Abstract:
The invention consists of a new registration and authentication protocol for between a Mobile Node and a Home Agent. The new protocol uses a novel messaging sequence to request registration, authentication and authorization of the Mobile Node when it is located on a foreign network, and the novel protocol will avoid some of the standard registration and authentication protocol messages in order to eliminate the problems associated with re-transmission errors.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/205,499, filed Mar. 12, 2014, which is a continuation of U.S. patent application Ser. No. 12/671,985, filed Feb. 3, 2010, now U.S. Pat. No. 8,713,637, which is a National Stage Entry of PCT/US2008/009646, filed Aug. 12, 2008, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 60/955,533 filed on Aug. 13, 2007 and 60/956,550 filed on Aug. 17, 2007, each of which are herein incorporated by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     A system and method for a mobile IP-based system, including an IP-based mobile communication system having a home network, foreign network and a mobile node. 
     BACKGROUND OF THE INVENTION 
     IP-based mobile system includes at least one Mobile Node in a wireless communication system. The term “Mobile Node” includes a mobile communication unit, and, in addition to the Mobile Node, the communication system has a home network and a foreign network. The Mobile Node may change its point of attachment to the Internet through these other networks, but the Mobile Node will always be associated with a single home network for IP addressing purposes. The home network has a Home Agent and the foreign network has a Foreign Agent—both of which control the routing of information packets into and out of their network. 
     The Mobile Node, Home Agent and Foreign Agent may be called other names depending on the nomenclature used on any particular network configuration or communication system. For instance, a “Mobile Node” encompasses PC&#39;s having cabled (e.g., telephone line (“twisted pair”), Ethernet cable, optical cable, and so on) connectivity to the wireless network, as well as wireless connectivity directly to the cellular network, as can be experienced by various makes and models of mobile terminals (“cell phones”) having various features and functionality, such as Internet access, e-mail, messaging services, and the like. 
     And, a home agent may be referred to as a Home Agent, Home Mobility Manager, Home Location Register, and a foreign agent may be referred to as a Foreign Agent, Serving Mobility Manager, Visited Location Register, and Visiting Serving Entity. The terms Mobile Node, Home Agent and Foreign Agent are not meant to be restrictively defined, but could include other mobile communication units or supervisory routing devices located on the home or foreign networks. Foreign networks can also be called serving networks. 
     Registering the Mobile Node 
     Foreign Agents and Home Agents periodically broadcast an agent advertisement to all nodes on the local network associated with that agent. An agent advertisement is a message from the agent on a network that may be issued under the Mobile IP protocol (RFC 2002) or any other type of communications protocol. This advertisement should include information that is required to uniquely identify a mobility agent (e.g. a Home Agent, a Foreign Agent, etc.) to a mobile node. Mobile Nodes examine the agent advertisement and determine whether they are connected to the home network or a foreign network. 
     If the Mobile Node is located on its home network, information packets will be routed to the Mobile Node according to the standard addressing and routing scheme. If the Mobile Node is visiting a foreign network, however, the Mobile Node obtains appropriate information from the agent advertisement, and transmits a registration request message to its Home Agent through the Foreign Agent. The registration request message will include a care-of address for the Mobile Node. A registration reply message may be sent to the Mobile Node by the Home Agent to confirm that the registration process has been successfully completed. 
     The Mobile Node keeps the Home Agent informed as to its current location by registering a “care-of address” with the Home Agent. The registered care-of address identifies the foreign network where the Mobile Node is located, and the Home Agent uses this registered care-of address to forward information packets to the foreign network for subsequent transfer onto the Mobile Node. If the Home Agent receives an information packet addressed to the Mobile Node while the Mobile Node is located on a foreign network, the Home Agent will transmit the information packet to the Mobile Node&#39;s current location on the foreign network using the applicable care-of address. 
     Authentication, Authorization and Accounting (“AAA”) 
     In an IP-based mobile communications system, when a mobile node travels outside its home administrative domain, the mobile node may need to communicate through multiple domains in order to maintain network connectivity with its home network. While connected to a foreign network controlled by another administrative domain, network servers must authenticate, authorize and collect accounting information for services rendered to the mobile node. This authentication, authorization, and accounting activity is called “AAA”, and AAA servers on the home and foreign network perform the AAA activities for each network. 
     Authentication is the process of proving one&#39;s claimed identity, and security systems on a mobile IP network will often require authentication of the system user&#39;s identity before authorizing a requested activity. The AAA server authenticates the identity of an authorized user and authorizes the mobile node&#39;s requested activity. Additionally, the AAA server will also provide the accounting function including tracking usage and charges for use of transmissions links between administrative domains. 
     Another function for the AAA server is to support secured transmission of information packets by storing and allocating security associations. Security associations refer to those encryption protocols, nonces, and keys required to specify and support encrypting an information packet transmission between two nodes in a secure format. The security associations are a collection of security contexts existing between the nodes that can be applied to the information packets exchanged between them. Each context indicates an authentication algorithm and mode, a shared or secret key or appropriate public/private key pair, and a style of replay protection. 
     The current registration and authentication protocols are not efficient because they require the re-transmission of registration and authentication request messages in certain time-out situations. The re-transmission of the registration and authentication request messages may be unnecessary in these situations, and such a re-transmission of these messages may result in multiple request messages being transmitted onto the network when only one request message was needed. 
     SUMMARY OF THE INVENTION 
     The invention consists of a new registration and authentication protocol for between a Mobile Node and a Home Agent. The new protocol will use a novel messaging sequence to request registration, authentication and authorization of the Mobile Node when it is located on a foreign network, and the novel protocol will avoid some of the standard registration and authentication protocol messages in order to eliminate the problems associated with re-transmission errors. 
     The initial sequence of messaging in the protocol will be conducted between the Mobile Node, Foreign Agent, foreign AAA server and home network AAA server, before a registration request is allowed to be sent to the Home Agent. The initial registration request message is transmitted to the Home Agent only after the successful completion of the initial message sequence between the other components on the network. The home agent will exchange messages with its home agent AAA server to confirm authentication and authorization on the home network, and if successful, the home agent will respond to the registration request with a response that is sent back to the Mobile Node on the foreign network. The invention can be implemented using a new protocol application or using modified messages from prior registration applications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the invention will become more readily understood from the following detailed description and appended claims when read in conjunction with the accompanying drawings in which like numerals represent like elements and in which: 
         FIG. 1  is a mobile IP-based communication system as used in the present invention; 
         FIG. 2  is a message sequence for registration and authentication protocol used in the prior art. 
         FIG. 3-4  are message sequences for the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , the overall architecture of the IP-based mobile system is shown with a Mobile Node  64 , a home network  10  and a foreign network  40 . As shown in  FIG. 1 , the home network  10  and the foreign network  40  are coupled to the Internet represented by the cloud  35 . The home network  10  has a central buss line  20  coupled to the Home Agent  28  via communication link  24 . The buss line  20  is coupled to the AAA server  17  via communication link  22 . The home network  10  is coupled to the Internet  35  via communication link  30 . A communications link is any connection between two or more nodes on a network or users on networks or administrative domains. 
     The foreign network  40  has a central buss line  50  coupled to the foreign agent  58  via communication link  54 . The buss line  50  is coupled to the AAA foreign network server  47  via communication link  52 . The foreign network  40  is coupled to the Internet  35  via communication link  37 . Mobile Node  64  is shown electronically coupled to the foreign network  40  via the wireless communication link  66  of transceiver  60 . Transceiver  60  is coupled to the foreign network  40  via communication link  62 . The Mobile Node  64  can communicate with any transceiver or Access Network coupled to the foreign network  40 . 
     The terms Home Agent and Foreign Agent may be as defined in the Mobile IP Protocol (RFC 2002), but these agents are not restricted to a single protocol or system. In fact, the term Home Agent, as used in this application, can refer to a Home Mobility Manager, Home Location Register, Home Serving Entity, or any other agent at a home network  10  having the responsibility to manage mobility-related functionality for a Mobile Node  64 . Likewise, the term Foreign Agent, as used in this application, can refer to a Serving Mobility Manager, Visited Location Register, Visiting Serving Entity, or any other agent on a foreign network  40  having the responsibility to manage mobility-related functionality for a Mobile Node  64 . 
     In the mobile IP communications system shown in  FIG. 1 , the Mobile Node  64  is identified by a permanent IP address. While the Mobile Node  64  is coupled to its home network  10 , the Mobile Node  64  receives information packets like any other fixed node on the home network  10 . When mobile, the Mobile Node  64  can also locate itself on foreign network  40 . When located on foreign network  40 , the home network  10  sends data communications to the Mobile Node  64  by “tunneling” the communications to the foreign network  40 . 
     The Mobile Node  64  keeps the Home Agent  28  informed of its current location, or foreign network association, by registering a care-of address with the Home Agent  28 . Essentially, the care-of address represents the foreign network  40  where the Mobile Node  64  is currently located. If the Home Agent  28  receives an information packet addressed to the Mobile Node  64  while the Mobile Node  64  is located on a foreign network  40 , the Home Agent  28  will “tunnel” the information packet to foreign network  40  for subsequent transmission to Mobile Node  64 . 
     The Foreign Agent  58  participates in informing the Home Agent  28  of the Mobile Node&#39;s  64  current care-of address. The Foreign Agent  58  also receives information packets for the Mobile Node  64  after the information packets have been forwarded to the Foreign Agent  58  by the Home Agent  28 . Moreover, the Foreign Agent  58  serves as a default router for out-going information packets generated by the Mobile Node  64  while connected to the foreign network  40 . 
     The Mobile Node  64  participates in informing the Home Agent  28  of its current care-of address. When the Mobile Node  64  is visiting a foreign network  40 , the Mobile Node  64  obtains appropriate information regarding the address of the foreign network  40  and/or the Foreign Agent  58  from an agent advertisement. After obtaining this information, the Mobile Node  64  transmits the registration request to the Foreign Agent  58 , which prepares the registration request message for forwarding to the Home Agent  28 . 
     Mobile IP protocols require that the mobile node register the care-of address with the Home Agent  28  on the home network  10  after movement to a new foreign network  40 . As part of the registration process, the Mobile Node  64  issues a registration request in response to power-up on the foreign network  40  or receipt of an agent advertisement. A registration request message can be sent to the home network  10  that includes a care-of address for the Mobile Node  64 . A registration reply is issued by the home network  10  to acknowledge receipt of the registration request, confirm receipt of the care-of address for the Mobile Node  64 , and indicate completion of the registration process. 
     The care-of address identifies the foreign network  40  where the Mobile Node  64  is located, and the Home Agent  28  uses this care-of address to tunnel information packets to the foreign network  40  for subsequent transfer to the Mobile Node  64 . After registration is completed, the Home Agent  28  receives this communication and “tunnels” the message to the Mobile Node  64  on the foreign network  40 . The Foreign Agent  58  accepts the re-directed communication and delivers the information packet to the Mobile Node  64  through the transceiver  60 . In this manner, the information packets addressed to the Mobile Node  64  at its usual address on the home network  10  is re-directed or forwarded to the Mobile Node  64  on the foreign network  40 . The Foreign Agent  58  may also serve as a router for “outbound” information packets generated by the Mobile Node  64  while connected to the foreign network  40  depending on the delivery style chosen. 
       FIG. 2  shows the message sequence using a known protocol (RF 4004) for the registration and authentication of the Mobile Node  64  on a foreign network. In step  210 , the registration request RRQ is transmitted from the Mobile Node  64  to the Foreign Agent  58 . The registration request RRQ message is received and a new registration message AMR is formed by the Foreign Agent  58 , and, at step  220 , that message is transmitted from the Foreign Agent  58  to the AAAF server  47  on the foreign network. The AMR message is transmitted from the AAAF server  47  to the AAAH server  17  at step  230 , where a new registration request message HAR is generated and transmitted from the AAAH  17  to the Home Agent  28  at step  240 . 
     The Home Agent  28  analyzes this HAR message before responding to that message with a registration response message HAA, which is transmitted back to the AAAH server  17  at step  250 . The AAAH server  17  forms a new registration response message AMA at the AAAH server  17  and transmits that new registration response message AMA to the AAAF server  47  at step  260 . The AAAF server  47  forwards the registration response message AMA to the Foreign Agent  58  at step  270 , where a new registration response message RRP is formed. The Foreign Agent  58  transmits the new registration response message RRP to the Mobile Node  64  at step  280 . 
     This known protocol uses three different registration messages and three different registration response messages, all transmitted sequentially in eight steps between five components. Delays may occur at any stage in the protocol sequence, and if the registration request or registration response messages are delayed to a substantial degree, the Mobile Node  64  may re-issue its registration request under the assumption that the prior registration request was lost or failed transmission. This re-issue and re-transmission of the registration request may be unnecessary, and could cloud the networks with registration messages that should not otherwise have been issued and transmitted. The present invention eliminates the possibility for such problems by simplifying the request and response message sequence for registration and authentication. 
       FIG. 3  shows the message sequence using the present invention for the registration and authentication of the Mobile Node  64  on a foreign network. In step  310 , the registration request RRQ is transmitted from the Mobile Node  64  to the Foreign Agent  58 . The registration request RRQ message is received and a new registration message AMR is formed by the Foreign Agent  58 , and the AMR message is transmitted from the Foreign Agent  58  to the AAAF server  47  on the foreign network at step  320 . The AMR message is transmitted from the AAAF server  47  to the AAAH server  17  at step  330 . 
     Instead of allowing the request messages to be communicated directly to the Home Agent, the initial message sequence first requires the AAAH  17  to analyze the request message AMR and then prepare a response message AMA that is transmitted from the AAAH  17  to AAAF  47  at step  340 . The AAAF  47  transmits the response message AMA to the Foreign Agent  58  at step  350 . The initial message sequence is finalized with the receipt of that AMA message at step  350 . 
     After confirmation that the registration request has been approved and authenticated by the AAAH  17  through the AMA response message received by the Foreign Agent, the Foreign Agent forwards the registration request RRQ message initially received from the Mobile Node  64  directly to the Home Agent  28  at step  360 . The Home Agent transmits an AMR request message to the AAAH  17  at step  370  based on the receipt of the request message RRQ, and the AAAH  17  responds to the AMR request message with the transmission of a registration response AMA message at step  380 . With the receipt of the AMA message at step  380 , the Home Agent  28  confirms the ability to register the Mobile Node  64 . 
     After authentication and registration at the Home Agent  28 , the Home Agent  28  transmits a registration response message RRP to the Foreign Agent  58  at step  390 , and the Foreign Agent  58  forwards this registration response message to the Mobile Node  64  at step  395 . With the receipt of the registration response message RRP by the Mobile Node  64 , the registration and authentication protocol is completed. This protocol uses a reduced number of different message formats (four formats) compared to the prior art protocol, which assists in the reduction in the possibility that delays would occur and these delays would initiate re-transmissions of the registration request message. 
       FIG. 4  shows the message sequence using the present invention for the registration and authentication of the Mobile Node  64  on a foreign network. In step  405 , the initial message sequence is designated by the EAP Authentication communicated between the Mobile Node  64 , Foreign Agent  58 , LAAA  147  (corresponds to AAAF  47 ), and the HAAA  17 . This EAP Authentication  405  allows the Mobile Node  64  to be authenticated by the HAAA  17  through an initial sequence of messages. Instead of allowing the request messages to be communicated directly to the Home Agent, the initial message sequence first requires the AAAH  17  to analyze the request message and confirm authentication back to components on the foreign network  40 . 
     After step  405 , the registration request RRQ is transmitted from the Mobile Node  64  to the Foreign Agent  58  at step  410 . After confirmation that the registration request has been approved and authenticated by the AAAH  17  through the EAP Authentication  405 , the Foreign Agent forwards the registration request RRQ message initially received from the Mobile Node  64  directly to the Home Agent  28  at step  420 . The Home Agent transmits an AMR request message to the AAAH  17  at step  430  based on the receipt of the request message RRQ, and the AAAH  17  responds to the AMR request message with the transmission of a registration response AMA message at step  440 . With the receipt of the AMA message at step  440 , the Home Agent  28  confirms the ability to register the Mobile Node  64 . 
     After authentication and registration at the Home Agent  28 , the Home Agent  28  transmits a registration response message RRP to the Foreign Agent  58  at step  450 , and the Foreign Agent  58  forwards this registration response message to the Mobile Node  64  at step  460 . With the receipt of the registration response message RRP by the Mobile Node  64 , the registration and authentication protocol is completed. This protocol uses a reduced number of different message formats (four formats) compared to the prior art protocol, which assists in the reduction in the possibility that delays would occur and these delays would initiate re-transmissions of the registration request message.