Network Working Group F. Templin, Ed. Internet-Draft Boeing Research and Technology Intended status: Informational January 08, 2009 Expires: July 12, 2009 Virtual Enterprise Traversal (VET) draft-templin-autoconf-dhcp-26.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 July 12, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract Enterprise networks connect routers over various link types, and may also connect to provider networks and/or the global Internet. Nodes Templin Expires July 12, 2009 [Page 1] Internet-Draft VET January 2009 in enterprise networks must have a way to automatically provision IP addresses/prefixes and other information, and must also support internetworking operation even in highly-dynamic networks. This document specifies a Virtual Enterprise Traversal (VET) abstraction for autoconfiguration and operation of nodes in enterprise networks. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Enterprise Characteristics . . . . . . . . . . . . . . . . . . 7 4. Autoconfiguration . . . . . . . . . . . . . . . . . . . . . . 9 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. Provider-Aggregated Prefix Autoconfiguration . . . . . 12 4.2.3. Provider-Independent Prefix Autoconfiguration . . . . 13 4.3. Enterprise Border Gateway (EBG) Autoconfiguration . . . . 13 4.4. VET Host Autoconfiguration . . . . . . . . . . . . . . . . 13 5. Internetworking Operation . . . . . . . . . . . . . . . . . . 14 5.1. Routing Protocol Participation . . . . . . . . . . . . . . 14 5.2. DHCP Prefix Delegation Maintenance . . . . . . . . . . . . 14 5.3. Forwarding Packets . . . . . . . . . . . . . . . . . . . . 15 5.4. IPv6 Prefix Mapping . . . . . . . . . . . . . . . . . . . 15 5.5. IPv6 Router Discovery and Ingress Filtering . . . . . . . 16 5.6. Fortifying VET with SEAL . . . . . . . . . . . . . . . . . 18 5.7. Enterprise-Local Communications . . . . . . . . . . . . . 18 5.8. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 18 5.9. Service Discovery . . . . . . . . . . . . . . . . . . . . 19 5.10. Enterprise Partitioning . . . . . . . . . . . . . . . . . 19 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20 8. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 20 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 21 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 11.1. Normative References . . . . . . . . . . . . . . . . . . . 21 11.2. Informative References . . . . . . . . . . . . . . . . . . 22 Appendix A. Duplicate Address Detection (DAD) Considerations . . 24 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 25 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 29 Templin Expires July 12, 2009 [Page 2] Internet-Draft VET January 2009 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 internetworking operation, 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 July 12, 2009 [Page 3] Internet-Draft VET January 2009 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, as well as the IRTF rrg working group. 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 July 12, 2009 [Page 4] Internet-Draft VET January 2009 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 an enterprise in scope. A site within an enterprise can in some sense 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 July 12, 2009 [Page 5] Internet-Draft VET January 2009 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 July 12, 2009 [Page 6] Internet-Draft VET January 2009 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 therefore presents an automatic tunneling abstraction that represents the enterprise as a single IP hop. VET node any node (host or router) that configures and uses a VET interface. 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 PRLNAME - Identifying name for the PRL (default is "isatap") 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 Templin Expires July 12, 2009 [Page 7] Internet-Draft VET January 2009 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 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, VET nodes (i.e., EBRs, EBGs and simple hosts) configure VET interfaces that view all other VET nodes in an enterprise as single-hop neighbors, where the enterprise can also appear as a single IP hop within another enterprise. VET nodes 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. Templin Expires July 12, 2009 [Page 8] Internet-Draft VET January 2009 4. Autoconfiguration EIRs, EBRs, EBGs and VET hosts configure themselves for 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 6). 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 Templin Expires July 12, 2009 [Page 9] Internet-Draft VET January 2009 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. 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 VET interfaces over distinct sets of underlying enterprise-interior interfaces; an EBR can connect to multiple 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 Templin Expires July 12, 2009 [Page 10] Internet-Draft VET January 2009 protocol (where discovery of other EBRs is discussed in Section 5.5). The EBR can also confirm reachability of other EBRs through Neighbor Discovery (ND) and/or DHCP exchanges over the VET interface, or 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 The EBR next discovers a list of EBGs for each of its VET interfaces, i.e., for each enterprise it connects to. 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 multicast-capable enterprises, they can also listen for advertisements on the 'rasadv' [RASADV] IPv4 multicast group address. In particular, whether or not routing information is available the EBR can discover the list of EBGs in the PRL by resolving an identifying "hostname" ('PRLNAME') using an enterprise local name resolution service (e.g., an enterprise-local DNS service, LLMNR [RFC4759], etc.). The EBR discovers 'PRLNAME' through 'rasadv' protocol advertisements, through a DHCP option, through link-layer information (e.g., an IEEE 802.11 SSID), or through some other means specific to the enterprise. In the absence of other information, the EBR can use manual configuration and by default sets 'PRLNAME' to "isatap". After discovering 'PRLNAME', the EBR can discover the list of EBGs by resolving either the hostname 'PRLNAME' or the FQDN 'PRLNAME'.example.com if an enterprise-specific domain name "example.com" is available. The hostname 'PRLNAME' (and/or the FQDN 'PRLNAME'.example.com) as well as the addresses of EBGs and/or the prefixes they aggregate serve as an identifier for the enterprise. Templin Expires July 12, 2009 [Page 11] Internet-Draft VET January 2009 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. 4.2.2. Provider-Aggregated Prefix Autoconfiguration EBRs acquire provider-aggregated prefixes through autoconfiguration exchanges with EBGs over VET interfaces. When IPv4 is used as the inner IP protocol, the EBR acquires provider-aggregated prefixes via an unspecified automated IPv4 prefix delegation exchange, explicit management, etc. When IPv6 is used as the inner IP protocol, the EBR acquires provider-aggregated prefixes via IPv6 Neighbor Discovery and DHCPv6 Prefix Delegation exchanges. 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 the DHCPv6 server may be willing to delegate (see: Section 5.5). 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 Provider-Aggregated IPv6 prefixes from the server (acting as a delegating router). 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 EBG. The forwarded Solicit message will elicit a reply from the server containing provider-aggregated IPv6 prefix delegations. The EBR can 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. After the EBR received provider-aggregated prefix delegations, it can Templin Expires July 12, 2009 [Page 12] Internet-Draft VET January 2009 provision the prefixes on its enterprise-edge interfaces as well as on other VET interfaces for which it is configured as an EBG. 4.2.3. Provider-Independent Prefix Autoconfiguration Independent of any provider-aggregated prefixes (see: Section 4.2.2), EBRs can also acquire and use provider-independent and/or self- configured prefixes (e.g., IPv6 Unique Local Addresses (ULAs) [RFC4193][I-D.ietf-ipv6-ula-central]). EBRs can retain their provider-independent addresses/prefixes as they travel between visited enterprise networks as long as they register the prefixes with new enterprises and (preferrably) withdraw the prefixes from departed enterprises. EBRs can use Secure Neighbor Discovery (SEND) [RFC3971] to prove ownership of their provider- independent prefixes and can use DHCPv6 prefix delegation to register the prefixes in the new enterprise. EBRs can also act as delegating routers to sub-delegate portions of their provider-independent prefixes to requesting routers on their enterprise edge interfaces and on VET interfaces for which they are configured as EBGs. In this sense, the sub-delegations of an EBR's provider-independent prefix become provider-aggregated prefixes for another EBR. 4.3. Enterprise Border Gateway (EBG) Autoconfiguration EBGs are EBRs that connect enterprises 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 also configure a DHCP relay/server that can service prefix delegation requests. For each VET interface on which it is configured as an EBG, the EBG must arrange to add its 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). In particular, for each such VET interface the EBG adds its enterprise-interior interface addresses to the hostname 'PRLNAME' and/or the FQDN 'PRLNAME'.example.com. 4.4. VET Host Autoconfiguration Nodes 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 enterprise- interior interfaces exactly as for EBRs, but they configure their VET interfaces as host interfaces (and not router interfaces). VET hosts Templin Expires July 12, 2009 [Page 13] Internet-Draft VET January 2009 can then send packets to other hosts on the VET interface, or to off- enterprise destinations via a next-hop EBR. 5. Internetworking Operation Following the autoconfiguration procedures specified in Section 4, EIRs, EBRs, EBGs and VET hosts engage in normal internetworking operations as discussed in the following sections: 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 correct EBR. 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). When the EBR leaves the enterprise, it should first release its delegated provider-dependent prefixes and unregister its provider-independent prefixes to avoid black-holing future communications. 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 prefixes over the VET interface. Templin Expires July 12, 2009 [Page 14] Internet-Draft VET January 2009 5.3. Forwarding Packets VET nodes forward packets 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 nodes 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 nodes can discover the next-hop EBR/EBG through the mechanisms specified in Section 5.5. 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-in-IPv4 encapsulation, VET nodes 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. 5.4. IPv6 Prefix Mapping For each of the /64 prefixes they aggregate, EBRs must respond to messages addressed to the prefix's IPv6 subnet router anycast address [RFC4291]. EBRs must also publish the prefixes in the enterprise- local name service using the domain name suffix 'PRLNAME.example.com; for publications within the global DNS itself, the domain name suffix "isatap.net" is used instead. EBRs in enterprises that are managed under a cooperative administrative authority should publish their prefixes in the enterprise name service (e.g., the DNS [RFC1035]). EBRs in enterprises that are managed in a distributed fashion should implement their own distributed name resolution services (e.g., LLMNR [RFC4759]). The EBR publishes the prefix as a domain name consisting of a sequence of 16 nibbles in reverse order the same as 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.'PRLNAME'.example.com'. The EBR (or one of a group of EBRs that service the same prefix) includes in each prefix publication IPv4 addresses (e.g., in DNS A Templin Expires July 12, 2009 [Page 15] Internet-Draft VET January 2009 records) taken from the EBRs' enterprise interior interfaces. 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 prefixes through direct responses to distributed name resoultion service queries via a mechanism such as LLMNR. Prefix publication in new enterprises should be coordinated in conjunction with prefix withdrawls in recently departed enterprises such that mobility events are handled gracefully. In this way, all of the EBRs/EBGs on the path from the VET node to the Internet core can adjust their forwarding information to track the node's provider- independent prefixes as it moves between enterprises. 5.5. IPv6 Router Discovery and Ingress Filtering 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 nodes follow the router and prefix discovery procedures specified in ([RFC5214], Section 8.3). They discover EBGs within the enterprise as specified in Section 4.2.1.2, then perform SEND- protected RS/RA exchanges with the EBG to maintain default routes. EBRs accept packets that are fowarded by EBGs for which they have valid default routes. EBRs can also discover destination-specific next-hop EBRs within the enterprise 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 node can lookup the domain name: '2.0.0.0.1.0.0.0.8.b.d.0.1.0.0.2.'PRLNAME'.example.com'. If the name service lookup succeeds, it will return IPv4 addresses (e.g., in DNS A records) that correspond to the enterprise interior interfaces of potential next-hop EBRs. If the lookup fails, the VET node can continue to forward its packets to a default EBG. When a VET node forwards a packet to an EBG that has a mapping for the destination, the EBG forwards the packet to a next-hop EBR on the VET interface and returns an ICMP redirect. If the packet's source address is on-link on the VET interface, the EBG returns an ordinary "router-to-host" redirect with the source address of the packet as Templin Expires July 12, 2009 [Page 16] Internet-Draft VET January 2009 its destination. If the packet's source address is not on-link, the EBG instead returns a "router-to-router" redirect with the link-local ISATAP address of the originating EBR as its destination. The EBG also includes in the redirect one or more link-layer address options containing IPv4 addresses of potential next-hop EBRs, where the target link-layer address options are formatted exactly as specified in [RFC2529]. That is to say, the redirect may contain multiple target link-layer address options; each representing the link-layer address of a potential next-hop EBR. When a VET node received an ordinay "router-to-host" redirect, it processes it exacly as specified in [RFC4861], Section 8. When an EBR receives a "router-to-router" redirect, it discovers the link layer addresses of potential next-hop EBRs by examining the target link-layer address options included in the redirect. The EBR then sends a SEND-protected RA to a potential next-hop EBR over the VET interface with a link-local CGA address as the source, the IPv6 subnet router anycast address corresponding to the original packet's destination address as the destination, and a link-layer (i.e., IPv4) destination corresponding to the potential EBR. The EBR also includes a Route Information Option (RIO) [RFC4191] in the RA that contains the /64 prefix of the original packet's source address. When the potential next-hop EBR receives the RA, it uses SEND to verify the signature then installs the IPv6 prefix in the RIO as an ingress filter entry [RFC3704]. By default, the potential next-hop EBR discards any packets that were forwarded by a non-default router and for which there is no matching ingress filter entry. Therefore, the EBR that sent the RA is responsible for determining that the potential next-hop EBR received it. After an EBR sends an initial RA, it should send periodic RAs to refresh the next-hop EBR's ingress filter prefix lifetimes as long as traffic is flowing. If a VET node detects that the path to a next- hop EBR is failing, it should either select an alternate potential next-hop EBR (if one is available) or allow packets to flow through an EBG until another ICMP redirect is received. When a next-hop EBR receives a packet for which it no longer has a route to the final destination, it returns an appropriate ICMP unreachable message. When the VET node that sent the packet receives the ICMP unreachable message, it should discard its current list of potential next-hop EBRs and allow packets to flow through an EBG until another ICMP redirect is received; this allows for graceful handling of mobility events. VET nodes must only accept PIOs, M/O flag settings and default router preferences in RAs that are received from EBGs; they MUST NOT accept Templin Expires July 12, 2009 [Page 17] Internet-Draft VET January 2009 them from ordinary EBRs. 5.6. Fortifying VET with SEAL VET nodes should use SEAL encapsulation [I-D.templin-seal] in conjunction with VET to accommdate path MTU diversity, to defend against rogue routers and source address spoofing, and to monitor next-hop EBR reachability. In terms of security, when a VET node receives an ICMP message, it can confirm that the packet-in-error within the ICMP message corresponds to one of its recently-sent packets by using the SEAL_ID as a nonce. Additionally, a next-hop EBR can track the SEAL_ID sequence in packets received from EBRs for which there is an ingress filter entry and discard packets that have SEAL_ID values outside of the current window. To maintain synchronization, the next-hop EBR resets its cached SEAL_IDs for correspondent EBRs/EBGs whenever it receives a fresh SEND-protected RA. In terms of next-hop reachability, an EBR can set the SEAL "Acknowledgement Requested" bit in RA messages to confirm that a potential next-hop EBR received and processed the RA. The EBR can additionally periodically set this bit in ordinary data messages to monitor next-hop EBR reachability. 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.) Templin Expires July 12, 2009 [Page 18] Internet-Draft VET January 2009 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 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. 5.10. 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. 6. 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. Templin Expires July 12, 2009 [Page 19] Internet-Draft VET January 2009 7. Security Considerations Security considerations for MANETs are found in [RFC2501]. Security considerations with tunneling that apply also to VET are found in [RFC2529][RFC5214]. In particular, VET nodes 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). The securing methods specified in Section 5.6 provide additional mitigation against both rogue EBRs (via SEND) and source address spoofing (via the SEAL_ID and prefix-based ingress filtering). 8. 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]. 9. Acknowledgements The following individuals gave direct and/or indirect input that was essential to the work: Jari Arkko, Teco Boot, Emmanuel Bacelli, Brian Carpenter, James Bound, Thomas Clausen, Joel Halpern, Bob Hinden, Sapumal Jayatissa, Dan Jen, Tony Li, Joe Macker, Thomas Narten, Alexandru Petrescu, John Spence, Jinmei Tatuya, Dave Thaler, Ole Troan, Michaela Vanderveen, Lixia Zhang and others in the IETF AUTOCONF and MANET working groups. Many others have provided guidance over the course of many years. Templin Expires July 12, 2009 [Page 20] Internet-Draft VET January 2009 10. 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. 11. References 11.1. 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. Templin Expires July 12, 2009 [Page 21] Internet-Draft VET January 2009 [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. [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. 11.2. 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. Templin Expires July 12, 2009 [Page 22] Internet-Draft VET January 2009 [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-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. Templin Expires July 12, 2009 [Page 23] Internet-Draft VET January 2009 [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. [RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed Networks", BCP 84, RFC 3704, March 2004. [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", RFC 3753, June 2004. [RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. Wood, "Advice for Internet Subnetwork Designers", BCP 89, RFC 3819, July 2004. [RFC3927] Cheshire, S., Aboba, B., and E. Guttman, "Dynamic Configuration of IPv4 Link-Local Addresses", RFC 3927, May 2005. [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 Templin Expires July 12, 2009 [Page 24] Internet-Draft VET January 2009 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). 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 -25 to 26: o Clarifications on Router Discovery and Ingress FIltering. o Mechanisms for detecting locator liveness o Mechanisms for avoiding state synchonization requirements. Changes from -23 to 24: o Clarifications on router discovery. Changes from -22 to 23: o Clarifications on prefix mapping. Changes from -21 to 22: Templin Expires July 12, 2009 [Page 25] Internet-Draft VET January 2009 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: 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. Templin Expires July 12, 2009 [Page 26] Internet-Draft VET January 2009 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". 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. Templin Expires July 12, 2009 [Page 27] Internet-Draft VET January 2009 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. 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 Templin Expires July 12, 2009 [Page 28] Internet-Draft VET January 2009 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 Research and Technology P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: fltemplin@acm.org Templin Expires July 12, 2009 [Page 29]