Network Working Group F. Templin, Ed. Internet-Draft Boeing Research and Technology Intended status: Informational January 24, 2009 Expires: July 28, 2009 Virtual Enterprise Traversal (VET) draft-templin-autoconf-dhcp-31.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 28, 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 28, 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 . . . . . . . . . . . . . . . . . . 8 4. Autoconfiguration . . . . . . . . . . . . . . . . . . . . . . 9 4.1. Enterprise Interior Router (EIR) Autoconfiguration . . . . 10 4.2. Enterprise Border Router (EBR) Autoconfiguration . . . . . 11 4.2.1. VET Interface Autoconfiguration . . . . . . . . . . . 11 4.2.2. Provider-Aggregated (PA) Prefix Autoconfiguration . . 12 4.2.3. Provider-Independent (PI) Prefix Autoconfiguration . . 13 4.3. Enterprise Border Gateway (EBG) Autoconfiguration . . . . 13 4.4. VET Host Autoconfiguration . . . . . . . . . . . . . . . . 14 5. Internetworking Operation . . . . . . . . . . . . . . . . . . 14 5.1. Routing Protocol Participation . . . . . . . . . . . . . . 14 5.2. PA Prefix Maintenance . . . . . . . . . . . . . . . . . . 14 5.3. IPv6 EBG Discovery . . . . . . . . . . . . . . . . . . . . 15 5.4. IPv6 PI Prefix Registration . . . . . . . . . . . . . . . 15 5.5. IPv6 Next-Hop EBR Discovery . . . . . . . . . . . . . . . 17 5.6. Forwarding Packets . . . . . . . . . . . . . . . . . . . . 18 5.7. SEAL Encapsulation . . . . . . . . . . . . . . . . . . . . 19 5.8. Generating Errors . . . . . . . . . . . . . . . . . . . . 19 5.9. Processing Errors . . . . . . . . . . . . . . . . . . . . 20 5.10. Mobility and Multihoming Considerations . . . . . . . . . 21 5.11. Enterprise-Local Communications . . . . . . . . . . . . . 22 5.12. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 22 5.13. Service Discovery . . . . . . . . . . . . . . . . . . . . 23 5.14. Enterprise Partitioning . . . . . . . . . . . . . . . . . 23 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 7. Security Considerations . . . . . . . . . . . . . . . . . . . 24 8. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 24 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 25 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25 11.1. Normative References . . . . . . . . . . . . . . . . . . . 25 11.2. Informative References . . . . . . . . . . . . . . . . . . 27 Appendix A. Duplicate Address Detection (DAD) Considerations . . 29 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 30 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 34 Templin Expires July 28, 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 28, 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. Enterprise routers must have a means for supporting both Provider- Independent (PI) and Provider-Independent (PA) IP prefixes for global-scope communications. This is especially true for enterprise scenarios that involve mobility and multihoming. Ingress filtering for multi-homed sites, adaptation based on authenticated ICMP feedback from on-path routers, effective tunnel path MTU mitigations and routing scaling suppression are also required in many enterprise network scenarios. The VET specification provides a comprehensive solution that addresses these issues and more. VET 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 to respectively refer to the innermost IP {address, Templin Expires July 28, 2009 [Page 4] Internet-Draft VET January 2009 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: 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 dynamic links, where a wide variety of MANETs share common properties with enterprise networks. Characteristics of MANETs are defined in [RFC2501], Section 3. 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, where each set connects to a distinct enterprise. Templin Expires July 28, 2009 [Page 5] Internet-Draft VET January 2009 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. In particular, an EBR may configure mulitple VET interfaces - one for each distinct enterprise. All EBRs are also EIRs. Enterprise Border Gateway (EBG) an EBR that connects VET interfaces configued over child enterprises to a provider network - either directly via a provider-edge interface, or indirectly via another VET interface configured over a parent enterprise. EBRs may act as EBGs on some VET interfaces and as ordinary EBRs on other VET interfaces. All EBGs are also EBRs. EBGs provide packet forwarding, relaying and mapping services on behalf of EBRs and ordinary VET hosts within the enterprise. A "default mapper" [I-D.jen-apt] is a special case of an EBG that performs all EBG services except forwarding packets to provider networks. Default mappers must therefore configure a default route via a fully-qualified EBG. enterprise-interior interface a EIR's attachment to a link within an enterprise. Packets sent over enterprise-interior interfaces may be forwarded over multiple additional enterprise-interior interfaces within the enterprise before they are forwarded via an enterprise-edge interface, provider-edge interface or a VET interface configured over a different enterprise. 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. 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. Templin Expires July 28, 2009 [Page 6] Internet-Draft VET January 2009 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 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 used as the *outer* IP addresses during encapsulation, and can also be used as addresses for enterprise-internal communications that do not require encapsulation. Provider-Independent (PI) prefix an IPv6 or IPv4 prefix (e.g., 2001:DB8::/48, 192.0.2/24, etc.) that is routable within a limited scope and may also appear in a global mapping table. PI prefixes that can appear in a global mapping table are typically delegated to an EBR by a registry, but are not aggregated by a provider network. Local-use IPv6 and IPv4 prefixes (e.g., FD00::/8, 192.168/16, etc.) are another example of a PI prefix, but these typically do not appear in a global mapping table. Provider Aggregated (PA) prefix an IPv6 or IPv4 prefix that is either derived from a PI prefix or delegated directly to a provider network by a registry. Virtual Enterprise Traversal (VET) an abstraction that uses IP-in-IP encapsulation to span a multi- link enterprise in a single (inner) IP hop. VET interface an EBR's Non-Broadcast, Multiple Access (NBMA) 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 Templin Expires July 28, 2009 [Page 7] Internet-Draft VET January 2009 automatic tunneling abstraction that represents the enterprise as a single IP hop. VET host any node (host or router) that configures a VET interface for host operation only. Note that a single node may configure some of its VET interfaces as host interfaces and others as router interfaces. VET node any node 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 NBMA - Non-Broadcast, Multiple Access ND - Neighbor Discovery PA - Provider Aggregated PI - Provider Independent 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 enterprises to provider networks. A "default mapper" is a special case of an EBG that performs all EBG services except forwarding packets 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 Templin Expires July 28, 2009 [Page 8] Internet-Draft VET January 2009 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 engages in the enterprise-interior routing protocol, connects any of the enterprise router's edge networks to the enterprise and may also connect the enterprise to provider networks (see: Figure 1). In addition to other interface types, VET nodes 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. 4. Autoconfiguration EIRs, EBRs, EBGs, and VET hosts configure themselves for operation as specified in the following subsections: Templin Expires July 28, 2009 [Page 9] Internet-Draft VET January 2009 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 'All_DHCPv4_Servers' (see: Section 6). DHCPv4 servers that delegate ELAs join the 'All_DHCPv4_Servers' 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 July 28, 2009 [Page 10] Internet-Draft VET January 2009 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 Non-Broadcast, Multiple Access (NBMA) abstraction in which all EBRs in the enterprise appear 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 checked (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 VET nodes as single-hop neighbors from the viewpoint of the inner IP protocol. Templin Expires July 28, 2009 [Page 11] Internet-Draft VET January 2009 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. 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 name for the PRL ('PRLNAME') using an enterprise local name resolution service (e.g., an enterprise-local DNS service, LLMNR [RFC4759], etc.). 'PRLNAME' is formed as 'hostname.domainname', where 'hostname' is an enterprise-specific name string and 'domainname' is an enterprise-specific DNS suffix when such a suffix is available. The EBR discovers 'PRLNAME' through manual configuration, a DHCP option, 'rasadv' protocol advertisements, 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 sets the 'hostname' component of 'PRLNAME' to "isatap" and sets the 'domainname' component only if an enterprise-specifc DNS suffix "example.com" is known (e.g., as "isatap.example.com"). After discovering 'PRLNAME', the EBR can discover the list of EBGs by resolving 'PRLNAME' to a list of IPv4 addresses through a name service lookup. 'PRLNAME' as well as the ELAs of EBGs and/or the IP prefixes they aggregate serve as an identifier for the enterprise. 4.2.2. Provider-Aggregated (PA) Prefix Autoconfiguration EBRs can acquire Provider-Aggregated (PA) prefixes through autoconfiguration exchanges with EBGs over VET interfaces. When IPv4 is used as the inner IP protocol, the EBR acquires PA prefixes via an unspecified automated IPv4 prefix delegation exchange, explicit management, etc. When IPv6 is used as the inner IP protocol, the EBR acquires PA prefixes via IPv6 Neighbor Discovery and DHCPv6 Prefix Delegation exchanges. In particular, the EBR (acting as a requesting router) can use DHCPv6 prefix delegation [RFC3633] over the VET interface to obtain PA IPv6 prefixes from the server (acting as a delegating router). The EBR obtains prefixes using either a 2-message or 4-message DHCPv6 Templin Expires July 28, 2009 [Page 12] Internet-Draft VET January 2009 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 PA 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 receives PA prefix delegations, it can 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 (PI) Prefix Autoconfiguration Independent of any PA prefixes, EBRs can acquire and use Provider- Independent (PI) prefixes that are either delegated by a registration authority or self-configured by the EBR [RFC4193][I-D.ietf-ipv6-ula-central]). When an EBR acquires a PI prefix, it must also obtain credentials (e.g., from a certification authority) that it can use to prove prefix ownership through Secure Neighbor Discovery (SEND) [RFC3971] messaging. The minimum-sized PI prefix that an EBR may acquire is a /56. 4.3. Enterprise Border Gateway (EBG) Autoconfiguration EBGs are EBRs that connect child enterprises to a provider network via ordinay provider-edge interfaces and/or VET interfaces configured over parent enterprises. EBGs autoconfigure provider-edge interfaces in a manner that is specific to their provider connections, and autoconfigure VET interfaces as specified in Section 4.2.1. EBGs that support PA prefix delegation also configure a DHCP relay/server. For each VET interface on which it is configured as an EBG, the EBG must arrange to add its enterprise-interior interface addresses (i.e., its ELAs) 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 ELAs to name service resource records for 'PRLNAME'. Templin Expires July 28, 2009 [Page 13] Internet-Draft VET January 2009 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 perform the same VET interface autoconfiguration procedures as specified for EBRs in Section 4.2.1, but they configure their VET interfaces as host interfaces (and not router interfaces). VET hosts can then send packets to other hosts on the VET interface, or to off-enterprise destinations via a next-hop EBR. Note that a node may be configured as a host on some VET interfaces and as an EBR/EBG on other VET interfaces. 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 Following autoconfiguration, EIRs engage in any routing protocols over their enterprise-interior interfaces and forward outer IP packets within the enterprise as for any ordinary router. EBRs can additionally engage in any inner IP routing protocols over enterprise-edge and provider-edge 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. PA Prefix Maintenance When an EBR uses DHCP prefix delegation to obtain PA prefixes via an EBG, 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). Templin Expires July 28, 2009 [Page 14] Internet-Draft VET January 2009 Additionnally, ordinary requesting routers on enterprise edge interfaces can maintain PA prefix delegations exactly as specified in [RFC3633]. 5.3. IPv6 EBG Discovery EBGs follow the router and prefix discovery procedures specified in ([RFC5214], Section 8.2). They send solicited RAs over VET interfaces for which they are configured as gateways with default router lifetimes, with PIOs that contain PA prefixes for SLAAC, and with any other required options/parameters. EBGs must set the 'M' flag in RAs to 0, since the use of DHCPv6 for address configuration on VET interfaces is undefined. 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 PA 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 EBGs to establish and maintain default routes. In particular the VET node sends SEND-protected unicast RS messages to EBGs over its VET interface(s) to receive SEND-protected RAs. When the VET node receives an RA, it configures a default route based on the Router Lifetime. If the RA contains Prefix Information Options (PIOs) with the 'A' and 'L' bits set to 1, the VET node also autoconfigures IPv6 addresses from the advertised prefixes using SLAAC and assigns them to the VET interface. Thereafter, the VET node accepts packets that are fowarded by EBGs for which it has current default routing information (i.e., ingress filtering is based on the default router relationship rather than a prefix-specific ingress filter entry). 5.4. IPv6 PI Prefix Registration When an EBR discovers EBGs for the enterprise, it must register its PI prefixes by sending SEND-protected RAs to a set of one or more EBGs with Route information Options (RIOs) [RFC4191] that contain the EBR's PI prefixes. Each RA must include the ELA of an EBG as the outer IP destination address and an ISATAP link-local address derived from the ELA as the inner IP destination address. The RAs must also include a CGA link-local inner source address along with a SEND signature that can be used to validate the CGA plus any certificates needed to prove ownership of the PI prefixes. The EBR additionally tracks the set of EBGs that it sends RAs to so that it can send subsequent RAs to the same set. When the EBG receives the RA, it uses SEND to authenticate the Templin Expires July 28, 2009 [Page 15] Internet-Draft VET January 2009 message; if the authentication fails, the EBG discards the RA. Otherwise, the EBG installs the PI prefixes with their respective lifetimes in its Forwarding Information Base (FIB) and configures them for both ingress filtering [RFC3704] and forwarding purposes. In particular, the EBG configures the FIB entries as ingress filter rules to accept packets received on the VET interface with a source address taken from the PI prefixes. It also configures the FIB entries to forward packets received on other interfaces with a destination address taken from the PI prefixes to the EBR that registered the prefixes on the VET interface. The EBG then publishes the PI prefixes in a distributed database (e.g., in a private instance of a routing protocol in which only EBGs participate, via an automated name service update mechanism [RFC3007], etc.). For enterprises that are managed under a cooperative administrative authority, the EBG also makes the PI prefixes available for enterprise-local name service queries [RFC1035]. For VET interfaces configured over enterprises that are managed in a distributed fashion, EBG should instead respond directly to LLMNR [RFC4759] name service queries. To support name service queries, the EBG publishes each /56 prefix taken from the PI prefixes as a seperate FQDN that consists of a sequence of 14 nibbles in reverse order (i.e., the same as in [RFC3596], Section 2.5) followed by the string 'PRLNAME'. For example, when 'PRLNAME' is "isatap.example.com", the EBG publishes the prefix '2001:DB8::/56' as: '0.0.0.0.0.0.8.b.d.0.1.0.0.2.isatap.example.com'. The EBG includes the inner IPv6 CGA source address (e.g., in a DNS AAAA record) and the outer IPv4 source address of the RA (e.g., in a DNS A resource record) in each prefix publication. If the prefix was already installed in the distributed database, the EBG instead adds the outer IPv4 source address (e.g., in an additional DNS AAAA record) to the pre-existing publication. After the EBG authenticates the RA and publishes the PI prefixes, it next acts as an EBR on the VET interfaces configured over any of its provider enterprises and "relays" the RA to the default routers (i.e., EBGs) on those interfaces. The EBR tracks the set of EBGs that it relays the RA to, and should relay subsequent RAs to the same set of EBGs. Each relayed RA is formatted exactly as for the original RA, except that it uses the EBR's own CGA as the inner source address and an ELA taken from the VET interface as the outer IP source address. The RA authentication and PI prefix publication recurses in this fashion and ends when a default mapping service for the interdomain routing core is reached. (In the case of the global Internet interdomain routing core, the 'PRLNAME' for the default mapping service is "isatap.net".) Templin Expires July 28, 2009 [Page 16] Internet-Draft VET January 2009 After the initial PI prefix registration, the EBR that owns the prefix(es) must periodically send additional RAs to its set of EBGs to refresh prefix lifetimes. As long as the EBGs have retained sufficient state from a previous RA authentication as a means for detecting spoofed packets, however, authentication of these "keepalive" RAs is not required. This procedure has a direct analogy in the Teredo method of maintaining state in network middleboxes through the periodic transmission of "bubbles" [RFC4380]. 5.5. IPv6 Next-Hop EBR Discovery VET nodes discover destination-specific next-hop EBRs within the enterprise by either querying the name service for the /56 IPv6 PI prefix taken from a packet's destination address or by forwarding packets via a default route to an EBG. For example, for the IPv6 destination address '2001:DB8:1:2::1' and 'PRLNAME' "isatap.example.com" the VET node can lookup the domain name: '0.0.1.0.0.0.8.b.d.0.1.0.0.2.isatap.example.com'. If the name service lookup succeeds, it will return an IPv6 CGA address (e.g., in a DNS AAAA record) and IPv4 addresses (e.g., in DNS A records) that correspond to the ELAs assigned to enterprise interior interfaces of next-hop EBRs to which the VET node can forward packets. Alternatively, the VET node can simply forward an initial packet via a default route to an EBG. The EBG will forward the packet to a next-hop EBR on the VET interface and return a SEND-protected ICMPv6 Redirect [RFC4861]. If the packet's source address is on-link on the VET interface, the EBG returns an ordinary "router-to-host" redirects with the source address of the packet as 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 previous-hop EBR as its destination. The EBG also includes in the redirect one or more IPv6 Link-Layer Address Options (LLAOs) that contain the IPv4 ELAs of potential next-hop EBRs arranged in order from highest to lowest priority (i.e., the first LLAO contains the highest priority ELA and the final LLAO option contains the lowest priority). The LLAOs are formatted using a modified version of the form specified in ( [RFC2529], Section 5) as shown in Figure 2: +-------+-------+-------+-------+-------+-------+-------+-------+ | Type |Length | TTL | IPv4 Address | +-------+-------+-------+-------+-------+-------+-------+-------+ Figure 2: VET Link-Layer Address Option Format For each LLAO, the Type is set to 2 (for Target Link-Layer Address Templin Expires July 28, 2009 [Page 17] Internet-Draft VET January 2009 Option), Length is set to 1, and IPv4 Address is set to the IPv4 ELA of the next-hop EBR. TTL is set to the time in seconds that the recipient may cache the ELA, where the value 65535 represents infinity and the value 0 suspends forwarding through this ELA. When a VET host receives an ordinay "router-to-host" redirect, it processes the redirect exacly as specified in [RFC4861], Section 8. When an EBR receives a "router-to-router" redirect, it discovers the IPv4 ELA addresses of potential next-hop EBRs by examining the LLAOs included in the redirect. The EBR then installs a FIB entry that contains the /56 prefix of the destination address encoded in the redirect and the list of IPv4 ELAs of potential next-hop EBRs. The EBR then enables the FIB entry for forwarding to next-hop EBRs but DOES NOT enable it for ingress filtering acceptance of packets from next-hop EBRs (i.e., the forwarding determination is unidirectional). The EBR then sends RAs over the VET interface to one or more of the potential next-hop EBRs with a link-local ISATAP address that embeds a next-hop EBR IPv4 ELA as the destination. The RAs must include the EBR's CGA link-local address as the inner IPv6 source address along with a SEND signature. The RAs must also include a Route Information Option (RIO) [RFC4191] that contains the /56 PI prefix of the original packet's source address. When a next-hop EBR receives the RA, it uses SEND to verify the CGA then performs a name service lookup on the prefix in the RIO. If the name service returns the correct CGA and ELA information, the next- hop EBR then installs the prefix in the RIO in its FIB and enables the FIB entry for ingress filtering but DOES NOT enable it for forwarding purposes. After an EBR sends initial RAs following a redirect, it should send periodic RAs to refresh the next-hop EBR's ingress filter prefix lifetimes as long as traffic is flowing. 5.6. Forwarding Packets VET nodes forward packets by consulting the FIB to determine a specific EBR/EBG as the next-hop router on a 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 other than ::/0 available, VET nodes can discover the next-hop EBR/EBG through the mechanisms specified in Section 5.3 and 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 Templin Expires July 28, 2009 [Page 18] Internet-Draft VET January 2009 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 (i.e., the IPv4 ELA of the next-hop EBR) 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 there are multiple candidate destination ELAs available, the VET node should only select an ELA for which there is current forwarding information in the outer IP protocol FIB. 5.7. SEAL Encapsulation VET nodes that do not use IPsec encapsulation should use SEAL encapsulation [I-D.templin-seal] in conjunction with packet forwarding over VET interfaces to accommdate path MTU diversity, to detect source address spoofing, and to monitor next-hop EBR reachability. SEAL encapsulation maintains a unidirectional and monotonically-incrementing per-packet identification value known as the 'SEAL_ID'. When a VET node that uses SEAL encapsulation sends a SEND-protected Router Advertisement (RA) or Router Solicitation (RS) message to another VET node, both nodes cache the new SEAL_ID as per- tunnel state used for maintaining a window of unacknowledged SEAL_IDs. 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 examining the SEAL_ID along with source and destination addresses, etc. Additionally, a next-hop EBR can track the SEAL_ID 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. In terms of next-hop reachability, an EBR can set the SEAL "Acknowledgement Requested" bit in messages to receive confirmation that a next-hop EBR is reachable. Setting the "Acknowledgement Requested" bit is also used as the method for maintaining the window of outstanding SEAL_ID's. 5.8. Generating Errors When an EBR receives a packet over a VET interface and there is no matching ingress filter entry, it drops the packet and returns an ICMPv6 [RFC4443] "Destination Unreachable; Source address failed Templin Expires July 28, 2009 [Page 19] Internet-Draft VET January 2009 ingress/egress policy" message to the previous hop EBR subject to rate limiting. When an EBR receives a packet over a VET interface, and there is no longest-prefix-match FIB entry for the destination, it returns an ICMPv6 "Destination Unreachable; No route to destination" message to the previous hop EBR subject to rate limiting. When an EBR receives a packet over a VET interface and the longest- prefix-match FIB entry for the destination is configured over the same VET interface the packet arrived on, the EBR forwards the packet then (if the FIB prefix is longer than ::/0) sends a SEND-protected router-to-router ICMPv6 Redirect message to the previous hop EBR as specified in Section 5.5. Generation of other ICMPv6 messages (e.g., ICMPv6 "Packet Too Big") is the same as for any IPv6 interface. 5.9. Processing Errors When an EBR receives an ICMPv6 "Destination Unreachable; Source address failed ingress/egress policy" message from a next-hop EBR, and there is a longest-prefix-match FIB entry for the original packet's destination that is more-specific than ::/0, the EBR discards the message and marks the FIB entry for the destination as "forwarding suspended" for the ELA taken from the source address of the ICMPv6 message. The EBR should then allow subsequent packets to flow through different ELAs associated with the FIB entry until it forwards a new SEND-protected RA to the suspended ELA. If the EBR receives excessive ICMPv6 ingress policy errors through multiple ELAs associated with the same FIB entry, it should delete the FIB entry and allow subsequent packets to flow through an EBG. When a VET node receives an ICMPv6 "Destination Unreachable; No route to destination" message from a next-hop EBR, it forwards the ICMPv6 message to the source of the original packet as normal. If the EBR has longest-prefix-match FIB entry for the original packet's destination that is more-specific than ::/0, the EBR also deletes the FIB entry. When an EBR receives an ICMPv6 Redirect with a valid SEND signature, it processes the packet as specified in Section 5.5. When an EBG receives new mapping information for a specific destination prefix, it can propagate the update to other EBRs/EBGs by sending an ICMPv6 redirect message to the 'All Routers' link-local multicast address with a LLAO with the TTL for the unreachable LLAO set to zero, and with a NULL packet in error. Templin Expires July 28, 2009 [Page 20] Internet-Draft VET January 2009 Additionally, a VET node may receive ICMPv4 [RFC0792] "Destination Unreachable; net / host unreachable" messages from an EIR indicating that the path to a VET neighbor may be failing. The EBR should first check identifying information in the message (e.g., the SEAL_ID, IPsec sequence number, source address of the original packet if available, etc.) before accepting it, then should mark the longest- prefix-match FIB entry for the destination as "forwarding suspended" for the ELA destination address of the ICMPv4 packet-in-error. If the EBR receives excessive ICMPv4 unreachable errors through multiple ELAs associated with the same FIB entry, it should delete the FIB entry and allow subsequent packets to flow through a different route. 5.10. Mobility and Multihoming Considerations EBRs can retain their PI prefixes as they travel between distinct enterprise networks as long as they register the prefixes with new EBGs and (preferrably) withdraw the prefixes from old EBGs prior to departure. Prefix registration with new EBGs is coordinated exactly as specified in Section 5.4; prefix withdrawl from old EBGs is simply through re-announcing the PI prefixes with zero lifetimes. Since EBRs can move about independently of one another, stale FIB entry state may be left in VET nodes when a neighboring EBR departs. Additionally, EBRs can lose state for various reasons, e.g., power failure, machine reboot, etc. For this reason, EBRs are advised to set relatively short PI prefix lifetimes in RIO options, and to send additional RAs to refresh lifetimes before they expire. (EBRs should place conservative limits on the RAs they send to reduce congestion, however.) EBRs may register their PI prefixes with multiple EBGs for multihoming purposes. EBRs should only forward packets via EBGs with which it has registered its PI prefixes, since other EBGs may drop the packets and return ICMPv6 "Destination Unreachable; Source address failed ingress/egress policy" messages. EBRs can also act as delegating routers to sub-delegate portions of their PI 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 PI prefixes become the PA prefixes for downstream-dependent nodes. Downstream- dependent nodes that travel with a mobile provider EBR can continue to use addresses configured from PA prefixes; downstream-dependent nodes that move away from their provider EBR must perform address/ prefix renumbering when they assocate with a new provider. The EBGs of a multi-homed enterprise should participate in a private inner IP routing protocol instance between themselves (possibly over Templin Expires July 28, 2009 [Page 21] Internet-Draft VET January 2009 an alternate topology) to accommodate enterprise partitions/merges as well as intra-enterprise mobility events. These peer EBGs should accept packets from one another without respect to the destination (i.e., ingress filtering is based on the peering relationship rather than a prefix-specific ingress filter entry). 5.11. 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 encapsulation. 5.12. Multicast In multicast-capable deployments, EIRs provide an enterprise-wide multicasting service (e.g., Simplified Multicast Forwarding (SMF) [I-D.ietf-manet-smf], PIM routing, DVMRP routing, etc.) 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 nodes 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. In that case, operation of link- or greater scoped inner IP multicasting services (e.g., a link-scoped neighbor discovery protocol) over the VET interface is available, but link- scoped services should be used sparingly to minimize enterprise-wide flooding. VET nodes 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 protocols (respectively), [RFC2529] provides mappings from the IPv6 multicast address space to a site-scoped IPv4 multicast address space (for other IP-in-IP encapsulations, mappings are established through administrative configuration or through an unspecified alternate method). Multicast forwarding for inner IP multicast groups over outer IP multicast groups can be accommodated, e.g. through VET interface snooping of inner multicast group membership and routing protocol control messages. To support inner-to-outer IP multicast forwarding, VET interface acts as a virtual outer IP multicast host connected to its underlying enterprise-interior interfaces. When the VET Templin Expires July 28, 2009 [Page 22] Internet-Draft VET January 2009 interface detects inner IP multicast group joins or leaves, it forwards corresponding outer IP multicast group membership reports for each enterprise-interior interface over which the VET interface is configured. If the VET node is configured as an outer IP multicast router on the underlying enterprise-interior interfaces, the VET interface forwards locally looped-back group membership reports to the outer IP multicast routing process. If the VET node is configued as a simple outer IP multicast host, the VET interface instead fowards actual group membership reports (e.g., IGMP messages) directly over each of the underlying enterprise-interior interfaces. Since inner IP multicast groups are mapped to site-scoped outer IP multicast groups, the VET node must ensure that the site-scope outer IP multicast messages received on the enterprise-interior interfaces for one VET interface do not "leak over" to the enterprise-interior interfaces of another VET interface. This is accomodated through normal site-scoped outer IP multicast group filtering at enterprise- interior interface boundaries. 5.13. Service Discovery VET nodes 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. 5.14. 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 'PRLNAME' (e.g., 'isatap.zone1.example.com', 'isatap.zone2.example.com', etc.). EBGs can logically partition an enterprise using a single VET interface by sending RAs with PIOs containing different IPv6 PA prefixes to group nodes into different logical partitions. EBGs can identify partitions, e.g., by examining IPv4 ELA prefixes, observing the interfaces over which RSs are received, etc. In that case, a single 'PRLNAME' can cover all partitions. 6. IANA Considerations A Site-Local Scope IPv4 multicast group ('All_DHCPv4_Servers') for DHCPv4 server discovery is requested. The allocation should be taken Templin Expires July 28, 2009 [Page 23] Internet-Draft VET January 2009 from the 239.255.000.000-239.255.255.255 Site-Local Scope range in the IANA 'multicast-addresses' registry. 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) in conjunction with the ingress filtering mechanisms specified in this document. SEND [RFC3971] and SEAL Section 5.7 provide additional securing mitigations to detect source address spoofing and bogus RA messages sent by rogue routers. Rogue routers can send bogus RA messages with spoofed ELA source addresses that can consume network resources and cause EBGs to perform extra work. Nonetheless, EBGs should not "blacklist" such ELAs, as that may result in a denial of service to the ELAs' legitimate owners. 8. Related Work Brian Carpenter and Cyndi Jung introduced the concept of intra-site automatic tunneling in [RFC2529]; this concept was later called: "Virtual Ethernet" and investigated by Quang Nguyen under the guidance of Dr. Lixia Zhang. Subsequent works by these authors and their colleagues have motivated a number of foundational concepts on which this work is based. Telcordia has proposed DHCP-related solutions for MANETs through the CECOM MOSAIC program. The Naval Research Lab (NRL) Information Technology Division uses DHCP in their MANET research testbeds. [I-D.ietf-v6ops-tunnel-security-concerns] discusses security concerns pertaining to tunneling mechanisms. An automated IPv4 prefix delegation mechanism is proposed in [I-D.ietf-dhc-subnet-alloc]. MANET link types are discussed in [I-D.clausen-manet-linktype]. Templin Expires July 28, 2009 [Page 24] Internet-Draft VET January 2009 Various proposals within the IETF have suggested similar mechanisms. 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, Thomas Goff, Joel Halpern, Bob Hinden, Sapumal Jayatissa, Dan Jen, Darrel Lewis, Tony Li, Joe Macker, David Meyer, Thomas Narten, Pekka Nikander, 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. 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. [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, 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", Templin Expires July 28, 2009 [Page 25] Internet-Draft VET January 2009 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. [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC 4443, March 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. Templin Expires July 28, 2009 [Page 26] Internet-Draft VET January 2009 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. [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.jen-apt] Jen, D., Meisel, M., Massey, D., Wang, L., Zhang, B., and L. Zhang, "APT: A Practical Transit Mapping Service", draft-jen-apt-01 (work in progress), November 2007. [I-D.templin-seal] Templin, F., "The Subnetwork Encapsulation and Adaptation Templin Expires July 28, 2009 [Page 27] Internet-Draft VET January 2009 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. [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 Templin Expires July 28, 2009 [Page 28] Internet-Draft VET January 2009 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. [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Network Address Translations (NATs)", RFC 4380, February 2006. [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 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). 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. Templin Expires July 28, 2009 [Page 29] Internet-Draft VET January 2009 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 -28 to 29: o Updates on processing/receiving errors. Changes from -27 to 28: o Introduced concept of a default mapper. Changes from -26 to 27: o Introduced new model for PI prefix management. o Teredo mechanisms used in conjunction with ISATAP ("teratap"? "isado"?) 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 28, 2009 [Page 30] 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 28, 2009 [Page 31] 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 28, 2009 [Page 32] 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 28, 2009 [Page 33] 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 28, 2009 [Page 34]