Network Working Group O. Troan, Ed. Internet-Draft cisco Intended status: Standards Track October 24, 2011 Expires: April 26, 2012 Mapping of Address and Port (MAP) draft-mdt-softwire-mapping-address-and-port-00 Abstract This document describes a generic mechanism for mapping between an IPv4 prefix, address or parts thereof, and transport layer ports and an IPv6 prefix or address. 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 April 26, 2012. Copyright Notice Copyright (c) 2011 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. Troan Expires April 26, 2012 [Page 1] Internet-Draft MAP October 2011 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Mapping Rules . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Port mapping algorithm . . . . . . . . . . . . . . . . . . 6 4.2. Basic mapping rule - IPv4 address and port assignment . . 7 4.3. Forwarding mapping rule - from address and port to IPv6 address . . . . . . . . . . . . . . . . . . . . . . . 8 4.4. Default mapping rule - from address and port to BR . . . . 8 5. Use of the IPv6 Interface identifier . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . . 10 10.2. Informative References . . . . . . . . . . . . . . . . . . 10 Appendix A. Requirements . . . . . . . . . . . . . . . . . . . . 13 Appendix B. Deployment considerations . . . . . . . . . . . . . . 15 B.1. Flexible Assigment of Port Range . . . . . . . . . . . . . 15 B.2. Traffic Classification . . . . . . . . . . . . . . . . . . 15 B.3. Prefix Delegation Deployment . . . . . . . . . . . . . . . 15 B.4. Coexisting Deployment . . . . . . . . . . . . . . . . . . 15 B.5. Friendly to Network Provisioning . . . . . . . . . . . . . 16 B.6. Enable privacy addresses . . . . . . . . . . . . . . . . . 16 B.7. Facilitating 4v6 Service . . . . . . . . . . . . . . . . . 16 B.8. Independency with IPv6 Routing Planning . . . . . . . . . 16 B.9. Optimized Routing Path . . . . . . . . . . . . . . . . . . 17 Appendix C. Guidelines for Operators . . . . . . . . . . . . . . 17 C.1. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 17 C.2. Understanding address formats: their difference and relevance . . . . . . . . . . . . . . . . . . . . . . . . 17 C.3. A generic logic of working with MAP . . . . . . . . . . . 20 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 21 Troan Expires April 26, 2012 [Page 2] Internet-Draft MAP October 2011 1. Introduction The mechanism of mapping IPv4 addresses in IPv6 address has been described in numerous mechanisms dating back to [RFC1933] from 1996. The Automatic tunneling mechanism described in RFC1933, assigned a globally unique IPv6 address to a host by combining the hosts IPv4 address with a well known IPv6 prefix. Given an IPv6 packet with an destination address with an embedded IPv4 address, a node could automatically tunnel this packet by extracting the IPv4 tunnel end- point address from the IPv6 destination address. There are numerous variations of this idea, described in 6over4 [RFC2529], ISATAP [RFC5214] and 6rd [RFC5969]. The differences are the use of well known IPv6 prefixes, or Service Provider assigned IPv6 prefixes, and the exact position of the IPv4 bits embedded in the IPv6 address. Teredo [RFC4380] added a twist to this to achieve NAT traversal by also encoding transport layer ports into the IPv6 address. 6rd to achieve more efficient encoding, allowed for only an IPv4 address suffix to be embedded, with the IPv4 prefix being deducted from other provisioning mechanisms. NAT-PT [RFC2766](deprecated) combined with a DNS ALG used address mapping to put NAT state, namely the IPv6 to IPv4 binding encoded in an IPv6 address. This characteristic has been inherited by NAT64 [RFC6146] and DNS64 [RFC6147] which rely on an address format defined in [RFC6052]. [RFC6052] specifies the algorithmic translation of an IPv6 address to IPv4 address suffix to be embedded, with the deducted from other provisioning mechanisms. DNS ALG used address IPv4 binding encoded in it a corresponding IPv4 address, and vice versa. In particular, [RFC6052] specifies the address format to build IPv4- converted and IPv4-translatable IPv6 addresses. RFC6052 discusses the transport of the port range information in an IPv4-embedded IPv6 address but the conclusion was the following (excerpt from [RFC6052]): "There have been proposals to complement stateless translation with a port-range feature. Instead of mapping an IPv4 address to exactly one IPv6 prefix, the options would allow several IPv6 nodes to share an IPv4 address, with each node managing a different range of ports. If a port range extension is needed, could be defined later, using bits currently reserved as null in the suffix." The commonalities of all these mechanisms are: o Provisions an IPv6 address for a host or an IPv6 prefix for a site o Algorithmic or implicit address resolution for tunneling or encapsulation. Given an IPv6 destination address, an IPv4 tunnel endpoint address can be calculated. Likewise for translation, an IPv4 address can be calculated from an IPv6 destination address Troan Expires April 26, 2012 [Page 3] Internet-Draft MAP October 2011 and vice versa. o Embedding of an IPv4 address or part thereof and optionally transport layer ports into an IPv6 address. In the later phases of IPv4 to IPv6 migration, IPv6 only networks will be common, while there will still be a need for residual IPv4 deployment. This document describes a more generic mapping of IPv4 to IPv6 that can be used both for encapsulation (IPv4 over IPv6) and for translation between the two protocols. Just as the IPv6 over IPv4 mechanisms refereed to above, the residual IPv4 over IPv6 mechanisms must be capable of: o Provisioning an IPv4 prefix, an IPv4 address or a shared IPv4 address. o Algorithmically map between an IPv4 prefix, IPv4 address or a shared IPv4 address and an IPv6 address. This document describes delivery of IPv4 unicast service across an IPv6 infrastructure. IPv4 multicast is not considered further in this document. The unified mapping scheme described here supports translation mode, encapsulation mode, in both mesh and hub and spoke topologies. Other work that has motivated the work on a unified mapping mechanism for translation and encapsulation are: [I-D.sun-softwire-stateless-4over6] [I-D.murakami-softwire-4v6-translation] [I-D.despres-softwire-4rd-addmapping] [I-D.chen-softwire-4v6-add-format] [I-D.bcx-address-fmt-extension] [I-D.mrugalski-dhc-dhcpv6-4rd] [I-D.boucadair-dhcpv6-shared-address-option] [I-D.despres-softwire-sam] [I-D.chen-softwire-4v6-pd] [I-D.boucadair-softwire-stateless-requirements] [I-D.dec-stateless-4v6] [I-D.boucadair-behave-ipv6-portrange] [I-D.bsd-softwire-stateless-port-index-analysis] [I-D.despres-softwire-stateless-analysis-tool] [I-D.mrugalski-dhc-dhcpv6-4rd] [I-D.xli-behave-divi-pd] [I-D.murakami-softwire-4rd] [I-D.mrugalski-dhc-dhcpv6-4rd]. In particular the architecture of shared IPv4 address by distributing the port space is described in [RFC6346]. The corresponding stateful solution DS-lite is described in [RFC6333] Requirements and deployment considerations are documented in appendix A to C. These are kept in the document for informational purposes for now, but are in no way to be considered normative. Troan Expires April 26, 2012 [Page 4] Internet-Draft MAP October 2011 2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 3. Terminology MAP domain: A set of MAP CEs and BRs connected to the same virtual link. A service provider may deploy a single MAP domain, or may utilize multiple MAP domains. MAP Rule A set of parameters describing the mapping between an IPv4 prefix, IPv4 address or shared IPv4 address and an IPv6 prefix or address. Each MAP node in the domain has the same set of rules. MAP Border Relay (BR): A MAP enabled router managed by the service provider at the edge of a MAP domain. A Border Relay router has at least an IPv6-enabled interface and an IPv4 interface connected to the native IPv4 network. A MAP BR may also be referred to simply as a "BR" within the context of MAP. MAP Customer Edge (CE): A device functioning as a Customer Edge router in a MAP deployment. In a residential broadband deployment, this type of device is sometimes referred to as a "Residential Gateway" (RG) or "Customer Premises Equipment" (CPE). A typical MAP CE adopting MAP rules will serve a residential site with one WAN side interface, one or more LAN side interfaces. A MAP CE may also be referred to simply as a "CE" within the context of MAP. Shared IPv4 address: An IPv4 address that is shared among multiple CEs. Each node has a separate part of the transport layer port space; denoted as a port set. Only ports that belong to the assigned range can be used for communication. End user IPv6 prefix: The IPv6 prefix assigned to an End user CE by other means than MAP itself. MAP IPv6 address: The IPv6 address used to reach the MAP function of a CE from other CE's and from BR's. Troan Expires April 26, 2012 [Page 5] Internet-Draft MAP October 2011 Port-set ID (PSID): Algorithmically identifies a set of ports exclusively assigned to the CE. Rule IPv6 prefix: An IPv6 prefix assigned by a Service Provider for a mapping rule. Rule IPv4 prefix: An IPv4 prefix assigned by a Service Provider for a mapping rule. IPv4 Embedded Address (EA) bits: The IPv4 EA-bits in the IPv6 address identify an IPv4 prefix/address (or part thereof) or a shared IPv4 address (or part thereof and a port set identifier. 4. Mapping Rules A MAP node is provisioned with one or more mapping rules. Mapping Rules consists of the following items: o Rule IPv6 prefix o Rule IPv4 prefix o Port set parameters Mapping rules are used somewhat differently depending on its function. Every MAP node must be provisioned with a Basic mapping rule. This is used by the node to map from an end-user IPv6 prefix to an IPv4 prefix, address or shared IPv4 address. This same basic rule can also be used for forwarding (either encapsulation or translation), where an IPv4 destination address and optionally a destination port is mapped into an IPv6 address or prefix. Additional mapping rules can be specified to allow for e.g. multiple different IPv4 subnets to exist within the domain. Additional mapping rules are recognized by having a Rule IPv6 prefix different from the base End user IPv6 prefix. Traffic outside of the domain (IPv4 address not matching (using longest matching prefix) any Rule IPv4 prefix in the Rules database) will be forward using the Default Rule. The Default Rule maps outside destinations to the BR's IPv6 address or prefix. 4.1. Port mapping algorithm Note that various algorithms have been proposed to encode the port set. The effort to reach consensus on a port indexing algorithm meeting the requirements listed in the Requirements section is ongoing. The simplest port mapping algorithm one could imagine would be a simple CIDR style prefix. E.g. define a /6 worth of port space (out of the total 16 bits), giving the user 1024 ports. The issue with Troan Expires April 26, 2012 [Page 6] Internet-Draft MAP October 2011 that scheme is that it does not exclude the well known ports (0-1023). In a deployment where IPv6 address planning is independent of IPv4 address planning, that would result in some users being assigned that port space. To avoid that, Remi Despres invented a clever algorithm shown below. This algorithm uses an "infix" instead of a "prefix. By requiring that the 'Y' field (the first 6 bits) are larger then 0, results in all well known ports being excluded, while still sharing the ports fairly among all users. | Port range (16 bits) | +-------------------------+ | YYYY YY | P S I D | XX | +-------------------------+ | Y > 0 | Figure 1 4.2. Basic mapping rule - IPv4 address and port assignment | n bits | o bits | m bits | 128-n-o-m bits | +--------------------+---------+-----------+------------+----------+ | Domain IPv6 prefix | EA bits | subnet ID | interface ID | +--------------------+---------+-----------+-----------------------+ |<---IPv6 delegated prefix --->| Figure 2 The first half of the EA bits contain the IPv4 address, prefix or IPv4 suffix. The second half of the EA bits, in the case of a shared IPv4 address contains the PSID. | r bits | p bits | | q bits | +-------------+---------------------+ +------------+ | IPv4 prefix | IPv4 Address suffix | |Port Set ID | +-------------+---------------------+ +------------+ Figure 3 To create a complete IPv4 address, the IPv4 address suffix from the EA bits, are concatenated with a provisioned IPv4 prefix. Troan Expires April 26, 2012 [Page 7] Internet-Draft MAP October 2011 The PSID bits are not a prefix, but an infix. And is used to create a port range. | Port range (16 bits) | +-------------------------+ | YYYY YY | P S I D | XX | +-------------------------+ | Y > 0 | Figure 4 4.3. Forwarding mapping rule - from address and port to IPv6 address | 32 bits | | 16 bits | +--------------------------+ +-------------------+ | IPv4 destination address | | IPv4 dest port | +--------------------------+ +-------------------+ | p bits | | q bits | +------------------+ +------------+ | IPv4 addr suffix | |Port Set ID | +------------------+ +------------+ | n bits | o bits | m bits | 128-n-o-m bits | +--------------------+---------+-----------+------------+----------+ | Domain IPv6 prefix | EA bits | subnet ID | interface ID | +--------------------+---------+-----------+-----------------------+ |<---IPv6 delegated prefix --->| Figure 5 4.4. Default mapping rule - from address and port to BR TBD 5. Use of the IPv6 Interface identifier In an encapsulation solution, an IPv4 address and port is mapped to an IPv6 address. This is the address of the tunnel end point of the receiving MAP CE. For traffic outside the MAP domain, the IPv6 Troan Expires April 26, 2012 [Page 8] Internet-Draft MAP October 2011 tunnel end point address is the IPv6 address of the BR. As long as the interface-id is well known or provisioned and the same for all MAP nodes, it can be any interface identifier. E.g. ::1. When translating the destination IPv4 address is translated into a corresponding IPv6 address. In the case of traffic outside of the MAP domain, it is translated to the BR's IPv6 prefix. For the BR to be able to reverse the translation, the full destination IPv4 address must be encoded in the IPv6 address. There are multiple proposals for how to encode the IPv4 address, and if also the destinatino port or PSID should also be included. A couple of the proposals are shown in the figure below. Note: The encoding of the full IPv4 address into the interface identifier, both for the source and destination IPv6 addresses have been shown to be useful for troubleshooting. The format finally agreed upon here, will apply for both encapsulation and translation. Simple format similar to ISATAP: | 32 bits | 32 bits | +------------------+------------------+ | 02-00-5E-FE | IPv4 address | +------------------+------------------+ Figure 6 Parsable format including address length and PSID: <-8-><-------- L>=32 -------><48-L><8-> +---+----------------+------+-----+---+ | u | IPv4 address | PSID | 0 | L | +---+----------------+------+-----+---+ Figure 7 6. IANA Considerations This specification does not require any IANA actions. Troan Expires April 26, 2012 [Page 9] Internet-Draft MAP October 2011 7. Security Considerations There are no new security considerations pertaining to this document. 8. Contributors The members of the MAP design team are: Mohamed Boucadair, Gang Chen, Wojciech Dec, Congxiao Bao, Xiaohong Deng, Jouni Korhonen, Xing Li, Maoke, Satoru Matsushima, Tomasz Mrugalski, Jacni Qin, Qiong Sun, Tina Tsou, Dan Wing, Leaf Yeh and Jan Zorz 9. Acknowledgements 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC6346] Bush, R., "The Address plus Port (A+P) Approach to the IPv4 Address Shortage", RFC 6346, August 2011. 10.2. Informative References [I-D.bcx-address-fmt-extension] Bao, C. and X. Li, "Extended IPv6 Addressing for Encoding Port Range", draft-bcx-address-fmt-extension-02 (work in progress), October 2011. [I-D.boucadair-behave-ipv6-portrange] Boucadair, M., Levis, P., Grimault, J., Villefranque, A., Kassi-Lahlou, M., Bajko, G., Lee, Y., Melia, T., and O. Vautrin, "Flexible IPv6 Migration Scenarios in the Context of IPv4 Address Shortage", draft-boucadair-behave-ipv6-portrange-04 (work in progress), October 2009. [I-D.boucadair-dhcpv6-shared-address-option] Boucadair, M., Levis, P., Grimault, J., Savolainen, T., and G. Bajko, "Dynamic Host Configuration Protocol (DHCPv6) Options for Shared IP Addresses Solutions", draft-boucadair-dhcpv6-shared-address-option-01 (work in progress), December 2009. Troan Expires April 26, 2012 [Page 10] Internet-Draft MAP October 2011 [I-D.boucadair-softwire-stateless-requirements] Boucadair, M., Bao, C., Skoberne, N., and X. Li, "Requirements for Extending IPv6 Addressing with Port Sets", draft-boucadair-softwire-stateless-requirements-00 (work in progress), September 2011. [I-D.bsd-softwire-stateless-port-index-analysis] Boucadair, M., Skoberne, N., and W. Dec, "Analysis of Port Indexing Algorithms", draft-bsd-softwire-stateless-port-index-analysis-00 (work in progress), September 2011. [I-D.chen-softwire-4v6-add-format] Chen, G. and Z. Cao, "Design Principles of a Unified Address Format for 4v6", draft-chen-softwire-4v6-add-format-00 (work in progress), October 2011. [I-D.chen-softwire-4v6-pd] Chen, G., Sun, T., and H. Deng, "Prefix Delegation in 4V6", draft-chen-softwire-4v6-pd-00 (work in progress), August 2011. [I-D.dec-stateless-4v6] Dec, W., Asati, R., Bao, C., Deng, H., and M. Boucadair, "Stateless 4Via6 Address Sharing", draft-dec-stateless-4v6-04 (work in progress), October 2011. [I-D.despres-softwire-4rd-addmapping] Despres, R., Qin, J., Perreault, S., and X. Deng, "Stateless Address Mapping for IPv4 Residual Deployment (4rd)", draft-despres-softwire-4rd-addmapping-01 (work in progress), September 2011. [I-D.despres-softwire-sam] Despres, R., "Stateless Address Mapping (SAM) - a Simplified Mesh-Softwire Model", draft-despres-softwire-sam-01 (work in progress), July 2010. [I-D.despres-softwire-stateless-analysis-tool] Despres, R., "Analysis of Stateless Solutions for IPv4 Service across IPv6 Networks - A synthetic Analysis Tool", draft-despres-softwire-stateless-analysis-tool-00 (work in progress), September 2011. [I-D.mrugalski-dhc-dhcpv6-4rd] Troan Expires April 26, 2012 [Page 11] Internet-Draft MAP October 2011 Mrugalski, T., "DHCPv6 Options for IPv4 Residual Deployment (4rd)", draft-mrugalski-dhc-dhcpv6-4rd-00 (work in progress), July 2011. [I-D.murakami-softwire-4rd] Murakami, T., Troan, O., and S. Matsushima, "IPv4 Residual Deployment on IPv6 infrastructure - protocol specification", draft-murakami-softwire-4rd-01 (work in progress), September 2011. [I-D.murakami-softwire-4v6-translation] Murakami, T., Chen, G., Deng, H., Dec, W., and S. Matsushima, "4via6 Stateless Translation", draft-murakami-softwire-4v6-translation-00 (work in progress), July 2011. [I-D.sun-softwire-stateless-4over6] Sun, Q., Xie, C., Cui, Y., Wu, J., Wu, P., Zhou, C., and Y. Lee, "Stateless 4over6 in access network", draft-sun-softwire-stateless-4over6-00 (work in progress), September 2011. [I-D.xli-behave-divi] Bao, C., Li, X., Zhai, Y., and W. Shang, "dIVI: Dual- Stateless IPv4/IPv6 Translation", draft-xli-behave-divi-03 (work in progress), July 2011. [I-D.xli-behave-divi-pd] Li, X., Bao, C., Dec, W., Asati, R., Xie, C., and Q. Sun, "dIVI-pd: Dual-Stateless IPv4/IPv6 Translation with Prefix Delegation", draft-xli-behave-divi-pd-01 (work in progress), September 2011. [RFC1933] Gilligan, R. and E. Nordmark, "Transition Mechanisms for IPv6 Hosts and Routers", RFC 1933, April 1996. [RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 Domains without Explicit Tunnels", RFC 2529, March 1999. [RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address Translation - Protocol Translation (NAT-PT)", RFC 2766, February 2000. [RFC3194] Durand, A. and C. Huitema, "The H-Density Ratio for Address Assignment Efficiency An Update on the H ratio", RFC 3194, November 2001. [RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Troan Expires April 26, 2012 [Page 12] Internet-Draft MAP October 2011 Network Address Translations (NATs)", RFC 4380, February 2006. [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, March 2008. [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) -- Protocol Specification", RFC 5969, August 2010. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, October 2010. [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", RFC 6146, April 2011. [RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van Beijnum, "DNS64: DNS Extensions for Network Address Translation from IPv6 Clients to IPv4 Servers", RFC 6147, April 2011. [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC 6333, August 2011. Appendix A. Requirements This list of requirements for a stateless mapping of address and ports solution may not be complete. The requirements are listed in no particular order, and they may be conflicting. R-1: To allow for a single user delegated IPv6 prefix to be used for native IPv6 service and for MAP, the representation of an IPv4 prefix, address or shared IPv4 address and PSID must be efficient. As an example it must be possible to represent a shared IPv4 address and PSID in 24 bits or less. (Given a typical prefix assignment of /56 to the end-user and a MAP IPv6 prefix of /32.) R-2: The IPv6 address format and mapping must be flexible, and support any placement of the embedded bits from IPv4 prefix/ address and port set in the IPv6 address. Troan Expires April 26, 2012 [Page 13] Internet-Draft MAP October 2011 R-3: Algorithm complexity. The mapping from an IPv4 address and port to an IPv6 address is done in the forwarding plane on MAP nodes. It is important that the algorithm is bounded and as efficient as possible. R-4: MAP must allow service providers to define their own address sharing ratio. MAP MUST NOT in particular restrict by design the possible address sharing ratio; ideally 1:1 and 1:65536 should be supported. The mapping must at least support a sharing ratio of 64, 1024 ports per end-user. R-5: The mapping may support deployments using differentiated port- ranges. That is, end-users are assigned different sized port- ranges and direct communication between MAP CEs are permitted. R-6: The mapping should support differentiated port ranges within a single shared IPv4 address. (i.e., be able to assign port ranges of different sizes to customers without requiring any per customer state to be instantiated in network elements involved in data transfer). R-7: The MAP solution should support excluding the well known ports 0-1023. R-8: It MUST be possible to assign well known ports to a CE. R-9: There must not be any dependency between IPv6 addressing and IPv4 addressing. With the exception where full IPv4 addresses or prefixes are encoded. Then IPv6 prefix assignment must be done so that martian IPv4 addresses are not assigned. R-10: The mapping must not require IPv4 routing to be imported in IPv6 routing. R-11: The mapping should support legacy RTP/RTCP compatibility. (Allocating two consecutive ports). R-12: The mapping may be UPnP 1.0 friendly. A UPnP client will keep asking for the next port (as in current port + 1) a scattered port allocation will be more UPnP friendly. R-13: For out of domain traffic the mapping must support embedding a full IPv4 address in the IPv6 interface identifier. This is required in the translation case. It also simplifies pretty printing and other operational tools. R-14: For Service Providers requiring to apply specific policies on per Address-Family (e.g., IPv4, IPv6), some provisioning tools (e.g., DHCPv6 option) may be required to derive in a deterministic way the IPv6 address to be used for the IPv4 traffic based on the IPv6 prefix delegated to the home network. R-15: It should/must/may be possible to use the same IPv6 prefix (/64) for native IPv6 traffic and MAPed traffic. R-16: When only one single IPv6 prefix is assigned for both native IPv6 communications and the transport of IPv4 packets, the IPv4-translatable IPv6 prefix MUST have a length less than /64. When distinct prefixes are used, this requirement is relaxed. Troan Expires April 26, 2012 [Page 14] Internet-Draft MAP October 2011 R-17: The same mapping must support both translation and encapsulation solutions. Appendix B. Deployment considerations Regarding MAP solutions, the community has granted to investigate encap/decap and translation for different deployment cases. A new designed solutions should not impact customary behavior on existing network nodes. below has listed some deployment considerations. B.1. Flexible Assigment of Port Range Different classes of customers would require port sets of different sizes. In the context of shared IPv4 addresses, some customers would be satisfied with an shared IPv4 addresses, while others may need to be assigned with a single IPv4 address or delegated with IPv4 prefixes shorter than 32 bits due to increasing traffic demands. MAP would allow such flexibilities to allocate different port- set sizes for satisfy different demands. B.2. Traffic Classification Usually, ISPs adopt traffic classification to ensure service quality for different classes of customers. This feature is also helpful for customer behavior monitoring and security protection. for example, DIA (Dedicated Internet Access) has been provided by operators for corporations to cater for their Internet communications needs. Service is made by means of the edge router features and key systems, like ACL(Access List Control) to classify different traffic. Five tuples would be identified from IP header and UDP/TCP header. Currently, it is very well supported in IPv4. Vendors are delivering or committed to support that feature for IPv6. In order to facilitating IPv6 deployment, 4v6 solution would support this feature on IPv6 plane. B.3. Prefix Delegation Deployment Prefix delegation is an important feature both for broadband and mobile network. In mobile network, prefix delegation is introduced in 3GPP network in Release 10. The deployment of PD would be supported in 4v6 case. Variable length of IPv6 prefix is assigned to CPE for deriving IPv4 information. B.4. Coexisting Deployment 4v6 solutions(i.e. encapsulation and translation) would not only coexist with each other, but also can harmonize with other deployment Troan Expires April 26, 2012 [Page 15] Internet-Draft MAP October 2011 cases. Here lists some coexisting cases. (Note: more coexisting cases are expected to be investigated in future.) o Case 1: Coexisting between 4v6 encapsulation and 4v6 translation o Case 2: Coexisting between 4v6 translation and NAT64 (Single Translation) o Case 3: Coexisting between 4v6 solutions and SLAAC B.5. Friendly to Network Provisioning Network management plane normally has an ability to to identify different users and the compatible with the address assignment techniques in the domain. 4v6 would conform to current practices on management plane. In 3GPP network, for example, only the IPv6 prefix is assigned to the devices, used to identify different users. And management plane for one family address is better than two, namely the operating platform does not need to manage both IPv4 and IPv6. Since only IPv6 prefix is assigned, 4v6 on the management plane is naturally conducted only via IPv6. B.6. Enable privacy addresses User privacy should be taken into account when 4v6 solution is deployed. Some security concern associated with non-changing IPv6 interface identifiers has been expressed in RFC4941[RFC4941]. Ability to change the interface identifier over time makes it more difficult for eavesdroppers and other information collectors to identify when different addresses used in different sessions actually correspond to the same node. B.7. Facilitating 4v6 Service Some ISPs may need to offer services in a 4v6 domain with a shared address, e.g. 4v6 node hosts FTP server. The service provisioning may require well-know port range(i.e. port range belong to 0-1023). MAP would provide operators with possibilities to generate a port range including the 0-1023. Afterwards, operators could decide to assign it to any requesting user. B.8. Independency with IPv6 Routing Planning The IPv6 routing is easier to plan if it's not impacted by the encoded IPv4 or port ID information. MAP would prohibit IPv4 routing imported in IPv6. Troan Expires April 26, 2012 [Page 16] Internet-Draft MAP October 2011 B.9. Optimized Routing Path MAP could achieve optimized routing path both for hub case and mesh case. Traffic in hub and spoke case could follow asymmetric routing, in which incoming routes would not be binded to a given border point but others geographically closed to traffic initiators. In mesh cases, traffic between CPEs could directly communicate without going through remote border point. Appendix C. Guidelines for Operators C.1. Terms 4pfx the index for an IPv4 prefix. ug-octet the octet consisting of 64-71 bits in the IPv6 address, containing the bits u and g defined by EUI-64 standard. Common prefix an aggregate decided by a domain for the MAP deployment. It is a subset of the operator's aggregates by its RIR or provider. IPv4 suffix the part of IPv4 address bits used for identifying CEs. Host suffix the IPv6 suffix assigning to an end system. NOTE: it doesn't mean this should be really configured on a certain interface of a host. MAP format the address mapping format defined by this document. RFC6052 format the address mapping format defined by [RFC6052] and its succeeding extensions (or updates) for port-space sharing C.2. Understanding address formats: their difference and relevance It is important for an operator to understand what the MAP is designed for and where it could be applied. MAP introduces an address format of embedding IPv4 information to IPv6 address. On the other hand, we also have [RFC6052] defines an address format with the similar property. With extending port-set id, it can also support address sharing among different CEs [I-D.xli-behave-divi]. What are their differences and relations? We present a common abstract format for them both, as is depicted in Fig.A-1. For the easy expression, we exclude the ug-octet, which is not concerned in this appendix. Troan Expires April 26, 2012 [Page 17] Internet-Draft MAP October 2011 |<----- 120 bits (IPv6 address excluding ug-octet) --------->| +-------------+------+-------------+------+-----------//-----+ |Common Prefix| 4pfx | IPv4 suffix | PSID | Host Suffix | +-------------+------+-------------+------+-----------//-----+ Figure C-1. Abstract view of MAP and RFC6052 formats Figure 8 Only two parts in Fig.A-1 are different for MAP and RFC6052 formats. We compare them in Fig.A-2 and following paragraphs. +----------------+--------------+------------+ | | MAP | RFC6052 | +----------------+--------------+------------+ | from IPv4 | coding with | same, w/o | | prefix to 4pfx | compression | change | +----------------+--------------+------------+ | Host | full v4.addr | padding to | | Suffix | or 4rd IID | zero | +----------------+--------------+------------+ Figure A-2. Difference between MAP and RFC6052 formats Figure 9 This comparison clarifies that the major role of full IPv4 address embedded in the RFC6052 format is replaced by the MAP's coded IPv4 prefix index and the uncoded IPv4 suffix. The following Fig.A-3 illustrates this relationship. Troan Expires April 26, 2012 [Page 18] Internet-Draft MAP October 2011 (delegated prefix in RFC6052 format, w/o rule) +-------------+-------------+-------------+------+ |Common Prefix| full IPv4 address (32bit) | PSID | +-------------+-------------+-------------+------+ : : : : +-------------+-------------+ 32 bits: | 4pfx | IPv4 suffix | : +-------------+-------------+ + : . . . : . . . : . . . +-----+-------------+ + m bits: |4pfx | IPv4 suffix | : (w/ rules) +-----+-------------+ : : : : +-------------+-----+-------------+------+ | Rule IPv6 Prefix | CE index | +-------------+-----+-------------+------+ (delegated prefix in MAP format) Fig.A-3. Relevance between MAP and RFC6052 formats Figure 10 Why is it needed to code the IPv4 prefix? Precisely speaking, it is not "to compress the IPv4 prefix" but "to establish correspondence between IPv6 delegated prefixes and the residual IPv4 prefixes." MAP is designed for IPv4 residual deployment, which refers to efficiently applying residual (not-yet-assigned) IPv4 addresses in response to IPv4 communication demands of the IPv6 network in deployment. Therefore, the delegated CE prefixes are determined prior to finding proper IPv4 address blocks in hand to be mapped to the CE index and the IPv4 prefix index as well as the Rule IPv6 prefix, respectively. Because the IPv6 delegation planning is independent of the IPv4 addressing, the /64 prefix is a canonical configuration for all IPv6 local network. It is highly impossible to directly match some IPv4 prefixes to the already-determined IPv6 prefixes, and therefore the prefixes have to be coded and typically it is a compression. If we have a short-enough Common Prefix, it is also possible to deploy a direct matching where 4pfx is equal to IPv4 prefix. Only in this case, the MAP format is as same as the RFC6052 format and the Troan Expires April 26, 2012 [Page 19] Internet-Draft MAP October 2011 rule set could be simplified to a unique rule for 0.0.0.0/0. Why does MAP copy IPv4 address in the suffix? The full IPv4 address copied in the suffix plays auxiliary roles. Although the compression makes full IPv4 address not directly appear in the IPv6 address, the delegated prefix is sufficient to extract the corresponding IPv4 address for the CE. However, this relies on the distribution of rules. Embedding the full IPv4 address again in the suffix helps simple processing at IPv6-to-IPv4 translator when utilizing MAP for double translation. It also helps in setting filters at middle boxes, with exposing the IPv4 full addresses dispatched to the CEs. Although MAP is designed for the residual deployment, it is also suitable for the objective of providing stateless encapsulation or double translation for the ever deployed IPv4 networks whose provider backbone has upgraded to IPv6. However, unlike the residual deployment, the latter case needs to introduce IPv4 routing entropy into the IPv6 routing infrastructure. C.3. A generic logic of working with MAP This section illustrate how we can use MAP in the operation of residual deployment. It starts from IPv6 address planning. (A) IPv6 considerations (A1) Determine the maximum number N of CEs to be supported, and, for generality, suppose N = 2^n. (A2) Choose the length x of IPv6 prefixes to be assigned to ordinary customers (e.g., x = 60). (A3) Multiply N by a margin coefficient K, a power of two (K = 2 ^ k), to take into account that: - Some privileged customers may be assigned IPv6 prefixes of length x', shorter than x, to have larger addressing spaces than ordinary customers, both in IPv6 and IPv4. - Due to the hierarchy of routable prefixes, many theoretically delegatable prefixes may not be actually delegatable (ref: host density ratio of [RFC3194]). (B) IPv4 considerations (B1) List all (non overlapping, not yet assigned to any in-running networks) IPv4 prefixes Hi that are available for IPv4 residual deployment. (B2) Take enough of them, among the shortest ones, to get a total space whose size M is a power of two (M = 2 ^ m), and includes a good proportion of the available IPv4 space. If the M < N, addresses should be shared by N CEs and thus each is shared by N/M = 2^(n - m) CEs with PSID length of (n - m). (B3) For each IPv4 prefix Hi of length hi, choose a "rule index", i.e., the 4pfx in Fig.C-1 and Fig.C-3, say Ri of length ri = m - (32 - hi). All these indexes must be non overlapping prefixes (e.g. 0, 10, 110, 111 for one /10, one /11, and two /12). (C) After (A) and (B), deriving the rule(s) (C1) Troan Expires April 26, 2012 [Page 20] Internet-Draft MAP October 2011 Derive the length c of the "Common prefix" C that will appear at the beginning of all delegated prefixes (c = x - (n + k)). (C2) Take any prefix for this C of length c that starts with a RIR-allocated IPv6 prefix. (C3) For each IPv4 prefix Hi, make a rule, in which the key is Hi, and the value is the Common prefix C followed by the Rule index Ri. Then this i-th rule's Rule IPv6 Prefix will have the length of (c + ri). If different sharing ratio is expected, we may partition all CEs into subsets and do (A) and (B) for each subset, determining the PSID length for them separately. NOTE: Applying MAP for the operation other than residual deployment (e.g., the IPv6 mapping for already-deployed old IPv4 CEs and subnets) can reference the above text but please pay attention to the differences in prerequisites and demands. The condition for the deployment feasibility is possibly different. Author's Address Ole Troan (editor) cisco Oslo Norway Email: ot@cisco.com Troan Expires April 26, 2012 [Page 21]