Network Working Group F. Templin, Ed. Internet-Draft Boeing Phantom Works Intended status: Informational November 17, 2008 Expires: May 21, 2009 Routing and Addressing in Next-Generation EnteRprises (RANGER) draft-templin-ranger-04.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 21, 2009. Abstract Enterprise networks will require support for both Internet protocol versions (IPv4 and IPv6) for an indeterminant period; perhaps even indefinitely. This is particularly true for existing enterprise networks that must introduce IPv6 without disruption of IPv4 services, but the same principles apply even for clean-slate deployments in new enterprises. Next-generation enterprises therefore require an architected solution for coordination of their internal routing and addressing plans for both IPv6 and IPv4. The RANGER architecture addresses these requirements. Templin Expires May 21, 2009 [Page 1] Internet-Draft RANGER November 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. The RANGER Architecture . . . . . . . . . . . . . . . . . . . 6 3.1. The Enterprise-within-Enterprise Framework . . . . . . . . 6 3.2. Virtual Enterprise Traversal (VET) . . . . . . . . . . . . 8 3.3. Support for IPv4 Services . . . . . . . . . . . . . . . . 12 3.4. Subnetwork Encapsulation and Adaptation Layer (SEAL) . . . 13 3.5. Mobility Management . . . . . . . . . . . . . . . . . . . 14 4. Initiatives Related to RANGER/VET/SEAL . . . . . . . . . . . . 14 4.1. 6over4 and ISATAP . . . . . . . . . . . . . . . . . . . . 14 4.2. The Locator Identifier Split Protocol (LISP) . . . . . . . 14 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 8.1. Normative References . . . . . . . . . . . . . . . . . . . 16 8.2. Informative References . . . . . . . . . . . . . . . . . . 16 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 18 Intellectual Property and Copyright Statements . . . . . . . . . . 19 Templin Expires May 21, 2009 [Page 2] Internet-Draft RANGER November 2008 1. Introduction Enterprise networks will require support for both Internet protocol versions (IPv4 and IPv6) for an indeterminant period; perhaps even indefinitely. This is particularly true for existing enterprise networks that must introduce IPv6 without disruption of IPv4 services, but the same principles apply even for clean-slate deployments in new enterprises. Next-generation enterprises therefore require an architected solution for coordination of their internal routing and addressing plans for both IPv6 and IPv4. The RANGER architecture addresses these requirements, and provides a framework for IPv6/IPv4 coexistence [I-D.arkko-townsley-coexistence]. RANGER is a scalable architecture for routing and addressing in next- generation enterprise networks that may either comprise a single interior IPv4 addressing domain or contain multiple disjoint interior IPv4 addressing domains. Each of these domains may coordinate their own internal addressing plans independently of one another such that limited-scope addresses (e.g., [RFC1918] private-use IPv4 addresses) may be reused with impunity to provide unlimited scaling through spatial reuse. Each addressing domain therefore appears as an enterprise unto itself, such that a model of recursively nested "enterprises-within-enterprises" is enabled. Logical or physical partitioning of an enterprise into multiple sites is also possible and beneficial in many scenarios. Without an architected approach, routing and addressing within such a framework would be fragmented due to limited-scope address/prefix reuse between disjoint addressing domains. However, the enterprise can be unified via a virtual overlay architecture mainfested by automatic tunneling over disjoint domains interconnected via border routers. RANGER provides an architecture for operation of virtual overlay networks within a diverse range of enterprise network scenarios, as outlined in the following sections. While RANGER discusses the specific instance of IPv6 as a virtual overlay over or IPv4 networks, it is important to note that the same architectural principles apply to any combination of IP* within IP* virtual overlays. The RANGER architecture uses many mechanisms already documented or proposed in the IRTF and IETF. Technical details of the composite technologies that make up the architecture are found in the Virtual Enterprise Traversal (VET) specification [I-D.templin-autoconf-dhcp]. The RANGER architectural principles can be either directly or indirectly traced to the deliberations of the ROAD group in January 1992 [RFC1380], and also to still earlier works including NIMROD Templin Expires May 21, 2009 [Page 3] Internet-Draft RANGER November 2008 [RFC1753], the Catenet model for internetworking [CATENET][IEN48] [RFC2775], and many others. [RFC1955] [RFC1955] captures the high- level architectural aspects of the ROAD group deliberations in a "New Scheme for Internet Routing and Addressing [ENCAPS] for IPNG". 2. Terminology commons a routing region within an enterprise that provides a subnetwork for cooperative peering between the border routers of diverse organizations that may have competing interests. A prime example of a commons is the Default Free Zone (DFZ) of the global Internet. enterprise the same as defined in [RFC4852], where the enterprise deploys a unified IPv4 routing and addressing plan within the commons, but may contain many disjoint interior addressing domains and/or organizational groupings that can be considered as enterprises unto themselves. An enterprise therefore need not be "one big happy family", but instead provides a commons for the cooperative interconnection of diverse organizations that may have competing interests (e.g., such as the case within the global Internet default free zone). Enterprise networks are typically associated with large corporations or academic campuses, however the RANGER architectural principles apply to any network that has some degree of cooperative active management. This definition can therefore be extended to home networks, small office networks, a wide variety of mobile ad-hoc networks (MANETs), and even to the global Internet itself. site a logical and/or physical grouping of interfaces within a unified IPv4 addressing region of an enterprise, where the topology of the site is a proper subset of the topology of the enterprise. A site may contain many interior sites, which may themselves contain many interior sites in a recursive fashion. Throughout the remainder of this document, the term "enterprise" refers to either enterprise or site, i.e., the RANGER principles apply equally to enterprises and sites of any size or shape. At the lowest level of decomposition, a singleton Border Router can be considered as an enterprise unto itself. Templin Expires May 21, 2009 [Page 4] Internet-Draft RANGER November 2008 Border Router (BR) an IPv6/IPv4 dual-stack node at the edge of an enterprise and that is also configured as an IPv6 router in an overlay network. BRs connect their directly-attached IPv6 networks to the overlay network, and connect to other IPv6 networks via IPv6-in-IPv4 tunneling across the commons to other BRs. Border Gateway (BG) a BR that also connects the enterprise to provider networks and/or to the global Internet. BGs are typically configured as default IPv6 routers, and provide forwarding services for accessing IPv6 networks not reachable via a BR within the commons. overlay network a virtual network manifested by IPv6 routing and addressing over virtual links formed through automatic IPv6-in-IPv4 tunneling. An IPv6 overlay network may span many underlying IPv4 enterprises. 6over4 Transmission of IPv6 over IPv4 Domains without Explicit Tunnels [RFC2529]; functional specifications and operational practices for automatic tunneling of unicast/multicast IPv6 packets over multicast-capable IPv4 enterprises. ISATAP Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) [RFC5214]; functional specifications and operational practices for automatic tunneling of unicast IPv6 packets over unicast-only IPv4 enterprises. VET Virtual Enterprise Traversal (VET) [I-D.templin-autoconf-dhcp]; functional specifications and operational practices that provide a functional superset of 6over4 and ISATAP. In addition to both unicast and multicast tunneling, VET also supports address/prefix autoconfiguration as well as additional encapsulations such as IPSec, SEAL, LISP, etc. SEAL Subnetwork Encapsulation and Adaptation Layer (SEAL) [I-D.templin-seal]; a functional specification for robust and authenticated path MTU assurance over IPv6-in-IPv4 tunnels. Also provides authentication for other ICMP error messages, and adapts to subnetworks configured over links with diverse characteristics. Templin Expires May 21, 2009 [Page 5] Internet-Draft RANGER November 2008 3. The RANGER Architecture The RANGER architecture enables scalable IPv6 routing and addressing in next-generation enterprise networks, while sustaining support for legacy IPv4 networks and services. Key to this approach is a framework that accommodates interconnection of diverse organizations within the enterprise with a mutual spirit of cooperation, but with the potential for competing interests. The following sections outline the RANGER architecture within the context of anticipated use cases: 3.1. The Enterprise-within-Enterprise Framework Enterprise networks traditionally distribute routing information via Interior Gateway Protocols (IGPs) such as Open Shortest Path First (OSPF), while large enterprises may even use an Exterior Gateway Protocol (EGP) internally in place of an IGP. In particular, it is becoming increasingly commonplace for large enterprises to use the Border Gateway Protocol (BGP) internally and independently from the BGP instance that maintains the routing information base within the global Internet Default Free Zone (DFZ). As such, large enterprises may run an internal instance of BGP across many internal Autonomous Systems (ASs). Such a large enterprise can therefore appear as an Internet unto itself, albeit with default routes leading to the true global Internet. Additionally, each internal AS within such an enterprise may itself run BGP internally in place of an IGP, and can therefore also appear as an independent enterprise unto itself. This enterprise-within-enterprise framework can be extended in an hierarchical fashion as broadly and as deeply as desired to acheive scaling factors as well as organizational and/or functional compartmentalization, as shown in Figure 1. Templin Expires May 21, 2009 [Page 6] Internet-Draft RANGER November 2008 ,---------------. ,-' Global `-. <--------+ ( IPv6/IPv4 ) ,----|-----. `-. Internet ,-' ( Enterprises) `+--+..+--+ ...+--+ ( E2 thru EN ) _.-|R1|--|R2+----|Rn|-._ `.---------/ _.---'' +--+ +--+ ...+--+ -. ,--'' ,---. `---. ,-' X5 X6 .---.. `-. ,' ,.X1-.. / \ ,' `. `. ,' ,' `. .' E1.2 '. X8 E1.m \ `. / / \ | ,--. | / _,.._ \ \ / / E1.1 \ | Y3 `. | | / Y7 | \ ; | ___ | | ` W Y4 |... | `Y6 ,' | : | | ,-' `. X2 | `--' | | `'' | | : | | V Y2 | \ _ / | | ; \ | `-Y1,,' | \ .' Y5 / \ ,-Y8'`- / / \ \ / \ \_' / X9 `. ,'/ / `. \ X3 `.__,,' `._ Y9'',' ,' ` `._ _,' ___.......X7_ `---' ,' ` `---' ,-' `-. -' `---. `. E1.3 Z _' _.--' `-----. \---.......---' _.---'' `----------------'' <---------------- Enterprise E1 ----------------> Figure 1: Enterprise-within-Enterprise Framework Figure 1 depicts an enterprise 'E1' connected to the global IPv6/IPv4 Internet via routers 'R1' through 'Rn' and additional enterprises 'E2' through 'EN' that also connect to the global Internet. Within the 'E1' commons, there may be arbitrarily-many IPv4 hosts, routers and networks (not shown in the diagram) over which IPv4 packets can be forwarded and IPv6 packets can be tunneled. There may also be many internal enterprises 'E1.1' through 'E1.m' (shown in the diagram) that interconnect within the 'E1' commons via Border Routers (BRs) depicted as 'X1' through 'X9' (where 'X1' through 'X9' see 'R1' through 'Rn' as Border Gateways (BGs)). Within each 'E1.*' enterprise, there may also be arbitrarily-many IPv4 networks/nodes as well as lower layer enterprises that interconnect within the 'E1.*' commons via BRs depicted as 'Y1' through 'Y9' in the diagram (where 'Y1' through 'Y9' see 'X1' through 'X9' as BGs). This hierarchical decomposition can be recursively nested as deeply as desired, and ultimately terminates at singleton IPv6/IPv4 dual-stack systems such as those depicted as 'V', 'W' and 'Z' in the diagram. It is important to note that dual-stack systems such as 'V', 'W' and Templin Expires May 21, 2009 [Page 7] Internet-Draft RANGER November 2008 'Z' may be simple IPv6/IPv4 hosts, or they may be BRs that attach arbitrarily-complex IPv6-only edge networks. Such IPv6-only edge networks could be as simple as a home network behind a residential gateway, or as complex as a major corporate/academic campus, a large service provider network, etc. Again, this enterprise-within-enterprise framework can be recursively nested as broadly and deeply as desired. From the ultimate level of the hierarchy, consider now that the global Internet itself can be viewed as an "enterprise" that interconnects E1 through EN such that all RANGER architectural principles apply equally within the global Internet context. As a specific case in point, the future global Aeronautical Telecommuncations Network (ATN) under development within the civil aviation industry [I-D.bauer-mext-aero-topology] will take the form of a large enterprise network that appears as an Internet unto itself, i.e., exactly as depicted for 'E1' in Figure 1. Within the ATN, there will be many Air Communications Service Provider (ACSP) and Air Navigation Service Provider (ANSP) networks organized as autonomous systems internal to the ATN, i.e., exactly as depicted for 'E1.*' in the diagram. The ACSP/ANSP network BGs will participate in a BGP instance internal to the ATN, and may themselves run independent BGP instances internally and be further sub-divided into enterprises organized as regional, organizational, functional, etc. compartments. It is important to note that, while ACSPs/ANSPs within the ATN share a common objective of safety-of-flight for civil aviation services, there may be competing business/social/political interests between them such that the ATN is not necessarily "one big happy family". Therefore, the model parallels that of the global Internet itself. Such an operational framework may indeed be the case for many next- generation enterprises. In particular, although the inner-workings of all enterprises will require a mutual level of cooperative active management at a certain level, free market forces, business objectives, political alliances, etc. may drive internal competition. 3.2. Virtual Enterprise Traversal (VET) Within the enterprise-within-enterprise framework outlined in Section 3.1, the RANGER architecture is based on an overlay network approach manifested through Virtual Enterprise Traversal (VET) [I-D.templin-autoconf-dhcp]. The approach uses automatic IPv6-in- IPv4 tunneling within a hierarchy of child enterprises that are either configured within the same addressing region of a larger enterprise or use their own enterprise-local IPv4 routing and addressing internally. These logically and/or physically disjoint Templin Expires May 21, 2009 [Page 8] Internet-Draft RANGER November 2008 child enterprises are "glued together" by IPv6 BRs/BGs, with each BR requesting an IPv6 prefix delegation from a delegating BG. Additionally, fault tolerance and multihoming is naturally afforded through configuration of multiple BGs per child enterprise. Figure 2 below depits a vertical slice (albeit represented horizontally) from the enterprise-within-enterprise framework shown in Figure 1, where an IPv6 host 'H' that is deeply nested within Enterprise 'E1' connects to IPv6 server 'S1' located somewhere on the IPv6 Internet: +------+ | IPv6 | |Server| " " " " " " " "" " " " " " " " " " " " " " " " | S1 | " 2001:DB8:0:0::/56 *:0::/48 *:0::/40 " +--+---+ " . . . . . . . . . . . . . . . " | " . . . . . . " | " . +----+ v +--- + v +----+ v +----+ +-----+-------+ " . | V += e =+ Y1 += e =+ X2 += e =+ R2 +==+ Internet | " . +-+--+ t +----+ t +----+ t +----+ +-----+-------+ " . | 1 . . 2 . . 3 . " | " . H . . . . . " | " . . . . . . . . . . . . . . " +--+---+ " " | IPv4 | " 10/8 10/8 10/8 " |Server| " " " " " " " " " " " " " " "" " " " " " " " | S2 | <-- Enterprise E1 --> +------+ Figure 2: Virutal Enterprise Traversal within the RANGER Architecture Within this vertical slice, Figure 2 depicts each enterprise within the 'E1' hierarchy as spanned by automatic IPv6-in-IPv4 tunnels 'vet1' through 'vet3' manifested through Virtual Enterprise Traversal (VET) [I-D.templin-autoconf-dhcp]. Each 'vet*' interface within this framework is Non-Broadcast, Multiple Access (NBMA), and connects all BRs within the same enterprise. Each enterprise within the 'E1' hierarchy may comprise a smaller topological region within a larger IPv4 routing region, or they may configure an independent routing and addressing plan from a common (but spatially reused) limited-scope IPv4 prefix, e.g., depicted as '10/8' in the diagram. The BR for each 'E1*' enterprise receives an IPv6 prefix delegation from a delegating BG, depicted above as sub-delegations of the prefix '2001: DB8::/40'. VET specifies the necessary mechanisms and operational practices to manifest the RANGER architecture in a wide range of use cases such as in the example above. The use of VET in conjunction with the Subnetwork Encapsulation and Adaptation Layer (SEAL - see: Templin Expires May 21, 2009 [Page 9] Internet-Draft RANGER November 2008 Section 3.4) may also be essential in certain deployments to avoid issues related to ICMP spoofing and tunnel encapsulation overhead. VET allows 'V', 'Y1', 'X2' and 'R2' to configure separate 'vet*' interfaces for each enterprise they connect to, and to discover BGs through a static name service resolution (or, mapping) as specified in [I-D.templin-autoconf-dhcp]. After tunnels 'vet1' through 'vet3' are established and BG's discovered, the BRs connected to a 'vet*' interface can run an IPv6 routing protocol such as OSPVFv3 [RFC5340] and form adjacencies between themselves in an on-demand fashion while treating the 'vet*' interface as an ordinary IPv6 link. It is important to note that adjacencies can be formed on-demand and allowed to expire after idle periods such that a full mesh of links need not be maintained. This allows an IPv6 overlay network that spans 'E1' to dynamically adapt to changing conditions within the enterprise. In the example shown in Figure 2, a simple IPv6 host 'H' is attached to a shared link with IPv6/IPv4 dual stack node 'V'. IPv6 host 'H' uses standard IPv6 neighbor discovery mechanisms to discover 'V' as a default IPv6 router that can forward its packets off the local link, while 'V' sees node 'Y1' as a BG that can be reached via 'vet1' and that can forward packets toward IPv6 server 'S1'. Similarly, node 'Y1' is a BR for the enterprise spanned by 'vet2' that sees 'X2' as a BG, and node 'X2' is a BR for 'vet3' that sees 'R2' as a BG that connects 'E1' to the global IPv6 Internet. In a second example, Figure 3 depicts an instance of on-demand discovery of more-specific routes in which an IPv6 host 'H' connects to an IPv6 server 'J' located in a different organizational entity within 'E1': Templin Expires May 21, 2009 [Page 10] Internet-Draft RANGER November 2008 +------+ | IPv6 | |Server| " " " " " " " "" " " " " " " " " " " " " " " " | S1 | " 2001:DB8:0:0::/56 *0:0::/48 *0:0::/40 " +--+---+ " . . . . . . . . . . . . . . . " | " . . . . . . " | " . +----+ v +----+ v +----+ +----+ +-----+-------+ " . | V += e =+ Y1 += e =+ X2 += =+ R2 +==+ Internet | " . +-+--+ t +----+ t +----+ +----+ +-----+-------+ " . | 1 . . 2 . . . " | " . H . . . . v . " | " . . . . . . . . . . . e . " +--+---+ " . t . " | IPv4 | " . . . . . . , . 3 . " |Server| " . +----+ v +----+ . " | S2 | " . | Z += e =+ X7 += . " +------+ " . +-+--+ t +----+ . " " . | 4 . . . " " . J . . . . . " " . . . . . . . " " 2001:DB8:1:0::/56 *1:0::/40 " " " " " " " " " " " " " " " "" " " " " " " " <-- Enterprise E1 --> Figure 3: On-Demand Discovery within the RANGER Architecture In this scenario, tunnel interfaces 'vet1' through 'vet4' as well as IPv6 prefix delegations have been established through the enterprise autoconfiguration procedures specified in [I-D.templin-autoconf-dhcp]. When IPv6 host 'H' sends IPv6 packets to server 'J', however, unless IPv6 routing information is available BR 'X2' must determine that 'J' can be reached using a more direct route via 'X7' across the 'E1' commons. To do so, 'X2' can perform an on-demand mapping lookup by consulting the enterprise name service as specified in[I-D.templin-autoconf-dhcp]. Alternatively, 'X2' can send the packet to default router 'R2', and 'R2' can return an ICMPv6 redirect message indicating that 'J' can be reached via a more direct route through 'X7'. It is specifically worth noting that, in both of the previous examples, a BR may have potentially many VET interfaces over which it can connect to the BRs/BGs of potentially many neighboring enterprises across the commons. Templin Expires May 21, 2009 [Page 11] Internet-Draft RANGER November 2008 3.3. Support for IPv4 Services While the IPv6 overlay network that spans 'E1' provides a fully- connected routing and addressing capability for IPv6 services, access to legacy IPv4 services will still be required for an extended (and possibly indefinite) period. Figure 4 below depicts the applicable IPv4 service access models for the RANGER architecture: +------+ | IPv6 | |Server| " " " " " " " "" " " " " " " " " " " " " " " " | S1 | " 2001:DB8:0:0::/56 *:0::/48 *:0::/40 " +--+---+ " . . . . . . . . . . . . . . . " | " . . . . . . " | " . +----+ v +--- + v +----+ v +----+ +-----+-------+ " . | V += e =+ Y1 += e =+ X2 += e =+ R2 +==+ Internet | " . +----+ t +----+ t +----+ t +----+ +-----+-------+ " . 1 . . 2 . . 3 . " | " . K L . . . . M . " | " . . . . . . . . . . . . . . " +--+---+ " " | IPv4 | " " |Server| " " " " " " " " " " " " " " "" " " " " " " " | S2 | <-- Enterprise E1 --> +------+ Figure 4: IPv4 Service Access in the RANGER Architecture In a first instance, an IPv4 client 'K' within enterprise 'E1.1.1' can access IPv4 service 'L' within the same enterprise as-normal and without the need for any IPv6-in-IPv4 encapsulation. Instead, a "mapping" is done through a simple name lookup within the enterprise- local name service deployed in 'E1.1.1', and enterprise-local native IPv4 services are used. In many instances, this may indeed be the preferred service access model even when IPv6 services are widely deployed due to factors such as inability to replace legacy IPv4 applications, IPv6 header overhead avoidance, etc. In a second instance, IPv4 client 'K' can access IPv4 server 'S2' on the global IPv4 Internet in a number of ways. First, if the recursively nested enterprises are all configured within the same IPv4 routing region within E1, 'K' can simply forward its packets toward 'R2' that acts as an IPv4 Network Address Translator (NAT) and/or an ordinary IPv4 enterprise border router. Secondly, if the recursively nested enterprises are configured within disjoint IPv4 routing regions, all routers 'Y1', 'X2' and 'R2' can provide an IPv4 NAT capability however this approach requires multiple instances of stateful NAT devices on the path which can lead to an overall degree Templin Expires May 21, 2009 [Page 12] Internet-Draft RANGER November 2008 of brittleness and intolerance to routing changes. Instead, 'E1' could deploy a "Carrier-Grade NAT (CGN)" at 'R2' (i.e., at the enterprise border with the global Internet) and E1.1.1 could discover 'Y1' as an IPv4 default router. 'Y1' could then use the "dual-stack- lite" approach in which it uses IPv4-in-IPv6-in-IPv4 tunneling to convey the IPv4 packets from 'K' to the CGN at 'R2', which then decapsulates and translates the inner IPv4 packets before sending them on to 'S2'. Finally, 'K' could be configured as an IPv6-only node and use standard IPv6 routing to reach an IPv6/IPv4 translator located at an IPv6 BR for the enterprise in which 'S2' resides'. The translator would then use IPv6-to-IPv4 translation before sending packets onwards toward 'S2'. These and other alternatives are discussed in [I-D.wing-nat-pt-replacement-comparison]. In a final instance, IPv4 client 'K' can access an IPv4 server 'M' in a different enterprise within E1 as long as both enterprises are configured over the same underlying IPv4 routing region. If the enterprises are configured over disjoint IPv4 routing regions, however, to K' would only be able to access 'M' using IPv6-only services. 3.4. Subnetwork Encapsulation and Adaptation Layer (SEAL) Whenever the BRs of disjoint enterprises are joined across a commons, mechanisms that rely on ICMP feedback from routers within the network may become brittle or susceptible to spoofing attacks. This is due to the fact that ICMP messages can be lost due to congestion or packet filtering gateways, and that network middleboxes are essentially "anonymous" and may include insufficient information in ICMPs that can be used to authenticate their source. ICMP messages can therefore be forged by anonymous attackers, e.g., from a rogue node within an enterprise that has malicious intent toward another enterprise. The Subnetwork Encapsulation and Encapsulation Layer (SEAL) provides effective means for BRs to avoid these shortcomings by accepting only authenticated feedback from correspondent BRs that can be validated as topologically-correct routers within the commons (i.e., the subnetwork) using the Potential Router List (PRL) discovery mechanisms of [I-D.templin-autoconf-dhcp]. Moreover, SEAL does not require reliable delivery of all ICMPs, but rather supports continued operation even if some/many ICMPs are lost. Finally, SEAL adapts to subnetworks that contain links with diverse bandwidth and MTU size properties, and indeed allows for discovery and eradication of marginal links. The advantages of using SEAL within the RANGER enterprise-within- enterprise framework are tangible, and compare favorably with the Templin Expires May 21, 2009 [Page 13] Internet-Draft RANGER November 2008 alternative of deploying an all-IPv6 infrastructure even for clean- slate deployments. This is especially true within enterprises that provide a commons for joining organizational/political/functional entities with a spirit of mutual cooperation but with competing interests or objectives. 3.5. Mobility Management When a mobile IPv6 node within an enterprise network moves to a new IPv6 link, it can use mobility management mechanisms such as Mobile IPv6 [RFC3775] or HIP [RFC4423] to maintain a stable identifier even as it moves between foreign links. When a mobile BR moves to a new enterprise, it can renumber its IPv4 address(es) (i.e., its locators) and communicate these changes to peers using a mechanism such as MobIKE [RFC4555], dynaic updates to the DNS, etc. In that case, it can still retain its IPv6 addresses and/or prefixes without need for renumbering. This approach is especially useful for maintaining continuity for the provider- independent IPv6 prefixes owned by the BR. 4. Initiatives Related to RANGER/VET/SEAL 4.1. 6over4 and ISATAP Long before the RANGER architecture and VET/SEAL specifications were published, 6over4 [RFC2529] specified a means for automatic tunneling of unicast/multicast IPv6 packets over multicast-capable IPv4 enterprises, however it was unable to function in enterprises that did not support a full deployment of IPv4 multicast services. To address these shortcomings, ISATAP (a unicast-only variant of 6over4) [RFC5214] was specified and widely implemented among major software and equipment vendor products. ISATAP provides unicast-only neighbor discovery mechanisms and also adds a means for determining whether a node on an ISATAP interface is authorized to act as an IPv6 router; namely, the Potential Router List (PRL). VET provides a functional superset of the 6over4 and ISATAP mechanisms; VET further combines with SEAL to provide the functional elements of the RANGER architecture. 4.2. The Locator Identifier Split Protocol (LISP) The Locator-Identifier Split Protocol (LISP) [I-D.farinacci-lisp] proposes a map-and-encaps architecture for scalable routing and addressing within the global Internet Default Free Zone (DFZ). Templin Expires May 21, 2009 [Page 14] Internet-Draft RANGER November 2008 LISP, and a number of other proposals being discussed in the Routing Research Group, share a number of properties with the solution proposed here. They may therefore be architecturally consistent with the RANGER architecture. 5. IANA Considerations There are no IANA considerations for this document. 6. Security Considerations Communications between endpoints within different networks within an enterprise are carried across a commons that joins organizational entities with a mutual spirit of cooperation, but between which there may be competing business/sociological/political interests. As a result, mechanisms that rely on feedback from routers on the path may become brittle or susceptible to spoofing attacks. This is due to the fact that IP packets can be lost due to congestion or packet filtering gateways, and that the source addresses of IP packets can be forged. IP packets can therefore be generated by anonymous attackers, e.g., from a rogue node within a third-party enterprise that has malicious intent toward a victim. Path MTU discovery is an example of a mechanism that relies on ICMP feedback from routers on the path, and as such is susceptible to these issues. For IPv4, a common workaround is to disable Path MTU Discovery and let fragmentation occur in the network if it must. For IPv6, lack of fragmentation support in the network precludes this option such that the mitigation typically recommended is to discard ICMP messages that contain insufficient information and/or to operate with the minimum IPv6 path MTU. This example extends also to other mechanisms that either rely on or are enhanced by feedback from network devices, however attack vectors based on non-ICMP messages are also subject for concern. The RANGER architecture supports effective mitigations for attacks such as distributed denial-of-service, traffic amplification, etc. In particular, when VETand SEAL are is used, enterprise BGs can use the identification encoded in the SEAL header as well as ingress filtering to determine if a message has come from a topologically- correct enterprise located across the commons. This allows enterprises to employ effective mitigations at their borders without the requirement for mutual cooperation from other enterprises. When source address spoofing by nodes located within the commons is also subject for concern, additional securing mechanisms such as tunnel- mode IPsec between enterprise BGs can also be used. Templin Expires May 21, 2009 [Page 15] Internet-Draft RANGER November 2008 While the RANGER architecture does not in itself address security considerations, it proposes an architectural framework for functional specifications that do. Security concerns with tunneling along with recommendations that are compatible with the RANGER architecture are found in [I-D.ietf-v6ops-tunnel-security-concerns]. 7. Acknowledgements This work was inspired through the encouragement of the Boeing DC&NT network technology team and through the communications of the IESG. Many individuals have contributed to the architectural principles that form the basis for RANGER over the course of many years. 8. References 8.1. Normative References [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. 8.2. Informative References [CATENET] Pouzin, L., "A Proposal for Interconnecting Packet Switching Networks", May 1974. [I-D.arkko-townsley-coexistence] Arkko, J. and M. Townsley, "IPv4 Run-Out and IPv4-IPv6 Co- Existence Scenarios", draft-arkko-townsley-coexistence-00 (work in progress), September 2008. [I-D.bauer-mext-aero-topology] Bauer, C. and S. Ayaz, "ATN Topology Considerations for Aeronautical NEMO RO", draft-bauer-mext-aero-topology-00 (work in progress), July 2008. [I-D.farinacci-lisp] Farinacci, D., Fuller, V., Oran, D., Meyer, D., and S. Brim, "Locator/ID Separation Protocol (LISP)", draft-farinacci-lisp-09 (work in progress), October 2008. [I-D.ietf-v6ops-tunnel-security-concerns] Hoagland, J., Krishnan, S., and D. Thaler, "Security Templin Expires May 21, 2009 [Page 16] Internet-Draft RANGER November 2008 Concerns With IP Tunneling", draft-ietf-v6ops-tunnel-security-concerns-01 (work in progress), October 2008. [I-D.templin-autoconf-dhcp] Templin, F., "Virtual Enterprise Traversal (VET)", draft-templin-autoconf-dhcp-20 (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. [I-D.wing-nat-pt-replacement-comparison] Wing, D., Ward, D., and A. Durand, "A Comparison of Proposals to Replace NAT-PT", draft-wing-nat-pt-replacement-comparison-02 (work in progress), September 2008. [IEN48] Cerf, V., "The Catenet Model for Internetworking", July 1978. [RFC1380] Gross, P. and P. Almquist, "IESG Deliberations on Routing and Addressing", RFC 1380, November 1992. [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. [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. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol (HIP) Architecture", RFC 4423, May 2006. Templin Expires May 21, 2009 [Page 17] Internet-Draft RANGER November 2008 [RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol (MOBIKE)", RFC 4555, June 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. [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, March 2008. [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, July 2008. Author's Address Fred L. Templin (editor) Boeing Phantom Works P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: fltemplin@acm.org Templin Expires May 21, 2009 [Page 18] Internet-Draft RANGER November 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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