Distributed Mobility Management (DMM) J. Korhonen Internet-Draft Nokia Siemens Networks Updates: 4861,3484 (if approved) B. Patil Intended status: Standards Track Nokia Expires: September 12, 2012 S. Gundavelli Cisco March 11, 2012 IPv6 Prefix Mobility Management Properties draft-korhonen-dmm-prefix-properties-01.txt Abstract This specification defines an extension to the IPv6 Neighbor Discovery protocol and its Prefix Information Option. The Prefix Information Option is extended with flag bits that describe the mobility management properties associated to the prefix. This specification updates RFC4861 and also updates RFC3484 Source Address Selection algorithm. Requirements Language 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]. 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 September 12, 2012. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. Korhonen, et al. Expires September 12, 2012 [Page 1] Internet-Draft IPv6 Prefix Properties March 2012 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. Background and Motivation . . . . . . . . . . . . . . . . . . . 3 3. Option Formats . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Host Considerations . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Internal Data Structures . . . . . . . . . . . . . . . . . 6 4.2. Default Address Selection . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . . 7 Appendix A. Additions to the Socket Interface and the Protocol-Independent Nodename Translation . . . . . . 8 A.1. Socket Interface . . . . . . . . . . . . . . . . . . . . . 8 A.2. Protocol-Independent Nodename Translation . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Korhonen, et al. Expires September 12, 2012 [Page 2] Internet-Draft IPv6 Prefix Properties March 2012 1. Introduction This specification defines an extension to the IPv6 Neighbor Discovery protocol and its Prefix Information Option (PIO) [RFC4861]. The Prefix Information Option is extended with flag bits that describe the mobility management properties associated to the prefix, and at the same time defines corresponding source address selection hint flags to the IPv6 Socket API for Source Address Selection [RFC5014]. The IPv6 Socket API for Source Address Selection [RFC5014] already covers Mobile IPv6 [RFC6275] and allows selecting between a home address (HoA) and a care-of address (CoA). A mobile node (MN) with a client based mobility IP stack is supposed to know which prefixes are CoA(s) and/or HoA(s). The extensions to [RFC4861] are minimal in a sense that they do not define new functionality to any existing mobility protocol but instead add an explicit indication of network based mobility knowledge into the IPv6 stateless address autoconfiguration (SLAAC). This would allow for network based mobility solutions, such as Proxy Mobile IPv6 [RFC5213] or GTP [TS.29274] to explicitly indicate that their prefixes have mobility, and therefore, the MN IP stack can make an educated selection between prefixes that have mobility and those that do not. There is also a potential need to extend both [RFC3493] and [RFC5014] in order to provide required hooks into socket APIs. The underlying assumption is that a MN has multiple prefixes to choose from. Typically this means either the MN has multiple interfaces or an interface has been configured with multiple prefixes. This specification does not make a distinction between these alternatives and does not either make any assumptions how the possible transfer of a prefix is done between interfaces in the case a network based mobility solution is used. 2. Background and Motivation IP mobility and its centralized topological anchoring of IP addresses has known issues. For instance, non-optimal routing is a classical example. Another concerns include excessive tunneling, increased signaling due the maintenance of mobility related bindings, aggregation of traffic to centralized mobility anchor gateways and unnecessary IP mobility related state management for IP traffic that does not as such benefit from mobility. In general, it is observed that most applications do not need IP level mobility, and work just fine with "temporary" IP addresses that come and go. However, IP mobility still has its virtues making the applications unaware of mobility, and certain wireless mobile networking architecture make Korhonen, et al. Expires September 12, 2012 [Page 3] Internet-Draft IPv6 Prefix Properties March 2012 extensive use of network based IP mobility. In order to overcome some of the above issues, use of local resources and topologically local addressing could be enhanced. In many cases this would lead to use of multiple addresses of which some provide mobility and some do not. However, an end host has to have means to distinguish between addresses that provide mobility, and those that are short lived and usable only within a limited topological area. This specification provides extensions to IPv6 address management and source address selection so that end hosts (and their applications) can select a proper address for their needs. [to be enhanced] 3. Option Formats Neighbor Discovery messages include zero or more options, some of which may appear multiple times in the same message. Options should be padded when necessary to ensure that they end on their natural 64- bit boundaries. Figure 1 illustrates a Prefix Information Option [RFC4861] that is extended with flag bits describing the mobility properties of the prefix: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 3 | 4 | Prefix Length |L|A| Rsvd1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Valid Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Preferred Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | C | Reserved2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Prefix + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Extended Prefix Information Option Korhonen, et al. Expires September 12, 2012 [Page 4] Internet-Draft IPv6 Prefix Properties March 2012 'C' 2-bit flag field describing the mobility properties of the prefix. The following properties are defined: 00 No specific property associated to the prefix. The prefix is treated according to RFC4861. 01 The prefix may or may not provide network based mobility, and if mobility is provided that is only within a limited area. Therefore, the end host must be prepared that the prefix may become invalid abruptly before the valid or even the preferred lifetime expire. 10 The prefix provides network based mobility and should remain unchanged the valid lifetime of the prefix. 11 Reserved. Treated as '00' by the receiver. A common use case is to define 'C' flags when the 'A'=1 i.e. when Stateless Address AutoConfiguration (SLAAC) is used. However, it is possible to associate 'C' flags also to prefixes when 'A'=0. In cases when there are multiple learned prefixes with 'C' flags set to a non-zero value that can also be aggregated, then the longest prefix takes precedence. If the prefix lifetime(s) is set to infinity that does not override the prefix mobility properties indicated in 'C' flags. For instance, a prefix with an infinite lifetime but 'C' flags set to '01' indicate that the prefix is bound to change abruptly due a handover at some point of time. 'C' flags also define the prefix preference for an IP stack that understands the extensions defined in this specification. The IP stack SHOULD use the following preferences to supersede [I-D.ietf-6man-rfc3484bis] Source Address Selection Rule 8 when selecting a default source address among multiple choices and an application has not explicitly indicate what kind of source address it prefers: 00 Medium (default) preference. 01 High preference. 10 Low preference. 11 Reserved - MUST NOT be used. Korhonen, et al. Expires September 12, 2012 [Page 5] Internet-Draft IPv6 Prefix Properties March 2012 4. Host Considerations 4.1. Internal Data Structures The host internal data structures need to be extended with 'mobility property' flag information associated to the learned prefix and configured addresses. How this is accomplished is host implementation specific. It is also a host implementation issue how an application can learn or query mobility properties of an address or a prefix. One possibility is to provide such information through the socket API extensions (see discussion in Appendix A). Other possibilities include the use of e.g., ioctl() or NetLink [RFC3549] extensions. 4.2. Default Address Selection The 'mobility property' flags are only used as a hint. They do not affect the existing [I-D.ietf-6man-rfc3484bis] automatically. A specific rule to host's policy table has to be inserted by an application or some daemon process. Alternatively, an application can express its address mobility property preferences through the socket API extensions (see discussion in Appendix A), which means the socket library or middleware has to modify [I-D.ietf-6man-rfc3484bis] policy table or algorithm. 5. Security Considerations Existing Prefix Information Option related security considerations apply as described in [RFC4861] and [RFC4191]. A malicious node on the shared link could include such 'mobility property' flags in a Prefix Information Option causing the host to learn wrong information regarding the prefix and thus make misguided selection of prefixes on the link. Similarly a malicious middleman on the link could modify 'mobility property' flags in a Prefix Information Option causing misguided selection of prefixes. In order to avoid on-link attacks, SeND [RFC3971] can be used to reject Router Advertisements from potentially malicious nodes and guarantee integrity protection of the Router Advertisements. 6. IANA Considerations Section 3 defines a new flag bits (2 bit 'C' flag) to the IPv6 Neighbor Discovery protocol's Prefix Information Option [RFC4861]. 7. References Korhonen, et al. Expires September 12, 2012 [Page 6] Internet-Draft IPv6 Prefix Properties March 2012 7.1. Normative References [I-D.ietf-6man-rfc3484bis] Thaler, D., Draves, R., Matsumoto, A., and T. Chown, "Default Address Selection for Internet Protocol version 6 (IPv6)", draft-ietf-6man-rfc3484bis-01 (work in progress), March 2012. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. 7.2. Informative References [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. Stevens, "Basic Socket Interface Extensions for IPv6", RFC 3493, February 2003. [RFC3549] Salim, J., Khosravi, H., Kleen, A., and A. Kuznetsov, "Linux Netlink as an IP Services Protocol", RFC 3549, July 2003. [RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, November 2005. [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 Socket API for Source Address Selection", RFC 5014, September 2007. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support in IPv6", RFC 6275, July 2011. [TS.29274] 3GPP, "3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C)", 3GPP TS 29.060 8.11.0, December 2010. Korhonen, et al. Expires September 12, 2012 [Page 7] Internet-Draft IPv6 Prefix Properties March 2012 Appendix A. Additions to the Socket Interface and the Protocol- Independent Nodename Translation Following sections are for informational and discussion purposes only. This specification also describes non-normative extensions to both Socket Interface [RFC3493][RFC5014] and the Protocol-Independent Nodename Translation [RFC5014]. These socket APIs and DNS resolver APIs extension correspond to the Prefix Information option mobility properties flag bit settings. A.1. Socket Interface This specification extends the socket option IPV6_ADDR_PREFERENCES at the IPPROTO_IPV6 level. The following new flags are defined to query, alter or set the default rule of source address selection rules [I-D.ietf-6man-rfc3484bis]. They are also defined as a result of including the header: IPV6_PREFER_SRC_HNP /* Prefer Home Network Prefix derived IPv6 address as source */ IPV6_PREFER_SRC_HNP_TMP /* Prefer temoporary Home Network Prefix derived IPv6 address as source */ A.2. Protocol-Independent Nodename Translation the Default Address Selection [I-D.ietf-6man-rfc3484bis] document indicates possible implementation strategies for getaddrinfo(). The address selection hint flags for the getaddrinfo() specificed in this document extend the 'int ai_eflags' field in the struct addrinfo [RFC5014][RFC3493]. The IPV6 source address preference values (IPV6_PREFER_SRC_HNP and IPV6_PREFER_SRC_HNP_TMP) defined for the IPV6_ADDR_PREFERENCES socket option are also defined as address selection preference flags in header for the "ai_eflags" extended flag-set field of the addrinfo data structure. Similarly to [RFC5014], if contradictory flags, such as IPV6_PREFER_SRC_HOME and IPV6_PREFER_SRC_HNP*, are set in ai_eflags, the getaddrinfo() fails and returns the value EAI_BADEXTFLAGS. This error value MUST be interpreted into a descriptive text string when passed to the gai_strerror() function [RFC3493]. Korhonen, et al. Expires September 12, 2012 [Page 8] Internet-Draft IPv6 Prefix Properties March 2012 Authors' Addresses Jouni Korhonen Nokia Siemens Networks Linnoitustie 6 FIN-02600 Espoo Finland Email: jouni.nospam@gmail.com Basavaraj Patil Nokia 6021 Connection Drive Irving, TX 75039 USA Email: basavaraj.patil@nokia.com Sri Gundavelli Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: sgundave@cisco.com Korhonen, et al. Expires September 12, 2012 [Page 9]