Internet Research Task Force F. Templin, Ed. (IRTF) Boeing Research & Technology Internet-Draft June 9, 2010 Intended status: Informational Expires: December 11, 2010 The Internet Routing Overlay Network (IRON) draft-templin-iron-05.txt Abstract The Internet routing system is experiencing a growth profile that has led many to express concerns for unsustainable routing scaling. Operational practices such as increased use of multihoming with IPv4 Provider-Independent (PI) addressing are resulting in more and more fine-grained prefixes injected into the routing system from more and more end user networks. Furthermore, depletion of the remaining public IPv4 address space has raised concerns for both increased deaggregation (leading to yet further routing scaling) and an impending address space runout scenario. At the same time, the IPv6 routing system is finally beginning to see significant growth in IPv6 Provider-Aggregated (PA) prefixes but there does not seem to be a solution on the near term horizon for IPv6 PI addressing. Since the Internet must continue to support escalating growth due to increasing demand, it is clear that current mechanisms and operational practices must be updated. This document therefore proposes an Internet Routing Overlay Network (IRON) for supporting sustainable growth through PI addressing while requiring no changes to end systems and no changes to the existing routing system. This document is a product of the IRTF Routing Research Group (RRG). Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on December 11, 2010. Templin Expires December 11, 2010 [Page 1] Internet-Draft IRON June 2010 Copyright Notice Copyright (c) 2010 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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. IRON Routers . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. The Internet Routing Overlay Network (IRON) . . . . . . . . . 5 5. IRON Initialization . . . . . . . . . . . . . . . . . . . . . 7 5.1. IR(VP) and IR(GW) Initialization . . . . . . . . . . . . . 7 5.2. IR(EP) Initialization . . . . . . . . . . . . . . . . . . 8 6. IRON Operation . . . . . . . . . . . . . . . . . . . . . . . . 9 6.1. IR(EP) Operation . . . . . . . . . . . . . . . . . . . . . 9 6.2. IR(VP) Operation . . . . . . . . . . . . . . . . . . . . . 10 6.3. IR(GW) Operation . . . . . . . . . . . . . . . . . . . . . 10 6.4. IRON Reference Operating Scenario . . . . . . . . . . . . 11 6.5. Mobility, Multihoming and Traffic Engineering . . . . . . 12 6.5.1. Mobility Management . . . . . . . . . . . . . . . . . 12 6.5.2. Multihoming . . . . . . . . . . . . . . . . . . . . . 13 6.5.3. Inbound Traffic Engineering . . . . . . . . . . . . . 13 6.5.4. Outbound Traffic Engineering . . . . . . . . . . . . . 13 7. Related Initiatives . . . . . . . . . . . . . . . . . . . . . 14 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 9. Security Considerations . . . . . . . . . . . . . . . . . . . 14 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 11.1. Normative References . . . . . . . . . . . . . . . . . . . 14 11.2. Informative References . . . . . . . . . . . . . . . . . . 14 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16 Templin Expires December 11, 2010 [Page 2] Internet-Draft IRON June 2010 1. Introduction The Internet routing system is experiencing a growth profile that has led many to express concerns for unsustainable routing scaling. Operational practices such as increased use of multihoming with IPv4 Provider-Independent (PI) addressing are resulting in more and more fine-grained prefixes injected into the routing system from more and more end user networks. Furthermore, depletion of the remaining public IPv4 address space has raised concerns for both increased deaggregation (leading to yet further routing scaling) and an impending address space runout scenario. At the same time, the IPv6 routing system is finally beginning to see significant growth in IPv6 Provider-Aggregated (PA) prefixes but there does not seem to be a solution on the near term horizon for IPv6 PI addressing. Since the Internet must continue to support escalating growth due to increasing demand, it is clear that current mechanisms and operational practices must be updated. Virtual Aggregation (VA) [I-D.ietf-grow-va] and Aggregation in Increasing Scopes (AIS) [I-D.zhang-evolution] are global routing proposals that introduce routing overlays with Virtual Prefixes (VPs) for router Forwarding Information Base (FIB) and Routing Information Base (RIB) scaling reduction. Routing and Addressing in Networks with Global Enterprise Recursion (RANGER) [RFC5720] examines recursive arrangements of enterprise networks that can apply to a very broad set of use case scenarios [I-D.russert-rangers]. In particular, RANGER supports encapsulation and secure redirection by treating each layer in the recursive hierarchy as a virtual non- broadcast, multiple access (NBMA) "link". RANGER is an architectural framework that includes Virtual Enterprise Traversal (VET) [I-D.templin-intarea-vet] and the Subnetwork Adaptation and Encapsulation Layer (SEAL) [I-D.templin-intarea-seal] as its functional building blocks. This document proposes an Internet Routing Overlay Network (IRON) for supporting sustainable growth while requiring no changes to the existing routing system. IRON borrows concepts from VA, AIS and RANGER, and further borrows concepts from the Internet Vastly Improved Plumbing (Ivip) [I-D.whittle-ivip-arch] architecture proposal. IRON specifically seeks to enable scalable Provider- Independent (PI) addressing without changing the current BGP [RFC4271] routing systems of the IPv4 and IPv6 Internets in any way. IRON uses the IPv4 and IPv6 global Internet routing systems as virtual NBMA links for tunneling inner network protocol packets that use End User Network (EUN) PI Prefix (EP) source addresses within outer IPv4 or IPv6 packets that use Routing LOCator (RLOC) addresses. Moreover, inner packets can be either IPv4 or IPv6 without regard to Templin Expires December 11, 2010 [Page 3] Internet-Draft IRON June 2010 the address family used in the outer packet, and inner packets can even be non-IP protocols such as OSI/CLNP. This document is offered in compliance with Internet Research Task Force (IRTF) document stream procedures [RFC5743]; it is not an IETF product and is not a standard. The views in this document were considered controversial by the IRTF Routing Research Group (RRG) but the RG reached a consensus that the document should still be published. The document will undergo a period of review within the RRG and through selected expert reviewers prior to publication. The following sections discuss details of the IRON architecture. 2. Terminology The following abbreviations correspond to terms used within this document and elsewhere in common Internetworking nomenclature: EP - End User Network PI Prefix ETE - Egress Tunnel Endpoint EUN - End User Network ISP - Internet Service Provider ITE - Ingress Tunnel Endpoint MVP - Master Virtual Prefix (database) NBMA - Non-Broadcast, Multiple Access PA - Provider Aggregated PI - Provider Independent SCMP - the SEAL Control Message Protocol SEAL_ID - an Identification value, randomly initialized and monotonically incremented for each SEAL protocol packet TE - Tunnel Endpoint (i.e., either ingress or egress) VP - Virtual Prefix Templin Expires December 11, 2010 [Page 4] Internet-Draft IRON June 2010 3. IRON Routers IRON introduces a new class of routers called IRON Routers (IRs) that can be deployed on platforms ranging from high-end enterprise routers to customer premises routers to simple commodity servers. Moreover, IRs can be introduced incrementally and without affecting existing infrastructure. The purpose of these new IRs is to provide waypoints (or "cairns") for navigating the IRON so that packets with destination addresses taken from End User Network PI prefixes (EPs) can be delivered to the correct End User Networks (EUNs) through the use of encapsulation with minimum path stretch for initial packets and optimized routes for non-initial packets. The different categories of IRs includes: o IR - an IRON Router of any kind o IR(VP) - a tunnel endpoint router that is owned by a VP company and that aggregates VPs from which it sub-delegates more-specific EPs to EUNs. o IR(EP) - a tunnel endpoint router (or host with embedded gateway function) that obtains an EP from a VP company, and that connects an EUN to the IRON. An IR(EP) will typically be a customer premises equipment (CPE) device that connects the EUN to its ISP(s), but may also be a router or even a singleton host within the EUN. o IR(GW) - a router that acts as a gateway between the IRON and the non-IRON Internet. Each VP company configures one or more IR(GWs) which advertise the company's VPs into the IPv4 and/or IPv6 global Internet DFZs. An IR(GW) may be configured on the same physical platform as IR(VPs), or as a separate standalone platform. An IR(GW) will typically be a BGP router that is capable of sourcing encapsulated packets. IRON observes the Internet Protocol standards [RFC0791][RFC2460]. Other network layer protocols that can be encapsulated within IP packets (e.g., OSI/CLNP [RFC1070], etc.) are also within scope. 4. The Internet Routing Overlay Network (IRON) The Internet Routing Overlay Network (IRON) consists of IRON Routers (IRs) that use Virtual Enterprise Traversal (VET) and the Subnetwork Encapsulation and Adaptation Layer (SEAL) for the purpose of forwarding encapsulated inner network layer packets over the IPv4 and IPv6 Internets. Each such IR views the IPv4 and IPv6 global Internets as monolithic virtual NBMA "links", and connects to the Templin Expires December 11, 2010 [Page 5] Internet-Draft IRON June 2010 links via a VET interface used for automatic tunneling. Each IR therefore sees all other IRs as virtual single-hop neighbors on the link from the standpoint of the inner network layer protocol, while they may be separated by many physical outer IP hops. IRs are deployed incrementally and without disturbing the existing Internet routing system. The IRON is manifested through a business model in which VP companies own and manage a set of IR(VPs) that are dispersed throughout the Internet and that serve a set of highly-aggregated VPs. Each VP company sets up a service in which it leases EPs taken from the VPs to customer EUNs. These EUNs may be located within the same network as the VP company's IR(VP) routers, or they may be located elsewhere within the Internet. The VP company acts as a virtual enterprise network which EUNs loosely consider as their "home" network even though they physically arrange for basic connectivity via one or more ISP networks that may have no affiliation with the VP company. VP companies can therefore open for business and begin serving their customers immediately without the need to coordinate their activities with ISPs or with other VP companies. Each VP company also establishes a set of IR(GW) routers that connect to the IPv4 and/or IPv6 Internet DFZs. The IR(GW) advertises all of the VP company's IPv4 VPs into the IPv4 DFZ and advertises all of its IPv6 VPs into the IPv6 DFZ. Each IR(GW) forwards any packets coming from the DFZ to an IR(VP) that can encapsulate the packet and forward it to the appropriate IR(EP). In this way, end systems that use PA addresses can communicate with other end systems that use PI addresses taken from an IRON VP. EUNs establish at least one IR(EP) that connects the EUN to the IRON. The IR(EP) uses encapsulation to forward packets with EP source addresses to an IR(VP) belonging to its VP company as a default router. The VP company's IR(VP) then forwards the packets toward their final destination, and returns a SEAL Control Message Protocol (SCMP) redirect message to inform the IR(EP) of a better next hop if necessary. In this way, IR(EPs) experience reasonable path stretch for initial packets and can discover route-optimized paths for subsequent packets. The IRON additionally requires a global mapping database to allow IRs to map EPs/VPs to RLOCs assigned to the interfaces of other IRs. Each VP in the IRON is therefore represented in a globally distributed Master VP (MVP) mapping database. The MVP database is maintained by a globally-managed assigned numbers authority in the same manner as the Internet Assigned Numbers Authority (IANA) currently maintains the master list of all top-level IPv4 and IPv6 delegations. The database can be replicated across multiple servers Templin Expires December 11, 2010 [Page 6] Internet-Draft IRON June 2010 for load balancing much in the same way that FTP mirror sites are used to manage software distributions. Each VP in the MVP database is encoded as the tuple: "{address family, prefix, prefix-length, FQDN}", where: o "address family" is one of IPv4, IPv6, OSI/CLNP, etc. o "prefix" is the VP, e.g., 2001:DB8::/32 (IPv6), 192.2/16 (IPv4), etc. o "prefix-length" is the length (in bits) of the associated VP o FQDN is a DNS Fully-Qualified Domain Name For each VP entry in the MVP database, the VP company maintains a FQDN in the DNS to map the VP to a list of IR(VP)s that serve it. The FQDN is resolved by both other IR(VP)s and by IR(EP)s that hold EP delegations from the VP into a list of resource records. Each resource record corresponds to an individual IR(VP), and encodes the tuple : "{address family, RLOC address, WGS 84 coordinates}" where "address family" is the address family of the RLOC, "RLOC" is the routing locator assigned to an IR(VP), and "WGS 84 coordinates" identify the physical location of the IR(VP). Together, the MVP database and the FQDNs in the global DNS provide sufficient mapping capabilities to support navigation of the IRON. 5. IRON Initialization IRON initialization entails the startup actions of VP company and EUN equipment. The following sections discuss these startups procedures: 5.1. IR(VP) and IR(GW) Initialization Upon startup, each IR(VP) and IR(GW) owned by the VP company discovers the full set of VPs for the IRON by reading the MVP database (see Section 4). These VPs may be IPv4 or IPv6, but they may also be prefixes of other network layer protocols (e.g., OSI/CLNP NSAP [RFC4548], etc.). Each IR(VP/GW) reads the MVP database from a nearby server upon startup time, and periodically checks for deltas on the server since the database was last read. Upon reading the MVP database, the IR(VP/GW) resolves the FQDN corresponding to each VP into an RLOC and a physical location. Each RLOC address is an IPv4 or IPv6 RLOC address assigned to the IR(VP) within the DFZ. For each VP, the IR(VP/GW) sorts the list of RLOCs in order of "geographic closeness", and inserts each "VP->RLOC" mapping into its Forwarding Information Base (FIB) with a priority corresponding to Templin Expires December 11, 2010 [Page 7] Internet-Draft IRON June 2010 geographic closeness. Specifically, the FIB entries must be configured such that packets with destination addresses covered by the VP are forwarded to the corresponding RLOC using encapsulation of the inner network layer packet in an outer IP header. Note that the VP and RLOC may be of different address families; hence, possible encapsulations include IPv6-in-IPv4, IPv4-in-IPv6, IPv6-in-IPv6, IPv4-in-IPv4, OSI/CLNP-in-IPv6, OSI/CLNP-in-IPv4, etc. After each IR(VP/GW) reads in the list of VPs and sorts the information accordingly, it is said to be "synchronized with the IRON". Each IR(VP) next installs all EPs derived from its VPs into its FIB based on the mapping information received from each of its EUN customers. 5.2. IR(EP) Initialization Upon startup, each IR(EP) must register its EP-to-RLOC binding with the company that owns the corresponding VP, where the RLOC is an IPv4 or IPv6 address assigned to the IR(EP) by an ISP network. For example, if an IR(EP) owns the EP 192.2.1/24 (IPv4) and the RLOC assigned to the IR(EP) by the ISP is 2001:DB8::1 (IPv6), the IR(EP) informs the VP company that the route 192.2.1/24 with 2001:DB8::1 as the L2 address of the next-hop must be added to the FIB in each of its IR(VPs) that aggregates the EP. The IR(EP) typically informs the VP company by using an authenticated short transaction protocol (e.g., http(s) with username/password) to register its EP-to-RLOC mapping information. (The exact specification for the short transaction is up to the VP company and need only be communicated to the IR(EP); the IR(EP) also uses the same EP-to-RLOC registration procedure to inform its VP company of a change in RLOC, e.g., due to a mobility event, a change in its primary ISP, etc.). After the IR(EP) registers its mapping information, the VP company then propagates it to each of its IR(VPs) that aggregates the EP, e.g., via a routing protocol that all of the VP company's IR(VP)s engage in. After the IR(EP) informs the VP company of its EP->RLOC mapping, it resolves a FQDN for the VP company in order to discover the RLOC addresses and geographic locations of the IR(VPs) owned by the company. (This resolution closely resembles the ISATAP Potential Router List (PRL) resolution procedure [RFC5214].) The IR(EP) then selects the closest subset of these RLOC addresses (typically 2-4 routers chosen, e.g., based on geographic distance), and adds them to a default router list of FIB entries that each points to a VET interface with the RLOC as the L2 address of the next-hop. The IR(EP) will then use these routes in the default router list as the means for forwarding encapsulated packets with EID source addresses toward the final destination via encapsulation. Templin Expires December 11, 2010 [Page 8] Internet-Draft IRON June 2010 6. IRON Operation Following IRON initialization, IRs engage in the steady-state process of receiving and forwarding packets. Except in instances when it forwards an unencapsulated packet to the public Internet, the IR encapsulates each forwarded packet using the mechanisms of VET [I-D.templin-intarea-vet] and SEAL [I-D.templin-intarea-seal]. IRs also use the SEAL Control Message Protocol (SCMP) to test liveness of other IRs and to receive redirect messages informing them of a more optimal route. Each IR operates as specified in the following sections: 6.1. IR(EP) Operation After an IR(EP) is initialized, it sends periodic beacons to at least 2-4 of its VP company's IR(VP)s which serve as default routers. Each beacon is a SEAL Control Message Protocol (SCMP) Router Solicitation (RS) message, and will elicit an SCMP Router Advertisement (RA) message from the IR(VP). If the IR(EP) ceases to receive RA messages from an IR(VP), it marks the IR(VP) as unreachable and selects a different IR(VP). If the IR(EP) ceases to receive RA messages from multiple IR(VPs), it marks the ISP connection as failed/failing and uses an RLOC assigned by a different ISP to re-register its EP-to- RLOC mapping. When an end system in an EUN has a packet to send, the packet is forwarded through the EUN until it reaches the IR(EP). The source IR(EP) then forwards the packet either to an IR(VP) or to a destination IR(EP). The source IR(EP) first checks its FIB for the longest matching prefix. If the longest matching prefix is more- specific than "default", the source IR(EP) forwards the packet to the next-hop the same as for ordinary IP forwarding. If the longest match is "default", however, the source IR(EP) forwards the packet to one of the IR(VP)s serving as its default routers. The source IR(EP) uses VET and SEAL to encapsulate each forwarded packet in an outer IP header with the IP address of the next-hop IR as the destination address. The source IR(EP) further uses SCMP to test liveness and/or to accept redirect messages from the next-hop IR. When the source IR(EP) receives an SCMP redirect, it checks the SEAL_ID field of the encapsulated message to verify that the redirect corresponds to a packet that it had previously sent to the neighbor and accepts the redirect if there is a match. Thereafter, subsequent packets forwarded by the source IR(EP) will follow a route-optimized path. An IR(EP) that accepts redirects may be redirected by an IR(VP) in its home VP company network to one or more IR(VP)s in a "foreign" Templin Expires December 11, 2010 [Page 9] Internet-Draft IRON June 2010 network. In that case, the IR(EP) has no way of knowing if these foreign IR(VP)s are reachable and able to process encapsulated packets. In that case, the IR(EP) should select multiple foreign IR(VPs) (e.g., 2-4) and send "live" packets to one of them while sending corresponding "blank" packets to the others. In turn, each foreign IR(VP) accepts and forwards "live" packets, but drops "blank" packets after sending a redirect. In this way, even if the original packet is lost due to congestion or a short-term outage, the IR(EP) will receive a redirect from at least one of the foreign IR(VP)s. 6.2. IR(VP) Operation After an IR(VP) is initialized, it sends RA responses to the periodic RS beacons sent by IR(EPs) as described in Section 6.1. When the IR(VP) receives an encapsulated packet from another IR, it examines the inner destination address then forwards the packet as follows: o If the inner destination address matches an EP in its FIB, the IR(VP) 'A' re-encapsulates the packet using VET/SEAL and forwards it to the next-hop IR(EP) 'B'. If the source IR 'C' is accepting redirects, 'A' also sends an SCMP redirect message back to 'C'. 'C' will then send subsequent packets directly to 'B'. o If the inner destination address does not match an EP but matches a VP in its FIB, the IR(VP) 'A' re-encapsulates the packet using VET/SEAL and forwards it to the next-hop IR(VP) 'B' . If the source IR 'C' is accepting redirects, 'A' also sends an SCMP redirect message back to 'C'. 'C' will then send subsequent packets directly to 'B'. o if the inner destination address does not match an EP or a VP in the FIB, the IR(VP) decapsulates the packet and forwards it to the public Internet via a default or more-specific route. An IR(VP) that accepts redirects may need to forward initial packets via the IR(VP)s of a "foreign" network. In that case, the IR(VP) can send a "live" packet in parallel with corresponding "blanks" the same as for an IR(EP). 6.3. IR(GW) Operation Each VP company must establish one or more IR(GW) routers which advertise the full set of the company's VP's into the IPv4 and/or IPv6 Internet BGP. The VPs will be seen as ordinary routing information in the BGP, and any packets originating from the non-IRON IPv4 or IPv6 Internet will be forwarded into the VP company's network by an IR(GW). When an IR(GW) receives a packet from the non-IRON Internet but destined to an EP destination, it consults its FIB to Templin Expires December 11, 2010 [Page 10] Internet-Draft IRON June 2010 determine the best next-hop toward the final destination. The IR(GW) then either forwards the packet to an IR(VP) within the home network or acts as an IR(VP) itself to forward the packet further. 6.4. IRON Reference Operating Scenario With respect to the previous sections, a path between two EUNs can potentially involve both the two IR(EPs) and the IR(VP)s of the two VP companies that serve the EUNs. Route optimization based on redirection will allow shortcuts that eliminate the IR(VP)s from the path. The following figure depicts the IRON reference operating scenario for communications between two EUNs: +------------+ +------------+ | | | | /======>+ IR(VP(A)) +======>+ IR(VP(B)) +======\ // | | | | \\ // +------------+ +------------+ \\ // V +-----+-----+ +-----+-----+ | IR(EP(A)) | ........................................>| IR(EP(B)) | +-----+-----+ +-----+-----+ | | ........ ........ ( EUN A ) ( EUN B ) ........ ........ | | +---+----+ +---+----+ | Host A | | Host B | +--------+ +--------+ Figure 1: IRON Reference Operating Scenario In this reference scenario, VP companies A and B have established IR(VP)s within the Internet that serve EPs to EUNs. EUN A has procured an EP from VP company A, while EUN B has procured an EP from VP company B. The hosts in both EUNs have assigned addresses taken from their corresponding EPs on their EUN-interior interfaces, and the IR(EPs) have assigned RLOC addresses taken from their ISPs on their WAN interfaces. When Host A in EUN A has a packet to send to Host B in EUN B, normal routing conveys the packet from Host A to IR(EP(A)). If IR(EP(A ))does not have a more-specific route, it encapsulates the packet and forwards it to an IR(VP) owned by VP company A. IR(VP(A )) decapsulates the packet and checks its FIB for a route toward the packet's destination address. If IR(VP(A)) does not have an EP route Templin Expires December 11, 2010 [Page 11] Internet-Draft IRON June 2010 to Host B in its FIB, it consults its full table of VP-to-RLOC mappings to discover that the next-hop toward Host B is via IR(VP(B)). IR(VP(A)) then re-encapsulates the packet and sends it to IR(VP(B)) which has an EP route to Host B via IR(EP(B)). IR(VP(B)) then re-encapsulates the packet and sends it to IR(EP(B)), which decapsulates the packet and forwards it via EUN B to Host B. In this process, when an IR(VP) re-encapsulates the packet and forwards it to a next-hop IR, it also returns an SCMP redirect message to the previous hop IR if the previous hop is willing to accept redirects. The previous hop IR will then install a route in its FIB that uses a more optimal next hop. For example, if IR(EP(A)) is accepting redirects IR(VP(A)) will return a redirect message when it forwards a packet to IR(VP(B)). IR(EP(A)) will then send subsequent packets directly to IR(VP(B)), which will return a redirect message when it forwards the packets to IR(EP(B)). Finally, IR(EP(A)) will have an optimized route that lists IR(EP(B)) as the next hop (shown as "....>" in the diagram). Another redirection scenario arises when IR(VP(A)) is itself willing to accept redirects. In that case, IR(EP(A)) may discover IR(EP(B)) as a better next hop toward EUN A based solely on a redirect message from IR(VP(A)) and without involving IR(VP(B)). Note however that this may require IR(VP(A)) to carry thousands or even millions of EP entries in its FIB for all EUNs that it has sent packets to recently, which may negatively impact scalability. 6.5. Mobility, Multihoming and Traffic Engineering While IR(VP)s can be considered as fixed infrastructure, IR(EP)s may need to move between different network points of attachment, connect to multiple ISPs, or explicitly manage their traffic flows. The following sections discuss mobility, multihoming and traffic engineering considerations for IR(EP)s: 6.5.1. Mobility Management When an IR(EP) moves to a new topological location, it receives a new RLOC address. The IR(EP) then registers the new EP-to-RLOC mapping with its VP company the same as during its initialization phase as described in Section 5.2. In this way, mobile networks are naturally supported without the need for ancillary mechanisms. Next, the IR(EP) sends Neighbor Advertisement (NA) messages to each neighboring IR from which it has received packets recently. The NA message includes the new RLOC as the outer source address and includes the previous RLOC within an NA option field. The neighboring IR will update its neighbor cache so that subsequent Templin Expires December 11, 2010 [Page 12] Internet-Draft IRON June 2010 packets will flow through the new RLOC. 6.5.2. Multihoming An IR(EP) registers only the RLOC of its primary ISP with its VP company even if it connects to multiple ISPs. If the IR(EP) later needs to select a different ISP as its primary, it simply repeats the EP-to-RLOC registration process the same as if it were reacting to a mobility event as described above. 6.5.3. Inbound Traffic Engineering When an IR(EP) receives packets via its primary ISP (i.e., the ISP for which it is currently registered with the VP company), it may wish to balance the load of incoming traffic between multiple ISP connection points. In that case, the IR(EP) may send NA messages to certain neighboring IRs the same as in the case of a mobility event as described in Section 6.5.1. In that way, the IR(EP) can manage its incoming traffic flows for best utilization of its multiple ISPs. 6.5.4. Outbound Traffic Engineering IR(EP)s maintain a list of IR(VP)s that serve as default routers for VET interface encapsulation of inner packets with source addresses taken from an EP prefix. IR(EP)s also maintain a list of neighbors on underlying interfaces that serve as default routers for packets with non-EP source addresses. If the inner and outer protocols are of different versions (e.g., OSI/CLNP as the inner version and IPv4 as the outer version) then the default routes of both versions are mutually exclusive and no special arrangements are needed. If the inner and outer protocol versions are the same, however (e.g., IPv6 as both the inner and outer protocol) then a special treatment of the default route is necessary. In particular, the IR(EP) must examine the source address of a packet to be forwarded to determine the proper handling of "default". If the packet uses a source address taken from an EP prefix, the IR(EP) forwards it to an IR(VP) using encapsulation via a VET interface; otherwise, the IR(EP) forwards the packet to a next hop on an underlying link. Using this arrangement of default, when an IR(EP) forwards a packet with an EP source address it can forward it to any of its associated IR(VP)s using VET interface encapsulation over any of its underlying interfaces. The choice of underlying interface can be managed, and the source address assigned to the underlying interface will be used as the outer source address of the encapsulated packet. Each encapsulated packet can therefore be directed through the desired ISP using a topologically-correct outer source address. Templin Expires December 11, 2010 [Page 13] Internet-Draft IRON June 2010 7. Related Initiatives IRON builds upon the concepts RANGER architecture [RFC5720], and therefore inherits the same set of related initiatives. Virtual Aggregation (VA) [I-D.ietf-grow-va] and Aggregation in Increasing Scopes (AIS) [I-D.zhang-evolution] provide the basis for the Virtual Prefix concepts. Internet vastly improved plumbing (Ivip) [I-D.whittle-ivip-arch] has contributed valuable insights, including the use of real-time mapping. 8. IANA Considerations The IANA is instructed to create a Master Virtual Prefix (MVP) registry for IRON. 9. Security Considerations Security considerations for RANGER apply also to IRON. 10. Acknowledgements This ideas behind this work have benefited greatly from discussions with colleagues; some of which appear on the RRG and other IRTF/IETF mailing lists. 11. References 11.1. 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. 11.2. Informative References [I-D.ietf-grow-va] Francis, P., Xu, X., Ballani, H., Jen, D., Raszuk, R., and L. Zhang, "FIB Suppression with Virtual Aggregation", draft-ietf-grow-va-02 (work in progress), March 2010. Templin Expires December 11, 2010 [Page 14] Internet-Draft IRON June 2010 [I-D.russert-rangers] Russert, S., Fleischman, E., and F. Templin, "Operational Scenarios for IRON and RANGER", draft-russert-rangers-03 (work in progress), June 2010. [I-D.templin-intarea-seal] Templin, F., "The Subnetwork Encapsulation and Adaptation Layer (SEAL)", draft-templin-intarea-seal-15 (work in progress), June 2010. [I-D.templin-intarea-vet] Templin, F., "Virtual Enterprise Traversal (VET)", draft-templin-intarea-vet-15 (work in progress), June 2010. [I-D.whittle-ivip-arch] Whittle, R., "Ivip (Internet Vastly Improved Plumbing) Architecture", draft-whittle-ivip-arch-04 (work in progress), March 2010. [I-D.zhang-evolution] Zhang, B. and L. Zhang, "Evolution Towards Global Routing Scalability", draft-zhang-evolution-02 (work in progress), October 2009. [RFC1070] Hagens, R., Hall, N., and M. Rose, "Use of the Internet as a subnetwork for experimentation with the OSI network layer", RFC 1070, February 1989. [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. [RFC4548] Gray, E., Rutemiller, J., and G. Swallow, "Internet Code Point (ICP) Assignments for NSAP Addresses", RFC 4548, May 2006. [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, March 2008. [RFC5720] Templin, F., "Routing and Addressing in Networks with Global Enterprise Recursion (RANGER)", RFC 5720, February 2010. [RFC5743] Falk, A., "Definition of an Internet Research Task Force (IRTF) Document Stream", RFC 5743, December 2009. Templin Expires December 11, 2010 [Page 15] Internet-Draft IRON June 2010 Author's Address Fred L. Templin (editor) Boeing Research & Technology P.O. Box 3707 MC 7L-49 Seattle, WA 98124 USA Email: fltemplin@acm.org Templin Expires December 11, 2010 [Page 16]