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Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 6824 (Obsoleted by RFC 8684) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). 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: August 26, 2019 Intel 6 S. Jeon 7 Sungkyunkwan University 8 February 22, 2019 10 On Demand Mobility Management 11 draft-ietf-dmm-ondemand-mobility-17 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 August 26, 2019. 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 3.5. Conveying the Desired Address Type . . . . . . . . . . . 7 66 4. Usage example . . . . . . . . . . . . . . . . . . . . . . . . 8 67 4.1. Pseudo-code example . . . . . . . . . . . . . . . . . . . 8 68 4.2. Message Flow example . . . . . . . . . . . . . . . . . . 10 69 5. Backwards Compatibility Considerations . . . . . . . . . . . 12 70 5.1. Applications . . . . . . . . . . . . . . . . . . . . . . 12 71 5.2. IP Stack in the Mobile Host . . . . . . . . . . . . . . . 12 72 5.3. Network Infrastructure . . . . . . . . . . . . . . . . . 13 73 5.4. Merging this work with RFC5014 . . . . . . . . . . . . . 13 74 6. Summary of New Definitions . . . . . . . . . . . . . . . . . 13 75 6.1. New APIs . . . . . . . . . . . . . . . . . . . . . . . . 13 76 6.2. New Flags . . . . . . . . . . . . . . . . . . . . . . . . 14 77 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 78 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 79 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 80 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 81 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 82 11.1. Normative References . . . . . . . . . . . . . . . . . . 16 83 11.2. Informative References . . . . . . . . . . . . . . . . . 17 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 86 1. Introduction 88 In the context of Mobile IP [RFC5563][RFC6275][RFC5213][RFC5944], the 89 following two attributes are defined for IP service provided to 90 mobile hosts: 92 - Session Continuity 94 The ability to maintain an ongoing transport interaction by keeping 95 the same local end-point IP address throughout the life-time of the 96 IP socket despite the mobile host changing its point of attachment 97 within the IP network topology. The IP address of the host may 98 change after closing the IP socket and before opening a new one, but 99 that does not jeopardize the ability of applications using these IP 100 sockets to work flawlessly. Session continuity is essential for 101 mobile hosts to maintain ongoing flows without any interruption. 103 - IP Address Reachability 105 The ability to maintain the same IP address for an extended period of 106 time. The IP address stays the same across independent sessions, and 107 even in the absence of any session. The IP address may be published 108 in a long-term registry (e.g., DNS), and is made available for 109 serving incoming (e.g., TCP) connections. IP address reachability is 110 essential for mobile hosts to use specific/published IP addresses. 112 Mobile IP is designed to provide both session continuity and IP 113 address reachability to mobile hosts. Architectures utilizing these 114 protocols (e.g., 3GPP, 3GPP2, WIMAX) ensure that any mobile host 115 attached to the compliant networks can enjoy these benefits. Any 116 application running on these mobile hosts is subjected to the same 117 treatment with respect to session continuity and IP address 118 reachability. 120 Achieving session continuity and IP address reachability with Mobile 121 IP incurs some cost. Mobile IP protocol forces the mobile host's IP 122 traffic to traverse a centrally-located router (Home Agent, HA), 123 which incurs additional transmission latency and use of additional 124 network resources, adds to the network CAPEX and OPEX, and decreases 125 the reliability of the network due to the introduction of a single 126 point of failure [RFC7333]. Therefore, session continuity and IP 127 address reachability SHOULD be provided only when necessary. 129 In reality not every application may need these benefits. IP address 130 reachability is required for applications running as servers (e.g., a 131 web server running on the mobile host). But, a typical client 132 application (e.g., web browser) does not necessarily require IP 133 address reachability. Similarly, session continuity is not required 134 for all types of applications either. Applications performing brief 135 communication (e.g., text messaging) can survive without having 136 session continuity support. 138 Furthermore, when an application needs session continuity, it may be 139 able to satisfy that need by using a solution above the IP layer, 140 such as MPTCP [RFC6824], SIP mobility [RFC3261], or an application- 141 layer mobility solution. These higher-layer solutions are not 142 subject to the same issues that arise with the use of Mobile IP since 143 they can utilize the most direct data path between the end-points. 144 But, if Mobile IP is being applied to the mobile host, the higher- 145 layer protocols are rendered useless because their operation is 146 inhibited by Mobile IP. Since Mobile IP ensures that the IP address 147 of the mobile host remains fixed (despite the location and movement 148 of the mobile host), the higher-layer protocols never detect the IP- 149 layer change and never engage in mobility management. 151 This document proposes a solution for applications running on mobile 152 hosts to indicate when establishing the network connection ('on 153 demand') whether they need session continuity or IP address 154 reachability. The network protocol stack on the mobile host, in 155 conjunction with the network infrastructure, provides the required 156 type of service. It is for the benefit of both the users and the 157 network operators not to engage an extra level of service unless it 158 is absolutely necessary. It is expected that applications and 159 networks compliant with this specification will utilize this solution 160 to use network resources more efficiently. 162 2. Notational Conventions 164 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 165 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 166 "OPTIONAL" in this document are to be interpreted as described in BCP 167 14 , [RFC2119] [RFC8174] when, they appear in all capitals, as shown 168 here. 170 3. Solution 172 3.1. High-level Description 174 Enabling applications to indicate their mobility service requirements 175 e.g. session continuity and/or IP address reachability, comprises the 176 following steps: 178 - The application indicates to the network stack (local to the mobile 179 host) the desired mobility service. 181 - The network stack assigns a source IP address based on an IP prefix 182 with the desired services that was previously provided by the 183 network. If such an IP prefix is not available, the network stack 184 performs the additional steps below. 186 - The network stack sends a request to the network for a new source 187 IP prefix that is associated with the desired mobility service. 189 - The network responds with the suitable allocated source IP prefix 190 (or responds with a failure indication). 192 - If the suitable source IP prefix was allocates, the network stack 193 constructs a source IP address and provides it to the application. 195 This document specifies the new address types associated with 196 mobility services and details the interaction between the 197 applications and the network stack steps. It uses the Socket 198 interface as an example for an API between applications and the 199 network stack. Other steps are outside the scope of this document. 201 3.2. Types of IP Addresses 203 Four types of IP addresses are defined with respect to mobility 204 management. 206 - Fixed IP Address 208 A Fixed IP address is an address with a guarantee to be valid for a 209 very long time, regardless of whether it is being used in any packet 210 to/from the mobile host, or whether or not the mobile host is 211 connected to the network, or whether it moves from one point-of- 212 attachment to another (with a different IP prefix) while it is 213 connected. 215 Fixed IP addresses are required by applications that need both 216 session continuity and IP address reachability. 218 - Session-lasting IP Address 220 A session-lasting IP address is an address with a guarantee to be 221 valid throughout the life-time of the socket(s) for which it was 222 requested. It is guaranteed to be valid even after the mobile host 223 had moved from one point-of-attachment to another (with a different 224 IP prefix). 226 Session-lasting IP addresses are required by applications that need 227 session continuity but do not need IP address reachability. 229 - Non-persistent IP Address 231 This type of IP address has no guarantee to exist after a mobile host 232 moves from one point-of-attachment to another, and therefore, no 233 session continuity nor IP address reachability are provided. The IP 234 address is created from an IP prefix that is obtained from the 235 serving IP gateway and is not maintained across gateway changes. In 236 other words, the IP prefix may be released and replaced by a new one 237 when the IP gateway changes due to the movement of the mobile host 238 forcing the creation of a new source IP address with the updated 239 allocated IP prefix. 241 - Graceful Replacement IP Address 243 In some cases, the network cannot guarantee the validity of the 244 provided IP prefix throughout the duration of the opened socket, but 245 can provide a limited graceful period of time in which both the 246 original IP prefix and a new one are valid. This enables the 247 application some flexibility in the transition from the existing 248 source IP address to the new one. 250 This gracefulness is still better than the non-persistence type of 251 address for applications that can handle a change in their source IP 252 address but require that extra flexibility. 254 Applications running as servers at a published IP address require a 255 Fixed IP Address. Long-standing applications (e.g., an SSH session) 256 may also require this type of address. Enterprise applications that 257 connect to an enterprise network via virtual LAN require a Fixed IP 258 Address. 260 Applications with short-lived transient sessions can use Session- 261 lasting IP Addresses. For example: Web browsers. 263 Applications with very short sessions, such as DNS clients and 264 instant messengers, can utilize Non-persistent IP Addresses. Even 265 though they could very well use Fixed or Session-lasting IP 266 Addresses, the transmission latency would be minimized when a Non- 267 persistent IP Addresses are used. 269 Applications that can tolerate a short interruption in connectivity 270 can use the Graceful-replacement IP addresses. For example, a 271 streaming client that has buffering capabilities. 273 3.3. Granularity of Selection 275 IP address type selection is made on a per-socket granularity. 276 Different parts of the same application may have different needs. 277 For example, the control-plane of an application may require a Fixed 278 IP Address in order to stay reachable, whereas the data-plane of the 279 same application may be satisfied with a Session-lasting IP Address. 281 3.4. On Demand Nature 283 At any point in time, a mobile host may have a combination of IP 284 addresses configured. Zero or more Fixed, zero or more Session- 285 lasting, zero or more Non-persistent and zero or more Graceful- 286 Replacement IP addresses may be configured by the IP stack of the 287 host. The combination may be as a result of the host policy, 288 application demand, or a mix of the two. 290 When an application requires a specific type of IP address and such 291 an address is not already configured on the host, the IP stack SHALL 292 attempt to configure one. For example, a host may not always have a 293 Session-lasting IP address available. When an application requests 294 one, the IP stack SHALL make an attempt to configure one by issuing a 295 request to the network (see Section 3.5 below for more details). If 296 the operation fails, the IP stack SHALL fail the associated socket 297 request and return an error. If successful, a Session-lasting IP 298 Address gets configured on the mobile host. If another socket 299 requests a Session-lasting IP address at a later time, the same IP 300 address may be served to that socket as well. When the last socket 301 using the same configured IP address is closed, the IP address may be 302 released or kept for future applications that may be launched and 303 require a Session-lasting IP address. 305 In some cases it might be preferable for the mobile host to request a 306 new Session-lasting IP address for a new opening of an IP socket 307 (even though one was already assigned to the mobile host by the 308 network and might be in use in a different, already active IP 309 sockets). It is outside the scope of this specification to define 310 criteria for choosing to use available addresses or choosing to 311 request new ones. It supports both alternatives (and any 312 combination). 314 It is outside the scope of this specification to define how the host 315 requests a specific type of prefix and how the network indicates the 316 type of prefix in its advertisement or in its reply to a request. 318 The following are matters of policy, which may be dictated by the 319 host itself, the network operator, or the system architecture 320 standard: 322 - The initial set of IP addresses configured on the host at boot 323 time. 325 - Permission to grant various types of IP addresses to a requesting 326 application. 328 - Determination of a default address type when an application does 329 not make any explicit indication, whether it already supports the 330 required API or it is just a legacy application. 332 3.5. Conveying the Desired Address Type 334 [RFC5014] introduced the ability of applications to influence the 335 source address selection with the IPV6_ADDR_PREFERENCE option at the 336 IPPROTO_IPV6 level. This option is used with setsockopt() and 337 getsockopt() calls to set/get address selection preferences. 339 Extending this further by adding more flags does not work when a 340 request for an address of a certain type results in requiring the IP 341 stack to wait for the network to provide the desired source IP prefix 342 and hence causing the setsockopt() call to block until the prefix is 343 allocated (or an error indication from the network is received). 345 Alternatively a new socket API is defined - setsc() which allows 346 applications to express their desired type of session continuity 347 service. The new setsc() API will return an IPv6 address that is 348 associated with the desired session continuity service and with 349 status information indicating whether or not the desired service was 350 provided. 352 An application that wishes to secure a desired service will call 353 setsc() with the service type definition and a place to contain the 354 provided IP address, and call bind() to associate that IP address 355 with the socket (See pseudo-code example in Section 4 below). 357 When the IP stack is required to use a source IP address of a 358 specified type, it can use an existing address, or request a new IP 359 prefix (of the same type) from the network and create a new one. If 360 the host does not already have an IPv6 prefix of that specific type, 361 it MUST request one from the network. 363 Using an existing address from an existing prefix is faster but might 364 yield a less optimal route (if a hand-off event occurred after its 365 configuration). On the other hand, acquiring a new IP prefix from 366 the network may be slower due to signaling exchange with the network. 368 Applications can control the stack's operation by setting a new flag 369 - ON_NET flag - which directs the IP stack whether to use a 370 preconfigured source IP address (if exists) or to request a new IPv6 371 prefix from the current serving network and configure a new IP 372 address. 374 This new flag is added to the set of flags in the 375 IPV6_ADDR_PREFERENCES option at the IPPROTO_IPV6 level. It is used 376 in setsockopt() to set the desired behavior. 378 4. Usage example 380 4.1. Pseudo-code example 382 The following example shows pseudo-code for creating a Stream socket 383 (TCP) with a Session-Lasting source IP address: 385 #include 386 #include 388 // Socket information 389 int s ; // socket id 391 // Source information (for setsc() and bind()) 392 sockaddr_in6 sourceInfo // my address and port for bind() 393 in6_addr sourceAddress // will contain the provisioned 394 // source IP address 395 uint8_t sc_type = IPV6_REQUIRE_SESSION_LASTING_IP ; 396 // For requesting a Session-Lasting 397 // source IP address 399 // Destination information (for connect()) 400 sockaddr_in6 serverInfo ; // server info for connect() 402 // Create an IPv6 TCP socket 403 s = socket(AF_INET6, SOCK_STREAM, 0) ; 404 if (s!=0) { 405 // Handle socket creation error 406 // ... 407 } // if socket creation failed 408 else { 409 // Socket creation is successful 410 // The application cannot connect yet, since it wants to use 411 // a Session-Lasting source IP address It needs to request 412 // the Session-Lasting source IP before connecting 413 if (setsc(s, &sourceAddress, &sc_type)) == 0){ 414 // setting session continuity to Session Lasting is 415 // Successful. sourceAddress now contains the Session- 416 // Lasting source IP address 418 // Bind to that source IP address 419 sourceInfo.sin6_family = AF_INET6 ; 420 sourceInfo.sin6_port = 0 // let the stack choose the port 421 sourceInfo.sin6_address = sourceAddress ; 422 // Use the source address that was 423 // generated by the setsc() call 424 if (bind(s, &sourceInfo, sizeof(sourceInfo))==0){ 425 // Set the desired server's information for connect() 426 serverInfo.sin6_family = AF_INET6 ; 427 serverInfo.sin6_port = SERVER_PORT_NUM ; 428 serverAddress.sin6_addr = SERVER_IPV6_ADDRESS ; 430 // Connect to the server 431 if (connect(s, &serverInfo, sizeof(serverInfo))==0) { 432 // connect successful (3-way handshake has been 433 // completed with Session-Lasting source address. 435 // Continue application functionality 436 // ... 437 } // if connect() is successful 438 else { 439 // connect failed 440 // ... 441 // Application code that handles connect failure and 442 // closes the socket 443 // ... 444 } // if connect() failed 445 } // if bind() successful 446 else { 447 // bind() failed 448 // ... 449 // Application code that handles bind failure and 450 // closes the socket 451 // ... 452 } // if bind() failed 453 } // if setsc() was successful and of a Session-Lasting 454 // source IP address was provided 455 else { 456 // application code that does not use Session-lasting IP 457 // address. The application may either connect without 458 // the desired Session-lasting service, or close the 459 // socket... 460 } // if setsc() failed 461 } // if socket was created successfully 463 // The rest of the application's code 464 // ... 466 4.2. Message Flow example 468 The following message flow illustrates a possible interaction for 469 achieving On-Demand functionality. It is an example of one scenario 470 and should not be regarded as the only scenario or the preferred one. 472 This flow describes the interaction between the following entities: 474 - Applications requiring different types of On-Demand service. 476 - The mobile host's IP stack. 478 - The network infrastructure providing the services. 480 In this example, the network infrastructure provides 2 IPv6 prefixes 481 upon attachment of the mobile host to the network: A Session-lasting 482 IPv6 prefix and a Non-persistent IPv6 prefix. Whenever the mobile 483 host moves to a different point-of-attachment, the network 484 infrastructure provides a new Non-persistent IPv6 address. 486 In this example, the network infrastructure does not support Fixed IP 487 addresses nor Graceful-replacement IP addresses. 489 Whenever an application opens an IP socket and requests a specific 490 IPv6 address type, the IP stack will provide one from its available 491 IPv6 prefixes or return an error message if the request cannot be 492 fulfilled. 494 Message Flow: 496 - The mobile device attaches to the network. 498 - The Network provides two IPv6 prefixes: PREFsl1 - a Session-lasting 499 IPv6 prefix and PREFnp1 - a Non-persistent IPv6 prefix. 501 - An application on the mobile host is launched. It opens an IP 502 socket and requests a Non-persistent IPv6 address. 504 - The IP stack provides IPnp1 which is generated from PREFnp1. 506 - Another application is launched, requesting a Non-persistent IPv6 507 address. 509 - The IP stack provides IPnp1 again. 511 - A third application is launched. This time, it requires a Session- 512 lasting IPv6 address. 514 - The IP stack provides IPsl1 which is generated from PREFsl1. 516 - The mobile hosts moves to a new point-of-attachment. 518 - The network provides a new Non-persistent IPv6 prefix - PREFnp2. 519 PREFnp1 is no longer valid. 521 - The applications that were given IPnp1 re-establish the socket and 522 receive a new IPv6 address - IPnp2 which is generated from PREFnp2 524 - The application that is using IPsl1 can still use it since the 525 network guaranteed that PREFsl1 will be valid even after moving to a 526 new point-of-attachment. 528 - A new application is launched, this time requiring a Graceful- 529 replacement IPv6 address. 531 - The IP stack returns setsc() with an error since the network does 532 not support this service. 534 - The application re-attempts to open a socket, this time requesting 535 a Session-lasting IPv6 address. 537 - The IP stack provides IPsl1. 539 5. Backwards Compatibility Considerations 541 Backwards compatibility support is REQUIRED by the following 3 types 542 of entities: 544 - The Applications on the mobile host 546 - The IP stack in the mobile host 548 - The network infrastructure 550 5.1. Applications 552 Legacy applications that do not support the On-Demand functionality 553 will use the legacy API and will not be able to take advantage of the 554 On-Demand Mobility feature. 556 Applications using the new On-Demand functionality should be aware 557 that they may be executed in legacy environments that do not support 558 it. Such environments may include a legacy IP stack on the mobile 559 host, legacy network infrastructure, or both. In either case, the 560 API will return an error code and the invoking applications may just 561 give up and use legacy calls. 563 5.2. IP Stack in the Mobile Host 565 New IP stacks (that implement On Demand functionality) MUST continue 566 to support all legacy operations. If an application does not use On- 567 Demand functionality, the IP stack MUST respond in a legacy manner. 569 If the network infrastructure supports On-Demand functionality, the 570 IP stack SHOULD follow the application request: If the application 571 requests a specific address type, the stack SHOULD forward this 572 request to the network. If the application does not request an 573 address type, the IP stack MUST NOT request an address type and leave 574 it to the network's default behavior to choose the type of the 575 allocated IP prefix. If an IP prefix was already allocated to the 576 host, the IP stack uses it and may not request a new one from the 577 network. 579 5.3. Network Infrastructure 581 The network infrastructure may or may not support the On-Demand 582 functionality. How the IP stack on the host and the network 583 infrastructure behave in case of a compatibility issue is outside the 584 scope of this API specification. 586 5.4. Merging this work with RFC5014 588 [RFC5014] defines new flags that may be used with setsockopt() to 589 influence source IP address selection for a socket. The list of 590 flags include: source home address, care-of address, temporary 591 address, public address CGA (Cryptographically Created Address) and 592 non-CGA. When applications require session continuity service and 593 use setsc() and bind(), they SHOULD NOT set the flags specified in 594 [RFC5014]. 596 However, if an application erroneously performs a combination of (1) 597 Use setsockopt() to set a specific option (using one of the flags 598 specified in [RFC5014]) and (2) Selects a source IP address type 599 using setsc() and bind(), the IP stack will fulfill the request 600 specified by (2) and ignore the flags set by (1). 602 If bind() was not invoked after setsc() by the application, the IP 603 address generated by setsc() will not be used and traffic generated 604 by the socket will use a source IP address that complies with the 605 options selected by setsockopt(). 607 6. Summary of New Definitions 609 6.1. New APIs 611 setsc() enables applications to request a specific type of source IP 612 address in terms of session continuity. Its definition is: 614 int setsc(int sockfd, in6_addr *sourceAddress, sc_type addressType); 616 Where: 617 - sockfd - is the socket descriptor of the socket with which 618 a specific address type is associated 619 - sourceAddress - is a pointer to an area allocated for setsc() to 620 place the generated source IP address of the 621 desired session continuity type 622 - addressType - Is the desired type of session continuity service. 623 It is a 3-bit field containing one of the 624 following values: 625 0 - Reserved 626 1 - FIXED_IPV6_ADDRESS 627 2 - SESSION_LASTING_IPV6_ADDRESS 628 3 - NON_PERSISTENT_IPV6_ADDRESS 629 4 - GRACEFUL_REPLACEMENT_IPV6_ADDRESS 630 5-7 - Reserved 632 setsc() returns the status of the operation: 633 - 0 - Address was successfully generated 634 - EAI_REQUIREDIPNOTSUPPORTED - the required service type is not 635 supported 636 - EAI_REQUIREDIPFAILED - the network could not fulfill the desired 637 request 639 setsc() MAY block the invoking thread if it triggers the TCP/IP stack 640 to request a new IP prefix from the network to construct the desired 641 source IP address. If an IP prefix with the desired session 642 continuity features already exists (was previously allocated to the 643 mobile host) and the stack is not required to request a new one as a 644 result of setting the IPV6_REQUIRE_SRC_ON_NET flag (defined below), 645 setsc() MAY return immediately with the constructed IP address and 646 will not block the thread. 648 6.2. New Flags 650 The following flag is added to the list of flags in the 651 IPV6_ADDR_PREFERENCE option at the IPPROTO6 level: 653 IPV6_REQUIRE_SRC_ON_NET - set IP stack address allocation behavior 655 If set, the IP stack will request a new IPv6 prefix of the desired 656 type from the current serving network and configure a new source IP 657 address. If reset, the IP stack will use a preconfigured one if it 658 exists. If there is no preconfigured IP address of the desired type, 659 a new prefix will be requested and used for creating the IP address. 661 7. Security Considerations 663 The different service types (session continuity types and address 664 reachability) associated with the allocated IP address types, may be 665 associated with different costs. The cost to the operator for 666 enabling a type of service, and the cost to applications using a 667 selected service. A malicious application may use these to generate 668 extra billing of a mobile subscriber, and/or impose costly services 669 on the mobile operator. When costly services are limited, malicious 670 applications may exhaust them, preventing other applications on the 671 same mobile host from being able to use them. 673 Mobile hosts that enables such service options, should provide 674 capabilities for ensuring that only authorized applications can use 675 the costly (or limited) service types. 677 The ability to select service types requires the exchange of the 678 association of source IP prefixes and their corresponding service 679 types, between the mobile host and mobile network. Exposing these 680 associations may provide information to passive attackers even if the 681 traffic that is used with these addressed is encrypted. 683 To avoid profiling an application according to the type of IP 684 addresses, it is expected that prefixes provided by the mobile 685 operator are associated to various type of addresses over time. As a 686 result, the type of address could not be associated to the prefix, 687 making application profiling based on the type of address harder. 689 The application or the OS should ensure that IP addresses regularly 690 change to limit IP tracking by a passive observer. The application 691 should regularly set the On Demand flag. The application should be 692 able to ensure that session lasting IP addresses are regularly 693 changed by setting a lifetime for example handled by the application. 694 In addition, the application should consider the use of graceful 695 replacement IP addresses. 697 Similarly, the OS may also associated IP addresses with a lifetime. 698 Upon receiving a request for a given type of IP address, after some 699 time, the OS should request a new address to the network even if it 700 already has one IP address available with the requested type. This 701 includes any type of IP address. IP addresses of type graceful 702 replacement or non persistent should be regularly renewed by the OS. 704 The lifetime of an IP address may be expressed in number of seconds 705 or in number of bytes sent through this IP address. 707 8. IANA Considerations 709 This document has no IANA considerations. 711 9. Contributors 713 This document was merged with [I-D.sijeon-dmm-use-cases-api-source]. 714 We would like to acknowledge the contribution of the following people 715 to that document as well: 717 Sergio Figueiredo 718 Altran Research, France 719 Email: sergio.figueiredo@altran.com 721 Younghan Kim 722 Soongsil University, Korea 723 Email: younghak@ssu.ac.kr 725 John Kaippallimalil 726 Huawei, USA 727 Email: john.kaippallimalil@huawei.com 729 10. Acknowledgements 731 We would like to thank Wu-chi Feng, Alexandru Petrescu, Jouni 732 Korhonen, Sri Gundavelli, Dave Dolson Lorenzo Colitti and Daniel 733 Migault for their valuable comments and suggestions on this work. 735 11. References 737 11.1. Normative References 739 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 740 Requirement Levels", BCP 14, RFC 2119, 741 DOI 10.17487/RFC2119, March 1997, 742 . 744 [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 745 Socket API for Source Address Selection", RFC 5014, 746 DOI 10.17487/RFC5014, September 2007, 747 . 749 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 750 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 751 May 2017, . 753 11.2. Informative References 755 [I-D.sijeon-dmm-use-cases-api-source] 756 Jeon, S., Figueiredo, S., Kim, Y., and J. Kaippallimalil, 757 "Use Cases and API Extension for Source IP Address 758 Selection", draft-sijeon-dmm-use-cases-api-source-07 (work 759 in progress), September 2017. 761 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 762 A., Peterson, J., Sparks, R., Handley, M., and E. 763 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 764 DOI 10.17487/RFC3261, June 2002, 765 . 767 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 768 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 769 RFC 5213, DOI 10.17487/RFC5213, August 2008, 770 . 772 [RFC5563] Leung, K., Dommety, G., Yegani, P., and K. Chowdhury, 773 "WiMAX Forum / 3GPP2 Proxy Mobile IPv4", RFC 5563, 774 DOI 10.17487/RFC5563, February 2010, 775 . 777 [RFC5944] Perkins, C., Ed., "IP Mobility Support for IPv4, Revised", 778 RFC 5944, DOI 10.17487/RFC5944, November 2010, 779 . 781 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 782 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 783 2011, . 785 [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, 786 "TCP Extensions for Multipath Operation with Multiple 787 Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, 788 . 790 [RFC7333] Chan, H., Ed., Liu, D., Seite, P., Yokota, H., and J. 791 Korhonen, "Requirements for Distributed Mobility 792 Management", RFC 7333, DOI 10.17487/RFC7333, August 2014, 793 . 795 Authors' Addresses 796 Alper Yegin 797 Actility 798 Istanbul 799 Turkey 801 Email: alper.yegin@actility.com 803 Danny Moses 804 Intel Corporation 805 Petah Tikva 806 Israel 808 Email: danny.moses@intel.com 810 Seil Jeon 811 Sungkyunkwan University 812 Suwon 813 South Korea 815 Email: seiljeon@skku.edu