Network Working Group J. Korhonen, Ed. Internet-Draft Nokia Siemens Networks Intended status: Standards Track S. Gundavelli Expires: November 12, 2009 Cisco H. Yokota KDDI Lab May 11, 2009 Runtime LMA Assignment Support for Proxy Mobile IPv6 draft-korhonen-netext-redirect-02.txt 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 November 12, 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Korhonen, et al. Expires November 12, 2009 [Page 1] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 Abstract This document describes a redirect functionality and corresponding mobility options for Proxy Mobile IPv6. The redirect functionality allows a dynamic runtime assignment of a Local Mobility Anchor and redirecting the mobility session to the assigned Local Mobility Anchor. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements and Terminology . . . . . . . . . . . . . . . . . 4 2.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 3. Proxy Mobile IPv6 Domain Assumptions . . . . . . . . . . . . . 5 4. Mobility Options . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Redirect-Capability Mobility Option . . . . . . . . . . . 6 4.2. Redirect Mobility Option . . . . . . . . . . . . . . . . . 7 5. Redirection Scenarios . . . . . . . . . . . . . . . . . . . . 8 5.1. Proxied Redirection Answer . . . . . . . . . . . . . . . . 8 5.2. Direct Redirection Answer . . . . . . . . . . . . . . . . 9 6. Processing Considerations . . . . . . . . . . . . . . . . . . 10 6.1. Mobile Access Gateway Considerations . . . . . . . . . . . 10 6.2. Local Mobility Anchor Considerations . . . . . . . . . . . 11 7. Multi-Homing Considerations . . . . . . . . . . . . . . . . . 12 8. Configuration Variables . . . . . . . . . . . . . . . . . . . 13 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 12.1. Normative References . . . . . . . . . . . . . . . . . . . 14 12.2. Informative References . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Korhonen, et al. Expires November 12, 2009 [Page 2] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 1. Introduction This document describes the Redirect-Capability and the Redirect mobility options, and the corresponding functionality for a runtime assignment of the Local Mobility Anchor (LMA) for Proxy Mobile IPv6 (PMIPv6). Hereafter the terms 'runtime assignment' and 'redirection' are used interchangeably throughout this specification. The runtime assignment takes place during a Proxy Binding Update (PBU) and a Proxy Binding Acknowledgement (PBA) messages exchange between a Mobile Access Gateway (MAG) and a LMA. The runtime assignment functionality defined in this specification can be used, for example, for load balancing purposes during the initial PBU/PBA messages exchange. However, other use cases are also possible. In case of load balancing, the runtime assignment approach is just one implementation option. MAGs and LMAs can implement other solutions that are, for example, completely transparent at PMIPv6 protocol level and do not depend on the functionality defined in this specification. The runtime assignment functionality described in this specification does not depend on information provisioned to external entities, such as the Domain Name System (DNS) or the Authentication, Authorization and Accounting (AAA) infrastructure. The trust relationship and coordination management between LMAs within a PMIPv6 domain is deployment specific and not described in this specification. There are number of reasons, why the runtime assignment is an useful addition to the PMIPv6 protocol. The following list describes some identified ones: o LMAs with multiple IP addresses: a cluster of LMAs or a blade architecture LMA may appear to the routing system as multiple LMAs with separate unicast IP addresses. A MAG can initially select any of those LMA IP addresses as the LMA Address using e.g., DNS- and AAA-based solutions. However, MAG's initial selection may be suboptimal from the LMA point of view and immediate redirection to a "proper LMA" would be needed. The LMA could use [RFC5142] based approach but that would imply unnecessary setting up of a mobility session in a "wrong LMA" with associated backend support system interactions, involve additional signaling between the MAG and the LMA, and re-establishing mobility session to the new LMA again with associated signaling. o Bypassing a load balancer: a cluster of LMAs or a blade architecture LMA may have a load balancer in front of them or integrated in one of the LMAs. The load balancer would represent multiple LMAs during the LMA discovery phase and only its IP address would be exposed to the MAG hiding possible individual LMA Korhonen, et al. Expires November 12, 2009 [Page 3] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 or LMA blade IP addresses from the MAG. However, if all traffic must always go through the load balancer it becomes quickly a bottleneck. Therefore, a PMIPv6 protocol level support for bypassing the load balancer after the initial PBU/PBA exchange would greatly help scalability. Also bypassing the load balancer as soon as possible allows implementing load balancers that do not maintain any MN specific state information. o Independence from DNS: DNS-based load balancing is a common practise. However, keeping MAGs up-to-date with LMA load status using DNS is hard e.g., due caching and unpredictable zone update delays. Generally, LMAs constantly updating [RFC2136] zone's master DNS server might not feasible in a large PMIPv6 domain due to increased load on the master DNS server and additional background signaling. Furthermore, MAGs may do (LMA) destination address selection decisions that are not in-line what the DNS administrator actually wanted [RFC3484]. o Independence from AAA: AAA-based solutions have basically the same arguments as DNS-based solutions above. It is also typical that AAA-based solutions offload the initial LMA selection to the DNS infrastructure. The AAA infrastructure does not return an IP address or a Fully Qualified domain Name (FQDN) to a single LMA, rather a FQDN representing a group of LMAs. o Support for IPv6 anycast addressing [RFC4291]: the current PMIPv6 specification does not specify how the PMIPv6 protocol should treat anycast addresses assigned to mobility agents. Although [RFC4291] now allows using anycast addresses as source addresses, it does not make much sense using anycast addresses for the MAG to the LMA communication after the initial PBU/PBA exchange. For example, a blade architecture LMA may appear to the routing system as multiple LMAs with separate unicast IP addresses and with one or more "grouping" anycast addresses. 2. Requirements and Terminology 2.1. Requirements 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]. 2.2. Terminology In addition to the terminology defined in [RFC5213], the following terminology is also used: Korhonen, et al. Expires November 12, 2009 [Page 4] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 rfLMA The LMA which receives the PBU from a MAG and decides to redirect the IP mobility session, and forwards the PBU to the target LMA (r2LMA). r2LMA The LMA to which a MAG was redirected to. During the redirection, the PBA MAY already be sent to the MAG from this LMA. 3. Proxy Mobile IPv6 Domain Assumptions The redirection functionality has several assumptions on the PMIPv6 domain. They are discussed here as they have impact on PMIPv6 deployment. Each functional LMA, whether that is a separate LMA in a cluster or an individual blade in a chassis, participating to the redirection MUST be reachable at a unicast IP address. The rfLMA and the r2LMA MUST have a prior agreement and an established trust relationship to perform the redirection. The rfLMA MUST NOT redirect the mobility session to a r2LMA that is not able accept the redirected mobility session. That is, the redirection functionality in not enabled in the r2LMA, or the r2LMA is down or otherwise unreachable. How the rfLMA learns and knows of other r2LMAs where the mobility session can be redirected to, is not covered by this specification. Each LMA and MAG participating to the redirection is assumed to have required Security Associations (SA) already set up in advance. Dynamic negotiation of the SAs using e.g., IKEv2 [RFC4306] MAY be supported but is out of scope of this specification. However, it should be noted that if anycast addresses are used within the PMIPv6 domain to contact the rfLMA, then manual keying of the SAs may be required [RFC4303]. During the redirection, the authorization, setting up and the final anchoring of the mobility session takes place at the r2LMA. After a successful redirection, the r2LMA is always contacted directly. This approach supports the attempt of complete bypassing of the rfLMA and allows implementing rfLMAs without any MN specific state information. The redirection functionality negotiation during the PBU/PBA exchange is stateless. The LMA MUST NOT include the Redirect mobility option in the PBA and perform the redirection, unless the MAG indicated the redirection functionality support in the corresponding PBU using the Redirection-Capability mobility option. The LMA MUST NOT include the Korhonen, et al. Expires November 12, 2009 [Page 5] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 Redirect mobility option unsolicited even if the MAG had earlier indicated support for the redirection functionality. The MAG MUST NOT conclude LMA's redirection functionality support based on the absence of the Redirect mobility option in the PBA. 4. Mobility Options The Redirect mobility options allow a LMA to inform a MAG of a redirection to a new LMA during a PBU/PBA exchange. MAGs and LMAs that implement the Redirect mobility option MUST support the redirection functionality during the initial PBU/PBA exchange that creates a new mobility session. MAGs and LMAs that implement the Redirect mobility option MAY support the redirection of an established mobility session. 4.1. Redirect-Capability Mobility Option A PBU message MAY contain the Redirect-Capability mobility option as an indication to a LMA that a MAG supports the redirection functionality. The Redirect-Capability mobility option has the alignment requirement of 4n. There can zero or one Redirect- Capability mobility option in the PBU. The format of the Redirect- Capability mobility option is shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Type | Option Length |D| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Redirect-Capability Mobility Option o Option Type: 8-bit identifier set to TBD1. o Option Length: 8-bit unsigned integer, representing the length of the Redirect-Capability mobility option in octets, excluding the Option Type and Length fields. The Option Length MUST be set to 2. o 'D' flag: The 'D'irect flag indicates whether a MAG is able to receive PBAs directly from the r2LMA. The MAG sets the 'D' flag to 1 (one) if it is able to receive a PBA containing the Redirect mobility option directly from the r2LMA Address. The MAG sets the 'D' flag to 0 (zero) if it MUST receive a PBA containing the Redirect mobility option from the rfLMA Address. Korhonen, et al. Expires November 12, 2009 [Page 6] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 o Reserved: This field is unused. MUST be set zero. 4.2. Redirect Mobility Option The LMA MAY include the Redirect mobility option in a PBA only if the MAG indicated support for the redirection functionality and the mobility session was redirected from the LMA to another. The Redirect mobility option in the PBA MUST contain the IPv6 addresses (unicast or anycast) of the rfLMA and the r2LMA. The Redirect mobility option in the PBA MAY contain the IPv4 addresses of the rfLMA and the r2LMA. The Redirect mobility option has the alignment requirement of 4n+2. There can zero or one Redirect mobility option in the PBA. The format of the Redirect mobility option is shown below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Type | Option Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | IPv6 rfLMA Address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | IPv6 r2LMA Address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Optional IPv4 rfLMA Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Optional IPv4 r2LMA Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Redirect Mobility Option o Option Type: 8-bit identifier set to TBD2. o Option Length: 8-bit unsigned integer, representing the length of the Redirect mobility option in octets, excluding the Option Type and Length fields. If the IPv4 LMA Addresses are included in the option, the Option Length MUST be set to 40. Otherwise, the Option Length MUST be set to 32. Korhonen, et al. Expires November 12, 2009 [Page 7] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 o IPv6 rfLMA Address: the IPv6 address of the rfLMA. o IPv6 r2LMA Address: the IPv6 address of the r2LMA. o Optional IPv4 rfLMA Address: the IPv4 address of the rfLMA. This value is present if the rfLMA IPv4 address is available. o Optional IPv4 r2LMA Address: the IPv4 address of the r2LMA. This value is present if the r2LMA IPv4 address is available. Note that IPv4 LMA addresses are always used in pairs. The option cannot include, for example, only the r2LMA IPv4 address or the rfLMA IPv4 address. 5. Redirection Scenarios The following sections describe the supported redirection scenarios that are possible using the redirection functionality defined in this specification. We describe two different scenarios and discuss general PMIPv6 domain assumptions. 5.1. Proxied Redirection Answer During the redirection the PBA is returned from the LMA Address where the PBU was sent to i.e., from the rfLMA. After the redirection all PMIPv6 communication continues between the MAG and the r2LMA. The proxied redirection answer scenario is shown in Figure 1. In this scenario, the MAG requested proxied redirection answer by setting the D-flag to 0 in the Redirect-Capability mobility option in the PBU. Alternatively, this scenario also applies when the 'LMA' (consisting of the rfLMA and the r2LMA) does not support returning a PBA directly from the r2LMA even if the MAG indicated a support for it. The proxied redirection answer scenario has several benefits: o Easier deployment with IPsec. The security model including possible dynamic negotiation of the MAG-LMA Security Association (SA) is completely align with the PMIPv6 base protocol as defined in [RFC5213]. o Easier deployment with firewalls. As the PBA is always returned from the same LMA Address where the PBU was sent to (even in case of anycast LMA Address), stateful firewall rules can still be used for PBU/PBA traffic. Korhonen, et al. Expires November 12, 2009 [Page 8] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 MAG rfLMA r2LMA | | | |--PBU-->|--PBU-->| (redirection takes place, |<--PBA--|<--PBA--| PBA contains rfLMA & r2LMA | | | information) | | | |<=====data======>| | | | |-------PBU------>| (lifetime extension, |<------PBA-------| de-registration, etc.) Figure 1: A MAG sets D-flag to 0, or a 'LMA' does not support D-flag set to 1 functionality 5.2. Direct Redirection Answer During the redirection the PBA is returned directly from the redirected to LMA Address i.e., from the r2LMA. After the redirection all PMIPv6 communication continues between the MAG and the r2LMA. The direct redirection answer scenario is shown in Figure 2. In this scenario, the MAG indicates a support for direct redirection answer by setting the D-flag to 1 in the Redirect-Capability mobility option in the PBU. The 'LMA' (consisting of the rfLMA and the r2LMA) also has a support for returning a PBA directly from the r2LMA. The direct redirection scenario is only possible between MAGs and LMAs that have an existing SA set up. It is the responsibility of the rfLMA that receives a PBU from a MAG to redirect the MAG to a such r2LMA whom the MAG already has a SA set up with. The direct redirection answer scenario has the following benefits: o In a load balancing case (where the rfLMA acts as a load balancer), the direct answer scenario allows complete bypassing of the load balancer after the redirection decision, including the response traffic during the redirection. The load balancer can also be made completely stateless. This is especially valuable when the rfLMA and the r2LMA are separate physical entities. o For anycast traffic the answer (i.e., the PBA) can already be sent from the real unicast LMA Address (i.e., the r2LMA Address). The direct redirection answer scenario has the following deployment related concerns: Korhonen, et al. Expires November 12, 2009 [Page 9] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 o Deployment of stateful firewalls within a PMIPv6 domain becomes a challenge as responses arrive from a different address than where requests were sent to. o Synchronizing PBU/PBA Sequence Numbers become more complicated. The sequence are matched between the MAG-LMA pairs, so there is no "pending" request for the PBA coming from the r2LMA. Using a timestamp-based solution instead of sequence numbers is an easy solution for message ordering. Alternatively, on the MAG side the PBU/PBA matching MUST be based on the rfLMA address included in the Redirect mobility option instead of the IP address where the PBA came from. MAG rfLMA r2LMA | | | |--PBU-->|--PBU-->| (redirection takes place, |<-----------PBA--| PBA contains rfLMA & r2LMA | | | information) | | | |<=====data======>| | | | |-------PBU------>| (lifetime extension, |<------PBA-------| de-registration, etc.) Figure 2: A MAG sets D-flag to 1 and a 'LMA' supports D-flag set to 1 functionality 6. Processing Considerations 6.1. Mobile Access Gateway Considerations If the redirection functionality is enabled, then the MAG MAY include the Redirect-Capability mobility option in any PBU. The Redirect- Capability mobility option in the PBU is also an indication to a LMA that the MAG supports the redirection functionality. The redirection concerns always one mobility session at time. If the "direct redirection answer" functionality is enabled, then the MAG sets the D-flag to 1 in the Redirect-Capability mobility option. Otherwise, the MAG sets the D-flag to 0 in the Redirect-Capability mobility option. If the MAG receives a PBA that contains the Redirect mobility option without first including the Redirect-Capability mobility option in the corresponding PBU, then the MAG MUST treat the PBA as if the binding update failed and log the event. If the MAG receives a PBA Korhonen, et al. Expires November 12, 2009 [Page 10] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 that contains the Redirect mobility option and the MAG had included the Redirect-Capability mobility option in the corresponding PBU, then the MAG MUST perform the following steps in addition to the normal RFC 5213 PBA processing: o Check if the Redirect mobility option contains the IP address of the LMA to whom the MAG originally sent the PBU (i.e., the rfLMA Address field). If the check fails, then the MAG MUST treat the PBA as if the binding update failed and log the event. o Perform the PBU and the PBA matching using the rfLMA Address field from the Redirect mobility option. This applies especially to the case where the MAG supports the "direct redirection answer" scenario. If the redirection was successful, the MAG updates the Binding Update List to correspond to the r2LMA Address included in the received Redirect mobility option. There is no need to resend any PBUs to the r2LMA after a successful redirection. The mobility session has already been established in the r2LMA. The MAG MUST send subsequent binding refreshing PBUs and user traffic to the new r2LMA Address. If the MAG includes the Redirect-Capability mobility option in subsequent PBUs, the LMA MAY redirect the MAG again. 6.2. Local Mobility Anchor Considerations The text in this section refers to a 'LMA' when it means the combination of the rfLMA and the r2LMA i.e., the entity where redirection is possible. When the text points to a specific LMA role during the redirection, it uses either the 'rfLMA' or the 'r2LMA'. If the redirection functionality is not enabled in a LMA, then the LMA MUST ignore the Redirect-Capability mobility option received in PBUs. If the redirection functionality is enabled in the LMA and the received PBU contains the Redirect-Capability mobility option, then the rfLMA MAY redirect the MAG to a new r2LMA. In the case of redirection, the r2LMA MUST always include the IPv6 address (unicast or anycast) of the rfLMA and the IPv6 address (unicast) of the r2LMA in the Redirect mobility option in the PBA. If the LMA has IPv4 support enabled, then the r2LMA MUST include the IPv4 address of the rfLMA and the r2LMA in the Redirect mobility option. If the received PBU contains the Redirect-Capability mobility option with D-flag set to 1, the LMA MAY return the PBA directly from the r2LMA Address. Otherwise, if the D-flag is set to 0 or the LMA does not support the 'direct redirection answer' scenario, the PBA MUST be returned from the rfLMA Address. Korhonen, et al. Expires November 12, 2009 [Page 11] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 The rfLMA MUST only redirect the MAG to a new r2LMA that it knows the MAG has a SA with. The rfLMA MUST NOT redirect the MAG to a r2LMA that the rfLMA and the r2LMA do not have a prior redirection agreement and an established trust relationship for the redirection. These SA related knowledge issues and trust relationships are deployment specific in a PMIPv6 domain and out of scope of this specification. Possible context transfer and other coordination management between the rfLMA and the r2LMA, are again deployment specific for LMAs in a PMIPv6 domain. The rfLMA MUST NOT redirect a MAG using IPv6 transport to a new r2LMA using IPv4 transport, if the MAG does not indicate support for IPv4 in the Redirect-Capability mobility option, as there is no guarantee that the MAG supports switching from IPv6 transport to IPv4 transport. If the redirection was successful, the mobility session is established in the r2LMA. The actual PBU processing takes place in the r2LMA. However, depending on the LMA's implementation of the PMIPv6 security framework, the IPsec processing of the PBU may take place in the rfLMA before the PBU is forwarded to the r2LMA. 7. Multi-Homing Considerations A MN can be multi-homed. A single LMA entity should have the control over all possible multi-homed mobility sessions the MN has. All mobility sessions a multi-homed MN may have SHOULD be anchored in the single LMA entity. Therefore, once the MN has established one mobility session with one LMA, the subsequent mobility sessions of the same MN SHOULD be anchored to the LMA that was initially assigned. One possible solution already supported by this specification is applying the redirection only for the very first initial attach a multi-homed MN does towards a PMIPv6 domain. After the initial attach, the assigned r2LMA Address has been stored in the policy profile. For the subsequent mobility sessions of the multi-homed MN, the same assigned r2LMA Address would be used and there is no need to contact the rfLMA. MAGs have a control over selectively enabling and disabling the redirection of the LMA. If the multi-homed MN is attached to a PMIPv6 domain via multiple MAGs, the assigned r2LMA Address should be stored in the remote policy store and downloaded as a part of the policy profile download to a MAG. Alternatively, MAGs can share policy profile information using other means. In both cases, the actual implementation of the policy profile information sharing is Korhonen, et al. Expires November 12, 2009 [Page 12] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 specific to a PMIPv6 deployment and out of scope of this specification. 8. Configuration Variables This specification defines three configuration variables that control the redirection functionality within a PMIPv6 domain. EnableLMARedirectFunction This configuration variable is available in both a MAG and in a rfLMA. When set to 1 (i.e., enabled), the PMIPv6 node enables the redirection functionality. The default value is 0 (i.e., disabled). EnableLMARedirectAcceptFunction This configuration variable is available in a r2LMA. When set to 1 (i.e., enabled), the r2LMA is able to accept redirected mobility sessions from a rfLMA. The default value is 0 (i.e., disabled). EnableDirectLMARedirectionFunction This configuration variable is available in both a MAG and in a r2LMA. When set to 1 (i.e., enabled), the r2LMA can return a PBA directly using its own unicast LMA Address after a successful redirection. The default value is 0 (i.e., disabled). 9. Security Considerations The security considerations of PMIPv6 signaling described in RFC 5213 apply to this document. An incorrectly configured LMA may cause unwanted redirection attempts to non-existing LMAs or to other LMAs that do not have and will not have a SA with the redirected MAG. At the same time, a falsely redirected MAG will experience failed binding updates or creation of mobility sessions. An incorrectly configured LMA may also cause biased load distribution within a PMIPv6 domain. This document also assumes that the LMAs that participate to redirection have adequate prior agreement and trust relationship between each other. If the SAs between MAGs and LMAs are manually keyed (as it might be needed by the 'direct redirection answer' scenario), then the anti- replay service of ESP protected PMIPv6 traffic cannot typically be provided. This is, however, deployment specific for a PMIPv6 domain. Korhonen, et al. Expires November 12, 2009 [Page 13] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 If a PMIPv6 domain deployment with a redirection requires that a rfLMA has to modify a received PBU in any way e.g., by changing the destination IP address field of the outer IP header, then the security mechanism (such as possible authentication options) used to protect the PBU must not cover the outer IP header on those parts that might get modified. Alternatively, the rfLMA can do all required security mechanism processing on the received PBU and remove those security related options from the PBU that would cause the security check to fail on the r2LMA. 10. IANA Considerations Two new mobility options for the use with PMIPv6 are defined in the [RFC3775] "Mobility Options" registry. The mobility options are defined in Section 4: Redirect-Capability Mobility Option is set to TBD1 Redirect Mobility Option is set to TBD2 11. Acknowledgements The author would like to thank Basavaraj Patil and Domagoj Premec for their reviews and comments on the initial versions of this document. 12. References 12.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 12.2. Informative References [RFC2136] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic Updates in the Domain Name System (DNS UPDATE)", RFC 2136, April 1997. [RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003. Korhonen, et al. Expires November 12, 2009 [Page 14] Internet-Draft LMA Redirect Support for PMIPv6 May 2009 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303, December 2005. [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306, December 2005. [RFC5142] Haley, B., Devarapalli, V., Deng, H., and J. Kempf, "Mobility Header Home Agent Switch Message", RFC 5142, January 2008. Authors' Addresses Jouni Korhonen (editor) Nokia Siemens Networks Linnoitustie 6 FI-02600 Espoo FINLAND Email: jouni.nospam@gmail.com Sri Gundavelli Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: sri.gundavelli@cisco.com Hidetoshi Yokota KDDI Lab 2-1-15 Ohara, Fujimino Saitama, 356-8502 Japan Email: yokota@kddilabs.jp Korhonen, et al. 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