Network Working Group P. McCann Internet-Draft Motorola Intended status: Best Current April 4, 2008 Practice Expires: October 6, 2008 Make-Before-Break Handoffs with Mobile IPv4 draft-mccann-mip4-mbb-00.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 October 6, 2008. Copyright Notice Copyright (C) The IETF Trust (2008). McCann Expires October 6, 2008 [Page 1] Internet-Draft MIP4 Make-Before-Break April 2008 Abstract A make-before-break handoff is one where resources on a target system are allocated prior to releasing the resources on a source system. Make-before-break can be an effective means to provide a more seamless handoff with fewer dropped packets. The existing Mobile IPv4 specification supports simultaneous bindings, which can facilitate a make-before-break handoff. However, the binding state at the home agent is only one example of a resource that can be allocated; others include the link connection to the Foreign Agent (or access router) and the provision of security associations between the mobile node and the mobility agents. It may be desirable to set up these resources on the target system without necessarily creating a binding entry on the Home Agent. This document provides some additional conventions on the use of simultaneous bindings in a make- before-break handoff that can be used to optimize the allocation of resources in these scenarios. McCann Expires October 6, 2008 [Page 2] Internet-Draft MIP4 Make-Before-Break April 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 5 3. Authentication Only Registration Request . . . . . . . . . . . 6 4. Bi-receiving . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. Normative References . . . . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 12 McCann Expires October 6, 2008 [Page 3] Internet-Draft MIP4 Make-Before-Break April 2008 1. Introduction During a make-before-break handoff, a mobile node attempts to set up resources on a target system while still connected to a source system. For example, a mobile node might have two wireless interfaces, one connected to FA1 (the source system) and another connected to FA2 (the target system). The mobile node would like to allocate some resources on FA2 before disconnecting from FA1, so that the time needed for actual media handoff is as short as possible. The base Mobile IP specification [RFC3344] provides for simultaneous bindings with the setting of the 'S' bit in a Registration Request. When the Home Agent (HA) receives such a request, it sets up an additional binding entry for the Mobile Node (MN) without deleting any existing binding(s). The multiple bindings cause packets destined for the MN to be duplicated and sent once for each binding to the corresponding Care-of-Address (CoA) registered as part of the binding. In a real-time communications scenario such as Voice-over-IP (VoIP), simultaneous bindings can allow for the packet stream to be ready and waiting on the new CoA before the old CoA is released. However, the simultaneous bindings as currently specified lacks some flexibility. In particular, the MN may need to set up a relationship with the HA (and a new FA) in advance of the handoff without necessarily beginning the forwarding of traffic. This is especially true if the Mobile IP Registration Request / Response exchange is used for access control on the new link [RFC4721] and to distribute keys to the MN and mobility agents [RFC3957]. It is desirable to allow these procedures to complete without sending media to the new access link, which would be wasteful of resources in case the MN will stay attached to its existing link for a period of time. In this document we define a new convention for the use of the 'S' bit to establish a new session and distribute keys, but without the establishment of binding state at the HA. Also, we give an implementation hint for HAs that implement simultaneous bindings that is expected to increase the quality of a real-time communication session. McCann Expires October 6, 2008 [Page 4] Internet-Draft MIP4 Make-Before-Break April 2008 2. 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]. McCann Expires October 6, 2008 [Page 5] Internet-Draft MIP4 Make-Before-Break April 2008 3. Authentication Only Registration Request In this section we define an Authentication Only Registration Request that can be used to provide access control and set up security associations between the MN and mobility agents. The existing text in the base Mobile IP specification says the following in Section 3.8.2.2: - If the Lifetime is zero and the Care-of Address equals the mobile node's home address, the home agent deletes all of the entries in the mobility binding list for the requesting mobile node. This is how a mobile node requests that its home agent cease providing mobility services. - If the Lifetime is zero and the Care-of Address does not equal the mobile node's home address, the home agent deletes only the entry containing the specified Care-of Address from the mobility binding list for the requesting mobile node. Any other active entries containing other care-of addresses will remain active. - If the Lifetime is nonzero, the home agent adds an entry containing the requested Care-of Address to the mobility binding list for the mobile node. If the 'S' bit is set and the home agent supports simultaneous mobility bindings, the previous mobility binding entries are retained. Otherwise, the home agent removes all previous entries in the mobility binding list for the mobile node. This document proposes a new case be added: - If the Lifetime is zero and the Care-of Address does not equal the mobile node's home address and the 'S' bit is set, then treat the Registration Request as an Authentication Only Registration Request. Perform authentication and key distribution [RFC3957] but do not establish a binding to the Care-of Address. Leave existing bindings unchanged. With this new convention, the MN will be able to perform access control on the new link and set up security associations with the home and foreign agents without yet directing traffic to the new CoA. When the MN is ready to perform the actual handoff of bearer to the new access link, it can send an ordinary registration request (with or without the 'S' bit set) to start receiving packets on the new CoA. The above procedure might be especially useful when handing off from a technology that uses Proxy Mobile IPv4 [I-D.leung-mip4-proxy-mode] to a technology that uses client Mobile IPv4. In this case, the MN McCann Expires October 6, 2008 [Page 6] Internet-Draft MIP4 Make-Before-Break April 2008 does not yet have a security association with the FA and HA while it is connected to the Proxy Mobile IP network, and needs to develop one with the new FA and existing HA prior to the actual handoff of traffic. McCann Expires October 6, 2008 [Page 7] Internet-Draft MIP4 Make-Before-Break April 2008 4. Bi-receiving During the process of handoff, the MN will establish new bindings and tear down old bindings. There may be a race condition here, because the message to delete a binding may arrive at the HA prior to some data packets that were sent from the old access router. For this reason, we propose that the HA implement a short hang timer when deleting a given binding, during which it will continue to receive and process data packets from the old point of attachment. This timer should be configured according to the expected deployment scenario. McCann Expires October 6, 2008 [Page 8] Internet-Draft MIP4 Make-Before-Break April 2008 5. Security Considerations None for now. McCann Expires October 6, 2008 [Page 9] Internet-Draft MIP4 Make-Before-Break April 2008 6. Normative References [I-D.leung-mip4-proxy-mode] Leung, K., "WiMAX Forum/3GPP2 Proxy Mobile IPv4", draft-leung-mip4-proxy-mode-04 (work in progress), October 2007. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, August 2002. [RFC3957] Perkins, C. and P. Calhoun, "Authentication, Authorization, and Accounting (AAA) Registration Keys for Mobile IPv4", RFC 3957, March 2005. [RFC4721] Perkins, C., Calhoun, P., and J. Bharatia, "Mobile IPv4 Challenge/Response Extensions (Revised)", RFC 4721, January 2007. McCann Expires October 6, 2008 [Page 10] Internet-Draft MIP4 Make-Before-Break April 2008 Author's Address Peter J. McCann Motorola Rm 2240 1301 E. Algonquin Rd Schaumburg, IL 60196 Phone: +1 847 576 3440 Email: pete.mccann@motorola.com McCann Expires October 6, 2008 [Page 11] Internet-Draft MIP4 Make-Before-Break April 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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, THE IETF TRUST 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). McCann Expires October 6, 2008 [Page 12]