Patent Application
20050207429
1. Field of the Invention
The present invention generally relates to a home agent duplication method and a home agent duplication apparatus, and more particularly, to a home agent duplication method and a home agent duplication apparatus for improving reliability of a home agent.
2. Description of the Related Art
In recent mobile communication network technology research and development, research and development are conducted on mobile IP (Internet Protocol) technology of a fourth generation network for achieving mobility throughout the entire IP network. In realizing such mobile IP, a home agent, which manages IP addresses assigned to destinations of mobile terminals (MN) and transfers packets addressed to the IP addresses, plays a vital role. Accordingly, in order to maintain and improve reliability and convenience of the mobile IP, enhancement in the reliability of the home agent is necessary.
The home agents 13, 14 have an IP in IP function, in which the home agents 13, 14 encapsulate a binding cache (BC), which holds a destination address (care of address: CoA) of the mobile terminal 10 in correspondence with a home address (HoA) of the mobile terminal 10, and transferred IP packets addressed to the home address of the mobile terminal 10, and transfer the encapsulated data.
Next, an operation of the mobile IP is described.
Accordingly, with the above-described conventional mobile IP technology, an available home agent (in this example, home agent 13) can be notified to the mobile terminal 10 by allowing one of the home agents 13, or 14 situated at the home link 11 to respond to the home agent search packet delivered from the mobile terminal 10.
That is, the home link 11 side is able to select the available home agent 13 and notify the selected available home agent 13 to the mobile terminal 10, to thereby allow the mobile terminal to select the most suitable home agent 13 according to the state of the home link 11.
The conventional technology is a technology for selecting an available home agent, and serves to improve reliability by dispersing the load of the home agent. However, in a case where a disorder occurs in the home agent, location information of the mobile terminal becomes lost, and data transfer is stopped.
Cluster technology may be employed for solving this problem, in which a plurality of home agents 14a, 14b logically posing to be a single home agent 14 are used. However, the employment of this technology has a problem of requiring expensive hardware and software.
Meanwhile, in an example shown in Japanese Laid-Open Patent Application No.10-512122, hardware and data redundancy are provided to a database including a location register maintained in a mobile switching center of a mobile telephone system.
Further, in an example shown in Japanese Laid-Open Patent Application No.2000-152315, a common line signal technique is employed for enhancing reliability of a health checkup, and an example shown in Japanese Laid-Open Patent Application No. 11-68780 serves to a solve problem(s) caused when applying a mobile IP technology to an ATM network.
However, with the conventional mobile IP technology, data transfer to a mobile terminal is obstructed whenever there is a disorder in the home agent since location information managed by the home agent is erased from the network.
Although cluster technology, which physically uses plural apparatuses as home agents, may be applied in solving the problem, the employment of this technology requires expensive hardware and software, to thereby result to an increase the cost of plant and equipment investment for companies and communication businesses.
It is a general object of the present invention to provide a home agent duplication method and a home agent duplication apparatus that substantially obviates one or more of the problems caused by the limitations and disadvantages of the related art.
Features and advantages of the present invention will be set forth in the description which follows, and in part will become apparent from the description and the accompanying drawings, or may be learned by practice of the invention according to the teachings provided in the description. Objects as well as other features and advantages of the present invention will be realized and attained by a home agent duplication method and a home agent duplication apparatus particularly pointed out in the specification in such full, clear, concise, and exact terms as to enable a person having ordinary skill in the art to practice the invention.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a method for duplicating a home agent including an address correspondence maintaining unit for maintaining a destination address of a mobile terminal in correspondence with a home address of the mobile terminal, and a transferring unit for encapsulating an IP packet addressed to the home address of the mobile terminal and transferring the encapsulated IP packet to the destination address of the mobile terminal, the method including the steps of: setting a home agent address, which is the same as a home agent address of an operation system home agent, to a standby system home agent; and receiving a location registration request, which is sent from the mobile terminal and addressed to the operation system home agent, with the standby system home agent.
The home agent duplication method according to an embodiment of the present invention may further include the steps of: generating a corresponding relation between the destination address of the mobile terminal and the home address of the mobile terminal with the standby system home agent, the generated corresponding relation having the same content as the corresponding relation of the operation system home agent; maintaining the generated corresponding relation in an address correspondence maintaining unit of the standby system home agent; and returning no response from the standby system home agent with respect to the location registration request sent from the mobile terminal.
The home agent duplication method according to the present invention may further include a step of: periodically transmitting location registration requests registered in an address correspondence maintaining unit of the operation system home agent to the standby system home agent.
The home agent duplication method according to the present invention may further include the steps of: monitoring an operation state of the operation system home agent; and switching a transmission destination from the operation system home agent to the standby system home agent when a disorder of the operation system home agent is detected from monitoring the operation state of the operation system home agent, so that packets addressed to the home address and the operation system home agent are transferred to the standby system home agent.
The home agent duplication method according to the present invention may further include the steps of: transmitting location registration requests registered in the address correspondence maintaining unit of the standby system home agent to the operation system home agent when a recovery of the disorder of the operation system home agent is detected from monitoring the operation state of the operation system home agent; generating another corresponding relation between the destination address of the mobile terminal and the home address of the mobile terminal with the operation system home agent, the other generated corresponding relation having the same content as the corresponding relation of the standby system home agent; maintaining the generated corresponding relation in the address correspondence maintaining unit of the standby system home agent; and returning no response from the operation system home agent with respect to the location registration request sent from the mobile terminal.
The home agent duplication method according to the present invention may further include a step of: switching a transmission destination from the standby system home agent to the operation system home agent when completing the transmission of the location registration requests from the standby system home agent to the operation system home agent after detecting the recovery of the disorder of the operation system home agent, so that packets addressed to the home address and the operation system home agent are transferred to the operation system home agent.
The home agent duplication method according to the present invention may further include a step of: setting another home agent address, which is the same as another home agent address of another operation system home agent, to the standby system home agent.
Furthermore, the present invention provides a standby system home agent used for a method for duplicating a home agent including an address correspondence maintaining unit for maintaining a destination address of a mobile terminal in correspondence with a home address of the mobile terminal, and a transferring unit for encapsulating an IP packet addressed to the home address of the mobile terminal and transferring the encapsulated IP packet to the destination address of the mobile terminal, the standby system home agent including: a home agent address maintaining unit for maintaining a home agent address which is the same as a home agent of an operation system agent, wherein the standby system home agent receives a location registration request which is sent from the mobile terminal and addressed to the operation system home agent.
The standby system home agent according to an embodiment of the present invention may further include a no response unit for generating a corresponding relation between the destination address of the mobile terminal and the home address of the mobile terminal, the generated corresponding relation having the same content as the corresponding relation of the operation system home agent, for maintaining the generated corresponding relation in an address correspondence maintaining unit of the standby system home agent, and for returning no response with respect to the location registration request sent from the mobile terminal.
The standby system home agent according to an embodiment of the present invention may further include a switching unit for switching a transmission destination from the operation system home agent to the standby system home agent when a disorder of the operation system home agent is detected from monitoring an operation state of the operation system home agent, so that packets addressed to the home address and the operation system home agent are transferred to the standby system home agent.
The standby system home agent according to an embodiment of the present invention may further include a transmitting unit for transmitting location registration requests registered in the address correspondence maintaining unit of the standby system home agent to the operation system home agent when a recovery of the disorder of the operation system home agent is detected from monitoring the operation state of the operation system home agent.
In the standby system home agent according to an embodiment of the present invention, the switching unit switches a transmission destination from the standby system home agent to the operation system home agent when completing the transmission of the location registration requests from the standby system home agent to the operation system home agent after detecting the recovery of the disorder of the operation system home agent, so that packets addressed to the home address and the operation system home agent are transferred to the operation system home agent.
Furthermore, the present invention provides an operation system home agent used for a method for duplicating a home agent including an address correspondence maintaining unit for maintaining a destination address of a mobile terminal in correspondence with a home address of the mobile terminal, and a transferring unit for encapsulating an IP packet addressed to the home address of the mobile terminal and transferring the encapsulated IP packet to the destination address of the mobile terminal, the operation system home agent including: a transmitting unit for periodically transmitting location registration requests registered in an address correspondence maintaining unit of the operation system home agent to the standby system home agent.
The operation system home agent according to an embodiment of the present invention may further include a no response unit for receiving location registration requests registered in the address correspondence maintaining unit of the standby system home agent from the standby system home agent, for generating a corresponding relation between the destination address of the mobile terminal and the home address of the mobile terminal, the generated corresponding relation having the same content as the corresponding relation of the standby system home agent, for maintaining the generated corresponding relation in the address correspondence maintaining unit of the standby system home agent, and for returning no response with respect to the location registration request sent from the mobile terminal.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.
In the following, embodiments of the present invention will be described with reference to the accompanying drawings.
The home agent 231˜23n, 24 have an IP in IP function, in which the home agents 231˜23w, 24 encapsulate a binding cache (BC), which holds a move destination address (care of address: CoA) of the mobile terminal 20 in correspondence with a home address (HoA) of the mobile terminal 20, and transferred IP packets addressed to the home address of the mobile terminal 20, and transfer the encapsulated data to the care of address (CoA).
The standby system home agent 100 shown in
The packet control part 31 includes functions of: receiving packets from other transmission apparatuses connected to the home link 21 (e.g. router 22); determining the types of received packets and allocating the received packets; transferring the allocated received packets to upper level control parts (e.g. the ARP control part 32, the MIP control part 33, and the disorder monitor control part 34); accepting packet transmission requests from the upper level control parts; and transmitting packets to other transmission apparatuses connected to the network.
Meanwhile, when the packet control part 31 accepts a packet transmission request from the upper level control part(s), the packet control part 31 transmits the received packet to the other transmission apparatuses, such as, mobile terminal 20, router 22 (Step S20).
The ARP control part 32 includes an ARP (Address Resolution Protocol) defined in RFC 826 function, and an extended address resolution function (an extended address resolution function part) for determining whether response transmission is necessary. The ARP control part 32 also includes a GARP (Gratuitous Address Resolution Protocol) function based on RFC 2002 for notifying the correspondence between the IP address and the MAC address to the other surrounding nodes, and a switching control function (switching control function part), so that a substitute packet receiving function can be set and/or released according to the results of the disorder monitoring.
In a case where the requested address applies to that of the apparatus itself and where the apparatus itself is a standby system (i.e. not an operation system), the extended address resolution function part does not generate and send an address conversion response since the standby system does not need to receive packets addressed to the operation system home agent(s). However, in a case where the extended address resolution function part determines that there is a disorder in the operation system (YES in Step 25), the extended address resolution function part generates the address conversion response (Step S23), and sends the response to the packet control part 31 (Step S24) for allowing the standby system home agent to receive packets addressed to the operation system home agent.
In a case where the requested address is not that of the apparatus itself (NO in Step S21), the requested address is transferred to the MIP control part 33 (Step S26) for conducting a binding cache recovery confirmation.
Meanwhile, in a case where the switching request is not a switching request due to disorder, the system switching control function part determines whether the switching request is due to disorder recovery (Step S34). If the request is determined as a request due to disorder recovery (as a notification of receipt from the MIP control part 34) (YES in Step S34), the system switching control function part generates a GARP request for enabling the recovered system to accept internets packets being delivered to its own apparatus (own home agent), and transmit the GARP request to the packet control part 31 (Step S35).
In a case where the apparatus itself is an operation system, the MIP control part 33 includes a mobile IP control protocol function (defined in RFC 2002 and RFC 3344) and a mobile IP control protocol transfer function for transferring a location registration request(s) to the standby system.
In a case where the apparatus itself is a standby system, the MIP control part 33 includes a mobile IP control protocol transfer function, and a mobile IP control protocol reception standby function for not transmitting a location registration request response, after forming a binding cache, in accordance a location registration request transferred from the operation system.
The MIP control part 33 also includes a mobile IP control binding cache recovery function for enabling the recovered operation system to recover its binding cache maintained by the standby. system when the operation system recovers, and a mobile IP control binding cache recovery monitor function for monitoring the recovery of the binding cache of the operation system.
In the flowchart, the mobile IP control protocol transfer function part receives a location registration request from the packet control part 31 and conducts location registration control according to RFC 2002, RFC 3344 (here, location registration includes, for example, registration, update, and/or deletion of location) (Step S41). Then, the mobile IP control protocol transfer function part determined whether the apparatus itself is an operation system (Step S42). If the apparatus itself is an operation system (YES in Step S42), the mobile IP control protocol transfer function part obtains the address of the transmission origin from the standby system list (Step S43), generates a location registration request in accordance with the address (Step S44), and sends the generated request to the packet control part 31 to be transferred to the standby system (Step S45).
In the flowchart, whenever a prescribed cycle elapses (Step S46), the mobile IP control information retransmission function part reads mobile IP control information (binding cache) 37 maintained by the operation system home agent (Step S47) for synchronizing the binding cache maintained by the operation system home agent and the binding cache maintained by the standby system home agent. Then, the mobile IP control information retransmission function part generates a location registration request according to the read binding cache (Step S48), and sends the request to the packet control part 31 to be transmitted to the standby system home agent (Step S49).
This function is conducted with the standby system, in which the binding cache, maintained by the standby system home agent during disorder of the operation system home agent, is provided to an operation system home agent that has recovered from the disorder.
In a case where the disorder monitor control part 34 detects recovery of the operation system, the mobile IP control binding cache recovery function part, upon receiving a request for transmittal of a location registration request, reads mobile IP control information (binding cache) (Step S51). After confirming the binding cache of the mobile terminal (MN) to be installed in the operation system home agent, a loop including the procedures of Steps S52 to S55 is executed in a number of times corresponding to the number of mobile terminals. In the loop, the mobile IP control binding cache recovery function part generates a location registration request with respect to one mobile terminal (Step S53), and sends the request to the packet control part 31 for transmission to the operation system (Step S54).
This function is conducted with the standby system for determining that the binding cache of all operation systems are recovered in a case of receiving a GARP request addressed to the mobile terminal from the ARP control part 32 of the operation system, wherein a system switch request is sent to the ARP control part 32 for switching systems with a GARP request after receiving GARP requests in a number corresponding to the number of mobile terminals requesting location registration as shown in
In
The disorder monitor control part 34 shown in
In the flowchart, the disorder monitor packet transmission function part determines whether the apparatus itself (home agent itself) is a standby system (Step S71). If the apparatus itself is a standby system (YES in Step S71), a first loop including Steps S72 to S78 is started in a predetermined cycle (Step S72). The disorder monitor packet transmission function part obtains an operation system list 36 (Step S73), and starts a second loop including Steps S74 to S77 (Step S74). That is, the disorder monitor packet transmission function part executes a arrival confirmation timer registration (Step S75), and sends an arrival confirmation request (arrival confirmation packet ping) to the packet control part 31 (Step S76) for transmission to respective operation system home agents.
In a case where the transmission origin is listed in the operation system list 36 (YES in Step S84), the disorder monitor packet reception function part cancels the arrival confirmation timer (Step S86). Then, the disorder monitor packet reception function part determines whether the previous state of the transmission origin is disordered (Step S87), in which the operation system is determined to be recovered only when the previous state of the transmission origin is disordered. The disorder monitor packet reception function part request the MIP control part 33 to transmit a location registration request (Step S88) for recovering the binding cache of the operation system.
Meanwhile, in a case where the apparatus itself is an operation system home agent (i.e. not a standby system home agent) (NO in Step S81), the disorder monitor packet reception function part starts an endless loop 2 including Steps S91 to S94 (Step S91). That is, the disorder monitor packet reception function part receives an arrival confirmation packet(s) from the packet control part 31 (Step S92), and sends the arrival confirmation packet to the packet control part 31 (Step S93) for transmission to the standby system home agent.
That is, the disorder monitor timer control function part detects timeout when no arrival confirmation packet(s) is received within an arrival confirmation period of a target apparatus (operation system home agent) (Step S103), and determines whether the previous state of the target apparatus is disordered (Step S104). Only when a timeout is detected for the first time in a case where the previous state of the target apparatus is not disordered, the disorder monitor timer control function part sends a disorder switch request to the ARP control part 32 (Step S105).
After the power of the home agent 24 is switched on, reading of an operation system list 36 is performed for obtaining a home agent (HA) address. Since an operation system list exists, the home agent 24 operates as a standby system. The home agent 24 sets the home agent address obtained from the operation system list 36 since the home agent 24 operates as the standby system, and enables reception of packets addressed to the home agent address.
Since the home agent 23 is an operation system, the response with respect to the ARP resolution from the router 22 is returned to the router 22 via the home link 21. The router 22, receiving the ARP response, transfers the location registration request addressed to the home agent to the home agent 231. The home agent 231, receiving the location registration request, generates a binding cache, and returns the location registration response to the mobile terminal 20.
Subsequently, the home agent 231 transfers the location registration request transmitted from the mobile terminal 20 to the standby home agent 24. After completing the transmission, the home agent 231 sets a location registration request retransmission timer. The standby system home agent 24, receiving the location registration request from the home agent 231, generates a binding cache which is the same as that of the home agent 231. The home agent 24 does not return a location registration response since the home agent 24 is operating as the standby system.
Next, as shown in
The router 22, receiving the ARP response, transfers the packets addressed to the mobile terminal 20 to the home agent 231. The home agent 231, receiving the packets addressed to the mobile terminal 20, encapsulates the packets and transfers the encapsulated packets according to the binding cache. The transferred encapsulated packets arrive at the mobile terminal 20 according to IP routing.
Likewise, in a case where location registration request(s) from periodic update and handover is transmitted from the mobile terminal 20 to the home agent address (HA), the home agent 231 receives the location registration request and transfers the request to the home agent 24.
However, since the home agent 24 is not activated, the location registration request cannot be received, and the binding cache cannot be generated.
After the home agent 24 is activated as the standby system, the binding cache of the home agent 24 would not conform (match) with that of the since the binding cache generated in the home agent 231 is not generated in the home agent 24.
In a case where there is a timeout (e.g. a timeout for a few minutes) of the location registration request retransmission timer upon receiving the location registration request, the home agent 231 retransmits the location registration requests of all the mobile terminals generating binding caches to the standby system home agent 24 so as to attaining conformity between the binding cache of the home agent 231 and that of the standby system home agent 24.
Subsequently, the standby system home agent 24, receiving the location registration requests, generates a binding cache, to thereby obtain a binding which is the same as that of the home agent 231.
The router 22, receiving the GARP, rewrites its ARP cache of the router, having a home agent (IP address) corresponding to the home agent 231 (MAC address) home agent and the mobile terminal 20 corresponding to the home agent 231 (MAC address), is rewritten in a manner where the home agent (IP address) corresponds to the home agent 24 and the mobile terminal 20 corresponds to the home agent 24 (MAC address).
Accordingly, the packets addressed to the mobile terminal 20 can be transferred from the communication terminal 27 to the home agent 24 via the home link 21 and the router 22, to thereby allow the home agent 24 to encapsulate and transfer the packets to the mobile terminal 20.
Furthermore, the packets addressed to the home agents (location registration requests) are transferred to the home agent 24 via the home link 21 and the router 22, and the home agent 24 continues to maintain its binding cache, to thereby continue communication between the communication terminal and the mobile terminal 20.
The operation system home agent 231, receiving the location registration requests, generates a binding cache transmits a GARP for rewriting the ARP cache maintained by a neighboring router 22, to thereby notify the router 22 to transfer packets addressed to the mobile terminal 20 to the operation system home agent 231. By receiving the GARP, the standby system home agent 24 determines that the location registration requests is properly sent to the operation system home agent 231 and that the binding cache is generated. However, the operation system home agent 231 does not return a response to the location registration requests from the standby system home agent 24.
In
Accordingly, packets addressed to the mobile terminal 20 are transferred from the communication terminal 27 to the operation system home agent 231 via the home link 21 and the router 22. The operation system home agent 231 encapsulates the packets and transfers the encapsulated packets to the operation system home agent 231.
In addition, location registration requests, which are also packets addressed to the operation system home agent 231, are also transferred to the operation system home agent 231 via the home link 21 and the router 22, and are maintained in the binding cache of the operation system home agent 231, thereby continuing communication between the communication terminal 27 and the mobile terminal 20.
The home agent 24 reads in finding the operation system list 36 for obtaining a home agent address. Since the operation system list 36 exists having plural home agent addresses listed thereto, the home agent 24 sets all of the home agent addresses for receiving all of the packets addressed to the home agent addresses. Subsequently, the operation described with FIGS. 17 to 22 is performed with respect to all of the home agent addresses.
In consequence, the present invention is able to achieve duplication of a home agent without requiring addition of a particular hardware. The home link can be provided in compliance to the mobile IP protocol control of RFC 2002 and RFC 3344. Furthermore, with the present invention, neither the mobile terminal nor the communication terminal is required to be subjected to a particular control due to a redundant configuration of the home agent. The home agent duplication configuration according to the present invention can be applied to a conventional mobile network.
The present invention ensures communication with mobile terminals without requiring any particular network configuration or hardware in a case of switching home agents due to home agent disorder. Accordingly, the present invention ensures network quality without requiring additional investment for equipment and the like. Since the duplication configuration according to the present invention does not require the standby system and the operation system to correspond on a one to one basis, the communication service provider may freely adjust the configuration to one system to N number of systems according to the investment cost and/or the required quality level.
Although the above-described example shown in Japanese Laid-Open Patent Application No. 10-512122 has a slave responding to a transferred message from a master, the present invention is different in that the standby system home agent does not respond to the transferred location registration request. Furthermore, although the above-described example shown in Japanese Laid-Open Patent Application No.2000-152315 uses a common line signal method for enhancing reliability of a health checkup, the present invention is different in that the standby system home agent monitors the operation system home agent by periodically sending an arrival confirmation request(s) to the operation system home agent. Furthermore, although the above-described example shown in Japanese Laid-Open Patent Application No.11-68780 applies mobile IP technology to an ATM network, the present invention is different in that the home agents are duplicated.
It is to be noted that the mobile IP control information 37 corresponds to an address correspondence maintaining unit, the packet control part 31 corresponds to a transferring unit (transmitting unit), the operation system list 36 corresponds to a home agent address maintaining unit, the MIP control part 33 corresponds to a sending unit and a no-responding unit, and the ARP control part 32 corresponds to a switching unit.
Further, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention.
The present application is based on Japanese priority application No.2004-076624 filed on Mar. 17, 2004, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-076624 | Mar 2004 | JP | national |
