Network Working Group F. Templin, Ed. Internet-Draft Boeing Phantom Works Intended status: Informational December 5, 2008 Expires: June 8, 2009 Virtual Enterprise Traversal (VET) draft-templin-autoconf-dhcp-22.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 June 8, 2009. Abstract Enterprise networks connect routers over various link types, and may also connect to provider networks and/or the global Internet. Nodes in enterprise networks must have a way to automatically provision IP addresses/prefixes and other information, and must also support post- autoconfiguration operations even for highly-dynamic networks. This document specifies a Virtual Enterprise Traversal (VET) abstraction for autoconfiguration and operation of nodes in enterprise networks. Templin Expires June 8, 2009 [Page 1] Internet-Draft VET December 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Enterprise Characteristics . . . . . . . . . . . . . . . . . . 7 4. Autoconfiguration . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Enterprise Interior Router (EIR) Autoconfiguration . . . . 9 4.2. Enterprise Border Router (EBR) Autoconfiguration . . . . . 10 4.2.1. VET Interface Autoconfiguration . . . . . . . . . . . 10 4.2.2. Inner IP Address/Prefix Delegation and Maintenance . . 12 4.2.3. Portable Inner IP Addresses/Prefixes . . . . . . . . . 12 4.2.4. Enterprise-edge Interface Autoconfiguration . . . . . 13 4.3. Enterprise Border Gateway (EBG) Autoconfiguration . . . . 13 4.4. VET Host Autoconfiguration . . . . . . . . . . . . . . . . 13 5. Post-Autoconfiguration Operation . . . . . . . . . . . . . . . 14 5.1. Routing Protocol Participation . . . . . . . . . . . . . . 14 5.2. DHCP Prefix Delegation Maintenance . . . . . . . . . . . . 14 5.3. IPv6 Prefix Mapping . . . . . . . . . . . . . . . . . . . 15 5.4. IPv6 EBR/EBG Router Discovery . . . . . . . . . . . . . . 15 5.5. Forwarding Packets to Destinations Outside of the Enterprise . . . . . . . . . . . . . . . . . . . . . . . . 16 5.6. Source Address Verification . . . . . . . . . . . . . . . 17 5.7. Enterprise-Local Communications . . . . . . . . . . . . . 17 5.8. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 17 5.9. Service Discovery . . . . . . . . . . . . . . . . . . . . 18 6. Enterprise Partitioning . . . . . . . . . . . . . . . . . . . 18 7. Securing VET with SEAL . . . . . . . . . . . . . . . . . . . . 18 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 9. Security Considerations . . . . . . . . . . . . . . . . . . . 19 10. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 20 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 20 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 13.1. Normative References . . . . . . . . . . . . . . . . . . . 21 13.2. Informative References . . . . . . . . . . . . . . . . . . 22 Appendix A. Duplicate Address Detection (DAD) Considerations . . 24 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 25 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 28 Intellectual Property and Copyright Statements . . . . . . . . . . 29 Templin Expires June 8, 2009 [Page 2] Internet-Draft VET December 2008 1. Introduction Enterprise networks [RFC4852] connect routers over various link types (see: [RFC4861], Section 2.2). Certain Mobile Ad-hoc Networks (MANETs) [RFC2501] can be considered as a challenging example of an enterprise network, in that their topologies may change dynamically over time and that they may employ little/no active management by a centralized network administrative authority. These specialized characteristics for MANETs require careful consideration, but the same principles apply equally to other enterprise network scenarios. This document specifies a Virtual Enterprise Traversal (VET) abstraction for autoconfiguration and runtime operation of nodes in enterprises, where addresses of different scopes may be assigned on various types of interfaces with diverse properties. Both IPv4 [RFC0791] and IPv6 [RFC2460] are discussed within this context. The use of standard DHCP [RFC2131][RFC3315] and neighbor discovery [RFC0826][RFC4861] mechanisms is assumed unless otherwise specified. Provider-edge Interfaces x x x | | | +--------------------+---+--------+----------+ E | | | | | n | I | | .... | | t | n +---+---+--------+---+ | e | t | +--------+ /| | r | e I x----+ | Host | I /*+------+--< p I | r n | |Function| n|**| | r n | n t | +--------+ t|**| | i t | a e x----+ V e|**+------+--< s e | l r . | E r|**| . | e r | f . | T f|**| . | f | V a . | +--------+ a|**| . | I a | i c . | | Router | c|**| . | n c | r e x----+ |Function| e \*+------+--< t e | t s | +--------+ \| | e s | u +---+---+--------+---+ | r | a | | .... | | i | l | | | | o +--------------------+---+--------+----------+ r | | | x x x Enterprise-edge Interfaces Figure 1: Enterprise Router Architecture Figure 1 above depicts the architectural model for an enterprise Templin Expires June 8, 2009 [Page 3] Internet-Draft VET December 2008 router. As shown in the figure, an enterprise router may have a variety of interface types including enterprise-edge, enterprise- interior, provider-edge, internal-virtual, as well as VET interfaces used for encapsulation of inner IP packets within outer IP headers. The different types of interfaces are defined, and the autoconfiguration mechanisms used for each type are specified. This architecture applies equally for MANET routers, in which enterprise- interior interfaces correspond to the wireless multihop radio interfaces typically associated with MANETs. Out of scope for this document is the autoconfiguration of provider interfaces, which must be coordinated in a manner specific to the service provider's network. The VET specification represents a functional superset of 6over4 [RFC2529] and ISATAP [RFC5214], and further supports additional encapsulations such as IPsec [RFC4301], SEAL [I-D.templin-seal], etc. As a result, VET provides a map-and-encaps architecture using IP-in-IP tunneling based on both forwarding table and mapping service lookups (defined herein). The VET principles can be either directly or indirectly traced to the deliberations of the ROAD group in January 1992, and also to still earlier works including NIMROD [RFC1753], the Catenet model for internetworking [CATENET][IEN48][RFC2775], etc. [RFC1955] captures the high-level architectural aspects of the ROAD group deliberations in a "New Scheme for Internet Routing and Addressing [ENCAPS] for IPNG". VET is related to the present-day activites of the IETF autoconf, dhc, ipv6, manet and v6ops working groups. 2. Terminology The mechanisms within this document build upon the fundamental principles of IP-within-IP encapsulation. The terms "inner" and "outer" are used throughout this document to respectively refer to the innermost IP {address, protocol, header, packet, etc.} *before* encapsulation, and the outermost IP {address, protocol, header, packet, etc.} *after* encapsulation. VET also supports the inclusion of "mid-layer" encapsulations between the inner and outer layers, including IPSec [RFC4301], the Subnetwork Encapsulation and Adaptation Layer (SEAL) [I-D.templin-seal], etc. The terminology in the normative references apply; the following terms are defined within the scope of this document: Templin Expires June 8, 2009 [Page 4] Internet-Draft VET December 2008 subnetwork the same as defined in [RFC3819]. enterprise the same as defined in [RFC4852]. site a logical and/or physical grouping of interfaces that connect a topological area less than or equal to the enterprise in scope. A site within an enterprise can be considered as an enterprise unto itself. Mobile Ad-hoc Network (MANET) a connected topology of mobile or fixed routers that maintain a routing structure among themselves over MANET link types [I-D.clausen-manet-linktype], where a wide variety of MANETs share common properties with enterprise networks. Further information on MANETs can be found in [RFC2501]. enterprise/site/MANET throughout the remainder of this document, the term "enterprise" is used to collectively refer to any of enterprise/site/MANET, i.e., the VET mechanisms and operational principles apply equally to enterprises, sites and MANETs. enterprise router an Enterprise Interior Router, Enterprise Border Router, or Enterprise Border Gateway. As depicted in Figure 1, an enterprise router comprises a router function, a host function, one or more enterprise-interior interfaces and zero or more internal virtual, enterprise-edge, provider-edge and VET interfaces. Enterprise Interior Router (EIR) a fixed or mobile enterprise router that forwards packets over one or more sets of enterprise-interior interface; each set connected to a distinct enterprise. Enterprise Border Router (EBR) an EIR that connects edge networks to the enterprise, and/or connects multiple enterprises together. An EBR configures a seperate VET interface over each set of enterprise-interior interfaces that connect the EBR to each distinct enterprise, i.e., an EBR may configure mulitple VET interfaces - one for each distinct enterprise. All EBRs are also EIRs. Templin Expires June 8, 2009 [Page 5] Internet-Draft VET December 2008 Enterprise Border Gateway (EBG) an EBR that either directly or indirectly connects the enterprise to provider networks and can delegate addresses/prefixes to other EBRs within the enterprise. All EBGs are also EBRs. internal-virtual interface a virtual interface that is a special case of either an enterprise-edge or an enterprise-interior interface. Internal- virtual interfaces that are also enterprise-edge interfaces are often loopback interfaces of some form. Internal-virtual interfaces that are also enterprise-interior interfaces are often tunnel interfaces of some form configured over another enterprise- interior interface. enterprise-edge interface an EBR's attachment to a link (e.g., an ethernet, a wireless personal area network, etc.) on an arbitrarily-complex edge network that the EBR connects to an enterprise and/or to provider networks. provider-edge interface an EBR's attachment to the Internet, or to a provider network outside of the enterprise via which the Internet can be reached. enterprise-interior interface a EIR's attachment to a link within an enterprise. An enterprise- interior interface is "neutral" in its orientation, i.e., it is inherently neither an enterprise-edge nor provider-edge interface. In particular, a packet may need to be forwarded over several enterprise-interior interfaces before it is forwarded via either an enterprise-edge or provider-edge interface. Enterprise Local Address (ELA) an enterprise-scoped IP address (e.g., an IPv6 Unique Local Address [RFC4193], an IPv4 privacy address [RFC1918], etc.) that is assigned to an enterprise-interior interface and unique within the enterprise. ELAs are used as identifiers for operating the routing protocol and/or locators for packet forwarding within the scope of the enterprise; ELAs are also used as *outer* IP addresses during encapsulation. Virtual Enterprise Traversal (VET) an abstraction that uses IP-in-IP encapsulation to span a multi- link enterprise in a single (inner) IP hop. Templin Expires June 8, 2009 [Page 6] Internet-Draft VET December 2008 VET interface an EBR's Non-Broadcast, Multiple Access interface used for Virtual Enterprise Traversal. The EBR configures a VET interface over a set of underlying enterprise-interior interface(s) belonging to the same enterprise. When there are multiple distinct enterprises (each with their own distinct set of enterprise-interior interfaces), the EBR configures a separate VET interface over each set of enterprise-interior interfaces, i.e., the EBR configures multiple VET interfaces. The VET interface encapsulates each inner IP packet in any mid- layer headers plus an outer IP header then forwards it on an underlying enterprise-interior interface such that the TTL/Hop Limit in the inner header is not decremented as the packet traverses the enterprise. The VET interface presents an automatic tunneling abstraction that represents the enterprise as a single IP hop. The following additional acronyms are used throughout the document: CGA - Cryptographically Generated Address DHCP[v4,v6] - the Dynamic Host Configuration Protocol FIB - Forwarding Information Base ISATAP - Intra-Site Automatic Tunnel Addressing Protocol ND - Neighbor Discovery PIO - Prefix Information Option PRL - Potential Router List RIO - Route Information Option RS/RA - IPv6 Neighbor Discovery Router Solicitation/Advertisement SEAL - Subnetwork Encapsulation and Adaptation Layer SLAAC - IPv6 StateLess Address AutoConfiguation 3. Enterprise Characteristics Enterprises consist of links that are connected by enterprise routers as depicted in Figure 1. All enterprise routers are also Enterprise Interior Routers (EIRs), and typically participate in a routing protocol over enterprise-interior interfaces to discover routes that may include multiple Layer-2 or Layer-3 forwarding hops. Enterprise Border Routers (EBRs) are EIRs that connect edge networks and/or join multiple enterprises together, while Enterprise Border Gateways (EBGs) are EBRs that either directly or indirectly connect enterprises to provider networks. An enterprise may be as simple as a small collection of enterprise routers (and their attached edge networks); an enterprise may also contain other enterprises and/or be a subnetwork of a larger Templin Expires June 8, 2009 [Page 7] Internet-Draft VET December 2008 enterprise. An enterprise may further encompass a set of branch offices and/or nomadic hosts connected to a home office over one or several service providers, e.g., through Virtual Private Network (VPN) tunnels. Enterprises that comprise link types with sufficiently similar properties (e.g., Layer-2 (L2) address formats, maximum transmission units (MTUs), etc.) can configure a sub-IP layer routing service such that IP sees the enterprise 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 enterprise without IP layer encapsulation. Enterprises that comprise link types with diverse properties and/or configure multiple IP subnets must also provide a routing service that operates as an IP layer mechanism. In that case, multiple IP hops may be necessary to traverse the enterprise such that specific autoconfiguration procedures are necessary to avoid multilink subnet issues [RFC4903]. In particular, we describe herein the use of IP- in-IP encapsulation to span the enterprise in a single (inner) IP hop in order to avoid the multilink subnet issues that arise when enterprise-interior interfaces are used directly by applications. Conceptually, an enterprise router (i.e, an EIR/EBR/EBG) embodies both a host function and router function. The host function supports global-scoped communications over any of the enterprise router's non- enterprise-interior interfaces according to the weak end system model [RFC1122] and also supports enterprise-local-scoped communications over its enterprise-interior interfaces. The router function connects the enterprise router's attached edge networks to the enterprise and/or connects the enterprise to other networks including the Internet (see: Figure 1). In addition to other interface types, EBRs configure VET interfaces that view all other EBRs in an enterprise as single-hop neighbors, where the enterprise can also appear as a single IP hop within another enterprise. EBRs configure a separate VET interface for each distinct enterprise to which they connect, and discover a list of EBRs for each VET interface that can be used for forwarding packets to off-enterprise destinations. The following sections present the Virtual Enterprise Traversal approach. 4. Autoconfiguration EIRs configure enterprise-interior interfaces. An EBR is an EIR that also configures enterprise-edge and VET interfaces. An EBG is an EBR that also either directly or indirectly connects the enterprise to a provider network. EIRs, EBRs and EBGs configure themselves for Templin Expires June 8, 2009 [Page 8] Internet-Draft VET December 2008 operation according to the following subsections: 4.1. Enterprise Interior Router (EIR) Autoconfiguration EIRs configure enterprise-interior interfaces and engage in routing protocols over those interfaces. When an EIR joins an enterprise, it first configures a unique IPv6 link-local address on each enterprise-interior interface that requires an IPv6 link-local capability and an IPv4 link-local address on each enterprise-interior interface that requires an IPv4 link- local capability. IPv6 link-local address generation mechanisms that provide sufficient uniqueness include Cryptographically Generated Addresses (CGAs) [RFC3972], IPv6 Privacy Addresses [RFC4941], StateLess Address AutoConfiguration (SLAAC) using EUI-64 interface identifiers [RFC4862], etc. The mechanisms specified in [RFC3927] provide an IPv4 link-local address generation capability. Next, the EIR configures an Enterprise Local Address (ELA) of the outer IP protocol version on each of its enterprise-interior interfaces and engages in any routing protocols on those interfaces. The EIR can configure an ELA via explicit management, DHCP autoconfiguration, pseudo-random self-generation from a suitably large address pool, or through an alternate autoconfiguration mechanism. In some enterprise use cases (e.g., highly dynamic MANETs), assignment of ELAs as singleton addresses (i.e., as /32s for IPv4 and /128s for IPv6) may be necessary to avoid multilink subnet issues. EIRs that configure ELAs using DHCP may require relay support from other EIRs within the enterprise; the EIR can alternatively configure both a DHCP client and relay that are connected, e.g., via a pair of back-to-back connected ethernet interfaces, a tun/tap interface, a loopback interface, custom S/W coding, etc. For DHCPv6, relays that do not already know the ELA of a server relay requests to the 'All_DHCP_Servers' site-scoped IPv6 multicast group. For DHCPv4, relays that do not already know the ELA of a server relay requests to the site-scoped IPv4 multicast group address TBD (see: Section 8). DHCPv4 servers that delegate ELAs join the TBD multicast group and service any DHCPv4 messages received for that group. Self-generation of ELAs for IPv6 can be from a large IPv6 local-use address range, e.g., IPv6 Unique Local Addresses [RFC4193]. Self- generation of ELAs for IPv4 can be from a large IPv4 private address range (e.g., [RFC1918]). When self-generation is used alone, the EIR must continuously monitor the ELAs for uniqueness, e.g., by monitoring the routing protocol, but care must be taken in the interaction of this monitoring with existing mechanisms. Templin Expires June 8, 2009 [Page 9] Internet-Draft VET December 2008 A combined approach using both DHCP and self-generation is also possible in which the EIR first self-generates a temporary ELA used only for the purpose of procuring an actual ELA taken from a disjoint addressing range. The EIR then assigns the temporary ELA to an enterprise-interior interface, engages in the routing protocol and performs a DHCP client/relay exchange using the temporary ELA as the address of the relay. When the DHCP server delegates an actual ELA, the EIR abandons the temporary ELA, assigns the actual ELA to the enterprise-interior interface and re-engages in the routing protocol. 4.2. Enterprise Border Router (EBR) Autoconfiguration EBRs are EIRs that configure enterprise-edge interfaces and also configure VET interfaces over sets of underlying enterprise-interior interfaces. Note that an EBR may connect to multiple distinct enterprises, in which case it would configure multiple VET interfaces. EBRs perform the following autoconfiguration operations: 4.2.1. VET Interface Autoconfiguration VET interface autoconfiguration entails: 1) interface initialization, 2) EBG discovery and enterprise identification, and 3) IPv6 stateless address autoconfiguration. These functions are specified in the following sections: 4.2.1.1. Interface Initialization EBRs configure a VET interface over a set of underlying enterprise- interior interfaces belonging to the same enterprise, where the VET interface presents a virtual view of all EBRs in the enterprise as single hop neighbors through the use of IP-in-IP encapsulation. When IPv6 and IPv4 are used as the inner/outer protocols (respectively), the EBR autoconfigures an ISATAP link-local address ([RFC5214], Section 6.2) on the VET interface to support packet forwarding and operation of the IPv6 neighbor discovery protocol. The ISATAP link-local address embeds an IPv4 ELA assigned to an underlying enterprise-interior interface, and need not be checked for uniqueness since the IPv4 ELA itself was already determined to be unique (see: Section 4.1). Link-local address configuration for other inner/outer IP protocol combinations is through administrative configuration or through an unspecified alternate method. After the EBR configures a VET interface, it can communicate with other EBRs as single-hop neighbors from the viewpoint of the inner IP protocol (where discovery of other EBRs is discussed in Section 5.4). The EBR can also confirm reachability of other EBRs through Neighbor Discovery (ND) and/or DHCP exchanges over the VET interface, or Templin Expires June 8, 2009 [Page 10] Internet-Draft VET December 2008 through other means such as information conveyed in the routing protocol. The EBR must be able to detect and recover from the loss of VET interface neighbors due to, e.g., network partitions, node failures, etc. Mechanisms specified outside of this document such as monitoring the routing protocol, ND beaconing/polling, DHCP renewals/ leasequeries, upper layer protocol hints of forward progress, bidirectional forward detection, detection of network attachment, etc. can be used according to the particular deployment scenario. 4.2.1.2. Enterprise Border Gateway Discovery and Enterprise Identification After the EBR configures its VET interfaces, it next discovers a list of EBGs for each distinct enterprise to which it connects. The list can be discovered through information conveyed in the routing protocol and/or through the Potential Router List (PRL) discovery mechanisms outlined in [RFC5214], Section 8.3.2. In particular, whether or not routing information is available the EBR can discover the list of EBGs by resolving an identifying name for the enterprise using an enterprise local name resolution service (e.g., and enterprise-wide DNS service, LLMNR [RFC4759], etc.). In the absence of other identifying names, the EBR can resolve either the hostname "6over4" or the FQDN "6over4.example.com" (i.e., if an enterprise specific suffix "example.com" is known) for multicast capable enterprises. For non-multicast enterprises, the EBR can instead resolve the hostname "isatap" or the FQDN "isatap.example.com". Identifying names along with addresses of EBGs and/or the prefixes they aggregate serve as an identifier for the enterprise. 4.2.1.3. IPv6 Stateless Address Autoconfiguration (SLAAC) When IPv6 is used as the inner protocol, the EBR sends unicast IPv6 Router Solicitation (RS) messages over its VET interface(s) to receive Router Advertisements (RAs) from EBGs. When the EBR receives an RA containing Prefix Information Options (PIOs) with the 'A' and 'L' bits set to 1, it autoconfigures IPv6 addresses from the prefixes using SLAAC and assigns them to the VET interface. (When IPv4 is used as the outer IP protocol, the addresses are autoconfigured and assigned as ISATAP addresses the same as specified in [RFC5214].) The use of DHCPv6 for address configuration on VET interfaces is undefined. Templin Expires June 8, 2009 [Page 11] Internet-Draft VET December 2008 4.2.2. Inner IP Address/Prefix Delegation and Maintenance EBRs acquire inner IP protocol addresses and/or prefix delegations through autoconfiguration exchanges via EBGs over VET interfaces, as discussed in the following sections: 4.2.2.1. IPv4 Addresses/Prefix Delegation When IPv4 is used as the inner IP protocol, the EBR acquires IPv4 prefixes for sub-delegation and/or assignment on its enterprise-edge interfaces. This could be via an unspecified automated prefix delegation exchange, explicit management, etc. 4.2.2.2. IPv6 Addresses/Prefix Delegation If the EBR receives an RA from an EBG that contains PIOs with the 'L' bit set to 0, it can use the PIOs as hints of prefixes a DHCPv6 server reachable via the EBG may be willing to delegate (see: Section 5.4). Whether or not such hints are available, the EBR (acting as a requesting router) can use DHCPv6 prefix delegation [RFC3633] over the VET interface to obtain IPv6 prefixes from the server (acting as a delegating router). The EBR can then use the delegated prefixes for sub-delegation on enterprise-edge networks and/or assignment on its enterprise-edge interfaces. The EBR obtains prefixes using either a 2-message or 4-message DHCPv6 exchange [RFC3315]. For example, to perform the 2-message exchange the EBR's DHCPv6 client forwards a Solicit message with an IA_PD option to its DHCPv6 relay, i.e., the EBR acts as a combined client/ relay (see: Section 4.1). The relay then forwards the message over the VET interface to the server via the EBG. The forwarded Solicit message will elicit a Reply from the server containing IPv6 prefix delegations. The EBR can also propose a specific prefix to the DHCPv6 server per Section 7 of [RFC3633], e.g., if a prefix delegation hint is available. The server will check the proposed prefix for consistency and uniqueness, then return it in the reply to the EBR if it was able to perform the delegation. The EBR can use mechanisms such as CGAs [RFC3972], IPv6 privacy address [RFC4941], etc. to self-generate addresses in conjunction with prefix delegation. 4.2.3. Portable Inner IP Addresses/Prefixes Independent of any inner IP address/prefix delegations (see: Section 4.2.2), an EBR can also use portable IP addresses/prefixes (e.g., taken from a home network) and/or self-configured IP addresses/prefixes (e.g., IPv6 Unique Local Addresses (ULAs) Templin Expires June 8, 2009 [Page 12] Internet-Draft VET December 2008 [RFC4193][I-D.ietf-ipv6-ula-central]). Indeed, the mechanisms defined herein easily support portable addresses/prefixes for enterprises that choose to use them. The EBR can continue to use these addresses/prefixes as it travels between visited enterprise networks as long as it coordinates in some fashion with a mapping agent, prefix aggregation authority, etc. EBRs can also sub-delegate portable (and other self-configured) prefixes to requesting routers on networks connected on their enterprise-edge interfaces as well as to EBRs in other enterprises. 4.2.4. Enterprise-edge Interface Autoconfiguration After the EBR receives inner IP address/prefix delegations (see: Section 4.2.2), it assigns them on enterprise-edge interfaces only; it does not assign them on provider-edge, VET, or enterprise-interior interfaces (see: [RFC3633], Section 12.1). Similarly, the EBR can assign portable and/or self-configured addresses/prefixes (see: Section 4.2.3) on enterprise-edge interfaces. 4.3. Enterprise Border Gateway (EBG) Autoconfiguration EBGs are EBRs that connect an enterprise to a service provider either directly via provider-edge interfaces or indirectly via another enterprise. EBGs configure provider-edge interfaces in a manner that is specific to its provider connections. EBGs should also configure a DHCP relay/server that can service prefix delegation requests from EBRs. EBGs must arrange to add their enterprise-interior interface addresses to the PRL (see: Section 4.2.1.2), and must maintain these resource records in accordance with ([RFC5214], Section 9). EBGs add their enterprise-interior interface addresses to the hostname "isatap" and/or the FQDN "isatap.example.com"; EBGs that connect to multicast-capable enterprises additionally add these addresses to the hostname "6over4" and/or the FQDN "6over4.example.com". 4.4. VET Host Autoconfiguration Non-routing hosts that cannot be attached via an EBR's enterprise- edge interface (e.g., nomadic laptops that connect to a home office via a Virtual Private Network (VPN)) can instead be configured for operation as a simple host connected to the VET interface. Such VET hosts configure one or more VET interfaces over corresponding sets of Templin Expires June 8, 2009 [Page 13] Internet-Draft VET December 2008 enterprise-interior interfaces exactly as for EBRs, but they do not configure a router function nor provide packet forwarding services for nodes on enterprise-edge interfaces. VET hosts can then send packets to other hosts on the VET interface, or to off-enterprise destinations via a next-hop EBR. 5. Post-Autoconfiguration Operation The following sections discuss post-autoconfiguration operations: 5.1. Routing Protocol Participation After an EIR has been autoconfigured, it participates in any routing protocols over enterprise-interior interfaces and forwards outer IP packets within the enterprise as for any ordinary router. EBRs can additionally engage in any inner IP routing protocols over enterprise-edge, provider-edge and VET interfaces, and can use those interfaces for forwarding inner IP packets to off-enterprise destinations. Note that these inner IP routing protocols are separate and distinct from any enterprise-interior routing protocols. 5.2. DHCP Prefix Delegation Maintenance When DHCP prefix delegation is used, the DHCP server ensures that the delegations are unique and that the EBG's router function will forward IP packets over the VET interface to the EBRs to which the prefixes were delegated. The EBRs can then sub-delegate inner IP prefixes to requesting routers on networks connected on their enterprise-edge interfaces as well as to EBRs in other enterprises. The DHCP prefix delegations remain active as long as the EBR continues to issue renewals over the VET interface before lease lifetimes expire. The lease lifetime also keeps the delegation state active even if communications between the EBR and DHCP server are disrupted for a period of time (e.g., due to an enterprise network partition) before being reestablished (e.g., due to an enterprise network merge). Since the DHCP client and relay are co-resident on the same EBR, no special coordination is necessary for the EBG to maintain routing information. The EBG simply retains Forwarding Information Base (FIB) entries that identify the EBR as the next-hop toward the prefix over the VET interface. Templin Expires June 8, 2009 [Page 14] Internet-Draft VET December 2008 5.3. IPv6 Prefix Mapping EBRs in enterprises that are managed under a cooperative administrative authority should use the enterprise name service (e.g., the DNS [RFC1035]) as the IPv6 prefix mapping service. EBRs in enterprises that are managed in a distributed fashion should implement their own distributed name resolution service (e.g., LLMNR [RFC4759]). For each /64 IPv6 prefix reachable via one of its enterprise edge interfaces, the EBR configures the IPv6 subnet router anycast address for the prefix [RFC4291], e.g., on a loopback interface. The EBR then publishes the most-significant 64 bits of the prefix in the enterprise name service using the domain name suffix 'isatap.example.com'. The EBR publishes the prefix as a domain name containing a sequence of 16 nibbles in reverse order using a format corresponding to that specified in ([RFC3596], Section 2.5). For example, the EBR publishes the prefix 2001:DB8::/64 as: '0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.isatap.example.com'. For publications within the interdomain global DNS itself, the domain name suffix 'isatap.net' is used instead of 'isatap.example.com'. The EBR includes in the publication IPv4 addresses (e.g., in DNS A records) taken from the EBR's enterprise interior interfaces, and an IPv6 link-local CGA address [RFC3972] (e.g., in DNS AAAA records) that other nodes can use to uniquely identify the EBR (or one of a group of redundant EBRs). In enterprises with a cooperative administrative authority, EBRs coordinate their publications with an administrator and/or by using a secure automated name service update mechanism (e.g., [RFC3007]). In enterprises that are managed in a distributed fashion, EBRs publish their /64 IPv6 prefixes through direct responses to distributed name resoultion service queries. In this way, the name service itself becomes an extension of the enterprise's PRL. 5.4. IPv6 EBR/EBG Router Discovery EBGs follow the router and prefix discovery procedures specified in ([RFC5214], Section 8.2). They send RAs over VET interfaces for which they are gateways with PIOs for SLAAC, with the 'M' flag set to 0 and with the 'O' flag set to indicate whether "other" DHCP services are available. EBGs can also include PIOs with the 'L' bit set to 0 and with a prefix such as 2001:DB8::/48 as a hint of an aggregated prefix from which it is willing to delegate longer prefixes. VET hosts and EBRs follow the router and prefix discovery procedures specified in ([RFC5214], Section 8.3). They discover EBGs by Templin Expires June 8, 2009 [Page 15] Internet-Draft VET December 2008 resolving the names "6over4.example.com" and/or "isatap.example.com"; in some multicast-capable deployments, they can also derive hints of EBG reachability by listening for advertisements on the 'rasadv' [RASADV] IPv4 multicast group address. VET hosts and EBRs discover the EBRs for specific IPv6 prefixes by querying the name service for the /64 IPv6 prefix corresponding to a packet's destination address. For example, for the IPv6 destination address 2001:DB8:1:2::1 the VET host/EBR queries the 'isatap.example.com' domain for the domain name: '2.0.0.0.1.0.0.0.8.b.d.0.1.0.0.2.isatap.example.com'. The name service query will return IPv4 addresses (e.g., in DNS A records) that correspond to an EBR's enterprise interior interfaces and an IPv6 link-local CGA address (e.g., in DNS AAAA records) that the VET host/EBR can use to verify EBR/EBG address ownership. VET hosts and EBRs discover default router lifetimes, default router preferences and more-specific routes [RFC4191] by sending an RS over the VET interface using the link-local CGA address of the EBR/EBG as the destination address. The EBR/EBG returns an RA using Secure Neighbor Discovery (SEND) [RFC3971], with the CGA published in the name service as the IPv6 link-local source address and with an IPv4 address taken from its enterprise interior addresses as the IPv4 address in the outer header. The VET host/EBR can then use SEND to verify that the RA came from the correct EBR/EBG. VET hosts and EBRs must only accept PIOs, M/O flag settings and default router preferences in RAs that are received from EBGs; they MUST NOT accept them from ordinary EBRs. 5.5. Forwarding Packets to Destinations Outside of the Enterprise After default and/or more-specific routes are discovered, VET hosts and EBRs can forward IP packets to off-enterprise destinations by consulting the FIB to determine a specific EBR/EBG as the next-hop router on the VET interface. When multiple next-hop routers are available, VET hosts and EBRs can use default router preferences, routing protocol information, traffic engineering configurations, etc. to select the best exit router. When there is no FIB information available, VET hosts and EBRs can discover the next-hop EBR/EBG through the mechanisms specified in Section 5.4. VET interfaces encapsulate inner IP packets in any mid-layer headers followed by an outer IP header according to the specific encapsulation type (e.g., [RFC4301][RFC5214][I-D.templin-seal]); they next submit the encapsulated packet to the outer IP forwarding engine for transmission on an underlying enterprise-interior interface. For forwarding to next-hop addresses over VET interfaces that use IPv6- Templin Expires June 8, 2009 [Page 16] Internet-Draft VET December 2008 in-IPv4 encapsulation, VET hosts and EBRs determine the outer destination address through static extraction of the IPv4 address embedded in the next-hop ISATAP address. For other IP-in-IP encapsulations, determination of the outer destination address is through administrative configuration or through an unspecified alternate method. When a VET host/EBR forward packets to an EBG that has more comprehensive FIB information, the EBG can forward the packet and issue ordinary ICMP redirects over the VET interface as necessary. If the next-hop corresponds to a node outside the enterprise, the EBG decapulates the packet and forwards it the same as for an ordinary router. If the next-hop corresponds to another node on the VET interface, however, the EBG forwards the packet without decapsulation by rewriting the outer IP destination address but leaving the outer IP source address intact. 5.6. Source Address Verification VET hosts and EBRs must verify that the outer IP source address of a packet received on a VET interface is correct for the inner IP source address using the procedures specified in ([RFC5214], Section 7.3). 5.7. Enterprise-Local Communications When permitted by policy, end systems that configure the endpoints of enterprise-local communications can avoid VET interface encapsulation by directly invoking the outer IP protocol using ELAs assigned to their enterprise-interior interfaces. For example, when the outer protocol is IPv4, end systems can use IPv4 ELAs for enterprise-local communications over their enterprise-interior interfaces without using the VET interface. 5.8. Multicast In multicast-capable deployments, EIRs provide an enterprise-wide multicasting service such as Simplified Multicast Forwarding (SMF) [I-D.ietf-manet-smf] over their enterprise-interior interfaces such that outer IP multicast messages of site- or greater scope will be propagated across the enterprise. For such deployments, VET hosts and EBRs can also provide an inner IP multicast/broadcast capability over their VET interfaces through mapping of the inner IP multicast address space to the outer IP multicast address space. VET hosts and EBRs encapsulate inner IP multicast messages sent over the VET interface in any mid-layer headers (e.g., IPsec, SEAL, etc.) plus an outer IP header with a site-scoped outer IP multicast address as the destination. For the case of IPv6 and IPv4 as the inner/outer Templin Expires June 8, 2009 [Page 17] Internet-Draft VET December 2008 protocols (respectively), [RFC2529] provides mappings from the IPv6 multicast address space to the IPv4 multicast address space. For other IP-in-IP encapsulations, mappings are established through administrative configuration or through an unspecified alternate method. For multicast-capable enterprises, use of the inner IP multicast service for operating the ND protocol over the VET interface is available but should be used sparingly to minimize enterprise-wide flooding. 5.9. Service Discovery VET hosts and EBRs can peform enterprise-wide service discovery using a suitable name-to-address resolution service. Examples of flooding- based services include the use of LLMNR [RFC4759] over the VET interface or mDNS [I-D.cheshire-dnsext-multicastdns] over an underlying enterprise-interior interface. More scalable and efficient service discovery mechanisms are for further study. 6. Enterprise Partitioning EBGs can physically partition an enterprise by configuring multiple VET interfaces over multiple distinct sets of underlying interfaces. In that case, each partition (i.e., each VET interface) must configure its own distinct PRL zone (e.g., 'zone1.example.com', 'zone2.example.com', etc.). EBGs can logically partition an enterprise using a single VET interface by sending RAs with PIOs containing different IPv6 subnet prefixes to nodes in different logical partitions. EBGs can identify partitions, e.g., by examining IPv4 prefixes, observing the interfaces over which RSs are received, etc. In that case, a single PRL zone can cover all partitions. 7. Securing VET with SEAL Enterprises for which use of IPsec is infeasible (or for which additional mechanisms are desired) can use SEAL encapsulation [I-D.templin-seal] in conjunction with VET to defend against rogue routers and source address spoofing. When an ingress EBR in an enterprise that uses SEAL encapsulation has an IPv6 packet to send but there is no matching FIB entry, it should first send an IPv6 RA using the IPv6 subnet router anycast address [RFC4291] corresponding to the destination as the RA's destination Templin Expires June 8, 2009 [Page 18] Internet-Draft VET December 2008 and using its published IPv6 CGA address as the RA's source. The RA should contain SEND parameters and Route Information Options [RFC4191] corresponding to the ingress EBR's aggregated IPv6 prefixes. The ingress EBR should populate its FIB entries based on mapping lookups in parallel with sending the RA to the subnet router anycast address; it can optionally buffer the RA and subsequent packets while mapping lookups are performed, or it can forward the packets immediately via an EBG. Using this approach, the ingress EBR can optionally set the 'Acknolwedgement Requested' bit in the SEAL header to receive L2 confirmation that an egress EBR has received its RA, and can schedule retransmissions if no confirmation is received. The ingress EBR also sets the SEAL_ID in the packet such that the egress EBR can discover the current encapsulation sequence number. When an egress EBR that configures the subnet router anycast address receives the RA, it can use SEND mechanisms to verify that the packet came from an authentic ingress EBR and can use the SEAL_ID to track the sequence of subsequent packets it receives from the ingress EBR. The egress EBR can therefore use the SEAL_ID to detect and discard potentially spoofed packets that have IDs outside of the current window, and can use the prefixes received from the ingress EBR for egress filtering to detect source address spoofing. The egress EBR can also send an RS to elicit an RA from the ingress EBR to refresh prefix lifetimes, or at any time state synchronization must be reestablished. 8. IANA Considerations A Site-Local Scope IPv4 multicast group (TBD) for DHCPv4 server discovery is requested. The allocation should be taken from the 239.255.000.000-239.255.255.255 Site-Local Scope range in the IANA 'multicast-addresses' registry. 9. Security Considerations Security considerations for MANETs are found in [RFC2501]. Security considerations with tunneling that apply also to VET are found in [RFC2529][RFC5214]. The securing methods specified in Section 7 provide additional mitigation against both rogue EBRs (via SEND) and source address spoofing (via the SEAL_ID and prefix-based egress filtering). These mechanisms can further be fortifed and made more resiliant against Templin Expires June 8, 2009 [Page 19] Internet-Draft VET December 2008 DOS attacks when EIRs function as IPv6 RA-Guards [I-D.ietf-v6ops-ra-guard]. 10. 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. As for this document, these architectural principles also follow from earlier works articulated by the ROAD group deliberations of 1992. 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 proposals within the IETF have suggested similar mechanisms. [I-D.ietf-v6ops-tunnel-security-concerns] discusses security concerns regarding tunneling mechanisms that may subvert security through Network Address Translator (NAT) traversal. An automated IPv4 prefix delegation mechanism is proposed in [I-D.ietf-dhc-subnet-alloc]. 11. 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, Joel Halpern, Bob Hinden, Joe Macker, Thomas Narten, Alexandru Petrescu, John Spence, Jinmei Tatuya, Dave Thaler, Ole Troan, Michaela Vanderveen and others in the IETF AUTOCONF and MANET working groups. Many others have provided guidance over the course of many years. 12. Contributors The following individuals have contributed to this document: Eric Fleischman (eric.fleischman@boeing.com) Thomas Henderson (thomas.r.henderson@boeing.com) Steven Russert (steven.w.russert@boeing.com) Seung Yi (seung.yi@boeing.com) Ian Chakeres (ian.chakeres@gmail.com) contributed to earlier versions of the document. Templin Expires June 8, 2009 [Page 20] Internet-Draft VET December 2008 13. References 13.1. Normative References [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981. [RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or converting network protocol addresses to 48.bit Ethernet address for transmission on Ethernet hardware", STD 37, RFC 826, November 1982. [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC3007] Wellington, B., "Secure Domain Name System (DNS) Dynamic Update", RFC 3007, November 2000. [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. [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, "DNS Extensions to Support IP Version 6", RFC 3596, October 2003. [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003. [RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", RFC 3972, March 2005. [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, November 2005. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. Templin Expires June 8, 2009 [Page 21] Internet-Draft VET December 2008 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007. [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, March 2008. 13.2. Informative References [CATENET] Pouzin, L., "A Proposal for Interconnecting Packet Switching Networks", May 1974. [I-D.cheshire-dnsext-multicastdns] Cheshire, S. and M. Krochmal, "Multicast DNS", draft-cheshire-dnsext-multicastdns-07 (work in progress), September 2008. [I-D.clausen-manet-linktype] Clausen, T., "The MANET Link Type", draft-clausen-manet-linktype-00 (work in progress), October 2008. [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-07 (work in progress), July 2008. [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-08 (work in progress), November 2008. [I-D.ietf-v6ops-ra-guard] Levy-Abegnoli, E., Velde, G., Popoviciu, C., and J. Templin Expires June 8, 2009 [Page 22] Internet-Draft VET December 2008 Mohacsi, "IPv6 RA-Guard", draft-ietf-v6ops-ra-guard-01 (work in progress), September 2008. [I-D.ietf-v6ops-tunnel-security-concerns] Hoagland, J., Krishnan, S., and D. Thaler, "Security Concerns With IP Tunneling", draft-ietf-v6ops-tunnel-security-concerns-01 (work in progress), October 2008. [I-D.templin-seal] Templin, F., "The Subnetwork Encapsulation and Adaptation Layer (SEAL)", draft-templin-seal-23 (work in progress), August 2008. [IEN48] Cerf, V., "The Catenet Model for Internetworking", July 1978. [RASADV] Microsoft, "Remote Access Server Advertisement (RASADV) Protocol Specification", October 2008. [RFC1122] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, October 1989. [RFC1753] Chiappa, J., "IPng Technical Requirements Of the Nimrod Routing and Addressing Architecture", RFC 1753, December 1994. [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, February 1996. [RFC1955] Hinden, R., "New Scheme for Internet Routing and Addressing (ENCAPS) for IPNG", RFC 1955, June 1996. [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. [RFC2775] Carpenter, B., "Internet Transparency", RFC 2775, February 2000. [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via IPv4 Clouds", RFC 3056, February 2001. [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", Templin Expires June 8, 2009 [Page 23] Internet-Draft VET December 2008 RFC 3753, June 2004. [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. Wood, "Advice for Internet Subnetwork Designers", BCP 89, RFC 3819, July 2004. [RFC3927] Cheshire, S., Aboba, B., and E. Guttman, "Dynamic Configuration of IPv4 Link-Local Addresses", RFC 3927, May 2005. [RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast Addresses", RFC 4193, October 2005. [RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [RFC4759] Stastny, R., Shockey, R., and L. Conroy, "The ENUM Dip Indicator Parameter for the "tel" URI", RFC 4759, December 2006. [RFC4852] Bound, J., Pouffary, Y., Klynsma, S., Chown, T., and D. Green, "IPv6 Enterprise Network Analysis - IP Layer 3 Focus", RFC 4852, April 2007. [RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, June 2007. [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, September 2007. Appendix A. Duplicate Address Detection (DAD) Considerations A-priori uniqueness determination (also known as "pre-service DAD") for an ELA assigned on an enterprise-interior interface (such as specified in [RFC4862]) would require either flooding the entire enterprise or somehow discovering a link in the enterprise 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 an enterprise-wide DAD would be substantial and prone to false-negatives due to packet loss and intermittent connectivity. An alternative to pre-service DAD is to autoconfigure pseudo-random ELAs on enterprise-interior interfaces and employ a passive in-service DAD (e.g., one that monitors routing protocol messages for duplicate assignments). Templin Expires June 8, 2009 [Page 24] Internet-Draft VET December 2008 Pseudo-random IPv6 ELAs can be generated with mechanisms such as CGAs, IPv6 privacy addresses, etc. with very small probability of collision. Pseudo-random IPv4 ELAs can be generated through random assignment from a suitably large IPv4 prefix space. Consistent operational practices can assure uniqueness for EBG- aggregated addresses/prefixes, while statistical properties for pseudo-random address self-generation can assure uniqueness for the ELAs assigned on an EIR's enterprise-interior interfaces. Still, an ELA delegation authority should be used when available, while a passive in-service DAD mechanism should be used to detect ELA duplications when there is no ELA delegation authority. Appendix B. Change Log (Note to RFC editor - this section to be removed before publication as an RFC.) Changes from -21 to 22: o Using SEAL to secure VET Changes from -20 to 21: o Enterprise partitioning. o Mapping and name service management. Changes from -18 to 20: o Added support for simple hosts. o Added EBG name service maintenace procedures o Added router and prefix maintenace procedures Changes from -17 to 18: o adjusted section headings to group autoconf operations under EIR/ EBR/EBG. o clarified M/O bits o clarified EBG roles Changes from -15 to 17: Templin Expires June 8, 2009 [Page 25] Internet-Draft VET December 2008 o title change to "Virtual Enterprise Traversal (VET)". o changed document focus from MANET-centric to the much-broader Enterprise-centric, where "Enterprise" is understood to also cover a wide range of MANET types. Changes from -14 to 15: o title change to "Virtual Enterprise Traversal (VET) for MANETs". o Address review comments Changes from -12 to 14: o title change to "The MANET Virtual Ethernet Abstraction". o Minor section rearrangement. o Clartifications on portable and self-configured prefixes. o Clarifications on DHCPv6 prefix delegation procedures. Changes from -11 to 12: o title change to "MANET Autoconfiguration using Virtual Ethernet". o DHCP prefix delegation for both IPv4 and IPv6 as primary address delegation mechanism. o IPv6 SLAAC for address autoconfiguration on the VET interface. o fixed editorials based on comments received. 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". Templin Expires June 8, 2009 [Page 26] Internet-Draft VET December 2008 o Changed address delegation language to speak of "MNBR-aggregated" instead of global/local. o Updated figures 1-3. o Explained why a MANET interface is "neutral". o Removed DHCPv4 "MLA Address option". Now, MNBRs can only be DHCPv4 servers; not relays. Changes from -07 to -08: o changed terms "unenhanced" and "enhanced" to "transparent" and "opaque". o revised MANET Router diagram. o introduced RFC3753 terminology for Mobile Router; ingress/egress interface. o changed abbreviations to "MNR" and "MNBR". o added text on ULAs and ULA-Cs to "Self-Generated Addresses". o rearranged Section 3.1. o various minor text cleanups Changes from -06 to -07: o added MANET Router diagram. o added new references o various minor text cleanups Changed from -05 to -06: o Changed terms "raw" and "cooked" to "unenhanced" and "enhanced". o minor changes to preserve generality Changed from -04 to -05: o introduced conceptual "virtual ethernet" model. o support "raw" and "cooked" modes as equivalent access methods on the virutal ethernet. Templin Expires June 8, 2009 [Page 27] Internet-Draft VET December 2008 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 Author's Address Fred L. Templin (editor) Boeing Phantom Works P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: fltemplin@acm.org Templin Expires June 8, 2009 [Page 28] Internet-Draft VET December 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. 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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. Templin Expires June 8, 2009 [Page 29]