Network Working Group F. Templin Internet-Draft S. Russert Intended status: Informational S. Yi Expires: May 17, 2008 Boeing Phantom Works November 14, 2007 MANET Autoconfiguration draft-templin-autoconf-dhcp-10.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 17, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract Mobile Ad-hoc Networks (MANETs) connect routers on links with asymmetric reachability characteristics, and may also connect to other networks including the Internet. Routers in MANETs must have a way to automatically provision IP addresses/prefixes and other information. This document specifies mechanisms for MANET autoconfiguration; both IPv4 and IPv6 are discussed. Templin, et al. Expires May 17, 2008 [Page 1] Internet-Draft MANET Autoconfiguration November 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. MANET Autoconfiguration . . . . . . . . . . . . . . . . . . . 6 3.1. MANET Router (MNR) Operation . . . . . . . . . . . . . . . 6 3.1.1. MANET Local Address (MLA) Configuration . . . . . . . 6 3.1.2. MNBR List Discovery . . . . . . . . . . . . . . . . . 7 3.1.3. VET Interface Configuration . . . . . . . . . . . . . 8 3.1.4. Reachability Confirmation . . . . . . . . . . . . . . 9 3.1.5. MNBR-Aggregated Address/Prefix Autoconfiguration . . . 9 3.1.6. Unique-local Address Autoconfiguration . . . . . . . . 11 3.1.7. Self-Generated IPv6 Interface Identifiers . . . . . . 11 3.1.8. Forwarding Packets to Off-MANET Destinations . . . . . 11 3.2. MANET Border Router (MNBR) Operation . . . . . . . . . . . 12 3.3. MANET Flooding . . . . . . . . . . . . . . . . . . . . . . 12 3.4. Changes to the Neighbor Discovery Model . . . . . . . . . 12 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 5. Security Considerations . . . . . . . . . . . . . . . . . . . 13 6. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 13 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . . 13 9.2. Informative References . . . . . . . . . . . . . . . . . . 14 Appendix A. IPv6 Neighbor Discovery (ND) and Duplicate Address Detection (DAD) . . . . . . . . . . . . . . . 15 Appendix B. IPv6 StateLess Address AutoConfiguration (SLAAC) . . 16 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 Intellectual Property and Copyright Statements . . . . . . . . . . 20 Templin, et al. Expires May 17, 2008 [Page 2] Internet-Draft MANET Autoconfiguration November 2007 1. Introduction Mobile Ad-hoc Networks (MANETs) connect MANET Routers (MNRs) on links with asymmetric reachability characteristics (see: [RFC2461], Section 2.2). MNRs may participate in a routing protocol over MANET interfaces to discover routes across the MANET using multiple Layer-2 or Layer-3 forwarding hops if necessary. MANETs may also connect to other networks including the Internet via MANET Border Routers (MNBRs), and MNRs may be multiple hops away from their nearest MNBR in some scenarios. A MANET may span an entire Autonomous System (AS) or may be as simple as a small collection of MNRs (and their attached networks). A MANET may contain other MANETs, and may also be a subnetwork of a larger MANET. MANETs that comprise homogeneous link types can configure the routing protocol to operate as a sub-IP layer mechanism such that IP sees the MANET as an ordinary shared link the same as for a (bridged) campus LAN. In that case, a single IP hop is sufficient to traverse the MANET. MANETs that comprise heterogeneous link types must instead (or, in addition) provide a routing service that operates as an IP layer mechanism to accommodate media types with dissimilar Layer-2 address formats and maximum transmission units (MTUs). In that case, multiple IP hops may be necessary to traverse the MANET such that MNRs require specialized autoconfiguration procedures to avoid multilink subnet issues [RFC4903]. Conceptually, a MNR embodies a router entity that connects its attached networks to MANETs and/or other networks including the Internet (see: Figure 1). The router entity also connects to an imaginary Virtual Ethernet (VET) via a virtual interface configured over its MANET interfaces and used to avoid multilink subnet issues. An "opaque" view of the VET sees the MANET as a fully-connected shared link that connects all MNRs, while a "transparent" view sees the MANET as a multilink site. For each distinct MANET to which they connect, MNRs discover a list of MNBRs that determines the MANET's identity. An MNR (and its attached networks) is a "site" unto itself, therefore a MANET is a "site-of-sites". This document specifies mechanisms and operational practices for MANET autoconfiguration with multilink subnet avoidance. Operation using standard DHCP [RFC2131][I-D.ietf-dhc-subnet-alloc][RFC3315][RFC3633] and neighbor discovery [RFC1256][RFC2461][RFC2462] mechanisms is assumed unless otherwise specified. Both IPv4 [RFC0791] and IPv6 [RFC2460] are discussed. Templin, et al. Expires May 17, 2008 [Page 3] Internet-Draft MANET Autoconfiguration November 2007 2. Terminology The terminology in [I-D.ietf-autoconf-manetarch] and the normative references apply. The following terms are defined within the scope of this document: subnetwork the same as defined in [RFC3819]. egress/ingress interface the same as defined in ([RFC3753], Section 3). Mobile Ad-hoc Network (MANET) a connected network region of MANET routers that maintain a routing structure among themselves over asymmetric reachability links (see: [RFC2461], Section 2.2). A MANET may span an entire Autonomous System (AS) or only a small collection of MANET routers, and a MANET may also be a subnetwork of a larger MANET. A MANET router (and its attached networks) is a site unto itself, and a MANET is therefore a site-of-sites. (Note that this document considers the terms "MANET" and "site" as functional equivalents.) Further information on the characteristics of MANETs can be found in [RFC2501]. MANET Router (MNR) a mobile router that forwards packets on behalf of both other MNRs over its MANET interfaces and networks attached on its ingress interfaces. A MNR can also forward packets to other networks either directly via its egress interfaces or indirectly via an MNBR. For the purpose of this specification, an MNR comprises a router entity, one or more host entities, and its attached ingress/egress/MANET interfaces (see: Figure 1). MANET Border Router (MNBR) an MNR that connects a MANET to "upstream" networks (e.g., the Internet) via egress interfaces, and delegates addresses/prefixes to other MNRs. MANET Interface a MANET Router's attachment to a link in a MANET. A MANET interface is "neutral" in its orientation, i.e., it is inherently neither egress nor ingress. In particular, a packet may need to traverse several MANET interfaces before it is forwarded via either an egress or ingress interface. Templin, et al. Expires May 17, 2008 [Page 4] Internet-Draft MANET Autoconfiguration November 2007 MANET Local Address (MLA) an address configured by an MNR that is unique within the MANET; it is used as an identifier for operating the routing protocol and may also be assigned to a MANET interface as a locator for packet forwarding within the scope of the MANET. Virtual Ethernet (VET) an imaginary shared link that connects all MNRs in a MANET. VET interface a MNR's attachment to a VET. Each VET interface is configured over a set of underlying MANET interface(s) belonging to the same MANET, and presents both opaque and transparent "portals" (see: Figure 2 and Figure 3). The opaque portal encapsulates each IP packet in an outer IP header then sends it on an underlying MANET interface such that the TTL/HOP Limit in the inner IP header is not decremented as the packet traverses the MANET, i.e., the opaque portal views the MANET as a unified shared link. In this sense, the opaque portal presents an automatic tunneling abstraction. The transparent portal sends each IP packet on an underlying MANET interface without further encapsulation such that the TTL/Hop Limit may be decremented as the packet traverses the MANET, i.e., the transparent portal views the MANET as a multilink site. Extended Neighbor Discovery (END) message an IP Neighbor Discovery (ND) message [RFC1256] [RFC2461] transmitted on the transparent portal of a VET interface with an MLA of the underlying MANET interface as a source address and with destination address set to an MLA or a site-scoped multicast address. The TTL/Hop Limit in END messages may be decremented as the message traverses the MANET. The following figure depicts the architectural model for a MANET router: Templin, et al. Expires May 17, 2008 [Page 5] Internet-Draft MANET Autoconfiguration November 2007 Egress Interfaces (to Internet) x x x | | | +------------------------+---+--------+----------+ | Internal hosts | | | | M | and routers | | .... | | A | ,-. | +---+---+--------+---+ | N | (H1 )---+ | /| | E | | `-' | | I /*+------+--< T | . | +---+ | | n|**| | | . +--|R1 |---+-----+ t|**| | I | . | +---+ | | Router V e|**+------+--< n | | ,-. | | E r|**| . | t | (H2 )---+ | Entity T f|**| . | e | `-' | . | a|**| . | r | . | c|**| . | f | ,-. . | e \*+------+--< a | (Hn )---------+ \| | c | `-' +---+---+--------+---+ | e | Ingress Interfaces | | .... | | s | (to internal networks) | | | | +------------------------+---+--------+----------+ | | | x x x Ingress Interfaces (to mobile networks) Figure 1: MANET Router 3. MANET Autoconfiguration 3.1. MANET Router (MNR) Operation MNRs configure egress interfaces that connect "upstream" toward fixed Internet infrastructure, ingress interfaces that connect "downstream" toward attached mobile networks, and MANET interfaces that are "neutral" in the sense that the packets they forward may need to traverse several other MANET interfaces before they are forwarded via either an egress or ingress interface. MNRs configure VET interfaces and engage in the routing protocol over their MANET interfaces; they also obtain addresses/prefixes and other autoconfiguration information using the mechanisms and operational practices specified in the following sections: 3.1.1. MANET Local Address (MLA) Configuration Upon joining a MANET, each MNR first configures MANET Local Addresses (MLAs) that it will use for operating the routing protocol and/or for Templin, et al. Expires May 17, 2008 [Page 6] Internet-Draft MANET Autoconfiguration November 2007 local communications within the MANET. IPv6 MLAs can be manually configured, administratively assigned, autoconfigured using DHCP, autoconfigured using IPv6 StateLess Address AutoConfiguration (SLAAC) [RFC2462], or self-generated using IPv6 Unique Local Addresses (ULAs) [RFC4193][I-D.ietf-ipv6-ula-central]. IPv6 MLAs include interface identifiers that are either managed for uniqueness (e.g., see: [RFC4291], Appendix A) or self-generated using a suitable pseudo- random interface identifier generation mechanism (e.g., Cryptographically Generated Addresses (CGAs) [RFC3972], IPv6 privacy addresses [I-D.ietf-ipv6-privacy-addrs-v2], etc.). IPv4 MLAs can be manually configured, administratively assigned, autoconfigured using DHCP or self-generated using an unspecified IPv4 unique local address configuration mechanism. (Such a mechanism could be considered as a site-scoped equivalent to IPv4 link-local addresses [RFC3927].) When there is no manually configured/administratively assigned MLA, the choice of autoconfiguring an MLA using DHCP or self-generating one using some other mechanism is up to the MNR and may depend on the particular MANET deployment scenario. DHCP-generated MLAs have the benefit of a "managed" avoidance of address collisions, while self- generated MLAs must be monitored for collisions with other nodes that might assign a duplicate. Note also that DHCP service for MLA configuration may not be available in all MANETs. Since a MNR initially has no non-link-local addresses, DHCP configuration of MLAs may require relay support from other MNRs that have already been autoconfigured within the MANET. This means that MNRs with assigned MLAs should be prepared to relay another MNR's DHCP requests, e.g. to a site-scoped multicast address, to a unicast address(es), etc. 3.1.2. MNBR List Discovery After configuring MLAs, the MNR next engages in any routing protocol(s) over its MANET interfaces and discovers the list of MNBRs (if any) on the MANET. The list of MNBRs can be discovered through information conveyed in the routing protocol, or through an alternate discovery mechanism, e.g., per [RFC4214], Section 8.3.2. The list of MNBRs serves as an identifier for the MANET. If the list of MNBRs is NULL, an alternate token such as the Layer-2 address of an ordinary MNR can serve as an identifier for the MANET. Templin, et al. Expires May 17, 2008 [Page 7] Internet-Draft MANET Autoconfiguration November 2007 3.1.3. VET Interface Configuration The MNR configures a VET interface for the MANET over the underlying MANET interfaces. The opaque portal of the VET interface configures a link-local address that is assured to be unique among the VET interfaces of all MNRs in the MANET, e.g., an ISATAP link-local address ([RFC4214], Section 6.2) derived from the IPv4 MLA of an underlying MANET interface. IP packets sent via the opaque portal are encapsulated in an outer IP header then submitted to ip_output() for transmission on an underlying MANET interface. The transparent portal of the VET interface configures no addresses itself, but rather provides IP with direct access to the underlying MANET interfaces and their associated MLAs. IP packets sent via the transparent portal are transmitted unencapsulated on an underlying MANET interface, but may require an IPv4 source routing header (likewise IPv6 routing header) or a subnetwork-specific encapsulation to direct packets to specific MNBRs. Figure 2 depicts the protocol stack model for the VET output routine, and Figure 3 depicts the corresponding model for the VET input routine: +--------------------------------------------------+ | | ip_output() | | +--------------------------------------------------+ | | vet_output() | | | | | _ transparent portal _ ___ opaque portal _____ | p |/ \ / \| a | - MANET intf already | - select MANET intf | c | selected | - encapsulate in IP | k | - insert routing hdr | - forward to MANET intf | e | (if necessary) | via ip_output() | t | - forward directly to +-------------------------+ s | MANET intf | ip_output() | +--------------+---------+----+-...-+--------------+ | | MANET Intf 0 | MANET Intf 1 | ... | MANET Intf n | | | (MLA 0) | (MLA 1) | ... | (MLA n) | | +--------------+--------------+-...-+--------------+ v Figure 2: vet_output() Templin, et al. Expires May 17, 2008 [Page 8] Internet-Draft MANET Autoconfiguration November 2007 +--------------------------------------------------+ ^ | ip_input() | | +--------------------------------------------------+ | | vet_input() | | | p | _ transparent portal _ ___ opaque portal ____ | a |/ \ / \| c | - submit to ip_input() | - decapsulate packet | k | | - submit to ip_input() | e | +-------------------------+ t | | ip_input() | s +--------------+---------+----+-...-+--------------+ | MANET Intf 0 | MANET Intf 1 | ... | MANET Intf n | | | (MLA 0) | (MLA 1) | ... | (MLA n) | | +--------------+--------------+-...-+--------------+ | Figure 3: vet_input() 3.1.4. Reachability Confirmation After the MNR configures a VET interface, it can confirm reachability of MNRs/MNBRs and (in the case of IPv6) discover prefixes associated with the VET. The MNR can confirm reachability by sending/receiving END messages over the transparent portal, by sending/receiving ordinary ND messages over the opaque portal, by issuing DHCP requests, via reachability information conveyed in the routing protocol itself, or through some other means associated with the particular MANET subnetwork technology. 3.1.5. MNBR-Aggregated Address/Prefix Autoconfiguration After the MNR discovers MNBRs, it can acquire MNBR-aggregated addresses/prefixes using either DHCP or IPv6 Stateless Address AutoConfiguration (SLAAC) (but see Appendix B for further considerations on SLAAC). These addresses/prefixes are delegated by specific MNBRs, and may be: o global-scope and provider aggregated o global-scope and provider-independent o global-scope and 6to4 [RFC3056] o unique-local scope and centrally administrated o unique-local scope and locally assigned Templin, et al. Expires May 17, 2008 [Page 9] Internet-Draft MANET Autoconfiguration November 2007 o other non-link-local scope When DHCP is used, a DHCP client associated with the MNR's host entity forwards a DHCP DISCOVER (DHCPv4) or Solicit (DHCPv6) request to a DHCP relay associated with its router entity to request IP address/prefix delegations (i.e., the MNR acts as both DHCP client and relay). The relay function then forwards the request to the unicast addresses of one or more MNBRs, to a site-scoped multicast address, or to another known DHCP server within the MANET. For DHCPv6, the MNR's relay function writes an address from the VET interface in the "peer-address" field and also writes an address from the prefix associated with the VET in the "link-address" field (if a prefix is available). The MNR can also (or, instead) use DHCPv6 prefix delegation [RFC3633] to obtain addresses/prefixes via MNBRs for assignment and/or further sub-delegation on networks connected on its ingress interfaces. (Note that the MNR can obtain /128 prefixes using DHCP prefix delegation the same as for any IPv6 prefix.) For DHCPv4, the MNR's relay function writes an address from the VET interface in the 'giaddr' field. If necessary to identify the MNR's ingress interface, the relay also includes a link selection sub- option [RFC3527] with an address from the prefix associated with the VET (if a prefix is available). The MNR can also (or, instead) use DHCPv4 prefix delegation [I-D.ietf-dhc-subnet-alloc] to obtain addresses/prefixes via MNBRs for further assignment and/or further sub-delegation on networks connected on its ingress interfaces. (Note that the MNR can obtain /32 prefixes using DHCP prefix delegation the same as for any IPv4 prefix.) The DHCP request will elicit a DHCP reply from a server with IP address/prefix delegations that are aggregated by one or more MNBRs. When addresses are delegated, the MNR assigns the resulting addresses to an ingress interface, i.e., it does not assign the addresses on the VET interface or an underlying MANET interface. When prefixes are delegated, the MNR can assign and/or further sub-delegate them to networks connected on its ingress interfaces. If the MANET subnetwork uses a proactive routing protocol, the MNR can advertise the delegated addresses/prefixes into the routing protocol during the duration of the delegation lifetimes. The DHCP server ensures IP address/prefix delegations that are unique within the MANET. By assigning these IP addresses/prefixes only on ingress interfaces there is no requirement for the MNR to perform Duplicate Address Detection (DAD) for them over its MANET interfaces or VET interfaces (but see Appendix A for further DAD considerations). Templin, et al. Expires May 17, 2008 [Page 10] Internet-Draft MANET Autoconfiguration November 2007 3.1.6. Unique-local Address Autoconfiguration Independent of any MNBR-aggregated addresses/prefixes (see: Section 3.1.5), MNRs can self-generate IPv6 Unique Local Address (ULA) prefixes [RFC4193][I-D.ietf-ipv6-ula-central] and sub-delegate them on networks connected on their ingress interfaces. Note that in some scenarios a MNR may not require any MNBR-aggregated address/ prefix assignments at all, and can use its own ULAs instead. Self-generated unique-local addresses are portable and not aggregated by MNBRs. The addresses can therefore travel with the MNR as it moves to new MANETs and/or configures peering arrangements with MNRs in other MANETs. Self-generation of unique-local addresses can therefore occur independently of any other MNR autoconfiguration considerations. 3.1.7. Self-Generated IPv6 Interface Identifiers MNR's can self-generate IPv6 interface identifiers such as specified for CGAs [RFC3972], IPv6 privacy address [I-D.ietf-ipv6-privacy-addrs-v2], etc. For MNBR-aggregated address/prefix autoconfiguration (see: Section 3.1.5), the MNR can propose a self-generated address to the DHCPv6 server which will delegate the address to the MNR for assignment on an ingress interface if the proposed address is unique. 3.1.8. Forwarding Packets to Off-MANET Destinations After the MNR configures IP addresses/prefixes, it can forward IP packets to off-MANET destinations. For IPv6, MNRs can discover default router preferences and more- specific routes per [RFC4191] by sending unicast Router Solicitations over the VET interface opaque portal to elicit Router Advertisements from MNBRs and other MNRs. MNRs/MNBRs should therefore send Router Advertisements with default router preferences and/or more-specific routes in response to unicast Router Solicitations. This matches the operational framework established by ISATAP [RFC4214]. Once default routers and/or more-specific routes are discovered, the MNR can either 1) forward the packets via the opaque portal with an MLA for an MNR/MNBR as the destination in the outer IP header, or 2) forward the packets via the transparent portal and insert an IPv4 source routing header (likewise IPv6 routing header) or a subnetwork- specific encapsulation. (For MANETs in which 'default' and/or more-specific routes are made Templin, et al. Expires May 17, 2008 [Page 11] Internet-Draft MANET Autoconfiguration November 2007 available through the routing protocol, the MNR can optionally forward IP packets to off-MANET destinations using the transparent VET interface portal.) 3.2. MANET Border Router (MNBR) Operation MNBRs connect the MANET to upstream networks over egress interfaces. MNBRs send/receive END messages on the VET interface transparent portal and/or send/receive ordinary ND messages on the opaque portal. When stateful configuration is desired, MNBRs should set the M bit to 1 in the RA messages they send. (Stateless configuration is also possible, but see: Appendix B for further considerations on using SLAAC for MANET Autoconfiguration.) For DHCPv6, MNBRs act as DHCP relays and/or servers for a MNR's DHCP requests/replies. For DHCPv4, MNBRs may only act as DHCP servers, since the MLA address in the 'giaddr' field is not routable outside the scope of the MANET. 3.3. MANET Flooding MANETs that operate routing as an IP layer service should deploy a multicast flooding service (e.g., Simplified Multicast Forwarding (SMF) [I-D.ietf-manet-smf]) so that site-scoped multicast messages will be propagated across the MANET. 3.4. Changes to the Neighbor Discovery Model Ordinary link-scoped ND messages work as-normal over the VET interface opaque portal, so ND operation over the opaque portal requires no changes to the standard IP neighbor discovery protocols specified in [RFC1256][RFC2461]. END messages over the VET interface transparent portal must use a site-scoped unicast source address (i.e., an MLA) and an MLA or site- scoped multicast destination address such that the messages may be forwarded by a router and have their TTL/Hop Limit decremented on the path. This means that END messages provide a site-scoped (and not link-scoped) discovery service which represents a departure from the link-scoped services specified in [RFC1256][RFC2461]. 4. IANA Considerations A site-scoped IPv4 multicast group for: "All-MANET-Routers", or: "All-Site-Routers" is requested, e.g., to support MANET flooding for site-scoped service discovery (see: Section 3.3). Templin, et al. Expires May 17, 2008 [Page 12] Internet-Draft MANET Autoconfiguration November 2007 5. Security Considerations Threats relating to MANET routing protocols also apply to this document. 6. Related Work The authors acknowledge the work done by Brian Carpenter and Cyndi Jung in [RFC2529] that introduced the concept of intra-site automatic tunneling. This concept was later called: "Virtual Ethernet" and researched by Quang Nguyen under the guidance of Dr. Lixia Zhang. Telcordia has proposed DHCP-related solutions for the CECOM MOSAIC program. The Naval Research Lab (NRL) Information Technology Division uses DHCP in their MANET research testbeds. Various IETF AUTOCONF working group proposals have suggested similar mechanisms. 7. Acknowledgements The following individuals gave direct and/or indirect input that was essential to the work: Jari Arkko, Teco Boot, Emmanuel Bacelli, James Bound, Thomas Clausen, Eric Fleischman, Bob Hinden, Joe Macker, Thomas Narten, Alexandru Petrescu, Jinmei Tatuya, Dave Thaler, and others in the IETF AUTOCONF and MANET working groups. Many others have provided guidance over the course of many years. 8. Contributors Thomas Henderson (thomas.r.henderson@boeing.com) contributed to this document. Ian Chakeres (ian.chakeres@gmail.com) contributed to earlier versions of the document. 9. References 9.1. Normative References [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981. [RFC1256] Deering, S., "ICMP Router Discovery Messages", RFC 1256, September 1991. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. Templin, et al. Expires May 17, 2008 [Page 13] Internet-Draft MANET Autoconfiguration November 2007 [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003. [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, November 2005. [RFC4214] Templin, F., Gleeson, T., Talwar, M., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 4214, October 2005. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. 9.2. Informative References [I-D.ietf-autoconf-manetarch] Chakeres, I., Macker, J., and T. Clausen, "Mobile Ad hoc Network Architecture", draft-ietf-autoconf-manetarch-07 (work in progress), November 2007. [I-D.ietf-dhc-subnet-alloc] Johnson, R., "Subnet Allocation Option", draft-ietf-dhc-subnet-alloc-05 (work in progress), June 2007. [I-D.ietf-ipv6-privacy-addrs-v2] Narten, T., "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", draft-ietf-ipv6-privacy-addrs-v2-05 (work in progress), October 2006. Templin, et al. Expires May 17, 2008 [Page 14] Internet-Draft MANET Autoconfiguration November 2007 [I-D.ietf-ipv6-ula-central] Hinden, R., "Centrally Assigned Unique Local IPv6 Unicast Addresses", draft-ietf-ipv6-ula-central-02 (work in progress), June 2007. [I-D.ietf-manet-smf] Macker, J., "Simplified Multicast Forwarding for MANET", draft-ietf-manet-smf-05 (work in progress), June 2007. [RFC2501] Corson, M. and J. Macker, "Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations", RFC 2501, January 1999. [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 Domains without Explicit Tunnels", RFC 2529, March 1999. [RFC3527] Kinnear, K., Stapp, M., Johnson, R., and J. Kumarasamy, "Link Selection sub-option for the Relay Agent Information Option for DHCPv4", RFC 3527, April 2003. [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", RFC 3753, June 2004. [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. Wood, "Advice for Internet Subnetwork Designers", BCP 89, RFC 3819, July 2004. [RFC3927] Cheshire, S., Aboba, B., and E. Guttman, "Dynamic Configuration of IPv4 Link-Local Addresses", RFC 3927, May 2005. [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", RFC 3972, March 2005. [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast Addresses", RFC 4193, October 2005. [RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, June 2007. Appendix A. IPv6 Neighbor Discovery (ND) and Duplicate Address Detection (DAD) In terms of ND, existing standards [RFC2461][RFC4291] require that a node configure a link-local address on each of its IPv6-enabled interfaces, but the primary requirement for link-locals seems to be Templin, et al. Expires May 17, 2008 [Page 15] Internet-Draft MANET Autoconfiguration November 2007 for the purpose of uniquely identifying routers on the link. It is therefore for further study as to whether MNRs should send RAs on MANET interfaces (or even configure link local addresses on MANET interfaces at all), since the transparent view of the MANET appears as a multilink peering point between distinct sites, and not a unified link. In terms of DAD, pre-service DAD for an MLA assigned on a MANET interface (such as specified in [RFC2462]) would require either flooding the entire MANET or somehow discovering a link in the MANET on which a node that configures a duplicate address is attached and performing a localized DAD exchange on that link. But, the control message overhead for such a MANET-wide DAD would be substantial and prone to false-negatives due to packet loss and node mobility. An alternative to pre-service DAD is to autoconfigure pseudo-random MLAs on MANET interfaces and employ a passive in-service DAD (e.g., one that monitors routing protocol messages for duplicate assignments). Pseudo-random link-local addresses can be generated with mechanisms such as CGAs, IPv6 privacy addresses, etc. with very small probability of collision. But, IPv6 ULAs also provide an additional 40 pseudo-random bits in the prefix. Statistical properties for pseudo-random address self-generation can assure uniqueness for the MLAs assigned on a MNR's MANET interfaces, and consistent operational practices can assure uniqueness for MNBR- aggregated addresses/prefixes. However, a passive in-service DAD mechanism should still be used to detect duplicates that were assigned through other means, e.g., manual configuration. Appendix B. IPv6 StateLess Address AutoConfiguration (SLAAC) For IPv6, the use of StateLess Address AutoConfiguration (SLAAC) [RFC2462] could be indicated by prefix information options in END and/or ordinary ND messages with the 'A' bit set to 1. MNRs that receive such messages could then self-generate an address from the prefix and assign it to the VET interface, then use a passive in- service DAD approach to detect duplicates within the MANET. But, if the MANET partitions, DAD might not be able to monitor the other partitions and address duplication could result. Further study on DAD implications for SLAAC in MANETs is required. Appendix C. Change Log (Note to RFC editor - this section to be removed before publication as an RFC.) Templin, et al. Expires May 17, 2008 [Page 16] Internet-Draft MANET Autoconfiguration November 2007 Changes from -08 to -09: o Introduced the term "VET". o Changed address delegation language to speak of "MNBR-aggregated" instead of global/local. o Updated figures 1-3. o Explained why a MANET interface is "neutral". o Removed DHCPv4 "MLA Address option". Now, MNBRs can only be DHCPv4 servers; not relays. Changes from -07 to -08: o changed terms "unenhanced" and "enhanced" to "transparent" and "opaque". o revised MANET Router diagram. o introduced RFC3753 terminology for Mobile Router; ingress/egress interface. o changed abbreviations to "MNR" and "MNBR". o added text on ULAs and ULA-Cs to "Self-Generated Addresses". o rearranged Section 3.1. o various minor text cleanups Changes from -06 to -07: o added MANET Router diagram. o added new references o various minor text cleanups Changed from -05 to -06: o Changed terms "raw" and "cooked" to "unenhanced" and "enhanced". o minor changes to preserve generality Changed from -04 to -05: Templin, et al. Expires May 17, 2008 [Page 17] Internet-Draft MANET Autoconfiguration November 2007 o introduced conceptual "virtual ethernet" model. o support "raw" and "cooked" modes as equivalent access methods on the virutal ethernet. Changed from -03 to -04: o introduced conceptual "imaginary shared link" as a representation for a MANET. o discussion of autonomous system and site abstractions for MANETs o discussion of autoconfiguration of CGAs o new appendix on IPv6 StateLess Address AutoConfiguration Changes from -02 to -03: o updated terminology based on RFC2461 "asymmetric reachability" link type; IETF67 MANET Autoconf wg discussions. o added new appendix on IPv6 Neighbor Discovery and Duplicate Address Detection o relaxed DHCP server deployment considerations allow DHCP servers within the MANET itself Changes from -01 to -02: o minor updates for consistency with recent developments Changes from -00 to -01: o new text on DHCPv6 prefix delegation and multilink subnet considerations. o various editorial changes Templin, et al. Expires May 17, 2008 [Page 18] Internet-Draft MANET Autoconfiguration November 2007 Authors' Addresses Fred L. Templin Boeing Phantom Works P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: fred.l.templin@boeing.com Steven W. Russert Boeing Phantom Works P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: steven.w.russert@boeing.com Seung Yi Boeing Phantom Works P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: seung.yi@boeing.com Templin, et al. Expires May 17, 2008 [Page 19] Internet-Draft MANET Autoconfiguration November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Templin, et al. Expires May 17, 2008 [Page 20]