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Versions: 00 01 02 03 04                                                
Network Working Group                                            X. Xu
Internet Draft                                                  Huawei
Intended status: Informational
Expires: February 2011                                 August 10, 2010

       Routing Architecture for the Next Generation Internet (RANGI)

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on February 10, 2011.

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   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
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   IRTF Routing Research Group (RRG) is exploring a new routing and
   addressing architecture to address the issues with the current
   Internet, e.g., mobility, multi-homing, traffic engineering, and
   especially the routing scalability issue. This document describes a
   new identifier (ID)/locator split based routing and addressing
   architecture, called Routing Architecture for the Next Generation
   Internet (RANGI), in an attempt to deal with the above problems.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC-2119 [RFC2119].

Table of Contents

   1. Introduction.................................................3
   2. Architecture Description.....................................3
      2.1. Host Identifiers........................................3
      2.2. Host Locators...........................................5
      2.3. Packet Formats..........................................6
      2.4. ID->Locator Mapping Resolution..........................6
      2.5. Routing and Forwarding System...........................8
      2.6. Site Multi-homing and Traffic-Engineering...............9
      2.7. Host Mobility and Multi-homing.........................10
      2.8. Network Mobility.......................................11
   3. Summary.....................................................11
   4. Security Considerations.....................................12
   5. IANA Considerations.........................................12
   6. Acknowledgments.............................................12
   7. References..................................................12

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1. Introduction

   The Default Free Zone (DFZ) routing table size has been growing at an
   increasing and potentially alarming rate for several years, which has
   detrimental impact on the routing system scalability and the routing
   convergence performance. This so-called routing scalability issue has
   drawn significant attention from both industry and academia. After
   much discussion following the IAB Routing and Addressing workshop
   [RAWS] in Amsterdam, a common conclusion was reached that the
   explosive growth in the DFZ routing table is mainly caused by the
   wide adoption of multi-homing, traffic engineering and provider-
   independent address. However, the underlying reason for this issue is
   the overloading of IP address semantics of both identifiers and
   locators. This overloading makes it impossible to renumber IP
   addresses in a topologically aggregatable way.

   At present, the IRTF Routing Research Group (RRG) is chartered to
   explore a new routing and addressing architecture which is expected
   to support the multi-homing, traffic-engineering, mobility and
   simplified renumbering features in a more scalable way.

   This document describes a new ID/locator split architecture, called
   Routing Architecture for the Next Generation Internet (RANGI), which
   aims to deal with the above issues. Similar with Host Identity
   Protocol (HIP) [RFC4423], RANGI also introduces a host identifier (ID)
   layer between the IPv6 network layer and the transport layer. As a
   result, the transport-layer associations (e.g., TCP connections) are
   no longer bound to IP addresses, but to the host IDs. Unlike HIP,
   RANGI adopts hierarchical and cryptographic host IDs which have
   delegation-oriented structure. As a result, the corresponding ID-
   >locator mapping system for such identifiers has a reasonable
   business model and clear trust boundaries. In addition, RANGI uses
   special IPv4-embeded IPv6 addresses as locators. With such locators,
   site-controlled traffic-engineering and simplified renumbering can be
   easily achieved, meanwhile, the deployment cost of this new
   architecture is reduced greatly.

2. Architecture Description

   2.1. Host Identifiers

   In RANGI, host IDs are hierarchical and 128-bit long. As depicted in
   Figure 1, a host ID consists of two parts: the leftmost n bits (Note
   that the suitable value of "n" has not been determined yet, while the
   value of " n" is set to 64 in our current prototype) part is the
   Administrative Domain (AD) ID which has embedded organizational

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   affiliation and global uniqueness, and the remaining part (i.e., the
   rightmost 128-n bits)is the Local Host ID which is generated by
   computing a cryptographic one-way hash function from a public key of
   the ID owner and auxiliary parameters, e.g., the ID owner's AD ID.
   The binding between the public key and the host ID can be verified by
   re-computing the hash value and by comparing the hash with the host
   ID. As these identifiers are expected to be used along with IPv6
   addresses at both applications and APIs, especially in the RANGI
   transition mechanisms defined in [RANGI-PROXY], it is desired to
   explicitly distinguish host IDs from IPv6 addresses (i.e., locators)
   and vice versa. Hence, a separate prefix for identifiers SHOULD be
   allocated by the IANA. As a result, several leftmost bits in the AD
   ID field SHOULD be reserved to fill this dedicated prefix.

          |<------- n bits --------->|<-- 128-n bits-->|
          | Administrative Domain ID |   Local Host ID |
          |                            \
          |                              \
          |                                \
          |                                   \
          |                                      \
          |Country Code|Authority Code|Region Code| <------Example

                    Figure 1. Host Identifier Structure

   The approach of generating hierarchical RANGI host IDs is similar to
   that for Cryptographically Generated Addresses (CGA) [RFC3972]. The
   major difference is that the prefix of the RANGI host ID is AD ID,
   rather than ordinary IPv6 address prefix. In CGA, the process of
   generating a new address takes three input values: a 64-bit subnet
   prefix, the public key of the address owner as a DER-encoded ASN.1
   structure of the type SubjectPublicKeyInfo and the security parameter
   Sec, which is an unsigned three-bit integer. In contrast, the process
   of generating a hierarchical host ID in RANGI also takes three input
   values: the n-bit AD ID, the public key of the host ID owner and the
   security parameter Sec. Therefore, if we set the value of n to 64,
   the process of generating RANGI host IDs can be compatible with that
   for CGA.

   The benefits of using hierarchical host IDs in RANGI include but not
   limited to: 1) manage the global identifier namespace in a scalable
   way; 2) hold a reasonable economic model and clear trust boundaries

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   in the corresponding ID->Locator mapping system; 3) ease the
   transition from the current Internet to RANGI.

   In RANGI, the global uniqueness of host IDs is guaranteed through
   some registration mechanism. Since the AD IDs are globally unique and
   owned by the corresponding host ID registration and administrative
   authorities of different countries respectively, the Local Host IDs
   are only REQUIRED to be unique within the corresponding AD scope.

   The resolution infrastructure for flat labels has no "pay-for-your-
   own" model, as names are stored at essentially random nodes (See
   Layered Naming Architecture (LNA) [LNA]). In contrast, the resolution
   infrastructure for hierarchical host IDs in RANGI has reasonable
   business model and clear trust boundaries since host IDs can be
   stored in the corresponding authoritative servers according to their
   organizational structures. To some extent, the business model of the
   ID->Locator mapping system in RANGI is similar to that for the Domain
   Name Service (DNS).

   In the RANGI transition mechanisms described in [RANGI-PROXY], the
   identifiers of RANGI hosts are treated as ordinary IPv6 addresses by
   legacy IPv6 hosts. Upon receives a packet with the destination
   address being a host ID, the router SHOULD forward the packet
   according to the destination IPv6 address as normal. In the end, the
   packet will be forwarded to a dedicated proxy that is responsible for
   translating the packets between RANGI and IPv6. Since the identifiers
   are hierarchical and delegation-oriented aggregatable, such
   identifier-based routing during transition period will not cause any
   routing scalability issue. For more details, please refer to [RANGI-

   2.2. Host Locators

   The host locators in RANGI are ordinary IPv6 addresses. Since the
   IPv4/IPv6 coexistence and transition will last for a long period, in
   order to reduce the deployment cost of this new routing and
   addressing architecture, RANGI uses specific IPv4-embeded IPv6
   addresses as locators. As shown in Figure 2, the leftmost 96-bit part
   of a locator is called Locator Domain Identifier (LD ID), while the
   rightmost 32-bit part is filled with an IPv4 address which is
   REQUIRED to be unique within the scope of corresponding LD. LD IDs
   are used to globally identify each site network which is allowed to
   adopt independent IPv4 address space (either public or private IPv4
   addresses). Actually, LD IDs are Provider-Assigned (PA) /96 IPv6
   prefixes which are topologically aggregatable in provider networks.

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              |<------- 96 bits -------->|<---- 32 bits--->|
              |         LD ID            |       IPv4      |

                     Figure 2. Host Locator Structure

   Similar with the Intra-Site Automatic Tunnel Addressing Protocol
   (ISATAP) [RFC5214], this specific locator can be used for
   automatically tunneling IPv6 packets over IPv4 site networks.

   2.3. Packet Formats

   RANGI reuse the IPv6 packet format to maximum extent. The host IDs
   are filled as options in the Destination Option Header, whereas the
   locators are filled as IPv6 addresses in the IPv6 header. Packets
   sent from a RANGI host can be protected by attaching the public key
   and auxiliary parameters and by signing the packets with the
   corresponding private key. The protection works without a
   certification authority or any security infrastructure.

   The details about the packet format and how to use IPsec to carry the
   data traffic will be described in the latter version of this draft or
   in a separate draft.

   2.4. ID->Locator Mapping Resolution

   ID/locator split implies a need for storing and distributing the
   mappings from host IDs to locators.

   In RANGI, the mappings from Fully Qualified Domain Names (FQDNs) to
   host IDs are stored in the DNS system, while the mappings from host
   IDs to locators are stored in a distributed ID->Locator mapping
   system which can be built on the current DNS infrastrature. In a DNS
   based ID->Locator mapping system, if there are too many entries to be
   maintained by the authoritative servers of a given Administrative
   Domain (AD), Distribute Hash Table (DHT) technology can be used
   further to make these authoritative servers scale better. That is to
   say, the mappings maintained by a given AD will be distributed among
   a group of authoritative servers in a DHT fashion. As a result, the
   robustness feature of DHT is inherited naturally into the ID->Locator
   mapping system. Meanwhile, there is no trust issue since each AD
   authority runs its own DHT ring which maintains only mappings for the
   identifiers belonging to this AD.

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   A detailed mapping lookup example is given as follows:

   1. A host ID will be transformed to a FQDN format string. Firstly, a
   host ID is expressed as "country-code.authority-code.region-
   code.local-host-ID" by inserting dots between adjacent fields, then
   by reversing the fields and attaching with the suffix "rangiid.arpa."
   it is transformed into a FQDN-format string as "local-host-ID.region-

   2. The FQDN-format string is used as a key to locate the
   authoritative DNS server which maintains the desired resource records.

   In order to facilitate such a lookup process, a new sub-domain "
   rangiid.arpa." needs to be inserted into the current domain name
   hierarchy. This sub-domain can delegate its own sub-domains according
   to the hierarchy of the FQDN-format string of the host ID. A new
   Resource Record (RR) named RANGI is also defined for the ID->Locator
   mappings, in which the NAME field is filled with the FQDN-format
   string of a host ID, while the RDATA field is filled with the
   corresponding locator information, including but not limited to an
   IPv6 address (i.e., locator) and its preference, and so on.

   The resolution infrastructure for flat names has no "pay-for-your-
   own" model, as the flat names are stored at essentially random nodes.
   In contrast, the resolution infrastructure for hierarchical host IDs,
   as used in RANGI, has reasonable business and trust models because
   hierarchical host IDs have clear organization affiliation.

   To prevent the Man-in-the-Middle attacks during mapping lookups, the
   DNS Security Extensions (DNSSEC) [RFC535] is strongly recommended for
   the origin authentication and integrity assurance of the DNS data.

   To prevent DNS recursive servers caching antique ID->Locator mapping
   information, the TTL of a RANGI RR for a mobile host SHOULD be set to
   0 or a very small value. However, if a host (i.e., Correspondence
   Node) wants to cache the RR of the communicating host (i.e., Mobile
   Node), it can reset the TTL of that RR to a reasonable value

   The Secure DNS Dynamic Update mechanism defined in [RFC3007] is
   directly used for dynamically updating the ID->Locator mapping
   entries in the ID->Locator mapping system in a secure way.

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   2.5. Routing and Forwarding System

   In RANGI, site networks (i.e., LDs) are connected to the IPv6
   Internet via site border routers called Locator Domain Border Routers
   (LDBRs). LDBRd play the similar role as ISATAP [RFC5214] routers.

   A simple RANGI routing procedure is illustrated in Figure 3. Host A
   (as source host) looks up the locator of host B (as destination host)
   through the ID->Locator mapping system before communicating with host
   B. Since these two hosts are located in different LDs, A will tunnel
   the packets destined for B to one of its local LDBRs, e.g., BR1.
   Otherwise, A will tunnel the packets destined for B directly towards
   B's IPv4 address. Once the packets arrive at the LDBR of the
   destination site, e.g., BR4, it will tunnel the IPv6 packets towards
   B's IPv4 address which is the last four octets of the destination

   +-------------+  +-------------+  +-------------+  +-------------+
   | Payload     |  | Payload     |  | Payload     |  | Payload     |
   +-------------+  +-------------+  +-------------+  +-------------+
   |HI(A)->HI(B) |  |HI(A)->HI(B) |  |HI(A)->HI(B) |  |HI(A)->HI(B) |
   +-------------+  +-------------+  +-------------+  +-------------+
   |IPv6->IPv6   |  |IPv6->IPv6   |  |IPv6->IPv6   |  |IPv6->IPv6   |
   | (A)   (B)   |  | (A)   (B)   |  | (A)   (B)   |  | (A)   (B)   |
   +-------------+  +-------------+  +-------------+  +-------------+
   |IPv4->IPv4   |                                    |IPv4->IPv4   |
   | (A)   (BR1) |                                    | (BR4) (B)   |
   +-------------+                                    +-------------+
   |<- A to BR1  ->|<-BR1 to BR2 ->|<-BR3 to BR4 ->|  |<-BR4 to B ->|

          +---------              ------             ---------|
        +---+       \            /      \           /      +---+
        | A |        \          /        \         /      /| B |
        +---+\\       \        /          \       /     // +---+
          |    \\      |      |            |     |     /      |
          |      \\ +---+    +---+      +---+   +---+//       |
          |        \|BR1+----+BR2+------+BR3+---+BR4+/        |
          |         +---+    +---+      +---+   +---+         |
          |            |      |            |     |            |
           \  LD #1   /        \ Internet /       \  LD #3   /
            \        /          \        /         \        /
             \      /            \      /           \      /
              ------              ------             ------

                        Figure 3. Routing Procedure

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   LDBRs are dual-stack routers which could be able to perform source-
   based policy routing and source address rewriting according to
   traffic-engineering policies on the outgoing packets.

   Hosts can get the IPv4 addresses of their local LDBRs in several ways,
   e.g., a new Dynamic Host Configuration Protocol (DHCP) option, or a
   site-scope well-known anycast address dedicated for LDBRs.

   In RANGI, IPv6-over-IPv4 tunnels are deployed in the site networks.
   Hence, RANGI can achieve a smooth IPv4/IPv6 transition in the scope
   of site networks.

   2.6. Site Multi-homing and Traffic-Engineering

   In RANGI, each multi-homed site shall be assigned a /96 IPv6 prefix
   from each upstream ISP. Each host inside the multi-homed site, in
   turn, has multiple locators by concatenating the provider-assigned
   /96 IPv6 prefix with its locally unique IPv4 address. Hosts register
   the mappings from their identifiers to locators on the ID->Locator
   mapping system. As shown in Figure 4, host A is a RANGI host inside a
   multi-homed site, and it has two locators which are respectively
   synthesized from the LD IDs delegated from ISP1 and ISP2 and its IPv4
   address. Host A chooses either one as the source locator of the
   outgoing packets. Upon receiving the packets, the site border router,
   BR1, performs source-based policy routing. For example, if the source
   locator is from ISP1, the packets will be forwarded to ISP1,
   otherwise, they will be forwarded to ISP2. In addition, BR1 could
   also rewrite the LD ID of the source locator to the one assigned from
   another ISP according to the configured traffic-engineering policy,
   and then forward the packets to the corresponding ISP according to
   source-based policy routing. Similar to the GSE [GSE], the site-
   controlled traffic-engineering by rewriting the source LD ID will
   impact the path (upstream ISP) selection for both outgoing packets
   and returned packets.

   In addition, since each ID->locator mapping in the ID->Locator
   mapping system is associated with a preference. By setting different
   preference values for different locators of a given host which is
   located inside a multi-homed site network, the upstream ISP selection
   for the incoming traffic can also influenced.

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                                      /          \
                                     |           |
                                    +---+        |
                                    +BR2|        |
                                   /+---+        |
                                  /  |   ISP#1   |
                                 /    \          /
             /------            /      \        /
        +---*       \          /        --------
        | A |        \        /
        +---+\\       \      /
          |    \\      |    /
          |      \\ +---+  /
          |        \|BR1+/
          |         +---+--
          |            |   --          ----------
           \          /      --       /          \
            \ Site A /         --    |           |
             \      /            -- +---+        |
              ------               -+BR3|        |
                                    +---+        |
                                     |           |
                                      \  ISP#2   /
                                       \        /

            Figure 4.  Site Multi-homing and Traffic-engineering

   2.7. Host Mobility and Multi-homing

   To some extent, host multi-homing is similar to host mobility since
   their effects on the network and on correspondents are identical.

   In RANGI, when a host physically moves from one attachment point of
   network to another in the event of mobility or re-homing, it SHOULD
   inform its current correspondents of its new locator as soon as
   possible. Furthermore, it needs to update its locator information on
   the ID->Locator mapping authoritative server timely. In the case of
   simultaneous mobility, at least one of the communicating entities
   SHOULD resolve the correspondence node's new locator from the ID-
   >Locator mapping system so as to continue their communication.

   In order to allow legacy IPv6 hosts to initiate communicates with
   RANGI mobile hosts, many RANGI transit proxies SHOULD be deployed in
   the transit networks and each of them is dedicated to a bunch of

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   identifiers in a given AD scope and is responsible for translating
   packets from IPv6 and RANGI, and vice versa. For more details, please
   refer to the transit proxy mechanism defined in [RANGI-PROXY].

   2.8. Network Mobility

   To mitigate the registration burden on the ID->Locator mapping system
   triggered by network mobility, NEMO mechanism [RFC3963] is reused in
   RANGI to support network mobility. That is to say, the mobile router
   is responsible for updating its current locator on its home agent. As
   a result, network mobility event is transparent to the hosts inside
   that mobile network. Details about network mobility will be explored
   in the latter version of this draft.

3. Summary

   RANGI achieves almost all of goals set by RRG, which are listed as

   1) Routing Scalability: Scalability is achieved by separating
      identifiers from locators.

   2) Traffic Engineering: Hosts inside a multi-homed site can
      suggest the upstream ISP for outgoing and returned packets by
      using the appropriate source locator, while the local LDBRs have
      the final decision on the upstream ISP selection since they can
      perform site-controlled traffic-engineering through source locator

   3) Mobility and Multi-homing: Sessions will not be interrupted due to
      locator change in the case of mobility or re-homing.

   4) Simplified Renumbering: When changing providers, the local IPv4
      addresses of the site do not need to change. Hence the internal
      routers within the site don't need renumbering.

   5) Decoupling Location and Identifier: Obvious.

   6) Routing Stability: Since the locators are topologically
      aggregatable and the internal topology within the LD will not be
      disclosed outside, routing stability could be improved greatly.

   7) Routing Security: RANGI reuses existing routing system and does
      not introduce any new security risk into the routing system.

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   8) Incremental Deployability: RANGI allows an easy transition from
      IPv4 networks to IPv6 networks.  In addition, RANGI proxy allows
      RANGI-aware hosts to communicate to legacy IPv4 or IPv6 hosts,
      and vice-versa.

4. Security Considerations


5. IANA Considerations

   A specific prefix for host IDs needs to be assigned from the IPv6
   address space.

   Two new options in the Destination Option Header need to be assigned
   for the host ID and its corresponding parameter date structure

6. Acknowledgments

   The author would like to thank Raj Jain, Xuewei Wang and Dacheng
   Zhang for their valuable contributions. Thanks SHOULD also be given
   to Paul Francis, Lixia Zhang, Brain Carpenter, Dave Oran, Joel
   Halpern, and Tony Li for their insightful comments.

   This research project is partially funded by the National"863" Hi-
   Tech Program of China.

7. References

   [RAWS] D. Meyer, L. Zhang, and K. Fall. "Report from the IAB Workshop
             on Routing and Addressing", Internet draft, draft-iab-raws-
             report-01.txt, work in progress, February 2007.

   [GOALS] T. Li, "Design Goals for Scalable Internet Routing", draft-
             irtf-rrg-design-goals-01, July 2007.

   [RFC4423] R. Moskowitz and P. Nikander, "Host Identity Protocol (HIP)
             Architecture", RFC 4423, May 2006.

   [RFC3972] T. Aura, "Cryptographically Generated Addresses (CGA)",
             RFC3972, Mar 2005.

   [RFC3963]  V. Devarapalli, R. Wakikawa, A. Petrescu and P. Thubert
             "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
             January 2005.

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   [RFC5214] F. Templin, T. Gleeson, "Intra-Site Automatic Tunnel
             Addressing Protocol (ISATAP)", RFC 5214, March, 2008.

   [RFC2136] P. Vixie, S. Thomson, Y. Rekhter, J. Bound, "Dynamic
             Updates in the Domain Name System (DNS UPDATE)", RFC 2136,
             April 1997.

   [RFC2535] Eastlake, D., "Domain Name System Security Extensions",
             RFC 2535, March 1999.

   [RFC3007] B. Wellington, "Secure Domain Name System Dynamic Update",
             RFC 3007, November 2000.

   [H-DHT] L. Garces-Erice, E. Biersack, P. Felber, K. Ross, and G.
             Urvoy-Keller, "Hierarchical Peer-to-peer Systems", In Proc.
             Euro-Par 2003, Klagenfurt, Austria, 2003.

   [GSE] M. O'Dell, "GSE-An Alternative Addressing Architecture for
             IPv6", Internet-Draft, Feb 1997.

   [LNA] Hari Balakrishnan, Karthik Lakshminarayanan, Sylvia
             Ratnasamy,Scott Shenker, Ion Stoica and Michael Walfish, "A
             Layered Naming Architecture for the Internet", Proc. ACM
             SIGCOMM, Portland, Oregon, USA, August 30 - September 3,

   [RANGI-PROXY] X. Xu, "Transition Mechanisms for Routing Architecture
             for the Next Generation Internet (RANGI)", draft-xu-rangi-
             proxy-01.txt, July 2009.

Authors' Addresses

   Xiaohu Xu
   Huawei Technologies,
   No.3 Xinxi Rd., Shang-Di Information Industry Base,
   Hai-Dian District, Beijing 100085, P.R. China
   Phone: +86 10 82882573
   Email: xuxh@huawei.com