Netext BOF S. Krishnan Internet-Draft Ericsson Intended status: Informational H. Yokota Expires: August 13, 2009 KDDI Lab T. Melia Alcatel-Lucent February 9, 2009 Issues with network based inter-technology handovers draft-krishnan-netext-intertech-ps-00 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 13, 2009. Copyright Notice Copyright (c) 2009 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. Krishnan, et al. Expires August 13, 2009 [Page 1] Internet-Draft Network based Inter-technology handovers February 2009 Abstract Proxy Mobile IPv6 (PMIPv6) is a network based mobility management protocol enables IP mobility for a host without requiring its participation in any mobility-related signaling. While the PMIPv6 protocol itself supports handover across interfaces and between access types, there are several issues with effectively performing inter-technology handovers with network based mobility protocols. This document aims to enumerate some known issues with such handovers. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . . 3 2. Issues occuring in the MN . . . . . . . . . . . . . . . . . . . 4 2.1. Formation of interface identifier . . . . . . . . . . . . . 4 2.2. Usage of the same address on multiple interfaces . . . . . 4 2.3. Limitations of interfaces . . . . . . . . . . . . . . . . . 4 3. Issues occuring in the network . . . . . . . . . . . . . . . . 5 3.1. Access selection . . . . . . . . . . . . . . . . . . . . . 5 3.2. Detecting handovers . . . . . . . . . . . . . . . . . . . . 5 3.3. Predictive handovers . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6. Normative References . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Krishnan, et al. Expires August 13, 2009 [Page 2] Internet-Draft Network based Inter-technology handovers February 2009 1. Introduction Proxy Mobile IPv6 (PMIPv6) [RFC5213] is a network based mobility management protocol enables IP mobility for a host without requiring its participation in any mobility-related signaling. While the PMIPv6 protocol itself supports handover across interfaces and between access types, there are several issues with effectively performing inter-technology handovers with network based mobility protocols. This document aims to enumerate some known issues with such handovers. On a high level these can be classified into those issues occuring on the MN and those issues occuring in the network. 1.1. Conventions used in this document 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]. Krishnan, et al. Expires August 13, 2009 [Page 3] Internet-Draft Network based Inter-technology handovers February 2009 2. Issues occuring in the MN 2.1. Formation of interface identifier The IPv6 address of the MN is composed of two parts, the prefix and the interface identifier. Even if the network correctly identified the handover and allocated the same prefix on the new interface, the MN might come up with a different interface identifier on the new interface than it was using on the old interface. This is usually in several link-layer technologies because the interface identifier is formed based on a unique identifier of the link-layer interface. E.g. the modified EUI-64 based interface identifiers based on the MAC address of the link-layer interface. If this is the case, the resulting address on the new interface is different that the address the MN was using prior to the handover and hence the applications bound to the earlier IPv6 address will lose connectivity. 2.2. Usage of the same address on multiple interfaces Several MN operating system implementations do not allow the configuration of the same address on multiple interfaces. Even on those that do, the resulting behavior is usually not predictable. e.g. after a handover all the traffic might still be directed to the old interface (hence getting dropped) because the default route was pointing towards that interface. 2.3. Limitations of interfaces Certain types of point-to-point interfaces are tightly bound to the underlying interface and could be torn down even if there is another viable interface that can carry the traffic. Krishnan, et al. Expires August 13, 2009 [Page 4] Internet-Draft Network based Inter-technology handovers February 2009 3. Issues occuring in the network 3.1. Access selection The network nodes may not always be aware of the complete set of access technologies available to the MN. This is especially true if the multple accesses are administered by different entities. Only the MN is guaranteed to have this information. The network may also not know about the characteristics that the MN desires from the selected access technology. Because of these reasons it is almost impossible for the network to perform access selection without some amount of co-operation from the MN. 3.2. Detecting handovers The network nodes may not always be aware of the intent of the MN when it attaches to a new attachment point. The MN may be performing a handover, may wish to be simultaneously connected. The access router at the new attachment point is unable to distinguish between these cases, but needs to communicate this information to the mobility anchor. The mobility anchor point needs this information to determine whether to handover an existing mobility session or to create a new one. 3.3. Predictive handovers An MN that is capable of being attached to multiple accesses can perform a predictive handover attaching to the target access even before detaching from the previous access. This is done in order to reduce the handover latency and to reduce packet loss. Most of the time, the intent of the MN is to continue using the previous access until it explicitly signals to the network to start using the new access. The target access router cannot determine if this is the case and may end up prematurely moving the MNs binding over to the new access even while the MN is sending outgoing packets onto the old access. Krishnan, et al. Expires August 13, 2009 [Page 5] Internet-Draft Network based Inter-technology handovers February 2009 4. Security Considerations This document discusses issues with inter-technology handovers with network based mobility protocols, and does not raise any new security issues. Krishnan, et al. Expires August 13, 2009 [Page 6] Internet-Draft Network based Inter-technology handovers February 2009 5. IANA Considerations This document does not require any IANA action. Krishnan, et al. Expires August 13, 2009 [Page 7] Internet-Draft Network based Inter-technology handovers February 2009 6. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. Krishnan, et al. Expires August 13, 2009 [Page 8] Internet-Draft Network based Inter-technology handovers February 2009 Authors' Addresses Suresh Krishnan Ericsson 8400 Blvd Decarie Town of Mount Royal, Quebec Canada Email: suresh.krishnan@ericsson.com Hidetoshi Yokota KDDI Lab Email: yokota@kddilabs.jp Telemaco Melia Alcatel-Lucent Route de Villejust Nozay 91620 France Email: telemaco.melia@alcatel-lucent.com Krishnan, et al. Expires August 13, 2009 [Page 9]