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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group F. Templin, Ed. 3 Internet-Draft The Boeing Company 4 Intended status: Standards Track A. Whyman 5 Expires: August 20, 2020 MWA Ltd c/o Inmarsat Global Ltd 6 February 17, 2020 8 Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) 9 Interfaces 10 draft-templin-atn-aero-interface-21 12 Abstract 14 Mobile nodes (e.g., aircraft of various configurations, terrestrial 15 vehicles, seagoing vessels, mobile enterprise devices, etc.) 16 communicate with networked correspondents over multiple access 17 network data links and configure mobile routers to connect end user 18 networks. A multilink interface specification is therefore needed 19 for coordination with the network-based mobility service. This 20 document specifies the transmission of IPv6 packets over Overlay 21 Multilink Network (OMNI) Interfaces. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on August 20, 2020. 40 Copyright Notice 42 Copyright (c) 2020 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 6 60 4. Overlay Multilink Network (OMNI) Interface Model . . . . . . 6 61 5. Maximum Transmission Unit (MTU) and Fragmentation . . . . . . 10 62 6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 11 63 7. Link-Local Addresses . . . . . . . . . . . . . . . . . . . . 11 64 8. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 12 65 8.1. Sub-Options . . . . . . . . . . . . . . . . . . . . . . . 14 66 8.1.1. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . 14 67 8.1.2. PadN . . . . . . . . . . . . . . . . . . . . . . . . 15 68 8.1.3. ifIndex-tuple (Type 1) . . . . . . . . . . . . . . . 15 69 8.1.4. ifIndex-tuple (Type 2) . . . . . . . . . . . . . . . 17 70 8.1.5. Notification ID . . . . . . . . . . . . . . . . . . . 18 71 9. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 18 72 10. Address Mapping for IPv6 Neighbor Discovery Messages . . . . 19 73 11. Conceptual Sending Algorithm . . . . . . . . . . . . . . . . 19 74 11.1. Multiple OMNI Interfaces . . . . . . . . . . . . . . . . 20 75 12. Router Discovery and Prefix Registration . . . . . . . . . . 20 76 13. AR and MSE Resilience . . . . . . . . . . . . . . . . . . . . 23 77 14. Detecting and Responding to MSE Failures . . . . . . . . . . 24 78 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 79 16. Security Considerations . . . . . . . . . . . . . . . . . . . 25 80 17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 81 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 82 18.1. Normative References . . . . . . . . . . . . . . . . . . 26 83 18.2. Informative References . . . . . . . . . . . . . . . . . 27 84 Appendix A. Type 1 ifIndex-tuple Traffic Classifier Preference 85 Encoding . . . . . . . . . . . . . . . . . . . . . . 29 86 Appendix B. Prefix Length Considerations . . . . . . . . . . . . 31 87 Appendix C. VDL Mode 2 Considerations . . . . . . . . . . . . . 31 88 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 32 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 91 1. Introduction 93 Mobile Nodes (MNs) (e.g., aircraft of various configurations, 94 terrestrial vehicles, seagoing vessels, mobile enterprise devices, 95 etc.) often have multiple data links for communicating with networked 96 correspondents. These data links may have diverse performance, cost 97 and availability properties that can change dynamically according to 98 mobility patterns, flight phases, proximity to infrastructure, etc. 99 MNs coordinate their data links in a discipline known as "multilink", 100 in which a single virtual interface is configured over the underlying 101 data link interfaces. 103 The MN configures a virtual interface (termed the "Overlay Multilink 104 Network (OMNI) interface") as a thin layer over the underlying access 105 network interfaces. The OMNI interface is therefore the only 106 interface abstraction exposed to the IPv6 layer and behaves according 107 to the Non-Broadcast, Multiple Access (NBMA) interface principle, 108 while underlying access network interfaces appear as link layer 109 communication channels in the architecture. The OMNI interface 110 connects to a virtual overlay service known as the "OMNI link". The 111 OMNI link spans a worldwide Internetwork that may include private-use 112 infrastructures and/or the global public Internet itself. 114 Each MN receives a Mobile Network Prefix (MNP) for numbering 115 downstream-attached End User Networks (EUNs) independently of the 116 access network data links selected for data transport. The MN 117 performs router discovery over the OMNI interface (i.e., similar to 118 IPv6 customer edge routers [RFC7084]) and acts as a mobile router on 119 behalf of its EUNs. The router discovery process is iterated over 120 each of the OMNI interface's underlying access network data links in 121 order to register per-link parameters (see Section 12). 123 The OMNI interface provides a multilink nexus for exchanging inbound 124 and outbound traffic via the correct underlying Access Network (ANET) 125 interface(s). The IPv6 layer sees the OMNI interface as a point of 126 connection to the OMNI link. Each OMNI link has one or more 127 associated Mobility Service Prefixes (MSPs) from which OMNI link MNPs 128 are derived. If there are multiple OMNI links, the IPv6 layer will 129 see multiple OMNI interfaces. 131 The OMNI interface interacts with a network-based Mobility Service 132 (MS) through IPv6 Neighbor Discovery (ND) control message exchanges 133 [RFC4861]. The MS provides Mobility Service Endpoints (MSEs) that 134 track MN movements and represent their MNPs in a global routing or 135 mapping system. 137 This document specifies the transmission of IPv6 packets [RFC8200] 138 and MN/MS control messaging over OMNI interfaces. 140 2. Terminology 142 The terminology in the normative references applies; especially, the 143 terms "link" and "interface" are the same as defined in the IPv6 144 [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications. 146 Also, the Protocol Constants defined in Section 10 of [RFC4861] are 147 used in their same format and meaning in this document. The terms 148 "All-Routers multicast", "All-Nodes multicast" and "Subnet-Router 149 anycast" are defined in [RFC4291] (with Link-Local scope assumed). 151 The following terms are defined within the scope of this document: 153 Mobile Node (MN) 154 an end system with multiple distinct upstream data link 155 connections that are managed together as a single logical unit. 156 The MN's data link connection parameters can change over time due 157 to, e.g., node mobility, link quality, etc. The MN further 158 connects a downstream-attached End User Network (EUN). The term 159 MN used here is distinct from uses in other documents, and does 160 not imply a particular mobility protocol. 162 End User Network (EUN) 163 a simple or complex downstream-attached mobile network that 164 travels with the MN as a single logical unit. The IPv6 addresses 165 assigned to EUN devices remain stable even if the MN's upstream 166 data link connections change. 168 Mobility Service (MS) 169 a mobile routing service that tracks MN movements and ensures that 170 MNs remain continuously reachable even across mobility events. 171 Specific MS details are out of scope for this document. 173 Mobility Service Endpoint (MSE) 174 an entity in the MS (either singluar or aggregate) that 175 coordinates the mobility events of one or more MN. 177 Mobility Service Prefix (MSP) 178 an aggregated IPv6 prefix (e.g., 2001:db8::/32) advertised to the 179 rest of the Internetwork by the MS, and from which more-specific 180 Mobile Network Prefixes (MNPs) are derived. 182 Mobile Network Prefix (MNP) 183 a longer IPv6 prefix taken from the MSP (e.g., 184 2001:db8:1000:2000::/56) and assigned to a MN. MNs sub-delegate 185 the MNP to devices located in EUNs. 187 Access Network (ANET) 188 a data link service network (e.g., an aviation radio access 189 network, satellite service provider network, cellular operator 190 network, wifi network, etc.) that connects MNs. Physical and/or 191 data link level security between the MN and ANET are assumed. 193 Access Router (AR) 194 a first-hop router in the ANET for connecting MNs to 195 correspondents in outside Internetworks. 197 ANET interface 198 a MN's attachment to a link in an ANET. 200 Internetwork (INET) 201 a connected network region with a coherent IP addressing plan that 202 provides transit forwarding services for ANET MNs and INET 203 correspondents. Examples include private enterprise networks, 204 ground domain aviation service networks and the global public 205 Internet itself. 207 INET interface 208 a node's attachment to a link in an INET. 210 OMNI link 211 a virtual overlay configured over one or more INETs and their 212 connected ANETs. An OMNI link can comprise multiple INET segments 213 joined by bridges the same as for any link; the addressing plans 214 in each segment may be mutually exclusive and managed by different 215 administrative entities. 217 OMNI interface 218 a node's attachment to an OMNI link, and configured over one or 219 more underlying ANET/INET interfaces. 221 OMNI link local address (LLA) 222 an IPv6 link-local address constructed as specified in Section 7, 223 and assigned to an OMNI interface. 225 OMNI Option 226 an IPv6 Neighbor Discovery option providing multilink parameters 227 for the OMNI interface as specified in Section 8. 229 Multilink 230 an OMNI interface's manner of managing diverse underlying data 231 link interfaces as a single logical unit. The OMNI interface 232 provides a single unified interface to upper layers, while 233 underlying data link selections are performed on a per-packet 234 basis considering factors such as DSCP, flow label, application 235 policy, signal quality, cost, etc. Multilinking decisions are 236 coordinated in both the outbound (i.e. MN to correspondent) and 237 inbound (i.e., correspondent to MN) directions. 239 L2 240 The second layer in the OSI network model. Also known as "layer- 241 2", "link-layer", "sub-IP layer", "data link layer", etc. 243 L3 244 The third layer in the OSI network model. Also known as "layer- 245 3", "network-layer", "IPv6 layer", etc. 247 3. Requirements 249 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 250 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 251 "OPTIONAL" in this document are to be interpreted as described in BCP 252 14 [RFC2119][RFC8174] when, and only when, they appear in all 253 capitals, as shown here. 255 An implementation is not required to internally use the architectural 256 constructs described here so long as its external behavior is 257 consistent with that described in this document. 259 4. Overlay Multilink Network (OMNI) Interface Model 261 An OMNI interface is a MN virtual interface configured over one or 262 more ANET interfaces, which may be physical (e.g., an aeronautical 263 radio link) or virtual (e.g., an Internet or higher-layer "tunnel"). 264 The MN receives a MNP from the MS, and coordinates with the MS 265 through IPv6 ND message exchanges. The MN uses the MNP to construct 266 a unique OMNI LLA through the algorithmic derivation specified in 267 Section 7 and assigns the LLA to the OMNI interface. 269 The OMNI interface architectural layering model is the same as in 270 [RFC7847], and augmented as shown in Figure 1. The IP layer (L3) 271 therefore sees the OMNI interface as a single network layer interface 272 with multiple underlying ANET interfaces that appear as L2 273 communication channels in the architecture. 275 +----------------------------+ 276 | Upper Layer Protocol | 277 Session-to-IP +---->| | 278 Address Binding | +----------------------------+ 279 +---->| IP (L3) | 280 IP Address +---->| | 281 Binding | +----------------------------+ 282 +---->| OMNI Interface | 283 Logical-to- +---->| (OMNI LLA) | 284 Physical | +----------------------------+ 285 Interface +---->| L2 | L2 | | L2 | 286 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 287 +------+------+ +------+ 288 | L1 | L1 | | L1 | 289 | | | | | 290 +------+------+ +------+ 292 Figure 1: OMNI Interface Architectural Layering Model 294 The OMNI virtual interface model gives rise to a number of 295 opportunities: 297 o since OMNI LLAs are uniquely derived from an MNP, no Duplicate 298 Address Detection (DAD) messaging is necessary over the OMNI 299 interface. 301 o ANET interfaces do not require any L3 addresses (i.e., not even 302 link-local) in environments where communications are coordinated 303 entirely over the OMNI interface. (An alternative would be to 304 also assign the same OMNI LLA to all ANET interfaces.) 306 o as ANET interface properties change (e.g., link quality, cost, 307 availability, etc.), any active ANET interface can be used to 308 update the profiles of multiple additional ANET interfaces in a 309 single message. This allows for timely adaptation and service 310 continuity under dynamically changing conditions. 312 o coordinating ANET interfaces in this way allows them to be 313 represented in a unified MS profile with provisions for mobility 314 and multilink operations. 316 o exposing a single virtual interface abstraction to the IPv6 layer 317 allows for multilink operation (including QoS based link 318 selection, packet replication, load balancing, etc.) at L2 while 319 still permitting L3 traffic shaping based on, e.g., DSCP, flow 320 label, etc. 322 o L3 sees the OMNI interface as a point of connection to the OMNI 323 link; if there are multiple OMNI links (i.e., multiple MS's), L3 324 will see multiple OMNI interfaces. 326 Other opportunities are discussed in [RFC7847]. 328 Figure 2 depicts the architectural model for a MN connecting to the 329 MS via multiple independent ANETs. When an ANET interface becomes 330 active, the MN's OMNI interface sends native (i.e., unencapsulated) 331 IPv6 ND messages via the underlying ANET interface. IPv6 ND messages 332 traverse the ground domain ANETs until they reach an Access Router 333 (AR#1, AR#2, .., AR#n). The AR then coordinates with a Mobility 334 Service Endpoint (MSE#1, MSE#2, ..., MSE#m) in the INET and returns 335 an IPv6 ND message response to the MN. IPv6 ND messages traverse the 336 ANET at layer 2; hence, the Hop Limit is not decremented. 338 +--------------+ 339 | MN | 340 +--------------+ 341 |OMNI interface| 342 +----+----+----+ 343 +--------|IF#1|IF#2|IF#n|------ + 344 / +----+----+----+ \ 345 / | \ 346 / <---- Native | IP ----> \ 347 v v v 348 (:::)-. (:::)-. (:::)-. 349 .-(::ANET:::) .-(::ANET:::) .-(::ANET:::) 350 `-(::::)-' `-(::::)-' `-(::::)-' 351 +----+ +----+ +----+ 352 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 353 . +-|--+ +-|--+ +-|--+ . 354 . | | | 355 . v v v . 356 . <----- Encapsulation -----> . 357 . . 358 . +-----+ (:::)-. . 359 . |MSE#2| .-(::::::::) +-----+ . 360 . +-----+ .-(::: INET :::)-. |MSE#m| . 361 . (::::: Routing ::::) +-----+ . 362 . `-(::: System :::)-' . 363 . +-----+ `-(:::::::-' . 364 . |MSE#1| +-----+ +-----+ . 365 . +-----+ |MSE#3| |MSE#4| . 366 . +-----+ +-----+ . 367 . . 368 . . 369 . <----- Worldwide Connected Internetwork ----> . 370 ........................................................... 372 Figure 2: MN/MS Coordination via Multiple ANETs 374 After the initial IPv6 ND message exchange, the MN can send and 375 receive unencapsulated IPv6 data packets over the OMNI interface. 376 OMNI interface multilink services will forward the packets via ARs in 377 the correct underlying ANETs. The AR encapsulates the packets 378 according to the capabilities provided by the MS and forwards them to 379 the next hop within the worldwide connected Internetwork via optimal 380 routes. 382 5. Maximum Transmission Unit (MTU) and Fragmentation 384 All IPv6 interfaces are REQUIRED to configure a minimum Maximum 385 Transmission Unit (MTU) of 1280 bytes [RFC8200]. The network 386 therefore MUST forward packets of at least 1280 bytes without 387 generating an IPv6 Path MTU Discovery (PMTUD) Packet Too Big (PTB) 388 message [RFC8201]. 390 The OMNI interface configures an MTU of 9180 bytes [RFC2492]; the 391 size is therefore not a reflection of the underlying ANET interface 392 MTUs, but rather determines the largest packet the OMNI interface can 393 forward or reassemble. 395 The OMNI interface can employ link-layer IPv6 encapsulation and 396 fragmentation/reassembly per [RFC2473], but its use is OPTIONAL since 397 correct operation will result in either case. Implementations that 398 omit link-layer IPv6 fragmentation/reassembly may be more prone to 399 dropping large packets and returning a PTB, while those that include 400 it may see performance increases at the expense of including 401 additional code. In both cases, OMNI interface neighbors are 402 responsible for advertising their willingness to reassemble. 404 The OMNI interface returns internally-generated PTB messages for 405 packets admitted into the interface that it deems too large for the 406 outbound underlying ANET interface (e.g., according to ANET 407 performance characteristics, MTU, etc). For all other packets, the 408 OMNI interface performs PMTUD even if the destination appears to be 409 on the same link since a proxy on the path could return a PTB 410 message. This ensures that the path MTU is adaptive and reflects the 411 current path used for a given data flow. 413 The MN's OMNI interface forwards packets that are no larger than the 414 MTU of the selected underlying ANET interface according to the ANET 415 L2 frame format. When the OMNI interface forwards a packet that is 416 larger than the ANET interface MTU, it drops the packet and returns a 417 PTB if the AR is not willing to reassemble. 419 Otherwise, the OMNI interface encapsulates the packet in an IPv6 420 header with source address set to the MN's link-local address and 421 destination address set to the link-local address of the MSE (see: 422 Section 7). The OMNI interface then uses IPv6 fragmentation to break 423 the encapsulated packet into fragments that are no larger than the 424 ANET interface MTU and sends the fragments over the ANET where they 425 will be intercepted by the AR. The AR then reassembles and conveys 426 the packet toward the final destination. 428 When an AR receives a fragmented or whole packet from the INET 429 destined to an ANET MN, it first determines whether to forward or 430 drop and return a PTB. If the AR deems the packet to be of 431 acceptable size, it first reassembles locally (if necessary) then 432 forwards the packet to the MN. If the (reassembled) packet is no 433 larger than the ANET MTU, the AR forwards according to the ANET L2 434 frame format. If the packet is larger than the ANET MTU, the AR 435 instead uses link-layer IPv6 encapsulation and fragmentation as above 436 if the MN accepts fragments or drops and returns a PTB otherwise. 437 The MN then reassembles and discards the encapsulation header, then 438 forwards the whole packet to the final destination. 440 Applications that cannot tolerate loss due to MTU restrictions SHOULD 441 avoid sending packets larger than 1280 bytes, since dynamic path 442 changes can reduce the path MTU at any time. Applications that may 443 benefit from sending larger packets even though the path MTU may 444 change dynamically MAY use larger sizes (i.e., up to the OMNI 445 interface MTU). 447 Note that when the AR forwards a fragmented packet received from the 448 INET, it is imperative that the AR reassembles locally first instead 449 of blindly forwarding fragments directly to the MN to avoid attacks 450 such as tiny fragments, overlapping fragments, etc. 452 6. Frame Format 454 The OMNI interface transmits IPv6 packets according to the native 455 frame format of each underlying ANET interface. For example, for 456 Ethernet-compatible interfaces the frame format is specified in 457 [RFC2464], for aeronautical radio interfaces the frame format is 458 specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical 459 Manual), for tunnels over IPv6 the frame format is specified in 460 [RFC2473], etc. 462 7. Link-Local Addresses 464 OMNI interfaces assign IPv6 Link-Local Addresses (i.e., "OMNI LLAs") 465 using the following constructs: 467 o IPv6 MN OMNI LLAs encode the most-significant 64 bits of a MNP 468 within the least-significant 64 bits (i.e., the interface ID) of a 469 Link-Local IPv6 Unicast Address (see: [RFC4291], Section 2.5.6). 470 For example, for the MNP 2001:db8:1000:2000::/56 the corresponding 471 LLA is fe80::2001:db8:1000:2000. 473 o IPv4-compatible MN OMNI LLAs are assigned as fe80::ffff:[v4addr], 474 i.e., the most significant 10 bits of the prefix fe80::/10, 475 followed by 70 '0' bits, followed by 16 '1' bits, followed by a 476 32bit IPv4 address. For example, the IPv4-Compatible MN OMNI LLA 477 for 192.0.2.1 is fe80::ffff:192.0.2.1 (also written as 478 fe80::ffff:c000:0201). 480 o MSE OMNI LLAs are assigned from the range fe80::/96, and MUST be 481 managed for uniqueness. The lower 32 bits of the LLA includes a 482 unique integer value between '1' and 'fffffffe', e.g., as in 483 fe80::1, fe80::2, fe80::3, etc., fe80::ffff:fffe. The address 484 fe80:: is the link-local Subnet-Router anycast address [RFC4291] 485 and the address fe80::ffff:ffff is reserved. (Note that distinct 486 OMNI link segments can avoid overlap by assigning MSE OMNI LLAs 487 from unique fe80::/96 sub-prefixes. For example, a first segment 488 could assign from fe80::1000/116, a second from fe80::2000/116, a 489 third from fe80::3000/116, etc.) 491 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 492 MNPs can be allocated from that block ensuring that there is no 493 possibility for overlap between the above OMNI LLA constructs. 495 Since MN OMNI LLAs are based on the distribution of administratively 496 assured unique MNPs, and since MSE OMNI LLAs are guaranteed unique 497 through administrative assignment, OMNI interfaces set the 498 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 500 8. Address Mapping - Unicast 502 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 503 state and use the link-local address format specified in Section 7. 504 IPv6 Neighbor Discovery (ND) [RFC4861] messages on MN OMNI interfaces 505 observe the native Source/Target Link-Layer Address Option (S/TLLAO) 506 formats of the underlying ANET interfaces (e.g., for Ethernet the S/ 507 TLLAO is specified in [RFC2464]). 509 MNs such as aircraft typically have many wireless data link types 510 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 511 etc.) with diverse performance, cost and availability properties. 512 The OMNI interface would therefore appear to have multiple L2 513 connections, and may include information for multiple ANET interfaces 514 in a single IPv6 ND message exchange. 516 OMNI interfaces use an IPv6 ND option called the "OMNI option" 517 formatted as shown in Figure 3: 519 0 1 2 3 520 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 521 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 522 | Type | Length | Prefix Length |R|P|A| Reserved| 523 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 524 | | 525 ~ Sub-Options ~ 526 | | 527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 529 Figure 3: OMNI Option Format 531 In this format: 533 o Type is set to TBD. 535 o Length is set to the number of 8 octet blocks in the option. 537 o Prefix Length is set according to the IPv6 source address type. 538 For MN OMNI LLAs, the value is set to the length of the embedded 539 MNP. For IPv4-compatible MN OMNI LLAs, the value is set to 96 540 plus the length of the embedded IPv4 prefix. For MSE OMNI LLAs, 541 the value is set to 128. 543 o R (the "Register/Release" bit) is set to '1' to register an MNP or 544 set to '0' to release a registration. 546 o P (the "Primary" bit) is set to '1' in a MN RS message to request 547 an AR to serve as primary, and set to '1' in the AR's RA message 548 to accept the primary role. Set to '0' in all other RS/RA 549 messages, and ignored in all other ND messages. 551 o A (the "Accepts Fragments" bit) is set to '1' in an RS/RA message 552 to indicate whether the sender is willing to accept OMNI interface 553 link-local fragments (see: Section 5). Nodes that are willing to 554 perform link-local reassembly set A to '1' (otherwise '0'). 556 o Reserved is set to the value '0' on transmission and ignored on 557 reception. 559 o Sub-Options is a Variable-length field, of length such that the 560 complete OMNI Option is an integer multiple of 8 octets long. 561 Contains one or more options, as described in Section 8.1. 563 8.1. Sub-Options 565 The OMNI option includes zero or more Sub-Options, some of which may 566 appear multiple times in the same message. Each consecutive Sub- 567 Option is concatenated immediately after its predecessor. All Sub- 568 Options except Pad1 (see below) are type-length-value (TLV) encoded 569 in the following format: 571 0 1 2 572 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 573 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 574 | Sub-Type | Sub-length | Sub-Option Data ... 575 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 577 Figure 4: Sub-Option Format 579 o Sub-Type is a 1-byte field that encodes the Sub-Option type. Sub- 580 Options defined in this document are: 582 Option Name Sub-Type 583 Pad1 0 584 PadN 1 585 ifIndex-tuple (Type 1) 2 586 ifIndex-tuple (Type 2) 3 587 Notification ID 4 589 Figure 5 591 Sub-Types 253 and 254 are reserved for experimentation, as 592 recommended in[RFC3692]]. 594 o Sub-Length is a 1-byte field that encodes the length of the Sub- 595 Body, in bytes 597 o Sub-Body is a byte string with format determined by Sub-Type 599 During processing, unrecognized Sub-Options are ignored and the next 600 Sub-Option processed until the end of the OMNI option. 602 The following Sub-Option types and formats are defined in this 603 document: 605 8.1.1. Pad1 606 0 607 0 1 2 3 4 5 6 7 608 +-+-+-+-+-+-+-+-+ 609 | Sub-Type=0 | 610 +-+-+-+-+-+-+-+-+ 612 Figure 6: Pad1 614 o Sub-Type is set to 0. 616 o No Sub-Length or Sub-Body follows (i.e., the "Sub-Option" consists 617 of a single zero octet). 619 8.1.2. PadN 621 0 1 2 622 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 624 | Sub-Type=1 |Sub-length=N-2 | N-2 padding bytes ... 625 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 627 Figure 7: PadN 629 o Sub-Type is set to 1. 631 o Sub-Length is set to N-2 being the number of padding bytes that 632 follow. 634 o Sub-Body consists of N-2 zero-valued octets. 636 8.1.3. ifIndex-tuple (Type 1) 638 0 1 2 3 639 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 640 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 641 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 643 | Provider ID | Link |S|I|RSV| Bitmap(0)=0xff|P00|P01|P02|P03| 644 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 645 |P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19| 646 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 647 |P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| Bitmap(1)=0xff| 648 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 649 |P32|P33|P34|P35|P36|P37|P38|P39| ... 650 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 652 Figure 8: ifIndex-tuple (Type 1) 654 o Sub-Type is set to 2. 656 o Sub-Length is set to 4+N (the number of Sub-Body bytes that 657 follow). 659 o Sub-Body contains an "ifIndex-tuple" (Type 1) encoded as follows 660 (note that the first four bytes must be present): 662 * ifIndex is set to an 8-bit integer value corresponding to a 663 specific underlying ANET interface. OMNI options MAY include 664 multiple ifIndex-tuples, and MUST number each with an ifIndex 665 value between '1' and '255' that represents a MN-specific 8-bit 666 mapping for the actual ifIndex value assigned to the ANET 667 interface by network management [RFC2863] (the ifIndex value 668 '0' is reserved for use by the MS). Multiple ifIndex-tuples 669 with the same ifIndex value MAY appear in the same OMNI option. 671 * ifType is set to an 8-bit integer value corresponding to the 672 underlying ANET interface identified by ifIndex. The value 673 represents an OMNI interface-specific 8-bit mapping for the 674 actual IANA ifType value registered in the 'IANAifType-MIB' 675 registry [http://www.iana.org]. 677 * Provider ID is set to an OMNI interface-specific 8-bit ID value 678 for the network service provider associated with this ifIndex. 680 * Link encodes a 4-bit link metric. The value '0' means the link 681 is DOWN, and the remaining values mean the link is UP with 682 metric ranging from '1' ("lowest") to '15' ("highest"). 684 * S is set to '1' if this ifIndex-tuple corresponds to the 685 underlying ANET interface that is the source of the ND message. 686 Set to '0' otherwise. 688 * I is set to '0' ("Simplex") if the index for each singleton 689 Bitmap byte in the Sub-Body is inferred from its sequential 690 position (i.e., 0, 1, 2, ...), or set to '1' ("Indexed") if 691 each Bitmap is preceded by an Index byte. Figure 8 shows the 692 simplex case for I set to '0'. For I set to '1', each Bitmap 693 is instead preceded by an Index that encodes a value "i" = (0 - 694 255) as the index for its companion Bitmap as follows: 696 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 697 | Index=i | Bitmap(i) |P[*] values ... 698 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 700 Figure 9 702 * RSV is set to the value 0 on transmission and ignored on 703 reception. 705 * The remainder of the Sub-Body contains N = (0 - 251) bytes of 706 traffic classifier preferences consisting of a first (indexed) 707 Bitmap (i.e., "Bitmap(i)") followed by 0-8 1-byte blocks of 708 2-bit P[*] values, followed by a second Bitmap (i), followed by 709 0-8 blocks of P[*] values, etc. Reading from bit 0 to bit 7, 710 the bits of each Bitmap(i) that are set to '1'' indicate the 711 P[*] blocks from the range P[(i*32)] through P[(i*32) + 31] 712 that follow; if any Bitmap(i) bits are '0', then the 713 corresponding P[*] block is instead omitted. For example, if 714 Bitmap(0) contains 0xff then the block with P[00]-P[03], 715 followed by the block with P[04]-P[07], etc., and ending with 716 the block with P[28]-P[31] are included (as showin in 717 Figure 8). The next Bitmap(i) is then consulted with its bits 718 indicating which P[*] blocks follow, etc. out to the end of the 719 Sub-Option. The first 16 P[*] blocks correspond to the 64 720 Differentiated Service Code Point (DSCP) values P[00] - P[63] 721 [RFC2474]. If additional P[*] blocks follow, their values 722 correspond to "pseudo-DSCP" traffic classifier values P[64], 723 P[65], P[66], etc. See Appendix A for further discussion and 724 examples. 726 * Each 2-bit P[*] field is set to the value '0' ("disabled"), '1' 727 ("low"), '2' ("medium") or '3' ("high") to indicate a QoS 728 preference level for ANET interface selection purposes. Not 729 all P[*] values need to be included in all OMNI option 730 instances of a given ifIndex-tuple. Any P[*] values 731 represented in an earlier OMNI option but ommitted in the 732 current OMNI option remain unchanged. Any P[*] values not yet 733 represented in any OMNI option default to "medium". 735 8.1.4. ifIndex-tuple (Type 2) 737 0 1 2 3 738 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 739 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 740 | Sub-Type=3 | Sub-length=4+N| ifIndex | ifType | 741 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 742 | Provider ID | Link |S|Resvd| ~ 743 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 744 ~ ~ 745 ~ RFC 6088 Format Traffic Selector ~ 746 ~ ~ 747 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 749 Figure 10: ifIndex-tuple (Type 2) 751 o Sub-Type is set to 3. 753 o Sub-Length is set to 4+N (the number of Sub-Body bytes that 754 follow). 756 o Sub-Body contains an "ifIndex-tuple" (Type 2) encoded as follows 757 (note that the first four bytes must be present): 759 * ifIndex, ifType, Provider ID, Link and S are set exactly as for 760 Type 1 ifIndex-tuples as specified in Section 8.1.3. 762 * the remainder of the Sub-Option body encodes a variable-length 763 traffic selector formatted per [RFC6088]. 765 8.1.5. Notification ID 767 0 1 2 3 768 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 770 | Sub-Type=4 | Sub-length=4 | Notification ID (bits 0 - 15) | 771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 772 | Notification ID (bits 16 - 32)| 773 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 775 Figure 11: Notification ID 777 o Sub-Type is set to 4. 779 o Sub-Length is set to 4. 781 o Notification ID contains the least-significant 32 bits of an MSE 782 OMNI LLA to notify (e.g., for the LLA fe80::face:cafe the field 783 contains 0xfacecafe). Valid only in MN RS messages, and ignored 784 in all other ND messages. OMNI options contain zero or more 785 Notification IDs. 787 9. Address Mapping - Multicast 789 The multicast address mapping of the native underlying ANET interface 790 applies. The mobile router on board the aircraft also serves as an 791 IGMP/MLD Proxy for its EUNs and/or hosted applications per [RFC4605] 792 while using the L2 address of the router as the L2 address for all 793 multicast packets. 795 10. Address Mapping for IPv6 Neighbor Discovery Messages 797 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 798 unicast link-scoped IPv6 destination address. However, IPv6 ND 799 messaging is coordinated between the MN and MS only without invoking 800 other nodes on the ANET. 802 For this reason, ANET links maintain unicast L2 addresses ("MSADDR") 803 for the purpose of supporting MN/MS IPv6 ND messaging. For Ethernet- 804 compatible ANETs, this specification reserves one Ethernet unicast 805 address TBD2. For non-Ethernet statically-addressed ANETs, MSADDR is 806 reserved per the assigned numbers authority for the ANET addressing 807 space. For still other ANETs, MSADDR may be dynamically discovered 808 through other means, e.g., L2 beacons. 810 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 811 both multicast and unicast) to an MSADDR instead of to an ordinary 812 unicast or multicast L2 address. In this way, all of the MN's IPv6 813 ND messages will be received by MS devices that are configured to 814 accept packets destined to MSADDR. Note that multiple MS devices on 815 the link could be configured to accept packets destined to MSADDR, 816 e.g., as a basis for supporting redundancy. 818 Therefore, ARs MUST accept and process packets destined to MSADDR, 819 while all other devices MUST NOT process packets destined to MSADDR. 820 This model has well-established operational experience in Proxy 821 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 823 11. Conceptual Sending Algorithm 825 The MN's IPv6 layer selects the outbound OMNI interface according to 826 standard IPv6 requirements when forwarding data packets from local or 827 EUN applications to external correspondents. The OMNI interface 828 maintains default routes and neighbor cache entries for MSEs, and may 829 also include additional neighbor cache entries created through other 830 means (e.g., Address Resolution, static configuration, etc.). 832 After a packet enters the OMNI interface, an outbound ANET interface 833 is selected based on multilink parameters such as DSCP, application 834 port number, cost, performance, message size, etc. OMNI interface 835 multilink selections could also be configured to perform replication 836 across multiple ANET interfaces for increased reliability at the 837 expense of packet duplication. 839 OMNI interface multilink service designers MUST observe the BCP 840 guidance in Section 15 [RFC3819] in terms of implications for 841 reordering when packets from the same flow may be spread across 842 multiple ANET interfaces having diverse properties. 844 11.1. Multiple OMNI Interfaces 846 MNs may associate with multiple MS instances concurrently. Each MS 847 instance represents a distinct OMNI link distinguished by its 848 associated MSPs. The MN configures a separate OMNI interface for 849 each link so that multiple interfaces (e.g., omni0, omni1, omni2, 850 etc.) are exposed to the IPv6 layer. 852 Depending on local policy and configuration, an MN may choose between 853 alternative active OMNI interfaces using a packet's DSCP, routing 854 information or static configuration. Interface selection based on 855 per-packet source addresses is also enabled when the MSPs for each 856 OMNI interface are known (e.g., discovered through Prefix Information 857 Options (PIOs) and/or Route Information Options (RIOs)). 859 Each OMNI interface can be configured over the same or different sets 860 of ANET interfaces. Each ANET distinguishes between the different 861 OMNI links based on the MSPs represented in per-packet IPv6 862 addresses. 864 Multiple distinct OMNI links can therefore be used to support fault 865 tolerance, load balancing, reliability, etc. The architectural model 866 parallels Layer 2 Virtual Local Area Networks (VLANs), where the MSPs 867 serve as (virtual) VLAN tags. 869 12. Router Discovery and Prefix Registration 871 ARs process IPv6 ND messages destined to All-Routers multicast 872 (ff02::2), Subnet-Router anycast (fe80::) and unicast IPv6 LLAs 873 [RFC4291]. ARs configure the L2 address MSADDR (see: Section 10) and 874 act as a proxy for MSE OMNI LLAs. 876 MNs interface with the MS by sending RS messages with OMNI options. 877 For each ANET interface, the MN sends an RS message with an OMNI 878 option, with L2 destination address set to MSADDR and with L3 879 destination address set to either a specific MSE OMNI LLA, link-local 880 Subnet-Router anycast, or All-Routers multicast. The MN discovers 881 MSE OMNI LLAs either through an RA message response to an initial 882 anycast/multicast RS or before sending an initial RS message. 883 [RFC5214] provides example MSE address discovery methods, including 884 information conveyed during data link login, name service lookups, 885 static configuration, etc. 887 The AR receives the RS messages and coordinates with the 888 corresponding MSE in a manner outside the scope of this document. 889 The AR returns an RA message with source address set to the MSE OMNI 890 LLA, with an OMNI option and with any information for the link that 891 would normally be delivered in a solicited RA message. (Note that if 892 all MSEs share common state, the AR can instead return an RA with 893 source address set to link-local Subnet-Router anycast.) 895 MNs configure OMNI interfaces that observe the properties discussed 896 in the previous section. The OMNI interface and its underlying 897 interfaces are said to be in either the "UP" or "DOWN" state 898 according to administrative actions in conjunction with the interface 899 connectivity status. An OMNI interface transitions to UP or DOWN 900 through administrative action and/or through state transitions of the 901 underlying interfaces. When a first underlying interface transitions 902 to UP, the OMNI interface also transitions to UP. When all 903 underlying interfaces transition to DOWN, the OMNI interface also 904 transitions to DOWN. 906 When an OMNI interface transitions to UP, the MN sends initial RS 907 messages to register its MNP and an initial set of underlying ANET 908 interfaces that are also UP. The MN sends additional RS messages to 909 refresh lifetimes and to register/deregister underlying ANET 910 interfaces as they transition to UP or DOWN. 912 ARs return RA messages with configuration information in response to 913 a MN's RS messages. The AR sets the RA Cur Hop Limit, M and O flags, 914 Router Lifetime, Reachable Time and Retrans Timer values as directed 915 by the MSE, and includes any necessary options such as: 917 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 919 o RIOs [RFC4191] with more-specific routes. 921 o an MTU option that specifies the maximum acceptable packet size 922 for this ANET interface. 924 The AR coordinates with the MSE and sends immediate unicast RA 925 responses without delay; therefore, the IPv6 ND MAX_RA_DELAY_TIME and 926 MIN_DELAY_BETWEEN_RAS constants for multicast RAs do not apply. The 927 AR MAY send periodic and/or event-driven unsolicited RA messages, but 928 is not required to do so for unicast advertisements [RFC4861]. 930 The MN sends RS messages from within the OMNI interface while using 931 an UP underlying ANET interface as the outbound interface. Each RS 932 message is formatted as though it originated from the IPv6 layer, but 933 the process is coordinated wholly from within the OMNI interface and 934 is therefore opaque to the IPv6 layer. The MN sends initial RS 935 messages over an UP underlying interface with its OMNI LLA as the 936 source and with destination set as discussed above. The RS messages 937 include an OMNI option per Section 8 with a valid Prefix Length, 938 (R,P,A) flags, and with ifIndex-tuples appropriate for underlying 939 ANET interfaces. The AR processes RS message and conveys the OMNI 940 option information to the MSE. 942 When the MSE processes the OMNI information, it first validates the 943 prefix registration information. If the prefix registration was 944 valid, the MSE injects the MNP into the routing/mapping system then 945 caches the new Prefix Length, MNP and ifIndex-tuples. If the MN's 946 OMNI option included one or more Notification IDs, the new MSE also 947 notifies the former MSE(s). The MSE then directs the AR to return an 948 RA message to the MN with an OMNI option per Section 8 and with a 949 non-zero Router Lifetime if the prefix registration was successful; 950 otherwise, with a zero Router Lifetime. 952 When the MN receives the RA message, it creates a default route with 953 L3 next hop address set to the address found in the RA source address 954 and with L2 address set to MSADDR. The AR will then forward packets 955 between the MN and the MS. 957 The MN then manages its underlying ANET interfaces according to their 958 states as follows: 960 o When an underlying ANET interface transitions to UP, the MN sends 961 an RS over the ANET interface with an OMNI option. The OMNI 962 option contains at least one ifIndex-tuple with values specific to 963 this ANET interface, and may contain additional ifIndex-tuples 964 specific to this and/or other ANET interfaces. 966 o When an underlying ANET interface transitions to DOWN, the MN 967 sends an RS or unsolicited NA message over any UP ANET interface 968 with an OMNI option containing an ifIndex-tuple for the DOWN ANET 969 interface with Link(i) set to '0'. The MN sends an RS when an 970 acknowledgement is required, or an unsolicited NA when reliability 971 is not thought to be a concern (e.g., if redundant transmissions 972 are sent on multiple ANET interfaces). 974 o When a MN wishes to release from a current MSE, it sends an RS or 975 unsolicited NA message over any UP ANET interfaces with an OMNI 976 option with R set to 0. The corresponding MSE then withdraws the 977 MNP from the routing/mapping system and (for RS responses) directs 978 the AR to return an RA message with an OMNI option and with Router 979 Lifetime set to 0. 981 o When a MN wishes to transition to a new MSE, it sends an RS or 982 unsolicited NA message over any UP ANET interfaces with an OMNI 983 option with R set to 1, with the new MSE OMNI LLA set in the 984 destination address, and (optionally) with a Notification ID 985 included for the former MSE. 987 o When all of a MNs underlying interfaces have transitioned to DOWN 988 (or if the prefix registration lifetime expires) the MSE withdraws 989 the MNP the same as if it had received a message with an OMNI 990 option with R set to 0. 992 The MN is responsible for retrying each RS exchange up to 993 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 994 seconds until an RA is received. If no RA is received over multiple 995 UP ANET interfaces, the MN declares this MSE unreachable and tries a 996 different MSE. 998 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 999 Therefore, when the IPv6 layer sends an RS message the OMNI interface 1000 returns an internally-generated RA message as though the message 1001 originated from an IPv6 router. The internally-generated RA message 1002 contains configuration information that is consistent with the 1003 information received from the RAs generated by the MS. 1005 Whether the OMNI interface IPv6 ND messaging process is initiated 1006 from the receipt of an RS message from the IPv6 layer is an 1007 implementation matter. Some implementations may elect to defer the 1008 IPv6 ND messaging process until an RS is received from the IPv6 1009 layer, while others may elect to initiate the process proactively. 1011 Note: The Router Lifetime value in RA messages indicates the time 1012 before which the MN must send another RS message over this underlying 1013 interface (e.g., 600 seconds), however that timescale may be 1014 significantly longer than the lifetime the MS has committed to retain 1015 the prefix registration (e.g., REACHABLETIME seconds). For this 1016 reason, the MN should select a primary AR, which is responsible for 1017 keeping the MS prefix registration alive on the MN's behalf. If the 1018 MN does not select a primary, then it must perform more frequent RS/ 1019 RA exchanges on its own behalf to refresh the MS prefix registration 1020 lifetime. 1022 13. AR and MSE Resilience 1024 ANETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 1025 [RFC5798] configurations so that service continuity is maintained 1026 even if one or more ARs fail. Using VRRP, the MN is unaware which of 1027 the (redundant) ARs is currently providing service, and any service 1028 discontinuity will be limited to the failover time supported by VRRP. 1029 Widely deployed public domain implementations of VRRP are available. 1031 MSEs SHOULD use high availability clustering services so that 1032 multiple redundant systems can provide coordinated response to 1033 failures. As with VRRP, widely deployed public domain 1034 implementations of high availability clustering services are 1035 available. Note that special-purpose and expensive dedicated 1036 hardware is not necessary, and public domain implementations can be 1037 used even between lightweight virtual machines in cloud deployments. 1039 14. Detecting and Responding to MSE Failures 1041 In environments where fast recovery from MSE failure is required, ARs 1042 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 1043 manner that parallels Bidirectional Forwarding Detection (BFD) 1044 [RFC5880] to track MSE reachability. ARs can then quickly detect and 1045 react to failures so that cached information is re-established 1046 through alternate paths. Proactive NUD control messaging is carried 1047 only over well-connected ground domain networks (i.e., and not low- 1048 end aeronautical radio links) and can therefore be tuned for rapid 1049 response. 1051 ARs perform proactive NUD for MSEs for which there are currently 1052 active ANET MNs. If an MSE fails, ARs can quickly inform MNs of the 1053 outage by sending multicast RA messages on the ANET interface. The 1054 AR sends RA messages to the MN via the ANET interface with source 1055 address set to the MSEs OMNI LLA, destination address set to All- 1056 Nodes multicast (ff02::1) [RFC4291], and Router Lifetime set to 0. 1058 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 1059 by small delays [RFC4861]. Any MNs on the ANET interface that have 1060 been using the (now defunct) MSE will receive the RA messages and 1061 associate with a new MSE. 1063 15. IANA Considerations 1065 The IANA is instructed to allocate an official Type number TBD from 1066 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 1067 option. Implementations set Type to 253 as an interim value 1068 [RFC4727]. 1070 The OMNI option also defines an 8-bit Sub-Type field, for which IANA 1071 is instructed to create and maintain a new registry entitled "OMNI 1072 option Sub-Type values". Initial values for the OMNI option Sub-Type 1073 values registry are given below; future assignments are to be made 1074 through Expert Review [RFC8126]. 1076 Value Sub-Type name Reference 1077 ----- ------------- ---------- 1078 0 Pad1 [RFCXXXX] 1079 1 PadN [RFCXXXX] 1080 2 ifIndex-tuple (Type 1) [RFCXXXX] 1081 3 ifIndex-tuple (Type 2) [RFCXXXX] 1082 4 Notification ID [RFCXXXX] 1083 5-252 Unassigned 1084 253-254 Experimental [RFCXXXX] 1085 255 Reserved [RFCXXXX] 1087 Figure 12: OMNI Option Sub-Type Values 1089 The IANA is instructed to allocate one Ethernet unicast address TBD2 1090 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 1091 Address Block - Unicast Use". 1093 16. Security Considerations 1095 Security considerations for IPv6 [RFC8200] and IPv6 Neighbor 1096 Discovery [RFC4861] apply. OMNI interface IPv6 ND messages SHOULD 1097 include Nonce and Timestamp options [RFC3971] when synchronized 1098 transaction confirmation is needed. 1100 Security considerations for specific access network interface types 1101 are covered under the corresponding IP-over-(foo) specification 1102 (e.g., [RFC2464], [RFC2492], etc.). 1104 17. Acknowledgements 1106 The first version of this document was prepared per the consensus 1107 decision at the 7th Conference of the International Civil Aviation 1108 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 1109 2019. Consensus to take the document forward to the IETF was reached 1110 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 1111 Attendees and contributors included: Guray Acar, Danny Bharj, 1112 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 1113 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 1114 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 1115 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 1116 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 1117 Fryderyk Wrobel and Dongsong Zeng. 1119 The following individuals are acknowledged for their useful comments: 1120 Michael Matyas, Madhu Niraula, Greg Saccone, Stephane Tamalet, Eric 1121 Vyncke. Pavel Drasil, Zdenek Jaron and Michal Skorepa are recognized 1122 for their many helpful ideas and suggestions. 1124 This work is aligned with the NASA Safe Autonomous Systems Operation 1125 (SASO) program under NASA contract number NNA16BD84C. 1127 This work is aligned with the FAA as per the SE2025 contract number 1128 DTFAWA-15-D-00030. 1130 18. References 1132 18.1. Normative References 1134 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1135 Requirement Levels", BCP 14, RFC 2119, 1136 DOI 10.17487/RFC2119, March 1997, 1137 . 1139 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1140 "Definition of the Differentiated Services Field (DS 1141 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1142 DOI 10.17487/RFC2474, December 1998, 1143 . 1145 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 1146 "SEcure Neighbor Discovery (SEND)", RFC 3971, 1147 DOI 10.17487/RFC3971, March 2005, 1148 . 1150 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 1151 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 1152 November 2005, . 1154 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 1155 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 1156 2006, . 1158 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 1159 ICMPv6, UDP, and TCP Headers", RFC 4727, 1160 DOI 10.17487/RFC4727, November 2006, 1161 . 1163 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1164 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1165 DOI 10.17487/RFC4861, September 2007, 1166 . 1168 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1169 Address Autoconfiguration", RFC 4862, 1170 DOI 10.17487/RFC4862, September 2007, 1171 . 1173 [RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont, 1174 "Traffic Selectors for Flow Bindings", RFC 6088, 1175 DOI 10.17487/RFC6088, January 2011, 1176 . 1178 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 1179 Hosts in a Multi-Prefix Network", RFC 8028, 1180 DOI 10.17487/RFC8028, November 2016, 1181 . 1183 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1184 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1185 May 2017, . 1187 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1188 (IPv6) Specification", STD 86, RFC 8200, 1189 DOI 10.17487/RFC8200, July 2017, 1190 . 1192 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 1193 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 1194 DOI 10.17487/RFC8201, July 2017, 1195 . 1197 18.2. Informative References 1199 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 1200 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 1201 . 1203 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 1204 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 1205 . 1207 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 1208 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 1209 December 1998, . 1211 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 1212 Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999, 1213 . 1215 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 1216 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 1217 . 1219 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 1220 Considered Useful", BCP 82, RFC 3692, 1221 DOI 10.17487/RFC3692, January 2004, 1222 . 1224 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 1225 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 1226 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 1227 RFC 3819, DOI 10.17487/RFC3819, July 2004, 1228 . 1230 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 1231 "Internet Group Management Protocol (IGMP) / Multicast 1232 Listener Discovery (MLD)-Based Multicast Forwarding 1233 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 1234 August 2006, . 1236 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 1237 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 1238 RFC 5213, DOI 10.17487/RFC5213, August 2008, 1239 . 1241 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 1242 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 1243 DOI 10.17487/RFC5214, March 2008, 1244 . 1246 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 1247 Version 3 for IPv4 and IPv6", RFC 5798, 1248 DOI 10.17487/RFC5798, March 2010, 1249 . 1251 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 1252 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 1253 . 1255 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 1256 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 1257 2012, . 1259 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 1260 Requirements for IPv6 Customer Edge Routers", RFC 7084, 1261 DOI 10.17487/RFC7084, November 2013, 1262 . 1264 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 1265 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1266 Boundary in IPv6 Addressing", RFC 7421, 1267 DOI 10.17487/RFC7421, January 2015, 1268 . 1270 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 1271 Support for IP Hosts with Multi-Access Support", RFC 7847, 1272 DOI 10.17487/RFC7847, May 2016, 1273 . 1275 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1276 Writing an IANA Considerations Section in RFCs", BCP 26, 1277 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1278 . 1280 Appendix A. Type 1 ifIndex-tuple Traffic Classifier Preference Encoding 1282 Adaptation of the OMNI option Type 1 ifIndex-tuple's traffic 1283 classifier bitmap to specific Internetworks such as the Aeronautical 1284 Telecommunications Network with Internet Protocol Services (ATN/IPS) 1285 may include link selection preferences based on other traffic 1286 classifiers (e.g., transport port numbers, etc.) in addition to the 1287 existing DSCP-based preferences. Nodes on specific Internetworks 1288 maintain a map of traffic classifiers to additional P[*] preference 1289 fields beyond the first 64. For example, TCP port 22 maps to P[67], 1290 TCP port 443 maps to P[70], UDP port 8060 maps to P[76], etc. 1292 Implementations use Simplex or Indexed encoding formats for P[*] 1293 encoding in order to encode a given set of traffic classifiers in the 1294 most efficient way. Some use cases may be more efficiently coded 1295 using Simplex form, while others may be more efficient using Indexed. 1296 Once a format is selected for preparation of a single ifIndex-tuple 1297 the same format must be used for the entire Sub-Option. Different 1298 Sub-Options may use different formats. 1300 The following examples show coding examples for various Simplex and 1301 Indexed formats: 1303 0 1 2 3 1304 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1306 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 1307 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1308 | Provider ID | Link |S|0|RSV| Bitmap(0)=0xff|P00|P01|P02|P03| 1309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1310 |P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19| 1311 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1312 |P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| Bitmap(1)=0xff| 1313 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1314 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 1315 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1316 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1317 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1318 | Bitmap(2)=0xff|P64|P65|P67|P68| ... 1319 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1321 Figure 13: Example 1: Dense Simplex Encoding 1323 0 1 2 3 1324 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1326 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 1327 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1328 | Provider ID | Link |S|0|RSV| Bitmap(0)=0x00| Bitmap(1)=0x0f| 1329 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1330 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1332 | Bitmap(2)=0x00| Bitmap(3)=0x00| Bitmap(4)=0x00| Bitmap(5)=0x00| 1333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1334 | Bitmap(6)=0xf0|192|193|194|195|196|197|198|199|200|201|202|203| 1335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1336 |204|205|206|207| Bitmap(7)=0x00| Bitmap(8)=0x0f|272|273|274|275| 1337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1338 |276|277|278|279|280|281|282|283|284|285|286|287| Bitmap(9)=0x00| 1339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1340 |Bitmap(10)=0x00| ... 1341 +-+-+-+-+-+-+-+-+-+-+- 1343 Figure 14: Example 2: Sparse Simplex Encoding 1345 0 1 2 3 1346 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1347 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1348 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 1349 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1350 | Provider ID | Link |S|1|RSV| Index = 0x00 | Bitmap = 0x80 | 1351 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1352 |P00|P01|P02|P03| Index = 0x01 | Bitmap = 0x01 |P60|P61|P62|P63| 1353 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1354 | Index = 0x10 | Bitmap = 0x80 |512|513|514|515| Index = 0x18 | 1355 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1356 | Bitmap = 0x01 |796|797|798|799| ... 1357 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1359 Figure 15: Example 3: Indexed Encoding 1361 Appendix B. Prefix Length Considerations 1363 The 64-bit boundary in IPv6 addresses [RFC7421] determines the MN 1364 OMNI LLA format for encoding the most-significant 64 MNP bits into 1365 the least-significant 64 bits of the prefix fe80::/64 as discussed in 1366 Section 7. 1368 [RFC4291] defines the link-local address format as the most 1369 significant 10 bits of the prefix fe80::/10, followed by 54 unused 1370 bits, followed by the least-significant 64 bits of the address. If 1371 the 64-bit boundary is relaxed through future standards activity, 1372 then the 54 unused bits can be employed for extended coding of MNPs 1373 of length /65 up to /118. 1375 The extended coding format would continue to encode MNP bits 0-63 in 1376 bits 64-127 of the OMNI LLA, while including MNP bits 64-117 in bits 1377 10-63. For example, the OMNI LLA corresponding to the MNP 1378 2001:db8:1111:2222:3333:4444:5555::/112 would be 1379 fe8c:ccd1:1115:5540:2001:db8:1111:2222, and would still be a valid 1380 IPv6 LLA per [RFC4291]. 1382 Appendix C. VDL Mode 2 Considerations 1384 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 1385 (VDLM2) that specifies an essential radio frequency data link service 1386 for aircraft and ground stations in worldwide civil aviation air 1387 traffic management. The VDLM2 link type is "multicast capable" 1388 [RFC4861], but with considerable differences from common multicast 1389 links such as Ethernet and IEEE 802.11. 1391 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 1392 magnitude less than most modern wireless networking gear. Second, 1393 due to the low available link bandwidth only VDLM2 ground stations 1394 (i.e., and not aircraft) are permitted to send broadcasts, and even 1395 so only as compact layer 2 "beacons". Third, aircraft employ the 1396 services of ground stations by performing unicast RS/RA exchanges 1397 upon receipt of beacons instead of listening for multicast RA 1398 messages and/or sending multicast RS messages. 1400 This beacon-oriented unicast RS/RA approach is necessary to conserve 1401 the already-scarce available link bandwidth. Moreover, since the 1402 numbers of beaconing ground stations operating within a given spatial 1403 range must be kept as sparse as possible, it would not be feasible to 1404 have different classes of ground stations within the same region 1405 observing different protocols. It is therefore highly desirable that 1406 all ground stations observe a common language of RS/RA as specified 1407 in this document. 1409 Note that links of this nature may benefit from compression 1410 techniques that reduce the bandwidth necessary for conveying the same 1411 amount of data. The IETF lpwan working group is considering possible 1412 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 1414 Appendix D. Change Log 1416 << RFC Editor - remove prior to publication >> 1418 Differences from draft-templin-atn-aero-interface-20 to draft- 1419 templin-atn-aero-interface-21: 1421 o OMNI option format 1423 o MTU 1425 Differences from draft-templin-atn-aero-interface-19 to draft- 1426 templin-atn-aero-interface-20: 1428 o MTU 1430 Differences from draft-templin-atn-aero-interface-18 to draft- 1431 templin-atn-aero-interface-19: 1433 o MTU 1435 Differences from draft-templin-atn-aero-interface-17 to draft- 1436 templin-atn-aero-interface-18: 1438 o MTU and RA configuration information updated. 1440 Differences from draft-templin-atn-aero-interface-16 to draft- 1441 templin-atn-aero-interface-17: 1443 o New "Primary" flag in OMNI option. 1445 Differences from draft-templin-atn-aero-interface-15 to draft- 1446 templin-atn-aero-interface-16: 1448 o New note on MSE OMNI LLA uniqueness assurance. 1450 o General cleanup. 1452 Differences from draft-templin-atn-aero-interface-14 to draft- 1453 templin-atn-aero-interface-15: 1455 o General cleanup. 1457 Differences from draft-templin-atn-aero-interface-13 to draft- 1458 templin-atn-aero-interface-14: 1460 o General cleanup. 1462 Differences from draft-templin-atn-aero-interface-12 to draft- 1463 templin-atn-aero-interface-13: 1465 o Minor re-work on "Notify-MSE" (changed to Notification ID). 1467 Differences from draft-templin-atn-aero-interface-11 to draft- 1468 templin-atn-aero-interface-12: 1470 o Removed "Request/Response" OMNI option formats. Now, there is 1471 only one OMNI option format that applies to all ND messages. 1473 o Added new OMNI option field and supporting text for "Notify-MSE". 1475 Differences from draft-templin-atn-aero-interface-10 to draft- 1476 templin-atn-aero-interface-11: 1478 o Changed name from "aero" to "OMNI" 1480 o Resolved AD review comments from Eric Vyncke (posted to atn list) 1482 Differences from draft-templin-atn-aero-interface-09 to draft- 1483 templin-atn-aero-interface-10: 1485 o Renamed ARO option to AERO option 1487 o Re-worked Section 13 text to discuss proactive NUD. 1489 Differences from draft-templin-atn-aero-interface-08 to draft- 1490 templin-atn-aero-interface-09: 1492 o Version and reference update 1494 Differences from draft-templin-atn-aero-interface-07 to draft- 1495 templin-atn-aero-interface-08: 1497 o Removed "Classic" and "MS-enabled" link model discussion 1499 o Added new figure for MN/AR/MSE model. 1501 o New Section on "Detecting and responding to MSE failure". 1503 Differences from draft-templin-atn-aero-interface-06 to draft- 1504 templin-atn-aero-interface-07: 1506 o Removed "nonce" field from AR option format. Applications that 1507 require a nonce can include a standard nonce option if they want 1508 to. 1510 o Various editorial cleanups. 1512 Differences from draft-templin-atn-aero-interface-05 to draft- 1513 templin-atn-aero-interface-06: 1515 o New Appendix C on "VDL Mode 2 Considerations" 1517 o New Appendix D on "RS/RA Messaging as a Single Standard API" 1519 o Various significant updates in Section 5, 10 and 12. 1521 Differences from draft-templin-atn-aero-interface-04 to draft- 1522 templin-atn-aero-interface-05: 1524 o Introduced RFC6543 precedent for focusing IPv6 ND messaging to a 1525 reserved unicast link-layer address 1527 o Introduced new IPv6 ND option for Aero Registration 1529 o Specification of MN-to-MSE message exchanges via the ANET access 1530 router as a proxy 1532 o IANA Considerations updated to include registration requests and 1533 set interim RFC4727 option type value. 1535 Differences from draft-templin-atn-aero-interface-03 to draft- 1536 templin-atn-aero-interface-04: 1538 o Removed MNP from aero option format - we already have RIOs and 1539 PIOs, and so do not need another option type to include a Prefix. 1541 o Clarified that the RA message response must include an aero option 1542 to indicate to the MN that the ANET provides a MS. 1544 o MTU interactions with link adaptation clarified. 1546 Differences from draft-templin-atn-aero-interface-02 to draft- 1547 templin-atn-aero-interface-03: 1549 o Sections re-arranged to match RFC4861 structure. 1551 o Multiple aero interfaces 1553 o Conceptual sending algorithm 1555 Differences from draft-templin-atn-aero-interface-01 to draft- 1556 templin-atn-aero-interface-02: 1558 o Removed discussion of encapsulation (out of scope) 1560 o Simplified MTU section 1562 o Changed to use a new IPv6 ND option (the "aero option") instead of 1563 S/TLLAO 1565 o Explained the nature of the interaction between the mobility 1566 management service and the air interface 1568 Differences from draft-templin-atn-aero-interface-00 to draft- 1569 templin-atn-aero-interface-01: 1571 o Updates based on list review comments on IETF 'atn' list from 1572 4/29/2019 through 5/7/2019 (issue tracker established) 1574 o added list of opportunities afforded by the single virtual link 1575 model 1577 o added discussion of encapsulation considerations to Section 6 1579 o noted that DupAddrDetectTransmits is set to 0 1581 o removed discussion of IPv6 ND options for prefix assertions. The 1582 aero address already includes the MNP, and there are many good 1583 reasons for it to continue to do so. Therefore, also including 1584 the MNP in an IPv6 ND option would be redundant. 1586 o Significant re-work of "Router Discovery" section. 1588 o New Appendix B on Prefix Length considerations 1590 First draft version (draft-templin-atn-aero-interface-00): 1592 o Draft based on consensus decision of ICAO Working Group I Mobility 1593 Subgroup March 22, 2019. 1595 Authors' Addresses 1597 Fred L. Templin (editor) 1598 The Boeing Company 1599 P.O. Box 3707 1600 Seattle, WA 98124 1601 USA 1603 Email: fltemplin@acm.org 1605 Tony Whyman 1606 MWA Ltd c/o Inmarsat Global Ltd 1607 99 City Road 1608 London EC1Y 1AX 1609 England 1611 Email: tony.whyman@mccallumwhyman.com