idnits 2.17.1 draft-templin-autoconf-dhcp-15.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 16. -- Found old boilerplate from RFC 3978, Section 5.5, updated by RFC 4748 on line 989. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 1000. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 1007. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 1013. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust Copyright Line does not match the current year -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (August 19, 2008) is 5729 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'RFC3056' is defined on line 755, but no explicit reference was found in the text == Unused Reference: 'RFC3753' is defined on line 758, but no explicit reference was found in the text == Outdated reference: A later version (-13) exists of draft-ietf-dhc-subnet-alloc-07 ** Obsolete normative reference: RFC 2460 (Obsoleted by RFC 8200) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) ** Obsolete normative reference: RFC 3633 (Obsoleted by RFC 8415) == Outdated reference: A later version (-15) exists of draft-cheshire-dnsext-multicastdns-06 == Outdated reference: A later version (-14) exists of draft-ietf-manet-smf-07 == Outdated reference: A later version (-23) exists of draft-templin-seal-22 -- Obsolete informational reference (is this intentional?): RFC 4941 (Obsoleted by RFC 8981) Summary: 4 errors (**), 0 flaws (~~), 7 warnings (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group F. Templin, Ed. 3 Internet-Draft S. Russert 4 Intended status: Informational S. Yi 5 Expires: February 20, 2009 Boeing Phantom Works 6 August 19, 2008 8 MANET Autoconfiguration using Virtual Enterprise Traversal (VET) 9 draft-templin-autoconf-dhcp-15.txt 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on February 20, 2009. 36 Abstract 38 Mobile Ad-hoc Networks (MANETs) connect routers on links with 39 asymmetric reachability characteristics, and may also connect to 40 other networks including the Internet. Routers in MANETs must have a 41 way to automatically provision IP addresses/prefixes and other 42 information. This document specifies a Virtual Enterprise Traversal 43 (VET) abstraction for autoconfiguration and operation of routers in 44 MANETs. 46 Table of Contents 48 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 49 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 50 3. MANET Characteristics . . . . . . . . . . . . . . . . . . . . 6 51 4. MANET Router Autoconfiguration . . . . . . . . . . . . . . . . 7 52 4.1. MANET Interface Autoconfiguration . . . . . . . . . . . . 8 53 4.2. VET Interface Autoconfiguration . . . . . . . . . . . . . 9 54 4.3. MANET Gateway List Discovery and MANET Identification . . 10 55 4.4. Site-interior Interface Autoconfiguration . . . . . . . . 10 56 4.4.1. Autoconfiguration of IPv4 Addresses/Prefixes . . . . . 10 57 4.4.2. Autoconfiguration of IPv6 Addresses/Prefixes . . . . . 11 58 4.4.3. Prefix and Route Maintenance . . . . . . . . . . . . . 12 59 4.5. Portable and Self-Configured IP Prefixes . . . . . . . . . 12 60 4.6. Separation of IP Addressing Domains . . . . . . . . . . . 13 61 5. Post-Autoconfiguration Operation . . . . . . . . . . . . . . . 13 62 5.1. Forwarding Packets to Off-MANET Destinations . . . . . . . 13 63 5.2. MANET-Local Communications . . . . . . . . . . . . . . . . 14 64 5.3. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 14 65 5.4. Service Discovery . . . . . . . . . . . . . . . . . . . . 14 66 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 67 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 68 8. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 15 69 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 70 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 15 71 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 72 11.1. Normative References . . . . . . . . . . . . . . . . . . . 16 73 11.2. Informative References . . . . . . . . . . . . . . . . . . 16 74 Appendix A. Duplicate Address Detection (DAD) Considerations . . 18 75 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 19 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 77 Intellectual Property and Copyright Statements . . . . . . . . . . 23 79 1. Introduction 81 Mobile Ad-hoc Networks (MANETs) connect MANET Routers (MNRs) on links 82 with asymmetric reachability characteristics (see: [RFC4861], Section 83 2.2). From the standpoint of IP autoconfiguration, MANETs share 84 properties with enterprise networks [RFC4852] except that their 85 topologies may change dynamically over time and there may be 86 little/no active management by (centralized) network operation 87 authorities. These specialized characteristics require careful 88 considerations for MANET router autoconfiguration and operation, 89 however the same principles apply equally to enterprise network 90 scenarios that may be neither mobile nor ad-hoc. 92 MANET autoconfiguration entails the configuration of addresses/ 93 prefixes and other information on routers in MANETs, where addresses 94 of different scopes may be assigned on various types of interfaces 95 with diverse properties. The different types of interfaces that may 96 occur on a MANET router are defined, and the autoconfiguration 97 mechanisms used for each type are specified. (Out of scope for this 98 document is the autoconfiguration of Internet-facing interfaces, 99 which must be coordinated in a manner specific to the service 100 provider's network.) Figure 1 below depicts the conceptual model for 101 a MANET Router: 103 Internet-facing Interfaces 104 x x x 105 | | | 106 +----------------------+---+--------+----------+ 107 | | | | | M 108 | | | .... | | A 109 | +---+---+--------+---+ | N 110 | | +--------+ /| | E 111 | I V I x----+ | Host | I /*+------+--< T 112 | n i n | |Function| n|**| | 113 | t r t | +--------+ t|**| | I 114 | e t e x----+ V e|**+------+--< n 115 | r u r . | E r|**| . | t 116 | n a f . | T f|**| . | e 117 | a l a . | +--------+ a|**| . | r 118 | l c . | | Router | c|**| . | f 119 | e x----+ |Function| e \*+------+--< a 120 | s | +--------+ \| | c 121 | +---+---+--------+---+ | e 122 | | | .... | | s 123 | | | | | 124 +----------------------+---+--------+----------+ 125 | | | 126 x x x 127 Site-Interior Interfaces 129 Figure 1: MANET Router 131 This document specifies a Virtual Enterprise Traversal (VET) 132 abstraction for MANET autoconfiguration and operation with multilink 133 subnet avoidance; both IPv4 [RFC0791] and IPv6 [RFC2460] are 134 discussed within this context. The use of standard DHCP 135 [RFC2131][RFC3315] and neighbor discovery [RFC0826][RFC4861] 136 mechanisms is assumed unless otherwise specified. 138 This work is related to activites of the IETF autoconf, dhc, ipv6, 139 manet and v6ops working groups. 141 2. Terminology 143 The terms "inner" and "outer" are used throughout this document to 144 respectively refer to the innermost IP {address, protocol, header, 145 packet, etc.} *before* encapsulation, and the outermost IP {address, 146 protocol, header, packet, etc.} *after* encapsulation. (There may 147 also be "mid-layer" encapsulations between the inner and outer 148 layers, including IPSec [RFC4301], the Subnetwork Encapsulation and 149 Adaptation Layer (SEAL) [I-D.templin-seal], etc.) 150 The terminology in [I-D.ietf-autoconf-manetarch] and the normative 151 references apply. The following terms are defined within the scope 152 of this document: 154 subnetwork 155 the same as defined in [RFC3819]. 157 Mobile Ad-hoc Network (MANET) 158 a connected network region of MANET routers that maintain a 159 routing structure among themselves over asymmetric reachability 160 links (see: [RFC4861], Section 2.2). Further information on 161 MANETs can be found in [RFC2501] and 162 [I-D.ietf-autoconf-manetarch]. 164 MANET Router (MNR) 165 a mobile router that forwards packets over MANET interfaces. For 166 the purpose of this specification, an MNR comprises a router 167 function, a host function, one or more MANET interfaces and zero 168 or more internal virtual, site-interior, Internet-facing and VET 169 interfaces. 171 MANET Border Router (MNBR) 172 an MNR that connects other networks to the MANET and/or connects 173 the MANET to other networks, including the Internet. MNBRs also 174 configure a seperate VET interface (used for automatic tunneling) 175 for each distinct MANET they connect to. All MNBRs are also MNRs. 177 MANET Gateway (MNGW) 178 a MNBR that connects the MANET to the Internet via Internet-facing 179 interfaces and can delegate addresses/prefixes to other MNBRs. 180 All MNGWs are also MNBRs. 182 Internal Virtual Interface 183 a MNBR's attachment to an internal virual link (e.g., a loopback 184 ). Internal virtual interfaces are also considered as site- 185 interior interfaces. 187 Site-interior Interface 188 a MNBR's attachment to a link (e.g., an ethernet, a wireless 189 personal area network, etc.) that it connects to the MANET and/or 190 the Internet. 192 Internet-facing Interface 193 a MNBR's attachment to the Internet, or to a provider network 194 outside of the MANET via which the Internet can be reached. 196 MANET Interface 197 a MNR's attachment to a link in a MANET. A MANET interface is 198 "neutral" in its orientation, i.e., it is inherently neither site- 199 interior nor Internet-facing. In particular, a packet may need to 200 be forwarded over several MANET interfaces before it is forwarded 201 via either a site-interior or Internet-facing interface. 203 MANET Local Address (MLA) 204 a MANET-scoped IP address (e.g., an IPv6 Unique Local Address 205 [RFC4193], an IPv4 privacy address [RFC1918], etc.) that is 206 assigned to a MANET interface and unique within the MANET. MLAs 207 are used as identifiers for operating the routing protocol and/or 208 locators for packet forwarding within the scope of the MANET; MLAs 209 are also used as *outer* IP addresses during encapsulation. 211 Virtual Enterprise Traversal (VET) 212 an abstraction that uses IP-in-IP encapsulation to span a multi- 213 link network (e.g., a MANET) in a single (inner) IP hop. 215 VET interface 216 a MNBR's interface used for virtual enterprise traversal. The 217 MNBR configures a VET interface over a set of underlying MANET 218 interface(s) belonging to the same MANET. The VET interface 219 encapsulates each inner IP packet in any mid-layer headers plus an 220 outer IP header then forwards it on an underlying MANET interface 221 such that the TTL/Hop Limit in the inner header is not decremented 222 as the packet traverses the MANET. The VET interface presents an 223 automatic tunneling abstraction that represents the MANET as a 224 single IP hop. 226 The following additional abbreviations are used throughout the 227 document: 229 CGA - Cryptographically Generated Address 230 DHCP[v4,v6] - the Dynamic Host Configuration Protocol 231 IP[v4,v6] - the Internet Protocol 232 ISATAP - Intra-Site Automatic Tunnel Addressing Protocol 233 ND - Neighbor Discovery 234 PIO - Prefix Information Option 235 RIO - Route Information Option 236 RS/RA - IPv6 Neighbor Discovery Router Solicitation/Advertisement 237 SEAL - Subnetwork Encapsulation and Adaptation Layer 238 SLAAC - IPv6 StateLess Address AutoConfiguation 240 3. MANET Characteristics 242 MNRs typically participate in a routing protocol over MANET 243 interfaces to discover routes across the MANET using multiple Layer-2 244 or Layer-3 forwarding hops if necessary. MANETs may also connect to 245 other networks via MANET Border Routers (MNBRs) and connect to the 246 Internet via MANET Gateways (MNGWs). A MANET may be as simple as a 247 small collection of MNRs (and their attached networks); a MANET may 248 also contain other MANETs and/or be a subnetwork of a larger MANET. 250 MANETs that comprise homogeneous link types within a single IP subnet 251 can configure the routing protocol to operate as a sub-IP layer 252 mechanism such that IP sees the MANET as an ordinary shared link the 253 same as for a (bridged) campus LAN. In that case, a single IP hop is 254 sufficient to traverse the MANET without IP layer encapsulation. 256 MANETs that comprise heterogeneous link types and/or multiple IP 257 subnets must also provide a routing service that operates as an IP 258 layer mechanism, e.g., to accommodate media types with dissimilar 259 Layer-2 address formats and maximum transmission units (MTUs). In 260 that case, multiple IP hops may be necessary to traverse the MANET 261 such that specific autoconfiguration procedures are necessary to 262 avoid multilink subnet issues [RFC4903]. In particular, we describe 263 herein the use of IP-in-IP encapsulation to span the MANET in a 264 single (inner) IP hop in order to avoid the multilink subnet issues 265 that arise when MANET interfaces are used directly by applications. 267 Conceptually, a MNR embodies both a host function and router 268 function. The host function enables the MNR to generate and receive 269 packets over any of its non-MANET interfaces according to the weak 270 end system model [RFC1122]. The router function connects the MNR's 271 attached networks to MANETs via MANET interfaces and/or connects the 272 MANET to other networks including the Internet (see: Figure 1). 274 MNBRs also configure a VET interface that views all routers in the 275 MANET as single-hop neighbors, where the MANET can also appear as a 276 single IP hop within another MANET. MNBRs configure a seperate VET 277 interface for each distinct MANET to which they connect, and discover 278 a list of MNBRs for each VET interface that can be used for 279 forwarding packets to off-MANET destinations. The following sections 280 present the Virtual Enterprise Traversal approach for MANET 281 Autoconfiguration. 283 4. MANET Router Autoconfiguration 285 MNRs configure one or more MANET interfaces and engage in any MANET 286 routing protocols over those interfaces. They also configure zero or 287 more Internet-facing interfaces that connect the MANET to the 288 Internet, and zero or more site-interior interfaces (including 289 internal virtual interfaces such as a loopback interface) that attach 290 other networks to the MANET. 292 MNRs that configure site-interior/Internet-facing interfaces also act 293 as MNBRs, and configure a VET interface over a set of underlying 294 MANET interfaces belonging to the same MANET. (Note that a MNBR may 295 connect to multiple distinct MANETs, in which case it would configure 296 multiple VET interfaces.) MNRs obtain addresses/prefixes and other 297 autoconfiguration information using the mechanisms specified in the 298 following sections. 300 4.1. MANET Interface Autoconfiguration 302 When a MNR joins a MANET, it first configures a unique IPv6 link- 303 local address on each MANET interface that requires an IPv6 link- 304 local capability and an IPv4 link-local address on each MANET 305 interface that requires an IPv4 link-local capability. IPv6 link- 306 local address generation mechanisms that provide sufficient 307 uniqueness include Cryptographically Generated Addresses (CGAs) 308 [RFC3972], StateLess Address AutoConfiguration (SLAAC) using EUI-64 309 interface identifiers [RFC4862], etc. The mechanisms specified in 310 [RFC3927] provide an IPv4 link-local address generation capability. 312 Next, the MNR configures a MANET Local Address (MLA) of the outer IP 313 protocol version on each of its MANET interfaces and engages in any 314 MANET routing protocols on those interfaces. The MNR can configure 315 an MLA via explicit management, DHCP autoconfiguration, pseudo-random 316 self-generation from a suitably large address pool, or through an 317 alternate autoconfiguration mechanism. 319 DHCP configuration of MLAs may require support from relays within the 320 MANET that have already autoconfigured an MLA as well as a MANET-wide 321 multicast forwarding capability. For DHCPv6, relays that do not 322 already know the MLA of a server relay requests to the 323 'All_DHCP_Servers' site-scoped IPv6 multicast group. For DHCPv4, 324 relays that do not already know the MLA of a server relay requests to 325 the site-scoped IPv4 multicast group address TBD (see: Section 6). 326 DHCPv4 servers that delegate MLAs join the TBD multicast group and 327 service any DHCPv4 messages received for that group. 329 Self-generation of MLAs for IPv6 can be from a large IPv6 local-use 330 address range, e.g., IPv6 Unique Local Addresses [RFC4193]. Self- 331 generation of MLAs for IPv4 can be from a large IPv4 private address 332 range, e.g., 240/4 [I-D.fuller-240space]. When self-generation is 333 used alone, the MNR must continuously monitor the MLAs for 334 uniqueness, e.g., by monitoring the routing protocol, sending 335 beacons, etc. (This continuous monitoring process is sometimes known 336 as "in-service duplicate address detection"). 338 A combined approach using both DHCP and self-generation is also 339 possible. In this combined approach, the MNR first self-generates a 340 temporary MLA which it will use only for the purpose of procuring an 341 actual MLA from a DHCP server. Acting as a combined client/relay, 342 the MNR then uses the temporary MLA to engage in the routing protocol 343 and performs a relay-server exchange using the temporary MLA as an 344 address for the relay. When the DHCP server delegates an actual MLA, 345 the MNR abandons the temporary MLA, assigns the actual MLA to the 346 MANET interface and re-engages in the routing protocol. Note that 347 the range of MLAs delegated by a DHCP server must be disjoint from 348 the range of MLAs used by the MNR for self-generation. 350 4.2. VET Interface Autoconfiguration 352 MNBRs configure a VET interface over a set of underlying MANET 353 interfaces belonging to the same MANET, where the VET interface sees 354 all MNBRs in the MANET as single hop neighbors. Inner IP packets 355 forwarded over the VET interface are encapsulated in any mid-layer 356 headers (e.g., IPsec, the SEAL header, etc.) followed by an outer IP 357 header, then submitted to the outer IP forwarding engine for 358 transmission on an underlying MANET interface (further encapsulation 359 details are specified in Section 5.) 361 When IPv6 and IPv4 are used as the inner/outer protocols 362 (respectively), the MNBR autoconfigures an ISATAP link-local address 363 ([RFC5214], Section 6.2) on the VET interface to support packet 364 forwarding and operation of the IPv6 neighbor discovery protocol. 365 The ISATAP address embeds an IPv4 MLA assigned to an underlying MANET 366 interface, and need not be checked for uniqueness since the IPv4 MLA 367 itself was already determined to be unique. Link-local address 368 configuration for other inner/outer IP protocol combinations is 369 through administrative configuration or through an unspecified 370 alternate method. 372 After the MNBR configures a VET interface, it can communicate with 373 other MNBRs as single-hop neighbors, i.e., it can confirm 374 reachability of other MNBRs through Neighbor Discovery (ND) and/or 375 DHCP exchanges over the VET interface. (The MNBR can also confirm 376 reachability through information conveyed in the MANET routing 377 protocol or through some other means associated with the specific 378 MANET subnetwork technology.) 380 The MNBR must be able to detect and recover from the loss of VET 381 interface neighbors due to e.g., MANET partitions, node failures, 382 etc. Mechanisms specified outside of this document such as 383 monitoring the routing protocol, ND beaconing/polling, DHCP renewals/ 384 leasequeries, upper layer protocol hints of forward progress, 385 bidirectional forward detection, detection of network attachment, 386 etc. can be used according to the particular deployment scenario. 388 4.3. MANET Gateway List Discovery and MANET Identification 390 After the MNBR configures its VET interfaces, it next discovers a 391 list of MNGWs for each distinct MANET to which it connects. The list 392 can be discovered through information conveyed in the routing 393 protocol or through the discovery mechanisms outlined in [RFC5214], 394 Section 8.3.2. 396 In particular, whether or not routing information is available the 397 MNBR can discover the list of MNGWs by resolving an identifying name 398 for the MANET using a MANET-local name resolution service (such as 399 LLMNR [RFC4759] over the VET interface). In the absence of other 400 identifying names, the MNBR can resolve either the hostname 401 "isatapv2" or the FQDN "isatapv2.example.com" (i.e., if a MANET- 402 specific suffix "example.com" is known) for multicast-capable MANETs. 403 For non-multicast MANETs, the MNBR can instead resolve the hostname 404 "isatap" or the FQDN "isatap.example.com". 406 Identifying names, addresses of MNGWs and/or the prefixes they 407 aggregate serve as an identifier for the MANET. 409 4.4. Site-interior Interface Autoconfiguration 411 MNBRs can acquire addresses and/or prefix delegations for assignment 412 on site-interior interfaces through autoconfiguration exchanges with 413 MNGWs over the VET interface. Site-interior interface 414 autoconfiguration considerations are discussed in the following 415 sections: 417 4.4.1. Autoconfiguration of IPv4 Addresses/Prefixes 419 When IPv4 is used as the inner protocol, the MNBR discovers the 420 addresses of one or more MNGWs that delegate IPv4 prefixes then 421 performs a DHCPv4 prefix delegation exchange 422 [I-D.ietf-dhc-subnet-alloc] over the VET interface to obtain IPv4 423 prefixes for assignment and/or sub-delegation on its site-interior 424 interfaces. 426 To perform the DHCPv4 prefix delegation exchange, a DHCPv4 client 427 associated with the MNBR's host function forwards a DHCPDISCOVER 428 message with a Subnet Allocation option to a DHCPv4 relay associated 429 with its router function, i.e., the MNBR acts as both client and 430 relay. The relay then forwards the message over the VET interface to 431 the DHCPv4 server on a MNGW. The forwarded DHCPDISCOVER will elicit 432 a DHCPOFFER from the server containing IPv4 prefix delegations, and 433 the MNBR completes the delegation through a DHCPREQUEST/DHCPACK 434 exchange (again using the combined client/relay approach). 436 When the MNBR receives IPv4 prefix delegations, it assigns the 437 prefixes on site-interior interfaces; it does not assign them on the 438 VET interface or on MANET interfaces. The MNBR can also obtain /32 439 prefixes using DHCPv4 prefix delegation the same as for any IPv4 440 prefix, and can assign them as IPv4 addresses with /32 netmasks on 441 site-interior interfaces. 443 4.4.2. Autoconfiguration of IPv6 Addresses/Prefixes 445 When IPv6 is used as the inner protocol, the MNBR sends unicast IPv6 446 Router Solicitation (RS) messages to MNGWs over the VET interface to 447 receive Router Advertisements (RAs) with Prefix Information Options 448 (PIOs) and/or with the 'M' flag set to signify whether DHCPv6 449 autoconfiguration is available. When the MNBR receives an RA 450 containing PIOs with the 'A' and 'L' bits set to 1, it autoconfigures 451 IPv6 addresses from the prefixes using SLAAC and assigns them to the 452 VET interface. (When IPv4 is used as the outer IP protocol, the 453 addresses are autoconfigured and assigned as ISATAP addresses the 454 same as specified in [RFC5214].) 456 When the MNBR receives an RA with the 'M' flag set to 1, the MNGW 457 that sent the RA also hosts a DHCPv6 server capable of delegating 458 IPv6 prefixes (support for the MNGW acting as a DHCPv6 relay may be 459 considered in the future). If the RA also contains PIOs with the 'L' 460 bit set to 0, the MNBR can use them as hints of prefixes the server 461 is willing to delegate. For example, a MNGW can include a PIO with a 462 prefix such as 2001::DB8::/48 as a hint of an aggregated prefix from 463 which it is willing to delegate longer prefixes. Whether or not such 464 hints are available, the MNBR (acting as a requesting router) can use 465 DHCPv6 prefix delegation [RFC3633] over the VET interface to obtain 466 IPv6 prefixes from the MNGW (acting as a delegating router). The 467 MNBR can then use the delegated prefixes for assignment and/or sub- 468 delegation on its site-interior interfaces. 470 The MNBR obtains prefixes using either a 2-message or 4-message 471 DHCPv6 exchange [RFC3315]. For example, to perform the 2-message 472 exchange a DHCPv6 client associated with the MNBR's host function 473 forwards a Solicit message with an IA_PD option to a DHCPv6 relay 474 associated with its router function, i.e., the MNBR acts as both 475 client and relay. The relay then forwards the message over the VET 476 interface to the DHCPv6 server. The forwarded Solicit message will 477 elicit a Reply from the server containing IPv6 prefix delegations. 478 When the MNBR receives IPv6 prefix delegations, it assigns the 479 prefixes on site-interior interfaces only; it does not assign them on 480 Internet-facing, VET, or MANET interfaces (see: [RFC3633], Section 481 12.1). 483 The MNBR can also propose a specific prefix to the DHCPv6 server per 484 Section 7 of [RFC3633], e.g., if a prefix delegation hint is 485 available. The server will check the proposed prefix for consistency 486 and uniqueness, then return it in the reply to the MNBR if it was 487 able to perform the delegation. The MNBR can use mechanisms such as 488 CGAs [RFC3972], IPv6 privacy address [RFC4941], etc. to self-generate 489 addresses in conjunction with prefix delegation. 491 4.4.3. Prefix and Route Maintenance 493 When DHCP prefix delegation is used, the MNGW's DHCP server ensures 494 that the delegations are unique within the MANET and that its router 495 function will forward IP packets over the VET interface to the MNBR 496 to which the prefix was delegated. The prefix delegation remains 497 active as long as the MNBR continues to issue renewals over the VET 498 interface before the lease lifetime expires. The lease lifetime also 499 keeps the delegation state active even if communications between the 500 MNBR and MNGW is disrupted for a period of time (e.g., due to a MANET 501 partition) before being reestablished (e.g., due to a MANET merge). 503 Since the DHCP client and relay are co-resident on the same MNBR, no 504 special coordination is necessary for the MNGW to maintain routing 505 information. The MNGW simply retains forwarding information base 506 entries that identify the MNBR as the next-hop toward the prefix via 507 the VET interface, and issues ordinary redirects over the VET 508 interface when necessary . 510 4.5. Portable and Self-Configured IP Prefixes 512 Independent of any MNGW-aggregated addresses/prefixes (see: 513 Section 4.4), a MNBR can retain portable IP prefixes (e.g., prefixes 514 taken from a home network, IPv6 Unique Local Addresses (ULAs) 515 [RFC4193][I-D.ietf-ipv6-ula-central], etc.) as it travels between 516 visited networks as long it coordinates in some fashion, e.g., with a 517 mapping agent, prefix aggregation authority, etc. MNBRs can sub- 518 delegate portable (and other self-configured) prefixes on networks 519 connected on their site-interior interfaces. 521 Portable prefixes are not aggregated, redistributed or advertised by 522 MNGWs and can therefore travel with the MNBR as it moves to new 523 visited networks and/or configures peering arrangements with other 524 nodes. Generation and coordination of portable (and other self- 525 configured) prefixes can therefore occur independently of any other 526 autoconfiguration considerations. 528 4.6. Separation of IP Addressing Domains 530 When the inner and outer IP protocols are different (i.e., IPv6-in- 531 IPv4 or IPv4-in-IPv6), the MNBR's dual-stack orientation provides a 532 natural separation between the inner and outer IP addressing domains, 533 and separate default routes can be configured for each domain. 535 When the inner and outer IP protocols are the same (i.e., IPv4-in- 536 IPv4 or IPv6-in-IPv6) separation between inner and outer IP 537 addressing domains can only be determined through the examination of 538 IP prefixes. In that case, special configurations/mechanisms may be 539 necessary to support unambiguous determination of when to encapsulate 540 using the VET interface vs when to forward using a MANET interface. 542 5. Post-Autoconfiguration Operation 544 After a MNR has been autoconfigured, it participates in any MANET 545 routing protocols over MANET interfaces and forwards outer IP packets 546 within the MANET as for any ordinary router. MNBRs can additionally 547 participate in any inner IP routing protocols over non-MANET 548 interfaces and forward inner IP packets to off-MANET destinations. 549 The following sections discuss post-autoconfiguration operations: 551 5.1. Forwarding Packets to Off-MANET Destinations 553 MNBRs consult the inner IP forwarding table to determine the next hop 554 address (e.g., the VET interface address of another MNBR) for 555 forwarding packets to off-MANET destinations. When there is no 556 forwarding information available, the MNBR can discover the next-hop 557 through FQDN or reverse lookup using the same name resolution 558 services as for MNGW discovery (see Section 4.3). 560 For forwarding to next-hop addresses over VET interfaces that use 561 IPv6-in-IPv4 encapsulation, MNBRs determine the outer destination 562 address through static extraction of the IPv4 address embedded in the 563 next-hop ISATAP address. For other IP-in-IP encapsulations, 564 determination of the outer destination address is through 565 administrative configuration or through an unspecified alternate 566 method. 568 MNBRs that use IPv6 as the inner protocol can discover default router 569 preferences and more-specific routes [RFC4191] by sending an RS over 570 the VET interface to elicit an RA from another MNBR. After default 571 and/or more-specific routes are discovered, the MNBR can forward IP 572 packets via a specific MNBR as the next-hop router on the VET 573 interface. When multiple default routers are available, the MNBR can 574 use default router preferences, routing protocol information, traffic 575 engineering configurations, etc. to select the best exit router. 577 5.2. MANET-Local Communications 579 When permitted by policy, pairs of MNRs that configure the endpoints 580 of a communications session can avoid VET interface encapsulation by 581 directly invoking the outer IP protocol using MLAs assigned to their 582 MANET interfaces. For example, when the outer protocol is IPv4 a 583 pair of communicating MNRs can use IPv4 MLAs for direct 584 communications over their MANET interfaces without using the VET 585 interface. 587 5.3. Multicast 589 In multicast-capable deployments, MNRs provide a MANET-wide 590 multicasting service such as Simplified Multicast Forwarding (SMF) 591 [I-D.ietf-manet-smf] over their MANET interfaces such that outer IP 592 multicast messages of site- or greater scope will be propagated 593 across the MANET. For such deployments, MNBRs can also provide an 594 inner IP multicast/broadcast capability over their VET interfaces 595 through mapping of the inner IP multicast address space to the outer 596 IP multicast address space. 598 MNBRs encapsulate inner IP multicast messages sent over the VET 599 interface in any mid-layer headers (e.g., IPsec, SEAL, etc.) plus an 600 outer IP header with a site-scoped outer IP multicast address as the 601 destination. For the case of IPv6 and IPv4 as the inner/outer 602 protocols (respectively), [RFC2529] provides mappings from the IPv6 603 multicast address space to the IPv4 multicast address space. For 604 other IP-in-IP encapsulations, mappings are established through 605 administrative configuration or through an unspecified alternate 606 method. 608 For multicast-capable MANETs, use of the inner IP multicast service 609 for operating the ND protocol over the VET interface is available but 610 should be used sparingly to minimize MANET-wide flooding. Therefore, 611 MNBRs should use unicast ND services over the VET interface instead 612 of multicast whenever possible. 614 5.4. Service Discovery 616 MNRs can peform MANET-wide service discovery using a suitable name- 617 to-address resolution service. Examples of flooding-based services 618 include the use of LLMNR [RFC4759] over the VET interface or mDNS 619 [I-D.cheshire-dnsext-multicastdns] over an underlying MANET 620 interface. More scalable and efficient service discovery mechanisms 621 for MANETs are for further study. 623 6. IANA Considerations 625 A site-scoped IPv4 multicast group (TBD) for DHCPv4 server discovery 626 is requested. 628 7. Security Considerations 630 Security considerations for MANETs are found in 631 [RFC2501][I-D.ietf-autoconf-manetarch] and apply also to the 632 mechanisms and procedures specified in this document. 634 Security considerations for MANET routing protocols that may be used 635 within this context are found in their respective specifications. 637 8. Related Work 639 The authors acknowledge the work done by Brian Carpenter and Cyndi 640 Jung in [RFC2529] that introduced the concept of intra-site automatic 641 tunneling. This concept was later called: "Virtual Ethernet" and 642 investigated by Quang Nguyen under the guidance of Dr. Lixia Zhang. 644 Telcordia has proposed DHCP-related solutions for the CECOM MOSAIC 645 program. The Naval Research Lab (NRL) Information Technology 646 Division uses DHCP in their MANET research testbeds. Various 647 proposals within the IETF have suggested similar mechanisms. 649 9. Acknowledgements 651 The following individuals gave direct and/or indirect input that was 652 essential to the work: Jari Arkko, Teco Boot, Emmanuel Bacelli, James 653 Bound, Thomas Clausen, Eric Fleischman, Bob Hinden, Joe Macker, 654 Thomas Narten, Alexandru Petrescu, John Spence, Jinmei Tatuya, Dave 655 Thaler, Michaela Vanderveen and others in the IETF AUTOCONF and MANET 656 working groups. Many others have provided guidance over the course 657 of many years. 659 10. Contributors 661 Thomas Henderson (thomas.r.henderson@boeing.com) contributed to this 662 document. Ian Chakeres (ian.chakeres@gmail.com) contributed to 663 earlier versions of the document. 665 11. References 666 11.1. Normative References 668 [I-D.ietf-dhc-subnet-alloc] 669 Johnson, R., "Subnet Allocation Option", 670 draft-ietf-dhc-subnet-alloc-07 (work in progress), 671 July 2008. 673 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 674 September 1981. 676 [RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or 677 converting network protocol addresses to 48.bit Ethernet 678 address for transmission on Ethernet hardware", STD 37, 679 RFC 826, November 1982. 681 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 682 RFC 2131, March 1997. 684 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 685 (IPv6) Specification", RFC 2460, December 1998. 687 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 688 and M. Carney, "Dynamic Host Configuration Protocol for 689 IPv6 (DHCPv6)", RFC 3315, July 2003. 691 [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic 692 Host Configuration Protocol (DHCP) version 6", RFC 3633, 693 December 2003. 695 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 696 More-Specific Routes", RFC 4191, November 2005. 698 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 699 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 700 September 2007. 702 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 703 Address Autoconfiguration", RFC 4862, September 2007. 705 [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site 706 Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, 707 March 2008. 709 11.2. Informative References 711 [I-D.cheshire-dnsext-multicastdns] 712 Cheshire, S. and M. Krochmal, "Multicast DNS", 713 draft-cheshire-dnsext-multicastdns-06 (work in progress), 714 August 2006. 716 [I-D.fuller-240space] 717 Fuller, V., "Reclassifying 240/4 as usable unicast address 718 space", draft-fuller-240space-02 (work in progress), 719 March 2008. 721 [I-D.ietf-autoconf-manetarch] 722 Chakeres, I., Macker, J., and T. Clausen, "Mobile Ad hoc 723 Network Architecture", draft-ietf-autoconf-manetarch-07 724 (work in progress), November 2007. 726 [I-D.ietf-ipv6-ula-central] 727 Hinden, R., "Centrally Assigned Unique Local IPv6 Unicast 728 Addresses", draft-ietf-ipv6-ula-central-02 (work in 729 progress), June 2007. 731 [I-D.ietf-manet-smf] 732 Macker, J. and S. Team, "Simplified Multicast Forwarding 733 for MANET", draft-ietf-manet-smf-07 (work in progress), 734 February 2008. 736 [I-D.templin-seal] 737 Templin, F., "The Subnetwork Encapsulation and Adaptation 738 Layer (SEAL)", draft-templin-seal-22 (work in progress), 739 June 2008. 741 [RFC1122] Braden, R., "Requirements for Internet Hosts - 742 Communication Layers", STD 3, RFC 1122, October 1989. 744 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 745 E. Lear, "Address Allocation for Private Internets", 746 BCP 5, RFC 1918, February 1996. 748 [RFC2501] Corson, M. and J. Macker, "Mobile Ad hoc Networking 749 (MANET): Routing Protocol Performance Issues and 750 Evaluation Considerations", RFC 2501, January 1999. 752 [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 753 Domains without Explicit Tunnels", RFC 2529, March 1999. 755 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains 756 via IPv4 Clouds", RFC 3056, February 2001. 758 [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", 759 RFC 3753, June 2004. 761 [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., 762 Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. 763 Wood, "Advice for Internet Subnetwork Designers", BCP 89, 764 RFC 3819, July 2004. 766 [RFC3927] Cheshire, S., Aboba, B., and E. Guttman, "Dynamic 767 Configuration of IPv4 Link-Local Addresses", RFC 3927, 768 May 2005. 770 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 771 RFC 3972, March 2005. 773 [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast 774 Addresses", RFC 4193, October 2005. 776 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 777 Internet Protocol", RFC 4301, December 2005. 779 [RFC4759] Stastny, R., Shockey, R., and L. Conroy, "The ENUM Dip 780 Indicator Parameter for the "tel" URI", RFC 4759, 781 December 2006. 783 [RFC4852] Bound, J., Pouffary, Y., Klynsma, S., Chown, T., and D. 784 Green, "IPv6 Enterprise Network Analysis - IP Layer 3 785 Focus", RFC 4852, April 2007. 787 [RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, 788 June 2007. 790 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 791 Extensions for Stateless Address Autoconfiguration in 792 IPv6", RFC 4941, September 2007. 794 Appendix A. Duplicate Address Detection (DAD) Considerations 796 A-priori uniqueness determination (also known as "pre-service DAD") 797 for an MLA assigned on a MANET interface (such as specified in 798 [RFC4862]) would require either flooding the entire MANET or somehow 799 discovering a link in the MANET on which a node that configures a 800 duplicate address is attached and performing a localized DAD exchange 801 on that link. But, the control message overhead for such a MANET- 802 wide DAD would be substantial and prone to false-negatives due to 803 packet loss and intermittent connectivity. An alternative to pre- 804 service DAD is to autoconfigure pseudo-random MLAs on MANET 805 interfaces and employ a passive in-service DAD (e.g., one that 806 monitors routing protocol messages for duplicate assignments). 808 Pseudo-random IPv6 MLAs can be generated with mechanisms such as 809 CGAs, IPv6 privacy addresses, etc. with very small probability of 810 collision. Pseudo-random IPv4 MLAs can be generated through random 811 assignment from a suitably large IPv4 prefix space, e.g., the soon- 812 to-be-reclassified 240/4 space [I-D.fuller-240space]. 814 Consistent operational practices can assure uniqueness for MNGW- 815 aggregated addresses/prefixes, while statistical properties for 816 pseudo-random address self-generation can assure uniqueness for the 817 MLAs assigned on a MNR's MANET interfaces. Still, an MLA delegation 818 authority should be used when available, while a passive in-service 819 DAD mechanism should be used to detect MLA duplications when there is 820 no MLA delegation authority. 822 Appendix B. Change Log 824 (Note to RFC editor - this section to be removed before publication 825 as an RFC.) 827 Changes from -14 to 15: 829 o title change to "Virtual Enterprise Traversal (VET) for MANETs". 831 o Address review comments 833 Changes from -12 to 14: 835 o title change to "The MANET Virtual Ethernet Abstraction". 837 o Minor section rearrangement. 839 o Clartifications on portable and self-configured prefixes. 841 o Clarifications on DHCPv6 prefix delegation procedures. 843 Changes from -11 to 12: 845 o title change to "MANET Autoconfiguration using Virtual Ethernet". 847 o DHCP prefix delegation for both IPv4 and IPv6 as primary address 848 delegation mechanism. 850 o IPv6 SLAAC for address autoconfiguration on the VET interface. 852 o fixed editorials based on comments received. 854 Changes from -10 to 11: 856 o removed the transparent/opaque VET portal abstractions. 858 o removed routing header as an option for MANET exit router 859 selection. 861 o included IPv6 SLAAC as an endorsed address configuration mechanism 862 for the VET interface. 864 Changes from -08 to -09: 866 o Introduced the term "VET". 868 o Changed address delegation language to speak of "MNBR-aggregated" 869 instead of global/local. 871 o Updated figures 1-3. 873 o Explained why a MANET interface is "neutral". 875 o Removed DHCPv4 "MLA Address option". Now, MNBRs can only be 876 DHCPv4 servers; not relays. 878 Changes from -07 to -08: 880 o changed terms "unenhanced" and "enhanced" to "transparent" and 881 "opaque". 883 o revised MANET Router diagram. 885 o introduced RFC3753 terminology for Mobile Router; ingress/egress 886 interface. 888 o changed abbreviations to "MNR" and "MNBR". 890 o added text on ULAs and ULA-Cs to "Self-Generated Addresses". 892 o rearranged Section 3.1. 894 o various minor text cleanups 896 Changes from -06 to -07: 898 o added MANET Router diagram. 900 o added new references 902 o various minor text cleanups 903 Changed from -05 to -06: 905 o Changed terms "raw" and "cooked" to "unenhanced" and "enhanced". 907 o minor changes to preserve generality 909 Changed from -04 to -05: 911 o introduced conceptual "virtual ethernet" model. 913 o support "raw" and "cooked" modes as equivalent access methods on 914 the virutal ethernet. 916 Changed from -03 to -04: 918 o introduced conceptual "imaginary shared link" as a representation 919 for a MANET. 921 o discussion of autonomous system and site abstractions for MANETs 923 o discussion of autoconfiguration of CGAs 925 o new appendix on IPv6 StateLess Address AutoConfiguration 927 Changes from -02 to -03: 929 o updated terminology based on RFC2461 "asymmetric reachability" 930 link type; IETF67 MANET Autoconf wg discussions. 932 o added new appendix on IPv6 Neighbor Discovery and Duplicate 933 Address Detection 935 o relaxed DHCP server deployment considerations allow DHCP servers 936 within the MANET itself 938 Changes from -01 to -02: 940 o minor updates for consistency with recent developments 942 Changes from -00 to -01: 944 o new text on DHCPv6 prefix delegation and multilink subnet 945 considerations. 947 o various editorial changes 949 Authors' Addresses 951 Fred L. Templin (editor) 952 Boeing Phantom Works 953 P.O. Box 3707 MC 7L-49 954 Seattle, WA 98124 955 USA 957 Email: fltemplin@acm.org 959 Steven W. Russert 960 Boeing Phantom Works 961 P.O. Box 3707 MC 7L-49 962 Seattle, WA 98124 963 USA 965 Email: steven.w.russert@boeing.com 967 Seung Yi 968 Boeing Phantom Works 969 P.O. Box 3707 MC 7L-49 970 Seattle, WA 98124 971 USA 973 Email: seung.yi@boeing.com 975 Full Copyright Statement 977 Copyright (C) The IETF Trust (2008). 979 This document is subject to the rights, licenses and restrictions 980 contained in BCP 78, and except as set forth therein, the authors 981 retain all their rights. 983 This document and the information contained herein are provided on an 984 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 985 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 986 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 987 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 988 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 989 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 991 Intellectual Property 993 The IETF takes no position regarding the validity or scope of any 994 Intellectual Property Rights or other rights that might be claimed to 995 pertain to the implementation or use of the technology described in 996 this document or the extent to which any license under such rights 997 might or might not be available; nor does it represent that it has 998 made any independent effort to identify any such rights. Information 999 on the procedures with respect to rights in RFC documents can be 1000 found in BCP 78 and BCP 79. 1002 Copies of IPR disclosures made to the IETF Secretariat and any 1003 assurances of licenses to be made available, or the result of an 1004 attempt made to obtain a general license or permission for the use of 1005 such proprietary rights by implementers or users of this 1006 specification can be obtained from the IETF on-line IPR repository at 1007 http://www.ietf.org/ipr. 1009 The IETF invites any interested party to bring to its attention any 1010 copyrights, patents or patent applications, or other proprietary 1011 rights that may cover technology that may be required to implement 1012 this standard. Please address the information to the IETF at 1013 ietf-ipr@ietf.org.