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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: rfc1191, rfc4443, rfc8201 (if A. Whyman 5 approved) MWA Ltd c/o Inmarsat Global Ltd 6 Intended status: Standards Track February 2, 2021 7 Expires: August 6, 2021 9 Transmission of IP Packets over Overlay Multilink Network (OMNI) 10 Interfaces 11 draft-templin-6man-omni-interface-74 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 IP 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 August 6, 2021. 41 Copyright Notice 43 Copyright (c) 2021 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 . . . . . . . . . . . . . . . . . . . . . . . . . 5 60 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 9 61 4. Overlay Multilink Network (OMNI) Interface Model . . . . . . 9 62 5. The OMNI Adaptation Layer (OAL) . . . . . . . . . . . . . . . 14 63 5.1. Fragmentation Security Implications . . . . . . . . . . . 19 64 5.2. OAL "Super-Packet" Packing . . . . . . . . . . . . . . . 20 65 6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 22 66 7. Link-Local Addresses (LLAs) . . . . . . . . . . . . . . . . . 22 67 8. Unique-Local Addresses (ULAs) . . . . . . . . . . . . . . . . 24 68 9. Global Unicast Addresses (GUAs) . . . . . . . . . . . . . . . 25 69 10. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 26 70 10.1. Sub-Options . . . . . . . . . . . . . . . . . . . . . . 28 71 10.1.1. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . 29 72 10.1.2. PadN . . . . . . . . . . . . . . . . . . . . . . . . 29 73 10.1.3. Interface Attributes (Type 1) . . . . . . . . . . . 30 74 10.1.4. Interface Attributes (Type 2) . . . . . . . . . . . 31 75 10.1.5. Traffic Selector . . . . . . . . . . . . . . . . . . 35 76 10.1.6. Origin Indication . . . . . . . . . . . . . . . . . 36 77 10.1.7. MS-Register . . . . . . . . . . . . . . . . . . . . 37 78 10.1.8. MS-Release . . . . . . . . . . . . . . . . . . . . . 37 79 10.1.9. Geo Coordinates . . . . . . . . . . . . . . . . . . 38 80 10.1.10. Dynamic Host Configuration Protocol for IPv6 81 (DHCPv6) Message . . . . . . . . . . . . . . . . . . 38 82 10.1.11. Host Identity Protocol (HIP) Message . . . . . . . . 39 83 10.1.12. Node Identification . . . . . . . . . . . . . . . . 40 84 11. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 41 85 12. Multilink Conceptual Sending Algorithm . . . . . . . . . . . 41 86 12.1. Multiple OMNI Interfaces . . . . . . . . . . . . . . . . 42 87 12.2. MN<->AR Traffic Loop Prevention . . . . . . . . . . . . 42 88 13. Router Discovery and Prefix Registration . . . . . . . . . . 43 89 13.1. Router Discovery in IP Multihop and IPv4-Only Networks . 47 90 13.2. MS-Register and MS-Release List Processing . . . . . . . 48 91 13.3. DHCPv6-based Prefix Registration . . . . . . . . . . . . 50 92 14. Secure Redirection . . . . . . . . . . . . . . . . . . . . . 51 93 15. AR and MSE Resilience . . . . . . . . . . . . . . . . . . . . 51 94 16. Detecting and Responding to MSE Failures . . . . . . . . . . 52 95 17. Transition Considerations . . . . . . . . . . . . . . . . . . 52 96 18. OMNI Interfaces on the Open Internet . . . . . . . . . . . . 53 97 19. Time-Varying MNPs . . . . . . . . . . . . . . . . . . . . . . 54 98 20. Node Identification . . . . . . . . . . . . . . . . . . . . . 55 99 21. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 56 100 22. Security Considerations . . . . . . . . . . . . . . . . . . . 57 101 23. Implementation Status . . . . . . . . . . . . . . . . . . . . 58 102 24. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 58 103 25. References . . . . . . . . . . . . . . . . . . . . . . . . . 59 104 25.1. Normative References . . . . . . . . . . . . . . . . . . 59 105 25.2. Informative References . . . . . . . . . . . . . . . . . 61 106 Appendix A. Interface Attribute Preferences Bitmap Encoding . . 67 107 Appendix B. VDL Mode 2 Considerations . . . . . . . . . . . . . 69 108 Appendix C. MN / AR Isolation Through L2 Address Mapping . . . . 70 109 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 71 110 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 73 112 1. Introduction 114 Mobile Nodes (MNs) (e.g., aircraft of various configurations, 115 terrestrial vehicles, seagoing vessels, enterprise wireless devices, 116 pedestrians with cellphones, etc.) often have multiple interface 117 connections to wireless and/or wired-link data links used for 118 communicating with networked correspondents. These data links may 119 have diverse performance, cost and availability properties that can 120 change dynamically according to mobility patterns, flight phases, 121 proximity to infrastructure, etc. MNs coordinate their data links in 122 a discipline known as "multilink", in which a single virtual 123 interface is configured over the node's underlying interface 124 connections to the data links. 126 The MN configures a virtual interface (termed the "Overlay Multilink 127 Network (OMNI) interface") as a thin layer over the underlying 128 interfaces. The OMNI interface is therefore the only interface 129 abstraction exposed to the IP layer and behaves according to the Non- 130 Broadcast, Multiple Access (NBMA) interface principle, while 131 underlying interfaces appear as link layer communication channels in 132 the architecture. The OMNI interface connects to a virtual overlay 133 service known as the "OMNI link". The OMNI link spans one or more 134 Internetworks that may include private-use infrastructures and/or the 135 global public Internet itself. 137 Each MN receives a Mobile Network Prefix (MNP) for numbering 138 downstream-attached End User Networks (EUNs) independently of the 139 access network data links selected for data transport. The MN 140 performs router discovery over the OMNI interface (i.e., similar to 141 IPv6 customer edge routers [RFC7084]) and acts as a mobile router on 142 behalf of its EUNs. The router discovery process is iterated over 143 each of the OMNI interface's underlying interfaces in order to 144 register per-link parameters (see Section 13). 146 The OMNI interface provides a multilink nexus for exchanging inbound 147 and outbound traffic via the correct underlying interface(s). The IP 148 layer sees the OMNI interface as a point of connection to the OMNI 149 link. Each OMNI link has one or more associated Mobility Service 150 Prefixes (MSPs), which are typically IP Global Unicast Address (GUA) 151 prefixes from which OMNI link MNPs are derived. If there are 152 multiple OMNI links, the IPv6 layer will see multiple OMNI 153 interfaces. 155 MNs may connect to multiple distinct OMNI links by configuring 156 multiple OMNI interfaces, e.g., omni0, omni1, omni2, etc. Each OMNI 157 interface is configured over a set of underlying interfaces and 158 provides a nexus for Safety-Based Multilink (SBM) operation. Each 159 OMNI SBM topology configures a common ULA prefix [ULA]::/48, and each 160 OMNI link within the topology configures a unique 16-bit Subnet ID 161 '*' to construct the sub-prefix [ULA*]::/64 (see: Section 8). The IP 162 layer applies SBM routing to select an OMNI interface, which then 163 applies Performance-Based Multilink (PBM) to select the correct 164 underlying interface. Applications can apply Segment Routing 165 [RFC8402] to select independent SBM topologies for fault tolerance. 167 The OMNI interface interacts with a network-based Mobility Service 168 (MS) through IPv6 Neighbor Discovery (ND) control message exchanges 169 [RFC4861]. The MS provides Mobility Service Endpoints (MSEs) that 170 track MN movements and represent their MNPs in a global routing or 171 mapping system. 173 Many OMNI use cases are currently under active consideration. In 174 particular, the International Civil Aviation Organization (ICAO) 175 Working Group-I Mobility Subgroup is developing a future Aeronautical 176 Telecommunications Network with Internet Protocol Services (ATN/IPS) 177 and has issued a liaison statement requesting IETF adoption [ATN] in 178 support of ICAO Document 9896 [ATN-IPS]. The IETF IP Wireless Access 179 in Vehicular Environments (ipwave) working group has further included 180 problem statement and use case analysis for OMNI in a document now in 181 AD evaluation for RFC publication 182 [I-D.ietf-ipwave-vehicular-networking]. Still other communities of 183 interest include AEEC, RTCA Special Committee 228 (SC-228) and NASA 184 programs that examine commercial aviation, Urban Air Mobility (UAM) 185 and Unmanned Air Systems (UAS). Pedestrians with handheld devices 186 represent another large class of potential OMNI users. 188 This document specifies the transmission of IP packets and MN/MS 189 control messages over OMNI interfaces. The OMNI interface supports 190 either IP protocol version (i.e., IPv4 [RFC0791] or IPv6 [RFC8200]) 191 as the network layer in the data plane, while using IPv6 ND messaging 192 as the control plane independently of the data plane IP protocol(s). 193 The OMNI Adaptation Layer (OAL) which operates as a mid-layer between 194 L3 and L2 is based on IP-in-IPv6 encapsulation per [RFC2473] as 195 discussed in the following sections. OMNI interfaces enable 196 multilink, mobility, multihop and multicast services, with provisions 197 for both Vehicle-to-Infrastructure (V2I) communications and Vehicle- 198 to-Vehicle (V2V) communications outside the context of 199 infrastructure. 201 2. Terminology 203 The terminology in the normative references applies; especially, the 204 terms "link" and "interface" are the same as defined in the IPv6 205 [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications. 206 Additionally, this document assumes the following IPv6 ND message 207 types: Router Solicitation (RS), Router Advertisement (RA), Neighbor 208 Solicitation (NS), Neighbor Advertisement (NA) and Redirect. 210 The Protocol Constants defined in Section 10 of [RFC4861] are used in 211 their same format and meaning in this document. The terms "All- 212 Routers multicast", "All-Nodes multicast" and "Subnet-Router anycast" 213 are the same as defined in [RFC4291] (with Link-Local scope assumed). 215 The term "IP" is used to refer collectively to either Internet 216 Protocol version (i.e., IPv4 [RFC0791] or IPv6 [RFC8200]) when a 217 specification at the layer in question applies equally to either 218 version. 220 The following terms are defined within the scope of this document: 222 Mobile Node (MN) 223 an end system with a mobile router having multiple distinct 224 upstream data link connections that are grouped together in one or 225 more logical units. The MN's data link connection parameters can 226 change over time due to, e.g., node mobility, link quality, etc. 227 The MN further connects a downstream-attached End User Network 228 (EUN). The term MN used here is distinct from uses in other 229 documents, and does not imply a particular mobility protocol. 231 End User Network (EUN) 232 a simple or complex downstream-attached mobile network that 233 travels with the MN as a single logical unit. The IP addresses 234 assigned to EUN devices remain stable even if the MN's upstream 235 data link connections change. 237 Mobility Service (MS) 238 a mobile routing service that tracks MN movements and ensures that 239 MNs remain continuously reachable even across mobility events. 240 Specific MS details are out of scope for this document. 242 Mobility Service Endpoint (MSE) 243 an entity in the MS (either singular or aggregate) that 244 coordinates the mobility events of one or more MN. 246 Mobility Service Prefix (MSP) 247 an aggregated IP Global Unicast Address (GUA) prefix (e.g., 248 2001:db8::/32, 192.0.2.0/24, etc.) assigned to the OMNI link and 249 from which more-specific Mobile Network Prefixes (MNPs) are 250 delegated. OMNI link administrators typically obtain MSPs from an 251 Internet address registry, however private-use prefixes can 252 alternatively be used subject to certain limitations (see: 253 Section 9). OMNI links that connect to the global Internet 254 advertise their MSPs to their interdomain routing peers. 256 Mobile Network Prefix (MNP) 257 a longer IP prefix delegated from an MSP (e.g., 258 2001:db8:1000:2000::/56, 192.0.2.8/30, etc.) and assigned to a MN. 259 MNs sub-delegate the MNP to devices located in EUNs. 261 Access Network (ANET) 262 a data link service network (e.g., an aviation radio access 263 network, satellite service provider network, cellular operator 264 network, wifi network, etc.) that connects MNs. Physical and/or 265 data link level security is assumed, and sometimes referred to as 266 "protected spectrum". Private enterprise networks and ground 267 domain aviation service networks may provide multiple secured IP 268 hops between the MN's point of connection and the nearest Access 269 Router. 271 Access Router (AR) 272 a router in the ANET for connecting MNs to correspondents in 273 outside Internetworks. The AR may be located on the same physical 274 link as the MN, or may be located multiple IP hops away. In the 275 latter case, the MN uses encapsulation to communicate with the AR 276 as though it were on the same physical link. 278 ANET interface 279 a MN's attachment to a link in an ANET. 281 Internetwork (INET) 282 a connected network region with a coherent IP addressing plan that 283 provides transit forwarding services between ANETs and nodes that 284 connect directly to the open INET via unprotected media. No 285 physical and/or data link level security is assumed, therefore 286 security must be applied by upper layers. The global public 287 Internet itself is an example. 289 INET interface 290 a node's attachment to a link in an INET. 292 *NET 293 a "wildcard" term used when a given specification applies equally 294 to both ANET and INET cases. 296 OMNI link 297 a Non-Broadcast, Multiple Access (NBMA) virtual overlay configured 298 over one or more INETs and their connected ANETs. An OMNI link 299 can comprise multiple INET segments joined by bridges the same as 300 for any link; the addressing plans in each segment may be mutually 301 exclusive and managed by different administrative entities. 303 OMNI interface 304 a node's attachment to an OMNI link, and configured over one or 305 more underlying *NET interfaces. If there are multiple OMNI links 306 in an OMNI domain, a separate OMNI interface is configured for 307 each link. 309 OMNI Adaptation Layer (OAL) 310 an OMNI interface process whereby packets admitted into the 311 interface are wrapped in a mid-layer IPv6 header and fragmented/ 312 reassembled if necessary to support the OMNI link Maximum 313 Transmission Unit (MTU). The OAL is also responsible for 314 generating MTU-related control messages as necessary, and for 315 providing addressing context for spanning multiple segments of a 316 bridged OMNI link. 318 OMNI Option 319 an IPv6 Neighbor Discovery option providing multilink parameters 320 for the OMNI interface as specified in Section 10. 322 Mobile Network Prefix Link Local Address (MNP-LLA) 323 an IPv6 Link Local Address that embeds the most significant 64 324 bits of an MNP in the lower 64 bits of fe80::/64, as specified in 325 Section 7. 327 Mobile Network Prefix Unique Local Address (MNP-ULA) 328 an IPv6 Unique-Local Address derived from an MNP-LLA. 330 Administrative Link Local Address (ADM-LLA) 331 an IPv6 Link Local Address that embeds a 32-bit administratively- 332 assigned identification value in the lower 32 bits of fe80::/96, 333 as specified in Section 7. 335 Administrative Unique Local Address (ADM-ULA) 336 an IPv6 Unique-Local Address derived from an ADM-LLA. 338 Multilink 339 an OMNI interface's manner of managing diverse underlying 340 interface connections to data links as a single logical unit. The 341 OMNI interface provides a single unified interface to upper 342 layers, while underlying interface selections are performed on a 343 per-packet basis considering factors such as DSCP, flow label, 344 application policy, signal quality, cost, etc. Multilinking 345 decisions are coordinated in both the outbound (i.e. MN to 346 correspondent) and inbound (i.e., correspondent to MN) directions. 348 Multihop 349 an iterative relaying of IP packets between MNs over an OMNI 350 underlying interface technology (such as omnidirectional wireless) 351 without support of fixed infrastructure. Multihop services entail 352 node-to-node relaying within a Mobile Ad-hoc Network (MANET) for 353 MN-to-MN communications and/or for "range extension" where MNs 354 within range of communications infrastructure elements provide 355 forwarding services for other MNs. 357 L2 358 The second layer in the OSI network model. Also known as "layer- 359 2", "link-layer", "sub-IP layer", "data link layer", etc. 361 L3 362 The third layer in the OSI network model. Also known as "layer- 363 3", "network-layer", "IP layer", etc. 365 underlying interface 366 a *NET interface over which an OMNI interface is configured. The 367 OMNI interface is seen as a L3 interface by the IP layer, and each 368 underlying interface is seen as a L2 interface by the OMNI 369 interface. The underlying interface either connects directly to 370 the physical communications media or coordinates with another node 371 where the physical media is hosted. 373 Mobility Service Identification (MSID) 374 Each MSE and AR is assigned a unique 32-bit Identification (MSID) 375 (see: Section 7). IDs are assigned according to MS-specific 376 guidelines (e.g., see: [I-D.templin-intarea-6706bis]). 378 Safety-Based Multilink (SBM) 379 A means for ensuring fault tolerance through redundancy by 380 connecting multiple affiliated OMNI interfaces to independent 381 routing topologies (i.e., multiple independent OMNI links). 383 Performance Based Multilink (PBM) 384 A means for selecting underlying interface(s) for packet 385 transmission and reception within a single OMNI interface. 387 OMNI Domain 388 The set of all SBM/PBM OMNI links that collectively provides 389 services for a common set of MSPs. Each OMNI domain consists of a 390 set of affiliated OMNI links that all configure the same ::/48 ULA 391 prefix with a unique 16-bit Subnet ID as discussed in Section 8. 393 3. Requirements 395 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 396 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 397 "OPTIONAL" in this document are to be interpreted as described in BCP 398 14 [RFC2119][RFC8174] when, and only when, they appear in all 399 capitals, as shown here. 401 OMNI links maintain a constant value "MAX_MSID" selected to provide 402 MNs with an acceptable level of MSE redundancy while minimizing 403 control message amplification. It is RECOMMENDED that MAX_MSID be 404 set to the default value 5; if a different value is chosen, it should 405 be set uniformly by all nodes on the OMNI link. 407 An implementation is not required to internally use the architectural 408 constructs described here so long as its external behavior is 409 consistent with that described in this document. 411 4. Overlay Multilink Network (OMNI) Interface Model 413 An OMNI interface is a MN virtual interface configured over one or 414 more underlying interfaces, which may be physical (e.g., an 415 aeronautical radio link) or virtual (e.g., an Internet or higher- 416 layer "tunnel"). The MN receives a MNP from the MS, and coordinates 417 with the MS through IPv6 ND message exchanges. The MN uses the MNP 418 to construct a unique Link-Local Address (MNP-LLA) through the 419 algorithmic derivation specified in Section 7 and assigns the LLA to 420 the OMNI interface. 422 The OMNI interface architectural layering model is the same as in 423 [RFC5558][RFC7847], and augmented as shown in Figure 1. The IP layer 424 therefore sees the OMNI interface as a single L3 interface with 425 multiple underlying interfaces that appear as L2 communication 426 channels in the architecture. 428 +----------------------------+ 429 | Upper Layer Protocol | 430 Session-to-IP +---->| | 431 Address Binding | +----------------------------+ 432 +---->| IP (L3) | 433 IP Address +---->| | 434 Binding | +----------------------------+ 435 +---->| OMNI Interface | 436 Logical-to- +---->| (LLA) | 437 Physical | +----------------------------+ 438 Interface +---->| L2 | L2 | | L2 | 439 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 440 +------+------+ +------+ 441 | L1 | L1 | | L1 | 442 | | | | | 443 +------+------+ +------+ 445 Figure 1: OMNI Interface Architectural Layering Model 447 Each underlying interface provides an L2/L1 abstraction according to 448 one of the following models: 450 o INET interfaces connect to an INET either natively or through one 451 or several IPv4 Network Address Translators (NATs). Native INET 452 interfaces have global IP addresses that are reachable from any 453 INET correspondent. NATed INET interfaces typically have private 454 IP addresses and connect to a private network behind one or more 455 NATs that provide INET access. 457 o ANET interfaces connect to a protected ANET that is separated from 458 the open INET by an AR acting as a proxy. The ANET interface may 459 be either on the same L2 link segment as the AR, or separated from 460 the AR by multiple IP hops. 462 o VPNed interfaces use security encapsulation over a *NET to a 463 Virtual Private Network (VPN) gateway. Other than the link-layer 464 encapsulation format, VPNed interfaces behave the same as for 465 Direct interfaces. 467 o Direct (aka "point-to-point") interfaces connect directly to a 468 peer without crossing any *NET paths. An example is a line-of- 469 sight link between a remote pilot and an unmanned aircraft. 471 The OMNI virtual interface model gives rise to a number of 472 opportunities: 474 o since MNP-LLAs are uniquely derived from an MNP, no Duplicate 475 Address Detection (DAD) or Multicast Listener Discovery (MLD) 476 messaging is necessary. 478 o since Temporary LLAs are statistically unique, they can be used 479 without DAD for short-term purposes, e.g. until an MNP-LLA is 480 obtained. 482 o *NET interfaces on the same L2 link segment as an AR do not 483 require any L3 addresses (i.e., not even link-local) in 484 environments where communications are coordinated entirely over 485 the OMNI interface. (An alternative would be to also assign the 486 same LLA to all *NET interfaces.) 488 o as underlying interface properties change (e.g., link quality, 489 cost, availability, etc.), any active interface can be used to 490 update the profiles of multiple additional interfaces in a single 491 message. This allows for timely adaptation and service continuity 492 under dynamically changing conditions. 494 o coordinating underlying interfaces in this way allows them to be 495 represented in a unified MS profile with provisions for mobility 496 and multilink operations. 498 o exposing a single virtual interface abstraction to the IPv6 layer 499 allows for multilink operation (including QoS based link 500 selection, packet replication, load balancing, etc.) at L2 while 501 still permitting L3 traffic shaping based on, e.g., DSCP, flow 502 label, etc. 504 o the OMNI interface allows inter-INET traversal when nodes located 505 in different INETs need to communicate with one another. This 506 mode of operation would not be possible via direct communications 507 over the underlying interfaces themselves. 509 o the OMNI Adaptation Layer (OAL) within the OMNI interface supports 510 lossless and adaptive path MTU mitigations not available for 511 communications directly over the underlying interfaces themselves. 512 The OAL supports "packing" of multiple IP payload packets within a 513 single OAL packet. 515 o L3 sees the OMNI interface as a point of connection to the OMNI 516 link; if there are multiple OMNI links (i.e., multiple MS's), L3 517 will see multiple OMNI interfaces. 519 o Multiple independent OMNI interfaces can be used for increased 520 fault tolerance through Safety-Based Multilink (SBM), with 521 Performance-Based Multilink (PBM) applied within each interface. 523 Other opportunities are discussed in [RFC7847]. Note that even when 524 the OMNI virtual interface is present, applications can still access 525 underlying interfaces either through the network protocol stack using 526 an Internet socket or directly using a raw socket. This allows for 527 intra-network (or point-to-point) communications without invoking the 528 OMNI interface and/or OAL. For example, when an IPv6 OMNI interface 529 is configured over an underlying IPv4 interface, applications can 530 still invoke IPv4 intra-network communications as long as the 531 communicating endpoints are not subject to mobility dynamics. 532 However, the opportunities discussed above are not available when the 533 architectural layering is bypassed in this way. 535 Figure 2 depicts the architectural model for a MN with an attached 536 EUN connecting to the MS via multiple independent *NETs. When an 537 underlying interface becomes active, the MN's OMNI interface sends 538 IPv6 ND messages without encapsulation if the first-hop Access Router 539 (AR) is on the same underlying link; otherwise, the interface uses 540 IP-in-IP encapsulation. The IPv6 ND messages traverse the ground 541 domain *NETs until they reach an AR (AR#1, AR#2, ..., AR#n), which 542 then coordinates with an INET Mobility Service Endpoint (MSE#1, 543 MSE#2, ..., MSE#m) and returns an IPv6 ND message response to the MN. 544 The Hop Limit in IPv6 ND messages is not decremented due to 545 encapsulation; hence, the OMNI interface appears to be attached to an 546 ordinary link. 548 +--------------+ (:::)-. 549 | MN |<-->.-(::EUN:::) 550 +--------------+ `-(::::)-' 551 |OMNI interface| 552 +----+----+----+ 553 +--------|IF#1|IF#2|IF#n|------ + 554 / +----+----+----+ \ 555 / | \ 556 / | \ 557 v v v 558 (:::)-. (:::)-. (:::)-. 559 .-(::*NET:::) .-(::*NET:::) .-(::*NET:::) 560 `-(::::)-' `-(::::)-' `-(::::)-' 561 +----+ +----+ +----+ 562 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 563 . +-|--+ +-|--+ +-|--+ . 564 . | | | 565 . v v v . 566 . <----- INET Encapsulation -----> . 567 . . 568 . +-----+ (:::)-. . 569 . |MSE#2| .-(::::::::) +-----+ . 570 . +-----+ .-(::: INET :::)-. |MSE#m| . 571 . (::::: Routing ::::) +-----+ . 572 . `-(::: System :::)-' . 573 . +-----+ `-(:::::::-' . 574 . |MSE#1| +-----+ +-----+ . 575 . +-----+ |MSE#3| |MSE#4| . 576 . +-----+ +-----+ . 577 . . 578 . . 579 . <----- Worldwide Connected Internetwork ----> . 580 ........................................................... 582 Figure 2: MN/MS Coordination via Multiple *NETs 584 After the initial IPv6 ND message exchange, the MN (and/or any nodes 585 on its attached EUNs) can send and receive IP data packets over the 586 OMNI interface. OMNI interface multilink services will forward the 587 packets via ARs in the correct underlying *NETs. The AR encapsulates 588 the packets according to the capabilities provided by the MS and 589 forwards them to the next hop within the worldwide connected 590 Internetwork via optimal routes. 592 OMNI links span one or more underlying Internetwork via the OMNI 593 Adaptation Layer (OAL) which is based on a mid-layer overlay 594 encapsulation using [RFC2473]. Each OMNI link corresponds to a 595 different overlay (differentiated by an address codepoint) which may 596 be carried over a completely separate underlying topology. Each MN 597 can facilitate SBM by connecting to multiple OMNI links using a 598 distinct OMNI interface for each link. 600 Note: OMNI interface underlying interfaces often connect directly to 601 physical media on the local platform (e.g., a laptop computer with 602 WiFi, etc.), but in some configurations the physical media may be 603 hosted on a separate Local Area Network (LAN) node. In that case, 604 the OMNI interface can establish a Layer-2 VLAN or a point-to-point 605 tunnel (at a layer below the underlying interface) to the node 606 hosting the physical media. The OMNI interface may also apply 607 encapsulation at a layer above the underlying interface such that 608 packets would appear "double-encapsulated" on the LAN; the node 609 hosting the physical media in turn removes the LAN encapsulation 610 prior to transmission or inserts it following reception. Finally, 611 the underlying interface must monitor the node hosting the physical 612 media (e.g., through periodic keepalives) so that it can convey 613 up/down/status information to the OMNI interface. 615 5. The OMNI Adaptation Layer (OAL) 617 The OMNI interface observes the link nature of tunnels, including the 618 Maximum Transmission Unit (MTU), Maximum Reassembly Unit (MRU) and 619 the role of fragmentation and reassembly [I-D.ietf-intarea-tunnels]. 620 The OMNI interface is configured over one or more underlying 621 interfaces that may have diverse MTUs. OMNI interfaces accommodate 622 MTU diversity through the use of the OMNI Adaptation Layer (OAL) as 623 discussed in this section. 625 IPv6 underlying interfaces are REQUIRED to configure a minimum MTU of 626 1280 bytes and a minimum MRU of 1500 bytes [RFC8200]. Therefore, the 627 minimum IPv6 path MTU is 1280 bytes since routers on the path are not 628 permitted to perform network fragmentation even though the 629 destination is required to reassemble more. The network therefore 630 MUST forward packets of at least 1280 bytes without generating an 631 IPv6 Path MTU Discovery (PMTUD) Packet Too Big (PTB) message 632 [RFC8201]. (Note: the source can apply "source fragmentation" for 633 locally-generated IPv6 packets up to 1500 bytes and larger still if 634 it if has a way to determine that the destination configures a larger 635 MRU, but this does not affect the minimum IPv6 path MTU.) 637 IPv4 underlying interfaces are REQUIRED to configure a minimum MTU of 638 68 bytes [RFC0791] and a minimum MRU of 576 bytes [RFC0791][RFC1122]. 639 Therefore, when the Don't Fragment (DF) bit in the IPv4 header is set 640 to 0 the minimum IPv4 path MTU is 576 bytes since routers on the path 641 support network fragmentation and the destination is required to 642 reassemble at least that much. The "Don't Fragment" (DF) bit in the 643 IPv4 encapsulation headers of packets sent over IPv4 underlying 644 interfaces therefore MUST be set to 0. (Note: even if the 645 encapsulation source has a way to determine that the encapsulation 646 destination configures an MRU larger than 576 bytes, it should not 647 assume a larger minimum IPv4 path MTU without careful consideration 648 of the issues discussed in Section 5.1.) 650 In network paths where IPv6/IPv4 protocol translation or IPv6-in-IPv4 651 encapsulation may be prevalent, it may be prudent for the OAL to 652 always assume the IPv4 minimum path MTU (i.e., 576 bytes) regardless 653 of the underlying interface IP protocol version. By always assuming 654 the IPv4 minimum path MTU even for IPv6 underlying interfaces, the 655 OAL may produce smaller fragments and additional header overhead but 656 will always interoperate and never run the risk of presenting a 657 destination interface with a packet that exceeds its MRU. 659 The OMNI interface configures both an MTU and MRU of 9180 bytes 660 [RFC2492]; the size is therefore not a reflection of the underlying 661 interface MTUs, but rather determines the largest packet the OMNI 662 interface can forward or reassemble. The OMNI interface uses the 663 OMNI Adaptation Layer (OAL) to admit packets from the network layer 664 that are no larger than the OMNI interface MTU while generating 665 ICMPv4 Fragmentation Needed [RFC1191] or ICMPv6 Path MTU Discovery 666 (PMTUD) Packet Too Big (PTB) [RFC8201] messages as necessary. This 667 document refers to both of these ICMPv4/ICMPv6 message types simply 668 as "PTBs", and introduces a distinction between PTB "hard" and "soft" 669 errors as discussed below. 671 For IPv4 packets with DF=0, the network layer performs IPv4 672 fragmentation if necessary then admits the packets/fragments into the 673 OMNI interface; these fragments will be reassembled by the final 674 destination. For IPv4 packets with DF=1 and IPv6 packets, the 675 network layer admits the packet if it is no larger than the OMNI 676 interface MTU; otherwise, it drops the packet and returns a PTB hard 677 error message to the source. 679 For each admitted IP packet/fragment, the OMNI interface internally 680 employs the OAL when necessary by encapsulating the inner IP packet/ 681 fragment in a mid-layer IPv6 header per [RFC2473] before adding any 682 outer IP encapsulations. (The OAL does not decrement the inner IP 683 Hop Limit/TTL during encapsulation since the insertion occurs at a 684 layer below IP forwarding.) If the OAL packet will itself require 685 fragmentation, the OMNI interface then calculates the 32-bit CRC over 686 the entire mid-layer packet and writes the value in a trailing field 687 at the end of the packet. Next, the OAL fragments this mid-layer 688 IPv6 packet, forwards the fragments (using *NET encapsulation if 689 necessary), and returns an internally-generated PTB soft error 690 message (subject to rate limiting) if it deems the packet too large 691 according to factors such as link performance characteristics, 692 reassembly congestion, etc. This ensures that the path MTU is 693 adaptive and reflects the current path used for a given data flow. 695 The OAL operates with respect to both the minimum IPv6 and IPv4 path 696 MTUs as follows: 698 o When an OMNI interface sends a packet toward a final destination 699 via an ANET peer, it sends without OAL encapsulation if the packet 700 (including any outer-layer ANET encapsulations) is no larger than 701 the underlying interface MTU for on-link ANET peers or the minimum 702 ANET path MTU for peers separated by multiple IP hops. Otherwise, 703 the OAL inserts an IPv6 header per [RFC2473] with source address 704 set to the node's own Unique-Local Address (ULA) (see: Section 8) 705 and destination set to either the Administrative ULA (ADM-ULA) of 706 the ANET peer or the Mobile Network Prefix ULA (MNP-ULA) 707 corresponding to the final destination (see below). The OAL then 708 calculates and appends the trailing 32-bit CRC, then uses IPv6 709 fragmentation to break the packet into a minimum number of non- 710 overlapping fragments where the size of each non-final fragment 711 (including both the OMNI and any outer-layer ANET encapsulations) 712 is determined by the underlying interface MTU for on-link ANET 713 peers or the minimum ANET path MTU for peers separated by multiple 714 IP hops. The OAL then encapsulates the fragments in any ANET 715 headers and sends them to the ANET peer, which either reassembles 716 before forwarding if the OAL destination is its own ADM-ULA or 717 forwards the fragments toward the final destination without first 718 reassembling otherwise. 720 o When an OMNI interface sends a packet toward a final destination 721 via an INET interface, it sends packets (including any outer-layer 722 INET encapsulations) no larger than the minimum INET path MTU 723 without OAL encapsulation if the destination is reached via an 724 INET address within the same OMNI link segment. Otherwise, the 725 OAL inserts an IPv6 header per [RFC2473] with source address set 726 to the node's ULA, destination set to the ULA of the next hop OMNI 727 node toward the final destination and (if necessary) with an OMNI 728 Routing Header (ORH) (see: [I-D.templin-intarea-6706bis]) with 729 final segment addressing information. The OAL next calculates and 730 appends the trailing 32-bit CRC, then uses IPv6 fragmentation to 731 break the packet into a minimum number of non-overlapping 732 fragments where the size of each non-final fragment (including 733 both the OMNI and outer-layer INET encapsulations) is determined 734 by the minimum INET path MTU. The OAL then encapsulates the 735 fragments in any INET headers and sends them to the OMNI link 736 neighbor, which reassembles before forwarding toward the final 737 destination. 739 In light of the above considerations, the OAL should assume a minimum 740 path MTU of 576 bytes for the purpose of generating OAL fragments. 741 Each OAL fragment will undergo *NET encapsulation including either a 742 20 byte IPv4 or 40 byte IPv6 header (plus an 8 byte UDP header for 743 INETs), leaving a minimum of 528 bytes for each fragment. Each OAL 744 fragment must accommodate 40 bytes for the OAL IPv6 header plus 8 745 bytes for the fragment header (while reserving 40 additional bytes in 746 case a maximum-length ORH is inserted during re-encapsulation), 747 leaving 440 bytes to accommodate the actual inner IP packet fragment. 748 OAL fragmentation algorithms therefore MUST produce non-final 749 fragments with the OAL IPv6 header Payload Length set to no less than 750 448 bytes (8 bytes for the fragment header plus 440 bytes for the 751 inner packet fragment), while the Payload Length of the final 752 fragment may be smaller. OAL reassembly algorithms MUST drop any 753 non-final fragments with Payload Length less than 448 bytes. 755 Note that OAL fragmentation algorithms MAY produce larger non-final 756 OAL fragments if better path MTU information is available. For 757 example, for ANETs in which no UDP encapsulation header is needed the 758 algorithm can increase the minimum non-final fragment length by 8 759 bytes. In a second example, for ANETs in which no IPv6 hops will be 760 traversed over the path the algorithm can increase the minimum length 761 by 20 bytes. In a third example, if there is assurance that no ORH 762 will be inserted in the path the algorithm can increase the minimum 763 length by 40 bytes. In a final example, when two ANET peers share a 764 common physical or virtual link with a larger MTU (e.g., 1280 bytes 765 or larger), the OAL can base the minimum non-final fragment length on 766 this larger MTU size as long as the receiving ANET peer reassembles 767 (and possibly also refragments) before forwarding. (Other examples 768 are possible, and dependent on actual ANET/INET deployment 769 scenarios.) 771 In all of the above examples, optimizing the minimum OAL fragment 772 size may be important for accommodating links where performance is 773 dependent on maximum use of the available link MTU, e.g. for wireless 774 aviation data links. Additionally, in order to set the correct 775 context for reassembly, the OMNI interface that inserts the OAL 776 header MUST also be the one that inserts the IPv6 fragment header 777 Identification value. While not strictly required, sending all 778 fragments of the same fragmented OAL packet consecutively over the 779 same underlying interface with minimal inter-fragment delay may 780 increase the likelihood of successful reassembly. 782 Ordinary PTB messages with ICMPv4 header "unused" field or ICMPv6 783 header Code field value 0 are hard errors that always indicate that a 784 packet has been dropped due to a real MTU restriction. However, the 785 OAL can also forward large packets via encapsulation and 786 fragmentation while at the same time returning PTB soft error 787 messages (subject to rate limiting) indicating that a forwarded 788 packet was uncomfortably large. The OMNI interface can therefore 789 continuously forward large packets without loss while returning PTB 790 soft error messages recommending a smaller size. Original sources 791 that receive the soft errors in turn reduce the size of the packets 792 they send, i.e., the same as for hard errors. 794 The OAL sets the ICMPv4 header "unused" field or ICMPv6 header Code 795 field to the value 1 in PTB soft error messages. The OAL sets the 796 PTB destination address to the source address of the original packet, 797 and sets the source address to the MNP Subnet Router Anycast address 798 of the MN. The OAL then sets the MTU field to a value no smaller 799 than 576 for ICMPv4 or 1280 for ICMPv6, and returns the PTB soft 800 error to the original source. 802 When the original source receives the PTB, it reduces its path MTU 803 estimate the same as for hard errors but does not regard the message 804 as a loss indication. (If the original source does not recognize the 805 soft error code, it regards the PTB the same as a hard error but 806 should heed the retransmission advice given in [RFC8201] suggesting 807 retransmission based on normal packetization layer retransmission 808 timers.) This document therefore updates [RFC1191][RFC4443] and 809 [RFC8201]. Furthermore, implementations of [RFC4821] must be aware 810 that PTB hard or soft errors may arrive at any time even if after a 811 successful MTU probe (this is the same consideration as for an 812 ordinary path fluctuation following a successful probe). 814 In summary, the OAL supports continuous transmission and reception of 815 packets of various sizes in the face of dynamically changing network 816 conditions. Moreover, since PTB soft errors do not indicate loss, 817 original sources that receive soft errors can quickly scan for path 818 MTU increases without waiting for the minimum 10 minutes specified 819 for loss-oriented PTB hard errors [RFC1191][RFC8201]. The OAL 820 therefore provides a lossless and adaptive service that accommodates 821 MTU diversity especially well-suited for dynamic multilink 822 environments. 824 Note: An OMNI interface that reassembles OAL fragments may experience 825 congestion-oriented loss in its reassembly cache and can optionally 826 send PTB soft errors to the original source and/or ICMP "Time 827 Exceeded" messages to the source of the OAL fragments. In 828 environments where the messages may contribute to unacceptable 829 additional congestion, however, the OMNI interface can refrain from 830 sending PTB soft errors and simply regard the loss as an ordinary 831 unreported congestion event for which the original source will 832 eventually compensate. 834 Note: When the network layer forwards an IPv4 packet/fragment with 835 DF=0 into the OMNI interface, the interface can optionally perform 836 (further) IPv4 fragmentation before invoking the OAL so that the 837 fragments will be reassembled by the final destination. When the 838 network layer performs IPv6 fragmentation for locally-generated IPv6 839 packets, the OMNI interface typically invokes the OAL without first 840 applying (further) IPv6 fragmentation; the network layer should 841 therefore fragment to the minimum IPv6 path MTU (or smaller still) to 842 push the reassembly burden to the final destination and avoid 843 receiving PTB soft errors from the OMNI interface. Aside from these 844 non-normative guidelines, the manner in which any IP fragmentation is 845 invoked prior to OAL encapsulation/fragmentation is an implementation 846 matter. 848 Note: The source OAL includes a trailing 32-bit CRC only for OAL 849 packets that require fragmentation, and the destination OAL discards 850 any OAL packets with incorrect CRC values following reassembly. (The 851 source OAL calculates the CRC over the entire packet, then appends 852 the CRC to the end of the packet and adds the CRC length to the OAL 853 Payload Length prior to fragmentation. The destination OAL subtracts 854 the CRC length from the OAL Payload Length and verifies the CRC 855 following reassembly.) A 32-bit CRC is sufficient for detecting 856 reassembly misassociations for packet sizes no larger than the OMNI 857 interface MTU but may not be sufficient to detect errors for larger 858 sizes [CRC]. 860 Note: Some underlying interface types (e.g., VPNs) may already 861 provide their own robust fragmentation and reassembly services even 862 without OAL encapsulation. In those cases, the OAL can invoke the 863 inherent underlying interface schemes instead while employing PTB 864 soft errors in the same fashion as described above. Other underlying 865 interface facilities such as header/message compression can also be 866 harnessed in a similar fashion. 868 Note: Applications can dynamically tune the size of the packets they 869 to send to produce the best possible throughput and latency, with the 870 understanding that these parameters may change over time due to 871 factors such as congestion, mobility, network path changes, etc. The 872 receipt or absence of soft errors should be seen as hints of when 873 increasing or decreasing packet sizes may be beneficial. 875 5.1. Fragmentation Security Implications 877 As discussed in Section 3.7 of [RFC8900], there are four basic 878 threats concerning IPv6 fragmentation; each of which is addressed by 879 effective mitigations as follows: 881 1. Overlapping fragment attacks - reassembly of overlapping 882 fragments is forbidden by [RFC8200]; therefore, this threat does 883 not apply to the OAL. 885 2. Resource exhaustion attacks - this threat is mitigated by 886 providing a sufficiently large OAL reassembly cache and 887 instituting "fast discard" of incomplete reassemblies that may be 888 part of a buffer exhaustion attack. The reassembly cache should 889 be sufficiently large so that a sustained attack does not cause 890 excessive loss of good reassemblies but not so large that (timer- 891 based) data structure management becomes computationally 892 expensive. The cache should also be indexed based on the arrival 893 underlying interface such that congestion experienced over a 894 first underlying interface does not cause discard of incomplete 895 reassemblies for uncongested underlying interfaces. 897 3. Attacks based on predictable fragment identification values - 898 this threat is mitigated by selecting a suitably random ID value 899 per [RFC7739]. 901 4. Evasion of Network Intrusion Detection Systems (NIDS) - this 902 threat is mitigated by disallowing "tiny fragments" per the OAL 903 fragmentation procedures specified above. 905 Additionally, IPv4 fragmentation includes a 16-bit Identification (IP 906 ID) field with only 65535 unique values such that at high data rates 907 the field could wrap and apply to new packets while the fragments of 908 old packets using the same ID are still alive in the network 909 [RFC4963]. However, since the largest OAL fragment that will be sent 910 via an IPv4 *NET path is 576 bytes any IPv4 fragmentation would occur 911 only on links with an IPv4 MTU smaller than this size, and [RFC3819] 912 recommendations suggest that such links will have low data rates. 913 Since IPv6 provides a 32-bit Identification value, IP ID wraparound 914 at high data rates is not a concern for IPv6 fragmentation. 916 Finally, [RFC6980] documents fragmentation security concerns for 917 large IPv6 ND messages. These concerns are addressed when the OMNI 918 interface employs the OAL instead of directly fragmenting the IPv6 ND 919 message itself. For this reason, OMNI interfaces MUST NOT admit IPv6 920 ND messages larger than the OMNI interface MTU, and MUST employ the 921 OAL for IPv6 ND messages admitted into the OMNI interface the same as 922 discussed above. 924 5.2. OAL "Super-Packet" Packing 926 By default, the source OAL includes a 40-byte IPv6 encapsulation 927 header for each inner IP payload packet during OAL encapsulation. 928 When fragmentation is needed, the source OAL also calculates and 929 includes a 32-bit trailing CRC for the entire packet then performs 930 fragmentation such that a copy of the 40-byte IPv6 header plus an 931 8-byte IPv6 Fragment Header is included in each fragment. However, 932 these encapsulations may represent excessive overhead in some 933 environments. A technique known as "packing" discussed in 934 [I-D.ietf-intarea-tunnels] is therefore supported so that multiple 935 inner IP payload packets can be included within a single OAL packet 936 known as a "super-packet". 938 When the source OAL has multiple inner IP payload packets with total 939 length no larger than the OMNI interface MTU to send to the same 940 destination, it can optionally concatenate them into a super-packet 941 encapsulated in a single OAL header. Within the super-packet, the IP 942 header of the first inner packet (iHa) followed by its data (iDa) is 943 concatenated immediately following the OAL header, then the inner IP 944 header of the next packet (iHb) followed by its data (iDb) is 945 concatenated immediately following the first packet, etc. The super- 946 packet format is transposed from [I-D.ietf-intarea-tunnels] and shown 947 in Figure 3: 949 <-- Multiple inner IP payload packets to be "packed" --> 950 +-----+-----+ 951 | iHa | iDa | 952 +-----+-----+ 953 | 954 | +-----+-----+ 955 | | iHb | iDb | 956 | +-----+-----+ 957 | | 958 | | +-----+-----+ 959 | | | iHc | iDc | 960 | | +-----+-----+ 961 | | | 962 v v v 963 +----------+-----+-----+-----+-----+-----+-----+ 964 | OAL Hdr | iHa | iDa | iHb | iDb | iHc | iDc | 965 +----------+-----+-----+-----+-----+-----+-----+ 966 <-- OMNI "Super-Packet" with single OAL hdr --> 968 Figure 3: OAL Super-Packet Format 970 When the source OAL sends a super-packet, it calculates a CRC and 971 applies OAL fragmentation if necessary then sends the packet or 972 fragments to the destination OAL. When the destination OAL receives 973 the super-packet as a whole packet or as fragments, it reassembles 974 and verifies the CRC if necessary then regards the OAL header Payload 975 Length (after subtracting the CRC length) as the sum of the lengths 976 of all payload packets. The destination OAL then selectively 977 extracts each individual payload packet (e.g., by setting pointers 978 into the buffer containing the super-packet and maintaining a 979 reference count, by copying each payload packet into its own buffer, 980 etc.) and forwards each payload packet or processes it locally as 981 appropriate. During extraction, the OAL determines the IP protocol 982 version of each successive inner payload packet 'j' by examining the 983 first four bits of iH(j), and determines the length of the inner 984 packet by examining the rest of iH(j) according to the IP protocol 985 version. 987 Note: OMNI interfaces must take care to avoid processing super-packet 988 payload elements that would subvert security. Specifically, if a 989 super-packet contains a mix of data and control payload packets 990 (which could include critical security codes), the node MUST NOT 991 process the data packets before processing the control packets. 993 6. Frame Format 995 The OMNI interface transmits IP packets according to the native frame 996 format of each underlying interface. For example, for Ethernet- 997 compatible interfaces the frame format is specified in [RFC2464], for 998 aeronautical radio interfaces the frame format is specified in 999 standards such as ICAO Doc 9776 (VDL Mode 2 Technical Manual), for 1000 tunnels over IPv6 the frame format is specified in [RFC2473], etc. 1002 7. Link-Local Addresses (LLAs) 1004 OMNI nodes are assigned OMNI interface IPv6 Link-Local Addresses 1005 (LLAs) through pre-service administrative actions. "MNP-LLAs" embed 1006 the MNP assigned to the mobile node, while "ADM-LLAs" include an 1007 administratively-unique ID that is guaranteed to be unique on the 1008 link. LLAs are configured as follows: 1010 o IPv6 MNP-LLAs encode the most-significant 64 bits of a MNP within 1011 the least-significant 64 bits of the IPv6 link-local prefix 1012 fe80::/64, i.e., in the LLA "interface identifier" portion. The 1013 prefix length for the LLA is determined by adding 64 to the MNP 1014 prefix length. For example, for the MNP 2001:db8:1000:2000::/56 1015 the corresponding MNP-LLA is fe80::2001:db8:1000:2000/120. 1017 o IPv4-compatible MNP-LLAs are constructed as fe80::ffff:[IPv4], 1018 i.e., the interface identifier consists of 16 '0' bits, followed 1019 by 16 '1' bits, followed by a 32bit IPv4 address/prefix. The 1020 prefix length for the LLA is determined by adding 96 to the MNP 1021 prefix length. For example, the IPv4-Compatible MN OMNI LLA for 1022 192.0.2.0/24 is fe80::ffff:192.0.2.0/120 (also written as 1023 fe80::ffff:c000:0200/120). 1025 o ADM-LLAs are assigned to ARs and MSEs and MUST be managed for 1026 uniqueness. The lower 32 bits of the LLA includes a unique 1027 integer "MSID" value between 0x00000001 and 0xfeffffff, e.g., as 1028 in fe80::1, fe80::2, fe80::3, etc., fe80::feffffff. The ADM-LLA 1029 prefix length is determined by adding 96 to the MSID prefix 1030 length. For example, if the prefix length for MSID 0x10012001 is 1031 16 then the ADM-LLA prefix length is set to 112 and the LLA is 1032 written as fe80::1001:2001/112. The "zero" address for each ADM- 1033 LLA prefix is the Subnet-Router anycast address for that prefix 1034 [RFC4291]; for example, the Subnet-Router anycast address for 1035 fe80::1001:2001/112 is simply fe80::1001:2000. The MSID range 1036 0xff000000 through 0xffffffff is reserved for future use. 1038 o Temporary LLAs are constructed per [I-D.ietf-6man-rfc4941bis] and 1039 used by MNs for the short-term purpose of procuring an actual MNP- 1040 LLA upon startup or (re)connecting to the network. MNs may use 1041 Temporary LLAs as the IPv6 source address of an RS message in 1042 order to request a MNP-LLA from the MS. 1044 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 1045 MNPs can be allocated from that block ensuring that there is no 1046 possibility for overlap between the MNP- and ADM-LLA constructs 1047 discussed above. 1049 Since MNP-LLAs are based on the distribution of administratively 1050 assured unique MNPs, and since ADM-LLAs are guaranteed unique through 1051 administrative assignment, OMNI interfaces set the autoconfiguration 1052 variable DupAddrDetectTransmits to 0 [RFC4862]. 1054 Temporary LLAs are distinguished from MNP- and ADM-LLAs by examining 1055 the OMNI option 'T' bit (see: Section 10), and employ optimistic DAD 1056 principles [RFC4429] since they are probabilistically unique and 1057 their use is short-duration in nature. 1059 Note: If future protocol extensions relax the 64-bit boundary in IPv6 1060 addressing, the additional prefix bits of an MNP could be encoded in 1061 bits 16 through 63 of the MNP-LLA. (The most-significant 64 bits 1062 would therefore still be in bits 64-127, and the remaining bits would 1063 appear in bits 16 through 48.) However, the analysis provided in 1064 [RFC7421] suggests that the 64-bit boundary will remain in the IPv6 1065 architecture for the foreseeable future. 1067 Note: Even though this document honors the 64-bit boundary in IPv6 1068 addressing per [RFC7421], it suggests prefix lengths longer than /64 1069 for routing purposes. This effectively extends IPv6 routing 1070 determination into the interface identifier portion of the IPv6 1071 address, but it does not redefine the 64-bit boundary. 1073 8. Unique-Local Addresses (ULAs) 1075 OMNI domains use IPv6 Unique-Local Addresses (ULAs) as the source and 1076 destination addresses in OAL IPv6 encapsulation headers. ULAs are 1077 only routable within the scope of a an OMNI domain, and are derived 1078 from the IPv6 Unique Local Address prefix fc00::/7 followed by the L 1079 bit set to 1 (i.e., as fd00::/8) followed by a 40-bit pseudo-random 1080 Global ID to produce the prefix [ULA]::/48, which is then followed by 1081 a 16-bit Subnet ID then finally followed by a 64 bit Interface ID as 1082 specified in Section 3 of [RFC4193]. All nodes in the same OMNI 1083 domain configure the same 40-bit Global ID as the OMNI domain 1084 identifier. The statistic uniqueness of the 40-bit pseudo-random 1085 Global ID allows different OMNI domains to be joined together in the 1086 future without requiring renumbering. 1088 Each OMNI link instance is identified by a value between 0x0000 and 1089 0xfeff in bits 48-63 of [ULA]::/48 (the values 0xff00 through 0xffff 1090 are reserved for future use). For example, OMNI ULAs associated with 1091 instance 0 are configured from the prefix [ULA]:0000::/64, instance 1 1092 from [ULA]:0001::/64, instance 2 from [ULA]:0002::/64, etc. ULAs and 1093 their associated prefix lengths are configured in correspondence with 1094 LLAs through stateless prefix translation where "MNP-ULAs" are 1095 assigned in correspondence to MNP-LLAs and "ADM-ULAs" are assigned in 1096 correspondence to ADM-LLAs. For example, for OMNI link instance 1097 [ULA]:1010::/64: 1099 o the MNP-ULA corresponding to the MNP-LLA fe80::2001:db8:1:2 with a 1100 56-bit MNP length is derived by copying the lower 64 bits of the 1101 LLA into the lower 64 bits of the ULA as 1102 [ULA]:1010:2001:db8:1:2/120 (where, the ULA prefix length becomes 1103 64 plus the IPv6 MNP length). 1105 o the MNP-ULA corresponding to fe80::ffff:192.0.2.0 with a 28-bit 1106 MNP length is derived by simply writing the LLA interface ID into 1107 the lower 64 bits as [ULA]:1010:0:ffff:192.0.2.0/124 (where, the 1108 ULA prefix length is 64 plus 32 plus the IPv4 MNP length). 1110 o the ADM-ULA corresponding to fe80::1000/112 is simply 1111 [ULA]:1010::1000/112. 1113 o the ADM-ULA corresponding to fe80::/128 is simply 1114 [ULA]:1010::/128. 1116 o the Temporary ULA corresponding to a Temporary LLA is simply 1117 [ULA]:1010:[64-bit Temporary Interface ID]/128. 1119 o etc. 1121 Each OMNI interface assigns the Anycast ADM-ULA specific to the OMNI 1122 link instance. For example, the OMNI interface connected to instance 1123 3 assigns the Anycast address [ULA]:0003::/128. Routers that 1124 configure OMNI interfaces advertise the OMNI service prefix (e.g., 1125 [ULA]:0003::/64) into the local routing system so that applications 1126 can direct traffic according to SBM requirements. 1128 The ULA presents an IPv6 address format that is routable within the 1129 OMNI routing system and can be used to convey link-scoped IPv6 ND 1130 messages across multiple hops using IPv6 encapsulation [RFC2473]. 1131 The OMNI link extends across one or more underling Internetworks to 1132 include all ARs and MSEs. All MNs are also considered to be 1133 connected to the OMNI link, however OAL encapsulation is omitted 1134 whenever possible to conserve bandwidth (see: Section 12). 1136 Each OMNI link can be subdivided into "segments" that often 1137 correspond to different administrative domains or physical 1138 partitions. OMNI nodes can use IPv6 Segment Routing [RFC8402] when 1139 necessary to support efficient packet forwarding to destinations 1140 located in other OMNI link segments. A full discussion of Segment 1141 Routing over the OMNI link appears in [I-D.templin-intarea-6706bis]. 1143 Note: IPv6 ULAs taken from the prefix fc00::/7 followed by the L bit 1144 set to 0 (i.e., as fc00::/8) are never used for OMNI OAL addressing, 1145 however the range could be used for MSP and MNP addressing under 1146 certain limiting conditions (see: Section 9). 1148 9. Global Unicast Addresses (GUAs) 1150 OMNI domains use IP Global Unicast Address (GUA) prefixes [RFC4291] 1151 as Mobility Service Prefixes (MSPs) from which Mobile Network 1152 Prefixes (MNP) are delegated to Mobile Nodes (MNs). 1154 For IPv6, GUA prefixes are assigned by IANA [IPV6-GUA] and/or an 1155 associated regional assigned numbers authority such that the OMNI 1156 domain can be interconnected to the global IPv6 Internet without 1157 causing inconsistencies in the routing system. An OMNI domain could 1158 instead use ULAs with the 'L' bit set to 0 (i.e., from the prefix 1159 fc00::/8)[RFC4193], however this would require IPv6 NAT if the domain 1160 were ever connected to the global IPv6 Internet. 1162 For IPv4, GUA prefixes are assigned by IANA [IPV4-GUA] and/or an 1163 associated regional assigned numbers authority such that the OMNI 1164 domain can be interconnected to the global IPv4 Internet without 1165 causing routing inconsistencies. An OMNI domain could instead use 1166 private IPv4 prefixes (e.g., 10.0.0.0/8, etc.) [RFC3330], however 1167 this would require IPv4 NAT if the domain were ever connected to the 1168 global IPv4 Internet. 1170 10. Address Mapping - Unicast 1172 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 1173 state and use the link-local address format specified in Section 7. 1174 OMNI interface IPv6 Neighbor Discovery (ND) [RFC4861] messages sent 1175 over physical underlying interfaces without encapsulation observe the 1176 native underlying interface Source/Target Link-Layer Address Option 1177 (S/TLLAO) format (e.g., for Ethernet the S/TLLAO is specified in 1178 [RFC2464]). OMNI interface IPv6 ND messages sent over underlying 1179 interfaces via encapsulation do not include S/TLLAOs which were 1180 intended for encoding physical L2 media address formats and not 1181 encapsulation IP addresses. Furthermore, S/TLLAOs are not intended 1182 for encoding additional interface attributes needed for multilink 1183 coordination. Hence, this document does not define an S/TLLAO format 1184 but instead defines a new option type termed the "OMNI option" 1185 designed for these purposes. 1187 MNs such as aircraft typically have many wireless data link types 1188 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 1189 etc.) with diverse performance, cost and availability properties. 1190 The OMNI interface would therefore appear to have multiple L2 1191 connections, and may include information for multiple underlying 1192 interfaces in a single IPv6 ND message exchange. OMNI interfaces use 1193 an IPv6 ND option called the OMNI option formatted as shown in 1194 Figure 4: 1196 0 1 2 3 1197 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 1198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1199 | Type | Length |T| Preflen | S/T-omIndex | 1200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1201 | | 1202 ~ Sub-Options ~ 1203 | | 1204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1206 Figure 4: OMNI Option Format 1208 In this format: 1210 o Type is set to TBD1. 1212 o Length is set to the number of 8 octet blocks in the option. The 1213 value 0 is invalid, while the values 1 through 255 (i.e., 8 1214 through 2040 octets, respectively) indicate the total length of 1215 the OMNI option. 1217 o T is a 1-bit flag set to 1 for Temporary LLAs (otherwise, set to 1218 0) and Preflen is a 7 bit field that determines the length of 1219 prefix associated with an LLA. Values 1 through 127 specify a 1220 prefix length, while the value 0 indicates "unspecified". For 1221 IPv6 ND messages sent from a MN to the MS, T and Preflen apply to 1222 the IPv6 source LLA and provide the length that the MN is 1223 requesting or asserting to the MS. For IPv6 ND messages sent from 1224 the MS to the MN, T and Preflen apply to the IPv6 destination LLA 1225 and indicate the length that the MS is granting to the MN. For 1226 IPv6 ND messages sent between MS endpoints, T is set to 0 and 1227 Preflen provides the length associated with the source/target MN 1228 that is subject of the ND message. 1230 o S/T-omIndex corresponds to the omIndex value for source or target 1231 underlying interface used to convey this IPv6 ND message. OMNI 1232 interfaces MUST number each distinct underlying interface with an 1233 omIndex value between '1' and '255' that represents a MN-specific 1234 8-bit mapping for the actual ifIndex value assigned by network 1235 management [RFC2863] (the omIndex value '0' is reserved for use by 1236 the MS). For RS and NS messages, S/T-omIndex corresponds to the 1237 source underlying interface the message originated from. For RA 1238 and NA messages, S/T-omIndex corresponds to the target underlying 1239 interface that the message is destined to. (For NS messages used 1240 for Neighbor Unreachability Detection (NUD), S/T-omIndex instead 1241 identifies the neighbor's underlying interface to be used as the 1242 target interface to return the NA.) 1244 o Sub-Options is a Variable-length field, of length such that the 1245 complete OMNI Option is an integer multiple of 8 octets long. 1246 Contains one or more Sub-Options, as described in Section 10.1. 1248 The OMNI option may appear in any IPv6 ND message type; it is 1249 processed by interfaces that recognize the option and ignored by all 1250 other interfaces. If multiple OMNI option instances appear in the 1251 same IPv6 ND message, the interface processes the T, Preflen and S/ 1252 T-omIndex fields in the first instance and ignores those fields in 1253 all other instances. The interface processes the Sub-Options of all 1254 OMNI option instances in the consecutive order in which they appear 1255 in the IPv6 ND message, beginning with the first instance and 1256 continuing consecutively through any additional instances to the end 1257 of the message. 1259 The OMNI option(s) in each IPv6 ND message may include full or 1260 partial information for the neighbor. The union of the information 1261 in the most recently received OMNI options is therefore retained, and 1262 the information is aged/removed in conjunction with the corresponding 1263 neighbor cache entry. 1265 10.1. Sub-Options 1267 The OMNI option includes zero or more Sub-Options. Each consecutive 1268 Sub-Option is concatenated immediately after its predecessor. All 1269 Sub-Options except Pad1 (see below) are in type-length-value (TLV) 1270 encoded in the following format: 1272 0 1 2 1273 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 1274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1275 | Sub-Type| Sub-length | Sub-Option Data ... 1276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1278 Figure 5: Sub-Option Format 1280 o Sub-Type is a 5-bit field that encodes the Sub-Option type. Sub- 1281 Options defined in this document are: 1283 Option Name Sub-Type 1284 Pad1 0 1285 PadN 1 1286 Interface Attributes (Type 1) 2 1287 Interface Attributes (Type 2) 3 1288 Traffic Selector 4 1289 Origin Indication 5 1290 MS-Register 6 1291 MS-Release 7 1292 Geo Coordinates 8 1293 DHCPv6 Message 9 1294 HIP Message 10 1295 Node Identification 11 1297 Figure 6 1299 Sub-Types 12-29 are available for future assignment. Sub-Type 30 1300 is reserved for experimentation, as recommended in [RFC3692]. 1301 Sub-Type 31 is reserved by IANA. 1303 o Sub-Length is an 11-bit field that encodes the length of the Sub- 1304 Option Data ranging from 0 to 2034 octets (the values 2035 through 1305 2047 are invalid, since each OMNI option is limited to 2040 1306 octets). 1308 o Sub-Option Data is a block of data with format determined by Sub- 1309 Type and length determined by Sub-Length. 1311 Note that Sub-Type and Sub-Length are coded together in network byte 1312 order in two consecutive octets. Note also that Sub-Option Data may 1313 be up to 2034 octets in length. This allows ample space for encoding 1314 large objects (e.g., ascii character strings, protocol messages, 1315 security codes, etc.), while a single OMNI option is limited to 2040 1316 octets the same as for any IPv6 ND option. If the Sub-Options to be 1317 coded would cause an OMNI option to exceed 2040 octets, any remaining 1318 Sub-Options are encoded in additional OMNI options in the consecutive 1319 order of intended processing. Implementations must therefore be 1320 mindful of size limitations, and must refrain from sending IPv6 ND 1321 messages larger than the OMNI interface MTU. 1323 During processing, unrecognized Sub-Options are ignored and the next 1324 Sub-Option processed until the end of the OMNI option is reached. 1326 The following Sub-Option types and formats are defined in this 1327 document: 1329 10.1.1. Pad1 1331 0 1332 0 1 2 3 4 5 6 7 1333 +-+-+-+-+-+-+-+-+ 1334 | S-Type=0|x|x|x| 1335 +-+-+-+-+-+-+-+-+ 1337 Figure 7: Pad1 1339 o Sub-Type is set to 0. If multiple instances appear in OMNI 1340 options of the same message all are processed. 1342 o Sub-Type is followed by three 'x' bits, set randomly on 1343 transmission and ignored on receipt. Pad1 therefore consists of a 1344 whole single octet with the most significant 5 bits set to 0, and 1345 with no Sub-Length or Sub-Option Data fields following. 1347 10.1.2. PadN 1349 0 1 2 1350 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 1351 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1352 | S-Type=1| Sub-length=N | N padding octets ... 1353 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1355 Figure 8: PadN 1357 o Sub-Type is set to 1. If multiple instances appear in OMNI 1358 options of the same message all are processed. 1360 o Sub-Length is set to N (from 0 to 2034 being the number of padding 1361 octets that follow. 1363 o Sub-Option Data consists of N zero-valued octets. 1365 10.1.3. Interface Attributes (Type 1) 1367 The Interface Attributes (Type 1) sub-option provides a basic set of 1368 attributes for underlying interfaces. Interface Attributes (Type 1) 1369 is deprecated throughout the rest of this specification, and 1370 Interface Attributes (Type 2) (see: Section 10.1.4) are indicated 1371 wherever the term "Interface Attributes" appears without an 1372 associated Type designation. 1374 Nodes SHOULD NOT include Interface Attributes (Type 1) sub-options in 1375 IPv6 ND messages they send, and MUST ignore any in IPv6 ND messages 1376 they receive. If an Interface Attributes (Type 1) is included, it 1377 must have the following format: 1379 0 1 2 3 1380 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 1381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1382 | Sub-Type=2| Sub-length=N | omIndex | omType | 1383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1384 | Provider ID | Link | Resvd |P00|P01|P02|P03|P04|P05|P06|P07| 1385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1386 |P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19|P20|P21|P22|P23| 1387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1388 |P24|P25|P26|P27|P28|P29|P30|P31|P32|P33|P34|P35|P36|P37|P38|P39| 1389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1390 |P40|P41|P42|P43|P44|P45|P46|P47|P48|P49|P50|P51|P52|P53|P54|P55| 1391 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1392 |P56|P57|P58|P59|P60|P61|P62|P63| 1393 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1395 Figure 9: Interface Attributes (Type 1) 1397 o Sub-Type is set to 2. If multiple instances with different 1398 omIndex values appear in OMNI option of the same message all are 1399 processed; if multiple instances with the same omIndex value 1400 appear, the first is processed and all others are ignored 1402 o Sub-Length is set to N (from 4 to 2034 that encodes the number of 1403 Sub-Option Data octets that follow. 1405 o omIndex is a 1-octet field containing a value from 0 to 255 1406 identifying the underlying interface for which the attributes 1407 apply. 1409 o omType is a 1-octet field containing a value from 0 to 255 1410 corresponding to the underlying interface identified by omIndex. 1412 o Provider ID is a 1-octet field containing a value from 0 to 255 1413 corresponding to the underlying interface identified by omIndex. 1415 o Link encodes a 4-bit link metric. The value '0' means the link is 1416 DOWN, and the remaining values mean the link is UP with metric 1417 ranging from '1' ("lowest") to '15' ("highest"). 1419 o Resvd is reserved for future use. 1421 o A 16-octet ""Preferences" field immediately follows 'Resvd', with 1422 values P[00] through P[63] corresponding to the 64 Differentiated 1423 Service Code Point (DSCP) values [RFC2474]. Each 2-bit P[*] field 1424 is set to the value '0' ("disabled"), '1' ("low"), '2' ("medium") 1425 or '3' ("high") to indicate a QoS preference for underlying 1426 interface selection purposes. 1428 10.1.4. Interface Attributes (Type 2) 1430 The Interface Attributes (Type 2) sub-option provides L2 forwarding 1431 information for the multilink conceptual sending algorithm discussed 1432 in Section 12. The L2 information is used for selecting among 1433 potentially multiple candidate underlying interfaces that can be used 1434 to forward packets to the neighbor based on factors such as DSCP 1435 preferences and link quality. Interface Attributes (Type 2) further 1436 includes link-layer address information to be used for either OAL 1437 encapsulation or direct UDP/IP encapsulation (when OAL encapsulation 1438 can be avoided). 1440 Interface Attributes (Type 2) are the sole Interface Attributes 1441 format in this specification that all OMNI nodes must honor. 1442 Wherever the term "Interface Attributes" occurs throughout this 1443 specification without a "Type" designation, the format given below is 1444 indicated: 1446 0 1 2 3 1447 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 1448 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1449 | S-Type=3| Sub-length=N | omIndex | omType | 1450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1451 | Provider ID | Link |R| API | SRT | FMT | LHS (0 - 7) | 1452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1453 | LHS (bits 8 - 31) | ~ 1454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1455 ~ ~ 1456 ~ Link Layer Address (L2ADDR) ~ 1457 ~ ~ 1458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1459 | Bitmap(0)=0xff|P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11| 1460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1461 |P12|P13|P14|P15|P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27| 1462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1463 |P28|P29|P30|P31| Bitmap(1)=0xff|P32|P33|P34|P35|P36| ... 1464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1466 Figure 10: Interface Attributes (Type 2) 1468 o Sub-Type is set to 3. If multiple instances with different 1469 omIndex values appear in OMNI options of the same message all are 1470 processed; if multiple instances with the same omIndex value 1471 appear, the first is processed and all others are ignored. 1473 o Sub-Length is set to N (from 4 to 2034) that encodes the number of 1474 Sub-Option Data octets that follow. 1476 o Sub-Option Data contains an "Interface Attributes (Type 2)" option 1477 encoded as follows (note that the first four octets must be 1478 present): 1480 * omIndex is set to an 8-bit integer value corresponding to a 1481 specific underlying interface the same as specified above for 1482 the OMNI option S/T-omIndex field. The OMNI options of a same 1483 message may include multiple Interface Attributes Sub-Options, 1484 with each distinct omIndex value pertaining to a different 1485 underlying interface. The OMNI option will often include an 1486 Interface Attributes Sub-Option with the same omIndex value 1487 that appears in the S/T-omIndex. In that case, the actual 1488 encapsulation address of the received IPv6 ND message should be 1489 compared with the L2ADDR encoded in the Sub-Option (see below); 1490 if the addresses are different (or, if L2ADDR is absent) the 1491 presence of a NAT is assumed. 1493 * omType is set to an 8-bit integer value corresponding to the 1494 underlying interface identified by omIndex. The value 1495 represents an OMNI interface-specific 8-bit mapping for the 1496 actual IANA ifType value registered in the 'IANAifType-MIB' 1497 registry [http://www.iana.org]. 1499 * Provider ID is set to an OMNI interface-specific 8-bit ID value 1500 for the network service provider associated with this omIndex. 1502 * Link encodes a 4-bit link metric. The value '0' means the link 1503 is DOWN, and the remaining values mean the link is UP with 1504 metric ranging from '1' ("lowest") to '15' ("highest"). 1506 * R is reserved for future use. 1508 * API - a 3-bit "Address/Preferences/Indexed" code that 1509 determines the contents of the remainder of the sub-option as 1510 follows: 1512 + When the most significant bit (i.e., "Address") is set to 1, 1513 the SRT, FMT, LHS and L2ADDR fields are included immediately 1514 following the API code; else, they are omitted. 1516 + When the next most significant bit (i.e., "Preferences") is 1517 set to 1, a preferences block is included next; else, it is 1518 omitted. (Note that if "Address" is set the preferences 1519 block immediately follows L2ADDR; else, it immediately 1520 follows the API code.) 1522 + When a preferences block is present and the least 1523 significant bit (i.e., "Indexed") is set to 0, the block is 1524 encoded in "Simplex" form as shown in Figure 9; else it is 1525 encoded in "Indexed" form as discussed below. 1527 * When API indicates that an "Address" is included, the following 1528 fields appear in consecutive order (else, they are omitted): 1530 + SRT - a 5-bit Segment Routing Topology prefix length value 1531 that (when added to 96) determines the prefix length to 1532 apply to the ULA formed from concatenating [ULA*]::/96 with 1533 the 32 bit LHS MSID value that follows. For example, the 1534 value 16 corresponds to the prefix length 112. 1536 + FMT - a 3-bit "Framework/Mode/Type" code corresponding to 1537 the included Link Layer Address as follows: 1539 - When the most significant bit (i.e., "Framework") is set 1540 to 0, L2ADDR is the INET encapsulation address of a 1541 Proxy/Server; otherwise, it is the address for the 1542 Source/Target itself 1544 - When the next most significant bit (i.e., "Mode") is set 1545 to 0, the Source/Target L2ADDR is on the open INET; 1546 otherwise, it is (likely) located behind one or more 1547 NATs. 1549 - When the least significant bit (i.e., "Type") is set to 1550 0, L2ADDR includes a UDP Port Number followed by an IPv4 1551 address; else, a UDP Port Number followed by an IPv6 1552 address. 1554 + LHS - the 32 bit MSID of the Last Hop Server/Proxy on the 1555 path to the target. When SRT and LHS are both set to 0, the 1556 LHS is considered unspecified in this IPv6 ND message. When 1557 SRT is set to 0 and LHS is non-zero, the prefix length is 1558 set to 128. SRT and LHS together provide guidance to the 1559 OMNI interface forwarding algorithm. Specifically, if SRT/ 1560 LHS is located in the local OMNI link segment then the OMNI 1561 interface can encapsulate according to FMT/L2ADDR (following 1562 any necessary NAT traversal messaging); else, it must 1563 forward according to the OMNI link spanning tree. See 1564 [I-D.templin-intarea-6706bis] for further discussion. 1566 + Link Layer Address (L2ADDR) - Formatted according to FMT, 1567 and identifies the link-layer address (i.e., the 1568 encapsulation address) of the source/target. The UDP Port 1569 Number appears in the first two octets and the IP address 1570 appears in the next 4 octets for IPv4 or 16 octets for IPv6. 1571 The Port Number and IP address are recorded in ones- 1572 compliment "obfuscated" form per [RFC4380]. The OMNI 1573 interface forwarding algorithm uses FMT/L2ADDR to determine 1574 the encapsulation address for forwarding when SRT/LHS is 1575 located in the local OMNI link segment. Note that if the 1576 target is behind a NAT, L2ADDR will contain the mapped INET 1577 address stored in the NAT; otherwise, L2ADDR will contain 1578 the native INET information of the target itself. 1580 * When API indicates that "Preferences" are included, a 1581 preferences block appears as the remainder of the Sub-Option as 1582 a series of Bitmaps and P[*] values. In "Simplex" form, the 1583 index for each singleton Bitmap octet is inferred from its 1584 sequential position (i.e., 0, 1, 2, ...) as shown in Figure 9. 1585 In "Indexed" form, each Bitmap is preceded by an Index octet 1586 that encodes a value "i" = (0 - 255) as the index for its 1587 companion Bitmap as follows: 1589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1590 | Index=i | Bitmap(i) |P[*] values ... 1591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1593 Figure 11 1595 * The preferences consist of a first (simplex/indexed) Bitmap 1596 (i.e., "Bitmap(i)") followed by 0-8 single-octet blocks of 1597 2-bit P[*] values, followed by a second Bitmap (i), followed by 1598 0-8 blocks of P[*] values, etc. Reading from bit 0 to bit 7, 1599 the bits of each Bitmap(i) that are set to '1'' indicate the 1600 P[*] blocks from the range P[(i*32)] through P[(i*32) + 31] 1601 that follow; if any Bitmap(i) bits are '0', then the 1602 corresponding P[*] block is instead omitted. For example, if 1603 Bitmap(0) contains 0xff then the block with P[00]-P[03], 1604 followed by the block with P[04]-P[07], etc., and ending with 1605 the block with P[28]-P[31] are included (as shown in Figure 9). 1606 The next Bitmap(i) is then consulted with its bits indicating 1607 which P[*] blocks follow, etc. out to the end of the Sub- 1608 Option. 1610 * Each 2-bit P[*] field is set to the value '0' ("disabled"), '1' 1611 ("low"), '2' ("medium") or '3' ("high") to indicate a QoS 1612 preference for underlying interface selection purposes. Not 1613 all P[*] values need to be included in the OMNI option of each 1614 IPv6 ND message received. Any P[*] values represented in an 1615 earlier OMNI option but omitted in the current OMNI option 1616 remain unchanged. Any P[*] values not yet represented in any 1617 OMNI option default to "medium". 1619 * The first 16 P[*] blocks correspond to the 64 Differentiated 1620 Service Code Point (DSCP) values P[00] - P[63] [RFC2474]. Any 1621 additional P[*] blocks that follow correspond to "pseudo-DSCP" 1622 traffic classifier values P[64], P[65], P[66], etc. See 1623 Appendix A for further discussion and examples. 1625 10.1.5. Traffic Selector 1626 0 1 2 3 1627 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 1628 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1629 | S-Type=4| Sub-length=N | omIndex | ~ 1630 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1631 ~ ~ 1632 ~ RFC 6088 Format Traffic Selector ~ 1633 ~ ~ 1634 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1636 Figure 12: Traffic Selector 1638 o Sub-Type is set to 4. If multiple instances appear in OMNI 1639 options of the same message all are processed, i.e., even if the 1640 same omIndex value appears multiple times. 1642 o Sub-Length is set to N (the number of Sub-Option Data octets that 1643 follow). 1645 o Sub-Option Data contains a 1-octet omIndex encoded exactly as 1646 specified in Section 10.1.3, followed by an N-1 octet traffic 1647 selector formatted per [RFC6088] beginning with the "TS Format" 1648 field. The largest traffic selector for a given omIndex is 1649 therefore 2033 octets. 1651 10.1.6. Origin Indication 1653 0 1 2 3 1654 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 1655 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1656 | S-Type=5| Sub-length=6/18 | Origin Port Number | 1657 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1658 ~ Origin IPv4/IPv6 Address ~ 1659 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1661 Figure 13: Origin Indication 1663 o Sub-Type is set to 5. If multiple instances appear in OMNI 1664 options of the same message the first instance is processed and 1665 all others are ignored. 1667 o Sub-Length is set to either 6 or 18; if Sub-Length encodes any 1668 other value, the Sub-Option is ignored. 1670 o Sub-Option Data contains a 2-octet Port Number followed by a 1671 4-octet IPv4 address if Sub-Length encodes 6 or a 16-octet IPv6 1672 address if Sub-Length encodes 18. 1674 10.1.7. MS-Register 1676 0 1 2 3 1677 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 1678 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1679 | S-Type=6| Sub-length=4n | MSID[1] (bits 0 - 15) | 1680 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1681 | MSID [1] (bits 16 - 32) | MSID[2] (bits 0 - 15) | 1682 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1683 | MSID [2] (bits 16 - 32) | MSID[3] (bits 0 - 15) | 1684 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1685 ... ... ... ... ... ... 1686 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1687 | MSID [n] (bits 16 - 32) | 1688 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1690 Figure 14: MS-Register Sub-option 1692 o Sub-Type is set to 6. If multiple instances appear in OMNI 1693 options of the same message all are processed. Only the first 1694 MAX_MSID values processed (whether in a single instance or 1695 multiple) are retained and all other MSIDs are ignored. 1697 o Sub-Length is set to 4n, with 508 as the maximum value for n. 1699 o A list of n 4-octet MSIDs is included in the following 4n octets. 1700 The Anycast MSID value '0' in an RS message MS-Register sub-option 1701 requests the recipient to return the MSID of a nearby MSE in a 1702 corresponding RA response. 1704 10.1.8. MS-Release 1706 0 1 2 3 1707 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 1708 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1709 | S-Type=7| Sub-length=4n | MSID[1] (bits 0 - 15) | 1710 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1711 | MSID [1] (bits 16 - 32) | MSID[2] (bits 0 - 15) | 1712 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1713 | MSID [2] (bits 16 - 32) | MSID[3] (bits 0 - 15) | 1714 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1715 ... ... ... ... ... ... 1716 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1717 | MSID [n] (bits 16 - 32) | 1718 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1720 Figure 15: MS-Release Sub-option 1722 o Sub-Type is set to 7. If multiple instances appear in OMNI 1723 options of the same message all are processed. Only the first 1724 MAX_MSID values processed (whether in a single instance or 1725 multiple) are retained and all other MSIDs are ignored. 1727 o Sub-Length is set to 4n, with 508 as the maximum value for n. 1729 o A list of n 4 octet MSIDs is included in the following 4n octets. 1730 The Anycast MSID value '0' is ignored in MS-Release sub-options, 1731 i.e., only non-zero values are processed. 1733 10.1.9. Geo Coordinates 1735 0 1 2 3 1736 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 1737 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1738 | S-Type=8| Sub-length=N | Geo Coordinates 1739 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... 1741 Figure 16: Geo Coordinates Sub-option 1743 o Sub-Type is set to 8. If multiple instances appear in OMNI 1744 options of the same message the first is processed and all others 1745 are ignored. 1747 o Sub-Length is set to N (i.e., the length of the encoded Geo 1748 Coordinates up to a maximum of 2034 octets). 1750 o A set of Geo Coordinates. Format(s) to be specified in future 1751 documents; should include Latitude/Longitude, plus any additional 1752 attributes such as altitude, heading, speed, etc. 1754 10.1.10. Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Message 1756 0 1 2 3 1757 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 1758 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1759 | S-Type=9| Sub-length=N | msg-type | id (octet 0) | 1760 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1761 | transaction-id (octets 1-2) | | 1762 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1763 | | 1764 . DHCPv6 options . 1765 . (variable number and length) . 1766 | | 1767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1769 Figure 17: DHCPv6 Message Sub-option 1771 o Sub-Type is set to 9. If multiple instances appear in OMNI 1772 options of the same message the first is processed and all others 1773 are ignored. 1775 o Sub-Length is set to N (i.e., the length of the DHCPv6 message 1776 beginning with 'msg-type' and continuing to the end of the DHCPv6 1777 options). The length of the entire DHCPv6 message is therefore 1778 restricted to 2034 octets. 1780 o 'msg-type' and 'transaction-id' are coded according to Section 8 1781 of [RFC8415]. 1783 o A set of DHCPv6 options coded according to Section 21 of [RFC8415] 1784 follows. 1786 10.1.11. Host Identity Protocol (HIP) Message 1788 0 1 2 3 1789 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 1790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1791 |S-Type=10| Sub-length=N |0| Packet Type |Version| RES.|1| 1792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1793 | Checksum | Controls | 1794 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1795 | Sender's Host Identity Tag (HIT) | 1796 | | 1797 | | 1798 | | 1799 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1800 | Receiver's Host Identity Tag (HIT) | 1801 | | 1802 | | 1803 | | 1804 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1805 | | 1806 / HIP Parameters / 1807 / / 1808 | | 1809 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1811 Figure 18: HIP Message Sub-option 1813 o Sub-Type is set to 10. If multiple instances appear in OMNI 1814 options of the same message the first is processed and all others 1815 are ignored. 1817 o Sub-Length is set to N, i.e., the length of the option in octets 1818 beginning immediately following the Sub-Length field and extending 1819 to the end of the HIP parameters. The length of the entire HIP 1820 message is therefore restricted to 2034 octets. 1822 o The HIP message is coded exactly as specified in Section 5 of 1823 [RFC7401], with the exception that the OMNI "Sub-Type" and "Sub- 1824 Length" fields replace the first two header octets of the HIP 1825 message (i.e., the Next Header and Header Length fields). 1827 10.1.12. Node Identification 1829 0 1 2 3 1830 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 1831 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1832 |S-Type=11| Sub-length=N | ID-Type | ~ 1833 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1834 ~ Node Identification Value (N-1 octets) ~ 1835 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1837 Figure 19: Node Identification 1839 o Sub-Type is set to 11. If multiple instances appear in OMNI 1840 options of the same IPv6 ND message the first instance of a 1841 specific ID-Type is processed and all other instances of the same 1842 ID-Type are ignored. (Note therefore that it is possible for a 1843 single IPv6 ND message to convey multiple Node Identifications - 1844 each having a different ID-Type.) 1846 o Sub-Length is set to N, i.e., the combined length of the ID-Type 1847 and Node Identification Value fields. The maximum Node 1848 Identification Value length is therefore 2033 octets. 1850 o ID-Type is a one-octet field that encodes the type of the Node 1851 Identification Value. The following ID-Type values are currently 1852 defined: 1854 * 0 - Universally Unique IDentifier (UUID) [RFC4122]. Indicates 1855 that Node Identification Value contains a 16 octet UUID. 1857 * 1 - Host Identity Tag (HIT) [RFC7401]. Indicates that Node 1858 Identification Value contains a 16 octet HIT. 1860 * 2 - Hierarchical HIT (HHIT) [I-D.ietf-drip-rid]. Indicates 1861 that Node Identification Value contains a 16 octet HHIT. 1863 * 3 - Network Access Identifier (NAI) [RFC7542]. Indicates that 1864 Node Identification Value contains an N-1 octet NAI. 1866 * 4 - Fully-Qualified Domain Name (FQDN) [RFC1035]. Indicates 1867 that Node Identification Value contains an N-1 octet FQDN. 1869 * 5 - 252 - Unassigned. 1871 * 253-254 - Reserved for experimentation, as recommended in 1872 [RFC3692]. 1874 * 255 - reserved by IANA. 1876 o Node Identification Value is an (N - 1)-octet field encoded 1877 according to the appropriate the "ID-Type" reference above. 1879 11. Address Mapping - Multicast 1881 The multicast address mapping of the native underlying interface 1882 applies. The mobile router on board the MN also serves as an IGMP/ 1883 MLD Proxy for its EUNs and/or hosted applications per [RFC4605] while 1884 using the L2 address of the AR as the L2 address for all multicast 1885 packets. 1887 The MN uses Multicast Listener Discovery (MLDv2) [RFC3810] to 1888 coordinate with the AR, and *NET L2 elements use MLD snooping 1889 [RFC4541]. 1891 12. Multilink Conceptual Sending Algorithm 1893 The MN's IPv6 layer selects the outbound OMNI interface according to 1894 SBM considerations when forwarding data packets from local or EUN 1895 applications to external correspondents. Each OMNI interface 1896 maintains a neighbor cache the same as for any IPv6 interface, but 1897 with additional state for multilink coordination. Each OMNI 1898 interface maintains default routes via ARs discovered as discussed in 1899 Section 13, and may configure more-specific routes discovered through 1900 means outside the scope of this specification. 1902 After a packet enters the OMNI interface, one or more outbound 1903 underlying interfaces are selected based on PBM traffic attributes, 1904 and one or more neighbor underlying interfaces are selected based on 1905 the receipt of Interface Attributes sub-options in IPv6 ND messages 1906 (see: Figure 9). Underlying interface selection for the nodes own 1907 local interfaces are based on attributes such as DSCP, application 1908 port number, cost, performance, message size, etc. OMNI interface 1909 multilink selections could also be configured to perform replication 1910 across multiple underlying interfaces for increased reliability at 1911 the expense of packet duplication. The set of all Interface 1912 Attributes received in IPv6 ND messages determines the multilink 1913 forwarding profile for selecting the neighbor's underlying 1914 interfaces. 1916 When the OMNI interface sends a packet over a selected outbound 1917 underlying interface, the OAL includes or omits a mid-layer 1918 encapsulation header as necessary as discussed in Section 5 and as 1919 determined by the L2 address information received in Interface 1920 Attributes. The OAL also performs encapsulation when the nearest AR 1921 is located multiple hops away as discussed in Section 13.1. (Note 1922 that the OAL MAY employ packing when multiple packets are available 1923 for forwarding to the same destination.) 1925 OMNI interface multilink service designers MUST observe the BCP 1926 guidance in Section 15 [RFC3819] in terms of implications for 1927 reordering when packets from the same flow may be spread across 1928 multiple underlying interfaces having diverse properties. 1930 12.1. Multiple OMNI Interfaces 1932 MNs may connect to multiple independent OMNI links concurrently in 1933 support of SBM. Each OMNI interface is distinguished by its Anycast 1934 ULA (e.g., [ULA]:0002::, [ULA]:1000::, [ULA]:7345::, etc.). The MN 1935 configures a separate OMNI interface for each link so that multiple 1936 interfaces (e.g., omni0, omni1, omni2, etc.) are exposed to the IPv6 1937 layer. A different Anycast ULA is assigned to each interface, and 1938 the MN injects the service prefixes for the OMNI link instances into 1939 the EUN routing system. 1941 Applications in EUNs can use Segment Routing to select the desired 1942 OMNI interface based on SBM considerations. The Anycast ULA is 1943 written into the IPv6 destination address, and the actual destination 1944 (along with any additional intermediate hops) is written into the 1945 Segment Routing Header. Standard IP routing directs the packets to 1946 the MN's mobile router entity, and the Anycast ULA identifies the 1947 OMNI interface to be used for transmission to the next hop. When the 1948 MN receives the message, it replaces the IPv6 destination address 1949 with the next hop found in the routing header and transmits the 1950 message over the OMNI interface identified by the Anycast ULA. 1952 Multiple distinct OMNI links can therefore be used to support fault 1953 tolerance, load balancing, reliability, etc. The architectural model 1954 is similar to Layer 2 Virtual Local Area Networks (VLANs). 1956 12.2. MN<->AR Traffic Loop Prevention 1958 After an AR has registered an MNP for a MN (see: Section 13), the AR 1959 will forward packets destined to an address within the MNP to the MN. 1961 The MN will under normal circumstances then forward the packet to the 1962 correct destination within its internal networks. 1964 If at some later time the MN loses state (e.g., after a reboot), it 1965 may begin returning packets destined to an MNP address to the AR as 1966 its default router. The AR therefore must drop any packets 1967 originating from the MN and destined to an address within the MN's 1968 registered MNP. To do so, the AR institutes the following check: 1970 o if the IP destination address belongs to a neighbor on the same 1971 OMNI interface, and if the link-layer source address is the same 1972 as one of the neighbor's link-layer addresses, drop the packet. 1974 13. Router Discovery and Prefix Registration 1976 MNs interface with the MS by sending RS messages with OMNI options 1977 under the assumption that one or more AR on the *NET will process the 1978 message and respond. The MN then configures default routes for the 1979 OMNI interface via the discovered ARs as the next hop. The manner in 1980 which the *NET ensures AR coordination is link-specific and outside 1981 the scope of this document (however, considerations for *NETs that do 1982 not provide ARs that recognize the OMNI option are discussed in 1983 Section 18). 1985 For each underlying interface, the MN sends an RS message with an 1986 OMNI option to coordinate with MSEs identified by MSID values. 1987 Example MSID discovery methods are given in [RFC5214] and include 1988 data link login parameters, name service lookups, static 1989 configuration, a static "hosts" file, etc. The MN can also send an 1990 RS with an MS-Register sub-option that includes the Anycast MSID 1991 value '0', i.e., instead of or in addition to any non-zero MSIDs. 1992 When the AR receives an RS with a MSID '0', it selects a nearby MSE 1993 (which may be itself) and returns an RA with the selected MSID in an 1994 MS-Register sub-option. The AR selects only a single wildcard MSE 1995 (i.e., even if the RS MS-Register sub-option included multiple '0' 1996 MSIDs) while also soliciting the MSEs corresponding to any non-zero 1997 MSIDs. 1999 MNs configure OMNI interfaces that observe the properties discussed 2000 in the previous section. The OMNI interface and its underlying 2001 interfaces are said to be in either the "UP" or "DOWN" state 2002 according to administrative actions in conjunction with the interface 2003 connectivity status. An OMNI interface transitions to UP or DOWN 2004 through administrative action and/or through state transitions of the 2005 underlying interfaces. When a first underlying interface transitions 2006 to UP, the OMNI interface also transitions to UP. When all 2007 underlying interfaces transition to DOWN, the OMNI interface also 2008 transitions to DOWN. 2010 When an OMNI interface transitions to UP, the MN sends RS messages to 2011 register its MNP and an initial set of underlying interfaces that are 2012 also UP. The MN sends additional RS messages to refresh lifetimes 2013 and to register/deregister underlying interfaces as they transition 2014 to UP or DOWN. The MN sends initial RS messages over an UP 2015 underlying interface with its MNP-LLA as the source and with 2016 destination set to All-Routers multicast (ff02::2) [RFC4291]. The RS 2017 messages include an OMNI option per Section 10 with a Preflen 2018 assertion, Interface Attributes appropriate for underlying 2019 interfaces, MS-Register/Release sub-options containing MSID values, 2020 and with any other necessary OMNI sub-options (e.g., a DUID sub- 2021 option as an identity for the MN). The S/T-omIndex field is set to 2022 the index of the underlying interface over which the RS message is 2023 sent. 2025 ARs process IPv6 ND messages with OMNI options and act as an MSE 2026 themselves and/or as a proxy for other MSEs. ARs receive RS messages 2027 and create a neighbor cache entry for the MN, then coordinate with 2028 any MSEs named in the Register/Release lists in a manner outside the 2029 scope of this document. When an MSE processes the OMNI information, 2030 it first validates the prefix registration information then injects/ 2031 withdraws the MNP in the routing/mapping system and caches/discards 2032 the new Preflen, MNP and Interface Attributes. The MSE then informs 2033 the AR of registration success/failure, and the AR returns an RA 2034 message to the MN with an OMNI option per Section 10. 2036 The AR returns the RA message via the same underlying interface of 2037 the MN over which the RS was received, and with destination address 2038 set to the MNP-LLA (i.e., unicast), with source address set to its 2039 own LLA, and with an OMNI option with S/T-omIndex set to the value 2040 included in the RS. The OMNI option also includes a Preflen 2041 confirmation, Interface Attributes, MS-Register/Release and any other 2042 necessary OMNI sub-options (e.g., a DUID sub-option as an identity 2043 for the AR). The RA also includes any information for the link, 2044 including RA Cur Hop Limit, M and O flags, Router Lifetime, Reachable 2045 Time and Retrans Timer values, and includes any necessary options 2046 such as: 2048 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 2050 o RIOs [RFC4191] with more-specific routes. 2052 o an MTU option that specifies the maximum acceptable packet size 2053 for this underlying interface. 2055 The AR MAY also send periodic and/or event-driven unsolicited RA 2056 messages per [RFC4861]. In that case, the S/T-omIndex field in the 2057 OMNI option of the unsolicited RA message identifies the target 2058 underlying interface of the destination MN. 2060 The AR can combine the information from multiple MSEs into one or 2061 more "aggregate" RAs sent to the MN in order conserve *NET bandwidth. 2062 Each aggregate RA includes an OMNI option with MS-Register/Release 2063 sub-options with the MSEs represented by the aggregate. If an 2064 aggregate is sent, the RA message contents must consistently 2065 represent the combined information advertised by all represented 2066 MSEs. Note that since the AR uses its own ADM-LLA as the RA source 2067 address, the MN determines the addresses of the represented MSEs by 2068 examining the MS-Register/Release OMNI sub-options. 2070 When the MN receives the RA message, it creates an OMNI interface 2071 neighbor cache entry for each MSID that has confirmed MNP 2072 registration via the L2 address of this AR. If the MN connects to 2073 multiple *NETs, it records the additional L2 AR addresses in each 2074 MSID neighbor cache entry (i.e., as multilink neighbors). The MN 2075 then configures a default route via the MSE that returned the RA 2076 message, and assigns the Subnet Router Anycast address corresponding 2077 to the MNP (e.g., 2001:db8:1:2::) to the OMNI interface. The MN then 2078 manages its underlying interfaces according to their states as 2079 follows: 2081 o When an underlying interface transitions to UP, the MN sends an RS 2082 over the underlying interface with an OMNI option. The OMNI 2083 option contains at least one Interface Attribute sub-option with 2084 values specific to this underlying interface, and may contain 2085 additional Interface Attributes specific to other underlying 2086 interfaces. The option also includes any MS-Register/Release sub- 2087 options. 2089 o When an underlying interface transitions to DOWN, the MN sends an 2090 RS or unsolicited NA message over any UP underlying interface with 2091 an OMNI option containing an Interface Attribute sub-option for 2092 the DOWN underlying interface with Link set to '0'. The MN sends 2093 an RS when an acknowledgement is required, or an unsolicited NA 2094 when reliability is not thought to be a concern (e.g., if 2095 redundant transmissions are sent on multiple underlying 2096 interfaces). 2098 o When the Router Lifetime for a specific AR nears expiration, the 2099 MN sends an RS over the underlying interface to receive a fresh 2100 RA. If no RA is received, the MN can send RS messages to an 2101 alternate MSID in case the current MSID has failed. If no RS 2102 messages are received even after trying to contact alternate 2103 MSIDs, the MN marks the underlying interface as DOWN. 2105 o When a MN wishes to release from one or more current MSIDs, it 2106 sends an RS or unsolicited NA message over any UP underlying 2107 interfaces with an OMNI option with a Release MSID. Each MSID 2108 then withdraws the MNP from the routing/mapping system and informs 2109 the AR that the release was successful. 2111 o When all of a MNs underlying interfaces have transitioned to DOWN 2112 (or if the prefix registration lifetime expires), any associated 2113 MSEs withdraw the MNP the same as if they had received a message 2114 with a release indication. 2116 The MN is responsible for retrying each RS exchange up to 2117 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 2118 seconds until an RA is received. If no RA is received over an UP 2119 underlying interface (i.e., even after attempting to contact 2120 alternate MSEs), the MN declares this underlying interface as DOWN. 2122 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 2123 Therefore, when the IPv6 layer sends an RS message the OMNI interface 2124 returns an internally-generated RA message as though the message 2125 originated from an IPv6 router. The internally-generated RA message 2126 contains configuration information that is consistent with the 2127 information received from the RAs generated by the MS. Whether the 2128 OMNI interface IPv6 ND messaging process is initiated from the 2129 receipt of an RS message from the IPv6 layer is an implementation 2130 matter. Some implementations may elect to defer the IPv6 ND 2131 messaging process until an RS is received from the IPv6 layer, while 2132 others may elect to initiate the process proactively. Still other 2133 deployments may elect to administratively disable the ordinary RS/RA 2134 messaging used by the IPv6 layer over the OMNI interface, since they 2135 are not required to drive the internal RS/RA processing. (Note that 2136 this same logic applies to IPv4 implementations that employ ICMP- 2137 based Router Discovery per [RFC1256].) 2139 Note: The Router Lifetime value in RA messages indicates the time 2140 before which the MN must send another RS message over this underlying 2141 interface (e.g., 600 seconds), however that timescale may be 2142 significantly longer than the lifetime the MS has committed to retain 2143 the prefix registration (e.g., REACHABLETIME seconds). ARs are 2144 therefore responsible for keeping MS state alive on a shorter 2145 timescale than the MN is required to do on its own behalf. 2147 Note: On multicast-capable underlying interfaces, MNs should send 2148 periodic unsolicited multicast NA messages and ARs should send 2149 periodic unsolicited multicast RA messages as "beacons" that can be 2150 heard by other nodes on the link. If a node fails to receive a 2151 beacon after a timeout value specific to the link, it can initiate a 2152 unicast exchange to test reachability. 2154 Note: if an AR acting as a proxy forwards a MN's RS message to 2155 another node acting as an MSE using UDP/IP encapsulation, it must use 2156 a distinct UDP source port number for each MN. This allows the MSE 2157 to distinguish different MNs behind the same AR at the link-layer, 2158 whereas the link-layer addresses would otherwise be 2159 indistinguishable. 2161 Note: when an AR acting as an MSE returns an RA to an INET Client, it 2162 includes an OMNI option with an Interface Attributes sub-option with 2163 omIndex set to 0 and with SRT, FMT, LHS and L2ADDR information for 2164 its INET interface. This provides the Client with partition prefix 2165 context regarding the local OMNI link segment. 2167 13.1. Router Discovery in IP Multihop and IPv4-Only Networks 2169 On some *NETs, a MN may be located multiple IP hops away from the 2170 nearest AR. Forwarding through IP multihop *NETs is conducted 2171 through the application of a routing protocol (e.g., a Mobile Ad-hoc 2172 Network (MANET) routing protocol over omni-directional wireless 2173 interfaces, an inter-domain routing protocol in an enterprise 2174 network, etc.). These *NETs could be either IPv6-enabled or 2175 IPv4-only, while IPv4-only *NETs could be either multicast-capable or 2176 unicast-only (note that for IPv4-only *NETs the following procedures 2177 apply for both single-hop and multihop cases). 2179 A MN located potentially multiple *NET hops away from the nearest AR 2180 prepares an RS message with source address set to either its MNP-LLA 2181 or a Temporary LLA, and with destination set to link-scoped All- 2182 Routers multicast the same as discussed above. For IPv6-enabled 2183 *NETs, the MN then encapsulates the message in an IPv6 header with 2184 source address set to the ULA corresponding to the LLA source address 2185 and with destination set to either a unicast or anycast ADM-ULA. For 2186 IPv4-only *NETs, the MN instead encapsulates the RS message in an 2187 IPv4 header with source address set to the node's own IPv4 address 2188 and with destination address set to either the unicast IPv4 address 2189 of an AR [RFC5214] or an IPv4 anycast address reserved for OMNI. The 2190 MN then sends the encapsulated RS message via the *NET interface, 2191 where it will be forwarded by zero or more intermediate *NET hops. 2193 When an intermediate *NET hop that participates in the routing 2194 protocol receives the encapsulated RS, it forwards the message 2195 according to its routing tables (note that an intermediate node could 2196 be a fixed infrastructure element or another MN). This process 2197 repeats iteratively until the RS message is received by a penultimate 2198 *NET hop within single-hop communications range of an AR, which 2199 forwards the message to the AR. 2201 When the AR receives the message, it decapsulates the RS and 2202 coordinates with the MS the same as for an ordinary link-local RS, 2203 since the inner Hop Limit will not have been decremented by the 2204 multihop forwarding process. The AR then prepares an RA message with 2205 source address set to its own ADM-LLA and destination address set to 2206 the LLA of the original MN, then encapsulates the message in an IPv4/ 2207 IPv6 header with source address set to its own IPv4/ULA address and 2208 with destination set to the encapsulation source of the RS. 2210 The AR then forwards the message to an *NET node within 2211 communications range, which forwards the message according to its 2212 routing tables to an intermediate node. The multihop forwarding 2213 process within the *NET continues repetitively until the message is 2214 delivered to the original MN, which decapsulates the message and 2215 performs autoconfiguration the same as if it had received the RA 2216 directly from the AR as an on-link neighbor. 2218 Note: An alternate approach to multihop forwarding via IPv6 2219 encapsulation would be to statelessly translate the IPv6 LLAs into 2220 ULAs and forward the messages without encapsulation. This would 2221 violate the [RFC4861] requirement that certain IPv6 ND messages must 2222 use link-local addresses and must not be accepted if received with 2223 Hop Limit less than 255. This document therefore advocates 2224 encapsulation since the overhead is nominal considering the 2225 infrequent nature and small size of IPv6 ND messages. Future 2226 documents may consider encapsulation avoidance through translation 2227 while updating [RFC4861]. 2229 Note: An alternate approach to multihop forwarding via IPv4 2230 encapsulation would be to employ IPv6/IPv4 protocol translation. 2231 However, for IPv6 ND messages the LLAs would be truncated due to 2232 translation and the OMNI Router and Prefix Discovery services would 2233 not be able to function. The use of IPv4 encapsulation is therefore 2234 indicated. 2236 Note: An IPv4 anycast address for OMNI in IPv4 networks could be part 2237 of a new IPv4 /24 prefix allocation, but this may be difficult to 2238 obtain given IPv4 address exhaustion. An alternative would be to re- 2239 purpose the prefix 192.88.99.0 which has been set aside from its 2240 former use by [RFC7526]. 2242 13.2. MS-Register and MS-Release List Processing 2244 When a MN sends an RS message with an OMNI option via an underlying 2245 interface to an AR, the MN must convey its knowledge of its 2246 currently-associated MSEs. Initially, the MN will have no associated 2247 MSEs and should therefore include an MS-Register sub-option with the 2248 single MSID value 0 which requests the AR to select and assign an 2249 MSE. The AR will then return an RA message with source address set 2250 to the ADM-LLA of the selected MSE. 2252 As the MN activates additional underlying interfaces, it can 2253 optionally include an MS-Register sub-option with MSID value 0, or 2254 with non-zero MSIDs for MSEs discovered from previous RS/RA 2255 exchanges. The MN will thus eventually begin to learn and manage its 2256 currently active set of MSEs, and can register with new MSEs or 2257 release from former MSEs with each successive RS/RA exchange. As the 2258 MN's MSE constituency grows, it alone is responsible for including or 2259 omitting MSIDs in the MS-Register/Release lists it sends in RS 2260 messages. The inclusion or omission of MSIDs determines the MN's 2261 interface to the MS and defines the manner in which MSEs will 2262 respond. The only limiting factor is that the MN should include no 2263 more than MAX_MSID values in each list per each IPv6 ND message, and 2264 should avoid duplication of entries in each list unless it wants to 2265 increase likelihood of control message delivery. 2267 When an AR receives an RS message sent by a MN with an OMNI option, 2268 the option will contain zero or more MS-Register and MS-Release sub- 2269 options containing MSIDs. After processing the OMNI option, the AR 2270 will have a list of zero or more MS-Register MSIDs and a list of zero 2271 or more of MS-Release MSIDs. The AR then processes the lists as 2272 follows: 2274 o For each list, retain the first MAX_MSID values in the list and 2275 discard any additional MSIDs (i.e., even if there are duplicates 2276 within a list). 2278 o Next, for each MSID in the MS-Register list, remove all matching 2279 MSIDs from the MS-Release list. 2281 o Next, proceed according to whether the AR's own MSID or the value 2282 0 appears in the MS-Register list as follows: 2284 * If yes, send an RA message directly back to the MN and send a 2285 proxy copy of the RS message to each additional MSID in the MS- 2286 Register list with the MS-Register/Release lists omitted. 2287 Then, send an unsolicited NA (uNA) message to each MSID in the 2288 MS-Release list with the MS-Register/Release lists omitted and 2289 with an OMNI option with S/T-omIndex set to 0. 2291 * If no, send a proxy copy of the RS message to each additional 2292 MSID in the MS-Register list with the MS-Register list omitted. 2293 For the first MSID, include the original MS-Release list; for 2294 all other MSIDs, omit the MS-Release list. 2296 Each proxy copy of the RS message will include an OMNI option and 2297 encapsulation header with the ADM-ULA of the AR as the source and the 2298 ADM-ULA of the Register MSE as the destination. When the Register 2299 MSE receives the proxy RS message, if the message includes an MS- 2300 Release list the MSE sends a uNA message to each additional MSID in 2301 the Release list. The Register MSE then sends an RA message back to 2302 the (Proxy) AR wrapped in an OMNI encapsulation header with source 2303 and destination addresses reversed, and with RA destination set to 2304 the MNP-LLA of the MN. When the AR receives this RA message, it 2305 sends a proxy copy of the RA to the MN. 2307 Each uNA message (whether send by the first-hop AR or by a Register 2308 MSE) will include an OMNI option and an encapsulation header with the 2309 ADM-ULA of the Register MSE as the source and the ADM-ULA of the 2310 Release ME as the destination. The uNA informs the Release MSE that 2311 its previous relationship with the MN has been released and that the 2312 source of the uNA message is now registered. The Release MSE must 2313 then note that the subject MN of the uNA message is now "departed", 2314 and forward any subsequent packets destined to the MN to the Register 2315 MSE. 2317 Note that it is not an error for the MS-Register/Release lists to 2318 include duplicate entries. If duplicates occur within a list, the AR 2319 will generate multiple proxy RS and/or uNA messages - one for each 2320 copy of the duplicate entries. 2322 13.3. DHCPv6-based Prefix Registration 2324 When a MN is not pre-provisioned with an MNP-LLA (or, when multiple 2325 MNPs are needed), it will require the AR to select MNPs on its behalf 2326 and set up the correct routing state within the MS. The DHCPv6 2327 service [RFC8415] supports this requirement. 2329 When an MN needs to have the AR select MNPs, it sends an RS message 2330 with a Temporary LLA as the source and with DHCPv6 Message sub-option 2331 containing a Client Identifier, one or more IA_PD options and a Rapid 2332 Commit option. The MN also sets the 'msg-type' field to "Solicit", 2333 and includes a 3-octet 'transaction-id'. 2335 When the AR receives the RS message, it extracts the DHCPv6 message 2336 from the OMNI option. The AR then acts as a "Proxy DHCPv6 Client" in 2337 a message exchange with the locally-resident DHCPv6 server, which 2338 delegates MNPs and returns a DHCPv6 Reply message with PD parameters. 2339 (If the AR wishes to defer creation of MN state until the DHCPv6 2340 Reply is received, it can instead act as a Lightweight DHCPv6 Relay 2341 Agent per [RFC6221] by encapsulating the DHCPv6 message in a Relay- 2342 forward/reply exchange with Relay Message and Interface ID options.) 2343 When the AR receives the DHCPv6 Reply, it adds routes to the routing 2344 system and creates MNP-LLAs based on the delegated MNPs. The AR then 2345 sends an RA back to the MN with the DHCPv6 Reply message included in 2346 an OMNI DHCPv6 message sub-option. If the RS message source address 2347 was a Temporary address, the AR includes one of the (newly-created) 2348 MNP-LLAs as the RA destination address. The MN then creates a 2349 default route, assigns Subnet Router Anycast addresses and uses the 2350 RA destination address as its primary MNP-LLA. The MN will then use 2351 this primary MNP-LLA as the source address of any IPv6 ND messages it 2352 sends as long as it retains ownership of the MNP. 2354 Note: After a MN performs a DHCPv6-based prefix registration exchange 2355 with a first AR, it would need to repeat the exchange with each 2356 additional MSE it registers with. In that case, the MN supplies the 2357 MNP delegations received from the first AR in the IA_PD fields of a 2358 DHCPv6 message when it engages the additional MSEs. 2360 14. Secure Redirection 2362 If the *NET link model is multiple access, the AR is responsible for 2363 assuring that address duplication cannot corrupt the neighbor caches 2364 of other nodes on the link. When the MN sends an RS message on a 2365 multiple access *NET link, the AR verifies that the MN is authorized 2366 to use the address and returns an RA with a non-zero Router Lifetime 2367 only if the MN is authorized. 2369 After verifying MN authorization and returning an RA, the AR MAY 2370 return IPv6 ND Redirect messages to direct MNs located on the same 2371 *NET link to exchange packets directly without transiting the AR. In 2372 that case, the MNs can exchange packets according to their unicast L2 2373 addresses discovered from the Redirect message instead of using the 2374 dogleg path through the AR. In some *NET links, however, such direct 2375 communications may be undesirable and continued use of the dogleg 2376 path through the AR may provide better performance. In that case, 2377 the AR can refrain from sending Redirects, and/or MNs can ignore 2378 them. 2380 15. AR and MSE Resilience 2382 *NETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 2383 [RFC5798] configurations so that service continuity is maintained 2384 even if one or more ARs fail. Using VRRP, the MN is unaware which of 2385 the (redundant) ARs is currently providing service, and any service 2386 discontinuity will be limited to the failover time supported by VRRP. 2387 Widely deployed public domain implementations of VRRP are available. 2389 MSEs SHOULD use high availability clustering services so that 2390 multiple redundant systems can provide coordinated response to 2391 failures. As with VRRP, widely deployed public domain 2392 implementations of high availability clustering services are 2393 available. Note that special-purpose and expensive dedicated 2394 hardware is not necessary, and public domain implementations can be 2395 used even between lightweight virtual machines in cloud deployments. 2397 16. Detecting and Responding to MSE Failures 2399 In environments where fast recovery from MSE failure is required, ARs 2400 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 2401 manner that parallels Bidirectional Forwarding Detection (BFD) 2402 [RFC5880] to track MSE reachability. ARs can then quickly detect and 2403 react to failures so that cached information is re-established 2404 through alternate paths. Proactive NUD control messaging is carried 2405 only over well-connected ground domain networks (i.e., and not low- 2406 end *NET links such as aeronautical radios) and can therefore be 2407 tuned for rapid response. 2409 ARs perform proactive NUD for MSEs for which there are currently 2410 active MNs on the *NET. If an MSE fails, ARs can quickly inform MNs 2411 of the outage by sending multicast RA messages on the *NET interface. 2412 The AR sends RA messages to MNs via the *NET interface with an OMNI 2413 option with a Release ID for the failed MSE, and with destination 2414 address set to All-Nodes multicast (ff02::1) [RFC4291]. 2416 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 2417 by small delays [RFC4861]. Any MNs on the *NET interface that have 2418 been using the (now defunct) MSE will receive the RA messages and 2419 associate with a new MSE. 2421 17. Transition Considerations 2423 When a MN connects to an *NET link for the first time, it sends an RS 2424 message with an OMNI option. If the first hop AR recognizes the 2425 option, it returns an RA with its ADM-LLA as the source, the MNP-LLA 2426 as the destination and with an OMNI option included. The MN then 2427 engages the AR according to the OMNI link model specified above. If 2428 the first hop AR is a legacy IPv6 router, however, it instead returns 2429 an RA message with no OMNI option and with a non-OMNI unicast source 2430 LLA as specified in [RFC4861]. In that case, the MN engages the *NET 2431 according to the legacy IPv6 link model and without the OMNI 2432 extensions specified in this document. 2434 If the *NET link model is multiple access, there must be assurance 2435 that address duplication cannot corrupt the neighbor caches of other 2436 nodes on the link. When the MN sends an RS message on a multiple 2437 access *NET link with an LLA source address and an OMNI option, ARs 2438 that recognize the option ensure that the MN is authorized to use the 2439 address and return an RA with a non-zero Router Lifetime only if the 2440 MN is authorized. ARs that do not recognize the option instead 2441 return an RA that makes no statement about the MN's authorization to 2442 use the source address. In that case, the MN should perform 2443 Duplicate Address Detection to ensure that it does not interfere with 2444 other nodes on the link. 2446 An alternative approach for multiple access *NET links to ensure 2447 isolation for MN / AR communications is through L2 address mappings 2448 as discussed in Appendix C. This arrangement imparts a (virtual) 2449 point-to-point link model over the (physical) multiple access link. 2451 18. OMNI Interfaces on the Open Internet 2453 OMNI interfaces configured over IPv6-enabled underlying interfaces on 2454 the open Internet without an OMNI-aware first-hop AR receive RA 2455 messages that do not include an OMNI option, while OMNI interfaces 2456 configured over IPv4-only underlying interfaces do not receive any 2457 (IPv6) RA messages at all. OMNI interfaces that receive RA messages 2458 without an OMNI option configure addresses, on-link prefixes, etc. on 2459 the underlying interface that received the RA according to standard 2460 IPv6 ND and address resolution conventions [RFC4861] [RFC4862]. OMNI 2461 interfaces configured over IPv4-only underlying interfaces configure 2462 IPv4 address information on the underlying interfaces using 2463 mechanisms such as DHCPv4 [RFC2131]. 2465 OMNI interfaces configured over underlying interfaces that connect to 2466 the open Internet can apply security services such as VPNs to connect 2467 to an MSE, or can establish a direct link to an MSE through some 2468 other means (see Section 4). In environments where an explicit VPN 2469 or direct link may be impractical, OMNI interfaces can instead use 2470 UDP/IP encapsulation per [RFC6081][RFC4380] and HIP-based message 2471 authentication per [RFC7401]. 2473 For "Vehicle-to-Infrastructure (V2I)" coordination, the MN codes a 2474 HIP "Initiator" message in an OMNI option of an IPv6 RS message and 2475 the MSE responds with a HIP "Responder" message coded in an OMNI 2476 option of an IPv6 RA message. HIP security services are applied per 2477 [RFC7401], using the RS/RA messages as simple "shipping containers" 2478 to convey the HIP parameters. In that case, a "two-message HIP 2479 exchange" through a single RS/RA exchange may be sufficient for 2480 mutual authentication. For "Vehicle-to-Vehicle (V2V)" coordination, 2481 two MNs can coordinate directly with one another with HIP "Initiator/ 2482 Responder" messages coded in OMNI options of IPv6 NS/NA messages. In 2483 that case, a four-message HIP exchange (i.e., two back-to-back NS/NA 2484 exchanges) may be necessary for the two MNs to attain mutual 2485 authentication. 2487 After establishing a VPN or preparing for UDP/IP encapsulation, OMNI 2488 interfaces send control plane messages to interface with the MS, 2489 including RS/RA messages used according to Section 13 and NS/NA 2490 messages used for route optimization and mobility (see: 2491 [I-D.templin-intarea-6706bis]). The control plane messages must be 2492 authenticated while data plane messages are delivered the same as for 2493 ordinary best-effort Internet traffic with basic source address-based 2494 data origin verification. Data plane communications via OMNI 2495 interfaces that connect over the open Internet without an explicit 2496 VPN should therefore employ transport- or higher-layer security to 2497 ensure integrity and/or confidentiality. 2499 OMNI interfaces in the open Internet are often located behind NATs. 2500 The OMNI interface accommodates NAT traversal using UDP/IP 2501 encapsulation and the mechanisms discussed in 2502 [I-D.templin-intarea-6706bis]. 2504 Note: Following the initial HIP Initiator/Responder exchange, OMNI 2505 interfaces configured over the open Internet maintain HIP 2506 associations through the transmission of IPv6 ND messages that 2507 include OMNI options with HIP "Update" and "Notify" messages. OMNI 2508 interfaces use the HIP "Update" message when an acknowledgement is 2509 required, and use the "Notify" message in unacknowledged isolated 2510 IPv6 ND messages (e.g., unsolicited NAs). 2512 19. Time-Varying MNPs 2514 In some use cases, it is desirable, beneficial and efficient for the 2515 MN to receive a constant MNP that travels with the MN wherever it 2516 moves. For example, this would allow air traffic controllers to 2517 easily track aircraft, etc. In other cases, however (e.g., 2518 intelligent transportation systems), the MN may be willing to 2519 sacrifice a modicum of efficiency in order to have time-varying MNPs 2520 that can be changed every so often to defeat adversarial tracking. 2522 The prefix delegation services discussed in Section 13.3 allows OMNI 2523 MNs that desire time-varying MNPs to obtain short-lived prefixes to 2524 use a Temporary LLA as the source address of an RS message with an 2525 OMNI option with DHCPv6 Option sub-options. The MN would then be 2526 obligated to renumber its internal networks whenever its MNP (and 2527 therefore also its OMNI address) changes. This should not present a 2528 challenge for MNs with automated network renumbering services, 2529 however presents limits for the durations of ongoing sessions that 2530 would prefer to use a constant address. 2532 20. Node Identification 2534 MNs and MSEs that connect over the open Internet generate a Host 2535 Identity Tag (HIT) using the procedures specified in [RFC7401] and 2536 use the value as a robust general-purpose node ID. Emerging work on 2537 Hierarchical HITs (HHITs) [I-D.ietf-drip-rid] may also produce node 2538 IDs for use in specific domains such as the Unmanned (Air) Traffic 2539 Management (UTM) service for Unmanned Air Systems (UAS). 2541 After generating a (H)HIT, the node may use it in both HIP and DHCPv6 2542 protocol message exchanges. In the latter case, the (H)HIT is coded 2543 as a DHCP Unique IDentifier (DUID) using the "DUID-EN for OMNI" 2544 format with enterprise number 45282 (see: Section 21) as shown in 2545 Figure 20: 2547 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 2548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2549 | DUID-Type (2) | EN (high bits == 0) | 2550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2551 | EN (low bits = 45282) | ID-Type | . 2552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . 2553 . Node Identification Value . 2554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2556 Figure 20: DUID-EN for OMNI Format 2558 In this format, "ID-Type" encodes the type of Node Identification, 2559 and Node Identification Value encodes the ID itself per Figure 19. 2560 This document therefore permanently associates Private Enterprise 2561 Number 45282 with the DUID-EN for OMNI format shown in Figure 20. 2563 When a MN is truly outside the context of any infrastructure, it may 2564 have no MNP information at all. In that case, it may be able to use 2565 its (H)HIT as the IPv6 source address in packets used for ongoing 2566 communications with other vehicles in V2V scenarios. The (H)HIT 2567 could also be propagated into the multihop routing protocol tables of 2568 (collective) Mobile/Vehicular Ad-hoc Networks (MANETs/VANETs) using 2569 only the vehicles themselves as communications relays. 2571 Note: In environments with strong link-layer and physical-layer 2572 security, a node may be able to include an administratively-assigned 2573 identifier (e.g., a MAC address, serial number, airframe ID, VIN, 2574 etc.) in message exchanges where a (H)HIT may not be necessary. In 2575 that case, a (H)HIT SHOULD still be generated and maintained both on 2576 the node and in a network-wide database in one-to-one correspondence 2577 with the (non-cryptographic) administrative identifier. The node can 2578 then include the (H)HIT in an OMNI "Node Identification" sub-option 2579 should the need to transmit it over the network ever arise. 2581 21. IANA Considerations 2583 The IANA has assigned a 4-octet Private Enterprise Number (PEN) code 2584 "45282" in the "enterprise-numbers" registry. This document is the 2585 normative reference for using this code in DHCP Unique IDentifiers 2586 based on Enterprise Numbers (DUID-EN) for OMNI Interfaces (see: 2587 Section 20). 2589 The IANA is instructed to allocate an official Type number TBD1 from 2590 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 2591 option. Implementations set Type to 253 as an interim value 2592 [RFC4727]. 2594 The IANA is instructed to assign a new Code value "1" in the "ICMPv6 2595 Code Fields: Type 2 - Packet Too Big" registry. The registry should 2596 read as follows: 2598 Code Name Reference 2599 --- ---- --------- 2600 0 Diagnostic Packet Too Big [RFC4443] 2601 1 Advisory Packet Too Big [RFCXXXX] 2603 Figure 21: ICMPv6 Code Fields: Type 2 - Packet Too Big Values 2605 The IANA is instructed to allocate one Ethernet unicast address TBD2 2606 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 2607 Address Block - Unicast Use". 2609 The OMNI option defines a 5-bit Sub-Type field, for which IANA is 2610 instructed to create and maintain a new registry entitled "OMNI 2611 option Sub-Type values". Initial values for the OMNI option Sub-Type 2612 values registry are given below; future assignments are to be made 2613 through Expert Review [RFC8126]. 2615 Value Sub-Type name Reference 2616 ----- ------------- ---------- 2617 0 Pad1 [RFCXXXX] 2618 1 PadN [RFCXXXX] 2619 2 Interface Attributes (Type 1) [RFCXXXX] 2620 3 Interface Attributes (Type 2) [RFCXXXX] 2621 4 Traffic Selector [RFCXXXX] 2622 5 Origin Indication [RFCXXXX] 2623 6 MS-Register [RFCXXXX] 2624 7 MS-Release [RFCXXXX] 2625 8 Geo Coordinates [RFCXXXX] 2626 9 DHCPv6 Message [RFCXXXX] 2627 10 HIP Message [RFCXXXX] 2628 11 Node Identification [RFCXXXX] 2629 12-29 Unassigned 2630 30 Experimental [RFCXXXX] 2631 31 Reserved [RFCXXXX] 2633 Figure 22: OMNI Option Sub-Type Values 2635 The OMNI Node Identification Sub-Option (see: Section 10.1.12) 2636 contains an 8-bit ID-Type field, for which IANA is instructed to 2637 create and maintain a new registry entitled "OMNI Node Identification 2638 Sub-Option ID-Type values". Initial values for the OMNI Node 2639 Identification Sub-Option ID Type values registry are given below; 2640 future assignments are to be made through Expert Review [RFC8126]. 2642 Value Sub-Type name Reference 2643 ----- ------------- ---------- 2644 0 UUID [RFCXXXX] 2645 1 HIT [RFCXXXX] 2646 2 HHIT [RFCXXXX] 2647 3 Network Access Identifier [RFCXXXX] 2648 4 FQDN [RFCXXXX] 2649 5-252 Unassigned [RFCXXXX] 2650 253-254 Experimental [RFCXXXX] 2651 255 Reserved [RFCXXXX] 2653 Figure 23: OMNI Node Identification Sub-Option ID-Type Values 2655 22. Security Considerations 2657 Security considerations for IPv4 [RFC0791], IPv6 [RFC8200] and IPv6 2658 Neighbor Discovery [RFC4861] apply. OMNI interface IPv6 ND messages 2659 SHOULD include Nonce and Timestamp options [RFC3971] when transaction 2660 confirmation and/or time synchronization is needed. 2662 MN OMNI interfaces configured over secured ANET interfaces inherit 2663 the physical and/or link-layer security properties (i.e., "protected 2664 spectrum") of the connected ANETs. MN OMNI interfaces configured 2665 over open INET interfaces can use symmetric securing services such as 2666 VPNs or can by some other means establish a direct link. When a VPN 2667 or direct link may be impractical, however, the security services 2668 specified in [RFC7401] can be employed. While the OMNI link protects 2669 control plane messaging, applications must still employ end-to-end 2670 transport- or higher-layer security services to protect the data 2671 plane. 2673 Strong network layer security for control plane messages and 2674 forwarding path integrity for data plane messages between MSEs MUST 2675 be supported. In one example, the AERO service 2676 [I-D.templin-intarea-6706bis] constructs a spanning tree between MSEs 2677 and secures the links in the spanning tree with network layer 2678 security mechanisms such as IPsec [RFC4301] or Wireguard. Control 2679 plane messages are then constrained to travel only over the secured 2680 spanning tree paths and are therefore protected from attack or 2681 eavesdropping. Since data plane messages can travel over route 2682 optimized paths that do not strictly follow the spanning tree, 2683 however, end-to-end transport- or higher-layer security services are 2684 still required. 2686 Identity-based key verification infrastructure services such as iPSK 2687 may be necessary for verifying the identities claimed by MNs. This 2688 requirement should be harmonized with the manner in which (H)HITs are 2689 attested in a given operational environment. 2691 Security considerations for specific access network interface types 2692 are covered under the corresponding IP-over-(foo) specification 2693 (e.g., [RFC2464], [RFC2492], etc.). 2695 Security considerations for IPv6 fragmentation and reassembly are 2696 discussed in Section 5.1. 2698 23. Implementation Status 2700 Draft -29 is implemented in the recently tagged AERO/OMNI 3.0.0 2701 internal release, and Draft -30 is now tagged as the AERO/OMNI 3.0.1. 2702 Newer specification versions will be tagged in upcoming releases. 2703 First public release expected before the end of 2020. 2705 24. Acknowledgements 2707 The first version of this document was prepared per the consensus 2708 decision at the 7th Conference of the International Civil Aviation 2709 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 2710 2019. Consensus to take the document forward to the IETF was reached 2711 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 2712 Attendees and contributors included: Guray Acar, Danny Bharj, 2713 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 2714 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 2715 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 2716 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 2717 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 2718 Fryderyk Wrobel and Dongsong Zeng. 2720 The following individuals are acknowledged for their useful comments: 2721 Stuart Card, Michael Matyas, Robert Moskowitz, Madhu Niraula, Greg 2722 Saccone, Stephane Tamalet, Eric Vyncke. Pavel Drasil, Zdenek Jaron 2723 and Michal Skorepa are especially recognized for their many helpful 2724 ideas and suggestions. Madhuri Madhava Badgandi, Sean Dickson, Don 2725 Dillenburg, Joe Dudkowski, Vijayasarathy Rajagopalan, Ron Sackman and 2726 Katherine Tran are acknowledged for their hard work on the 2727 implementation and technical insights that led to improvements for 2728 the spec. 2730 Discussions on the IETF 6man and atn mailing lists during the fall of 2731 2020 suggested additional points to consider. The authors gratefully 2732 acknowledge the list members who contributed valuable insights 2733 through those discussions. Eric Vyncke and Erik Kline were the 2734 intarea ADs, while Bob Hinden and Ole Troan were the 6man WG chairs 2735 at the time the document was developed; they are all gratefully 2736 acknowledged for their many helpful insights. 2738 This work is aligned with the NASA Safe Autonomous Systems Operation 2739 (SASO) program under NASA contract number NNA16BD84C. 2741 This work is aligned with the FAA as per the SE2025 contract number 2742 DTFAWA-15-D-00030. 2744 This work is aligned with the Boeing Information Technology (BIT) 2745 Mobility Vision Lab (MVL) program. 2747 25. References 2749 25.1. Normative References 2751 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 2752 DOI 10.17487/RFC0791, September 1981, 2753 . 2755 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2756 Requirement Levels", BCP 14, RFC 2119, 2757 DOI 10.17487/RFC2119, March 1997, 2758 . 2760 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 2761 "Definition of the Differentiated Services Field (DS 2762 Field) in the IPv4 and IPv6 Headers", RFC 2474, 2763 DOI 10.17487/RFC2474, December 1998, 2764 . 2766 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 2767 "SEcure Neighbor Discovery (SEND)", RFC 3971, 2768 DOI 10.17487/RFC3971, March 2005, 2769 . 2771 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 2772 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 2773 November 2005, . 2775 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 2776 Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005, 2777 . 2779 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 2780 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2781 2006, . 2783 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 2784 Control Message Protocol (ICMPv6) for the Internet 2785 Protocol Version 6 (IPv6) Specification", STD 89, 2786 RFC 4443, DOI 10.17487/RFC4443, March 2006, 2787 . 2789 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 2790 ICMPv6, UDP, and TCP Headers", RFC 4727, 2791 DOI 10.17487/RFC4727, November 2006, 2792 . 2794 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 2795 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 2796 DOI 10.17487/RFC4861, September 2007, 2797 . 2799 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 2800 Address Autoconfiguration", RFC 4862, 2801 DOI 10.17487/RFC4862, September 2007, 2802 . 2804 [RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont, 2805 "Traffic Selectors for Flow Bindings", RFC 6088, 2806 DOI 10.17487/RFC6088, January 2011, 2807 . 2809 [RFC7401] Moskowitz, R., Ed., Heer, T., Jokela, P., and T. 2810 Henderson, "Host Identity Protocol Version 2 (HIPv2)", 2811 RFC 7401, DOI 10.17487/RFC7401, April 2015, 2812 . 2814 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 2815 Hosts in a Multi-Prefix Network", RFC 8028, 2816 DOI 10.17487/RFC8028, November 2016, 2817 . 2819 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2820 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2821 May 2017, . 2823 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 2824 (IPv6) Specification", STD 86, RFC 8200, 2825 DOI 10.17487/RFC8200, July 2017, 2826 . 2828 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 2829 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 2830 DOI 10.17487/RFC8201, July 2017, 2831 . 2833 [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., 2834 Richardson, M., Jiang, S., Lemon, T., and T. Winters, 2835 "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", 2836 RFC 8415, DOI 10.17487/RFC8415, November 2018, 2837 . 2839 25.2. Informative References 2841 [ATN] Maiolla, V., "The OMNI Interface - An IPv6 Air/Ground 2842 Interface for Civil Aviation, IETF Liaison Statement 2843 #1676, https://datatracker.ietf.org/liaison/1676/", March 2844 2020. 2846 [ATN-IPS] WG-I, ICAO., "ICAO Document 9896 (Manual on the 2847 Aeronautical Telecommunication Network (ATN) using 2848 Internet Protocol Suite (IPS) Standards and Protocol), 2849 Draft Edition 3 (work-in-progress)", December 2020. 2851 [CRC] Jain, R., "Error Characteristics of Fiber Distributed Data 2852 Interface (FDDI), IEEE Transactions on Communications", 2853 August 1990. 2855 [I-D.ietf-6man-rfc4941bis] 2856 Gont, F., Krishnan, S., Narten, T., and R. Draves, 2857 "Temporary Address Extensions for Stateless Address 2858 Autoconfiguration in IPv6", draft-ietf-6man-rfc4941bis-12 2859 (work in progress), November 2020. 2861 [I-D.ietf-drip-rid] 2862 Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov, 2863 "UAS Remote ID", draft-ietf-drip-rid-06 (work in 2864 progress), December 2020. 2866 [I-D.ietf-intarea-tunnels] 2867 Touch, J. and M. Townsley, "IP Tunnels in the Internet 2868 Architecture", draft-ietf-intarea-tunnels-10 (work in 2869 progress), September 2019. 2871 [I-D.ietf-ipwave-vehicular-networking] 2872 Jeong, J., "IPv6 Wireless Access in Vehicular Environments 2873 (IPWAVE): Problem Statement and Use Cases", draft-ietf- 2874 ipwave-vehicular-networking-19 (work in progress), July 2875 2020. 2877 [I-D.templin-6man-dhcpv6-ndopt] 2878 Templin, F., "A Unified Stateful/Stateless Configuration 2879 Service for IPv6", draft-templin-6man-dhcpv6-ndopt-11 2880 (work in progress), January 2021. 2882 [I-D.templin-6man-lla-type] 2883 Templin, F., "The IPv6 Link-Local Address Type Field", 2884 draft-templin-6man-lla-type-02 (work in progress), 2885 November 2020. 2887 [I-D.templin-intarea-6706bis] 2888 Templin, F., "Asymmetric Extended Route Optimization 2889 (AERO)", draft-templin-intarea-6706bis-87 (work in 2890 progress), January 2021. 2892 [IPV4-GUA] 2893 Postel, J., "IPv4 Address Space Registry, 2894 https://www.iana.org/assignments/ipv4-address-space/ipv4- 2895 address-space.xhtml", December 2020. 2897 [IPV6-GUA] 2898 Postel, J., "IPv6 Global Unicast Address Assignments, 2899 https://www.iana.org/assignments/ipv6-unicast-address- 2900 assignments/ipv6-unicast-address-assignments.xhtml", 2901 December 2020. 2903 [RFC1035] Mockapetris, P., "Domain names - implementation and 2904 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 2905 November 1987, . 2907 [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - 2908 Communication Layers", STD 3, RFC 1122, 2909 DOI 10.17487/RFC1122, October 1989, 2910 . 2912 [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, 2913 DOI 10.17487/RFC1191, November 1990, 2914 . 2916 [RFC1256] Deering, S., Ed., "ICMP Router Discovery Messages", 2917 RFC 1256, DOI 10.17487/RFC1256, September 1991, 2918 . 2920 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 2921 RFC 2131, DOI 10.17487/RFC2131, March 1997, 2922 . 2924 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 2925 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 2926 . 2928 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 2929 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 2930 . 2932 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 2933 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 2934 December 1998, . 2936 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 2937 Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999, 2938 . 2940 [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 2941 Domains without Explicit Tunnels", RFC 2529, 2942 DOI 10.17487/RFC2529, March 1999, 2943 . 2945 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 2946 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 2947 . 2949 [RFC3330] IANA, "Special-Use IPv4 Addresses", RFC 3330, 2950 DOI 10.17487/RFC3330, September 2002, 2951 . 2953 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 2954 Considered Useful", BCP 82, RFC 3692, 2955 DOI 10.17487/RFC3692, January 2004, 2956 . 2958 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 2959 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 2960 DOI 10.17487/RFC3810, June 2004, 2961 . 2963 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 2964 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 2965 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 2966 RFC 3819, DOI 10.17487/RFC3819, July 2004, 2967 . 2969 [RFC3879] Huitema, C. and B. Carpenter, "Deprecating Site Local 2970 Addresses", RFC 3879, DOI 10.17487/RFC3879, September 2971 2004, . 2973 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 2974 Unique IDentifier (UUID) URN Namespace", RFC 4122, 2975 DOI 10.17487/RFC4122, July 2005, 2976 . 2978 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 2979 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 2980 DOI 10.17487/RFC4271, January 2006, 2981 . 2983 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 2984 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 2985 December 2005, . 2987 [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through 2988 Network Address Translations (NATs)", RFC 4380, 2989 DOI 10.17487/RFC4380, February 2006, 2990 . 2992 [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery 2993 Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April 2994 2006, . 2996 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 2997 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 2998 . 3000 [RFC4541] Christensen, M., Kimball, K., and F. Solensky, 3001 "Considerations for Internet Group Management Protocol 3002 (IGMP) and Multicast Listener Discovery (MLD) Snooping 3003 Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006, 3004 . 3006 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 3007 "Internet Group Management Protocol (IGMP) / Multicast 3008 Listener Discovery (MLD)-Based Multicast Forwarding 3009 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 3010 August 2006, . 3012 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 3013 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 3014 . 3016 [RFC4963] Heffner, J., Mathis, M., and B. Chandler, "IPv4 Reassembly 3017 Errors at High Data Rates", RFC 4963, 3018 DOI 10.17487/RFC4963, July 2007, 3019 . 3021 [RFC5175] Haberman, B., Ed. and R. Hinden, "IPv6 Router 3022 Advertisement Flags Option", RFC 5175, 3023 DOI 10.17487/RFC5175, March 2008, 3024 . 3026 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 3027 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 3028 RFC 5213, DOI 10.17487/RFC5213, August 2008, 3029 . 3031 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 3032 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 3033 DOI 10.17487/RFC5214, March 2008, 3034 . 3036 [RFC5558] Templin, F., Ed., "Virtual Enterprise Traversal (VET)", 3037 RFC 5558, DOI 10.17487/RFC5558, February 2010, 3038 . 3040 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 3041 Version 3 for IPv4 and IPv6", RFC 5798, 3042 DOI 10.17487/RFC5798, March 2010, 3043 . 3045 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 3046 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 3047 . 3049 [RFC6081] Thaler, D., "Teredo Extensions", RFC 6081, 3050 DOI 10.17487/RFC6081, January 2011, 3051 . 3053 [RFC6221] Miles, D., Ed., Ooghe, S., Dec, W., Krishnan, S., and A. 3054 Kavanagh, "Lightweight DHCPv6 Relay Agent", RFC 6221, 3055 DOI 10.17487/RFC6221, May 2011, 3056 . 3058 [RFC6355] Narten, T. and J. Johnson, "Definition of the UUID-Based 3059 DHCPv6 Unique Identifier (DUID-UUID)", RFC 6355, 3060 DOI 10.17487/RFC6355, August 2011, 3061 . 3063 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 3064 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 3065 2012, . 3067 [RFC6980] Gont, F., "Security Implications of IPv6 Fragmentation 3068 with IPv6 Neighbor Discovery", RFC 6980, 3069 DOI 10.17487/RFC6980, August 2013, 3070 . 3072 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 3073 Requirements for IPv6 Customer Edge Routers", RFC 7084, 3074 DOI 10.17487/RFC7084, November 2013, 3075 . 3077 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 3078 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 3079 Boundary in IPv6 Addressing", RFC 7421, 3080 DOI 10.17487/RFC7421, January 2015, 3081 . 3083 [RFC7526] Troan, O. and B. Carpenter, Ed., "Deprecating the Anycast 3084 Prefix for 6to4 Relay Routers", BCP 196, RFC 7526, 3085 DOI 10.17487/RFC7526, May 2015, 3086 . 3088 [RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542, 3089 DOI 10.17487/RFC7542, May 2015, 3090 . 3092 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 3093 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 3094 February 2016, . 3096 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 3097 Support for IP Hosts with Multi-Access Support", RFC 7847, 3098 DOI 10.17487/RFC7847, May 2016, 3099 . 3101 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 3102 Writing an IANA Considerations Section in RFCs", BCP 26, 3103 RFC 8126, DOI 10.17487/RFC8126, June 2017, 3104 . 3106 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 3107 Decraene, B., Litkowski, S., and R. Shakir, "Segment 3108 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 3109 July 2018, . 3111 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 3112 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 3113 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 3114 . 3116 [RFC8900] Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O., 3117 and F. Gont, "IP Fragmentation Considered Fragile", 3118 BCP 230, RFC 8900, DOI 10.17487/RFC8900, September 2020, 3119 . 3121 Appendix A. Interface Attribute Preferences Bitmap Encoding 3123 Adaptation of the OMNI option Interface Attributes Preferences Bitmap 3124 encoding to specific Internetworks such as the Aeronautical 3125 Telecommunications Network with Internet Protocol Services (ATN/IPS) 3126 may include link selection preferences based on other traffic 3127 classifiers (e.g., transport port numbers, etc.) in addition to the 3128 existing DSCP-based preferences. Nodes on specific Internetworks 3129 maintain a map of traffic classifiers to additional P[*] preference 3130 fields beyond the first 64. For example, TCP port 22 maps to P[67], 3131 TCP port 443 maps to P[70], UDP port 8060 maps to P[76], etc. 3133 Implementations use Simplex or Indexed encoding formats for P[*] 3134 encoding in order to encode a given set of traffic classifiers in the 3135 most efficient way. Some use cases may be more efficiently coded 3136 using Simplex form, while others may be more efficient using Indexed. 3137 Once a format is selected for preparation of a single Interface 3138 Attribute the same format must be used for the entire Interface 3139 Attribute sub-option. Different sub-options may use different 3140 formats. 3142 The following figures show coding examples for various Simplex and 3143 Indexed formats: 3145 0 1 2 3 3146 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 3147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3148 | Sub-Type=3| Sub-length=N | omIndex | omType | 3149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3150 | Provider ID | Link |R| API | Bitmap(0)=0xff|P00|P01|P02|P03| 3151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3152 |P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19| 3153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3154 |P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| Bitmap(1)=0xff| 3155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3156 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 3157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3158 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 3159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3160 | Bitmap(2)=0xff|P64|P65|P67|P68| ... 3161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 3163 Figure 24: Example 1: Dense Simplex Encoding 3165 0 1 2 3 3166 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 3167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3168 | Sub-Type=3| Sub-length=N | omIndex | omType | 3169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3170 | Provider ID | Link |R| API | Bitmap(0)=0x00| Bitmap(1)=0x0f| 3171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3172 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 3173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3174 | Bitmap(2)=0x00| Bitmap(3)=0x00| Bitmap(4)=0x00| Bitmap(5)=0x00| 3175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3176 | Bitmap(6)=0xf0|192|193|194|195|196|197|198|199|200|201|202|203| 3177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3178 |204|205|206|207| Bitmap(7)=0x00| Bitmap(8)=0x0f|272|273|274|275| 3179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3180 |276|277|278|279|280|281|282|283|284|285|286|287| Bitmap(9)=0x00| 3181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3182 |Bitmap(10)=0x00| ... 3183 +-+-+-+-+-+-+-+-+-+-+- 3185 Figure 25: Example 2: Sparse Simplex Encoding 3187 0 1 2 3 3188 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 3189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3190 | Sub-Type=3| Sub-length=N | omIndex | omType | 3191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3192 | Provider ID | Link |R| API | Index = 0x00 | Bitmap = 0x80 | 3193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3194 |P00|P01|P02|P03| Index = 0x01 | Bitmap = 0x01 |P60|P61|P62|P63| 3195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3196 | Index = 0x10 | Bitmap = 0x80 |512|513|514|515| Index = 0x18 | 3197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3198 | Bitmap = 0x01 |796|797|798|799| ... 3199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 3201 Figure 26: Example 3: Indexed Encoding 3203 Appendix B. VDL Mode 2 Considerations 3205 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 3206 (VDLM2) that specifies an essential radio frequency data link service 3207 for aircraft and ground stations in worldwide civil aviation air 3208 traffic management. The VDLM2 link type is "multicast capable" 3209 [RFC4861], but with considerable differences from common multicast 3210 links such as Ethernet and IEEE 802.11. 3212 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 3213 magnitude less than most modern wireless networking gear. Second, 3214 due to the low available link bandwidth only VDLM2 ground stations 3215 (i.e., and not aircraft) are permitted to send broadcasts, and even 3216 so only as compact layer 2 "beacons". Third, aircraft employ the 3217 services of ground stations by performing unicast RS/RA exchanges 3218 upon receipt of beacons instead of listening for multicast RA 3219 messages and/or sending multicast RS messages. 3221 This beacon-oriented unicast RS/RA approach is necessary to conserve 3222 the already-scarce available link bandwidth. Moreover, since the 3223 numbers of beaconing ground stations operating within a given spatial 3224 range must be kept as sparse as possible, it would not be feasible to 3225 have different classes of ground stations within the same region 3226 observing different protocols. It is therefore highly desirable that 3227 all ground stations observe a common language of RS/RA as specified 3228 in this document. 3230 Note that links of this nature may benefit from compression 3231 techniques that reduce the bandwidth necessary for conveying the same 3232 amount of data. The IETF lpwan working group is considering possible 3233 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 3235 Appendix C. MN / AR Isolation Through L2 Address Mapping 3237 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 3238 unicast link-scoped IPv6 destination address. However, IPv6 ND 3239 messaging should be coordinated between the MN and AR only without 3240 invoking other nodes on the *NET. This implies that MN / AR control 3241 messaging should be isolated and not overheard by other nodes on the 3242 link. 3244 To support MN / AR isolation on some *NET links, ARs can maintain an 3245 OMNI-specific unicast L2 address ("MSADDR"). For Ethernet-compatible 3246 *NETs, this specification reserves one Ethernet unicast address TBD2 3247 (see: Section 21). For non-Ethernet statically-addressed *NETs, 3248 MSADDR is reserved per the assigned numbers authority for the *NET 3249 addressing space. For still other *NETs, MSADDR may be dynamically 3250 discovered through other means, e.g., L2 beacons. 3252 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 3253 both multicast and unicast) to MSADDR instead of to an ordinary 3254 unicast or multicast L2 address. In this way, all of the MN's IPv6 3255 ND messages will be received by ARs that are configured to accept 3256 packets destined to MSADDR. Note that multiple ARs on the link could 3257 be configured to accept packets destined to MSADDR, e.g., as a basis 3258 for supporting redundancy. 3260 Therefore, ARs must accept and process packets destined to MSADDR, 3261 while all other devices must not process packets destined to MSADDR. 3262 This model has well-established operational experience in Proxy 3263 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 3265 Appendix D. Change Log 3267 << RFC Editor - remove prior to publication >> 3269 Differences from draft-templin-6man-omni-interface-35 to draft- 3270 templin-6man-omni-interface-36: 3272 o Major clarifications on aspects such as "hard/soft" PTB error 3273 messages 3275 o Made generic so that either IP protocol version (IPv4 or IPv6) can 3276 be used in the data plane. 3278 Differences from draft-templin-6man-omni-interface-31 to draft- 3279 templin-6man-omni-interface-32: 3281 o MTU 3283 o Support for multi-hop ANETS such as ISATAP. 3285 Differences from draft-templin-6man-omni-interface-29 to draft- 3286 templin-6man-omni-interface-30: 3288 o Moved link-layer addressing information into the OMNI option on a 3289 per-ifIndex basis 3291 o Renamed "ifIndex-tuple" to "Interface Attributes" 3293 Differences from draft-templin-6man-omni-interface-27 to draft- 3294 templin-6man-omni-interface-28: 3296 o Updates based on implementation experience. 3298 Differences from draft-templin-6man-omni-interface-25 to draft- 3299 templin-6man-omni-interface-26: 3301 o Further clarification on "aggregate" RA messages. 3303 o Expanded Security Considerations to discuss expectations for 3304 security in the Mobility Service. 3306 Differences from draft-templin-6man-omni-interface-20 to draft- 3307 templin-6man-omni-interface-21: 3309 o Safety-Based Multilink (SBM) and Performance-Based Multilink 3310 (PBM). 3312 Differences from draft-templin-6man-omni-interface-18 to draft- 3313 templin-6man-omni-interface-19: 3315 o SEND/CGA. 3317 Differences from draft-templin-6man-omni-interface-17 to draft- 3318 templin-6man-omni-interface-18: 3320 o Teredo 3322 Differences from draft-templin-6man-omni-interface-14 to draft- 3323 templin-6man-omni-interface-15: 3325 o Prefix length discussions removed. 3327 Differences from draft-templin-6man-omni-interface-12 to draft- 3328 templin-6man-omni-interface-13: 3330 o Teredo 3332 Differences from draft-templin-6man-omni-interface-11 to draft- 3333 templin-6man-omni-interface-12: 3335 o Major simplifications and clarifications on MTU and fragmentation. 3337 o Document now updates RFC4443 and RFC8201. 3339 Differences from draft-templin-6man-omni-interface-10 to draft- 3340 templin-6man-omni-interface-11: 3342 o Removed /64 assumption, resulting in new OMNI address format. 3344 Differences from draft-templin-6man-omni-interface-07 to draft- 3345 templin-6man-omni-interface-08: 3347 o OMNI MNs in the open Internet 3349 Differences from draft-templin-6man-omni-interface-06 to draft- 3350 templin-6man-omni-interface-07: 3352 o Brought back L2 MSADDR mapping text for MN / AR isolation based on 3353 L2 addressing. 3355 o Expanded "Transition Considerations". 3357 Differences from draft-templin-6man-omni-interface-05 to draft- 3358 templin-6man-omni-interface-06: 3360 o Brought back OMNI option "R" flag, and discussed its use. 3362 Differences from draft-templin-6man-omni-interface-04 to draft- 3363 templin-6man-omni-interface-05: 3365 o Transition considerations, and overhaul of RS/RA addressing with 3366 the inclusion of MSE addresses within the OMNI option instead of 3367 as RS/RA addresses (developed under FAA SE2025 contract number 3368 DTFAWA-15-D-00030). 3370 Differences from draft-templin-6man-omni-interface-02 to draft- 3371 templin-6man-omni-interface-03: 3373 o Added "advisory PTB messages" under FAA SE2025 contract number 3374 DTFAWA-15-D-00030. 3376 Differences from draft-templin-6man-omni-interface-01 to draft- 3377 templin-6man-omni-interface-02: 3379 o Removed "Primary" flag and supporting text. 3381 o Clarified that "Router Lifetime" applies to each ANET interface 3382 independently, and that the union of all ANET interface Router 3383 Lifetimes determines MSE lifetime. 3385 Differences from draft-templin-6man-omni-interface-00 to draft- 3386 templin-6man-omni-interface-01: 3388 o "All-MSEs" OMNI LLA defined. Also reserved fe80::ff00:0000/104 3389 for future use (most likely as "pseudo-multicast"). 3391 o Non-normative discussion of alternate OMNI LLA construction form 3392 made possible if the 64-bit assumption were relaxed. 3394 First draft version (draft-templin-atn-aero-interface-00): 3396 o Draft based on consensus decision of ICAO Working Group I Mobility 3397 Subgroup March 22, 2019. 3399 Authors' Addresses 3400 Fred L. Templin (editor) 3401 The Boeing Company 3402 P.O. Box 3707 3403 Seattle, WA 98124 3404 USA 3406 Email: fltemplin@acm.org 3408 Tony Whyman 3409 MWA Ltd c/o Inmarsat Global Ltd 3410 99 City Road 3411 London EC1Y 1AX 3412 England 3414 Email: tony.whyman@mccallumwhyman.com