idnits 2.17.1 draft-templin-atn-aero-interface-12.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 22, 2020) is 1548 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 444 -- Looks like a reference, but probably isn't: '2' on line 454 == Missing Reference: 'N' is mentioned on line 466, but not defined == Unused Reference: 'RFC2225' is defined on line 927, 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 25, 2020 MWA Ltd c/o Inmarsat Global Ltd 6 January 22, 2020 8 Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) 9 Interfaces 10 draft-templin-atn-aero-interface-12 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 July 25, 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 . . . . . . . . . . . . . . . . . 13 66 10. Address Mapping for IPv6 Neighbor Discovery Messages . . . . 13 67 11. Conceptual Sending Algorithm . . . . . . . . . . . . . . . . 14 68 11.1. Multiple OMNI Interfaces . . . . . . . . . . . . . . . . 14 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 . . . . . . . . . . . . . . . . . . . . . 18 73 16. Security Considerations . . . . . . . . . . . . . . . . . . . 19 74 17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 75 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 76 18.1. Normative References . . . . . . . . . . . . . . . . . . 19 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 . . . . . . . . . . . . . 23 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, mobile enterprise devices, 88 etc.) often have multiple data links for communicating with networked 89 correspondents. These data links may have diverse performance, cost 90 and availability characteristics that can change dynamically 91 according to mobility patterns, flight phases, proximity to 92 infrastructure, etc. MNs coordinate their data links in a discipline 93 known as "multilink", in which a single virtual interface is 94 configured over the underlying 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) for numbering End User 108 Networks (EUNs) 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 EUNs. The 112 router discovery process is iterated over each of the OMNI 113 interface's underlying access network data links in order to register 114 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 an 146 EUN, and its data link connection parameters can change over time 147 due to, e.g., node mobility, link quality, etc. The term MN used 148 here is distinct from uses in other documents, and does not imply 149 a particular mobility protocol. 151 End User Network (EUN) 152 a simple or complex mobile network that travels with the MN as a 153 single logical unit. The IPv6 addresses assigned to EUN devices 154 remain stable even if the MN's data link connections change. 156 Mobility Service (MS) 157 a mobile routing service that tracks MN movements and ensures that 158 MNs remain continuously reachable even across mobility events. 159 Specific MS details are out of scope for this document. 161 Mobility Service Prefix (MSP) 162 an aggregated IPv6 prefix (e.g., 2001:db8::/32) advertised to the 163 rest of the Internetwork by the MS, and from which more-specific 164 Mobile Network Prefixes (MNPs) are derived. 166 Mobile Network Prefix (MNP) 167 a longer IPv6 prefix taken from the MSP (e.g., 168 2001:db8:1000:2000::/56) and assigned to a MN. MNs sub-delegate 169 the MNP to devices located in EUNs. 171 Access Network (ANET) 172 a data link service network (e.g., an aviation radio access 173 network, satellite service provider network, cellular operator 174 network, etc.) that provides an Access Router (AR) for connecting 175 MNs to correspondents in outside Internetworks. Physical and/or 176 data link level security between the MN and AR are assumed. 178 ANET interface 179 a MN's attachment to a link in an ANET. 181 Internetwork (INET) 182 a connected network region with a coherent IP addressing plan that 183 provides transit forwarding services for ANET MNs and INET 184 correspondents. Examples include private enterprise networks, 185 ground domain aviation service networks and the global public 186 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 IPv6 Link-Local Addresses (LLAs) using the 389 following constructs: 391 o MN OMNI LLAs encode the most-significant 64 bits of a MNP within 392 the least-significant 64 bits (i.e., the interface ID) of a Link- 393 Local IPv6 Unicast Address (see: [RFC4291], Section 2.5.6). For 394 example, for the MNP 2001:db8:1000:2000::/56 the corresponding LLA 395 is fe80::2001:db8:1000:2000. 397 o MSE OMNI LLAs are allocated from the range fe80::/96, and MUST be 398 managed for uniqueness by the collective OMNI link administrative 399 authorities. The lower 32 bits of the LLA includes a unique 400 integer value between '1' and 'fffffffe', e.g., as in fe80::1, 401 fe80::2, fe80::3, etc., fe80::ffff:fffe. The address fe80:: is 402 the IPv6 link-local Subnet Router Anycast address [RFC4291] and 403 the address fe80::ffff:ffff is reserved. 405 o IPv4-compatible MN OMNI LLAs are allocated as fe80::ffff:[v4addr], 406 i.e., fe80::/10, followed by 70 '0' bits, followed by 16 '1' bits, 407 followed by a 32bit IPv4 address. For example, the 408 IPv4-Compatible MN OMNI LLA for 192.0.2.1 is fe80::ffff:192.0.2.1 409 (also written as fe80::ffff:c000:0201). 411 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 412 MNPs can be allocated from that block ensuring that there is no 413 possibility for overlap between the different OMNI LLA constructs. 415 Since MN OMNI LLAs are based on the distribution of administratively 416 assured unique MNPs, and since MSE OMNI LLAs are guaranteed unique 417 through administrative assignment, OMNI interfaces set the 418 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 420 8. Address Mapping - Unicast 422 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 423 state and use the link-local address format specified in Section 7. 424 IPv6 Neighbor Discovery (ND) [RFC4861] messages on MN OMNI interfaces 425 observe the native Source/Target Link-Layer Address Option (S/TLLAO) 426 formats of the underlying ANET interfaces (e.g., for Ethernet the S/ 427 TLLAO is specified in [RFC2464]). 429 MNs such as aircraft typically have many wireless data link types 430 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 431 etc.) with diverse performance, cost and availability properties. 432 The OMNI interface would therefore appear to have multiple L2 433 connections, and may include information for multiple ANET interfaces 434 in a single IPv6 ND message exchange. 436 OMNI interfaces use an IPv6 ND option called the "OMNI option" 437 formatted as shown in Figure 3: 439 0 1 2 3 440 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 1 441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 442 | Type | Length | Prefix Length |R| Reserved | 443 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 444 | ifIndex[1] | ifType[1] | Reserved [1] |Link[1]|QoS[1] | 445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 446 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 447 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 448 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 449 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 450 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 451 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 452 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 | ifIndex[2] | ifType[2] | Reserved [2] |Link[2]|QoS[2] | 455 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 456 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 457 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 458 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 459 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 460 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 461 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 462 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 463 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 464 ... ... ... 465 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 466 | ifIndex[N] | ifType[N] | Reserved [N] |Link[N]|QoS[N] | 467 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 468 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 469 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 470 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 471 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 472 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 474 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 476 | Notify-MSE | 477 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 478 | zero-padding (if necessary) | 479 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 481 Figure 3: OMNI Option Format 483 In this format: 485 o Type is set to TBD. 487 o Length is set to the number of 8 octet blocks in the option. 489 o Prefix Length is set according to the IPv6 source LLA type. For 490 MN OMNI LLAs, the value is set to the length of the embedded MNP. 491 For MSE OMNI LLAs, the value is set to 128. 493 o R (the "Register" bit) is set to '1' to assert MNP registration or 494 set to '0' to cancel MNP registration. 496 o Reserved is set to the value '0' on transmission and ignored on 497 reception. 499 o A set of N ANET interface "ifIndex-tuples" are included as 500 follows: 502 * ifIndex[i] is set to an 8-bit integer value corresponding to a 503 specific underlying ANET interface. The first ifIndex-tuple 504 MUST correspond to the ANET interface over which the message is 505 sent. IPv6 ND messages originating from a MN may include 506 multiple ifIndex-tuples, and MUST number each ifIndex with a 507 distinct value between '1' and '255' that represents a MN- 508 specific 8-bit mapping for the actual ifIndex value assigned to 509 the ANET interface by network management [RFC2863]. IPv6 ND 510 messages originating from the MS include a single ifIndex-tuple 511 with ifIndex set to the value '0'. 513 * ifType[i] is set to an 8-bit integer value corresponding to the 514 underlying ANET interface identified by ifIndex. The value 515 represents an OMNI interface-specific 8-bit mapping for the 516 actual IANA ifType value registered in the 'IANAifType-MIB' 517 registry [http://www.iana.org]. 519 * Reserved[i] is set to the value '0' on transmission and ignored 520 on reception. 522 * Link[i] encodes a 4-bit link metric. The value '0' means the 523 link is DOWN, and the remaining values mean the link is UP with 524 metric ranging from '1' ("lowest") to '15' ("highest"). 526 * QoS[i] encodes the number of 4-byte blocks (between '0' and 527 '15') of two-bit P[*] values that follow. The first 4 blocks 528 correspond to the 64 Differentiated Service Code Point (DSCP) 529 values P00 - P63 [RFC2474]. If additional 4-byte P[i] blocks 530 follow, their values correspond to "pseudo-DSCP" values P64, 531 P65, P66, etc. numbered consecutively. The pseudo-DSCP values 532 correspond to ancillary QoS information defined for the 533 specific OMNI interface (e.g., see Appendix A). 535 * P[*] includes zero or more per-ifIndex 4-byte blocks of two-bit 536 Preferences. Each P[*] field is set to the value '0' 537 ("disabled"), '1' ("low"), '2' ("medium") or '3' ("high") to 538 indicate a QoS preference level for ANET interface selection 539 purposes. The first four blocks always correspond to the 64 540 DSCP values. If one or more of the blocks are absent (e.g., 541 for QoS values 0,1,2,3) the P[*] values for the missing blocks 542 default to "medium". 544 o Notify-MSE contains the ID of a former MSE (between 0 and 545 0xfffffffe) to be notified of the MN's new MSE association (the 546 value 0xffffffff indicates that no notification is requested). 548 o Zero-padding added if necessary to produce an integral number of 8 549 octet blocks. 551 9. Address Mapping - Multicast 553 The multicast address mapping of the native underlying ANET interface 554 applies. The mobile router on board the aircraft also serves as an 555 IGMP/MLD Proxy for its EUNs and/or hosted applications per [RFC4605] 556 while using the L2 address of the router as the L2 address for all 557 multicast packets. 559 10. Address Mapping for IPv6 Neighbor Discovery Messages 561 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 562 unicast link-scoped IPv6 destination address. However, IPv6 ND 563 messaging is coordinated between the MN and MS only without invoking 564 other nodes on the ANET. 566 For this reason, ANET links maintain unicast L2 addresses ("MSADDR") 567 for the purpose of supporting MN/MS IPv6 ND messaging. For Ethernet- 568 compatible ANETs, this specification reserves one Ethernet unicast 569 address TBD2. For non-Ethernet statically-addressed ANETs, MSADDR is 570 reserved per the assigned numbers authority for the ANET addressing 571 space. For still other ANETs, MSADDR may be dynamically discovered 572 through other means, e.g., L2 beacons. 574 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 575 both multicast and unicast) to an MSADDR instead of to an ordinary 576 unicast or multicast L2 address. In this way, all of the MN's IPv6 577 ND messages will be received by MS devices that are configured to 578 accept packets destined to MSADDR. Note that multiple MS devices on 579 the link could be configured to accept packets destined to MSADDR, 580 e.g., as a basis for supporting redundancy. 582 Therefore, ARs MUST accept and process packets destined to MSADDR, 583 while all other devices MUST NOT process packets destined to MSADDR. 584 This model has well-established operational experience in Proxy 585 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 587 11. Conceptual Sending Algorithm 589 The MN's IPv6 layer selects the outbound OMNI interface according to 590 standard IPv6 requirements when forwarding data packets from local or 591 EUN applications to external correspondents. The OMNI interface 592 maintains default routes and neighbor cache entries for MSEs, and may 593 also include additional neighbor cache entries created through other 594 means (e.g., Address Resolution, static configuration, etc.). 596 After a packet enters the OMNI interface, an outbound ANET interface 597 is selected based on multilink parameters such as DSCP, application 598 port number, cost, performance, message size, etc. OMNI interface 599 multilink selections could also be configured to perform replication 600 across multiple ANET interfaces for increased reliability at the 601 expense of packet duplication. 603 OMNI interface multilink service designers MUST observe the BCP 604 guidance in Section 15 [RFC3819] in terms of implications for 605 reordering when packets from the same flow may be spread across 606 multiple ANET interfaces having diverse properties. 608 11.1. Multiple OMNI Interfaces 610 MNs may associate with multiple MS instances concurrently. Each MS 611 instance represents a distinct OMNI link distinguished by its 612 associated MSPs. The MN configures a separate OMNI interface for 613 each link so that multiple interfaces (e.g., omni0, omni1, omni2, 614 etc.) are exposed to the IPv6 layer. 616 Depending on local policy and configuration, an MN may choose between 617 alternative active OMNI interfaces using a packet's DSCP, routing 618 information or static configuration. Interface selection based on 619 per-packet source addresses is also enabled when the MSPs for each 620 OMNI interface are known (e.g., discovered through Prefix Information 621 Options (PIOs) and/or Route Information Options (RIOs)). 623 Each OMNI interface can be configured over the same or different sets 624 of ANET interfaces. Each ANET distinguishes between the different 625 OMNI links based on the MSPs represented in per-packet IPv6 626 addresses. 628 Multiple distinct OMNI links can therefore be used to support fault 629 tolerance, load balancing, reliability, etc. The architectural model 630 parallels Layer 2 Virtual Local Area Networks (VLANs), where the MSPs 631 serve as (virtual) VLAN tags. 633 12. Router Discovery and Prefix Registration 635 ARs process IPv6 ND messages destined to all-routers multicast 636 (ff02::2), the subnet router anycast LLA (fe80::) and unicast IPv6 637 LLAs. ARs configure the L2 address MSADDR (see: Section 10) and act 638 as a proxy for MSE OMNI LLAs in the range fe80::1 through 639 fe80::ffff:fffe. 641 MNs interface with the MS by sending RS messages with OMNI options. 642 For each ANET interface, the MN sends an RS message with an OMNI 643 option, with L2 destination address set to MSADDR and with L3 644 destination address set to either a specific MSE OMNI LLA, subnet 645 router anycast LLA, or all-routers multicast. The MN discovers MSE 646 OMNI LLAs either through an RA message response to an initial 647 anycast/multicast RS or before sending an initial RS message. 648 [RFC5214] provides example MSE address discovery methods, including 649 information conveyed during data link login, name service lookups, 650 static configuration, etc. 652 The AR receives the RS messages and coordinates with the 653 corresponding MSE in a manner outside the scope of this document. 654 The AR returns an RA message with source address set to the MSE OMNI 655 LLA, with an OMNI option and with any information for the link that 656 would normally be delivered in a solicited RA message. (Note that if 657 all MSEs share common state, the AR can instead return an RA with 658 source address set to the subnet router anycast LLA.) 660 MNs configure OMNI interfaces that observe the properties discussed 661 in the previous section. The OMNI interface and its underlying 662 interfaces are said to be in either the "UP" or "DOWN" state 663 according to administrative actions in conjunction with the interface 664 connectivity status. An OMNI interface transitions to UP or DOWN 665 through administrative action and/or through state transitions of the 666 underlying interfaces. When a first underlying interface transitions 667 to UP, the OMNI interface also transitions to UP. When all 668 underlying interfaces transition to DOWN, the OMNI interface also 669 transitions to DOWN. 671 When an OMNI interface transitions to UP, the MN sends initial RS 672 messages to register its MNP and an initial set of underlying ANET 673 interfaces that are also UP. The MN sends additional RS messages to 674 refresh lifetimes and to register/deregister underlying ANET 675 interfaces as they transition to UP or DOWN. 677 ARs return RA messages with configuration information in response to 678 a MN's RS messages. The RAs include a Router Lifetime value and any 679 necessary options, such as: 681 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 683 o RIOs [RFC4191] with more-specific routes. 685 o an MTU option that specifies the maximum acceptable packet size 686 for the OMNI link 688 The AR coordinates with the MSE and sends immediate unicast RA 689 responses without delay; therefore, the IPv6 ND MAX_RA_DELAY_TIME and 690 MIN_DELAY_BETWEEN_RAS constants for multicast RAs do not apply. The 691 AR MAY send periodic and/or event-driven unsolicited RA messages, but 692 is not required to do so for unicast advertisements [RFC4861]. 694 The MN sends RS messages from within the OMNI interface while using 695 an UP underlying ANET interface as the outbound interface. Each RS 696 message is formatted as though it originated from the IPv6 layer, but 697 the process is coordinated wholly from within the OMNI interface and 698 is therefore opaque to the IPv6 layer. The MN sends initial RS 699 messages over an UP underlying interface with its OMNI LLA as the 700 source. The RS messages include an OMNI option with a valid Prefix 701 Length as well as ifIndex-tuples appropriate for underlying ANET 702 interfaces. The AR processes RS message and conveys the OMNI option 703 information to the MSE. 705 When the MSE processes the OMNI information, if the prefix 706 registration was accepted the MSE injects the MNP into the routing/ 707 mapping system then caches the new Prefix Length, MNP and ifIndex- 708 tuples. The MSE then directs the AR to return an RA message to the 709 MN with an OMNI option and with a non-zero Router Lifetime if the 710 prefix assertion was acceptable; otherwise, with a zero Router 711 Lifetime. If the MN's OMNI option included a "Notify-MSE" value 712 between 0 and 0xfffffffe, the new MSE also notifies the former MSE 713 (with reliable confirmation). 715 When the MN receives the RA message, it creates a default route with 716 L3 next hop address set to the address found in the RA source address 717 and with L2 address set to MSADDR. The AR will then forward packets 718 between the MN and the MS. 720 The MN then manages its underlying ANET interfaces according to their 721 states as follows: 723 o When an underlying ANET interface transitions to UP, the MN sends 724 an RS over the ANET interface with an OMNI option. The OMNI 725 option contains a first ifIndex-tuple with values specific to this 726 ANET interface, and may contain additional ifIndex-tuples specific 727 to other ANET interfaces. 729 o When an underlying ANET interface transitions to DOWN, the MN 730 sends an RS or unsolicited NA message over any UP ANET interface 731 with an OMNI option containing an ifIndex-tuple for the DOWN ANET 732 interface with Link(i) set to '0'. The MN sends an RS when an 733 acknowledgement is required, or an unsolicited NA when reliability 734 is not thought to be a concern (e.g., if redundant transmissions 735 are sent on multiple ANET interfaces). 737 o When a MN wishes to release from a current MSE, it sends an RS or 738 unsolicited NA message over any UP ANET interfaces with an OMNI 739 option with R set to 0. The corresponding MSE then withdraws the 740 MNP from the routing/mapping system and (for RS responses) returns 741 an RA message with an OMNI option and with Router Lifetime set to 742 0. 744 o When a MN wishes to transition to a new MSE, it sends an RS or 745 unsolicited NA message over any UP ANET interfaces with an OMNI 746 option with R set to 1, with the new MSE OMNI LLA set in the 747 destination address, and (optionally) with a former MSE value set 748 in the "Notify-MSE" field. 750 o When all of a MNs underlying interfaces have transitioned to DOWN, 751 the MSE withdraws the MNP the same as if it had received a message 752 with an OMNI option with R set to 0. 754 The MN is responsible for retrying each RS exchange up to 755 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 756 seconds until an RA is received. If no RA is received over multiple 757 UP ANET interfaces, the MN declares this MSE unreachable and tries a 758 different MSE. 760 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 761 Therefore, when the IPv6 layer sends an RS message the OMNI interface 762 returns an internally-generated RA message as though the message 763 originated from an IPv6 router. The internally-generated RA message 764 contains configuration information (such as Router Lifetime, MTU, 765 etc.) that is consistent with the information received from the RAs 766 generated by the MS. 768 Whether the OMNI interface IPv6 ND messaging process is initiated 769 from the receipt of an RS message from the IPv6 layer is an 770 implementation matter. Some implementations may elect to defer the 771 IPv6 ND messaging process until an RS is received from the IPv6 772 layer, while others may elect to initiate the process proactively. 774 13. AR and MSE Resilience 776 ANETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 777 [RFC5798] configurations so that service continuity is maintained 778 even if one or more ARs fail. Using VRRP, the MN is unaware which of 779 the (redundant) ARs is currently providing service, and any service 780 discontinuity will be limited to the failover time supported by VRRP. 781 Widely deployed public domain implementations of VRRP are available. 783 MSEs SHOULD use high availability clustering services so that 784 multiple redundant systems can provide coordinated response to 785 failures. As with VRRP, widely deployed public domain 786 implementations of high availability clustering services are 787 available. Note that special-purpose and expensive dedicated 788 hardware is not necessary, and public domain implementations can be 789 used even between lightweight virtual machines in cloud deployments. 791 14. Detecting and Responding to MSE Failures 793 In environments where fast recovery from MSE failure is required, ARs 794 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 795 manner that parallels Bidirectional Forwarding Detection (BFD) 796 [RFC5880] to track MSE reachability. ARs can then quickly detect and 797 react to failures so that cached information is re-established 798 through alternate paths. Proactive NUD control messaging is carried 799 only over well-connected ground domain networks (i.e., and not low- 800 end aeronautical radio links) and can therefore be tuned for rapid 801 response. 803 ARs employ proactive NUD with MSEs for which there are currently 804 active ANET MNs. If an MSE fails, ARs can quickly inform MNs of the 805 outage by sending RA messages on the ANET interface. The AR sends RA 806 messages to the MN via the ANET interface with source address set to 807 the MSEs OMNI LLA, destination address set to all-nodes multicast, 808 and Router Lifetime set to 0. 810 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 811 by small delays [RFC4861]. Any MNs on the ANET interface that have 812 been using the (now defunct) MSE will receive the RA messages and 813 associate with a new MSE. 815 15. IANA Considerations 817 The IANA is instructed to allocate an official Type number TBD from 818 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 819 option. Implementations set Type to 253 as an interim value 820 [RFC4727]. 822 The IANA is instructed to allocate one Ethernet unicast address TBD2 823 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 824 Address Block - Unicast Use". 826 16. Security Considerations 828 Security considerations for IPv6 [RFC8200] and IPv6 Neighbor 829 Discovery [RFC4861] apply. OMNI interface IPv6 ND messages SHOULD 830 include Nonce and Timestamp options [RFC3971] when synchronized 831 transaction confirmation is needed. 833 Security considerations for specific access network interface types 834 are covered under the corresponding IP-over-(foo) specification 835 (e.g., [RFC2464]). 837 17. Acknowledgements 839 The first version of this document was prepared per the consensus 840 decision at the 7th Conference of the International Civil Aviation 841 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 842 2019. Consensus to take the document forward to the IETF was reached 843 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 844 Attendees and contributors included: Guray Acar, Danny Bharj, 845 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 846 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 847 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 848 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 849 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 850 Fryderyk Wrobel and Dongsong Zeng. 852 The following individuals are acknowledged for their useful comments: 853 Pavel Drasil, Zdenek Jaron, Michael Matyas, Madhu Niraula, Greg 854 Saccone, Stephane Tamalet, Eric Vyncke. Naming of the IPv6 ND option 855 was discussed on the 6man mailing list. 857 This work is aligned with the NASA Safe Autonomous Systems Operation 858 (SASO) program under NASA contract number NNA16BD84C. 860 This work is aligned with the FAA as per the SE2025 contract number 861 DTFAWA-15-D-00030. 863 18. References 865 18.1. Normative References 867 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 868 Requirement Levels", BCP 14, RFC 2119, 869 DOI 10.17487/RFC2119, March 1997, 870 . 872 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 873 "Definition of the Differentiated Services Field (DS 874 Field) in the IPv4 and IPv6 Headers", RFC 2474, 875 DOI 10.17487/RFC2474, December 1998, 876 . 878 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 879 "SEcure Neighbor Discovery (SEND)", RFC 3971, 880 DOI 10.17487/RFC3971, March 2005, 881 . 883 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 884 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 885 November 2005, . 887 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 888 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 889 2006, . 891 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 892 ICMPv6, UDP, and TCP Headers", RFC 4727, 893 DOI 10.17487/RFC4727, November 2006, 894 . 896 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 897 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 898 DOI 10.17487/RFC4861, September 2007, 899 . 901 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 902 Address Autoconfiguration", RFC 4862, 903 DOI 10.17487/RFC4862, September 2007, 904 . 906 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 907 Hosts in a Multi-Prefix Network", RFC 8028, 908 DOI 10.17487/RFC8028, November 2016, 909 . 911 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 912 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 913 May 2017, . 915 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 916 (IPv6) Specification", STD 86, RFC 8200, 917 DOI 10.17487/RFC8200, July 2017, 918 . 920 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 921 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 922 DOI 10.17487/RFC8201, July 2017, 923 . 925 18.2. Informative References 927 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 928 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 929 . 931 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 932 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 933 . 935 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 936 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 937 December 1998, . 939 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 940 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 941 . 943 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 944 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 945 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 946 RFC 3819, DOI 10.17487/RFC3819, July 2004, 947 . 949 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 950 "Internet Group Management Protocol (IGMP) / Multicast 951 Listener Discovery (MLD)-Based Multicast Forwarding 952 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 953 August 2006, . 955 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 956 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 957 RFC 5213, DOI 10.17487/RFC5213, August 2008, 958 . 960 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 961 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 962 DOI 10.17487/RFC5214, March 2008, 963 . 965 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 966 Version 3 for IPv4 and IPv6", RFC 5798, 967 DOI 10.17487/RFC5798, March 2010, 968 . 970 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 971 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 972 . 974 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 975 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 976 2012, . 978 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 979 Requirements for IPv6 Customer Edge Routers", RFC 7084, 980 DOI 10.17487/RFC7084, November 2013, 981 . 983 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 984 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 985 Boundary in IPv6 Addressing", RFC 7421, 986 DOI 10.17487/RFC7421, January 2015, 987 . 989 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 990 Support for IP Hosts with Multi-Access Support", RFC 7847, 991 DOI 10.17487/RFC7847, May 2016, 992 . 994 Appendix A. OMNI Option Extensions for Pseudo-DSCP Mappings 996 Adaptation of the OMNI interface to specific Internetworks such as 997 the Aeronautical Telecommunications Network with Internet Protocol 998 Services (ATN/IPS) includes link selection preferences based on 999 transport port numbers in addition to the existing DSCP-based 1000 preferences. ATN/IPS nodes maintain a map of transport port numbers 1001 to additional "pseudo-DSCP" P[*] preference fields beyond the first 1002 64. For example, TCP port 22 maps to pseudo-DSCP value P67, TCP port 1003 443 maps to P70, UDP port 8060 maps to P76, etc. Figure 4 shows an 1004 example OMNI option with extended P[*] values beyond the base 64 used 1005 for DSCP mapping (i.e., for QoS values 5 or greater): 1007 0 1 2 3 1008 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 1009 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1010 | Type | Length | Prefix Length |R| Reserved | 1011 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1012 | ifIndex | ifType | Flags | Link |QoS=5+ | 1013 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1014 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 1015 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1016 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 1017 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1018 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 1019 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1020 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1021 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1022 |P64|P65|P66|P67|P68|P69|P70|P71|P72|P73|P74|P75|P76|P77|P78|P79| 1023 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1024 ... 1026 Figure 4: ATN/IPS Extended OMNI Option Format 1028 Appendix B. Prefix Length Considerations 1030 The 64-bit boundary in IPv6 addresses [RFC7421] determines the MN 1031 OMNI LLA format for encoding the most-significant 64 MNP bits into 1032 the least-significant 64 bits of the prefix fe80::/64 as discussed in 1033 Section 7. 1035 [RFC4291] defines the link-local address format as fe80::/10, 1036 followed by 54 unused bits, followed by the least-significant 64 bits 1037 of the address. If the 64-bit boundary is relaxed through future 1038 standards activity, then the 54 unused bits can be employed for 1039 extended coding of MNPs of length /65 up to /118. 1041 The extended coding format would continue to encode MNP bits 0-63 in 1042 bits 64-127 of the OMNI LLA, while including MNP bits 64-117 in bits 1043 10-63. For example, the OMNI LLA corresponding to the MNP 1044 2001:db8:1111:2222:3333:4444:5555::/112 would be 1045 fe8c:ccd1:1115:5540:2001:db8:1111:2222, and would still be a valid 1046 IPv6 LLA per [RFC4291]. 1048 Appendix C. VDL Mode 2 Considerations 1050 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 1051 (VDLM2) that specifies an essential radio frequency data link service 1052 for aircraft and ground stations in worldwide civil aviation air 1053 traffic management. The VDLM2 link type is "multicast capable" 1055 [RFC4861], but with considerable differences from common multicast 1056 links such as Ethernet and IEEE 802.11. 1058 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 1059 magnitude less than most modern wireless networking gear. Second, 1060 due to the low available link bandwidth only VDLM2 ground stations 1061 (i.e., and not aircraft) are permitted to send broadcasts, and even 1062 so only as compact layer 2 "beacons". Third, aircraft employ the 1063 services of ground stations by performing unicast RS/RA exchanges 1064 upon receipt of beacons instead of listening for multicast RA 1065 messages and/or sending multicast RS messages. 1067 This beacon-oriented unicast RS/RA approach is necessary to conserve 1068 the already-scarce available link bandwidth. Moreover, since the 1069 numbers of beaconing ground stations operating within a given spatial 1070 range must be kept as sparse as possible, it would not be feasible to 1071 have different classes of ground stations within the same region 1072 observing different protocols. It is therefore highly desirable that 1073 all ground stations observe a common language of RS/RA as specified 1074 in this document. 1076 Note that links of this nature may benefit from compression 1077 techniques that reduce the bandwidth necessary for conveying the same 1078 amount of data. The IETF lpwan working group is considering possible 1079 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 1081 Appendix D. Change Log 1083 << RFC Editor - remove prior to publication >> 1085 Differences from draft-templin-atn-aero-interface-11 to draft- 1086 templin-atn-aero-interface-12: 1088 o Removed "Request/Response" OMNI option formats. Now, there is 1089 only one OMNI option format that applies to all ND messages. 1091 o Added new OMNI option field and supporting text for "Notify-MSE". 1093 Differences from draft-templin-atn-aero-interface-10 to draft- 1094 templin-atn-aero-interface-11: 1096 o Changed name from "aero" to "OMNI" 1098 o Resolved AD review comments from Eric Vyncke (posted to atn list) 1100 Differences from draft-templin-atn-aero-interface-09 to draft- 1101 templin-atn-aero-interface-10: 1103 o Renamed ARO option to AERO option 1105 o Re-worked Section 13 text to discuss proactive NUD. 1107 Differences from draft-templin-atn-aero-interface-08 to draft- 1108 templin-atn-aero-interface-09: 1110 o Version and reference update 1112 Differences from draft-templin-atn-aero-interface-07 to draft- 1113 templin-atn-aero-interface-08: 1115 o Removed "Classic" and "MS-enabled" link model discussion 1117 o Added new figure for MN/AR/MSE model. 1119 o New Section on "Detecting and responding to MSE failure". 1121 Differences from draft-templin-atn-aero-interface-06 to draft- 1122 templin-atn-aero-interface-07: 1124 o Removed "nonce" field from AR option format. Applications that 1125 require a nonce can include a standard nonce option if they want 1126 to. 1128 o Various editorial cleanups. 1130 Differences from draft-templin-atn-aero-interface-05 to draft- 1131 templin-atn-aero-interface-06: 1133 o New Appendix C on "VDL Mode 2 Considerations" 1135 o New Appendix D on "RS/RA Messaging as a Single Standard API" 1137 o Various significant updates in Section 5, 10 and 12. 1139 Differences from draft-templin-atn-aero-interface-04 to draft- 1140 templin-atn-aero-interface-05: 1142 o Introduced RFC6543 precedent for focusing IPv6 ND messaging to a 1143 reserved unicast link-layer address 1145 o Introduced new IPv6 ND option for Aero Registration 1147 o Specification of MN-to-MSE message exchanges via the ANET access 1148 router as a proxy 1150 o IANA Considerations updated to include registration requests and 1151 set interim RFC4727 option type value. 1153 Differences from draft-templin-atn-aero-interface-03 to draft- 1154 templin-atn-aero-interface-04: 1156 o Removed MNP from aero option format - we already have RIOs and 1157 PIOs, and so do not need another option type to include a Prefix. 1159 o Clarified that the RA message response must include an aero option 1160 to indicate to the MN that the ANET provides a MS. 1162 o MTU interactions with link adaptation clarified. 1164 Differences from draft-templin-atn-aero-interface-02 to draft- 1165 templin-atn-aero-interface-03: 1167 o Sections re-arranged to match RFC4861 structure. 1169 o Multiple aero interfaces 1171 o Conceptual sending algorithm 1173 Differences from draft-templin-atn-aero-interface-01 to draft- 1174 templin-atn-aero-interface-02: 1176 o Removed discussion of encapsulation (out of scope) 1178 o Simplified MTU section 1180 o Changed to use a new IPv6 ND option (the "aero option") instead of 1181 S/TLLAO 1183 o Explained the nature of the interaction between the mobility 1184 management service and the air interface 1186 Differences from draft-templin-atn-aero-interface-00 to draft- 1187 templin-atn-aero-interface-01: 1189 o Updates based on list review comments on IETF 'atn' list from 1190 4/29/2019 through 5/7/2019 (issue tracker established) 1192 o added list of opportunities afforded by the single virtual link 1193 model 1195 o added discussion of encapsulation considerations to Section 6 1197 o noted that DupAddrDetectTransmits is set to 0 1198 o removed discussion of IPv6 ND options for prefix assertions. The 1199 aero address already includes the MNP, and there are many good 1200 reasons for it to continue to do so. Therefore, also including 1201 the MNP in an IPv6 ND option would be redundant. 1203 o Significant re-work of "Router Discovery" section. 1205 o New Appendix B on Prefix Length considerations 1207 First draft version (draft-templin-atn-aero-interface-00): 1209 o Draft based on consensus decision of ICAO Working Group I Mobility 1210 Subgroup March 22, 2019. 1212 Authors' Addresses 1214 Fred L. Templin (editor) 1215 The Boeing Company 1216 P.O. Box 3707 1217 Seattle, WA 98124 1218 USA 1220 Email: fltemplin@acm.org 1222 Tony Whyman 1223 MWA Ltd c/o Inmarsat Global Ltd 1224 99 City Road 1225 London EC1Y 1AX 1226 England 1228 Email: tony.whyman@mccallumwhyman.com