idnits 2.17.1 draft-templin-atn-aero-interface-14.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (January 29, 2020) is 1549 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 446 -- Looks like a reference, but probably isn't: '2' on line 456 == Missing Reference: 'N' is mentioned on line 468, but not defined == Unused Reference: 'RFC2225' is defined on line 932, 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 1, 2020 MWA Ltd c/o Inmarsat Global Ltd 6 January 29, 2020 8 Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) 9 Interfaces 10 draft-templin-atn-aero-interface-14 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 1, 2020. 40 Copyright Notice 42 Copyright (c) 2020 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5 60 4. Overlay Multilink Network Interface (OMNI) Model . . . . . . 5 61 5. Maximum Transmission Unit . . . . . . . . . . . . . . . . . . 9 62 6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 9 63 7. Link-Local Addresses . . . . . . . . . . . . . . . . . . . . 9 64 8. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 10 65 9. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 13 66 10. Address Mapping for IPv6 Neighbor Discovery Messages . . . . 13 67 11. Conceptual Sending Algorithm . . . . . . . . . . . . . . . . 14 68 11.1. Multiple OMNI Interfaces . . . . . . . . . . . . . . . . 14 69 12. Router Discovery and Prefix Registration . . . . . . . . . . 15 70 13. AR and MSE Resilience . . . . . . . . . . . . . . . . . . . . 18 71 14. Detecting and Responding to MSE Failures . . . . . . . . . . 18 72 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 73 16. Security Considerations . . . . . . . . . . . . . . . . . . . 19 74 17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 75 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 76 18.1. Normative References . . . . . . . . . . . . . . . . . . 19 77 18.2. Informative References . . . . . . . . . . . . . . . . . 21 78 Appendix A. OMNI Option Extensions for Pseudo-DSCP Mappings . . 22 79 Appendix B. Prefix Length Considerations . . . . . . . . . . . . 23 80 Appendix C. VDL Mode 2 Considerations . . . . . . . . . . . . . 23 81 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 24 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 84 1. Introduction 86 Mobile Nodes (MNs) (e.g., aircraft of various configurations, 87 terrestrial vehicles, seagoing vessels, mobile enterprise devices, 88 etc.) often have multiple data links for communicating with networked 89 correspondents. These data links may have diverse performance, cost 90 and availability characteristics that can change dynamically 91 according to mobility patterns, flight phases, proximity to 92 infrastructure, etc. MNs coordinate their data links in a discipline 93 known as "multilink", in which a single virtual interface is 94 configured over the underlying data link interfaces. 96 The MN configures a virtual interface (termed the "Overlay Multilink 97 Network (OMNI) interface") as a thin layer over the underlying access 98 network interfaces. The OMNI interface is therefore the only 99 interface abstraction exposed to the IPv6 layer and behaves according 100 to the Non-Broadcast, Multiple Access (NBMA) interface principle, 101 while underlying access network interfaces appear as link layer 102 communication channels in the architecture. The OMNI interface 103 connects to a virtual overlay service known as the "OMNI link". The 104 OMNI link spans a worldwide Internetwork that may include private-use 105 infrastructures and/or the global public Internet itself. 107 Each MN receives a Mobile Network Prefix (MNP) for numbering End User 108 Networks (EUNs) independently of the access network data links 109 selected for data transport. The MN performs router discovery over 110 the OMNI interface (i.e., similar to IPv6 customer edge routers 111 [RFC7084]) and acts as a mobile router on behalf of its EUNs. The 112 router discovery process is iterated over each of the OMNI 113 interface's underlying access network data links in order to register 114 per-link parameters (see Section 12). 116 The OMNI interface provides a multilink nexus for guiding inbound and 117 outbound traffic to the correct underlying Access Network (ANET) 118 interface(s). The IPv6 layer sees the OMNI interface as a point of 119 connection to the OMNI link. Each OMNI link has one or more 120 associated Mobility Service Prefixes (MSPs) from which OMNI link MNPs 121 are derived. If there are multiple OMNI links, the IPv6 layer will 122 see multiple OMNI interfaces. 124 The OMNI interface interacts with an Internetwork Mobility Service 125 (MS) through IPv6 Neighbor Discovery (ND) control message exchanges 126 [RFC4861]. The MS provides Mobility Service Endpoints (MSEs) that 127 track MN movements and represent their MNPs in a global routing or 128 mapping system. 130 This document specifies the transmission of IPv6 packets [RFC8200] 131 and MN/MS control messaging over OMNI interfaces. 133 2. Terminology 135 The terminology in the normative references applies; especially, the 136 terms "link" and "interface" are the same as defined in the IPv6 137 [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications. 138 Also, the Protocol Constants defined in Section 10 of [RFC4861] are 139 used in their same format and meaning in this document. 141 The following terms are defined within the scope of this document: 143 Mobile Node (MN) 144 an end system with multiple distinct data link connections that 145 are managed together as a single logical unit. The MN's data link 146 connection parameters can change over time due to, e.g., node 147 mobility, link quality, etc. The MN further connects a 148 downstream-attached End User Network (EUN). The term MN used here 149 is distinct from uses in other documents, and does not imply a 150 particular mobility protocol. 152 End User Network (EUN) 153 a simple or complex mobile network that travels with the MN as a 154 single logical unit. The IPv6 addresses assigned to EUN devices 155 remain stable even if the MN's data link connections change. 157 Mobility Service (MS) 158 a mobile routing service that tracks MN movements and ensures that 159 MNs remain continuously reachable even across mobility events. 160 Specific MS details are out of scope for this document. 162 Mobility Service Prefix (MSP) 163 an aggregated IPv6 prefix (e.g., 2001:db8::/32) advertised to the 164 rest of the Internetwork by the MS, and from which more-specific 165 Mobile Network Prefixes (MNPs) are derived. 167 Mobile Network Prefix (MNP) 168 a longer IPv6 prefix taken from the MSP (e.g., 169 2001:db8:1000:2000::/56) and assigned to a MN. MNs sub-delegate 170 the MNP to devices located in EUNs. 172 Access Network (ANET) 173 a data link service network (e.g., an aviation radio access 174 network, satellite service provider network, cellular operator 175 network, etc.) that provides an Access Router (AR) for connecting 176 MNs to correspondents in outside Internetworks. Physical and/or 177 data link level security between the MN and AR are assumed. 179 ANET interface 180 a MN's attachment to a link in an ANET. 182 Internetwork (INET) 183 a connected network region with a coherent IP addressing plan that 184 provides transit forwarding services for ANET MNs and INET 185 correspondents. Examples include private enterprise networks, 186 ground domain aviation service networks and the global public 187 Internet itself. 189 INET interface 190 a node's attachment to a link in an INET. 192 OMNI link 193 a virtual overlay configured over one or more INETs and their 194 connected ANETs. An OMNI link can comprise multiple INET segments 195 joined by bridges the same as for any link; the addressing plans 196 in each segment may be mutually exclusive and managed by different 197 administrative entities. 199 OMNI interface 200 a node's attachment to an OMNI link, and configured over one or 201 more underlying ANET/INET interfaces. 203 OMNI link local address (LLA) 204 an IPv6 link-local address constructed as specified in Section 7, 205 and assigned to an OMNI interface. 207 Multilink 208 an OMNI interface's manner of managing diverse underlying data 209 link interfaces as a single logical unit. The OMNI interface 210 provides a single unified interface to upper layers, while 211 underlying data link selections are performed on a per-packet 212 basis considering factors such as DSCP, flow label, application 213 policy, signal quality, cost, etc. Multilinking decisions are 214 coordinated in both the outbound (i.e. MN to correspondent) and 215 inbound (i.e., correspondent to MN) directions. 217 L2 218 The second layer in the OSI network model. Also known as "layer- 219 2", "link-layer", "sub-IP layer", "data link layer", etc. 221 L3 222 The third layer in the OSI network model. Also known as "layer- 223 3", "network-layer", "IPv6 layer", etc. 225 3. Requirements 227 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 228 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 229 "OPTIONAL" in this document are to be interpreted as described in BCP 230 14 [RFC2119][RFC8174] when, and only when, they appear in all 231 capitals, as shown here. 233 4. Overlay Multilink Network Interface (OMNI) Model 235 An OMNI interface is a MN virtual interface configured over one or 236 more ANET interfaces, which may be physical (e.g., an aeronautical 237 radio link) or virtual (e.g., an Internet or higher-layer "tunnel"). 238 The MN receives a MNP from the MS, and coordinates with the MS 239 through IPv6 ND message exchanges. The MN uses the MNP to construct 240 a unique OMNI LLA through the algorithmic derivation specified in 241 Section 7 and assigns the LLA to the OMNI interface. 243 The OMNI interface architectural layering model is the same as in 244 [RFC7847], and augmented as shown in Figure 1. The IP layer (L3) 245 therefore sees the OMNI interface as a single network layer interface 246 with multiple underlying ANET interfaces that appear as L2 247 communication channels in the architecture. 249 +----------------------------+ 250 | Upper Layer Protocol | 251 Session-to-IP +---->| | 252 Address Binding | +----------------------------+ 253 +---->| IP (L3) | 254 IP Address +---->| | 255 Binding | +----------------------------+ 256 +---->| OMNI Interface | 257 Logical-to- +---->| (OMNI LLA) | 258 Physical | +----------------------------+ 259 Interface +---->| L2 | L2 | | L2 | 260 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 261 +------+------+ +------+ 262 | L1 | L1 | | L1 | 263 | | | | | 264 +------+------+ +------+ 266 Figure 1: OMNI Interface Architectural Layering Model 268 The OMNI virtual interface model gives rise to a number of 269 opportunities: 271 o since OMNI LLAs are uniquely derived from an MNP, no Duplicate 272 Address Detection (DAD) messaging is necessary over the OMNI 273 interface. 275 o ANET interfaces do not require any L3 addresses (i.e., not even 276 link-local) in environments where communications are coordinated 277 entirely over the OMNI interface. 279 o as ANET interface properties change (e.g., link quality, cost, 280 availability, etc.), any active ANET interface can be used to 281 update the profiles of multiple additional ANET interfaces in a 282 single message. This allows for timely adaptation and service 283 continuity under dynamically changing conditions. 285 o coordinating ANET interfaces in this way allows them to be 286 represented in a unified MS profile with provisions for mobility 287 and multilink operations. 289 o exposing a single virtual interface abstraction to the IPv6 layer 290 allows for multilink operation (including QoS based link 291 selection, packet replication, load balancing, etc.) at L2 while 292 still permitting queuing at the L3 based on, e.g., DSCP, flow 293 label, etc. 295 o L3 sees the OMNI interface as a point of connection to the OMNI 296 link; if there are multiple OMNI links (i.e., multiple MS's), L3 297 will see multiple OMNI interfaces. 299 Other opportunities are discussed in [RFC7847]. 301 Figure 2 depicts the architectural model for a MN connecting to the 302 MS via multiple independent ANETs. When an ANET interface becomes 303 active, the MN sends native (i.e., unencapsulated) IPv6 ND messages 304 via the underlying ANET interface. IPv6 ND messages traverse the 305 ground domain ANETs until they reach an Access Router (AR#1, AR#2, 306 .., AR#n). The AR then coordinates with a Mobility Service Endpoint 307 (MSE#1, MSE#2, ..., MSE#m) in the INET and returns an IPv6 ND message 308 response to the MN. IPv6 ND messages traverse the ANET at layer 2; 309 hence, the Hop Limit is not decremented. 311 +--------------+ 312 | MN | 313 +--------------+ 314 |OMNI interface| 315 +----+----+----+ 316 +--------|IF#1|IF#2|IF#n|------ + 317 / +----+----+----+ \ 318 / | \ 319 / <---- Native | IP ----> \ 320 v v v 321 (:::)-. (:::)-. (:::)-. 322 .-(::ANET:::) .-(::ANET:::) .-(::ANET:::) 323 `-(::::)-' `-(::::)-' `-(::::)-' 324 +----+ +----+ +----+ 325 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 326 . +-|--+ +-|--+ +-|--+ . 327 . | | | 328 . v v v . 329 . <----- Encapsulation -----> . 330 . . 331 . +-----+ (:::)-. . 332 . |MSE#2| .-(::::::::) +-----+ . 333 . +-----+ .-(::: INET :::)-. |MSE#m| . 334 . (::::: Routing ::::) +-----+ . 335 . `-(::: System :::)-' . 336 . +-----+ `-(:::::::-' . 337 . |MSE#1| +-----+ +-----+ . 338 . +-----+ |MSE#3| |MSE#4| . 339 . +-----+ +-----+ . 340 . . 341 . . 342 . <----- Worldwide Connected Internetwork ----> . 343 ........................................................... 345 Figure 2: MN/MS Coordination via Multiple ANETs 347 After the initial IPv6 ND message exchange, the MN can send and 348 receive unencapsulated IPv6 data packets over the OMNI interface. 349 OMNI interface multilink services will forward the packets via ARs in 350 the correct underlying ANETs. The AR encapsulates the packets 351 according to the capabilities provided by the MS and forwards them to 352 the next hop within the worldwide connected Internetwork via optimal 353 routes. 355 5. Maximum Transmission Unit 357 All IPv6 interfaces MUST configure an MTU of at least 1280 bytes 358 [RFC8200]. The OMNI interface configures its MTU based on the 359 largest MTU among all underlying ANET interfaces. The value MAY be 360 overridden if an RA message with an MTU option is received. 362 The OMNI interface returns internally-generated IPv6 Path MTU 363 Discovery (PMTUD) Packet Too Big (PTB) messages [RFC8201] for packets 364 admitted into the OMNI interface that are too large for the outbound 365 underlying ANET interface. Similarly, the OMNI interface performs 366 PMTUD even if the destination appears to be on the same link since a 367 proxy on the path could return a PTB message. PMTUD therefore 368 ensures that the OMNI interface MTU is adaptive and reflects the 369 current path used for a given data flow. 371 Applications that cannot tolerate loss due to MTU restrictions SHOULD 372 refrain from sending packets larger than 1280 bytes, since dynamic 373 path changes can reduce the path MTU at any time. Applications that 374 may benefit from sending larger packets even though the path MTU may 375 change dynamically MAY use larger sizes. 377 6. Frame Format 379 The OMNI interface transmits IPv6 packets according to the native 380 frame format of each underlying ANET interface. For example, for 381 Ethernet-compatible interfaces the frame format is specified in 382 [RFC2464], for aeronautical radio interfaces the frame format is 383 specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical 384 Manual), for tunnels over IPv6 the frame format is specified in 385 [RFC2473], etc. 387 7. Link-Local Addresses 389 OMNI interfaces assign IPv6 Link-Local Addresses (i.e., "OMNI LLAs") 390 using the following constructs: 392 o MN OMNI LLAs encode the most-significant 64 bits of a MNP within 393 the least-significant 64 bits (i.e., the interface ID) of a Link- 394 Local IPv6 Unicast Address (see: [RFC4291], Section 2.5.6). For 395 example, for the MNP 2001:db8:1000:2000::/56 the corresponding LLA 396 is fe80::2001:db8:1000:2000. 398 o MSE OMNI LLAs are allocated from the range fe80::/96, and MUST be 399 managed for uniqueness by the collective OMNI link administrative 400 authorities. The lower 32 bits of the LLA includes a unique 401 integer value between '1' and 'fffffffe', e.g., as in fe80::1, 402 fe80::2, fe80::3, etc., fe80::ffff:fffe. The address fe80:: is 403 the IPv6 link-local Subnet Router Anycast address [RFC4291] and 404 the address fe80::ffff:ffff is reserved. 406 o IPv4-compatible MN OMNI LLAs are allocated 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 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 414 MNPs can be allocated from that block ensuring that there is no 415 possibility for overlap between the different OMNI LLA constructs. 417 Since MN OMNI LLAs are based on the distribution of administratively 418 assured unique MNPs, and since MSE OMNI LLAs are guaranteed unique 419 through administrative assignment, OMNI interfaces set the 420 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 422 8. Address Mapping - Unicast 424 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 425 state and use the link-local address format specified in Section 7. 426 IPv6 Neighbor Discovery (ND) [RFC4861] messages on MN OMNI interfaces 427 observe the native Source/Target Link-Layer Address Option (S/TLLAO) 428 formats of the underlying ANET interfaces (e.g., for Ethernet the S/ 429 TLLAO is specified in [RFC2464]). 431 MNs such as aircraft typically have many wireless data link types 432 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 433 etc.) with diverse performance, cost and availability properties. 434 The OMNI interface would therefore appear to have multiple L2 435 connections, and may include information for multiple ANET interfaces 436 in a single IPv6 ND message exchange. 438 OMNI interfaces use an IPv6 ND option called the "OMNI option" 439 formatted as shown in Figure 3: 441 0 1 2 3 442 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 1 443 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 444 | Type | Length | Prefix Length |R|N| Reserved | 445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 446 | ifIndex[1] | ifType[1] | Reserved [1] |Link[1]|QoS[1] | 447 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 448 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 449 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 450 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 451 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 452 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 455 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 456 | ifIndex[2] | ifType[2] | Reserved [2] |Link[2]|QoS[2] | 457 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 458 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 459 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 460 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 461 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 462 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 463 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 464 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 465 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 466 ... ... ... 467 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 468 | ifIndex[N] | ifType[N] | Reserved [N] |Link[N]|QoS[N] | 469 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 470 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 471 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 472 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 474 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 476 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 477 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 478 | zero-padding (if necessary) | 479 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 480 | Notification ID (present only if N=1) | 481 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 Figure 3: OMNI Option Format 485 In this format: 487 o Type is set to TBD. 489 o Length is set to the number of 8 octet blocks in the option. 491 o Prefix Length is set according to the IPv6 source LLA type. For 492 MN OMNI LLAs, the value is set to the length of the embedded MNP. 493 For MSE OMNI LLAs, the value is set to 128. 495 o R (the "Register" bit) is set to '1' to assert MNP registration or 496 set to '0' to cancel MNP registration. 498 o N (the "Notify" bit) is set to '1' if the option includes a 499 trailing 4 byte "Notification ID" (see below); set to '0' 500 otherwise. 502 o Reserved is set to the value '0' on transmission and ignored on 503 reception. 505 o A set of N ANET interface "ifIndex-tuples" are included as 506 follows: 508 * ifIndex[i] is set to an 8-bit integer value corresponding to a 509 specific underlying ANET interface. The first ifIndex-tuple 510 MUST correspond to the ANET interface over which the message is 511 sent. IPv6 ND messages originating from a MN may include 512 multiple ifIndex-tuples, and MUST number each ifIndex with a 513 distinct value between '1' and '255' that represents a MN- 514 specific 8-bit mapping for the actual ifIndex value assigned to 515 the ANET interface by network management [RFC2863]. IPv6 ND 516 messages originating from the MS include a single ifIndex-tuple 517 with ifIndex set to the value '0'. 519 * ifType[i] is set to an 8-bit integer value corresponding to the 520 underlying ANET interface identified by ifIndex. The value 521 represents an OMNI interface-specific 8-bit mapping for the 522 actual IANA ifType value registered in the 'IANAifType-MIB' 523 registry [http://www.iana.org]. 525 * Reserved[i] is set to the value '0' on transmission and ignored 526 on reception. 528 * Link[i] encodes a 4-bit link metric. The value '0' means the 529 link is DOWN, and the remaining values mean the link is UP with 530 metric ranging from '1' ("lowest") to '15' ("highest"). 532 * QoS[i] encodes the number of 4-byte blocks (between '0' and 533 '15') of two-bit P[*] values that follow. The first 4 blocks 534 correspond to the 64 Differentiated Service Code Point (DSCP) 535 values P00 - P63 [RFC2474]. If additional 4-byte P[i] blocks 536 follow, their values correspond to "pseudo-DSCP" values P64, 537 P65, P66, etc. numbered consecutively. The pseudo-DSCP values 538 correspond to ancillary QoS information defined for the 539 specific OMNI interface (e.g., see Appendix A). 541 * P[*] includes zero or more per-ifIndex 4-byte blocks of two-bit 542 Preferences. Each P[*] field is set to the value '0' 543 ("disabled"), '1' ("low"), '2' ("medium") or '3' ("high") to 544 indicate a QoS preference level for ANET interface selection 545 purposes. The first four blocks always correspond to the 64 546 DSCP values in consecutive order. If one or more of the blocks 547 are absent (e.g., for QoS values 0,1,2,3) the P[*] values for 548 the missing blocks default to "medium". 550 o Zero-padding added if necessary to produce an integral number of 8 551 octet blocks. 553 o Notification ID (present only if N = '1') contains the least- 554 significant 32 bits of an MSE OMNI LLA to notify. For example, 555 for the LLA fe80::face:cafe the field contains 0xfacecafe. 557 9. Address Mapping - Multicast 559 The multicast address mapping of the native underlying ANET interface 560 applies. The mobile router on board the aircraft also serves as an 561 IGMP/MLD Proxy for its EUNs and/or hosted applications per [RFC4605] 562 while using the L2 address of the router as the L2 address for all 563 multicast packets. 565 10. Address Mapping for IPv6 Neighbor Discovery Messages 567 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 568 unicast link-scoped IPv6 destination address. However, IPv6 ND 569 messaging is coordinated between the MN and MS only without invoking 570 other nodes on the ANET. 572 For this reason, ANET links maintain unicast L2 addresses ("MSADDR") 573 for the purpose of supporting MN/MS IPv6 ND messaging. For Ethernet- 574 compatible ANETs, this specification reserves one Ethernet unicast 575 address TBD2. For non-Ethernet statically-addressed ANETs, MSADDR is 576 reserved per the assigned numbers authority for the ANET addressing 577 space. For still other ANETs, MSADDR may be dynamically discovered 578 through other means, e.g., L2 beacons. 580 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 581 both multicast and unicast) to an MSADDR instead of to an ordinary 582 unicast or multicast L2 address. In this way, all of the MN's IPv6 583 ND messages will be received by MS devices that are configured to 584 accept packets destined to MSADDR. Note that multiple MS devices on 585 the link could be configured to accept packets destined to MSADDR, 586 e.g., as a basis for supporting redundancy. 588 Therefore, ARs MUST accept and process packets destined to MSADDR, 589 while all other devices MUST NOT process packets destined to MSADDR. 590 This model has well-established operational experience in Proxy 591 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 593 11. Conceptual Sending Algorithm 595 The MN's IPv6 layer selects the outbound OMNI interface according to 596 standard IPv6 requirements when forwarding data packets from local or 597 EUN applications to external correspondents. The OMNI interface 598 maintains default routes and neighbor cache entries for MSEs, and may 599 also include additional neighbor cache entries created through other 600 means (e.g., Address Resolution, static configuration, etc.). 602 After a packet enters the OMNI interface, an outbound ANET interface 603 is selected based on multilink parameters such as DSCP, application 604 port number, cost, performance, message size, etc. OMNI interface 605 multilink selections could also be configured to perform replication 606 across multiple ANET interfaces for increased reliability at the 607 expense of packet duplication. 609 OMNI interface multilink service designers MUST observe the BCP 610 guidance in Section 15 [RFC3819] in terms of implications for 611 reordering when packets from the same flow may be spread across 612 multiple ANET interfaces having diverse properties. 614 11.1. Multiple OMNI Interfaces 616 MNs may associate with multiple MS instances concurrently. Each MS 617 instance represents a distinct OMNI link distinguished by its 618 associated MSPs. The MN configures a separate OMNI interface for 619 each link so that multiple interfaces (e.g., omni0, omni1, omni2, 620 etc.) are exposed to the IPv6 layer. 622 Depending on local policy and configuration, an MN may choose between 623 alternative active OMNI interfaces using a packet's DSCP, routing 624 information or static configuration. Interface selection based on 625 per-packet source addresses is also enabled when the MSPs for each 626 OMNI interface are known (e.g., discovered through Prefix Information 627 Options (PIOs) and/or Route Information Options (RIOs)). 629 Each OMNI interface can be configured over the same or different sets 630 of ANET interfaces. Each ANET distinguishes between the different 631 OMNI links based on the MSPs represented in per-packet IPv6 632 addresses. 634 Multiple distinct OMNI links can therefore be used to support fault 635 tolerance, load balancing, reliability, etc. The architectural model 636 parallels Layer 2 Virtual Local Area Networks (VLANs), where the MSPs 637 serve as (virtual) VLAN tags. 639 12. Router Discovery and Prefix Registration 641 ARs process IPv6 ND messages destined to all-routers multicast 642 (ff02::2), the subnet router anycast LLA (fe80::) and unicast IPv6 643 LLAs. ARs configure the L2 address MSADDR (see: Section 10) and act 644 as a proxy for MSE OMNI LLAs. 646 MNs interface with the MS by sending RS messages with OMNI options. 647 For each ANET interface, the MN sends an RS message with an OMNI 648 option, with L2 destination address set to MSADDR and with L3 649 destination address set to either a specific MSE OMNI LLA, subnet 650 router anycast LLA, or all-routers multicast. The MN discovers MSE 651 OMNI LLAs either through an RA message response to an initial 652 anycast/multicast RS or before sending an initial RS message. 653 [RFC5214] provides example MSE address discovery methods, including 654 information conveyed during data link login, name service lookups, 655 static configuration, etc. 657 The AR receives the RS messages and coordinates with the 658 corresponding MSE in a manner outside the scope of this document. 659 The AR returns an RA message with source address set to the MSE OMNI 660 LLA, with an OMNI option and with any information for the link that 661 would normally be delivered in a solicited RA message. (Note that if 662 all MSEs share common state, the AR can instead return an RA with 663 source address set to the subnet router anycast LLA.) 665 MNs configure OMNI interfaces that observe the properties discussed 666 in the previous section. The OMNI interface and its underlying 667 interfaces are said to be in either the "UP" or "DOWN" state 668 according to administrative actions in conjunction with the interface 669 connectivity status. An OMNI interface transitions to UP or DOWN 670 through administrative action and/or through state transitions of the 671 underlying interfaces. When a first underlying interface transitions 672 to UP, the OMNI interface also transitions to UP. When all 673 underlying interfaces transition to DOWN, the OMNI interface also 674 transitions to DOWN. 676 When an OMNI interface transitions to UP, the MN sends initial RS 677 messages to register its MNP and an initial set of underlying ANET 678 interfaces that are also UP. The MN sends additional RS messages to 679 refresh lifetimes and to register/deregister underlying ANET 680 interfaces as they transition to UP or DOWN. 682 ARs return RA messages with configuration information in response to 683 a MN's RS messages. The RAs include a Router Lifetime value and any 684 necessary options, such as: 686 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 688 o RIOs [RFC4191] with more-specific routes. 690 o an MTU option that specifies the maximum acceptable packet size 691 for the OMNI link 693 The AR coordinates with the MSE and sends immediate unicast RA 694 responses without delay; therefore, the IPv6 ND MAX_RA_DELAY_TIME and 695 MIN_DELAY_BETWEEN_RAS constants for multicast RAs do not apply. The 696 AR MAY send periodic and/or event-driven unsolicited RA messages, but 697 is not required to do so for unicast advertisements [RFC4861]. 699 The MN sends RS messages from within the OMNI interface while using 700 an UP underlying ANET interface as the outbound interface. Each RS 701 message is formatted as though it originated from the IPv6 layer, but 702 the process is coordinated wholly from within the OMNI interface and 703 is therefore opaque to the IPv6 layer. The MN sends initial RS 704 messages over an UP underlying interface with its OMNI LLA as the 705 source. The RS messages include an OMNI option with a valid Prefix 706 Length as well as ifIndex-tuples appropriate for underlying ANET 707 interfaces. The AR processes RS message and conveys the OMNI option 708 information to the MSE. 710 When the MSE processes the OMNI information, if the prefix 711 registration was accepted the MSE injects the MNP into the routing/ 712 mapping system then caches the new Prefix Length, MNP and ifIndex- 713 tuples. The MSE then directs the AR to return an RA message to the 714 MN with an OMNI option and with a non-zero Router Lifetime if the 715 prefix assertion was acceptable; otherwise, with a zero Router 716 Lifetime. If the MN's OMNI option included a Notification ID, the 717 new MSE also notifies the former MSE (with reliable confirmation). 719 When the MN receives the RA message, it creates a default route with 720 L3 next hop address set to the address found in the RA source address 721 and with L2 address set to MSADDR. The AR will then forward packets 722 between the MN and the MS. 724 The MN then manages its underlying ANET interfaces according to their 725 states as follows: 727 o When an underlying ANET interface transitions to UP, the MN sends 728 an RS over the ANET interface with an OMNI option. The OMNI 729 option contains a first ifIndex-tuple with values specific to this 730 ANET interface, and may contain additional ifIndex-tuples specific 731 to other ANET interfaces. 733 o When an underlying ANET interface transitions to DOWN, the MN 734 sends an RS or unsolicited NA message over any UP ANET interface 735 with an OMNI option containing an ifIndex-tuple for the DOWN ANET 736 interface with Link(i) set to '0'. The MN sends an RS when an 737 acknowledgement is required, or an unsolicited NA when reliability 738 is not thought to be a concern (e.g., if redundant transmissions 739 are sent on multiple ANET interfaces). 741 o When a MN wishes to release from a current MSE, it sends an RS or 742 unsolicited NA message over any UP ANET interfaces with an OMNI 743 option with R set to 0. The corresponding MSE then withdraws the 744 MNP from the routing/mapping system and (for RS responses) returns 745 an RA message with an OMNI option and with Router Lifetime set to 746 0. 748 o When a MN wishes to transition to a new MSE, it sends an RS or 749 unsolicited NA message over any UP ANET interfaces with an OMNI 750 option with R set to 1, with the new MSE OMNI LLA set in the 751 destination address, and (optionally) with a Notification ID for 752 the former MSE. 754 o When all of a MNs underlying interfaces have transitioned to DOWN 755 (or if no further MN RS messages are received before Router 756 Lifetime expires) the MSE withdraws the MNP the same as if it had 757 received a message with an OMNI option with R set to 0. 759 The MN is responsible for retrying each RS exchange up to 760 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 761 seconds until an RA is received. If no RA is received over multiple 762 UP ANET interfaces, the MN declares this MSE unreachable and tries a 763 different MSE. 765 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 766 Therefore, when the IPv6 layer sends an RS message the OMNI interface 767 returns an internally-generated RA message as though the message 768 originated from an IPv6 router. The internally-generated RA message 769 contains configuration information (such as Router Lifetime, MTU, 770 etc.) that is consistent with the information received from the RAs 771 generated by the MS. 773 Whether the OMNI interface IPv6 ND messaging process is initiated 774 from the receipt of an RS message from the IPv6 layer is an 775 implementation matter. Some implementations may elect to defer the 776 IPv6 ND messaging process until an RS is received from the IPv6 777 layer, while others may elect to initiate the process proactively. 779 13. AR and MSE Resilience 781 ANETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 782 [RFC5798] configurations so that service continuity is maintained 783 even if one or more ARs fail. Using VRRP, the MN is unaware which of 784 the (redundant) ARs is currently providing service, and any service 785 discontinuity will be limited to the failover time supported by VRRP. 786 Widely deployed public domain implementations of VRRP are available. 788 MSEs SHOULD use high availability clustering services so that 789 multiple redundant systems can provide coordinated response to 790 failures. As with VRRP, widely deployed public domain 791 implementations of high availability clustering services are 792 available. Note that special-purpose and expensive dedicated 793 hardware is not necessary, and public domain implementations can be 794 used even between lightweight virtual machines in cloud deployments. 796 14. Detecting and Responding to MSE Failures 798 In environments where fast recovery from MSE failure is required, ARs 799 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 800 manner that parallels Bidirectional Forwarding Detection (BFD) 801 [RFC5880] to track MSE reachability. ARs can then quickly detect and 802 react to failures so that cached information is re-established 803 through alternate paths. Proactive NUD control messaging is carried 804 only over well-connected ground domain networks (i.e., and not low- 805 end aeronautical radio links) and can therefore be tuned for rapid 806 response. 808 ARs employ proactive NUD with MSEs for which there are currently 809 active ANET MNs. If an MSE fails, ARs can quickly inform MNs of the 810 outage by sending RA messages on the ANET interface. The AR sends RA 811 messages to the MN via the ANET interface with source address set to 812 the MSEs OMNI LLA, destination address set to all-nodes multicast, 813 and Router Lifetime set to 0. 815 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 816 by small delays [RFC4861]. Any MNs on the ANET interface that have 817 been using the (now defunct) MSE will receive the RA messages and 818 associate with a new MSE. 820 15. IANA Considerations 822 The IANA is instructed to allocate an official Type number TBD from 823 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 824 option. Implementations set Type to 253 as an interim value 825 [RFC4727]. 827 The IANA is instructed to allocate one Ethernet unicast address TBD2 828 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 829 Address Block - Unicast Use". 831 16. Security Considerations 833 Security considerations for IPv6 [RFC8200] and IPv6 Neighbor 834 Discovery [RFC4861] apply. OMNI interface IPv6 ND messages SHOULD 835 include Nonce and Timestamp options [RFC3971] when synchronized 836 transaction confirmation is needed. 838 Security considerations for specific access network interface types 839 are covered under the corresponding IP-over-(foo) specification 840 (e.g., [RFC2464]). 842 17. Acknowledgements 844 The first version of this document was prepared per the consensus 845 decision at the 7th Conference of the International Civil Aviation 846 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 847 2019. Consensus to take the document forward to the IETF was reached 848 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 849 Attendees and contributors included: Guray Acar, Danny Bharj, 850 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 851 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 852 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 853 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 854 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 855 Fryderyk Wrobel and Dongsong Zeng. 857 The following individuals are acknowledged for their useful comments: 858 Pavel Drasil, Zdenek Jaron, Michael Matyas, Madhu Niraula, Greg 859 Saccone, Stephane Tamalet, Eric Vyncke. Naming of the IPv6 ND option 860 was discussed on the 6man mailing list. 862 This work is aligned with the NASA Safe Autonomous Systems Operation 863 (SASO) program under NASA contract number NNA16BD84C. 865 This work is aligned with the FAA as per the SE2025 contract number 866 DTFAWA-15-D-00030. 868 18. References 870 18.1. Normative References 872 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 873 Requirement Levels", BCP 14, RFC 2119, 874 DOI 10.17487/RFC2119, March 1997, 875 . 877 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 878 "Definition of the Differentiated Services Field (DS 879 Field) in the IPv4 and IPv6 Headers", RFC 2474, 880 DOI 10.17487/RFC2474, December 1998, 881 . 883 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 884 "SEcure Neighbor Discovery (SEND)", RFC 3971, 885 DOI 10.17487/RFC3971, March 2005, 886 . 888 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 889 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 890 November 2005, . 892 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 893 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 894 2006, . 896 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 897 ICMPv6, UDP, and TCP Headers", RFC 4727, 898 DOI 10.17487/RFC4727, November 2006, 899 . 901 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 902 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 903 DOI 10.17487/RFC4861, September 2007, 904 . 906 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 907 Address Autoconfiguration", RFC 4862, 908 DOI 10.17487/RFC4862, September 2007, 909 . 911 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 912 Hosts in a Multi-Prefix Network", RFC 8028, 913 DOI 10.17487/RFC8028, November 2016, 914 . 916 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 917 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 918 May 2017, . 920 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 921 (IPv6) Specification", STD 86, RFC 8200, 922 DOI 10.17487/RFC8200, July 2017, 923 . 925 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 926 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 927 DOI 10.17487/RFC8201, July 2017, 928 . 930 18.2. Informative References 932 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 933 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 934 . 936 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 937 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 938 . 940 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 941 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 942 December 1998, . 944 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 945 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 946 . 948 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 949 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 950 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 951 RFC 3819, DOI 10.17487/RFC3819, July 2004, 952 . 954 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 955 "Internet Group Management Protocol (IGMP) / Multicast 956 Listener Discovery (MLD)-Based Multicast Forwarding 957 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 958 August 2006, . 960 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 961 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 962 RFC 5213, DOI 10.17487/RFC5213, August 2008, 963 . 965 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 966 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 967 DOI 10.17487/RFC5214, March 2008, 968 . 970 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 971 Version 3 for IPv4 and IPv6", RFC 5798, 972 DOI 10.17487/RFC5798, March 2010, 973 . 975 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 976 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 977 . 979 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 980 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 981 2012, . 983 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 984 Requirements for IPv6 Customer Edge Routers", RFC 7084, 985 DOI 10.17487/RFC7084, November 2013, 986 . 988 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 989 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 990 Boundary in IPv6 Addressing", RFC 7421, 991 DOI 10.17487/RFC7421, January 2015, 992 . 994 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 995 Support for IP Hosts with Multi-Access Support", RFC 7847, 996 DOI 10.17487/RFC7847, May 2016, 997 . 999 Appendix A. OMNI Option Extensions for Pseudo-DSCP Mappings 1001 Adaptation of the OMNI interface to specific Internetworks such as 1002 the Aeronautical Telecommunications Network with Internet Protocol 1003 Services (ATN/IPS) includes link selection preferences based on 1004 transport port numbers in addition to the existing DSCP-based 1005 preferences. ATN/IPS nodes maintain a map of transport port numbers 1006 to additional "pseudo-DSCP" P[*] preference fields beyond the first 1007 64. For example, TCP port 22 maps to pseudo-DSCP value P67, TCP port 1008 443 maps to P70, UDP port 8060 maps to P76, etc. Figure 4 shows an 1009 example OMNI option with extended P[*] values beyond the base 64 used 1010 for DSCP mapping (i.e., for QoS values 5 or greater): 1012 0 1 2 3 1013 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 1014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1015 | Type | Length | Prefix Length |R| Reserved | 1016 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1017 | ifIndex | ifType | Flags | Link |QoS=5+ | 1018 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1019 |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15| 1020 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1021 |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| 1022 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1023 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 1024 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1025 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1026 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1027 |P64|P65|P66|P67|P68|P69|P70|P71|P72|P73|P74|P75|P76|P77|P78|P79| 1028 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1029 ... 1031 Figure 4: ATN/IPS Extended OMNI Option Format 1033 Appendix B. Prefix Length Considerations 1035 The 64-bit boundary in IPv6 addresses [RFC7421] determines the MN 1036 OMNI LLA format for encoding the most-significant 64 MNP bits into 1037 the least-significant 64 bits of the prefix fe80::/64 as discussed in 1038 Section 7. 1040 [RFC4291] defines the link-local address format as the most 1041 significant 10 bits of the prefix fe80::/10, followed by 54 unused 1042 bits, followed by the least-significant 64 bits of the address. If 1043 the 64-bit boundary is relaxed through future standards activity, 1044 then the 54 unused bits can be employed for extended coding of MNPs 1045 of length /65 up to /118. 1047 The extended coding format would continue to encode MNP bits 0-63 in 1048 bits 64-127 of the OMNI LLA, while including MNP bits 64-117 in bits 1049 10-63. For example, the OMNI LLA corresponding to the MNP 1050 2001:db8:1111:2222:3333:4444:5555::/112 would be 1051 fe8c:ccd1:1115:5540:2001:db8:1111:2222, and would still be a valid 1052 IPv6 LLA per [RFC4291]. 1054 Appendix C. VDL Mode 2 Considerations 1056 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 1057 (VDLM2) that specifies an essential radio frequency data link service 1058 for aircraft and ground stations in worldwide civil aviation air 1059 traffic management. The VDLM2 link type is "multicast capable" 1061 [RFC4861], but with considerable differences from common multicast 1062 links such as Ethernet and IEEE 802.11. 1064 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 1065 magnitude less than most modern wireless networking gear. Second, 1066 due to the low available link bandwidth only VDLM2 ground stations 1067 (i.e., and not aircraft) are permitted to send broadcasts, and even 1068 so only as compact layer 2 "beacons". Third, aircraft employ the 1069 services of ground stations by performing unicast RS/RA exchanges 1070 upon receipt of beacons instead of listening for multicast RA 1071 messages and/or sending multicast RS messages. 1073 This beacon-oriented unicast RS/RA approach is necessary to conserve 1074 the already-scarce available link bandwidth. Moreover, since the 1075 numbers of beaconing ground stations operating within a given spatial 1076 range must be kept as sparse as possible, it would not be feasible to 1077 have different classes of ground stations within the same region 1078 observing different protocols. It is therefore highly desirable that 1079 all ground stations observe a common language of RS/RA as specified 1080 in this document. 1082 Note that links of this nature may benefit from compression 1083 techniques that reduce the bandwidth necessary for conveying the same 1084 amount of data. The IETF lpwan working group is considering possible 1085 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 1087 Appendix D. Change Log 1089 << RFC Editor - remove prior to publication >> 1091 Differences from draft-templin-atn-aero-interface-12 to draft- 1092 templin-atn-aero-interface-13: 1094 o Minor re-work on "Notify-MSE" (changed to Notification ID). 1096 Differences from draft-templin-atn-aero-interface-11 to draft- 1097 templin-atn-aero-interface-12: 1099 o Removed "Request/Response" OMNI option formats. Now, there is 1100 only one OMNI option format that applies to all ND messages. 1102 o Added new OMNI option field and supporting text for "Notify-MSE". 1104 Differences from draft-templin-atn-aero-interface-10 to draft- 1105 templin-atn-aero-interface-11: 1107 o Changed name from "aero" to "OMNI" 1108 o Resolved AD review comments from Eric Vyncke (posted to atn list) 1110 Differences from draft-templin-atn-aero-interface-09 to draft- 1111 templin-atn-aero-interface-10: 1113 o Renamed ARO option to AERO option 1115 o Re-worked Section 13 text to discuss proactive NUD. 1117 Differences from draft-templin-atn-aero-interface-08 to draft- 1118 templin-atn-aero-interface-09: 1120 o Version and reference update 1122 Differences from draft-templin-atn-aero-interface-07 to draft- 1123 templin-atn-aero-interface-08: 1125 o Removed "Classic" and "MS-enabled" link model discussion 1127 o Added new figure for MN/AR/MSE model. 1129 o New Section on "Detecting and responding to MSE failure". 1131 Differences from draft-templin-atn-aero-interface-06 to draft- 1132 templin-atn-aero-interface-07: 1134 o Removed "nonce" field from AR option format. Applications that 1135 require a nonce can include a standard nonce option if they want 1136 to. 1138 o Various editorial cleanups. 1140 Differences from draft-templin-atn-aero-interface-05 to draft- 1141 templin-atn-aero-interface-06: 1143 o New Appendix C on "VDL Mode 2 Considerations" 1145 o New Appendix D on "RS/RA Messaging as a Single Standard API" 1147 o Various significant updates in Section 5, 10 and 12. 1149 Differences from draft-templin-atn-aero-interface-04 to draft- 1150 templin-atn-aero-interface-05: 1152 o Introduced RFC6543 precedent for focusing IPv6 ND messaging to a 1153 reserved unicast link-layer address 1155 o Introduced new IPv6 ND option for Aero Registration 1156 o Specification of MN-to-MSE message exchanges via the ANET access 1157 router as a proxy 1159 o IANA Considerations updated to include registration requests and 1160 set interim RFC4727 option type value. 1162 Differences from draft-templin-atn-aero-interface-03 to draft- 1163 templin-atn-aero-interface-04: 1165 o Removed MNP from aero option format - we already have RIOs and 1166 PIOs, and so do not need another option type to include a Prefix. 1168 o Clarified that the RA message response must include an aero option 1169 to indicate to the MN that the ANET provides a MS. 1171 o MTU interactions with link adaptation clarified. 1173 Differences from draft-templin-atn-aero-interface-02 to draft- 1174 templin-atn-aero-interface-03: 1176 o Sections re-arranged to match RFC4861 structure. 1178 o Multiple aero interfaces 1180 o Conceptual sending algorithm 1182 Differences from draft-templin-atn-aero-interface-01 to draft- 1183 templin-atn-aero-interface-02: 1185 o Removed discussion of encapsulation (out of scope) 1187 o Simplified MTU section 1189 o Changed to use a new IPv6 ND option (the "aero option") instead of 1190 S/TLLAO 1192 o Explained the nature of the interaction between the mobility 1193 management service and the air interface 1195 Differences from draft-templin-atn-aero-interface-00 to draft- 1196 templin-atn-aero-interface-01: 1198 o Updates based on list review comments on IETF 'atn' list from 1199 4/29/2019 through 5/7/2019 (issue tracker established) 1201 o added list of opportunities afforded by the single virtual link 1202 model 1204 o added discussion of encapsulation considerations to Section 6 1206 o noted that DupAddrDetectTransmits is set to 0 1208 o removed discussion of IPv6 ND options for prefix assertions. The 1209 aero address already includes the MNP, and there are many good 1210 reasons for it to continue to do so. Therefore, also including 1211 the MNP in an IPv6 ND option would be redundant. 1213 o Significant re-work of "Router Discovery" section. 1215 o New Appendix B on Prefix Length considerations 1217 First draft version (draft-templin-atn-aero-interface-00): 1219 o Draft based on consensus decision of ICAO Working Group I Mobility 1220 Subgroup March 22, 2019. 1222 Authors' Addresses 1224 Fred L. Templin (editor) 1225 The Boeing Company 1226 P.O. Box 3707 1227 Seattle, WA 98124 1228 USA 1230 Email: fltemplin@acm.org 1232 Tony Whyman 1233 MWA Ltd c/o Inmarsat Global Ltd 1234 99 City Road 1235 London EC1Y 1AX 1236 England 1238 Email: tony.whyman@mccallumwhyman.com