idnits 2.17.1 draft-templin-atn-aero-interface-18.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 6, 2020) is 1512 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 457 -- Looks like a reference, but probably isn't: '2' on line 467 == Missing Reference: 'N' is mentioned on line 479, but not defined == Unused Reference: 'RFC2225' is defined on line 962, 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 9, 2020 MWA Ltd c/o Inmarsat Global Ltd 6 February 6, 2020 8 Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) 9 Interfaces 10 draft-templin-atn-aero-interface-18 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 9, 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 (including the OMNI interface's underlying ANET 362 interfaces) MUST configure an MTU of at least 1280 bytes [RFC8200]. 364 The OMNI interface configures an MTU of 9180 bytes (i.e., the same as 365 specified in [RFC2492]) noting that this size may be larger than the 366 MTUs of any underlying ANET interfaces. The size is therefore not a 367 reflection of the underlying physical media, but rather the maximum 368 amount that the OMNI link will ever need to reassemble. 370 The OMNI interface returns internally-generated IPv6 Path MTU 371 Discovery (PMTUD) Packet Too Big (PTB) messages [RFC8201] for packets 372 admitted into the interface that are too large for the outbound 373 underlying ANET interface. For all other packets, the OMNI interface 374 performs PMTUD even if the destination appears to be on the same link 375 since a proxy on the path could return a PTB message; this ensures 376 that the path MTU is adaptive and reflects the current path used for 377 a given data flow. 379 Applications that cannot tolerate loss due to MTU restrictions SHOULD 380 refrain from sending packets larger than 1280 bytes, since dynamic 381 path changes can reduce the path MTU at any time. Applications that 382 may benefit from sending larger packets even though the path MTU may 383 change dynamically MAY use larger sizes. 385 6. Frame Format 387 The OMNI interface transmits IPv6 packets according to the native 388 frame format of each underlying ANET interface. For example, for 389 Ethernet-compatible interfaces the frame format is specified in 390 [RFC2464], for aeronautical radio interfaces the frame format is 391 specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical 392 Manual), for tunnels over IPv6 the frame format is specified in 393 [RFC2473], etc. 395 7. Link-Local Addresses 397 OMNI interfaces assign IPv6 Link-Local Addresses (i.e., "OMNI LLAs") 398 using the following constructs: 400 o IPv6 MN OMNI LLAs encode the most-significant 64 bits of a MNP 401 within the least-significant 64 bits (i.e., the interface ID) of a 402 Link-Local IPv6 Unicast Address (see: [RFC4291], Section 2.5.6). 403 For example, for the MNP 2001:db8:1000:2000::/56 the corresponding 404 LLA is fe80::2001:db8:1000:2000. 406 o IPv4-compatible MN OMNI LLAs are assigned as fe80::ffff:[v4addr], 407 i.e., the most significant 10 bits of the prefix fe80::/10, 408 followed by 70 '0' bits, followed by 16 '1' bits, followed by a 409 32bit IPv4 address. For example, the IPv4-Compatible MN OMNI LLA 410 for 192.0.2.1 is fe80::ffff:192.0.2.1 (also written as 411 fe80::ffff:c000:0201). 413 o MSE OMNI LLAs are assigned from the range fe80::/96, and MUST be 414 managed for uniqueness. The lower 32 bits of the LLA includes a 415 unique integer value between '1' and 'fffffffe', e.g., as in 416 fe80::1, fe80::2, fe80::3, etc., fe80::ffff:fffe. The address 417 fe80:: is the link-local Subnet-Router anycast address [RFC4291] 418 and the address fe80::ffff:ffff is reserved. (Note that distinct 419 OMNI link segments can avoid overlap by assignig MSE OMNI LLAs 420 from unique fe80::/96 sub-prefixes. For example, a first segment 421 could assign from fe80::1000/116, a second from fe80::2000/116, a 422 third from fe80::3000/116, etc.) 424 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 425 MNPs can be allocated from that block ensuring that there is no 426 possibility for overlap between the above OMNI LLA constructs. 428 Since MN OMNI LLAs are based on the distribution of administratively 429 assured unique MNPs, and since MSE OMNI LLAs are guaranteed unique 430 through administrative assignment, OMNI interfaces set the 431 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 433 8. Address Mapping - Unicast 435 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 436 state and use the link-local address format specified in Section 7. 437 IPv6 Neighbor Discovery (ND) [RFC4861] messages on MN OMNI interfaces 438 observe the native Source/Target Link-Layer Address Option (S/TLLAO) 439 formats of the underlying ANET interfaces (e.g., for Ethernet the S/ 440 TLLAO is specified in [RFC2464]). 442 MNs such as aircraft typically have many wireless data link types 443 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 444 etc.) with diverse performance, cost and availability properties. 445 The OMNI interface would therefore appear to have multiple L2 446 connections, and may include information for multiple ANET interfaces 447 in a single IPv6 ND message exchange. 449 OMNI interfaces use an IPv6 ND option called the "OMNI option" 450 formatted as shown in Figure 3: 452 0 1 2 3 453 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 1 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 | Type | Length | Prefix Length |R|N|P| Reservd | 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 | ifIndex[1] | ifType[1] | Reserved [1] |Link[1]|QoS[1] | 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 459 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 461 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 463 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 467 | ifIndex[2] | ifType[2] | Reserved [2] |Link[2]|QoS[2] | 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 469 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 471 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 472 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 473 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 474 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 475 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 ... ... ... 478 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 | ifIndex[N] | ifType[N] | Reserved [N] |Link[N]|QoS[N] | 480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 481 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 485 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 487 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 488 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 489 | zero-padding (if necessary) | 490 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 491 | Notification ID (present only if N=1) | 492 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 Figure 3: OMNI Option Format 496 In this format: 498 o Type is set to TBD. 500 o Length is set to the number of 8 octet blocks in the option. 502 o Prefix Length is set according to the IPv6 source LLA type. For 503 MN OMNI LLAs, the value is set to the length of the embedded MNP. 504 For MSE OMNI LLAs, the value is set to 128. 506 o R (the "Register/Release" bit) is set to '1' to register an MNP or 507 set to '0' to release a registration. 509 o N (the "Notify" bit) is set to '1' if the option includes a 510 trailing 4 byte "Notification ID" (see below). Valid only in MN 511 RS messages, and ignored in all other ND messages. 513 o P (the "Primary" bit) is set to '1' in a MN RS message to request 514 an AR to serve as primary, and set to '1' in the AR's RA message 515 to accept the primary role. Set to '0' in all other RS/RA 516 messages, and ignored in all other ND messages. 518 o Reservd is set to the value '0' on transmission and ignored on 519 reception. 521 o A set of N ANET interface "ifIndex-tuples" are included as 522 follows: 524 * ifIndex[i] is set to an 8-bit integer value corresponding to a 525 specific underlying ANET interface. The first ifIndex-tuple 526 MUST correspond to the ANET interface over which the message is 527 sent. IPv6 ND messages originating from a MN may include 528 multiple ifIndex-tuples, and MUST number each with a distinct 529 ifIndex value between '1' and '255' that represents a MN- 530 specific 8-bit mapping for the actual ifIndex value assigned to 531 the ANET interface by network management [RFC2863]. IPv6 ND 532 messages originating from the MS include a single ifIndex-tuple 533 with ifIndex set to the value '0'. 535 * ifType[i] is set to an 8-bit integer value corresponding to the 536 underlying ANET interface identified by ifIndex. The value 537 represents an OMNI interface-specific 8-bit mapping for the 538 actual IANA ifType value registered in the 'IANAifType-MIB' 539 registry [http://www.iana.org]. 541 * Reserved[i] is set to the value '0' on transmission and ignored 542 on reception. 544 * Link[i] encodes a 4-bit link metric. The value '0' means the 545 link is DOWN, and the remaining values mean the link is UP with 546 metric ranging from '1' ("lowest") to '15' ("highest"). 548 * QoS[i] encodes the number of 4-byte blocks (between '0' and 549 '15') of two-bit P[*] values that follow. The first 4 blocks 550 correspond to the 64 Differentiated Service Code Point (DSCP) 551 values P00 - P63 [RFC2474]. If additional 4-byte P[i] blocks 552 follow, their values correspond to "pseudo-DSCP" values P64, 553 P65, P66, etc. numbered consecutively. The pseudo-DSCP values 554 correspond to ancillary QoS information defined for the 555 specific OMNI interface (e.g., see Appendix A). 557 * P[*] includes zero or more per-ifIndex 4-byte blocks of two-bit 558 Preferences. Each P[*] field is set to the value '0' 559 ("disabled"), '1' ("low"), '2' ("medium") or '3' ("high") to 560 indicate a QoS preference level for ANET interface selection 561 purposes. The first four blocks always correspond to the 64 562 DSCP values in consecutive order. If one or more of the blocks 563 are absent (e.g., for QoS values 0,1,2,3) the P[*] values for 564 the missing blocks default to "medium". 566 o Zero-padding added if necessary to produce an integral number of 8 567 octet blocks. 569 o Notification ID (present only if N = '1') contains the least- 570 significant 32 bits of an MSE OMNI LLA to notify (e.g., for the 571 LLA fe80::face:cafe the field contains 0xfacecafe). Valid only in 572 MN RS messages, and ignored in all other ND messages. 574 9. Address Mapping - Multicast 576 The multicast address mapping of the native underlying ANET interface 577 applies. The mobile router on board the aircraft also serves as an 578 IGMP/MLD Proxy for its EUNs and/or hosted applications per [RFC4605] 579 while using the L2 address of the router as the L2 address for all 580 multicast packets. 582 10. Address Mapping for IPv6 Neighbor Discovery Messages 584 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 585 unicast link-scoped IPv6 destination address. However, IPv6 ND 586 messaging is coordinated between the MN and MS only without invoking 587 other nodes on the ANET. 589 For this reason, ANET links maintain unicast L2 addresses ("MSADDR") 590 for the purpose of supporting MN/MS IPv6 ND messaging. For Ethernet- 591 compatible ANETs, this specification reserves one Ethernet unicast 592 address TBD2. For non-Ethernet statically-addressed ANETs, MSADDR is 593 reserved per the assigned numbers authority for the ANET addressing 594 space. For still other ANETs, MSADDR may be dynamically discovered 595 through other means, e.g., L2 beacons. 597 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 598 both multicast and unicast) to an MSADDR instead of to an ordinary 599 unicast or multicast L2 address. In this way, all of the MN's IPv6 600 ND messages will be received by MS devices that are configured to 601 accept packets destined to MSADDR. Note that multiple MS devices on 602 the link could be configured to accept packets destined to MSADDR, 603 e.g., as a basis for supporting redundancy. 605 Therefore, ARs MUST accept and process packets destined to MSADDR, 606 while all other devices MUST NOT process packets destined to MSADDR. 607 This model has well-established operational experience in Proxy 608 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 610 11. Conceptual Sending Algorithm 612 The MN's IPv6 layer selects the outbound OMNI interface according to 613 standard IPv6 requirements when forwarding data packets from local or 614 EUN applications to external correspondents. The OMNI interface 615 maintains default routes and neighbor cache entries for MSEs, and may 616 also include additional neighbor cache entries created through other 617 means (e.g., Address Resolution, static configuration, etc.). 619 After a packet enters the OMNI interface, an outbound ANET interface 620 is selected based on multilink parameters such as DSCP, application 621 port number, cost, performance, message size, etc. OMNI interface 622 multilink selections could also be configured to perform replication 623 across multiple ANET interfaces for increased reliability at the 624 expense of packet duplication. 626 OMNI interface multilink service designers MUST observe the BCP 627 guidance in Section 15 [RFC3819] in terms of implications for 628 reordering when packets from the same flow may be spread across 629 multiple ANET interfaces having diverse properties. 631 11.1. Multiple OMNI Interfaces 633 MNs may associate with multiple MS instances concurrently. Each MS 634 instance represents a distinct OMNI link distinguished by its 635 associated MSPs. The MN configures a separate OMNI interface for 636 each link so that multiple interfaces (e.g., omni0, omni1, omni2, 637 etc.) are exposed to the IPv6 layer. 639 Depending on local policy and configuration, an MN may choose between 640 alternative active OMNI interfaces using a packet's DSCP, routing 641 information or static configuration. Interface selection based on 642 per-packet source addresses is also enabled when the MSPs for each 643 OMNI interface are known (e.g., discovered through Prefix Information 644 Options (PIOs) and/or Route Information Options (RIOs)). 646 Each OMNI interface can be configured over the same or different sets 647 of ANET interfaces. Each ANET distinguishes between the different 648 OMNI links based on the MSPs represented in per-packet IPv6 649 addresses. 651 Multiple distinct OMNI links can therefore be used to support fault 652 tolerance, load balancing, reliability, etc. The architectural model 653 parallels Layer 2 Virtual Local Area Networks (VLANs), where the MSPs 654 serve as (virtual) VLAN tags. 656 12. Router Discovery and Prefix Registration 658 ARs process IPv6 ND messages destined to All-Routers multicast 659 (ff02::2), Subnet-Router anycast (fe80::) and unicast IPv6 LLAs 660 [RFC4291]. ARs configure the L2 address MSADDR (see: Section 10) and 661 act as a proxy for MSE OMNI LLAs. 663 MNs interface with the MS by sending RS messages with OMNI options. 664 For each ANET interface, the MN sends an RS message with an OMNI 665 option, with L2 destination address set to MSADDR and with L3 666 destination address set to either a specific MSE OMNI LLA, link-local 667 Subnet-Router anycast, or All-Routers multicast. The MN discovers 668 MSE OMNI LLAs either through an RA message response to an initial 669 anycast/multicast RS or before sending an initial RS message. 670 [RFC5214] provides example MSE address discovery methods, including 671 information conveyed during data link login, name service lookups, 672 static configuration, etc. 674 The AR receives the RS messages and coordinates with the 675 corresponding MSE in a manner outside the scope of this document. 676 The AR returns an RA message with source address set to the MSE OMNI 677 LLA, with an OMNI option and with any information for the link that 678 would normally be delivered in a solicited RA message. (Note that if 679 all MSEs share common state, the AR can instead return an RA with 680 source address set to link-local Subnet-Router anycast.) 682 MNs configure OMNI interfaces that observe the properties discussed 683 in the previous section. The OMNI interface and its underlying 684 interfaces are said to be in either the "UP" or "DOWN" state 685 according to administrative actions in conjunction with the interface 686 connectivity status. An OMNI interface transitions to UP or DOWN 687 through administrative action and/or through state transitions of the 688 underlying interfaces. When a first underlying interface transitions 689 to UP, the OMNI interface also transitions to UP. When all 690 underlying interfaces transition to DOWN, the OMNI interface also 691 transitions to DOWN. 693 When an OMNI interface transitions to UP, the MN sends initial RS 694 messages to register its MNP and an initial set of underlying ANET 695 interfaces that are also UP. The MN sends additional RS messages to 696 refresh lifetimes and to register/deregister underlying ANET 697 interfaces as they transition to UP or DOWN. 699 ARs return RA messages with configuration information in response to 700 a MN's RS messages. The AR sets the RA Cur Hop Limit, M and O flags, 701 Router Lifetime, Reachable Time and Retrans Timer values as directed 702 by the MSE, and includes any necessary options such as: 704 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 706 o RIOs [RFC4191] with more-specific routes. 708 o an MTU option that specifies the maximum acceptable packet size 709 for this ANET interface. 711 The AR coordinates with the MSE and sends immediate unicast RA 712 responses without delay; therefore, the IPv6 ND MAX_RA_DELAY_TIME and 713 MIN_DELAY_BETWEEN_RAS constants for multicast RAs do not apply. The 714 AR MAY send periodic and/or event-driven unsolicited RA messages, but 715 is not required to do so for unicast advertisements [RFC4861]. 717 The MN sends RS messages from within the OMNI interface while using 718 an UP underlying ANET interface as the outbound interface. Each RS 719 message is formatted as though it originated from the IPv6 layer, but 720 the process is coordinated wholly from within the OMNI interface and 721 is therefore opaque to the IPv6 layer. The MN sends initial RS 722 messages over an UP underlying interface with its OMNI LLA as the 723 source and with destination set as discussed above. The RS messages 724 include an OMNI option per Section 8 with a valid Prefix Length, 725 (R,N,P) flags, and with ifIndex-tuples appropriate for underlying 726 ANET interfaces. The AR processes RS message and conveys the OMNI 727 option information to the MSE. 729 When the MSE processes the OMNI information, it first validates the 730 prefix registration information. If the prefix registration was 731 valid, the MSE injects the MNP into the routing/mapping system then 732 caches the new Prefix Length, MNP and ifIndex-tuples. If the MN's 733 OMNI option included a Notification ID, the new MSE also notifies the 734 former MSE. The MSE then directs the AR to return an RA message to 735 the MN with an OMNI option per Section 8 and with a non-zero Router 736 Lifetime if the prefix registration was successful; otherwise, with a 737 zero Router Lifetime. 739 When the MN receives the RA message, it creates a default route with 740 L3 next hop address set to the address found in the RA source address 741 and with L2 address set to MSADDR. The AR will then forward packets 742 between the MN and the MS. 744 The MN then manages its underlying ANET interfaces according to their 745 states as follows: 747 o When an underlying ANET interface transitions to UP, the MN sends 748 an RS over the ANET interface with an OMNI option. The OMNI 749 option contains a first ifIndex-tuple with values specific to this 750 ANET interface, and may contain additional ifIndex-tuples specific 751 to other ANET interfaces. 753 o When an underlying ANET interface transitions to DOWN, the MN 754 sends an RS or unsolicited NA message over any UP ANET interface 755 with an OMNI option containing an ifIndex-tuple for the DOWN ANET 756 interface with Link(i) set to '0'. The MN sends an RS when an 757 acknowledgement is required, or an unsolicited NA when reliability 758 is not thought to be a concern (e.g., if redundant transmissions 759 are sent on multiple ANET interfaces). 761 o When a MN wishes to release from a current MSE, it sends an RS or 762 unsolicited NA message over any UP ANET interfaces with an OMNI 763 option with R set to 0. The corresponding MSE then withdraws the 764 MNP from the routing/mapping system and (for RS responses) directs 765 the AR to return an RA message with an OMNI option and with Router 766 Lifetime set to 0. 768 o When a MN wishes to transition to a new MSE, it sends an RS or 769 unsolicited NA message over any UP ANET interfaces with an OMNI 770 option with R set to 1, with the new MSE OMNI LLA set in the 771 destination address, and (optionally) with N set to 1 and a 772 Notification ID included for the former MSE. 774 o When all of a MNs underlying interfaces have transitioned to DOWN 775 (or if the prefix registration lifetime expires) the MSE withdraws 776 the MNP the same as if it had received a message with an OMNI 777 option with R set to 0. 779 The MN is responsible for retrying each RS exchange up to 780 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 781 seconds until an RA is received. If no RA is received over multiple 782 UP ANET interfaces, the MN declares this MSE unreachable and tries a 783 different MSE. 785 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 786 Therefore, when the IPv6 layer sends an RS message the OMNI interface 787 returns an internally-generated RA message as though the message 788 originated from an IPv6 router. The internally-generated RA message 789 contains configuration information that is consistent with the 790 information received from the RAs generated by the MS. 792 Whether the OMNI interface IPv6 ND messaging process is initiated 793 from the receipt of an RS message from the IPv6 layer is an 794 implementation matter. Some implementations may elect to defer the 795 IPv6 ND messaging process until an RS is received from the IPv6 796 layer, while others may elect to initiate the process proactively. 798 Note: The Router Lifetime value in RA messages indicates the time 799 before which the MN must send another RS message over this underlying 800 interface (e.g., 600 seconds), however that timescale may be 801 significantly longer than the lifetime the MS has committed to retain 802 the prefix registration (e.g., REACHABLETIME seconds). For this 803 reason, the MN should select a primary AR, which is responsible for 804 keeping the MS prefix registration alive on the MN's behalf. If the 805 MN does not select a primary, then it must perform more frequent RS/ 806 RA exchanges on its own behalf to refresh the MS prefix registration 807 lifetime. 809 13. AR and MSE Resilience 811 ANETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 812 [RFC5798] configurations so that service continuity is maintained 813 even if one or more ARs fail. Using VRRP, the MN is unaware which of 814 the (redundant) ARs is currently providing service, and any service 815 discontinuity will be limited to the failover time supported by VRRP. 816 Widely deployed public domain implementations of VRRP are available. 818 MSEs SHOULD use high availability clustering services so that 819 multiple redundant systems can provide coordinated response to 820 failures. As with VRRP, widely deployed public domain 821 implementations of high availability clustering services are 822 available. Note that special-purpose and expensive dedicated 823 hardware is not necessary, and public domain implementations can be 824 used even between lightweight virtual machines in cloud deployments. 826 14. Detecting and Responding to MSE Failures 828 In environments where fast recovery from MSE failure is required, ARs 829 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 830 manner that parallels Bidirectional Forwarding Detection (BFD) 831 [RFC5880] to track MSE reachability. ARs can then quickly detect and 832 react to failures so that cached information is re-established 833 through alternate paths. Proactive NUD control messaging is carried 834 only over well-connected ground domain networks (i.e., and not low- 835 end aeronautical radio links) and can therefore be tuned for rapid 836 response. 838 ARs perform proactive NUD for MSEs for which there are currently 839 active ANET MNs. If an MSE fails, ARs can quickly inform MNs of the 840 outage by sending multicast RA messages on the ANET interface. The 841 AR sends RA messages to the MN via the ANET interface with source 842 address set to the MSEs OMNI LLA, destination address set to All- 843 Nodes multicast (ff02::1) [RFC4291], and Router Lifetime set to 0. 845 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 846 by small delays [RFC4861]. Any MNs on the ANET interface that have 847 been using the (now defunct) MSE will receive the RA messages and 848 associate with a new MSE. 850 15. IANA Considerations 852 The IANA is instructed to allocate an official Type number TBD from 853 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 854 option. Implementations set Type to 253 as an interim value 855 [RFC4727]. 857 The IANA is instructed to allocate one Ethernet unicast address TBD2 858 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 859 Address Block - Unicast Use". 861 16. Security Considerations 863 Security considerations for IPv6 [RFC8200] and IPv6 Neighbor 864 Discovery [RFC4861] apply. OMNI interface IPv6 ND messages SHOULD 865 include Nonce and Timestamp options [RFC3971] when synchronized 866 transaction confirmation is needed. 868 Security considerations for specific access network interface types 869 are covered under the corresponding IP-over-(foo) specification 870 (e.g., [RFC2464], [RFC2492], etc.). 872 17. Acknowledgements 874 The first version of this document was prepared per the consensus 875 decision at the 7th Conference of the International Civil Aviation 876 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 877 2019. Consensus to take the document forward to the IETF was reached 878 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 879 Attendees and contributors included: Guray Acar, Danny Bharj, 880 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 881 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 882 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 883 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 884 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 885 Fryderyk Wrobel and Dongsong Zeng. 887 The following individuals are acknowledged for their useful comments: 888 Pavel Drasil, Zdenek Jaron, Michael Matyas, Madhu Niraula, Greg 889 Saccone, Stephane Tamalet, Eric Vyncke. Naming of the IPv6 ND option 890 was discussed on the 6man mailing list. 892 This work is aligned with the NASA Safe Autonomous Systems Operation 893 (SASO) program under NASA contract number NNA16BD84C. 895 This work is aligned with the FAA as per the SE2025 contract number 896 DTFAWA-15-D-00030. 898 18. References 900 18.1. Normative References 902 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 903 Requirement Levels", BCP 14, RFC 2119, 904 DOI 10.17487/RFC2119, March 1997, 905 . 907 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 908 "Definition of the Differentiated Services Field (DS 909 Field) in the IPv4 and IPv6 Headers", RFC 2474, 910 DOI 10.17487/RFC2474, December 1998, 911 . 913 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 914 "SEcure Neighbor Discovery (SEND)", RFC 3971, 915 DOI 10.17487/RFC3971, March 2005, 916 . 918 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 919 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 920 November 2005, . 922 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 923 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 924 2006, . 926 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 927 ICMPv6, UDP, and TCP Headers", RFC 4727, 928 DOI 10.17487/RFC4727, November 2006, 929 . 931 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 932 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 933 DOI 10.17487/RFC4861, September 2007, 934 . 936 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 937 Address Autoconfiguration", RFC 4862, 938 DOI 10.17487/RFC4862, September 2007, 939 . 941 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 942 Hosts in a Multi-Prefix Network", RFC 8028, 943 DOI 10.17487/RFC8028, November 2016, 944 . 946 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 947 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 948 May 2017, . 950 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 951 (IPv6) Specification", STD 86, RFC 8200, 952 DOI 10.17487/RFC8200, July 2017, 953 . 955 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 956 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 957 DOI 10.17487/RFC8201, July 2017, 958 . 960 18.2. Informative References 962 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 963 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 964 . 966 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 967 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 968 . 970 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 971 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 972 December 1998, . 974 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 975 Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999, 976 . 978 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 979 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 980 . 982 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 983 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 984 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 985 RFC 3819, DOI 10.17487/RFC3819, July 2004, 986 . 988 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 989 "Internet Group Management Protocol (IGMP) / Multicast 990 Listener Discovery (MLD)-Based Multicast Forwarding 991 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 992 August 2006, . 994 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 995 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 996 RFC 5213, DOI 10.17487/RFC5213, August 2008, 997 . 999 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 1000 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 1001 DOI 10.17487/RFC5214, March 2008, 1002 . 1004 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 1005 Version 3 for IPv4 and IPv6", RFC 5798, 1006 DOI 10.17487/RFC5798, March 2010, 1007 . 1009 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 1010 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 1011 . 1013 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 1014 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 1015 2012, . 1017 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 1018 Requirements for IPv6 Customer Edge Routers", RFC 7084, 1019 DOI 10.17487/RFC7084, November 2013, 1020 . 1022 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 1023 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1024 Boundary in IPv6 Addressing", RFC 7421, 1025 DOI 10.17487/RFC7421, January 2015, 1026 . 1028 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 1029 Support for IP Hosts with Multi-Access Support", RFC 7847, 1030 DOI 10.17487/RFC7847, May 2016, 1031 . 1033 Appendix A. OMNI Option Extensions for Pseudo-DSCP Mappings 1035 Adaptation of the OMNI interface to specific Internetworks such as 1036 the Aeronautical Telecommunications Network with Internet Protocol 1037 Services (ATN/IPS) includes link selection preferences based on 1038 transport port numbers in addition to the existing DSCP-based 1039 preferences. ATN/IPS nodes maintain a map of transport port numbers 1040 to additional "pseudo-DSCP" P[*] preference fields beyond the first 1041 64. For example, TCP port 22 maps to pseudo-DSCP value P67, TCP port 1042 443 maps to P70, UDP port 8060 maps to P76, etc. Figure 4 shows an 1043 example OMNI option with extended P[*] values beyond the base 64 used 1044 for DSCP mapping (i.e., for QoS values 5 or greater): 1046 0 1 2 3 1047 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 1048 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1049 | Type | Length | Prefix Length |R|N|P| Reservd | 1050 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1051 | ifIndex | ifType | Flags | Link |QoS=5+ | 1052 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1053 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 1054 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1055 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 1056 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1057 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 1058 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1059 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1060 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1061 |P64|P65|P66|P67|P68|P69|P70|P71|P72|P73|P74|P75|P76|P77|P78|P79| 1062 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1063 ... 1065 Figure 4: ATN/IPS Extended OMNI Option Format 1067 Appendix B. Prefix Length Considerations 1069 The 64-bit boundary in IPv6 addresses [RFC7421] determines the MN 1070 OMNI LLA format for encoding the most-significant 64 MNP bits into 1071 the least-significant 64 bits of the prefix fe80::/64 as discussed in 1072 Section 7. 1074 [RFC4291] defines the link-local address format as the most 1075 significant 10 bits of the prefix fe80::/10, followed by 54 unused 1076 bits, followed by the least-significant 64 bits of the address. If 1077 the 64-bit boundary is relaxed through future standards activity, 1078 then the 54 unused bits can be employed for extended coding of MNPs 1079 of length /65 up to /118. 1081 The extended coding format would continue to encode MNP bits 0-63 in 1082 bits 64-127 of the OMNI LLA, while including MNP bits 64-117 in bits 1083 10-63. For example, the OMNI LLA corresponding to the MNP 1084 2001:db8:1111:2222:3333:4444:5555::/112 would be 1085 fe8c:ccd1:1115:5540:2001:db8:1111:2222, and would still be a valid 1086 IPv6 LLA per [RFC4291]. 1088 Appendix C. VDL Mode 2 Considerations 1090 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 1091 (VDLM2) that specifies an essential radio frequency data link service 1092 for aircraft and ground stations in worldwide civil aviation air 1093 traffic management. The VDLM2 link type is "multicast capable" 1094 [RFC4861], but with considerable differences from common multicast 1095 links such as Ethernet and IEEE 802.11. 1097 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 1098 magnitude less than most modern wireless networking gear. Second, 1099 due to the low available link bandwidth only VDLM2 ground stations 1100 (i.e., and not aircraft) are permitted to send broadcasts, and even 1101 so only as compact layer 2 "beacons". Third, aircraft employ the 1102 services of ground stations by performing unicast RS/RA exchanges 1103 upon receipt of beacons instead of listening for multicast RA 1104 messages and/or sending multicast RS messages. 1106 This beacon-oriented unicast RS/RA approach is necessary to conserve 1107 the already-scarce available link bandwidth. Moreover, since the 1108 numbers of beaconing ground stations operating within a given spatial 1109 range must be kept as sparse as possible, it would not be feasible to 1110 have different classes of ground stations within the same region 1111 observing different protocols. It is therefore highly desirable that 1112 all ground stations observe a common language of RS/RA as specified 1113 in this document. 1115 Note that links of this nature may benefit from compression 1116 techniques that reduce the bandwidth necessary for conveying the same 1117 amount of data. The IETF lpwan working group is considering possible 1118 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 1120 Appendix D. Change Log 1122 << RFC Editor - remove prior to publication >> 1124 Differences from draft-templin-atn-aero-interface-17 to draft- 1125 templin-atn-aero-interface-18: 1127 o MTU and RA configuration information updated. 1129 Differences from draft-templin-atn-aero-interface-16 to draft- 1130 templin-atn-aero-interface-17: 1132 o New "Primary" flag in OMNI option. 1134 Differences from draft-templin-atn-aero-interface-15 to draft- 1135 templin-atn-aero-interface-16: 1137 o New note on MSE OMNI LLA uniqueness assurance. 1139 o General cleanup. 1141 Differences from draft-templin-atn-aero-interface-14 to draft- 1142 templin-atn-aero-interface-15: 1144 o General cleanup. 1146 Differences from draft-templin-atn-aero-interface-13 to draft- 1147 templin-atn-aero-interface-14: 1149 o General cleanup. 1151 Differences from draft-templin-atn-aero-interface-12 to draft- 1152 templin-atn-aero-interface-13: 1154 o Minor re-work on "Notify-MSE" (changed to Notification ID). 1156 Differences from draft-templin-atn-aero-interface-11 to draft- 1157 templin-atn-aero-interface-12: 1159 o Removed "Request/Response" OMNI option formats. Now, there is 1160 only one OMNI option format that applies to all ND messages. 1162 o Added new OMNI option field and supporting text for "Notify-MSE". 1164 Differences from draft-templin-atn-aero-interface-10 to draft- 1165 templin-atn-aero-interface-11: 1167 o Changed name from "aero" to "OMNI" 1168 o Resolved AD review comments from Eric Vyncke (posted to atn list) 1170 Differences from draft-templin-atn-aero-interface-09 to draft- 1171 templin-atn-aero-interface-10: 1173 o Renamed ARO option to AERO option 1175 o Re-worked Section 13 text to discuss proactive NUD. 1177 Differences from draft-templin-atn-aero-interface-08 to draft- 1178 templin-atn-aero-interface-09: 1180 o Version and reference update 1182 Differences from draft-templin-atn-aero-interface-07 to draft- 1183 templin-atn-aero-interface-08: 1185 o Removed "Classic" and "MS-enabled" link model discussion 1187 o Added new figure for MN/AR/MSE model. 1189 o New Section on "Detecting and responding to MSE failure". 1191 Differences from draft-templin-atn-aero-interface-06 to draft- 1192 templin-atn-aero-interface-07: 1194 o Removed "nonce" field from AR option format. Applications that 1195 require a nonce can include a standard nonce option if they want 1196 to. 1198 o Various editorial cleanups. 1200 Differences from draft-templin-atn-aero-interface-05 to draft- 1201 templin-atn-aero-interface-06: 1203 o New Appendix C on "VDL Mode 2 Considerations" 1205 o New Appendix D on "RS/RA Messaging as a Single Standard API" 1207 o Various significant updates in Section 5, 10 and 12. 1209 Differences from draft-templin-atn-aero-interface-04 to draft- 1210 templin-atn-aero-interface-05: 1212 o Introduced RFC6543 precedent for focusing IPv6 ND messaging to a 1213 reserved unicast link-layer address 1215 o Introduced new IPv6 ND option for Aero Registration 1216 o Specification of MN-to-MSE message exchanges via the ANET access 1217 router as a proxy 1219 o IANA Considerations updated to include registration requests and 1220 set interim RFC4727 option type value. 1222 Differences from draft-templin-atn-aero-interface-03 to draft- 1223 templin-atn-aero-interface-04: 1225 o Removed MNP from aero option format - we already have RIOs and 1226 PIOs, and so do not need another option type to include a Prefix. 1228 o Clarified that the RA message response must include an aero option 1229 to indicate to the MN that the ANET provides a MS. 1231 o MTU interactions with link adaptation clarified. 1233 Differences from draft-templin-atn-aero-interface-02 to draft- 1234 templin-atn-aero-interface-03: 1236 o Sections re-arranged to match RFC4861 structure. 1238 o Multiple aero interfaces 1240 o Conceptual sending algorithm 1242 Differences from draft-templin-atn-aero-interface-01 to draft- 1243 templin-atn-aero-interface-02: 1245 o Removed discussion of encapsulation (out of scope) 1247 o Simplified MTU section 1249 o Changed to use a new IPv6 ND option (the "aero option") instead of 1250 S/TLLAO 1252 o Explained the nature of the interaction between the mobility 1253 management service and the air interface 1255 Differences from draft-templin-atn-aero-interface-00 to draft- 1256 templin-atn-aero-interface-01: 1258 o Updates based on list review comments on IETF 'atn' list from 1259 4/29/2019 through 5/7/2019 (issue tracker established) 1261 o added list of opportunities afforded by the single virtual link 1262 model 1264 o added discussion of encapsulation considerations to Section 6 1266 o noted that DupAddrDetectTransmits is set to 0 1268 o removed discussion of IPv6 ND options for prefix assertions. The 1269 aero address already includes the MNP, and there are many good 1270 reasons for it to continue to do so. Therefore, also including 1271 the MNP in an IPv6 ND option would be redundant. 1273 o Significant re-work of "Router Discovery" section. 1275 o New Appendix B on Prefix Length considerations 1277 First draft version (draft-templin-atn-aero-interface-00): 1279 o Draft based on consensus decision of ICAO Working Group I Mobility 1280 Subgroup March 22, 2019. 1282 Authors' Addresses 1284 Fred L. Templin (editor) 1285 The Boeing Company 1286 P.O. Box 3707 1287 Seattle, WA 98124 1288 USA 1290 Email: fltemplin@acm.org 1292 Tony Whyman 1293 MWA Ltd c/o Inmarsat Global Ltd 1294 99 City Road 1295 London EC1Y 1AX 1296 England 1298 Email: tony.whyman@mccallumwhyman.com