Abstract:
A network component comprising at least one processor configured to implement a method comprising promoting an optimization of a communications route associated with a mobile node (MN) and a correspondent node (CN) using Internet Protocol version 4 (IPv4) packets is disclosed. Also disclosed is a network comprising a mobility access gateway (MAG) in communication with a MN, and a CN in communication with the MAG and that desires to communicate with the MN, wherein a communications route between the MN and the CN is optimized using IPv4 signaling. Included is a method comprising promoting an optimization of a communications route between a MN and a CN using IPv4 signaling. Standalone CNs and CNs under a MAG embodiments are supported.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 60/987,354 filed Nov. 12, 2007 by Qin et al. and entitled “PMIPv6 Route Optimization Protocol,” which is incorporated herein by reference as if reproduced in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO A MICROFICHE APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND 
       [0004]    In modern wireless access networks, mobile nodes (MNs) allow users to freely move between access points without the user having to configure the MN for each access point. Specifically, when the MN reaches the coverage limit of one access point, the access point hands over the MN to an adjacent access point, typically without any disruption to the MN&#39;s service. In Internet Protocol version 6 (IPv6) networks, a process called proxy mobile IPv6 defines a relatively orderly and efficient network-based method for handing off the MN between adjacent access points. Specifically, proxy mobile IPv6 allows a mobility access gateway (MAG) and a local mobility anchor (LMA) track the movements of the MN and initiate the required mobility signaling on behalf of MN. In addition, the MN always uses the same IPv6 home address before and handover, and does the MN does not participate in the handover or any other mobility signaling. Proxy mobile IPv6 also defines a route optimization procedure. Unfortunately, proxy mobile IPv6 do not support Internet Protocol version 4 (IPv4), and thus cannot be implemented using IPv4 signaling. 
       SUMMARY 
       [0005]    In a first embodiment, the disclosure includes a network component comprising at least one processor configured to implement a method comprising promoting a optimization of a communications route associated with a MN and a correspondent node (CN) using IPv4 packets. 
         [0006]    In a second embodiment, the disclosure includes a network comprising a mobility access gateway (MAG) in communication with a MN, and a CN in communication with the MAG and that desires to communicate with the MN, wherein a communications route between the MN and the CN is optimized using IPv4 signaling. 
         [0007]    In a third embodiment, the disclosure includes a method comprising promoting an optimization of a communications route between a MN and a CN using IPv4 signaling. 
         [0008]    These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. 
           [0010]      FIG. 1  is a schematic diagram of an embodiment of a wireless system showing the operation of Proxy Mobile IPv6. 
           [0011]      FIG. 2  is a schematic diagram of an embodiment showing the operation of Proxy Mobile IPv6 support of an IPv4 network. 
           [0012]      FIG. 3  is a protocol diagram of an embodiment of an IPv4 attachment procedure. 
           [0013]      FIG. 4  is a protocol diagram of an embodiment of a Proxy Home Test (PHoT) procedure. 
           [0014]      FIG. 5  is a protocol diagram of an embodiment of a Proxy Care-of Test (PCoT) procedure. 
           [0015]      FIG. 6  is a protocol diagram of an embodiment of a handover procedure. 
           [0016]      FIG. 7  is a protocol diagram of an embodiment of a route optimization procedure. 
           [0017]      FIG. 8  is a schematic diagram of an embodiment of a PHoT message. 
           [0018]      FIG. 9  is a schematic diagram of an embodiment of a PHoT init (PHoTI) message. 
           [0019]      FIG. 10  is an illustration of an embodiment general-purpose computer system. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents. 
         [0021]    Disclosed herein is a method and system for implementing IPv6 route optimization using components that do not support IPv6, such as IPv4 components. The methods include a PHoT procedure and a PCoT procedure that may allow the CN to verify the reachability of the MN&#39;s home address (HoA) and care-of address (CoA) using IPv4 signaling using the optimized route. Specifically, the PHoT and PCoT procedures may be implemented between the MN&#39;s MAG and the CN or the CN&#39;s MAG. 
         [0022]      FIG. 1  illustrates an embodiment of a wireless system  100 . The system  100  may comprise a MN  102 , a plurality of MAGs  104 , a LMA  106 , a network  108 , a CN  110 , and an authentication, authorization, and accounting (AAA) server  112 , all of which are in communication with each other as shown in  FIG. 1 . The system may be an Internet Protocol (IP) system, such as an IPv4 system, an IPv6 system as shown in  FIG. 1 , or combinations thereof. Alternatively, the system may be any other type of wireless system implementing any other suitable protocol. It will be appreciated that  FIG. 1  is only one embodiment of the system  100 , and that the system  100  may comprise additional components including additional MNs  102 , MAGs  104 , LMAs  106 , networks  108 , CNs  110 , AAA servers  112 , or combinations thereof. 
         [0023]    The MN  102  may be any device or component that uses the MAG  104  and/or LMA  106  to communicate with the CN  110 . Typically, the MN  102  is a mobile user-oriented device that communicates wirelessly with the LMA  106  via the MAG  104 , but the MN  102  should not be limited as such. For example, the MNs  102  may be cellular phones, notebook computers, personal digital assistants (PDAs), or any other wireless devices. Alternatively, the MNs  102  may be a component that exchanges data between the system  100  and an external network, such as a wireless router. 
         [0024]    The MAGs  104  may be any devices or components that exchange data between the MN  102  and the LMA  106 . The MAGs  104  may be routers in that they forward packets that are not explicitly addressed to themselves to other nodes. The MAGs  104  may also perform mobility signaling with the LMA  106  and other MAGs  104  on behalf of MN  102  and/or perform mobility signaling with the MN  102  on behalf of the LMA  106 . The MAGs  104  may reside on the access link where the MN  102  is anchored and perform mobility management on behalf of a MN  102 . As such, the MAGs  104  may be responsible for detecting the MN&#39;s  102  movements on the access links and for sending binding registrations to the LMA  106 . In some embodiments, the MAGs  104  may comprise or may be part of a base transceiver station (BTS), a base station controller, or the like, and/or may use such to communicate with the MN  102 . 
         [0025]    The LMA  106  may be any device or component that allows the MN  102  to communicate with the network  108  and/or the CN  110 . The LMA  106  may communicate with the MNs  102  through the MAGs  104  or may communicate directly with the MNs  102 . The LMA  106  may be a router in that it forwards packets that are not explicitly addressed to the LMA  106  to other nodes. The LMA  106  may be responsible for maintaining the MN&#39;s  102  reachability state and may be the topological anchor point for the MN&#39;s  102  home network prefix. In an embodiment, the LMA  106  may comprise or be a part of a Home Agent. As such, the LMA  106  may act as a dynamic host configuration protocol (DHCP) client and/or an AAA client, and may comprise an address cache. In addition, the LMA  106  may handle IP routing for the MNs  102  that may roam into a foreign network. 
         [0026]    In an embodiment, the network  108  may be any device, component, or network that exchanges data between the LMA  106  and the CN  110 . For example, the network  108  may be a Packet Switched Network (PSN), such as a local area network (LAN), a metropolitan area network (MAN), a wide area network (WAN), an intranet, or the Internet. Alternatively, the network  108  may be a circuit switched network, such as a public switched telephone network (PSTN), or any other network. 
         [0027]    The CN  110  may be any device or component that desires to communicate with the MN  102  or with which the MN  102  desires to communicate. The CN  110  may be another MN or may be a fixed device. It will be appreciated that while the CN  110  shown in  FIG. 1  is not in the same LMA or MAG domain as the MN  102 , in some embodiments the CN  110  may be in the same LMA and/or MAG domain as the MN  102 . 
         [0028]    The AAA server  112  may be any device, component, or network that comprises authentication, authorization, and/or accounting data and/or implements authentication, authorization, and/or accounting functions. The AAA server  112  may communicate with the MN  102 , MAGs  104 , and/or LMA  106  using any suitable protocol, including IP, RADIUS, and DIAMETER. 
         [0029]    The components described above may communicate with each other via fixed and/or wireless links using a variety of technologies. The wireless links may be created dynamically when the MN  102  attaches to the LMA  106  directly or through the MAGs  104 . The wireless links may be implemented using a multiple access technology, such as Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or Time Division Multiple Access (TDMA). Examples of suitable wireless link technologies include the Internet Engineering Task Force (IETF), Worldwide Interoperability for Microwave Access (WiMAX), Wireless Fidelity (WiFi), Wideband CDMA (WCDMA), Global System for Mobile communications (GSM), Enhanced Data for GSM Evolution (EDGE), Universal Mobile Telecommunication Systems (UMTS), Third Generation Partnership Project (3GPP), Third Generation Partnership Project 2 (3GPP2), Advanced Mobile Phone Service (AMPS), one of the Institute of Electrical and Electronic Engineers (IEEE) 802 wireless networks, such as 802.16d/e, or any other wireless network. The remaining components may be coupled together via fixed links, such as electrical or optical links. Examples of suitable fixed link technologies include IP, Ethernet, Asynchronous Transfer Mode (ATM), Frame Relay, Synchronous Optical Network (SONET), and Synchronous Digital Hierarchy (SDH). The fixed and wireless links may have a fixed bandwidth such that a fixed amount of data is transported over the link, or may have a variable-sized bandwidth. 
         [0030]    When the system  100  is a Proxy Mobile IPv6 system, the system  100  may implement an attachment and handover procedure to ensure constant communications between the MN  102  and the CN  110 . Briefly, the attachment procedure comprises attachment between the MN  102  and a MAG  104 . Next, the MAG  104  authenticates the MN  102  using an AAA policy obtained from the AAA server  112 . The MN  102  then requests an IP address from the MAG  104 , for example using a DHCP request, which causes a proxy binding update (PBU) and proxy binding acknowledgement (PBA or PBAck) procedure to occur between the MAG  104  and the LMA  106 . A communications tunnel  114  is subsequently formed between the MAG  104  and the LMA  106 , and the IP Address is conveyed to the MN  102 , for example using DHCP. The MN  102  then configures the MN&#39;s IP address, known at its HoA, and commences communications with the CN  110 . Communications from the CN  110  to the MN  102  are first routed to the LMA  106 , then to the proxy CoA at the MAG  104 , and then to the HoA in the MN  102 . When the MN  102  changes locations sufficient to change the MAG  104  with which it communicates, at least part of the above process may be repeated. Consequently, the communications tunnel  114  may be torn down and a new tunnel may be constructed between the LMA  106  and the new MAG  104  in communication with the MN  102 . The MN  102  may be unaware of any of the signaling that occurs between the MAGs  104  and the LMA  106 . 
         [0031]    In Mobile IPv6, the routing of communications between the CN  110  and the MN  102  can be less than optimal because it is not the most direct path between the CN  110  and the MN  102 . Specifically, packets from the CN  110  to the MN  102  may first go to the LMA  106  and then are directly routed to the MN  102  via the MAG  104 . In addition, packets from the MN  102  to the CN  110  may be theoretically routed directly to the CN  110 , however in practice these packets are routed through the LMA  104  due to ingress filtering. As such, a return routability procedure has been created to facility direct packet routing between the CN  110  and the MN  102 . 
         [0032]    While the above procedures are useful in IPv6 networks, not all networks support IPv6. Specifically, many existing MNs and network components are only configured to support IPv4, and there may be little need or desire to replace or upgrade them to support IPv6.  FIG. 2  is an embodiment of such an IPv4 network  400 . The network  400  comprises a plurality of MNs  402 , MAGs  404 , and LMAs  406  in communication with each other as shown in  FIG. 2 . The MNs  402 , MAGs  404 , and LMAs  406  may be substantially the same as the MN  102 , MAGs  104 , and LMA  106 , respectively, described above. However, the communications between the LMAs  406  and the MAGS  404  (and perhaps other components) may be implemented using IPv4 instead of IPv6, as indicated by the dashed oval  408 . As such, the LMAs  406  may be configured with IPv4 addresses, such as IPv4-LMAA1 for LMA  1  and IPv4-LMAA2 for LMA  2 . Similarly, the MAGs  404  may be configured with IPv4 addresses, such as IPv4-Proxy-CoA1 for MAG  1  and IPv4-Proxy-CoA2 for MAG  2 . Finally, the MNs  402  may also be IPv4 components, and as such may be configured with IPv4 addresses, such as IPv4-MN-HoA1 for MN  1 , IPv4-MN-HoA2 for MN  2 , and IPv4-MN-HoA3 for MN  3 . 
         [0033]      FIG. 3  illustrates an embodiment of an attachment procedure  500  that may be implemented in IPv4 networks. The attachment procedure  500  may begin when a MN attaches to a MAG at  502 . Next, the MAG may interface with the AAA server at  504 , for example to authenticate the MN, obtain an AAA profile for the MN, and/or obtain an AAA policy. The MAG may then send a PBU message to the LMA at  506 . Upon acceptance of the PBU message, the LMA may allocate an IPv4 HoA to the MN, create a binding cache entry (BCE), and begin to set up a tunnel to the MAG at  508 . The LMA may then send a PBA message to the MAG at  510 . Upon acceptance of the PBA message, the MAG may complete the setup of the tunnel and any other routing details at  512 . Step  514  indicates the establishment of the bi-directional tunnel between the LMA and the MAG. The MAG and the MN may then complete a DHCP message exchange at  516 , after which the MN may configure its IPv4 address at  518 . 
         [0034]    In IPv6 networks, once a MN enters a Proxy Mobile IPv6 domain the MAG may perform the mobility related signaling on behalf of the MN. As such, the MAG may determine when to optimize the route paths between the MNs and the CNs according to some policy. The policy may be stationary in user profiles or dynamically created or maintained, and may be pre-configured or obtained by the MAG from an AAA infrastructure or a policy function infrastructure. When the MAG makes a decision that a MN-CN combination needs route optimization, the MAG may initiate a PHoT procedure, which allows the CN to verify the reachability of the MN&#39;s HoA using IPv4 signaling and/or without assistance from the MN. The CNs may also need to verify the reachability of CoA. In such a case, a PCoT init (PCoTI) message may be piggybacked onto a PBU message that is sent by the MAG on behalf of the MN to register with the CN. 
         [0035]      FIG. 4  illustrates an embodiment of a PHoT procedure  600 , which may be used to validate the MN&#39;s HoA using IPv4 signaling. The PHoT procedure  600  differs from previous Home Test (HoT) procedures in that the MAG, not the MN, is the initiator and recipient of the signaling. As such, the MAG may imitate the MN&#39;s HoT signaling. The PHoT procedure  600  may begin when the MAG sends a PHoTI message to the LMA at  602 , for example using the tunnel between the MAG and the LMA. The PHoTI message may comprise two IPv4 headers. The first IPv4 header may comprise the CN&#39;s IPv4 address as the destination address and the MN&#39;s IPv4 HoA as the source address. For example and with reference to  FIG. 2 , if MN  1  is the MN and MN  3  is the CN, then the destination address would be IPv4-MN-HoA3 and the source address would be IPv4-MN-HoA1. The second IPv4 header may comprise the LMA&#39;s IPv4 address as the destination address and the MAG&#39;s egress interface IPv4 address as the source address. For example and again referring to  FIG. 2 , if MAG  1  is the MN&#39;s MAG and LMA  2  is the LMA, then the destination address would be IPv4-LMAA2 and the source address would be IPv4-Proxy-CoA1. Upon receipt of the PHoTI message, the LMA may remove the second header from the PHOTI message, and then send the PHoTI message to the CN at  604 . The CN responds by sending a PHoT message to the LMA at  606 . Specifically, the PHoT message may be sent to the MN&#39;s HoA as an IPv4 packet, and as such the CN may add an IPv4 header to the PHoT message prior to sending it. The LMA forwards the PHoT message to the MAG at  608 , where it is processed rather than being forwarded to the MN. In an embodiment, the PHoT message may comprise the permanent home keygen token. A keygen token may be a number supplied by the CN that enables the MN to compute the necessary binding management key (Kbm) for authorizing a BU. A home keygen token may be a keygen token sent by the CN in a PHoT message, and may be either temporary or permanent. Similarly, a care-of keygen token may be a keygen token sent by the CN in a CoT message, and may be either temporary or permanent. 
         [0036]      FIG. 5  illustrates an embodiment of a PCoT procedure  700 , which may be used to validate the MN&#39;s CoA using IPv4 signaling. The PCoT procedure  700  differs from previous Care-of Test (CoT) procedures in that the MAG, not the MN, is the initiator and recipient of the signaling. As such, the MAG may imitate the MN&#39;s CoT signaling, which may be piggybacked onto the PBU signaling. For example, the PHoT procedure  700  may begin when the MAG sends an early PBU message to the CN at  702 . The early PBU may not comprise the care-of keygen token described above, but may comprise a CoT init (CoTI) option, a HoA option, the Cryptographically Generated Address (CGA) parameters, and/or a signature option. The MAG may calculate the CGA parameters and signature option using the MN&#39;s HoA. For IPv4 MNs, the HoA may be a 128-bit value that may comprise the home network prefix (HNP) assigned by LMA as the leftmost 64 bits (e.g. the subnet prefix) and the interface identifier as the rightmost 64 bits. The interface identifier bits can be obtained randomly or from the MN&#39;s layer 2 address, e.g. the MN&#39;s Medium Access Control (MAC) address. The MAG may download the MN&#39;s public and private keys from the AAA server during access authentication, and use the MN&#39;s public and private keys to calculate the CGA parameters and signature option. 
         [0037]    The PCoT procedure  700  may be implemented prior to, simultaneous with, or subsequent to the PHoT procedure  600 . As such, the MAG may or may not have the permanent home keygen token when implementing the PCoT procedure  700 . If MAG only has the temporary home keygen token instead of the permanent home keygen token, the MAG may calculate the Binding Authorization Data option field of the early PBU message with the temporary home keygen token, and the care-of keygen token may be set to zero. If the MAG has the permanent home keygen token, the MAG may calculate the Binding Authorization Data option field of the early PBU message using the permanent home keygen token, and the care-of keygen token may be set to zero. In such a case, no CGA parameters and/or signature option may be required. 
         [0038]    The IPv4 MNs and CNs may calculate the parameters and security tokens (e.g. the home keygen and care-of keygen tokens) as if they were IPv6-enabled nodes. For example, the MNs and CNs may calculate the parameters and security tokens used in PMIPv6 route optimization procedure by using the HNP and interface identifiers for IPv6 nodes. In a specific embodiment, the tokens may be calculated as described in Arkko, et al., “Enhanced Route Optimization for Mobile IPv6,” IETF Network Working Group Request for Comments (RFC) 4866, May 2007 (hereinafter Arkko), and the CGA parameters may be calculated as described in Aura, “Cryptographically Generated Addresses,” IETF Network Working Group RFC 3972, March 2005 (hereinafter Aura), both of which are incorporated herein by reference in its entirety. 
         [0039]    In response to the early PBU message, the CN may send a Proxy Binding Acknowledgement (BAck) message to the MAG at  704 . The proxy BAck message may comprise the CoT option, which may comprise the care-of keygen token. A complete PBU message exchange may occur after the PBAck message is received. Specifically, the MAG may send a PBU message to the CN, where the PBU message may comprise the CGA parameters and the signature option. The CN may authenticate the PBU message using both the temporary home keygen token and the care-of keygen token generated during the PCoT procedure  700 . The CN may also validate the proxy BCE created by the early PBU exchange and then send a complete PBAck message to the MAG as a reply. The complete PBAck message may comprise the permanent home keygen token. In addition, the MAG may add the permanent home keygen token to the Binding Update (BU) list entry for the CN. 
         [0040]    Some or all of the PBU and PBAck messages may be IPv4 packets. Specifically, the PBU message may comprise an IPv4 header comprising the CN&#39;s IPv4 address as the destination address and the MN&#39;s IPv4 HoA as the source address. The PBU message may also comprise a payload comprising the PBU mobility options. Similarly, the PBA message may comprise an IPv4 header comprising the MN&#39;s IPv4 HoA as the destination address and the CN&#39;s IPv4 address as the source address. The PBA message may also comprise a payload comprising the PBA mobility options. 
         [0041]    When handoff occurs, the proxy CoA changes. As such, the CN must re-verify the reachability of HoA. As such, the new MAG may initiate the PHoT procedure. After the handover home keygen token is transferred from the previous MAG to the new MAG, the permanent home keygen token generated after the HoT may be used to authenticate the early PBU that originated from the new MAG. A PCoT procedure may also be implemented when MN moves into the new MAG. Such a process may be implemented concurrently with the PHoT procedure, if desired. In addition, the PCoT messages may be piggybacked onto the early PBU exchange to prevent handoff latency. As handoff occurs, the new MAG calculates the Binding Authorization Data option for early PBU based on the permanent home keygen token. The new MAG and CNs can resume communication, while PCoT procedure proceeds. 
         [0042]      FIG. 6  illustrates an embodiment of a handover procedure  800 . The handover procedure  800  may begin when the previous MAG suspects a handover of the MN may be necessary, for example via a layer 2 indication. Specifically, the previous MAG may proactively send a handover context message to the new MAG at  802 . The handover context message may comprise the HoA (e.g. IPv4-MN-HoA for an IPv4 MN), a HNP, at least one CN address (e.g. the addresses of the CNs that the MN is communication with using PMIPv6 route optimization), the home keygen token, the MN&#39;s CGA parameters, MN identifier (ID), interface ID, link layer address, and/or any other pertinent data. These parameters help the new MAG to pass the verification of HoA required by CN. Alternatively, the context can be reactively transferred, for example if the MN accesses the new MAG before the context is transferred. In reactive handover, when the new MAG detects the attachment of the MN, the new MAG requests the private key and other pertinent parameters from the previous MAG if the previous MAG is known. Otherwise, the new MAG obtains the private key during the authentication procedure. In any event, the previous MAG may deregister the BCE from the CN at  804  after the MN has left the previous MAG. For example, the previous MAG may send a PBU with a lifetime of about zero to the CN. The CN may respond with an optional PBAck message at  806 , if desired. 
         [0043]    The new MAG may then send an early PBU message to the CN at  808 . The early PBU message may comprise a CoTI option and a Binding Authorization Data option, which may be calculated using the home keygen token, and the care-of keygen token may be set to about zero. The early PBU may also comprise the CGA parameters, the signature option, the MN&#39;s public key, and the private key used to request the care-of keygen token. Upon receipt of the early PBU, the CN may verify (authenticate) it, for example using the home keygen token and the CGA parameters. If the early PBU passes the verification, the CN may respond with a PBAck message comprising a CoT option at  810 . In an embodiment, the PBAck message comprises a care-of keygen token that has been encrypted using the new MAG&#39;s public key. 
         [0044]    The new MAG may then renew the permanent home keygen token via a complete PBU message exchange. Specifically, the new MAG may send a complete PBU to the CN at  812 . The complete PBU message may comprise a Binding Authorization Data option that is calculated using both the care-of keygen token and the home keygen token. Such allows the CN to verify the CoA is reachable and authenticate the legitimacy of the MAG that is sending the message on behalf of MN. The complete PBU may also comprise the CGA parameters and the signature option for the new MAG to request the permanent home keygen token from the CN. The CGA provides a strong binding between its interface identifier and the CGA owner&#39;s public key. This enables other nodes to securely authenticate the CGA owner. 
         [0045]    In response to the PBU message, the CN may send a PBAck message comprising the home keygen token to the new MAG at  814 . The CN may authenticate the complete PBU message based on the CGA property of the MN&#39;s HoA. If the MAG only has the temporary home keygen token, then the MAG may use it to calculate the Binding Authorization Data option for the complete PBU message. Alternatively, if the MAG has the permanent home keygen token, the MAG may use it to calculate the Binding Authorization Data option. In such a case, the home nonce index may set to about zero. If the permanent home keygen token is required, the permanent home keygen token may be generated and encrypted using the MN&#39;s public key. The token may then be transferred from CN to the new proxy MN via the PBAck message. Thus, it may be apparent that after the new MAG obtains the care-of keygen token via the early PBU and PBAck messages described in  FIG. 5 , the BCE is generated in the CN but remains unverified. When the complete PBU message described in  FIG. 6  is received by the CN, the BCE can be verified. 
         [0046]    If a MAG provides mobility service for the CN, then the PMIPv6 Route Optimization protocol can be used for the CN, provided that the MAG intercepts and processes the route optimization extensions by analyzing the mobility header (MH) types and distinguishing Proxy Mobile IP signaling from normal data.  FIG. 7  illustrates an embodiment of a suitable route optimization procedure  900 . The route optimization procedure  900  may be implemented when the MN and the CN have different LMAs and different MAGs. The route optimization procedure  900  may begin when the MN&#39;s MAG sends a PHoTI message to the MN&#39;s LMA at  902 , for example using the MAG-LMA tunnel. The PHoTI message may be an IPv6 message, and as such may comprise an IPv6 header comprising the proxy CoA of the CN&#39;s MAG, e.g. the IPv6 CoA for the CN, as the destination address and the proxy CoA of the MN&#39;s MAG, e.g. the IPv6 CoA for the MN, as the source address. The PHoTI message may also comprise the CN&#39;s IPv4 HoA so that the CN&#39;s MAG knows which CN is intended to receive the PHoTI. If the MN&#39;s MAG and LMA are using IPv4, then the PHoTI message may further comprise an IPv4 header comprising the IPv4 address for the MN&#39;s LMA, e.g. the IPv4-LMAA, as the destination address and the IPv4 address of the egress interface of the MN&#39;s MAG, e.g. the IPv4-Proxy-CoA, as the source address. In such a case, the MN&#39;s LMA may remove the IPv4 header to expose the underlying IPv6 PHoTI message. The MN&#39;s LMA may then add an IPv6 header to the PHoTI message, wherein the IPv6 header comprises the IPv6 address for the egress interface of the CN&#39;s LMA. The MN&#39;s LMA can obtain the IPv6 address for the egress interface of the CN&#39;s LMA from the AAA server. The MN&#39;s LMA may then forward the PHoTI message to the CN&#39;s LMA at  904 . 
         [0047]    The CN&#39;s LMA may remove the outer IPv6 header and expose the original PHoTI message. The CN&#39;s LMA may also add an IPv4 header to the PHoTI message, where the IPv4 header comprises the CN&#39;s IPv4 Proxy CoA, e.g. the IPv4-Proxy-CoA, as the destination address and the IPv4 address of the CN&#39;s LMA, e.g. the IPv4-LMA, as the source address. The CN&#39;s LMA may send the PHoTI message to the CN&#39;s MAG at  906 , for example using the LMA-MAG tunnel. 
         [0048]    The CN&#39;s MAG may remove the IPv4 header and process the original PHoTI message. Specifically, the CN&#39;s MAG may not forward the packet to the CN because the CN&#39;s MAG may recognize the packet as a PHoTI message. Instead, the CN&#39;s MAG may extract the MN&#39;s HoA and CoA from the PHoTI message, for example from the IPv4 HoA and CoA fields. The CN&#39;s MAG may also create a BU List entry for the MN. In addition, the CN&#39;s MAG may send a PHoT message to the CN&#39;s LMA at  908 , for example using the LMA-MAG tunnel. The PHoT message may be an IPv6 packet, and may comprise the Proxy-CoA of MN&#39;s MAG as the destination address and the Proxy-CoA of CN&#39;s MAG as the source address. The PHoT message may also comprise the CN&#39;s CoA and the MN&#39;s IPv4 HoA, for example in the CoA and IPv4 HoA fields, respectively. The CN&#39;s LMA may forward the PHoT message to the MN&#39;s LMA at  910 , and the MN&#39;s LMA may forward the PHoT message to the MN&#39;s MAG at  912 , for example using the LMA-MAG tunnel. The MN&#39;s MAG may extract the CN&#39;s CoA from the PHoT message and add such to the CN&#39;s BCE. 
         [0049]    The MN&#39;s MAG and the CN&#39;s MAG may then implement the PBU messaging described above. Specifically, the MN&#39;s MAG may start the CoT signaling by sending an early PBU message directly to the CN&#39;s MAG at  914 , and the CN&#39;s MAG may respond with an early PBAck message sent directly to the MN&#39;s MAG at  916 . The MN&#39;s MAG may then send a complete PBU message directly to the CN&#39;s MAG at  918 , and the CN&#39;s MAG may respond with a complete PBAck message sent directly to the MN&#39;s MAG at  920 . In some embodiments, the CoT signaling in  FIG. 7  may not be implemented simultaneously with the HoT signaling due to the address exchanges in the PHoTI and PHoT messages. 
         [0050]    When both the MN and CN are served by MAGs, the route optimization packets may be IPv6 packets even if the MN, CN, or both only support IPv4. Such may be possible when the two MAGs support IPv6 because the route optimization packets do not reach the MN or CN. 
         [0051]    When the MN and LMA have separate LMAs and MAGs and handover is required, the context may be transferred between the MAGs, as described herein. In such a case, the context may comprise the MN&#39;s HoA (e.g. the IPv4-MN-HoA for IPv4 nodes), at least one CN address (e.g. the IPv4 Addresses of all the CNs with which the MN is communicating using route optimization), the home keygen token, and the MN&#39;s CGA parameters, such as the MN&#39;s private key, HNP, home keygen token, MN-ID, interface ID and/or link layer address. 
         [0052]      FIG. 8  is an illustration of an embodiment of the PHoT message  1000 . The PHoT message  1000  may comprise a home nonce index  1002 , a home init cookie  1004 , a home keygen token  1006 , a CoA  1008 , an IPv4 HoA  1010 , and any mobility options  1012 , which are arranged as shown in  FIG. 8 . The home nonce index  1002  may tell the CN which nonce value to use when producing the home keygen token  1006 , and may be the first about 16 bits of the PHoT message  1000 . The home init cookie  1004  may be a random value used to match the PHoTI message with the corresponding PHoT message, and may be the subsequent about 64 bits of the PHoT message  1000 . The home keygen token  1006  may be a token used to authenticate the PBU, and may be the subsequent about 64 bits of the PHoT message  1000 . The CoA  1008  may be the CoA assigned to the CN by the MAG, and may be the subsequent about 128 bits of the PHoT message  1000 . The IPv4 HoA  1010  may be the IPv4 HoA of the MN, and may be the subsequent about 32 bits of the PHoT message  1000 . The mobility options  1012  are optional, may be any of the mobility options described in Johnson, et al., “Mobility Support in IPv6,” IETF Network Working Group RFC 3775, June 2004 (hereinafter Johnson), which is incorporated herein by reference in its entirety, or any other mobility options, and may be the subsequent (32*n) bits of the PHoT message  1000 , where n is a positive integer. 
         [0053]      FIG. 9  is an illustration of an embodiment of the PHoTI message  1100 . The PHoTI message  1100  may comprise a reserved field  1102 , a home init cookie  1104 , a CoA  1106 , an IPv4 HoA  1108 , and any mobility options  1110  arranged as shown in  FIG. 9 . The reserved field  1102  may be reserved for other purposes, and may be the first about 16 bits of the PHoTI message  1100 . The home init cookie  1104  may be a random value used to match the PHoTI message with the corresponding PHoT message, and may be the subsequent about 64 bits of the PHoTI message  1100 . The CoA  1106  may be the CoA assigned to the MN by the MAG, and may be the subsequent about 128 bits of the PHoTI message  1100 . The IPv4 HoA  1108  may be the IPv4 HoA of the MN, and may be the subsequent about 32 bits of the PHoTI message  1100 . The mobility options  1110  are optional, may be any of the mobility options described in Johnson or any other mobility options, and may be the subsequent (32*n) bits of the PHoTI message  1100 , where n is a positive integer. 
         [0054]    The network components described above may be implemented on any general-purpose network component, such as a computer or network component with sufficient processing power, memory resources, and network throughput capability to handle the necessary workload placed upon it.  FIG. 10  illustrates a typical, general-purpose network component  1200  suitable for implementing one or more embodiments of the components disclosed herein. The network component  1200  includes a processor  1202  (which may be referred to as a central processor unit or CPU) that is in communication with memory devices including secondary storage  1204 , read only memory (ROM)  1206 , random access memory (RAM)  1208 , input/output (I/O) devices  1210 , and network connectivity devices  1212 . The processor  1202  may be implemented as one or more CPU chips, or may be part of one or more application specific integrated circuits (ASICs). 
         [0055]    The secondary storage  1204  is typically comprised of one or more disk drives or tape drives and is used for non-volatile storage of data and as an over-flow data storage device if RAM  1208  is not large enough to hold all working data. Secondary storage  1204  may be used to store programs that are loaded into RAM  1208  when such programs are selected for execution. The ROM  1206  is used to store instructions and perhaps data that are read during program execution. ROM  1206  is a non-volatile memory device that typically has a small memory capacity relative to the larger memory capacity of secondary storage  1204 . The RAM  1208  is used to store volatile data and perhaps to store instructions. Access to both ROM  1206  and RAM  1208  is typically faster than to secondary storage  1204 . 
         [0056]    At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R l , and an upper limit, R u , is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R l +k*(R u −R l ), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers, as defined in the above, is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure. The discussion of a reference in the disclosure is not an admission that it is prior art, especially any reference that has a publication date after the priority date of this application. The disclosure of all patents, patent applications, and publications cited in the disclosure are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to the disclosure. 
         [0057]    While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented. 
         [0058]    In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.