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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 8811 -- Obsolete informational reference (is this intentional?): RFC 8782 (Obsoleted by RFC 9132) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M. Boucadair 3 Internet-Draft Orange 4 Intended status: Standards Track T. Reddy 5 Expires: May 27, 2021 McAfee 6 W. Pan 7 Huawei Technologies 8 November 23, 2020 10 Multi-homing Deployment Considerations for Distributed-Denial-of-Service 11 Open Threat Signaling (DOTS) 12 draft-ietf-dots-multihoming-05 14 Abstract 16 This document discusses multi-homing considerations for Distributed- 17 Denial-of-Service Open Threat Signaling (DOTS). The goal is to 18 provide some guidance for DOTS clients/gateways when multihomed. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on May 27, 2021. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 56 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 57 4. Multi-Homing Scenarios . . . . . . . . . . . . . . . . . . . 4 58 4.1. Residential Single CPE . . . . . . . . . . . . . . . . . 5 59 4.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream 60 ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 5 61 4.3. Multi-homed Enterprise: Multiple CPEs, Multiple Upstream 62 ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 6 63 4.4. Multi-homed Enterprise with the Same ISP . . . . . . . . 7 64 5. DOTS Multi-homing Deployment Considerations . . . . . . . . . 7 65 5.1. Residential CPE . . . . . . . . . . . . . . . . . . . . . 8 66 5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream 67 ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 9 68 5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream 69 ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 11 70 5.4. Multi-Homed Enterprise: Single ISP . . . . . . . . . . . 12 71 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 72 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 73 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 74 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 75 9.1. Normative References . . . . . . . . . . . . . . . . . . 13 76 9.2. Informative References . . . . . . . . . . . . . . . . . 14 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 79 1. Introduction 81 In many deployments, it may not be possible for a network to 82 determine the cause of a distributed Denial-of-Service (DoS) attack 83 [RFC4732]. Rather, the network may just realize that some resources 84 seem to be under attack. To improve such situation, the IETF is 85 specifying the DDoS Open Threat Signaling (DOTS) 86 [RFC8811]architecture, where a DOTS client can inform a DOTS server 87 that the network is under a potential attack and that appropriate 88 mitigation actions are required. Indeed, because the lack of a 89 common method to coordinate a real-time response among involved 90 actors and network domains jeopardizes the efficiency of DDoS attack 91 mitigation actions, the DOTS protocol is meant to carry requests for 92 DDoS attack mitigation, thereby reducing the impact of an attack and 93 leading to more efficient responsive actions. 94 [I-D.ietf-dots-use-cases] identifies a set of scenarios for DOTS; 95 most of these scenarios involve a Customer Premises Equipment (CPE). 97 The high-level base DOTS architecture is illustrated in Figure 1 98 ([RFC8811]): 100 +-----------+ +-------------+ 101 | Mitigator | ~~~~~~~~~~ | DOTS Server | 102 +-----------+ +-------------+ 103 | 104 | 105 | 106 +---------------+ +-------------+ 107 | Attack Target | ~~~~~~ | DOTS Client | 108 +---------------+ +-------------+ 110 Figure 1: Basic DOTS Architecture 112 [RFC8811] specifies that the DOTS client may be provided with a list 113 of DOTS servers; each of these servers is associated with one or more 114 IP addresses. These addresses may or may not be of the same address 115 family. The DOTS client establishes one or more DOTS sessions by 116 connecting to the provided DOTS server(s) addresses. 118 DOTS may be deployed within networks that are connected to one single 119 upstream provider. It can also be enabled within networks that are 120 multi-homed. The reader may refer to [RFC3582] for an overview of 121 multi-homing goals and motivations. This document discusses DOTS 122 multi-homing considerations. Specifically, the document aims to: 124 1. Complete the base DOTS architecture with multi-homing specifics. 125 Those specifics need to be taken into account because: 127 * Send a DOTS mitigation request to an arbitrary DOTS server 128 won't help mitigating a DDoS attack. 130 * Blindly forking all DOTS mitigation requests among all 131 available DOTS servers is suboptimal. 133 * Sequentially contacting DOTS servers may increase the delay 134 before a mitigation plan is enforced. 136 2. Identify DOTS deployment schemes in a multi-homing context, where 137 DOTS services can be offered by all or a subset of upstream 138 providers. 140 3. Sketch guidelines and recommendations for placing DOTS requests 141 in multi-homed networks, e.g.,: 143 * Select the appropriate DOTS server(s). 145 * Identify cases where anycast is not recommended. 147 This document adopts the following methodology: 149 o Identify and extract viable deployment candidates from 150 [I-D.ietf-dots-use-cases]. 152 o Augment the description with multi-homing technicalities, e.g., 154 * One vs. multiple upstream network providers 156 * One vs. multiple interconnect routers 158 * Provider-Independent (PI) vs. Provider-Aggregatable (PA) IP 159 addresses 161 o Describe the recommended behavior of DOTS clients and gateways for 162 each case. 164 Multi-homed DOTS agents are assumed to make use of the protocols 165 defined in [RFC8782] and [RFC8783]; no specific extension is required 166 to the base DOTS protocols for deploying DOTS in a multi-homed 167 context. 169 2. Requirements Language 171 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 172 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 173 "OPTIONAL" in this document are to be interpreted as described in BCP 174 14 [RFC2119][RFC8174] when, and only when, they appear in all 175 capitals, as shown here. 177 3. Terminology 179 This document makes use of the terms defined in [RFC8811] and 180 [RFC4116]. 182 IP indifferently refers to IPv4 or IPv6. 184 4. Multi-Homing Scenarios 186 This section describes some multi-homing scenarios that are relevant 187 to DOTS. In the following sub-sections, only the connections of 188 border routers are shown; internal network topologies are not 189 elaborated. 191 This section distinguishes between residential CPEs vs. enterprise 192 CPEs because PI addresses may be used for enterprises while this is 193 not the current practice for residential CPEs. 195 4.1. Residential Single CPE 197 The scenario shown in Figure 2 is characterized as follows: 199 o The home network is connected to the Internet using one single CPE 200 (Customer Premises Equipment). 202 o The CPE is connected to multiple provisioning domains (i.e., both 203 fixed and mobile networks). Provisioning domain (PvD) is 204 explained in [RFC7556]. 206 o Each of these provisioning domains assigns IP addresses/prefixes 207 to the CPE and provides additional configuration information such 208 as a list of DNS servers, DNS suffixes associated with the 209 network, default gateway address, and DOTS server's name 210 [I-D.ietf-dots-server-discovery]. These addresses/prefixes are 211 assumed to be Provider-Aggregatable (PA). 213 o Because of ingress filtering, packets forwarded by the CPE towards 214 a given provisioning domain must be sent with a source IP address 215 that was assigned by that domain [RFC8043]. 217 +-------+ +-------+ 218 |Fixed | |Mobile | 219 |Network| |Network| 220 +---+---+ +---+---+ 221 | | Service Providers 222 ............|....................|....................... 223 +---------++---------+ Home Network 224 || 225 +--++-+ 226 | CPE | 227 +-----+ 228 ... (Internal Network) 230 Figure 2: Typical Multi-homed Residential CPE 232 4.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream ISPs 234 The scenario shown in Figure 3 is characterized as follows: 236 o The enterprise network is connected to the Internet using one 237 single router. 239 o That router is connected to multiple provisioning domains (i.e., 240 managed by distinct administrative entities). 242 Unlike the previous scenario, two sub-cases can be considered for an 243 enterprise network with regards to assigned addresses: 245 1. PI addresses/prefixes: The enterprise is the owner of the IP 246 addresses/prefixes; the same address/prefix is then used when 247 establishing communications over any of the provisioning domains. 249 2. PA addresses/prefixes: Each of the provisioning domains assigns 250 IP addresses/prefixes to the enterprise network. 252 +------+ +------+ 253 | ISP1 | | ISP2 | 254 +---+--+ +--+---+ 255 | | Service Providers 256 ............|....................|....................... 257 +---------++---------+ Enterprise Network 258 || 259 +--++-+ 260 | rtr | 261 +-----+ 262 ... (Internal Network) 264 Figure 3: Multi-homed Enterprise Network (Single CPE connected to 265 Multiple Networks) 267 4.3. Multi-homed Enterprise: Multiple CPEs, Multiple Upstream ISPs 269 This scenario is similar to the one described in Section 4.2; the 270 main difference is that dedicated routers are used to connect to each 271 provisioning domain. 273 +------+ +------+ 274 | ISP1 | | ISP2 | 275 +---+--+ +--+---+ 276 | | Service Providers 277 ......................|..........|....................... 278 | | Enterprise Network 279 +---+--+ +--+---+ 280 | rtr1 | | rtr2 | 281 +------+ +------+ 283 ... (Internal Network) 285 Figure 4: Multi-homed Enterprise Network (Multiple CPEs, Multiple 286 ISPs) 288 4.4. Multi-homed Enterprise with the Same ISP 290 This scenario is a variant of Section 4.2 and Section 4.3 in which 291 multi-homing is supported by the same ISP (i.e., same provisioning 292 domain). 294 Editor's Note: The use of anycast addresses is to be consistently 295 discussed. 297 5. DOTS Multi-homing Deployment Considerations 299 Table 1 provides some sample, non-exhaustive, deployment schemes to 300 illustrate how DOTS agents may be deployed for each of the scenarios 301 introduced in Section 4. 303 +---------------------------+-------------------------+-------------+ 304 | Scenario | DOTS client | DOTS | 305 | | | gateway | 306 +---------------------------+-------------------------+-------------+ 307 | Residential CPE | CPE | N/A | 308 +---------------------------+-------------------------+-------------+ 309 | Single CPE, Multiple | internal hosts or CPE | CPE | 310 | provisioning domains | | | 311 +---------------------------+-------------------------+-------------+ 312 | Multiple CPEs, Multiple | internal hosts or all | CPEs (rtr1 | 313 | provisioning domains | CPEs (rtr1 and rtr2) | and rtr2) | 314 +---------------------------+-------------------------+-------------+ 315 | Multi-homed enterprise, | internal hosts or all | CPEs (rtr1 | 316 | Single provisioning | CPEs (rtr1 and rtr2) | and rtr2) | 317 | domain | | | 318 +---------------------------+-------------------------+-------------+ 320 Table 1: Sample Deployment Cases 322 These deployment schemes are further discussed in the following sub- 323 sections. 325 5.1. Residential CPE 327 Figure 5 depicts DOTS sessions that need to be established between a 328 DOTS client (C) and two DOTS servers (S1, S2) within the context of 329 the scenario described in Section 4.1. 331 For each provisioning domain, the DOTS client MUST resolve the DOTS 332 server's name provided by a provisioning domain 333 ([I-D.ietf-dots-server-discovery]) using the DNS servers learned from 334 the respective provisioning domain. IPv6-capable DOTS clients MUST 335 use the source address selection algorithm defined in [RFC6724] to 336 select the candidate source addresses to contact each of these DOTS 337 servers. DOTS sessions MUST be established and maintained with each 338 of the DOTS servers because the mitigation scope of these servers is 339 restricted. The DOTS client SHOULD use the certificate provisioned 340 by a provisioning domain to authenticate itself to the DOTS server 341 provided by the same provisioning domain. 343 When conveying a mitigation request to protect the attack target(s), 344 the DOTS client among the DOTS servers available MUST select a DOTS 345 server whose network has assigned the prefixes from which target 346 prefixes and target IP addresses are derived. This implies that if 347 no appropriate DOTS server is found, the DOTS client MUST NOT send 348 the mitigation request to any DOTS server. 350 For example, a mitigation request to protect target resources bound 351 to a PA IP address/prefix cannot be satisfied by a provisioning 352 domain another domain than the one that owns those addresses/ 353 prefixes. Consequently, if a CPE detects a DDoS attack that spreads 354 over all its network attachments, it MUST contact both DOTS servers 355 for mitigation purposes. Nevertheless, if the DDoS attack is 356 received from one single network, then only the DOTS server of that 357 network MUST be contacted. 359 The DOTS client MUST be able to associate a DOTS server with each 360 provisioning domain. For example, if the DOTS client is provisioned 361 with S1 using DHCP when attaching to a first network and with S2 362 using Protocol Configuration Option (PCO) when attaching to a second 363 network, the DOTS client must record the interface from which a DOTS 364 server was provisioned. DOTS signaling session to a given DOTS 365 server must be established using the interface from which the DOTS 366 server was provisioned. 368 +--+ 369 -----------|S1| 370 / +--+ 371 / 372 / 373 +---+/ 374 | C | 375 +---+\ 376 \ 377 \ 378 \ +--+ 379 -----------|S2| 380 +--+ 382 Figure 5: DOTS Associations for a Multihomed Residential CPE 384 5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream ISPs 386 Figure 6 illustrates a first set of DOTS associations that can be 387 established with a DOTS gateway, which is enabled within the context 388 of the scenario described in Section 4.2. This deployment is 389 characterized as follows: 391 o One of more DOTS clients are enabled in hosts located in the 392 internal network. 394 o A DOTS gateway is enabled to aggregate and then relay the requests 395 towards upstream DOTS servers. 397 When PA addresses/prefixes are in use, the same considerations 398 discussed in Section 5.1 need to be followed by the DOTS gateway to 399 contact its DOTS server(s). The DOTS gateways can be reachable from 400 DOTS clients by using an unicast address or an anycast address. 402 Nevertheless, when PI addresses/prefixes are assigned, the DOTS 403 gateway MUST send mitigation requests to all its DOTS servers. 404 Otherwise, the attack traffic may still be delivered via the ISP 405 which hasn't received the mitigation request. 407 +--+ 408 -----------|S1| 409 +---+ / +--+ 410 | C1|----+ / 411 +---+ | / 412 +---+ +-+-+/ 413 | C3|------| G | 414 +---+ +-+-+\ 415 +---+ | \ 416 | C2|----+ \ 417 +---+ \ +--+ 418 -----------|S2| 419 +--+ 421 Figure 6: Multiple DOTS Clients, Single DOTS Gateway, Multiple DOTS 422 Servers 424 An alternate deployment model is depicted in Figure 7. This 425 deployment assumes that: 427 o One or more DOTS clients are enabled in hosts located in the 428 internal network. These DOTS clients may use 429 [I-D.ietf-dots-server-discovery] to discover their DOTS server(s). 431 o These DOTS clients communicate directly with upstream DOTS 432 servers. 434 If PI addresses/prefixes are in use, the DOTS client MUST send a 435 mitigation request to all the DOTS servers. The use of anycast 436 addresses to reach the DOTS servers is NOT RECOMMENDED. 438 If PA addresses/prefixes are used, the same considerations discussed 439 in Section 5.1 need to be followed by the DOTS clients. Because DOTS 440 clients are not embedded in the CPE and multiple addreses/prefixes 441 may not be assigned to the DOTS client (typically in an IPv4 442 context), some issues arise to steer traffic towards the appropriate 443 DOTS server by using the appropriate source IP address. These 444 complications discussed in [RFC4116] are not specific to DOTS. 446 +--+ 447 +--------|C1|--------+ 448 | +--+ | 449 +--+ +--+ +--+ 450 |S2|------|C3|------|S1| 451 +--+ +--+ +--+ 452 | +--+ | 453 +--------|C2|--------+ 454 +--+ 456 Figure 7: Multiple DOTS Clients, Multiple DOTS Servers 458 Another deployment approach is to enable many DOTS clients; each of 459 them is responsible for handling communications with a specific DOTS 460 server (see Figure 8). 462 +--+ 463 +--------|C1| 464 | +--+ 465 +--+ +--+ +--+ 466 |S2| |C2|------|S1| 467 +--+ +--+ +--+ 469 Figure 8: Single Homed DOTS Clients 471 Each DOTS client SHOULD be provided with policies (e.g., a prefix 472 filter that will be against DDoS detection alarms) that will trigger 473 DOTS communications with the DOTS servers. Such policies will help 474 the DOTS client to select the appropriate destination DOTS server. 476 The CPE MUST select the appropriate source IP address when forwarding 477 DOTS messages received from an internal DOTS client. If anycast 478 addresses are used to reach DOTS servers, the CPE may not be able to 479 select the appropriate provisioning domain to which the mitigation 480 request should be forwarded. As a consequence, the request may not 481 be forwarded to the appropriate DOTS server. 483 5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream ISPs 485 The deployments depicted in Figures 7 and 8 also apply to the 486 scenario described in Section 4.3. One specific problem for this 487 scenario is to select the appropriate exit router when contacting a 488 given DOTS server. 490 An alternative deployment scheme is shown in Figure 9: 492 o DOTS clients are enabled in hosts located in the internal network. 494 o A DOTS gateway is enabled in each CPE (rtr1, rtr2). 496 o Each of these DOTS gateways communicates with the DOTS server of 497 the provisioning domain. 499 When PI addresses/prefixes are used, DOTS clients MUST contact all 500 the DOTS gateways to send a DOTS message. DOTS gateways will then 501 relay the request to the DOTS server. Note that the use of anycast 502 addresses is NOT RECOMMENDED to establish DOTS sessions between DOTS 503 clients and DOTS gateways. 505 When PA addresses/prefixes are used, but no filter rules are provided 506 to DOTS clients, the latter MUST contact all DOTS gateways 507 simultaneously to send a DOTS message. Upon receipt of a request by 508 a DOTS gateway, it MUST check whether the request is to be forwarded 509 upstream (if the target IP prefix is managed by the upstream server) 510 or rejected. 512 When PA addresses/prefixes are used, but specific filter rules are 513 provided to DOTS clients using some means that are out of scope of 514 this document, the clients MUST select the appropriate DOTS gateway 515 to reach. The use of anycast addresses is NOT RECOMMENDED to reach 516 DOTS gateways. 518 +---+ 519 +------------| C1|----+ 520 | +---+ | 521 +--+ +-+-+ +---+ +-+-+ +--+ 522 |S2|------|G2 |------| C3|------|G1 |------|S1| 523 +--+ +-+-+ +---+ +-+-+ +--+ 524 | +---+ | 525 +------------| C2|----+ 526 +---+ 528 Figure 9: Multiple DOTS Clients, Multiple DOTS Gateways, Multiple 529 DOTS Servers 531 5.4. Multi-Homed Enterprise: Single ISP 533 The key difference of the scenario described in Section 4.4 compared 534 to the other scenarios is that multi-homing is provided by the same 535 ISP. Concretely, that ISP can decide to provision the enterprise 536 network with: 538 1. The same DOTS server for all network attachments. 540 2. Distinct DOTS servers for each network attachment. These DOTS 541 servers need to coordinate when a mitigation action is received 542 from the enterprise network. 544 In both cases, DOTS agents enabled within the enterprise network MAY 545 decide to select one or all network attachments to send DOTS 546 mitigation requests. 548 6. Security Considerations 550 DOTS-related security considerations are discussed in Section 4 of 551 [RFC8811]. 553 DOTS clients should control the information that they share with peer 554 DOTS servers. For example, if a DOTS client maintains DOTS 555 associations with specific DOTS servers per interconnection link, the 556 DOTS client should not leak information specific to a given link to 557 DOTS servers not authorized to mitigate attacks received on that 558 link. Whether this constraint is relaxed is deployment specific and 559 must be subject to explicit consent from the DOTS client domain 560 administrator. 562 7. IANA Considerations 564 This document does not require any action from IANA. 566 8. Acknowledgements 568 Thanks to Roland Dobbins, Nik Teague, Jon Shallow, Dan Wing, and 569 Christian Jacquenet for sharing their comments on the mailing list. 571 Thanks to Kirill Kasavchenko for the comments. 573 9. References 575 9.1. Normative References 577 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 578 Requirement Levels", BCP 14, RFC 2119, 579 DOI 10.17487/RFC2119, March 1997, 580 . 582 [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, 583 "Default Address Selection for Internet Protocol Version 6 584 (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, 585 . 587 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 588 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 589 May 2017, . 591 [RFC8811] Mortensen, A., Ed., Reddy.K, T., Ed., Andreasen, F., 592 Teague, N., and R. Compton, "DDoS Open Threat Signaling 593 (DOTS) Architecture", RFC 8811, DOI 10.17487/RFC8811, 594 August 2020, . 596 9.2. Informative References 598 [I-D.ietf-dots-server-discovery] 599 Boucadair, M. and T. Reddy.K, "Distributed-Denial-of- 600 Service Open Threat Signaling (DOTS) Agent Discovery", 601 draft-ietf-dots-server-discovery-15 (work in progress), 602 November 2020. 604 [I-D.ietf-dots-use-cases] 605 Dobbins, R., Migault, D., Moskowitz, R., Teague, N., Xia, 606 L., and K. Nishizuka, "Use cases for DDoS Open Threat 607 Signaling", draft-ietf-dots-use-cases-25 (work in 608 progress), July 2020. 610 [RFC3582] Abley, J., Black, B., and V. Gill, "Goals for IPv6 Site- 611 Multihoming Architectures", RFC 3582, 612 DOI 10.17487/RFC3582, August 2003, 613 . 615 [RFC4116] Abley, J., Lindqvist, K., Davies, E., Black, B., and V. 616 Gill, "IPv4 Multihoming Practices and Limitations", 617 RFC 4116, DOI 10.17487/RFC4116, July 2005, 618 . 620 [RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet 621 Denial-of-Service Considerations", RFC 4732, 622 DOI 10.17487/RFC4732, December 2006, 623 . 625 [RFC7556] Anipko, D., Ed., "Multiple Provisioning Domain 626 Architecture", RFC 7556, DOI 10.17487/RFC7556, June 2015, 627 . 629 [RFC8043] Sarikaya, B. and M. Boucadair, "Source-Address-Dependent 630 Routing and Source Address Selection for IPv6 Hosts: 631 Overview of the Problem Space", RFC 8043, 632 DOI 10.17487/RFC8043, January 2017, 633 . 635 [RFC8782] Reddy.K, T., Ed., Boucadair, M., Ed., Patil, P., 636 Mortensen, A., and N. Teague, "Distributed Denial-of- 637 Service Open Threat Signaling (DOTS) Signal Channel 638 Specification", RFC 8782, DOI 10.17487/RFC8782, May 2020, 639 . 641 [RFC8783] Boucadair, M., Ed. and T. Reddy.K, Ed., "Distributed 642 Denial-of-Service Open Threat Signaling (DOTS) Data 643 Channel Specification", RFC 8783, DOI 10.17487/RFC8783, 644 May 2020, . 646 Authors' Addresses 648 Mohamed Boucadair 649 Orange 650 Rennes 35000 651 France 653 Email: mohamed.boucadair@orange.com 655 Tirumaleswar Reddy 656 McAfee, Inc. 657 Embassy Golf Link Business Park 658 Bangalore, Karnataka 560071 659 India 661 Email: TirumaleswarReddy_Konda@McAfee.com 663 Wei Pan 664 Huawei Technologies 666 Email: william.panwei@huawei.com