could be 84 leveraged to provide spring capabilities in an IPv6/MPLS environment. 86 However, there are other cases and/or specific network segments (such 87 as for example the Home Network, the Data Center, etc.) where MPLS 88 may not be available or deployable for lack of support on network 89 elements or for an operator's design choice. In such scenarios a 90 non-MPLS based solution would be preferred by the network operators 91 of such infrastructures. 93 In addition there are cases where the operators could have made the 94 design choice to disable IPv4, for ease of management and scale 95 (return to single-stack) or due to an address constraint, for example 96 because they do not possess enough IPv4 addresses resources to number 97 all the endpoints and other network elements on which they desire to 98 run MPLS. 100 In such scenario the support for MPLS operations on an IPv6-only 101 network would be required. However today's IPv6-only networks are 102 not fully capable of supporting MPLS. There is ongoing work in the 103 MPLS Working Group, described in [RFC7439] to identify gaps that must 104 be addressed in order to allow MPLS-related protocols and 105 applications to be used with IPv6-only networks. This is an another 106 example of scenario where a solution relying on IPv6 without 107 requiring the use of MPLS could represent a valid option to solve the 108 problem and meet operators' requirements. 110 It is important to clarify that today, it is possible to run IPv6 on 111 top of an IPv4 MPLS network by using the mechanism called 6PE, 112 described in [RFC4798]. However this approach does not fulfill the 113 requirement of removing the need of IPv4 addresses in the network, as 114 requested in the above use case. 116 In summary there is a class of use cases that motivates an IPv6 data 117 plane. This document identifies some fundamental scenarios that, 118 when recognized in conjunction, strongly indicate an IPv6 data plane: 120 1. There is a need or desire to impose source-routing semantics 121 within an application or at the edge of a network (for example, a 122 CPE or home gateway) 124 2. There is a strict lack of an MPLS dataplane in a portion of the 125 end to end path 127 3. There is a need or desire to remove routing state from any node 128 other than the source, such that the source is the only node that 129 knows and will know the path a packet will take, a priori 131 4. There is a need to connect millions of addressable segment 132 endpoints, thus high routing scalability is a requirement. IPv6 133 addresses are inherently summarizable: a very large operator 134 could scale by summarizing IPv6 subnets at various internal 135 boundaries. This is very simple and is a basic property of IP 136 routing. MPLS node segments are not summarizable. To reach the 137 same scale, an operator would need to introduce additional 138 complexity, such as mechanisms known with the industry term 139 Seamless MPLS [I-D.ietf-mpls-seamless-mpls]. 141 In any environment with requirements such as those listed above, an 142 IPv6 data plane provides a powerful combination of capabilities for a 143 network operator to realize benefits in explicit routing, protection 144 and restoration, high routing scalability, traffic engineering, 145 service chaining, service differentiation and application flexibility 146 via programmability. 148 2. IPv6 SPRING use cases 150 This section will describe some scenarios where MPLS may not be 151 present and it will highlight the need for the spring architecture to 152 take them into account. 154 The use cases described in the section do not constitute an 155 exhaustive list of all the possible scenarios; this section only 156 includes some of the most common envisioned deployment models for 157 IPv6 Segment Routing. In addition to the use cases described in this 158 document the spring architecture should be able to be applied to all 159 the use cases described in [RFC7855] for the spring MPLS data plane, 160 when an IPv6 data plane is present. 162 2.1. SPRING in the Home Network 164 An IPv6-enabled home network provides ample globally routed IP 165 addresses for all devices in the home. An IPv6 home network with 166 multiple egress points and associated provider-assigned prefixes 167 will, in turn, provide multiple IPv6 addresses to hosts. A homenet 168 performing Source and Destination Routing 169 ([I-D.ietf-rtgwg-enterprise-pa-multihoming]) will ensure that packets 170 exit the home at the appropriate egress based on the associated 171 delegated prefix for that link. 173 A spring enabled home provides the ability to steer traffic into a 174 specific path from end-hosts in the home, or from a customer edge 175 router in the home. If the selection of the source routed path is 176 enabled at the customer edge router, that router is responsible for 177 classifying traffic and steering it into the correct path. If hosts 178 in the home have explicit source selection rules, classification can 179 be based on source address or associated network egress point, 180 avoiding the need for DPI-based implicit classification techniques. 181 If the traffic is steered into a specific path by the host itself, it 182 is important to know which networks can interpret the spring header. 183 This information can be provided as part of host configuration as a 184 property of the configured IP address. 186 The ability to steer traffic to an appropriate egress or utilize a 187 specific type of media (e.g., low-power, WIFI, wired, femto-cell, 188 bluetooth, MOCA, HomePlug, etc.) within the home itself are obvious 189 cases which may be of interest to an application running within a 190 home network. 192 Steering to a specific egress point may be useful for a number of 193 reasons, including: 195 o Regulatory 197 o Performance of a particular service associated with a particular 198 link 200 o Cost imposed due to data-caps or per-byte charges 202 o Home vs. work traffic in homes with one or more teleworkers, etc. 204 o Specific services provided by one ISP vs. another 206 Information included in the spring header, whether imposed by the 207 end-host itself, a customer edge router, or within the access network 208 of the ISP, may be of use at the far ends of the data communication 209 as well. For example, an application running on an end-host with 210 application-support in a data center can utilize the spring header as 211 a channel to include information that affects its treatment within 212 the data center itself, allowing for application-level steering and 213 load-balancing without relying upon implicit application 214 classification techniques at the data-center edge. Further, as more 215 and more application traffic is encrypted, the ability to extract 216 (and include in the spring header) just enough information to enable 217 the network and data center to load-balance and steer traffic 218 appropriately becomes more and more important. 220 2.2. SPRING in the Access Network 222 Access networks deliver a variety of types of traffic from the 223 service provider's network to the home environment and from the home 224 towards the service provider's network. 226 For bandwidth management or related purposes, the service provider 227 may want to associate certain types of traffic to specific physical 228 or logical downstream capacity pipes. 230 This mapping is not the same thing as classification and scheduling. 231 In the Cable access network, each of these pipes are represented at 232 the DOCSIS [DOCSIS] layer as different service flows, which are 233 better identified as differing data links. As such, creating this 234 separation allows an operator to differentiate between different 235 types of content and perform a variety of differing functions on 236 these pipes, such as byte capping, regulatory compliance functions, 237 and billing. 239 In a cable operator's environment, these downstream pipes could be a 240 specific QAM [QAM], a DOCSIS [DOCSIS] service flow or a service 241 group. 243 Similarly, the operator may want to map traffic from the home sent 244 towards the service provider's network to specific upstream capacity 245 pipes. Information carried in a packet's spring header could provide 246 the target pipe for this specific packet. The access device would 247 not need to know specific details about the packet to perform this 248 mapping; instead the access device would only need to know the 249 interpretation of the spring header and how to map it to the target 250 pipe. 252 2.3. SPRING in the Data Center 254 Some Data Center operators are transitioning their Data Center 255 infrastructure from IPv4 to native IPv6 only, in order to cope with 256 IPv4 address depletion and to achieve larger scale. In such 257 environment, source routing (through Segment Routing IPv6) can be 258 used to steer traffic across specific paths through the network. The 259 specific path may also include a given function one or more nodes in 260 the path are requested to perform. 262 In addition one of the fundamental requirements for Data Center 263 architecture is to provide scalable, isolated tenant networks. In 264 such scenario Segment Routing can be used to identify specific nodes, 265 tenants, and functions and to build a construct to steer the traffic 266 across that specific path. 268 2.4. SPRING in the Content Delivery Networks 270 The rise of online video applications and new, video-capable IP 271 devices has led to an explosion of video traffic traversing network 272 operator infrastructures. In the drive to reduce the capital and 273 operational impact of the massive influx of online video traffic, as 274 well as to extend traditional TV services to new devices and screens, 275 network operators are increasingly turning to Content Delivery 276 Networks (CDNs). 278 Several studies showed the benefits of connecting caches in a 279 hierarchical structure following the hierarchical nature of the 280 Internet. In a cache hierarchy one cache establishes peering 281 relationships with its neighbor caches. There are two types of 282 relationship: parent and sibling. A parent cache is essentially one 283 level up in a cache hierarchy. A sibling cache is on the same level. 284 Multiple levels of hierarchy are commonly used in order to build 285 efficient caches architecture. 287 In an environment, where each single cache system can be uniquely 288 identified by its own IPv6 address, a list containing a sequence of 289 the caches in a hierarchy can be built. At each node (cache) in the 290 list, the presence of the requested content if checked. If the 291 requested content is found at the cache (cache hits scenario) the 292 sequence ends, even if there are more nodes in the list; otherwise 293 next element in the list (next node/cache) is examined. 295 2.5. SPRING in the Core networks 297 MPLS is a well-known technology widely deployed in many IP core 298 networks. However there are some operators that do not run MPLS 299 everywhere in their core network today, thus moving forward they 300 would prefer to have an IPv6 native infrastructure for the core 301 network. 303 While the overall amount of traffic offered to the network continues 304 to grow and considering that multiple types of traffic with different 305 characteristics and requirements are quickly converging over single 306 network architecture, the network operators are starting to face new 307 challenges. 309 Some operators are looking at the possibility to setup an explicit 310 path based on the IPv6 source address for specific types of traffic 311 in order to efficiently use their network infrastructure. In case of 312 IPv6 some operators are currently assigning or plan to assign IPv6 313 prefix(es) to their IPv6 customers based on regions/geography, thus 314 the subscriber's IPv6 prefix could be used to identify the region 315 where the customer is located. In such environment the IPv6 source 316 address could be used by the Edge nodes of the network to steer 317 traffic and forward it through a specific path other than the optimal 318 path. 320 The need to setup a source-based path, going through some specific 321 middle/intermediate points in the network may be related to different 322 requirements: 324 o The operator may want to be able to use some high bandwidth links 325 for specific type of traffic (like video) avoiding the need for 326 over-dimensioning all the links of the network; 328 o The operator may want to be able to setup a specific path for 329 delay sensitive applications; 331 o The operator may have the need to be able to select one (or 332 multiple) specific exit point(s) at peering points when different 333 peering points are available; 335 o The operator may have the need to be able to setup a source based 336 path for specific services in order to be able to reach some 337 servers hosted in some facilities not always reachable through the 338 optimal path; 340 o The operator may have the need to be able to provision guaranteed 341 disjoint paths (so-called dual-plane network) for diversity 342 purposes 344 All these scenarios would require a form of traffic engineering 345 capabilities in IP core networks not running MPLS and not willing to 346 run it. 348 3. Contributors 350 Many people contributed to this document. The authors of this 351 document would like to thank and recognize them and their 352 contributions. These contributors provided invaluable concepts and 353 content for this document's creation. 355 Ida Leung 356 Rogers Communications 357 8200 Dixie Road 358 Brampton, ON L6T 0C1 359 CANADA 361 Email: Ida.Leung@rci.rogers.com 363 Stefano Previdi 364 Cisco Systems 365 Via Del Serafico, 200 366 Rome 00142 367 Italy 369 Email: sprevidi@cisco.com 371 Christian Martin 372 Cisco Systems 374 Email: martincj@cisco.com 376 4. Acknowledgements 378 The authors would like to thank Brian Field, Robert Raszuk, Wes 379 George, Eric Vyncke, Fred Baker, John G. Scudder and Yakov Rekhter 380 for their valuable comments and inputs to this document. 382 5. IANA Considerations 384 This document does not require any action from IANA. 386 6. Security Considerations 388 This document presents use cases to be considered by the spring 389 architecture and potential IPv6 extensions. As such, it does not 390 introduce any security considerations. However, there are a number 391 of security concerns with source routing at the IP layer [RFC5095]. 392 It is expected that any solution that addresses these use cases to 393 also address any security concerns. 395 7. References 397 7.1. Informative References 399 [DOCSIS] "DOCSIS Specifications Page", 400 . 403 [I-D.ietf-mpls-seamless-mpls] 404 Leymann, N., Decraene, B., Filsfils, C., Konstantynowicz, 405 M., and D. Steinberg, "Seamless MPLS Architecture", draft- 406 ietf-mpls-seamless-mpls-07 (work in progress), June 2014. 408 [I-D.ietf-rtgwg-enterprise-pa-multihoming] 409 Baker, F., Bowers, C., and J. Linkova, "Enterprise 410 Multihoming using Provider-Assigned Addresses without 411 Network Prefix Translation: Requirements and Solution", 412 draft-ietf-rtgwg-enterprise-pa-multihoming-00 (work in 413 progress), March 2017. 415 [I-D.ietf-spring-segment-routing] 416 Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., 417 and R. Shakir, "Segment Routing Architecture", draft-ietf- 418 spring-segment-routing-11 (work in progress), February 419 2017. 421 [I-D.ietf-spring-segment-routing-mpls] 422 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 423 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 424 data plane", draft-ietf-spring-segment-routing-mpls-08 425 (work in progress), March 2017. 427 [QAM] "QAM specification", . 430 [RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur, 431 "Connecting IPv6 Islands over IPv4 MPLS Using IPv6 432 Provider Edge Routers (6PE)", RFC 4798, 433 DOI 10.17487/RFC4798, February 2007, 434 . 436 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 437 of Type 0 Routing Headers in IPv6", RFC 5095, 438 DOI 10.17487/RFC5095, December 2007, 439 . 441 [RFC7439] George, W., Ed. and C. Pignataro, Ed., "Gap Analysis for 442 Operating IPv6-Only MPLS Networks", RFC 7439, 443 DOI 10.17487/RFC7439, January 2015, 444 . 446 7.2. Normative References 448 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 449 Litkowski, S., Horneffer, M., and R. Shakir, "Source 450 Packet Routing in Networking (SPRING) Problem Statement 451 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 452 2016, . 454 Authors' Addresses 456 John Brzozowski 457 Comcast 459 Email: john_brzozowski@cable.comcast.com 461 John Leddy 462 Comcast 464 Email: John_Leddy@cable.comcast.com 465 Clarence Filsfils 466 Cisco Systems 467 Brussels 468 BE 470 Email: cfilsfil@cisco.com 472 Roberta Maglione (editor) 473 Cisco Systems 474 Via Torri Bianche 8 475 Vimercate 20871 476 Italy 478 Email: robmgl@cisco.com 480 Mark Townsley 481 Cisco Systems 483 Email: townsley@cisco.com