Network Working Group F. Templin Internet-Draft S. Russert Intended status: Informational I. Chakeres Expires: August 24, 2007 S. Yi Boeing Phantom Works February 20, 2007 MANET Autoconfiguration draft-templin-autoconf-dhcp-06.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 August 24, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract Mobile Ad-hoc Networks (MANETs) consist of routers operating over multihop wireless links, and may or may not connect to other networks and/or the Internet. Routers in MANETs must have a way to automatically provision local and global-use IP addresses/prefixes. This document specifies mechanisms for MANET autoconfiguration. Both IPv4 and IPv6 are discussed. Templin, et al. Expires August 24, 2007 [Page 1] Internet-Draft MANET Autoconfiguration February 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. MANET Autoconfiguration . . . . . . . . . . . . . . . . . . . 5 3.1. MANET Router (MR) Operation . . . . . . . . . . . . . . . 5 3.2. MANET Border Router Operation . . . . . . . . . . . . . . 8 3.3. DHCP Server Extensions . . . . . . . . . . . . . . . . . . 9 3.4. MLA Encapsulation . . . . . . . . . . . . . . . . . . . . 9 3.5. MANET Flooding . . . . . . . . . . . . . . . . . . . . . . 10 3.6. Self-Generated Addresses . . . . . . . . . . . . . . . . . 10 3.7. Changes to the Neighbor Discovery Model . . . . . . . . . 10 4. Operation with Multiple MBRs . . . . . . . . . . . . . . . . . 10 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 11 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 9.1. Normative References . . . . . . . . . . . . . . . . . . . 11 9.2. Informative References . . . . . . . . . . . . . . . . . . 12 Appendix A. IPv6 Neighbor Discovery (ND) and Duplicate Address Detection (DAD) . . . . . . . . . . . . . . . 14 Appendix B. IPv6 StateLess Address AutoConfiguration (SLAAC) . . 14 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 Intellectual Property and Copyright Statements . . . . . . . . . . 17 Templin, et al. Expires August 24, 2007 [Page 2] Internet-Draft MANET Autoconfiguration February 2007 1. Introduction Mobile Ad-hoc Networks (MANETs) comprise links with asymmetric reachability characteristics (see: [RFC2461], Section 2.2) that connect MANET Routers (MRs). MRs participate in a routing protocol to discover routes for forwarding packets across the MANET using multiple Layer-2 and/or Layer-3 hops if necessary. MANETs may connect to other networks via MANET Border Routers (MBRs), and MRs may be multiple IP hops away from their nearest MBR in some scenarios. A MANET may be as large as an Autonomous System (AS) or as small as an individual site. A MANET may contain other MANETs and/or fixed networks, and a MANET may also be a smaller component of a larger site. MRs with hosts on downstream-attached links must have a means to automatically provision local and global-use IP addresses/ prefixes and/or other configuration information. Conceptually, MRs comprise a router entity and (one or more) host entity connected by a virtual point-to-point interface. The router entity also connects to an imaginary shared link (i.e., a "virtual ethernet") that connects all MRs in the MANET. An "enhanced" view of this virtual ethernet sees the MANET as a fully-connected shared link that connects all MRs, while an "unenhanced" view sees the MANET as a multilink site. For each MANET to which they connect, MRs discover a list of MBRs that determines the MANET's identity. An MR (and its downstream-attached links) is a "site" unto itself, and a MANET is therefore a "site-of-sites". MANETs that comprise homogeneous link types can configure the routing protocol to operate as a sub-IP layer mechanism such that IP (i.e., Layer-3) 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 configure the routing protocol to operate as a Layer-3 mechanism such that routing protocol operation is based on MANET-local Addresses (MLAs) or other identifiers that are unique within the MANET to avoid issues associated with bridging 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. This document specifies mechanisms and operational practices for MANET autoconfiguration. Operation using standard BOOTP/DHCP [RFC0951][RFC2131][RFC3315][RFC3633] and neighbor discovery [RFC0826][RFC1256][RFC2461][RFC2462] mechanisms is assumed unless otherwise specified. Both IPv4 [RFC0791] and IPv6 [RFC2460] are discussed. Templin, et al. Expires August 24, 2007 [Page 3] Internet-Draft MANET Autoconfiguration February 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: Mobile Ad-hoc Network (MANET) a connected network region that comprises MANET routers that maintain a routing structure among themselves in a relatively arbitrary fashion over links with asymmetric reachability characteristics (see: [RFC2461], Section 2.2). MANETs may be large as an Autonomous System (AS) or as small as an individual site, and may also be a smaller component of a larger site. A MANET router (and its downstream-attached links) is a "site" unto itself, and a MANET is therefore a "site-of-sites". Further information on the characteristics of MANETs can be found in [RFC2501]. MANET Interface a MANET router's attachment to a link in the MANET. virtual ethernet an imaginary shared link that connects all MRs in a MANET. MRs connect to this virtual ethernet via an interface configured over underlying MANET interface(s) that provides both enhanced and unenhanced "portals" (see: Figure 1 and Figure 2). The enhanced portal encapsulates packets in an outer IP header then sends them on an underlying MANET interface such that only a single Layer 3 hop is necessary to traverse the MANET, i.e., the enhanced portal views the MANET as a unified shared link. The unenhanced portal sends packets on an underlying MANET interface without further encapsulation such that multiple Layer 3 hops may be necessary to traverse the MANET, i.e., the unenhanced portal views the MANET as a multilink site. MANET Router (MR) a node that participates in a routing protocol over its MANET interface(s) and forwards packets on behalf of its downstream- attached nodes and other MRs. Conceptually, an MR comprises a router entity and (one or more) host entity connected via a virtual point-to-point interface, plus any other physical or virtual interfaces connected to the router entity. For the purpose of this specification, an MR's host entity configures a DHCP client and its router entity configures a DHCP relay. Templin, et al. Expires August 24, 2007 [Page 4] Internet-Draft MANET Autoconfiguration February 2007 MANET Border Router (MBR) an MR that connects the MANET to other networks. For the purpose of this specification, MBRs are assumed to configure a DHCP relay and/or a DHCP server. MANET Local Address (MLA) a Layer-3 unicast address configured by an MR that is unique within the MANET; it is used as an identifier for operating the routing protocol and also as a locator for packet forwarding within the scope of the MANET. For IPv6, Unique Local Addresses (ULAs) [RFC4193][I-D.jelger-autoconf-mla] provide a natural MLA mechanism. Extended Neighbor Discovery (END) message an IP Neighbor Discovery (ND) message [RFC1256] [RFC2461] transmitted on the unenhanced portal of the MR's virtual ethernet interface with an MLA of the underlying MANET interface as a source address and the 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. 3. MANET Autoconfiguration The following sections specify autoconfiguration mechanisms and operational practices that allow MRs to participate in the routing protocol and obtain addresses/prefixes for Intra-MANET and global Internet communications. 3.1. MANET Router (MR) Operation Each MR configures MLAs used for operating the routing protocol and/or for assignment on MANET interfaces. For IPv6 MANET interfaces, MLAs are generated using Unique Local Addresses [RFC4193][I-D.jelger-autoconf-mla] with interface identifiers that are either managed for uniqueness (e.g., per [RFC4291], Appendix A) or self-generated using a suitable random interface identifier generation mechanism that is compatible with EUI-64 format (e.g., Cryptographically Generated Addresses (CGAs) [RFC3972], IPv6 privacy addresses [I-D.ietf-ipv6-privacy-addrs-v2], etc.). For IPv4, MLAs are generated using a corresponding unique local address configuration mechanism. (Such a mechanism could be considered as a site-scoped equivalent to IPv4 link-local addresses [RFC3927].) The MR next engages in the routing protocol over its MANET interfaces and discovers the set of MBRs that identify the virtual ethernet associated with the MANET. The set of MBRs is discovered the same as for the ISATAP Potential Router List (PRL) initialization procedure Templin, et al. Expires August 24, 2007 [Page 5] Internet-Draft MANET Autoconfiguration February 2007 [RFC4214]; if the set of MBRs is NULL, an alternate token (such as the IEEE MAC address of an ordinary MR) can be used as an identifier for the MANET. For each MANET to which it attaches, the MR also configures a virtual ethernet interface over the underlying MANET interfaces connected to the MANET. The enhanced portal of the virtual ethernet interface presents an opaque view to IP, and configures a link-local address that is assured to be unique among the virtual interfaces of all MRs in the MANET. IP packets sent via the enhanced portal are encapsulated in an outer IP header then submitted to ip_output() for transmission on an underlying MANET interface. The unenhanced portal of the virtual ethernet interface presents a transparent view to IP, and provides direct access to the underlying MANET interfaces and their associated addresses. IP packets sent via the unenhanced portal are transmitted unencapsulated on an underlying MANET interface, but may include an IPv4 source routing header (likewise IPv6 routing header). Figure 1 shows the protocol stack model for the virtual ethernet output routine, and Figure 2 shows the corresponding model for the virtual ethernet input routine: +--------------------------------------------------+ | | ip_output() | | +--------------------------------------------------+ | | virtual_ethernet_output() | | | | | _ unenhanced portal __ __ enhanced portal ___ | p |/ \ / \| a | - MANET intf already | - select MANET intf | c | selected by ULP | - encapsulate in IP | k | - insert routing hdr | - send to MANET intf | e | (if necessary) | via ip_output() | t | - send directly to +-------------------------+ s | MANET intf | ip_output() | +--------------+---------+----+-...-+--------------+ | | MANET Intf 0 | MANET Intf 1 | ... | MANET Intf n | | | (MLA 0) | (MLA 1) | ... | (MLA n) | | +--------------+--------------+-...-+--------------+ v Figure 1: virtual_ethernet_output() Templin, et al. Expires August 24, 2007 [Page 6] Internet-Draft MANET Autoconfiguration February 2007 +--------------------------------------------------+ ^ | ip_input() | | +--------------------------------------------------+ | | virtual_ethernet_input() | | | p | _ unenhanced portal __ __ enhanced 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 2: virtual_ethernet_input() After the MR configures the virtual ethernet interface, it can confirm reachability of MBRs and (in the case of IPv6) discover prefixes associated with the MANET's virtual ethernet. It can confirm reachability by sending/receiving END messages over the unenhanced portal, by sending/receiving ordinary ND messages over the enhanced portal, via information conveyed in the routing protocol itself, or through some other means associated with the particular link technology. For IPv6, prefixes can also be discovered through an out-of-band service discovery protocol. After the MR discovers MBRs, it can configure addresses/prefixes according to either DHCP or IPv6 Stateless Address AutoConfiguration (SLAAC) (but see Appendix B for further considerations on SLAAC). When DHCP is used, the DHCP client associated with its host function forwards a DHCP DISCOVER (DHCPv4) or Solicit (DHCPv6) request to the DHCP relay associated with its router function to request global IP address and/or prefix delegations (see also: Section 3.6). The relay function then forwards the request to one or more MBRs, to other known DHCP servers, or to a site-scoped "All-DHCP-Servers" multicast address. For DHCPv4, the MR's relay function writes an address from the appropriate virtual ethernet interface portal in the 'giaddr' field and also includes the address in a DHCPv4 MLA option (see: Section 3.4). If necessary to identify the MR's downstream-attached host function, the relay also includes a link selection sub-option [RFC3527] with an address from the prefix associated with the virtual ethernet (if a prefix is available). For DHCPv6, the MR's relay function writes an address from the Templin, et al. Expires August 24, 2007 [Page 7] Internet-Draft MANET Autoconfiguration February 2007 appropriate virtual ethernet interface portal in the "peer-address" field and also writes an address from the prefix associated with the virtual ethernet in the "link-address" field (if a prefix is available). The MR can also use DHCP prefix delegation [RFC3633] to obtain prefixes for further sub-delegation to nodes on its downstream-attached links. The DHCP request will elicit a DHCP reply from a server with IP address/prefix delegations. When addresses are delegated, the MR assigns the resulting addresses to the virtual point-to-point interface that connects its host and router functions, i.e., the addresses are *not* assigned on the virtual ethernet interface or an underlying MANET interface. When prefixes are delegated, the MR can assign and/or further sub-delegate the prefixes to its downstream- attached links. If the MANET uses a proactive routing protocol, the MR can advertise the delegated addresses/prefixes into the routing protocol during the duration of the delegation lifetimes. The DHCP server ensures unique IP address/prefix delegations. By assigning global IP addresses/prefixes only on downstream-attached interfaces there is no requirement for the MR to perform Duplicate Address Detection (DAD) over its virtual ethernet or MANET interfaces. See Appendix A for further DAD considerations. After the MR configures global IP addresses/prefixes, it can send IP packets with global IP source addresses to on- and off-MANET destinations. Packets can be sent to off-MANET destinations either by using any available MBRs as egress gateways or by selecting specific MBRs on a per-packet basis. For MANETs in which MBRs can advertise a 'default' route that propagates throughout the routing protocol, the MR can send IP packets using the unenhanced virtual ethernet interface portal at the expense of extra TTL (IPv4) or Hop Limit (IPv6) decrementation. For MANETs in which the routing protocol cannot propagate a default route, or when the MR wishes to select a specific MBR as the egress gateway, the MR can ensure that the packets will be forwarded through a specific MBR by either 1) sending the packets via the enhanced portal with an MLA for an MBR as the destination address in the outer header, or 2) sending the packets via the unenhanced portal and inserting an IPv4 source routing header (likewise IPv6 routing header). 3.2. MANET Border Router Operation MBRs send END messages on the virtual ethernet unenhanced port and/or ordinary ND messages on the enhanced port. When stateful configuration is desired, prefixes advertised in RA messages should be advertised as not to be used for on-link determination or StateLess Address AutoConfiguration (SLAAC) [RFC2462] by setting the Templin, et al. Expires August 24, 2007 [Page 8] Internet-Draft MANET Autoconfiguration February 2007 'A', 'L' bits in Prefix Information Options to 0. (But, see: Appendix B for further considerations on using SLAAC for MANET Autoconfiguration.) MBRs act as BOOTP/DHCP relays and/or servers for a MR's DHCP requests/replies. For DHCPv4, when a MBR acting as a relay forwards a DHCP request that includes an MLA option, it writes its own address in the 'giaddr' field, i.e., it overwrites the value that was written into 'giaddr' by the MR's relay function. 3.3. DHCP Server Extensions No MANET autoconfiguration-specific extensions are required for DHCPv6 servers. DHCPv4 servers examine DHCPv4 requests for a DHCPv4 MLA option (see: Section 3.4). If a DHCPv4 MLA option is present, the DHCPv4 server copies the option into the corresponding DHCPv4 reply message(s). 3.4. MLA Encapsulation For DHCPv6, the MLA is encoded directly in the "peer-address" field of DHCPv6 requests/replies. For DHCPv4, a new DHCPv4 option [RFC2132] called the 'MLA option' is required to encode an MLA for DHCP transactions that will traverse a MBR, i.e., so that the MBR has a MANET-relevant address to direct DHCPv4 replies to the correct MR, which may be multiple Layer-3 hops away. The format of the DHCPv4 MLA option is given below: Code Len Ether Type MLA +-----+-----+-----+-----+-----+-----+--- | TBD | n | type | a1 | a2 | ... +-----+-----+-----+-----+-----+-----+--- Code a one-octet field that identifies the option type (see: Section 5). Len a one-octet field that encodes the remaining option length. Ether Type a type value from the IANA "ethernet-numbers" registry. Templin, et al. Expires August 24, 2007 [Page 9] Internet-Draft MANET Autoconfiguration February 2007 MLA a variable-length MANET Local Address (MLA). 3.5. MANET Flooding When multicast service discovery is required, Layer-3 MANETs that implement this specification must use a MANET flooding mechanism (e.g., Simplified Multicast Forwarding (SMF) [I-D.ietf-manet-smf]) so that site-scoped multicast messages can be propagated across multiple Layer-3 hops. 3.6. Self-Generated Addresses MR's can self-generate an address (e.g., an IPv6 CGA [RFC3972], an IPv6 privacy address [I-D.ietf-ipv6-privacy-addrs-v2], etc.) then propose the address to the DHCP server. If the DHCP server determines that the self-generated address is unique, it will delegate the address for the MR's use. 3.7. Changes to the Neighbor Discovery Model Ordinary link-scoped ND messages work as-normal over the virtual ethernet enhanced port, so ND operation over the enhanced port requires no changes to the standard IP neighbor discovery protocols specified in [RFC1256][RFC2461]. END messages over the virtual ethernet unenhanced port 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. Operation with Multiple MBRs For a set of MANETs and MBRs that attach to the same backbone network, MRs can retain their global IP address/prefix delegations as they move if the backbone network participates with the MBRs and MRs in a localized mobility management scheme, e.g., see: [I-D.templin-autoconf-netlmm-dhcp]. For a set of MBRs that attach to different backbone networks and/or serve different global IP prefixes from within the same network, MRs must configure new global IP addresses/prefixes as they change between different MBRs unless inter-MBR tunnels and routing protocol exchanges are supported, e.g., see: Templin, et al. Expires August 24, 2007 [Page 10] Internet-Draft MANET Autoconfiguration February 2007 [I-D.templin-autoconf-netlmm-dhcp], Appendix A. Global mobility management mechanisms for MRs that configure new global IP addresses/prefixes as they move between different MBRs are beyond the scope of this document. 5. IANA Considerations A new DHCP option code is requested for the DHCP MLA Option in the IANA "bootp-dhcp-parameters" registry. 6. Security Considerations Threats relating to MANET routing protocols also apply to this document. 7. Related Work Telcordia has proposed DHCP-related solutions for the CECOM MOSAIC program. The virtual ethernet model was proposed by Quang Nguyen under the guidance of Dr. Lixia Zhang. Various IETF AUTOCONF working group proposals have suggested similar mechanisms. 8. Acknowledgements The following individuals gave direct and/or indirect input that was essential to the work: Jari Arkko, Emmanuel Bacelli, James Bound, Thomas Clausen, Joe Macker, Thomas Henderson, Bob Hinden, 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. The Naval Research Lab (NRL) Information Technology Division uses DHCP in their MANET research testbeds. 9. References 9.1. Normative References [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981. [RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or Templin, et al. Expires August 24, 2007 [Page 11] Internet-Draft MANET Autoconfiguration February 2007 converting network protocol addresses to 48.bit Ethernet address for transmission on Ethernet hardware", STD 37, RFC 826, November 1982. [RFC0951] Croft, B. and J. Gilmore, "Bootstrap Protocol", RFC 951, September 1985. [RFC1256] Deering, S., "ICMP Router Discovery Messages", RFC 1256, September 1991. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [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. [RFC4214] Templin, F., Gleeson, T., Talwar, M., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 4214, October 2005. 9.2. Informative References [I-D.ietf-autoconf-manetarch] Chakeres, I., "Mobile Ad hoc Network Architecture", draft-ietf-autoconf-manetarch-00 (work in progress), February 2007. [I-D.ietf-ipv6-privacy-addrs-v2] Narten, T., "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", Templin, et al. Expires August 24, 2007 [Page 12] Internet-Draft MANET Autoconfiguration February 2007 draft-ietf-ipv6-privacy-addrs-v2-05 (work in progress), October 2006. [I-D.ietf-manet-smf] Macker, J., "Simplified Multicast Forwarding for MANET", draft-ietf-manet-smf-03 (work in progress), October 2006. [I-D.jelger-autoconf-mla] Jelger, C., "MANET Local IPv6 Addresses", draft-jelger-autoconf-mla-01 (work in progress), October 2006. [I-D.templin-autoconf-netlmm-dhcp] Templin, F., "Network Localized Mobility Management using DHCP", draft-templin-autoconf-netlmm-dhcp-04 (work in progress), October 2006. [I-D.thaler-autoconf-multisubnet-manets] Thaler, D., "Multi-Subnet MANETs", draft-thaler-autoconf-multisubnet-manets-00 (work in progress), February 2006. [I-D.thaler-intarea-multilink-subnet-issues] Thaler, D., "Issues With Protocols Proposing Multilink Subnets", draft-thaler-intarea-multilink-subnet-issues-00 (work in progress), March 2006. [RFC2501] Corson, M. and J. Macker, "Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations", RFC 2501, January 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. [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. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. Templin, et al. Expires August 24, 2007 [Page 13] Internet-Draft MANET Autoconfiguration February 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 for the purpose of uniquely identifying routers on the link. But, it is for further study as to whether MRs should even send RAs on MANET interfaces at all, since the unenhanced view of the MANET is as a multilink peering point between distinct sites and not a unified link. It is therefore also for further study as to whether MANET interfaces should configure link local addresses at all. 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 (remote) 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., but ULAs provide an additional 40/56 pseudo-random bits in the IPv6 address prefix. Statistical properties can assure uniqueness for the MLAs assigned on a MR's MANET interfaces, and careful operational practices can assure uniqueness for the global addresses/prefixes assigned on a MR's downstream-attached links (since the DHCP server assures unique assignments). However, a passive in-service DAD mechanism should still be used to detect duplicates that were assigned via 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. MRs that receive such messages could then self-generate an address from the prefix and assign it to the virtual point-to-point interface associated with the MANET's virtual ethernet, 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 routing exchanges occurring in other partitions and address duplication could result. Further study on DAD implications for SLAAC is required. Templin, et al. Expires August 24, 2007 [Page 14] Internet-Draft MANET Autoconfiguration February 2007 Appendix C. Change Log 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: 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 August 24, 2007 [Page 15] Internet-Draft MANET Autoconfiguration February 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 Ian D. Chakeres Boeing Phantom Works P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: ian.chakeres@gmail.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 August 24, 2007 [Page 16] Internet-Draft MANET Autoconfiguration February 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 August 24, 2007 [Page 17]