Network Working Group H. Yokota Internet-Draft KDDI Lab Intended status: Standards Track K. Chowdhury Expires: July 1, 2010 R. Koodli Starent Networks B. Patil Nokia F. Xia Huawei USA December 28, 2009 Fast Handovers for Proxy Mobile IPv6 draft-ietf-mipshop-pfmipv6-12.txt Abstract Mobile IPv6 (MIPv6) [RFC3775] provides a mobile node with IP mobility when it performs a handover from one access router to another and fast handovers for Mobile IPv6 (FMIPv6) [RFC5568] are specified to enhance the handover performance in terms of latency and packet loss. While MIPv6 (and FMIPv6 as well) requires the participation of the mobile node in the mobility-related signaling, Proxy Mobile IPv6 (PMIPv6) [RFC5213] provides IP mobility to mobile nodes that either have or do not have MIPv6 functionality without such involvement. Nevertheless, the basic performance of PMIPv6 in terms of handover latency and packet loss is considered not any different from that of MIPv6. When the fast handover is considered in such an environment, several modifications are needed to FMIPv6 to adapt to the network-based mobility management. This document specifies the usage of Fast Mobile IPv6 (FMIPv6) when Proxy Mobile IPv6 is used as the mobility management protocol. Necessary extensions are specified for FMIPv6 to support the scenario when the mobile node does not have IP mobility functionality and hence is not involved with either MIPv6 or FMIPv6 operations. 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. Yokota, et al. Expires July 1, 2010 [Page 1] Internet-Draft Proxy-based Fast Handover December 2009 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 July 1, 2010. 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. 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 BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Yokota, et al. Expires July 1, 2010 [Page 2] Internet-Draft Proxy-based Fast Handover December 2009 Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Proxy-based FMIPv6 Protocol Overview . . . . . . . . . . . . . 7 4.1. Protocol Operation . . . . . . . . . . . . . . . . . . . . 8 4.2. Inter-AR Tunneling Operation . . . . . . . . . . . . . . . 15 4.3. IPv4 Support Considerations . . . . . . . . . . . . . . . 17 5. PMIPv6-related Fast Handover Issues . . . . . . . . . . . . . 18 5.1. Manageability Considerations . . . . . . . . . . . . . . . 18 5.2. Expedited Packet Transmission . . . . . . . . . . . . . . 18 6. Message Formats . . . . . . . . . . . . . . . . . . . . . . . 20 6.1. Mobility Header . . . . . . . . . . . . . . . . . . . . . 20 6.1.1. Handover Initiate (HI) . . . . . . . . . . . . . . . . 20 6.1.2. Handover Acknowledge (HAck) . . . . . . . . . . . . . 22 6.2. Mobility Options . . . . . . . . . . . . . . . . . . . . . 24 6.2.1. Context Request Option . . . . . . . . . . . . . . . . 24 6.2.2. Local Mobility Anchor Address (LMAA) Option . . . . . 25 6.2.3. Mobile Node Link-local Address Interface Identifier (MN LLA-IID) Option . . . . . . . . . . . . 26 6.2.4. Home Network Prefix Option . . . . . . . . . . . . . . 27 6.2.5. Link-local Address Option . . . . . . . . . . . . . . 27 6.2.6. GRE Key Option . . . . . . . . . . . . . . . . . . . . 27 6.2.7. IPv4 Address Option . . . . . . . . . . . . . . . . . 27 6.2.8. Vendor-Specific Mobility Option . . . . . . . . . . . 27 7. Security Considerations . . . . . . . . . . . . . . . . . . . 28 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 31 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32 10.1. Normative References . . . . . . . . . . . . . . . . . . . 32 10.2. Informative References . . . . . . . . . . . . . . . . . . 32 Appendix A. Applicable Use Cases . . . . . . . . . . . . . . . . 33 A.1. PMIPv6 Handoff Indication . . . . . . . . . . . . . . . . 33 A.2. Local Routing . . . . . . . . . . . . . . . . . . . . . . 33 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 35 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41 Yokota, et al. Expires July 1, 2010 [Page 3] Internet-Draft Proxy-based Fast Handover December 2009 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]. Yokota, et al. Expires July 1, 2010 [Page 4] Internet-Draft Proxy-based Fast Handover December 2009 2. Introduction Proxy Mobile IPv6 [RFC5213] provides IP mobility to a mobile node that does not support Mobile IPv6 [RFC3775] mobile node functionality. A proxy agent in the network performs the mobility management signaling on behalf of the mobile node. This model transparently provides mobility for mobile nodes within a PMIPv6 domain. Nevertheless, the basic performance of PMIPv6 in terms of handover latency and packet loss is considered not any different from that of Mobile IPv6. Fast Handovers for Mobile IPv6 (FMIPv6) [RFC5568] describes the protocol to reduce the handover latency for Mobile IPv6 by allowing a mobile node to send packets as soon as it detects a new subnet link and by delivering packets to the mobile node as soon as its attachment is detected by the new access router. This document extends FMIPv6 for Proxy MIPv6 operation to minimize handover delay and packet loss as well as to transfer network-resident context for a PMIPv6 handover. [RFC5568] should be considered normative for this document, except where this document specifies new or revised functions and messages. Yokota, et al. Expires July 1, 2010 [Page 5] Internet-Draft Proxy-based Fast Handover December 2009 3. Terminology This document reuses terminology from [RFC5213], [RFC5568] and [RFC3775]. The following terms and abbreviations are additionally used in this document. Access Network (AN): A network composed of link-layer access devices such as access points or base stations providing access to an Access Router (AR) connected to it. Previous Access Network (P-AN): The access network to which the Mobile Node (MN) is attached before handover. New Access Network (N-AN): The access network to which the Mobile Node (MN) is attached after handover. Previous Mobile Access Gateway (PMAG): The MAG that manages mobility related signaling for the mobile node before handover. In this document, the MAG and the Access Router are co-located. New Mobile Access Gateway (NMAG): The MAG that manages mobility related signaling for the mobile node after handover. In this document, the MAG and the Access Router (AR) are co-located. Local Mobility Anchor (LMA) The topological anchor point for the mobile node's home network prefix(es) and the entity that manages the mobile node's binding state. This specification does not alter any capability or functionality defined in [RFC5213]. Handover indication: A generic signaling message, sent from the P-AN to the PMAG that indicates a mobile node's handover. While this signaling is dependent on the access technology, it is assumed that Handover indication can carry the information to identify the mobile node and to assist the PMAG to resolve the NMAG and the new access point or base station to which the mobile node is moving to. The details of this message are outside the scope of this document. Yokota, et al. Expires July 1, 2010 [Page 6] Internet-Draft Proxy-based Fast Handover December 2009 4. Proxy-based FMIPv6 Protocol Overview This specification describes fast handover protocols for the network- based mobility management protocol called Proxy Mobile IP (PMIPv6) [RFC5213]. The core functional entities defined in PMIPv6 are the Local Mobility Anchor (LMA) and the Mobile Access Gateway (MAG). The LMA is the topological anchor point for the mobile node's home network prefix(es). The MAG acts as an access router (AR) for the mobile node and performs the mobility management procedures on its behalf. The MAG is responsible for detecting the mobile node's movements to and from the access link and for initiating binding registrations to the mobile node's local mobility anchor. If the MAGs can be informed of the detachment and/or attachment of the mobile node in a timely manner via e.g., the lower layer signaling, it will become possible to optimize the handover procedure, which involves establishing a connection on the new link and signaling between mobility agents, compared to the baseline specification of PMIPv6. In order to further improve the performance during the handover, the PFMIPv6 protocol in this document specifies a bi-directional tunnel between the Previous MAG (PMAG) and the New MAG (NMAG) to tunnel packets meant for the mobile node. In order to enable the NMAG to send the Proxy Binding Update (PBU), the Handover Initiate (HI) and Handover Acknowledge (HAck) messages in [RFC5568] are extended for context transfer, in which parameters such as mobile node's Network Access Identifier (NAI), Home Network Prefix (HNP), IPv4 Home Address, are transferred from the PMAG. New flags 'P' and 'F' are defined for the HI and HAck messages to distinguish from those in [RFC5568] and to request packet forwarding, respectively. In this document, the Previous Access Router (PAR) and New Access Router (NAR) are interchangeable with the PMAG and NMAG, respectively. The reference network is illustrated in Figure 1. The access networks in the figure (i.e., P-AN and N-AN) are composed of Access Points (APs) defined in [RFC5568], which are often referred to as base stations in cellular networks. Since a mobile node is not directly involved with IP mobility protocol operations, it follows that the mobile node is not directly involved with fast handover procedures either. Hence, the messages involving the mobile node in [RFC5568] are not used when PMIPv6 is in use. More specifically, the Router Solicitation for Proxy Advertisement (RtSolPr), the Proxy Router Advertisement (PrRtAdv), Fast Binding Update (FBU), Fast Binding Acknowledgment (FBack) and the Unsolicited Neighbor Advertisement (UNA) messages are not applicable in the PMIPv6 context. Yokota, et al. Expires July 1, 2010 [Page 7] Internet-Draft Proxy-based Fast Handover December 2009 +----------+ | LMA | | | +----------+ / \ / \ / \ +........../..+ +..\..........+ . +-------+-+ .______. +-+-------+ . . | PMAG |()_______)| NMAG | . . | (PAR) | . . | (NAR) | . . +----+----+ . . +----+----+ . . | . . | . . ___|___ . . ___|___ . . / \ . . / \ . . ( P-AN ) . . ( N-AN ) . . \_______/ . . \_______/ . . | . . | . . +----+ . . +----+ . . | MN | ----------> | MN | . . +----+ . . +----+ . +.............+ +.............+ Figure 1: Reference network for fast handover 4.1. Protocol Operation There are two modes of operation in FMIPv6 [RFC5568]. In the predictive mode of fast handover, a bi-directional tunnel between the PMAG (PAR) and NMAG (NAR) is established prior to the mobile node's attachment to the NMAG. In the reactive mode, this tunnel establishment takes place after the mobile node attaches to the NMAG. In order to alleviate the packet loss during a mobile node's handover (especially when the mobile node is detached from both links), the downlink packets for the mobile node need to be buffered either at the PMAG or NMAG, depending on when the packet forwarding is performed. It is hence required that all MAGs have the capability and enough resources to buffer packets for the mobile nodes accommodated by them. The buffer size to be prepared and the rate at which buffered packets are drained are addressed in Section 5.4 of [RFC5568]. Note that the protocol operation specified in the document is transparent to the local mobility anchor (LMA), hence there is no new functional requirement or change on the LMA. Unlike MIPv6, the mobile node in the PMIPv6 domain is not involved with IP mobility signaling; therefore, in order for the predictive fast handover to work effectively, it is required that the mobile node is capable of reporting lower-layer information to the AN at a Yokota, et al. Expires July 1, 2010 [Page 8] Internet-Draft Proxy-based Fast Handover December 2009 short enough interval, and the AN is capable of sending the Handover indication to the PMAG at an appropriate timing. The sequence of events for the predictive fast handover are illustrated in Figure 2. PMAG NMAG MN P-AN N-AN (PAR) (NAR) LMA | | | | | | (a) |--Report-->| | | | | | | | | | | | | Handover | | | (b) | |------indication------>| | | | | | | | | | | | | | | (c) | | | |----HI---->| | | | | | | | | | | | | | (d) | | | |<---HAck---| | | | | | | | | | | | | | | | | |HI/HAck(optional) | (e) | | | |<- - - - ->| | | | | #=|<===================| (f) | | | #====DL data=>| | | Handover | Handover | | | (g) |<-command--|<------command---------| | | ~~~ | | | | | ~~~ | | | | | | MN-AN connection | AN-MAG connection | | (h) |<---establishment---->|<----establishment----->| | | | | (substitute for UNA) | | | | | | | | (i) |<==================DL data=====================| | | | | | | | (j) |===================UL data====================>|=# | | | | #=|<============# | | | | #=====================>| / | | | | | | \ |(k) | | | | |--PBU-->| | | | | | | | | | |(l) | | | | |<--PBA--| | | |<==================DL data=====================|<=======| | | | | | | | | | \ |===================UL data====================>|=======>| / Figure 2: Predictive fast handover for PMIPv6 (PMAG initiated) The detailed descriptions are as follows: Yokota, et al. Expires July 1, 2010 [Page 9] Internet-Draft Proxy-based Fast Handover December 2009 (a) The mobile node detects that a handover is imminent and reports the identifier of itself (MN ID) and the New Access Point Identifier (New AP ID) [RFC5568] to which the mobile node is most likely to move. The MN ID could be the NAI, Link-layer address, or any other suitable identifier, but the MAG SHOULD be able to map any access specific identifier to the NAI as the MN ID. In some cases, the previous access network (P-AN) will determine the New AP ID for the mobile node. This step is access technology specific and details are outside the scope of this document. (b) The previous access network, to which the mobile node is currently attached, indicates the handover of the mobile node to the previous mobile access gateway (PMAG), with the MN ID and New AP ID. Detailed definition and specification of this message are outside the scope of this document. (c) The previous MAG derives the new mobile access gateway (NMAG) from the New AP ID, which is a similar process to that of constructing an [AP ID, AR-Info] tuple in [RFC5568]. The previous MAG then sends the Handover Initiate (HI) message to the new MAG. The HI message MUST have the P flag set and include the MN ID, the HNP(s) and the address of the local mobility anchor that is currently serving the mobile node. If there is a valid (non-zero) MN Link-layer Identifier (MN LL-ID), that information MUST also be included. With some link layers, the MN Link-local Address IID (MN LLA-IID) can also be included (see Section 6.2.3). (d) The new MAG sends the Handover Acknowledge (HAck) message back to the previous MAG with the P flag set. (e) If it is preferred that the timing of buffering or forwarding should be later than step (c), the new MAG may optionally request the previous MAG at a later and appropriate time to buffer or forward packets by setting U flag [RFC5568] or F flag in the HI message, respectively. (f) If the F flag is set in the previous step, a bi-directional tunnel is established between the previous MAG and new MAG and packets destined for the mobile node are forwarded from the previous MAG to the new MAG over this tunnel. After decapsulation, those packets may be buffered at the new MAG. If the connection between the new access network and new MAG has already been established, those packets may be forwarded towards the new access network, which then becomes responsible for them (e.g., buffering or delivering depending on the condition of the mobile node's attachment); this is access technology specific. Yokota, et al. Expires July 1, 2010 [Page 10] Internet-Draft Proxy-based Fast Handover December 2009 (g) When handover is ready on the network side, the mobile node is triggered to perform handover to the new access network. This step is access technology specific and details are outside the scope of this document. (h) The mobile node establishes a physical link connection with the new access network (e.g., radio channel assignment), which in turn triggers the establishment of a link-layer connection between the new access network and new MAG if not yet established. An IP layer connection setup may be performed at this time (e.g., PPP IPv6CP) or at a later time (e.g., stateful or stateless auto address configuration). This step can be a substitute for the Unsolicited Neighbor Advertisement (UNA) in [RFC5568]. If the new MAG acquires a valid new MN LL-ID via the new access network and a valid old MN LL-ID from the previous MAG at step (c), these IDs SHOULD be compared to determine whether the same interface is used before and after handover. When the connection between the mobile node and new MAG is PPP and the same interface is used for the handover, the new MAG SHOULD confirm that the same interface identifier is used for the mobile node's link-local address (this is transferred from previous MAG using the MN LLA-IID option at step (c), and sent to the mobile node during the Configure-Request/Ack exchange). (i) The new MAG starts to forward packets destined for the mobile node via the new access network. (j) The uplink packets from the mobile node are sent to the new MAG via the new access network and the new MAG forwards them to the previous MAG. The previous MAG then sends the packets to the local mobility anchor that is currently serving the mobile node. (k) The new MAG sends the Proxy Binding Update (PBU) to the local mobility anchor, whose address is provided in (c). Steps (k) and (l) are not part of the fast handover procedure, but shown for reference. (l) The local mobility anchor sends back the Proxy Binding Acknowledgment (PBA) to the new MAG. From this time on, the packets to/from the mobile node go through the new MAG instead of the previous MAG. According to Section 4 of [RFC5568], the previous access router establishes a binding between the Previous Care-of Address (PCoA) and New Care-of Address (NCoA) to forward packets for the mobile node to the new access router, and the new access router creates a proxy neighbor cache entry to receive those packets for the NCoA before the mobile node arrives. In the case of PMIPv6, however, the only Yokota, et al. Expires July 1, 2010 [Page 11] Internet-Draft Proxy-based Fast Handover December 2009 address that is used by the mobile node is MN-HoA (Mobile Node's Home Address), so the PMAG forwards mobile node's packets to the NMAG instead of the NCoA. The NMAG then simply decapsulates those packets and delivers them to the mobile node. FMIPv4 [RFC4988] specifies forwarding when the mobile node uses the home address as its on-link address rather than the care-of address. The usage in PMIPv6 is similar to that in FMIPv4, where the address(es) used by the mobile node is/are based on its HNP(s). Since the NMAG can obtain the Link- layer address (MN LL-ID) and HNP(s) via the HI message (also the interface identifier of the mobile node's link-local address (MN LLA-ID) if available), it can create a neighbor cache entry for the Link-local Address and the routes for the whole HNP(s) even before the mobile node performs Neighbor Discovery. For the uplink packets from the mobile node after handover in (j), the NMAG forwards the packets to the PMAG through the tunnel established in step (f). The PMAG then decapsulates and sends them to the local mobility anchor. The timing of the context transfer and that of packet forwarding may be different. Thus, a new flag 'F' and Option Code values for it in the HI and HAck messages are defined to request forwarding. To request buffering, 'U' flag has already been defined in [RFC5568]. If the PMAG receives the HI message with the F flag set, it starts forwarding packets for the mobile node. The HI message with the U flag set may be sent earlier if the timing of buffering is different from that of forwarding. If packet forwarding is completed, the PMAG MAY send the HI message with the F flag set and the Option Code value being 2. By this message, the ARs on both ends can tear down the forwarding tunnel synchronously. The IP addresses in the headers of those user packets are summarized below: In Step (f), Inner source address: IP address of the CN Inner destination address: HNP or Mobile Node's IPv4 Home Address (IPv4-MN-HoA) Outer source address: IP address of the PMAG Outer destination address: IP address of the NMAG In Step (i), Yokota, et al. Expires July 1, 2010 [Page 12] Internet-Draft Proxy-based Fast Handover December 2009 Source address: IP address of the CN Destination address: HNP or IPv4-MN-HoA In Step (j), - from the mobile node to the NMAG, Source address: HNP or IPv4-MN-HoA Destination address: IP address of the CN - from the NMAG to the PMAG, Inner source address: HNP or IPv4-MN-HoA Inner destination address: IP address of the CN Outer source address: IP address of the NMAG Outer destination address: IP address of the PMAG - from the PMAG to the LMA, Inner source address: HNP or IPv4-MN-HoA Inner destination address: IP address of the CN Outer source address: IP address of the PMAG Outer destination address: IP address of the LMA In the case of the reactive handover for PMIPv6, since the mobile node does not send either the FBU or UNA, it would be more natural that the NMAG sends the HI to the PMAG after the mobile node has moved to the new link. The NMAG then needs to obtain the information of the PMAG beforehand. Such information could be provided, for example, by the mobile node sending the AP-ID on the old link and/or by the lower-layer procedures between the P-AN and N-AN. The exact method is not specified in this document. Figure 3 illustrates the reactive fast handover procedures for PMIPv6, where the bi- directional tunnel establishment is initiated by the NMAG. Yokota, et al. Expires July 1, 2010 [Page 13] Internet-Draft Proxy-based Fast Handover December 2009 PMAG NMAG MN P-AN N-AN (PAR) (NAR) LMA | | | | | | (a) ~~~ | | | | | ~~~ | | | | | | MN-AN connection | AN-MAG connection | | (b) |<--establishment-->|<-------establishment------>| | | | |(substitute for UNA and FBU)| | | | | | | | | | | | | | (c) | | | |<-----HI-------| | | | | | | | | | | | | | (d) | | | |-----HAck----->| | | | | | | | | | | | | | (e) | | | #=|<=======================| | | | #================>|=# | |<====================DL data======================# | | | | | | | (f) |=====================UL data===================>|=# | | | | #=|<================# | | | | #=========================>| | | | | | | / | | | | | | \ |(g) | | | | |--PBU-->| | | | | | | | | | |(h) | | | | |<--PBA--| | | |<====================DL data====================|<=======| | | | | | | | | | \ |=====================UL data===================>|=======>| / Figure 3: Reactive fast handover for PMIPv6 (NMAG initiated) The detailed descriptions are as follows: (a) The mobile node undergoes handover from the previous access network to the new access network. (b) The mobile node establishes a connection (e.g., radio channel) with the new access network, which triggers the establishment of the connection between the new access network and new MAG. The MN ID is transferred to the new MAG at this step for the subsequent procedures. The AP-ID on the old link (Old AP ID), which will be provided by either the mobile node or the new access network, is also transferred to the new MAG to help identify the previous MAG on the new link. This can be regarded as a substitute for the UNA and FBU. Yokota, et al. Expires July 1, 2010 [Page 14] Internet-Draft Proxy-based Fast Handover December 2009 (c) The new MAG sends the HI to the previous MAG. The HI message MUST have the P flag set and include the MN ID. The Context Request Option MAY be included to request additional context information on the mobile node to the previous MAG. (d) The previous MAG sends the HAck back to the new MAG with the P flag set. The HAck message MUST include the HNP(s) and/or IPv4- MN-HoA that is corresponding to the MN ID in the HI message and SHOULD include the MN LL-ID, only if it is valid (non zero), and the local mobility anchor address that is currently serving the mobile node. The context information requested by the new MAG MUST be included. If the requested context is not available for some reason, the previous MAG MUST return the HAck with the Code value 131. If the F flag is set in the HI at step (c) and forwarding is nevertheless not executable for some reason, the previous MAG MUST return the HAck with the Code value 132. (e) If the F flag in the HI is set at step (c), a bi-directional tunnel is established between the previous MAG and new MAG and packets destined for the mobile node are forwarded from the previous MAG to the new MAG over this tunnel. After decapsulation, those packets are delivered to the mobile node via the new access network. (f) The uplink packets from the mobile node are sent to the new MAG via the new access network and the new MAG forwards them to the previous MAG. The previous MAG then sends the packets to the local mobility anchor that is currently serving the mobile node. Steps (g)-(h) are the same as (k)-(l) in the predictive fast handover procedures. In step (c), the IP address of the PMAG needs to be resolved by the NMAG to send the HI to the PMAG. This information may come from the N-AN or some database that the NMAG can access. 4.2. Inter-AR Tunneling Operation When the PMAG (PAR) or NMAG (NAR), depending on the fast handover mode, receives the HI message with the F flag set, it prepares to send/receive the mobile node's packets to/from the other MAG and returns the HAck message with the same sequence number. The both MAGs SHOULD support the following encapsulation modes for the user packets, which are also defined for the tunnel between the local mobility anchor and MAG: o IPv4-or-IPv6-over-IPv6 [IPv4PMIPv6] Yokota, et al. Expires July 1, 2010 [Page 15] Internet-Draft Proxy-based Fast Handover December 2009 o IPv4-or-IPv6-over-IPv4 [IPv4PMIPv6] o IPv4-or-IPv6-over-IPv4-UDP [IPv4PMIPv6] o TLV-header UDP tunneling [GREKEY] o GRE tunneling with or without GRE key(s) [GREKEY] The PMAG and the NMAG MUST use the same tunneling mechanism for the data traffic tunneled between them. The encapsulation mode to be employed SHOULD be configurable. This specification recommends the following: 1. As the default behavior, the inter-MAG tunnel uses the same encapsulation mechanism as that for the PMIPv6 tunnel between the local mobility anchor and the MAGs. The PMAG and NMAG automatically start using the same encapsulation mechanism without a need for a special configuration on the MAGs or a dynamic tunneling mechanism negotiation between them. 2. Configuration on the MAGs can override the default mechanism specified in #1 above. The PMAG and NMAG MUST be configured with the same mechanism and this configuration is most likely to be uniform throughout the PMIPv6 domain. If the packets on the PMIPv6 tunnel cannot be uniquely mapped on to the configured inter-MAG tunnel, this scenario is not applicable and scenario #3 below SHOULD directly be applied. 3. An implicit or explicit tunnel negotiation mechanism between the MAGs can override the default mechanism specified in #1 above. The employed tunnel negotiation mechanism is outside the scope of this document. The necessary information MUST be transferred in the HI/HAck messages to distinguish mobile node's packets for forwarding in advance or at this time. Such information includes the HNP(s) (or IPv4-MN-HoA) and/or GRE key(s). In the case of GRE tunneling with GRE keys being used, for each mobility session, the NMAG selects the GRE key for the downlink packets and the PMAG selects the GRE key for the uplink packets. These GRE keys are exchanged between the PMAG and the NMAG using the GRE Key option as described in [GREKEY], e.g., In the case of the reactive mode as shown in Figure 3, the DL GRE key is communicated in the HI message while the UL GRE key is sent in the HAck message. For the downlink packets, the PMAG redirects mobile node's packets from the local mobility anchor towards the NMAG and if the mobile node is ready to receive those packets or the N-AN can handle them regardless of the state of the mobile node, the NMAG should immediately send them towards the N-AN; otherwise it should Yokota, et al. Expires July 1, 2010 [Page 16] Internet-Draft Proxy-based Fast Handover December 2009 buffer them until the mobile node is ready. For the uplink packets, the NMAG SHOULD reverse-tunnel them from the mobile node towards the PMAG and the PMAG sends them to the local mobility anchor. When the PMAG or NMAG receives the HI message with the U flag set, it prepares to buffer the mobile node's packets and returns the HAck message with the same sequence number. It MUST be followed by another HI message with the F flag set at an appropriate time to forward the buffered packets. If the MAG that received the HI message encounters an erroneous situation (e.g., insufficient buffer space), it SHOULD immediately send the HAck message with the cause of the error and cancel all tunneling operation. 4.3. IPv4 Support Considerations The motivation and usage scenarios of IPv4 protocol support by PMIPv6 are described in [IPv4PMIPv6]. The scope of IPv4 support covers the following two features: o IPv4 Home Address Mobility Support, and o IPv4 Transport Support. As for IPv4 Home Address Mobility Support, the mobile node acquires IPv4 Home Address (IPv4-MN-HoA) and in the case of handover, the PMAG needs to transfer IPv4-MN-HoA to the NMAG, which is the inner destination address of the packets forwarded on the downlink. For this purpose, IPv4 Address Option described in Section 6.2.7 is used. In order to provide IPv4 Transport Support, the NMAG needs to know the IPv4 address of the local mobility anchor (IPv4-LMAA) to send PMIPv6 signaling messages to the local mobility anchor in the IPv4 transport network. For this purpose, a new option called LMA Address (LMAA) Option is defined in Section 6.2.2 so as to convey IPv4-LMAA from the PMAG to NMAG. Yokota, et al. Expires July 1, 2010 [Page 17] Internet-Draft Proxy-based Fast Handover December 2009 5. PMIPv6-related Fast Handover Issues 5.1. Manageability Considerations This specification does not require any additional IP-level functionality on the local mobility anchor and the mobile node running in the PMIPv6 domain. A typical network interface that the mobile node could be assumed to have is one with the cellular network, where the network controls the movement of the mobile node. Different types of interfaces could be involved such as different generations (3G and 3.9G) or different radio access systems. This specification supports a mobile node with the single radio mode, where only one interface is active at any given time. The assigned IP address is preserved whether the physical interface changes or not and the mobile node can identify which interface should be used if there are multiple ones. 5.2. Expedited Packet Transmission The protocol specified in this document enables the NMAG to obtain parameters which would otherwise be available only by communicating with the local mobility anchor. For instance, the HNP(s) and/or IPv4-MN-HoA of a mobile node are made available to the NMAG through context transfer. This allows the NMAG to perform some procedures that may be beneficial. The NMAG, for example, could send a Router Advertisement (RA) with the HNP option to the mobile node as soon as its link attachment is detected (e.g., via receipt of a Router Solicitation message). Such an RA is recommended, for example, in scenarios where the mobile node uses a new radio interface while attaching to the NMAG; since the mobile node does not have information regarding the new interface, it will not be able to immediately send packets without first receiving an RA with HNP(s). Especially, in the reactive fast handover, the NMAG gets to know the HNP(s) assigned to the mobile node on the previous link at step (d) in Figure 3. In order to reduce the communication disruption time, the NMAG SHOULD expect the mobile node to keep using the same HNP and to send uplink packets before that step upon the mobile node's request. However, if the HAck from the PMAG returns a different HNP or the subsequent PMIPv6 binding registration for the HNP fails for some reason, then the NMAG MUST withdraw the advertised HNP by sending another RA with zero prefix lifetime for the HNP in question. This operation is the same as described in Section 6.12 of [RFC5213]. The protocol specified in this document is applicable regardless of whether link-layer addresses are used between a mobile node and its access router. A mobile node should be able to continue sending packets on the uplink even when it changes link. When link-layer addresses are used, the mobile node performs Neighbor Unreachability Yokota, et al. Expires July 1, 2010 [Page 18] Internet-Draft Proxy-based Fast Handover December 2009 Detection (NUD) [RFC4861], after attaching to a new link, probing the reachability of its default router. The new router should respond to the NUD probe, providing its link-layer address in the solicited Neighbor Advertisement, which is common in the PMIPv6 domain. Implementations should allow the mobile node to continue to send uplink packets while it is performing NUD. Yokota, et al. Expires July 1, 2010 [Page 19] Internet-Draft Proxy-based Fast Handover December 2009 6. Message Formats This document defines new Mobility Header messages for the extended HI and Hack and new mobility options for conveying context information. 6.1. Mobility Header 6.1.1. Handover Initiate (HI) This section defines extensions to the HI message in [RFC5568]. The format of the Message Data field in the Mobility Header is as follows: 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 +-------------------------------+ | Sequence # | +-+-+-+-+-------+---------------+-------------------------------+ |S|U|P|F|Resv'd | Code | | +-+-+-+-+-------+---------------+ | | | . . . Mobility options . . . | | +---------------------------------------------------------------+ (Note:P=1) IP Fields: Source Address The IP address of PMAG or NMAG Destination Address The IP address of the peer MAG Message Data: Sequence # Same as [RFC5568]. S flag Defined in [RFC5568] and MUST be set to zero in this specification. Yokota, et al. Expires July 1, 2010 [Page 20] Internet-Draft Proxy-based Fast Handover December 2009 U flag Buffer flag. Same as [RFC5568]. P flag Proxy flag. Used to distinguish the message from that defined in [RFC5568] and MUST be set in all new message formats defined in this document when using this protocol extension. F flag Forwarding flag. Used to request to forward the packets for the mobile node. Reserved Same as [RFC5568]. Code [RFC5568] defines this field and its values 0 and 1. In this specification, with the P flag set, this field can be set to zero by default or the following values: 2: Indicate the completion of forwarding 3: All available context transferred Code value 3 is set when the transfer of all necessary context information is completed with this message. This Code value is used in both cases where the context information is fragmented into several pieces and the last fragment is contained in this message and where the whole information is transferred in one piece. Mobility options: This field contains one or more mobility options, whose encoding and formats are defined in [RFC3775]. Required option In order to uniquely identify the target mobile node, the mobile node Identifier MUST be contained in the Mobile Node Identifier Option. The transferred context MUST be for one mobile node per message. In addition, the NMAG can request necessary mobility options by the Context Request Option defined in this document. Context Request Option This option MAY be present to request context information typically by the NMAG to the PMAG in the NMAG-initiated fast handover. Yokota, et al. Expires July 1, 2010 [Page 21] Internet-Draft Proxy-based Fast Handover December 2009 6.1.2. Handover Acknowledge (HAck) This section defines extensions to the HAck message in[RFC5568]. The format of the Message Data field in the Mobility Header is as follows: 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 +-------------------------------+ | Sequence # | +-+-+-+---------+---------------+-------------------------------+ |U|P|F|Reserved | Code | | +-+-+-+---------+---------------+ | | | . . . Mobility options . . . | | +---------------------------------------------------------------+ (Note:P=1) IP Fields: Source Address Copied from the destination address of the Handover Initiate message to which this message is a response. Destination Address Copied from the source address of the Handover Initiate message to which this message is a response. Message Data: The usages of Sequence # and Reserved fields are exactly the same as those in [RFC5568]. U flag Same as defined in Section 6.1.1. P flag Used to distinguish the message from that defined in [RFC5568] and MUST be set in all new message formats defined in this document when using this protocol extension. Yokota, et al. Expires July 1, 2010 [Page 22] Internet-Draft Proxy-based Fast Handover December 2009 F flag Same as defined in Section 6.1.1. Code Code values 0 through 4 and 128 through 130 are defined in [RFC5568]. In this specification, the meaning of Code value 0 is modified, 128 through 130 are reused, and 5, 6, 131 and 132 are newly defined. 0: Handover Accepted or Successful 5: Context Transfer Accepted or Successful 6: All available Context Transferred 128: Handover Not Accepted, reason unspecified 129: Administratively prohibited 130: Insufficient resources 131: Requested Context Not Available 132: Forwarding Not Available Mobility options: This field contains one or more mobility options, whose encoding and formats are defined in [RFC3775]. The mobility option that uniquely identifies the target mobile node MUST be copied from the corresponding HI message and the transferred context MUST be for one mobile node per message. Required option(s) All the context information requested by the Context Request Option in the HI message SHOULD be present in the HAck message. The other cases are described below. In the case of the PMAG-initiated fast handover, when the PMAG sends the HI message to the NMAG with the context information and the NMAG successfully receives it, the NMAG returns the HAck message with Code value 5. In the case of the NMAG-initiated fast handover, when the NMAG sends the HI message to the PMAG with or without Context Request Option, the PMAG returns the HAck message with the requested or default context information (if any). If all available context information is transferred, the PMAG sets the Code value in the HAck message to 6. If more context information is available, the PMAG sets the Code value in the HAck to 5 and the NMAG MAY send new HI message(s) to retrieve the rest of the available context information. If none of the requested context information is available, the PMAG Yokota, et al. Expires July 1, 2010 [Page 23] Internet-Draft Proxy-based Fast Handover December 2009 returns the HAck message with Code value 131 without any context information. 6.2. Mobility Options 6.2.1. Context Request Option This option is sent in the HI message to request context information on the mobile node. If a default set of context information is defined and always sufficient, this option is not used. This option is more useful to retrieve additional or dynamically selected context information. Context Request Option is typically used for the reactive (NMAG- initiated) fast handover mode to retrieve the context information from the PMAG. When this option is included in the HI message, all the requested context information SHOULD be included in the HAck message in the corresponding mobility option(s) (e.g., HNP, LMAA or MN LL-ID mobility options). The default context information to request is the Home Network Prefix Option. If the Mobile Node link-layer is available and used, the Mobile Node Link-layer Identifier Option MUST also be requested. 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 | Reserved | +---------------+---------------+-------------------------------+ | Req-type-1 | Req-length-1 | Req-type-2 | Req-length-2 | +---------------------------------------------------------------+ | Req-type-3 | Req-length-3 | Req-option-3 | +---------------------------------------------------------------+ | ... | Option-Type TBD1 Option-Length The length in octets of this option, not including the Option Type and Option Length fields. Reserved This field is unused. It MUST be initialized to zero by the sender and MUST be ignored by the receiver. Req-type-n The type value for the n'th requested option. Yokota, et al. Expires July 1, 2010 [Page 24] Internet-Draft Proxy-based Fast Handover December 2009 Req-length-n The length of the n'th requested option excluding the Req-type-n and Req-length-n fields. Req-option-n The optional data to uniquely identify the requested context for the n'th requested option. In the case where there are only Req-type-n and Req-length-n fields, the value of the Req-length-n is set to zero. If additional information besides the Req-type-n is necessary to uniquely specify the requested context, such information follows after the Req-length-n. For example, when the requested contexts start with the HNP Option (type=22), the MN Link-layer ID Option (type=25) and the Vendor-Specific Option (type=19), the required option format looks as follows: | ... | +---------------+---------------+---------------+---------------+ |Option-Type=CRO| Option-Length | Reserved | +---------------+---------------+---------------+---------------+ | Req-type-N=22 | Req-length-N=0| Req-type-N=25 | Req-length-N=0| +---------------+---------------+-------------------------------+ | Req-type-N=19 | Req-length-N=5| Vendor-ID | +-------------------------------+---------------+---------------+ | Vendor-ID | Sub-Type | | +-----------------------------------------------+ | | ... | The first two options can uniquely identify the requested contexts (i.e., the HNP and MN Link-layer ID) by the Req-type, so the Req- length is set to zero; however, the subsequent Vendor-Specific Option further needs the Vendor-ID and Sub-type to identify the requested context, so these parameters follow and the Req-length is set to 5. Note that the exact values in the Vendor-ID ans Sub-Type follow [RFC5094]. 6.2.2. Local Mobility Anchor Address (LMAA) Option This option is used to transfer the Local Mobility Anchor IPv6 Address (LMAA) or its IPv4 Address (IPv4-LMAA), with which the mobile node is currently registered. The detailed definition of the LMAA is described in [RFC5213]. 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 | Option-Code | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local Mobility Anchor Address ... | Yokota, et al. Expires July 1, 2010 [Page 25] Internet-Draft Proxy-based Fast Handover December 2009 Option-Type TBD2 Option-Length 18 or 6 Option-Code 0 Reserved 1 IPv6 address of the local mobility anchor (LMAA) 2 IPv4 address of the local mobility anchor (IPv4- LMAA) Reserved This field is unused. It MUST be initialized to zero by the sender and MUST be ignored by the receiver. Local Mobility Anchor Address If Option-Code is 1, the LMA IPv6 address (LMAA) is inserted. If Option-Code is 2, the LMA IPv4 address (IPv4-LMA) is inserted. 6.2.3. Mobile Node Link-local Address Interface Identifier (MN LLA-IID) Option This option is used to transfer the interface identifier of the mobile node's IPv6 Link-local Address that is used in the P-AN. In deployments where the interface identifier is assigned by the network, or it is known to the network, this option is used to transfer this identifier from the PMAG to NMAG. 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + Interface Identifier + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Option-Type TBD3 Option-Length 10 Reserved This field is unused. It MUST be initialized to zero by the sender and MUST be ignored by the receiver. Yokota, et al. Expires July 1, 2010 [Page 26] Internet-Draft Proxy-based Fast Handover December 2009 Interface Identifier The Interface Identifier value used for the mobile node's IPv6 Link-local address in the P-AN. 6.2.4. Home Network Prefix Option This option is used to transfer the home network prefix that is assigned to the mobile node in the P-AN. The Home Network Prefix Option defined in [RFC5213] is used for this. 6.2.5. Link-local Address Option This option is used to transfer the link-local address of the PMAG (PMAG). The Link-local Address Option defined in [RFC5213] is used for this. 6.2.6. GRE Key Option This option is used to transfer the GRE Key for the mobile node's data flow over the bi-directional tunnel between the PMAG and NMAG. The message format of this option follows the GRE Key Option defined in [GREKEY]. The GRE Key value uniquely identifies each flow and the sender of this option expects to receive packets of the flow from the peer AR with this value. 6.2.7. IPv4 Address Option As described in Section 4.3, if the mobile node runs in IPv4-only mode or dual-stack mode, it requires IPv4 home address (IPv4-MN-HoA). This option is used to transfer the IPv4 home address if assigned on the previous link. The format of this option follows the IPv4 Home Address Request Option defined in [IPv4PMIPv6]. 6.2.8. Vendor-Specific Mobility Option This option is used to transfer any other information defined in this document. The format and used values of this option follow the Vendor-Specific Mobility Option defined in [RFC5094]. Yokota, et al. Expires July 1, 2010 [Page 27] Internet-Draft Proxy-based Fast Handover December 2009 7. Security Considerations Security issues for this document follow those for PMIPv6 [RFC5213] and FMIPv6 [RFC5568]. In PMIPv6, the MAG and local mobility anchor are assumed to share security associations. In FMIPv6, the access routers (i.e., the PMAG and NMAG in this document) are assumed to share security associations. The Handover Initiate (HI) and Handover Acknowledge (HAck) messages exchanged between the PMAG and NMAG MUST be protected using end-to- end security association(s) offering integrity and data origin authentication. The PMAG and the NMAG MUST implement IPsec [RFC4301] for protecting the HI and HAck messages. IPsec Encapsulating Security Payload (ESP) [RFC4303] in transport mode with mandatory integrity protection SHOULD be used for protecting the signaling messages. Confidentiality protection SHOULD be used if sensitive context related to the mobile node is transferred. IPsec ESP [RFC4303] in tunnel mode SHOULD be used to protect the mobile node's packets at the time of forwarding if the link between the PMAG and NMAG exposes the mobile node's packets to more threats than if they had followed their normal routed path. Yokota, et al. Expires July 1, 2010 [Page 28] Internet-Draft Proxy-based Fast Handover December 2009 8. IANA Considerations This document defines new flags and status codes in the HI and HAck messages as well as three new mobility options. The Type values for these mobility options are assigned from the same numbering space as allocated for the other mobility options defined in [RFC3775]. Those for the flags and status codes are assigned from the corresponding numbering space defined in [RFC5568] and requested to be created as new tables in the IANA registry (marked with asterisks). New values for these registries can be allocated by Standards Action or IESG approval [RFC5226]. Mobility Options Value Description Reference ----- ------------------------------------- ------------- TBD1 Context Request Option Section 6.2.1 TBD2 Local Mobility Anchor Address Option Section 6.2.2 TBD3 Mobile Node Link-local Address Interface Identifier Option Section 6.2.3 Handover Initiate Flags (*) Registration Procedures: Standards Action or IESG Approval Flag Value Description Reference ---- ----- ----------------------------------- ------------- S 0x80 Assigned Address Configuration flag [RFC5568] U 0x40 Buffer flag [RFC5568] P 0x20 Proxy flag Section 6.1.1 F 0x10 Forwarding flag Section 6.1.1 Handover Acknowledge Flags (*) Registration Procedures: Standards Action or IESG Approval Flag Value Description Reference ---- ----- ------------------------------- ------------- U 0x80 Buffer flag Section 6.1.2 P 0x40 Proxy flag Section 6.1.2 F 0x20 Forwarding flag Section 6.1.2 Handover Initiate Status Codes (*) Registration Procedures: Standards Action or IESG Approval Code Description Reference ---- -------------------------------------- ------------- 0 FBU with the PCoA as source IP address [RFC5568] 1 FBU whose source IP address is not PCoA [RFC5568] 2 Indicate the completion of forwarding Section 6.1.1 3 All available context transferred Section 6.1.1 Yokota, et al. Expires July 1, 2010 [Page 29] Internet-Draft Proxy-based Fast Handover December 2009 4-255 Unassigned Handover Acknowledge Status Codes (*) Registration Procedures: Standards Action or IESG Approval Code Description Reference ---- --------------------------------------- ------------- 0 Handover Accepted or Successful Section 6.1.2 (with NCoA valid) [RFC5568] 1 Handover Accepted, NCoA not valid [RFC5568] 2 Handover Accepted, NCoA assigned [RFC5568] 3 Handover Accepted, use PCoA [RFC5568] 4 Message sent unsolicited [RFC5568] 5 Context Transfer Accepted or Successful Section 6.1.2 6 All available Context Transferred Section 6.1.2 7-127 Unassigned 128 Handover Not Accepted, reason unspecified [RFC5568] 129 Administratively prohibited [RFC5568] 130 Insufficient resources [RFC5568] 131 Requested Context Not Available Section 6.1.2 132 Forwarding Not Available Section 6.1.2 133-255 Unassigned Yokota, et al. Expires July 1, 2010 [Page 30] Internet-Draft Proxy-based Fast Handover December 2009 9. Acknowledgments The authors would like to specially thank Vijay Devarapalli and Sri Gundavelli for their thorough reviews of this document. The authors would also like to thank Charlie Perkins, Desire Oulai, Ahmad Muhanna, Giaretta Gerardo, Domagoj Premec, Marco Liebsch, Fan Zhao, Julien Laganier and Pierrick Seite for their passionate discussions in the working group mailing list. Yokota, et al. Expires July 1, 2010 [Page 31] Internet-Draft Proxy-based Fast Handover December 2009 10. References 10.1. Normative References [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5568] Koodli, R., "Mobile IPv6 Fast Handovers", RFC 5568, July 2009. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303, December 2005. [RFC5094] Devarapalli, V., Patel, A., and K. Leung, "Mobile IPv6 Vendor Specific Option", RFC 5094, December 2007. [IPv4PMIPv6] Wakikawa, R., Ed. and S. Gundavelli, "IPv4 Support for Proxy Mobile IPv6", draft-ietf-netlmm-pmip6-ipv4-support-17.txt, September 2009. [GREKEY] Muhanna, A., Ed., "GRE Key Option for Proxy Mobile IPv6", draft-ietf-netlmm-grekey-option-09.txt, May 2009. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. 10.2. Informative References [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [RFC4988] Koodli, R. and C. Perkins, "Mobile IPv4 Fast Handovers", RFC 4988, October 2007. Yokota, et al. Expires July 1, 2010 [Page 32] Internet-Draft Proxy-based Fast Handover December 2009 Appendix A. Applicable Use Cases A.1. PMIPv6 Handoff Indication PMIPv6 [RFC5213] defines the Handoff Indicator Option and describes the type of the handoff and the values to set to the option. This document proposes one approach to determining the handoff type by the NMAG when the handoff of the mobile node is executed. According to [RFC5213], the following handoff types are defined: 0) Reserved 1) Attachment over a new interface 2) Handoff between two different interfaces of the mobile node 3) Handoff between mobile access gateways for the same interface 4) Handoff state unknown 5) Handoff state not changed (Re-registration) Assuming that there is a valid MN Link-layer Identifier (MN LL-ID), the following solution can be considered. When the NMAG receives the MN LL-ID from the PMAG in the MN LL-ID option via the HI or HAck message, the NMAG compares it with the new MN LL-ID that is obtained from the mobile node in the N-AN. If these two MN LL-IDs are the same, the handoff type falls into 3) and the Handoff Indicator value is set to 3. If these two MN LL-IDs are different, the handoff is likely to be 2) since the HI/HAck message exchange implies that this is a handoff not a multi-homing, therefore the Handoff Indicator value can be set to 2. If there is no HI/HAck exchange performed prior to the network attachment of the mobile node in the N-AN, the NMAG may infer that this is a multi-homing case and set the Handoff Indicator value to 1. In the case of re-registration, the MAG, to which the mobile node is attached, can determine if the handoff state is not changed, so the MAG can set the HI value to 5 without any additional information. If none of them can be assumed or there is no valid MN LL-ID available, the NMAG may set the value to 4. A.2. Local Routing Section 6.10.3 in [RFC5213] describes that if EnableMAGLocalRouting flag is set, when two mobile nodes are attached to one MAG, the traffic between them may be locally routed. If one mobile node moves from this MAG (PMAG) to another MAG (NMAG) and if the PMAG does not detect the mobile node's detachment, it will continue to forward Yokota, et al. Expires July 1, 2010 [Page 33] Internet-Draft Proxy-based Fast Handover December 2009 packets locally forever. This situation is more likely to happen in the reactive fast handover with WLAN access, which does not have the capability to detect the detachment of the mobile node in a timely manner. PFMIPv6 can be applied to handle this case. When the mobile node attaches to the NMAG, the NMAG sends the HI message to the PMAG with the 'F' flag set, which makes the PMAG realize the detachment of the mobile node and establish the inter-MAG tunnel. The PMAG immediately stops the local routing and sends the packets for the mobile node to the NMAG via that tunnel, which are then delivered to the mobile node on the new link. Yokota, et al. Expires July 1, 2010 [Page 34] Internet-Draft Proxy-based Fast Handover December 2009 Appendix B. Change Log Changes at -00 * Added separate sections for MH and ICMP. * Clarified usage of HNP and IPv4-MN-HoA throughout the document. * Added IANA Considerations. * Added section on Other Considerations, including operation of uplink packets when using link-layer addresses, multiple interface usage and transmission of RA to withdraw HNP in the event of failure of PMIP6 registration. * Revised Security Considerations. Changes from -00 to -01 * Removed ICMPv6-based message format. * Clarified HI/HAck exchange in the predictive mode (step (e) in Figure 2). * Clarified information retrieval about the PMAG in the reactive mode. * Removed the extension to the GRE Key Option. * Clarified the handoff type considerations in Appendix A. * Home Network Prefix Option, Link-local Address Option and Vendor-Specific Mobility Option are added. Changes from -01 to -02 * Aligned HI/HAck message formats with draft-ietf-mipshop-rfc5268bis-00.txt. * Revised Section 8 removing the request for the type assignment of HI/HAck Mobility Headers. Changes from -02 to -03 * Updated HI/HAck message formats according to draft-ietf-mipshop-rfc5268bis-01.txt. Yokota, et al. Expires July 1, 2010 [Page 35] Internet-Draft Proxy-based Fast Handover December 2009 * Cleaned up Figure 2 and Figure 3. * Moved PMIP domain boundary crossing situation in Section 4.1 to Appendix A.3. * Removed the alternative protocol operation with an unsolicited HAck from Section 4.1. * Modified Code values in the HAck message in order to avoid collision with those in draft-ietf-mipshop-rfc5268bis-01.txt. * Clarified the usage scenarios of Context Request Option. * Modified the description of Code values in the HAck message. * Changed the container for the IPv4-LMAA from IPv4 Address option to the LMAA option. * Made Confidentiality protection "SHOULD" for context transfer. Changes from -03 to -04 * Added more explanations about MIPv6, FMIPv6 and PMIPv6 in Abstract. * Moved Figure 1 to Section 4. * More clearly indicated the FMIPv6 messages that are not applicable in the PMIPv6 context. * Mandated the support of IP Sec on the PMAG and NMAG in order to protect signaling and user packets and the context information. * Added a new section for the inter-AR tunneling operation (Section 4.2). * Added descriptions about the encapsulation type in Sections 4.1 and 4.3. * Added a description about buffering requirements on the MAG in Section 4.1. * Added a description about the timing of L2 and L3 connection establishments in Section 4.1. * Added a new section for PMIPv6-related fast handover issues (Section 5) and a description about preferable behaviors of the mobile node and MAG to reduce packet loss. Yokota, et al. Expires July 1, 2010 [Page 36] Internet-Draft Proxy-based Fast Handover December 2009 * Added Acknowledgments section (Section 9). * Added a new section for local routing in Appendix (A.2). Changes from -04 to -05 * Fixed Figure 2 (step (i)). * Defined the Mobile Network Interface Identifier (MN-IID) mobility option in Section 6.2.4 (swapped with old Section 6.2.5), and added it to IANA considerations (Section 8). * Changed from SHOULD to MUST regarding the inclusion of the MN-ID, MN-HNP, MN-IID and the LMAA options in the HI message (step (c) in Section 4.1). * The optional behavior of the NMAG that allows it to send uplink packets directly to the local mobility anchor before the PBU/ PBA exchange was removed from section 4.2 (as out of scope). * In Section A.3, the description about the HA address assignment from the NAR to the mobile node was removed (as out of scope). Changes from -05 to -06 * Added 'P' flag in the HI and Hack messages to distinguish them from those in FMIPv6. * Made editorial corrections in Section 2 (Introduction), Section 3 (Terminology), Section 4 (Protocol Overview) and Section 4.2 (Inter-AR Tunneling Operation). * Added a description on how forwarded packets should be handled in the access network at step (f) in Section 4.1. * Added all types of encapsulation methods that should be supported in Section 4.1. * Revised the Code values for the HI message in Section 6.1.1. * Revised the Code values for the HAck message in Section 6.1.2 and added a description of its usage at step (d) of the reactive handover mode in Section 4.1. * Removed the definition of the IP Address Option in Section 6.2.3 and moved to Section 6.2.7, which currently refers to the IPv4 Home Address Option defined by RFC5555. Revised the IANA Consideration section accordingly. Yokota, et al. Expires July 1, 2010 [Page 37] Internet-Draft Proxy-based Fast Handover December 2009 * Removed the Option-Code from the Mobile Node Identifier (MN IID) Option. * Removed Appendix A.3 (Handling of PMIPv6/MIPv6 switching). Changes from -06 to -07 * Added explanations about defining and setting the 'P' flag for the HI and Hack messages in Sections 4 and 4.1. * Corrected the references for the encapsulation types in Section 4.1. * Modified the Code values for the HI message in Section 6.1.1 to avoid overlapping with those in draft-ietf-mipshop-rfc5268bis-01.txt. * Modified the reference for the IPv4 Address Option from RFC5555 to [IPv4PMIPv6] in Section 6.2.7. Changes from -07 to -08 * Corrected the reference for the TLV-header UDP encapsulation in Section 4.1. * Updated the version number of the reference document [IPv4PMIPv6] and the option name defined by that document in Section 6.2.7. Changes from -08 to -09 * Added a paragraph at the beginning of Section 4 describing the assumption related to the lower layer signaling. * Added a new section on the manageability considerations in Section 5 describing the configurations on the network and the mobile node assumed in this document. * Modified the assumed configuration of the MAG regarding its link-layer address in Section 5 (Section 5.2 in version -09). * Specified the requested option to identify the target MN for the inter-AR tunneling in Section 6.1.1. * Specified the default context information in the Context Request Option in Section 6.2.1. Yokota, et al. Expires July 1, 2010 [Page 38] Internet-Draft Proxy-based Fast Handover December 2009 Changes from -09 to -10 * Revised the document based on the comments from TSV-DIR, SEC- DIR, OPS-DIR and GEN-ART. + Split the abstract section in half for readability. + Added the definition of Localized Mobility Anchor (local mobility anchor) in Section 3. + Added the purpose of this document at the beginning of Section 4 to make the paragraph more complete. + Revised the third paragraph of the Security Consideration section for more precise expression. + Moved the description about the requirement to set the 'P' flag in HI/HAck to Sections 6.1.1 and 6.1.2. Also, noted the 'P' flag setting below the message formats. + Described the both 'P' and 'F' flags as newly defined ones in Section 4. + Clarified the usage of the Context Request Option if a default set of context information is defined in Section 6.2.1 (changed from "not mandatory" to "not used"). + Modified the identifier for the interface on the MN to the MN's link-layer ID (MN LL-ID). + Corrected the local routing operation of the PMAG in Appendix A.2. * Revised the descriptions about the encapsulation mechanism for the inter-MAG tunnel in Section 4.2 and other related parts for clarification. * Also listed the new flags and status codes for the HI/HAck messages in the IANA Considerations section. * Elaborated on the example use of the Context Request Option in Section 6.2.1. Changes from -10 to -11 * Changed the term "MN Interface Identifier (MN-IID) option" to "MN Link-local Address Interface Identifier (MN LLA-IID) option" in Section 6.2.3. Its usage is valid only when the Yokota, et al. Expires July 1, 2010 [Page 39] Internet-Draft Proxy-based Fast Handover December 2009 network assigns the interface identifier. * Revised the description of the neighbor cache entry in Section 4.1 to include the MN LLA-IID. Changes from -11 to -12 * Changed the term "HO-Initiate" to "Handover indication". * Added the handover trigger from the PMAG to the mobile node ("Handover command") to clarify the timing of handover in Figure 2. * Revised IANA Considerations to include all values that are defined in RFC5568, but not in the IANA Registry yet. Yokota, et al. Expires July 1, 2010 [Page 40] Internet-Draft Proxy-based Fast Handover December 2009 Authors' Addresses Hidetoshi Yokota KDDI Lab 2-1-15 Ohara, Fujimino Saitama, 356-8502 Japan Email: yokota@kddilabs.jp Kuntal Chowdhury Starent Networks 30 International Place Tewksbury, MA 01876 USA Email: kchowdhury@starentnetworks.com Rajeev Koodli Starent Networks 30 International Place Tewksbury, MA 01876 USA Email: rkoodli@starentnetworks.com Basavaraj Patil Nokia 6000 Connection Drive Irving, TX 75039 USA Email: basavaraj.patil@nokia.com Frank Xia Huawei USA 1700 Alma Dr. Suite 500 Plano, TX 75075 USA Email: xiayangsong@huawei.com Yokota, et al. Expires July 1, 2010 [Page 41]