INTERNET-DRAFT Fred L. Templin SRI International 22 September 2000 An IPv6-IPv4 Compatibility Aggregatable Global Unicast Address Format for Incremental Deployment of IPv6 Nodes Within Predominantly IPv4-based Intranets Copyright Notice Placeholder for ISOC copyright. draft-templin-ngtrans-v6v4compat-01.txt Abstract This document specifies an IPv6-IPv4 compatibility aggregatable global unicast address format and its application for incremental IPv6 deployment for hosts and routers within predominantly IPv4-based Intranets. This document assumes that, during the IPv4 to IPv6 co- existence and transition phase, many sites will deploy IPv6 incrementally (not all at once) on hosts and routers within their pre-existing IPv4 interior routing domains; especially those sites which have large and complex pre-existing IPv4 infrastructures. In such cases, the address format and methods described in this document will enable IPv6 deployment for hosts and routers which do not share a common multiple access datalink with their default IPv6 gateways. While other works in progress in the NGTRANS working group propose mechanisms for assigning globally-unique IPv6 address prefixes to sites and methods for inter-domain routing between such sites, the approach outlined in this memo enables large-scale incremental deployment of IPv6 hosts and routers within an individual site's pre-existing IPv4 infrastructure without incurring aggregation scaling issues at the border gateways nor requiring site-wide deployment of special IPv4 services such as multicast. The approach proposed by this document supports IPv6 routing within both the site-local and global IPv6 routing domains as well as automatic IPv6 in IPv4 tunneling across portions of a site's IPv4 network which have no native IPv6 support. Moreover, this approach supports automatic tunneling within sites which use non globally-unique IPv4 address assignments, such as when Network Address Translation [NAT] is used. Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Templin Expires 22 March 2001 [Page 1] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 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. 1. Introduction The global Internet infrastructure is composed of communications entities (hosts and routers) that exchange messages using the Inter- net Protocol [IPV4]. The IPv4 architecture specifies a 32-bit address format; thus, the number of unique IPv4 addresses is limited to 2^32. (In practice, the actual number of unique addresses is considerably less due to other architectural constraints.) To eliminate the IPv4 address limitation issue, the IPNG working group of the Internet Engineering Task Force (IETF) has specified a next-generation Inter- net Protocol [IPV6] to succeed IPv4. The IPv6 protocol specifies a 128-bit address format [ADDR] which expand the number of uniquely addressable entities by staggering orders of magnitude over IPv4. IPv6 also includes numerous additional architectural improvements over IPv4, such as address autoconfiguration, neighbor discovery, and router discovery [AUTO][DISC]. But, the IPv4 protocol is so well understood and so deeply entrenched in the existing Internet infras- tructure that migration to IPv6 will require a transition period dur- ing which IPv6 will initially coexist with then gradually begin to supplant the existing IPv4 installed base. Due to these considerations, the IETF NGTRANS working group antici- pates an heterogeneous IPv4/IPv6 infrastructure for the near future and thus is chartered to develop methodologies to support IPv4/IPv6 coexistence and transition. For the most part, existing NGTRANS pro- posals focus on inter-domain routing between IPv6 "islands" using the existing global IPv4 backbone as transit. But, these islands may themselves consist of complex heterogeneous IPv4/IPv6 networks (e.g. large academic or commercial campus "intranets") that require intra- domain IPv4 to IPv6 transition mechanisms and strategies as well. In order to address this requirement, this document presents a simple Templin Expires 22 March 2001 [Page 2] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 and scalable approach that enables incremental intra-domain deploy- ment of IPv6 nodes within predominantly IPv4-based intranets. The approach outlined in this document is based on a new aggregatable global unicast address format that carries a standard 64-bit IPv6 address prefix [ADDR][AGGR] with a specially-constructed 64-bit EUI- 64 Interface Identifier [EUI64]. The 64-bit address prefix used by this format is fully compatible with all existing and emerging prefix assignment and inter-domain routing practices (e.g. [6to4],[6BONE]). But, the interface identifier employs a special construction using the IEEE Organizationally Unique Identifier (OUI) reserved by the Internet Assigned Numbers Authority [IANA] along with a "type" field to indicate that the identifier encapsulates an IPv4 address suitable for automatic intra-domain IPv6-in-IPv4 tunneling. As such, the embedded IPv4 address NEED NOT be globally unique; rather, it need only be topologically correct for (and unique within) the context of that site. This approach allows a dual-stack node that does not share a common multiple access datalink with an IPv6 gateway for its site to join the global IPv6 network by automatically tunneling IPv6 messages through the intra-site IPv4 routing infrastructure (*). This method further allows large-scale deployment of such nodes without incurring aggregation scaling issues at border gateways, since unique IPv4 addresses are embedded in the IPv6 address interface identifier while only a single IPv6 address prefix is used for the entire site. Finally, the method specified in this document supports intranets which use non-globally unique IPv4 addresses, such as when private address allocations [PRIVATE] and/or Network Address Translation [NAT] are used - even when multiple levels of NAT are used within a given site. (*) Since no router advertisements are available when a node does not share a common multiple access datalink with an IPv6 gateway, such a node requires two pieces of static configuration informa- tion: the 64-bit IPv6 network prefix for the site and the IPv4 address of a (dual-stack) IPv6 gateway servicing the site. Other- wise, no pre-configured tunnel state information is required. In the following sections, we present our proposed IPv6-IPv4 compati- bility address format in detail. We further discuss technical con- siderations for the application of IPv6-IPv4 compatibility addresses to facilitate incremental deployment of IPv6 within predominantly IPv4-based Intranets. Templin Expires 22 March 2001 [Page 3] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 2. IPv6-IPv4 Compatibility Address Format In sections 2.1 and 2.2, we will motivate our proposed extensions of the existing IEEE OUI reserved by IANA to support IEEE EUI-64 format addresses. While these proposed extensions are necessary to support our IPv6-IPv4 compatibility address format, they also provide a flex- ible framework for future IANA use. Therefore, we believe the exten- sions proposed in sections 2.1 and 2.2 may provide beneficial future use to the IANA beyond the scope of IPv6-IPv4 compatibility addresses. We present our IPv6-IPv4 compatibility address format pro- posal in sections 2.3 and 2.4. 2.1. IEEE EUI-64 Interface Identifiers in IPv6 Addresses IPv6 aggregatable global and local-use unicast addresses [ADDR] include a 64-bit interface identifier in IEEE EUI-64 format [EUI64], which is specified as the concatenation of a 24-bit company_id value (also known as the OUI) assigned by the IEEE Registration Authority (IEEE/RAC) and a 40-bit extension identifier assigned by the organi- zation owning that OUI. IEEE EUI-64 interface identifiers are for- matted as follows: |0 1|1 3|3 4|4 6| |0 5|6 1|2 7|8 3| +----------------+----------------+----------------+----------------+ |ccccccugcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm|mmmmmmmmmmmmmmmm| +----------------+----------------+----------------+----------------+ Where 'c' are the company-specific bits of the OUI, 'u' is the universal/local bit, 'g' is the individual/group bit and 'm' are the extension identifier bits. (NOTE: [ADDR] specifies that the 'u' bit is inverted from its normal sense in the IEEE context; therefore u=1 indicates global scope and u=0 indicates local scope). In order to support encapsulation of legacy IEEE EUI-48 (24-bit) extension identifier values, [EUI64] specifies that the first two octets of the EUI-64 40-bit extension identifier (bits 24 through 39 of the EUI-64 address itself) SHALL BE 0xFFFE if the extension iden- tifier encapsulates an EUI-48 value. [EUI64] further specifies that the first two octets of the extension identifier SHALL NOT be 0xFFFF, as this value is reserved by the IEEE/RAC. However, all other 40-bit extension identifier values are available for assignment by the addressing authority responsible for a given OUI. Templin Expires 22 March 2001 [Page 4] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 2.2. An EUI-64 Interface Identifier Format for IANA The IANA owns IEEE OUI: 0x00005E (also written as: 00-00-5E), and [IANA] specifies EUI-48 format (24-bit) interface identifier assign- ments within that OUI. But, [IANA] does not specify how these legacy EUI-48 assignments will be written in EUI-64 format, nor does it specify a format for future 40-bit extension identifier assignments. We propose the following format for EUI-64 addresses within IANA's OUI reservation: |0 2|2 3|3 3|4 6| |0 3|4 1|2 9|0 3| +------------------------+--------+--------+------------------------+ | OUI ("00-00-5E"+u+g) | TYPE | TSE | TSD | +------------------------+--------+--------+------------------------+ Where the fields are: OUI IANA's OUI: 00-00-5E with 'u' and 'g' bits (3 octets) TYPE Type field; indicates how (TSE, TSD) are interpreted (1 octet) TSE Type-Specific Extension (1 octet) TSD Type-Specific Data (3 octets) And the following interpretations are defined based on TYPE: TYPE (TSE, TSD) Interpretation ---- ------------------------- 0x00-0xFD RESERVED for future IANA use 0xFE (TSE, TSD) together contain an embedded IPv4 address 0xFF TSD is interpreted based on TSE as follows: TSE TSD Interpretation --- ------------------ 0x00-0xFD RESERVED for future IANA use 0xFE TSD contains 24-bit EUI-48 intf identif- ier 0xFF RESERVED by IEEE/RAC Essentially, if TYPE=0xFE, TSE is treated as an extension of TSD. If TYPE=0xFF, TSE is treated as an extension of TYPE. Other values for TYPE (and hence, other interpretations of TSE, TSD) are reserved for future IANA use. This format conforms to all requirements specified in [EUI64] and supports encapsulation of EUI-48 interface identifiers Templin Expires 22 March 2001 [Page 5] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 in the manner described by that document. For example, an existing IANA EUI-48 format multicast address such as: 01-00-5E-01-02-03 would be written in the IANA EUI-64 format as: 01-00-5E-FF-FE-01-02-03 But, this proposed format also provides a special TYPE (0xFE) for embedding IPv4 addresses within the IANA 40-bit extension identifier. This special TYPE forms the basis for our IPv6-IPv4 compatibility aggregatable global unicast address format proposal as described in the following sections. 2.3. IPv6-IPv4 Compatibility Address Construction Using the proposed IANA-specific method for interface identifier con- struction discussed in sections 2.1 and 2.2 (with TYPE=0xFE), and with reference to [ADDR], we can construct IPv6-IPv4 compatibility aggregatable global unicast addresses. Using this methodology, we propose an IPv6 address format with embedded IPv4 address in the EUI-64 interface identifier. The following diagram shows the con- struction: | 3| 13 | 8 | 24 | 16 | 8 | 8 | 8 | 8 | 32 bits | +--+-----+---+--------+--------+---+---+---+---+---+---+---+----+ |FP| TLA |RES| NLA | SLA | 0x| 0x| 0x| 0x| IPv4 Address | | | ID | | ID | ID | 02| 00| 5E| FE| of Endpoint | +--+-----+---+--------+--------+--------------------------------+ (NOTE: the least significant octet of the OUI in the interface iden- tifier is 0x02 instead of 0x00 since u=1 for global scope.) By way of example, an existing node with IPv4 address 140.173.129.8 might be assigned an IPv6 64-bit prefix of 3FFE:1a05:510:200::/64. We can then construct an IPv6-IPv4 compatibility aggregatable global unicast address for this node as: 3FFE:1a05:510:200:0200:5EFE:8CAD:8108 or (perhaps more appropriately) written as the alternative form for an IPv6 address with embedded IPv4 address found in [ADDR]: 3FFE:1a05:510:200:0200:5EFE:140.173.129.8 Similarly, we can construct the link-local and site-local variants Templin Expires 22 March 2001 [Page 6] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 (respectively) of the IPv6-IPv4 compatibility address as: FE80::0200:5EFE:140.173.129.8 FEC0::200:0200:5EFE:140.173.129.8 2.4. Advantages By embedding an IPv4 address in the interface identifier portion of an IPv6 address as described in section 2.3, we can construct aggre- gatable global unicast IPv6 addresses that can either be routed glo- bally via the IPv6 infrastructure or automatically tunneled locally across portions of a site's IPv4 infrastructure which have no native IPv6 routing support. Thus the addressing scheme would support heterogeneous IPv6/IPv4 infrastructures in transition with incremen- tal deployment of IPv6 at the site level. Additionally, a node with such an IPv6-IPv4 compatibility address could act as a router for nodes with native IPv6 addresses connected to the same link, since it could automatically tunnel messages across a site's IPv4 domain to reach a border IPv6 gateway for the site on behalf of such native IPv6 nodes. An example would be deployment of IPv6 on some subset of the hosts attached to a workgroup's Ethernet LAN. In this case, one host would receive an IPv6-IPv4 compatibility address and act as a router for the other hosts which receive native IPv6 addresses. An additional advantage for our proposed method of embedding an IPv4 address in the interface identifier portion of an IPv6 address not found in other approaches such as [6TO4] is that large numbers of IPv6-IPv4 compatibility addresses could be assigned within a common IPv6 routing prefix, thus providing maximal aggregation at the border gateways. For example, the single 64-bit IPv6 prefix: 3FFE:1a05:510:2412::/64 could include literally millions of nodes with IPv6-IPv4 compatibil- ity addresses. This feature would allow a "sparse mode" IPv6 deploy- ment such as the deployment of sparse populations of IPv6 hosts on large numbers of independent links throughout a large corporate Intranet. A final important advantage is that this method supports both sites that use globally unique IPv4 address assignments and those that use non-globally unique IPv4 addresses, such as when private address assignments and/or Network Address Translation are used. By way of analogy to the US Postal system, inter-domain transition approaches such as [6TO4] provide means for routing messages "cross-country" to the "street address" of a distant site while the approach outlined in this document provides localized routing information to reach a Templin Expires 22 March 2001 [Page 7] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 specific (mailstop, apartment number, post office box, etc) WITHIN that site. Thus, the site-level routing information need not have relevance outside the scope of that site. 3. Deployment Considerations IPv6-IPv4 compatibility addresses should only be used by hosts or routers which do not share a common multiple access datalink with an IPv6 router for their site. But, there are numerous cases in which this situation may occur within an heterogeneous IPv6/IPv4 Intranet. Two such examples are: - A researcher wishes to configure IPv6 on his existing IPv4-based workstation, but the network administrators for his site have not yet configured an IPv6 router for his workstation's LAN. The researcher is aware of a dual-stack IPv6 router elsewhere within his site (which may be several IPv4 router hops away from his workstation's LAN) and sets the 64-bit IPv6 address prefix and IPv4 address of the router as configuration information on his worksta- tion (**). The researcher's workstation can now access the global IPv6 Internet by first tunneling messages through the site-local IPv4 routing domain to the IPv6 router, which will in turn route the IPv6 messages. No static configuration information is needed on the IPv6 router on behalf of the researcher's workstation. (**) This configuration information is used to construct TWO IPv6-IPv4 compatibility addresses: the concatenation of the IPv6 prefix and the IPv4 address of the router construct the IPv6-IPv4 compatibility address for the router, which the researcher's workstation uses as its default IPv6 gateway address. The con- catenation of the IPv6 prefix and the IPv4 address of the researcher's workstation construct the IPv6-IPv4 compatibility address which the workstation uses as its own IPv6 source address. - An network administrative authority wishes to configure IPv6 on the existing IPv4 subnets under their jurisdiction, but these sub- nets are separated from the IPv6 border gateway for the site by other IPv4 subnets which are not ready for IPv6 deployment. The administrator configures a dual-stack IPv6 router (or routers) for his administrative domain by arranging for SLA-based subnet allocation(s) from the owner of the IPv6 border gateway for the site. The administrator further sets the 64-bit IPv6 address prefix and IPv4 address of the border gateway as configuration information on his router. The router(s) for the administrative domain can now access the global IPv6 Internet by first tunneling messages through the site-local IPv4 routing domain to the IPv6 border gateway for Templin Expires 22 March 2001 [Page 8] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 the site. Hosts and/or other IPv6 routers which share a common mul- tiple access datalink with the router receive router advertisements from which they can construct native IPv6 addresses with topologically-correct 64-bit prefixes and interface identifiers via address autoconfiguration. The IPv6 border gateway for the site need only have routing information which points to the router(s) for the SLA-based subnet allocations. As seen in the above examples, the IPv6-IPv4 compatibility address format enables incremental IPv6 deployment for hosts and routers within sites which have incomplete (or, "sparse") IPv6 coverage at the network infrastructure level. But, as native IPv6 services become more widely deployed throughout the site, IPv6-IPv4 compatibility addresses will begin to outlive their usefulness. In fact, the fol- lowing simple and automatic deprecation rule for hosts and routers using IPv6-IPv4 compatible addresses is possible: "While no IPv6 router advertisements are received, continue to use the IPv6-IPv4 compatibility address. If router advertisements ensue, discontinue use of the IPv6-IPv4 compatibility address and construct a native IPv6 address based on prefix information carried in the router advertisements." See section 6 for more details on automatic deprecation of IPv6-IPv4 compatibility addresses. 4. Sending Rules and Routing Considerations The sending rule for a host or router that sends an IPv6 packet to an IPv6-IPv4 compatibility destination address is simple and direct: "If the 64-bit IPv6 prefix of the IPv6-IPv4 compatibility destina- tion address matches the 64-bit IPv6 prefix of one of my network interfaces, tunnel the packet through IPv4 - else, route the packet through IPv6." From the above rule, a sender that does NOT have an interface which shares a common 64-bit routing prefix with the packet's IPv6-IPv4 compatibility destination address simply sends the packet to the next-hop gateway determined by an ordinary IPv6 routing table lookup. In short, when a sending node does not have an interface which shares a common 64-bit (site-level) routing prefix with an IPv6-IPv4 compa- tibility destination address, the sending rule is identical to that for a native IPv6 destination address. This decision is independent of whether the sender has an IPv6-IPv4 compatibility address itself, or whether the sender even comprises a dual-stack configuration. Indeed, the sender can simply be a native IPv6 node with no legacy Templin Expires 22 March 2001 [Page 9] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 IPv4 support. When a sender has an interface which shares a common 64-bit routing prefix with an IPv6-IPv4 compatibility destination address, however, the sender must assume that the destination is NOT directly reachable at the datalink level - even though the shared site-level routing prefix implies otherwise. Instead, if the sender comprises a dual- stack configuration, it should automatically tunnel the IPv6 packet (via IPv6-in-IPv4 tunneling as described in [MECH]) to the IPv4 address embedded within the IPv6-IPv4 compatibility destination address' interface identifier. If the sender is an IPv6-only node that DOES NOT comprise a dual-stack configuration, however, it has no means for automatically tunneling the packet via IPv4. In this case: - If the sender is the host that originates the packet, it should send the packet to a router that lists the 64-bit prefix in its router advertisements. If no such router exists, the sender should drop the packet and return a "No route to host" error indication to the ori- ginating application. - If the sender is a router that forwards the packet, it should drop the packet and send an ICMPv6 "Destination Unreachable" message to the source By implication, the scheme breaks down if a packet with an IPv6-IPv4 compatibility destination address reaches an IPv6-only router that has an interface which shares a common 64-bit routing prefix with the desti- nation address. Additional mechanisms to address this issue might be possible, such as allowing dual-stack routers to advertise 96-bit pre- fixes which incorporate the special 32-bit EUI-64 interface identifier prefix: 0200:5EFE. A sender could then interpret such an advertisement to mean that the advertising router comprises a dual stack and is capa- ble of intra-site IPv6-in-IPv4 tunneling. But a reasonable argument could be made to the effect that: "By the time IPv6-only routers begin to proliferate throughout a site, nodes within the site should no longer be using IPv6-IPv4 compatibil- ity addresses." In fact, the advent of IPv6-only routers within a site would serve as a strong indication that the site is no longer a predominantly IPv4-based infrastructure in transition, but rather that the transition is either complete or nearly complete. Therefore, IPv6-IPv4 compatibility addresses should no longer be used. Templin Expires 22 March 2001 [Page 10] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 5. Address Selection Other works in progress ([6TO4] and [SELECT]) have begun to explore the subject of address selection when multiple IPv6 destination address alternatives are available. These address selection policies deal with the 64-bit IPv6 routing prefix and thus can be applied independently of whether/not the destination address alternatives are constructed as described in this document. However, in order to ensure efficient routing within the destination's site, we propose the following simple "second-tier" address selection policy for deal- ing with IPv6-IPv4 compatibility addresses: "If multiple alternatives remain after address selection has been applied on the 64-bit routing prefixes, and if at least one of the remaining alternatives is constructed with a native IPv6 interface identifier (one that does NOT contain an embedded IPv4 address as described in this document), select a native IPv6 address. Other- wise, select an IPv6-IPv4 compatible address." This policy decision is in keeping with the concept that NGTRANS transition mechanisms should remain in place ONLY as long as needed and should be disabled as soon as native IPv6 mechanisms become available. 6. Automatic Deprecation IPv6-IPv4 compatibility addresses constructed in the manner described in this document are intended for use only by nodes which do not receive router advertisements due to not sharing a common multiple access datalink with an IPv6 router. When router advertisements become available (such as when an IPv6 router is deployed on a common multiple access datalink shared by the node), the node should discon- tinue use of its IPv6-IPv4 compatibility address and adopt a normal aggregatable global IPv4 unicast address using address auto- configuration [AUTO] for a prefix discovered through normal router discovery [DISC] means. In this way, IPv6-IPv4 compatibility addresses will gradually (and automatically) disappear as IPv6 routers become widely deployed within a site. 7. Multicast Considerations Other works in progress are currently investigating IPv4-mapped mul- ticast addressing issues. The address format discussed in this docu- ment is expected to be compatible with those emerging approaches. Templin Expires 22 March 2001 [Page 11] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 8. Relation to other works in progress The IPv6-IPv4 compatibility address format and routing policy deci- sions presented in this draft evolved from SRI contractual works out- side the scope of the NGTRANS working group. Additionally, the mechanisms presented in this draft were developed by the author with no prior knowledge of the activities in NGTRANS. The author recog- nizes that other works in progress seek to address very similar IPv4-IPv6 transition issues as those targeted by this draft. However, the approach described in this draft presents a number of unique advantages for NGTRANS that supplement the other works in progress. (Most specifically, advantages for incremental deployment of IPv6 nodes at the intra-domain level.) 9. IANA considerations In order support the EUI-64 address form described in this document, we propose that IANA adopt the EUI-64 Interface Identifier format specified in section 2.2 for the existing 00-00-5E OUI owned by IANA. No other actions are required by the IANA. 10. Security considerations If the administrative authority for a wishes to enforce a policy of not exposing internal IPv4 addresses outside of the site, the site's router could perform a sort of "reverse network address translation" to transform the IPv6-IPv4 compatibility address interface identifier (with embedded IPv4 address) into an anonymous ID for inter-domain routing outside the site. The fully-qualified IPv6-IPv4 compatibility address interface identifier must be used inside the site to enable automatic IPv6-in-IPv4 tunneling, however. Additional security issues are called out in [6TO4] and probably apply here as well. 11. Implementation status The author has implemented the mechanisms described in this draft through modifications to the FreeBSD 3.2-RELEASE [FBSD] operating system with the INRIA [INRIA] IPv6 distribution. These modifications implement the sending rules and routing considerations as described in section 3. The source code is not yet ready for public distribu- tion, but the author would be happy to discuss details with interested parties. Templin Expires 22 March 2001 [Page 12] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 Acknowledgements The ideas presented here were derived from SRI contractual work in which the author developed these new mechanisms based on principles which emerged through ad-hoc extensions to the FreeBSD 3.2-RELEASE operating system and INRIA IPv6 implementation. The author recognizes that ideas similar to those presented in this document may have already been presented by other authors in NGTRANS (or other forums) and wishes to acknowledge any other such authors. The author also wishes to acknowledge the SRI and government contract administrators who sponsored the projects from which these works derived. The author additionally wishes to specifically acknowledge SRI colleagues with whom he has discussed and reviewed this work, including Dr. Mike Frankel, J. Peter Marcotullio, Lou Rodriguez, and Dr. Ambatipudi Sas- try. The author further acknowledges discussions with Alain Durand and Keith Moore during the IETF 48 conference in Pittsburgh, PA. which helped motivate ideas on restructuring this document from the first version. References [AGGR] Hinden., R, O'Dell, M., and Deering, S., "An IPv6 Aggregatable Global Unicast Address Format", RFC 2374, July 1998. [ADDR] Hinden, R., and S. Deering, "IP Version 6 Addressing Architecture", RFC 2373, July 1998. [AUTO] Thomson, S., and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998. [DISC] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [EUI64] IEEE, "Guidelines for 64-bit Global Identifier (EUI-64) Registration Authority", http://standards.ieee.org/regauth/oui/tutorials/EUI64.html, March 1997 [IANA] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, USC/Information Sciences Institute, October 1994. [IPV4] Postel, J., "Internet Protocol", RFC 791 [IPV6] Deering, S., and R. Hinden, "Internet Protocol, Version 6 Templin Expires 22 March 2001 [Page 13] INTERNET-DRAFT IPv6-IPv4 Unicast Address Format 22 September 2000 (IPv6) Specification", RFC 2460 [6TO4] Carpenter, B., and K. Moore, "Connection of IPv6 Domains via IPv4 Clouds without Explicit Tunnels", draft-ietf-ngtrans-6to4-04.txt (work in progress). [MECH] Gilligan, R., and E. Nordmark, "Transition Mechanisms for IPv6 Hosts and Routers", draft-ietf-ngtrans-mech-04.txt (work in progress). [SELECT] Draves, R., Default Address Selection for IPv6, draft- ietf- ipngwg-default-addr-select-00.txt (work in progress) [FBSD] http://www.freebsd.org [INRIA] ftp://ftp.inria.fr/network/ipv6/ [6BONE] Rockell, R., and R. Fink, RFC 2772, February 2000. [PRIVATE] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. J., and E. Lear, "Address Allocation for Private Internets", RFC 1918, February 1996. [NAT] Egevang, K., and P. Francis, "The IP Network Address Translator (NAT)", RFC 1631, May 1994. Authors Addresses Fred L. Templin SRI International 333 Ravenswood Ave. Menlo Park, CA 94025, USA Email: templin@erg.sri.com Intellectual Property PLACEHOLDER for full IETF IPR Statement if needed. Full Copyright Statement PLACEHOLDER for full ISOC copyright Statement if needed. Templin Expires 22 March 2001 [Page 14]