idnits 2.17.1 draft-ietf-6lo-backbone-router-17.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 == Line 330 has weird spacing: '...ss side o ...' -- The document date (20 February 2020) is 1526 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 6830 (Obsoleted by RFC 9300, RFC 9301) == Outdated reference: A later version (-23) exists of draft-ietf-6lo-ap-nd-19 == Outdated reference: A later version (-30) exists of draft-ietf-6tisch-architecture-28 == Outdated reference: A later version (-15) exists of draft-ietf-mboned-ieee802-mcast-problems-11 == Outdated reference: A later version (-24) exists of draft-bi-savi-wlan-18 == Outdated reference: A later version (-02) exists of draft-thubert-6lo-unicast-lookup-00 Summary: 0 errors (**), 0 flaws (~~), 7 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6lo P. Thubert, Ed. 3 Internet-Draft Cisco Systems 4 Updates: 6775, 8505 (if approved) C.E. Perkins 5 Intended status: Standards Track Blue Meadow Networking 6 Expires: 23 August 2020 E. Levy-Abegnoli 7 Cisco Systems 8 20 February 2020 10 IPv6 Backbone Router 11 draft-ietf-6lo-backbone-router-17 13 Abstract 15 This document updates RFC 6775 and RFC 8505 in order to enable proxy 16 services for IPv6 Neighbor Discovery by Routing Registrars called 17 Backbone Routers. Backbone Routers are placed along the wireless 18 edge of a Backbone, and federate multiple wireless links to form a 19 single Multi-Link Subnet. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on 23 August 2020. 38 Copyright Notice 40 Copyright (c) 2020 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 45 license-info) in effect on the date of publication of this document. 46 Please review these documents carefully, as they describe your rights 47 and restrictions with respect to this document. Code Components 48 extracted from this document must include Simplified BSD License text 49 as described in Section 4.e of the Trust Legal Provisions and are 50 provided without warranty as described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 56 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 5 57 2.2. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 5 58 2.3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 6 59 2.4. References . . . . . . . . . . . . . . . . . . . . . . . 6 60 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7 61 3.1. Updating RFC 6775 and RFC 8505 . . . . . . . . . . . . . 10 62 3.2. Access Link . . . . . . . . . . . . . . . . . . . . . . . 10 63 3.3. Route-Over Mesh . . . . . . . . . . . . . . . . . . . . . 12 64 3.4. The Binding Table . . . . . . . . . . . . . . . . . . . . 13 65 3.5. Primary and Secondary 6BBRs . . . . . . . . . . . . . . . 14 66 3.6. Using Optimistic DAD . . . . . . . . . . . . . . . . . . 15 67 4. Multi-Link Subnet Considerations . . . . . . . . . . . . . . 15 68 5. Optional 6LBR serving the Multi-Link Subnet . . . . . . . . . 16 69 6. Using IPv6 ND Over the Backbone Link . . . . . . . . . . . . 17 70 7. Routing Proxy Operations . . . . . . . . . . . . . . . . . . 18 71 8. Bridging Proxy Operations . . . . . . . . . . . . . . . . . . 20 72 9. Creating and Maintaining a Binding . . . . . . . . . . . . . 21 73 9.1. Operations on a Binding in Tentative State . . . . . . . 22 74 9.2. Operations on a Binding in Reachable State . . . . . . . 23 75 9.3. Operations on a Binding in Stale State . . . . . . . . . 24 76 10. Registering Node Considerations . . . . . . . . . . . . . . . 25 77 11. Security Considerations . . . . . . . . . . . . . . . . . . . 26 78 12. Protocol Constants . . . . . . . . . . . . . . . . . . . . . 26 79 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 80 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 81 15. Normative References . . . . . . . . . . . . . . . . . . . . 27 82 16. Informative References . . . . . . . . . . . . . . . . . . . 28 83 Appendix A. Possible Future Extensions . . . . . . . . . . . . . 31 84 Appendix B. Applicability and Requirements Served . . . . . . . 31 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 87 1. Introduction 89 IEEE STD. 802.1 [IEEEstd8021] Ethernet Bridging provides an efficient 90 and reliable broadcast service for wired networks; applications and 91 protocols have been built that heavily depend on that feature for 92 their core operation. Unfortunately, Low-Power Lossy Networks (LLNs) 93 and local wireless networks generally do not provide the broadcast 94 capabilities of Ethernet Bridging in an economical fashion. 96 As a result, protocols designed for bridged networks that rely on 97 multicast and broadcast often exhibit disappointing behaviours when 98 employed unmodified on a local wireless medium (see 99 [I-D.ietf-mboned-ieee802-mcast-problems]). 101 Wi-Fi [IEEEstd80211] Access Points (APs) deployed in an Extended 102 Service Set (ESS) act as Ethernet Bridges [IEEEstd8021], with the 103 property that the bridging state is established at the time of 104 association. This ensures connectivity to the end node (the Wi-Fi 105 STA) and protects the wireless medium against broadcast-intensive 106 Transparent Bridging reactive Lookups. In other words, the 107 association process is used to register the MAC Address of the STA to 108 the AP. The AP subsequently proxies the bridging operation and does 109 not need to forward the broadcast Lookups over the radio. 111 In the same way as Transparent Bridging, IPv6 [RFC8200] Neighbor 112 Discovery [RFC4861] [RFC4862] Protocol (IPv6 ND) is a reactive 113 protocol, based on multicast transmissions to locate an on-link 114 correspondent and ensure the uniqueness of an IPv6 address. The 115 mechanism for Duplicate Address Detection (DAD) [RFC4862] was 116 designed for the efficient broadcast operation of Ethernet Bridging. 117 Since broadcast can be unreliable over wireless media, DAD often 118 fails to discover duplications [I-D.yourtchenko-6man-dad-issues]. In 119 practice, the fact that IPv6 addresses very rarely conflict is mostly 120 attributable to the entropy of the 64-bit Interface IDs as opposed to 121 the succesful operation of the IPv6 ND duplicate address detection 122 and resolution mechanisms. 124 The IPv6 ND Neighbor Solicitation (NS) [RFC4861] message is used for 125 DAD and address Lookup when a node moves, or wakes up and reconnects 126 to the wireless network. The NS message is targeted to a Solicited- 127 Node Multicast Address (SNMA) [RFC4291] and should in theory only 128 reach a very small group of nodes. But in reality, IPv6 multicast 129 messages are typically broadcast on the wireless medium, and so they 130 are processed by most of the wireless nodes over the subnet (e.g., 131 the ESS fabric) regardless of how few of the nodes are subscribed to 132 the SNMA. As a result, IPv6 ND address Lookups and DADs over a large 133 wireless and/or a LowPower Lossy Network (LLN) can consume enough 134 bandwidth to cause a substantial degradation to the unicast traffic 135 service. 137 Because IPv6 ND messages sent to the SNMA group are broadcast at the 138 radio MAC Layer, wireless nodes that do not belong to the SNMA group 139 still have to keep their radio turned on to listen to multicast NS 140 messages, which is a total waste of energy for them. In order to 141 reduce their power consumption, certain battery-operated devices such 142 as IoT sensors and smartphones ignore some of the broadcasts, making 143 IPv6 ND operations even less reliable. 145 These problems can be alleviated by reducing the IPv6 ND broadcasts 146 over wireless access links. This has been done by splitting the 147 broadcast domains and routes between subnets, or even by assigning a 148 /64 prefix to each wireless node (see [RFC8273]). 150 Another way is to proxy at the boundary of the wired and wireless 151 domains the Layer 3 protocols that rely on MAC Layer broadcast 152 operations. For instance, IEEE 802.11 [IEEEstd80211] situates proxy- 153 ARP (IPv4) and proxy-ND (IPv6) functions at the Access Points (APs). 154 The 6BBR provides a proxy-ND function and can be extended for proxy- 155 ARP in a continuation specification. 157 Knowledge of which address to proxy for can be obtained by snooping 158 the IPV6 ND protocol (see [I-D.bi-savi-wlan]), but it has been found 159 to be unreliable. An IPv6 address may not be discovered immediately 160 due to a packet loss, or if a "silent" node is not currently using 161 one of its addresses. A change of state (e.g., due to movement) may 162 be missed or misordered, leading to unreliable connectivity and 163 incomplete knowledge of the state of the network. 165 This specification defines the 6BBR as a Routing Registrar [RFC8505] 166 that provides proxy services for IPv6 Neighbor Discovery. As 167 represented in Figure 1, Backbone Routers federate multiple LLNs over 168 a Backbone Link to form a Multi-Link Subnet (MLSN). The MLSN breaks 169 the Layer 2 continuity and splits the broadcast domain, in a fashion 170 that each Link, including the backbone, is its own broadcast domain. 171 This means that devices that rely on a link-scope multicast on the 172 backbone will only reach other nodes on the backbone but not LLN 173 nodes. A key property of MLSNs is that link-local traffic and 174 traffic with a hop limit of 1 will not transit to nodes in the same 175 subnet on a different link, something that may produce unexpected 176 behavior in software that expects a subnet to be entirely contained 177 within a single link. In order to enable the continuity of IPv6 ND 178 operations beyond the backbone, and enable communication using Global 179 or Unique Local Addresses between any pair of nodes in the MLSN, 180 Backbone Routers placed along the LLN edge of the Backbone handle 181 IPv6 ND on behalf of Registered Nodes and forward IPv6 packets back 182 and forth. 184 A 6LoWPAN node (6LN) registers all its IPv6 Addresses using an 185 NS(EARO) as specified in [RFC8505] to the 6BBR. The 6BBR is also a 186 Border Router that performs IPv6 Neighbor Discovery (IPv6 ND) 187 operations on its Backbone interface on behalf of the 6LNs that have 188 registered addresses on its LLN interfaces without the need of a 189 broadcast over the wireless medium. A 6LN that resides on the 190 backbone does not register to the SNMA groups associated to its 191 Registered Addresses and defers to the 6BBR to answer or preferably 192 forward to it as unicast the corresponding multicast packets. 194 2. Terminology 196 2.1. BCP 14 198 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 199 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 200 "OPTIONAL" in this document are to be interpreted as described in BCP 201 14 [RFC2119] [RFC8174] when, and only when, they appear in all 202 capitals, as shown here. 204 2.2. New Terms 206 This document introduces the following terminology: 208 Federated: A subnet that comprises a Backbone and one or more 209 (wireless) access links, is said to be federated into one Multi- 210 Link Subnet. The proxy-ND operation of 6BBRs over the Backbone 211 extends IPv6 ND operation over the access links. 213 Sleeping Proxy: A 6BBR acts as a Sleeping Proxy if it answers ND 214 Neighbor Solicitations over the Backbone on behalf of the 215 Registering Node which might be in a sleep state in a low power 216 network. The Sleeping Proxy that is also a Bridging Proxy will 217 preferably forward the relevant messages to the Registering Node 218 as unicast frames in accord to the duty cycle of the Registering 219 Node and let it respond. 221 Routing Proxy: A Routing Proxy provides IPv6 ND proxy functions and 222 enables the MLSN operation over federated links that may not be 223 compatible for bridging. The Routing Proxy advertises its own MAC 224 Address as the Target Link Layer Address (TLLA) in the proxied NAs 225 over the Backbone, and routes at the Network Layer between the 226 federated links. 228 Bridging Proxy: A Bridging Proxy provides IPv6 ND proxy functions 229 while preserving forwarding continuity at the MAC Layer. The 230 Bridging Proxy advertises the MAC Address of the Registering Node 231 as the TLLA in the proxied NAs over the Backbone. In that case, 232 the MAC Address and the mobility of 6LN is still visible across 233 the bridged Backbone, and the 6BBR may be configured to proxy for 234 Link Local Addresses. 236 Binding Table: The Binding Table is an abstract database that is 237 maintained by the 6BBR to store the state associated with its 238 registrations. 240 Binding: A Binding is an abstract state associated to one 241 registration, in other words one entry in the Binding Table. 243 2.3. Abbreviations 245 This document uses the following abbreviations: 247 6BBR: 6LoWPAN Backbone Router 248 6LBR: 6LoWPAN Border Router 249 6LN: 6LoWPAN Node 250 6LR: 6LoWPAN Router 251 6CIO: Capability Indication Option 252 ARO: Address Registration Option 253 DAC: Duplicate Address Confirmation 254 DAD: Duplicate Address Detection 255 DAR: Duplicate Address Request 256 EARO: Extended Address Registration Option 257 EDAC: Extended Duplicate Address Confirmation 258 EDAR: Extended Duplicate Address Request 259 DODAG: Destination-Oriented Directed Acyclic Graph 260 ID: Identifier 261 LLN: Low-Power and Lossy Network 262 NA: Neighbor Advertisement 263 MAC: Medium Access Control 264 NCE: Neighbor Cache Entry 265 ND: Neighbor Discovery 266 NDP: Neighbor Discovery Protocol 267 NS: Neighbor Solicitation 268 NS(DAD): NDP NS message used for the purpose of duplication 269 avoidance (multicast) 270 NS(Lookup): NDP NS message used for the purpose of address 271 resolution (multicast) 272 NS(NUD): NDP NS message used for the purpose of unreachability 273 detection (unicast) 274 NUD: Neighbor Unreachability Detection 275 ROVR: Registration Ownership Verifier 276 RPL: IPv6 Routing Protocol for LLNs 277 RA: Router Advertisement 278 RS: Router Solicitation 279 SNMA: Solicited-Node Multicast Address 280 LLA: Link Layer Address (aka MAC address) 281 SLLA: Source Link Layer Address 282 TLLA: Target Link Layer Address 283 TID: Transaction ID 285 2.4. References 287 In this document, readers will encounter terms and concepts that are 288 discussed in the following documents: 290 * "Neighbor Discovery for IP version 6" [RFC4861], "IPv6 Stateless 291 Address Autoconfiguration" [RFC4862] and "Optimistic Duplicate 292 Address Detection" [RFC4429], 294 * "Neighbor Discovery Proxies (proxy-ND)" [RFC4389] and "Multi-Link 295 Subnet Issues" [RFC4903], 297 * "Problem Statement and Requirements for IPv6 over Low-Power 298 Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606], and 300 * Neighbor Discovery Optimization for Low-Power and Lossy Networks 301 [RFC6775] and "Registration Extensions for 6LoWPAN Neighbor 302 Discovery" [RFC8505]. 304 3. Overview 306 This section and its subsections present a non-normative high level 307 view of the operation of the 6BBR. The following sections cover the 308 normative part. Figure 1 illustrates a backbone link that federates 309 a collection of LLNs as a single IPv6 Subnet, with a number of 6BBRs 310 providing proxy-ND services to their attached LLNs. 312 The LLN may be a hub-and-spoke access link such as (Low-Power) IEEE 313 STD. 802.11 (Wi-Fi) [IEEEstd80211] and IEEE STD. 802.15.1 (Bluetooth) 314 [IEEEstd802151], or a Mesh-Under or a Route-Over network [RFC8505]. 315 The proxy state can be distributed across multiple 6BBRs attached to 316 the same Backbone. 318 | 319 +-----+ +-----+ +-----+ IPv6 320 (default) | | (Optional) | | | | Node 321 Router | | 6LBR | | | | or 322 +-----+ +-----+ +-----+ 6LN 323 | Backbone side | | 324 ----+-------+-----------------+---+-------------+----+----- 325 | | | 326 +------+ +------+ +------+ 327 | 6BBR | | 6BBR | | 6BBR | 328 | | | | | | 329 +------+ +------+ +------+ 330 o Wireless side o o o o o o 331 o o o o o o o o o o o o o o o o o o o o 332 o o o o o o o o o o o o o o o o o o o 333 o o o o o o o o o LLN o o o o o o o o o 334 o o o o o o o o o o o o o o 335 o o o 337 Figure 1: Backbone Link and Backbone Routers 339 The main features of a 6BBR are as follows: 341 * Multi-Link-subnet functions (provided by the 6BBR on the backbone) 342 performed on behalf of registered 6LNs, and 344 * Routing registrar services that reduce multicast within the LLN: 346 * Binding Table management 347 * failover, e.g., due to mobility 349 Each Backbone Router (6BBR) maintains a data structure for its 350 Registered Addresses called a Binding Table. The combined Binding 351 Tables of all the 6BBRs on a backbone form a distributed database of 352 6LNs that reside in the LLNs or on the IPv6 Backbone. 354 Unless otherwise configured, a 6BBR does the following: 356 * Create a new entry in a Binding Table for a new Registered Address 357 and ensure that the Address is not duplicated over the Backbone. 359 * Advertise a Registered Address over the Backbone using an 360 unsolicited NA message, asynchronously or as a response to a NS 361 message. This includes joining the multicast group associated to 362 the SNMA derived from the Registered Address as specified in 363 section 7.2.1. of [RFC4861] over the Backbone. 365 * The 6BBR may respond immediately as a Proxy in lieu of the 366 Registering Node, e.g., if the Registering Node has a sleeping 367 cycle that the 6BBR does not want to interrupt, or if the 6BBR has 368 a recent state that is deemed fresh enough to permit the proxied 369 response. It is preferred, though, that the 6BBR checks whether 370 the Registering Node is still responsive on the Registered 371 Address. To that effect: 373 - as a Bridging Proxy: 374 the 6BBR forwards the multicast DAD and Address Lookup messages 375 as a unicast MAC-Layer frames to the MAC address of the 376 Registering Node that matches the Target in the ND message, and 377 forwards as is the unicast Neighbor Unreachability Detection 378 (NUD) messages, so as to let the Registering Node answer with 379 the ND Message and options that it sees fit; 380 - as a Routing Proxy: 381 the 6BBR checks the liveliness of the Registering Node, e.g., 382 using a NUD verification, before answering on its behalf. 384 * Deliver packets arriving from the LLN, using Neighbor Solicitation 385 messages to look up the destination over the Backbone. 387 * Forward or bridge packets between the LLN and the Backbone. 389 * Verify liveness for a registration, when needed. 391 The first of these functions enables the 6BBR to fulfill its role as 392 a Routing Registrar for each of its attached LLNs. The remaining 393 functions fulfill the role of the 6BBRs as the border routers 394 connecting the Multi-link IPv6 subnet to the Internet. 396 The operation of IPv6 ND and of proxy-ND are not mutually exclusive 397 on the Backbone, meaning that nodes attached to the Backbone and 398 using IPv6 ND can transparently interact with 6LNs that rely on a 399 6BBR to proxy ND for them, whether the 6LNs are reachable over an LLN 400 or directly attached to the Backbone. 402 The [RFC8505] registration mechanism used to learn addresses to be 403 proxied for may co-exist in a 6BBR with a proprietary snooping or the 404 traditional bridging functionality of an Access Point, in order to 405 support legacy LLN nodes that do not support this specification. 407 The registration to a proxy service uses an NS/NA(EARO) exchange. 408 The 6BBR operation resembles that of a Mobile IPv6 (MIPv6) [RFC6275] 409 Home Agent (HA). The combination of a 6BBR and a MIPv6 HA enables 410 full mobility support for 6LNs, inside and outside the links that 411 form the subnet. 413 The 6BBRs use the Extended Address Registration Option (EARO) defined 414 in [RFC8505] as follows: 416 * The EARO is used in the IPv6 ND exchanges over the Backbone 417 between the 6BBRs to help distinguish duplication from movement. 418 Extended Duplicate Address Messages (EDAR and EDAC) may also be 419 used between a 6LBR, if one is present, and the 6BBR. Address 420 duplication is detected using the ROVR field. Conflicting 421 registrations to different 6BBRs for the same Registered Address 422 are resolved using the TID field. 424 * The Link Layer Address (LLA) that the 6BBR advertises for the 425 Registered Address on behalf of the Registered Node over the 426 Backbone can belong to the Registering Node; in that case, the 427 6BBR (acting as a Bridging Proxy (see Section 8)) bridges the 428 unicast packets. Alternatively, the LLA can be that of the 6BBR 429 on the Backbone interface, in which case the 6BBR (acting as a 430 Routing Proxy(see Section 7)) receives the unicast packets at 431 Layer 3 and routes over. 433 3.1. Updating RFC 6775 and RFC 8505 435 This specification adds the EARO as a possible option in RS, NS(DAD) 436 and NA messages over the backbone. [RFC8505] requires that the 437 registration NS(EARO) contains an Source Link Layer Address Option 438 (SLLAO). This specification details the use of those messages over 439 the backbone. 441 Note: [RFC6775] requires that the registration NS(EARO) contains an 442 SLLAO and [RFC4862] that the NS(DAD) is sent from the unspecified 443 address for which there cannot be a SLLAO. Consequently, an NS(DAD) 444 cannot be confused with a registration. 446 This specification adds the capability to insert IPv6 ND options in 447 the EDAR and EDAC messages. In particular, a 6BBR acting as a 6LR 448 for the Registered Address can insert an SLLAO in the EDAR to the 449 6LBR in order to avoid a Lookup back. This enables the 6LBR to store 450 the MAC address associated to the Registered Address on a Link and to 451 serve as a mapping server as described in 452 [I-D.thubert-6lo-unicast-lookup]. 454 3.2. Access Link 456 The simplest Multi-Link Subnet topology from the Layer 3 perspective 457 occurs when the wireless network appears as a single hop hub-and- 458 spoke network as shown in Figure 2. The Layer 2 operation may 459 effectively be hub-and-spoke (e.g., Wi-Fi) or Mesh-Under, with a 460 Layer 2 protocol handling the complex topology. 462 | 463 +-----+ +-----+ +-----+ IPv6 464 (default) | | (Optional) | | | | Node 465 Router | | 6LBR | | | | or 466 +-----+ +-----+ +-----+ 6LN 467 | Backbone side | | 468 ----+-------+-----------------+---+-------------+----+----- 469 | | | 470 +------+ +------+ +------+ 471 | 6BBR | | 6BBR | | 6BBR | 472 | 6LR | | 6LR | | 6LR | 473 +------+ +------+ +------+ 474 (6LN) (6LN) (6LN) (6LN) (6LN) (6LN) (6LN) (6LN) 476 Figure 2: Access Link Use case 478 Figure 3 illustrates a flow where 6LN forms an IPv6 Address and 479 registers it to a 6BBR acting as a 6LR [RFC8505]. The 6BBR applies 480 ODAD (see Section 3.6) to the registered address to enable 481 connectivity while the message flow is still in progress. 483 6LN(STA) 6BBR(AP) 6LBR default GW 484 | | | | 485 | LLN Access Link | IPv6 Backbone (e.g., Ethernet) | 486 | | | | 487 | RS(multicast) | | | 488 |---------------->| | | 489 | RA(PIO, Unicast)| | | 490 |<----------------| | | 491 | NS(EARO) | | | 492 |---------------->| | | 493 | | Extended DAR | | 494 | |--------------->| | 495 | | Extended DAC | | 496 | |<---------------| | 497 | | | 498 | | NS-DAD(EARO, multicast) | 499 | |--------> | 500 | |----------------------------------->| 501 | | | 502 | | RS(no SLLAO, for ODAD) | 503 | |----------------------------------->| 504 | | if (no fresher Binding) NS(Lookup) | 505 | | <----------------| 506 | |<-----------------------------------| 507 | | NA(SLLAO, not(O), EARO) | 508 | |----------------------------------->| 509 | | RA(unicast) | 510 | |<-----------------------------------| 511 | | | 512 | IPv6 Packets in optimistic mode | 513 |<---------------------------------------------------->| 514 | | | 515 | | 516 | NA(EARO) | 517 |<----------------| 518 | | 520 Figure 3: Initial Registration Flow to a 6BBR acting as Routing Proxy 522 In this example, a 6LBR is deployed on the backbone link to serve the 523 whole subnet, and EDAR / EDAC messages are used in combination with 524 DAD to enable coexistence with IPv6 ND over the backbone. 526 The RS sent initially by the 6LN(STA) is transmitted as a multicast 527 but since it is intercepted by the 6BBR, it is never effectively 528 broadcast. The multiple arrows associated to the ND messages on the 529 Backbone denote a real Layer 2 broadcast. 531 3.3. Route-Over Mesh 533 A more complex Multi-Link Subnet topology occurs when the wireless 534 network appears as a Layer 3 Mesh network as shown in Figure 4. A 535 so-called Route-Over routing protocol exposes routes between 6LRs 536 towards both 6LRs and 6LNs, and a 6LBR acts as Root of the Layer 3 537 Mesh network and proxy-registers the LLN addresses to the 6BBR. 539 | 540 +-----+ +-----+ +-----+ IPv6 541 (default) | | (Optional) | | | | Node 542 Router | | 6LBR | | | | or 543 +-----+ +-----+ +-----+ 6LN 544 | Backbone side | | 545 ----+-------+-----------------+---+-------------+----+----- 546 | | | 547 +------+ +------+ +------+ 548 | 6BBR | | 6BBR | | 6BBR | 549 +------+ +------+ +------+ 550 | | | 551 +------+ +------+ +------+ 552 | 6LBR | | 6LBR | | 6LBR | 553 +------+ +------+ +------+ 554 (6LN) (6LR) (6LN) (6LR) (6LN) (6LR) (6LR) (6LR)(6LN) 555 (6LN)(6LR) (6LR) (6LN) (6LN) (6LR)(6LN) (6LR) (6LR) (6LR) (6LN) 556 (6LR)(6LR) (6LR) (6LR) (6LR)(6LN) (6LR) (6LR)(6LR) 557 (6LR) (6LR) (6LR) (6LR) (6LN)(6LR) (6LR) (6LR) (6LR) (6LR) 558 (6LN) (6LN)(6LN) (6LN) (6LN) (6LN) (6LN) (6LN) (6LN) (6LN) 560 Figure 4: Route-Over Mesh Use case 562 Figure 5 illustrates IPv6 signaling that enables a 6LN (the 563 Registered Node) to form a Global or a Unique-Local Address and 564 register it to the 6LBR that serves its LLN using [RFC8505]. The 565 6LBR (the Registering Node) then proxies the [RFC8505] registration 566 to the 6BBR to obtain proxy-ND services from the 6BBR. 568 As above, the RS sent initially by the 6LN(STA) is a transmitted as a 569 multicast but since it is intercepted by the 6BBR, it is never 570 effectively broadcast, and the multiple arrows associated to the ND 571 messages on the Backbone denote a real Layer 2 broadcast. 573 6LoWPAN Node 6LR 6LBR 6BBR 574 (mesh leaf) (mesh router) (mesh root) 575 | | | | 576 | 6LoWPAN ND |6LoWPAN ND | 6LoWPAN ND | IPv6 ND 577 | LLN link |Route-Over mesh|Ethernet/serial| Backbone 578 | | |/Internal call | 579 | IPv6 ND RS | | | 580 |-------------->| | | 581 |-----------> | | | 582 |------------------> | | 583 | IPv6 ND RA | | | 584 |<--------------| | | 585 | | | | 586 | NS(EARO) | | | 587 |-------------->| | | 588 | 6LoWPAN ND | Extended DAR | | 589 | |-------------->| | 590 | | | NS(EARO) | 591 | | |-------------->| 592 | | | (proxied) | NS-DAD 593 | | | |------> 594 | | | | (EARO) 595 | | | | 596 | | | NA(EARO) | 597 | | |<--------------| 598 | | Extended DAC | | 599 | |<--------------| | 600 | NA(EARO) | | | 601 |<--------------| | | 602 | | | | 604 Figure 5: Initial Registration Flow over Route-Over Mesh 606 As a non-normative example of a Route-Over Mesh, the 6TiSCH 607 architecture [I-D.ietf-6tisch-architecture] suggests using the RPL 608 [RFC6550] routing protocol and collocating the RPL root with a 6LBR 609 that serves the LLN. The 6LBR is also either collocated with or 610 directly connected to the 6BBR over an IPv6 Link. 612 3.4. The Binding Table 614 Addresses in an LLN that are reachable from the Backbone by way of 615 the 6BBR function must be registered to that 6BBR, using an NS(EARO) 616 with the R flag set [RFC8505]. A 6BBR maintains a state for its 617 active registrations in an abstract Binding Table. 619 An entry in the Binding Table is called a "Binding". A Binding may 620 be in Tentative, Reachable or Stale state. 622 The 6BBR uses a combination of [RFC8505] and IPv6 ND over the 623 Backbone to advertise the registration and avoid a duplication. 624 Conflicting registrations are solved by the 6BBRs, transparently to 625 the Registering Nodes. 627 Only one 6LN may register a given Address, but the Address may be 628 registered to Multiple 6BBRs for higher availability. 630 Over the LLN, Binding Table management is as follows: 632 * De-registrations (newer TID, same ROVR, null Lifetime) are 633 accepted with a status of 4 ("Removed"); the entry is deleted; 635 * Newer registrations (newer TID, same ROVR, non-null Lifetime) are 636 accepted with a status of 0 (Success); the Binding is updated with 637 the new TID, the Registration Lifetime and the Registering Node; 638 in Tentative state the EDAC response is held and may be 639 overwritten; in other states the Registration Lifetime timer is 640 restarted and the entry is placed in Reachable state. 642 * Identical registrations (same TID, same ROVR) from the same 643 Registering Node are accepted with a status of 0 (Success). In 644 Tentative state, the response is held and may be overwritten, but 645 the response is eventually produced, carrying the result of the 646 DAD process; 648 * Older registrations (older TID, same ROVR) from the same 649 Registering Node are discarded; 651 * Identical and older registrations (not-newer TID, same ROVR) from 652 a different Registering Node are rejected with a status of 3 653 (Moved); this may be rate limited to avoid undue interference; 655 * Any registration for the same address but with a different ROVR is 656 rejected with a status of 1 (Duplicate). 658 The operation of the Binding Table is specified in detail in 659 Section 9. 661 3.5. Primary and Secondary 6BBRs 663 The same address may be successfully registered to more than one 664 6BBR, in which case the Registering Node uses the same EARO in all 665 the parallel registrations. To allow for this, ND(DAD) and NA 666 messages with an EARO that indicate an identical Binding in another 667 6BBR (same Registered address, same TID, same ROVR) are silently 668 ignored. 670 A 6BBR may optionally be primary or secondary. The primary is the 671 6BBR that has the highest EUI-64 Address of all the 6BBRs that share 672 a registration for the same Registered Address, with the same ROVR 673 and same Transaction ID, the EUI-64 Address being considered as an 674 unsigned 64bit integer. A given 6BBR can be primary for a given 675 Address and secondary for another Address, regardless of whether or 676 not the Addresses belong to the same 6LN. 678 In the following sections, is is expected that an NA is sent over the 679 backbone only if the node is primary or does not support the concept 680 of primary. More than one 6BBR claiming or defending an address 681 generates unwanted traffic but no reachability issue since all 6BBRs 682 provide reachability from the Backbone to the 6LN. 684 3.6. Using Optimistic DAD 686 Optimistic Duplicate Address Detection [RFC4429] (ODAD) specifies how 687 an IPv6 Address can be used before completion of Duplicate Address 688 Detection (DAD). ODAD guarantees that this behavior will not cause 689 harm if the new Address is a duplicate. 691 Support for ODAD avoids delays in installing the Neighbor Cache Entry 692 (NCE) in the 6BBRs and the default router, enabling immediate 693 connectivity to the registered node. As shown in Figure 3, if the 694 6BBR is aware of the Link-Layer Address (LLA) of a router, then the 695 6BBR sends a Router Solicitation (RS), using the Registered Address 696 as the IP Source Address, to the known router(s). The RS is sent 697 without a Source LLA Option (SLLAO), to avoid invalidating a 698 preexisting NCE in the router. 700 Following ODAD, the router may then send a unicast RA to the 701 Registered Address, and it may resolve that Address using an 702 NS(Lookup) message. In response, the 6BBR sends an NA with an EARO 703 and the Override flag [RFC4861] that is not set. The router can then 704 determine the freshest EARO in case of conflicting NA(EARO) messages, 705 using the method described in section 5.2.1 of [RFC8505]. If the 706 NA(EARO) is the freshest answer, the default router creates a Binding 707 with the SLLAO of the 6BBR (in Routing Proxy mode) or that of the 708 Registering Node (in Bridging Proxy mode) so that traffic from/to the 709 Registered Address can flow immediately. 711 4. Multi-Link Subnet Considerations 713 The Backbone and the federated LLN Links are considered as different 714 links in the Multi-Link Subnet, even if multiple LLNs are attached to 715 the same 6BBR. ND messages are link-scoped and are not forwarded by 716 the 6BBR between the backbone and the LLNs though some packets may be 717 reinjected in Bridging Proxy mode (see Section 8). 719 Nodes located inside the subnet do not perform the IPv6 Path MTU 720 Discovery [RFC8201]. For that reason, the MTU MUST have the same 721 value on the Backbone and all attached LLNs. As a consequence, the 722 6BBR MUST use the same MTU value in RAs over the Backbone and in the 723 RAs that it transmits towards the LLN links. 725 5. Optional 6LBR serving the Multi-Link Subnet 727 A 6LBR can be deployed to serve the whole MLSN. It may be attached 728 to the backbone, in which case it can be discovered by its capability 729 advertisement (see section 4.3. of [RFC8505]) in RA messages. 731 This specification allows for an address to be registered to more 732 than one 6BBR. Consequently a 6LBR MUST be capable of maintaining 733 state for each of the 6BBR having registered with the same TID and 734 same ROVR. 736 When a 6LBR is present, the 6BBR uses an EDAR/EDAC message exchange 737 with the 6LBR to check if the new registration corresponds to a 738 duplication or a movement. This is done prior to the NS(DAD) 739 process, which may be avoided if the 6LBR already maintains a 740 conflicting state for the Registered Address. 742 If this registration is duplicate or not the freshest, then the 6LBR 743 replies with an EDAC message with a status code of 1 ("Duplicate 744 Address") or 3 ("Moved"), respectively. If this registration is the 745 freshest, then the 6LBR replies with a status code of 0. In that 746 case, if this registration is fresher than an existing registration 747 for another 6BBR, then the 6LBR also sends an asynchronous EDAC with 748 a status of 4 ("Removed") to that other 6BBR. 750 The EDAR message SHOULD carry the SLLAO used in NS messages by the 751 6BBR for that Binding, and the EDAC message SHOULD carry the Target 752 Link Layer Address Option (TLLAO) associated with the currently 753 accepted registration. This enables a 6BBR to locate the new 754 position of a mobile 6LN in the case of a Routing Proxy operation, 755 and opens the capability for the 6LBR to serve as a mapping server in 756 the future. 758 Note that if Link Local addresses are registered, then the scope of 759 uniqueness on which the address duplication is checked is the total 760 collection of links that the 6LBR serves as opposed to the sole link 761 on which the Link Local address is assigned. 763 6. Using IPv6 ND Over the Backbone Link 765 On the Backbone side, the 6BBR MUST join the SNMA group corresponding 766 to a Registered Address as soon as it creates a Binding for that 767 Address, and maintain that SNMA membership as long as it maintains 768 the registration. The 6BBR uses either the SNMA or plain unicast to 769 defend the Registered Addresses in its Binding Table over the 770 Backbone (as specified in [RFC4862]). The 6BBR advertises and 771 defends the Registered Addresses over the Backbone Link using RS, 772 NS(DAD) and NA messages with the Registered Address as the Source or 773 Target address, respectively. 775 The 6BBR MUST place an EARO in the IPv6 ND messages that it generates 776 on behalf of the Registered Node. Note that an NS(DAD) does not 777 contain an SLLAO and cannot be confused with a proxy registration 778 such as performed by a 6LBR. 780 IPv6 ND operates as follows on the backbone: 782 * Section 7.2.8 of [RFC4861] specifies that an NA message generated 783 as a proxy does not have the Override flag set in order to ensure 784 that if the real owner is present on the link, its own NA will 785 take precedence, and that this NA does not update the NCE for the 786 real owner if one exists. 788 * A node that receives multiple NA messages updates an existing NCE 789 only if the Override flag is set; otherwise the node will probe 790 the cached address. 792 * When an NS(DAD) is received for a tentative address, which means 793 that 2 nodes form the same address at nearly the same time, 794 section 5.4.3 of [RFC4862] cannot sort out the first come and the 795 address is abandoned. 797 * In any fashion, [RFC4862] indicates that a node never responds to 798 a Neighbor Solicitation for a tentative address. 800 This specification adds information about proxied addresses that 801 helps sort out a duplication (different ROVR) from a movement (same 802 ROVR, different TID), and in the latter case the older registration 803 from the fresher one (by comparing TIDs). 805 When a Registering Node moves from one 6BBR to the next, the new 6BBR 806 sends NA messages to update the NCE in node over the backbone. The 807 6BBR may set the Override flag in the NA messages if it is known that 808 the Registering Node will not connect directly to the backbone (e.g., 809 the Registering Node is attached using a different type of 810 interface). 812 A node that supports this specification and that receives multiple NA 813 messages with an EARO option and the same ROVR MUST favor the NA with 814 the freshest EARO over the others. 816 When the Binding is in Tentative state: 818 * an NS(DAD) that indicates a duplication can still not be asserted 819 for first come, but the situation can be avoided using a 6LBR on 820 the backbone that will serialize the order of appearance of the 821 address and ensure first-come/first-serve. 823 * an NS or an NA that denotes an older registration for the same 824 Registered Node is not interpreted as a duplication as specified 825 in section 5.4.3 and 5.4.4 of [RFC4862], respectively. 827 When the Binding is no more in Tentative state: 829 * an NS or an NA with an EARO that denotes a duplicate registration 830 (different ROVR) is answered with an NA message that carries an 831 EARO with a status of 1 (Duplicate), unless the received message 832 is an NA that carries an EARO with a status of 1. 834 In any state: 836 * an NS or an NA with an EARO that denotes an older registration 837 (same ROVR) is answered with an NA message that carries an EARO 838 with a status of 3 (Moved) to ensure that the stale state is 839 removed rapidly. 841 This behavior is specified in more details in Section 9. 843 This specification enables proxy operation for the IPv6 ND resolution 844 of LLN devices and a prefix that is used across a Multi-Link Subnet 845 MAY be advertised as on-link over the Backbone. This is done for 846 backward compatibility with existing IPv6 hosts by setting the L flag 847 in the Prefix Information Option (PIO) of RA messages [RFC4861]. 849 For movement involving a slow reattachment, the NUD procedure defined 850 in [RFC4861] may time out too quickly. Nodes on the backbone SHOULD 851 support [RFC7048] whenever possible. 853 7. Routing Proxy Operations 855 A Routing Proxy provides IPv6 ND proxy functions for Global and 856 Unique Local addresses between the LLN and the backbone, but not for 857 Link-Local addresses. It operates as an IPv6 border router and 858 provides a full Link-Layer isolation. 860 In this mode, it is not required that the MAC addresses of the 6LNs 861 are visible at Layer 2 over the Backbone. It is thus useful when the 862 messaging over the Backbone that is associated to wireless mobility 863 becomes expensive, e.g., when the Layer 2 topology is virtualized 864 over a wide area IP underlay. 866 This mode is definitely required when the LLN uses a MAC address 867 format that is different from that on the Backbone (e.g., EUI-64 vs. 868 EUI-48). Since a 6LN may not be able to resolve an arbitrary 869 destination in the MLSN directly, the MLSN prefix MUST NOT be 870 advertised as on-link in RA messages sent towards the LLN. 872 In order to maintain IP connectivity, the 6BBR installs a connected 873 Host route to the Registered Address on the LLN interface, via the 874 Registering Node as identified by the Source Address and the SLLA 875 option in the NS(EARO) messages. 877 When operating as a Routing Proxy, the 6BBR MUST use its Layer 2 878 Address on its Backbone Interface in the SLLAO of the RS messages and 879 the TLLAO of the NA messages that it generates to advertise the 880 Registered Addresses. 882 For each Registered Address, multiple peers on the Backbone may have 883 resolved the Address with the 6BBR MAC Address, maintaining that 884 mapping in their Neighbor Cache. The 6BBR SHOULD maintain a list of 885 the peers on the Backbone which have associated its MAC Address with 886 the Registered Address. If that Registered Address moves to another 887 6BBR, the previous 6BBR SHOULD unicast a gratuitous NA to each such 888 peer, to supply the LLA of the new 6BBR in the TLLA option for the 889 Address. A 6BBR that does not maintain this list MAY multicast a 890 gratuitous NA message; this NA will possibly hit all the nodes on the 891 Backbone, whether or not they maintain an NCE for the Registered 892 Address. In either case, the 6BBR MAY set the Override flag if it is 893 known that the Registered Node cannot attach to the backbone, so as 894 to avoid interruptions and save probing flows in the future. 896 If a correspondent fails to receive the gratuitous NA, it will keep 897 sending traffic to a 6BBR to which the node was previously 898 registered. Since the previous 6BBR removed its Host route to the 899 Registered Address, it will look up the address over the backbone, 900 resolve the address with the LLA of the new 6BBR, and forward the 901 packet to the correct 6BBR. The previous 6BBR SHOULD also issue a 902 redirect message [RFC4861] to update the cache of the correspondent. 904 8. Bridging Proxy Operations 906 A Bridging Proxy provides IPv6 ND proxy functions between the LLN and 907 the backbone while preserving the forwarding continuity at the MAC 908 Layer. It acts as a Layer 2 Bridge for all types of unicast packets 909 including link-scoped, and appears as an IPv6 Host on the Backbone. 911 The Bridging Proxy registers any Binding including for a Link-Local 912 address to the 6LBR (if present) and defends it over the backbone in 913 IPv6 ND procedures. 915 To achieve this, the Bridging Proxy intercepts the IPv6 ND messages 916 and may reinject them on the other side, respond directly or drop 917 them. For instance, an ND(Lookup) from the backbone that matches a 918 Binding can be responded directly, or turned into a unicast on the 919 LLN side to let the 6LN respond. 921 As a Bridging Proxy, the 6BBR MUST use the Registering Node's Layer 2 922 Address in the SLLAO of the NS/RS messages and the TLLAO of the NA 923 messages that it generates to advertise the Registered Addresses. 924 The Registering Node's Layer 2 address is found in the SLLA of the 925 registration NS(EARO), and maintained in the Binding Table. 927 The Multi-Link Subnet prefix SHOULD NOT be advertised as on-link in 928 RA messages sent towards the LLN. If a destination address is seen 929 as on-link, then a 6LN may use NS(Lookup) messages to resolve that 930 address. In that case, the 6BBR MUST either answer the NS(Lookup) 931 message directly or reinject the message on the backbone, either as a 932 Layer 2 unicast or a multicast. 934 If the Registering Node owns the Registered Address, meaning that the 935 Registering Node is the Registered Node, then its mobility does not 936 impact existing NCEs over the Backbone. In a network where proxy 937 registrations are used, meaning that the Registering Node acts on 938 behalf of the Registered Node, if the Registered Node selects a new 939 Registering Node then the existing NCEs across the Backbone pointing 940 at the old Registering Node must be updated. In that case, the 6BBR 941 SHOULD attempt to fix the existing NCEs across the Backbone pointing 942 at other 6BBRs using NA messages as described in Section 7. 944 This method can fail if the multicast message is not received; one or 945 more correspondent nodes on the Backbone might maintain an stale NCE, 946 and packets to the Registered Address may be lost. When this 947 condition happens, it is eventually discovered and resolved using NUD 948 as defined in [RFC4861]. 950 9. Creating and Maintaining a Binding 952 Upon receiving a registration for a new Address (i.e., an NS(EARO) 953 with the R flag set), the 6BBR creates a Binding and operates as a 954 6LR according to [RFC8505], interacting with the 6LBR if one is 955 present. 957 An implementation of a Routing Proxy that creates a Binding MUST also 958 create an associated Host route pointing to the registering node in 959 the LLN interface from which the registration was received. 961 Acting as a 6BBR, the 6LR operation is modified as follows: 963 * Acting as Bridging Proxy the 6LR MUST proxy ND over the backbone 964 for registered Link-Local addresses. 966 * EDAR and EDAC messages SHOULD carry a SLLAO and a TLLAO, 967 respectively. 969 * An EDAC message with a status of 9 (6LBR Registry Saturated) is 970 assimilated as a status of 0 if a following DAD process protects 971 the address against duplication. 973 This specification enables nodes on a Backbone Link to co-exist along 974 with nodes implementing IPv6 ND [RFC4861] as well as other non- 975 normative specifications such as [I-D.bi-savi-wlan]. It is possible 976 that not all IPv6 addresses on the Backbone are registered and known 977 to the 6LBR, and an EDAR/EDAC echange with the 6LBR might succeed 978 even for a duplicate address. Consequently, and unless 979 administratively overridden, the 6BBR still needs to perform IPv6 ND 980 DAD over the backbone after an EDAC with a status code of 0 or 9. 982 For the DAD operation, the Binding is placed in Tentative state for a 983 duration of TENTATIVE_DURATION (Section 12), and an NS(DAD) message 984 is sent as a multicast message over the Backbone to the SNMA 985 associated with the registered Address [RFC4862]. The EARO from the 986 registration MUST be placed unchanged in the NS(DAD) message. 988 If a registration is received for an existing Binding with a non-null 989 Registration Lifetime and the registration is fresher (same ROVR, 990 fresher TID), then the Binding is updated, with the new Registration 991 Lifetime, TID, and possibly Registering Node. In Tentative state 992 (see Section 9.1), the current DAD operation continues unaltered. In 993 other states (see Section 9.2 and Section 9.3 ), the Binding is 994 placed in Reachable state for the Registration Lifetime, and the 6BBR 995 returns an NA(EARO) to the Registering Node with a status of 0 996 (Success). 998 Upon a registration that is identical (same ROVR, TID, and 999 Registering Node), the 6BBR returns an NA(EARO) back to the 1000 Registering Node with a status of 0 (Success). A registration that 1001 is not as fresh (same ROVR, older TID) is ignored. 1003 If a registration is received for an existing Binding and a 1004 registration Lifetime of zero, then the Binding is removed, and the 1005 6BBR returns an NA(EARO) back to the Registering Node with a status 1006 of 0 (Success). An implementation of a Routing Proxy that removes a 1007 binding MUST remove the associated Host route pointing on the 1008 registering node. It MAY preserve a temporary state in order to 1009 forward packets in flight. The state may be a NCE formed based on a 1010 received NA message, or a Binding in Stale state and pointing at the 1011 new 6BBR on the backbone. 1013 The old 6BBR SHOULD also use REDIRECT messages as specified in 1014 [RFC4861] to update the correspondents for the Registered Address, 1015 pointing to the new 6BBR. 1017 9.1. Operations on a Binding in Tentative State 1019 The Tentative state covers a DAD period over the backbone during 1020 which an address being registered is checked for duplication using 1021 procedures defined in [RFC4862]. 1023 For a Binding in Tentative state: 1025 * The Binding MUST be removed if an NA message is received over the 1026 Backbone for the Registered Address with no EARO, or containing an 1027 EARO that indicates an existing registration owned by a different 1028 Registering Node (different ROVR). An NA MUST be sent back to the 1029 Registering Node with a status of 1 (Duplicate). This behavior 1030 might be overridden by policy, in particular if the registration 1031 is trusted, e.g., based on the validation of the ROVR field (see 1032 [I-D.ietf-6lo-ap-nd]). 1034 * The Binding MUST be removed if an NS(DAD) message is received over 1035 the Backbone for the Registered Address with no EARO, or 1036 containing an EARO with a different ROVR that indicates a 1037 tentative registration by a different Registering Node. In that 1038 case, an NA MUST be sent back to the Registering Node with a 1039 status of 1 (Duplicate). This behavior might be overridden by 1040 policy, in particular if the registration is trusted, e.g., based 1041 on the validation of the ROVR field (see [I-D.ietf-6lo-ap-nd]). 1043 * The Binding MUST be removed if an NA or an NS(DAD) message is 1044 received over the Backbone for the Registered Address containing 1045 an EARO with a that indicates a fresher registration ([RFC8505]) 1046 for the same Registering Node (same ROVR). A status of 3 is 1047 returned in the NA(EARO) back to the Registering Node. 1049 * The Binding MUST be kept unchanged if an NA or an NS(DAD) message 1050 is received over the Backbone for the Registered Address 1051 containing an EARO with a that indicates an older registration 1052 ([RFC8505]) for the same Registering Node (same ROVR). The 1053 message SHOULD be answered with an NA that carries an EARO with a 1054 status of 3 (Moved) and the Override flag not set. This behavior 1055 might be overridden by policy, in particular if the registration 1056 is not trusted. 1058 * Other NS(DAD) and NA messages from the Backbone are ignored. 1060 * NS(Lookup) and NS(NUD) messages SHOULD be optimistically answered 1061 with an NA message containing an EARO with a status of 0 and the 1062 Override flag not set (see Section 3.6). If optimistic DAD is 1063 disabled, then they SHOULD be queued to be answered when the 1064 Binding goes to Reachable state. 1066 When the TENTATIVE_DURATION (Section 12) timer elapses, the Binding 1067 is placed in Reachable state for the Registration Lifetime, and the 1068 6BBR returns an NA(EARO) to the Registering Node with a status of 0 1069 (Success). 1071 The 6BBR also attempts to take over any existing Binding from other 1072 6BBRs and to update existing NCEs in backbone nodes. This is done by 1073 sending an NA message with an EARO and the Override flag not set over 1074 the backbone (see Section 7 and Section 8). 1076 9.2. Operations on a Binding in Reachable State 1078 The Reachable state covers an active registration after a successful 1079 DAD process. 1081 If the Registration Lifetime is of a long duration, an implementation 1082 might be configured to reassess the availability of the Registering 1083 Node at a lower period, using a NUD procedure as specified in 1084 [RFC7048]. If the NUD procedure fails, the Binding SHOULD be placed 1085 in Stale state immediately. 1087 For a Binding in Reachable state: 1089 * The Binding MUST be removed if an NA or an NS(DAD) message is 1090 received over the Backbone for the Registered Address containing 1091 an EARO that indicates a fresher registration ([RFC8505]) for the 1092 same Registered Node (i.e., same ROVR but fresher TID). A status 1093 of 4 (Removed) is returned in an asynchronous NA(EARO) to the 1094 Registering Node. Based on configuration, an implementation may 1095 delay this operation by a timer with a short setting, e.g., a few 1096 seconds to a minute, in order to a allow for a parallel 1097 registration to reach this node, in which case the NA might be 1098 ignored. 1100 * NS(DAD) and NA messages containing an EARO that indicates a 1101 registration for the same Registered Node that is not as fresh as 1102 this binding MUST be answered with an NA message containing an 1103 EARO with a status of 3 (Moved). 1105 * An NS(DAD) with no EARO or with an EARO that indicates a duplicate 1106 registration (i.e., different ROVR) MUST be answered with an NA 1107 message containing an EARO with a status of 1 (Duplicate) and the 1108 Override flag not set, unless the received message is an NA that 1109 carries an EARO with a status of 1, in which case the node 1110 refrains from answering. 1112 * Other NS(DAD) and NA messages from the Backbone are ignored. 1114 * NS(Lookup) and NS(NUD) messages SHOULD be answered with an NA 1115 message containing an EARO with a status of 0 and the Override 1116 flag not set. The 6BBR MAY check whether the Registering Node is 1117 still available using a NUD procedure over the LLN prior to 1118 answering; this behaviour depends on the use case and is subject 1119 to configuration. 1121 When the Registration Lifetime timer elapses, the Binding is placed 1122 in Stale state for a duration of STALE_DURATION (Section 12). 1124 9.3. Operations on a Binding in Stale State 1126 The Stale state enables tracking of the Backbone peers that have a 1127 NCE pointing to this 6BBR in case the Registered Address shows up 1128 later. 1130 If the Registered Address is claimed by another 6LN on the Backbone, 1131 with an NS(DAD) or an NA, the 6BBR does not defend the Address. 1133 For a Binding in Stale state: 1135 * The Binding MUST be removed if an NA or an NS(DAD) message is 1136 received over the Backbone for the Registered Address containing 1137 no EARO or an EARO that indicates either a fresher registration 1138 for the same Registered Node or a duplicate registration. A 1139 status of 4 (Removed) MAY be returned in an asynchronous NA(EARO) 1140 to the Registering Node. 1142 * NS(DAD) and NA messages containing an EARO that indicates a 1143 registration for the same Registered Node that is not as fresh as 1144 this MUST be answered with an NA message containing an EARO with a 1145 status of 3 (Moved). 1147 * If the 6BBR receives an NS(Lookup) or an NS(NUD) message for the 1148 Registered Address, the 6BBR MUST attempt a NUD procedure as 1149 specified in [RFC7048] to the Registering Node, targeting the 1150 Registered Address, prior to answering. If the NUD procedure 1151 succeeds, the operation in Reachable state applies. If the NUD 1152 fails, the 6BBR refrains from answering. 1154 * Other NS(DAD) and NA messages from the Backbone are ignored. 1156 When the STALE_DURATION (Section 12) timer elapses, the Binding MUST 1157 be removed. 1159 10. Registering Node Considerations 1161 A Registering Node MUST implement [RFC8505] in order to interact with 1162 a 6BBR (which acts as a routing registrar). Following [RFC8505], the 1163 Registering Node signals that it requires IPv6 proxy-ND services from 1164 a 6BBR by registering the corresponding IPv6 Address using an 1165 NS(EARO) message with the R flag set. 1167 The Registering Node may be the 6LN owning the IPv6 Address, or a 1168 6LBR that performs the registration on its behalf in a Route-Over 1169 mesh. 1171 The Registering Node MUST register all of its IPv6 Addresses to its 1172 6LR, which is the 6BBR when they are connected at Layer 2. Failure 1173 to register an address may result in the address being unreachable by 1174 other parties if the 6BBR cancels the NS(Lookup) over the LLN or to 1175 selected LLN nodes that are known to register their addresses. 1177 The Registering Node MUST refrain from using multicast NS(Lookup) 1178 when the destination is not known as on-link, e.g., if the prefix is 1179 advertised in a PIO with the L flag that is not set. In that case, 1180 the Registering Node sends its packets directly to its 6LR. 1182 The Registering Node SHOULD also follow [RFC7772] in order to limit 1183 the use of multicast RAs. It SHOULD also implement Simple Procedures 1184 for Detecting Network Attachment in IPv6 [RFC6059] (DNA procedures) 1185 to detect movements, and support Packet-Loss Resiliency for Router 1186 Solicitations [RFC7559] in order to improve reliability for the 1187 unicast RS messages. 1189 11. Security Considerations 1191 This specification applies to LLNs and a backbone in which the 1192 individual links are protected against rogue access, e.g., by 1193 authenticating a node that attaches to the network and encrypting at 1194 the MAC layer the transmissions that may be overheard. In 1195 particular, the LLN MAC is required to provide secure unicast to/from 1196 the Backbone Router and secure Broadcast from the Backbone Router in 1197 a way that prevents tampering with or replaying the RA messages. 1199 [I-D.ietf-6lo-ap-nd] guarantees the ownership of a registered address 1200 based on a proof-of-ownership encoded in the ROVR field and protects 1201 against address theft and impersonation inside the LLN, because the 1202 6LR can challenge the Registered Node for a proof-of-ownership. This 1203 method does not extend over the backbone since the 6BBR cannot 1204 provide the proof-of-ownership. A possible attack over the backbone 1205 can be done by sending an NS with an EARO and expecting the NA(EARO) 1206 back to contain the TID and ROVR fields of the existing state. With 1207 that information, the attacker can easily increase the TID and take 1208 over the Binding. 1210 12. Protocol Constants 1212 This Specification uses the following constants: 1214 TENTATIVE_DURATION: 800 milliseconds 1216 STALE_DURATION: see below 1218 In LLNs with long-lived Addresses such as LPWANs, STALE_DURATION 1219 SHOULD be configured with a relatively long value to cover an 1220 interval when the address may be reused, and before it is safe to 1221 expect that the address was definitively released. A good default 1222 value can be 24 hours. In LLNs where addresses are renewed rapidly, 1223 e.g., for privacy reasons, STALE_DURATION SHOULD be configured with a 1224 relatively shorter value, by default 5 minutes. 1226 13. IANA Considerations 1228 This document has no request to IANA. 1230 14. Acknowledgments 1232 Many thanks to Dorothy Stanley, Thomas Watteyne and Jerome Henry for 1233 their various contributions. Also many thanks to Timothy Winters and 1234 Erik Nordmark for their help, review and support in preparation to 1235 the IESG cycle, and to Kyle Rose, Elwyn Davies and Dominique Barthel 1236 for their useful contributions through the IETF last call and IESG 1237 process. 1239 15. Normative References 1241 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1242 Requirement Levels", BCP 14, RFC 2119, 1243 DOI 10.17487/RFC2119, March 1997, 1244 . 1246 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 1247 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 1248 2006, . 1250 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 1251 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 1252 . 1254 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1255 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1256 DOI 10.17487/RFC4861, September 2007, 1257 . 1259 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1260 Address Autoconfiguration", RFC 4862, 1261 DOI 10.17487/RFC4862, September 2007, 1262 . 1264 [RFC6059] Krishnan, S. and G. Daley, "Simple Procedures for 1265 Detecting Network Attachment in IPv6", RFC 6059, 1266 DOI 10.17487/RFC6059, November 2010, 1267 . 1269 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 1270 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 1271 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 1272 Low-Power and Lossy Networks", RFC 6550, 1273 DOI 10.17487/RFC6550, March 2012, 1274 . 1276 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 1277 Bormann, "Neighbor Discovery Optimization for IPv6 over 1278 Low-Power Wireless Personal Area Networks (6LoWPANs)", 1279 RFC 6775, DOI 10.17487/RFC6775, November 2012, 1280 . 1282 [RFC7048] Nordmark, E. and I. Gashinsky, "Neighbor Unreachability 1283 Detection Is Too Impatient", RFC 7048, 1284 DOI 10.17487/RFC7048, January 2014, 1285 . 1287 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1288 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1289 May 2017, . 1291 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1292 (IPv6) Specification", STD 86, RFC 8200, 1293 DOI 10.17487/RFC8200, July 2017, 1294 . 1296 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 1297 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 1298 DOI 10.17487/RFC8201, July 2017, 1299 . 1301 [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. 1302 Perkins, "Registration Extensions for IPv6 over Low-Power 1303 Wireless Personal Area Network (6LoWPAN) Neighbor 1304 Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, 1305 . 1307 16. Informative References 1309 [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery 1310 Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April 1311 2006, . 1313 [RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, 1314 DOI 10.17487/RFC4903, June 2007, 1315 . 1317 [RFC5415] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley, 1318 Ed., "Control And Provisioning of Wireless Access Points 1319 (CAPWAP) Protocol Specification", RFC 5415, 1320 DOI 10.17487/RFC5415, March 2009, 1321 . 1323 [RFC6606] Kim, E., Kaspar, D., Gomez, C., and C. Bormann, "Problem 1324 Statement and Requirements for IPv6 over Low-Power 1325 Wireless Personal Area Network (6LoWPAN) Routing", 1326 RFC 6606, DOI 10.17487/RFC6606, May 2012, 1327 . 1329 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1330 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 1331 2011, . 1333 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 1334 Locator/ID Separation Protocol (LISP)", RFC 6830, 1335 DOI 10.17487/RFC6830, January 2013, 1336 . 1338 [RFC7559] Krishnan, S., Anipko, D., and D. Thaler, "Packet-Loss 1339 Resiliency for Router Solicitations", RFC 7559, 1340 DOI 10.17487/RFC7559, May 2015, 1341 . 1343 [RFC7772] Yourtchenko, A. and L. Colitti, "Reducing Energy 1344 Consumption of Router Advertisements", BCP 202, RFC 7772, 1345 DOI 10.17487/RFC7772, February 2016, 1346 . 1348 [RFC8273] Brzozowski, J. and G. Van de Velde, "Unique IPv6 Prefix 1349 per Host", RFC 8273, DOI 10.17487/RFC8273, December 2017, 1350 . 1352 [I-D.yourtchenko-6man-dad-issues] 1353 Yourtchenko, A. and E. Nordmark, "A survey of issues 1354 related to IPv6 Duplicate Address Detection", Work in 1355 Progress, Internet-Draft, draft-yourtchenko-6man-dad- 1356 issues-01, 3 March 2015, . 1359 [I-D.nordmark-6man-dad-approaches] 1360 Nordmark, E., "Possible approaches to make DAD more robust 1361 and/or efficient", Work in Progress, Internet-Draft, 1362 draft-nordmark-6man-dad-approaches-02, 19 October 2015, 1363 . 1366 [I-D.ietf-6man-rs-refresh] 1367 Nordmark, E., Yourtchenko, A., and S. Krishnan, "IPv6 1368 Neighbor Discovery Optional RS/RA Refresh", Work in 1369 Progress, Internet-Draft, draft-ietf-6man-rs-refresh-02, 1370 31 October 2016, . 1373 [I-D.ietf-6lo-ap-nd] 1374 Thubert, P., Sarikaya, B., Sethi, M., and R. Struik, 1375 "Address Protected Neighbor Discovery for Low-power and 1376 Lossy Networks", Work in Progress, Internet-Draft, draft- 1377 ietf-6lo-ap-nd-19, 6 February 2020, 1378 . 1380 [I-D.ietf-6tisch-architecture] 1381 Thubert, P., "An Architecture for IPv6 over the TSCH mode 1382 of IEEE 802.15.4", Work in Progress, Internet-Draft, 1383 draft-ietf-6tisch-architecture-28, 29 October 2019, 1384 . 1387 [I-D.ietf-mboned-ieee802-mcast-problems] 1388 Perkins, C., McBride, M., Stanley, D., Kumari, W., and J. 1389 Zuniga, "Multicast Considerations over IEEE 802 Wireless 1390 Media", Work in Progress, Internet-Draft, draft-ietf- 1391 mboned-ieee802-mcast-problems-11, 11 December 2019, 1392 . 1395 [I-D.bi-savi-wlan] 1396 Bi, J., Wu, J., Wang, Y., and T. Lin, "A SAVI Solution for 1397 WLAN", Work in Progress, Internet-Draft, draft-bi-savi- 1398 wlan-18, 17 November 2019, 1399 . 1401 [I-D.thubert-6lo-unicast-lookup] 1402 Thubert, P. and E. Levy-Abegnoli, "IPv6 Neighbor Discovery 1403 Unicast Lookup", Work in Progress, Internet-Draft, draft- 1404 thubert-6lo-unicast-lookup-00, 25 January 2019, 1405 . 1408 [IEEEstd8021] 1409 IEEE standard for Information Technology, "IEEE Standard 1410 for Information technology -- Telecommunications and 1411 information exchange between systems Local and 1412 metropolitan area networks Part 1: Bridging and 1413 Architecture". 1415 [IEEEstd80211] 1416 IEEE standard for Information Technology, "IEEE Standard 1417 for Information technology -- Telecommunications and 1418 information exchange between systems Local and 1419 metropolitan area networks-- Specific requirements Part 1420 11: Wireless LAN Medium Access Control (MAC) and Physical 1421 Layer (PHY) Specifications". 1423 [IEEEstd802151] 1424 IEEE standard for Information Technology, "IEEE Standard 1425 for Information Technology - Telecommunications and 1426 Information Exchange Between Systems - Local and 1427 Metropolitan Area Networks - Specific Requirements. - Part 1428 15.1: Wireless Medium Access Control (MAC) and Physical 1429 Layer (PHY) Specifications for Wireless Personal Area 1430 Networks (WPANs)". 1432 [IEEEstd802154] 1433 IEEE standard for Information Technology, "IEEE Standard 1434 for Local and metropolitan area networks -- Part 15.4: 1435 Low-Rate Wireless Personal Area Networks (LR-WPANs)". 1437 Appendix A. Possible Future Extensions 1439 With the current specification, the 6LBR is not leveraged to avoid 1440 multicast NS(Lookup) on the Backbone. This could be done by adding a 1441 lookup procedure in the EDAR/EDAC exchange. 1443 By default the specification does not have a trust model, e.g., 1444 whereby nodes that associate their address with a proof-of-ownership 1445 [I-D.ietf-6lo-ap-nd] should be more trusted than nodes that do not. 1446 Such a trust model and related signaling could be added in the future 1447 to override the default operation and favor trusted nodes. 1449 Future documents may extend this specification by allowing the 6BBR 1450 to redistribute Host routes in routing protocols that would operate 1451 over the Backbone, or in MIPv6, or FMIP, or the Locator/ID Separation 1452 Protocol (LISP) [RFC6830] to support mobility on behalf of the 6LNs, 1453 etc... LISP may also be used to provide an equivalent to the EDAR/ 1454 EDAC exchange using a Map Server / Map Resolver as a replacement to 1455 the 6LBR. 1457 Appendix B. Applicability and Requirements Served 1459 This document specifies proxy-ND functions that can be used to 1460 federate an IPv6 Backbone Link and multiple IPv6 LLNs into a single 1461 Multi-Link Subnet. The proxy-ND functions enable IPv6 ND services 1462 for Duplicate Address Detection (DAD) and Address Lookup that do not 1463 require broadcasts over the LLNs. 1465 The term LLN is used to cover multiple types of WLANs and WPANs, 1466 including (Low-Power) Wi-Fi, BLUETOOTH(R) Low Energy, IEEE STD 1467 802.11ah and IEEE STD.802.15.4 wireless meshes, covering the types of 1468 networks listed in Appendix B.3 of [RFC8505] "Requirements Related to 1469 Various Low-Power Link Types". 1471 Each LLN in the subnet is attached to an IPv6 Backbone Router (6BBR). 1472 The Backbone Routers interconnect the LLNs and advertise the 1473 Addresses of the 6LNs over the Backbone Link using proxy-ND 1474 operations. 1476 This specification updates IPv6 ND over the Backbone to distinguish 1477 Address movement from duplication and eliminate stale state in the 1478 Backbone routers and Backbone nodes once a 6LN has roamed. This way, 1479 mobile nodes may roam rapidly from one 6BBR to the next and 1480 requirements in Appendix B.1 of [RFC8505] "Requirements Related to 1481 Mobility" are met. 1483 A 6LN can register its IPv6 Addresses and thereby obtain proxy-ND 1484 services over the Backbone, meeting the requirements expressed in 1485 Appendix B.4 of [RFC8505], "Requirements Related to Proxy 1486 Operations". 1488 The impact if the IPv6 ND operation is limited to one of the 1489 federated LLNs, enabling the number of 6LNs to grow. The Routing 1490 Proxy operation avoids the need to expose the MAC addresses of the 1491 6LNs onto the backbone, keeping the Layer 2 topology simple and 1492 stable. This meets the requirements in Appendix B.6 of [RFC8505] 1493 "Requirements Related to Scalability", as long has the 6BBRs are 1494 dimensioned for the number of registrations that each needs to 1495 support. 1497 In the case of a Wi-Fi access link, a 6BBR may be collocated with the 1498 Access Point (AP), or with a Fabric Edge (FE) or a CAPWAP [RFC5415] 1499 Wireless LAN Controller (WLC). In those cases, the wireless client 1500 (STA) is the 6LN that makes use of [RFC8505] to register its IPv6 1501 Address(es) to the 6BBR acting as Routing Registrar. The 6LBR can be 1502 centralized and either connected to the Backbone Link or reachable 1503 over IP. The 6BBR proxy-ND operations eliminate the need for 1504 wireless nodes to respond synchronously when a Lookup is performed 1505 for their IPv6 Addresses. This provides the function of a Sleep 1506 Proxy for ND [I-D.nordmark-6man-dad-approaches]. 1508 For the TimeSlotted Channel Hopping (TSCH) mode of [IEEEstd802154], 1509 the 6TiSCH architecture [I-D.ietf-6tisch-architecture] describes how 1510 a 6LoWPAN ND host could connect to the Internet via a RPL mesh 1511 Network, but doing so requires extensions to the 6LOWPAN ND protocol 1512 to support mobility and reachability in a secure and manageable 1513 environment. The extensions detailed in this document also work for 1514 the 6TiSCH architecture, serving the requirements listed in 1515 Appendix B.2 of [RFC8505] "Requirements Related to Routing 1516 Protocols". 1518 The registration mechanism may be seen as a more reliable alternate 1519 to snooping [I-D.bi-savi-wlan]. It can be noted that registration 1520 and snooping are not mutually exclusive. Snooping may be used in 1521 conjunction with the registration for nodes that do not register 1522 their IPv6 Addresses. The 6BBR assumes that if a node registers at 1523 least one IPv6 Address to it, then the node registers all of its 1524 Addresses to the 6BBR. With this assumption, the 6BBR can possibly 1525 cancel all undesirable multicast NS messages that would otherwise 1526 have been delivered to that node. 1528 Scalability of the Multi-Link Subnet [RFC4903] requires avoidance of 1529 multicast/broadcast operations as much as possible even on the 1530 Backbone [I-D.ietf-mboned-ieee802-mcast-problems]. Although hosts 1531 can connect to the Backbone using IPv6 ND operations, multicast RAs 1532 can be saved by using [I-D.ietf-6man-rs-refresh], which also requires 1533 the support of [RFC7559]. 1535 Authors' Addresses 1537 Pascal Thubert (editor) 1538 Cisco Systems, Inc 1539 Building D 1540 45 Allee des Ormes - BP1200 1541 06254 MOUGINS - Sophia Antipolis 1542 France 1544 Phone: +33 497 23 26 34 1545 Email: pthubert@cisco.com 1547 Charles E. Perkins 1548 Blue Meadow Networking 1549 Saratoga, 95070 1550 United States of America 1552 Email: charliep@computer.org 1554 Eric Levy-Abegnoli 1555 Cisco Systems, Inc 1556 Building D 1557 45 Allee des Ormes - BP1200 1558 06254 MOUGINS - Sophia Antipolis 1559 France 1560 Phone: +33 497 23 26 20 1561 Email: elevyabe@cisco.com