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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 Updates: rfc4193, rfc4291, rfc4443, A. Whyman 5 rfc8201 (if approved) MWA Ltd c/o Inmarsat Global Ltd 6 Intended status: Standards Track June 2, 2020 7 Expires: December 4, 2020 9 Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) 10 Interfaces 11 draft-templin-6man-omni-interface-24 13 Abstract 15 Mobile nodes (e.g., aircraft of various configurations, terrestrial 16 vehicles, seagoing vessels, enterprise wireless devices, etc.) 17 communicate with networked correspondents over multiple access 18 network data links and configure mobile routers to connect end user 19 networks. A multilink interface specification is therefore needed 20 for coordination with the network-based mobility service. This 21 document specifies the transmission of IPv6 packets over Overlay 22 Multilink Network (OMNI) Interfaces. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at https://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on December 4, 2020. 41 Copyright Notice 43 Copyright (c) 2020 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (https://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 59 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7 61 4. Overlay Multilink Network (OMNI) Interface Model . . . . . . 7 62 5. Maximum Transmission Unit (MTU) and Fragmentation . . . . . . 10 63 5.1. Fragmentation Security Implications . . . . . . . . . . . 12 64 6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 13 65 7. Link-Local Addresses (LLAs) . . . . . . . . . . . . . . . . . 13 66 8. Unique-Local Addresses (ULAs) . . . . . . . . . . . . . . . . 14 67 9. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 15 68 9.1. Sub-Options . . . . . . . . . . . . . . . . . . . . . . . 16 69 9.1.1. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . 17 70 9.1.2. PadN . . . . . . . . . . . . . . . . . . . . . . . . 17 71 9.1.3. ifIndex-tuple (Type 1) . . . . . . . . . . . . . . . 17 72 9.1.4. ifIndex-tuple (Type 2) . . . . . . . . . . . . . . . 20 73 9.1.5. MS-Register . . . . . . . . . . . . . . . . . . . . . 20 74 9.1.6. MS-Release . . . . . . . . . . . . . . . . . . . . . 21 75 9.1.7. Network Access Identifier (NAI) . . . . . . . . . . . 21 76 9.1.8. Geo Coordiantes . . . . . . . . . . . . . . . . . . . 21 77 10. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 22 78 11. Conceptual Sending Algorithm . . . . . . . . . . . . . . . . 22 79 11.1. Multiple OMNI Interfaces . . . . . . . . . . . . . . . . 23 80 12. Router Discovery and Prefix Registration . . . . . . . . . . 23 81 12.1. Multihop Router Discovery . . . . . . . . . . . . . . . 26 82 13. Secure Redirection . . . . . . . . . . . . . . . . . . . . . 27 83 14. AR and MSE Resilience . . . . . . . . . . . . . . . . . . . . 28 84 15. Detecting and Responding to MSE Failures . . . . . . . . . . 28 85 16. Transition Considerations . . . . . . . . . . . . . . . . . . 29 86 17. OMNI Interfaces on the Open Internet . . . . . . . . . . . . 29 87 18. Time-Varying MNPs . . . . . . . . . . . . . . . . . . . . . . 30 88 19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 89 20. Security Considerations . . . . . . . . . . . . . . . . . . . 31 90 21. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32 91 22. References . . . . . . . . . . . . . . . . . . . . . . . . . 32 92 22.1. Normative References . . . . . . . . . . . . . . . . . . 32 93 22.2. Informative References . . . . . . . . . . . . . . . . . 34 94 Appendix A. Type 1 ifIndex-tuple Traffic Classifier Preference 95 Encoding . . . . . . . . . . . . . . . . . . . . . . 38 96 Appendix B. VDL Mode 2 Considerations . . . . . . . . . . . . . 39 97 Appendix C. MN / AR Isolation Through L2 Address Mapping . . . . 40 98 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 41 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46 101 1. Introduction 103 Mobile Nodes (MNs) (e.g., aircraft of various configurations, 104 terrestrial vehicles, seagoing vessels, enterprise wireless devices, 105 etc.) often have multiple data links for communicating with networked 106 correspondents. These data links may have diverse performance, cost 107 and availability properties that can change dynamically according to 108 mobility patterns, flight phases, proximity to infrastructure, etc. 109 MNs coordinate their data links in a discipline known as "multilink", 110 in which a single virtual interface is configured over the underlying 111 data links. 113 The MN configures a virtual interface (termed the "Overlay Multilink 114 Network (OMNI) interface") as a thin layer over the underlying Access 115 Network (ANET) interfaces. The OMNI interface is therefore the only 116 interface abstraction exposed to the IPv6 layer and behaves according 117 to the Non-Broadcast, Multiple Access (NBMA) interface principle, 118 while underlying interfaces appear as link layer communication 119 channels in the architecture. The OMNI interface connects to a 120 virtual overlay service known as the "OMNI link". The OMNI link 121 spans one or more Internetworks that may include private-use 122 infrastructures and/or the global public Internet itself. 124 Each MN receives a Mobile Network Prefix (MNP) for numbering 125 downstream-attached End User Networks (EUNs) independently of the 126 access network data links selected for data transport. The MN 127 performs router discovery over the OMNI interface (i.e., similar to 128 IPv6 customer edge routers [RFC7084]) and acts as a mobile router on 129 behalf of its EUNs. The router discovery process is iterated over 130 each of the OMNI interface's underlying interfaces in order to 131 register per-link parameters (see Section 12). 133 The OMNI interface provides a multilink nexus for exchanging inbound 134 and outbound traffic via the correct underlying interface(s). The 135 IPv6 layer sees the OMNI interface as a point of connection to the 136 OMNI link. Each OMNI link has one or more associated Mobility 137 Service Prefixes (MSPs) from which OMNI link MNPs are derived. If 138 there are multiple OMNI links, the IPv6 layer will see multiple OMNI 139 interfaces. 141 MNs may connect to multiple distinct OMNI links by configuring 142 multiple OMNI interfaces, e.g., omni0, omni1, omni2, etc. Each OMNI 143 interface is configured over a set of underlying interfaces and 144 provides a nexus for Safety-Based Multilink (SBM) operation. The IP 145 layer selects an OMNI interface based on SBM routing considerations, 146 then the selected interface applies Performance-Based Multilink (PBM) 147 to select the correct underlying interface. Applications can apply 148 Segment Routing [RFC8402] to select independent SBM topologies for 149 fault tolerance. 151 The OMNI interface interacts with a network-based Mobility Service 152 (MS) through IPv6 Neighbor Discovery (ND) control message exchanges 153 [RFC4861]. The MS provides Mobility Service Endpoints (MSEs) that 154 track MN movements and represent their MNPs in a global routing or 155 mapping system. 157 This document specifies the transmission of IPv6 packets [RFC8200] 158 and MN/MS control messaging over OMNI interfaces. 160 2. Terminology 162 The terminology in the normative references applies; especially, the 163 terms "link" and "interface" are the same as defined in the IPv6 164 [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications. 165 Also, the Protocol Constants defined in Section 10 of [RFC4861] are 166 used in their same format and meaning in this document. The terms 167 "All-Routers multicast", "All-Nodes multicast" and "Subnet-Router 168 anycast" are the same as defined in [RFC4291] (with Link-Local scope 169 assumed). 171 The following terms are defined within the scope of this document: 173 Mobile Node (MN) 174 an end system with a mobile router having multiple distinct 175 upstream data link connections that are grouped together in one or 176 more logical units. The MN's data link connection parameters can 177 change over time due to, e.g., node mobility, link quality, etc. 178 The MN further connects a downstream-attached End User Network 179 (EUN). The term MN used here is distinct from uses in other 180 documents, and does not imply a particular mobility protocol. 182 End User Network (EUN) 183 a simple or complex downstream-attached mobile network that 184 travels with the MN as a single logical unit. The IPv6 addresses 185 assigned to EUN devices remain stable even if the MN's upstream 186 data link connections change. 188 Mobility Service (MS) 189 a mobile routing service that tracks MN movements and ensures that 190 MNs remain continuously reachable even across mobility events. 191 Specific MS details are out of scope for this document. 193 Mobility Service Endpoint (MSE) 194 an entity in the MS (either singular or aggregate) that 195 coordinates the mobility events of one or more MN. 197 Mobility Service Prefix (MSP) 198 an aggregated IPv6 prefix (e.g., 2001:db8::/32) advertised to the 199 rest of the Internetwork by the MS, and from which more-specific 200 Mobile Network Prefixes (MNPs) are derived. 202 Mobile Network Prefix (MNP) 203 a longer IPv6 prefix taken from an MSP (e.g., 204 2001:db8:1000:2000::/56) and assigned to a MN. MNs sub-delegate 205 the MNP to devices located in EUNs. 207 Access Network (ANET) 208 a data link service network (e.g., an aviation radio access 209 network, satellite service provider network, cellular operator 210 network, wifi network, etc.) that connects MNs. Physical and/or 211 data link level security between the MN and ANET are assumed. 213 Access Router (AR) 214 a first-hop router in the ANET for connecting MNs to 215 correspondents in outside Internetworks. 217 ANET interface 218 a MN's attachment to a link in an ANET. 220 Internetwork (INET) 221 a connected network region with a coherent IP addressing plan that 222 provides transit forwarding services for ANET MNs and INET 223 correspondents. Examples include private enterprise networks, 224 ground domain aviation service networks and the global public 225 Internet itself. 227 INET interface 228 a node's attachment to a link in an INET. 230 OMNI link 231 a virtual overlay configured over one or more INETs and their 232 connected ANETs. An OMNI link can comprise multiple INET segments 233 joined by bridges the same as for any link; the addressing plans 234 in each segment may be mutually exclusive and managed by different 235 administrative entities. 237 OMNI interface 238 a node's attachment to an OMNI link, and configured over one or 239 more underlying ANET/INET interfaces. 241 OMNI link local address (LLA) 242 an IPv6 link-local address constructed as specified in Section 7, 243 and assigned to an OMNI interface. 245 OMNI Option 246 an IPv6 Neighbor Discovery option providing multilink parameters 247 for the OMNI interface as specified in Section 9. 249 Multilink 250 an OMNI interface's manner of managing diverse underlying data 251 link interfaces as a single logical unit. The OMNI interface 252 provides a single unified interface to upper layers, while 253 underlying data link selections are performed on a per-packet 254 basis considering factors such as DSCP, flow label, application 255 policy, signal quality, cost, etc. Multilinking decisions are 256 coordinated in both the outbound (i.e. MN to correspondent) and 257 inbound (i.e., correspondent to MN) directions. 259 L2 260 The second layer in the OSI network model. Also known as "layer- 261 2", "link-layer", "sub-IP layer", "data link layer", etc. 263 L3 264 The third layer in the OSI network model. Also known as "layer- 265 3", "network-layer", "IPv6 layer", etc. 267 underlying interface 268 an ANET/INET interface over which an OMNI interface is configured. 269 The OMNI interface is seen as a L3 interface by the IP layer, and 270 each underlying interface is seen as a L2 interface by the OMNI 271 interface. 273 Mobility Service Identification (MSID) 274 Each MSE and AR is assigned a unique 32-bit Identification (MSID) 275 as specified in Section 7. 277 Safety-Based Multilink (SBM) 278 A means for ensuring fault tolerance through redundancy by 279 connecting multiple independent OMNI interfaces to independent 280 routing topologies (i.e., multiple independent OMNI links). 282 Performance Based Multilink (PBM) 283 A means for selecting underlying interface(s) for packet 284 trasnmission and reception within a single OMNI interface. 286 3. Requirements 288 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 289 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 290 "OPTIONAL" in this document are to be interpreted as described in BCP 291 14 [RFC2119][RFC8174] when, and only when, they appear in all 292 capitals, as shown here. 294 An implementation is not required to internally use the architectural 295 constructs described here so long as its external behavior is 296 consistent with that described in this document. 298 4. Overlay Multilink Network (OMNI) Interface Model 300 An OMNI interface is a MN virtual interface configured over one or 301 more underlying interfaces, which may be physical (e.g., an 302 aeronautical radio link) or virtual (e.g., an Internet or higher- 303 layer "tunnel"). The MN receives a MNP from the MS, and coordinates 304 with the MS through IPv6 ND message exchanges. The MN uses the MNP 305 to construct a unique OMNI LLA through the algorithmic derivation 306 specified in Section 7 and assigns the LLA to the OMNI interface. 308 The OMNI interface architectural layering model is the same as in 309 [RFC5558][RFC7847], and augmented as shown in Figure 1. The IP layer 310 therefore sees the OMNI interface as a single L3 interface with 311 multiple underlying interfaces that appear as L2 communication 312 channels in the architecture. 314 +----------------------------+ 315 | Upper Layer Protocol | 316 Session-to-IP +---->| | 317 Address Binding | +----------------------------+ 318 +---->| IP (L3) | 319 IP Address +---->| | 320 Binding | +----------------------------+ 321 +---->| OMNI Interface | 322 Logical-to- +---->| (OMNI LLA) | 323 Physical | +----------------------------+ 324 Interface +---->| L2 | L2 | | L2 | 325 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 326 +------+------+ +------+ 327 | L1 | L1 | | L1 | 328 | | | | | 329 +------+------+ +------+ 331 Figure 1: OMNI Interface Architectural Layering Model 333 The OMNI virtual interface model gives rise to a number of 334 opportunities: 336 o since OMNI LLAs are uniquely derived from an MNP, no Duplicate 337 Address Detection (DAD) or Muticast Listener Discovery (MLD) 338 messaging is necessary. 340 o ANET interfaces do not require any L3 addresses (i.e., not even 341 link-local) in environments where communications are coordinated 342 entirely over the OMNI interface. (An alternative would be to 343 also assign the same OMNI LLA to all ANET interfaces.) 345 o as ANET interface properties change (e.g., link quality, cost, 346 availability, etc.), any active ANET interface can be used to 347 update the profiles of multiple additional ANET interfaces in a 348 single message. This allows for timely adaptation and service 349 continuity under dynamically changing conditions. 351 o coordinating ANET interfaces in this way allows them to be 352 represented in a unified MS profile with provisions for mobility 353 and multilink operations. 355 o exposing a single virtual interface abstraction to the IPv6 layer 356 allows for multilink operation (including QoS based link 357 selection, packet replication, load balancing, etc.) at L2 while 358 still permitting L3 traffic shaping based on, e.g., DSCP, flow 359 label, etc. 361 o L3 sees the OMNI interface as a point of connection to the OMNI 362 link; if there are multiple OMNI links (i.e., multiple MS's), L3 363 will see multiple OMNI interfaces. 365 o Multiple independent OMNI interfaces can be used for increased 366 fault tolerance through Safety-Based Multilink (SBM), with 367 Performance-Based Multilink (PBM) applied within each interface. 369 Other opportunities are discussed in [RFC7847]. 371 Figure 2 depicts the architectural model for a MN connecting to the 372 MS via multiple independent ANETs. When an underlying interface 373 becomes active, the MN's OMNI interface sends native (i.e., 374 unencapsulated) IPv6 ND messages via the underlying interface. IPv6 375 ND messages traverse the ground domain ANETs until they reach an 376 Access Router (AR#1, AR#2, .., AR#n). The AR then coordinates with a 377 Mobility Service Endpoint (MSE#1, MSE#2, ..., MSE#m) in the INET and 378 returns an IPv6 ND message response to the MN. IPv6 ND messages 379 traverse the ANET at layer 2; hence, the Hop Limit is not 380 decremented. 382 +--------------+ 383 | MN | 384 +--------------+ 385 |OMNI interface| 386 +----+----+----+ 387 +--------|IF#1|IF#2|IF#n|------ + 388 / +----+----+----+ \ 389 / | \ 390 / <---- Native | IP ----> \ 391 v v v 392 (:::)-. (:::)-. (:::)-. 393 .-(::ANET:::) .-(::ANET:::) .-(::ANET:::) 394 `-(::::)-' `-(::::)-' `-(::::)-' 395 +----+ +----+ +----+ 396 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 397 . +-|--+ +-|--+ +-|--+ . 398 . | | | 399 . v v v . 400 . <----- Encapsulation -----> . 401 . . 402 . +-----+ (:::)-. . 403 . |MSE#2| .-(::::::::) +-----+ . 404 . +-----+ .-(::: INET :::)-. |MSE#m| . 405 . (::::: Routing ::::) +-----+ . 406 . `-(::: System :::)-' . 407 . +-----+ `-(:::::::-' . 408 . |MSE#1| +-----+ +-----+ . 409 . +-----+ |MSE#3| |MSE#4| . 410 . +-----+ +-----+ . 411 . . 412 . . 413 . <----- Worldwide Connected Internetwork ----> . 414 ........................................................... 416 Figure 2: MN/MS Coordination via Multiple ANETs 418 After the initial IPv6 ND message exchange, the MN can send and 419 receive unencapsulated IPv6 data packets over the OMNI interface. 420 OMNI interface multilink services will forward the packets via ARs in 421 the correct underlying ANETs. The AR encapsulates the packets 422 according to the capabilities provided by the MS and forwards them to 423 the next hop within the worldwide connected Internetwork via optimal 424 routes. 426 OMNI links span one or more underlying Internetwork via a mid-layer 427 overlay encapsulation based on [RFC2473] and using [RFC4193] 428 addressing. Each OMNI link corresponds to a different overlay 429 (differentiated by an address codepoint) which may be carried over a 430 completely separate underlying topology. Each MN can facilitate SBM 431 by connecting to multiple OMNI links using a distinct OMNI interface 432 for each link. 434 5. Maximum Transmission Unit (MTU) and Fragmentation 436 The OMNI interface observes the link nature of tunnels, including the 437 Maximum Transmission Unit (MTU) and the role of fragmentation and 438 reassembly[I-D.ietf-intarea-tunnels]. The OMNI interface is 439 configured over one or more underlying interfaces that may have 440 diverse MTUs. 442 IPv6 underlying interfaces are REQUIRED to configure a minimum MTU of 443 1280 bytes [RFC8200]. The network therefore MUST forward packets of 444 at least 1280 bytes without generating an IPv6 Path MTU Discovery 445 (PMTUD) Packet Too Big (PTB) message [RFC8201]. The minimum MTU for 446 IPv4 underlying interfaces is only 68 bytes [RFC1122], meaning that a 447 packet smaller than the IPv6 minimum MTU may require fragmentation 448 when IPv4 encapsulation is used. Therefore, the Don't Fragment (DF) 449 bit in the IPv4 encapsulation header MUST be set to 0 451 The OMNI interface configures an MTU of 9180 bytes [RFC2492]; the 452 size is therefore not a reflection of the underlying interface MTUs, 453 but rather determines the largest packet the OMNI interface can 454 forward or reassemble. The OMNI interface therefore accommodates 455 packets as large as the OMNI interface MTU while generating IPv6 Path 456 MTU Discovery (PMTUD) Packet Too Big (PTB) messages [RFC8201] as 457 necessary (see below). For IPv4 packets with DF=0, the IP layer 458 performs IPv4 fragmentation if necessary to admit the fragments into 459 the OMNI interface. The interface may then internally apply further 460 IPv4 fragmentation prior to encapsulation to ensure that the IPv4 461 fragments are delivered to the final destination. 463 OMNI interfaces internally employ OMNI link encapsulation and 464 fragmentation/reassembly per [RFC2473]. The encapsulation inserts a 465 mid-layer IPv6 header between the inner IP packet and any outer IP 466 encapsulation headers. The OMNI interface returns internally- 467 generated PTB messages for packets admitted into the interface that 468 it deems too large (e.g., according to link performance 469 characteristics, reassembly cost, etc.) while either dropping or 470 forwarding the packet as necessary. The OMNI interface performs 471 PMTUD even if the destination appears to be on the same link since an 472 OMNI link node on the path may return a PTB. This ensures that the 473 path MTU is adaptive and reflects the current path used for a given 474 data flow. 476 OMNI interfaces perform encapsulation and fragmentation/reassembly as 477 follows: 479 o When an OMNI interface sends a packet toward a final destination 480 via an ANET peer, it sends without OMNI link encapsulation if the 481 packet is no larger than the underlying interface MTU. Otherwise, 482 it inserts an IPv6 header with source address set to the node's 483 own OMNI Unique Local Address (ULA) (see: Section 8) and 484 destination set to the OMNI ULA of the ANET peer. The OMNI 485 interface then uses IPv6 fragmentation to break the packet into a 486 minimum number of non-overlapping fragments, where the largest 487 fragment size is determined by the underlying interface MTU and 488 the smallest fragment is no smaller than 640 bytes. The OMNI 489 interface then sends the fragments to the ANET peer, which 490 reassembles before forwarding toward the final destination. 492 o When an OMNI interface sends a packet toward a final destination 493 via an INET interface, it sends packets no larger than 1280 bytes 494 (including any INET encapsulation headers) without inserting a 495 mid-layer IPv6 header if the destination is reached via an INET 496 address within the same OMNI link segment. Otherwise, it inserts 497 an IPv6 header with source address set to the node's OMNI ULA, 498 destination set to the ULA of the next hop OMNI node toward the 499 final destination and (if necessary) with a Segment Routing Header 500 with the remaining Segment IDs on the path to the final 501 destination. The OMNI interface then uses IPv6 fragmentation to 502 break the encapsulated packet into a minimum number of non- 503 overlapping fragments, where the largest fragment size (including 504 both the OMNI mid-layer IPv6 and outer-layer INET encapsulations) 505 is 1280 bytes and the smallest fragment is no smaller than 640 506 bytes. The OMNI interface then encapsulates the fragments in any 507 INET headers and sends them to the OMNI link neighbor, which 508 reassembles before forwarding toward the final destination. 510 OMNI interfaces unconditionally drop all OMNI link fragments smaller 511 than 640 bytes. In order to set the correct context for reassembly, 512 the OMNI interface that inserts the IPv6 header MUST also be the one 513 that inserts the IPv6 Fragment Header Identification value. While 514 not strictly required, sending all fragments of the same fragmented 515 mid-layer packet consecutively over the same underlying interface 516 with minimal inter-fragment delay can in some cases increase the 517 likelihood of successful reassembly. 519 Note that the OMNI interface can forward large packets via 520 encapsulation and fragmentation while at the same time returning 521 "advisory" PTB messages (subject to rate limiting). The receiving 522 node that performs reassembly can also send advisory PTB messages if 523 reassembly conditions become unfavorable. The OMNI interface can 524 therefore continuously forward large packets without loss while 525 returning advisory PTB messages recommending a smaller size. 527 OMNI interfaces that send advisory PTB messages set the ICMPv6 528 message header Code field to the value 1. Receiving nodes that 529 recognize the code reduce their estimate of the path MTU the same as 530 for ordinary "diagnistic" PTBs but do not regard the message as a 531 loss indication. Nodes that do not recognize the code treat the 532 message the same as a diagnostic PTB, but should heed the advice in 533 [RFC8201] regarding retransmissions. This document therefore updates 534 [RFC4443] and [RFC8201]. 536 5.1. Fragmentation Security Implications 538 As discussed in Section 3.7 of [I-D.ietf-intarea-frag-fragile], there 539 are four basic threats concerning IPv6 fragmentation; each of which 540 is addressed by a suitable mitigation as follows: 542 1. Overlapping fragment attacks - reassembly of overlapping 543 fragments is forbidden by [RFC8200]; therefore, this threat does 544 not apply to OMNI interfaces. 546 2. Resource exhaustion attacks - this threat is mitigated by 547 providing a sufficiently large OMNI interface reassembly cache 548 and instituting "fast discard" of incomplete reassemblies that 549 may be part of a buffer exhaustion attack. The reassembly cache 550 should be sufficiently large so that a sustained attack does not 551 cause excessive loss of good reassemblies but not so large that 552 (timer-based) data structure management becomes computationally 553 expensive. 555 3. Attacks based on predictable fragment identification values - 556 this threat is mitigated by selecting a suitably random ID value 557 per [RFC7739]. 559 4. Evasion of Network Intrusion Detection Systems (NIDS) - this 560 threat is mitigated by disallowing "tiny fragments" per the OMNI 561 interface fragmentation procedures specified above. 563 Additionally, IPv4 fragmentation includes a 16-bit Identification (IP 564 ID) field with only 65535 unique values, meaning that for even 565 moderately high data rates the field could wrap and apply to new 566 packets while the fragments of old packets using the same ID are 567 still alive in the network [RFC4963]. Since IPv6 provides a 32-bit 568 Identification value, however, this is not a concern for IPv6 569 fragmentation. 571 6. Frame Format 573 The OMNI interface transmits IPv6 packets according to the native 574 frame format of each underlying interface. For example, for 575 Ethernet-compatible interfaces the frame format is specified in 576 [RFC2464], for aeronautical radio interfaces the frame format is 577 specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical 578 Manual), for tunnels over IPv6 the frame format is specified in 579 [RFC2473], etc. 581 7. Link-Local Addresses (LLAs) 583 OMNI interfaces construct IPv6 Link-Local Addresses (i.e., "OMNI 584 LLAs") as follows: 586 o IPv6 MN OMNI LLAs encode the most-significant 112 bits of a MNP 587 within the least-significant 112 bits of the IPv6 link-local 588 prefix fe80::/16. For example, for the MNP 589 2001:db8:1000:2000::/56 the corresponding LLA is 590 fe80:2001:db8:1000:2000::. This updates the IPv6 link-local 591 address format specified in Section 2.5.6 of [RFC4291] by defining 592 a use for bits 11 - 63. 594 o IPv4-compatible MN OMNI LLAs are constructed as 595 fe80::ffff:[v4addr], i.e., the most significant 16 bits of the 596 prefix fe80::/16, followed by 64 '0' bits, followed by 16 '1' 597 bits, followed by a 32bit IPv4 address. For example, the 598 IPv4-Compatible MN OMNI LLA for 192.0.2.1 is fe80::ffff:192.0.2.1 599 (also written as fe80::ffff:c000:0201). 601 o MS OMNI LLAs are assigned to ARs and MSEs from the range 602 fe80::/96, and MUST be managed for uniqueness. The lower 32 bits 603 of the LLA includes a unique integer "MSID" value between 604 0x00000001 and 0xfeffffff, e.g., as in fe80::1, fe80::2, fe80::3, 605 etc., fe80::feff:ffff. The MSID 0x00000000 corresponds to the 606 link-local Subnet-Router anycast address (fe80::) [RFC4291]. The 607 MSID range 0xff000000 through 0xffffffff is reserved for future 608 use. 610 o The OMNI LLA range fe80::/32 is used as the service prefix for the 611 address format specified in Section 4 of [RFC4380] (see Section 17 612 for further discussion). 614 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 615 MNPs can be allocated from that block ensuring that there is no 616 possibility for overlap between the above OMNI LLA constructs. 618 Since MN OMNI LLAs are based on the distribution of administratively 619 assured unique MNPs, and since MS OMNI LLAs are guaranteed unique 620 through administrative assignment, OMNI interfaces set the 621 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 623 8. Unique-Local Addresses (ULAs) 625 OMNI links use IPv6 Unique Local Addresses (i.e., "OMNI ULAs") 626 [RFC4193] as the source and destination addresses in OMNI link IPv6 627 encapsulation headers. This document updates [RFC4193] by reserving 628 the ULA prefix fc80::/10 for mapping OMNI LLAs to routable OMNI ULAs. 630 Each OMNI link instance is identified by bits 10-15 of the OMNI 631 service prefix fc80::/10. For example, OMNI ULAs associated with 632 instance 0 are configured from the prefix fc80::/16, instance 1 from 633 fc81::/16, etc., up to instance 63 from fcbf::/16. OMNI ULAs are 634 configured in one-to-one correspondence with OMNI LLAs through 635 stateless prefix translation. For example, for OMNI link instance 636 fc80::/16: 638 o the OMNI ULA corresponding to fe80:2001:db8:1:2:: is simply 639 fc80:2001:db8:1:2:: 641 o the OMNI ULA corresponding to fe80::ffff:192.0.2.1 is simply 642 fc80::ffff:192.0.2.1 644 o the OMNI ULA corresponding to fe80::1000 is simply fc80::1000 646 o the OMNI ULA corresponding to fe80:: is simply fc80:: 648 Each OMNI interface assigns the Anycast OMNI ULA specific to the OMNI 649 link instance, e.g., the OMNI interface connected to instance 3 650 assigns the Anycast OMNI ULA fc83:. Routers that configure OMNI 651 interfaces advertise the OMNI service prefix (e.g., fc83::/16) into 652 the local routing system so that applications can direct traffic 653 according to SBM requirements. 655 The OMNI ULA presents an IPv6 address format that is routable within 656 the OMNI link routing system and can be used to convey link-scoped 657 messages across multiple hops using IPv6 encapsulation [RFC2473]. 658 The OMNI link extends across one or more underling Internetworks to 659 include all ARs and MSEs. All MNs are also considered to be 660 connected to the OMNI link, however OMNI link encapsulation is 661 omitted over ANET links when possible to conserve bandwidth (see: 662 Section 11). 664 The OMNI link can be subdivided into "segments" that often correspond 665 to different administrative domains or physical partitions. OMNI 666 nodes can use IPv6 Segment Routing [RFC8402] when necessary to 667 support efficient packet forwarding to destinations located in other 668 OMNI link segments. A full discussion of Segment Routing over the 669 OMNI link appears in [I-D.templin-intarea-6706bis]. 671 9. Address Mapping - Unicast 673 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 674 state and use the link-local address format specified in Section 7. 675 IPv6 Neighbor Discovery (ND) [RFC4861] messages on MN OMNI interfaces 676 observe the native Source/Target Link-Layer Address Option (S/TLLAO) 677 formats of the underlying interfaces (e.g., for Ethernet the S/TLLAO 678 is specified in [RFC2464]). 680 MNs such as aircraft typically have many wireless data link types 681 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 682 etc.) with diverse performance, cost and availability properties. 683 The OMNI interface would therefore appear to have multiple L2 684 connections, and may include information for multiple underlying 685 interfaces in a single IPv6 ND message exchange. 687 OMNI interfaces use an IPv6 ND option called the "OMNI option" 688 formatted as shown in Figure 3: 690 0 1 2 3 691 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 1 692 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 693 | Type | Length | Prefix Length |R| Reserved | 694 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 695 | | 696 ~ Sub-Options ~ 697 | | 698 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 700 Figure 3: OMNI Option Format 702 In this format: 704 o Type is set to TBD. 706 o Length is set to the number of 8 octet blocks in the option. 708 o Prefix Length is set according to the IPv6 source address type. 709 For MN OMNI LLAs, the value is set to the length of the embedded 710 MNP. For IPv4-compatible MN OMNI LLAs, the value is set to 96 711 plus the length of the embedded IPv4 prefix. For MS OMNI LLAs, 712 the value is set to 128. 714 o R (the "Register/Release" bit) is set to 1/0 to request the 715 message recipient to register/release a MN's MNP. The OMNI option 716 may additionally include MSIDs for the recipient to contact to 717 also register/release the MNP. 719 o Reserved is set to the value '0' on transmission and ignored on 720 reception. 722 o Sub-Options is a Variable-length field, of length such that the 723 complete OMNI Option is an integer multiple of 8 octets long. 724 Contains one or more options, as described in Section 9.1. 726 9.1. Sub-Options 728 The OMNI option includes zero or more Sub-Options, some of which may 729 appear multiple times in the same message. Each consecutive Sub- 730 Option is concatenated immediately after its predecessor. All Sub- 731 Options except Pad1 (see below) are type-length-value (TLV) encoded 732 in the following format: 734 0 1 2 735 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 5 736 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 737 | Sub-Type | Sub-length | Sub-Option Data ... 738 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 740 Figure 4: Sub-Option Format 742 o Sub-Type is a 1-byte field that encodes the Sub-Option type. Sub- 743 Options defined in this document are: 745 Option Name Sub-Type 746 Pad1 0 747 PadN 1 748 ifIndex-tuple (Type 1) 2 749 ifIndex-tuple (Type 2) 3 750 MS-Register 4 751 MS-Release 5 752 Network Access Identifier 6 753 Geo Coordinates 7 755 Figure 5 757 Sub-Types 253 and 254 are reserved for experimentation, as 758 recommended in [RFC3692]. 760 o Sub-Length is a 1-byte field that encodes the length of the Sub- 761 Option Data, in bytes 763 o Sub-Option Data is a byte string with format determined by Sub- 764 Type 766 During processing, unrecognized Sub-Options are ignored and the next 767 Sub-Option processed until the end of the OMNI option. 769 The following Sub-Option types and formats are defined in this 770 document: 772 9.1.1. Pad1 774 0 775 0 1 2 3 4 5 6 7 776 +-+-+-+-+-+-+-+-+ 777 | Sub-Type=0 | 778 +-+-+-+-+-+-+-+-+ 780 Figure 6: Pad1 782 o Sub-Type is set to 0. 784 o No Sub-Length or Sub-Option Data follows (i.e., the "Sub-Option" 785 consists of a single zero octet). 787 9.1.2. PadN 789 0 1 2 790 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 5 791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 792 | Sub-Type=1 |Sub-length=N-2 | N-2 padding bytes ... 793 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 795 Figure 7: PadN 797 o Sub-Type is set to 1. 799 o Sub-Length is set to N-2 being the number of padding bytes that 800 follow. 802 o Sub-Option Data consists of N-2 zero-valued octets. 804 9.1.3. ifIndex-tuple (Type 1) 805 0 1 2 3 806 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 1 807 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 808 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 809 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 810 | Provider ID | Link |S|I|RSV| Bitmap(0)=0xff|P00|P01|P02|P03| 811 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 812 |P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19| 813 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 814 |P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| Bitmap(1)=0xff| 815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 816 |P32|P33|P34|P35|P36|P37|P38|P39| ... 817 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 819 Figure 8: ifIndex-tuple (Type 1) 821 o Sub-Type is set to 2. 823 o Sub-Length is set to 4+N (the number of Sub-Option Data bytes that 824 follow). 826 o Sub-Option Data contains an "ifIndex-tuple" (Type 1) encoded as 827 follows (note that the first four bytes must be present): 829 * ifIndex is set to an 8-bit integer value corresponding to a 830 specific underlying interface. OMNI options MAY include 831 multiple ifIndex-tuples, and MUST number each with an ifIndex 832 value between '1' and '255' that represents a MN-specific 8-bit 833 mapping for the actual ifIndex value assigned to the underlying 834 interface by network management [RFC2863] (the ifIndex value 835 '0' is reserved for use by the MS). Multiple ifIndex-tuples 836 with the same ifIndex value MAY appear in the same OMNI option. 838 * ifType is set to an 8-bit integer value corresponding to the 839 underlying interface identified by ifIndex. The value 840 represents an OMNI interface-specific 8-bit mapping for the 841 actual IANA ifType value registered in the 'IANAifType-MIB' 842 registry [http://www.iana.org]. 844 * Provider ID is set to an OMNI interface-specific 8-bit ID value 845 for the network service provider associated with this ifIndex. 847 * Link encodes a 4-bit link metric. The value '0' means the link 848 is DOWN, and the remaining values mean the link is UP with 849 metric ranging from '1' ("lowest") to '15' ("highest"). 851 * S is set to '1' if this ifIndex-tuple corresponds to the 852 underlying interface that is the source of the ND message. Set 853 to '0' otherwise. 855 * I is set to '0' ("Simplex") if the index for each singleton 856 Bitmap byte in the Sub-Option Data is inferred from its 857 sequential position (i.e., 0, 1, 2, ...), or set to '1' 858 ("Indexed") if each Bitmap is preceded by an Index byte. 859 Figure 8 shows the simplex case for I set to '0'. For I set to 860 '1', each Bitmap is instead preceded by an Index byte that 861 encodes a value "i" = (0 - 255) as the index for its companion 862 Bitmap as follows: 864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 865 | Index=i | Bitmap(i) |P[*] values ... 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 868 Figure 9 870 * RSV is set to the value 0 on transmission and ignored on 871 reception. 873 * The remainder of the Sub-Option Data contains N = (0 - 251) 874 bytes of traffic classifier preferences consisting of a first 875 (indexed) Bitmap (i.e., "Bitmap(i)") followed by 0-8 1-byte 876 blocks of 2-bit P[*] values, followed by a second Bitmap (i), 877 followed by 0-8 blocks of P[*] values, etc. Reading from bit 0 878 to bit 7, the bits of each Bitmap(i) that are set to '1'' 879 indicate the P[*] blocks from the range P[(i*32)] through 880 P[(i*32) + 31] that follow; if any Bitmap(i) bits are '0', then 881 the corresponding P[*] block is instead omitted. For example, 882 if Bitmap(0) contains 0xff then the block with P[00]-P[03], 883 followed by the block with P[04]-P[07], etc., and ending with 884 the block with P[28]-P[31] are included (as shown in Figure 8). 885 The next Bitmap(i) is then consulted with its bits indicating 886 which P[*] blocks follow, etc. out to the end of the Sub- 887 Option. The first 16 P[*] blocks correspond to the 64 888 Differentiated Service Code Point (DSCP) values P[00] - P[63] 889 [RFC2474]. Any additional P[*] blocks that follow correspond 890 to "pseudo-DSCP" traffic classifier values P[64], P[65], P[66], 891 etc. See Appendix A for further discussion and examples. 893 * Each 2-bit P[*] field is set to the value '0' ("disabled"), '1' 894 ("low"), '2' ("medium") or '3' ("high") to indicate a QoS 895 preference level for underlying interface selection purposes. 896 Not all P[*] values need to be included in all OMNI option 897 instances of a given ifIndex-tuple. Any P[*] values 898 represented in an earlier OMNI option but omitted in the 899 current OMNI option remain unchanged. Any P[*] values not yet 900 represented in any OMNI option default to "medium". 902 9.1.4. ifIndex-tuple (Type 2) 904 0 1 2 3 905 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 1 906 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 907 | Sub-Type=3 | Sub-length=4+N| ifIndex | ifType | 908 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 909 | Provider ID | Link |S|Resvd| ~ 910 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 911 ~ ~ 912 ~ RFC 6088 Format Traffic Selector ~ 913 ~ ~ 914 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 916 Figure 10: ifIndex-tuple (Type 2) 918 o Sub-Type is set to 3. 920 o Sub-Length is set to 4+N (the number of Sub-Option Data bytes that 921 follow). 923 o Sub-Option Data contains an "ifIndex-tuple" (Type 2) encoded as 924 follows (note that the first four bytes must be present): 926 * ifIndex, ifType, Provider ID, Link and S are set exactly as for 927 Type 1 ifIndex-tuples as specified in Section 9.1.3. 929 * the remainder of the Sub-Option body encodes a variable-length 930 traffic selector formatted per [RFC6088], beginning with the 931 "TS Format" field. 933 9.1.5. MS-Register 935 0 1 2 3 936 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 1 937 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 938 | Sub-Type=4 | Sub-length=4 | MSID (bits 0 - 15) | 939 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 940 | MSID (bits 16 - 32) | 941 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 943 Figure 11: MS-Register Sub-option 945 o Sub-Type is set to 4. 947 o Sub-Length is set to 4. 949 o MSID contains the 32 bit ID of an MSE or AR, in network byte 950 order. OMNI options contain zero or more MS-Register sub-options. 952 9.1.6. MS-Release 954 0 1 2 3 955 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 1 956 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 957 | Sub-Type=5 | Sub-length=4 | MSID (bits 0 - 15) | 958 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 959 | MSID (bits 16 - 32) | 960 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 962 Figure 12: MS-Release Sub-option 964 o Sub-Type is set to 5. 966 o Sub-Length is set to 4. 968 o MSIID contains the 32 bit ID of an MS or AR, in network byte 969 order. OMNI options contain zero or more MS-Release sub-options. 971 9.1.7. Network Access Identifier (NAI) 973 0 1 2 3 974 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 1 975 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 976 | Sub-Type=6 | Sub-length=N |Network Access Identifier (NAI) 977 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... 979 Figure 13: Network Access Identifier (NAI) Sub-option 981 o Sub-Type is set to 6. 983 o Sub-Length is set to N. 985 o Network Access Identifier (NAI) is coded per [RFC7542], and is up 986 to 253 bytes in length. 988 9.1.8. Geo Coordiantes 989 0 1 2 3 990 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 1 991 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 992 | Sub-Type=7 | Sub-length=N | Geo Coordinates 993 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... 995 Figure 14: Geo Coordinates Sub-option 997 o Sub-Type is set to 7. 999 o Sub-Length is set to N. 1001 o A set of Geo Coordinates up to 253 bytes in length (format TBD). 1002 Includes Latitude/Longitude at a minimum; may also include 1003 additional attributes such as altitude, heading, speed, etc.). 1005 10. Address Mapping - Multicast 1007 The multicast address mapping of the native underlying interface 1008 applies. The mobile router on board the MN also serves as an IGMP/ 1009 MLD Proxy for its EUNs and/or hosted applications per [RFC4605] while 1010 using the L2 address of the AR as the L2 address for all multicast 1011 packets. 1013 The MN uses Multicast Listener Discovery (MLDv2) [RFC3810] to 1014 coordinate with the AR, and ANET L2 elements use MLD snooping 1015 [RFC4541]. 1017 11. Conceptual Sending Algorithm 1019 The MN's IPv6 layer selects the outbound OMNI interface according to 1020 SBM considerations when forwarding data packets from local or EUN 1021 applications to external correspondents. Each OMNI interface 1022 maintains a neighbor cache the same as for any IPv6 interface, but 1023 with additional state for multilink coordination. 1025 After a packet enters the OMNI interface, an outbound underlying 1026 interface is selected based on PBM traffic selectors such as DSCP, 1027 application port number, cost, performance, message size, etc. OMNI 1028 interface multilink selections could also be configured to perform 1029 replication across multiple underlying interfaces for increased 1030 reliability at the expense of packet duplication. 1032 When an OMNI interface sends a packet over a selected outbound 1033 underlying interface, it omits OMNI link encapsulation if the packet 1034 does not require fragmentation and the neighbor can determine the 1035 OMNI ULAs through other means (e.g., the packet's destination, 1036 neighbor cache information, etc.). Otherwise, the OMNI interface 1037 inserts an IPv6 header with the OMNI ULAs and performs fragmentation 1038 if necessary. The OMNI interface also performs enacpsulation when 1039 the nearest AR is located multiple hops away as discussed in 1040 Section 12.1. 1042 OMNI interface multilink service designers MUST observe the BCP 1043 guidance in Section 15 [RFC3819] in terms of implications for 1044 reordering when packets from the same flow may be spread across 1045 multiple underlying interfaces having diverse properties. 1047 11.1. Multiple OMNI Interfaces 1049 MNs may connect to multiple independent OMNI links concurrently in 1050 support of SBM. Each OMNI interface is distinguished by its Anycast 1051 OMNI ULA (e.g., fc80::, fc81::, fc82::). The MN configures a 1052 separate OMNI interface for each link so that multiple interfaces 1053 (e.g., omni0, omni1, omni2, etc.) are exposed to the IPv6 layer. A 1054 different Anycast OMNI ULA is assigned to each interface, and the MN 1055 injects the service prefixes for the OMNI link instances into the EUN 1056 routing system. 1058 Applications in EUNs can use Segment Routing to select the desired 1059 OMNI interface based on SBM considerations. The Anycast OMNI ULA is 1060 written into the IPv6 destination address, and the actual destination 1061 (along with any additional intermediate hops) is written into the 1062 Segment Routing Header. Standard IP routing directs the packets to 1063 the MN's mobile router entity, and the Anycast OMNI ULA identifies 1064 the OMNI interface to be used for transmission to the next hop. When 1065 the MN receives the message, it replaces the IPv6 destination address 1066 with the next hop found in the routing header and transmits the 1067 message over the OMNI interface identified by the Anycast OMNI ULA. 1069 Multiple distinct OMNI links can therefore be used to support fault 1070 tolerance, load balancing, reliability, etc. The architectural model 1071 is similar to Layer 2 Virtual Local Area Networks (VLANs). 1073 12. Router Discovery and Prefix Registration 1075 MNs interface with the MS by sending RS messages with OMNI options 1076 under the assumption that a single AR on the ANET will process the 1077 message and respond. This places a requirement on each ANET, which 1078 may be enforced by physical/logical partitioning, L2 AR beaconing, 1079 etc. The manner in which the ANET ensures single AR coordination is 1080 link-specific and outside the scope of this document. 1082 For each underlying interface, the MN sends an RS message with an 1083 OMNI option with prefix registration information, ifIndex-tuples, MS- 1084 Register/Release suboptions containing MSIDs, and with destination 1085 address set to link-scoped All-Routers multicast (ff02::2) [RFC4291]. 1086 Example MSID discovery methods are given in [RFC5214], including data 1087 link login parameters, name service lookups, static configuration, 1088 etc. Alternatively, MNs can discover individual MSIDs by sending an 1089 initial RS with MS-Register MSID set to 0x00000000. 1091 MNs configure OMNI interfaces that observe the properties discussed 1092 in the previous section. The OMNI interface and its underlying 1093 interfaces are said to be in either the "UP" or "DOWN" state 1094 according to administrative actions in conjunction with the interface 1095 connectivity status. An OMNI interface transitions to UP or DOWN 1096 through administrative action and/or through state transitions of the 1097 underlying interfaces. When a first underlying interface transitions 1098 to UP, the OMNI interface also transitions to UP. When all 1099 underlying interfaces transition to DOWN, the OMNI interface also 1100 transitions to DOWN. 1102 When an OMNI interface transitions to UP, the MN sends RS messages to 1103 register its MNP and an initial set of underlying interfaces that are 1104 also UP. The MN sends additional RS messages to refresh lifetimes 1105 and to register/deregister underlying interfaces as they transition 1106 to UP or DOWN. The MN sends initial RS messages over an UP 1107 underlying interface with its OMNI LLA as the source and with 1108 destination set to All-Routers multicast. The RS messages include an 1109 OMNI option per Section 9 with valid prefix registration information, 1110 ifIndex-tuples appropriate for underlying interfaces and MS-Register/ 1111 Release sub-options. 1113 ARs process IPv6 ND messages with OMNI options and act as a proxy for 1114 MSEs. ARs receive RS messages and create a neighbor cache entry for 1115 the MN, then coordinate with any named MSIDs in a manner outside the 1116 scope of this document. The AR returns an RA message with 1117 destination address set to the MN OMNI LLA (i.e., unicast), with 1118 source address set to its MS OMNI LLA, with the P(roxy) bit set in 1119 the RA flags [RFC4389][RFC5175], with an OMNI option with valid 1120 prefix registration information, ifIndex-tuples, MS-Register/Release 1121 sub-options, and with any information for the link that would 1122 normally be delivered in a solicited RA message. ARs return RA 1123 messages with configuration information in response to a MN's RS 1124 messages. The AR sets the RA Cur Hop Limit, M and O flags, Router 1125 Lifetime, Reachable Time and Retrans Timer values, and includes any 1126 necessary options such as: 1128 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 1130 o RIOs [RFC4191] with more-specific routes. 1132 o an MTU option that specifies the maximum acceptable packet size 1133 for this ANET interface. 1135 The AR coordinates with each Register/Release MSID then sends an 1136 immediate unicast RA response without delay; therefore, the IPv6 ND 1137 MAX_RA_DELAY_TIME and MIN_DELAY_BETWEEN_RAS constants for multicast 1138 RAs do not apply. The AR MAY send periodic and/or event-driven 1139 unsolicited RA messages according to the standard [RFC4861]. 1141 When the MSE processes the OMNI information, it first validates the 1142 prefix registration information. The MSE then injects/withdraws the 1143 MNP in the routing/mapping system and caches/discards the new Prefix 1144 Length, MNP and ifIndex-tuples. The MSE then informs the AR of 1145 registration success/failure, and the AR adds the MSE to the list of 1146 Register/Release MSIDs to return in an RA message OMNI option per 1147 Section 9. 1149 When the MN receives the RA message, it creates an OMNI interface 1150 neighbor cache entry with the AR's address as an L2 address and 1151 records the MSIDs that have confirmed MNP registration via this AR. 1152 If the MN connects to multiple ANETs, it establishes additional AR L2 1153 addresses (i.e., as a Multilink neighbor). The MN then manages its 1154 underlying interfaces according to their states as follows: 1156 o When an underlying interface transitions to UP, the MN sends an RS 1157 over the underlying interface with an OMNI option with R set to 1. 1158 The OMNI option contains at least one ifIndex-tuple with values 1159 specific to this underlying interface, and may contain additional 1160 ifIndex-tuples specific to this and/or other underlying 1161 interfaces. The option also includes any Register/Release MSIDs. 1163 o When an underlying interface transitions to DOWN, the MN sends an 1164 RS or unsolicited NA message over any UP underlying interface with 1165 an OMNI option containing an ifIndex-tuple for the DOWN underlying 1166 interface with Link set to '0'. The MN sends an RS when an 1167 acknowledgement is required, or an unsolicited NA when reliability 1168 is not thought to be a concern (e.g., if redundant transmissions 1169 are sent on multiple underlying interfaces). 1171 o When the Router Lifetime for a specific AR nears expiration, the 1172 MN sends an RS over the underlying interface to receive a fresh 1173 RA. If no RA is received, the MN marks the underlying interface 1174 as DOWN. 1176 o When a MN wishes to release from one or more current MSIDs, it 1177 sends an RS or unsolicited NA message over any UP underlying 1178 interfaces with an OMNI option with a Release MSID. Each MSID 1179 then withdraws the MNP from the routing/mapping system and informs 1180 the AR that the release was successful. 1182 o When all of a MNs underlying interfaces have transitioned to DOWN 1183 (or if the prefix registration lifetime expires), any associated 1184 MSEs withdraw the MNP the same as if they had received a message 1185 with a release indication. 1187 The MN is responsible for retrying each RS exchange up to 1188 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 1189 seconds until an RA is received. If no RA is received over a an UP 1190 underlying interface, the MN declares this underlying interface as 1191 DOWN. 1193 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 1194 Therefore, when the IPv6 layer sends an RS message the OMNI interface 1195 returns an internally-generated RA message as though the message 1196 originated from an IPv6 router. The internally-generated RA message 1197 contains configuration information that is consistent with the 1198 information received from the RAs generated by the MS. Whether the 1199 OMNI interface IPv6 ND messaging process is initiated from the 1200 receipt of an RS message from the IPv6 layer is an implementation 1201 matter. Some implementations may elect to defer the IPv6 ND 1202 messaging process until an RS is received from the IPv6 layer, while 1203 others may elect to initiate the process proactively. 1205 Note: The Router Lifetime value in RA messages indicates the time 1206 before which the MN must send another RS message over this underlying 1207 interface (e.g., 600 seconds), however that timescale may be 1208 significantly longer than the lifetime the MS has committed to retain 1209 the prefix registration (e.g., REACHABLETIME seconds). ARs are 1210 therefore responsible for keeping MS state alive on a shorter 1211 timescale than the MN is required to do on its own behalf. 1213 Note: On multicast-capable underlying interfaces, MNs should send 1214 periodic unsolicited multicast NA messages and ARs should send 1215 periodic unsolicited multicast RA messages as "beacons" that can be 1216 heard by other nodes on the link. If a node fails to receive a 1217 beacon after a timeout value specific to the link, it can initiate a 1218 unicast exchange to test reachability. 1220 12.1. Multihop Router Discovery 1222 On some ANET types (e.g., omni-directional ad-hoc wireless) a MN may 1223 be located multiple hops away from a node which has connectivity to 1224 the nearest AR. Forwarding through these multiple hops would be 1225 conducted through the application of a Mobile Ad-hoc Network (MANET) 1226 routing protocol operating across the ANET interfaces. 1228 A MN located potentially multiple ANET hops away from the nearst AR 1229 prepares an RS message as normal then encapsulates the message in an 1230 IPv6 header with source address set to the ULA corresponding to the 1231 RS LLA source address, and with destination set to site-scoped All- 1232 Routers multicast (ff05::2)[RFC4291]. The MN then sends the 1233 encapsulated RS message via the ANET interface, where it will be 1234 received by zero or more nearby intermediate MNs. 1236 When an intermediate MN that particpates in the MANET routing 1237 protocol receives the encapsulated RS, it forwards the message 1238 according to its (ULA-based) MANET routing tables. This process 1239 repeats iteratively until the RS message is received by an ultimate 1240 MN that is within communications range of an AR, which forwards the 1241 message to the AR. 1243 When the AR receives the RS message, it coordinates with the MS the 1244 same as if the message were received as an ordinary link-local RS, 1245 since the inner Hop Limit will not have been decremented by the MANET 1246 multihop forwarding process. The AR then prepares an RA message with 1247 source address set to its own LLA and destination address set to the 1248 LLA of the original MN, then encapsulates the message in an IPv6 1249 header with source and destination set to the ULAs corresponding to 1250 the inner header. 1252 The AR then forwards the message to an MN within communications 1253 range, which forwards the message according to its MANET routing 1254 tables to an intermediate MN. The MANET forwarding process continues 1255 repetitively until the message is delivered to the original MN, which 1256 decapsulates the message and performs autoconfiguration the same as 1257 if it had received the RA directly from an AR. 1259 Note: An alternate approach to encapsulation of IPv6 ND messages for 1260 multihop forwarding would be to statelessly translate the IPv6 LLAs 1261 into ULAs and forward the messages without encapsulation. This would 1262 violate the [RFC4861] requirement that certain IPv6 ND messages must 1263 use link-local addresses and must not be accepted if received with 1264 Hop Limit less than 255. This document therefore advocates 1265 encapsulation since the overhead is nominal considering the 1266 infrequent nature and small size of IPv6 ND messages. Future 1267 documents may consider encapsulation avoidance through translation 1268 while updating [RFC4861]. 1270 13. Secure Redirection 1272 If the ANET link model is multiple access, the AR is responsible for 1273 assuring that address duplication cannot corrupt the neighbor caches 1274 of other nodes on the link. When the MN sends an RS message on a 1275 multiple access ANET link, the AR verifies that the MN is authorized 1276 to use the address and returns an RA with a non-zero Router Lifetime 1277 only if the MN is authorized. 1279 After verifying MN authorization and returning an RA, the AR MAY 1280 return IPv6 ND Redirect messages to direct MNs located on the same 1281 ANET link to exchange packets directly without transiting the AR. In 1282 that case, the MNs can exchange packets according to their unicast L2 1283 addresses discovered from the Redirect message instead of using the 1284 dogleg path through the AR. In some ANET links, however, such direct 1285 communications may be undesirable and continued use of the dogleg 1286 path through the AR may provide better performance. In that case, 1287 the AR can refrain from sending Redirects, and/or MNs can ignore 1288 them. 1290 14. AR and MSE Resilience 1292 ANETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 1293 [RFC5798] configurations so that service continuity is maintained 1294 even if one or more ARs fail. Using VRRP, the MN is unaware which of 1295 the (redundant) ARs is currently providing service, and any service 1296 discontinuity will be limited to the failover time supported by VRRP. 1297 Widely deployed public domain implementations of VRRP are available. 1299 MSEs SHOULD use high availability clustering services so that 1300 multiple redundant systems can provide coordinated response to 1301 failures. As with VRRP, widely deployed public domain 1302 implementations of high availability clustering services are 1303 available. Note that special-purpose and expensive dedicated 1304 hardware is not necessary, and public domain implementations can be 1305 used even between lightweight virtual machines in cloud deployments. 1307 15. Detecting and Responding to MSE Failures 1309 In environments where fast recovery from MSE failure is required, ARs 1310 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 1311 manner that parallels Bidirectional Forwarding Detection (BFD) 1312 [RFC5880] to track MSE reachability. ARs can then quickly detect and 1313 react to failures so that cached information is re-established 1314 through alternate paths. Proactive NUD control messaging is carried 1315 only over well-connected ground domain networks (i.e., and not low- 1316 end ANET links such as aeronautical radios) and can therefore be 1317 tuned for rapid response. 1319 ARs perform proactive NUD for MSEs for which there are currently 1320 active MNs on the ANET. If an MSE fails, ARs can quickly inform MNs 1321 of the outage by sending multicast RA messages on the ANET interface. 1322 The AR sends RA messages to MNs via the ANET interface with an OMNI 1323 option with a Release ID for the failed MSE, and with destination 1324 address set to All-Nodes multicast (ff02::1) [RFC4291]. 1326 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 1327 by small delays [RFC4861]. Any MNs on the ANET interface that have 1328 been using the (now defunct) MSE will receive the RA messages and 1329 associate with a new MSE. 1331 16. Transition Considerations 1333 When a MN connects to an ANET link for the first time, it sends an RS 1334 message with an OMNI option. If the first hop AR recognizes the 1335 option, it returns an RA with its MS OMNI LLA as the source, the MN 1336 OMNI LLA as the destination, the P(roxy) bit set in the RA flags and 1337 with an OMNI option included. The MN then engages the AR according 1338 to the OMNI link model specified above. If the first hop AR is a 1339 legacy IPv6 router, however, it instead returns an RA message with no 1340 OMNI option and with a non-OMNI unicast source LLA as specified in 1341 [RFC4861]. In that case, the MN engages the ANET according to the 1342 legacy IPv6 link model and without the OMNI extensions specified in 1343 this document. 1345 If the ANET link model is multiple access, there must be assurance 1346 that address duplication cannot corrupt the neighbor caches of other 1347 nodes on the link. When the MN sends an RS message on a multiple 1348 access ANET link with an OMNI LLA source address and an OMNI option, 1349 ARs that recognize the option ensure that the MN is authorized to use 1350 the address and return an RA with a non-zero Router Lifetime only if 1351 the MN is authorized. ARs that do not recognize the option instead 1352 return an RA that makes no statement about the MN's authorization to 1353 use the source address. In that case, the MN should perform 1354 Duplicate Address Detection to ensure that it does not interfere with 1355 other nodes on the link. 1357 An alternative approach for multiple access ANET links to ensure 1358 isolation for MN / AR communications is through L2 address mappings 1359 as discussed in Appendix C. This arrangement imparts a (virtual) 1360 point-to-point link model over the (physical) multiple access link. 1362 17. OMNI Interfaces on the Open Internet 1364 OMNI interfaces configured over INET interfaces that connect to the 1365 open Internet can apply symmetric security services such as VPNs or 1366 establish a direct link through some other means. In environments 1367 where an explicit VPN or direct link may be impractical, OMNI 1368 interfaces can instead use Teredo UDP/IP encapsulation 1369 [RFC6081][RFC4380]. (SEcure Neighbor Discovery (SEND) and 1370 Cryptographically Generated Addresses (CGA) [RFC3971][RFC3972] can 1371 also be used if additional authentication is necessary.) 1373 The IPv6 ND control plane messages used to establish neighbor cache 1374 state must be authenticated while data plane messages are delivered 1375 the same as for ordinary best-effort Internet traffic with basic 1376 source address-based data origin verification. Data plane 1377 communications via OMNI interfaces that connect over the open 1378 Internet without an explicit VPN should therefore employ transport- 1379 or higher-layer security to ensure integrity and/or confidentiality. 1381 OMNI interfaces in the open Internet are often located behind Network 1382 Address Translators (NATs). The OMNI interface accommodates NAT 1383 traversal using UDP/IP encapsulation and the mechanisms discussed in 1384 [RFC6081][RFC4380][I-D.templin-intarea-6706bis]. 1386 18. Time-Varying MNPs 1388 In some use cases, it is desirable, beneficial and efficient for the 1389 MN to receive a constant MNP that travels with the MN wherever it 1390 moves. For example, this would allow air traffic controllers to 1391 easily track aircraft, etc. In other cases, however (e.g., 1392 intelligent transportation systems), the MN may be willing to 1393 sacrifice a modicum of efficiency in order to have time-varying MNPs 1394 that can be changed every so often to defeat adversarial tracking. 1396 Prefix delegation services such as those discussed in 1397 [I-D.templin-6man-dhcpv6-ndopt] and [I-D.templin-intarea-6706bis] 1398 allow OMNI MNs that desire time-varying MNPs to obtain short-lived 1399 prefixes. In that case, the identity of the MN can be used as a 1400 prefix delegation seed (e.g., a DHCPv6 Device Unique IDentifier 1401 (DUID) [RFC8415]). The MN would then be obligated to renumber its 1402 internal networks whenever its MNP (and therefore also its OMNI 1403 address) changes. This should not present a challenge for MNs with 1404 automated network renumbering services, however presents limits for 1405 the durations of ongoing sessions that would prefer to use a constant 1406 address. 1408 19. IANA Considerations 1410 The IANA is instructed to allocate an official Type number TBD from 1411 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 1412 option. Implementations set Type to 253 as an interim value 1413 [RFC4727]. 1415 The IANA is instructed to assign a new Code value "1" in the "ICMPv6 1416 Code Fields: Type 2 - Packet Too Big" registry. The registry should 1417 read as follows: 1419 Code Name Reference 1420 --- ---- --------- 1421 0 Diagnostic Packet Too Big [RFC4443] 1422 1 Advisory Packet Too Big [RFCXXXX] 1424 Figure 15: OMNI Option Sub-Type Values 1426 The IANA is instructed to allocate one Ethernet unicast address TBD2 1427 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 1428 Address Block - Unicast Use". 1430 The OMNI option also defines an 8-bit Sub-Type field, for which IANA 1431 is instructed to create and maintain a new registry entitled "OMNI 1432 option Sub-Type values". Initial values for the OMNI option Sub-Type 1433 values registry are given below; future assignments are to be made 1434 through Expert Review [RFC8126]. 1436 Value Sub-Type name Reference 1437 ----- ------------- ---------- 1438 0 Pad1 [RFCXXXX] 1439 1 PadN [RFCXXXX] 1440 2 ifIndex-tuple (Type 1) [RFCXXXX] 1441 3 ifIndex-tuple (Type 2) [RFCXXXX] 1442 4 MS-Register [RFCXXXX] 1443 5 MS-Release [RFCXXXX] 1444 6 Network Acceess Identifier [RFCXXXX] 1445 7 Geo Coordinates [RFCXXXX] 1446 8-252 Unassigned 1447 253-254 Experimental [RFCXXXX] 1448 255 Reserved [RFCXXXX] 1450 Figure 16: OMNI Option Sub-Type Values 1452 20. Security Considerations 1454 Security considerations for IPv6 [RFC8200] and IPv6 Neighbor 1455 Discovery [RFC4861] apply. OMNI interface IPv6 ND messages SHOULD 1456 include Nonce and Timestamp options [RFC3971] when transaction 1457 confirmation and/or time synchronization is needed. 1459 OMNI interfaces configured over secured ANET interfaces inherit the 1460 physical and/or link-layer security properties of the connected 1461 ANETs. OMNI interfaces configured over open INET interfaces can use 1462 symmetric securing services such as VPNs or can by some other means 1463 establish a direct link. When a VPN or direct link may be 1464 impractical, however, an asymmetric security service such as SEcure 1465 Neighbor Discovery (SEND) [RFC3971] with Cryptographically Generated 1466 Addresses (CGAs) [RFC3972] and/or the Teredo Authentication option 1467 [RFC4380] may be necessary. 1469 While the OMNI link protects control plane messaging as discussed 1470 above, applications should still employ transport- or higher-layer 1471 security services to protect the data plane. 1473 Security considerations for specific access network interface types 1474 are covered under the corresponding IP-over-(foo) specification 1475 (e.g., [RFC2464], [RFC2492], etc.). 1477 Security considerations for IPv6 fragmentation and reassembly are 1478 discussed in Section 5.1. 1480 21. Acknowledgements 1482 The first version of this document was prepared per the consensus 1483 decision at the 7th Conference of the International Civil Aviation 1484 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 1485 2019. Consensus to take the document forward to the IETF was reached 1486 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 1487 Attendees and contributors included: Guray Acar, Danny Bharj, 1488 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 1489 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 1490 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 1491 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 1492 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 1493 Fryderyk Wrobel and Dongsong Zeng. 1495 The following individuals are acknowledged for their useful comments: 1496 Michael Matyas, Madhu Niraula, Greg Saccone, Stephane Tamalet, Eric 1497 Vyncke. Pavel Drasil, Zdenek Jaron and Michal Skorepa are recognized 1498 for their many helpful ideas and suggestions. 1500 This work is aligned with the NASA Safe Autonomous Systems Operation 1501 (SASO) program under NASA contract number NNA16BD84C. 1503 This work is aligned with the FAA as per the SE2025 contract number 1504 DTFAWA-15-D-00030. 1506 22. References 1508 22.1. Normative References 1510 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1511 Requirement Levels", BCP 14, RFC 2119, 1512 DOI 10.17487/RFC2119, March 1997, 1513 . 1515 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1516 "Definition of the Differentiated Services Field (DS 1517 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1518 DOI 10.17487/RFC2474, December 1998, 1519 . 1521 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 1522 "SEcure Neighbor Discovery (SEND)", RFC 3971, 1523 DOI 10.17487/RFC3971, March 2005, 1524 . 1526 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 1527 RFC 3972, DOI 10.17487/RFC3972, March 2005, 1528 . 1530 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 1531 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 1532 November 2005, . 1534 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 1535 Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005, 1536 . 1538 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 1539 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 1540 2006, . 1542 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 1543 Control Message Protocol (ICMPv6) for the Internet 1544 Protocol Version 6 (IPv6) Specification", STD 89, 1545 RFC 4443, DOI 10.17487/RFC4443, March 2006, 1546 . 1548 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 1549 ICMPv6, UDP, and TCP Headers", RFC 4727, 1550 DOI 10.17487/RFC4727, November 2006, 1551 . 1553 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 1554 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 1555 DOI 10.17487/RFC4861, September 2007, 1556 . 1558 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 1559 Address Autoconfiguration", RFC 4862, 1560 DOI 10.17487/RFC4862, September 2007, 1561 . 1563 [RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont, 1564 "Traffic Selectors for Flow Bindings", RFC 6088, 1565 DOI 10.17487/RFC6088, January 2011, 1566 . 1568 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 1569 Hosts in a Multi-Prefix Network", RFC 8028, 1570 DOI 10.17487/RFC8028, November 2016, 1571 . 1573 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1574 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1575 May 2017, . 1577 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1578 (IPv6) Specification", STD 86, RFC 8200, 1579 DOI 10.17487/RFC8200, July 2017, 1580 . 1582 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 1583 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 1584 DOI 10.17487/RFC8201, July 2017, 1585 . 1587 22.2. Informative References 1589 [I-D.ietf-intarea-frag-fragile] 1590 Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O., 1591 and F. Gont, "IP Fragmentation Considered Fragile", draft- 1592 ietf-intarea-frag-fragile-17 (work in progress), September 1593 2019. 1595 [I-D.ietf-intarea-tunnels] 1596 Touch, J. and M. Townsley, "IP Tunnels in the Internet 1597 Architecture", draft-ietf-intarea-tunnels-10 (work in 1598 progress), September 2019. 1600 [I-D.templin-6man-dhcpv6-ndopt] 1601 Templin, F., "A Unified Stateful/Stateless Configuration 1602 Service for IPv6", draft-templin-6man-dhcpv6-ndopt-09 1603 (work in progress), January 2020. 1605 [I-D.templin-intarea-6706bis] 1606 Templin, F., "Asymmetric Extended Route Optimization 1607 (AERO)", draft-templin-intarea-6706bis-52 (work in 1608 progress), May 2020. 1610 [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - 1611 Communication Layers", STD 3, RFC 1122, 1612 DOI 10.17487/RFC1122, October 1989, 1613 . 1615 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 1616 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 1617 . 1619 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 1620 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 1621 . 1623 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 1624 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 1625 December 1998, . 1627 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 1628 Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999, 1629 . 1631 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 1632 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 1633 . 1635 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 1636 Considered Useful", BCP 82, RFC 3692, 1637 DOI 10.17487/RFC3692, January 2004, 1638 . 1640 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 1641 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 1642 DOI 10.17487/RFC3810, June 2004, 1643 . 1645 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 1646 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 1647 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 1648 RFC 3819, DOI 10.17487/RFC3819, July 2004, 1649 . 1651 [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through 1652 Network Address Translations (NATs)", RFC 4380, 1653 DOI 10.17487/RFC4380, February 2006, 1654 . 1656 [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery 1657 Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April 1658 2006, . 1660 [RFC4541] Christensen, M., Kimball, K., and F. Solensky, 1661 "Considerations for Internet Group Management Protocol 1662 (IGMP) and Multicast Listener Discovery (MLD) Snooping 1663 Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006, 1664 . 1666 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 1667 "Internet Group Management Protocol (IGMP) / Multicast 1668 Listener Discovery (MLD)-Based Multicast Forwarding 1669 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 1670 August 2006, . 1672 [RFC4963] Heffner, J., Mathis, M., and B. Chandler, "IPv4 Reassembly 1673 Errors at High Data Rates", RFC 4963, 1674 DOI 10.17487/RFC4963, July 2007, 1675 . 1677 [RFC5175] Haberman, B., Ed. and R. Hinden, "IPv6 Router 1678 Advertisement Flags Option", RFC 5175, 1679 DOI 10.17487/RFC5175, March 2008, 1680 . 1682 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 1683 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 1684 RFC 5213, DOI 10.17487/RFC5213, August 2008, 1685 . 1687 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 1688 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 1689 DOI 10.17487/RFC5214, March 2008, 1690 . 1692 [RFC5558] Templin, F., Ed., "Virtual Enterprise Traversal (VET)", 1693 RFC 5558, DOI 10.17487/RFC5558, February 2010, 1694 . 1696 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 1697 Version 3 for IPv4 and IPv6", RFC 5798, 1698 DOI 10.17487/RFC5798, March 2010, 1699 . 1701 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 1702 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 1703 . 1705 [RFC6081] Thaler, D., "Teredo Extensions", RFC 6081, 1706 DOI 10.17487/RFC6081, January 2011, 1707 . 1709 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 1710 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 1711 2012, . 1713 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 1714 Requirements for IPv6 Customer Edge Routers", RFC 7084, 1715 DOI 10.17487/RFC7084, November 2013, 1716 . 1718 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 1719 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 1720 Boundary in IPv6 Addressing", RFC 7421, 1721 DOI 10.17487/RFC7421, January 2015, 1722 . 1724 [RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542, 1725 DOI 10.17487/RFC7542, May 2015, 1726 . 1728 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 1729 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 1730 February 2016, . 1732 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 1733 Support for IP Hosts with Multi-Access Support", RFC 7847, 1734 DOI 10.17487/RFC7847, May 2016, 1735 . 1737 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1738 Writing an IANA Considerations Section in RFCs", BCP 26, 1739 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1740 . 1742 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1743 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1744 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1745 July 2018, . 1747 [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., 1748 Richardson, M., Jiang, S., Lemon, T., and T. Winters, 1749 "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", 1750 RFC 8415, DOI 10.17487/RFC8415, November 2018, 1751 . 1753 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 1754 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 1755 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 1756 . 1758 Appendix A. Type 1 ifIndex-tuple Traffic Classifier Preference Encoding 1760 Adaptation of the OMNI option Type 1 ifIndex-tuple's traffic 1761 classifier Bitmap to specific Internetworks such as the Aeronautical 1762 Telecommunications Network with Internet Protocol Services (ATN/IPS) 1763 may include link selection preferences based on other traffic 1764 classifiers (e.g., transport port numbers, etc.) in addition to the 1765 existing DSCP-based preferences. Nodes on specific Internetworks 1766 maintain a map of traffic classifiers to additional P[*] preference 1767 fields beyond the first 64. For example, TCP port 22 maps to P[67], 1768 TCP port 443 maps to P[70], UDP port 8060 maps to P[76], etc. 1770 Implementations use Simplex or Indexed encoding formats for P[*] 1771 encoding in order to encode a given set of traffic classifiers in the 1772 most efficient way. Some use cases may be more efficiently coded 1773 using Simplex form, while others may be more efficient using Indexed. 1774 Once a format is selected for preparation of a single ifIndex-tuple 1775 the same format must be used for the entire Sub-Option. Different 1776 Sub-Options may use different formats. 1778 The following figures show coding examples for various Simplex and 1779 Indexed formats: 1781 0 1 2 3 1782 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 1783 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1784 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 1785 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1786 | Provider ID | Link |S|0|RSV| Bitmap(0)=0xff|P00|P01|P02|P03| 1787 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1788 |P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19| 1789 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1790 |P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| Bitmap(1)=0xff| 1791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1792 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 1793 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1794 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1795 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1796 | Bitmap(2)=0xff|P64|P65|P67|P68| ... 1797 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1799 Figure 17: Example 1: Dense Simplex Encoding 1801 0 1 2 3 1802 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 1803 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1804 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 1805 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1806 | Provider ID | Link |S|0|RSV| Bitmap(0)=0x00| Bitmap(1)=0x0f| 1807 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1808 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 1809 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1810 | Bitmap(2)=0x00| Bitmap(3)=0x00| Bitmap(4)=0x00| Bitmap(5)=0x00| 1811 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1812 | Bitmap(6)=0xf0|192|193|194|195|196|197|198|199|200|201|202|203| 1813 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1814 |204|205|206|207| Bitmap(7)=0x00| Bitmap(8)=0x0f|272|273|274|275| 1815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1816 |276|277|278|279|280|281|282|283|284|285|286|287| Bitmap(9)=0x00| 1817 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1818 |Bitmap(10)=0x00| ... 1819 +-+-+-+-+-+-+-+-+-+-+- 1821 Figure 18: Example 2: Sparse Simplex Encoding 1823 0 1 2 3 1824 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 1825 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1826 | Sub-Type=2 | Sub-length=4+N| ifIndex | ifType | 1827 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1828 | Provider ID | Link |S|1|RSV| Index = 0x00 | Bitmap = 0x80 | 1829 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1830 |P00|P01|P02|P03| Index = 0x01 | Bitmap = 0x01 |P60|P61|P62|P63| 1831 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1832 | Index = 0x10 | Bitmap = 0x80 |512|513|514|515| Index = 0x18 | 1833 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1834 | Bitmap = 0x01 |796|797|798|799| ... 1835 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1837 Figure 19: Example 3: Indexed Encoding 1839 Appendix B. VDL Mode 2 Considerations 1841 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 1842 (VDLM2) that specifies an essential radio frequency data link service 1843 for aircraft and ground stations in worldwide civil aviation air 1844 traffic management. The VDLM2 link type is "multicast capable" 1845 [RFC4861], but with considerable differences from common multicast 1846 links such as Ethernet and IEEE 802.11. 1848 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 1849 magnitude less than most modern wireless networking gear. Second, 1850 due to the low available link bandwidth only VDLM2 ground stations 1851 (i.e., and not aircraft) are permitted to send broadcasts, and even 1852 so only as compact layer 2 "beacons". Third, aircraft employ the 1853 services of ground stations by performing unicast RS/RA exchanges 1854 upon receipt of beacons instead of listening for multicast RA 1855 messages and/or sending multicast RS messages. 1857 This beacon-oriented unicast RS/RA approach is necessary to conserve 1858 the already-scarce available link bandwidth. Moreover, since the 1859 numbers of beaconing ground stations operating within a given spatial 1860 range must be kept as sparse as possible, it would not be feasible to 1861 have different classes of ground stations within the same region 1862 observing different protocols. It is therefore highly desirable that 1863 all ground stations observe a common language of RS/RA as specified 1864 in this document. 1866 Note that links of this nature may benefit from compression 1867 techniques that reduce the bandwidth necessary for conveying the same 1868 amount of data. The IETF lpwan working group is considering possible 1869 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 1871 Appendix C. MN / AR Isolation Through L2 Address Mapping 1873 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 1874 unicast link-scoped IPv6 destination address. However, IPv6 ND 1875 messaging should be coordinated between the MN and AR only without 1876 invoking other nodes on the ANET. This implies that MN / AR control 1877 messaging should be isolated and not overheard by other nodes on the 1878 link. 1880 To support MN / AR isolation on some ANET links, ARs can maintain an 1881 OMNI-specific unicast L2 address ("MSADDR"). For Ethernet-compatible 1882 ANETs, this specification reserves one Ethernet unicast address TBD2 1883 (see: Section 19). For non-Ethernet statically-addressed ANETs, 1884 MSADDR is reserved per the assigned numbers authority for the ANET 1885 addressing space. For still other ANETs, MSADDR may be dynamically 1886 discovered through other means, e.g., L2 beacons. 1888 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 1889 both multicast and unicast) to MSADDR instead of to an ordinary 1890 unicast or multicast L2 address. In this way, all of the MN's IPv6 1891 ND messages will be received by ARs that are configured to accept 1892 packets destined to MSADDR. Note that multiple ARs on the link could 1893 be configured to accept packets destined to MSADDR, e.g., as a basis 1894 for supporting redundancy. 1896 Therefore, ARs must accept and process packets destined to MSADDR, 1897 while all other devices must not process packets destined to MSADDR. 1898 This model has well-established operational experience in Proxy 1899 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 1901 Appendix D. Change Log 1903 << RFC Editor - remove prior to publication >> 1905 Differences from draft-templin-6man-omni-interface-20 to draft- 1906 templin-6man-omni-interface-21: 1908 o Safety-Based Multilink (SBM) and Performance-Based Multilink 1909 (PBM). 1911 Differences from draft-templin-6man-omni-interface-18 to draft- 1912 templin-6man-omni-interface-19: 1914 o SEND/CGA. 1916 Differences from draft-templin-6man-omni-interface-17 to draft- 1917 templin-6man-omni-interface-18: 1919 o Teredo 1921 Differences from draft-templin-6man-omni-interface-14 to draft- 1922 templin-6man-omni-interface-15: 1924 o Prefix length discussions removed. 1926 Differences from draft-templin-6man-omni-interface-12 to draft- 1927 templin-6man-omni-interface-13: 1929 o Teredo 1931 Differences from draft-templin-6man-omni-interface-11 to draft- 1932 templin-6man-omni-interface-12: 1934 o Major simplifications and clarifications on MTU and fragmentation. 1936 o Document now updates RFC4443 and RFC8201. 1938 Differences from draft-templin-6man-omni-interface-10 to draft- 1939 templin-6man-omni-interface-11: 1941 o Removed /64 assumption, resulting in new OMNI address format. 1943 Differences from draft-templin-6man-omni-interface-07 to draft- 1944 templin-6man-omni-interface-08: 1946 o OMNI MNs in the open Internet 1948 Differences from draft-templin-6man-omni-interface-06 to draft- 1949 templin-6man-omni-interface-07: 1951 o Brought back L2 MSADDR mapping text for MN / AR isolation based on 1952 L2 addressing. 1954 o Expanded "Transition Considerations". 1956 Differences from draft-templin-6man-omni-interface-05 to draft- 1957 templin-6man-omni-interface-06: 1959 o Brought back OMNI option "R" flag, and discussed its use. 1961 Differences from draft-templin-6man-omni-interface-04 to draft- 1962 templin-6man-omni-interface-05: 1964 o Transition considerations, and overhaul of RS/RA addressing with 1965 the inclusion of MSE addresses within the OMNI option instead of 1966 as RS/RA addresses (developed under FAA SE2025 contract number 1967 DTFAWA-15-D-00030). 1969 Differences from draft-templin-6man-omni-interface-02 to draft- 1970 templin-6man-omni-interface-03: 1972 o Added "advisory PTB messages" under FAA SE2025 contract number 1973 DTFAWA-15-D-00030. 1975 Differences from draft-templin-6man-omni-interface-01 to draft- 1976 templin-6man-omni-interface-02: 1978 o Removed "Primary" flag and supporting text. 1980 o Clarified that "Router Lifetime" applies to each ANET interface 1981 independently, and that the union of all ANET interface Router 1982 Lifetimes determines MSE lifetime. 1984 Differences from draft-templin-6man-omni-interface-00 to draft- 1985 templin-6man-omni-interface-01: 1987 o "All-MSEs" OMNI LLA defined. Also reserved fe80::ff00:0000/104 1988 for future use (most likely as "pseudo-multicast"). 1990 o Non-normative discussion of alternate OMNI LLA construction form 1991 made possible if the 64-bit assumption were relaxed. 1993 Differences from draft-templin-atn-aero-interface-21 to draft- 1994 templin-6man-omni-interface-00: 1996 o Minor clarification on Type-2 ifIndex-tuple encoding. 1998 o Draft filename change (replaces draft-templin-atn-aero-interface). 2000 Differences from draft-templin-atn-aero-interface-20 to draft- 2001 templin-atn-aero-interface-21: 2003 o OMNI option format 2005 o MTU 2007 Differences from draft-templin-atn-aero-interface-19 to draft- 2008 templin-atn-aero-interface-20: 2010 o MTU 2012 Differences from draft-templin-atn-aero-interface-18 to draft- 2013 templin-atn-aero-interface-19: 2015 o MTU 2017 Differences from draft-templin-atn-aero-interface-17 to draft- 2018 templin-atn-aero-interface-18: 2020 o MTU and RA configuration information updated. 2022 Differences from draft-templin-atn-aero-interface-16 to draft- 2023 templin-atn-aero-interface-17: 2025 o New "Primary" flag in OMNI option. 2027 Differences from draft-templin-atn-aero-interface-15 to draft- 2028 templin-atn-aero-interface-16: 2030 o New note on MSE OMNI LLA uniqueness assurance. 2032 o General cleanup. 2034 Differences from draft-templin-atn-aero-interface-14 to draft- 2035 templin-atn-aero-interface-15: 2037 o General cleanup. 2039 Differences from draft-templin-atn-aero-interface-13 to draft- 2040 templin-atn-aero-interface-14: 2042 o General cleanup. 2044 Differences from draft-templin-atn-aero-interface-12 to draft- 2045 templin-atn-aero-interface-13: 2047 o Minor re-work on "Notify-MSE" (changed to Notification ID). 2049 Differences from draft-templin-atn-aero-interface-11 to draft- 2050 templin-atn-aero-interface-12: 2052 o Removed "Request/Response" OMNI option formats. Now, there is 2053 only one OMNI option format that applies to all ND messages. 2055 o Added new OMNI option field and supporting text for "Notify-MSE". 2057 Differences from draft-templin-atn-aero-interface-10 to draft- 2058 templin-atn-aero-interface-11: 2060 o Changed name from "aero" to "OMNI" 2062 o Resolved AD review comments from Eric Vyncke (posted to atn list) 2064 Differences from draft-templin-atn-aero-interface-09 to draft- 2065 templin-atn-aero-interface-10: 2067 o Renamed ARO option to AERO option 2069 o Re-worked Section 13 text to discuss proactive NUD. 2071 Differences from draft-templin-atn-aero-interface-08 to draft- 2072 templin-atn-aero-interface-09: 2074 o Version and reference update 2076 Differences from draft-templin-atn-aero-interface-07 to draft- 2077 templin-atn-aero-interface-08: 2079 o Removed "Classic" and "MS-enabled" link model discussion 2081 o Added new figure for MN/AR/MSE model. 2083 o New Section on "Detecting and responding to MSE failure". 2085 Differences from draft-templin-atn-aero-interface-06 to draft- 2086 templin-atn-aero-interface-07: 2088 o Removed "nonce" field from AR option format. Applications that 2089 require a nonce can include a standard nonce option if they want 2090 to. 2092 o Various editorial cleanups. 2094 Differences from draft-templin-atn-aero-interface-05 to draft- 2095 templin-atn-aero-interface-06: 2097 o New Appendix C on "VDL Mode 2 Considerations" 2099 o New Appendix D on "RS/RA Messaging as a Single Standard API" 2101 o Various significant updates in Section 5, 10 and 12. 2103 Differences from draft-templin-atn-aero-interface-04 to draft- 2104 templin-atn-aero-interface-05: 2106 o Introduced RFC6543 precedent for focusing IPv6 ND messaging to a 2107 reserved unicast link-layer address 2109 o Introduced new IPv6 ND option for Aero Registration 2111 o Specification of MN-to-MSE message exchanges via the ANET access 2112 router as a proxy 2114 o IANA Considerations updated to include registration requests and 2115 set interim RFC4727 option type value. 2117 Differences from draft-templin-atn-aero-interface-03 to draft- 2118 templin-atn-aero-interface-04: 2120 o Removed MNP from aero option format - we already have RIOs and 2121 PIOs, and so do not need another option type to include a Prefix. 2123 o Clarified that the RA message response must include an aero option 2124 to indicate to the MN that the ANET provides a MS. 2126 o MTU interactions with link adaptation clarified. 2128 Differences from draft-templin-atn-aero-interface-02 to draft- 2129 templin-atn-aero-interface-03: 2131 o Sections re-arranged to match RFC4861 structure. 2133 o Multiple aero interfaces 2135 o Conceptual sending algorithm 2136 Differences from draft-templin-atn-aero-interface-01 to draft- 2137 templin-atn-aero-interface-02: 2139 o Removed discussion of encapsulation (out of scope) 2141 o Simplified MTU section 2143 o Changed to use a new IPv6 ND option (the "aero option") instead of 2144 S/TLLAO 2146 o Explained the nature of the interaction between the mobility 2147 management service and the air interface 2149 Differences from draft-templin-atn-aero-interface-00 to draft- 2150 templin-atn-aero-interface-01: 2152 o Updates based on list review comments on IETF 'atn' list from 2153 4/29/2019 through 5/7/2019 (issue tracker established) 2155 o added list of opportunities afforded by the single virtual link 2156 model 2158 o added discussion of encapsulation considerations to Section 6 2160 o noted that DupAddrDetectTransmits is set to 0 2162 o removed discussion of IPv6 ND options for prefix assertions. The 2163 aero address already includes the MNP, and there are many good 2164 reasons for it to continue to do so. Therefore, also including 2165 the MNP in an IPv6 ND option would be redundant. 2167 o Significant re-work of "Router Discovery" section. 2169 o New Appendix B on Prefix Length considerations 2171 First draft version (draft-templin-atn-aero-interface-00): 2173 o Draft based on consensus decision of ICAO Working Group I Mobility 2174 Subgroup March 22, 2019. 2176 Authors' Addresses 2177 Fred L. Templin (editor) 2178 The Boeing Company 2179 P.O. Box 3707 2180 Seattle, WA 98124 2181 USA 2183 Email: fltemplin@acm.org 2185 Tony Whyman 2186 MWA Ltd c/o Inmarsat Global Ltd 2187 99 City Road 2188 London EC1Y 1AX 2189 England 2191 Email: tony.whyman@mccallumwhyman.com