Network Working Group F. Templin Internet-Draft S. Russert Intended status: Informational S. Yi Expires: August 7, 2008 Boeing Phantom Works February 4, 2008 MANET Autoconfiguration draft-templin-autoconf-dhcp-11.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 7, 2008. Copyright Notice Copyright (C) The IETF Trust (2008). 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 August 7, 2008 [Page 1] Internet-Draft MANET Autoconfiguration February 2008 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 . . . . . . . . . . . . . 7 3.1.4. Reachability Confirmation . . . . . . . . . . . . . . 7 3.1.5. MNBR-Aggregated Address/Prefix Autoconfiguration . . . 8 3.1.6. Nomadic IPv6 Prefixes . . . . . . . . . . . . . . . . 9 3.1.7. Self-Generated IPv6 Interface Identifiers . . . . . . 9 3.1.8. Forwarding Packets to Off-MANET Destinations . . . . . 10 3.2. MANET Border Router (MNBR) Operation . . . . . . . . . . . 10 3.3. MANET Flooding . . . . . . . . . . . . . . . . . . . . . . 10 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 11 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 9.1. Normative References . . . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . . 13 Appendix A. Duplicate Address Detection (DAD) Considerations . . 14 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 Intellectual Property and Copyright Statements . . . . . . . . . . 18 Templin, et al. Expires August 7, 2008 [Page 2] Internet-Draft MANET Autoconfiguration February 2008 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 be as simple as a small collection of MNRs (and their attached networks); a MANET may also contain other MANETs and/or 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 without IP layer encapsulation. 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 specialized autoconfiguration procedures are necessary to avoid multilink subnet issues [RFC4903]. In particular, we describe herein the use of a virtualized link that spans the MANET, to avoid the multilink subnet issues that arise when MANET interfaces are used directly by applications. 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) that sees the MANET as a fully- connected shared link. 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 August 7, 2008 [Page 3] Internet-Draft MANET Autoconfiguration February 2008 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). Note that in some MANET scenarios, an interface may dynamically switch from being an ingress interface to being an egress interface, and vice-versa. 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 be as simple as a small collection of MNRs (and their attached networks); a MANET may also contain other MANETs and/or 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. 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 other networks, including the Internet. MNBRs that configure egress interfaces can delegate 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 August 7, 2008 [Page 4] Internet-Draft MANET Autoconfiguration February 2008 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. The VET interface encapsulates each IP packet in an outer IP header then forwards it over 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 VET interface views the MANET as a unified shared link and presents an automatic tunneling abstraction. The following figure depicts the architectural model for a MANET router: 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 attached networks) Figure 1: MANET Router Templin, et al. Expires August 7, 2008 [Page 5] Internet-Draft MANET Autoconfiguration February 2008 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 networks, and both MANET and VET interfaces that are "neutral" in the sense that the packets they forward may need to traverse several MANET hops before they are forwarded via either an egress or ingress interface. MNRs also engage in the routing protocol over their MANET interfaces, and 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 assignment to MANET interfaces. IPv4 MLAs can be manually configured, administratively assigned, autoconfigured using DHCP or self-generated using a suitable pseudo- random IPv4 unique local address autoconfiguration mechanism. Such a mechanism could be considered as a site-scoped equivalent to IPv4 link-local addresses [RFC3927], and could delegate addresses out of a suitably large IPv4 prefix space such as the soon-to-be-reclassified 240/4 space [I-D.fuller-240space]. 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.). When there is no manually/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. Since a MNR initially has no non-link-local addresses, DHCP Templin, et al. Expires August 7, 2008 [Page 6] Internet-Draft MANET Autoconfiguration February 2008 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 routing protocol information, or through an alternate discovery mechanism, e.g., per [RFC4214], Section 8.3.2. Identifying names/values for one or more MNBRs, and/or a set of address prefixes that they aggregate, serve as an identifier for the MANET. 3.1.3. VET Interface Configuration The MNR configures a VET interface over a set of underlying MANET interfaces that represents a unified shared link for the MANET. The VET interface autoconfigures a link-local address, e.g., an ISATAP link-local address ([RFC4214], Section 6.2) derived from an IPv4 MLA assigned to an underlying MANET interface, an IPv4 link local address[RFC3927], etc.. IP packets sent via the VET interface are encapsulated in an outer IP header then submitted to the IP forwarding engine for transmission on an underlying MANET interface. Considerations for setting the VET interface Maximum Transmission Unit (MTU) are discussed in [RFC4213]. 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 ordinary ND messages and/or issuing DHCP requests over the VET interface. It can also confirm reachability through information conveyed in the routing protocol itself, or through some other means associated with the particular MANET subnetwork technology. Out of scope for this document are specific mitigations for the loss of MNRs/MNBRs due to e.g., network partitions, node failures, etc. Mechanisms such as routing protocol information, bidirectional forward detection, detection of network attachment, neighbor discovery hints of forward progress, short beaconing/polling intervals, etc. are candidates for further study. Templin, et al. Expires August 7, 2008 [Page 7] Internet-Draft MANET Autoconfiguration February 2008 3.1.5. MNBR-Aggregated Address/Prefix Autoconfiguration After the MNR discovers MNBRs, it can acquire MNBR-aggregated addresses/prefixes using either IPv6 Stateless Address AutoConfiguration (SLAAC) or DHCP. 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 o other non-link-local scope The following subsections discuss IPv6 SLAAC and DHCP address/prefix autoconfiguration considerations: 3.1.5.1. IPv6 SLAAC For IPv6, MNRs can autoconfigure addresses on the VET interface based on Prefix Information Options in received RAs, i.e., the same as for ordinary IPv6 links (see: Section 3.2). 3.1.5.2. DHCP Address/Prefix Autoconfiguration 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 for assignment on ingress interfaces (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.) Templin, et al. Expires August 7, 2008 [Page 8] Internet-Draft MANET Autoconfiguration February 2008 For DHCPv4, the MNR's relay function writes an address from a MANET 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. 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 and VET interfaces (but see Appendix A for further DAD considerations). 3.1.6. Nomadic IPv6 Prefixes 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. Similarly, a MNR can carry IPv6 prefixes (e.g., taken from a home network) as it travels between MANETs as long it coordinates in some fashion with a prefix aggregation authority. Such nomadic-use IPv6 prefixes are not aggregated, redistributed or advertised by MNBRs and can therefore travel with the MNR as it moves to new MANETs and/or configures peering arrangements with MNRs in other MANETs. Generation of nomadic IPv6 prefixes 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. Templin, et al. Expires August 7, 2008 [Page 9] Internet-Draft MANET Autoconfiguration February 2008 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 MNRs use the VET interface to 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 to elicit Router Advertisements from MNBRs. MNRs/MNBRs should therefore include default router preferences and/or more-specific routes in their Router Advertisements. Once default routers and/or more-specific routes are discovered, the MNR can forward the packets via the VET interface with an MLA for an MNR/MNBR as the destination in the outer IP header. When multiple MNR/MNBRs are available as next-hop routers on the VET interface, the MNR can use default router preferences, traffic engineering configurations, etc. to select the best exit router. 3.2. MANET Border Router (MNBR) Operation MNBRs connect networks on ingress interfaces to the MANET, and may also connect the MANET to other networks that lead toward the Internet over egress interfaces. This latter category of MNBRs can also delegate addresses/prefixes to other MNRs on the MANET. MNBRs send ordinary ND messages such as IPv6 RA messages with Route Information Options [RFC4191] to other MNRs over the VET interface. MNBRs that delegate addresses/prefixes for the MANET can also include link specific parameters, default router lifetimes, default router preferences, and Prefix Information Options for SLAAC on the VET interface in the IPv6 RA messages they send. For DHCPv6, MNBRs that delegate addresses/prefixes act as DHCP relays and/or servers for 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. Templin, et al. Expires August 7, 2008 [Page 10] Internet-Draft MANET Autoconfiguration February 2008 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). 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 investigated 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 Templin, et al. Expires August 7, 2008 [Page 11] Internet-Draft MANET Autoconfiguration February 2008 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. [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. [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms for IPv6 Hosts and Routers", RFC 4213, October 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. Templin, et al. Expires August 7, 2008 [Page 12] Internet-Draft MANET Autoconfiguration February 2008 9.2. Informative References [I-D.fuller-240space] Fuller, V., "Reclassifying 240/4 as usable unicast address space", draft-fuller-240space-00 (work in progress), September 2007. [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-06 (work in progress), November 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. [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. and S. Team, "Simplified Multicast Forwarding for MANET", draft-ietf-manet-smf-06 (work in progress), November 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., Templin, et al. Expires August 7, 2008 [Page 13] Internet-Draft MANET Autoconfiguration February 2008 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. Duplicate Address Detection (DAD) Considerations 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 IPv6 MLAs 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). Pseudo-random IPv4 MLAs can be generated through random assignment from a suitably large IPv4 prefix space, e.g., the soon-to-be-reclassified 240/4 space [I-D.fuller-240space]. 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. Templin, et al. Expires August 7, 2008 [Page 14] Internet-Draft MANET Autoconfiguration February 2008 Appendix B. Change Log (Note to RFC editor - this section to be removed before publication as an RFC.) Changes from -10 to 11: o removed the transparent/opaque VET portal abstractions. o removed routing header as an option for MANET exit router selection. o included IPv6 SLAAC as an endorsed address configuration mechanism for the VET interface. 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: Templin, et al. Expires August 7, 2008 [Page 15] Internet-Draft MANET Autoconfiguration February 2008 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: 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: Templin, et al. Expires August 7, 2008 [Page 16] Internet-Draft MANET Autoconfiguration February 2008 o new text on DHCPv6 prefix delegation and multilink subnet considerations. o various editorial changes Authors' Addresses Fred L. Templin Boeing Phantom Works P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: fltemplin@acm.org 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 August 7, 2008 [Page 17] Internet-Draft MANET Autoconfiguration February 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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 7, 2008 [Page 18]