MIF Working Group Z. Cao Internet-Draft D. Liu Intended status: Informational China Mobile Expires: August 5, 2010 February 2010 IP Family Selection for MIF Host draft-cao-mif-ifs-01 Abstract This document attempts to summarize the problems that are not addressed by current default address selection algorithms. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 5, 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 Cao & Liu Expires August 5, 2010 [Page 1] Internet-Draft MIF IP Family Selection February 2010 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 BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Summary . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Problem 1: NAT64 or NAT44? . . . . . . . . . . . . . . . . 4 2.2. Problem #2: NAT464 or NAT46? . . . . . . . . . . . . . . . 4 2.3. Problem #3: Self-assigned or Shared Addresses . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 5. Normative References . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Cao & Liu Expires August 5, 2010 [Page 2] Internet-Draft MIF IP Family Selection February 2010 1. Introduction Default Address Selection algorithms defined in RFC3484 [RFC3484] specify default behavior for all IPv6 implementations. By default, IPv6 is preferred over IPv4 for dual stack host. Some specific scenarios in IP family selection have not been considered in RFC3484. This document attempts to summarize the problems regarding IP family selection. Cao & Liu Expires August 5, 2010 [Page 3] Internet-Draft MIF IP Family Selection February 2010 2. Problem Summary 2.1. Problem 1: NAT64 or NAT44? If a dual stack host is configured with a DNS64 server [DNS64] and communicates with an IPv4 only server, the synthesized AAAA record will be preferred over the A record. So the dual stack host will choose IPv6 to communicate with IPv4 and packets will go through the NAT64 translator instead of NAT44. Draft [DNS64-Config] identifies this problem and introduces serveral solutions to this problem. 2.2. Problem #2: NAT464 or NAT46? On a BIS/BIA enabled host, if the server is IPv4 only, the Extension Name Resolver will return a type A record to the application and normally IP traffic will go through the NAT64 gateway as in PNAT[I-D.huang-behave-pnat]. If the server is upgraded to dual stack, the ENR on the host will get both an A and an AAAA record. According to RFC3484 [RFC3484], the host will prefer communicating using the IPv6 address and translation will be conducted in NAT46. But problems arises for those applications that need ALG. There may need ALG for those applications on the host. If no ALG functions are available on the host, the communication will fail. So in this case, the BIA/BIS enabled host is desired to retain communicating. via NAT464. 2.3. Problem #3: Self-assigned or Shared Addresses RFC3484 should consider the effect of non-meaningful IPv4 address (in PNAT [I-D.huang-behave-pnat]) and IANA assigned shared IPv4 address in DS-Lite [I.D-GI-DSL], and define cope for these addresses. For example, the dual stack host has been assigned an IPv4 address (public or private), and has been assigned an IPv6 prefix and self- assigned IPv4 address, When the DNS returns an A record, the dual stack host should have a specific way to choose which IPv4 address is preferred. Suppose only an AAAA record is returned, on a BIA/BIS enabled host with only IPv4 application, the DNS resolver will return the mapped IPv4 address to the application. The source address selection algorithm is left to select an appropriate source address for communication. In this case, if the network assigned IPv4 address is selected, communication may fail. Cao & Liu Expires August 5, 2010 [Page 4] Internet-Draft MIF IP Family Selection February 2010 3. Security Considerations TBD. Cao & Liu Expires August 5, 2010 [Page 5] Internet-Draft MIF IP Family Selection February 2010 4. IANA Considerations This document does not require any IANA actions. Cao & Liu Expires August 5, 2010 [Page 6] Internet-Draft MIF IP Family Selection February 2010 5. Normative References [DNS64] Bagnulo, M., "DNS64: DNS extensions for Network Address Translation from IPv6 Clients to IPv4 Servers", December 2009, . [DNS64-Config] Wing, D., "DNS64 Resolvers and Dual-Stack Hosts", Oct 2009, . [I-D.huang-behave-pnat] Huang, B. and H. Deng, "Prefix NAT: Host based IPv6 translation", December 2009, . [I-D.huang-bia-bis] Huang, B., Deng, H., and T. Savolainen, "Dual Stack Hosts Using "Bump-in-the-API" (BIA)", October 2009, . [I-D.huang-bis-bis] Huang, B., Deng, H., and T. Savolainen, "Dual Stack Hosts using the "Bump-In-the-Stack" Technique (BIS)", October 2009, . [I.D-GI-DSL] Brockners, F. and S. Gundavelli, "Gateway Initiated Dual- Stack Lite Deployment", December 2009, . [NAT64] Bagnulo, M., "NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", draft-bagnulo-behave-nat64-03.txt (work in progress), March 2009. [RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003. Cao & Liu Expires August 5, 2010 [Page 7] Internet-Draft MIF IP Family Selection February 2010 Authors' Addresses Zhen Cao China Mobile Unit2, 28 Xuanwumenxi Ave,Xuanwu District Beijing 100053 China Email: zehn.cao@gmail.com Dapeng Liu China Mobile Unit2, 28 Xuanwumenxi Ave,Xuanwu District Beijing 100053 China Email: liudapeng@chinamobile.com Cao & Liu Expires August 5, 2010 [Page 8]