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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 December 16, 2020 7 Expires: June 19, 2021 9 Transmission of IP Packets over Overlay Multilink Network (OMNI) 10 Interfaces 11 draft-templin-6man-omni-interface-60 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 June 19, 2021. 41 Copyright Notice 43 Copyright (c) 2020 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (https://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 59 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 60 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 8 61 4. Overlay Multilink Network (OMNI) Interface Model . . . . . . 9 62 5. The OMNI Adaptation Layer (OAL) . . . . . . . . . . . . . . . 13 63 5.1. Fragmentation Security Implications . . . . . . . . . . . 18 64 6. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 18 65 7. Link-Local Addresses (LLAs) . . . . . . . . . . . . . . . . . 19 66 8. Unique-Local Addresses (ULAs) . . . . . . . . . . . . . . . . 20 67 9. Global Unicast Addresses (GUAs) . . . . . . . . . . . . . . . 21 68 10. Address Mapping - Unicast . . . . . . . . . . . . . . . . . . 22 69 10.1. Sub-Options . . . . . . . . . . . . . . . . . . . . . . 24 70 10.1.1. Pad1 . . . . . . . . . . . . . . . . . . . . . . . . 25 71 10.1.2. PadN . . . . . . . . . . . . . . . . . . . . . . . . 25 72 10.1.3. Interface Attributes . . . . . . . . . . . . . . . . 25 73 10.1.4. Traffic Selector . . . . . . . . . . . . . . . . . . 29 74 10.1.5. MS-Register . . . . . . . . . . . . . . . . . . . . 30 75 10.1.6. MS-Release . . . . . . . . . . . . . . . . . . . . . 30 76 10.1.7. Network Access Identifier (NAI) . . . . . . . . . . 31 77 10.1.8. Geo Coordinates . . . . . . . . . . . . . . . . . . 32 78 10.1.9. DHCP Unique Identifier (DUID) . . . . . . . . . . . 32 79 10.1.10. DHCPv6 Message . . . . . . . . . . . . . . . . . . . 33 80 11. Address Mapping - Multicast . . . . . . . . . . . . . . . . . 33 81 12. Multilink Conceptual Sending Algorithm . . . . . . . . . . . 34 82 12.1. Multiple OMNI Interfaces . . . . . . . . . . . . . . . . 34 83 12.2. MN<->AR Traffic Loop Prevention . . . . . . . . . . . . 35 84 13. Router Discovery and Prefix Registration . . . . . . . . . . 35 85 13.1. Router Discovery in IP Multihop and IPv4-Only Networks . 39 86 13.2. MS-Register and MS-Release List Processing . . . . . . . 41 87 13.3. DHCPv6-based Prefix Registration . . . . . . . . . . . . 42 88 14. Secure Redirection . . . . . . . . . . . . . . . . . . . . . 43 89 15. AR and MSE Resilience . . . . . . . . . . . . . . . . . . . . 44 90 16. Detecting and Responding to MSE Failures . . . . . . . . . . 44 91 17. Transition Considerations . . . . . . . . . . . . . . . . . . 45 92 18. OMNI Interfaces on the Open Internet . . . . . . . . . . . . 45 93 19. Time-Varying MNPs . . . . . . . . . . . . . . . . . . . . . . 46 94 20. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47 95 21. Security Considerations . . . . . . . . . . . . . . . . . . . 48 96 22. Implementation Status . . . . . . . . . . . . . . . . . . . . 48 97 23. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 49 98 24. References . . . . . . . . . . . . . . . . . . . . . . . . . 49 99 24.1. Normative References . . . . . . . . . . . . . . . . . . 49 100 24.2. Informative References . . . . . . . . . . . . . . . . . 51 101 Appendix A. Interface Attribute Preferences Bitmap Encoding . . 57 102 Appendix B. VDL Mode 2 Considerations . . . . . . . . . . . . . 58 103 Appendix C. MN / AR Isolation Through L2 Address Mapping . . . . 59 104 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 60 105 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 62 107 1. Introduction 109 Mobile Nodes (MNs) (e.g., aircraft of various configurations, 110 terrestrial vehicles, seagoing vessels, enterprise wireless devices, 111 etc.) often have multiple interface connections to wireless and/or 112 wired-link data links used for communicating with networked 113 correspondents. These data links may have diverse performance, cost 114 and availability properties that can change dynamically according to 115 mobility patterns, flight phases, proximity to infrastructure, etc. 116 MNs coordinate their data links in a discipline known as "multilink", 117 in which a single virtual interface is configured over the node's 118 underlying interface connections to the data links. 120 The MN configures a virtual interface (termed the "Overlay Multilink 121 Network (OMNI) interface") as a thin layer over the underlying 122 interfaces. The OMNI interface is therefore the only interface 123 abstraction exposed to the IP layer and behaves according to the Non- 124 Broadcast, Multiple Access (NBMA) interface principle, while 125 underlying interfaces appear as link layer communication channels in 126 the architecture. The OMNI interface connects to a virtual overlay 127 service known as the "OMNI link". The OMNI link spans one or more 128 Internetworks that may include private-use infrastructures and/or the 129 global public Internet itself. 131 Each MN receives a Mobile Network Prefix (MNP) for numbering 132 downstream-attached End User Networks (EUNs) independently of the 133 access network data links selected for data transport. The MN 134 performs router discovery over the OMNI interface (i.e., similar to 135 IPv6 customer edge routers [RFC7084]) and acts as a mobile router on 136 behalf of its EUNs. The router discovery process is iterated over 137 each of the OMNI interface's underlying interfaces in order to 138 register per-link parameters (see Section 13). 140 The OMNI interface provides a multilink nexus for exchanging inbound 141 and outbound traffic via the correct underlying interface(s). The IP 142 layer sees the OMNI interface as a point of connection to the OMNI 143 link. Each OMNI link has one or more associated Mobility Service 144 Prefixes (MSPs), which are typically IP Global Unicast Address (GUA) 145 prefixes from which OMNI link MNPs are derived. If there are 146 multiple OMNI links, the IPv6 layer will see multiple OMNI 147 interfaces. 149 MNs may connect to multiple distinct OMNI links by configuring 150 multiple OMNI interfaces, e.g., omni0, omni1, omni2, etc. Each OMNI 151 interface is configured over a set of underlying interfaces and 152 provides a nexus for Safety-Based Multilink (SBM) operation. Each 153 OMNI SBM "domain" configures a common OMNI ULA ::/48 prefix, and each 154 OMNI link within the domain configures a unique ::/64 sub-prefix 155 within the domain common ::/48 (see: Section 8). The IP layer 156 applies SBM routing to select an OMNI interface, which then applies 157 Performance-Based Multilink (PBM) to select the correct underlying 158 interface. Applications can apply Segment Routing [RFC8402] to 159 select independent SBM topologies for fault tolerance. 161 The OMNI interface interacts with a network-based Mobility Service 162 (MS) through IPv6 Neighbor Discovery (ND) control message exchanges 163 [RFC4861]. The MS provides Mobility Service Endpoints (MSEs) that 164 track MN movements and represent their MNPs in a global routing or 165 mapping system. 167 Many OMNI use cases are currently under active consideration. In 168 particular, the International Civil Aviation Organization (ICAO) 169 Working Group-I Mobility Subgroup is developing a future Aeronautical 170 Telecommunications Network with Internet Protocol Services (ATN/IPS) 171 and has issued a liaison statement requesting IETF adoption [ATN] in 172 support of ICAO Document 9896 [ATN-IPS]. The IETF IP Wireless Access 173 in Vehicular Environments (ipwave) working group has further included 174 problem statement and use case analysis for OMNI in a document now in 175 AD evaluation for RFC publication 176 [I-D.ietf-ipwave-vehicular-networking]. Still other communities of 177 interest include AEEC, RTCA Special Committee 228 (SC-228) and NASA 178 programs that examine commercial aviation, Urban Air Mobility (UAM) 179 and Unmanned Air Systems (UAS). Pedestrians with handheld devices 180 represent another large class of potential OMNI users. 182 This document specifies the transmission of IP packets and MN/MS 183 control messages over OMNI interfaces. The OMNI interface supports 184 either IP protocol version (i.e., IPv4 [RFC0791] or IPv6 [RFC8200]) 185 as the network layer in the data plane, while using IPv6 ND messaging 186 as the control plane independently of the data plane IP protocol(s). 187 The OMNI Adaptation Layer (OAL) which operates as a mid-layer between 188 L3 and L2 is based on IP-in-IPv6 encapsulation per [RFC2473] as 189 discussed in the following sections. 191 2. Terminology 193 The terminology in the normative references applies; especially, the 194 terms "link" and "interface" are the same as defined in the IPv6 195 [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications. 196 Additionally, this document assumes the following IPv6 ND message 197 types: Router Solicitation (RS), Router Advertisement (RA), Neighbor 198 Solicitation (NS), Neighbor Advertisement (NA) and Redirect. 200 The Protocol Constants defined in Section 10 of [RFC4861] are used in 201 their same format and meaning in this document. The terms "All- 202 Routers multicast", "All-Nodes multicast" and "Subnet-Router anycast" 203 are the same as defined in [RFC4291] (with Link-Local scope assumed). 205 The term "IP" is used to refer collectively to either Internet 206 Protocol version (i.e., IPv4 [RFC0791] or IPv6 [RFC8200]) when a 207 specification at the layer in question applies equally to either 208 version. 210 The following terms are defined within the scope of this document: 212 Mobile Node (MN) 213 an end system with a mobile router having multiple distinct 214 upstream data link connections that are grouped together in one or 215 more logical units. The MN's data link connection parameters can 216 change over time due to, e.g., node mobility, link quality, etc. 217 The MN further connects a downstream-attached End User Network 218 (EUN). The term MN used here is distinct from uses in other 219 documents, and does not imply a particular mobility protocol. 221 End User Network (EUN) 222 a simple or complex downstream-attached mobile network that 223 travels with the MN as a single logical unit. The IP addresses 224 assigned to EUN devices remain stable even if the MN's upstream 225 data link connections change. 227 Mobility Service (MS) 228 a mobile routing service that tracks MN movements and ensures that 229 MNs remain continuously reachable even across mobility events. 230 Specific MS details are out of scope for this document. 232 Mobility Service Endpoint (MSE) 233 an entity in the MS (either singular or aggregate) that 234 coordinates the mobility events of one or more MN. 236 Mobility Service Prefix (MSP) 237 an aggregated IP Global Unicast Address (GUA) prefix (e.g., 238 2001:db8::/32, 192.0.2.0/24, etc.) assigned to the OMNI link and 239 from which more-specific Mobile Network Prefixes (MNPs) are 240 delegated. OMNI link administrators typically obtain MSPs from an 241 Internet address registry, however private-use prefixes can 242 alternatively be used subject to certain limitations (see: 243 Section 9). OMNI links that connect to the global Internet 244 advertise their MSPs to their interdomain routing peers. 246 Mobile Network Prefix (MNP) 247 a longer IP prefix delegated from an MSP (e.g., 248 2001:db8:1000:2000::/56, 192.0.2.8/30, etc.) and assigned to a MN. 249 MNs sub-delegate the MNP to devices located in EUNs. 251 Access Network (ANET) 252 a data link service network (e.g., an aviation radio access 253 network, satellite service provider network, cellular operator 254 network, wifi network, etc.) that connects MNs. Physical and/or 255 data link level security is assumed, and sometimes referred to as 256 "protected spectrum". Private enterprise networks and ground 257 domain aviation service networks may provide multiple secured IP 258 hops between the MN's point of connection and the nearest Access 259 Router. 261 Access Router (AR) 262 a router in the ANET for connecting MNs to correspondents in 263 outside Internetworks. The AR may be located on the same physical 264 link as the MN, or may be located multiple IP hops away. In the 265 latter case, the MN uses encapsulation to communicate with the AR 266 as though it were on the same phsyical link. 268 ANET interface 269 a MN's attachment to a link in an ANET. 271 Internetwork (INET) 272 a connected network region with a coherent IP addressing plan that 273 provides transit forwarding services between ANETs and nodes that 274 connect directly to the open INET via unprotected media. No 275 physical and/or data link level security is assumed, therefore 276 security must be applied by upper layers. The global public 277 Internet itself is an example. 279 INET interface 280 a node's attachment to a link in an INET. 282 *NET 283 a "wildcard" term used when a given specification applies equally 284 to both ANET and INET cases. 286 OMNI link 287 a Non-Broadcast, Multiple Access (NBMA) virtual overlay configured 288 over one or more INETs and their connected ANETs. An OMNI link 289 can comprise multiple INET segments joined by bridges the same as 290 for any link; the addressing plans in each segment may be mutually 291 exclusive and managed by different administrative entities. 293 OMNI interface 294 a node's attachment to an OMNI link, and configured over one or 295 more underlying *NET interfaces. If there are multiple OMNI links 296 in an OMNI domain, a separate OMNI interface is configured for 297 each link. 299 OMNI Adaptation Layer (OAL) 300 an OMNI interface process whereby packets admitted into the 301 interface are wrapped in a mid-layer IPv6 header and fragmented/ 302 reassembled if necessary to support the OMNI link Maximum 303 Transmission Unit (MTU). The OAL is also responsible for 304 generating MTU-related control messages as necessary, and for 305 providing addressing context for spanning multiple segments of a 306 bridged OMNI link. 308 OMNI Link-Local Address (LLA) 309 a link local IPv6 address per [RFC4291] constructed as specified 310 in Section 7. 312 OMNI Unique-Local Address (DLA) 313 an IPv6 address from a /64 sub-prefix of fd00::/8 constructed as 314 specified in Section 3 of [RFC4193]. OMNI ULAs are statelessly 315 derived from OMNI LLAs, and vice-versa. 317 OMNI Option 318 an IPv6 Neighbor Discovery option providing multilink parameters 319 for the OMNI interface as specified in Section 10. 321 Multilink 322 an OMNI interface's manner of managing diverse underlying 323 interface connections to data links as a single logical unit. The 324 OMNI interface provides a single unified interface to upper 325 layers, while underlying interface selections are performed on a 326 per-packet basis considering factors such as DSCP, flow label, 327 application policy, signal quality, cost, etc. Multilinking 328 decisions are coordinated in both the outbound (i.e. MN to 329 correspondent) and inbound (i.e., correspondent to MN) directions. 331 L2 332 The second layer in the OSI network model. Also known as "layer- 333 2", "link-layer", "sub-IP layer", "data link layer", etc. 335 L3 336 The third layer in the OSI network model. Also known as "layer- 337 3", "network-layer", "IP layer", etc. 339 underlying interface 340 a *NET interface over which an OMNI interface is configured. The 341 OMNI interface is seen as a L3 interface by the IP layer, and each 342 underlying interface is seen as a L2 interface by the OMNI 343 interface. The underlying interface either connects directly to 344 the physical communications media or coordinates with another node 345 where the physical media is hosted. 347 Mobility Service Identification (MSID) 348 Each MSE and AR is assigned a unique 32-bit Identification (MSID) 349 as specified in Section 7. 351 Safety-Based Multilink (SBM) 352 A means for ensuring fault tolerance through redundancy by 353 connecting multiple affiliated OMNI interfaces to independent 354 routing topologies (i.e., multiple independent OMNI links). 356 Performance Based Multilink (PBM) 357 A means for selecting underlying interface(s) for packet 358 transmission and reception within a single OMNI interface. 360 OMNI Domain 361 The set of all SBM/PBM OMNI links that collectively provides 362 services for a common set of MSPs. Each OMNI domain consists of a 363 set of affiliated OMNI links that all configure the same ::/48 ULA 364 prefix with a unique 16-bit Subnet ID as discussed in Section 8. 366 3. Requirements 368 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 369 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 370 "OPTIONAL" in this document are to be interpreted as described in BCP 371 14 [RFC2119][RFC8174] when, and only when, they appear in all 372 capitals, as shown here. 374 OMNI links maintain a constant value "MAX_MSID" selected to provide 375 MNs with an acceptable level of MSE redundancy while minimizing 376 control message amplification. It is RECOMMENDED that MAX_MSID be 377 set to the default value 5; if a different value is chosen, it should 378 be set uniformly by all nodes on the OMNI link. 380 An implementation is not required to internally use the architectural 381 constructs described here so long as its external behavior is 382 consistent with that described in this document. 384 4. Overlay Multilink Network (OMNI) Interface Model 386 An OMNI interface is a MN virtual interface configured over one or 387 more underlying interfaces, which may be physical (e.g., an 388 aeronautical radio link) or virtual (e.g., an Internet or higher- 389 layer "tunnel"). The MN receives a MNP from the MS, and coordinates 390 with the MS through IPv6 ND message exchanges. The MN uses the MNP 391 to construct a unique OMNI LLA through the algorithmic derivation 392 specified in Section 7 and assigns the LLA to the OMNI interface. 394 The OMNI interface architectural layering model is the same as in 395 [RFC5558][RFC7847], and augmented as shown in Figure 1. The IP layer 396 therefore sees the OMNI interface as a single L3 interface with 397 multiple underlying interfaces that appear as L2 communication 398 channels in the architecture. 400 +----------------------------+ 401 | Upper Layer Protocol | 402 Session-to-IP +---->| | 403 Address Binding | +----------------------------+ 404 +---->| IP (L3) | 405 IP Address +---->| | 406 Binding | +----------------------------+ 407 +---->| OMNI Interface | 408 Logical-to- +---->| (OMNI LLA) | 409 Physical | +----------------------------+ 410 Interface +---->| L2 | L2 | | L2 | 411 Binding |(IF#1)|(IF#2)| ..... |(IF#n)| 412 +------+------+ +------+ 413 | L1 | L1 | | L1 | 414 | | | | | 415 +------+------+ +------+ 417 Figure 1: OMNI Interface Architectural Layering Model 419 Each underlying interface provides an L2/L1 abstraction according to 420 one of the following models: 422 o INET interfaces connect to an INET either natively or through one 423 or several IPv4 Network Address Translators (NATs). Native INET 424 interfaces have global IP addresses that are reachable from any 425 INET correspondent. NATed INET interfaces typically have private 426 IP addresses and connect to a private network behind one or more 427 NATs that provide INET access. 429 o ANET interfaces connect to a protected ANET that is separated from 430 the open INET by an AR acting as a proxy. The ANET interface may 431 be either on the same L2 link segment as the AR, or separated from 432 the AR by multiple IP hops. 434 o VPNed interfaces use security encapsulation over a *NET to a 435 Virtual Private Network (VPN) gateway. Other than the link-layer 436 encapsulation format, VPNed interfaces behave the same as for 437 Direct interfaces. 439 o Direct (aka "point-to-point") interfaces connect directly to a 440 peer without crossing any *NET paths. An example is a line-of- 441 sight link between a remote pilot and an unmanned aircraft. 443 The OMNI virtual interface model gives rise to a number of 444 opportunities: 446 o since MN OMNI LLAs are uniquely derived from an MNP, no Duplicate 447 Address Detection (DAD) or Multicast Listener Discovery (MLD) 448 messaging is necessary. 450 o since Temporary OMNI LLAs are statistically unique, they can be 451 used without DAD for short-term purposes, e.g. until an MN OMNI 452 LLA is obtained. 454 o *NET interfaces on the same L2 link segment as an AR do not 455 require any L3 addresses (i.e., not even link-local) in 456 environments where communications are coordinated entirely over 457 the OMNI interface. (An alternative would be to also assign the 458 same OMNI LLA to all *NET interfaces.) 460 o as underlying interface properties change (e.g., link quality, 461 cost, availability, etc.), any active interface can be used to 462 update the profiles of multiple additional interfaces in a single 463 message. This allows for timely adaptation and service continuity 464 under dynamically changing conditions. 466 o coordinating underlying interfaces in this way allows them to be 467 represented in a unified MS profile with provisions for mobility 468 and multilink operations. 470 o exposing a single virtual interface abstraction to the IPv6 layer 471 allows for multilink operation (including QoS based link 472 selection, packet replication, load balancing, etc.) at L2 while 473 still permitting L3 traffic shaping based on, e.g., DSCP, flow 474 label, etc. 476 o the OMNI interface allows inter-INET traversal when nodes located 477 in different INETs need to communicate with one another. This 478 mode of operation would not be possible via direct communications 479 over the underlying interfaces themselves. 481 o the OMNI Adaptation Layer (OAL) within the OMNI interface supports 482 lossless and adaptive path MTU mitigations not available for 483 communications directly over the underlying interfaces themselves. 485 o L3 sees the OMNI interface as a point of connection to the OMNI 486 link; if there are multiple OMNI links (i.e., multiple MS's), L3 487 will see multiple OMNI interfaces. 489 o Multiple independent OMNI interfaces can be used for increased 490 fault tolerance through Safety-Based Multilink (SBM), with 491 Performance-Based Multilink (PBM) applied within each interface. 493 Other opportunities are discussed in [RFC7847]. Note that even when 494 the OMNI virtual interface is present, applications can still access 495 underlying interfaces either through the network protocol stack using 496 an Internet socket or directly using a raw socket. This allows for 497 intra-network (or point-to-point) communications without invoking the 498 OMNI interface and/or OAL. For example, when an IPv6 OMNI interface 499 is configured over an underlying IPv4 interface, applications can 500 still invoke IPv4 intra-network communications as long as the 501 communicating endpoints are not subject to mobility dynamics. 502 However, the opportunities discussed above are not available when the 503 architectural layering is bypassed in this way. 505 Figure 2 depicts the architectural model for a MN with an attached 506 EUN connecting to the MS via multiple independent *NETs. When an 507 underlying interface becomes active, the MN's OMNI interface sends 508 IPv6 ND messages without encapsulation if the first-hop Access Router 509 (AR) is on the same underlying link; otherwise, the interface uses 510 IP-in-IP encapsulation. The IPv6 ND messages traverse the ground 511 domain *NETs until they reach an AR (AR#1, AR#2, ..., AR#n), which 512 then coordinates with an INET Mobility Service Endpoint (MSE#1, 513 MSE#2, ..., MSE#m) and returns an IPv6 ND message response to the MN. 514 The Hop Limit in IPv6 ND messages is not decremented due to 515 encapsulation; hence, the OMNI interface appears to be attached to an 516 ordinary link. 518 +--------------+ (:::)-. 519 | MN |<-->.-(::EUN:::) 520 +--------------+ `-(::::)-' 521 |OMNI interface| 522 +----+----+----+ 523 +--------|IF#1|IF#2|IF#n|------ + 524 / +----+----+----+ \ 525 / | \ 526 / | \ 527 v v v 528 (:::)-. (:::)-. (:::)-. 529 .-(::*NET:::) .-(::*NET:::) .-(::*NET:::) 530 `-(::::)-' `-(::::)-' `-(::::)-' 531 +----+ +----+ +----+ 532 ... |AR#1| .......... |AR#2| ......... |AR#n| ... 533 . +-|--+ +-|--+ +-|--+ . 534 . | | | 535 . v v v . 536 . <----- INET Encapsulation -----> . 537 . . 538 . +-----+ (:::)-. . 539 . |MSE#2| .-(::::::::) +-----+ . 540 . +-----+ .-(::: INET :::)-. |MSE#m| . 541 . (::::: Routing ::::) +-----+ . 542 . `-(::: System :::)-' . 543 . +-----+ `-(:::::::-' . 544 . |MSE#1| +-----+ +-----+ . 545 . +-----+ |MSE#3| |MSE#4| . 546 . +-----+ +-----+ . 547 . . 548 . . 549 . <----- Worldwide Connected Internetwork ----> . 550 ........................................................... 552 Figure 2: MN/MS Coordination via Multiple *NETs 554 After the initial IPv6 ND message exchange, the MN (and/or any nodes 555 on its attached EUNs) can send and receive IP data packets over the 556 OMNI interface. OMNI interface multilink services will forward the 557 packets via ARs in the correct underlying *NETs. The AR encapsulates 558 the packets according to the capabilities provided by the MS and 559 forwards them to the next hop within the worldwide connected 560 Internetwork via optimal routes. 562 OMNI links span one or more underlying Internetwork via the OMNI 563 Adaptation Layer (OAL) which is based on a mid-layer overlay 564 encapsulation using [RFC2473]. Each OMNI link corresponds to a 565 different overlay (differentiated by an address codepoint) which may 566 be carried over a completely separate underlying topology. Each MN 567 can facilitate SBM by connecting to multiple OMNI links using a 568 distinct OMNI interface for each link. 570 Note: OMNI interface underlying interfaces often connect directly to 571 physical media on the local platform (e.g., a laptop computer with 572 WiFi, etc.), but in some configurations the physical media may be 573 hosted on a separate Local Area Network (LAN) node. In that case, 574 the OMNI interface can establish a Layer-2 VLAN or a point-to-point 575 tunnel (at a layer below the underlying interface) to the node 576 hosting the physical media. The OMNI interface may also apply 577 encapsulation at a layer above the underlying interface such that 578 packets would appear "double-encapsulated" on the LAN; the node 579 hosting the physical media in turn removes the LAN encapsulation 580 prior to transmission or inserts it following reception. Finally, 581 the underlying interface must monitor the node hosting the physical 582 media (e.g., through active pingiing) so that it can convey up/down/ 583 status information to the OMNI interface. 585 5. The OMNI Adaptation Layer (OAL) 587 The OMNI interface observes the link nature of tunnels, including the 588 Maximum Transmission Unit (MTU), Maximum Reassembly Unit (MRU) and 589 the role of fragmentation and reassembly [I-D.ietf-intarea-tunnels]. 590 The OMNI interface is configured over one or more underlying 591 interfaces that may have diverse MTUs. OMNI interfaces accommodate 592 MTU diversity through the use of the OMNI Adaptation Layer (OAL) as 593 discussed in this section. 595 IPv6 underlying interfaces are REQUIRED to configure a minimum MTU of 596 1280 bytes and a minimum MRU of 1500 bytes [RFC8200]. Therefore, the 597 minimum IPv6 path MTU is 1280 bytes since routers on the path are not 598 permitted to perform network fragmentation even though the 599 destination is required to reassemble more. The network therefore 600 MUST forward packets of at least 1280 bytes without generating an 601 IPv6 Path MTU Discovery (PMTUD) Packet Too Big (PTB) message 602 [RFC8201]. (Note: the source can apply "source fragmentation" for 603 locally-generated IPv6 packets up to 1500 bytes and larger still if 604 it if has a way to determine that the destination configures a larger 605 MRU, but this does not affect the minimum IPv6 path MTU.) 607 IPv4 underlying interfaces are REQUIRED to configure a minimum MTU of 608 68 bytes [RFC0791] and a minimum MRU of 576 bytes [RFC0791][RFC1122]. 609 Therefore, when the Don't Fragment (DF) bit in the IPv4 header is set 610 to 0 the minimum IPv4 path MTU is 576 bytes since routers on the path 611 support network fragmentation and the destination is required to 612 reassemble at least that much. The DF bit in the IPv4 encapsulation 613 headers of packets sent over IPv4 underlying interfaces therefore 614 MUST be set to 0. (Note: even if the encapsulation source has a way 615 to determine that the encapsulation destination configures an MRU 616 larger than 576 bytes, it should not assume a larger minimum IPv4 617 path MTU without careful consideration of the issues discussed in 618 Section 5.1.) 620 The OMNI interface configures both an MTU and MRU of 9180 bytes 621 [RFC2492]; the size is therefore not a reflection of the underlying 622 interface MTUs, but rather determines the largest packet the OMNI 623 interface can forward or reassemble. The OMNI interface uses the 624 OMNI Adaptation Layer (OAL) to admit packets from the network layer 625 that are no larger than the OMNI interface MTU while generating 626 ICMPv4 Fragmentation Needed [RFC1191] or ICMPv6 Path MTU Discovery 627 (PMTUD) Packet Too Big (PTB) [RFC8201] messages as necessary. This 628 document refers to both of these ICMPv4/ICMPv6 message types simply 629 as "PTBs", and introduces a distinction between PTB "hard" and "soft" 630 errors as discussed below. 632 For IPv4 packets with DF=0, the network layer performs IPv4 633 fragmentation if necessary then admits the packets/fragments into the 634 OMNI interface; these fragments will be reassembled by the final 635 destination. For IPv4 packets with DF=1 and IPv6 packets, the 636 network layer admits the packet if it is no larger than the OMNI 637 interface MTU; otherwise, it drops the packet and returns a PTB hard 638 error message to the source. 640 For each admitted IP packet/fragment, the OMNI interface internally 641 employs the OAL when necessary by inserting a mid-layer IPv6 header 642 between the inner IP packet/fragment and any outer IP encapsulation 643 headers per [RFC2473]. (The OAL does not decrement the inner IP Hop 644 Limit/TTL during enapsulation since the insertion occurs at a layer 645 below IP forwarding.) The OAL then calculates the 32-bit CRC over 646 the entire mid-layer packet and writes the value in a trailing 647 4-octet field at the end of the packet. Next, the OAL fragments this 648 mid-layer IPv6 packet, forwards the fragments (using outer IP 649 encapsulation if necessary), and returns an internally-generated PTB 650 soft error message (subject to rate limiting) if it deems the packet 651 too large according to factors such as link performance 652 characteristics, reassembly congestion, etc. This ensures that the 653 path MTU is adaptive and reflects the current path used for a given 654 data flow. 656 The OAL operates with respect to both the minimum IPv6 and IPv4 path 657 MTUs as follows: 659 o When an OMNI interface sends a packet toward a final destination 660 via an ANET peer, it sends without OAL encapsulation if the packet 661 (including any outer-layer ANET encapsulations) is no larger than 662 the underlying interface MTU for on-link ANET peers or the minimum 663 ANET path MTU for peers separated by multiple IP hops. Otherwise, 664 the OAL inserts an IPv6 header per [RFC2473] with source address 665 set to the node's own OMNI Unique-Local Address (ULA) (see: 666 Section 8) and destination set to the OMNI ULA of the ANET peer. 667 The OAL then calculates and appends the trailing 32-bit CRC, then 668 uses IPv6 fragmentation to break the packet into a minimum number 669 of non-overlapping fragments where the largest fragment size 670 (including both the OMNI and any outer-layer ANET encapsulations) 671 is determined by the underlying interface MTU for on-link ANET 672 peers or the minimum ANET path MTU for peers separated by multiple 673 IP hops. The OAL then encapsulates the fragments in any ANET 674 headers and sends them to the ANET peer, which reassembles before 675 forwarding toward the final destination. 677 o When an OMNI interface sends a packet toward a final destination 678 via an INET interface, it sends packets (including any outer-layer 679 INET encapsulations) no larger than the minimum INET path MTU 680 without OAL encapsulation if the destination is reached via an 681 INET address within the same OMNI link segment. Otherwise, the 682 OAL inserts an IPv6 header per [RFC2473] with source address set 683 to the node's OMNI ULA, destination set to the ULA of the next hop 684 OMNI node toward the final destination and (if necessary) with a 685 Segment Routing Header with the remaining Segment IDs on the path 686 to the final destination. The OAL then calculates and appends the 687 trailing 32-bit CRC, then uses IPv6 fragmentation to break the 688 packet into a minimum number of non-overlapping fragments where 689 the largest fragment size (including both the OMNI and outer-layer 690 INET encapsulations) is the minimum INET path MTU, and the 691 smallest fragment size is no smaller than 256 bytes (i.e., 692 slightly less than half the minimum IPv4 path MTU). The OAL then 693 encapsulates the fragments in any INET headers and sends them to 694 the OMNI link neighbor, which reassembles before forwarding toward 695 the final destination. 697 The OAL unconditionally drops all OAL fragments received from an INET 698 peer that are smaller than 256 bytes (note that no minimum fragment 699 size is specified for ANET peers since the underlying ANET is secured 700 against tiny fragment attacks). In order to set the correct context 701 for reassembly, the OAL of the OMNI interface that inserts the IPv6 702 header MUST also be the one that inserts the IPv6 Fragment Header 703 Identification value. While not strictly required, sending all 704 fragments of the same fragmented OAL packet consecutively over the 705 same underlying interface with minimal inter-fragment delay may 706 increase the likelihood of successful reassembly. 708 Ordinary PTB messages with ICMPv4 header "unused" field or ICMPv6 709 header Code field value 0 are hard errors that always indicate that a 710 packet has been dropped due to a real MTU restriction. However, the 711 OAL can also forward large packets via encapsulation and 712 fragmentation while at the same time returning PTB soft error 713 messages (subject to rate limiting) indicating that a forwarded 714 packet was uncomfortably large. The OMNI interface can therefore 715 continuously forward large packets without loss while returning PTB 716 soft error messages recommending a smaller size. Original sources 717 that receive the soft errors in turn reduce the size of the packets 718 they send, i.e., the same as for hard errors. 720 The OAL sets the ICMPv4 header "unused" field or ICMPv6 header Code 721 field to the value 1 in PTB soft error messages. The OAL sets the 722 PTB destination address to the source address of the original packet, 723 and sets the source address to the MNP Subnet Router Anycast address 724 of the MN (i.e., whether the MN was the source or target of the 725 original packet). When the original source receives the PTB, it 726 reduces its path MTU estimate the same as for hard errors but does 727 not regard the message as a loss indication. (If the original source 728 does not recognize the soft error code, it regards the PTB the same 729 as a hard error but should heed the retransmission advice given in 730 [RFC8201] suggesting retransmission based on normal packetization 731 layer retransmission timers.) This document therefore updates 732 [RFC1191][RFC4443] and [RFC8201]. Furthermore, implementations of 733 [RFC4821] must be aware that PTB hard or soft errors may arrive at 734 any time even if after a successful MTU probe (this is the same 735 consideration as for an ordinary path fluctuation following a 736 successful probe). 738 In summary, the OAL supports continuous transmission and reception of 739 packets of various sizes in the face of dynamically changing network 740 conditions. Moreover, since PTB soft errors do not indicate loss, 741 original sources that receive soft errors can quickly scan for path 742 MTU increases without waiting for the minimum 10 minutes specified 743 for loss-oriented PTB hard errors [RFC1191][RFC8201]. The OAL 744 therefore provides a lossless and adaptive service that accommodates 745 MTU diversity especially well-suited for dynamic multilink 746 environments. 748 Note: In network paths where IPv6/IPv4 protocol translation or IPv6- 749 in-IPv4 encapsulation may be prevalent, it may be prudent for the OAL 750 to always assume the IPv4 minimum path MTU (i.e., 576 bytes) 751 regardless of the underlying interface IP protocol version. Always 752 assuming the IPv4 minimum path MTU even for IPv6 underlying 753 interfaces may produce more fragments and additional header overhead, 754 but will always interoperate and never run the risk of presenting an 755 IPv4 interface with a packet that exceeds its MRU. 757 Note: An OMNI interface that reassembles OAL fragments may experience 758 congestion-oriented loss in its reassembly cache and can optionally 759 send PTB soft errors to the original source and/or ICMP "Time 760 Exceeded" messages to the source of the OAL fragments. In 761 environments where the messages may contribute to unacceptable 762 additional congestion, however, the OMNI interface can simply regard 763 the loss as an ordinary unreported congestion event for which the 764 original source will eventually compensate. 766 Note: When the network layer forwards an IPv4 packet/fragment with 767 DF=0 into the OMNI interface, the interface can optionally perform 768 (further) IPv4 fragmentation before invoking the OAL so that the 769 fragments will be reassembled by the final destination. When the 770 network layer performs IPv6 fragmentation for locally-generated IPv6 771 packets, the OMNI interface typically invokes the OAL without first 772 applying (further) IPv6 fragmentation; the network layer should 773 therefore fragment to the minimum IPv6 path MTU (or smaller still) to 774 push the reassembly burden to the final destination and avoid 775 receiving PTB soft errors from the OMNI interface. Aside from these 776 non-normative guidelines, the manner in which any IP fragmentation is 777 invoked prior to OAL encapsulation/fragmentation is an implementation 778 matter. 780 Note: Inclusion of the 32-bit CRC prior to fragmentation assumes that 781 the receiving OAL will discard any packets with incorrect CRC values 782 following reassembly. The 32-bit CRC is sufficient to detect 783 reassembly misassociations for packet sizes up to the OMNI interface 784 MTU 9180 but may not be sufficient to detect errors for larger sizes 785 [CRC]. 787 Note: Some underlying interface types (e.g., VPNs) may already 788 provide their own robust fragmentation and reassembly services even 789 without OAL encapsulation. In those cases, the OAL can invoke the 790 inherent underlying interface schemes instead while employing PTB 791 soft errors in the same fashion as described above. Other underlying 792 interface properties such as header/message compression can also be 793 harnessed in a similar fashion. 795 Note: Applications can dynamically tune the size of the packets they 796 to send to produce the best possible throughput and latency, with the 797 understanding that these parameters may change over time due to 798 factors such as congestion, mobility, network path changes, etc. The 799 receipt or absence of soft errors should be seen as hints of when 800 increasing or decreasing packet sizes may be beneficial. 802 5.1. Fragmentation Security Implications 804 As discussed in Section 3.7 of [RFC8900], there are four basic 805 threats concerning IPv6 fragmentation; each of which is addressed by 806 effective mitigations as follows: 808 1. Overlapping fragment attacks - reassembly of overlapping 809 fragments is forbidden by [RFC8200]; therefore, this threat does 810 not apply to the OAL. 812 2. Resource exhaustion attacks - this threat is mitigated by 813 providing a sufficiently large OAL reassembly cache and 814 instituting "fast discard" of incomplete reassemblies that may be 815 part of a buffer exhaustion attack. The reassembly cache should 816 be sufficiently large so that a sustained attack does not cause 817 excessive loss of good reassemblies but not so large that (timer- 818 based) data structure management becomes computationally 819 expensive. The cache should also be indexed based on the arrival 820 underlying interface such that congestion experienced over a 821 first underlying interface does not cause discard of incomplete 822 reassemblies for uncongested underlying interfaces. 824 3. Attacks based on predictable fragment identification values - 825 this threat is mitigated by selecting a suitably random ID value 826 per [RFC7739]. 828 4. Evasion of Network Intrusion Detection Systems (NIDS) - this 829 threat is mitigated by disallowing "tiny fragments" per the OAL 830 fragmentation procedures specified above. 832 Additionally, IPv4 fragmentation includes a 16-bit Identification (IP 833 ID) field with only 65535 unique values such that at high data rates 834 the field could wrap and apply to new packets while the fragments of 835 old packets using the same ID are still alive in the network 836 [RFC4963]. However, since the largest OAL fragment that will be sent 837 via an IPv4 *NET path is 576 bytes any IPv4 fragmentation would occur 838 only on links with an IPv4 MTU smaller than this size, and [RFC3819] 839 recommendations suggest that such links will have low data rates. 840 Since IPv6 provides a 32-bit Identification value, IP ID wraparound 841 at high data rates is not a concern for IPv6 fragmentation. 843 6. Frame Format 845 The OMNI interface transmits IPv6 packets according to the native 846 frame format of each underlying interface. For example, for 847 Ethernet-compatible interfaces the frame format is specified in 848 [RFC2464], for aeronautical radio interfaces the frame format is 849 specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical 850 Manual), for tunnels over IPv6 the frame format is specified in 851 [RFC2473], etc. 853 7. Link-Local Addresses (LLAs) 855 OMNI nodes are assigned OMNI interface IPv6 Link-Local Addresses 856 (i.e., "OMNI LLAs") through pre-service administrative actions. MN 857 OMNI LLAs embed the MNP assigned to the mobile node, while MS OMNI 858 LLAs include an administratively-unique ID that is guaranteed to be 859 unique on the link. OMNI LLAs are configured as follows: 861 o IPv6 MN OMNI LLAs encode the most-significant 64 bits of a MNP 862 within the least-significant 64 bits of the IPv6 link-local prefix 863 fe80::/64, i.e., in the LLA "interface identifier" portion. The 864 prefix length for the LLA is determined by adding 64 to the MNP 865 prefix length. For example, for the MNP 2001:db8:1000:2000::/56 866 the corresponding MN OMNI LLA is fe80::2001:db8:1000:2000/120. 868 o IPv4-compatible MN OMNI LLAs are constructed as fe80::ffff:[IPv4], 869 i.e., the interface identifier consists of 16 '0' bits, followed 870 by 16 '1' bits, followed by a 32bit IPv4 address/prefix. The 871 prefix length for the LLA is determined by adding 96 to the MNP 872 prefix length. For example, the IPv4-Compatible MN OMNI LLA for 873 192.0.2.0/24 is fe80::ffff:192.0.2.0/120 (also written as 874 fe80::ffff:c000:0200/120). 876 o MS OMNI LLAs are assigned to ARs and MSEs and MUST be managed for 877 uniqueness. The lower 32 bits of the LLA includes a unique 878 integer "MSID" value between 0x00000001 and 0xfeffffff, e.g., as 879 in fe80::1, fe80::2, fe80::3, etc., fe80::feff:ffff. The MS OMNI 880 LLA prefix length is determined by adding 96 to the MSID prefix 881 length. For example, if the MSID '0x10002000' prefix length is 16 882 then the MS OMNI LLA prefix length is set to 112 and the LLA is 883 written as fe80::1000:2000/112. The MSID 0x00000000 is the 884 "Anycast" MSID and corresponds to the link-local Subnet-Router 885 anycast address (fe80::) [RFC4291]; the MSID range 0xff000000 886 through 0xffffffff is reserved for future use. 888 o Temporary OMNI LLAs are constructed per [I-D.ietf-6man-rfc4941bis] 889 and used by MNs for the short-term purpose of procuring an actual 890 MN OMNI LLA upon startup or (re)connecting to the network. MNs 891 may use Temporary OMNI LLAs as the IPv6 source address of an RS 892 message in order to request a MN OMNI LLA from the MS. 894 Since the prefix 0000::/8 is "Reserved by the IETF" [RFC4291], no 895 MNPs can be allocated from that block ensuring that there is no 896 possibility for overlap between the various OMNI LLA constructs 897 discussed above. 899 Since MN OMNI LLAs are based on the distribution of administratively 900 assured unique MNPs, and since MS OMNI LLAs are guaranteed unique 901 through administrative assignment, OMNI interfaces set the 902 autoconfiguration variable DupAddrDetectTransmits to 0 [RFC4862]. 904 Temporary OMNI LLAs employ optimistic DAD principles [RFC4429] since 905 they are probabilistically unique and their use is short-duration in 906 nature. 908 Note: If future extensions of the IPv6 protocol permit extension of 909 the /64 boundary, the additional prefix bits of IPv6 MN OMNI LLAs 910 would be encoded in bits 16 through 63 of the LLA. (The most- 911 significant 64 bits would therefore still be in LLA bits 64-127, and 912 the remaining bits would be in bits 16 through 48 of the LLA. This 913 would permit encoding of IPv6 prefix lengths up to /112.) 915 8. Unique-Local Addresses (ULAs) 917 OMNI domains use IPv6 Unique-Local Addresses (i.e., "OMNI ULAs") as 918 the source and destination addresses in OAL IPv6 encapsulation 919 headers. OMNI ULAs are only routable within the scope of a an OMNI 920 domain, and are derived from the IPv6 Unique Local Address (ULA) 921 prefix fc00::/7 followed by the L bit set to 1 (i.e., as fd00::/8) 922 followed by a 40-bit pseudo-random Global ID to produce the prefix 923 [ULA]::/48, which is then followed by a 16-bit Subnet ID then finally 924 followed by a 64 bit Interface ID as specified in Section 3 of 925 [RFC4193]. The statistic uniqueness of the 40-bit pseudo-random 926 Global ID allows different OMNI domains to be joined together at a 927 later time. 929 Each OMNI link instance is identified by a value between 0x0000 and 930 0xfeff in bits 48-63 of [ULA]::/48 (the values 0xff00 through 0xfffe 931 are reserved for future use and the value 0xffff denotes a Temporary 932 OMNI ULA). For example, OMNI ULAs associated with instance 0 are 933 configured from the prefix [ULA]:0000::/64, instance 1 from 934 [ULA]:0001::/64, instance 2 from [ULA]:0002::/64, etc. OMNI ULAs and 935 their associated prefix lengths are configured in correspondence with 936 OMNI LLAs through stateless prefix translation. For example, for 937 OMNI link instance [ULA]:1010::/64: 939 o the OMNI ULA corresponding to the MN OMNI LLA fe80::2001:db8:1:2 940 with a 56-bit MNP length is derived by copying the lower 64 bits 941 of the LLA into the lower 64 bits of the ULA as 942 [ULA]:1010:2001:db8:1:2/120 (where, the ULA prefix length becomes 943 64 plus the IPv6 MNP length). 945 o the OMNI ULA corresponding to fe80::ffff:192.0.2.0 with a 28-bit 946 MNP length is derived by simply writing the LLA interface ID into 947 the lower 64 bits as [ULA]:1010:0:ffff:192.0.2.0/124 (where, the 948 ULA prefix length is 64 plus 32 plus the IPv4 MNP length). 950 o the OMNI ULA corresponding to fe80::1000/112 is simply 951 [ULA]:1010::1000/112. 953 o the OMNI ULA corresponding to fe80::/128 is simply 954 [ULA]:1010::/128. 956 o the OMNI ULA corresponding to a Temporary OMNI LLA is simply 957 [ULA]:ffff:[64-bit Temporary Interface ID]/128. 959 o etc. 961 Each OMNI interface assigns the Anycast OMNI ULA specific to the OMNI 962 link instance. For example, the OMNI interface connected to instance 963 3 assigns the Anycast OMNI ULA [ULA]:0003::/128. Routers that 964 configure OMNI interfaces advertise the OMNI service prefix (e.g., 965 [ULA]:0003::/64) into the local routing system so that applications 966 can direct traffic according to SBM requirements. 968 The OMNI ULA presents an IPv6 address format that is routable within 969 the OMNI routing system and can be used to convey link-scoped IPv6 ND 970 messages across multiple hops using IPv6 encapsulation [RFC2473]. 971 The OMNI link extends across one or more underling Internetworks to 972 include all ARs and MSEs. All MNs are also considered to be 973 connected to the OMNI link, however OAL encapsulation is omitted 974 whenever possible to conserve bandwidth (see: Section 12). 976 Each OMNI link can be subdivided into "segments" that often 977 correspond to different administrative domains or physical 978 partitions. OMNI nodes can use IPv6 Segment Routing [RFC8402] when 979 necessary to support efficient packet forwarding to destinations 980 located in other OMNI link segments. A full discussion of Segment 981 Routing over the OMNI link appears in [I-D.templin-intarea-6706bis]. 983 Note: IPv6 ULAs taken from the prefix fc00::/7 followed by the L bit 984 set to 0 (i.e., as fc00::/8) are never used for OMNI OAL addressing, 985 however the range could be used for MSP and MNP addressing under 986 certain limiting conditions (see: Section 9). 988 9. Global Unicast Addresses (GUAs) 990 OMNI domains use IP Global Unicast Address (GUA) prefixes [RFC4291] 991 as Mobility Service Prefixes (MSPs) from which Mobile Network 992 Prefixes (MNP) are delegated to Mobile Nodes (MNs). 994 For IPv6, GUA prefixes are assigned by IANA [IPV6-GUA] and/or an 995 associated regional assigned numbers authority such that the OMNI 996 domain can be interconnected to the global IPv6 Internet without 997 causing inconsistencies in the routing system. An OMNI domain could 998 instead use ULAs with the 'L' bit set to 0 (i.e., from the prefix 999 fc00::/8)[RFC4193], however this would require IPv6 Network Address 1000 Translation (NAT) if the domain were ever connected to the global 1001 IPv6 Internet. 1003 For IPv4, GUA prefixes are assigned by IANA [IPV4-GUA] and/or an 1004 associated regional assigned numbers authority such that the OMNI 1005 domain can be interconnected to the global IPv4 Internet without 1006 causing routing inconsistencies. An OMNI domain could instead use 1007 private IPv4 prefixes (e.g., 10.0.0.0/8, etc.) [RFC3330], however 1008 this would require IPv4 NAT if the domain were ever connected to the 1009 global IPv4 Internet. 1011 10. Address Mapping - Unicast 1013 OMNI interfaces maintain a neighbor cache for tracking per-neighbor 1014 state and use the link-local address format specified in Section 7. 1015 OMNI interface IPv6 Neighbor Discovery (ND) [RFC4861] messages sent 1016 over physical underlying interfaces without encapsulation observe the 1017 native underlying interface Source/Target Link-Layer Address Option 1018 (S/TLLAO) format (e.g., for Ethernet the S/TLLAO is specified in 1019 [RFC2464]). OMNI interface IPv6 ND messages sent over underlying 1020 interfaces via encapsulation do not include S/TLLAOs which were 1021 intended for encoding physical L2 media address formats and not 1022 encapsulation IP addresses. Furthermore, S/TLLAOs are not intended 1023 for encoding additional interface attributes needed for multilink 1024 coordination. Hence, this document does not define an S/TLLAO format 1025 but instead defines a new option type termed the "OMNI option" 1026 designed for these purposes. 1028 MNs such as aircraft typically have many wireless data link types 1029 (e.g. satellite-based, cellular, terrestrial, air-to-air directional, 1030 etc.) with diverse performance, cost and availability properties. 1031 The OMNI interface would therefore appear to have multiple L2 1032 connections, and may include information for multiple underlying 1033 interfaces in a single IPv6 ND message exchange. OMNI interfaces use 1034 an IPv6 ND option called the OMNI option formatted as shown in 1035 Figure 3: 1037 0 1 2 3 1038 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 1039 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1040 | Type | Length |T| Preflen | S/T-ifIndex | 1041 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1042 | | 1043 ~ Sub-Options ~ 1044 | | 1045 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1047 Figure 3: OMNI Option Format 1049 In this format: 1051 o Type is set to TBD. If multiple OMNI option instances appear in 1052 the same IPv6 ND message, the first instance is processed and all 1053 other instances are ignored. 1055 o Length is set to the number of 8 octet blocks in the option. 1057 o T is a 1-bit flag set to 1 for Temporary OMNI LLAs (otherwise, set 1058 to 0) and Preflen is a 7 bit field that determines the length of 1059 prefix associated with an MN OMNI LLA. Values 1 through 127 1060 specify a prefix length, while the value 0 indicates 1061 "unspecified". For IPv6 ND messages sent from a MN to the MS, T 1062 and Preflen apply to the IPv6 source LLA and provide the length 1063 that the MN is requesting or asserting to the MS. For IPv6 ND 1064 messages sent from the MS to the MN, T and Preflen apply to the 1065 IPv6 destination LLA and indicate the length that the MS is 1066 granting to the MN. For IPv6 ND messages sent between MS 1067 endpoints, T is set to 0 and Preflen provides the length 1068 associated with the source/target MN that is subject of the ND 1069 message. 1071 o S/T-ifIndex corresponds to the ifIndex value for source or target 1072 underlying interface used to convey this IPv6 ND message. OMNI 1073 interfaces MUST number each distinct underlying interface with an 1074 ifIndex value between '1' and '255' that represents a MN-specific 1075 8-bit mapping for the actual ifIndex value assigned by network 1076 management [RFC2863] (the ifIndex value '0' is reserved for use by 1077 the MS). For RS and NS messages, S/T-ifIndex corresponds to the 1078 source underlying interface the message originated from. For RA 1079 and NA messages, S/T-ifIndex corresponds to the target underlying 1080 interface that the message is destined to. 1082 o Sub-Options is a Variable-length field, of length such that the 1083 complete OMNI Option is an integer multiple of 8 octets long. 1084 Contains one or more Sub-Options, as described in Section 10.1. 1086 10.1. Sub-Options 1088 The OMNI option includes zero or more Sub-Options. Each consecutive 1089 Sub-Option is concatenated immediately after its predecessor. All 1090 Sub-Options except Pad1 (see below) are in type-length-value (TLV) 1091 encoded in the following format: 1093 0 1 2 1094 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 1095 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1096 | Sub-Type | Sub-length | Sub-Option Data ... 1097 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1099 Figure 4: Sub-Option Format 1101 o Sub-Type is a 1-octet field that encodes the Sub-Option type. 1102 Sub-Options defined in this document are: 1104 Option Name Sub-Type 1105 Pad1 0 1106 PadN 1 1107 Interface Attributes 2 1108 Traffic Selector 3 1109 MS-Register 4 1110 MS-Release 5 1111 Network Access Identifier 6 1112 Geo Coordinates 7 1113 DHCP Unique Identifier (DUID) 8 1114 DHCPv6 Message 9 1116 Figure 5 1118 Sub-Types 253 and 254 are reserved for experimentation, as 1119 recommended in [RFC3692]. 1121 o Sub-Length is a 1-octet field that encodes the length of the Sub- 1122 Option Data (i.e., ranging from 0 to 255 octets). 1124 o Sub-Option Data is a block of data with format determined by Sub- 1125 Type. 1127 During processing, unrecognized Sub-Options are ignored and the next 1128 Sub-Option processed until the end of the OMNI option is reached. 1130 The following Sub-Option types and formats are defined in this 1131 document: 1133 10.1.1. Pad1 1135 0 1136 0 1 2 3 4 5 6 7 1137 +-+-+-+-+-+-+-+-+ 1138 | Sub-Type=0 | 1139 +-+-+-+-+-+-+-+-+ 1141 Figure 6: Pad1 1143 o Sub-Type is set to 0. If multiple instances appear in the same 1144 OMNI option all are processed. 1146 o No Sub-Length or Sub-Option Data follows (i.e., the "Sub-Option" 1147 consists of a single zero octet). 1149 10.1.2. PadN 1151 0 1 2 1152 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 1153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1154 | Sub-Type=1 | Sub-length=N | N padding octets ... 1155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1157 Figure 7: PadN 1159 o Sub-Type is set to 1. If multiple instances appear in the same 1160 OMNI option all are processed. 1162 o Sub-Length is set to N (from 0 to 255) being the number of padding 1163 octets that follow. 1165 o Sub-Option Data consists of N zero-valued octets. 1167 10.1.3. Interface Attributes 1169 The Interface Attributes sub-option provides L2 forwarding 1170 information for the multilink conceptual sending algorithm discussed 1171 in Section 12. The L2 information is used for selecting among 1172 potentially multiple candidate underlying interfaces that can be used 1173 to forward packets to the neighbor based on factors such as DSCP 1174 preferences and link quality. Interface Attributes further include 1175 link-layer address information to be used for either OAL 1176 encapsulation or direct UDP/IP encapsulation (when OAL encapsulation 1177 can be avoided). The Interface Attributes format and contents are 1178 given in Figure 8 below: 1180 0 1 2 3 1181 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 1182 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1183 | Sub-Type=2 | Sub-length=N | ifIndex | ifType | 1184 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1185 | Provider ID | Link |R| API | SRT | FMT | LHS (0 - 7) | 1186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1187 | LHS (bits 8 - 31) | ~ 1188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1189 ~ ~ 1190 ~ Link Layer Address (L2ADDR) ~ 1191 ~ ~ 1192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1193 | Bitmap(0)=0xff|P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11| 1194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1195 |P12|P13|P14|P15|P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27| 1196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1197 |P28|P29|P30|P31| Bitmap(1)=0xff|P32|P33|P34|P35|P36| ... 1198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1200 Figure 8: Interface Attributes 1202 o Sub-Type is set to 2. If multiple instances with different 1203 ifIndex values appear in the same OMNI option all are processed; 1204 if multiple instances with the same ifIndex value appear, the 1205 first is processed and all others are ignored. 1207 o Sub-Length is set to N (from 4 to 255) that encodes the number of 1208 Sub-Option Data octets that follow. 1210 o Sub-Option Data contains an "Interface Attribute" option encoded 1211 as follows (note that the first four octets must be present): 1213 * ifIndex is set to an 8-bit integer value corresponding to a 1214 specific underlying interface the same as specified above for 1215 the OMNI option header S/T-ifIndex. An OMNI option may include 1216 multiple Interface Attributes Sub-Options, with each distinct 1217 ifIndex value pertaining to a different underlying interface. 1218 The OMNI option will often include an Interface Attributes Sub- 1219 Option with the same ifIndex value that appears in the S/ 1220 T-ifIndex. In that case, the actual encapsulation address of 1221 the received IPv6 ND message should be compared with the L2ADDR 1222 encoded in the Sub-Option (see below); if the addresses are 1223 different (or, if L2ADDR absent) the presence of a Network 1224 Address Translator (NAT) is indicated. 1226 * ifType is set to an 8-bit integer value corresponding to the 1227 underlying interface identified by ifIndex. The value 1228 represents an OMNI interface-specific 8-bit mapping for the 1229 actual IANA ifType value registered in the 'IANAifType-MIB' 1230 registry [http://www.iana.org]. 1232 * Provider ID is set to an OMNI interface-specific 8-bit ID value 1233 for the network service provider associated with this ifIndex. 1235 * Link encodes a 4-bit link metric. The value '0' means the link 1236 is DOWN, and the remaining values mean the link is UP with 1237 metric ranging from '1' ("lowest") to '15' ("highest"). 1239 * R is reserved for future use. 1241 * API - a 3-bit "Address/Preferences/Indexed" code that 1242 determines the contents of the remainder of the sub-option as 1243 follows: 1245 + When the most significant bit (i.e., "Address") is set to 1, 1246 the SRT, FMT, LHS and L2ADDR fields are included immediately 1247 following the API code; else, they are omitted. 1249 + When the next most significant bit (i.e., "Preferences") is 1250 set to 1, a preferences block is included next; else, it is 1251 omitted. (Note that if "Address" is set the preferences 1252 block immediately follows L2ADDR; else, it immediately 1253 follows the API code.) 1255 + When a preferences block is present and the least 1256 significant bit (i.e., "Indexed") is set to 0, the block is 1257 encoded in "Simplex" form as shown in Figure 8; else it is 1258 encoded in "Indexed" form as discussed below. 1260 * When API indicates that an "Address" is included, the following 1261 fields appear in consecutive order (else, they are omitted): 1263 + SRT - a 5-bit Segment Routing Topology prefix length value 1264 that (when added to 96) determines the prefix length to 1265 apply to the ULA formed from concatenating fe*::/96 with the 1266 32 bit LHS MSID value that follows. For example, the value 1267 16 corresponds to the prefix length 112. 1269 + FMT - a 3-bit "Framework/Mode/Type" code corresponding to 1270 the included Link Layer Address as follows: 1272 - When the most significant bit (i.e., "Framework") is set 1273 to 0, L2ADDR is the INET encapsulation address of a 1274 Proxy/Server; otherwise, it is the address for the 1275 Source/Target itself 1277 - When the next most significant bit (i.e., "Mode") is set 1278 to 0, the Source/Target L2ADDR is on the open INET; 1279 otherwise, it is (likely) located behind a Network 1280 Address Translator (NAT). 1282 - When the least significant bit (i.e., "Type") is set to 1283 0, L2ADDR includes a UDP Port Number followed by an IPv4 1284 address; else, a UDP Port Number followed by an IPv6 1285 address. 1287 + LHS - the 32 bit MSID of the Last Hop Server/Proxy on the 1288 path to the target. When SRT and LHS are both set to 0, the 1289 LHS is considered unspecified in this IPv6 ND message. When 1290 SRT is set to 0 and LHS is non-zero, the prefix length is 1291 set to 128. SRT and LHS provide guidance to the OMNI 1292 interface forwarding algorithm. Specifically, if SRT/LHS is 1293 located in the local OMNI link segment then the OMNI 1294 interface can encapsulate according to FMT/L2ADDR; else, it 1295 must forward according to the OMNI link spanning tree. See 1296 [I-D.templin-intarea-6706bis] for further discussion. 1298 + Link Layer Address (L2ADDR) - Formatted according to FMT, 1299 and identifies the link-layer address (i.e., the 1300 encapsulation address) of the source/target. The UDP Port 1301 Number appears in the first two octets and the IP address 1302 appears in the next 4 octets for IPv4 or 16 octets for IPv6. 1303 The Port Number and IP address are recorded in ones- 1304 compliment "obfuscated" form per [RFC4380]. The OMNI 1305 interface forwarding algorithm uses FMT/L2ADDR to determine 1306 the encapsulation address for forwarding when SRT/LHS is 1307 located in the local OMNI link segment. 1309 * When API indicates that "Preferences" are included, a 1310 preferences block appears as the remainder of the Sub-Option as 1311 a series of Bitmaps and P[*] values. In "Simplex" form, the 1312 index for each singleton Bitmap octet is inferred from its 1313 sequential position (i.e., 0, 1, 2, ...) as shown in Figure 8. 1314 In "Indexed" form, each Bitmap is preceded by an Index octet 1315 that encodes a value "i" = (0 - 255) as the index for its 1316 companion Bitmap as follows: 1318 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1319 | Index=i | Bitmap(i) |P[*] values ... 1320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 1322 Figure 9 1324 * The preferences consist of a first (simplex/indexed) Bitmap 1325 (i.e., "Bitmap(i)") followed by 0-8 single-octet blocks of 1326 2-bit P[*] values, followed by a second Bitmap (i), followed by 1327 0-8 blocks of P[*] values, etc. Reading from bit 0 to bit 7, 1328 the bits of each Bitmap(i) that are set to '1'' indicate the 1329 P[*] blocks from the range P[(i*32)] through P[(i*32) + 31] 1330 that follow; if any Bitmap(i) bits are '0', then the 1331 corresponding P[*] block is instead omitted. For example, if 1332 Bitmap(0) contains 0xff then the block with P[00]-P[03], 1333 followed by the block with P[04]-P[07], etc., and ending with 1334 the block with P[28]-P[31] are included (as shown in Figure 8). 1335 The next Bitmap(i) is then consulted with its bits indicating 1336 which P[*] blocks follow, etc. out to the end of the Sub- 1337 Option. 1339 * Each 2-bit P[*] field is set to the value '0' ("disabled"), '1' 1340 ("low"), '2' ("medium") or '3' ("high") to indicate a QoS 1341 preference for underlying interface selection purposes. Not 1342 all P[*] values need to be included in the OMNI option of each 1343 IPv6 ND message received. Any P[*] values represented in an 1344 earlier OMNI option but omitted in the current OMNI option 1345 remain unchanged. Any P[*] values not yet represented in any 1346 OMNI option default to "medium". 1348 * The first 16 P[*] blocks correspond to the 64 Differentiated 1349 Service Code Point (DSCP) values P[00] - P[63] [RFC2474]. Any 1350 additional P[*] blocks that follow correspond to "pseudo-DSCP" 1351 traffic classifier values P[64], P[65], P[66], etc. See 1352 Appendix A for further discussion and examples. 1354 10.1.4. Traffic Selector 1356 0 1 2 3 1357 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 1358 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1359 | Sub-Type=3 | Sub-length=N | ifIndex | ~ 1360 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ 1361 ~ ~ 1362 ~ RFC 6088 Format Traffic Selector ~ 1363 ~ ~ 1364 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1366 Figure 10: Traffic Selector 1368 o Sub-Type is set to 3. If multiple instances appear in the same 1369 OMNI option all are processed, i.e., even if the same ifIndex 1370 value appears multiple times. 1372 o Sub-Length is set to N (the number of Sub-Option Data octets that 1373 follow). 1375 o Sub-Option Data contains a 1-octet ifIndex encoded exactly as 1376 specified in Section 10.1.3, followed by an N-1 octet traffic 1377 selector formatted per [RFC6088] beginning with the "TS Format" 1378 field. The largest traffic selector for a given ifIndex is 1379 therefore 254 octets. 1381 10.1.5. MS-Register 1383 0 1 2 3 1384 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 1385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1386 | Sub-Type=4 | Sub-length=4n | MSID[1] (bits 0 - 15) | 1387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1388 | MSID [1] (bits 16 - 32) | MSID[2] (bits 0 - 15) | 1389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1390 | MSID [2] (bits 16 - 32) | MSID[3] (bits 0 - 15) | 1391 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1392 ... ... ... ... ... ... 1393 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1394 | MSID [n] (bits 16 - 32) | 1395 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1397 Figure 11: MS-Register Sub-option 1399 o Sub-Type is set to 4. If multiple instances appear in the same 1400 OMNI option all are processed. Only the first MAX_MSID values 1401 processed (whether in a single instance or multiple) are retained 1402 and all other MSIDs are ignored. 1404 o Sub-Length is set to 4n. 1406 o A list of n 4-octet MSIDs is included in the following 4n octets. 1407 The Anycast MSID value '0' in an RS message MS-Register sub-option 1408 requests the recipient to return the MSID of a nearby MSE in a 1409 corresponding RA response. 1411 10.1.6. MS-Release 1412 0 1 2 3 1413 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 1414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1415 | Sub-Type=5 | Sub-length=4n | MSID[1] (bits 0 - 15) | 1416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1417 | MSID [1] (bits 16 - 32) | MSID[2] (bits 0 - 15) | 1418 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1419 | MSID [2] (bits 16 - 32) | MSID[3] (bits 0 - 15) | 1420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1421 ... ... ... ... ... ... 1422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1423 | MSID [n] (bits 16 - 32) | 1424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1426 Figure 12: MS-Release Sub-option 1428 o Sub-Type is set to 5. If multiple instances appear in the same 1429 IPv6 OMNI option all are processed. Only the first MAX_MSID 1430 values processed (whether in a single instance or multiple) are 1431 retained and all other MSIDs are ignored. 1433 o Sub-Length is set to 4n. 1435 o A list of n 4 octet MSIDs is included in the following 4n octets. 1436 The Anycast MSID value '0' is ignored in MS-Release sub-options, 1437 i.e., only non-zero values are processed. 1439 10.1.7. Network Access Identifier (NAI) 1441 0 1 2 3 1442 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 1443 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1444 | Sub-Type=6 | Sub-length=N |Network Access Identifier (NAI) 1445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... 1447 Figure 13: Network Access Identifier (NAI) Sub-option 1449 o Sub-Type is set to 6. If multiple instances appear in the same 1450 OMNI option the first is processed and all others are ignored. 1452 o Sub-Length is set to N. 1454 o A Network Access Identifier (NAI) up to 255 octets in length is 1455 coded per [RFC7542]. 1457 10.1.8. Geo Coordinates 1459 0 1 2 3 1460 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 1461 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1462 | Sub-Type=7 | Sub-length=N | Geo Coordinates 1463 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... 1465 Figure 14: Geo Coordinates Sub-option 1467 o Sub-Type is set to 7. If multiple instances appear in the same 1468 OMNI option the first is processed and all others are ignored. 1470 o Sub-Length is set to N. 1472 o A set of Geo Coordinates up to 255 octets in length (format TBD). 1473 Includes Latitude/Longitude at a minimum; may also include 1474 additional attributes such as altitude, heading, speed, etc.). 1476 10.1.9. DHCP Unique Identifier (DUID) 1478 0 1 2 3 1479 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 1480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1481 | Sub-Type=8 | Sub-length=N | DUID-Type | 1482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1483 . . 1484 . type-specific DUID body (variable length) . 1485 . . 1486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1488 Figure 15: DHCP Unique Identifier (DUID) Sub-option 1490 o Sub-Type is set to 8. If multiple instances appear in the same 1491 OMNI option the first is processed and all others are ignored. 1493 o Sub-Length is set to N (i.e., the length of the option beginning 1494 with the DUID-Type and continuing to the end of the type-specific 1495 body). 1497 o DUID-Type is a two-octet field coded in network byte order that 1498 determines the format and contents of the type-specific body 1499 according to Section 11 of [RFC8415]. DUID-Type 4 in particular 1500 corresponds to the Universally Unique Identifier (UUID) [RFC6355] 1501 which will occur in common operational practice. 1503 o A type-specific DUID body up to 253 octets in length follows, 1504 formatted according to DUID-type. For example, for type 4 the 1505 body consists of a 128-bit UUID selected according to [RFC6355]. 1507 10.1.10. DHCPv6 Message 1509 0 1 2 3 1510 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 1511 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1512 | Sub-Type=9 | Sub-length=N | msg-type | id (octet 0) | 1513 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1514 | transaction-id (octets 1-2) | | 1515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1516 | | 1517 . DHCPv6 options . 1518 . (variable number and length) . 1519 | | 1520 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1522 Figure 16: DHCPv6 Message Sub-option 1524 o Sub-Type is set to 9. If multiple instances appear in the same 1525 OMNI option the first is processed and all others are ignored. 1527 o Sub-Length is set to N (i.e., the length of the DHCPv6 message 1528 beginning with 'msg-type' and continuing to the end of the DHCPv6 1529 options). The length of the entire DHCPv6 message is therefore 1530 restricted to 255 octets. 1532 o 'msg-type' and 'transaction-id' are coded according to Section 8 1533 of [RFC8415]. 1535 o A set of DHCPv6 options coded according to Section 21 of [RFC8415] 1536 follows. 1538 11. Address Mapping - Multicast 1540 The multicast address mapping of the native underlying interface 1541 applies. The mobile router on board the MN also serves as an IGMP/ 1542 MLD Proxy for its EUNs and/or hosted applications per [RFC4605] while 1543 using the L2 address of the AR as the L2 address for all multicast 1544 packets. 1546 The MN uses Multicast Listener Discovery (MLDv2) [RFC3810] to 1547 coordinate with the AR, and *NET L2 elements use MLD snooping 1548 [RFC4541]. 1550 12. Multilink Conceptual Sending Algorithm 1552 The MN's IPv6 layer selects the outbound OMNI interface according to 1553 SBM considerations when forwarding data packets from local or EUN 1554 applications to external correspondents. Each OMNI interface 1555 maintains a neighbor cache the same as for any IPv6 interface, but 1556 with additional state for multilink coordination. Each OMNI 1557 interface maintains default routes via ARs discovered as discussed in 1558 Section 13, and may configure more-specific routes discovered through 1559 means outside the scope of this specification. 1561 After a packet enters the OMNI interface, one or more outbound 1562 underlying interfaces are selected based on PBM traffic attributes, 1563 and one or more neighbor underlying interfaces are selected based on 1564 the receipt of Interface Attributes sub-options in IPv6 ND messages 1565 (see: Figure 8). Underlying interface selection for the nodes own 1566 local interfaces are based on attributes such as DSCP, application 1567 port number, cost, performance, message size, etc. OMNI interface 1568 multilink selections could also be configured to perform replication 1569 across multiple underlying interfaces for increased reliability at 1570 the expense of packet duplication. The set of all Interface 1571 Attributes received in IPv6 ND messages determine the multilink 1572 forwarding profile for selecting the neighbor's underlying 1573 interfaces. 1575 When the OMNI interface sends a packet over a selected outbound 1576 underlying interface, the OAL includes or omits a mid-layer 1577 encapsulation header as necessary as discussed in Section 5 and as 1578 determined by the L2 address information received in Interface 1579 Attributes. The OAL also performs encapsulation when the nearest AR 1580 is located multiple hops away as discussed in Section 13.1. 1582 OMNI interface multilink service designers MUST observe the BCP 1583 guidance in Section 15 [RFC3819] in terms of implications for 1584 reordering when packets from the same flow may be spread across 1585 multiple underlying interfaces having diverse properties. 1587 12.1. Multiple OMNI Interfaces 1589 MNs may connect to multiple independent OMNI links concurrently in 1590 support of SBM. Each OMNI interface is distinguished by its Anycast 1591 OMNI ULA (e.g., [ULA]:0002::, [ULA]:1000::, [ULA]:7345::, etc.). The 1592 MN configures a separate OMNI interface for each link so that 1593 multiple interfaces (e.g., omni0, omni1, omni2, etc.) are exposed to 1594 the IPv6 layer. A different Anycast OMNI ULA is assigned to each 1595 interface, and the MN injects the service prefixes for the OMNI link 1596 instances into the EUN routing system. 1598 Applications in EUNs can use Segment Routing to select the desired 1599 OMNI interface based on SBM considerations. The Anycast OMNI ULA is 1600 written into the IPv6 destination address, and the actual destination 1601 (along with any additional intermediate hops) is written into the 1602 Segment Routing Header. Standard IP routing directs the packets to 1603 the MN's mobile router entity, and the Anycast OMNI ULA identifies 1604 the OMNI interface to be used for transmission to the next hop. When 1605 the MN receives the message, it replaces the IPv6 destination address 1606 with the next hop found in the routing header and transmits the 1607 message over the OMNI interface identified by the Anycast OMNI ULA. 1609 Multiple distinct OMNI links can therefore be used to support fault 1610 tolerance, load balancing, reliability, etc. The architectural model 1611 is similar to Layer 2 Virtual Local Area Networks (VLANs). 1613 12.2. MN<->AR Traffic Loop Prevention 1615 After an AR has registered an MNP for a MN (see: Section 13), the AR 1616 will forward packets destined to an address within the MNP to the MN. 1617 The MN will under normal circumstances then forward the packet to the 1618 correct destination within its internal networks. 1620 If at some later time the MN loses state (e.g., after a reboot), it 1621 may begin returning packets destined to an MNP address to the AR as 1622 its default router. The AR therefore must drop any packets 1623 originating from the MN and destined to an address within the MN's 1624 registered MNP. To do so, the AR institutes the following check: 1626 o if the IP destination address belongs to a neighbor on the same 1627 OMNI interface, and if the link-layer source address is the same 1628 as one of the neighbor's link-layer addresses, drop the packet. 1630 13. Router Discovery and Prefix Registration 1632 MNs interface with the MS by sending RS messages with OMNI options 1633 under the assumption that one or more AR on the *NET will process the 1634 message and respond. The MN then configures default routes for the 1635 OMNI interface via the discovered ARs as the next hop. The manner in 1636 which the *NET ensures AR coordination is link-specific and outside 1637 the scope of this document (however, considerations for *NETs that do 1638 not provide ARs that recognize the OMNI option are discussed in 1639 Section 18). 1641 For each underlying interface, the MN sends an RS message with an 1642 OMNI option to coordinate with MSEs identified by MSID values. 1643 Example MSID discovery methods are given in [RFC5214] and include 1644 data link login parameters, name service lookups, static 1645 configuration, a static "hosts" file, etc. The MN can also send an 1646 RS with an MS-Register suboption that includes the Anycast MSID value 1647 '0', i.e., instead of or in addition to any non-zero MSIDs. When the 1648 AR receives an RS with a MSID '0', it selects a nearby MSE (which may 1649 be itself) and returns an RA with the selected MSID in an MS-Register 1650 suboption. The AR selects only a single wildcard MSE (i.e., even if 1651 the RS MS-Register suboption included multiple '0' MSIDs) while also 1652 soliciting the MSEs corresponding to any non-zero MSIDs. 1654 MNs configure OMNI interfaces that observe the properties discussed 1655 in the previous section. The OMNI interface and its underlying 1656 interfaces are said to be in either the "UP" or "DOWN" state 1657 according to administrative actions in conjunction with the interface 1658 connectivity status. An OMNI interface transitions to UP or DOWN 1659 through administrative action and/or through state transitions of the 1660 underlying interfaces. When a first underlying interface transitions 1661 to UP, the OMNI interface also transitions to UP. When all 1662 underlying interfaces transition to DOWN, the OMNI interface also 1663 transitions to DOWN. 1665 When an OMNI interface transitions to UP, the MN sends RS messages to 1666 register its MNP and an initial set of underlying interfaces that are 1667 also UP. The MN sends additional RS messages to refresh lifetimes 1668 and to register/deregister underlying interfaces as they transition 1669 to UP or DOWN. The MN sends initial RS messages over an UP 1670 underlying interface with its MN OMNI LLA as the source and with 1671 destination set to All-Routers multicast (ff02::2) [RFC4291]. The RS 1672 messages include an OMNI option per Section 10 with a Preflen 1673 assertion, Interface Attributes appropriate for underlying 1674 interfaces, MS-Register/Release sub-options containing MSID values, 1675 and with any other necessary OMNI sub-options (e.g., a DUID suboption 1676 as an identity for the MN). The S/T-ifIndex field is set to the 1677 index of the underlying interface over which the RS message is sent. 1679 ARs process IPv6 ND messages with OMNI options and act as an MSE 1680 themselves and/or as a proxy for other MSEs. ARs receive RS messages 1681 and create a neighbor cache entry for the MN, then coordinate with 1682 any MSEs named in the Register/Release lists in a manner outside the 1683 scope of this document. When an MSE processes the OMNI information, 1684 it first validates the prefix registration information then injects/ 1685 withdraws the MNP in the routing/mapping system and caches/discards 1686 the new Preflen, MNP and Interface Attributes. The MSE then informs 1687 the AR of registration success/failure, and the AR returns an RA 1688 message to the MN with an OMNI option per Section 10. 1690 The AR returns the RA message via the same underlying interface of 1691 the MN over which the RS was received, and with destination address 1692 set to the MN OMNI LLA (i.e., unicast), with source address set to 1693 its own OMNI LLA, and with an OMNI option with S/T-ifIndex set to the 1694 value included in the RS. The OMNI option also includes a Preflen 1695 confirmation, Interface Attributes, MS-Register/Release and any other 1696 necessary OMNI sub-options (e.g., a DUID suboption as an identity for 1697 the AR). The RA also includes any information for the link, 1698 including RA Cur Hop Limit, M and O flags, Router Lifetime, Reachable 1699 Time and Retrans Timer values, and includes any necessary options 1700 such as: 1702 o PIOs with (A; L=0) that include MSPs for the link [RFC8028]. 1704 o RIOs [RFC4191] with more-specific routes. 1706 o an MTU option that specifies the maximum acceptable packet size 1707 for this underlying interface. 1709 The AR MAY also send periodic and/or event-driven unsolicited RA 1710 messages per [RFC4861]. In that case, the S/T-ifIndex field in the 1711 OMNI header of the unsolicited RA message identifies the target 1712 underlying interface of the destination MN. 1714 The AR can combine the information from multiple MSEs into one or 1715 more "aggregate" RAs sent to the MN in order conserve *NET bandwidth. 1716 Each aggregate RA includes an OMNI option with MS-Register/Release 1717 sub-options with the MSEs represented by the aggregate. If an 1718 aggregate is sent, the RA message contents must consistently 1719 represent the combined information advertised by all represented 1720 MSEs. Note that since the AR uses its own OMNI LLA as the RA source 1721 address, the MN determines the addresses of the represented MSEs by 1722 examining the MS-Register/Release OMNI sub-options. 1724 When the MN receives the RA message, it creates an OMNI interface 1725 neighbor cache entry for each MSID that has confirmed MNP 1726 registration via the L2 address of this AR. If the MN connects to 1727 multiple *NETs, it records the additional L2 AR addresses in each 1728 MSID neighbor cache entry (i.e., as multilink neighbors). The MN 1729 then configures a default route via the MSE that returned the RA 1730 message, and assigns the Subnet Router Anycast address corresponding 1731 to the MNP (e.g., 2001:db8:1:2::) to the OMNI interface. The MN then 1732 manages its underlying interfaces according to their states as 1733 follows: 1735 o When an underlying interface transitions to UP, the MN sends an RS 1736 over the underlying interface with an OMNI option. The OMNI 1737 option contains at least one Interface Attribute sub-option with 1738 values specific to this underlying interface, and may contain 1739 additional Interface Attributes specific to other underlying 1740 interfaces. The option also includes any MS-Register/Release sub- 1741 options. 1743 o When an underlying interface transitions to DOWN, the MN sends an 1744 RS or unsolicited NA message over any UP underlying interface with 1745 an OMNI option containing an Interface Attribute sub-option for 1746 the DOWN underlying interface with Link set to '0'. The MN sends 1747 an RS when an acknowledgement is required, or an unsolicited NA 1748 when reliability is not thought to be a concern (e.g., if 1749 redundant transmissions are sent on multiple underlying 1750 interfaces). 1752 o When the Router Lifetime for a specific AR nears expiration, the 1753 MN sends an RS over the underlying interface to receive a fresh 1754 RA. If no RA is received, the MN can send RS messages to an 1755 alternate MSID in case the current MSID has failed. If no RS 1756 messages are received even after trying to contact alternate 1757 MSIDs, the MN marks the underlying interface as DOWN. 1759 o When a MN wishes to release from one or more current MSIDs, it 1760 sends an RS or unsolicited NA message over any UP underlying 1761 interfaces with an OMNI option with a Release MSID. Each MSID 1762 then withdraws the MNP from the routing/mapping system and informs 1763 the AR that the release was successful. 1765 o When all of a MNs underlying interfaces have transitioned to DOWN 1766 (or if the prefix registration lifetime expires), any associated 1767 MSEs withdraw the MNP the same as if they had received a message 1768 with a release indication. 1770 The MN is responsible for retrying each RS exchange up to 1771 MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL 1772 seconds until an RA is received. If no RA is received over an UP 1773 underlying interface (i.e., even after attempting to contact 1774 alternate MSEs), the MN declares this underlying interface as DOWN. 1776 The IPv6 layer sees the OMNI interface as an ordinary IPv6 interface. 1777 Therefore, when the IPv6 layer sends an RS message the OMNI interface 1778 returns an internally-generated RA message as though the message 1779 originated from an IPv6 router. The internally-generated RA message 1780 contains configuration information that is consistent with the 1781 information received from the RAs generated by the MS. Whether the 1782 OMNI interface IPv6 ND messaging process is initiated from the 1783 receipt of an RS message from the IPv6 layer is an implementation 1784 matter. Some implementations may elect to defer the IPv6 ND 1785 messaging process until an RS is received from the IPv6 layer, while 1786 others may elect to initiate the process proactively. Still other 1787 deployments may elect to administratively disable the ordinary RS/RA 1788 messaging used by the IPv6 layer over the OMNI interface, since they 1789 are not required to drive the internal RS/RA processing. (Note that 1790 this same logic applies to IPv4 implementations that employ ICMP- 1791 based Router Discovery per [RFC1256].) 1793 Note: The Router Lifetime value in RA messages indicates the time 1794 before which the MN must send another RS message over this underlying 1795 interface (e.g., 600 seconds), however that timescale may be 1796 significantly longer than the lifetime the MS has committed to retain 1797 the prefix registration (e.g., REACHABLETIME seconds). ARs are 1798 therefore responsible for keeping MS state alive on a shorter 1799 timescale than the MN is required to do on its own behalf. 1801 Note: On multicast-capable underlying interfaces, MNs should send 1802 periodic unsolicited multicast NA messages and ARs should send 1803 periodic unsolicited multicast RA messages as "beacons" that can be 1804 heard by other nodes on the link. If a node fails to receive a 1805 beacon after a timeout value specific to the link, it can initiate a 1806 unicast exchange to test reachability. 1808 Note: if an AR acting as a proxy forwards a MN's RS message to 1809 another node acting as an MSE using UDP/IP encapsulation, it must use 1810 a distinct UDP source port number for each MN. This allows the MSE 1811 to distinguish different MNs behind the same AR at the link-layer, 1812 whereas the link-layer addresses would otherwise be 1813 indistinguishable. 1815 13.1. Router Discovery in IP Multihop and IPv4-Only Networks 1817 On some *NETs, a MN may be located multiple IP hops away from the 1818 nearest AR. Forwarding through IP multihop *NETs is conducted 1819 through the application of a routing protocol (e.g., a Mobile Ad-hoc 1820 Network (MANET) routing protocol over omni-directional wireless 1821 interfaces, an inter-domain routing protocol in an enterprise 1822 network, etc.). These *NETs could be either IPv6-enabled or 1823 IPv4-only, while IPv4-only *NETs could be either multicast-capable or 1824 unicast-only (note that for IPv4-only *NETs the following procedures 1825 apply for both single-hop and multihop cases). 1827 A MN located potentially multiple *NET hops away from the nearest AR 1828 prepares an RS message with source address set to either its MN OMNI 1829 LLA or a Temporary OMNI LLA, and with destination set to link-scoped 1830 All-Routers multicast the same as discussed above. For IPv6-enabled 1831 *NETs, the MN then encapsulates the message in an IPv6 header with 1832 source address set to the ULA corresponding to the LLA source address 1833 and with destination set to either a unicast or anycast ULA. For 1834 IPv4-only *NETs, the MN instead encapsulates the RS message in an 1835 IPv4 header with source address set to the node's own IPv4 address 1836 and with destination address set to either the unicast IPv4 address 1837 of an AR [RFC5214] or an IPv4 anycast address reserved for OMNI. The 1838 MN then sends the encapsulated RS message via the *NET interface, 1839 where it will be forwarded by zero or more intermediate *NET hops. 1841 When an intermediate *NET hop that participates in the routing 1842 protocol receives the encapsulated RS, it forwards the message 1843 according to its routing tables (note that an intermediate node could 1844 be a fixed infrastructure element or another MN). This process 1845 repeats iteratively until the RS message is received by a penultimate 1846 *NET hop within single-hop communications range of an AR, which 1847 forwards the message to the AR. 1849 When the AR receives the message, it decapsulates the RS and 1850 coordinates with the MS the same as for an ordinary link-local RS, 1851 since the inner Hop Limit will not have been decremented by the 1852 multihop forwarding process. The AR then prepares an RA message with 1853 source address set to its own LLA and destination address set to the 1854 LLA of the original MN, then encapsulates the message in an IPv4/IPv6 1855 header with source address set to its own IPv4/ULA address and with 1856 destination set to the encapsulation source of the RS. 1858 The AR then forwards the message to an *NET node within 1859 communications range, which forwards the message according to its 1860 routing tables to an intermediate node. The multihop forwarding 1861 process within the *NET continues repetitively until the message is 1862 delivered to the original MN, which decapsulates the message and 1863 performs autoconfiguration the same as if it had received the RA 1864 directly from the AR as an on-link neighbor. 1866 Note: An alternate approach to multihop forwarding via IPv6 1867 encapsulation would be to statelessly translate the IPv6 LLAs into 1868 ULAs and forward the messages without encapsulation. This would 1869 violate the [RFC4861] requirement that certain IPv6 ND messages must 1870 use link-local addresses and must not be accepted if received with 1871 Hop Limit less than 255. This document therefore advocates 1872 encapsulation since the overhead is nominal considering the 1873 infrequent nature and small size of IPv6 ND messages. Future 1874 documents may consider encapsulation avoidance through translation 1875 while updating [RFC4861]. 1877 Note: An alternate approach to multihop forwarding via IPv4 1878 encapsulation would be to employ IPv6/IPv4 protocol translation. 1879 However, for IPv6 ND messages the OMNI LLA addresses would be 1880 truncated due to translation and the OMNI Router and Prefix Discovery 1881 services would not be able to function. The use of IPv4 1882 encapsulation is therefore indicated. 1884 Note: An IPv4 anycast address for OMNI in IPv4 networks could be part 1885 of a new IPv4 /24 prefix allocation, but this may be difficult to 1886 obtain given IPv4 address exhaustion. An alternative would be to re- 1887 purpose the prefix 192.88.99.0 which has been set aside from its 1888 former use by [RFC7526]. 1890 13.2. MS-Register and MS-Release List Processing 1892 When a MN sends an RS message with an OMNI option via an underlying 1893 interface to an AR, the MN must convey its knowledge of its 1894 currently-associated MSEs. Initially, the MN will have no associated 1895 MSEs and should therefore include an MS-Register sub-option with the 1896 single MSID value 0 which requests the AR to select and assign an 1897 MSE. The AR will then return an RA message with source address set 1898 to the OMNI LLA containing the MSE of the selected MSE. 1900 As the MN activates additional underlying interfaces, it can 1901 optionally include an MS-Register sub-option with MSID value 0, or 1902 with non-zero MSIDs for MSEs discovered from previous RS/RA 1903 exchanges. The MN will thus eventually begin to learn and manage its 1904 currently active set of MSEs, and can register with new MSEs or 1905 release from former MSEs with each successive RS/RA exchange. As the 1906 MN's MSE constituency grows, it alone is responsible for including or 1907 omitting MSIDs in the MS-Register/Release lists it sends in RS 1908 messages. The inclusion or omission of MSIDs determines the MN's 1909 interface to the MS and defines the manner in which MSEs will 1910 respond. The only limiting factor is that the MN should include no 1911 more than MAX_MSID values in each list per each IPv6 ND message, and 1912 should avoid duplication of entries in each list unless it wants to 1913 increase likelihood of control message delivery. 1915 When an AR receives an RS message sent by a MN with an OMNI option, 1916 the option will contain zero or more MS-Register and MS-Release sub- 1917 options containing MSIDs. After processing the OMNI option, the AR 1918 will have a list of zero or more MS-Register MSIDs and a list of zero 1919 or more of MS-Release MSIDs. The AR then processes the lists as 1920 follows: 1922 o For each list, retain the first MAX_MSID values in the list and 1923 discard any additional MSIDs (i.e., even if there are duplicates 1924 within a list). 1926 o Next, for each MSID in the MS-Register list, remove all matching 1927 MSIDs from the MS-Release list. 1929 o Next, proceed according to whether the AR's own MSID or the value 1930 0 appears in the MS-Register list as follows: 1932 * If yes, send an RA message directly back to the MN and send a 1933 proxy copy of the RS message to each additional MSID in the MS- 1934 Register list with the MS-Register/Release lists omitted. 1935 Then, send a uNA message to each MSID in the MS-Release list 1936 with the MS-Register/Release lists omitted and with an OMNI 1937 header with S/T-ifIndex set to 0. 1939 * If no, send a proxy copy of the RS message to each additional 1940 MSID in the MS-Register list with the MS-Register list omitted. 1941 For the first MSID, include the original MS-Release list; for 1942 all other MSIDs, omit the MS-Release list. 1944 Each proxy copy of the RS message will include an OMNI option and 1945 encapsulation header with the ULA of the AR as the source and the ULA 1946 of the Register MSE as the destination. When the Register MSE 1947 receives the proxy RS message, if the message includes an MS-Release 1948 list the MSE sends a uNA message to each additional MSID in the 1949 Release list. The Register MSE then sends an RA message back to the 1950 (Proxy) AR wrapped in an OMNI encapsulation header with source and 1951 destination addresses reversed, and with RA destination set to the 1952 LLA of the MN. When the AR receives this RA message, it sends a 1953 proxy copy of the RA to the MN. 1955 Each uNA message (whether send by the first-hop AR or by a Register 1956 MSE) will include an OMNI option and an encapsulation header with the 1957 ULA of the Register MSE as the source and the ULA of the Release ME 1958 as the destination. The uNA informs the Release MSE that its 1959 previous relationship with the MN has been released and that the 1960 source of the uNA message is now registered. The Release MSE must 1961 then note that the subject MN of the uNA message is now "departed", 1962 and forward any subsequent packets destined to the MN to the Register 1963 MSE. 1965 Note that it is not an error for the MS-Register/Release lists to 1966 include duplicate entries. If duplicates occur within a list, the AR 1967 will generate multiple proxy RS and/or uNA messages - one for each 1968 copy of the duplicate entries. 1970 13.3. DHCPv6-based Prefix Registration 1972 When a MN is not pre-provisioned with an OMNI LLA containing a MNP 1973 (or, when multiple MNPs are needed), it will require the AR to select 1974 MNPs on its behalf and set up the correct routing state within the 1975 MS. The DHCPv6 service [RFC8415] supports this requirement. 1977 When an MN needs to have the AR select MNPs, it sends an RS message 1978 with a DHCPv6 Message suboption containing a Client Identifier, one 1979 or more IA_PD options and a Rapid Commit option. The MN also sets 1980 the 'msg-type' field to "Solicit", and includes a 3-octet 1981 'transaction-id'. 1983 When the AR receives the RS message, it extracts the DHCPv6 message 1984 from the OMNI option. The AR then acts as a "Proxy DHCPv6 Client" in 1985 a message exchange with the locally-resident DHCPv6 server, which 1986 delegates MNPs and returns a DHCPv6 Reply message with PD parameters. 1987 (If the AR wishes to defer creation of MN state until the DHCPv6 1988 Reply is received, it can instead act as a Lightweight DHCPv6 Relay 1989 Agent per [RFC6221] by encapsulating the DHCPv6 message in a Relay- 1990 forward/reply exchange with Relay Message and Interface ID options.) 1992 When the AR receives the DHCPv6 Reply, it adds routes to the routing 1993 system and creates MN OMNI LLAs based on the delegated MNPs. The AR 1994 then sends an RA back to the MN with the DHCPv6 Reply message 1995 included in an OMNI DHCPv6 message sub-option. If the RS message 1996 source address was a Temporary address, the AR includes one of the 1997 (newly-created) MN OMNI LLAs as the RA destination address. The MN 1998 then creates a default route, assigns Subnet Router Anycast addresses 1999 and uses the RA destination address as its primary MN OMNI LLA. The 2000 MN will then use this primary MN OMNI LLA as the source address of 2001 any IPv6 ND messages it sends as long as it retains ownership of the 2002 MNP. 2004 Note: The single-octet OMNI sub-option length field restricts the 2005 DHCPv6 Message sub-option to a maximum of 255 octets for both the RS 2006 and RA messages. This provides sufficient room for the DHCPv6 2007 message header, a Client/Server Identifier option, a Rapid Commit 2008 option, at least 3 Identity Association for Prefix Delegation (IA_PD) 2009 options and any other supporting DHCPv6 options. A MN requiring more 2010 DHCPv6-based configuration information than this can either perform 2011 multiple independent RS/RA exchanges (with each exchange providing a 2012 subset of the total configuration information) or simply perform an 2013 actual DHCPv6 message exchange in addition to any RS/RA exchanges. 2015 Note: After a MN performs a DHCPv6-based prefix registration exchange 2016 with a first AR, it would need to repeat the exchange with each 2017 additional MSE it registers with. In that case, the MN supplies the 2018 MNP delegations received from the first AR in the IA_PD fields of a 2019 DHCPv6 message when it engages the additonal MSEs. 2021 14. Secure Redirection 2023 If the *NET link model is multiple access, the AR is responsible for 2024 assuring that address duplication cannot corrupt the neighbor caches 2025 of other nodes on the link. When the MN sends an RS message on a 2026 multiple access *NET link, the AR verifies that the MN is authorized 2027 to use the address and returns an RA with a non-zero Router Lifetime 2028 only if the MN is authorized. 2030 After verifying MN authorization and returning an RA, the AR MAY 2031 return IPv6 ND Redirect messages to direct MNs located on the same 2032 *NET link to exchange packets directly without transiting the AR. In 2033 that case, the MNs can exchange packets according to their unicast L2 2034 addresses discovered from the Redirect message instead of using the 2035 dogleg path through the AR. In some *NET links, however, such direct 2036 communications may be undesirable and continued use of the dogleg 2037 path through the AR may provide better performance. In that case, 2038 the AR can refrain from sending Redirects, and/or MNs can ignore 2039 them. 2041 15. AR and MSE Resilience 2043 *NETs SHOULD deploy ARs in Virtual Router Redundancy Protocol (VRRP) 2044 [RFC5798] configurations so that service continuity is maintained 2045 even if one or more ARs fail. Using VRRP, the MN is unaware which of 2046 the (redundant) ARs is currently providing service, and any service 2047 discontinuity will be limited to the failover time supported by VRRP. 2048 Widely deployed public domain implementations of VRRP are available. 2050 MSEs SHOULD use high availability clustering services so that 2051 multiple redundant systems can provide coordinated response to 2052 failures. As with VRRP, widely deployed public domain 2053 implementations of high availability clustering services are 2054 available. Note that special-purpose and expensive dedicated 2055 hardware is not necessary, and public domain implementations can be 2056 used even between lightweight virtual machines in cloud deployments. 2058 16. Detecting and Responding to MSE Failures 2060 In environments where fast recovery from MSE failure is required, ARs 2061 SHOULD use proactive Neighbor Unreachability Detection (NUD) in a 2062 manner that parallels Bidirectional Forwarding Detection (BFD) 2063 [RFC5880] to track MSE reachability. ARs can then quickly detect and 2064 react to failures so that cached information is re-established 2065 through alternate paths. Proactive NUD control messaging is carried 2066 only over well-connected ground domain networks (i.e., and not low- 2067 end *NET links such as aeronautical radios) and can therefore be 2068 tuned for rapid response. 2070 ARs perform proactive NUD for MSEs for which there are currently 2071 active MNs on the *NET. If an MSE fails, ARs can quickly inform MNs 2072 of the outage by sending multicast RA messages on the *NET interface. 2073 The AR sends RA messages to MNs via the *NET interface with an OMNI 2074 option with a Release ID for the failed MSE, and with destination 2075 address set to All-Nodes multicast (ff02::1) [RFC4291]. 2077 The AR SHOULD send MAX_FINAL_RTR_ADVERTISEMENTS RA messages separated 2078 by small delays [RFC4861]. Any MNs on the *NET interface that have 2079 been using the (now defunct) MSE will receive the RA messages and 2080 associate with a new MSE. 2082 17. Transition Considerations 2084 When a MN connects to an *NET link for the first time, it sends an RS 2085 message with an OMNI option. If the first hop AR recognizes the 2086 option, it returns an RA with its MS OMNI LLA as the source, the MN 2087 OMNI LLA as the destination and with an OMNI option included. The MN 2088 then engages the AR according to the OMNI link model specified above. 2089 If the first hop AR is a legacy IPv6 router, however, it instead 2090 returns an RA message with no OMNI option and with a non-OMNI unicast 2091 source LLA as specified in [RFC4861]. In that case, the MN engages 2092 the *NET according to the legacy IPv6 link model and without the OMNI 2093 extensions specified in this document. 2095 If the *NET link model is multiple access, there must be assurance 2096 that address duplication cannot corrupt the neighbor caches of other 2097 nodes on the link. When the MN sends an RS message on a multiple 2098 access *NET link with an OMNI LLA source address and an OMNI option, 2099 ARs that recognize the option ensure that the MN is authorized to use 2100 the address and return an RA with a non-zero Router Lifetime only if 2101 the MN is authorized. ARs that do not recognize the option instead 2102 return an RA that makes no statement about the MN's authorization to 2103 use the source address. In that case, the MN should perform 2104 Duplicate Address Detection to ensure that it does not interfere with 2105 other nodes on the link. 2107 An alternative approach for multiple access *NET links to ensure 2108 isolation for MN / AR communications is through L2 address mappings 2109 as discussed in Appendix C. This arrangement imparts a (virtual) 2110 point-to-point link model over the (physical) multiple access link. 2112 18. OMNI Interfaces on the Open Internet 2114 OMNI interfaces configured over IPv6-enabled underlying interfaces on 2115 the open Internet without an OMNI-aware first-hop AR receive RA 2116 messages that do not include an OMNI option, while OMNI interfaces 2117 configured over IPv4-only underlying interfaces do not receive any 2118 (IPv6) RA messages at all. OMNI interfaces that receive RA messages 2119 without an OMNI option configure addresses, on-link prefixes, etc. on 2120 the underlying interface that received the RA according to standard 2121 IPv6 ND and address resolution conventions [RFC4861] [RFC4862]. OMNI 2122 interfaces configured over IPv4-only underlying interfaces configure 2123 IPv4 address information on the underlying interfaces using 2124 mechanisms such as DHCPv4 [RFC2131]. 2126 OMNI interfaces configured over underlying interfaces that connect to 2127 the open Internet can apply security services such as VPNs to connect 2128 to an MSE or establish a direct link to an MSE through some other 2129 means (see Section 4). In environments where an explicit VPN or 2130 direct link may be impractical, OMNI interfaces can instead use UDP/ 2131 IP encapsulation and HMAC-based message authentication per 2132 [RFC6081][RFC4380]. 2134 After establishing a VPN or preparing for UDP/IP encapsulation, OMNI 2135 interfaces send control plane messages to interface with the MS, 2136 including Neighbor Solicitation (NS) and Neighbor Advertisement (NA) 2137 messages used for address resolution / route optimization (see: 2138 [I-D.templin-intarea-6706bis]). The control plane messages must be 2139 authenticated while data plane messages are delivered the same as for 2140 ordinary best-effort Internet traffic with basic source address-based 2141 data origin verification. Data plane communications via OMNI 2142 interfaces that connect over the open Internet without an explicit 2143 VPN should therefore employ transport- or higher-layer security to 2144 ensure integrity and/or confidentiality. 2146 OMNI interfaces in the open Internet are often located behind Network 2147 Address Translators (NATs). The OMNI interface accommodates NAT 2148 traversal using UDP/IP encapsulation and the mechanisms discussed in 2149 [RFC6081][RFC4380][I-D.templin-intarea-6706bis]. 2151 19. Time-Varying MNPs 2153 In some use cases, it is desirable, beneficial and efficient for the 2154 MN to receive a constant MNP that travels with the MN wherever it 2155 moves. For example, this would allow air traffic controllers to 2156 easily track aircraft, etc. In other cases, however (e.g., 2157 intelligent transportation systems), the MN may be willing to 2158 sacrifice a modicum of efficiency in order to have time-varying MNPs 2159 that can be changed every so often to defeat adversarial tracking. 2161 The prefix delegation services discussed in Section 13.3 allows OMNI 2162 MNs that desire time-varying MNPs to obtain short-lived prefixes to 2163 use a Temporary OMNI LLA as the source address of an RS message with 2164 an OMNI option with DHCPv6 Option sub-options. The MN would then be 2165 obligated to renumber its internal networks whenever its MNP (and 2166 therefore also its OMNI address) changes. This should not present a 2167 challenge for MNs with automated network renumbering services, 2168 however presents limits for the durations of ongoing sessions that 2169 would prefer to use a constant address. 2171 20. IANA Considerations 2173 The IANA is instructed to allocate an official Type number TBD from 2174 the registry "IPv6 Neighbor Discovery Option Formats" for the OMNI 2175 option. Implementations set Type to 253 as an interim value 2176 [RFC4727]. 2178 The IANA is instructed to assign a new Code value "1" in the "ICMPv6 2179 Code Fields: Type 2 - Packet Too Big" registry. The registry should 2180 read as follows: 2182 Code Name Reference 2183 --- ---- --------- 2184 0 Diagnostic Packet Too Big [RFC4443] 2185 1 Advisory Packet Too Big [RFCXXXX] 2187 Figure 17: OMNI Option Sub-Type Values 2189 The IANA is instructed to allocate one Ethernet unicast address TBD2 2190 (suggest 00-00-5E-00-52-14 [RFC5214]) in the registry "IANA Ethernet 2191 Address Block - Unicast Use". 2193 The OMNI option also defines an 8-bit Sub-Type field, for which IANA 2194 is instructed to create and maintain a new registry entitled "OMNI 2195 option Sub-Type values". Initial values for the OMNI option Sub-Type 2196 values registry are given below; future assignments are to be made 2197 through Expert Review [RFC8126]. 2199 Value Sub-Type name Reference 2200 ----- ------------- ---------- 2201 0 Pad1 [RFCXXXX] 2202 1 PadN [RFCXXXX] 2203 2 Interface Attributes [RFCXXXX] 2204 3 Traffic Selector [RFCXXXX] 2205 4 MS-Register [RFCXXXX] 2206 5 MS-Release [RFCXXXX] 2207 6 Network Access Identifier [RFCXXXX] 2208 7 Geo Coordinates [RFCXXXX] 2209 8 DHCP Unique Identifier (DUID) [RFCXXXX] 2210 9 DHCPv6 Message [RFCXXXX] 2211 10-252 Unassigned 2212 253-254 Experimental [RFCXXXX] 2213 255 Reserved [RFCXXXX] 2215 Figure 18: OMNI Option Sub-Type Values 2217 21. Security Considerations 2219 Security considerations for IPv4 [RFC0791], IPv6 [RFC8200] and IPv6 2220 Neighbor Discovery [RFC4861] apply. OMNI interface IPv6 ND messages 2221 SHOULD include Nonce and Timestamp options [RFC3971] when transaction 2222 confirmation and/or time synchronization is needed. 2224 OMNI interfaces configured over secured ANET interfaces inherit the 2225 physical and/or link-layer security properties (i.e., "protected 2226 spectrum") of the connected ANETs. OMNI interfaces configured over 2227 open INET interfaces can use symmetric securing services such as VPNs 2228 or can by some other means establish a direct link. When a VPN or 2229 direct link may be impractical, however, an asymmetric security 2230 service such as the authentication option specified in [RFC4380] or 2231 other protocol control message security mechanisms may be necessary. 2232 While the OMNI link protects control plane messaging, applications 2233 must still employ end-to-end transport- or higher-layer security 2234 services to protect the data plane. 2236 The Mobility Service MUST provide strong network layer security for 2237 control plane messages and forwarding path integrity for data plane 2238 messages. In one example, the AERO service 2239 [I-D.templin-intarea-6706bis] constructs a spanning tree between 2240 mobility service elements and secures the links in the spanning tree 2241 with network layer security mechanisms such as IPsec [RFC4301] or 2242 Wireguard. Control plane messages are then constrained to travel 2243 only over the secured spanning tree paths and are therefore protected 2244 from attack or eavesdropping. Since data plane messages can travel 2245 over route optimized paths that do not strictly follow the spanning 2246 tree, however, end-to-end transport- or higher-layer security 2247 services are still required. 2249 Security considerations for specific access network interface types 2250 are covered under the corresponding IP-over-(foo) specification 2251 (e.g., [RFC2464], [RFC2492], etc.). 2253 Security considerations for IPv6 fragmentation and reassembly are 2254 discussed in Section 5.1. 2256 22. Implementation Status 2258 Draft -29 is implemented in the recently tagged AERO/OMNI 3.0.0 2259 internal release, and Draft -30 is now tagged as the AERO/OMNI 3.0.1. 2260 Newer specification versions will be tagged in upcoming releases. 2261 First public release expected before the end of 2020. 2263 23. Acknowledgements 2265 The first version of this document was prepared per the consensus 2266 decision at the 7th Conference of the International Civil Aviation 2267 Organization (ICAO) Working Group-I Mobility Subgroup on March 22, 2268 2019. Consensus to take the document forward to the IETF was reached 2269 at the 9th Conference of the Mobility Subgroup on November 22, 2019. 2270 Attendees and contributors included: Guray Acar, Danny Bharj, 2271 Francois D'Humieres, Pavel Drasil, Nikos Fistas, Giovanni Garofolo, 2272 Bernhard Haindl, Vaughn Maiolla, Tom McParland, Victor Moreno, Madhu 2273 Niraula, Brent Phillips, Liviu Popescu, Jacky Pouzet, Aloke Roy, Greg 2274 Saccone, Robert Segers, Michal Skorepa, Michel Solery, Stephane 2275 Tamalet, Fred Templin, Jean-Marc Vacher, Bela Varkonyi, Tony Whyman, 2276 Fryderyk Wrobel and Dongsong Zeng. 2278 The following individuals are acknowledged for their useful comments: 2279 Michael Matyas, Madhu Niraula, Greg Saccone, Stephane Tamalet, Eric 2280 Vyncke. Pavel Drasil, Zdenek Jaron and Michal Skorepa are recognized 2281 for their many helpful ideas and suggestions. Madhuri Madhava 2282 Badgandi, Katherine Tran, and Vijayasarathy Rajagopalan are 2283 acknowledged for their hard work on the implementation and insights 2284 that led to improvements to the spec. 2286 Discussions on the IETF 6man and atn mailing lists during the fall of 2287 2020 suggested additional points to consider. The authors gratefully 2288 acknowledge the list members who contributed valuable insights 2289 through those discussions. Eric Vyncke and Erik Kline were the 2290 intarea ADs, while Bob Hinden and Ole Troan were the 6man WG chairs 2291 at the time the document was developed; they are all gratefully 2292 acknowledged for their many helpful insights. 2294 This work is aligned with the NASA Safe Autonomous Systems Operation 2295 (SASO) program under NASA contract number NNA16BD84C. 2297 This work is aligned with the FAA as per the SE2025 contract number 2298 DTFAWA-15-D-00030. 2300 24. References 2302 24.1. Normative References 2304 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 2305 DOI 10.17487/RFC0791, September 1981, 2306 . 2308 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2309 Requirement Levels", BCP 14, RFC 2119, 2310 DOI 10.17487/RFC2119, March 1997, 2311 . 2313 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 2314 "Definition of the Differentiated Services Field (DS 2315 Field) in the IPv4 and IPv6 Headers", RFC 2474, 2316 DOI 10.17487/RFC2474, December 1998, 2317 . 2319 [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, 2320 "SEcure Neighbor Discovery (SEND)", RFC 3971, 2321 DOI 10.17487/RFC3971, March 2005, 2322 . 2324 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 2325 More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, 2326 November 2005, . 2328 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 2329 Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005, 2330 . 2332 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 2333 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2334 2006, . 2336 [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet 2337 Control Message Protocol (ICMPv6) for the Internet 2338 Protocol Version 6 (IPv6) Specification", STD 89, 2339 RFC 4443, DOI 10.17487/RFC4443, March 2006, 2340 . 2342 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 2343 ICMPv6, UDP, and TCP Headers", RFC 4727, 2344 DOI 10.17487/RFC4727, November 2006, 2345 . 2347 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 2348 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 2349 DOI 10.17487/RFC4861, September 2007, 2350 . 2352 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 2353 Address Autoconfiguration", RFC 4862, 2354 DOI 10.17487/RFC4862, September 2007, 2355 . 2357 [RFC6088] Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont, 2358 "Traffic Selectors for Flow Bindings", RFC 6088, 2359 DOI 10.17487/RFC6088, January 2011, 2360 . 2362 [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by 2363 Hosts in a Multi-Prefix Network", RFC 8028, 2364 DOI 10.17487/RFC8028, November 2016, 2365 . 2367 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2368 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2369 May 2017, . 2371 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 2372 (IPv6) Specification", STD 86, RFC 8200, 2373 DOI 10.17487/RFC8200, July 2017, 2374 . 2376 [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., 2377 "Path MTU Discovery for IP version 6", STD 87, RFC 8201, 2378 DOI 10.17487/RFC8201, July 2017, 2379 . 2381 [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., 2382 Richardson, M., Jiang, S., Lemon, T., and T. Winters, 2383 "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", 2384 RFC 8415, DOI 10.17487/RFC8415, November 2018, 2385 . 2387 24.2. Informative References 2389 [ATN] Maiolla, V., "The OMNI Interface - An IPv6 Air/Ground 2390 Interface for Civil Aviation, IETF Liaison Statement 2391 #1676, https://datatracker.ietf.org/liaison/1676/", March 2392 2020. 2394 [ATN-IPS] WG-I, ICAO., "ICAO Document 9896 (Manual on the 2395 Aeronautical Telecommunication Network (ATN) using 2396 Internet Protocol Suite (IPS) Standards and Protocol), 2397 Draft Edition 3 (work-in-progress)", December 2020. 2399 [CRC] Jain, R., "Error Characteristics of Fiber Distributed Data 2400 Interface (FDDI), IEEE Transactions on Communications", 2401 August 1990. 2403 [I-D.ietf-6man-rfc4941bis] 2404 Gont, F., Krishnan, S., Narten, T., and R. Draves, 2405 "Temporary Address Extensions for Stateless Address 2406 Autoconfiguration in IPv6", draft-ietf-6man-rfc4941bis-12 2407 (work in progress), November 2020. 2409 [I-D.ietf-intarea-tunnels] 2410 Touch, J. and M. Townsley, "IP Tunnels in the Internet 2411 Architecture", draft-ietf-intarea-tunnels-10 (work in 2412 progress), September 2019. 2414 [I-D.ietf-ipwave-vehicular-networking] 2415 Jeong, J., "IPv6 Wireless Access in Vehicular Environments 2416 (IPWAVE): Problem Statement and Use Cases", draft-ietf- 2417 ipwave-vehicular-networking-19 (work in progress), July 2418 2020. 2420 [I-D.templin-6man-dhcpv6-ndopt] 2421 Templin, F., "A Unified Stateful/Stateless Configuration 2422 Service for IPv6", draft-templin-6man-dhcpv6-ndopt-10 2423 (work in progress), June 2020. 2425 [I-D.templin-6man-lla-type] 2426 Templin, F., "The IPv6 Link-Local Address Type Field", 2427 draft-templin-6man-lla-type-02 (work in progress), 2428 November 2020. 2430 [I-D.templin-intarea-6706bis] 2431 Templin, F., "Asymmetric Extended Route Optimization 2432 (AERO)", draft-templin-intarea-6706bis-77 (work in 2433 progress), December 2020. 2435 [IPV4-GUA] 2436 Postel, J., "IPv4 Address Space Registry, 2437 https://www.iana.org/assignments/ipv4-address-space/ipv4- 2438 address-space.xhtml", December 2020. 2440 [IPV6-GUA] 2441 Postel, J., "IPv6 Global Unicast Address Assignments, 2442 https://www.iana.org/assignments/ipv6-unicast-address- 2443 assignments/ipv6-unicast-address-assignments.xhtml", 2444 December 2020. 2446 [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - 2447 Communication Layers", STD 3, RFC 1122, 2448 DOI 10.17487/RFC1122, October 1989, 2449 . 2451 [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, 2452 DOI 10.17487/RFC1191, November 1990, 2453 . 2455 [RFC1256] Deering, S., Ed., "ICMP Router Discovery Messages", 2456 RFC 1256, DOI 10.17487/RFC1256, September 1991, 2457 . 2459 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 2460 RFC 2131, DOI 10.17487/RFC2131, March 1997, 2461 . 2463 [RFC2225] Laubach, M. and J. Halpern, "Classical IP and ARP over 2464 ATM", RFC 2225, DOI 10.17487/RFC2225, April 1998, 2465 . 2467 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 2468 Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, 2469 . 2471 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 2472 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 2473 December 1998, . 2475 [RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM 2476 Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999, 2477 . 2479 [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 2480 Domains without Explicit Tunnels", RFC 2529, 2481 DOI 10.17487/RFC2529, March 1999, 2482 . 2484 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 2485 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 2486 . 2488 [RFC3330] IANA, "Special-Use IPv4 Addresses", RFC 3330, 2489 DOI 10.17487/RFC3330, September 2002, 2490 . 2492 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 2493 Considered Useful", BCP 82, RFC 3692, 2494 DOI 10.17487/RFC3692, January 2004, 2495 . 2497 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 2498 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 2499 DOI 10.17487/RFC3810, June 2004, 2500 . 2502 [RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D., 2503 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 2504 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 2505 RFC 3819, DOI 10.17487/RFC3819, July 2004, 2506 . 2508 [RFC3879] Huitema, C. and B. Carpenter, "Deprecating Site Local 2509 Addresses", RFC 3879, DOI 10.17487/RFC3879, September 2510 2004, . 2512 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 2513 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 2514 December 2005, . 2516 [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through 2517 Network Address Translations (NATs)", RFC 4380, 2518 DOI 10.17487/RFC4380, February 2006, 2519 . 2521 [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery 2522 Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April 2523 2006, . 2525 [RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD) 2526 for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006, 2527 . 2529 [RFC4541] Christensen, M., Kimball, K., and F. Solensky, 2530 "Considerations for Internet Group Management Protocol 2531 (IGMP) and Multicast Listener Discovery (MLD) Snooping 2532 Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006, 2533 . 2535 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 2536 "Internet Group Management Protocol (IGMP) / Multicast 2537 Listener Discovery (MLD)-Based Multicast Forwarding 2538 ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605, 2539 August 2006, . 2541 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 2542 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 2543 . 2545 [RFC4963] Heffner, J., Mathis, M., and B. Chandler, "IPv4 Reassembly 2546 Errors at High Data Rates", RFC 4963, 2547 DOI 10.17487/RFC4963, July 2007, 2548 . 2550 [RFC5175] Haberman, B., Ed. and R. Hinden, "IPv6 Router 2551 Advertisement Flags Option", RFC 5175, 2552 DOI 10.17487/RFC5175, March 2008, 2553 . 2555 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., 2556 Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", 2557 RFC 5213, DOI 10.17487/RFC5213, August 2008, 2558 . 2560 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 2561 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 2562 DOI 10.17487/RFC5214, March 2008, 2563 . 2565 [RFC5558] Templin, F., Ed., "Virtual Enterprise Traversal (VET)", 2566 RFC 5558, DOI 10.17487/RFC5558, February 2010, 2567 . 2569 [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) 2570 Version 3 for IPv4 and IPv6", RFC 5798, 2571 DOI 10.17487/RFC5798, March 2010, 2572 . 2574 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 2575 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 2576 . 2578 [RFC6081] Thaler, D., "Teredo Extensions", RFC 6081, 2579 DOI 10.17487/RFC6081, January 2011, 2580 . 2582 [RFC6221] Miles, D., Ed., Ooghe, S., Dec, W., Krishnan, S., and A. 2583 Kavanagh, "Lightweight DHCPv6 Relay Agent", RFC 6221, 2584 DOI 10.17487/RFC6221, May 2011, 2585 . 2587 [RFC6355] Narten, T. and J. Johnson, "Definition of the UUID-Based 2588 DHCPv6 Unique Identifier (DUID-UUID)", RFC 6355, 2589 DOI 10.17487/RFC6355, August 2011, 2590 . 2592 [RFC6543] Gundavelli, S., "Reserved IPv6 Interface Identifier for 2593 Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May 2594 2012, . 2596 [RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic 2597 Requirements for IPv6 Customer Edge Routers", RFC 7084, 2598 DOI 10.17487/RFC7084, November 2013, 2599 . 2601 [RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S., 2602 Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit 2603 Boundary in IPv6 Addressing", RFC 7421, 2604 DOI 10.17487/RFC7421, January 2015, 2605 . 2607 [RFC7526] Troan, O. and B. Carpenter, Ed., "Deprecating the Anycast 2608 Prefix for 6to4 Relay Routers", BCP 196, RFC 7526, 2609 DOI 10.17487/RFC7526, May 2015, 2610 . 2612 [RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542, 2613 DOI 10.17487/RFC7542, May 2015, 2614 . 2616 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 2617 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 2618 February 2016, . 2620 [RFC7847] Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface 2621 Support for IP Hosts with Multi-Access Support", RFC 7847, 2622 DOI 10.17487/RFC7847, May 2016, 2623 . 2625 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 2626 Writing an IANA Considerations Section in RFCs", BCP 26, 2627 RFC 8126, DOI 10.17487/RFC8126, June 2017, 2628 . 2630 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 2631 Decraene, B., Litkowski, S., and R. Shakir, "Segment 2632 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 2633 July 2018, . 2635 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 2636 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 2637 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 2638 . 2640 [RFC8900] Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O., 2641 and F. Gont, "IP Fragmentation Considered Fragile", 2642 BCP 230, RFC 8900, DOI 10.17487/RFC8900, September 2020, 2643 . 2645 Appendix A. Interface Attribute Preferences Bitmap Encoding 2647 Adaptation of the OMNI option Interface Attributes Preferences Bitmap 2648 encoding to specific Internetworks such as the Aeronautical 2649 Telecommunications Network with Internet Protocol Services (ATN/IPS) 2650 may include link selection preferences based on other traffic 2651 classifiers (e.g., transport port numbers, etc.) in addition to the 2652 existing DSCP-based preferences. Nodes on specific Internetworks 2653 maintain a map of traffic classifiers to additional P[*] preference 2654 fields beyond the first 64. For example, TCP port 22 maps to P[67], 2655 TCP port 443 maps to P[70], UDP port 8060 maps to P[76], etc. 2657 Implementations use Simplex or Indexed encoding formats for P[*] 2658 encoding in order to encode a given set of traffic classifiers in the 2659 most efficient way. Some use cases may be more efficiently coded 2660 using Simplex form, while others may be more efficient using Indexed. 2661 Once a format is selected for preparation of a single Interface 2662 Attribute the same format must be used for the entire Interface 2663 Attribute sub-option. Different sub-options may use different 2664 formats. 2666 The following figures show coding examples for various Simplex and 2667 Indexed formats: 2669 0 1 2 3 2670 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 2671 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2672 | Sub-Type=2 | Sub-length=N | ifIndex | ifType | 2673 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2674 | Provider ID | Link |R| API | Bitmap(0)=0xff|P00|P01|P02|P03| 2675 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2676 |P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19| 2677 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2678 |P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31| Bitmap(1)=0xff| 2679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2680 |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47| 2681 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2682 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 2683 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2684 | Bitmap(2)=0xff|P64|P65|P67|P68| ... 2685 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 2687 Figure 19: Example 1: Dense Simplex Encoding 2689 0 1 2 3 2690 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 2691 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2692 | Sub-Type=2 | Sub-length=N | ifIndex | ifType | 2693 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2694 | Provider ID | Link |R| API | Bitmap(0)=0x00| Bitmap(1)=0x0f| 2695 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2696 |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63| 2697 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2698 | Bitmap(2)=0x00| Bitmap(3)=0x00| Bitmap(4)=0x00| Bitmap(5)=0x00| 2699 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2700 | Bitmap(6)=0xf0|192|193|194|195|196|197|198|199|200|201|202|203| 2701 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2702 |204|205|206|207| Bitmap(7)=0x00| Bitmap(8)=0x0f|272|273|274|275| 2703 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2704 |276|277|278|279|280|281|282|283|284|285|286|287| Bitmap(9)=0x00| 2705 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2706 |Bitmap(10)=0x00| ... 2707 +-+-+-+-+-+-+-+-+-+-+- 2709 Figure 20: Example 2: Sparse Simplex Encoding 2711 0 1 2 3 2712 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 2713 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2714 | Sub-Type=2 | Sub-length=N | ifIndex | ifType | 2715 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2716 | Provider ID | Link |R| API | Index = 0x00 | Bitmap = 0x80 | 2717 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2718 |P00|P01|P02|P03| Index = 0x01 | Bitmap = 0x01 |P60|P61|P62|P63| 2719 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2720 | Index = 0x10 | Bitmap = 0x80 |512|513|514|515| Index = 0x18 | 2721 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2722 | Bitmap = 0x01 |796|797|798|799| ... 2723 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 2725 Figure 21: Example 3: Indexed Encoding 2727 Appendix B. VDL Mode 2 Considerations 2729 ICAO Doc 9776 is the "Technical Manual for VHF Data Link Mode 2" 2730 (VDLM2) that specifies an essential radio frequency data link service 2731 for aircraft and ground stations in worldwide civil aviation air 2732 traffic management. The VDLM2 link type is "multicast capable" 2733 [RFC4861], but with considerable differences from common multicast 2734 links such as Ethernet and IEEE 802.11. 2736 First, the VDLM2 link data rate is only 31.5Kbps - multiple orders of 2737 magnitude less than most modern wireless networking gear. Second, 2738 due to the low available link bandwidth only VDLM2 ground stations 2739 (i.e., and not aircraft) are permitted to send broadcasts, and even 2740 so only as compact layer 2 "beacons". Third, aircraft employ the 2741 services of ground stations by performing unicast RS/RA exchanges 2742 upon receipt of beacons instead of listening for multicast RA 2743 messages and/or sending multicast RS messages. 2745 This beacon-oriented unicast RS/RA approach is necessary to conserve 2746 the already-scarce available link bandwidth. Moreover, since the 2747 numbers of beaconing ground stations operating within a given spatial 2748 range must be kept as sparse as possible, it would not be feasible to 2749 have different classes of ground stations within the same region 2750 observing different protocols. It is therefore highly desirable that 2751 all ground stations observe a common language of RS/RA as specified 2752 in this document. 2754 Note that links of this nature may benefit from compression 2755 techniques that reduce the bandwidth necessary for conveying the same 2756 amount of data. The IETF lpwan working group is considering possible 2757 alternatives: [https://datatracker.ietf.org/wg/lpwan/documents]. 2759 Appendix C. MN / AR Isolation Through L2 Address Mapping 2761 Per [RFC4861], IPv6 ND messages may be sent to either a multicast or 2762 unicast link-scoped IPv6 destination address. However, IPv6 ND 2763 messaging should be coordinated between the MN and AR only without 2764 invoking other nodes on the *NET. This implies that MN / AR control 2765 messaging should be isolated and not overheard by other nodes on the 2766 link. 2768 To support MN / AR isolation on some *NET links, ARs can maintain an 2769 OMNI-specific unicast L2 address ("MSADDR"). For Ethernet-compatible 2770 *NETs, this specification reserves one Ethernet unicast address TBD2 2771 (see: Section 20). For non-Ethernet statically-addressed *NETs, 2772 MSADDR is reserved per the assigned numbers authority for the *NET 2773 addressing space. For still other *NETs, MSADDR may be dynamically 2774 discovered through other means, e.g., L2 beacons. 2776 MNs map the L3 addresses of all IPv6 ND messages they send (i.e., 2777 both multicast and unicast) to MSADDR instead of to an ordinary 2778 unicast or multicast L2 address. In this way, all of the MN's IPv6 2779 ND messages will be received by ARs that are configured to accept 2780 packets destined to MSADDR. Note that multiple ARs on the link could 2781 be configured to accept packets destined to MSADDR, e.g., as a basis 2782 for supporting redundancy. 2784 Therefore, ARs must accept and process packets destined to MSADDR, 2785 while all other devices must not process packets destined to MSADDR. 2786 This model has well-established operational experience in Proxy 2787 Mobile IPv6 (PMIP) [RFC5213][RFC6543]. 2789 Appendix D. Change Log 2791 << RFC Editor - remove prior to publication >> 2793 Differences from draft-templin-6man-omni-interface-35 to draft- 2794 templin-6man-omni-interface-36: 2796 o Major clarifications on aspects such as "hard/soft" PTB error 2797 messages 2799 o Made generic so that either IP protocol version (IPv4 or IPv6) can 2800 be used in the data plane. 2802 Differences from draft-templin-6man-omni-interface-31 to draft- 2803 templin-6man-omni-interface-32: 2805 o MTU 2807 o Support for multi-hop ANETS such as ISATAP. 2809 Differences from draft-templin-6man-omni-interface-29 to draft- 2810 templin-6man-omni-interface-30: 2812 o Moved link-layer addressing information into the OMNI option on a 2813 per-ifIndex basis 2815 o Renamed "ifIndex-tuple" to "Interface Attributes" 2817 Differences from draft-templin-6man-omni-interface-27 to draft- 2818 templin-6man-omni-interface-28: 2820 o Updates based on implementation expereince. 2822 Differences from draft-templin-6man-omni-interface-25 to draft- 2823 templin-6man-omni-interface-26: 2825 o Further clarification on "aggregate" RA messages. 2827 o Expanded Security Considerations to discuss expectations for 2828 security in the Mobility Service. 2830 Differences from draft-templin-6man-omni-interface-20 to draft- 2831 templin-6man-omni-interface-21: 2833 o Safety-Based Multilink (SBM) and Performance-Based Multilink 2834 (PBM). 2836 Differences from draft-templin-6man-omni-interface-18 to draft- 2837 templin-6man-omni-interface-19: 2839 o SEND/CGA. 2841 Differences from draft-templin-6man-omni-interface-17 to draft- 2842 templin-6man-omni-interface-18: 2844 o Teredo 2846 Differences from draft-templin-6man-omni-interface-14 to draft- 2847 templin-6man-omni-interface-15: 2849 o Prefix length discussions removed. 2851 Differences from draft-templin-6man-omni-interface-12 to draft- 2852 templin-6man-omni-interface-13: 2854 o Teredo 2856 Differences from draft-templin-6man-omni-interface-11 to draft- 2857 templin-6man-omni-interface-12: 2859 o Major simplifications and clarifications on MTU and fragmentation. 2861 o Document now updates RFC4443 and RFC8201. 2863 Differences from draft-templin-6man-omni-interface-10 to draft- 2864 templin-6man-omni-interface-11: 2866 o Removed /64 assumption, resulting in new OMNI address format. 2868 Differences from draft-templin-6man-omni-interface-07 to draft- 2869 templin-6man-omni-interface-08: 2871 o OMNI MNs in the open Internet 2873 Differences from draft-templin-6man-omni-interface-06 to draft- 2874 templin-6man-omni-interface-07: 2876 o Brought back L2 MSADDR mapping text for MN / AR isolation based on 2877 L2 addressing. 2879 o Expanded "Transition Considerations". 2881 Differences from draft-templin-6man-omni-interface-05 to draft- 2882 templin-6man-omni-interface-06: 2884 o Brought back OMNI option "R" flag, and discussed its use. 2886 Differences from draft-templin-6man-omni-interface-04 to draft- 2887 templin-6man-omni-interface-05: 2889 o Transition considerations, and overhaul of RS/RA addressing with 2890 the inclusion of MSE addresses within the OMNI option instead of 2891 as RS/RA addresses (developed under FAA SE2025 contract number 2892 DTFAWA-15-D-00030). 2894 Differences from draft-templin-6man-omni-interface-02 to draft- 2895 templin-6man-omni-interface-03: 2897 o Added "advisory PTB messages" under FAA SE2025 contract number 2898 DTFAWA-15-D-00030. 2900 Differences from draft-templin-6man-omni-interface-01 to draft- 2901 templin-6man-omni-interface-02: 2903 o Removed "Primary" flag and supporting text. 2905 o Clarified that "Router Lifetime" applies to each ANET interface 2906 independently, and that the union of all ANET interface Router 2907 Lifetimes determines MSE lifetime. 2909 Differences from draft-templin-6man-omni-interface-00 to draft- 2910 templin-6man-omni-interface-01: 2912 o "All-MSEs" OMNI LLA defined. Also reserved fe80::ff00:0000/104 2913 for future use (most likely as "pseudo-multicast"). 2915 o Non-normative discussion of alternate OMNI LLA construction form 2916 made possible if the 64-bit assumption were relaxed. 2918 First draft version (draft-templin-atn-aero-interface-00): 2920 o Draft based on consensus decision of ICAO Working Group I Mobility 2921 Subgroup March 22, 2019. 2923 Authors' Addresses 2924 Fred L. Templin (editor) 2925 The Boeing Company 2926 P.O. Box 3707 2927 Seattle, WA 98124 2928 USA 2930 Email: fltemplin@acm.org 2932 Tony Whyman 2933 MWA Ltd c/o Inmarsat Global Ltd 2934 99 City Road 2935 London EC1Y 1AX 2936 England 2938 Email: tony.whyman@mccallumwhyman.com