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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 22, 2021 7 Expires: August 26, 2021 9 Transmission of IP Packets over Overlay Multilink Network (OMNI) 10 Interfaces 11 draft-templin-6man-omni-interface-84 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 26, 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. OMNI Interface Maximum Transmission Unit (MTU) . . . . . . . 14 63 5.1. OMNI Interface MTU/MRU . . . . . . . . . . . . . . . . . 14 64 5.2. The OMNI Adaptation Layer (OAL) . . . . . . . . . . . . . 15 65 5.3. OAL ANET/INET Addressing Considerations . . . . . . . . . 18 66 5.4. OMNI Interface MTU Feedback Messaging . . . . . . . . . . 18 67 5.5. OAL Fragmentation Security Implications . . . . . . . . . 20 68 5.6. OAL Super-Packets . . . . . . . . . . . . . . . . . . . . 21 69 6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 23 70 7. Link-Local Addresses (LLAs) . . . . . . . . . . . . . . . . . 23 71 8. Unique-Local Addresses (ULAs) . . . . . . . . . . . . . . . . 24 72 9. Global Unicast Addresses (GUAs) . . . . . . . . . . . . . . . 26 73 10. Node Identification . . . . . . . . . . . . . . . . . . . . . 26 74 11. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 27 75 11.1. Sub-Options . . . . . . . . . . . . . . . . . . . . . . 29 76 11.1.1. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . 31 77 11.1.2. PadN . . . . . . . . . . . . . . . . . . . . . . . . 31 78 11.1.3. Interface Attributes (Type 1) . . . . . . . . . . . 32 79 11.1.4. Interface Attributes (Type 2) . . . . . . . . . . . 33 80 11.1.5. Traffic Selector . . . . . . . . . . . . . . . . . . 37 81 11.1.6. MS-Register . . . . . . . . . . . . . . . . . . . . 38 82 11.1.7. MS-Release . . . . . . . . . . . . . . . . . . . . . 39 83 11.1.8. Geo Coordinates . . . . . . . . . . . . . . . . . . 39 84 11.1.9. Dynamic Host Configuration Protocol for IPv6 85 (DHCPv6) Message . . . . . . . . . . . . . . . . . . 40 86 11.1.10. Host Identity Protocol (HIP) Message . . . . . . . . 41 87 11.1.11. Node Identification . . . . . . . . . . . . . . . . 42 88 11.1.12. Sub-Type Extension . . . . . . . . . . . . . . . . . 43 89 12. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 46 90 13. Multilink Conceptual Sending Algorithm . . . . . . . . . . . 47 91 13.1. Multiple OMNI Interfaces . . . . . . . . . . . . . . . . 47 92 13.2. MN<->AR Traffic Loop Prevention . . . . . . . . . . . . 48 93 14. Router Discovery and Prefix Registration . . . . . . . . . . 48 94 14.1. Router Discovery in IP Multihop and IPv4-Only Networks . 53 95 14.2. MS-Register and MS-Release List Processing . . . . . . . 54 96 14.3. DHCPv6-based Prefix Registration . . . . . . . . . . . . 56 98 15. Secure Redirection . . . . . . . . . . . . . . . . . . . . . 58 99 16. AR and MSE Resilience . . . . . . . . . . . . . . . . . . . . 58 100 17. Detecting and Responding to MSE Failures . . . . . . . . . . 58 101 18. Transition Considerations . . . . . . . . . . . . . . . . . . 59 102 19. OMNI Interfaces on Open Internetworks . . . . . . . . . . . . 59 103 20. Time-Varying MNPs . . . . . . . . . . . . . . . . . . . . . . 61 104 21. (H)HITs and Temporary ULAs . . . . . . . . . . . . . . . . . 62 105 22. Address Selection . . . . . . . . . . . . . . . . . . . . . . 63 106 23. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 63 107 23.1. "IPv6 Neighbor Discovery Option Formats" Registry . . . 63 108 23.2. "Ethernet Numbers" Registry . . . . . . . . . . . . . . 63 109 23.3. "ICMPv6 Code Fields: Type 2 - Packet Too Big" Registry . 64 110 23.4. "OMNI Option Sub-Type Values" (New Registry) . . . . . . 64 111 23.5. "OMNI Node Identification ID-Type Values" (New Registry) 64 112 23.6. "OMNI Option Sub-Type Extension Values" (New Registry) . 65 113 23.7. "OMNI RFC4380 UDP/IP Header Option" (New Registry) . . . 65 114 23.8. "OMNI RFC6081 UDP/IP Trailer Option" (New Registry) . . 66 115 23.9. Additional Considerations . . . . . . . . . . . . . . . 66 116 24. Security Considerations . . . . . . . . . . . . . . . . . . . 67 117 25. Implementation Status . . . . . . . . . . . . . . . . . . . . 68 118 26. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 68 119 27. References . . . . . . . . . . . . . . . . . . . . . . . . . 69 120 27.1. Normative References . . . . . . . . . . . . . . . . . . 69 121 27.2. Informative References . . . . . . . . . . . . . . . . . 71 122 Appendix A. Interface Attribute Preferences Bitmap Encoding . . 77 123 Appendix B. VDL Mode 2 Considerations . . . . . . . . . . . . . 79 124 Appendix C. MN / AR Isolation Through L2 Address Mapping . . . . 80 125 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 80 126 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 83 128 1. Introduction 130 Mobile Nodes (MNs) (e.g., aircraft of various configurations, 131 terrestrial vehicles, seagoing vessels, enterprise wireless devices, 132 pedestrians with cellphones, etc.) often have multiple interface 133 connections to wireless and/or wired-link data links used for 134 communicating with networked correspondents. These data links may 135 have diverse performance, cost and availability properties that can 136 change dynamically according to mobility patterns, flight phases, 137 proximity to infrastructure, etc. MNs coordinate their data links in 138 a discipline known as "multilink", in which a single virtual 139 interface is configured over the node's underlying interface 140 connections to the data links. 142 The MN configures a virtual interface (termed the "Overlay Multilink 143 Network Interface (OMNI)") as a thin layer over the underlying 144 interfaces. The OMNI interface is therefore the only interface 145 abstraction exposed to the IP layer and behaves according to the Non- 146 Broadcast, Multiple Access (NBMA) interface principle, while 147 underlying interfaces appear as link layer communication channels in 148 the architecture. The OMNI interface internally employs the "OMNI 149 Adaptation Layer (OAL)" to ensure that packets are delivered without 150 loss due to size restrictions. The OMNI interface connects to a 151 virtual overlay service known as the "OMNI link". The OMNI link 152 spans one or more Internetworks that may include private-use 153 infrastructures and/or the global public Internet itself. 155 Each MN receives a Mobile Network Prefix (MNP) for numbering 156 downstream-attached End User Networks (EUNs) independently of the 157 access network data links selected for data transport. The MN 158 performs router discovery over the OMNI interface (i.e., similar to 159 IPv6 customer edge routers [RFC7084]) and acts as a mobile router on 160 behalf of its EUNs. The router discovery process is iterated over 161 each of the OMNI interface's underlying interfaces in order to 162 register per-link parameters (see Section 14). 164 The OMNI interface provides a multilink nexus for exchanging inbound 165 and outbound traffic via the correct underlying interface(s). The IP 166 layer sees the OMNI interface as a point of connection to the OMNI 167 link. Each OMNI link has one or more associated Mobility Service 168 Prefixes (MSPs), which are typically IP Global Unicast Address (GUA) 169 prefixes from which OMNI link MNPs are derived. If there are 170 multiple OMNI links, the IPv6 layer will see multiple OMNI 171 interfaces. 173 MNs may connect to multiple distinct OMNI links within the same OMNI 174 domain by configuring multiple OMNI interfaces, e.g., omni0, omni1, 175 omni2, etc. Each OMNI interface is configured over a set of 176 underlying interfaces and provides a nexus for Safety-Based Multilink 177 (SBM) operation. Each OMNI interface within the same OMNI domain 178 configures a common ULA prefix [ULA]::/48, and configures a unique 179 16-bit Subnet ID '*' to construct the sub-prefix [ULA*]::/64 (see: 180 Section 8). The IP layer applies SBM routing to select an OMNI 181 interface, which then applies Performance-Based Multilink (PBM) to 182 select the correct underlying interface. Applications can apply 183 Segment Routing [RFC8402] to select independent SBM topologies for 184 fault tolerance. 186 The OMNI interface interacts with a network-based Mobility Service 187 (MS) through IPv6 Neighbor Discovery (ND) control message exchanges 188 [RFC4861]. The MS provides Mobility Service Endpoints (MSEs) that 189 track MN movements and represent their MNPs in a global routing or 190 mapping system. 192 Many OMNI use cases have been proposed. In particular, the 193 International Civil Aviation Organization (ICAO) Working Group-I 194 Mobility Subgroup is developing a future Aeronautical 195 Telecommunications Network with Internet Protocol Services (ATN/IPS) 196 and has issued a liaison statement requesting IETF adoption [ATN] in 197 support of ICAO Document 9896 [ATN-IPS]. The IETF IP Wireless Access 198 in Vehicular Environments (ipwave) working group has further included 199 problem statement and use case analysis for OMNI in a document now in 200 AD evaluation for RFC publication 201 [I-D.ietf-ipwave-vehicular-networking]. Still other communities of 202 interest include AEEC, RTCA Special Committee 228 (SC-228) and NASA 203 programs that examine commercial aviation, Urban Air Mobility (UAM) 204 and Unmanned Air Systems (UAS). Pedestrians with handheld devices 205 represent another large class of potential OMNI users. 207 This document specifies the transmission of IP packets and MN/MS 208 control messages over OMNI interfaces. The OMNI interface supports 209 either IP protocol version (i.e., IPv4 [RFC0791] or IPv6 [RFC8200]) 210 as the network layer in the data plane, while using IPv6 ND messaging 211 as the control plane independently of the data plane IP protocol(s). 212 The OAL operates as a mid-layer between L3 and L2 based on IP-in-IPv6 213 encapsulation per [RFC2473] as discussed in the following sections. 214 OMNI interfaces enable multilink, mobility, multihop and multicast 215 services, with provisions for both Vehicle-to-Infrastructure (V2I) 216 communications and Vehicle-to-Vehicle (V2V) communications outside 217 the context of infrastructure. 219 2. Terminology 221 The terminology in the normative references applies; especially, the 222 terms "link" and "interface" are the same as defined in the IPv6 223 [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications. 224 Additionally, this document assumes the following IPv6 ND message 225 types: Router Solicitation (RS), Router Advertisement (RA), Neighbor 226 Solicitation (NS), Neighbor Advertisement (NA) and Redirect. 228 The Protocol Constants defined in Section 10 of [RFC4861] are used in 229 their same format and meaning in this document. The terms "All- 230 Routers multicast", "All-Nodes multicast" and "Subnet-Router anycast" 231 are the same as defined in [RFC4291] (with Link-Local scope assumed). 233 The term "IP" is used to refer collectively to either Internet 234 Protocol version (i.e., IPv4 [RFC0791] or IPv6 [RFC8200]) when a 235 specification at the layer in question applies equally to either 236 version. 238 The following terms are defined within the scope of this document: 240 Mobile Node (MN) 241 an end system with a mobile router having multiple distinct 242 upstream data link connections that are grouped together in one or 243 more logical units. The MN's data link connection parameters can 244 change over time due to, e.g., node mobility, link quality, etc. 245 The MN further connects a downstream-attached End User Network 246 (EUN). The term MN used here is distinct from uses in other 247 documents, and does not imply a particular mobility protocol. 249 End User Network (EUN) 250 a simple or complex downstream-attached mobile network that 251 travels with the MN as a single logical unit. The IP addresses 252 assigned to EUN devices remain stable even if the MN's upstream 253 data link connections change. 255 Mobility Service (MS) 256 a mobile routing service that tracks MN movements and ensures that 257 MNs remain continuously reachable even across mobility events. 258 Specific MS details are out of scope for this document. 260 Mobility Service Endpoint (MSE) 261 an entity in the MS (either singular or aggregate) that 262 coordinates the mobility events of one or more MN. 264 Mobility Service Prefix (MSP) 265 an aggregated IP Global Unicast Address (GUA) prefix (e.g., 266 2001:db8::/32, 192.0.2.0/24, etc.) assigned to the OMNI link and 267 from which more-specific Mobile Network Prefixes (MNPs) are 268 delegated. OMNI link administrators typically obtain MSPs from an 269 Internet address registry, however private-use prefixes can 270 alternatively be used subject to certain limitations (see: 271 Section 9). OMNI links that connect to the global Internet 272 advertise their MSPs to their interdomain routing peers. 274 Mobile Network Prefix (MNP) 275 a longer IP prefix delegated from an MSP (e.g., 276 2001:db8:1000:2000::/56, 192.0.2.8/30, etc.) and assigned to a MN. 277 MNs sub-delegate the MNP to devices located in EUNs. 279 Access Network (ANET) 280 a data link service network (e.g., an aviation radio access 281 network, satellite service provider network, cellular operator 282 network, WiFi network, etc.) that connects MNs. Physical and/or 283 data link level security is assumed, and sometimes referred to as 284 "protected spectrum". Private enterprise networks and ground 285 domain aviation service networks may provide multiple secured IP 286 hops between the MN's point of connection and the nearest Access 287 Router. 289 Access Router (AR) 290 a router in the ANET for connecting MNs to correspondents in 291 outside Internetworks. The AR may be located on the same physical 292 link as the MN, or may be located multiple IP hops away. In the 293 latter case, the MN uses encapsulation to communicate with the AR 294 as though it were on the same physical link. 296 ANET interface 297 a MN's attachment to a link in an ANET. 299 Internetwork (INET) 300 a connected network region with a coherent IP addressing plan that 301 provides transit forwarding services between ANETs and nodes that 302 connect directly to the open INET via unprotected media. No 303 physical and/or data link level security is assumed, therefore 304 security must be applied by upper layers. The global public 305 Internet itself is an example. 307 INET interface 308 a node's attachment to a link in an INET. 310 *NET 311 a "wildcard" term used when a given specification applies equally 312 to both ANET and INET cases. 314 OMNI link 315 a Non-Broadcast, Multiple Access (NBMA) virtual overlay configured 316 over one or more INETs and their connected ANETs. An OMNI link 317 can comprise multiple INET segments joined by bridges the same as 318 for any link; the addressing plans in each segment may be mutually 319 exclusive and managed by different administrative entities. 321 OMNI interface 322 a node's attachment to an OMNI link, and configured over one or 323 more underlying *NET interfaces. If there are multiple OMNI links 324 in an OMNI domain, a separate OMNI interface is configured for 325 each link. 327 OMNI Adaptation Layer (OAL) 328 an OMNI interface process whereby packets admitted into the 329 interface are wrapped in a mid-layer IPv6 header and fragmented/ 330 reassembled if necessary to support the OMNI link Maximum 331 Transmission Unit (MTU). The OAL is also responsible for 332 generating MTU-related control messages as necessary, and for 333 providing addressing context for spanning multiple segments of a 334 bridged OMNI link. 336 OMNI Option 337 an IPv6 Neighbor Discovery option providing multilink parameters 338 for the OMNI interface as specified in Section 11. 340 Mobile Network Prefix Link Local Address (MNP-LLA) 341 an IPv6 Link Local Address that embeds the most significant 64 342 bits of an MNP in the lower 64 bits of fe80::/64, as specified in 343 Section 7. 345 Mobile Network Prefix Unique Local Address (MNP-ULA) 346 an IPv6 Unique-Local Address derived from an MNP-LLA. 348 Administrative Link Local Address (ADM-LLA) 349 an IPv6 Link Local Address that embeds a 32-bit administratively- 350 assigned identification value in the lower 32 bits of fe80::/96, 351 as specified in Section 7. 353 Administrative Unique Local Address (ADM-ULA) 354 an IPv6 Unique-Local Address derived from an ADM-LLA. 356 Multilink 357 an OMNI interface's manner of managing diverse underlying 358 interface connections to data links as a single logical unit. The 359 OMNI interface provides a single unified interface to upper 360 layers, while underlying interface selections are performed on a 361 per-packet basis considering factors such as DSCP, flow label, 362 application policy, signal quality, cost, etc. Multilinking 363 decisions are coordinated in both the outbound (i.e. MN to 364 correspondent) and inbound (i.e., correspondent to MN) directions. 366 Multihop 367 an iterative relaying of IP packets between MNs over an OMNI 368 underlying interface technology (such as omnidirectional wireless) 369 without support of fixed infrastructure. Multihop services entail 370 node-to-node relaying within a Mobile/Vehicular Ad-hoc Network 371 (MANET/VANET) for MN-to-MN communications and/or for "range 372 extension" where MNs within range of communications infrastructure 373 elements provide forwarding services for other MNs. 375 L2 376 The second layer in the OSI network model. Also known as "layer- 377 2", "link-layer", "sub-IP layer", "data link layer", etc. 379 L3 380 The third layer in the OSI network model. Also known as "layer- 381 3", "network-layer", "IP layer", etc. 383 underlying interface 384 a *NET interface over which an OMNI interface is configured. The 385 OMNI interface is seen as a L3 interface by the IP layer, and each 386 underlying interface is seen as a L2 interface by the OMNI 387 interface. The underlying interface either connects directly to 388 the physical communications media or coordinates with another node 389 where the physical media is hosted. 391 Mobility Service Identification (MSID) 392 Each MSE and AR is assigned a unique 32-bit Identification (MSID) 393 (see: Section 7). IDs are assigned according to MS-specific 394 guidelines (e.g., see: [I-D.templin-intarea-6706bis]). 396 Safety-Based Multilink (SBM) 397 A means for ensuring fault tolerance through redundancy by 398 connecting multiple affiliated OMNI interfaces to independent 399 routing topologies (i.e., multiple independent OMNI links). 401 Performance Based Multilink (PBM) 402 A means for selecting underlying interface(s) for packet 403 transmission and reception within a single OMNI interface. 405 OMNI Domain 406 The set of all SBM/PBM OMNI links that collectively provides 407 services for a common set of MSPs. Each OMNI domain consists of a 408 set of affiliated OMNI links that all configure the same ::/48 ULA 409 prefix with a unique 16-bit Subnet ID as discussed in Section 8. 411 3. Requirements 413 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 414 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 415 "OPTIONAL" in this document are to be interpreted as described in BCP 416 14 [RFC2119][RFC8174] when, and only when, they appear in all 417 capitals, as shown here. 419 An implementation is not required to internally use the architectural 420 constructs described here so long as its external behavior is 421 consistent with that described in this document. 423 4. Overlay Multilink Network (OMNI) Interface Model 425 An OMNI interface is a MN virtual interface configured over one or 426 more underlying interfaces, which may be physical (e.g., an 427 aeronautical radio link) or virtual (e.g., an Internet or higher- 428 layer "tunnel"). The MN receives a MNP from the MS, and coordinates 429 with the MS through IPv6 ND message exchanges. The MN uses the MNP 430 to construct a unique Link-Local Address (MNP-LLA) through the 431 algorithmic derivation specified in Section 7 and assigns the LLA to 432 the OMNI interface. 434 The OMNI interface architectural layering model is the same as in 435 [RFC5558][RFC7847], and augmented as shown in Figure 1. The IP layer 436 therefore sees the OMNI interface as a single L3 interface with 437 multiple underlying interfaces that appear as L2 communication 438 channels in the architecture. 440 +----------------------------+ 441 | Upper Layer Protocol | 442 Session-to-IP +---->| | 443 Address Binding | +----------------------------+ 444 +---->| IP (L3) | 445 IP Address +---->| | 446 Binding | +----------------------------+ 447 +---->| OMNI Interface | 448 Logical-to- +---->| (LLA) | 449 Physical | +----------------------------+ 450 Interface +---->| L2 | L2 | | L2 | 451 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 452 +------+------+ +------+ 453 | L1 | L1 | | L1 | 454 | | | | | 455 +------+------+ +------+ 457 Figure 1: OMNI Interface Architectural Layering Model 459 Each underlying interface provides an L2/L1 abstraction according to 460 one of the following models: 462 o INET interfaces connect to an INET either natively or through one 463 or several IPv4 Network Address Translators (NATs). Native INET 464 interfaces have global IP addresses that are reachable from any 465 INET correspondent. NATed INET interfaces typically have private 466 IP addresses and connect to a private network behind one or more 467 NATs that provide INET access. 469 o ANET interfaces connect to a protected ANET that is separated from 470 the open INET by an AR acting as a proxy. The ANET interface may 471 be either on the same L2 link segment as the AR, or separated from 472 the AR by multiple IP hops. 474 o VPNed interfaces use security encapsulation over a *NET to a 475 Virtual Private Network (VPN) gateway. Other than the link-layer 476 encapsulation format, VPNed interfaces behave the same as for 477 Direct interfaces. 479 o Direct (aka "point-to-point") interfaces connect directly to a 480 peer without crossing any *NET paths. An example is a line-of- 481 sight link between a remote pilot and an unmanned aircraft. 483 The OMNI virtual interface model gives rise to a number of 484 opportunities: 486 o since MNP-LLAs are uniquely derived from an MNP, no Duplicate 487 Address Detection (DAD) or Multicast Listener Discovery (MLD) 488 messaging is necessary. 490 o since Temporary ULAs are statistically unique, they can be used 491 without DAD, e.g. for MN-to-MN communications until an MNP-LLA is 492 obtained. 494 o *NET interfaces on the same L2 link segment as an AR do not 495 require any L3 addresses (i.e., not even link-local) in 496 environments where communications are coordinated entirely over 497 the OMNI interface. (An alternative would be to also assign the 498 same LLA to all *NET interfaces.) 500 o as underlying interface properties change (e.g., link quality, 501 cost, availability, etc.), any active interface can be used to 502 update the profiles of multiple additional interfaces in a single 503 message. This allows for timely adaptation and service continuity 504 under dynamically changing conditions. 506 o coordinating underlying interfaces in this way allows them to be 507 represented in a unified MS profile with provisions for mobility 508 and multilink operations. 510 o exposing a single virtual interface abstraction to the IPv6 layer 511 allows for multilink operation (including QoS based link 512 selection, packet replication, load balancing, etc.) at L2 while 513 still permitting L3 traffic shaping based on, e.g., DSCP, flow 514 label, etc. 516 o the OMNI interface allows inter-INET traversal when nodes located 517 in different INETs need to communicate with one another. This 518 mode of operation would not be possible via direct communications 519 over the underlying interfaces themselves. 521 o the OMNI Adaptation Layer (OAL) within the OMNI interface supports 522 lossless and adaptive path MTU mitigations not available for 523 communications directly over the underlying interfaces themselves. 524 The OAL supports "packing" of multiple IP payload packets within a 525 single OAL packet. 527 o L3 sees the OMNI interface as a point of connection to the OMNI 528 link; if there are multiple OMNI links (i.e., multiple MS's), L3 529 will see multiple OMNI interfaces. 531 o Multiple independent OMNI interfaces can be used for increased 532 fault tolerance through Safety-Based Multilink (SBM), with 533 Performance-Based Multilink (PBM) applied within each interface. 535 Other opportunities are discussed in [RFC7847]. Note that even when 536 the OMNI virtual interface is present, applications can still access 537 underlying interfaces either through the network protocol stack using 538 an Internet socket or directly using a raw socket. This allows for 539 intra-network (or point-to-point) communications without invoking the 540 OMNI interface and/or OAL. For example, when an IPv6 OMNI interface 541 is configured over an underlying IPv4 interface, applications can 542 still invoke IPv4 intra-network communications as long as the 543 communicating endpoints are not subject to mobility dynamics. 544 However, the opportunities discussed above are not available when the 545 architectural layering is bypassed in this way. 547 Figure 2 depicts the architectural model for a MN with an attached 548 EUN connecting to the MS via multiple independent *NETs. When an 549 underlying interface becomes active, the MN's OMNI interface sends 550 IPv6 ND messages without encapsulation if the first-hop Access Router 551 (AR) is on the same underlying link; otherwise, the interface uses 552 IP-in-IP encapsulation. The IPv6 ND messages traverse the ground 553 domain *NETs until they reach an AR (AR#1, AR#2, ..., AR#n), which 554 then coordinates with an INET Mobility Service Endpoint (MSE#1, 555 MSE#2, ..., MSE#m) and returns an IPv6 ND message response to the MN. 556 The Hop Limit in IPv6 ND messages is not decremented due to 557 encapsulation; hence, the OMNI interface appears to be attached to an 558 ordinary link. 560 +--------------+ (:::)-. 561 | MN |<-->.-(::EUN:::) 562 +--------------+ `-(::::)-' 563 |OMNI interface| 564 +----+----+----+ 565 +--------|IF#1|IF#2|IF#n|------ + 566 / +----+----+----+ \ 567 / | \ 568 / | \ 569 v v v 570 (:::)-. (:::)-. (:::)-. 571 .-(::*NET:::) .-(::*NET:::) .-(::*NET:::) 572 `-(::::)-' `-(::::)-' `-(::::)-' 573 +----+ +----+ +----+ 574 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 575 . +-|--+ +-|--+ +-|--+ . 576 . | | | 577 . v v v . 578 . <----- INET Encapsulation -----> . 579 . . 580 . +-----+ (:::)-. . 581 . |MSE#2| .-(::::::::) +-----+ . 582 . +-----+ .-(::: INET :::)-. |MSE#m| . 583 . (::::: Routing ::::) +-----+ . 584 . `-(::: System :::)-' . 585 . +-----+ `-(:::::::-' . 586 . |MSE#1| +-----+ +-----+ . 587 . +-----+ |MSE#3| |MSE#4| . 588 . +-----+ +-----+ . 589 . . 590 . . 591 . <----- Worldwide Connected Internetwork ----> . 592 ........................................................... 594 Figure 2: MN/MS Coordination via Multiple *NETs 596 After the initial IPv6 ND message exchange, the MN (and/or any nodes 597 on its attached EUNs) can send and receive IP data packets over the 598 OMNI interface. OMNI interface multilink services will forward the 599 packets via ARs in the correct underlying *NETs. The AR encapsulates 600 the packets according to the capabilities provided by the MS and 601 forwards them to the next hop within the worldwide connected 602 Internetwork via optimal routes. 604 OMNI links span one or more underlying Internetwork via the OMNI 605 Adaptation Layer (OAL) which is based on a mid-layer overlay 606 encapsulation using [RFC2473]. Each OMNI link corresponds to a 607 different overlay (differentiated by an address codepoint) which may 608 be carried over a completely separate underlying topology. Each MN 609 can facilitate SBM by connecting to multiple OMNI links using a 610 distinct OMNI interface for each link. 612 Note: OMNI interface underlying interfaces often connect directly to 613 physical media on the local platform (e.g., a laptop computer with 614 WiFi, etc.), but in some configurations the physical media may be 615 hosted on a separate Local Area Network (LAN) node. In that case, 616 the OMNI interface can establish a Layer-2 VLAN or a point-to-point 617 tunnel (at a layer below the underlying interface) to the node 618 hosting the physical media. The OMNI interface may also apply 619 encapsulation at a layer above the underlying interface such that 620 packets would appear "double-encapsulated" on the LAN; the node 621 hosting the physical media in turn removes the LAN encapsulation 622 prior to transmission or inserts it following reception. Finally, 623 the underlying interface must monitor the node hosting the physical 624 media (e.g., through periodic keepalives) so that it can convey 625 up/down/status information to the OMNI interface. 627 5. OMNI Interface Maximum Transmission Unit (MTU) 629 The OMNI interface observes the link nature of tunnels, including the 630 Maximum Transmission Unit (MTU), Maximum Reassembly Unit (MRU) and 631 the role of fragmentation and reassembly [I-D.ietf-intarea-tunnels]. 632 The OMNI interface is configured over one or more underlying 633 interfaces as discussed in Section 4, where the interfaces (and their 634 associated *NET paths) may have diverse MTUs. The OMNI interface 635 accommodates MTU diversity by encapsulating original IP packets using 636 the OMNI Adaptation Layer (OAL) mid-layer encapsulation and 637 fragmentation/reassembly service. The OAL then further encapsulates 638 the resulting OAL packets/fragments in *NET headers for transmission 639 over underlying interfaces. OMNI interface considerations for 640 accommodating original IP packets of various sizes are discussed in 641 the following sections. 643 5.1. OMNI Interface MTU/MRU 645 IPv6 underlying interfaces are REQUIRED to configure a minimum MTU of 646 1280 bytes and a minimum MRU of 1500 bytes [RFC8200]. Therefore, the 647 minimum IPv6 path MTU is 1280 bytes since routers on the path are not 648 permitted to perform network fragmentation even though the 649 destination is required to reassemble more. The network therefore 650 MUST forward packets of at least 1280 bytes without generating an 651 IPv6 Path MTU Discovery (PMTUD) Packet Too Big (PTB) message 652 [RFC8201]. (Note: the source can apply "source fragmentation" for 653 locally-generated IPv6 packets up to 1500 bytes and larger still if 654 it if has a way to determine that the destination configures a larger 655 MRU, but this does not affect the minimum IPv6 path MTU.) 656 IPv4 underlying interfaces are REQUIRED to configure a minimum MTU of 657 68 bytes [RFC0791] and a minimum MRU of 576 bytes [RFC0791][RFC1122]. 658 Therefore, when the Don't Fragment (DF) bit in the IPv4 header is set 659 to 0 the minimum IPv4 path MTU is 576 bytes since routers on the path 660 support network fragmentation and the destination is required to 661 reassemble at least that much. The OMNI interface therefore MUST set 662 DF to 0 in the IPv4 encapsulation headers of OAL/*NET packets that 663 are no larger than 576 bytes, and MUST set DF to 1 in larger packets. 664 (Note: even if the encapsulation source has a way to determine that 665 the encapsulation destination configures an MRU larger than 576 666 bytes, it should not assume a larger minimum IPv4 path MTU without 667 careful consideration of the issues discussed in Section 5.5.) 669 The OMNI interface configures both an MTU and MRU of 9180 bytes 670 [RFC2492]; the size is therefore not a reflection of the underlying 671 interface or *NET path MTUs, but rather determines the largest 672 original IP packet the OMNI interface can forward or reassemble. The 673 OMNI interface employs the OAL as a "mid-layer" encapsulation, 674 fragmentation and reassembly service for original IP packets, and the 675 OAL in turn uses *NET encapsulation to forward OAL/*NET packets/ 676 fragments over the underlying interfaces (see: Section 5.2). 678 5.2. The OMNI Adaptation Layer (OAL) 680 For each original IP packet/fragment admitted into the OMNI interface 681 that requires fragmentation and/or multi-segment path traversal (see 682 below), the OAL inserts a mid-layer IPv6 encapsulation header per 683 [RFC2473] to create an "OAL packet" before inserting any outer *NET 684 encapsulations. (The OAL does not decrement the inner IP Hop Limit/ 685 TTL during encapsulation since the insertion occurs at a layer below 686 IP forwarding.) If the resulting OAL packet requires fragmentation, 687 the OAL then calculates the 32-bit CRC over the entire packet 688 beginning with the OAL IPv6 header, and writes the value in a 689 trailing 4 byte field at the end of the packet while incrementing the 690 OAL IPv6 Payload Length to reflect the addition of the CRC. The OAL 691 then inserts a single OMNI Routing Header (ORH) if necessary (see: 692 [I-D.templin-intarea-6706bis]) while incrementing Payload Length to 693 reflect the addition of the ORH, fragments the OAL packet if 694 necessary, and forwards the packet/fragments using *NET 695 encapsulation. 697 For each OAL/*NET packet/fragment received by an OMNI interface, the 698 OAL discards the *NET encapsulation headers then performs reassembly 699 if necessary. Following any reassembly, the OAL next removes the ORH 700 if present while decrementing Payload Length to reflect the removal 701 of the ORH. If reassembly was required, the OAL next verifies the 702 CRC and decrements Payload Length to reflect the removal of the CRC. 703 If the CRC was correct, the OAL removes the OAL IPv6 header and 704 delivers the original IP packet to the IP layer; otherwise, it 705 discards the packet. Note that a 32-bit CRC is sufficient for 706 detecting reassembly misassociations for packet sizes no larger than 707 the OMNI interface MTU but may not be sufficient to detect errors for 708 larger sizes [CRC]. 710 When the source OAL performs OAL/*NET encapsulation, it should always 711 assume the IPv4 minimum path MTU (i.e., 576 bytes) as the worst case 712 for OAL fragmentation regardless of the underlying interface IP 713 protocol version since IPv6/IPv4 protocol translation and/or IPv6-in- 714 IPv4 encapsulation may occur in any *NET path. By always assuming 715 the IPv4 minimum even for IPv6 underlying interfaces, the OAL may 716 produce smaller fragments with additional encapsulation overhead but 717 will always interoperate and never run the risk of loss due to an MTU 718 restriction or due to presenting a destination interface with a 719 packet that exceeds its MRU. Additionally, the OAL path could 720 traverse multiple *NET "segments" with intermediate OAL forwarding 721 nodes performing re-encapsulation, where the *NET encapsulation of 722 the previous segment is replaced by the *NET encapsulation of the 723 next segment which may use a differing IP protocol version. Re- 724 encapsulation at each successive intermediate node could introduce a 725 larger encapsulation overhead than that which appeared in previous 726 segments; hence, the worst-case encapsulation overhead must be 727 assumed. 729 The OAL therefore by default assumes an absolute minimum path MTU of 730 576 bytes at each *NET segment for the purpose of generating OAL 731 fragments. Each successive *NET segment will re-encapsulate with 732 either a 20 byte IPv4 or 40 byte IPv6 header, an 8 byte UDP header 733 for INETs and in some cases an IP security encapsulation (40 bytes 734 maximum assumed). Any *NET segment may also insert a maximum-length 735 (40 byte) ORH as an extension to the existing 40 byte OAL IPv6 header 736 plus 8 byte Fragment Header if an ORH was not already present. 737 Assuming therefore an absolute worst case of (40 + 40 + 8) = 88 bytes 738 for *NET encapsulation plus (40 + 40 + 8) = 88 bytes for OAL 739 encapsulation, this leaves 400 bytes to accommodate a portion of the 740 original IP packet/fragment. OMNI interfaces therefore set a minimum 741 Maximum Cell Size (MCS) of 400 bytes as the basis for the minimum- 742 sized OAL fragment that can be assured of traversing all segments 743 without loss due to an MTU/MRU restriction. The fragment size for 744 OAL fragmentation is therefore determined by adding the size of the 745 encapsulating OAL header plus extension headers to the MCS. 747 The OAL therefore MUST NOT perform OAL fragmentation for original IP 748 packets smaller than the minimum MCS. Instead, OAL fragmentation 749 algorithms MUST produce non-final fragments that contain a non- 750 overlapping portion of the original IP packet at least as large as 751 the minimum MCS, and OAL reassembly algorithms MUST unconditionally 752 drop any non-final OAL fragments containing less than the minimum 753 MCS. Additionally, intermediate nodes MUST NOT perform further OAL 754 fragmentation, and OAL destinations MUST unconditionally drop OAL 755 packets/fragments that include any extension headers other than a 756 single ORH and a single Fragment Header. 758 For selected OAL destinations, the OAL source MAY maintain a "path 759 MCS" value initialized to the minimum MCS and increased to larger 760 values if better information is known or discovered. For example: 762 o the OAL can increase path MCS by 8 bytes for ANET paths in which 763 no UDP encapsulation header is needed. 765 o the OAL can increase path MCS by 20 bytes for ANET paths in which 766 no IPv6 hops will occur. 768 o the OAL can increase path MCS by 40 bytes if there is assurance 769 that no ORH will be inserted in the path. 771 o when ANET peers share a common physical link or a fixed path with 772 a known larger MTU, the OAL can base path MCS on this larger size 773 (i.e., instead of 576 bytes) as long as the ANET peer reassembles 774 before re-encapsulating and forwarding (while re-fragmenting if 775 necessary). 777 o etc. 779 The OAL source can also actively probe OAL destinations to discover 780 larger path MCS values (e.g., per [RFC4821][RFC8899]), but care must 781 be taken to avoid setting static values for dynamically changing 782 paths leading to black holes. The probe involves sending an OAL 783 packet that contains more than the minimum MCS worth of probe data 784 and receiving a small acknowledgement message in response. For this 785 purpose, the OAL source can create a large NS message with OMNI 786 options with PadN sub-options (see: Section 11) in order to receive a 787 small NA response from the OAL destination. While observing the 788 minimum MCS will always result in robust and secure behavior, the OAL 789 should optimize path MCS values for OAL destinations when more 790 efficient utilization may result in better performance (e.g. for 791 wireless aviation data links). 793 By way of example, under the minimum MCS a 1500 byte inner IP packet 794 would require 4 OAL fragments, with each non-final fragment 795 containing 400 bytes and the final fragment containing 300 bytes of 796 the original packet. Also note that (while not strictly required) 797 when the OMNI interface sends all fragments of the same fragmented 798 OAL packet consecutively over the same underlying interface with 799 minimal inter-fragment delay the likelihood of successful reassembly 800 may be increased. 802 5.3. OAL ANET/INET Addressing Considerations 804 The OMNI interface performs OAL encapsulation and selects source and 805 destination addresses for the OAL IPv6 header according to the node's 806 ANET/INET orientation. The OMNI interface sets the OAL IPv6 header 807 addresses to Unique Local Addresses (ULAs) based on either 808 Administrative (ADM-ULA) or Mobile Network Prefix (MNP-ULA) values 809 (see: Section 8). When an ADM-ULA or MNP-ULA is not available, the 810 OMNI interface can use Temporary ULAs and/or Host Identity Tags 811 (HITs) instead (see: Section 21). The following sections discuss the 812 addressing considerations for OMNI Interfaces configured over ANET/ 813 INET interfaces. 815 When an OMNI interface sends an original IP packet toward a final 816 destination via an ANET interface, it sends without OAL encapsulation 817 if the packet (including any outer-layer ANET encapsulations) is no 818 larger than the underlying interface MTU for on-link ANET peers or 819 the minimum ANET path MTU for peers separated by multiple IP hops. 820 Otherwise, the OAL inserts an IPv6 header per [RFC2473] with source 821 address set to the node's own ULA and destination set to either the 822 Administrative ULA (ADM-ULA) of the ANET peer or the Mobile Network 823 Prefix ULA (MNP-ULA) corresponding to the final destination (see 824 below). The OAL then fragments if necessary, encapsulates the OAL 825 packet/fragments in any ANET headers and sends them to the ANET peer 826 which either reassembles before forwarding if the OAL destination is 827 its own ADM-ULA or forwards the fragments toward the final 828 destination without first reassembling otherwise. 830 When an OMNI interface sends an original IP packet toward a final 831 destination via an INET interface, it sends packets (including any 832 outer-layer INET encapsulations) no larger than the minimum INET path 833 MTU without OAL encapsulation if the destination is reached via an 834 INET address within the same OMNI link segment. Otherwise, the OAL 835 inserts an IPv6 header per [RFC2473] with source address set to the 836 node's ULA, destination set to the ULA of an OMNI node on the final 837 *NET segment. The OAL then fragments if necessary, encapsulates the 838 OAL packet/fragments in any INET headers and sends them toward the 839 final segment OMNI node, which reassembles before forwarding toward 840 the final destination. 842 5.4. OMNI Interface MTU Feedback Messaging 844 When the OMNI interface admits original IP packets, it invokes the 845 OAL and returns internally-generated ICMPv4 Fragmentation Needed 846 [RFC1191] or ICMPv6 Path MTU Discovery (PMTUD) Packet Too Big (PTB) 848 [RFC8201] messages as necessary. This document refers to both of 849 these ICMPv4/ICMPv6 message types simply as "PTBs", and introduces a 850 distinction between PTB "hard" and "soft" errors as discussed below. 852 Ordinary PTB messages with ICMPv4 header "unused" field or ICMPv6 853 header Code field value 0 are hard errors that always indicate that a 854 packet has been dropped due to a real MTU restriction. However, the 855 OMNI interface can also forward large original IP packets via OAL 856 encapsulation and fragmentation while at the same time returning PTB 857 soft error messages (subject to rate limiting) if it deems the 858 original IP packet too large according to factors such as link 859 performance characteristics, reassembly congestion, etc. This 860 ensures that the path MTU is adaptive and reflects the current path 861 used for a given data flow. The OMNI interface can therefore 862 continuously forward large packets without loss while returning PTB 863 soft error messages recommending a smaller size. Original sources 864 that receive the soft errors in turn reduce the size of the packets 865 they send, i.e., the same as for hard errors. 867 The OMNI interface sets the ICMPv4 header "unused" field or ICMPv6 868 header Code field to the value 1 in PTB soft error messages. The 869 OMNI interface sets the PTB destination address to the source address 870 of the original packet, and sets the source address to the MNP Subnet 871 Router Anycast address of the MN. The OMNI interface then sets the 872 MTU field to a value no smaller than 576 for ICMPv4 or 1280 for 873 ICMPv6, and returns the PTB soft error to the original source. 875 When the original source receives the PTB, it reduces its path MTU 876 estimate the same as for hard errors but does not regard the message 877 as a loss indication. (If the original source does not recognize the 878 soft error code, it regards the PTB the same as a hard error but 879 should heed the retransmission advice given in [RFC8201] suggesting 880 retransmission based on normal packetization layer retransmission 881 timers.) This document therefore updates [RFC1191][RFC4443] and 882 [RFC8201]. Furthermore, implementations of [RFC4821] must be aware 883 that PTB hard or soft errors may arrive at any time even if after a 884 successful MTU probe (this is the same consideration as for an 885 ordinary path fluctuation following a successful probe). 887 An OMNI interface that reassembles OAL fragments may experience 888 congestion-oriented loss in its reassembly cache and can optionally 889 send PTB soft errors to the original source and/or ICMP "Time 890 Exceeded" messages to the source of the OAL fragments. In 891 environments where the messages may contribute to unacceptable 892 additional congestion, however, the OMNI interface can refrain from 893 sending PTB soft errors and simply regard the loss as an ordinary 894 unreported congestion event for which the original source will 895 eventually compensate. 897 Applications that receive PT soft errors can dynamically tune the 898 size of the packets they to send to produce the best possible 899 throughput and latency, with the understanding that these parameters 900 may change over time due to factors such as congestion, mobility, 901 network path changes, etc. The receipt or absence of soft errors 902 should be seen as hints of when increasing or decreasing packet sizes 903 may be beneficial. 905 In summary, the OMNI interface supports continuous transmission and 906 reception of packets of various sizes in the face of dynamically 907 changing network conditions. Moreover, since PTB soft errors do not 908 indicate loss, original sources that receive soft errors can quickly 909 scan for path MTU increases without waiting for the minimum 10 910 minutes specified for loss-oriented PTB hard errors 911 [RFC1191][RFC8201]. The OMNI interface therefore provides a lossless 912 and adaptive service that accommodates MTU diversity especially well- 913 suited for dynamic multilink environments. 915 5.5. OAL Fragmentation Security Implications 917 As discussed in Section 3.7 of [RFC8900], there are four basic 918 threats concerning IPv6 fragmentation; each of which is addressed by 919 effective mitigations as follows: 921 1. Overlapping fragment attacks - reassembly of overlapping 922 fragments is forbidden by [RFC8200]; therefore, this threat does 923 not apply to the OAL. 925 2. Resource exhaustion attacks - this threat is mitigated by 926 providing a sufficiently large OAL reassembly cache and 927 instituting "fast discard" of incomplete reassemblies that may be 928 part of a buffer exhaustion attack. The reassembly cache should 929 be sufficiently large so that a sustained attack does not cause 930 excessive loss of good reassemblies but not so large that (timer- 931 based) data structure management becomes computationally 932 expensive. The cache should also be indexed based on the arrival 933 underlying interface such that congestion experienced over a 934 first underlying interface does not cause discard of incomplete 935 reassemblies for uncongested underlying interfaces. 937 3. Attacks based on predictable fragment identification values - 938 this threat is mitigated by selecting a suitably random ID value 939 per [RFC7739]. 941 4. Evasion of Network Intrusion Detection Systems (NIDS) - this 942 threat is mitigated by setting a minimum MCS for OAL 943 fragmentation, which defeats all "tiny fragment"-based attacks. 945 Additionally, IPv4 fragmentation includes a 16-bit Identification (IP 946 ID) field with only 65535 unique values such that at high data rates 947 the field could wrap and apply to new packets while the fragments of 948 old packets using the same ID are still alive in the network 949 [RFC4963]. However, since the largest OAL fragment that will be sent 950 via an IPv4 *NET path with DF = 0 is 576 bytes any IPv4 fragmentation 951 would occur only on links with an IPv4 MTU smaller than this size, 952 and [RFC3819] recommendations suggest that such links will have low 953 data rates. Since IPv6 provides a 32-bit Identification value, IP ID 954 wraparound at high data rates is not a concern for IPv6 955 fragmentation. 957 Finally, [RFC6980] documents fragmentation security concerns for 958 large IPv6 ND messages. These concerns are addressed when the OMNI 959 interface employs the OAL instead of directly fragmenting the IPv6 ND 960 message itself. For this reason, OMNI interfaces MUST NOT admit IPv6 961 ND messages larger than the OMNI interface MTU, and MUST employ the 962 OAL for IPv6 ND messages admitted into the OMNI interface the same as 963 discussed above. 965 5.6. OAL Super-Packets 967 By default, the source OAL includes a 40-byte IPv6 encapsulation 968 header for each original IP packet during OAL encapsulation. When 969 fragmentation is needed, the source OAL also calculates and includes 970 a 32-bit trailing CRC for the entire packet then performs 971 fragmentation such that a copy of the 40-byte IPv6 header plus an 972 8-byte IPv6 Fragment Header is included in each OAL fragment (when an 973 ORH is added, the OAL encapsulation headers become larger still). 974 However, these encapsulations may represent excessive overhead in 975 some environments. A technique known as "packing" discussed in 976 [I-D.ietf-intarea-tunnels] is therefore supported so that multiple 977 original IP packets can be included within a single OAL "super- 978 packet". 980 When the source OAL has multiple original IP packets with total 981 length no larger than the OMNI interface MTU to send to the same 982 destination, it can optionally concatenate them into a super-packet 983 encapsulated in a single OAL header. Within the OAL super-packet, 984 the IP header of the first original packet (iHa) followed by its data 985 (iDa) is concatenated immediately following the OAL header, then the 986 IP header of the next original packet (iHb) followed by its data 987 (iDb) is concatenated immediately following the first original 988 packet, etc. The OAL super-packet format is transposed from 989 [I-D.ietf-intarea-tunnels] and shown in Figure 3: 991 <-- Multiple original IP packets to be "packed" --> 992 +-----+-----+ 993 | iHa | iDa | 994 +-----+-----+ 995 | 996 | +-----+-----+ 997 | | iHb | iDb | 998 | +-----+-----+ 999 | | 1000 | | +-----+-----+ 1001 | | | iHc | iDc | 1002 | | +-----+-----+ 1003 | | | 1004 v v v 1005 +----------+-----+-----+-----+-----+-----+-----+ 1006 | OAL Hdr | iHa | iDa | iHb | iDb | iHc | iDc | 1007 +----------+-----+-----+-----+-----+-----+-----+ 1008 <--- OAL "Super-Packet" with single OAL Hdr ---> 1010 Figure 3: OAL Super-Packet Format 1012 When the source OAL sends a super-packet, it calculates a CRC and 1013 applies OAL fragmentation if necessary then sends the packet or 1014 fragments to the destination OAL. When the destination OAL receives 1015 the super-packet as a whole packet or as fragments, it reassembles 1016 and verifies the CRC if necessary then regards the OAL header Payload 1017 Length (after subtracting the CRC length) as the sum of the lengths 1018 of all payload packets. The destination OAL then selectively 1019 extracts each individual original IP packet (e.g., by setting 1020 pointers into the buffer containing the super-packet and maintaining 1021 a reference count, by copying each payload packet into its own 1022 buffer, etc.) and forwards each packet or processes it locally as 1023 appropriate. During extraction, the OAL determines the IP protocol 1024 version of each successive original IP packet 'j' by examining the 1025 four most-significant bits of iH(j), and determines the length of the 1026 packet by examining the rest of iH(j) according to the IP protocol 1027 version. 1029 Note that OMNI interfaces must take care to avoid processing super- 1030 packet payload elements that would subvert security. Specifically, 1031 if a super-packet contains a mix of data and control payload packets 1032 (which could include critical security codes), the node MUST NOT 1033 process the data packets before processing the control packets 1035 6. Frame Format 1037 The OMNI interface transmits IP packets according to the native frame 1038 format of each underlying interface. For example, for Ethernet- 1039 compatible interfaces the frame format is specified in [RFC2464], for 1040 aeronautical radio interfaces the frame format is specified in 1041 standards such as ICAO Doc 9776 (VDL Mode 2 Technical Manual), for 1042 tunnels over IPv6 the frame format is specified in [RFC2473], etc. 1044 7. Link-Local Addresses (LLAs) 1046 OMNI nodes are assigned OMNI interface IPv6 Link-Local Addresses 1047 (LLAs) through pre-service administrative actions. "MNP-LLAs" embed 1048 the MNP assigned to the mobile node, while "ADM-LLAs" include an 1049 administratively-unique ID that is guaranteed to be unique on the 1050 link. LLAs are configured as follows: 1052 o IPv6 MNP-LLAs encode the most-significant 64 bits of a MNP within 1053 the least-significant 64 bits of the IPv6 link-local prefix 1054 fe80::/64, i.e., in the LLA "interface identifier" portion. The 1055 prefix length for the LLA is determined by adding 64 to the MNP 1056 prefix length. For example, for the MNP 2001:db8:1000:2000::/56 1057 the corresponding MNP-LLA is fe80::2001:db8:1000:2000/120. 1059 o IPv4-compatible MNP-LLAs are constructed as fe80::ffff:[IPv4], 1060 i.e., the interface identifier consists of 16 '0' bits, followed 1061 by 16 '1' bits, followed by a 32bit IPv4 address/prefix. The 1062 prefix length for the LLA is determined by adding 96 to the MNP 1063 prefix length. For example, the IPv4-Compatible MN OMNI LLA for 1064 192.0.2.0/24 is fe80::ffff:192.0.2.0/120 (also written as 1065 fe80::ffff:c000:0200/120). 1067 o ADM-LLAs are assigned to ARs and MSEs and MUST be managed for 1068 uniqueness. The lower 32 bits of the LLA includes a unique 1069 integer "MSID" value between 0x00000001 and 0xfeffffff, e.g., as 1070 in fe80::1, fe80::2, fe80::3, etc., fe80::feffffff. The ADM-LLA 1071 prefix length is determined by adding 96 to the MSID prefix 1072 length. For example, if the prefix length for MSID 0x10012001 is 1073 16 then the ADM-LLA prefix length is set to 112 and the LLA is 1074 written as fe80::1001:2001/112. The "zero" address for each ADM- 1075 LLA prefix is the Subnet-Router anycast address for that prefix 1076 [RFC4291]; for example, the Subnet-Router anycast address for 1077 fe80::1001:2001/112 is simply fe80::1001:2000. The MSID range 1078 0xff000000 through 0xffffffff is reserved for future use. 1080 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 1081 MNPs can be allocated from that block ensuring that there is no 1082 possibility for overlap between the different MNP- and ADM-LLA 1083 constructs discussed above. 1085 Since MNP-LLAs are based on the distribution of administratively 1086 assured unique MNPs, and since ADM-LLAs are guaranteed unique through 1087 administrative assignment, OMNI interfaces set the autoconfiguration 1088 variable DupAddrDetectTransmits to 0 [RFC4862]. 1090 Note: If future protocol extensions relax the 64-bit boundary in IPv6 1091 addressing, the additional prefix bits of an MNP could be encoded in 1092 bits 16 through 63 of the MNP-LLA. (The most-significant 64 bits 1093 would therefore still be in bits 64-127, and the remaining bits would 1094 appear in bits 16 through 48.) However, the analysis provided in 1095 [RFC7421] suggests that the 64-bit boundary will remain in the IPv6 1096 architecture for the foreseeable future. 1098 Note: Even though this document honors the 64-bit boundary in IPv6 1099 addressing, it specifies prefix lengths longer than /64 for routing 1100 purposes. This effectively extends IPv6 routing determination into 1101 the interface identifier portion of the IPv6 address, but it does not 1102 redefine the 64-bit boundary. Modern routing protocol 1103 implementations honor IPv6 prefixes of all lengths, up to and 1104 including /128. 1106 8. Unique-Local Addresses (ULAs) 1108 OMNI domains use IPv6 Unique-Local Addresses (ULAs) as the source and 1109 destination addresses in OAL IPv6 encapsulation headers. ULAs are 1110 only routable within the scope of a an OMNI domain, and are derived 1111 from the IPv6 Unique Local Address prefix fc00::/7 followed by the L 1112 bit set to 1 (i.e., as fd00::/8) followed by a 40-bit pseudo-random 1113 Global ID to produce the prefix [ULA]::/48, which is then followed by 1114 a 16-bit Subnet ID then finally followed by a 64 bit Interface ID as 1115 specified in Section 3 of [RFC4193]. All nodes in the same OMNI 1116 domain configure the same 40-bit Global ID as the OMNI domain 1117 identifier. The statistic uniqueness of the 40-bit pseudo-random 1118 Global ID allows different OMNI domains to be joined together in the 1119 future without requiring renumbering. 1121 Each OMNI link instance is identified by a value between 0x0000 and 1122 0xfeff in bits 48-63 of [ULA]::/48; the values 0xff00 through 0xfffe 1123 are reserved for future use, and the value 0xffff denotes the 1124 presence of a Temporary ULA (see below). For example, OMNI ULAs 1125 associated with instance 0 are configured from the prefix 1126 [ULA]:0000::/64, instance 1 from [ULA]:0001::/64, instance 2 from 1127 [ULA]:0002::/64, etc. ULAs and their associated prefix lengths are 1128 configured in correspondence with LLAs through stateless prefix 1129 translation where "MNP-ULAs" are assigned in correspondence to MNP- 1130 LLAs and "ADM-ULAs" are assigned in correspondence to ADM-LLAs. For 1131 example, for OMNI link instance [ULA]:1010::/64: 1133 o the MNP-ULA corresponding to the MNP-LLA fe80::2001:db8:1:2 with a 1134 56-bit MNP length is derived by copying the lower 64 bits of the 1135 LLA into the lower 64 bits of the ULA as 1136 [ULA]:1010:2001:db8:1:2/120 (where, the ULA prefix length becomes 1137 64 plus the IPv6 MNP length). 1139 o the MNP-ULA corresponding to fe80::ffff:192.0.2.0 with a 28-bit 1140 MNP length is derived by simply writing the LLA interface ID into 1141 the lower 64 bits as [ULA]:1010:0:ffff:192.0.2.0/124 (where, the 1142 ULA prefix length is 64 plus 32 plus the IPv4 MNP length). 1144 o the ADM-ULA corresponding to fe80::1000/112 is simply 1145 [ULA]:1010::1000/112. 1147 o the ADM-ULA corresponding to fe80::/128 is simply 1148 [ULA]:1010::/128. 1150 o etc. 1152 Each OMNI interface assigns the Anycast ADM-ULA specific to the OMNI 1153 link instance. For example, the OMNI interface connected to instance 1154 3 assigns the Anycast address [ULA]:0003::/128. Routers that 1155 configure OMNI interfaces advertise the OMNI service prefix (e.g., 1156 [ULA]:0003::/64) into the local routing system so that applications 1157 can direct traffic according to SBM requirements. 1159 The ULA presents an IPv6 address format that is routable within the 1160 OMNI routing system and can be used to convey link-scoped IPv6 ND 1161 messages across multiple hops using IPv6 encapsulation [RFC2473]. 1162 The OMNI link extends across one or more underling Internetworks to 1163 include all ARs and MSEs. All MNs are also considered to be 1164 connected to the OMNI link, however OAL encapsulation is omitted 1165 whenever possible to conserve bandwidth (see: Section 13). 1167 Each OMNI link can be subdivided into "segments" that often 1168 correspond to different administrative domains or physical 1169 partitions. OMNI nodes can use IPv6 Segment Routing [RFC8402] when 1170 necessary to support efficient packet forwarding to destinations 1171 located in other OMNI link segments. A full discussion of Segment 1172 Routing over the OMNI link appears in [I-D.templin-intarea-6706bis]. 1174 Temporary ULAs are constructed per [I-D.ietf-6man-rfc4941bis] based 1175 on the prefix [ULA]:ffff::/64 and used by MNs when they have no other 1176 addresses. Temporary ULAs can be used for MN-to-MN communications 1177 outside the context of any supporting OMNI link infrastructure, and 1178 can also be used as an initial address while the MN is in the process 1179 of procuring an MNP. Temporary ULAs are not routable within the OMNI 1180 routing system, and are therefore useful only for OMNI link "edge" 1181 communications. Temporary ULAs employ optimistic DAD principles 1182 [RFC4429] since they are probabilistically unique. 1184 Note: IPv6 ULAs taken from the prefix fc00::/7 followed by the L bit 1185 set to 0 (i.e., as fc00::/8) are never used for OMNI OAL addressing, 1186 however the range could be used for MSP and MNP addressing under 1187 certain limiting conditions (see: Section 9). 1189 9. Global Unicast Addresses (GUAs) 1191 OMNI domains use IP Global Unicast Address (GUA) prefixes [RFC4291] 1192 as Mobility Service Prefixes (MSPs) from which Mobile Network 1193 Prefixes (MNP) are delegated to Mobile Nodes (MNs). 1195 For IPv6, GUA prefixes are assigned by IANA [IPV6-GUA] and/or an 1196 associated regional assigned numbers authority such that the OMNI 1197 domain can be interconnected to the global IPv6 Internet without 1198 causing inconsistencies in the routing system. An OMNI domain could 1199 instead use ULAs with the 'L' bit set to 0 (i.e., from the prefix 1200 fc00::/8)[RFC4193], however this would require IPv6 NAT if the domain 1201 were ever connected to the global IPv6 Internet. 1203 For IPv4, GUA prefixes are assigned by IANA [IPV4-GUA] and/or an 1204 associated regional assigned numbers authority such that the OMNI 1205 domain can be interconnected to the global IPv4 Internet without 1206 causing routing inconsistencies. An OMNI domain could instead use 1207 private IPv4 prefixes (e.g., 10.0.0.0/8, etc.) [RFC3330], however 1208 this would require IPv4 NAT if the domain were ever connected to the 1209 global IPv4 Internet. 1211 10. Node Identification 1213 OMNI MNs and MSEs that connect over open Internetworks generate a 1214 Host Identity Tag (HIT) as specified in [RFC7401] and use the value 1215 as a robust general-purpose node identification value. Hierarchical 1216 HITs (HHITs) [I-D.ietf-drip-rid] may provide a useful alternative in 1217 certain domains such as the Unmanned (Air) Traffic Management (UTM) 1218 service for Unmanned Air Systems (UAS). MNs and MSEs can then use 1219 their (H)HITs in IPv6 ND control message exchanges. 1221 When a MN is truly outside the context of any infrastructure, it may 1222 have no MNP information at all. In that case, the MN can use its 1223 (H)HIT as an IPv6 source/destination address for sustained 1224 communications in Vehicle-to-Vehicle (V2V) and (multihop) Vehicle-to- 1225 Infrastructure (V2I) scenarios. The MN can also propagate the (H)HIT 1226 into the multihop routing tables of (collective) Mobile/Vehicular Ad- 1227 hoc Networks (MANETs/VANETs) using only the vehicles themselves as 1228 communications relays. 1230 When a MN connects to ARs over (non-multihop) protected-spectrum 1231 ANETs, an alternate form of node identification (e.g., MAC address, 1232 serial number, airframe identification value, VIN, etc.) may be 1233 sufficient. In that case, the MN should still generate a (H)HIT and 1234 maintain it in conjunction with any other node identifiers. The MN 1235 can then include OMNI "Node Identification" sub-options (see: 1236 Section 11.1.11) in IPv6 ND messages should the need to transmit 1237 identification information over the network arise. 1239 11. Address Mapping - Unicast 1241 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 1242 state and use the link-local address format specified in Section 7. 1243 OMNI interface IPv6 Neighbor Discovery (ND) [RFC4861] messages sent 1244 over physical underlying interfaces without encapsulation observe the 1245 native underlying interface Source/Target Link-Layer Address Option 1246 (S/TLLAO) format (e.g., for Ethernet the S/TLLAO is specified in 1247 [RFC2464]). OMNI interface IPv6 ND messages sent over underlying 1248 interfaces via encapsulation do not include S/TLLAOs which were 1249 intended for encoding physical L2 media address formats and not 1250 encapsulation IP addresses. Furthermore, S/TLLAOs are not intended 1251 for encoding additional interface attributes needed for multilink 1252 coordination. Hence, this document does not define an S/TLLAO format 1253 but instead defines a new option type termed the "OMNI option" 1254 designed for these purposes. 1256 MNs such as aircraft typically have many wireless data link types 1257 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 1258 etc.) with diverse performance, cost and availability properties. 1259 The OMNI interface would therefore appear to have multiple L2 1260 connections, and may include information for multiple underlying 1261 interfaces in a single IPv6 ND message exchange. OMNI interfaces use 1262 an IPv6 ND option called the OMNI option formatted as shown in 1263 Figure 4: 1265 0 1 2 3 1266 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 1267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1268 | Type | Length | Preflen | S/T-omIndex | 1269 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1270 | | 1271 ~ Sub-Options ~ 1272 | | 1273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1275 Figure 4: OMNI Option Format 1277 In this format: 1279 o Type is set to TBD1. 1281 o Length is set to the number of 8 octet blocks in the option. The 1282 value 0 is invalid, while the values 1 through 255 (i.e., 8 1283 through 2040 octets, respectively) indicate the total length of 1284 the OMNI option. 1286 o Preflen is an 8 bit field that determines the length of prefix 1287 associated with an LLA. Values 0 through 128 specify a valid 1288 prefix length (all other values are invalid). For IPv6 ND 1289 messages sent from a MN to the MS, Preflen applies to the IPv6 1290 source LLA and provides the length that the MN is requesting or 1291 asserting to the MS. For IPv6 ND messages sent from the MS to the 1292 MN, Preflen applies to the IPv6 destination LLA and indicates the 1293 length that the MS is granting to the MN. For IPv6 ND messages 1294 sent between MS endpoints, Preflen provides the length associated 1295 with the source/target MN that is subject of the ND message. 1297 o S/T-omIndex is an 8 bit field corresponds to the omIndex value for 1298 source or target underlying interface used to convey this IPv6 ND 1299 message. OMNI interfaces MUST number each distinct underlying 1300 interface with an omIndex value between '1' and '255' that 1301 represents a MN-specific 8-bit mapping for the actual ifIndex 1302 value assigned by network management [RFC2863] (the omIndex value 1303 '0' is reserved for use by the MS). For RS and NS messages, S/ 1304 T-omIndex corresponds to the source underlying interface the 1305 message originated from. For RA and NA messages, S/T-omIndex 1306 corresponds to the target underlying interface that the message is 1307 destined to. (For NS messages used for Neighbor Unreachability 1308 Detection (NUD), S/T-omIndex instead identifies the neighbor's 1309 underlying interface to be used as the target interface to return 1310 the NA.) 1312 o Sub-Options is a Variable-length field, of length such that the 1313 complete OMNI Option is an integer multiple of 8 octets long. 1314 Contains one or more Sub-Options, as described in Section 11.1. 1316 The OMNI option may appear in any IPv6 ND message type; it is 1317 processed by interfaces that recognize the option and ignored by all 1318 other interfaces. If multiple OMNI option instances appear in the 1319 same IPv6 ND message, the interface processes the Preflen and S/ 1320 T-omIndex fields in the first instance and ignores those fields in 1321 all other instances. The interface processes the Sub-Options of all 1322 OMNI option instances in the same IPv6 ND message in the consecutive 1323 order in which they occur. 1325 The OMNI option(s) in each IPv6 ND message may include full or 1326 partial information for the neighbor. The union of the information 1327 in the most recently received OMNI options is therefore retained, and 1328 the information is aged/removed in conjunction with the corresponding 1329 neighbor cache entry. 1331 11.1. Sub-Options 1333 Each OMNI option includes zero or more Sub-Options. Each consecutive 1334 Sub-Option is concatenated immediately after its predecessor. All 1335 Sub-Options except Pad1 (see below) are in type-length-value (TLV) 1336 encoded in the following format: 1338 0 1 2 1339 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 1340 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1341 | Sub-Type| Sub-length | Sub-Option Data ... 1342 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1344 Figure 5: Sub-Option Format 1346 o Sub-Type is a 5-bit field that encodes the Sub-Option type. Sub- 1347 Options defined in this document are: 1349 Sub-Option Name Sub-Type 1350 Pad1 0 1351 PadN 1 1352 Interface Attributes (Type 1) 2 1353 Interface Attributes (Type 2) 3 1354 Traffic Selector 4 1355 MS-Register 5 1356 MS-Release 6 1357 Geo Coordinates 7 1358 DHCPv6 Message 8 1359 HIP Message 9 1360 Node Identification 10 1361 Sub-Type Extension 30 1363 Figure 6 1365 Sub-Types 11-29 are available for future assignment for major 1366 protocol functions. Sub-Type 31 is reserved by IANA. 1368 o Sub-Length is an 11-bit field that encodes the length of the Sub- 1369 Option Data ranging from 0 to 2034 octets. 1371 o Sub-Option Data is a block of data with format determined by Sub- 1372 Type and length determined by Sub-Length. 1374 During transmission, the OMNI interface codes Sub-Type and Sub-Length 1375 together in network byte order in 2 consecutive octets, where Sub- 1376 Option Data may be up to 2034 octets in length. This allows ample 1377 space for coding large objects (e.g., ascii character strings, 1378 protocol messages, security codes, etc.), while a single OMNI option 1379 is limited to 2040 octets the same as for any IPv6 ND option. If the 1380 Sub-Options to be coded would cause an OMNI option to exceed 2040 1381 octets, the OMNI interface codes any remaining Sub-Options in 1382 additional OMNI option instances in the intended order of processing 1383 in the same IPv6 ND message. Implementations must therefore observe 1384 size limitations, and must refrain from sending IPv6 ND messages 1385 larger than the OMNI interface MTU. 1387 During reception, the OMNI interface processes each OMNI option Sub- 1388 Option while skipping over and ignoring any unrecognized Sub-Options. 1389 The OMNI interface processes the Sub-Options of all OMNI option 1390 instances in the consecutive order in which they appear in the IPv6 1391 ND message, beginning with the first instance and continuing through 1392 any additional instances to the end of the message. If a Sub-Option 1393 length would cause the running total for that OMNI option to exceed 1394 the length coded in the option header, the interface accepts any Sub- 1395 Options already processed and ignores the remainder of that OMNI 1396 option. The interface then processes any remaining OMNI options in 1397 the same fashion to the end of the IPv6 ND message. 1399 Note: large objects that exceed the Sub-Option Data limit of 2034 1400 octets are not supported under the current specification; if this 1401 proves to be limiting in practice, future specifications may define 1402 support for fragmenting large objects across multiple OMNI options 1403 within the same IPv6 ND message. 1405 The following Sub-Option types and formats are defined in this 1406 document: 1408 11.1.1. Pad1 1410 0 1411 0 1 2 3 4 5 6 7 1412 +-+-+-+-+-+-+-+-+ 1413 | S-Type=0|x|x|x| 1414 +-+-+-+-+-+-+-+-+ 1416 Figure 7: Pad1 1418 o Sub-Type is set to 0. If multiple instances appear in OMNI 1419 options of the same message all are processed. 1421 o Sub-Type is followed by three 'x' bits, set randomly on 1422 transmission and ignored on receipt. Pad1 therefore consists of a 1423 1 octet with the most significant 5 bits set to 0, and with no 1424 Sub-Length or Sub-Option Data fields following. 1426 11.1.2. PadN 1428 0 1 2 1429 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 1430 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1431 | S-Type=1| Sub-length=N | N padding octets ... 1432 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1434 Figure 8: PadN 1436 o Sub-Type is set to 1. If multiple instances appear in OMNI 1437 options of the same message all are processed. 1439 o Sub-Length is set to N (from 0 to 2034) that encodes the number of 1440 padding octets that follow. 1442 o Sub-Option Data consists of N zero-valued octets. 1444 11.1.3. Interface Attributes (Type 1) 1446 The Interface Attributes (Type 1) sub-option provides a basic set of 1447 attributes for underlying interfaces. Interface Attributes (Type 1) 1448 is deprecated throughout the rest of this specification, and 1449 Interface Attributes (Type 2) (see: Section 11.1.4) are indicated 1450 wherever the term "Interface Attributes" appears without an 1451 associated Type designation. 1453 Nodes SHOULD NOT include Interface Attributes (Type 1) sub-options in 1454 IPv6 ND messages they send, and MUST ignore any in IPv6 ND messages 1455 they receive. If an Interface Attributes (Type 1) is included, it 1456 must have the following format: 1458 0 1 2 3 1459 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 1460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1461 | Sub-Type=2| Sub-length=N | omIndex | omType | 1462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1463 | Provider ID | Link | Resvd |P00|P01|P02|P03|P04|P05|P06|P07| 1464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1465 |P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19|P20|P21|P22|P23| 1466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1467 |P24|P25|P26|P27|P28|P29|P30|P31|P32|P33|P34|P35|P36|P37|P38|P39| 1468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1469 |P40|P41|P42|P43|P44|P45|P46|P47|P48|P49|P50|P51|P52|P53|P54|P55| 1470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1471 |P56|P57|P58|P59|P60|P61|P62|P63| 1472 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1474 Figure 9: Interface Attributes (Type 1) 1476 o Sub-Type is set to 2. If multiple instances with different 1477 omIndex values appear in OMNI option of the same message all are 1478 processed; if multiple instances with the same omIndex value 1479 appear, the first is processed and all others are ignored 1481 o Sub-Length is set to N (from 4 to 2034) that encodes the number of 1482 Sub-Option Data octets that follow. 1484 o omIndex is a 1-octet field containing a value from 0 to 255 1485 identifying the underlying interface for which the attributes 1486 apply. 1488 o omType is a 1-octet field containing a value from 0 to 255 1489 corresponding to the underlying interface identified by omIndex. 1491 o Provider ID is a 1-octet field containing a value from 0 to 255 1492 corresponding to the underlying interface identified by omIndex. 1494 o Link encodes a 4-bit link metric. The value '0' means the link is 1495 DOWN, and the remaining values mean the link is UP with metric 1496 ranging from '1' ("lowest") to '15' ("highest"). 1498 o Resvd is reserved for future use. Set to 0 on transmission and 1499 ignored on reception. 1501 o A 16-octet ""Preferences" field immediately follows 'Resvd', with 1502 values P[00] through P[63] corresponding to the 64 Differentiated 1503 Service Code Point (DSCP) values [RFC2474]. Each 2-bit P[*] field 1504 is set to the value '0' ("disabled"), '1' ("low"), '2' ("medium") 1505 or '3' ("high") to indicate a QoS preference for underlying 1506 interface selection purposes. 1508 11.1.4. Interface Attributes (Type 2) 1510 The Interface Attributes (Type 2) sub-option provides L2 forwarding 1511 information for the multilink conceptual sending algorithm discussed 1512 in Section 13. The L2 information is used for selecting among 1513 potentially multiple candidate underlying interfaces that can be used 1514 to forward packets to the neighbor based on factors such as DSCP 1515 preferences and link quality. Interface Attributes (Type 2) further 1516 includes link-layer address information to be used for either OAL 1517 encapsulation or direct UDP/IP encapsulation (when OAL encapsulation 1518 can be avoided). 1520 Interface Attributes (Type 2) are the sole Interface Attributes 1521 format in this specification that all OMNI nodes must honor. 1522 Wherever the term "Interface Attributes" occurs throughout this 1523 specification without a "Type" designation, the format given below is 1524 indicated: 1526 0 1 2 3 1527 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 1528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1529 | S-Type=3| Sub-length=N | omIndex | omType | 1530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1531 | Provider ID | Link |R| API | SRT | FMT | LHS (0 - 7) | 1532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1533 | LHS (bits 8 - 31) | ~ 1534 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1535 ~ ~ 1536 ~ Link Layer Address (L2ADDR) ~ 1537 ~ ~ 1538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1539 | Bitmap(0)=0xff|P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11| 1540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1541 |P12|P13|P14|P15|P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27| 1542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1543 |P28|P29|P30|P31| Bitmap(1)=0xff|P32|P33|P34|P35|P36| ... 1544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1546 Figure 10: Interface Attributes (Type 2) 1548 o Sub-Type is set to 3. If multiple instances with different 1549 omIndex values appear in OMNI options of the same message all are 1550 processed; if multiple instances with the same omIndex value 1551 appear, the first is processed and all others are ignored. 1553 o Sub-Length is set to N (from 4 to 2034) that encodes the number of 1554 Sub-Option Data octets that follow. The 'omIndex', 'omType', 1555 'Provider ID', 'Link', 'R' and 'API' fields are always present; 1556 hence, the remainder of the Sub-Option Data is limited to 2030 1557 octets. 1559 o Sub-Option Data contains an "Interface Attributes (Type 2)" option 1560 encoded as follows: 1562 * omIndex is set to an 8-bit integer value corresponding to a 1563 specific underlying interface the same as specified above for 1564 the OMNI option S/T-omIndex field. The OMNI options of a same 1565 message may include multiple Interface Attributes Sub-Options, 1566 with each distinct omIndex value pertaining to a different 1567 underlying interface. The OMNI option will often include an 1568 Interface Attributes Sub-Option with the same omIndex value 1569 that appears in the S/T-omIndex. In that case, the actual 1570 encapsulation address of the received IPv6 ND message should be 1571 compared with the L2ADDR encoded in the Sub-Option (see below); 1572 if the addresses are different (or, if L2ADDR is absent) the 1573 presence of a NAT is assumed. 1575 * omType is set to an 8-bit integer value corresponding to the 1576 underlying interface identified by omIndex. The value 1577 represents an OMNI interface-specific 8-bit mapping for the 1578 actual IANA ifType value registered in the 'IANAifType-MIB' 1579 registry [http://www.iana.org]. 1581 * Provider ID is set to an OMNI interface-specific 8-bit ID value 1582 for the network service provider associated with this omIndex. 1584 * Link encodes a 4-bit link metric. The value '0' means the link 1585 is DOWN, and the remaining values mean the link is UP with 1586 metric ranging from '1' ("lowest") to '15' ("highest"). 1588 * R is reserved for future use. 1590 * API - a 3-bit "Address/Preferences/Indexed" code that 1591 determines the contents of the remainder of the sub-option as 1592 follows: 1594 + When the most significant bit (i.e., "Address") is set to 1, 1595 the SRT, FMT, LHS and L2ADDR fields are included immediately 1596 following the API code; else, they are omitted. 1598 + When the next most significant bit (i.e., "Preferences") is 1599 set to 1, a preferences block is included next; else, it is 1600 omitted. (Note that if "Address" is set the preferences 1601 block immediately follows L2ADDR; else, it immediately 1602 follows the API code.) 1604 + When a preferences block is present and the least 1605 significant bit (i.e., "Indexed") is set to 0, the block is 1606 encoded in "Simplex" form as shown in Figure 9; else it is 1607 encoded in "Indexed" form as discussed below. 1609 * When API indicates that an "Address" is included, the following 1610 fields appear in consecutive order (else, they are omitted): 1612 + SRT - a 5-bit Segment Routing Topology prefix length value 1613 that (when added to 96) determines the prefix length to 1614 apply to the ULA formed from concatenating [ULA*]::/96 with 1615 the 32 bit LHS MSID value that follows. For example, the 1616 value 16 corresponds to the prefix length 112. 1618 + FMT - a 3-bit "Framework/Mode/Type" code corresponding to 1619 the included Link Layer Address as follows: 1621 - When the most significant bit (i.e., "Framework") is set 1622 to 1, L2ADDR is the INET encapsulation address for the 1623 Source/Target Client itself; otherwise L2ADDR is the 1624 address of the Server/Proxy named in the LHS. 1626 - When the next most significant bit (i.e., "Mode") is set 1627 to 1, the Framework node is (likely) located behind an 1628 INET Network Address Translator (NAT); otherwise, it is 1629 on the open INET. 1631 - When the least significant bit (i.e., "Type") is set to 1632 0, L2ADDR includes a UDP Port Number followed by an IPv4 1633 address; otherwise, it includes a UDP Port Number 1634 followed by an IPv6 address. 1636 + LHS - the 32 bit MSID of the Last Hop Server/Proxy on the 1637 path to the target. When SRT and LHS are both set to 0, the 1638 LHS is considered unspecified in this IPv6 ND message. When 1639 SRT is set to 0 and LHS is non-zero, the prefix length is 1640 set to 128. SRT and LHS together provide guidance to the 1641 OMNI interface forwarding algorithm. Specifically, if SRT/ 1642 LHS is located in the local OMNI link segment then the OMNI 1643 interface can encapsulate according to FMT/L2ADDR (following 1644 any necessary NAT traversal messaging); else, it must 1645 forward according to the OMNI link spanning tree. See 1646 [I-D.templin-intarea-6706bis] for further discussion. 1648 + Link Layer Address (L2ADDR) - Formatted according to FMT, 1649 and identifies the link-layer address (i.e., the 1650 encapsulation address) of the source/target. The UDP Port 1651 Number appears in the first 2 octets and the IP address 1652 appears in the next 4 octets for IPv4 or 16 octets for IPv6. 1653 The Port Number and IP address are recorded in network byte 1654 order, and in ones-compliment "obfuscated" form per 1655 [RFC4380]. The OMNI interface forwarding algorithm uses 1656 FMT/L2ADDR to determine the encapsulation address for 1657 forwarding when SRT/LHS is located in the local OMNI link 1658 segment. Note that if the target is behind a NAT, L2ADDR 1659 will contain the mapped INET address stored in the NAT; 1660 otherwise, L2ADDR will contain the native INET information 1661 of the target itself. 1663 * When API indicates that "Preferences" are included, a 1664 preferences block appears as the remainder of the Sub-Option as 1665 a series of Bitmaps and P[*] values. In "Simplex" form, the 1666 index for each singleton Bitmap octet is inferred from its 1667 sequential position (i.e., 0, 1, 2, ...) as shown in Figure 10. 1668 In "Indexed" form, each Bitmap is preceded by an Index octet 1669 that encodes a value "i" = (0 - 255) as the index for its 1670 companion Bitmap as follows: 1672 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1673 | Index=i | Bitmap(i) |P[*] values ... 1674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1676 Figure 11 1678 * The preferences consist of a first (simplex/indexed) Bitmap 1679 (i.e., "Bitmap(i)") followed by 0-8 single-octet blocks of 1680 2-bit P[*] values, followed by a second Bitmap (i), followed by 1681 0-8 blocks of P[*] values, etc. Reading from bit 0 to bit 7, 1682 the bits of each Bitmap(i) that are set to '1'' indicate the 1683 P[*] blocks from the range P[(i*32)] through P[(i*32) + 31] 1684 that follow; if any Bitmap(i) bits are '0', then the 1685 corresponding P[*] block is instead omitted. For example, if 1686 Bitmap(0) contains 0xff then the block with P[00]-P[03], 1687 followed by the block with P[04]-P[07], etc., and ending with 1688 the block with P[28]-P[31] are included (as shown in Figure 9). 1689 The next Bitmap(i) is then consulted with its bits indicating 1690 which P[*] blocks follow, etc. out to the end of the Sub- 1691 Option. 1693 * Each 2-bit P[*] field is set to the value '0' ("disabled"), '1' 1694 ("low"), '2' ("medium") or '3' ("high") to indicate a QoS 1695 preference for underlying interface selection purposes. Not 1696 all P[*] values need to be included in the OMNI option of each 1697 IPv6 ND message received. Any P[*] values represented in an 1698 earlier OMNI option but omitted in the current OMNI option 1699 remain unchanged. Any P[*] values not yet represented in any 1700 OMNI option default to "medium". 1702 * The first 16 P[*] blocks correspond to the 64 Differentiated 1703 Service Code Point (DSCP) values P[00] - P[63] [RFC2474]. Any 1704 additional P[*] blocks that follow correspond to "pseudo-DSCP" 1705 traffic classifier values P[64], P[65], P[66], etc. See 1706 Appendix A for further discussion and examples. 1708 11.1.5. Traffic Selector 1709 0 1 2 3 1710 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 1711 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1712 | S-Type=4| Sub-length=N | omIndex | ~ 1713 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1714 ~ ~ 1715 ~ RFC 6088 Format Traffic Selector ~ 1716 ~ ~ 1717 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1719 Figure 12: Traffic Selector 1721 o Sub-Type is set to 4. If multiple instances appear in OMNI 1722 options of the same message all are processed, i.e., even if the 1723 same omIndex value appears multiple times. 1725 o Sub-Length is set to N (from 1 to 2034) that encodes the number of 1726 Sub-Option Data octets that follow. 1728 o Sub-Option Data contains a 1 octet omIndex encoded exactly as 1729 specified in Section 11.1.3, followed by an N-1 octet traffic 1730 selector formatted per [RFC6088] beginning with the "TS Format" 1731 field. The largest traffic selector for a given omIndex is 1732 therefore 2033 octets. 1734 11.1.6. MS-Register 1736 0 1 2 3 1737 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 1738 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1739 | S-Type=5| Sub-length=4n | MSID[1] (bits 0 - 15) | 1740 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1741 | MSID [1] (bits 16 - 32) | MSID[2] (bits 0 - 15) | 1742 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1743 | MSID [2] (bits 16 - 32) | MSID[3] (bits 0 - 15) | 1744 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1745 ... ... ... ... ... ... 1746 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1747 | MSID [n] (bits 16 - 32) | 1748 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1750 Figure 13: MS-Register Sub-option 1752 o Sub-Type is set to 5. If multiple instances appear in OMNI 1753 options of the same message all are processed. Only the first 1754 MAX_MSID values processed (whether in a single instance or 1755 multiple) are retained and all other MSIDs are ignored. 1757 o Sub-Length is set to 4n, with 508 as the maximum value for n. The 1758 length of the Sub-Option Data section is therefore limited to 2032 1759 octets. 1761 o A list of n 4 octet MSIDs is included in the following 4n octets. 1762 The Anycast MSID value '0' in an RS message MS-Register sub-option 1763 requests the recipient to return the MSID of a nearby MSE in a 1764 corresponding RA response. 1766 11.1.7. MS-Release 1768 0 1 2 3 1769 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 1770 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1771 | S-Type=6| Sub-length=4n | MSID[1] (bits 0 - 15) | 1772 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1773 | MSID [1] (bits 16 - 32) | MSID[2] (bits 0 - 15) | 1774 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1775 | MSID [2] (bits 16 - 32) | MSID[3] (bits 0 - 15) | 1776 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1777 ... ... ... ... ... ... 1778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1779 | MSID [n] (bits 16 - 32) | 1780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1782 Figure 14: MS-Release Sub-option 1784 o Sub-Type is set to 6. If multiple instances appear in OMNI 1785 options of the same message all are processed. Only the first 1786 MAX_MSID values processed (whether in a single instance or 1787 multiple) are retained and all other MSIDs are ignored. 1789 o Sub-Length is set to 4n, with 508 as the maximum value for n. The 1790 length of the Sub-Option Data section is therefore limited to 2032 1791 octets. 1793 o A list of n 4 octet MSIDs is included in the following 4n octets. 1794 The Anycast MSID value '0' is ignored in MS-Release sub-options, 1795 i.e., only non-zero values are processed. 1797 11.1.8. Geo Coordinates 1798 0 1 2 3 1799 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 1800 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1801 | S-Type=7| Sub-length=N | Geo Coordinates 1802 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... 1804 Figure 15: Geo Coordinates Sub-option 1806 o Sub-Type is set to 7. If multiple instances appear in OMNI 1807 options of the same message the first is processed and all others 1808 are ignored. 1810 o Sub-Length is set to N (from 0 to 2034) that encodes the number of 1811 Sub-Option Data octets that follow. 1813 o A set of Geo Coordinates of maximum length 2034 octets. Format(s) 1814 to be specified in future documents; should include Latitude/ 1815 Longitude, plus any additional attributes such as altitude, 1816 heading, speed, etc. 1818 11.1.9. Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Message 1820 The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) sub-option 1821 may be included in the OMNI options of RS messages sent by MNs and RA 1822 messages returned by MSEs. ARs that act as proxys to forward RS/RA 1823 messages between MNs and MSEs also forward DHCPv6 sub-options 1824 unchanged and do not process DHCPv6 sub-options themselves. 1826 0 1 2 3 1827 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 1828 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1829 | S-Type=8| Sub-length=N | msg-type | id (octet 0) | 1830 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1831 | transaction-id (octets 1-2) | | 1832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1833 | | 1834 . DHCPv6 options . 1835 . (variable number and length) . 1836 | | 1837 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1839 Figure 16: DHCPv6 Message Sub-option 1841 o Sub-Type is set to 8. If multiple instances appear in OMNI 1842 options of the same message the first is processed and all others 1843 are ignored. 1845 o Sub-Length is set to N (from 4 to 2034) that encodes the number of 1846 Sub-Option Data octets that follow. The 'msg-type' and 1847 'transaction-id' fields are always present; hence, the length of 1848 the DHCPv6 options is restricted to 2030 octets. 1850 o 'msg-type' and 'transaction-id' are coded according to Section 8 1851 of [RFC8415]. 1853 o A set of DHCPv6 options coded according to Section 21 of [RFC8415] 1854 follows. 1856 11.1.10. Host Identity Protocol (HIP) Message 1858 The Host Identity Protocol (HIP) Message sub-option may be included 1859 in the OMNI options of RS messages sent by MNs and RA messages 1860 returned by ARs. ARs that act as proxys authenticate and remove HIP 1861 messages in RS messages they forward from a MN to an MSE. ARs that 1862 act as proxys insert and sign HIP messages in the RA messages they 1863 forward from an MSE to a MN. 1865 0 1 2 3 1866 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 1867 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1868 | S-Type=9| Sub-length=N |0| Packet Type |Version| RES.|1| 1869 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1870 | Checksum | Controls | 1871 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1872 | Sender's Host Identity Tag (HIT) | 1873 | | 1874 | | 1875 | | 1876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1877 | Receiver's Host Identity Tag (HIT) | 1878 | | 1879 | | 1880 | | 1881 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1882 | | 1883 / HIP Parameters / 1884 / / 1885 | | 1886 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1888 Figure 17: HIP Message Sub-option 1890 o Sub-Type is set to 9. If multiple instances appear in OMNI 1891 options of the same message the first is processed and all others 1892 are ignored. 1894 o Sub-Length is set to N, i.e., the length of the option in octets 1895 beginning immediately following the Sub-Length field and extending 1896 to the end of the HIP parameters. The length of the entire HIP 1897 message is therefore restricted to 2034 octets. 1899 o The HIP message is coded exactly as specified in Section 5 of 1900 [RFC7401], except that the OMNI "Sub-Type" and "Sub-Length" fields 1901 replace the first 2 octets of the HIP message header (i.e., the 1902 Next Header and Header Length fields). 1904 11.1.11. Node Identification 1906 0 1 2 3 1907 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 1908 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1909 |S-Type=10| Sub-length=N | ID-Type | ~ 1910 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1911 ~ Node Identification Value (N-1 octets) ~ 1912 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1914 Figure 18: Node Identification 1916 o Sub-Type is set to 10. If multiple instances appear in OMNI 1917 options of the same IPv6 ND message the first instance of a 1918 specific ID-Type is processed and all other instances of the same 1919 ID-Type are ignored. (Note therefore that it is possible for a 1920 single IPv6 ND message to convey multiple Node Identifications - 1921 each having a different ID-Type.) 1923 o Sub-Length is set to N (from 1 to 2034) that encodes the number of 1924 Sub-Option Data octets that follow. The ID-Type field is always 1925 present; hence, the maximum Node Identification Value length is 1926 2033 octets. 1928 o ID-Type is a 1 octet field that encodes the type of the Node 1929 Identification Value. The following ID-Type values are currently 1930 defined: 1932 * 0 - Universally Unique IDentifier (UUID) [RFC4122]. Indicates 1933 that Node Identification Value contains a 16 octet UUID. 1935 * 1 - Host Identity Tag (HIT) [RFC7401]. Indicates that Node 1936 Identification Value contains a 16 octet HIT. 1938 * 2 - Hierarchical HIT (HHIT) [I-D.ietf-drip-rid]. Indicates 1939 that Node Identification Value contains a 16 octet HHIT. 1941 * 3 - Network Access Identifier (NAI) [RFC7542]. Indicates that 1942 Node Identification Value contains an N-1 octet NAI. 1944 * 4 - Fully-Qualified Domain Name (FQDN) [RFC1035]. Indicates 1945 that Node Identification Value contains an N-1 octet FQDN. 1947 * 5 - 252 - Unassigned. 1949 * 253-254 - Reserved for experimentation, as recommended in 1950 [RFC3692]. 1952 * 255 - reserved by IANA. 1954 o Node Identification Value is an (N - 1) octet field encoded 1955 according to the appropriate the "ID-Type" reference above. 1957 When a Node Identification Value is needed for DHCPv6 messaging 1958 purposes, it is encoded as a DHCP Unique IDentifier (DUID) using the 1959 "DUID-EN for OMNI" format with enterprise number 45282 (see: 1960 Section 23) as shown in Figure 19: 1962 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 1963 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1964 | DUID-Type (2) | EN (high bits == 0) | 1965 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1966 | EN (low bits = 45282) | ID-Type | | 1967 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1968 . Node Identification Value . 1969 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1971 Figure 19: DUID-EN for OMNI Format 1973 In this format, the ID-Type and Node Identification Value fields are 1974 coded exactly as in Figure 18 following the 6 octet DUID-EN header, 1975 and the entire "DUID-EN for OMNI" is included in a DHCPv6 message per 1976 [RFC8415]. 1978 11.1.12. Sub-Type Extension 1980 Since the Sub-Type field is only 5 bits in length, future 1981 specifications of major protocol functions may exhaust the remaining 1982 Sub-Type values available for assignment. This document therefore 1983 defines Sub-Type 30 as an "extension", meaning that the actual sub- 1984 option type is determined by examining a 1 octet "Extension-Type" 1985 field immediately following the Sub-Length field. The Sub-Type 1986 Extension is formatted as shown in Figure 20: 1988 0 1 2 3 1989 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 1990 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1991 |S-Type=30| Sub-length=N | Extension-Type| ~ 1992 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1993 ~ ~ 1994 ~ Extension-Type Body ~ 1995 ~ ~ 1996 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1998 Figure 20: Sub-Type Extension 2000 o Sub-Type is set to 30. If multiple instances appear in OMNI 2001 options of the same message all are processed, where each 2002 individual extension defines its own policy for processing 2003 multiple of that type. 2005 o Sub-Length is set to N (from 1 to 2034) that encodes the number of 2006 Sub-Option Data octets that follow. The Extension-Type field is 2007 always present; hence, the maximum Extension-Type Body length is 2008 2033 octets. 2010 o Extension-Type contains a 1 octet Sub-Type Extension value between 2011 0 and 255. 2013 o Extension-Type Body contains an N-1 octet block with format 2014 defined by the given extension specification. 2016 Extension-Type values 2 through 252 are available for assignment by 2017 future specifications, which must also define the format of the 2018 Extension-Type Body and its processing rules. Extension-Type values 2019 253 and 254 are reserved for experimentation, as recommended in 2020 [RFC3692], and value 255 is reserved by IANA. Extension-Type values 2021 0 and 1 are defined in the following subsections: 2023 11.1.12.1. RFC4380 UDP/IP Header Option 2025 0 1 2 3 2026 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 2027 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2028 |S-Type=30| Sub-length=N | Ext-Type=0 | Header Type | 2029 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2030 ~ Header Option Value ~ 2031 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2033 Figure 21: RFC4380 UDP/IP Header Option (Extension-Type 0) 2035 o Sub-Type is set to 30. 2037 o Sub-Length is set to N (from 2 to 2034) that encodes the number of 2038 Sub-Option Data octets that follow. The Extension-Type and Header 2039 Type fields are always present; hence, the maximum-length Header 2040 Option Value is 2032 octets. 2042 o Extension-Type is set to 0. Each instance encodes exactly one 2043 header option per Section 5.1.1 of [RFC4380], with the leading '0' 2044 octet omitted and the following octet coded as Header Type. If 2045 multiple instances of the same Header Type appear in OMNI options 2046 of the same message the first instance is processed and all others 2047 are ignored. 2049 o Header Type and Header Option Value are coded exactly as specified 2050 in Section 5.1.1 of [RFC4380]; the following types are currently 2051 defined: 2053 * 0 - Origin Indication (IPv4) - value coded per Section 5.1.1 of 2054 [RFC4380]. 2056 * 1 - Authentication Encapsulation - value coded per 2057 Section 5.1.1 of [RFC4380]. 2059 * 2 - Origin Indication (IPv6) - value coded per Section 5.1.1 of 2060 [RFC4380], except that the address is a 16-octet IPv6 address 2061 instead of a 4-octet IPv4 address. 2063 o Header Type values 3 through 252 are available for assignment by 2064 future specifications, which must also define the format of the 2065 Header Option Value and its processing rules. Header Type values 2066 253 and 254 are reserved for experimentation, as recommended in 2067 [RFC3692], and value 255 is Reserved by IANA. 2069 11.1.12.2. RFC6081 UDP/IP Trailer Option 2071 0 1 2 3 2072 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 2073 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2074 |S-Type=30| Sub-length=N | Ext-Type=1 | Trailer Type | 2075 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2076 ~ Trailer Option Value ~ 2077 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2079 Figure 22: RFC6081 UDP/IP Trailer Option (Extension-Type 1) 2081 o Sub-Type is set to 30. 2083 o Sub-Length is set to N (from 2 to 2034) that encodes the number of 2084 Sub-Option Data octets that follow. The Extension-Type and 2085 Trailer Type fields are always present; hence, the maximum-length 2086 Trailer Option Value is 2032 octets. 2088 o Extension-Type is set to 1. Each instance encodes exactly one 2089 trailer option per Section 4 of [RFC6081]. If multiple instances 2090 of the same trailer type appear in OMNI options of the same 2091 message the first instance is processed and all others ignored. 2093 o Trailer Type and Trailer Option Value are coded exactly as 2094 specified in Section 4 of [RFC6081]; the following Trailer Types 2095 are currently defined: 2097 * 0 - Unassigned 2099 * 1 - Nonce Trailer - value coded per Section 4.2 of [RFC6081]. 2101 * 2 - Unassigned 2103 * 3 - Alternate Address Trailer (IPv4) - value coded per 2104 Section 4.3 of [RFC6081]. 2106 * 4 - Neighbor Discovery Option Trailer - value coded per 2107 Section 4.4 of [RFC6081]. 2109 * 5 - Random Port Trailer - value coded per Section 4.5 of 2110 [RFC6081]. 2112 * 6 - Alternate Address Trailer (IPv6) - value coded per 2113 Section 4.3 of [RFC6081], except that each address is a 2114 16-octet IPv6 address instead of a 4-octet IPv4 address. 2116 o Trailer Type values 7 through 252 are available for assignment by 2117 future specifications, which must also define the format of the 2118 Trailer Option Value and its processing rules. Trailer Type 2119 values 253 and 254 are reserved for experimentation, as 2120 recommended in [RFC3692], and value 255 is Reserved by IANA. 2122 12. Address Mapping - Multicast 2124 The multicast address mapping of the native underlying interface 2125 applies. The mobile router on board the MN also serves as an IGMP/ 2126 MLD Proxy for its EUNs and/or hosted applications per [RFC4605] while 2127 using the L2 address of the AR as the L2 address for all multicast 2128 packets. 2130 The MN uses Multicast Listener Discovery (MLDv2) [RFC3810] to 2131 coordinate with the AR, and *NET L2 elements use MLD snooping 2132 [RFC4541]. 2134 13. Multilink Conceptual Sending Algorithm 2136 The MN's IPv6 layer selects the outbound OMNI interface according to 2137 SBM considerations when forwarding data packets from local or EUN 2138 applications to external correspondents. Each OMNI interface 2139 maintains a neighbor cache the same as for any IPv6 interface, but 2140 with additional state for multilink coordination. Each OMNI 2141 interface maintains default routes via ARs discovered as discussed in 2142 Section 14, and may configure more-specific routes discovered through 2143 means outside the scope of this specification. 2145 After a packet enters the OMNI interface, one or more outbound 2146 underlying interfaces are selected based on PBM traffic attributes, 2147 and one or more neighbor underlying interfaces are selected based on 2148 the receipt of Interface Attributes sub-options in IPv6 ND messages 2149 (see: Figure 9). Underlying interface selection for the nodes own 2150 local interfaces are based on attributes such as DSCP, application 2151 port number, cost, performance, message size, etc. OMNI interface 2152 multilink selections could also be configured to perform replication 2153 across multiple underlying interfaces for increased reliability at 2154 the expense of packet duplication. The set of all Interface 2155 Attributes received in IPv6 ND messages determines the multilink 2156 forwarding profile for selecting the neighbor's underlying 2157 interfaces. 2159 When the OMNI interface sends a packet over a selected outbound 2160 underlying interface, the OAL includes or omits a mid-layer 2161 encapsulation header as necessary as discussed in Section 5 and as 2162 determined by the L2 address information received in Interface 2163 Attributes. The OAL also performs encapsulation when the nearest AR 2164 is located multiple hops away as discussed in Section 14.1. (Note 2165 that the OAL MAY employ packing when multiple packets are available 2166 for forwarding to the same destination.) 2168 OMNI interface multilink service designers MUST observe the BCP 2169 guidance in Section 15 [RFC3819] in terms of implications for 2170 reordering when packets from the same flow may be spread across 2171 multiple underlying interfaces having diverse properties. 2173 13.1. Multiple OMNI Interfaces 2175 MNs may connect to multiple independent OMNI links concurrently in 2176 support of SBM. Each OMNI interface is distinguished by its Anycast 2177 ULA (e.g., [ULA]:0002::, [ULA]:1000::, [ULA]:7345::, etc.). The MN 2178 configures a separate OMNI interface for each link so that multiple 2179 interfaces (e.g., omni0, omni1, omni2, etc.) are exposed to the IPv6 2180 layer. A different Anycast ULA is assigned to each interface, and 2181 the MN injects the service prefixes for the OMNI link instances into 2182 the EUN routing system. 2184 Applications in EUNs can use Segment Routing to select the desired 2185 OMNI interface based on SBM considerations. The Anycast ULA is 2186 written into the IPv6 destination address, and the actual destination 2187 (along with any additional intermediate hops) is written into the 2188 Segment Routing Header. Standard IP routing directs the packets to 2189 the MN's mobile router entity, and the Anycast ULA identifies the 2190 OMNI interface to be used for transmission to the next hop. When the 2191 MN receives the message, it replaces the IPv6 destination address 2192 with the next hop found in the routing header and transmits the 2193 message over the OMNI interface identified by the Anycast ULA. 2195 Multiple distinct OMNI links can therefore be used to support fault 2196 tolerance, load balancing, reliability, etc. The architectural model 2197 is similar to Layer 2 Virtual Local Area Networks (VLANs). 2199 13.2. MN<->AR Traffic Loop Prevention 2201 After an AR has registered an MNP for a MN (see: Section 14), the AR 2202 will forward packets destined to an address within the MNP to the MN. 2203 The MN will under normal circumstances then forward the packet to the 2204 correct destination within its internal networks. 2206 If at some later time the MN loses state (e.g., after a reboot), it 2207 may begin returning packets destined to an MNP address to the AR as 2208 its default router. The AR therefore must drop any packets 2209 originating from the MN and destined to an address within the MN's 2210 registered MNP. To do so, the AR institutes the following check: 2212 o if the IP destination address belongs to a neighbor on the same 2213 OMNI interface, and if the link-layer source address is the same 2214 as one of the neighbor's link-layer addresses, drop the packet. 2216 14. Router Discovery and Prefix Registration 2218 MNs interface with the MS by sending RS messages with OMNI options 2219 under the assumption that one or more AR on the *NET will process the 2220 message and respond. The MN then configures default routes for the 2221 OMNI interface via the discovered ARs as the next hop. The manner in 2222 which the *NET ensures AR coordination is link-specific and outside 2223 the scope of this document (however, considerations for *NETs that do 2224 not provide ARs that recognize the OMNI option are discussed in 2225 Section 19). 2227 For each underlying interface, the MN sends an RS message with an 2228 OMNI option to coordinate with MSEs identified by MSID values. 2230 Example MSID discovery methods are given in [RFC5214] and include 2231 data link login parameters, name service lookups, static 2232 configuration, a static "hosts" file, etc. The MN can also send an 2233 RS with an MS-Register sub-option that includes the Anycast MSID 2234 value '0', i.e., instead of or in addition to any non-zero MSIDs. 2235 When the AR receives an RS with a MSID '0', it selects a nearby MSE 2236 (which may be itself) and returns an RA with the selected MSID in an 2237 MS-Register sub-option. The AR selects only a single wildcard MSE 2238 (i.e., even if the RS MS-Register sub-option included multiple '0' 2239 MSIDs) while also soliciting the MSEs corresponding to any non-zero 2240 MSIDs. 2242 MNs configure OMNI interfaces that observe the properties discussed 2243 in the previous section. The OMNI interface and its underlying 2244 interfaces are said to be in either the "UP" or "DOWN" state 2245 according to administrative actions in conjunction with the interface 2246 connectivity status. An OMNI interface transitions to UP or DOWN 2247 through administrative action and/or through state transitions of the 2248 underlying interfaces. When a first underlying interface transitions 2249 to UP, the OMNI interface also transitions to UP. When all 2250 underlying interfaces transition to DOWN, the OMNI interface also 2251 transitions to DOWN. 2253 When an OMNI interface transitions to UP, the MN sends RS messages to 2254 register its MNP and an initial set of underlying interfaces that are 2255 also UP. The MN sends additional RS messages to refresh lifetimes 2256 and to register/deregister underlying interfaces as they transition 2257 to UP or DOWN. The MN's OMNI interface sends initial RS messages 2258 over an UP underlying interface with its MNP-LLA as the source and 2259 with destination set to link-scoped All-Routers multicast (ff02::2) 2260 [RFC4291]. The OMNI interface includes an OMNI option per Section 11 2261 with a Preflen assertion, Interface Attributes appropriate for 2262 underlying interfaces, MS-Register/Release sub-options containing 2263 MSID values, and with any other necessary OMNI sub-options (e.g., a 2264 Node Identification sub-option as an identity for the MN). The OMNI 2265 interface then sets the S/T-omIndex field to the index of the 2266 underlying interface over which the RS message is sent. The OMNI 2267 interface then sends the RS over the underlying interface, using OAL 2268 encapsulation and fragmentation if necessary. If OAL encapsulation 2269 is used, the OMNI interface sets the OAL source address to the ULA 2270 corresponding to the RS source and sets the OAL destination to site- 2271 scoped All-Routers multicast (ff05::2). 2273 ARs process IPv6 ND messages with OMNI options and act as an MSE 2274 themselves and/or as a proxy for other MSEs. ARs receive RS messages 2275 (while performing OAL reassembly if necessary) and create a neighbor 2276 cache entry for the MN, then coordinate with any MSEs named in the 2277 Register/Release lists in a manner outside the scope of this 2278 document. When an MSE processes the OMNI information, it first 2279 validates the prefix registration information then injects/withdraws 2280 the MNP in the routing/mapping system and caches/discards the new 2281 Preflen, MNP and Interface Attributes. The MSE then informs the AR 2282 of registration success/failure, and the AR returns an RA message to 2283 the MN with an OMNI option per Section 11. 2285 The AR's OMNI interface returns the RA message via the same 2286 underlying interface of the MN over which the RS was received, and 2287 with destination address set to the MNP-LLA (i.e., unicast), with 2288 source address set to its own LLA, and with an OMNI option with S/ 2289 T-omIndex set to the value included in the RS. The OMNI option also 2290 includes a Preflen confirmation, Interface Attributes, MS-Register/ 2291 Release and any other necessary OMNI sub-options (e.g., a Node 2292 Identification sub-option as an identity for the AR). The RA also 2293 includes any information for the link, including RA Cur Hop Limit, M 2294 and O flags, Router Lifetime, Reachable Time and Retrans Timer 2295 values, and includes any necessary options such as: 2297 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 2299 o RIOs [RFC4191] with more-specific routes. 2301 o an MTU option that specifies the maximum acceptable packet size 2302 for this underlying interface. 2304 The OMNI interface then sends the RA, using OAL encapsulation and 2305 fragmentation if necessary. If OAL encapsulation is used, the OMNI 2306 interface sets the OAL source address to the ULA corresponding to the 2307 RA source and sets the OAL destination to the ULA corresponding to 2308 the RA destination. The AR MAY also send periodic and/or event- 2309 driven unsolicited RA messages per [RFC4861]. In that case, the S/ 2310 T-omIndex field in the OMNI option of the unsolicited RA message 2311 identifies the target underlying interface of the destination MN. 2313 The AR can combine the information from multiple MSEs into one or 2314 more "aggregate" RAs sent to the MN in order conserve *NET bandwidth. 2315 Each aggregate RA includes an OMNI option with MS-Register/Release 2316 sub-options with the MSEs represented by the aggregate. If an 2317 aggregate is sent, the RA message contents must consistently 2318 represent the combined information advertised by all represented 2319 MSEs. Note that since the AR uses its own ADM-LLA as the RA source 2320 address, the MN determines the addresses of the represented MSEs by 2321 examining the MS-Register/Release OMNI sub-options. 2323 When the MN receives the RA message, it creates an OMNI interface 2324 neighbor cache entry for each MSID that has confirmed MNP 2325 registration via the L2 address of this AR. If the MN connects to 2326 multiple *NETs, it records the additional L2 AR addresses in each 2327 MSID neighbor cache entry (i.e., as multilink neighbors). The MN 2328 then configures a default route via the MSE that returned the RA 2329 message, and assigns the Subnet Router Anycast address corresponding 2330 to the MNP (e.g., 2001:db8:1:2::) to the OMNI interface. The MN then 2331 manages its underlying interfaces according to their states as 2332 follows: 2334 o When an underlying interface transitions to UP, the MN sends an RS 2335 over the underlying interface with an OMNI option. The OMNI 2336 option contains at least one Interface Attribute sub-option with 2337 values specific to this underlying interface, and may contain 2338 additional Interface Attributes specific to other underlying 2339 interfaces. The option also includes any MS-Register/Release sub- 2340 options. 2342 o When an underlying interface transitions to DOWN, the MN sends an 2343 RS or unsolicited NA message over any UP underlying interface with 2344 an OMNI option containing an Interface Attribute sub-option for 2345 the DOWN underlying interface with Link set to '0'. The MN sends 2346 an RS when an acknowledgement is required, or an unsolicited NA 2347 when reliability is not thought to be a concern (e.g., if 2348 redundant transmissions are sent on multiple underlying 2349 interfaces). 2351 o When the Router Lifetime for a specific AR nears expiration, the 2352 MN sends an RS over the underlying interface to receive a fresh 2353 RA. If no RA is received, the MN can send RS messages to an 2354 alternate MSID in case the current MSID has failed. If no RS 2355 messages are received even after trying to contact alternate 2356 MSIDs, the MN marks the underlying interface as DOWN. 2358 o When a MN wishes to release from one or more current MSIDs, it 2359 sends an RS or unsolicited NA message over any UP underlying 2360 interfaces with an OMNI option with a Release MSID. Each MSID 2361 then withdraws the MNP from the routing/mapping system and informs 2362 the AR that the release was successful. 2364 o When all of a MNs underlying interfaces have transitioned to DOWN 2365 (or if the prefix registration lifetime expires), any associated 2366 MSEs withdraw the MNP the same as if they had received a message 2367 with a release indication. 2369 The MN is responsible for retrying each RS exchange up to 2370 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 2371 seconds until an RA is received. If no RA is received over an UP 2372 underlying interface (i.e., even after attempting to contact 2373 alternate MSEs), the MN declares this underlying interface as DOWN. 2375 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 2376 Therefore, when the IPv6 layer sends an RS message the OMNI interface 2377 returns an internally-generated RA message as though the message 2378 originated from an IPv6 router. The internally-generated RA message 2379 contains configuration information that is consistent with the 2380 information received from the RAs generated by the MS. Whether the 2381 OMNI interface IPv6 ND messaging process is initiated from the 2382 receipt of an RS message from the IPv6 layer is an implementation 2383 matter. Some implementations may elect to defer the IPv6 ND 2384 messaging process until an RS is received from the IPv6 layer, while 2385 others may elect to initiate the process proactively. Still other 2386 deployments may elect to administratively disable the ordinary RS/RA 2387 messaging used by the IPv6 layer over the OMNI interface, since they 2388 are not required to drive the internal RS/RA processing. (Note that 2389 this same logic applies to IPv4 implementations that employ ICMP- 2390 based Router Discovery per [RFC1256].) 2392 Note: The Router Lifetime value in RA messages indicates the time 2393 before which the MN must send another RS message over this underlying 2394 interface (e.g., 600 seconds), however that timescale may be 2395 significantly longer than the lifetime the MS has committed to retain 2396 the prefix registration (e.g., REACHABLETIME seconds). ARs are 2397 therefore responsible for keeping MS state alive on a shorter 2398 timescale than the MN is required to do on its own behalf. 2400 Note: On multicast-capable underlying interfaces, MNs should send 2401 periodic unsolicited multicast NA messages and ARs should send 2402 periodic unsolicited multicast RA messages as "beacons" that can be 2403 heard by other nodes on the link. If a node fails to receive a 2404 beacon after a timeout value specific to the link, it can initiate a 2405 unicast exchange to test reachability. 2407 Note: if an AR acting as a proxy forwards a MN's RS message to 2408 another node acting as an MSE using UDP/IP encapsulation, it must use 2409 a distinct UDP source port number for each MN. This allows the MSE 2410 to distinguish different MNs behind the same AR at the link-layer, 2411 whereas the link-layer addresses would otherwise be 2412 indistinguishable. 2414 Note: when an AR acting as an MSE returns an RA to an INET Client, it 2415 includes an OMNI option with an Interface Attributes sub-option with 2416 omIndex set to 0 and with SRT, FMT, LHS and L2ADDR information for 2417 its INET interface. This provides the Client with partition prefix 2418 context regarding the local OMNI link segment. 2420 14.1. Router Discovery in IP Multihop and IPv4-Only Networks 2422 On some *NETs, a MN may be located multiple IP hops away from the 2423 nearest AR. Forwarding through IP multihop *NETs is conducted 2424 through the application of a routing protocol (e.g., a MANET/VANET 2425 routing protocol over omni-directional wireless interfaces, an inter- 2426 domain routing protocol in an enterprise network, etc.). These *NETs 2427 could be either IPv6-enabled or IPv4-only, while IPv4-only *NETs 2428 could be either multicast-capable or unicast-only (note that for 2429 IPv4-only *NETs the following procedures apply for both single-hop 2430 and multihop cases). 2432 A MN located potentially multiple *NET hops away from the nearest AR 2433 prepares an RS message with source address set to its MNP-LLA (or to 2434 the unspecified address (::) if it does not yet have an MNP-LLA), and 2435 with destination set to link-scoped All-Routers multicast the same as 2436 discussed above. If OAL encapsulation and fragmentation are 2437 necessary, the OMNI interface sets the OAL source address to the ULA 2438 corresponding to the RS source (or to a Temporary ULA if the RS 2439 source was the unspecified address (::)) and sets the OAL destination 2440 to site-scoped All-Routers multicast (ff05::2). For IPv6-enabled 2441 *NETs, the MN then encapsulates the message in UDP/IPv6 headers with 2442 source address set to the underlying interface address (or to the ULA 2443 that would be used for OAL encapsulation if the underlying interface 2444 does not yet have an address) and sets the destination to either a 2445 unicast or anycast address of an AR. For IPv4-only *NETs, the MN 2446 instead encapsulates the RS message in an IPv4 header with source 2447 address set to the IPv4 address of the underlying interface and with 2448 destination address set to either the unicast IPv4 address of an AR 2449 [RFC5214] or an IPv4 anycast address reserved for OMNI. The MN then 2450 sends the encapsulated RS message via the *NET interface, where it 2451 will be forwarded by zero or more intermediate *NET hops. 2453 When an intermediate *NET hop that participates in the routing 2454 protocol receives the encapsulated RS, it forwards the message 2455 according to its routing tables (note that an intermediate node could 2456 be a fixed infrastructure element or another MN). This process 2457 repeats iteratively until the RS message is received by a penultimate 2458 *NET hop within single-hop communications range of an AR, which 2459 forwards the message to the AR. 2461 When the AR receives the message, it decapsulates the RS (while 2462 performing OAL reassembly, if necessary) and coordinates with the MS 2463 the same as for an ordinary link-local RS, since the inner Hop Limit 2464 will not have been decremented by the multihop forwarding process. 2465 The AR then prepares an RA message with source address set to its own 2466 ADM-LLA and destination address set to the LLA of the original MN. 2467 The AR then performs OAL encapsulation and fragmentation if 2468 necessary, with OAL source set to its own ADM-ULA and destination set 2469 to the ULA corresponding to the RA source. The AR then encapsulates 2470 the message in an IPv4/IPv6 header with source address set to its own 2471 IPv4/ULA address and with destination set to the encapsulation source 2472 of the RS. 2474 The AR then forwards the message to an *NET node within 2475 communications range, which forwards the message according to its 2476 routing tables to an intermediate node. The multihop forwarding 2477 process within the *NET continues repetitively until the message is 2478 delivered to the original MN, which decapsulates the message and 2479 performs autoconfiguration the same as if it had received the RA 2480 directly from the AR as an on-link neighbor. 2482 Note: An alternate approach to multihop forwarding via IPv6 2483 encapsulation would be for the MN and AR to statelessly translate the 2484 IPv6 LLAs into ULAs and forward the RS/RA messages without 2485 encapsulation. This would violate the [RFC4861] requirement that 2486 certain IPv6 ND messages must use link-local addresses and must not 2487 be accepted if received with Hop Limit less than 255. This document 2488 therefore mandates encapsulation since the overhead is nominal 2489 considering the infrequent nature and small size of IPv6 ND messages. 2490 Future documents may consider encapsulation avoidance through 2491 translation while updating [RFC4861]. 2493 Note: An alternate approach to multihop forwarding via IPv4 2494 encapsulation would be to employ IPv6/IPv4 protocol translation. 2495 However, for IPv6 ND messages the LLAs would be truncated due to 2496 translation and the OMNI Router and Prefix Discovery services would 2497 not be able to function. The use of IPv4 encapsulation is therefore 2498 indicated. 2500 Note: An IPv4 anycast address for OMNI in IPv4 networks could be part 2501 of a new IPv4 /24 prefix allocation, but this may be difficult to 2502 obtain given IPv4 address exhaustion. An alternative would be to re- 2503 purpose the prefix 192.88.99.0 which has been set aside from its 2504 former use by [RFC7526]. 2506 14.2. MS-Register and MS-Release List Processing 2508 OMNI links maintain a constant value "MAX_MSID" selected to provide 2509 MNs with an acceptable level of MSE redundancy while minimizing 2510 control message amplification. It is RECOMMENDED that MAX_MSID be 2511 set to the default value 5; if a different value is chosen, it should 2512 be set uniformly by all nodes on the OMNI link. 2514 When a MN sends an RS message with an OMNI option via an underlying 2515 interface to an AR, the MN must convey its knowledge of its 2516 currently-associated MSEs. Initially, the MN will have no associated 2517 MSEs and should therefore include an MS-Register sub-option with the 2518 single "anycast" MSID value 0 which requests the AR to select and 2519 assign an MSE. The AR will then return an RA message with source 2520 address set to the ADM-LLA of the selected MSE. 2522 As the MN activates additional underlying interfaces, it can 2523 optionally include an MS-Register sub-option with MSID value 0, or 2524 with non-zero MSIDs for MSEs discovered from previous RS/RA 2525 exchanges. The MN will thus eventually begin to learn and manage its 2526 currently active set of MSEs, and can register with new MSEs or 2527 release from former MSEs with each successive RS/RA exchange. As the 2528 MN's MSE constituency grows, it alone is responsible for including or 2529 omitting MSIDs in the MS-Register/Release lists it sends in RS 2530 messages. The inclusion or omission of MSIDs determines the MN's 2531 interface to the MS and defines the manner in which MSEs will 2532 respond. The only limiting factor is that the MN should include no 2533 more than MAX_MSID values in each list per each IPv6 ND message, and 2534 should avoid duplication of entries in each list unless it wants to 2535 increase likelihood of control message delivery. 2537 When an AR receives an RS message sent by a MN with an OMNI option, 2538 the option will contain zero or more MS-Register and MS-Release sub- 2539 options containing MSIDs. After processing the OMNI option, the AR 2540 will have a list of zero or more MS-Register MSIDs and a list of zero 2541 or more of MS-Release MSIDs. The AR then processes the lists as 2542 follows: 2544 o For each list, retain the first MAX_MSID values in the list and 2545 discard any additional MSIDs (i.e., even if there are duplicates 2546 within a list). 2548 o Next, for each MSID in the MS-Register list, remove all matching 2549 MSIDs from the MS-Release list. 2551 o Next, proceed according to whether the AR's own MSID or the value 2552 0 appears in the MS-Register list as follows: 2554 * If yes, send an RA message directly back to the MN and send a 2555 proxy copy of the RS message to each additional MSID in the MS- 2556 Register list with the MS-Register/Release lists omitted. 2557 Then, send an unsolicited NA (uNA) message to each MSID in the 2558 MS-Release list with the MS-Register/Release lists omitted and 2559 with an OMNI option with S/T-omIndex set to 0. 2561 * If no, send a proxy copy of the RS message to each additional 2562 MSID in the MS-Register list with the MS-Register list omitted. 2564 For the first MSID, include the original MS-Release list; for 2565 all other MSIDs, omit the MS-Release list. 2567 Each proxy copy of the RS message will include an OMNI option and OAL 2568 encapsulation header with the ADM-ULA of the AR as the source and the 2569 ADM-ULA of the Register MSE as the destination. When the Register 2570 MSE receives the proxy RS message, if the message includes an MS- 2571 Release list the MSE sends a uNA message to each additional MSID in 2572 the Release list with an OMNI option with S/T-omIndex set to 0. The 2573 Register MSE then sends an RA message back to the (Proxy) AR wrapped 2574 in an OAL encapsulation header with source and destination addresses 2575 reversed, and with RA destination set to the MNP-LLA of the MN. When 2576 the AR receives this RA message, it sends a proxy copy of the RA to 2577 the MN. 2579 Each uNA message (whether sent by the first-hop AR or by a Register 2580 MSE) will include an OMNI option and an OAL encapsulation header with 2581 the ADM-ULA of the Register MSE as the source and the ADM-ULA of the 2582 Release MSE as the destination. The uNA informs the Release MSE that 2583 its previous relationship with the MN has been released and that the 2584 source of the uNA message is now registered. The Release MSE must 2585 then note that the subject MN of the uNA message is now "departed", 2586 and forward any subsequent packets destined to the MN to the Register 2587 MSE. 2589 Note that it is not an error for the MS-Register/Release lists to 2590 include duplicate entries. If duplicates occur within a list, the AR 2591 will generate multiple proxy RS and/or uNA messages - one for each 2592 copy of the duplicate entries. 2594 14.3. DHCPv6-based Prefix Registration 2596 When a MN is not pre-provisioned with an MNP-LLA (or, when the MN 2597 requires additional MNP delegations), it requests the MSE to select 2598 MNPs on its behalf and set up the correct routing state within the 2599 MS. The DHCPv6 service [RFC8415] supports this requirement. 2601 When an MN needs to have the MSE select MNPs, it sends an RS message 2602 with source set to the unspecified address (::) if it has no 2603 MNP_LLAs. If the MN requires only a single MNP delegation, it can 2604 then include a Node Identification sub-option in the OMNI option and 2605 set Preflen to the length of the desired MNP. If the MN requires 2606 multiple MNP delegations and/or more complex DHCPv6 services, it 2607 instead includes a DHCPv6 Message sub-option containing a Client 2608 Identifier, one or more IA_PD options and a Rapid Commit option then 2609 sets the 'msg-type' field to "Solicit", and includes a 3 octet 2610 'transaction-id'. The MN then sets the RS destination to All-Routers 2611 multicast and sends the message using OAL encapsulation and 2612 fragmentation if necessary as discussed above. 2614 When the MSE receives the RS message, it performs OAL reassembly if 2615 necessary. Next, if the RS source is the unspecified address (::) 2616 and/or the OMNI option includes a DHCPv6 message sub-option, the MSE 2617 acts as a "Proxy DHCPv6 Client" in a message exchange with the 2618 locally-resident DHCPv6 server. If the RS did not contain a DHCPv6 2619 message sub-option, the MSE generates a DHCPv6 Solicit message on 2620 behalf of the MN using an IA_PD option with the prefix length set to 2621 the OMNI header Preflen value and with a Client Identifier formed 2622 from the OMNI option Node Identification sub-option; otherwise, the 2623 MSE uses the DHCPv6 Solicit message contained in the OMNI option. 2624 The MSE then sends the DHCPv6 message to the DHCPv6 Server, which 2625 delegates MNPs and returns a DHCPv6 Reply message with PD parameters. 2626 (If the MSE wishes to defer creation of MN state until the DHCPv6 2627 Reply is received, it can instead act as a Lightweight DHCPv6 Relay 2628 Agent per [RFC6221] by encapsulating the DHCPv6 message in a Relay- 2629 forward/reply exchange with Relay Message and Interface ID options. 2630 In the process, the MSE packs any state information needed to return 2631 an RA to the MN in the Relay-forward Interface ID option so that the 2632 information will be echoed back in the Relay-reply.) 2634 When the MSE receives the DHCPv6 Reply, it adds routes to the routing 2635 system and creates MNP-LLAs based on the delegated MNPs. The MSE 2636 then sends an RA back to the MN with the DHCPv6 Reply message 2637 included in an OMNI DHCPv6 message sub-option if and only if the RS 2638 message had included an explicit DHCPv6 Solicit. If the RS message 2639 source was the unspecified address (::), the MSE includes one of the 2640 (newly-created) MNP-LLAs as the RA destination address and sets the 2641 OMNI option Preflen accordingly; otherwise, the MSE includes the RS 2642 source address as the RA destination address. The MSE then sets the 2643 RA source address to its own ADM-LLA then performs OAL encapsulation 2644 and fragmentation if necessary and sends the RA to the MN. When the 2645 MN receives the RA, it reassembles and discards the OAL encapsulation 2646 if necessary, then creates a default route, assigns Subnet Router 2647 Anycast addresses and uses the RA destination address as its primary 2648 MNP-LLA. The MN will then use this primary MNP-LLA as the source 2649 address of any IPv6 ND messages it sends as long as it retains 2650 ownership of the MNP. 2652 Note: After a MN performs a DHCPv6-based prefix registration exchange 2653 with a first MSE, it would need to repeat the exchange with each 2654 additional MSE it registers with. In that case, the MN supplies the 2655 MNP delegation information received from the first MSE when it 2656 engages the additional MSEs. 2658 15. Secure Redirection 2660 If the *NET link model is multiple access, the AR is responsible for 2661 assuring that address duplication cannot corrupt the neighbor caches 2662 of other nodes on the link. When the MN sends an RS message on a 2663 multiple access *NET link, the AR verifies that the MN is authorized 2664 to use the address and returns an RA with a non-zero Router Lifetime 2665 only if the MN is authorized. 2667 After verifying MN authorization and returning an RA, the AR MAY 2668 return IPv6 ND Redirect messages to direct MNs located on the same 2669 *NET link to exchange packets directly without transiting the AR. In 2670 that case, the MNs can exchange packets according to their unicast L2 2671 addresses discovered from the Redirect message instead of using the 2672 dogleg path through the AR. In some *NET links, however, such direct 2673 communications may be undesirable and continued use of the dogleg 2674 path through the AR may provide better performance. In that case, 2675 the AR can refrain from sending Redirects, and/or MNs can ignore 2676 them. 2678 16. AR and MSE Resilience 2680 *NETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 2681 [RFC5798] configurations so that service continuity is maintained 2682 even if one or more ARs fail. Using VRRP, the MN is unaware which of 2683 the (redundant) ARs is currently providing service, and any service 2684 discontinuity will be limited to the failover time supported by VRRP. 2685 Widely deployed public domain implementations of VRRP are available. 2687 MSEs SHOULD use high availability clustering services so that 2688 multiple redundant systems can provide coordinated response to 2689 failures. As with VRRP, widely deployed public domain 2690 implementations of high availability clustering services are 2691 available. Note that special-purpose and expensive dedicated 2692 hardware is not necessary, and public domain implementations can be 2693 used even between lightweight virtual machines in cloud deployments. 2695 17. Detecting and Responding to MSE Failures 2697 In environments where fast recovery from MSE failure is required, ARs 2698 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 2699 manner that parallels Bidirectional Forwarding Detection (BFD) 2700 [RFC5880] to track MSE reachability. ARs can then quickly detect and 2701 react to failures so that cached information is re-established 2702 through alternate paths. Proactive NUD control messaging is carried 2703 only over well-connected ground domain networks (i.e., and not low- 2704 end *NET links such as aeronautical radios) and can therefore be 2705 tuned for rapid response. 2707 ARs perform proactive NUD for MSEs for which there are currently 2708 active MNs on the *NET. If an MSE fails, ARs can quickly inform MNs 2709 of the outage by sending multicast RA messages on the *NET interface. 2710 The AR sends RA messages to MNs via the *NET interface with an OMNI 2711 option with a Release ID for the failed MSE, and with destination 2712 address set to All-Nodes multicast (ff02::1) [RFC4291]. 2714 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 2715 by small delays [RFC4861]. Any MNs on the *NET interface that have 2716 been using the (now defunct) MSE will receive the RA messages and 2717 associate with a new MSE. 2719 18. Transition Considerations 2721 When a MN connects to an *NET link for the first time, it sends an RS 2722 message with an OMNI option. If the first hop AR recognizes the 2723 option, it returns an RA with its ADM-LLA as the source, the MNP-LLA 2724 as the destination and with an OMNI option included. The MN then 2725 engages the AR according to the OMNI link model specified above. If 2726 the first hop AR is a legacy IPv6 router, however, it instead returns 2727 an RA message with no OMNI option and with a non-OMNI unicast source 2728 LLA as specified in [RFC4861]. In that case, the MN engages the *NET 2729 according to the legacy IPv6 link model and without the OMNI 2730 extensions specified in this document. 2732 If the *NET link model is multiple access, there must be assurance 2733 that address duplication cannot corrupt the neighbor caches of other 2734 nodes on the link. When the MN sends an RS message on a multiple 2735 access *NET link with an LLA source address and an OMNI option, ARs 2736 that recognize the option ensure that the MN is authorized to use the 2737 address and return an RA with a non-zero Router Lifetime only if the 2738 MN is authorized. ARs that do not recognize the option instead 2739 return an RA that makes no statement about the MN's authorization to 2740 use the source address. In that case, the MN should perform 2741 Duplicate Address Detection to ensure that it does not interfere with 2742 other nodes on the link. 2744 An alternative approach for multiple access *NET links to ensure 2745 isolation for MN / AR communications is through L2 address mappings 2746 as discussed in Appendix C. This arrangement imparts a (virtual) 2747 point-to-point link model over the (physical) multiple access link. 2749 19. OMNI Interfaces on Open Internetworks 2751 OMNI interfaces configured over IPv6-enabled underlying interfaces on 2752 an open Internetwork without an OMNI-aware first-hop AR receive RA 2753 messages that do not include an OMNI option, while OMNI interfaces 2754 configured over IPv4-only underlying interfaces do not receive any 2755 (IPv6) RA messages at all. OMNI interfaces that receive RA messages 2756 without an OMNI option configure addresses, on-link prefixes, etc. on 2757 the underlying interface that received the RA according to standard 2758 IPv6 ND and address resolution conventions [RFC4861] [RFC4862]. OMNI 2759 interfaces configured over IPv4-only underlying interfaces configure 2760 IPv4 address information on the underlying interfaces using 2761 mechanisms such as DHCPv4 [RFC2131]. 2763 OMNI interfaces configured over underlying interfaces that connect to 2764 an open Internetwork can apply security services such as VPNs to 2765 connect to an MSE, or can establish a direct link to an MSE through 2766 some other means (see Section 4). In environments where an explicit 2767 VPN or direct link may be impractical, OMNI interfaces can instead 2768 use UDP/IP encapsulation per [RFC6081][RFC4380] and HIP-based message 2769 authentication per [RFC7401]. 2771 OMNI interfaces that use UDP/IP encapsulation use the UDP service 2772 port number 8060 for 'aero' (see: Section 23), but do not include 2773 [RFC4380] header nor [RFC6081] trailer extension options (the 2774 interface instead includes them as OMNI sub-options when needed). 2775 OMNI interfaces therefore unconditionally drop any UDP encapsulated 2776 messages that include any such header/trailer extension options. 2777 Furthermore, OMNI UDP/IP encapsulation over IPv6 underlying 2778 interfaces uses the encapsulation format specified in [RFC4380] with 2779 the exception that IPv6 is used as the outer IP protocol instead of 2780 IPv4. 2782 For "Vehicle-to-Infrastructure (V2I)" coordination, the MN codes a 2783 HIP "Initiator" message in an OMNI option of an IPv6 RS message and 2784 the AR responds with a HIP "Responder" message coded in an OMNI 2785 option of an IPv6 RA message. HIP security services are applied per 2786 [RFC7401], using the RS/RA messages as simple "shipping containers" 2787 to convey the HIP parameters. In that case, a "two-message HIP 2788 exchange" through a single RS/RA exchange may be sufficient for 2789 mutual authentication. For "Vehicle-to-Vehicle (V2V)" coordination, 2790 two MNs can coordinate directly with one another with HIP "Initiator/ 2791 Responder" messages coded in OMNI options of IPv6 NS/NA messages. In 2792 that case, a four-message HIP exchange (i.e., two back-to-back NS/NA 2793 exchanges) may be necessary for the two MNs to attain mutual 2794 authentication. 2796 After establishing a VPN or preparing for UDP/IP encapsulation, OMNI 2797 interfaces send control plane messages to interface with the MS, 2798 including RS/RA messages used according to Section 14 and NS/NA 2799 messages used for route optimization and mobility (see: 2800 [I-D.templin-intarea-6706bis]). The control plane messages must be 2801 authenticated while data plane messages are delivered the same as for 2802 ordinary best-effort traffic with basic source address-based data 2803 origin verification. Data plane communications via OMNI interfaces 2804 that connect over open Internetworks without an explicit VPN should 2805 therefore employ transport- or higher-layer security to ensure 2806 integrity and/or confidentiality. 2808 OMNI interfaces configured over open Internetworks are often located 2809 behind NATs. The OMNI interface accommodates NAT traversal using 2810 UDP/IP encapsulation and the mechanisms discussed in 2811 [I-D.templin-intarea-6706bis]. To support NAT determination, ARs 2812 include an Origin Indication sub-option in RA messages sent in 2813 response to RS messages received from a Client via UDP/IP 2814 encapsulation. 2816 Note: Following the initial HIP Initiator/Responder exchange, OMNI 2817 interfaces configured over open Internetworks maintain HIP 2818 associations through the transmission of IPv6 ND messages that 2819 include OMNI options with HIP "Update" and "Notify" messages. OMNI 2820 interfaces use the HIP "Update" message when an acknowledgement is 2821 required, and use the "Notify" message in unacknowledged isolated 2822 IPv6 ND messages (e.g., unsolicited NAs). 2824 Note: ARs that act as proxys on an open Internetwork authenticate and 2825 remove HIP message OMNI sub-options from RSes they forward from a MN 2826 to an MSE, and insert and sign HIP message and Origin Indication sub- 2827 options in RAs they forward from an MSE to an MN. Conversely, ARs 2828 that act as proxys forward without processing any DHCPv6 information 2829 in RS/RA message exchanges between MNs and MSEs. The AR is therefore 2830 responsible for MN authentication while the MSE is responsible for 2831 registering/delegating MNPs. 2833 20. Time-Varying MNPs 2835 In some use cases, it is desirable, beneficial and efficient for the 2836 MN to receive a constant MNP that travels with the MN wherever it 2837 moves. For example, this would allow air traffic controllers to 2838 easily track aircraft, etc. In other cases, however (e.g., 2839 intelligent transportation systems), the MN may be willing to 2840 sacrifice a modicum of efficiency in order to have time-varying MNPs 2841 that can be changed every so often to defeat adversarial tracking. 2843 The prefix delegation services discussed in Section 14.3 allows OMNI 2844 MNs that desire time-varying MNPs to obtain short-lived prefixes to 2845 send RS messages with source set to the unspecified address (::) and/ 2846 or with an OMNI option with DHCPv6 Option sub-options. The MN would 2847 then be obligated to renumber its internal networks whenever its MNP 2848 (and therefore also its OMNI address) changes. This should not 2849 present a challenge for MNs with automated network renumbering 2850 services, however presents limits for the durations of ongoing 2851 sessions that would prefer to use a constant address. 2853 21. (H)HITs and Temporary ULAs 2855 MNs that generate (H)HITs but do not have pre-assigned MNPs can 2856 request MNP delegations by issuing IPv6 ND messages that use the 2857 (H)HIT instead of a Temporary ULA. In particular, when a MN creates 2858 an RS message it can set the source to the unspecified address (::) 2859 and destination to All-Routers multicast. The IPv6 ND message 2860 includes an OMNI option with a HIP "Initiator" message sub-option, 2861 and need not include a Node Identification sub-option since the MN's 2862 HIT appears in the HIP message. The MN then encapsulates the message 2863 in an IPv6 header with the (H)HIT as the source address and with 2864 destination set to either a unicast or anycast ADM-ULA. The MN then 2865 sends the message to the AR as specified in Section 14.1. 2867 When the AR receives the message, it notes that the RS source was the 2868 unspecified address (::), then examines the RS encapsulation source 2869 address to determine that the source is a (H)HIT and not a Temporary 2870 ULA. The AR next invokes the DHCPv6 protocol to request an MNP 2871 prefix delegation while using the HIT as the Client Identifier, then 2872 prepares an RA message with source address set to its own ADM-LLA and 2873 destination set to the MNP-LLA corresponding to the delegated MNP. 2874 The AR next includes an OMNI option with a HIP "Responder" message 2875 and any DHCPv6 prefix delegation parameters. The AR then finally 2876 encapsulates the RA in an IPv6 header with source address set to its 2877 own ADM-ULA and destination set to the (H)HIT from the RS 2878 encapsulation source address, then returns the encapsulated RA to the 2879 MN. 2881 MNs can also use (H)HITs and/or Temporary ULAs for direct MN-to-MN 2882 communications outside the context of any OMNI link supporting 2883 infrastructure. When two MNs encounter one another they can use 2884 their (H)HITs and/or Temporary ULAs as IPv6 packet source and 2885 destination addresses to support direct communications. MNs can also 2886 inject their (H)HITs and/or Temporary ULAs into a MANET/VANET routing 2887 protocol to enable multihop communications. MNs can further exchange 2888 IPv6 ND messages (such as NS/NA) using their (H)HITs and/or Temporary 2889 ULAs as source and destination addresses. Note that the HIP security 2890 protocols for establishing secure neighbor relationships are based on 2891 (H)HITs; therefore, Temporary ULAs would presumably utilize some 2892 alternate form of message authentication such as the [RFC4380] 2893 authentication service. 2895 Lastly, when MNs are within the coverage range of OMNI link 2896 infrastructure a case could be made for injecting (H)HITs and/or 2897 Temporary ULAs into the global MS routing system. For example, when 2898 the MN sends an RS to a MSE it could include a request to inject the 2899 (H)HIT / Temporary ULA into the routing system instead of requesting 2900 an MNP prefix delegation. This would potentially enable OMNI link- 2901 wide communications using only (H)HITs or Temporary ULAs, and not 2902 MNPs. This document notes the opportunity, but makes no 2903 recommendation. 2905 22. Address Selection 2907 OMNI MNs use LLAs only for link-scoped communications on the OMNI 2908 link. Typically, MNs use LLAs as source/destination IPv6 addresses 2909 of IPv6 ND messages, but may also use them for addressing ordinary 2910 data packets exchanged with an OMNI link neighbor. 2912 OMNI MNs use MNP-ULAs as source/destination IPv6 addresses in the OAL 2913 headers of OAL-encapsulated packets. OMNI MNs use Temporary ULAs for 2914 OAL addressing when an MNP-ULA is not available, or as source/ 2915 destination IPv6 addresses for communications within a MANET/VANET 2916 local area. OMNI MNs use HITs instead of Temporary ULAs when 2917 operation outside the context of a specific ULA domain and/or source 2918 address attestation is necessary. 2920 OMNI MNs use MNP-based GUAs for communications with Internet 2921 destinations when they are within range of OMNI link supporting 2922 infrastructure that can inject the MNP into the routing system. 2924 23. IANA Considerations 2926 The following IANA actions are requested: 2928 23.1. "IPv6 Neighbor Discovery Option Formats" Registry 2930 The IANA is instructed to allocate an official Type number TBD1 from 2931 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 2932 option. Implementations set Type to 253 as an interim value 2933 [RFC4727]. 2935 23.2. "Ethernet Numbers" Registry 2937 The IANA is instructed to allocate one Ethernet unicast address TBD2 2938 (suggested value '00-52-14') in the 'ethernet-numbers' registry under 2939 "IANA Unicast 48-bit MAC Addresses" as follows: 2941 Addresses Usage Reference 2942 --------- ----- --------- 2943 00-52-14 Overlay Multilink Network (OMNI) Interface [RFCXXXX] 2945 Figure 23: IANA Unicast 48-bit MAC Addresses 2947 23.3. "ICMPv6 Code Fields: Type 2 - Packet Too Big" Registry 2949 The IANA is instructed to assign a new Code value "1" in the "ICMPv6 2950 Code Fields: Type 2 - Packet Too Big" registry. The registry should 2951 appear as follows: 2953 Code Name Reference 2954 --- ---- --------- 2955 0 Diagnostic Packet Too Big [RFC4443] 2956 1 Advisory Packet Too Big [RFCXXXX] 2958 Figure 24: ICMPv6 Code Fields: Type 2 - Packet Too Big Values 2960 23.4. "OMNI Option Sub-Type Values" (New Registry) 2962 The OMNI option defines a 5-bit Sub-Type field, for which IANA is 2963 instructed to create and maintain a new registry entitled "OMNI 2964 Option Sub-Type Values". Initial values are given below (future 2965 assignments are to be made through Standards Action [RFC8126]): 2967 Value Sub-Type name Reference 2968 ----- ------------- ---------- 2969 0 Pad1 [RFCXXXX] 2970 1 PadN [RFCXXXX] 2971 2 Interface Attributes (Type 1) [RFCXXXX] 2972 3 Interface Attributes (Type 2) [RFCXXXX] 2973 4 Traffic Selector [RFCXXXX] 2974 5 MS-Register [RFCXXXX] 2975 6 MS-Release [RFCXXXX] 2976 7 Geo Coordinates [RFCXXXX] 2977 8 DHCPv6 Message [RFCXXXX] 2978 9 HIP Message [RFCXXXX] 2979 10 Node Identification [RFCXXXX] 2980 11-29 Unassigned 2981 30 Sub-Type Extension [RFCXXXX] 2982 31 Reserved by IANA [RFCXXXX] 2984 Figure 25: OMNI Option Sub-Type Values 2986 23.5. "OMNI Node Identification ID-Type Values" (New Registry) 2988 The OMNI Node Identification Sub-Option (see: Section 11.1.11) 2989 contains an 8-bit ID-Type field, for which IANA is instructed to 2990 create and maintain a new registry entitled "OMNI Node Identification 2991 ID-Type Values". Initial values are given below (future assignments 2992 are to be made through Expert Review [RFC8126]): 2994 Value Sub-Type name Reference 2995 ----- ------------- ---------- 2996 0 UUID [RFCXXXX] 2997 1 HIT [RFCXXXX] 2998 2 HHIT [RFCXXXX] 2999 3 Network Access Identifier [RFCXXXX] 3000 4 FQDN [RFCXXXX] 3001 5-252 Unassigned [RFCXXXX] 3002 253-254 Reserved for Experimentation [RFCXXXX] 3003 255 Reserved by IANA [RFCXXXX] 3005 Figure 26: OMNI Node Identification ID-Type Values 3007 23.6. "OMNI Option Sub-Type Extension Values" (New Registry) 3009 The OMNI option defines an 8-bit Extension-Type field for Sub-Type 30 3010 (Sub-Type Extension), for which IANA is instructed to create and 3011 maintain a new registry entitled "OMNI Option Sub-Type Extension 3012 Values". Initial values are given below (future assignments are to 3013 be made through Expert Review [RFC8126]): 3015 Value Sub-Type name Reference 3016 ----- ------------- ---------- 3017 0 RFC4380 UDP/IP Header Option [RFCXXXX] 3018 1 RFC6081 UDP/IP Trailer Option [RFCXXXX] 3019 2-252 Unassigned 3020 253-254 Reserved for Experimentation [RFCXXXX] 3021 255 Reserved by IANA [RFCXXXX] 3023 Figure 27: OMNI Option Sub-Type Extension Values 3025 23.7. "OMNI RFC4380 UDP/IP Header Option" (New Registry) 3027 The OMNI Sub-Type Extension "RFC4380 UDP/IP Header Option" defines an 3028 8-bit Header Type field, for which IANA is instructed to create and 3029 maintain a new registry entitled "OMNI RFC4380 UDP/IP Header Option". 3030 Initial registry values are given below (future assignments are to be 3031 made through Expert Review [RFC8126]): 3033 Value Sub-Type name Reference 3034 ----- ------------- ---------- 3035 0 Origin Indication (IPv4) [RFC4380] 3036 1 Authentication Encapsulation [RFC4380] 3037 2 Origin Indication (IPv6) [RFCXXXX] 3038 3-252 Unassigned 3039 253-254 Reserved for Experimentation [RFCXXXX] 3040 255 Reserved by IANA [RFCXXXX] 3042 Figure 28: OMNI RFC4380 UDP/IP Header Option 3044 23.8. "OMNI RFC6081 UDP/IP Trailer Option" (New Registry) 3046 The OMNI Sub-Type Extension for "RFC6081 UDP/IP Trailer Option" 3047 defines an 8-bit Trailer Type field, for which IANA is instructed to 3048 create and maintain a new registry entitled "OMNI RFC6081 UDP/IP 3049 Trailer Option". Initial registry values are given below (future 3050 assignments are to be made through Expert Review [RFC8126]): 3052 Value Sub-Type name Reference 3053 ----- ------------- ---------- 3054 0 Unassigned 3055 1 Nonce [RFC6081] 3056 2 Unassigned 3057 3 Alternate Address (IPv4) [RFC6081] 3058 4 Neighbor Discovery Option [RFC6081] 3059 5 Random Port [RFC6081] 3060 6 Alternate Address (IPv6) [RFCXXXX] 3061 7-252 Unassigned 3062 253-254 Reserved for Experimentation [RFCXXXX] 3063 255 Reserved by IANA [RFCXXXX] 3065 Figure 29: OMNI RFC6081 Trailer Option 3067 23.9. Additional Considerations 3069 The IANA has assigned the UDP port number "8060" for an earlier 3070 experimental version of AERO [RFC6706]. This document together with 3071 [I-D.templin-intarea-6706bis] reclaims the UDP port number "8060" for 3072 'aero' as the service port for UDP/IP encapsulation. (Note that, 3073 although [RFC6706] was not widely implemented or deployed, any 3074 messages coded to that specification can be easily distinguished and 3075 ignored since they use the invalid ICMPv6 message type number '0'.) 3076 The IANA is therefore instructed to update the reference for UDP port 3077 number "8060" from "RFC6706" to "RFCXXXX" (i.e., this document). 3079 The IANA has assigned a 4 octet Private Enterprise Number (PEN) code 3080 "45282" in the "enterprise-numbers" registry. This document is the 3081 normative reference for using this code in DHCP Unique IDentifiers 3082 based on Enterprise Numbers ("DUID-EN for OMNI Interfaces") (see: 3083 Section 10). The IANA is therefore instructed to change the 3084 enterprise designation for PEN code "45282" from "LinkUp Networks" to 3085 "Overlay Multilink Network Interface (OMNI)". 3087 The IANA has assigned the ifType code "301 - omni - Overlay Multilink 3088 Network Interface (OMNI)" in accordance with Section 6 of [RFC8892]. 3089 The registration appears under the IANA "Structure of Management 3090 Information (SMI) Numbers (MIB Module Registrations) - Interface 3091 Types (ifType)" registry. 3093 No further IANA actions are required. 3095 24. Security Considerations 3097 Security considerations for IPv4 [RFC0791], IPv6 [RFC8200] and IPv6 3098 Neighbor Discovery [RFC4861] apply. OMNI interface IPv6 ND messages 3099 SHOULD include Nonce and Timestamp options [RFC3971] when transaction 3100 confirmation and/or time synchronization is needed. 3102 MN OMNI interfaces configured over secured ANET interfaces inherit 3103 the physical and/or link-layer security properties (i.e., "protected 3104 spectrum") of the connected ANETs. MN OMNI interfaces configured 3105 over open INET interfaces can use symmetric securing services such as 3106 VPNs or can by some other means establish a direct link. When a VPN 3107 or direct link may be impractical, however, the security services 3108 specified in [RFC7401] and/or [RFC4380] can be employed. While the 3109 OMNI link protects control plane messaging, applications must still 3110 employ end-to-end transport- or higher-layer security services to 3111 protect the data plane. 3113 Strong network layer security for control plane messages and 3114 forwarding path integrity for data plane messages between MSEs MUST 3115 be supported. In one example, the AERO service 3116 [I-D.templin-intarea-6706bis] constructs a spanning tree between MSEs 3117 and secures the links in the spanning tree with network layer 3118 security mechanisms such as IPsec [RFC4301] or Wireguard. Control 3119 plane messages are then constrained to travel only over the secured 3120 spanning tree paths and are therefore protected from attack or 3121 eavesdropping. Since data plane messages can travel over route 3122 optimized paths that do not strictly follow the spanning tree, 3123 however, end-to-end transport- or higher-layer security services are 3124 still required. 3126 Identity-based key verification infrastructure services such as iPSK 3127 may be necessary for verifying the identities claimed by MNs. This 3128 requirement should be harmonized with the manner in which (H)HITs are 3129 attested in a given operational environment. 3131 Security considerations for specific access network interface types 3132 are covered under the corresponding IP-over-(foo) specification 3133 (e.g., [RFC2464], [RFC2492], etc.). 3135 Security considerations for IPv6 fragmentation and reassembly are 3136 discussed in Section 5.5. 3138 25. Implementation Status 3140 AERO/OMNI Release-3.0.2 was tagged on October 15, 2020, and is 3141 undergoing internal testing. Additional internal releases expected 3142 within the coming months, with first public release expected end of 3143 1H2021. 3145 26. Acknowledgements 3147 The first version of this document was prepared per the consensus 3148 decision at the 7th Conference of the International Civil Aviation 3149 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 3150 2019. Consensus to take the document forward to the IETF was reached 3151 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 3152 Attendees and contributors included: Guray Acar, Danny Bharj, 3153 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 3154 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 3155 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 3156 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 3157 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 3158 Fryderyk Wrobel and Dongsong Zeng. 3160 The following individuals are acknowledged for their useful comments: 3161 Stuart Card, Michael Matyas, Robert Moskowitz, Madhu Niraula, Greg 3162 Saccone, Stephane Tamalet, Eric Vyncke. Pavel Drasil, Zdenek Jaron 3163 and Michal Skorepa are especially recognized for their many helpful 3164 ideas and suggestions. Madhuri Madhava Badgandi, Sean Dickson, Don 3165 Dillenburg, Joe Dudkowski, Vijayasarathy Rajagopalan, Ron Sackman and 3166 Katherine Tran are acknowledged for their hard work on the 3167 implementation and technical insights that led to improvements for 3168 the spec. 3170 Discussions on the IETF 6man and atn mailing lists during the fall of 3171 2020 suggested additional points to consider. The authors gratefully 3172 acknowledge the list members who contributed valuable insights 3173 through those discussions. Eric Vyncke and Erik Kline were the 3174 intarea ADs, while Bob Hinden and Ole Troan were the 6man WG chairs 3175 at the time the document was developed; they are all gratefully 3176 acknowledged for their many helpful insights. 3178 This work is aligned with the NASA Safe Autonomous Systems Operation 3179 (SASO) program under NASA contract number NNA16BD84C. 3181 This work is aligned with the FAA as per the SE2025 contract number 3182 DTFAWA-15-D-00030. 3184 This work is aligned with the Boeing Information Technology (BIT) 3185 Mobility Vision Lab (MVL) program. 3187 27. References 3189 27.1. Normative References 3191 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 3192 DOI 10.17487/RFC0791, September 1981, 3193 . 3195 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 3196 Requirement Levels", BCP 14, RFC 2119, 3197 DOI 10.17487/RFC2119, March 1997, 3198 . 3200 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 3201 "Definition of the Differentiated Services Field (DS 3202 Field) in the IPv4 and IPv6 Headers", RFC 2474, 3203 DOI 10.17487/RFC2474, December 1998, 3204 . 3206 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 3207 "SEcure Neighbor Discovery (SEND)", RFC 3971, 3208 DOI 10.17487/RFC3971, March 2005, 3209 . 3211 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 3212 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 3213 November 2005, . 3215 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 3216 Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005, 3217 . 3219 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 3220 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 3221 2006, . 3223 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 3224 Control Message Protocol (ICMPv6) for the Internet 3225 Protocol Version 6 (IPv6) Specification", STD 89, 3226 RFC 4443, DOI 10.17487/RFC4443, March 2006, 3227 . 3229 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 3230 ICMPv6, UDP, and TCP Headers", RFC 4727, 3231 DOI 10.17487/RFC4727, November 2006, 3232 . 3234 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 3235 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 3236 DOI 10.17487/RFC4861, September 2007, 3237 . 3239 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 3240 Address Autoconfiguration", RFC 4862, 3241 DOI 10.17487/RFC4862, September 2007, 3242 . 3244 [RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont, 3245 "Traffic Selectors for Flow Bindings", RFC 6088, 3246 DOI 10.17487/RFC6088, January 2011, 3247 . 3249 [RFC7401] Moskowitz, R., Ed., Heer, T., Jokela, P., and T. 3250 Henderson, "Host Identity Protocol Version 2 (HIPv2)", 3251 RFC 7401, DOI 10.17487/RFC7401, April 2015, 3252 . 3254 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 3255 Hosts in a Multi-Prefix Network", RFC 8028, 3256 DOI 10.17487/RFC8028, November 2016, 3257 . 3259 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 3260 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 3261 May 2017, . 3263 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 3264 (IPv6) Specification", STD 86, RFC 8200, 3265 DOI 10.17487/RFC8200, July 2017, 3266 . 3268 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 3269 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 3270 DOI 10.17487/RFC8201, July 2017, 3271 . 3273 [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., 3274 Richardson, M., Jiang, S., Lemon, T., and T. Winters, 3275 "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", 3276 RFC 8415, DOI 10.17487/RFC8415, November 2018, 3277 . 3279 27.2. Informative References 3281 [ATN] Maiolla, V., "The OMNI Interface - An IPv6 Air/Ground 3282 Interface for Civil Aviation, IETF Liaison Statement 3283 #1676, https://datatracker.ietf.org/liaison/1676/", March 3284 2020. 3286 [ATN-IPS] WG-I, ICAO., "ICAO Document 9896 (Manual on the 3287 Aeronautical Telecommunication Network (ATN) using 3288 Internet Protocol Suite (IPS) Standards and Protocol), 3289 Draft Edition 3 (work-in-progress)", December 2020. 3291 [CRC] Jain, R., "Error Characteristics of Fiber Distributed Data 3292 Interface (FDDI), IEEE Transactions on Communications", 3293 August 1990. 3295 [I-D.ietf-6man-rfc4941bis] 3296 Gont, F., Krishnan, S., Narten, T., and R. Draves, 3297 "Temporary Address Extensions for Stateless Address 3298 Autoconfiguration in IPv6", draft-ietf-6man-rfc4941bis-12 3299 (work in progress), November 2020. 3301 [I-D.ietf-drip-rid] 3302 Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov, 3303 "UAS Remote ID", draft-ietf-drip-rid-06 (work in 3304 progress), December 2020. 3306 [I-D.ietf-intarea-tunnels] 3307 Touch, J. and M. Townsley, "IP Tunnels in the Internet 3308 Architecture", draft-ietf-intarea-tunnels-10 (work in 3309 progress), September 2019. 3311 [I-D.ietf-ipwave-vehicular-networking] 3312 Jeong, J., "IPv6 Wireless Access in Vehicular Environments 3313 (IPWAVE): Problem Statement and Use Cases", draft-ietf- 3314 ipwave-vehicular-networking-19 (work in progress), July 3315 2020. 3317 [I-D.templin-6man-dhcpv6-ndopt] 3318 Templin, F., "A Unified Stateful/Stateless Configuration 3319 Service for IPv6", draft-templin-6man-dhcpv6-ndopt-11 3320 (work in progress), January 2021. 3322 [I-D.templin-6man-lla-type] 3323 Templin, F., "The IPv6 Link-Local Address Type Field", 3324 draft-templin-6man-lla-type-02 (work in progress), 3325 November 2020. 3327 [I-D.templin-intarea-6706bis] 3328 Templin, F., "Asymmetric Extended Route Optimization 3329 (AERO)", draft-templin-intarea-6706bis-87 (work in 3330 progress), January 2021. 3332 [IPV4-GUA] 3333 Postel, J., "IPv4 Address Space Registry, 3334 https://www.iana.org/assignments/ipv4-address-space/ipv4- 3335 address-space.xhtml", December 2020. 3337 [IPV6-GUA] 3338 Postel, J., "IPv6 Global Unicast Address Assignments, 3339 https://www.iana.org/assignments/ipv6-unicast-address- 3340 assignments/ipv6-unicast-address-assignments.xhtml", 3341 December 2020. 3343 [RFC1035] Mockapetris, P., "Domain names - implementation and 3344 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 3345 November 1987, . 3347 [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - 3348 Communication Layers", STD 3, RFC 1122, 3349 DOI 10.17487/RFC1122, October 1989, 3350 . 3352 [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, 3353 DOI 10.17487/RFC1191, November 1990, 3354 . 3356 [RFC1256] Deering, S., Ed., "ICMP Router Discovery Messages", 3357 RFC 1256, DOI 10.17487/RFC1256, September 1991, 3358 . 3360 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 3361 RFC 2131, DOI 10.17487/RFC2131, March 1997, 3362 . 3364 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 3365 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 3366 . 3368 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 3369 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 3370 . 3372 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 3373 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 3374 December 1998, . 3376 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 3377 Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999, 3378 . 3380 [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 3381 Domains without Explicit Tunnels", RFC 2529, 3382 DOI 10.17487/RFC2529, March 1999, 3383 . 3385 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 3386 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 3387 . 3389 [RFC3330] IANA, "Special-Use IPv4 Addresses", RFC 3330, 3390 DOI 10.17487/RFC3330, September 2002, 3391 . 3393 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 3394 Considered Useful", BCP 82, RFC 3692, 3395 DOI 10.17487/RFC3692, January 2004, 3396 . 3398 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 3399 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 3400 DOI 10.17487/RFC3810, June 2004, 3401 . 3403 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 3404 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 3405 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 3406 RFC 3819, DOI 10.17487/RFC3819, July 2004, 3407 . 3409 [RFC3879] Huitema, C. and B. Carpenter, "Deprecating Site Local 3410 Addresses", RFC 3879, DOI 10.17487/RFC3879, September 3411 2004, . 3413 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 3414 Unique IDentifier (UUID) URN Namespace", RFC 4122, 3415 DOI 10.17487/RFC4122, July 2005, 3416 . 3418 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 3419 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 3420 DOI 10.17487/RFC4271, January 2006, 3421 . 3423 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 3424 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 3425 December 2005, . 3427 [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through 3428 Network Address Translations (NATs)", RFC 4380, 3429 DOI 10.17487/RFC4380, February 2006, 3430 . 3432 [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery 3433 Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April 3434 2006, . 3436 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 3437 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 3438 . 3440 [RFC4541] Christensen, M., Kimball, K., and F. Solensky, 3441 "Considerations for Internet Group Management Protocol 3442 (IGMP) and Multicast Listener Discovery (MLD) Snooping 3443 Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006, 3444 . 3446 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 3447 "Internet Group Management Protocol (IGMP) / Multicast 3448 Listener Discovery (MLD)-Based Multicast Forwarding 3449 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 3450 August 2006, . 3452 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 3453 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 3454 . 3456 [RFC4963] Heffner, J., Mathis, M., and B. Chandler, "IPv4 Reassembly 3457 Errors at High Data Rates", RFC 4963, 3458 DOI 10.17487/RFC4963, July 2007, 3459 . 3461 [RFC5175] Haberman, B., Ed. and R. Hinden, "IPv6 Router 3462 Advertisement Flags Option", RFC 5175, 3463 DOI 10.17487/RFC5175, March 2008, 3464 . 3466 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 3467 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 3468 RFC 5213, DOI 10.17487/RFC5213, August 2008, 3469 . 3471 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 3472 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 3473 DOI 10.17487/RFC5214, March 2008, 3474 . 3476 [RFC5558] Templin, F., Ed., "Virtual Enterprise Traversal (VET)", 3477 RFC 5558, DOI 10.17487/RFC5558, February 2010, 3478 . 3480 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 3481 Version 3 for IPv4 and IPv6", RFC 5798, 3482 DOI 10.17487/RFC5798, March 2010, 3483 . 3485 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 3486 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 3487 . 3489 [RFC6081] Thaler, D., "Teredo Extensions", RFC 6081, 3490 DOI 10.17487/RFC6081, January 2011, 3491 . 3493 [RFC6221] Miles, D., Ed., Ooghe, S., Dec, W., Krishnan, S., and A. 3494 Kavanagh, "Lightweight DHCPv6 Relay Agent", RFC 6221, 3495 DOI 10.17487/RFC6221, May 2011, 3496 . 3498 [RFC6355] Narten, T. and J. Johnson, "Definition of the UUID-Based 3499 DHCPv6 Unique Identifier (DUID-UUID)", RFC 6355, 3500 DOI 10.17487/RFC6355, August 2011, 3501 . 3503 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 3504 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 3505 2012, . 3507 [RFC6706] Templin, F., Ed., "Asymmetric Extended Route Optimization 3508 (AERO)", RFC 6706, DOI 10.17487/RFC6706, August 2012, 3509 . 3511 [RFC6980] Gont, F., "Security Implications of IPv6 Fragmentation 3512 with IPv6 Neighbor Discovery", RFC 6980, 3513 DOI 10.17487/RFC6980, August 2013, 3514 . 3516 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 3517 Requirements for IPv6 Customer Edge Routers", RFC 7084, 3518 DOI 10.17487/RFC7084, November 2013, 3519 . 3521 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 3522 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 3523 Boundary in IPv6 Addressing", RFC 7421, 3524 DOI 10.17487/RFC7421, January 2015, 3525 . 3527 [RFC7526] Troan, O. and B. Carpenter, Ed., "Deprecating the Anycast 3528 Prefix for 6to4 Relay Routers", BCP 196, RFC 7526, 3529 DOI 10.17487/RFC7526, May 2015, 3530 . 3532 [RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542, 3533 DOI 10.17487/RFC7542, May 2015, 3534 . 3536 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 3537 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 3538 February 2016, . 3540 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 3541 Support for IP Hosts with Multi-Access Support", RFC 7847, 3542 DOI 10.17487/RFC7847, May 2016, 3543 . 3545 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 3546 Writing an IANA Considerations Section in RFCs", BCP 26, 3547 RFC 8126, DOI 10.17487/RFC8126, June 2017, 3548 . 3550 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 3551 Decraene, B., Litkowski, S., and R. Shakir, "Segment 3552 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 3553 July 2018, . 3555 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 3556 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 3557 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 3558 . 3560 [RFC8892] Thaler, D. and D. Romascanu, "Guidelines and Registration 3561 Procedures for Interface Types and Tunnel Types", 3562 RFC 8892, DOI 10.17487/RFC8892, August 2020, 3563 . 3565 [RFC8899] Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and 3566 T. Voelker, "Packetization Layer Path MTU Discovery for 3567 Datagram Transports", RFC 8899, DOI 10.17487/RFC8899, 3568 September 2020, . 3570 [RFC8900] Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O., 3571 and F. Gont, "IP Fragmentation Considered Fragile", 3572 BCP 230, RFC 8900, DOI 10.17487/RFC8900, September 2020, 3573 . 3575 Appendix A. Interface Attribute Preferences Bitmap Encoding 3577 Adaptation of the OMNI option Interface Attributes Preferences Bitmap 3578 encoding to specific Internetworks such as the Aeronautical 3579 Telecommunications Network with Internet Protocol Services (ATN/IPS) 3580 may include link selection preferences based on other traffic 3581 classifiers (e.g., transport port numbers, etc.) in addition to the 3582 existing DSCP-based preferences. Nodes on specific Internetworks 3583 maintain a map of traffic classifiers to additional P[*] preference 3584 fields beyond the first 64. For example, TCP port 22 maps to P[67], 3585 TCP port 443 maps to P[70], UDP port 8060 maps to P[76], etc. 3587 Implementations use Simplex or Indexed encoding formats for P[*] 3588 encoding in order to encode a given set of traffic classifiers in the 3589 most efficient way. Some use cases may be more efficiently coded 3590 using Simplex form, while others may be more efficient using Indexed. 3591 Once a format is selected for preparation of a single Interface 3592 Attribute the same format must be used for the entire Interface 3593 Attribute sub-option. Different sub-options may use different 3594 formats. 3596 The following figures show coding examples for various Simplex and 3597 Indexed formats: 3599 0 1 2 3 3600 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 3601 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3602 | Sub-Type=3| Sub-length=N | omIndex | omType | 3603 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3604 | Provider ID | Link |R| API | Bitmap(0)=0xff|P00|P01|P02|P03| 3605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3606 |P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19| 3607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3608 |P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| Bitmap(1)=0xff| 3609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3610 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 3611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3612 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 3613 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3614 | Bitmap(2)=0xff|P64|P65|P67|P68| ... 3615 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 3617 Figure 30: Example 1: Dense Simplex Encoding 3619 0 1 2 3 3620 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 3621 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3622 | Sub-Type=3| Sub-length=N | omIndex | omType | 3623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3624 | Provider ID | Link |R| API | Bitmap(0)=0x00| Bitmap(1)=0x0f| 3625 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3626 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 3627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3628 | Bitmap(2)=0x00| Bitmap(3)=0x00| Bitmap(4)=0x00| Bitmap(5)=0x00| 3629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3630 | Bitmap(6)=0xf0|192|193|194|195|196|197|198|199|200|201|202|203| 3631 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3632 |204|205|206|207| Bitmap(7)=0x00| Bitmap(8)=0x0f|272|273|274|275| 3633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3634 |276|277|278|279|280|281|282|283|284|285|286|287| Bitmap(9)=0x00| 3635 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3636 |Bitmap(10)=0x00| ... 3637 +-+-+-+-+-+-+-+-+-+-+- 3639 Figure 31: Example 2: Sparse Simplex Encoding 3641 0 1 2 3 3642 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 3643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3644 | Sub-Type=3| Sub-length=N | omIndex | omType | 3645 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3646 | Provider ID | Link |R| API | Index = 0x00 | Bitmap = 0x80 | 3647 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3648 |P00|P01|P02|P03| Index = 0x01 | Bitmap = 0x01 |P60|P61|P62|P63| 3649 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3650 | Index = 0x10 | Bitmap = 0x80 |512|513|514|515| Index = 0x18 | 3651 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3652 | Bitmap = 0x01 |796|797|798|799| ... 3653 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 3655 Figure 32: Example 3: Indexed Encoding 3657 Appendix B. VDL Mode 2 Considerations 3659 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 3660 (VDLM2) that specifies an essential radio frequency data link service 3661 for aircraft and ground stations in worldwide civil aviation air 3662 traffic management. The VDLM2 link type is "multicast capable" 3663 [RFC4861], but with considerable differences from common multicast 3664 links such as Ethernet and IEEE 802.11. 3666 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 3667 magnitude less than most modern wireless networking gear. Second, 3668 due to the low available link bandwidth only VDLM2 ground stations 3669 (i.e., and not aircraft) are permitted to send broadcasts, and even 3670 so only as compact layer 2 "beacons". Third, aircraft employ the 3671 services of ground stations by performing unicast RS/RA exchanges 3672 upon receipt of beacons instead of listening for multicast RA 3673 messages and/or sending multicast RS messages. 3675 This beacon-oriented unicast RS/RA approach is necessary to conserve 3676 the already-scarce available link bandwidth. Moreover, since the 3677 numbers of beaconing ground stations operating within a given spatial 3678 range must be kept as sparse as possible, it would not be feasible to 3679 have different classes of ground stations within the same region 3680 observing different protocols. It is therefore highly desirable that 3681 all ground stations observe a common language of RS/RA as specified 3682 in this document. 3684 Note that links of this nature may benefit from compression 3685 techniques that reduce the bandwidth necessary for conveying the same 3686 amount of data. The IETF lpwan working group is considering possible 3687 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 3689 Appendix C. MN / AR Isolation Through L2 Address Mapping 3691 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 3692 unicast link-scoped IPv6 destination address. However, IPv6 ND 3693 messaging should be coordinated between the MN and AR only without 3694 invoking other nodes on the *NET. This implies that MN / AR control 3695 messaging should be isolated and not overheard by other nodes on the 3696 link. 3698 To support MN / AR isolation on some *NET links, ARs can maintain an 3699 OMNI-specific unicast L2 address ("MSADDR"). For Ethernet-compatible 3700 *NETs, this specification reserves one Ethernet unicast address TBD2 3701 (see: Section 23). For non-Ethernet statically-addressed *NETs, 3702 MSADDR is reserved per the assigned numbers authority for the *NET 3703 addressing space. For still other *NETs, MSADDR may be dynamically 3704 discovered through other means, e.g., L2 beacons. 3706 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 3707 both multicast and unicast) to MSADDR instead of to an ordinary 3708 unicast or multicast L2 address. In this way, all of the MN's IPv6 3709 ND messages will be received by ARs that are configured to accept 3710 packets destined to MSADDR. Note that multiple ARs on the link could 3711 be configured to accept packets destined to MSADDR, e.g., as a basis 3712 for supporting redundancy. 3714 Therefore, ARs must accept and process packets destined to MSADDR, 3715 while all other devices must not process packets destined to MSADDR. 3716 This model has well-established operational experience in Proxy 3717 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 3719 Appendix D. Change Log 3721 << RFC Editor - remove prior to publication >> 3723 Differences from draft-templin-6man-omni-interface-35 to draft- 3724 templin-6man-omni-interface-36: 3726 o Major clarifications on aspects such as "hard/soft" PTB error 3727 messages 3729 o Made generic so that either IP protocol version (IPv4 or IPv6) can 3730 be used in the data plane. 3732 Differences from draft-templin-6man-omni-interface-31 to draft- 3733 templin-6man-omni-interface-32: 3735 o MTU 3736 o Support for multi-hop ANETS such as ISATAP. 3738 Differences from draft-templin-6man-omni-interface-29 to draft- 3739 templin-6man-omni-interface-30: 3741 o Moved link-layer addressing information into the OMNI option on a 3742 per-ifIndex basis 3744 o Renamed "ifIndex-tuple" to "Interface Attributes" 3746 Differences from draft-templin-6man-omni-interface-27 to draft- 3747 templin-6man-omni-interface-28: 3749 o Updates based on implementation experience. 3751 Differences from draft-templin-6man-omni-interface-25 to draft- 3752 templin-6man-omni-interface-26: 3754 o Further clarification on "aggregate" RA messages. 3756 o Expanded Security Considerations to discuss expectations for 3757 security in the Mobility Service. 3759 Differences from draft-templin-6man-omni-interface-20 to draft- 3760 templin-6man-omni-interface-21: 3762 o Safety-Based Multilink (SBM) and Performance-Based Multilink 3763 (PBM). 3765 Differences from draft-templin-6man-omni-interface-18 to draft- 3766 templin-6man-omni-interface-19: 3768 o SEND/CGA. 3770 Differences from draft-templin-6man-omni-interface-17 to draft- 3771 templin-6man-omni-interface-18: 3773 o Teredo 3775 Differences from draft-templin-6man-omni-interface-14 to draft- 3776 templin-6man-omni-interface-15: 3778 o Prefix length discussions removed. 3780 Differences from draft-templin-6man-omni-interface-12 to draft- 3781 templin-6man-omni-interface-13: 3783 o Teredo 3784 Differences from draft-templin-6man-omni-interface-11 to draft- 3785 templin-6man-omni-interface-12: 3787 o Major simplifications and clarifications on MTU and fragmentation. 3789 o Document now updates RFC4443 and RFC8201. 3791 Differences from draft-templin-6man-omni-interface-10 to draft- 3792 templin-6man-omni-interface-11: 3794 o Removed /64 assumption, resulting in new OMNI address format. 3796 Differences from draft-templin-6man-omni-interface-07 to draft- 3797 templin-6man-omni-interface-08: 3799 o OMNI MNs in the open Internet 3801 Differences from draft-templin-6man-omni-interface-06 to draft- 3802 templin-6man-omni-interface-07: 3804 o Brought back L2 MSADDR mapping text for MN / AR isolation based on 3805 L2 addressing. 3807 o Expanded "Transition Considerations". 3809 Differences from draft-templin-6man-omni-interface-05 to draft- 3810 templin-6man-omni-interface-06: 3812 o Brought back OMNI option "R" flag, and discussed its use. 3814 Differences from draft-templin-6man-omni-interface-04 to draft- 3815 templin-6man-omni-interface-05: 3817 o Transition considerations, and overhaul of RS/RA addressing with 3818 the inclusion of MSE addresses within the OMNI option instead of 3819 as RS/RA addresses (developed under FAA SE2025 contract number 3820 DTFAWA-15-D-00030). 3822 Differences from draft-templin-6man-omni-interface-02 to draft- 3823 templin-6man-omni-interface-03: 3825 o Added "advisory PTB messages" under FAA SE2025 contract number 3826 DTFAWA-15-D-00030. 3828 Differences from draft-templin-6man-omni-interface-01 to draft- 3829 templin-6man-omni-interface-02: 3831 o Removed "Primary" flag and supporting text. 3833 o Clarified that "Router Lifetime" applies to each ANET interface 3834 independently, and that the union of all ANET interface Router 3835 Lifetimes determines MSE lifetime. 3837 Differences from draft-templin-6man-omni-interface-00 to draft- 3838 templin-6man-omni-interface-01: 3840 o "All-MSEs" OMNI LLA defined. Also reserved fe80::ff00:0000/104 3841 for future use (most likely as "pseudo-multicast"). 3843 o Non-normative discussion of alternate OMNI LLA construction form 3844 made possible if the 64-bit assumption were relaxed. 3846 First draft version (draft-templin-atn-aero-interface-00): 3848 o Draft based on consensus decision of ICAO Working Group I Mobility 3849 Subgroup March 22, 2019. 3851 Authors' Addresses 3853 Fred L. Templin (editor) 3854 The Boeing Company 3855 P.O. Box 3707 3856 Seattle, WA 98124 3857 USA 3859 Email: fltemplin@acm.org 3861 Tony Whyman 3862 MWA Ltd c/o Inmarsat Global Ltd 3863 99 City Road 3864 London EC1Y 1AX 3865 England 3867 Email: tony.whyman@mccallumwhyman.com