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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DMM Working Group A. Yegin 3 Internet-Draft Actility 4 Intended status: Informational D. Moses 5 Expires: January 31, 2020 Intel 6 S. Jeon 7 Sungkyunkwan University 8 July 30, 2019 10 On Demand Mobility Management 11 draft-ietf-dmm-ondemand-mobility-18 13 Abstract 15 Applications differ with respect to whether they need session 16 continuity and/or IP address reachability. The network providing the 17 same type of service to any mobile host and any application running 18 on the host yields inefficiencies, as described in [RFC7333]. This 19 document defines a new concep of enabling applications to influence 20 the network's mobility services (session continuity and/or IP address 21 reachability) on a per-Socket basis, and suggests extensions to the 22 networking stack's API to accomodate this concept. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at https://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on January 31, 2020. 41 Copyright Notice 43 Copyright (c) 2019 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (https://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 59 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 4 60 3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 3.1. High-level Description . . . . . . . . . . . . . . . . . 4 62 3.2. Types of IP Addresses . . . . . . . . . . . . . . . . . . 5 63 3.3. Granularity of Selection . . . . . . . . . . . . . . . . 6 64 3.4. On Demand Nature . . . . . . . . . . . . . . . . . . . . 6 65 4. Backwards Compatibility Considerations . . . . . . . . . . . 7 66 4.1. Applications . . . . . . . . . . . . . . . . . . . . . . 8 67 4.2. IP Stack in the Mobile Host . . . . . . . . . . . . . . . 8 68 4.3. Network Infrastructure . . . . . . . . . . . . . . . . . 8 69 4.4. Merging this work with RFC5014 . . . . . . . . . . . . . 8 70 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 71 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 72 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10 73 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 74 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 75 9.1. Normative References . . . . . . . . . . . . . . . . . . 10 76 9.2. Informative References . . . . . . . . . . . . . . . . . 11 77 Appendix A. Conveying the Desired Address Type . . . . . . . . . 11 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 80 1. Introduction 82 In the context of Mobile IP [RFC5563][RFC6275][RFC5213][RFC5944], the 83 following two attributes are defined for IP service provided to 84 mobile hosts: 86 - Session Continuity 88 The ability to maintain an ongoing transport interaction by keeping 89 the same local end-point IP address throughout the life-time of the 90 IP socket despite the mobile host changing its point of attachment 91 within the IP network topology. The IP address of the host may 92 change after closing the IP socket and before opening a new one, but 93 that does not jeopardize the ability of applications using these IP 94 sockets to work flawlessly. Session continuity is essential for 95 mobile hosts to maintain ongoing flows without any interruption. 97 - IP Address Reachability 99 The ability to maintain the same IP address for an extended period of 100 time. The IP address stays the same across independent sessions, and 101 even in the absence of any session. The IP address may be published 102 in a long-term registry (e.g., DNS), and is made available for 103 serving incoming (e.g., TCP) connections. IP address reachability is 104 essential for mobile hosts to use specific/published IP addresses. 106 Mobile IP is designed to provide both session continuity and IP 107 address reachability to mobile hosts. Architectures utilizing these 108 protocols (e.g., 3GPP, 3GPP2, WIMAX) ensure that any mobile host 109 attached to the compliant networks can enjoy these benefits. Any 110 application running on these mobile hosts is subjected to the same 111 treatment with respect to session continuity and IP address 112 reachability. 114 Achieving session continuity and IP address reachability with Mobile 115 IP incurs some cost. Mobile IP protocol forces the mobile host's IP 116 traffic to traverse a centrally-located router (Home Agent, HA), 117 which incurs additional transmission latency and use of additional 118 network resources, adds to the network CAPEX and OPEX, and decreases 119 the reliability of the network due to the introduction of a single 120 point of failure [RFC7333]. Therefore, session continuity and IP 121 address reachability SHOULD be provided only when necessary. 123 In reality not every application may need these benefits. IP address 124 reachability is required for applications running as servers (e.g., a 125 web server running on the mobile host). But, a typical client 126 application (e.g., web browser) does not necessarily require IP 127 address reachability. Similarly, session continuity is not required 128 for all types of applications either. Applications performing brief 129 communication (e.g., text messaging) can survive without having 130 session continuity support. 132 Furthermore, when an application needs session continuity, it may be 133 able to satisfy that need by using a solution above the IP layer, 134 such as MPTCP [RFC6824], SIP mobility [RFC3261], or an application- 135 layer mobility solution. These higher-layer solutions are not 136 subject to the same issues that arise with the use of Mobile IP since 137 they can utilize the most direct data path between the end-points. 138 But, if Mobile IP is being applied to the mobile host, the higher- 139 layer protocols are rendered useless because their operation is 140 inhibited by Mobile IP. Since Mobile IP ensures that the IP address 141 of the mobile host remains fixed (despite the location and movement 142 of the mobile host), the higher-layer protocols never detect the IP- 143 layer change and never engage in mobility management. 145 This document proposes a solution for applications running on mobile 146 hosts to indicate when establishing the network connection ('on 147 demand') whether they need session continuity or IP address 148 reachability. The network protocol stack on the mobile host, in 149 conjunction with the network infrastructure, provides the required 150 type of service. It is for the benefit of both the users and the 151 network operators not to engage an extra level of service unless it 152 is absolutely necessary. It is expected that applications and 153 networks compliant with this specification will utilize this solution 154 to use network resources more efficiently. 156 2. Notational Conventions 158 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 159 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 160 "OPTIONAL" in this document are to be interpreted as described in BCP 161 14 , [RFC2119] [RFC8174] when, they appear in all capitals, as shown 162 here. 164 3. Solution 166 3.1. High-level Description 168 Enabling applications to indicate their mobility service requirements 169 e.g. session continuity and/or IP address reachability, comprises the 170 following steps: 172 - The application indicates to the network stack (local to the mobile 173 host) the desired mobility service. 175 - The network stack assigns a source IP address based on an IP prefix 176 with the desired services that was previously provided by the 177 network. If such an IP prefix is not available, the network stack 178 performs the additional steps below. 180 - The network stack sends a request to the network for a new source 181 IP prefix that is associated with the desired mobility service. 183 - The network responds with the suitable allocated source IP prefix 184 (or responds with a failure indication). 186 - If the suitable source IP prefix was allocates, the network stack 187 constructs a source IP address and provides it to the application. 189 This document specifies the new address types associated with 190 mobility services and details the interaction between the 191 applications and the network stack steps. It uses the Socket 192 interface as an example for an API between applications and the 193 network stack. Other steps are outside the scope of this document. 195 3.2. Types of IP Addresses 197 Four types of IP addresses are defined with respect to mobility 198 management. 200 - Fixed IP Address 202 A Fixed IP address is an address with a guarantee to be valid for a 203 very long time, regardless of whether it is being used in any packet 204 to/from the mobile host, or whether or not the mobile host is 205 connected to the network, or whether it moves from one point-of- 206 attachment to another (with a different IP prefix) while it is 207 connected. 209 Fixed IP addresses are required by applications that need both 210 session continuity and IP address reachability. 212 - Session-lasting IP Address 214 A session-lasting IP address is an address with a guarantee to be 215 valid throughout the life-time of the socket(s) for which it was 216 requested. It is guaranteed to be valid even after the mobile host 217 had moved from one point-of-attachment to another (with a different 218 IP prefix). 220 Session-lasting IP addresses are required by applications that need 221 session continuity but do not need IP address reachability. 223 - Non-persistent IP Address 225 This type of IP address has no guarantee to exist after a mobile host 226 moves from one point-of-attachment to another, and therefore, no 227 session continuity nor IP address reachability are provided. The IP 228 address is created from an IP prefix that is obtained from the 229 serving IP gateway and is not maintained across gateway changes. In 230 other words, the IP prefix may be released and replaced by a new one 231 when the IP gateway changes due to the movement of the mobile host 232 forcing the creation of a new source IP address with the updated 233 allocated IP prefix. 235 - Graceful Replacement IP Address 237 In some cases, the network cannot guarantee the validity of the 238 provided IP prefix throughout the duration of the opened socket, but 239 can provide a limited graceful period of time in which both the 240 original IP prefix and a new one are valid. This enables the 241 application some flexibility in the transition from the existing 242 source IP address to the new one. 244 This gracefulness is still better than the non-persistence type of 245 address for applications that can handle a change in their source IP 246 address but require that extra flexibility. 248 Applications running as servers at a published IP address require a 249 Fixed IP Address. Long-standing applications (e.g., an SSH session) 250 may also require this type of address. Enterprise applications that 251 connect to an enterprise network via virtual LAN require a Fixed IP 252 Address. 254 Applications with short-lived transient sessions can use Session- 255 lasting IP Addresses. For example: Web browsers. 257 Applications with very short sessions, such as DNS clients and 258 instant messengers, can utilize Non-persistent IP Addresses. Even 259 though they could very well use Fixed or Session-lasting IP 260 Addresses, the transmission latency would be minimized when a Non- 261 persistent IP Addresses are used. 263 Applications that can tolerate a short interruption in connectivity 264 can use the Graceful-replacement IP addresses. For example, a 265 streaming client that has buffering capabilities. 267 3.3. Granularity of Selection 269 IP address type selection is made on a per-socket granularity. 270 Different parts of the same application may have different needs. 271 For example, the control-plane of an application may require a Fixed 272 IP Address in order to stay reachable, whereas the data-plane of the 273 same application may be satisfied with a Session-lasting IP Address. 275 3.4. On Demand Nature 277 At any point in time, a mobile host may have a combination of IP 278 addresses configured. Zero or more Fixed, zero or more Session- 279 lasting, zero or more Non-persistent and zero or more Graceful- 280 Replacement IP addresses may be configured by the IP stack of the 281 host. The combination may be as a result of the host policy, 282 application demand, or a mix of the two. 284 When an application requires a specific type of IP address and such 285 an address is not already configured on the host, the IP stack SHALL 286 attempt to configure one. For example, a host may not always have a 287 Session-lasting IP address available. When an application requests 288 one, the IP stack SHALL make an attempt to configure one by issuing a 289 request to the network. If the operation fails, the IP stack SHALL 290 fail the associated socket request and return an error. If 291 successful, a Session-lasting IP Address gets configured on the 292 mobile host. If another socket requests a Session-lasting IP address 293 at a later time, the same IP address may be served to that socket as 294 well. When the last socket using the same configured IP address is 295 closed, the IP address may be released or kept for future 296 applications that may be launched and require a Session-lasting IP 297 address. 299 In some cases it might be preferable for the mobile host to request a 300 new Session-lasting IP address for a new opening of an IP socket 301 (even though one was already assigned to the mobile host by the 302 network and might be in use in a different, already active IP 303 sockets). It is outside the scope of this specification to define 304 criteria for choosing to use available addresses or choosing to 305 request new ones. It supports both alternatives (and any 306 combination). 308 It is outside the scope of this specification to define how the host 309 requests a specific type of prefix and how the network indicates the 310 type of prefix in its advertisement or in its reply to a request. 312 The following are matters of policy, which may be dictated by the 313 host itself, the network operator, or the system architecture 314 standard: 316 - The initial set of IP addresses configured on the host at boot 317 time. 319 - Permission to grant various types of IP addresses to a requesting 320 application. 322 - Determination of a default address type when an application does 323 not make any explicit indication, whether it already supports the 324 required API or it is just a legacy application. 326 4. Backwards Compatibility Considerations 328 Backwards compatibility support is REQUIRED by the following 3 types 329 of entities: 331 - The Applications on the mobile host 333 - The IP stack in the mobile host 335 - The network infrastructure 337 4.1. Applications 339 Legacy applications that do not support the On-Demand functionality 340 will use the legacy API and will not be able to take advantage of the 341 On-Demand Mobility feature. 343 Applications using the new On-Demand functionality should be aware 344 that they may be executed in legacy environments that do not support 345 it. Such environments may include a legacy IP stack on the mobile 346 host, legacy network infrastructure, or both. In either case, the 347 API will return an error code and the invoking applications may just 348 give up and use legacy calls. 350 4.2. IP Stack in the Mobile Host 352 New IP stacks (that implement On Demand functionality) MUST continue 353 to support all legacy operations. If an application does not use On- 354 Demand functionality, the IP stack MUST respond in a legacy manner. 356 If the network infrastructure supports On-Demand functionality, the 357 IP stack SHOULD follow the application request: If the application 358 requests a specific address type, the stack SHOULD forward this 359 request to the network. If the application does not request an 360 address type, the IP stack MUST NOT request an address type and leave 361 it to the network's default behavior to choose the type of the 362 allocated IP prefix. If an IP prefix was already allocated to the 363 host, the IP stack uses it and may not request a new one from the 364 network. 366 4.3. Network Infrastructure 368 The network infrastructure may or may not support the On-Demand 369 functionality. How the IP stack on the host and the network 370 infrastructure behave in case of a compatibility issue is outside the 371 scope of this API specification. 373 4.4. Merging this work with RFC5014 375 [RFC5014] defines new flags that may be used with setsockopt() to 376 influence source IP address selection for a socket. The list of 377 flags include: source home address, care-of address, temporary 378 address, public address CGA (Cryptographically Created Address) and 379 non-CGA. When applications require session continuity service, they 380 SHOULD NOT set the flags specified in [RFC5014]. 382 However, if an application erroneously performs a combination of (1) 383 Use setsockopt() to set a specific option (using one of the flags 384 specified in [RFC5014]) and (2) Selects a source IP address type, the 385 IP stack will fulfill the request specified by (2) and ignore the 386 flags set by (1). 388 5. Security Considerations 390 The different service types (session continuity types and address 391 reachability) associated with the allocated IP address types, may be 392 associated with different costs. The cost to the operator for 393 enabling a type of service, and the cost to applications using a 394 selected service. A malicious application may use these to generate 395 extra billing of a mobile subscriber, and/or impose costly services 396 on the mobile operator. When costly services are limited, malicious 397 applications may exhaust them, preventing other applications on the 398 same mobile host from being able to use them. 400 Mobile hosts that enables such service options, should provide 401 capabilities for ensuring that only authorized applications can use 402 the costly (or limited) service types. 404 The ability to select service types requires the exchange of the 405 association of source IP prefixes and their corresponding service 406 types, between the mobile host and mobile network. Exposing these 407 associations may provide information to passive attackers even if the 408 traffic that is used with these addressed is encrypted. 410 To avoid profiling an application according to the type of IP 411 addresses, it is expected that prefixes provided by the mobile 412 operator are associated to various type of addresses over time. As a 413 result, the type of address could not be associated to the prefix, 414 making application profiling based on the type of address harder. 416 The application or the OS should ensure that IP addresses regularly 417 change to limit IP tracking by a passive observer. The application 418 should regularly set the On Demand flag. The application should be 419 able to ensure that session lasting IP addresses are regularly 420 changed by setting a lifetime for example handled by the application. 421 In addition, the application should consider the use of graceful 422 replacement IP addresses. 424 Similarly, the OS may also associated IP addresses with a lifetime. 425 Upon receiving a request for a given type of IP address, after some 426 time, the OS should request a new address to the network even if it 427 already has one IP address available with the requested type. This 428 includes any type of IP address. IP addresses of type graceful 429 replacement or non persistent should be regularly renewed by the OS. 431 The lifetime of an IP address may be expressed in number of seconds 432 or in number of bytes sent through this IP address. 434 6. IANA Considerations 436 This document has no IANA considerations. 438 7. Contributors 440 This document was merged with [I-D.sijeon-dmm-use-cases-api-source]. 441 We would like to acknowledge the contribution of the following people 442 to that document as well: 444 Sergio Figueiredo 445 Altran Research, France 446 Email: sergio.figueiredo@altran.com 448 Younghan Kim 449 Soongsil University, Korea 450 Email: younghak@ssu.ac.kr 452 John Kaippallimalil 453 Huawei, USA 454 Email: john.kaippallimalil@huawei.com 456 8. Acknowledgements 458 We would like to thank Wu-chi Feng, Alexandru Petrescu, Jouni 459 Korhonen, Sri Gundavelli, Dave Dolson Lorenzo Colitti and Daniel 460 Migault for their valuable comments and suggestions on this work. 462 9. References 464 9.1. Normative References 466 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 467 Requirement Levels", BCP 14, RFC 2119, 468 DOI 10.17487/RFC2119, March 1997, 469 . 471 [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 472 Socket API for Source Address Selection", RFC 5014, 473 DOI 10.17487/RFC5014, September 2007, 474 . 476 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 477 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 478 May 2017, . 480 9.2. Informative References 482 [I-D.sijeon-dmm-use-cases-api-source] 483 Jeon, S., Figueiredo, S., Kim, Y., and J. Kaippallimalil, 484 "Use Cases and API Extension for Source IP Address 485 Selection", draft-sijeon-dmm-use-cases-api-source-07 (work 486 in progress), September 2017. 488 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 489 A., Peterson, J., Sparks, R., Handley, M., and E. 490 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 491 DOI 10.17487/RFC3261, June 2002, 492 . 494 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 495 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 496 RFC 5213, DOI 10.17487/RFC5213, August 2008, 497 . 499 [RFC5563] Leung, K., Dommety, G., Yegani, P., and K. Chowdhury, 500 "WiMAX Forum / 3GPP2 Proxy Mobile IPv4", RFC 5563, 501 DOI 10.17487/RFC5563, February 2010, 502 . 504 [RFC5944] Perkins, C., Ed., "IP Mobility Support for IPv4, Revised", 505 RFC 5944, DOI 10.17487/RFC5944, November 2010, 506 . 508 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 509 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 510 2011, . 512 [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, 513 "TCP Extensions for Multipath Operation with Multiple 514 Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, 515 . 517 [RFC7333] Chan, H., Ed., Liu, D., Seite, P., Yokota, H., and J. 518 Korhonen, "Requirements for Distributed Mobility 519 Management", RFC 7333, DOI 10.17487/RFC7333, August 2014, 520 . 522 Appendix A. Conveying the Desired Address Type 524 Following are some suggestions of possible extensions to the Socket 525 API for enabling applications to convey their session continuity and 526 address reachability requirements. 528 [RFC5014] introduced the ability of applications to influence the 529 source address selection with the IPV6_ADDR_PREFERENCE option at the 530 IPPROTO_IPV6 level. This option is used with setsockopt() and 531 getsockopt() calls to set/get address selection preferences. 533 One alternative is to extend the defintion of the IPV6_ADDR_REFERENCE 534 opion with flags that express the invoker's desire. An "OnDeman" 535 field could contains one of the values: FIXED_IP_ADDRESS, 536 SESSION_LASTING_IP_ADDRESS, NON_PERSISTENT_IP_ADDRESS or 537 GRACEFUL_REPLACEMENT_IP_ADDRESS. 539 Another alternative is to define a new Socket function used by the 540 invoker to convey its desire. This enables the implementation of two 541 behaviors of Socket functions: The existing "setsockotp()" is a 542 function that returns after executing, and the new "setsc()" (Set 543 Service Contionuity) function that may initaite a request for the 544 desired service, and wait until the network responds with the 545 allocated resources, before returning to the invoker. 547 After obtaining an IP address with the desired behavior the 548 application can call the bind() Socket function to associate that 549 received IP address with the socket. 551 Authors' Addresses 553 Alper Yegin 554 Actility 555 Istanbul 556 Turkey 558 Email: alper.yegin@actility.com 560 Danny Moses 561 Intel Corporation 562 Petah Tikva 563 Israel 565 Email: danny.moses@intel.com 567 Seil Jeon 568 Sungkyunkwan University 569 Suwon 570 South Korea 572 Email: seiljeon@skku.edu