idnits 2.17.1 draft-ietf-spring-ipv6-use-cases-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 27, 2014) is 3462 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-04) exists of draft-ietf-mpls-ipv6-only-gap-02 == Outdated reference: A later version (-06) exists of draft-ietf-sfc-dc-use-cases-01 == Outdated reference: A later version (-13) exists of draft-ietf-sfc-problem-statement-10 == Outdated reference: A later version (-08) exists of draft-ietf-spring-problem-statement-03 == Outdated reference: A later version (-08) exists of draft-previdi-6man-segment-routing-header-03 == Outdated reference: A later version (-07) exists of draft-quinn-sfc-nsh-03 Summary: 0 errors (**), 0 flaws (~~), 7 warnings (==), 1 comment (--).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: April 30, 2015 I. Leung 6 Rogers Communications 7 S. Previdi 8 M. Townsley 9 C. Martin 10 C. Filsfils 11 R. Maglione, Ed. 12 Cisco Systems 13 October 27, 2014 15 IPv6 SPRING Use Cases 16 draft-ietf-spring-ipv6-use-cases-02 18 Abstract 20 Source Packet Routing in Networking (SPRING) architecture leverages 21 the source routing paradigm. A node steers a packet through a 22 controlled set of instructions, called segments, by prepending the 23 packet with SPRING header. A segment can represent any instruction, 24 topological or service-based. A segment can have a local semantic to 25 the SPRING node or global within the SPRING domain. SPRING allows to 26 enforce a flow through any topological path and service chain while 27 maintaining per-flow state only at the ingress node to the SPRING 28 domain. 30 The objective of this document is to illustrate some use cases that 31 need to be taken into account by the Source Packet Routing in 32 Networking (SPRING) architecture. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at http://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on April 30, 2015. 50 Copyright Notice 52 Copyright (c) 2014 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. IPv6 SPRING use cases . . . . . . . . . . . . . . . . . . . . 3 69 2.1. SPRING in the Home Network . . . . . . . . . . . . . . . 5 70 2.2. SPRING in the Access Network . . . . . . . . . . . . . . 6 71 2.3. SPRING in the Data Center . . . . . . . . . . . . . . . . 7 72 2.4. SPRING in the Content Delivery Networks . . . . . . . . . 7 73 2.5. SPRING in the Core networks . . . . . . . . . . . . . . . 8 74 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 75 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 76 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 77 6. Informative References . . . . . . . . . . . . . . . . . . . 10 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 80 1. Introduction 82 Source Packet Routing in Networking (SPRING) architecture leverages 83 the source routing paradigm. An ingress node steers a packet through 84 a controlled set of instructions, called segments, by prepending the 85 packet with SPRING header. A segment can represent any instruction, 86 topological or service-based. A segment can represent a local 87 semantic on the SPRING node, or a global semantic within the SPRING 88 domain. SPRING allows one to enforce a flow through any topological 89 path and service chain while maintaining per-flow state only at the 90 ingress node to the SPRING domain. 92 The SPRING architecture is described in 93 [I-D.filsfils-spring-segment-routing]. The SPRING control plane is 94 agnostic to the dataplane, thus it can be applied to both MPLS and 95 IPv6. In case of MPLS the (list of) segment identifiers are carried 96 in the MPLS label stack, while for the IPv6 dataplane, a new type of 97 routing extension header is required. 99 The details of the new routing extension header are described in 100 [I-D.previdi-6man-segment-routing-header] which also covers the 101 security considerations and the aspects related to the deprecation of 102 the IPv6 Type 0 Routing Header described in [RFC5095]. 104 2. IPv6 SPRING use cases 106 In today's networks, source routing is typically accomplished by 107 encapsulating IP packets in MPLS LSPs that are signaled via RSVP-TE. 108 Therefore, there are scenarios where it may be possible to run IPv6 109 on top of MPLS, and as such, the MPLS Segment Routing architecture 110 described in [I-D.filsfils-spring-segment-routing-mpls] could be 111 leveraged to provide SPRING capabilities in an IPv6/MPLS environment. 113 However, there are other cases and/or specific network segments (such 114 as for example the Home Network, the Data Center, etc.) where MPLS 115 may not be available or deployable for lack of support on network 116 elements or for an operator's design choice. In such scenarios a 117 non-MPLS based solution would be preferred by the network operators 118 of such infrastructures. 120 In addition there are cases where the operators could have made the 121 design choice to disable IPv4, for ease of management and scale 122 (return to single-stack) or due to an address constraint, for example 123 because they do not possess enough IPv4 addresses resources to number 124 all the endpoints and other network elements on which they desire to 125 run MPLS. 127 In such scenario the support for MPLS operations on an IPv6-only 128 network would be required. However today's IPv6-only networks are 129 not fully capable of supporting MPLS. There is ongoing work in the 130 MPLS Working Group, described in [I-D.ietf-mpls-ipv6-only-gap] to 131 identify gaps that must be addressed in order to allow MPLS-related 132 protocols and applications to be used with IPv6-only networks. This 133 is an another example of scenario where an IPv6-only solution could 134 represent a valid option to solve the problem and meet operators' 135 requirements. 137 It is important to clarify that today, it is possible to run IPv6 on 138 top of an IPv4 MPLS network by using the mechanism called 6PE, 139 described in [RFC4798]. However this approach does not fulfill the 140 requirement of removing the need of IPv4 addresses in the network, as 141 requested in the above use case. 143 In addition it is worth to note that in today's MPLS dual-stack 144 networks IPv4 traffic is labeled while IPv6 traffic is usually 145 natively routed, not label-switched. Therefore in order to be able 146 to provide Traffic Engineering "like" capabilities for IPv6 traffic 147 additional/alternative encapsulation mechanisms would be required. 149 In summary there is a class of use cases that motivate an IPv6 data 150 plane. The authors identify some fundamental scenarios that, when 151 recognized in conjunction, strongly indicate an IPv6 data plane: 153 1. There is a need or desire to impose source-routing semantics 154 within an application or at the edge of a network (for example, a 155 CPE or home gateway) 157 2. There is a strict lack of an MPLS dataplane 159 3. There is a need or desire to remove routing state from any node 160 other than the source, such that the source is the only node that 161 knows and will know the path a packet will take, a priori 163 4. There is a need to connect millions of addressable segment 164 endpoints, thus high routing scalability is a requirement. IPv6 165 addresses are inherently summarizable: a very large operator 166 could scale by summarizing IPv6 subnets at various internal 167 boundaries. This is very simple and is a basic property of IP 168 routing. MPLS node segments are not summarizable. To reach the 169 same scale, an operator would need to introduce additional 170 complexity, such as mechanisms described in 171 [I-D.ietf-mpls-seamless-mpls] 173 In any environment with requirements such as those listed above, an 174 IPv6 data plane provides a powerful combination of capabilities for a 175 network operator to realize benefits in explicit routing, protection 176 and restoration, high routing scalability, traffic engineering, 177 service chaining, service differentiation and application flexibility 178 via programmability. 180 This section will describe some scenarios where MPLS may not be 181 present and it will highlight how the SPRING architecture could be 182 used to address such use cases, particularly, when an MPLS data plane 183 is neither present nor desired. 185 The use cases described in the section do not constitute an 186 exhaustive list of all the possible scenarios; this section only 187 includes some of the most common envisioned deployment models for 188 IPv6 Segment Routing. 190 In addition to the use cases described in this document the SPRING 191 architecture can be applied to all the use cases described in 192 [I-D.ietf-spring-problem-statement] for the SPRING MPLS data plane, 193 when an IPv6 data plane is present. 195 2.1. SPRING in the Home Network 197 An IPv6-enabled home network provides ample globally routed IP 198 addresses for all devices in the home. An IPv6 home network with 199 multiple egress points and associated provider-assigned prefixes 200 will, in turn, provide multiple IPv6 addresses to hosts. A homenet 201 performing Source and Destination Routing ([I-D.troan-homenet-sadr]) 202 will ensure that packets exit the home at the appropriate egress 203 based on the associated delegated prefix for that link. 205 A SPRING enabled home provides the possibility for imposition of a 206 Segment List by end-hosts in the home, or a customer edge router in 207 the home. If the Segment List is enabled at the customer edge 208 router, that router is responsible for classifying traffic and 209 inserting the appropriate Segment List. If hosts in the home have 210 explicit source selection rules (see 211 [I-D.lepape-6man-prefix-metadata]), classification can be based on 212 source address or associated network egress point, avoiding the need 213 for DPI-based implicit classification techniques. If the Segment 214 List is inserted by the host itself, it is important to know which 215 networks can interpret the SPRING header. This information can be 216 provided as part of host configuration as a property of the 217 configured IP address (see [I-D.bhandari-dhc-class-based-prefix]). 219 The ability to steer traffic to an appropriate egress or utilize a 220 specific type of media (e.g., low-power, WIFI, wired, femto-cell, 221 bluetooth, MOCA, HomePlug, etc.) within the home itself are obvious 222 cases which may be of interest to an application running within a 223 home network. 225 Steering to a specific egress point may be useful for a number of 226 reasons, including: 228 o Regulatory 230 o Performance of a particular service associated with a particular 231 link 233 o Cost imposed due to data-caps or per-byte charges 235 o Home vs. work traffic in homes with one or more teleworkers, etc. 237 o Specific services provided by one ISP vs. another 238 Information included in the Segment List, whether imposed by the end- 239 host itself, a customer edge router, or within the access network of 240 the ISP, may be of use at the far ends of the data communication as 241 well. For example, an application running on an end-host with 242 application-support in a data center can utilize the Segment List as 243 a channel to include information that affects its treatment within 244 the data center itself, allowing for application-level steering and 245 load-balancing without relying upon implicit application 246 classification techniques at the data-center edge. Further, as more 247 and more application traffic is encrypted, the ability to extract 248 (and include in the Segment List) just enough information to enable 249 the network and data center to load-balance and steer traffic 250 appropriately becomes more and more important. 252 2.2. SPRING in the Access Network 254 Access networks deliver a variety of types of traffic from the 255 service provider's network to the home environment and from the home 256 towards the service provider's network. 258 For bandwidth management or related purposes, the service provider 259 may want to associate certain types of traffic to specific physical 260 or logical downstream capacity pipes. 262 This mapping is not the same thing as classification and scheduling. 263 In the Cable access network, each of these pipes are represented at 264 the DOCSIS layer as different service flows, which are better 265 identified as differing data links. As such, creating this 266 separation allows an operator to differentiate between different 267 types of content and perform a variety of differing functions on 268 these pipes, such as egress vectoring, byte capping, regulatory 269 compliance functions, and billing. 271 In a cable operator's environment, these downstream pipes could be a 272 specific QAM, a DOCSIS service flow or a service group. 274 Similarly, the operator may want to map traffic from the home sent 275 towards the service provider's network to specific upstream capacity 276 pipes. Information carried in a packet's SPRING header could provide 277 the target pipe for this specific packet. The access device would 278 not need to know specific details about the packet to perform this 279 mapping; instead the access device would only need to know how to map 280 the SR SID value to the target pipe. 282 2.3. SPRING in the Data Center 284 A key use case for SPRING is to cause a packet to follow a specific 285 path through the network. One can think of the service function 286 performed at each SPRING node to be forwarding. More complex service 287 functions could be applied to the packet by a SPRING node including 288 accounting, IDS, load balancing, and fire walling. 290 The term "Service Function Chain", as defined in 291 [I-D.ietf-sfc-problem-statement], it is used to describe an ordered 292 set of service functions that must be applied to packets. 294 A service provider may choose to have these service functions 295 performed external to the routing infrastructure, specifically on 296 either dedicated physical servers or within VMs running on a 297 virtualization platform. 299 [I-D.ietf-sfc-dc-use-cases] describes use cases that demonstrate the 300 applicability of Service Function Chaining (SFC) within a data center 301 environment and provides SFC requirements for data center centric use 302 cases. 304 2.4. SPRING in the Content Delivery Networks 306 The rise of online video applications and new, video-capable IP 307 devices has led to an explosion of video traffic traversing network 308 operator infrastructures. In the drive to reduce the capital and 309 operational impact of the massive influx of online video traffic, as 310 well as to extend traditional TV services to new devices and screens, 311 network operators are increasingly turning to Content Delivery 312 Networks (CDNs). 314 Several studies showed the benefits of connecting caches in a 315 hierarchical structure following the hierarchical nature of the 316 Internet. In a cache hierarchy one cache establishes peering 317 relationships with its neighbor caches. There are two types of 318 relationship: parent and sibling. A parent cache is essentially one 319 level up in a cache hierarchy. A sibling cache is on the same level. 320 Multiple levels of hierarchy are commonly used in order to build 321 efficient caches architecture. 323 In an environment, where each single cache system can be uniquely 324 identified by its own IPv6 address, a Segment List containing a 325 sequence of the caches in a hierarchy can be built. At each node 326 (cache) present in the Segment List a TCP session to port 80 is 327 established and if the requested content is found at the cache (cache 328 hits scenario) the sequence ends, even if there are more nodes in the 329 list. 331 To achieve the behavior described above, in addition to the Segment 332 List, which specifies the path to be followed to explore the 333 hierarchic architecture, a way to instruct the node to take a 334 specific action is required. The function to be performed by a 335 service node can be carried into a new header called Network Service 336 Header (NSH) defined in [I-D.quinn-sfc-nsh]. A Network Service 337 Header (NSH) is metadata added to a packet that is used to create a 338 service plane. The service header is added by a service 339 classification function that determines which packets require 340 servicing, and correspondingly which service path to follow to apply 341 the appropriate service. 343 In the above example the service to be performed by the service node 344 was to establish a TCP session to port 80, but in other scenarios 345 different functions may be required. Another example of action to be 346 taken by the service node is the capability to perform 347 transformations on payload data, like real-time video transcode 348 option (for rate and/or resolution). 350 The use of SPRING together with the NSH allows building flexible 351 service chains where the topological information related to the path 352 to be followed is carried into the Segment List while the "service 353 plane related information" (function/action to be performed) is 354 encoded in the metadata, carried into the NSH. The details about 355 using SPRING together with NSH will be described in a separate 356 document. 358 2.5. SPRING in the Core networks 360 MPLS is a well-known technology widely deployed in many IP core 361 networks. However there are some operators that do not run MPLS 362 everywhere in their core network today, thus moving forward they 363 would prefer to have an IPv6 native infrastructure for the core 364 network. 366 While the overall amount of traffic offered to the network continues 367 to grow and considering that multiple types of traffic with different 368 characteristics and requirements are quickly converging over single 369 network architecture, the network operators are starting to face new 370 challenges. 372 Some operators are looking at the possibility to setup an explicit 373 path based on the IPv6 source address for specific types of traffic 374 in order to efficiently use their network infrastructure. In case of 375 IPv6 some operators are currently assigning or plan to assign IPv6 376 prefix(es) to their IPv6 customers based on regions/geography, thus 377 the subscriber's IPv6 prefix could be used to identify the region 378 where the customer is located. In such environment the IPv6 source 379 address could be used by the Edge nodes of the network to steer 380 traffic and forward it through a specific path other than the optimal 381 path. 383 The need to setup a source-based path, going through some specific 384 middle/intermediate points in the network may be related to different 385 requirements: 387 o The operator may want to be able to use some high bandwidth links 388 for specific type of traffic (like video) avoiding the need for 389 over-dimensioning all the links of the network; 391 o The operator may want to be able to setup a specific path for 392 delay sensitive applications; 394 o The operator may have the need to be able to select one (or 395 multiple) specific exit point(s) at peering points when different 396 peering points are available; 398 o The operator may have the need to be able to setup a source based 399 path for specific services in order to be able to reach some 400 servers hosted in some facilities not always reachable through the 401 optimal path; 403 o The operator may have the need to be able to provision guaranteed 404 disjoint paths (so-called dual-plane network) for diversity 405 purposes 407 All these scenarios would require a form of traffic engineering 408 capabilities in IP core networks not running MPLS and not willing to 409 run it. 411 IPv4 protocol does not provide such functionalities today and it is 412 not the intent of this document to address the IPv4 scenario, both 413 because this may create a lot of backward compatibility issues with 414 currently deployed networks and for the security issues that may 415 raise. 417 The described use cases could be addressed with the SPRING 418 architecture by having the Edge nodes of network to impose a Segment 419 List on specific traffic flows, based on certain classification 420 criteria that would include source IPv6 address. 422 3. Acknowledgements 424 The authors would like to thank Brian Field, Robert Raszuk, Wes 425 George, John G. Scudder and Yakov Rekhter for their valuable 426 comments and inputs to this document. 428 4. IANA Considerations 430 This document does not require any action from IANA. 432 5. Security Considerations 434 There are a number of security concerns with source routing at the IP 435 layer [RFC5095]. The new IPv6-based routing header will be defined 436 in way that blind attacks are never possible, i.e., attackers will be 437 unable to send source routed packets that get successfully processed, 438 without being part of the negations for setting up the source routes 439 or being able to eavesdrop legitimate source routed packets. In some 440 networks this base level security may be complemented with other 441 mechanisms, such as packet filtering, cryptographic security, etc. 443 6. Informative References 445 [I-D.bhandari-dhc-class-based-prefix] 446 Systems, C., Halwasia, G., Gundavelli, S., Deng, H., 447 Thiebaut, L., Korhonen, J., and I. Farrer, "DHCPv6 class 448 based prefix", draft-bhandari-dhc-class-based-prefix-05 449 (work in progress), July 2013. 451 [I-D.filsfils-spring-segment-routing] 452 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 453 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 454 Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, 455 "Segment Routing Architecture", draft-filsfils-spring- 456 segment-routing-04 (work in progress), July 2014. 458 [I-D.filsfils-spring-segment-routing-mpls] 459 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 460 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 461 Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, 462 "Segment Routing with MPLS data plane", draft-filsfils- 463 spring-segment-routing-mpls-03 (work in progress), August 464 2014. 466 [I-D.ietf-mpls-ipv6-only-gap] 467 George, W. and C. Pignataro, "Gap Analysis for Operating 468 IPv6-only MPLS Networks", draft-ietf-mpls-ipv6-only-gap-02 469 (work in progress), August 2014. 471 [I-D.ietf-mpls-seamless-mpls] 472 Leymann, N., Decraene, B., Filsfils, C., Konstantynowicz, 473 M., and D. Steinberg, "Seamless MPLS Architecture", draft- 474 ietf-mpls-seamless-mpls-07 (work in progress), June 2014. 476 [I-D.ietf-sfc-dc-use-cases] 477 Surendra, S., Tufail, M., Majee, S., Captari, C., and S. 478 Homma, "Service Function Chaining Use Cases In Data 479 Centers", draft-ietf-sfc-dc-use-cases-01 (work in 480 progress), July 2014. 482 [I-D.ietf-sfc-problem-statement] 483 Quinn, P. and T. Nadeau, "Service Function Chaining 484 Problem Statement", draft-ietf-sfc-problem-statement-10 485 (work in progress), August 2014. 487 [I-D.ietf-spring-problem-statement] 488 Previdi, S., Filsfils, C., Decraene, B., Litkowski, S., 489 Horneffer, M., and R. Shakir, "SPRING Problem Statement 490 and Requirements", draft-ietf-spring-problem-statement-03 491 (work in progress), October 2014. 493 [I-D.lepape-6man-prefix-metadata] 494 Pape, M., Systems, C., and I. Farrer, "IPv6 Prefix Meta- 495 data and Usage", draft-lepape-6man-prefix-metadata-00 496 (work in progress), July 2013. 498 [I-D.previdi-6man-segment-routing-header] 499 Previdi, S., Filsfils, C., Field, B., and I. Leung, "IPv6 500 Segment Routing Header (SRH)", draft-previdi-6man-segment- 501 routing-header-03 (work in progress), October 2014. 503 [I-D.quinn-sfc-nsh] 504 Quinn, P., Guichard, J., Fernando, R., Surendra, S., 505 Smith, M., Yadav, N., Agarwal, P., Manur, R., Chauhan, A., 506 Elzur, U., Garg, P., McConnell, B., and C. Wright, 507 "Network Service Header", draft-quinn-sfc-nsh-03 (work in 508 progress), July 2014. 510 [I-D.troan-homenet-sadr] 511 Troan, O. and L. Colitti, "IPv6 Multihoming with Source 512 Address Dependent Routing (SADR)", draft-troan-homenet- 513 sadr-01 (work in progress), September 2013. 515 [RFC4798] De Clercq, J., Ooms, D., Prevost, S., and F. Le Faucheur, 516 "Connecting IPv6 Islands over IPv4 MPLS Using IPv6 517 Provider Edge Routers (6PE)", RFC 4798, February 2007. 519 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 520 of Type 0 Routing Headers in IPv6", RFC 5095, December 521 2007. 523 Authors' Addresses 525 John Brzozowski 526 Comcast 528 Email: john_brzozowski@cable.comcast.com 530 John Leddy 531 Comcast 533 Email: John_Leddy@cable.comcast.com 535 Ida Leung 536 Rogers Communications 537 8200 Dixie Road 538 Brampton, ON L6T 0C1 539 CANADA 541 Email: Ida.Leung@rci.rogers.com 543 Stefano Previdi 544 Cisco Systems 545 Via Del Serafico, 200 546 Rome 00142 547 Italy 549 Email: sprevidi@cisco.com 551 Mark Townsley 552 Cisco Systems 554 Email: townsley@cisco.com 556 Christian Martin 557 Cisco Systems 559 Email: martincj@cisco.com 560 Clarence Filsfils 561 Cisco Systems 562 Brussels 563 BE 565 Email: cfilsfil@cisco.com 567 Roberta Maglione (editor) 568 Cisco Systems 569 Via Torri Bianche 8 570 Vimercate 20871 571 Italy 573 Email: robmgl@cisco.com