Patent Application
20090116446
The present invention relates to a crossover node detecting method by a handover of a mobile terminal (mobile node) performing wireless communication, a crossover node detecting program for executing the above method by computer, and a mobile node and a relay apparatus used in the crossover node detecting method. In particular, the invention relates to a crossover node detecting method by a handover of a mobile node performing wireless communication by using mobile IPv6 (mobile Internet Protocol version 6), which is the next generation Internet protocol, a crossover node detecting program for executing this method by computer, and to a mobile node and a relay apparatus used in the crossover node detecting method.
Currently, discussions are going on at the NSIS (Next Step in Signaling) Working Group of the IETF (Internet Engineering Task Force) on the standardization of a new protocol called NSIS (see the Non-Patent Document 1 given below). It is expected that NSIS is particularly effective for QoS (Quality of Service) guarantee in mobile environment, and there are references, which describe the requirements and the methods for realization of QoS guarantee and mobility support in NSIS (e.g. see the Non-Patent Documents 2-6 given below). Description will be given below on general outline of NSIS, which is a draft specification prepared by the NSIS Working Group of the IETF, and also on the method to establish QoS path (see the Non-Patent Documents 3 and 5 given below).
Next, referring to
To identify the resource reservation, a flow identifier and a session identifier are used. The flow identifier depends on care-of address (CoA) of MN 10 or IP address of CN 60. Each of QNE 63 and QNE 65 can have knowledge of whether or not resource reservation has been made to the data packet by confirming IP address of transmission source and destination of each data packet. When MN 10 moves to other subnet and CoA has been changed, the flow identifier is changed to match the change of CoA of MN 10. On the other hand, the session identifier is used to identify a series of data transmission for the session, and it is not changed due to the handover of the MN 10 as in the case of the flow Identifier.
As a method to check the availability of QoS resource with respect to an arbitrary path, a method called QUERY is known. This method is in advance to check whether a desired Qspec can be reserved or not at each QNE when QoS path is established from MN 10 to CN 60. To check whether the desired Qspec can be reserved or not at each QNE, a QUERY message is transmitted. By a RESPONSE message, which is a reply to this QUERY message, the result can be received. The condition of the current resource reservation is never changed due to the QUERY and the RESPONSE messages. In order that QNE sends a notification to another QNE, a NOTIFY message can be used. This NOTIFY message is used, for instance, for notification of error. The RESERVE message, the QUERY message, the RESPONSE message, and the NOTIFY message as described above are the messages of NSLP for QoS guarantee and are described in the Non-Patent Document 3.
Next, referring to
As described above, the flow identifier is changed due to the handover of MN 10. As a result, the flow identifier X on the path 24, and a flow identifier on the path 34 (the flow identifier on this path 34 is referred as “Z”) are different from each other. Because there is no resource reservation to the session identifier Y on any of interfaces, QNE 67 judges that a new path has been established and performs resource reservation for the flow identifier Z and the session identifier Y. On the other hand, resource reservation to the session identifier Y already exists at QNE 65 and QNE 66. QNE 65 and QNE 66 compare the flow identifiers, and by confirming that the flow identifier has changed from X to Z, it is judged that a new path has been established to match the handover of MN 10. Then, means are taken such as updating of the old reservation without making reservation of new resource in order to avoid double resource reservation. The QNE where the old path and the new path begin to cross each other is called a crossover node (CRN). CRN may indicate a router where the routes actually begin to cross each other in some cases (such as NE 64 in
As the methods to discover CRN in early stage, the following methods are known: First, MN transmits a request with a pair of old flow identifier and session identifier to a new access router (NAR), which fulfills the function as a proxy. Then, NAR transmits a QUERY message to CN in order to discover CRN of uplink. When the QUERY message is received, QNE on the path confirms the pair of old flow identifier and session identifier and checks whether QNE itself is CRN or not. When the QUERY message is received, CN transmits the QUERY message to NAR in order to discover CRN of downlink. By this method, however, at least one RTT (Round Trip Time) is required up to the discovery of CRN. In some cases, RTT is delayed very much.
To overcome the above problems, it is an object of the present invention to provide a crossover node detecting method, by which it is possible to quickly detect CRN so that a mobile node performing handover can quickly and continuously receive additional services, which have been received before the handover, even after the handover, to provide a crossover node detecting program for executing the above method by computer, and also to provide a mobile node and a relay apparatus to be used in the crossover node detecting method.
To attain the above object, the present invention provides a crossover node detecting method in a communication system where a plurality of access routers each constituting a subnet are connected via a communication network of hierarchical structure, and at least one or more access points to form an inherent communicatable region are connected to each of said plurality of access routers, wherein a mobile node is designed to communicate with said access router where said access point is connected via wireless communication with said access point within said communicatable region, and said mobile node detects a crossover node where new and old communication paths cross each other and are branched off before and after the changing of connection on the communication network of said hierarchical structure when said mobile node handovers and the connection from the current communicating access point to another access point is changed over, wherein said method comprises a step where said mobile node compares an address suitable for a subnet constituted by an access router, to which said another access point is connected, with an address suitable for a subnet constituted by the access router where the access point currently communicating is connected, and extracts a common address portion; a step where said mobile node transmits a message including the extracted common address portion to a terminal of communication destination of its own; and a step where a relay apparatus able to decipher said message on the communication network of hierarchical structure positioned between said mobile node and said terminal of communication destination nudges whether the apparatus itself is a crossover node or not according to said message. With the arrangement as described above, it is possible to quickly find out CRN so that the mobile node performing the handover can quickly and continuously receive additional services, which have been received before the handover, even after the handover.
Also, the present invention provides the crossover node detecting method as described above, wherein said method further comprises a step where said relay apparatus on said communication network of said hierarchical structure positioned between said mobile node and said terminal of communication destination judges whether the apparatus itself is the crossover node or not according to said message, and if it is judged that the apparatus itself is the crossover node, said apparatus transmits a message including information relating to the apparatus itself to said mobile node. With the arrangement as described above, the mobile node can have information of the crossover node and can include the information of the crossover node in a RESERVE message and can transmit it when resource reservation is made after handover a subnet.
Further, the present invention provides the crossover node detecting method as described above, wherein said method further comprises: a step where said relay apparatus transfers said message when said relay apparatus on said communication network of said hierarchical structure positioned between said mobile node and said terminal of communication destination judges whether the apparatus itself is the crossover node or not according to said message, and if it is judged that the apparatus itself is not the crossover node, said method further comprises a step where said relay apparatus transfers said message.
With the arrangement as described above, even when the relay apparatus is not a crossover node, the mobile node is possible to find out the crossover node at transfer destination.
Also, the present invention provides a crossover node detecting program for executing the crossover node detecting method according to claim 1 by computer. With the arrangement as described above, it is possible to quickly find out CRN so that the mobile node performing the handover can quickly and continuously receive additional services, which have been received before the handover, even after the handover.
Further, the present invention provides a mobile node used in a crossover node detecting method in a communication system where a plurality of access routers each constituting a subnet are connected via a communication network of hierarchical structure, and at least one or more access points to form an inherent communicatable region are connected to each of said plurality of access routers, wherein a mobile node is designed to communicate with said access router where said access point is connected via wireless communication with said access point within said communicatable region, and said mobile node detects a crossover node where new and old communication paths cross each other and are branched off before and after the changing of connection on the communication network of said hierarchical structure when said mobile node handovers and the connection from the current communicating access point to another access point is changed over, wherein said mobile terminal comprises: means for generating an address suitable for a subnet constituted by an access router where said another access point is connected; means or extracting common address portion by comparing said address generated by said generating means with an address suitable for a subnet constituted by an access router where an access point currently communicating is connected; and means for transmitting a message including said extracted common address portion to a terminal at its own communication destination. With the arrangement as described above, it is possible to quickly find out CRN so that the mobile node performing the handover can quickly and continuously receive additional services, which have been received before the handover, even after the handover.
Also, the present invention provides a relay apparatus on said communication network of hierarchical structure positioned between said mobile node and a terminal at communication destination, said mobile node to be used in a crossover node detecting method in a communication system where a plurality of access routers each consisting a subnet are connected via a communication network of hierarchical structure, and at least one or more access points to form an inherent communicatable region are connected to each of said plurality of access routers, wherein a mobile node is designed to communicate with said access router where said access point is connected via wireless communication with said access point within said communicatable region, and said mobile node detects a crossover node where new and old communication paths cross each other and are branched off before and after the changing of connection on the communication network of said hierarchical structure when said mobile node handovers and the connection from the current communicating access point to another access point is changed over, wherein said relay apparatus comprises: means for receiving a message including a common address portion, said common address portion which is extracted by said mobile node comparing an address suitable for a subnet constituted by an access router, to which said another access point is connected, with an address suitable for a subnet constituted by an access router where an access point currently communicating is connected; and means for judging whether the apparatus itself is a crossover node or not according to said message received by said receiving means. With the arrangement as described above, it is possible to quickly find out CRN so that the mobile node performing the handover can quickly and continuously receive additional services, which have been received before the handover, even after the handover.
Further, it is a preferred aspect of the present invention to provide the relay apparatus as described above, wherein, when the apparatus itself is judged as a crossover node by said judging means, said apparatus has transmitting means for transmitting a message including information on the apparatus itself to said mobile node. With the arrangement as described above, the mobile node can have information of the crossover node and can include the information of the crossover node in a RESERVE message and transmit it when resource reservation is made after handover a subnet.
Also, it is a preferred aspect of the present invention to provide the relay apparatus as described above, wherein, when it is judged that the apparatus itself is not a crossover node by said judging means, said apparatus has transfer means for transferring said message. With the arrangement as described above, even when the relay apparatus is not a crossover node, the mobile node is possible to find out the crossover node at transfer destination.
The crossover detecting method, the crossover node detecting program for executing the above method by computer, and a mobile node and a relay apparatus used in the crossover node detecting method are based on the arrangement as described above, and a mobile node performing the handover can quickly find CRN so that the additional services, which the mobile node has been receiving before the handover, can be quickly and continuously received after the handover.
Detailed description will be given below on an embodiment of the present invention referring to
Next, description will be given on the function of MN 10.
The handover destination candidate determination means 101 is the means to receive a signal from a plurality of different APs and to search a list of APs, which are able to perform L2 handover, for instance. The wireless reception means 102 and the wireless transmission means 103 are the means for receiving and transmitting data by wireless communication respectively, and various functions necessary for performing wireless communication are included in these means.
The NCoA generation means 104 is the means for generating NCoA (IP address) to be used at the destination of handover. The NCoA method is, for instance, a method, in which MN 10 has locally an AP-AR correlation information 41 as shown in
In this case, however, NCoA is automatically generated in stateless manner, and it is necessary to have the means to confirm whether this NCoA can be actually used nor not in the subnet at the handover destination. For this reason, a processing is required so that AR with proxy function can check the validity of NCoA by selecting a subnet where AR itself can act as a proxy at the handover destination and by sending a message including NCoA to AR. As another method to acquire NCoA, there is a method, in which a currently communicating AR (i.e. AR belonging to the subnet 20 before the handover) receives a part of usable CoA in advance from DHCP (Dynamic Host Configuration Protocol) server of a neighboring subnetwork and one of CoAs received from the DHCP server of the subnet is allocated to MN 10 before MN 10 handovers to another AR (AR belonging to the subnet 30 after the handover). In this case, there is no need to check the validity of CoA because CoA is allocated in stateful manner.
The address extraction means 105 compares an IP address generated by the NCoA generation means 104 with an IP address suitable for the subnet 20 currently communicating, and extracts a portion of address commonly used. Because the communication network in the embodiment of the invention has hierarchical structure, by extracting the commonly used portion of the address, it is possible to acquire a part of the address of a router or QNE where the old path (path 24) and the new path (path 34) cross each other.
The message generation means 106 is the means for generating an NSIS signaling message (hereinafter, also referred as “message A”) including the portion of address extracted by the address extraction means 105. It may be so designed that information of the flow of data or signaling in the direction from MN 10 to CR 60 (upper stream) may be included in addition to the information of the portion of address thus extracted. These types of information are stored in the information storage means 107. The message A generated by the message generation means 106 is transmitted to CN 60 along the path 24, which is the path of the current communication, by the wireless transmission means 103. In this case, it may be so arranged that message (also called “message B”) to acquire information of QNE, which is adjacent to a router or a QNE not having the extracted address portion, may be transmitted together with the message A.
Next, description will be given on the function of AR 21, which receives the message A from MN 10.
The reception means 211 and the transmission means 212 are the means for receiving and transmitting the data. The judgment means 213 compares address information contained in the received message A with address information of AR 21 stored in the information storage means 215 and judges whether the address information contained in the message A is included in the address information of AR 21 or not. Concrete details of this judging will be described later. In case of AR 21 in the embodiment of the present invention, the address information contained in the message A is included in the address information of AR 21, and there may be QNE in upstream region where the path 24 and the path 34 cross each other. Accordingly, the transfer means 214 transfers the message A to an upstream router 69. The router 68 has the same arrangement and the same functions as those of the router 69 as described later, and detailed description is not given here.
Next, description will be given on the functions of QNE 63, which receives the message A from MN 10 via the router 68.
The reception means 631 and the transmission means 632 are the means for receiving and transmitting data respectively. The judgment means 633 is the means to compare the address information contained in the received message A with the address information of QNE 63 stored in the information storage means 635 and to judge whether or not the address information contained in the message A is included in the address information of QNE 63. Concrete details of the judging will be described later. In case of QNE 63 in the embodiment of the present invention, the address information contained in the message A is included in the address information of QNE 63, and there may be QNE in upstream region where the path 24 and the path 34 cross each other. Accordingly, the transfer means 634 transfers the message A so the router 69 in upstream region.
Next, description will be given on the functions of the router 69, which receives the message A from QNE 63.
The reception means 691 and the transmission means 692 are the means for receiving and transmitting data respectively. The message process means 693 is the means to decide how the received data or message should be processed. For instance, the router 69 does not have the function to decipher the message A, and the message process means 693 judges that the message A cannot be deciphered and delivers the message A to the transfer means 694. On the other hand, when information such as the data can be deciphered are received via the reception means 691, the message process means 693 performs adequate processing to the received data. The transfer means 694 delivers the message A delivered by the message processing means 693 to QNE 65 in upstream region.
Next, description will be given on the functions of QNE 65, which receives the message A from the router 69.
Here, discussion will be made on a case where the address information of AR 21 is “11110541”, the address information of AR 31 is “11110841”, the address information of QNE 63 is “11110441”, the address information of QNE 65 is “11110234”, the address information of QNE 66 is “11111345”, and the address information of QNE 67 is “11110631”. In this case, the address information contained in the message A is “11110”. When the address information “11110541” of AR 21 is compared with the address information “11110” contained in the message A, the address information contained in the message A is included in the address information “11110541” of AR 21. Accordingly, it is judged at AR 21 that a branching point may exist in upstream region. Next, when the address information “11110441” of QNE 63 is compared with the address information “11110” contained in the message A, and it is found that the address information “11110” in the message A is included in the address information or QNE 63. Therefore, it is judged at QNE 63 that a branching point may exist still in upstream region.
Next, when the address information “11110234” of QNE 65 is compared with the address information “11110” contained in the message A, and it is found that the address information “11110” in the message A is included in the address information “11110234” of QNE 65. Therefore, it is judged at QNE 65 that a branching point may exist still in upstream region. Next, when the address information “11111345” of QNE 66 is compared with the address information “11110” contained in the message A, and it is found that the address information “11110” contained in the message A is not included in the address information “11111345” of QNE 66. Therefore, it is judged at QNE 66 that a branching point exists downstream of QNE 66. This means that QNE 65 is CRN.
In this case, the transmission means not shown in the figure of QNE 66 may transmit to QNE65 information that QNE 65 is CRN. And it may be so arranged that QNE 65 transmits a message including information relating to QNE 65 (e.g. information such as IP address of QNE 65) to MN 10. In case QNE 65 receives the message B as described above and if it already knows address information “11111345” of the neighboring QNE 66, QNE 65 can judge that it is itself the CRN without the need of transmitting the message A to QNE 66 because the address information “11110” Included in message A is not included in the address information “11111345” of the neighboring QNE 66. It may be so arranged that the transmission means 652 of QNE 65 transmits a message (also called “message C”) including information relating to QNE 65 (e.g. information such as IP address of QNE 65) to MN 10 to response message B.
When the information of CRN (QNE 65) has been known, MN 10 can transmit the information of CRN (QNE 65) by putting it in the RESERVE message when resource reservation is made after handover the subnet. When the relevant CRN (QNE 65) receives the RESERVE message including information of CRN (QNE 65), the relevant CRN (QNE 65) may perform the processing so that double reservation of the resource may not be made to CN 60 way ahead. For instance, the CRN (QNE 65) may perform the processing such as updating of old reservation without newly reserving the resource. If CRN (QNE 65) is specified in advance in this way, even when it is resource reservation after the handover of MN 10, it is not the resource reservation while searching for CRN (QNE 65) such as prior art, and it is possible to quickly generate QoS path.
It may be so designed that AR 31 at the destination of handover of MN 10 does not generate QoS path but CRN (QNE 65) generates it. In this case, CORN (QNE 65) must have information necessary for generating QoS path (e.g. NCoA of MN 10, for which the validity has been confirmed, or IP address of CN 60). When CRN (QNE 65) transmits the RESERVE message to both CN 60 and AR 31, the QoS path can be updated from CRN (QNE 65) to CN 60, and a QoS path can be newly generated between CRN (QNE 65) and AR 31.
Next, referring to the sequence charts shown in
Next, MN 10 compares the generated IP address with the IP address suitable for the subnet 20 currently communicating and extracts a common address portion (Step S803). Then, MN 10 generates the message A including the information of the extracted address portion (Step S804). In addition to the information of the extracted address portion, information of flow of data and signaling from MN 10 toward the direction of CN 60 (upper stream) may be included in the message A. In this case, the message B as described above may be transmitted together with the message A. Then, MN 10 transmits the generated message A to CN 60 via the path 24, which is the current communication path (Step S805).
When the message A transmitted from MN 10 has been received by AR 21, AR 21 compares the address information contained in the message A with the address information of AR 21 stored in the information storage means 215 and judges whether the address information contained in the message A is included or not in the address information of AR 21 (Step S806). In case of AR 21 in the embodiment of the present invention, the address information in the message A is included in the address of AR 21, and there may be QNE in upstream region where the path 24 and the path 34 cross each other. Thus, AR 21 transfers the message A to the router 68 in upstream region (Step S807).
When the message A has been received by the router 68 from AR 21, the router 68 transfers the message A to QNE 63 because it does not have the function to decipher the message A (Step S808). Upon receipt of the message A, QNE 63 compares the address information contained in the message A with the address information of QNE 63 stored in the information storage means 635 and nudges whether the address information contained in the message A is included or not in the address information of QNE 63 (Step S809). In case of QNE 63 in the embodiment of the present invention, the address information in the message A is included in the address information of QNE 63, and also, there may be QNE in upstream region where the path 24 and the path 34 cross each other. Thus, QNE 63 transfers the message A to the router 69 in upstream region (Step S810).
When the message A has been received by the router 69 from QNE 63, the router 69 transfers the message A to QNE 65 because it does not have the function to decipher the message A like the router 68 (Step S811). Upon receipt of the message A, QNE 65 compares the address information contained in the message A with the address information of QNE 65 stored in the information storage means 655 and judges whether the address information contained in the message A is included or not in the address information of QNE 65 (Step S812). In case of QNE 65 in the embodiment of the present invention, the address information contained in the message A is included in the address information of QNE 65, and there may be QNE in upstream region where the path 24 and the path 34 cross each other. Accordingly, QNE 65 transfers the message A to QNE 66 in upstream region (Step S813).
When the message A has been received by QNE 66 from QNE 65, QNE 66 compares the address information in the message A with the address information of QNE 66 stored in the information storage means of itself not shown in the figure and judges whether the address information contained in the message A is included or not in the address information of QNE 66 (Step S314). In case of QNE 66 in the embodiment of the present invention, the address information contained in the message A is not included in the address information of QNE 66, and QNE 66 judges that QNE 65 in downstream region of QNE 66 is a CRN (Step S815). QNE 66 may transmit the information that QNE 65 is the CRN to QNE 65.
When QNE 65 judges that QNE 65 itself is CRN, a message including the information relating to QNE 65 (e.g. information such as IP address of QNE 65) to MN 10. By knowing the information of CRN (QNE 65), MN 10 can transmit the information of CRN (QNE 65) together with the RESERVE message when resource reservation is made after handover in the subnet. When the relevant CRN (QNE 65) receives the RESERVE message including the information of CRN (QNE 65), the relevant CRN (QNE 65) can perform the processing so that double reservation of the resource is not made to CN 60 way ahead. For instance, the relevant CRN (QNE 65) can perform the processing such as updating of old reservation instead of new resource reservation of the resource.
When QNE 65 receives the message B as given above and has knowledge of the address information of the adjacent QNE 66, it can judge that the address information contained in the message A is not included in the address information of the adjacent QNE 66. Accordingly, it can be judged the it is itself CRN without the need of transmitting the message A to QNE 66 in Step S813. QNE 65 may transmit a message C including the information relating to QNE 65 (e.g. information such as IP address of QNE 65) to MN 10 to give response to the received message B.
The expression of “transmission destination” as described in the present specification (e.g. the expression of “transmitting to CN 60”) does not necessarily mean the transmission by specifying the address of CN 60 as transmission destination address of IP header. It means that a partner to ultimately receive the message is CN 60.
Each functional block used in the explanations of the embodiment of the present embodiment, described above, can be realized as a large scale integration (LSI) that is typically an integrated circuit. Each functional block can be individually formed into a single chip. Alternatively, some or all of the functional blocks can be included and formed into a single chip. Although referred to here as the LSI, depending on differences in integration, the integrated circuit can be referred to as the integrated circuit (IC), a system LSI, a super LSI, or an ultra LSI. The method of forming the integrated circuit is not limited to LSI and can be actualized by a dedicated circuit or a general-purpose processor. A field programmable gate array (FPGA) that can be programmed after LSI manufacturing or a reconfigurable processor of which connections and settings of the circuit cells within the LSI can be reconfigured can be used. Furthermore, if a technology for forming the integrated circuit that can replace LSI is introduced as a result of the advancement of semiconductor technology or a different derivative technology, the integration of the functional blocks can naturally be performed using the technology. For example, the application of biotechnology is a possibility.
By the crossover node detecting method, the crossover node detecting program for executing this method by computer, and the mobile terminal (mobile node) and the relay apparatus used in the crossover node detecting method, CRN can be quickly found out so that the mobile node to perform the handover can quickly and continuously receive additional services, which have been received before the handover, after the handover. With regard to the crossover node detecting method by the handover of a mobile terminal (mobile node) performing wireless communication, the crossover node detecting program for executing the above method by computer, and the mobile node and the relay apparatus to be used in the crossover node detecting method, the present invention is useful—particularly in accomplishing the crossover node detecting method by the handover of the mobile node performing wireless communication using the mobile IPv6 protocol, which is the next generation Internet protocol, the crossover node detecting program for executing the method by computer, and the mobile node and the relay apparatus to be used in the method.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-200322 | Jul 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/313300 | 7/4/2006 | WO | 00 | 1/6/2008 |
