idnits 2.17.1 draft-templin-atn-aero-interface-11.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 -- The document date (January 8, 2020) is 1542 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) -- Looks like a reference, but probably isn't: '1' on line 449 -- Looks like a reference, but probably isn't: '2' on line 459 == Missing Reference: 'N' is mentioned on line 471, but not defined == Unused Reference: 'RFC2225' is defined on line 942, but no explicit reference was found in the text Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). 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: July 11, 2020 MWA Ltd c/o Inmarsat Global Ltd 6 January 8, 2020 8 Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) 9 Interfaces 10 draft-templin-atn-aero-interface-11 12 Abstract 14 Mobile nodes (e.g., aircraft of various configurations, terrestrial 15 vehicles, seagoing vessels, etc.) communicate with networked 16 correspondents over multiple access network data links and configure 17 mobile routers to connect their on-board networks. A multilink 18 interface specification is therefore needed for coordination with the 19 network-based mobility service. This document specifies the 20 transmission of IPv6 packets over Overlay Multilink Network (OMNI) 21 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 July 11, 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 . . . . . . . . . . . . . . . . . . . . . . . . 5 60 4. Overlay Multilink Network Interface (OMNI) Model . . . . . . 5 61 5. Maximum Transmission Unit . . . . . . . . . . . . . . . . . . 9 62 6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 9 63 7. Link-Local Addresses . . . . . . . . . . . . . . . . . . . . 9 64 8. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 10 65 9. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 14 66 10. Address Mapping for IPv6 Neighbor Discovery Messages . . . . 14 67 11. Conceptual Sending Algorithm . . . . . . . . . . . . . . . . 14 68 11.1. Multiple Aero Interfaces . . . . . . . . . . . . . . . . 15 69 12. Router Discovery and Prefix Registration . . . . . . . . . . 15 70 13. AR and MSE Resilience . . . . . . . . . . . . . . . . . . . . 18 71 14. Detecting and Responding to MSE Failures . . . . . . . . . . 18 72 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 73 16. Security Considerations . . . . . . . . . . . . . . . . . . . 19 74 17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 75 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 76 18.1. Normative References . . . . . . . . . . . . . . . . . . 20 77 18.2. Informative References . . . . . . . . . . . . . . . . . 21 78 Appendix A. OMNI Option Extensions for Pseudo-DSCP Mappings . . 22 79 Appendix B. Prefix Length Considerations . . . . . . . . . . . . 23 80 Appendix C. VDL Mode 2 Considerations . . . . . . . . . . . . . 24 81 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 24 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 84 1. Introduction 86 Mobile Nodes (MNs) (e.g., aircraft of various configurations, 87 terrestrial vehicles, seagoing vessels, etc.) often have multiple 88 data links for communicating with networked correspondents. These 89 data links may have diverse performance, cost and availability 90 characteristics that can change dynamically according to mobility 91 patterns, flight phases, proximity to infrastructure, etc. MNs 92 coordinate their data links in a discipline known as "multilink", in 93 which a single virtual interface is configured over the underlying 94 data link interfaces. 96 The MN configures a virtual interface (termed the "Overlay Multilink 97 Network (OMNI) interface") as a thin layer over the underlying access 98 network interfaces. The OMNI interface is therefore the only 99 interface abstraction exposed to the IPv6 layer and behaves according 100 to the Non-Broadcast, Multiple Access (NBMA) interface principle, 101 while underlying access network interfaces appear as link layer 102 communication channels in the architecture. The OMNI interface 103 connects to a virtual overlay service known as the "OMNI link". The 104 OMNI link spans a worldwide Internetwork that may include private-use 105 infrastructures and/or the global public Internet itself. 107 Each MN receives a Mobile Network Prefix (MNP) that can be used by 108 on-board networks independently of the access network data links 109 selected for data transport. The MN performs router discovery over 110 the OMNI interface (i.e., similar to IPv6 customer edge routers 111 [RFC7084]) and acts as a mobile router on behalf of its on-board 112 networks. The router discovery process is iterated over each of the 113 OMNI interface's underlying access network data links in order to 114 register per-link parameters (see Section 12). 116 The OMNI interface provides a multilink nexus for guiding inbound and 117 outbound traffic to the correct underlying Access Network (ANET) 118 interface(s). The IPv6 layer sees the OMNI interface as a point of 119 connection to the OMNI link. Each OMNI link has one or more 120 associated Mobility Service Prefixes (MSPs) from which OMNI link MNPs 121 are derived. If there are multiple OMNI links, the IPv6 layer will 122 see multiple OMNI interfaces. 124 The OMNI interface interacts with an internetwork Mobility Service 125 (MS) through IPv6 Neighbor Discovery (ND) control message exchanges 126 [RFC4861]. The MS provides Mobility Service Endpoints (MSEs) that 127 track MN movements and represent their MNPs in a global routing or 128 mapping system. 130 This document specifies the transmission of IPv6 packets [RFC8200] 131 and MN/MS control messaging over OMNI interfaces. 133 2. Terminology 135 The terminology in the normative references applies; especially, the 136 terms "link" and "interface" are the same as defined in the IPv6 137 [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications. 138 Also, the Protocol Constants defined in Section 10 of [RFC4861] are 139 used in their same format and meaning in this document. 141 The following terms are defined within the scope of this document: 143 Mobile Node (MN) 144 an end system with multiple distinct data link connections that 145 are managed together as a single logical unit. The MN connects a 146 simple or complex local area network, and its data link connection 147 parameters can change over time due to, e.g., node mobility, link 148 quality, etc. The term MN used here is distinct from uses in 149 other documents, and does not imply a particular mobility 150 protocol. 152 End User Network (EUN) 153 a simple or complex local area network that travels with the MN as 154 a single logical unit. The IPv6 addresses assigned to EUN devices 155 remain statble even if the MN's data link connections change. 157 Mobility Service (MS) 158 a mobile routing service that tracks MN movements and ensures that 159 MNs remain continuously reachable even across mobility events. 160 Specific MS details are out of scope for this document. 162 Mobility Service Prefix (MSP) 163 an aggregated IPv6 prefix (e.g., 2001:db8::/32) advertised to the 164 rest of the Internetwork by the MS, and from which more-specific 165 Mobile Network Prefixes (MNPs) are derived. 167 Mobile Network Prefix (MNP) 168 a longer IPv6 prefix taken from the MSP (e.g., 169 2001:db8:1000:2000::/56) and assigned to a MN. MNs sub-delegate 170 the MNP to devices located in EUNs. 172 Access Network (ANET) 173 a data link service network (e.g., an aviation radio access 174 network, satellite service provider network, cellular operator 175 network, etc.) that provides an Access Router (AR) for connecting 176 MNs to correspondents in outside Internetworks. Physical and/or 177 data link level security between the MN and AR are assumed. 179 ANET interface 180 a MN's attachment to a link in an ANET. 182 Internetwork (INET) 183 a connected network region with a coherent IP addressing plan that 184 provides transit forwarding services for ANET MNs and INET 185 correspondents. Examples include private enterprise networks, 186 aviation networks and the global public Internet itself. 188 INET interface 189 a node's attachment to a link in an INET. 191 OMNI link 192 a virtual overlay configured over one or more INETs and their 193 connected ANETs. An OMNI link can comprise multiple INET segments 194 joined by bridges the same as for any link; the addressing plans 195 in each segment may be mutually exclusive and managed by different 196 administrative entities. 198 OMNI interface 199 a node's attachment to an OMNI link, and configured over one or 200 more underlying ANET/INET interfaces. 202 OMNI link local address (LLA) 203 an IPv6 link-local address constructed as specified in Section 7, 204 and assigned to an OMNI interface. 206 Multilink 207 an OMNI interface's manner of managing diverse underlying data 208 link interfaces as a single logical unit. The OMNI interface 209 provides a single unified interface to upper layers, while 210 underlying data link selections are performed on a per-packet 211 basis considering factors such as DSCP, flow label, application 212 policy, signal quality, cost, etc. Multilinking decisions are 213 coordinated in both the outbound (i.e. MN to correspondent) and 214 inbound (i.e., correspondent to MN) directions. 216 L2 217 The second layer in the OSI network model. Also known as "layer- 218 2", "link-layer", "sub-IP layer", "data link layer", etc. 220 L3 221 The third layer in the OSI network model. Also known as "layer- 222 3", "network-layer", "IPv6 layer", etc. 224 3. Requirements 226 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 227 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 228 "OPTIONAL" in this document are to be interpreted as described in BCP 229 14 [RFC2119][RFC8174] when, and only when, they appear in all 230 capitals, as shown here. 232 4. Overlay Multilink Network Interface (OMNI) Model 234 An OMNI interface is a MN virtual interface configured over one or 235 more ANET interfaces, which may be physical (e.g., an aeronautical 236 radio link) or virtual (e.g., an Internet or higher-layer "tunnel"). 237 The MN receives a MNP from the MS, and coordinates with the MS 238 through IPv6 ND message exchanges. The MN uses the MNP to construct 239 a unique OMNI LLA through the algorithmic derivation specified in 240 Section 7 and assigns the LLA to the OMNI interface. 242 The OMNI interface architectural layering model is the same as in 243 [RFC7847], and augmented as shown in Figure 1. The IP layer (L3) 244 therefore sees the OMNI interface as a single network layer interface 245 with multiple underlying ANET interfaces that appear as L2 246 communication channels in the architecture. 248 +----------------------------+ 249 | Upper Layer Protocol | 250 Session-to-IP +---->| | 251 Address Binding | +----------------------------+ 252 +---->| IP (L3) | 253 IP Address +---->| | 254 Binding | +----------------------------+ 255 +---->| OMNI Interface | 256 Logical-to- +---->| (OMNI LLA) | 257 Physical | +----------------------------+ 258 Interface +---->| L2 | L2 | | L2 | 259 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 260 +------+------+ +------+ 261 | L1 | L1 | | L1 | 262 | | | | | 263 +------+------+ +------+ 265 Figure 1: OMNI Interface Architectural Layering Model 267 The OMNI virtual interface model gives rise to a number of 268 opportunities: 270 o since OMNI LLAs are uniquely derived from an MNP, no Duplicate 271 Address Detection (DAD) messaging is necessary over the OMNI 272 interface. 274 o ANET interfaces do not require any L3 addresses (i.e., not even 275 link-local) in environments where communications are coordinated 276 entirely over the OMNI interface. 278 o as ANET interface properties change (e.g., link quality, cost, 279 availability, etc.), any active ANET interface can be used to 280 update the profiles of multiple additional ANET interfaces in a 281 single message. This allows for timely adaptation and service 282 continuity under dynamically changing conditions. 284 o coordinating ANET interfaces in this way allows them to be 285 represented in a unified MS profile with provisions for mobility 286 and multilink operations. 288 o exposing a single virtual interface abstraction to the IPv6 layer 289 allows for multilink operation (including QoS based link 290 selection, packet replication, load balancing, etc.) at L2 while 291 still permitting queuing at the L3 based on, e.g., DSCP, flow 292 label, etc. 294 o L3 sees the OMNI interface as a point of connection to the OMNI 295 link; if there are multiple OMNI links (i.e., multiple MS's), L3 296 will see multiple OMNI interfaces. 298 Other opportunities are discussed in [RFC7847]. 300 Figure 2 depicts the architectural model for a MN connecting to the 301 MS via multiple independent ANETs. When an ANET interface becomes 302 active, the MN sends native (i.e., unencapsulated) IPv6 ND messages 303 via the underlying ANET interface. IPv6 ND messages traverse the 304 ground domain ANETs until they reach an Access Router (AR#1, AR#2, 305 .., AR#n). The AR then coordinates with a Mobility Service Endpoint 306 (MSE#1, MSE#2, ..., MSE#m) in the INET and returns an IPv6 ND message 307 response to the MN. IPv6 ND messages traverse the ANET at layer 2; 308 hence, the Hop Limit is not decremented. 310 +--------------+ 311 | MN | 312 +--------------+ 313 |OMNI interface| 314 +----+----+----+ 315 +--------|IF#1|IF#2|IF#n|------ + 316 / +----+----+----+ \ 317 / | \ 318 / Native | IP \ 319 v v v 320 (:::)-. (:::)-. (:::)-. 321 .-(::ANET:::) .-(::ANET:::) .-(::ANET:::) 322 `-(::::)-' `-(::::)-' `-(::::)-' 323 +----+ +----+ +----+ 324 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 325 . +-|--+ +-|--+ +-|--+ . 326 . | | | 327 . v v v . 328 . <----- Encapsulation -----> . 329 . . 330 . +-----+ (:::)-. . 331 . |MSE#2| .-(::::::::) +-----+ . 332 . +-----+ .-(::: INET :::)-. |MSE#m| . 333 . (::::: Routing ::::) +-----+ . 334 . `-(::: System :::)-' . 335 . +-----+ `-(:::::::-' . 336 . |MSE#1| +-----+ +-----+ . 337 . +-----+ |MSE#3| |MSE#4| . 338 . +-----+ +-----+ . 339 . . 340 . . 341 . <----- Worldwide Connected Internetwork ----> . 342 ........................................................... 344 Figure 2: MN/MS Coordination via Multiple ANETs 346 After the initial IPv6 ND message exchange, the MN can send and 347 receive unencapsulated IPv6 data packets over the OMNI interface. 348 OMNI interface multilink services will forward the packets via ARs in 349 the correct underlying ANETs. The AR encapsulates the packets 350 according to the capabilities provided by the MS and forwards them to 351 the next hop within the worldwide connected Internetwork via optimal 352 routes. 354 5. Maximum Transmission Unit 356 All IPv6 interfaces MUST configure an MTU of at least 1280 bytes 357 [RFC8200]. The OMNI interface configures its MTU based on the 358 largest MTU among all underlying ANET interfaces. The value MAY be 359 overridden if an RA message with an MTU option is received. 361 The OMNI interface returns internally-generated IPv6 Path MTU 362 Discovery (PMTUD) Packet Too Big (PTB) messages [RFC8201] for packets 363 admitted into the OMNI interface that are too large for the outbound 364 underlying ANET interface. Similarly, the OMNI interface performs 365 PMTUD even if the destination appears to be on the same link since a 366 proxy on the path could return a PTB message. PMTUD therefore 367 ensures that the OMNI interface MTU is adaptive and reflects the 368 current path used for a given data flow. 370 Applications that cannot tolerate loss due to MTU restrictions SHOULD 371 refrain from sending packets larger than 1280 bytes, since dynamic 372 path changes can reduce the path MTU at any time. Applications that 373 may benefit from sending larger packets even though the path MTU may 374 change dynamically MAY use larger sizes. 376 6. Frame Format 378 The OMNI interface transmits IPv6 packets according to the native 379 frame format of each underlying ANET interface. For example, for 380 Ethernet-compatible interfaces the frame format is specified in 381 [RFC2464], for aeronautical radio interfaces the frame format is 382 specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical 383 Manual), for tunnels over IPv6 the frame format is specified in 384 [RFC2473], etc. 386 7. Link-Local Addresses 388 OMNI interfaces assign link-local addresses (LLAs) the same as any 389 IPv6 interface. The link-local address format for OMNI interfaces is 390 known as the "OMNI LLA". 392 MN OMNI LLAs encode the most-significant 64 bits of a MNP into the 393 least-significant 64 bits of the prefix fe80::/64. For example, for 394 the MNP 2001:db8:1000:2000::/56 the corresponding OMNI LLA is 395 fe80::2001:db8:1000:2000. (See Appendix B for considerations for 396 MNPs longer than /64.) 398 MSE OMNI LLAs are allocated from the range fe80::/96, and MUST be 399 managed for uniqueness by the collective OMNI link administrative 400 authorities. The lower 32 bits of the LLA includes a unique integer 401 value between 1 and ffff:fffe, e.g., as in fe80::1, fe80::2, fe80::3, 402 etc. The address fe80:: is the IPv6 link-local Subnet Router Anycast 403 address [RFC4291] and the address fe80::ffff:ffff is reserved; hence, 404 these values are not available for general assignment. (Note that 405 the IPv6 addressing architecture [RFC4291] reserves the prefix ::/8; 406 this assures that MNPs will not begin with ::/32 so that MN and MSE 407 OMNI LLAs cannot overlap.) 409 IPv4-compatible OMNI LLAs are allocated as fe80::ffff:[v4addr], i.e., 410 fe80::/10, followed by 70 '0' bits, followed by 16 '1' bits, followed 411 by a 32bit IPv4 address. For example, the IPv4-Compatible OMNI LLA 412 for 192.0.2.1 is fe80::ffff:192.0.2.1. 414 Since MN OMNI LLAs are based on the distribution of administratively 415 assured unique MNPs, and since MSE OMNI LLAs are guaranteed unique 416 through administrative assignment, OMNI interfaces set the 417 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 419 8. Address Mapping - Unicast 421 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 422 state and use the link-local address format specified in Section 7. 423 IPv6 Neighbor Discovery (ND) [RFC4861] messages on OMNI interfaces 424 observe the native Source/Target Link-Layer Address Option (S/TLLAO) 425 formats of the underlying ANET interfaces (e.g., for Ethernet the S/ 426 TLLAO is specified in [RFC2464]). 428 MNs such as aircraft typically have many wireless data link types 429 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 430 etc.) with diverse performance, cost and availability properties. 431 The OMNI interface would therefore appear to have multiple L2 432 connections, and may include information for multiple ANET interfaces 433 in a single message exchange. 435 OMNI interfaces use an IPv6 ND option called the "OMNI option". MNs 436 invoke the MS by including an OMNI "Request" option in Router 437 Solicitation (RS) and (unsolicited) Neighbor Advertisement (NA) 438 messages, and the MS includes an OMNI "Response" option in unicast 439 Router Advertisement (RA) responses to an RS. 441 RS/NA messages sent by the MN include OMNI options formatted as shown 442 in Figure 3: 444 0 1 2 3 445 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 1 446 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 447 | Type | Length | Prefix Length |S|R| Reserved | 448 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 449 | ifIndex[1] | ifType[1] | Reserved [1] |Link[1]|QoS[1] | 450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 451 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 453 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 459 | ifIndex[2] | ifType[2] | Reserved [2] |Link[2]|QoS[2] | 460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 461 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 463 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 467 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 469 ... ... ... 470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 471 | ifIndex[N] | ifType[N] | Reserved [N] |Link[N]|QoS[N] | 472 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 473 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 474 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 475 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 478 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 481 | zero-padding | 482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 484 Figure 3: OMNI Option Format in RS/NA Messages 486 In this format: 488 o Type is set to TBD. 490 o Length is set to the number of 8 octet blocks in the option (with 491 zero-padding added to the end of the option if necessary to 492 produce an integral number of 8 octet blocks). 494 o Prefix Length is set to the length of the MNP embedded in the MN's 495 OMNI LLA. 497 o S (the "Sub-type" bit) is set to '1' to signify "Request". 499 o R (the "Register" bit) is set to '1' to assert the MNP 500 registration or set to '0' to request de-registration. 502 o Reserved is set to the value '0' on transmission and ignored on 503 reception. 505 o A set of N ANET interface "ifIndex-tuples" are included as 506 follows: 508 * ifIndex[i] is set to an 8-bit integer value corresponding to a 509 specific underlying ANET interface. The first ifIndex-tuple 510 MUST correspond to the ANET interface over which the message is 511 sent. Once the MN has assigned an ifIndex to an ANET 512 interface, the assignment MUST remain unchanged while the MN 513 remains registered in the network. MNs MUST number each 514 ifIndex with a value between '1' and '255' that represents a 515 MN-specific 8-bit mapping for the actual ifIndex value assigned 516 to the ANET interface by network management [RFC2863]. 518 * ifType[i] is set to an 8-bit integer value corresponding to the 519 underlying ANET interface identified by ifIndex. The value 520 represents an OMNI interface-specific 8-bit mapping for the 521 actual IANA ifType value registered in the 'IANAifType-MIB' 522 registry [http://www.iana.org]. 524 * Reserved[i] is set to the value '0' on transmission and ignored 525 on reception. 527 * Link[i] encodes a 4-bit link metric. The value '0' means the 528 link is DOWN, and the remaining values mean the link is UP with 529 metric ranging from '1' ("low") to '15' ("high"). 531 * QoS[i] encodes the number of 4-byte blocks (between '0' and 532 '15') of two-bit P[i] values that follow. The first 4 blocks 533 correspond to the 64 Differentiated Service Code Point (DSCP) 534 values P00 - P63 [RFC2474]. If additional 4-byte P[i] blocks 535 follow, their values correspond to "pseudo-DSCP" values P64, 536 P65, P66, etc. numbered consecutively. The pseudo-DSCP values 537 correspond to ancillary QoS information defined for the 538 specific OMNI interface (e.g., see Appendix A). 540 * P[*] includes zero or more per-ifIndex 4-byte blocks of two-bit 541 Preferences. Each P[*] field is set to the value '0' 542 ("disabled"), '1' ("low"), '2' ("medium") or '3' ("high") to 543 indicate a QoS preference level for ANET interface selection 544 purposes. The first four blocks always correspond to the 64 545 DSCP values. If one or more of the blocks are absent (e.g., 546 for QoS values 0,1,2,3) the P[*] values for the missing blocks 547 default to "medium". 549 Unicast RA messages sent by the MS in response to MN RS messages 550 include OMNI options formatted as shown in Figure 4: 552 0 1 2 3 553 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 1 554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 555 | Type | Length = 1 | Prefix Length |S|R| Reserved | 556 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 557 | ifIndex | ifType | Flags | Link | QoS | 558 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 560 Figure 4: OMNI Option Format in RA messages 562 In this format: 564 o Type is set to TBD. 566 o Length is set to the constant value '1' (i.e., 1 unit of 8 567 octets). 569 o Prefix Length is set to the length associated with the OMNI LLA of 570 the destination MN. 572 o S is set to '0' to signify "Response". 574 o R is set to '1' to confirm registration or set to '0' to release/ 575 decline registration. 577 o Reserved is set to the value '0' on transmission and ignored on 578 reception. 580 o ifIndex, ifType, Flags, Link and QoS echo the values of the same 581 fields that were received in the first ifIndex-tuple of the 582 soliciting request. The echoed values provide a nonce that allows 583 the MN to associate the Response with the original Request. 585 9. Address Mapping - Multicast 587 The multicast address mapping of the native underlying ANET interface 588 applies. The mobile router on board the aircraft also serves as an 589 IGMP/MLD Proxy for its EUNs and/or hosted applications per [RFC4605] 590 while using the L2 address of the router as the L2 address for all 591 multicast packets. 593 10. Address Mapping for IPv6 Neighbor Discovery Messages 595 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 596 unicast link-scoped IPv6 destination address. However, IPv6 ND 597 messaging is coordinated between the MN and MS only without invoking 598 other nodes on the ANET. 600 For this reason, ANET links maintain unicast L2 addresses ("MSADDR") 601 for the purpose of supporting MN/MS IPv6 ND messaging. For Ethernet- 602 compatible ANETs, this specification reserves one Ethernet unicast 603 address TBD2. For non-Ethernet statically-addressed ANETs, MSADDR is 604 reserved per the assigned numbers authority for the ANET addressing 605 space. For still other ANETs, MSADDR may be dynamically discovered 606 through other means, e.g., L2 beacons. 608 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 609 both multicast and unicast) to an MSADDR instead of to an ordinary 610 unicast or multicast L2 address. In this way, all of the MN's IPv6 611 ND messages will be received by MS devices that are configured to 612 accept packets destined to MSADDR. Note that multiple MS devices on 613 the link could be configured to accept packets destined to MSADDR, 614 e.g., as a basis for supporting redundancy. 616 Therefore, ARs MUST accept and process packets destined to MSADDR, 617 while all other devices MUST NOT process packets destined to MSADDR. 618 This model has well-established operational experience in Proxy 619 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 621 11. Conceptual Sending Algorithm 623 The MN's IPv6 layer selects the outbound OMNI interface according to 624 standard IPv6 requirements. The OMNI interface maintains default 625 routes and neighbor cache entries for MSEs, and may also include 626 additional neighbor cache entries created through other means (e.g., 627 Address Resolution, static configuration, etc.). 629 After a packet enters the OMNI interface, an outbound ANET interface 630 is selected based on multilink parameters such as DSCP, application 631 port number, cost, performance, message size, etc. OMNI interface 632 multilink selections could also be configured to perform replication 633 across multiple ANET interfaces for increased reliability at the 634 expense of packet duplication. 636 OMNI interface multilink service designers MUST observe the BCP 637 guidance in Section 15 [RFC3819] in terms of implications for 638 reordering when packets from the same flow may be spread across 639 multiple ANET interfaces having diverse properties. 641 11.1. Multiple Aero Interfaces 643 MNs may associate with multiple MS instances concurrently. Each MS 644 instance represents a distinct OMNI link distinguished by its 645 associated MSPs. The MN configures a separate OMNI interface for 646 each link so that multiple interfaces (e.g., omni0, omni1, omni2, 647 etc.) are exposed to the IPv6 layer. 649 Depending on local policy and configuration, an MN may choose between 650 alternative active OMNI interfaces using a packet's DSCP, routing 651 information or static configuration. Interface selection based on 652 per-packet source addresses is also enabled when the MSPs for each 653 OMNI interface are known (e.g., discovered through Prefix Information 654 Options (PIOs) and/or Route Information Options (RIOs)). 656 Each OMNI interface can be configured over the same or different sets 657 of ANET interfaces. Each ANET distinguishes between the different 658 OMNI links based on the MSPs represented in per-packet IPv6 659 addresses. 661 Multiple distinct OMNI links can therefore be used to support fault 662 tolerance, load balancing, reliability, etc. The architectural model 663 parallels Layer 2 Virtual Local Area Networks (VLANs), where the MSPs 664 serve as (virtual) VLAN tags. 666 12. Router Discovery and Prefix Registration 668 ARs process IPv6 ND messages destined to all-routers multicast 669 (ff02::2), the subnet router anycast LLA (fe80::) and unicast IPv6 670 LLAs. ARs configure the L2 address MSADDR (see: Section 10) and act 671 as a proxy for MSE OMNI LLAs in the range fe80::1 through 672 fe80::ffff:fffe. 674 MNs interface with the MS by sending RS messages with OMNI options. 675 For each ANET interface, the MN sends RS messages with OMNI options 676 with L2 destination address set to MSADDR and with L3 destination 677 address set to either a specific MSE OMNI LLA, subnet router anycast 678 LLA, or all-routers multicast. The MN discovers MSE OMNI LLAs either 679 through an RA message response to an initial anycast/multicast RS or 680 before sending an initial RS message. [RFC5214] provides example MSE 681 address discovery methods, including information conveyed during data 682 link login, name service lookups, static configuration, etc. 684 The AR receives the RS messages and coordinates with the 685 corresponding MSE in a manner outside the scope of this document. 686 The AR returns an RA message with source address set to the MSE OMNI 687 LLA, with an OMNI option and with any information for the link that 688 would normally be delivered in a solicited RA message. (Note that if 689 all MSEs share common state, the AR can instead return an RA with 690 source address set to the subnet router anycast LLA.) 692 MNs configure OMNI interfaces that observe the properties discussed 693 in the previous section. The OMNI interface and its underlying 694 interfaces are said to be in either the "UP" or "DOWN" state 695 according to administrative actions in conjunction with the interface 696 connectivity status. An OMNI interface transitions to UP or DOWN 697 through administrative action and/or through state transitions of the 698 underlying interfaces. When a first underlying interface transitions 699 to UP, the OMNI interface also transitions to UP. When all 700 underlying interfaces transition to DOWN, the OMNI interface also 701 transitions to DOWN. 703 When an OMNI interface transitions to UP, the MN sends initial RS 704 messages to register its MNP and an initial set of underlying ANET 705 interfaces that are also UP. The MN sends additional RS messages to 706 refresh lifetimes and to register/deregister underlying ANET 707 interfaces as they transition to UP or DOWN. 709 ARs return RA messages with configuration information in response to 710 a MN's RS messages. The RAs include a Router Lifetime value and any 711 necessary options, such as: 713 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 715 o RIOs [RFC4191] with more-specific routes. 717 o an MTU option that specifies the maximum acceptable packet size 718 for the OMNI link 720 The AR sends immediate unicast RA responses without delay; therefore, 721 the IPv6 ND MAX_RA_DELAY_TIME and MIN_DELAY_BETWEEN_RAS constants for 722 multicast RAs do not apply. The AR MAY send periodic and/or event- 723 driven unsolicited RA messages, but is not required to do so for 724 unicast advertisements [RFC4861]. 726 The MN sends RS messages from within the OMNI interface while using 727 an UP underlying ANET interface as the outbound interface. Each RS 728 message is formatted as though it originated from the IPv6 layer, but 729 the process is coordinated wholly from within the OMNI interface and 730 is therefore opaque to the IPv6 layer. The MN sends initial RS 731 messages over an UP underlying interface with its OMNI LLA as the 732 source. The RS messages include OMNI options with a valid Prefix 733 Length as well as ifIndex-tuples appropriate for underlying ANET 734 interfaces. The AR processes RS message and conveys the OMNI option 735 information to the MSE. 737 When the MSE processes the AR information, if the prefix registration 738 was accepted the MSE injects the MNP into the routing/mapping system 739 then caches the new Prefix Length, MNP and ifIndex-tuples. The MSE 740 then directs the AR to return an RA message to the MN with an OMNI 741 option with a non-zero Router Lifetime if the prefix assertion was 742 acceptable; otherwise, with a zero Router Lifetime. 744 When the MN receives the RA message, it creates a default route with 745 L3 next hop address set to the address found in the RA source address 746 and with L2 address set to MSADDR. The AR will then forward packets 747 between the MN and the MS. 749 The MN then manages its underlying ANET interfaces according to their 750 states as follows: 752 o When an underlying ANET interface transitions to UP, the MN sends 753 an RS over the ANET interface with an OMNI option. The OMNI 754 option contains a first ifIndex-tuple with values specific to this 755 ANET interface, and may contain additional ifIndex-tuples specific 756 to other ANET interfaces. 758 o When an underlying ANET interface transitions to DOWN, the MN 759 sends an RS or unsolicited NA message over any UP ANET interface 760 with an OMNI option containing an ifIndex-tuple for the DOWN ANET 761 interface with Link(i) set to '0'. The MN sends an RS when an 762 acknowledgement is required, or an unsolicited NA when reliability 763 is not thought to be a concern (e.g., if redundant transmissions 764 are sent on multiple ANET interfaces). 766 o When a MN wishes to release from a current MSE, it sends an RS or 767 unsolicited NA message over any UP ANET interfaces with an OMNI 768 option with R set to 0. The corresponding MSE then withdraws the 769 MNP from the routing/mapping system and (for RS responses) returns 770 an RA message with an OMNI option with Router Lifetime set to 0. 772 o When all of a MNs underlying interfaces have transitioned to DOWN, 773 the MSE withdraws the MNP the same as if it had received a message 774 with an OMNI option with R set to 0. 776 The MN is responsible for retrying each RS exchange up to 777 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 778 seconds until an RA is received. If no RA is received over multiple 779 UP ANET interfaces, the MN declares this MSE unreachable and tries a 780 different MSE. 782 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 783 Therefore, when the IPv6 layer sends an RS message the OMNI interface 784 returns an internally-generated RA message as though the message 785 originated from an IPv6 router. The internally-generated RA message 786 contains configuration information (such as Router Lifetime, MTU, 787 etc.) that is consistent with the information received from the RAs 788 generated by the MS. 790 Whether the OMNI interface IPv6 ND messaging process is initiated 791 from the receipt of an RS message from the IPv6 layer is an 792 implementation matter. Some implementations may elect to defer the 793 IPv6 ND messaging process until an RS is received from the IPv6 794 layer, while others may elect to initiate the process independently 795 of any IPv6 layer messaging. 797 13. AR and MSE Resilience 799 ANETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 800 [RFC5798] configurations so that service continuity is maintained 801 even if one or more ARs fail. Using VRRP, the MN is unaware which of 802 the (redundant) ARs is currently providing service, and any service 803 discontinuity will be limited to the failover time supported by VRRP. 804 Widely deployed public domain implementation of VRRP are available. 806 MSEs SHOULD use high availability clustering services so that 807 multiple redundant systems can provide coordinated response to 808 failures. As with VRRP, widely deployed public domain 809 implementations of high availability clustering services are 810 available. Note that special-purpose and expensive dedicated 811 hardware is not necessary, and public domain implementations can be 812 used even between lightweight virtual machines in cloud deployments. 814 14. Detecting and Responding to MSE Failures 816 In environments where fast recovery from MSE failure is required, ARs 817 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 818 manner that parallels Bidirectional Forwarding Detection (BFD) 819 [RFC5880] to track MSE reachability. ARs can then quickly detect and 820 react to failures so that cached information is re-established 821 through alternate paths. Proactive NUD control messaging is carried 822 only over well-connected ground domain networks (i.e., and not low- 823 end aeronautical radio links) and can therefore be tuned for rapid 824 response. 826 ARs employ proactive NUD with MSEs for which there are currently 827 active ANET MNs. If an MSE fails, ARs can quickly inform MNs of the 828 outage by sending RA messages on the ANET interface. The AR sends RA 829 messages to the MN via the ANET interface with source address set to 830 the MSEs OMNI LLA, destination address set to all-nodes multicast, 831 and Router Lifetime set to 0. 833 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 834 by small delays [RFC4861]. Any MNs on the ANET interface that have 835 been using the (now defunct) MSE will receive the RA messages and 836 associate with a new MSE. 838 15. IANA Considerations 840 The IANA is instructed to allocate an official Type number TBD from 841 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 842 option. Implementations set Type to 253 as an interim value 843 [RFC4727]. 845 The IANA is instructed to allocate one Ethernet unicast address TBD2 846 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 847 Address Block - Unicast Use". 849 16. Security Considerations 851 Security considerations are the same as defined for the specific 852 access network interface types, and readers are referred to the 853 appropriate interface specifications. 855 IPv6 and IPv6 ND security considerations also apply. 857 17. Acknowledgements 859 The first version of this document was prepared per the consensus 860 decision at the 7th Conference of the International Civil Aviation 861 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 862 2019. Consensus to take the document forward to the IETF was reached 863 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 864 Attendees and contributors included: Guray Acar, Danny Bharj, 865 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 866 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 867 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 868 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 869 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 870 Fryderyk Wrobel and Dongsong Zeng. 872 The following individuals are acknowledged for their useful comments: 873 Pavel Drasil, Zdenek Jaron, Michael Matyas, Madhu Niraula, Greg 874 Saccone, Stephane Tamalet, Eric Vyncke. Naming of the IPv6 ND option 875 was discussed on the 6man mailing list. 877 This work is aligned with the NASA Safe Autonomous Systems Operation 878 (SASO) program under NASA contract number NNA16BD84C. 880 This work is aligned with the FAA as per the SE2025 contract number 881 DTFAWA-15-D-00030. 883 18. References 885 18.1. Normative References 887 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 888 Requirement Levels", BCP 14, RFC 2119, 889 DOI 10.17487/RFC2119, March 1997, 890 . 892 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 893 "Definition of the Differentiated Services Field (DS 894 Field) in the IPv4 and IPv6 Headers", RFC 2474, 895 DOI 10.17487/RFC2474, December 1998, 896 . 898 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 899 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 900 November 2005, . 902 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 903 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 904 2006, . 906 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 907 ICMPv6, UDP, and TCP Headers", RFC 4727, 908 DOI 10.17487/RFC4727, November 2006, 909 . 911 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 912 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 913 DOI 10.17487/RFC4861, September 2007, 914 . 916 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 917 Address Autoconfiguration", RFC 4862, 918 DOI 10.17487/RFC4862, September 2007, 919 . 921 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 922 Hosts in a Multi-Prefix Network", RFC 8028, 923 DOI 10.17487/RFC8028, November 2016, 924 . 926 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 927 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 928 May 2017, . 930 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 931 (IPv6) Specification", STD 86, RFC 8200, 932 DOI 10.17487/RFC8200, July 2017, 933 . 935 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 936 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 937 DOI 10.17487/RFC8201, July 2017, 938 . 940 18.2. Informative References 942 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 943 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 944 . 946 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 947 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 948 . 950 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 951 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 952 December 1998, . 954 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 955 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 956 . 958 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 959 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 960 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 961 RFC 3819, DOI 10.17487/RFC3819, July 2004, 962 . 964 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 965 "Internet Group Management Protocol (IGMP) / Multicast 966 Listener Discovery (MLD)-Based Multicast Forwarding 967 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 968 August 2006, . 970 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 971 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 972 RFC 5213, DOI 10.17487/RFC5213, August 2008, 973 . 975 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 976 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 977 DOI 10.17487/RFC5214, March 2008, 978 . 980 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 981 Version 3 for IPv4 and IPv6", RFC 5798, 982 DOI 10.17487/RFC5798, March 2010, 983 . 985 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 986 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 987 . 989 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 990 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 991 2012, . 993 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 994 Requirements for IPv6 Customer Edge Routers", RFC 7084, 995 DOI 10.17487/RFC7084, November 2013, 996 . 998 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 999 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1000 Boundary in IPv6 Addressing", RFC 7421, 1001 DOI 10.17487/RFC7421, January 2015, 1002 . 1004 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 1005 Support for IP Hosts with Multi-Access Support", RFC 7847, 1006 DOI 10.17487/RFC7847, May 2016, 1007 . 1009 Appendix A. OMNI Option Extensions for Pseudo-DSCP Mappings 1011 Adaptation of the OMNI interface to specific Internetworks such as 1012 the Aeronautical Telecommunications Network with Internet Protocol 1013 Services (ATN/IPS) includes link selection preferences based on 1014 transport port numbers in addition to the existing DSCP-based 1015 preferences. ATN/IPS nodes maintain a map of transport port numbers 1016 to additional "pseudo-DSCP" P[i] preference fields beyond the first 1017 64. For example, TCP port 22 maps to pseudo-DSCP value P67, TCP port 1018 443 maps to P70, UDP port 8060 maps to P76, etc. Figure 5 shows an 1019 example OMNI option with extended P[i] values beyond the base 64 used 1020 for DSCP mapping (i.e., for QoS values 5 or greater): 1022 0 1 2 3 1023 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 1024 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1025 | Type | Length | Prefix Length |R| Reserved | 1026 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1027 | ifIndex | ifType | Flags | Link |QoS=5+ | 1028 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1029 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 1030 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1031 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 1032 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1033 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 1034 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1035 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1036 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1037 |P64|P65|P66|P67|P68|P69|P70|P71|P72|P73|P74|P75|P76|P77|P78|P79| 1038 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1039 ... 1041 Figure 5: ATN/IPS Extended OMNI Option Format 1043 Appendix B. Prefix Length Considerations 1045 The 64-bit boundary in IPv6 addresses [RFC7421] determines the MN 1046 OMNI LLA format for encoding the most-significant 64 MNP bits into 1047 the least-significant 64 bits of the prefix fe80::/64 as discussed in 1048 Section 7. 1050 [RFC4291] defines the link-local address format as fe80::/10, 1051 followed by 54 unused bits, followed by the least-significant 64 bits 1052 of the address. If the 64-bit boundary is relaxed through future 1053 standards activity, then the 54 unused bits can be employed for 1054 extended coding of MNPs of length /65 up to /118. 1056 The extended coding format would continue to encode MNP bits 0-63 in 1057 bits 64-127 of the OMNI LLA, while including MNP bits 64-117 in bits 1058 10-63. For example, the OMNI LLA corresponding to the MNP 1059 2001:db8:1111:2222:3333:4444:5555::/112 would be 1060 fe8c:ccd1:1115:5540:2001:db8:1111:2222, and would still be a valid 1061 IPv6 LLA per [RFC4291]. 1063 Appendix C. VDL Mode 2 Considerations 1065 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 1066 (VDLM2) that specifies an essential radio frequency data link service 1067 for aircraft and ground stations in worldwide civil aviation air 1068 traffic management. The VDLM2 link type is "multicast capable" 1069 [RFC4861], but with considerable differences from common multicast 1070 links such as Ethernet and IEEE 802.11. 1072 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 1073 magnitude less than most modern wireless networking gear. Second, 1074 due to the low available link bandwidth only VDLM2 ground stations 1075 (i.e., and not aircraft) are permitted to send broadcasts, and even 1076 so only as compact layer 2 "beacons". Third, aircraft employ the 1077 services of ground stations by performing unicast RS/RA exchanges 1078 upon receipt of beacons instead of listening for multicast RA 1079 messages and/or sending multicast RS messages. 1081 This beacon-oriented unicast RS/RA approach is necessary to conserve 1082 the already-scarce available link bandwidth. Moreover, since the 1083 numbers of beaconing ground stations operating within a given spatial 1084 range must be kept as sparse as possible, it would not be feasible to 1085 have different classes of ground stations within the same region 1086 observing different protocols. It is therefore highly desirable that 1087 all ground stations observe a common language of RS/RA as specified 1088 in this document. 1090 Note that links of this nature may benefit from compression 1091 techniques that reduce the bandwidth necessary for conveying the same 1092 amount of data. The IETF lpwan working group is considering possible 1093 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 1095 Appendix D. Change Log 1097 << RFC Editor - remove prior to publication >> 1099 Differences from draft-templin-atn-aero-interface-10 to draft- 1100 templin-atn-aero-interface-11: 1102 o Changed name from "aero" to "OMNI" 1104 o Resolved AD review comments from Eric Vyncke (posted to atn list) 1106 Differences from draft-templin-atn-aero-interface-09 to draft- 1107 templin-atn-aero-interface-10: 1109 o Renamed ARO option to AERO option 1110 o Re-worked Section 13 text to discuss proactive NUD. 1112 Differences from draft-templin-atn-aero-interface-08 to draft- 1113 templin-atn-aero-interface-09: 1115 o Version and reference update 1117 Differences from draft-templin-atn-aero-interface-07 to draft- 1118 templin-atn-aero-interface-08: 1120 o Removed "Classic" and "MS-enabled" link model discussion 1122 o Added new figure for MN/AR/MSE model. 1124 o New Section on "Detecting and responding to MSE failure". 1126 Differences from draft-templin-atn-aero-interface-06 to draft- 1127 templin-atn-aero-interface-07: 1129 o Removed "nonce" field from AR option format. Applications that 1130 require a nonce can include a standard nonce option if they want 1131 to. 1133 o Various editorial cleanups. 1135 Differences from draft-templin-atn-aero-interface-05 to draft- 1136 templin-atn-aero-interface-06: 1138 o New Appendix C on "VDL Mode 2 Considerations" 1140 o New Appendix D on "RS/RA Messaging as a Single Standard API" 1142 o Various significant updates in Section 5, 10 and 12. 1144 Differences from draft-templin-atn-aero-interface-04 to draft- 1145 templin-atn-aero-interface-05: 1147 o Introduced RFC6543 precedent for focusing IPv6 ND messaging to a 1148 reserved unicast link-layer address 1150 o Introduced new IPv6 ND option for Aero Registration 1152 o Specification of MN-to-MSE message exchanges via the ANET access 1153 router as a proxy 1155 o IANA Considerations updated to include registration requests and 1156 set interim RFC4727 option type value. 1158 Differences from draft-templin-atn-aero-interface-03 to draft- 1159 templin-atn-aero-interface-04: 1161 o Removed MNP from aero option format - we already have RIOs and 1162 PIOs, and so do not need another option type to include a Prefix. 1164 o Clarified that the RA message response must include an aero option 1165 to indicate to the MN that the ANET provides a MS. 1167 o MTU interactions with link adaptation clarified. 1169 Differences from draft-templin-atn-aero-interface-02 to draft- 1170 templin-atn-aero-interface-03: 1172 o Sections re-arranged to match RFC4861 structure. 1174 o Multiple aero interfaces 1176 o Conceptual sending algorithm 1178 Differences from draft-templin-atn-aero-interface-01 to draft- 1179 templin-atn-aero-interface-02: 1181 o Removed discussion of encapsulation (out of scope) 1183 o Simplified MTU section 1185 o Changed to use a new IPv6 ND option (the "aero option") instead of 1186 S/TLLAO 1188 o Explained the nature of the interaction between the mobility 1189 management service and the air interface 1191 Differences from draft-templin-atn-aero-interface-00 to draft- 1192 templin-atn-aero-interface-01: 1194 o Updates based on list review comments on IETF 'atn' list from 1195 4/29/2019 through 5/7/2019 (issue tracker established) 1197 o added list of opportunities afforded by the single virtual link 1198 model 1200 o added discussion of encapsulation considerations to Section 6 1202 o noted that DupAddrDetectTransmits is set to 0 1204 o removed discussion of IPv6 ND options for prefix assertions. The 1205 aero address already includes the MNP, and there are many good 1206 reasons for it to continue to do so. Therefore, also including 1207 the MNP in an IPv6 ND option would be redundant. 1209 o Significant re-work of "Router Discovery" section. 1211 o New Appendix B on Prefix Length considerations 1213 First draft version (draft-templin-atn-aero-interface-00): 1215 o Draft based on consensus decision of ICAO Working Group I Mobility 1216 Subgroup March 22, 2019. 1218 Authors' Addresses 1220 Fred L. Templin (editor) 1221 The Boeing Company 1222 P.O. Box 3707 1223 Seattle, WA 98124 1224 USA 1226 Email: fltemplin@acm.org 1228 Tony Whyman 1229 MWA Ltd c/o Inmarsat Global Ltd 1230 99 City Road 1231 London EC1Y 1AX 1232 England 1234 Email: tony.whyman@mccallumwhyman.com