idnits 2.17.1 draft-templin-atn-aero-interface-17.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (February 4, 2020) is 1514 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 453 -- Looks like a reference, but probably isn't: '2' on line 463 == Missing Reference: 'N' is mentioned on line 475, but not defined == Unused Reference: 'RFC2225' is defined on line 958, 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: August 7, 2020 MWA Ltd c/o Inmarsat Global Ltd 6 February 4, 2020 8 Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) 9 Interfaces 10 draft-templin-atn-aero-interface-17 12 Abstract 14 Mobile nodes (e.g., aircraft of various configurations, terrestrial 15 vehicles, seagoing vessels, mobile enterprise devices, etc.) 16 communicate with networked correspondents over multiple access 17 network data links and configure mobile routers to connect end user 18 networks. A multilink interface specification is therefore needed 19 for coordination with the network-based mobility service. This 20 document specifies the transmission of IPv6 packets over Overlay 21 Multilink Network (OMNI) Interfaces. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on August 7, 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 (OMNI) Interface 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 . . . . . . . . . . . . . . . . . . . . . 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 . . 23 79 Appendix B. Prefix Length Considerations . . . . . . . . . . . . 23 80 Appendix C. VDL Mode 2 Considerations . . . . . . . . . . . . . 24 81 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 25 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28 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 properties that can change dynamically according to 91 mobility patterns, flight phases, proximity to infrastructure, etc. 92 MNs coordinate their data links in a discipline known as "multilink", 93 in 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) for numbering 108 downstream-attached End User Networks (EUNs) independently of the 109 access network data links selected for data transport. The MN 110 performs router discovery over the OMNI interface (i.e., similar to 111 IPv6 customer edge routers [RFC7084]) and acts as a mobile router on 112 behalf of its EUNs. The router discovery process is iterated over 113 each of the OMNI interface's underlying access network data links in 114 order to register per-link parameters (see Section 12). 116 The OMNI interface provides a multilink nexus for exchanging inbound 117 and outbound traffic via 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 a network-based 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. The terms 140 "All-Routers multicast", "All-Nodes multicast" and "Subnet-Router 141 anycast" are defined in [RFC4291] (with Link-Local scope assumed). 143 The following terms are defined within the scope of this document: 145 Mobile Node (MN) 146 an end system with multiple distinct upstream data link 147 connections that are managed together as a single logical unit. 148 The MN's data link connection parameters can change over time due 149 to, e.g., node mobility, link quality, etc. The MN further 150 connects a downstream-attached End User Network (EUN). The term 151 MN used here is distinct from uses in other documents, and does 152 not imply a particular mobility protocol. 154 End User Network (EUN) 155 a simple or complex downstream-attached mobile network that 156 travels with the MN as a single logical unit. The IPv6 addresses 157 assigned to EUN devices remain stable even if the MN's upstream 158 data link connections change. 160 Mobility Service (MS) 161 a mobile routing service that tracks MN movements and ensures that 162 MNs remain continuously reachable even across mobility events. 163 Specific MS details are out of scope for this document. 165 Mobility Service Prefix (MSP) 166 an aggregated IPv6 prefix (e.g., 2001:db8::/32) advertised to the 167 rest of the Internetwork by the MS, and from which more-specific 168 Mobile Network Prefixes (MNPs) are derived. 170 Mobile Network Prefix (MNP) 171 a longer IPv6 prefix taken from the MSP (e.g., 172 2001:db8:1000:2000::/56) and assigned to a MN. MNs sub-delegate 173 the MNP to devices located in EUNs. 175 Access Network (ANET) 176 a data link service network (e.g., an aviation radio access 177 network, satellite service provider network, cellular operator 178 network, etc.) that provides an Access Router (AR) for connecting 179 MNs to correspondents in outside Internetworks. Physical and/or 180 data link level security between the MN and AR are assumed. 182 ANET interface 183 a MN's attachment to a link in an ANET. 185 Internetwork (INET) 186 a connected network region with a coherent IP addressing plan that 187 provides transit forwarding services for ANET MNs and INET 188 correspondents. Examples include private enterprise networks, 189 ground domain aviation service networks and the global public 190 Internet itself. 192 INET interface 193 a node's attachment to a link in an INET. 195 OMNI link 196 a virtual overlay configured over one or more INETs and their 197 connected ANETs. An OMNI link can comprise multiple INET segments 198 joined by bridges the same as for any link; the addressing plans 199 in each segment may be mutually exclusive and managed by different 200 administrative entities. 202 OMNI interface 203 a node's attachment to an OMNI link, and configured over one or 204 more underlying ANET/INET interfaces. 206 OMNI link local address (LLA) 207 an IPv6 link-local address constructed as specified in Section 7, 208 and assigned to an OMNI interface. 210 Multilink 211 an OMNI interface's manner of managing diverse underlying data 212 link interfaces as a single logical unit. The OMNI interface 213 provides a single unified interface to upper layers, while 214 underlying data link selections are performed on a per-packet 215 basis considering factors such as DSCP, flow label, application 216 policy, signal quality, cost, etc. Multilinking decisions are 217 coordinated in both the outbound (i.e. MN to correspondent) and 218 inbound (i.e., correspondent to MN) directions. 220 L2 221 The second layer in the OSI network model. Also known as "layer- 222 2", "link-layer", "sub-IP layer", "data link layer", etc. 224 L3 225 The third layer in the OSI network model. Also known as "layer- 226 3", "network-layer", "IPv6 layer", etc. 228 3. Requirements 230 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 231 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 232 "OPTIONAL" in this document are to be interpreted as described in BCP 233 14 [RFC2119][RFC8174] when, and only when, they appear in all 234 capitals, as shown here. 236 4. Overlay Multilink Network (OMNI) Interface Model 238 An OMNI interface is a MN virtual interface configured over one or 239 more ANET interfaces, which may be physical (e.g., an aeronautical 240 radio link) or virtual (e.g., an Internet or higher-layer "tunnel"). 242 The MN receives a MNP from the MS, and coordinates with the MS 243 through IPv6 ND message exchanges. The MN uses the MNP to construct 244 a unique OMNI LLA through the algorithmic derivation specified in 245 Section 7 and assigns the LLA to the OMNI interface. 247 The OMNI interface architectural layering model is the same as in 248 [RFC7847], and augmented as shown in Figure 1. The IP layer (L3) 249 therefore sees the OMNI interface as a single network layer interface 250 with multiple underlying ANET interfaces that appear as L2 251 communication channels in the architecture. 253 +----------------------------+ 254 | Upper Layer Protocol | 255 Session-to-IP +---->| | 256 Address Binding | +----------------------------+ 257 +---->| IP (L3) | 258 IP Address +---->| | 259 Binding | +----------------------------+ 260 +---->| OMNI Interface | 261 Logical-to- +---->| (OMNI LLA) | 262 Physical | +----------------------------+ 263 Interface +---->| L2 | L2 | | L2 | 264 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 265 +------+------+ +------+ 266 | L1 | L1 | | L1 | 267 | | | | | 268 +------+------+ +------+ 270 Figure 1: OMNI Interface Architectural Layering Model 272 The OMNI virtual interface model gives rise to a number of 273 opportunities: 275 o since OMNI LLAs are uniquely derived from an MNP, no Duplicate 276 Address Detection (DAD) messaging is necessary over the OMNI 277 interface. 279 o ANET interfaces do not require any L3 addresses (i.e., not even 280 link-local) in environments where communications are coordinated 281 entirely over the OMNI interface. 283 o as ANET interface properties change (e.g., link quality, cost, 284 availability, etc.), any active ANET interface can be used to 285 update the profiles of multiple additional ANET interfaces in a 286 single message. This allows for timely adaptation and service 287 continuity under dynamically changing conditions. 289 o coordinating ANET interfaces in this way allows them to be 290 represented in a unified MS profile with provisions for mobility 291 and multilink operations. 293 o exposing a single virtual interface abstraction to the IPv6 layer 294 allows for multilink operation (including QoS based link 295 selection, packet replication, load balancing, etc.) at L2 while 296 still permitting queuing at the L3 based on, e.g., DSCP, flow 297 label, etc. 299 o L3 sees the OMNI interface as a point of connection to the OMNI 300 link; if there are multiple OMNI links (i.e., multiple MS's), L3 301 will see multiple OMNI interfaces. 303 Other opportunities are discussed in [RFC7847]. 305 Figure 2 depicts the architectural model for a MN connecting to the 306 MS via multiple independent ANETs. When an ANET interface becomes 307 active, the MN's OMNI interface sends native (i.e., unencapsulated) 308 IPv6 ND messages via the underlying ANET interface. IPv6 ND messages 309 traverse the ground domain ANETs until they reach an Access Router 310 (AR#1, AR#2, .., AR#n). The AR then coordinates with a Mobility 311 Service Endpoint (MSE#1, MSE#2, ..., MSE#m) in the INET and returns 312 an IPv6 ND message response to the MN. IPv6 ND messages traverse the 313 ANET at layer 2; hence, the Hop Limit is not decremented. 315 +--------------+ 316 | MN | 317 +--------------+ 318 |OMNI interface| 319 +----+----+----+ 320 +--------|IF#1|IF#2|IF#n|------ + 321 / +----+----+----+ \ 322 / | \ 323 / <---- Native | IP ----> \ 324 v v v 325 (:::)-. (:::)-. (:::)-. 326 .-(::ANET:::) .-(::ANET:::) .-(::ANET:::) 327 `-(::::)-' `-(::::)-' `-(::::)-' 328 +----+ +----+ +----+ 329 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 330 . +-|--+ +-|--+ +-|--+ . 331 . | | | 332 . v v v . 333 . <----- Encapsulation -----> . 334 . . 335 . +-----+ (:::)-. . 336 . |MSE#2| .-(::::::::) +-----+ . 337 . +-----+ .-(::: INET :::)-. |MSE#m| . 338 . (::::: Routing ::::) +-----+ . 339 . `-(::: System :::)-' . 340 . +-----+ `-(:::::::-' . 341 . |MSE#1| +-----+ +-----+ . 342 . +-----+ |MSE#3| |MSE#4| . 343 . +-----+ +-----+ . 344 . . 345 . . 346 . <----- Worldwide Connected Internetwork ----> . 347 ........................................................... 349 Figure 2: MN/MS Coordination via Multiple ANETs 351 After the initial IPv6 ND message exchange, the MN can send and 352 receive unencapsulated IPv6 data packets over the OMNI interface. 353 OMNI interface multilink services will forward the packets via ARs in 354 the correct underlying ANETs. The AR encapsulates the packets 355 according to the capabilities provided by the MS and forwards them to 356 the next hop within the worldwide connected Internetwork via optimal 357 routes. 359 5. Maximum Transmission Unit 361 All IPv6 interfaces MUST configure an MTU of at least 1280 bytes 362 [RFC8200]. The OMNI interface configures its MTU based on the 363 largest MTU among all underlying ANET interfaces. The value MAY be 364 overridden if an RA message with an MTU option is received. 366 The OMNI interface returns internally-generated IPv6 Path MTU 367 Discovery (PMTUD) Packet Too Big (PTB) messages [RFC8201] for packets 368 admitted into the OMNI interface that are too large for the outbound 369 underlying ANET interface. Similarly, the OMNI interface performs 370 PMTUD even if the destination appears to be on the same link since a 371 proxy on the path could return a PTB message. PMTUD therefore 372 ensures that the OMNI interface MTU is adaptive and reflects the 373 current path used for a given data flow. 375 Applications that cannot tolerate loss due to MTU restrictions SHOULD 376 refrain from sending packets larger than 1280 bytes, since dynamic 377 path changes can reduce the path MTU at any time. Applications that 378 may benefit from sending larger packets even though the path MTU may 379 change dynamically MAY use larger sizes. 381 6. Frame Format 383 The OMNI interface transmits IPv6 packets according to the native 384 frame format of each underlying ANET interface. For example, for 385 Ethernet-compatible interfaces the frame format is specified in 386 [RFC2464], for aeronautical radio interfaces the frame format is 387 specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical 388 Manual), for tunnels over IPv6 the frame format is specified in 389 [RFC2473], etc. 391 7. Link-Local Addresses 393 OMNI interfaces assign IPv6 Link-Local Addresses (i.e., "OMNI LLAs") 394 using the following constructs: 396 o IPv6 MN OMNI LLAs encode the most-significant 64 bits of a MNP 397 within the least-significant 64 bits (i.e., the interface ID) of a 398 Link-Local IPv6 Unicast Address (see: [RFC4291], Section 2.5.6). 399 For example, for the MNP 2001:db8:1000:2000::/56 the corresponding 400 LLA is fe80::2001:db8:1000:2000. 402 o IPv4-compatible MN OMNI LLAs are assigned as fe80::ffff:[v4addr], 403 i.e., the most significant 10 bits of the prefix fe80::/10, 404 followed by 70 '0' bits, followed by 16 '1' bits, followed by a 405 32bit IPv4 address. For example, the IPv4-Compatible MN OMNI LLA 406 for 192.0.2.1 is fe80::ffff:192.0.2.1 (also written as 407 fe80::ffff:c000:0201). 409 o MSE OMNI LLAs are assigned from the range fe80::/96, and MUST be 410 managed for uniqueness. The lower 32 bits of the LLA includes a 411 unique integer value between '1' and 'fffffffe', e.g., as in 412 fe80::1, fe80::2, fe80::3, etc., fe80::ffff:fffe. The address 413 fe80:: is the link-local Subnet-Router anycast address [RFC4291] 414 and the address fe80::ffff:ffff is reserved. (Note that distinct 415 OMNI link segments can avoid overlap by assignig MSE OMNI LLAs 416 from unique fe80::/96 sub-prefixes. For example, a first segment 417 could assign from fe80::1000/116, a second from fe80::2000/116, a 418 third from fe80::3000/116, etc.) 420 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 421 MNPs can be allocated from that block ensuring that there is no 422 possibility for overlap between the above OMNI LLA constructs. 424 Since MN OMNI LLAs are based on the distribution of administratively 425 assured unique MNPs, and since MSE OMNI LLAs are guaranteed unique 426 through administrative assignment, OMNI interfaces set the 427 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 429 8. Address Mapping - Unicast 431 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 432 state and use the link-local address format specified in Section 7. 433 IPv6 Neighbor Discovery (ND) [RFC4861] messages on MN OMNI interfaces 434 observe the native Source/Target Link-Layer Address Option (S/TLLAO) 435 formats of the underlying ANET interfaces (e.g., for Ethernet the S/ 436 TLLAO is specified in [RFC2464]). 438 MNs such as aircraft typically have many wireless data link types 439 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 440 etc.) with diverse performance, cost and availability properties. 441 The OMNI interface would therefore appear to have multiple L2 442 connections, and may include information for multiple ANET interfaces 443 in a single IPv6 ND message exchange. 445 OMNI interfaces use an IPv6 ND option called the "OMNI option" 446 formatted as shown in Figure 3: 448 0 1 2 3 449 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 1 450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 451 | Type | Length | Prefix Length |R|N|P| Reservd | 452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 453 | ifIndex[1] | ifType[1] | Reserved [1] |Link[1]|QoS[1] | 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 459 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 461 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 463 | ifIndex[2] | ifType[2] | Reserved [2] |Link[2]|QoS[2] | 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 467 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 469 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 471 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 472 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 473 ... ... ... 474 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 475 | ifIndex[N] | ifType[N] | Reserved [N] |Link[N]|QoS[N] | 476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 478 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 481 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 485 | zero-padding (if necessary) | 486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 487 | Notification ID (present only if N=1) | 488 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 490 Figure 3: OMNI Option Format 492 In this format: 494 o Type is set to TBD. 496 o Length is set to the number of 8 octet blocks in the option. 498 o Prefix Length is set according to the IPv6 source LLA type. For 499 MN OMNI LLAs, the value is set to the length of the embedded MNP. 500 For MSE OMNI LLAs, the value is set to 128. 502 o R (the "Register/Release" bit) is set to '1' to register an MNP or 503 set to '0' to release a registration. 505 o N (the "Notify" bit) is set to '1' if the option includes a 506 trailing 4 byte "Notification ID" (see below). Valid only in MN 507 RS messages, and ignored in all other ND messages. 509 o P (the "Primary" bit) is set to '1' in a MN RS message to request 510 an AR to serve as primary, and set to '1' in the AR's RA message 511 to accept the primary role. Set to '0' in all other RS/RA 512 messages, and ignored in all other ND messages. 514 o Reservd is set to the value '0' on transmission and ignored on 515 reception. 517 o A set of N ANET interface "ifIndex-tuples" are included as 518 follows: 520 * ifIndex[i] is set to an 8-bit integer value corresponding to a 521 specific underlying ANET interface. The first ifIndex-tuple 522 MUST correspond to the ANET interface over which the message is 523 sent. IPv6 ND messages originating from a MN may include 524 multiple ifIndex-tuples, and MUST number each with a distinct 525 ifIndex value between '1' and '255' that represents a MN- 526 specific 8-bit mapping for the actual ifIndex value assigned to 527 the ANET interface by network management [RFC2863]. IPv6 ND 528 messages originating from the MS include a single ifIndex-tuple 529 with ifIndex set to the value '0'. 531 * ifType[i] is set to an 8-bit integer value corresponding to the 532 underlying ANET interface identified by ifIndex. The value 533 represents an OMNI interface-specific 8-bit mapping for the 534 actual IANA ifType value registered in the 'IANAifType-MIB' 535 registry [http://www.iana.org]. 537 * Reserved[i] is set to the value '0' on transmission and ignored 538 on reception. 540 * Link[i] encodes a 4-bit link metric. The value '0' means the 541 link is DOWN, and the remaining values mean the link is UP with 542 metric ranging from '1' ("lowest") to '15' ("highest"). 544 * QoS[i] encodes the number of 4-byte blocks (between '0' and 545 '15') of two-bit P[*] values that follow. The first 4 blocks 546 correspond to the 64 Differentiated Service Code Point (DSCP) 547 values P00 - P63 [RFC2474]. If additional 4-byte P[i] blocks 548 follow, their values correspond to "pseudo-DSCP" values P64, 549 P65, P66, etc. numbered consecutively. The pseudo-DSCP values 550 correspond to ancillary QoS information defined for the 551 specific OMNI interface (e.g., see Appendix A). 553 * P[*] includes zero or more per-ifIndex 4-byte blocks of two-bit 554 Preferences. Each P[*] field is set to the value '0' 555 ("disabled"), '1' ("low"), '2' ("medium") or '3' ("high") to 556 indicate a QoS preference level for ANET interface selection 557 purposes. The first four blocks always correspond to the 64 558 DSCP values in consecutive order. If one or more of the blocks 559 are absent (e.g., for QoS values 0,1,2,3) the P[*] values for 560 the missing blocks default to "medium". 562 o Zero-padding added if necessary to produce an integral number of 8 563 octet blocks. 565 o Notification ID (present only if N = '1') contains the least- 566 significant 32 bits of an MSE OMNI LLA to notify (e.g., for the 567 LLA fe80::face:cafe the field contains 0xfacecafe). Valid only in 568 MN RS messages, and ignored in all other ND messages. 570 9. Address Mapping - Multicast 572 The multicast address mapping of the native underlying ANET interface 573 applies. The mobile router on board the aircraft also serves as an 574 IGMP/MLD Proxy for its EUNs and/or hosted applications per [RFC4605] 575 while using the L2 address of the router as the L2 address for all 576 multicast packets. 578 10. Address Mapping for IPv6 Neighbor Discovery Messages 580 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 581 unicast link-scoped IPv6 destination address. However, IPv6 ND 582 messaging is coordinated between the MN and MS only without invoking 583 other nodes on the ANET. 585 For this reason, ANET links maintain unicast L2 addresses ("MSADDR") 586 for the purpose of supporting MN/MS IPv6 ND messaging. For Ethernet- 587 compatible ANETs, this specification reserves one Ethernet unicast 588 address TBD2. For non-Ethernet statically-addressed ANETs, MSADDR is 589 reserved per the assigned numbers authority for the ANET addressing 590 space. For still other ANETs, MSADDR may be dynamically discovered 591 through other means, e.g., L2 beacons. 593 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 594 both multicast and unicast) to an MSADDR instead of to an ordinary 595 unicast or multicast L2 address. In this way, all of the MN's IPv6 596 ND messages will be received by MS devices that are configured to 597 accept packets destined to MSADDR. Note that multiple MS devices on 598 the link could be configured to accept packets destined to MSADDR, 599 e.g., as a basis for supporting redundancy. 601 Therefore, ARs MUST accept and process packets destined to MSADDR, 602 while all other devices MUST NOT process packets destined to MSADDR. 603 This model has well-established operational experience in Proxy 604 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 606 11. Conceptual Sending Algorithm 608 The MN's IPv6 layer selects the outbound OMNI interface according to 609 standard IPv6 requirements when forwarding data packets from local or 610 EUN applications to external correspondents. The OMNI interface 611 maintains default routes and neighbor cache entries for MSEs, and may 612 also include additional neighbor cache entries created through other 613 means (e.g., Address Resolution, static configuration, etc.). 615 After a packet enters the OMNI interface, an outbound ANET interface 616 is selected based on multilink parameters such as DSCP, application 617 port number, cost, performance, message size, etc. OMNI interface 618 multilink selections could also be configured to perform replication 619 across multiple ANET interfaces for increased reliability at the 620 expense of packet duplication. 622 OMNI interface multilink service designers MUST observe the BCP 623 guidance in Section 15 [RFC3819] in terms of implications for 624 reordering when packets from the same flow may be spread across 625 multiple ANET interfaces having diverse properties. 627 11.1. Multiple OMNI Interfaces 629 MNs may associate with multiple MS instances concurrently. Each MS 630 instance represents a distinct OMNI link distinguished by its 631 associated MSPs. The MN configures a separate OMNI interface for 632 each link so that multiple interfaces (e.g., omni0, omni1, omni2, 633 etc.) are exposed to the IPv6 layer. 635 Depending on local policy and configuration, an MN may choose between 636 alternative active OMNI interfaces using a packet's DSCP, routing 637 information or static configuration. Interface selection based on 638 per-packet source addresses is also enabled when the MSPs for each 639 OMNI interface are known (e.g., discovered through Prefix Information 640 Options (PIOs) and/or Route Information Options (RIOs)). 642 Each OMNI interface can be configured over the same or different sets 643 of ANET interfaces. Each ANET distinguishes between the different 644 OMNI links based on the MSPs represented in per-packet IPv6 645 addresses. 647 Multiple distinct OMNI links can therefore be used to support fault 648 tolerance, load balancing, reliability, etc. The architectural model 649 parallels Layer 2 Virtual Local Area Networks (VLANs), where the MSPs 650 serve as (virtual) VLAN tags. 652 12. Router Discovery and Prefix Registration 654 ARs process IPv6 ND messages destined to All-Routers multicast 655 (ff02::2), Subnet-Router anycast (fe80::) and unicast IPv6 LLAs 656 [RFC4291]. ARs configure the L2 address MSADDR (see: Section 10) and 657 act as a proxy for MSE OMNI LLAs. 659 MNs interface with the MS by sending RS messages with OMNI options. 660 For each ANET interface, the MN sends an RS message with an OMNI 661 option, with L2 destination address set to MSADDR and with L3 662 destination address set to either a specific MSE OMNI LLA, link-local 663 Subnet-Router anycast, or All-Routers multicast. The MN discovers 664 MSE OMNI LLAs either through an RA message response to an initial 665 anycast/multicast RS or before sending an initial RS message. 666 [RFC5214] provides example MSE address discovery methods, including 667 information conveyed during data link login, name service lookups, 668 static configuration, etc. 670 The AR receives the RS messages and coordinates with the 671 corresponding MSE in a manner outside the scope of this document. 672 The AR returns an RA message with source address set to the MSE OMNI 673 LLA, with an OMNI option and with any information for the link that 674 would normally be delivered in a solicited RA message. (Note that if 675 all MSEs share common state, the AR can instead return an RA with 676 source address set to link-local Subnet-Router anycast.) 678 MNs configure OMNI interfaces that observe the properties discussed 679 in the previous section. The OMNI interface and its underlying 680 interfaces are said to be in either the "UP" or "DOWN" state 681 according to administrative actions in conjunction with the interface 682 connectivity status. An OMNI interface transitions to UP or DOWN 683 through administrative action and/or through state transitions of the 684 underlying interfaces. When a first underlying interface transitions 685 to UP, the OMNI interface also transitions to UP. When all 686 underlying interfaces transition to DOWN, the OMNI interface also 687 transitions to DOWN. 689 When an OMNI interface transitions to UP, the MN sends initial RS 690 messages to register its MNP and an initial set of underlying ANET 691 interfaces that are also UP. The MN sends additional RS messages to 692 refresh lifetimes and to register/deregister underlying ANET 693 interfaces as they transition to UP or DOWN. 695 ARs return RA messages with configuration information in response to 696 a MN's RS messages. The RAs include a Router Lifetime value and any 697 necessary options, such as: 699 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 701 o RIOs [RFC4191] with more-specific routes. 703 o an MTU option that specifies the maximum acceptable packet size 704 for the OMNI link 706 The AR coordinates with the MSE and sends immediate unicast RA 707 responses without delay; therefore, the IPv6 ND MAX_RA_DELAY_TIME and 708 MIN_DELAY_BETWEEN_RAS constants for multicast RAs do not apply. The 709 AR MAY send periodic and/or event-driven unsolicited RA messages, but 710 is not required to do so for unicast advertisements [RFC4861]. 712 The MN sends RS messages from within the OMNI interface while using 713 an UP underlying ANET interface as the outbound interface. Each RS 714 message is formatted as though it originated from the IPv6 layer, but 715 the process is coordinated wholly from within the OMNI interface and 716 is therefore opaque to the IPv6 layer. The MN sends initial RS 717 messages over an UP underlying interface with its OMNI LLA as the 718 source and with destination set as discussed above. The RS messages 719 include an OMNI option per Section 8 with a valid Prefix Length, 720 (R,N,P) flags, and with ifIndex-tuples appropriate for underlying 721 ANET interfaces. The AR processes RS message and conveys the OMNI 722 option information to the MSE. 724 When the MSE processes the OMNI information, it first validates the 725 prefix registration information. If the prefix registration was 726 valid, the MSE injects the MNP into the routing/mapping system then 727 caches the new Prefix Length, MNP and ifIndex-tuples. If the MN's 728 OMNI option included a Notification ID, the new MSE also notifies the 729 former MSE. The MSE then directs the AR to return an RA message to 730 the MN with an OMNI option per Section 8 and with a non-zero Router 731 Lifetime if the prefix registration was successful; otherwise, with a 732 zero Router Lifetime. 734 When the MN receives the RA message, it creates a default route with 735 L3 next hop address set to the address found in the RA source address 736 and with L2 address set to MSADDR. The AR will then forward packets 737 between the MN and the MS. 739 The MN then manages its underlying ANET interfaces according to their 740 states as follows: 742 o When an underlying ANET interface transitions to UP, the MN sends 743 an RS over the ANET interface with an OMNI option. The OMNI 744 option contains a first ifIndex-tuple with values specific to this 745 ANET interface, and may contain additional ifIndex-tuples specific 746 to other ANET interfaces. 748 o When an underlying ANET interface transitions to DOWN, the MN 749 sends an RS or unsolicited NA message over any UP ANET interface 750 with an OMNI option containing an ifIndex-tuple for the DOWN ANET 751 interface with Link(i) set to '0'. The MN sends an RS when an 752 acknowledgement is required, or an unsolicited NA when reliability 753 is not thought to be a concern (e.g., if redundant transmissions 754 are sent on multiple ANET interfaces). 756 o When a MN wishes to release from a current MSE, it sends an RS or 757 unsolicited NA message over any UP ANET interfaces with an OMNI 758 option with R set to 0. The corresponding MSE then withdraws the 759 MNP from the routing/mapping system and (for RS responses) directs 760 the AR to return an RA message with an OMNI option and with Router 761 Lifetime set to 0. 763 o When a MN wishes to transition to a new MSE, it sends an RS or 764 unsolicited NA message over any UP ANET interfaces with an OMNI 765 option with R set to 1, with the new MSE OMNI LLA set in the 766 destination address, and (optionally) with N set to 1 and a 767 Notification ID included for the former MSE. 769 o When all of a MNs underlying interfaces have transitioned to DOWN 770 (or if the prefix registration lifetime expires) the MSE withdraws 771 the MNP the same as if it had received a message with an OMNI 772 option with R set to 0. 774 The MN is responsible for retrying each RS exchange up to 775 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 776 seconds until an RA is received. If no RA is received over multiple 777 UP ANET interfaces, the MN declares this MSE unreachable and tries a 778 different MSE. 780 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 781 Therefore, when the IPv6 layer sends an RS message the OMNI interface 782 returns an internally-generated RA message as though the message 783 originated from an IPv6 router. The internally-generated RA message 784 contains configuration information (such as Router Lifetime, MTU, 785 etc.) that is consistent with the information received from the RAs 786 generated by the MS. 788 Whether the OMNI interface IPv6 ND messaging process is initiated 789 from the receipt of an RS message from the IPv6 layer is an 790 implementation matter. Some implementations may elect to defer the 791 IPv6 ND messaging process until an RS is received from the IPv6 792 layer, while others may elect to initiate the process proactively. 794 Note: The Router Lifetime value in RA messages indicates the time 795 before which the MN must send another RS message over this underlying 796 interface (e.g., 600 seconds), however that timescale may be 797 significantly longer than the lifetime the MS has committed to retain 798 the prefix registration (e.g., REACHABLETIME seconds). For this 799 reason, the MN should select a primary AR, which is responsible for 800 keeping the MS prefix registration alive on the MN's behalf. If the 801 MN does not select a primary, then it must perform more frequent RS/ 802 RA exchanges on its own behalf to refresh the MS prefix registration 803 lifetime. 805 13. AR and MSE Resilience 807 ANETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 808 [RFC5798] configurations so that service continuity is maintained 809 even if one or more ARs fail. Using VRRP, the MN is unaware which of 810 the (redundant) ARs is currently providing service, and any service 811 discontinuity will be limited to the failover time supported by VRRP. 812 Widely deployed public domain implementations of VRRP are available. 814 MSEs SHOULD use high availability clustering services so that 815 multiple redundant systems can provide coordinated response to 816 failures. As with VRRP, widely deployed public domain 817 implementations of high availability clustering services are 818 available. Note that special-purpose and expensive dedicated 819 hardware is not necessary, and public domain implementations can be 820 used even between lightweight virtual machines in cloud deployments. 822 14. Detecting and Responding to MSE Failures 824 In environments where fast recovery from MSE failure is required, ARs 825 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 826 manner that parallels Bidirectional Forwarding Detection (BFD) 827 [RFC5880] to track MSE reachability. ARs can then quickly detect and 828 react to failures so that cached information is re-established 829 through alternate paths. Proactive NUD control messaging is carried 830 only over well-connected ground domain networks (i.e., and not low- 831 end aeronautical radio links) and can therefore be tuned for rapid 832 response. 834 ARs perform proactive NUD for MSEs for which there are currently 835 active ANET MNs. If an MSE fails, ARs can quickly inform MNs of the 836 outage by sending multicast RA messages on the ANET interface. The 837 AR sends RA messages to the MN via the ANET interface with source 838 address set to the MSEs OMNI LLA, destination address set to All- 839 Nodes multicast (ff02::1) [RFC4291], and Router Lifetime set to 0. 841 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 842 by small delays [RFC4861]. Any MNs on the ANET interface that have 843 been using the (now defunct) MSE will receive the RA messages and 844 associate with a new MSE. 846 15. IANA Considerations 848 The IANA is instructed to allocate an official Type number TBD from 849 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 850 option. Implementations set Type to 253 as an interim value 851 [RFC4727]. 853 The IANA is instructed to allocate one Ethernet unicast address TBD2 854 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 855 Address Block - Unicast Use". 857 16. Security Considerations 859 Security considerations for IPv6 [RFC8200] and IPv6 Neighbor 860 Discovery [RFC4861] apply. OMNI interface IPv6 ND messages SHOULD 861 include Nonce and Timestamp options [RFC3971] when synchronized 862 transaction confirmation is needed. 864 Security considerations for specific access network interface types 865 are covered under the corresponding IP-over-(foo) specification 866 (e.g., [RFC2464]). 868 17. Acknowledgements 870 The first version of this document was prepared per the consensus 871 decision at the 7th Conference of the International Civil Aviation 872 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 873 2019. Consensus to take the document forward to the IETF was reached 874 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 875 Attendees and contributors included: Guray Acar, Danny Bharj, 876 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 877 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 878 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 879 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 880 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 881 Fryderyk Wrobel and Dongsong Zeng. 883 The following individuals are acknowledged for their useful comments: 884 Pavel Drasil, Zdenek Jaron, Michael Matyas, Madhu Niraula, Greg 885 Saccone, Stephane Tamalet, Eric Vyncke. Naming of the IPv6 ND option 886 was discussed on the 6man mailing list. 888 This work is aligned with the NASA Safe Autonomous Systems Operation 889 (SASO) program under NASA contract number NNA16BD84C. 891 This work is aligned with the FAA as per the SE2025 contract number 892 DTFAWA-15-D-00030. 894 18. References 896 18.1. Normative References 898 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 899 Requirement Levels", BCP 14, RFC 2119, 900 DOI 10.17487/RFC2119, March 1997, 901 . 903 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 904 "Definition of the Differentiated Services Field (DS 905 Field) in the IPv4 and IPv6 Headers", RFC 2474, 906 DOI 10.17487/RFC2474, December 1998, 907 . 909 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 910 "SEcure Neighbor Discovery (SEND)", RFC 3971, 911 DOI 10.17487/RFC3971, March 2005, 912 . 914 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 915 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 916 November 2005, . 918 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 919 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 920 2006, . 922 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 923 ICMPv6, UDP, and TCP Headers", RFC 4727, 924 DOI 10.17487/RFC4727, November 2006, 925 . 927 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 928 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 929 DOI 10.17487/RFC4861, September 2007, 930 . 932 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 933 Address Autoconfiguration", RFC 4862, 934 DOI 10.17487/RFC4862, September 2007, 935 . 937 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 938 Hosts in a Multi-Prefix Network", RFC 8028, 939 DOI 10.17487/RFC8028, November 2016, 940 . 942 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 943 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 944 May 2017, . 946 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 947 (IPv6) Specification", STD 86, RFC 8200, 948 DOI 10.17487/RFC8200, July 2017, 949 . 951 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 952 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 953 DOI 10.17487/RFC8201, July 2017, 954 . 956 18.2. Informative References 958 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 959 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 960 . 962 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 963 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 964 . 966 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 967 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 968 December 1998, . 970 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 971 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 972 . 974 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 975 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 976 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 977 RFC 3819, DOI 10.17487/RFC3819, July 2004, 978 . 980 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 981 "Internet Group Management Protocol (IGMP) / Multicast 982 Listener Discovery (MLD)-Based Multicast Forwarding 983 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 984 August 2006, . 986 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 987 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 988 RFC 5213, DOI 10.17487/RFC5213, August 2008, 989 . 991 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 992 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 993 DOI 10.17487/RFC5214, March 2008, 994 . 996 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 997 Version 3 for IPv4 and IPv6", RFC 5798, 998 DOI 10.17487/RFC5798, March 2010, 999 . 1001 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 1002 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 1003 . 1005 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 1006 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 1007 2012, . 1009 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 1010 Requirements for IPv6 Customer Edge Routers", RFC 7084, 1011 DOI 10.17487/RFC7084, November 2013, 1012 . 1014 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 1015 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1016 Boundary in IPv6 Addressing", RFC 7421, 1017 DOI 10.17487/RFC7421, January 2015, 1018 . 1020 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 1021 Support for IP Hosts with Multi-Access Support", RFC 7847, 1022 DOI 10.17487/RFC7847, May 2016, 1023 . 1025 Appendix A. OMNI Option Extensions for Pseudo-DSCP Mappings 1027 Adaptation of the OMNI interface to specific Internetworks such as 1028 the Aeronautical Telecommunications Network with Internet Protocol 1029 Services (ATN/IPS) includes link selection preferences based on 1030 transport port numbers in addition to the existing DSCP-based 1031 preferences. ATN/IPS nodes maintain a map of transport port numbers 1032 to additional "pseudo-DSCP" P[*] preference fields beyond the first 1033 64. For example, TCP port 22 maps to pseudo-DSCP value P67, TCP port 1034 443 maps to P70, UDP port 8060 maps to P76, etc. Figure 4 shows an 1035 example OMNI option with extended P[*] values beyond the base 64 used 1036 for DSCP mapping (i.e., for QoS values 5 or greater): 1038 0 1 2 3 1039 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 1040 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1041 | Type | Length | Prefix Length |R|N|P| Reservd | 1042 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1043 | ifIndex | ifType | Flags | Link |QoS=5+ | 1044 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1045 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 1046 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1047 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 1048 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1049 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 1050 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1051 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1052 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1053 |P64|P65|P66|P67|P68|P69|P70|P71|P72|P73|P74|P75|P76|P77|P78|P79| 1054 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1055 ... 1057 Figure 4: ATN/IPS Extended OMNI Option Format 1059 Appendix B. Prefix Length Considerations 1061 The 64-bit boundary in IPv6 addresses [RFC7421] determines the MN 1062 OMNI LLA format for encoding the most-significant 64 MNP bits into 1063 the least-significant 64 bits of the prefix fe80::/64 as discussed in 1064 Section 7. 1066 [RFC4291] defines the link-local address format as the most 1067 significant 10 bits of the prefix fe80::/10, followed by 54 unused 1068 bits, followed by the least-significant 64 bits of the address. If 1069 the 64-bit boundary is relaxed through future standards activity, 1070 then the 54 unused bits can be employed for extended coding of MNPs 1071 of length /65 up to /118. 1073 The extended coding format would continue to encode MNP bits 0-63 in 1074 bits 64-127 of the OMNI LLA, while including MNP bits 64-117 in bits 1075 10-63. For example, the OMNI LLA corresponding to the MNP 1076 2001:db8:1111:2222:3333:4444:5555::/112 would be 1077 fe8c:ccd1:1115:5540:2001:db8:1111:2222, and would still be a valid 1078 IPv6 LLA per [RFC4291]. 1080 Appendix C. VDL Mode 2 Considerations 1082 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 1083 (VDLM2) that specifies an essential radio frequency data link service 1084 for aircraft and ground stations in worldwide civil aviation air 1085 traffic management. The VDLM2 link type is "multicast capable" 1086 [RFC4861], but with considerable differences from common multicast 1087 links such as Ethernet and IEEE 802.11. 1089 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 1090 magnitude less than most modern wireless networking gear. Second, 1091 due to the low available link bandwidth only VDLM2 ground stations 1092 (i.e., and not aircraft) are permitted to send broadcasts, and even 1093 so only as compact layer 2 "beacons". Third, aircraft employ the 1094 services of ground stations by performing unicast RS/RA exchanges 1095 upon receipt of beacons instead of listening for multicast RA 1096 messages and/or sending multicast RS messages. 1098 This beacon-oriented unicast RS/RA approach is necessary to conserve 1099 the already-scarce available link bandwidth. Moreover, since the 1100 numbers of beaconing ground stations operating within a given spatial 1101 range must be kept as sparse as possible, it would not be feasible to 1102 have different classes of ground stations within the same region 1103 observing different protocols. It is therefore highly desirable that 1104 all ground stations observe a common language of RS/RA as specified 1105 in this document. 1107 Note that links of this nature may benefit from compression 1108 techniques that reduce the bandwidth necessary for conveying the same 1109 amount of data. The IETF lpwan working group is considering possible 1110 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 1112 Appendix D. Change Log 1114 << RFC Editor - remove prior to publication >> 1116 Differences from draft-templin-atn-aero-interface-16 to draft- 1117 templin-atn-aero-interface-17: 1119 o New "Primary" flag in OMNI option. 1121 Differences from draft-templin-atn-aero-interface-15 to draft- 1122 templin-atn-aero-interface-16: 1124 o New note on MSE OMNI LLA uniqueness assurance. 1126 o General cleanup. 1128 Differences from draft-templin-atn-aero-interface-14 to draft- 1129 templin-atn-aero-interface-15: 1131 o General cleanup. 1133 Differences from draft-templin-atn-aero-interface-13 to draft- 1134 templin-atn-aero-interface-14: 1136 o General cleanup. 1138 Differences from draft-templin-atn-aero-interface-12 to draft- 1139 templin-atn-aero-interface-13: 1141 o Minor re-work on "Notify-MSE" (changed to Notification ID). 1143 Differences from draft-templin-atn-aero-interface-11 to draft- 1144 templin-atn-aero-interface-12: 1146 o Removed "Request/Response" OMNI option formats. Now, there is 1147 only one OMNI option format that applies to all ND messages. 1149 o Added new OMNI option field and supporting text for "Notify-MSE". 1151 Differences from draft-templin-atn-aero-interface-10 to draft- 1152 templin-atn-aero-interface-11: 1154 o Changed name from "aero" to "OMNI" 1156 o Resolved AD review comments from Eric Vyncke (posted to atn list) 1158 Differences from draft-templin-atn-aero-interface-09 to draft- 1159 templin-atn-aero-interface-10: 1161 o Renamed ARO option to AERO option 1163 o Re-worked Section 13 text to discuss proactive NUD. 1165 Differences from draft-templin-atn-aero-interface-08 to draft- 1166 templin-atn-aero-interface-09: 1168 o Version and reference update 1170 Differences from draft-templin-atn-aero-interface-07 to draft- 1171 templin-atn-aero-interface-08: 1173 o Removed "Classic" and "MS-enabled" link model discussion 1175 o Added new figure for MN/AR/MSE model. 1177 o New Section on "Detecting and responding to MSE failure". 1179 Differences from draft-templin-atn-aero-interface-06 to draft- 1180 templin-atn-aero-interface-07: 1182 o Removed "nonce" field from AR option format. Applications that 1183 require a nonce can include a standard nonce option if they want 1184 to. 1186 o Various editorial cleanups. 1188 Differences from draft-templin-atn-aero-interface-05 to draft- 1189 templin-atn-aero-interface-06: 1191 o New Appendix C on "VDL Mode 2 Considerations" 1193 o New Appendix D on "RS/RA Messaging as a Single Standard API" 1195 o Various significant updates in Section 5, 10 and 12. 1197 Differences from draft-templin-atn-aero-interface-04 to draft- 1198 templin-atn-aero-interface-05: 1200 o Introduced RFC6543 precedent for focusing IPv6 ND messaging to a 1201 reserved unicast link-layer address 1203 o Introduced new IPv6 ND option for Aero Registration 1205 o Specification of MN-to-MSE message exchanges via the ANET access 1206 router as a proxy 1208 o IANA Considerations updated to include registration requests and 1209 set interim RFC4727 option type value. 1211 Differences from draft-templin-atn-aero-interface-03 to draft- 1212 templin-atn-aero-interface-04: 1214 o Removed MNP from aero option format - we already have RIOs and 1215 PIOs, and so do not need another option type to include a Prefix. 1217 o Clarified that the RA message response must include an aero option 1218 to indicate to the MN that the ANET provides a MS. 1220 o MTU interactions with link adaptation clarified. 1222 Differences from draft-templin-atn-aero-interface-02 to draft- 1223 templin-atn-aero-interface-03: 1225 o Sections re-arranged to match RFC4861 structure. 1227 o Multiple aero interfaces 1229 o Conceptual sending algorithm 1231 Differences from draft-templin-atn-aero-interface-01 to draft- 1232 templin-atn-aero-interface-02: 1234 o Removed discussion of encapsulation (out of scope) 1236 o Simplified MTU section 1238 o Changed to use a new IPv6 ND option (the "aero option") instead of 1239 S/TLLAO 1241 o Explained the nature of the interaction between the mobility 1242 management service and the air interface 1244 Differences from draft-templin-atn-aero-interface-00 to draft- 1245 templin-atn-aero-interface-01: 1247 o Updates based on list review comments on IETF 'atn' list from 1248 4/29/2019 through 5/7/2019 (issue tracker established) 1250 o added list of opportunities afforded by the single virtual link 1251 model 1253 o added discussion of encapsulation considerations to Section 6 1255 o noted that DupAddrDetectTransmits is set to 0 1256 o removed discussion of IPv6 ND options for prefix assertions. The 1257 aero address already includes the MNP, and there are many good 1258 reasons for it to continue to do so. Therefore, also including 1259 the MNP in an IPv6 ND option would be redundant. 1261 o Significant re-work of "Router Discovery" section. 1263 o New Appendix B on Prefix Length considerations 1265 First draft version (draft-templin-atn-aero-interface-00): 1267 o Draft based on consensus decision of ICAO Working Group I Mobility 1268 Subgroup March 22, 2019. 1270 Authors' Addresses 1272 Fred L. Templin (editor) 1273 The Boeing Company 1274 P.O. Box 3707 1275 Seattle, WA 98124 1276 USA 1278 Email: fltemplin@acm.org 1280 Tony Whyman 1281 MWA Ltd c/o Inmarsat Global Ltd 1282 99 City Road 1283 London EC1Y 1AX 1284 England 1286 Email: tony.whyman@mccallumwhyman.com