Network Working Group G. Tsirtsis Internet-Draft V. Park Intended status: Standards Track Qualcomm Expires: May 5, 2007 H. Soliman Consultant November 2006 Dual Stack Mobile IPv4 draft-ietf-mip4-dsmipv4-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 May 5, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Tsirtsis, et al. Expires May 5, 2007 [Page 1] Internet-Draft Dual Stack Mobile IPv4 November 2006 Abstract This specification provides IPv6 extensions to the Mobile IPv4 protocol. The extensions allow a dual stack node to use IPv4 and IPv6 home addresses as well as to move between IPv4 and dual stack network infrastructures. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Non-Goals . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Implicit and Explicit Modes . . . . . . . . . . . . . . . 5 3. Extension Formats . . . . . . . . . . . . . . . . . . . . . . 6 3.1. IPv6 Prefix Extension . . . . . . . . . . . . . . . . . . 6 3.2. IPv6 Code Extension . . . . . . . . . . . . . . . . . . . 7 3.3. IPv6 Tunneling Mode Extension . . . . . . . . . . . . . . 8 4. Mobile IP Registrations . . . . . . . . . . . . . . . . . . . 10 4.1. Registration Request . . . . . . . . . . . . . . . . . . . 10 4.2. Registration Reply . . . . . . . . . . . . . . . . . . . . 10 4.3. Home Agent Considerations . . . . . . . . . . . . . . . . 11 4.3.1. IPv6 Packet Processing . . . . . . . . . . . . . . . . 12 4.3.2. Processing intercepted IPv6 Packets . . . . . . . . . 12 4.3.3. IPv6 Multicast Membership Control . . . . . . . . . . 14 4.4. Foreign Agent Considerations . . . . . . . . . . . . . . . 14 4.5. Mobile Node Considerations . . . . . . . . . . . . . . . . 15 4.6. Dynamic IPv6 Prefix allocation . . . . . . . . . . . . . . 16 4.6.1. Mobile IP Style Address Allocation . . . . . . . . . . 16 4.6.2. Prefix Delegation . . . . . . . . . . . . . . . . . . 17 4.7. Deregistration of IPv6 Prefix . . . . . . . . . . . . . . 17 4.8. Registration with a private CoA . . . . . . . . . . . . . 17 5. Security Considerations . . . . . . . . . . . . . . . . . . . 18 6. Changes since v00 . . . . . . . . . . . . . . . . . . . . . . 19 7. Aknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20 8. Normative References . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 Intellectual Property and Copyright Statements . . . . . . . . . . 23 Tsirtsis, et al. Expires May 5, 2007 [Page 2] Internet-Draft Dual Stack Mobile IPv4 November 2006 1. Requirements notation 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 [RFC2119]. Tsirtsis, et al. Expires May 5, 2007 [Page 3] Internet-Draft Dual Stack Mobile IPv4 November 2006 2. Introduction Mobile IPv4 [RFC3344] allows a mobile node with an IPv4 address to maintain communications while moving in an IPv4 network. Extensions defined in this document allow a node that has IPv4 and IPv6 addresses [RFC2460] to maintain communications with any of its addresses while moving in IPv4 or dual stack networks. Essentially, this specification separates the Mobile IPv4 signaling from the IP version of the traffic it tunnels. Mobile IPv4 with the present extensions remains a signaling protocol that runs over IPv4, and yet can set-up any combination of IPv4 and/or IPv6 over IPv4 tunnels. The aim is two-fold: On one hand, Mobile IPv4 with the present extensions becomes a powerful transition mechanism, allowing automated but controlled tunneling of IPv6 traffic over IPv4 tunnels. Dual stack nodes in dual stack home networks can now roam to and from legacy IPv4 networks, while IPv4 mobile nodes and networks can migrate to IPv6 without changing mobility management, and without upgrading all network nodes to IPv6 at once. On the other hand, and more importantly, it allows dual stack mobile nodes and networks to utilize a single protocol for the movement of both IPv4 and IPv6 stacks in the network topology. Note that features like Mobile IPv6 [RFC3775] style route optimization will not be possible with this solution as it still relies on Mobile IPv4 signaling, which does not provide route optimization. 2.1. Goals a. The solution supports the registration of IPv6 home address(es) and/or prefix(s) in addition to regular IPv4 home address registration b. The solution supports static and dynamic IPv6 home address(s)/ prefix(s) allocations c. The solution supports the above registrations with and without FA support Tsirtsis, et al. Expires May 5, 2007 [Page 4] Internet-Draft Dual Stack Mobile IPv4 November 2006 2.2. Non-Goals a. The solution does not provide support for IPv6 care-of address registration 2.3. Implicit and Explicit Modes As defined in NEMO [RFC3963], this specification also supports two modes of operation; the implicit mode and the explicit mode. In the implicit mode, the mobile node does not include a IPv6 Prefix Extensions in the Registration Request. The home agent can use any mechanism (not defined in this document) to determine the IPv6 Prefix(es) owned by the mobile node and to set up forwarding for these prefixes. In this mode of operation all traffic to and from the IPv6 prefixes MUST be tunneled over the mobile node to home agent tunnel and MUST be transparent to any foreign agent in the path. In the explicit mode, the mobile node includes one or more IPv6 Prefix extensions in the Registration Request. The rest of this specification is primarely defining the explicit mode. Tsirtsis, et al. Expires May 5, 2007 [Page 5] Internet-Draft Dual Stack Mobile IPv4 November 2006 3. Extension Formats The following extensions are defined according to this specification. 3.1. IPv6 Prefix Extension A new skippable extension to the Mobile IPv4 header in accordance to the short extension format of [RFC3344] is defined here. This extension contains a mobile IPv6 network prefix and its prefix length. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Sub-Type | Prefix Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Mobile IPv6 Network Prefix + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: IPv6 Prefix Extension Type DSMIPv4 Extensions (skippable type range to be assigned by IANA) Length 20 Sub-Type 1 (IPv6 Prefix) Prefix Length Indicates the prefix length of the prefix included in the Mobile Network IPv6 Prefix Field Mobile IPv6 Network Prefix Tsirtsis, et al. Expires May 5, 2007 [Page 6] Internet-Draft Dual Stack Mobile IPv4 November 2006 A sixteen-byte field containing the Mobile IPv6 Network Prefix 3.2. IPv6 Code Extension A new skippable extension to the Mobile IPv4 header in accordance to the short extension format of [RFC3344] is defined here. This extension defines a mobile IPv6 network prefix and its prefix length, as well as a code. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Sub-Type | Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Length | Reserved | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | | + + | | + Mobile IPv6 Network Prefix + | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: IPv6 Code Extension Type DSMIPv4 Extensions (skippable type range to be assigned by IANA) Length 22 Sub-Type 2 (IPv6 Prefix Acknowledgment) Code A value indicating the result of the registration request with respect to the IPv6 home address registration. See below for currently defined Codes. Prefix Length Tsirtsis, et al. Expires May 5, 2007 [Page 7] Internet-Draft Dual Stack Mobile IPv4 November 2006 Indicates the prefix length of the prefix included in the Mobile Network IPv6 Prefix Field Reserved Set to 0 by the sender, ignored by the receiver Mobile IPv6 Network Prefix A sixteen-byte field containing the Mobile IPv6 Network Prefix The following values are defined for use as a Code value in the above extension 0 registration accepted, IPv6 to be tunneled to HoA 1 registration accepted, IPv6 to be tunneled to CoA 8 registration rejected, reason unspecified 9 registration rejected, administratively prohibited 10 registration rejected, not home subnet 11 registration rejected, Duplicate Address Detection failed Note that a registration reply that does not include an IPv6 code extension indicates that the home agent does not support IPv6 extensions and thus has ignored such extensions in the registration request. 3.3. IPv6 Tunneling Mode Extension A new skippable extension to the Mobile IPv4 header in accordance to the short extension format of [RFC3344] is defined here. The presence of this extension in a registration request message indicates that the sender supports the IPv6 extensions specified in this document. By including this extension in a registration request the sender indicates that IPv6 traffic can be tunneled to the mobile's CoA. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Sub-Type | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Tsirtsis, et al. Expires May 5, 2007 [Page 8] Internet-Draft Dual Stack Mobile IPv4 November 2006 Figure 3: IPv6 Tunneling Mode Extension Type DSMIPv4 Extensions (skippable type range to be assigned by IANA) Length 4 Sub-Type 3 (IPv6 Tunneling Mode Extension) Reserved Set to 0 by the sender, ignored by the receiver Tsirtsis, et al. Expires May 5, 2007 [Page 9] Internet-Draft Dual Stack Mobile IPv4 November 2006 4. Mobile IP Registrations 4.1. Registration Request A mobile node MAY include one or more IPv6 prefix extensions defined in this specification in a registration request. A mobile node MAY include exactly one IPv6 tunneling mode extension when it uses the collocated care-of address mode of [RFC3344]. When IPv6 prefix and/or IPv6 tunneling mode extensions are used by the mobile IP client, they MUST be placed after the registration request header and before the mobile - home authentication extension so they MUST be included in the computation of any authentication extension. A foreign agent MAY include exactly one IPv6 tunneling mode extension defined in the specification in a registration request when a mobile node registered via that foreign agent. When the IPv6 tunneling mode extension is used by a foreign agent it MUST be placed after the mobile - home authentication extensions and before the foreign - home authentication extension so they MUST be included in the computation of the foreign - home authentication extension when one exists. 4.2. Registration Reply The mechanism described in the specification depends on skippable extensions. For that reason, a registration reply that does not include an IPv6 code extension, in response to a registration request that included an IPv6 prefix extension, indicates that the home agent does not support IPv6 extensions and has ignored the request. If an IPv6 code extension is included in a registration reply then, the extension indicates the success or failure of the IPv6 prefix registration. The IPv6 code extension does NOT affect in any way, the code value in the registration reply header. Note that a negative IPv6 code extension has the same effect with not including such extension at all in the sense that in both cases the mobile node and foreign agent must act as if the corresponding request of IPv6 prefix registration was rejected. Of course, the inclusion of the IPv6 code extension allows the home agent to indicate why a given request was rejected. Tsirtsis, et al. Expires May 5, 2007 [Page 10] Internet-Draft Dual Stack Mobile IPv4 November 2006 4.3. Home Agent Considerations The dual stack home agent defined in this specification is a Mobile IPv4 [RFC3344] Home Agent, in that it MUST operate as defined in MIPv4 [RFC3344]. In addition to that the following mechanism are defined in this specification. For each IPv6 prefix extension included in a valid registration request, a home agent that supports this specification SHOULD include a corresponding IPv6 code extension in the registration reply message. For each accepted IPv6 prefix the home agent MUST decide the tunneling mode that it is going to use and set the Code field of the IPv6 code extension to the appropriate value. The omission of a given code extension is equivalent to the rejection of the corresponding IPv6 prefix extension. The IPv6 prefix field of each of the IPv6 code extensions included in the registration reply MUST match a corresponding IPv6 prefix field of the IPv6 prefix extension included in the corresponding registration request message. If the IPv6 home address included in a IPv6 Prefix Extension is not an on-link IPv6 address with respect to the home agent's current Prefix List or a prefix it is configured to serve, the home agent MUST reject the IPv6 Prefix Extension and SHOULD return an IPv6 Code Extension with rejection code "not home subnet" in the Registration Reply to the mobile node. Else, if the home agent chooses to reject the Registration Request for any other reason (e.g., insufficient resources to serve another mobile node as a home agent), then the home agent SHOULD return a Registration Reply to the mobile node, in which the Code field is set to an appropriate value to indicate the reason for the rejection, according to MIPv4 [RFC3344]. Unless this home agent already has a binding for the given IPv6 home address, the home agent MUST perform Duplicate Address Detection [draft-ietf-ipv6-rfc2462bis-08.txt] on the mobile node's home IPv6 link before returning the Registration Reply. This ensures that no other node on the home link was using the mobile node's IPv6 home address when the Registration Request arrived. If this Duplicate Address Detection fails for the given IPv6 home address or an associated link local address, then the home agent MUST reject the IPv6 Prefix Extension and SHOULD return a Registration Reply to the mobile node, in which the Code field of a corresponding IPv6 Code Extension is set to "Duplicate Address Detection failed". When the home agent sends a successful Registration Reply to the mobile node, with the Code field of a corresponding IPv6 Code Extension set to one of the "registration accepted" values, the home agent assures to the mobile node that its IPv6 address(es) will be kept unique by the home Tsirtsis, et al. Expires May 5, 2007 [Page 11] Internet-Draft Dual Stack Mobile IPv4 November 2006 agent for as long as the lifetime was granted for the binding. Note that for IPv6 prefixes (rather than addresses), the home agent does not have to perform Duplicate Address Detection. 4.3.1. IPv6 Packet Processing Dual stack home agents MUST use Proxy Neighbor Discovery [draft-ietf-ipv6-2461bis-09.txt]on behalf of the nodes they serve. This allows the home agent to receive IPv6 packets addressed to the mobile node's registered IPv6 address(es). The dual stack home agent MUST act as defined in MIPv6 [RFC3775], Section 10.4.1. in order to intercept IPv6 packets for the mobile nodes it serves. The home agent MUST advertise reachability for the registered prefixes as defined in NEMO [RFC3963], section 6.3. 4.3.2. Processing intercepted IPv6 Packets A dual stack home agent that supports the IPv6 extensions defined in this specification, MUST keep track of the following IPv6 related state for the mobile nodes it supports, in addition to what state is defined in [RFC3344]. - Registered IPv6 prefix(es) and prefix length(s) - Tunneling mode for IPv6 traffic: - Tunnel to IPv4 HoA and accept IPv6 tunneled from IPv4 HoA - Tunnel to CoA and accept IPv6 tunneled from CoA Even if the tunnel for IPv4 traffic terminates at a different point than the tunnel for IPv6 traffic (mobile node's CoA vs HoA), both tunnels MUST use the tunneling mechanism negotiated by the Mobile IP header as defined in MIPv4 [RFC3344]. A home agent that supports this specification MUST be able to defend IPv4 and IPv6 packets destined to registered mobile nodes according to mechanisms described in MIPv4 [RFC3344] and MIPv6 [RFC3775] specifications. Tunneling mode selection for IPv6 traffic depends on the following parameters in a successful registration request: 1) Registration request is received with one or more IPv6 prefix Tsirtsis, et al. Expires May 5, 2007 [Page 12] Internet-Draft Dual Stack Mobile IPv4 November 2006 extensions. An IPv6 tunneling mode extension is not included. All IPv6 packets destined to the registered IPv6 prefix(es) MUST be tunneled by the home agent to the registered IPv4 home address of the mobile. Additionally, the home agent MUST be prepared to accept reverse tunneled packets from the IPv4 home address of the mobile encapsulating IPv6 packets sent by that mobile. 2) Registration request is received with one or more IPv6 prefix extensions. An IPv6 tunneling mode extension is included. All IPv6 packets destined to the registered IPv6 home address(s) SHOULD be tunneled by the home agent to the registered care-of address of the mobile node. Additionally, the home agent SHOULD be prepared to accept reverse tunneled packets from the care-of address of the mobile encapsulating IPv6 packets sent by that mobile. The home agent MAY ignore the presence of the IPv6 tunneling mode extension and act as in case (1) above. Packets addressed to the mobile node's IPv6 link-local address MUST NOT be tunneled to the mobile node. Instead, these packets MUST be discarded and the home agent SHOULD return an ICMPv6 Destination Unreachable, Code 3, message to the packet's Source Address (unless this Source Address is a multicast address). The home agent SHOULD check that all IPv6 packets received from the mobile client over a tunnel from the home address or the care-of address, include a source address that falls under the registered IPv6 prefix(es) for that mobile node. If the source address of the tunnel is not the registered IPv4 care-off address or the registered IPv4 home addresses, the packet SHOULD be dropped. If the source address of the encapsulated packet does not match any of the registered home addresses and/or prefixes the packet SHOULD be dropped. Interception and tunneling IPv6 multicast addressed packets on the home network are only done if the home agent supports multicast group membership control messages from the mobile node as described in the next section. Multicast IPv6 packets addressed to a multicast address with link-local scope [RFC4291], to which the mobile node is subscribed, MUST NOT be tunneled to the mobile node. These packets SHOULD be silently discarded (after delivering to other local multicast recipients). Multicast packets addressed to a multicast address with a scope larger than link-local, but smaller than global (e.g., site- local and organization-local [RFC4291], to which the mobile node is subscribed, SHOULD NOT be tunneled to the mobile node. Multicast packets addressed with a global scope, to which the mobile node has successfully subscribed, MUST be tunneled to the mobile Tsirtsis, et al. Expires May 5, 2007 [Page 13] Internet-Draft Dual Stack Mobile IPv4 November 2006 node. 4.3.3. IPv6 Multicast Membership Control IPv6 multicast membership control is provided as defined in MIPv6 [RFC3775], Section 10.4.3. The only clarification required for the purpose of this specification is that all MLD [RFC2710] or MLDv2 [RFC3810] messages between the mobile node and the home agent MUST be tunneled between the mobile node and the home agent, bypassing the foreign agent. 4.4. Foreign Agent Considerations A dual stack foreign agent that supports the IPv6 extensions defined in this specification MUST keep track of the following IPv6 related state for the mobile IP clients it supports in addition to what state is defined in [RFC3344]. - IPv6 Prefix(es) and Prefix Length(s) - Tunneling mode for IPv6 traffic: - accept IPv6 encapsulated in IPv4 and reverse tunnel IPv6 - IPv6 is tunneled directly to the IPv4 HoA so the foreign agent will not provide encapsulation/decapsulation services for IPv6 traffic for this mobile. When a foreign agent receives a registration request with IPv6 prefix extension(s) it has the following choices: 1) Ignore the extension(s). The registration request is forwarded as is to the home agent. The foreign agent SHOULD operate according to MIPv4 [RFC3344] 2) Attach an IPv6 tunneling mode extension to the registration request sent to the home agent. The foreign agent MUST be prepared to de-capsulate and deliver IPv6 packets, in addition to the IPv4 packets, sent to it in the home agent to foreign agent tunnel for that mobile node. The foreign agent MUST be prepared to receive IPv6 packets from the mobile node, in addition to IPv4 packets. All IPv6 traffic MUST be reverse tunneled to the home agent by the foreign agent irrespectively from the reverse tunneling setting negotiated for IPv4 packets by mechanisms in [RFC3024] Tsirtsis, et al. Expires May 5, 2007 [Page 14] Internet-Draft Dual Stack Mobile IPv4 November 2006 If the foreign agent sets the R flag included in the mobility agent advertisement [RFC3344] and a mobile node uses the collocated address mode of operation, the foreign agent MUST NOT include an IPv6 tunneling mode extension in the registration request messages sent from that mobile node. 4.5. Mobile Node Considerations A dual stack mobile node that supports the extensions described in this document MAY use these extensions to register its IPv6 home address(es) and/or prefix(es) while moving between access routers. The mobile node MAY include one or more IPv6 Prefix extension(s) in the registration request. In this case the mobile MUST take the following action depending on the extensions included in the registration reply it receives in response to the registration request: 1) The registration reply does not include any IPv6 code extensions. The mobile node SHOULD assume that the home agent does not support the extensions defined in this specification. The mobile node SHOULD continue to operate according to MIPv4 [RFC3344]. 2) The registration reply includes one or more IPv6 code extensions. The mobile node MUST match each IPv6 code extension with one of the IPv6 prefix extensions earlier included in the corresponding registration request message. If a matching IPv6 code extension is not included for one or more of corresponding IPv6 prefix extensions included in the registration request message, the mobile node SHOULD assume that these IPv6 prefixes are rejected. For each matching IPv6 code extensions the mobile node MUST inspect the Code field. If the field is set to a rejection code then the corresponding IPv6 prefix registration has been rejected. If the Code field is set to an acceptance code then the corresponding IPv6 prefix registration has been accepted. If the Code field is set to "0" then the mobile node MUST be prepared to send/receive IPv6 packets encapsulated in the bidirectional tunnel between the home agent address and the registered IPv4 home address of the mobile node. Tsirtsis, et al. Expires May 5, 2007 [Page 15] Internet-Draft Dual Stack Mobile IPv4 November 2006 If the Code field is set to "1" then the mobile node MUST act as follows: - If the care-of address mode of operation is used, the mobile node MUST be prepared to send/receive IPv6 traffic on its interface natively, unless reverse tunnel has been negotiated in which case both IPv4 and IPv6 traffic MUST be reverse tunneled [RFC3024]. IPv6 traffic is reverse tunneled over the same tunnel used by IPv4 traffic. - If the collocated care-of address mode is used, the mobile node MUST be prepared to send/receive IPv6 packets over the bidirectional tunnel between the home agent address and its collocated care-of address. The mobile node SHOULD include exactly one IPv6 tunneling mode extension if it uses the collocated care-of address model and it wants to request that IPv6 packets are tunneled to its collocated care-of address. If the mobile node uses the collocated care-of address model but it does not include the IPv6 tunneling mode extension the home agent will tunnel IPv6 traffic to the mobile client's home address. The mobile node MUST NOT include an IPv6 tunneling mode extension if it uses the care-of address mode of operation. Note that if the mobile includes an IPv6 tunneling mode extension in this case, IPv6 packets could be tunneled to the FA by the HA. The FA is then likely to drop them since it will not have appropriate state to process them. 4.6. Dynamic IPv6 Prefix allocation 4.6.1. Mobile IP Style Address Allocation A mobile node may include one or more IPv6 prefix extensions with the IPv6 prefix field set to zero. The mobile node MAY set the prefix length field of such extensions to zero or to a length of its choice as a hint to the home agent. Such IPv6 prefix extensions indicate that the mobile client requests IPv6 address(es) and prefix(es) to be assigned to it by the home agent. A home agent receiving an IPv6 prefix extension with the IPv6 prefix field set to zero MAY return an IPv6 Code extension with the IPv6 prefix field set to the IPv6 prefix allocated to the mobile node. The length of that prefix is at the discretion of the home agent. The home agent may take into account the prefix length hint if one is included in the IPv6 prefix extension. A mobile node MAY include one or more IPv6 prefix extensions with the IPv6 Prefix field set to ::interface_identifier, where Tsirtsis, et al. Expires May 5, 2007 [Page 16] Internet-Draft Dual Stack Mobile IPv4 November 2006 interface_identifier is the unique layer 2 address of the client. In this case the prefix length field SHOULD be set to 128. The home agent MAY in this case return an IPv6 Code extension with: - the IPv6 prefix field set to PREFIX:: and the prefix length field set to the desired prefix length value. - the IPv6 prefix field set to PREFIX::interface_identifier and the prefix length field set to 128. 4.6.2. Prefix Delegation An alternative way of dynamically allocating IPv6 prefixes is described in this section. A dual stack mobile node MAY use Prefix Delegation as defined in [draft-ietf-nemo-dhcpv6-pd-01.txt] to get a prefix. In that case the mobile MUST first register its IPv4 home address as per MIPv4 [RFC3344]. When that is done the mobile can generate a link local IPv6 address and use it to send DHCP messages according to [draft-ietf-nemo-dhcpv6-pd-01.txt]. All IPv6 messages required for Prefix Delegation MUST be tunneled over the IPv4 tunnel between the mobile and the home agent. Once prefixes are delegated, and assuming explicit mode, the mobile node SHOULD send a registration request with appropriate IPv6 Prefix extensions to the home agent to register the delegated prefixes. 4.7. Deregistration of IPv6 Prefix The mobile IP registration lifetime included in the registration request header is valid for all the bindings created by the registration request, which may include bindings for IPv6 address(es) and prefix(es). A registration request with a zero lifetime can be used to remove all bindings from the home agent. A re-registration request with non-zero lifetime can be used to deregister some of the registered IPv6 prefixes by not including corresponding IPv6 prefix extensions in the registration request message. 4.8. Registration with a private CoA If the care-of address is a private address then Mobile IP NAT Traversal as [RFC3519] MAY be used in combination with the extensions described in this specification. Tsirtsis, et al. Expires May 5, 2007 [Page 17] Internet-Draft Dual Stack Mobile IPv4 November 2006 5. Security Considerations This specification operates in the security constraints and requirements of [RFC3344]. It extends the operations defined in [RFC3344] for IPv4 home addresses to cover home IPv6 addresses prefixes and provides the same level of security for both address IP versions. Tsirtsis, et al. Expires May 5, 2007 [Page 18] Internet-Draft Dual Stack Mobile IPv4 November 2006 6. Changes since v00 The Home Agent Considerations section was re-written and expanded with a lot more details by adapting text from MIPv6 and NEMO specifications. New error codes were added to section 3.2 Allowed for any length prefix, not just 64 and 128. Numerous editorial and clarification changes. Tsirtsis, et al. Expires May 5, 2007 [Page 19] Internet-Draft Dual Stack Mobile IPv4 November 2006 7. Aknowledgements Thanks to Pat Calhoun, Paal Engelstad, Tom Hiller and Pete McCann for earlier work on this subject. Thanks also to Alex Petrescu for suggesting the use of prefix delegation for dynamic IPv6 address allocation. Special thanks also to Sri Gundavelli for his thorough review. Tsirtsis, et al. Expires May 5, 2007 [Page 20] Internet-Draft Dual Stack Mobile IPv4 November 2006 8. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, October 1999. [RFC2794] Calhoun, P. and C. Perkins, "Mobile IP Network Access Identifier Extension for IPv4", RFC 2794, March 2000. [RFC3024] Montenegro, G., "Reverse Tunneling for Mobile IP, revised", RFC 3024, January 2001. [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, August 2002. [RFC3519] Levkowetz, H. and S. Vaarala, "Mobile IP Traversal of Network Address Translation (NAT) Devices", RFC 3519, May 2003. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. Tsirtsis, et al. Expires May 5, 2007 [Page 21] Internet-Draft Dual Stack Mobile IPv4 November 2006 Authors' Addresses George Tsirtsis Qualcomm Phone: +908-947-7059 Email: tsirtsis@qualcomm.com Vincent Park Qualcomm Phone: +908-947-7084 Email: vpark@qualcomm.com Hesham Soliman Consultant Phone: +614-111-410-445 Email: solimanhs@gmail.com Tsirtsis, et al. Expires May 5, 2007 [Page 22] Internet-Draft Dual Stack Mobile IPv4 November 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Tsirtsis, et al. Expires May 5, 2007 [Page 23]