WO2008054002A1

WO2008054002A1 - Overlay network system and overlay network node

Info

Publication number: WO2008054002A1
Application number: PCT/JP2007/071435
Authority: WO
Inventors: Jun Hirano; Tien Ming Benjamin Koh; Chun Keong Benjamin Lim; Chan Wah Ng; Pek Yew Tan
Original assignee: Panasonic Corporation
Priority date: 2006-11-02
Filing date: 2007-10-29
Publication date: 2008-05-08

Abstract

The present invention discloses a technique to reliably offer specific functions to a subscriber of an overlay network service in an overlay network system where an overlay network node having specific functions and an overlay network node not having the specific functions are present in mixed state. According to this technique, when a mobile node 110 wants to receive the service relating to multi-interfaced functions, it is so arranged that a data packet transferred to LHA 150 and LHA 160 not having the multi-interfaced functions are sent via EHA 120, EHA 130 and EHA 140 having knowledge of the multi-interfaced functions. Specifically, binding information that a data packet addressed to the mobile node is transferred to EHA 140 (via a path 151) is registered, for instance, in a binding cache relating to the mobile node held at LHA 150.

Description

DESCRIPTION

OVERLAY NETWORK SYSTEM AND OVERLAY NETWORK NODE

TECHNICAL FIELD

The present invention relates to^' an overlay network system, which comprises the nodes of an overlay network for abstracting and representing a packet switched data communication network such as IP (Internet Protocol) network. The invention also relates to an overlay network node .

BACKGROUND ART

Currently, it is an important requirement that a user should be able to maintain the connectivity to Internet while roaming. In particular, the user must have connection to Internet at all times no matter wherever the user may be roaming. When a user moves from network to network, IP address must be changed, while this problem of the change of address is now solved by the introduction of the mobile IP.

In the working group Monami 6 (Mobile Nodes and Multiple Interfaces in IPv6) of the IETF (Internet Engineering Task Force) , discussions are being made to provide the functions, which can satisfactorily utilize the multi-mode characteristics to the multi-interfaced mobile node.

The multi-interfaced mobile node can register a plurality of care-of addresses acquired at the interface to the home agent. By the registration of a plurality of care-of addresses, the home agent can grasp that the mobile node can be reached via a plurality of routes.

Through the realization of this technique, the mobile node can specify a location where it wants to receive the data packet. Also, it is possible to determine the rules to specify the care-of address, which is to be the address for transmission of the streams (also called "flow") of data packets.

At the IETF, discussions are also being made in parallel to provide a method to optimize transmission route of the data packet to follow the moving of the mobile node using the mobile IP. This optimization is performed on various levels and in various formats. For instance, the end-to-end optimization between a transmitter and a receiver has been already discussed in the basic standards of the mobile IP. On the other hand, debates are still continued in many working groups of the IETF on the optimization between a mobile router or a mobile node and a home agent.

In the Non-Patent Document 1 as given below, a method for the optimization in an overlay network is proposed. According to this method proposed in the Non- Patent Document 1, the optimization of the route transparent to an end user can be accomplished by using a network of cooperative routers geographically dispersed. First, a mobile node of a user registers binding information to a home agent. The home agent distributes the binding information to other home agent within an overlay network geographically dispersed. As a result, the other home agent can also fulfill the function as a proxy home agent of the mobile node.

A data packet transmitted and received by the mobile node is intercepted by a proxy home agent nearest to the source node. After being encapsulated or decapsulated, it is tunneled to another proxy home agent located nearest to a destination node. In this way, in contrast to a route, which reaches the destination node via an original home agent (the home agent where the mobile node registered the binding information) from a source node, a path of the data packet is optimized between the source node and the destination node.

In the Patent Document 1 as given below, a technique is disclosed. According to this technique, in a system including a home agent, a home agent controller and a backup device, information held by the home agent is multi-cast to all controllers or the backup devices (backup home agents) , and the operation can be seamlessly switched over to the backup home agent.

Also, another technique is disclosed in the Patent Document 2 as given below, according to which an address of a virtual home agent is used and a client can be registered transparently to a plurality of home agents. In this technique, a plurality of home agents are so arranged that information is synchronized by "heartbeat" message and by multi-cast information. [Patent Document 1] U.S. Patent No. 7,080,151 [Patent Document 2] U.S. Patent No. 6,430,698

[Non-Patent Document 1] P. Thubert, et al . , "Global HA to HA protocol", Internet Engineering Task Force Internet Draft: draft-thubert-nemo-global-haha-01.txt, Work-in-Progress, 15 Oct 2005. However, the scope of the overlay network is limited. For instance, in a scope or a scale where an overlay network extending beyond the national border or across the continent is needed, cooperation of a multiple of service providers may be needed in order to actually accomplish the method proposed in the Non-Patent

Document 1. However, there are differences between the service providers, and it can be easily imagined that the nodes present in an overlay network do not necessarily concur with each other in the functions. In case a legacy home agent, not having the functions of Monami 6, is present in the overlay network, adequate cooperation cannot be attained between a home agent having the functions of Monami 6 and a legacy home agent. For instance, problem may arise that a subscriber of this service may not be able to receive the service in such extent as to match the counter value given to the behavior of the multi-interfaced node. Under such circumstance, filtering to match the user preference may not be attained to data stream, which passes through the legacy home agent, and the existing entry introduced in the legacy home agent must be followed.

Currently, a detailed operation method for the optimization of the overlay network is known. On the other hand, no solution is found yet on the problem as described above, which arises when the service is offered (the problem arising when overlay network nodes having different functions are present in mixed state) .

Further, the technique as disclosed in the Patent Document 1 brings benefit to the behavior of the overlay network, but it cannot support a system having different home agents with different abilities when the service for the subscriber must be guaranteed (i.e. in a system where the home agent having the functions of Monami 6 and the home agent not having the functions of Monami 6 coexist) . Similarly, in the technique disclosed in the Patent Document 2, adequate operation cannot be performed in this technique when the home agents have different functions .

DISCLOSURE OF THE INVENTION

To overcome the above problems, it is an object of the present invention to arrange that specific functions can be provided to the subscribers of the overlay- network service even in an overlay network system where an overlay network node having specific functions and an overlay network node not having specific functions are present in mixed state.

To attain the above object, the present invention provides an overlay network system, which comprises a plurality of overlay network nodes having functions relating to a specific overlay network service and one or more legacy overlay network nodes not having functions relating to said specific overlay network service, and an overlay network is formed on upper layer of a certain predetermined network, wherein: a data packet reaching said legacy overlay network node is transferred to an arbitrary overlay network node having functions relating to said specific overlay network service for the purpose of providing said specific overlay network service to an end node.

With the arrangement as described above, even in an overlay network system where an overlay network node having specific functions and an overlay network node not having the specific functions are present in mixed state, and the specific functions can be reliably provided to the subscribers of the overlay network service. Also, the present invention provides the overlay network system as described above, wherein, when an arbitrary overlay network node having function relating to said specific overlay network service grasps that said data packet is transferred either directly or indirectly from said legacy overlay network node to said end node while said specific overlay network service cannot be offered, an inquiry message including identification information of said legacy overlay network node and identification information of said end node is transmitted to a predetermined or an arbitrary overlay network node, identification information of an adequate overlay network node as a transfer destination of said data packet is received from said legacy overlay network node as a response to said inquiry message, and an instruction is given to said legacy overlay network node so that a data packet addressed to said end node is transferred to said adequate overlay network node.

With the- arrangement as described above, an overlay- network node makes inquiry to the other overlay network node and can have adequate transfer destination of a data packet from a legacy home agent.

-Further, the present invention provides the overlay network system as described above, wherein, when an overlay network node receiving said inquiry message receives a plurality of responses and grasps a plurality of said adequate overlay network nodes, one of said adequate overlay network nodes is selected from said plurality of adequate overlay network nodes, and an instruction is given to said legacy overlay network node as a transfer destination of said data packet. With the arrangement as described above, when a plurality of candidates for an adequate transfer destination have been obtained from a response to the inquiry, it is possible to select an adequate transfer destination from among the candidates.

Also, the present invention provides the overlay network system as described above, wherein, when an arbitrary overlay network node having function relating to said specific overlay network service grasps that said data packet is transferred to said end node from said legacy overlay network node, a Notify message including identification information of said legacy overlay network node and identification information of said end node is transmitted to a predetermined or an arbitrary overlay network node, an overlay network node receiving said Notify message judges whether the overlay network node itself is adequate or not as a transfer destination of said data packet addressed to said end node from said legacy overlay network node, and if it is judged that the overlay network node itself is adequate as the transfer destination of said data packet, an instruction is given to said legacy overlay network node so that the data packet addressed to said end node is transferred to the overlay network node itself. With the arrangement as described above, the overlay network node judges whether it can be an adequate transfer destination of the data packet from the legacy home agent or not. When it is judged that the overlay network node itself is an adequate transfer destination, an instruction can be given to the legacy home agent so that the data packet is transferred to the overlay network node.

Further, the present invention provides the overlay network system as described above, wherein, when an arbitrary overlay network node having function relating to said specific overlay network service grasps that said data packet is transferred either directly or indirectly from said legacy overlay network node to said end node while said specific overlay network service cannot be offered, it is so arranged that said end node grasps that registration or updating to need said specific overlay network service has been performed.

With the arrangement as described above, when an arbitrary overlay network node having the function relating to a specific overlay network service grasps that an end node has performed registration or updating to need the specific overlay network service, an operation can be carried out to the end node so that the functions relating to the specific overlay network service is reliably provided to the end node.

Also, the present invention provides the overlay network system as described above, wherein a path is set up to pass through the overlay network node, said node being judged as adequate as the data packet addressed to said end node, and it is so arranged that subsequent data packet addressed to said end node is transferred via said path.

With the arrangement as described above, based on the setting obtained by the operation according to the present invention, the transfer of the subsequent data packets can be carried out and the specific functions can be given to the end node by a single operation according to the present invention.

Further, the present invention provides the overlay network system as described above, wherein an overlay network node is set up in advance, said overlay network node having function relating to said specific overlay- network service adequate as a transfer destination of a data packet reaching said legacy overlay network node.

With the arrangement as described above, the specific functions can be reliably offered to the subscriber with high efficiency in a system with less change in network topology.

Also, to attain the above object, the present invention provides an overlay network node belonging to an overlay network node provided on upper layer of a predetermined network and having functions relating to a specific overlay network service, wherein said overlay network node comprises: means for transmitting an inquiry message including identification information of said legacy overlay network node and identification information of said end node to a predetermined or an arbitrary overlay network node when it is grasped that said data packet is transferred either directly or indirectly while said specific overlay network service cannot be offered to an end node to receive said specific overlay network service from a legacy overlay network node not having the functions relating to said specific overlay network service; means for receiving identification information of an overlay network node adequate as a transfer destination of said data packet from said legacy overlay network node as a response to said inquiry message; and means for giving an instruction to said legacy overlay network node so that the data packet addressed to said end node is to be transferred to said adequate overlay network node .

With the arrangement as described above, even in an overlay network system where an overlay network node having specific functions and an overlay network node not having the specific functions are present in mixed state, the specific functions can be reliably provided to the subscribers of the overlay network service. Also, with the arrangement as described above, an overlay network node makes inquiry to the other overlay network node and can have adequate transfer destination of a data packet from a legacy home agent.

Further, the present invention provides the overlay network node as described above, wherein said overlay network node has means for selecting one of said adequate overlay network nodes from a plurality of said adequate overlay network nodes when a plurality of responses to said inquiry message have been received and said plurality of adequate overlay network nodes have been grasped, and it is so arranged that an instruction is given to said legacy overlay network node that said selected adequate overlay network node is to be regarded as a transfer destination of said data packet.

With the arrangement as described above, when a plurality of candidates for an adequate transfer destination have been obtained from a response to the inquiry, it is possible to select an adequate transfer destination from among the candidates.

Further, the present invention provides the overlay network node as described above, wherein an overlay network node belonging to an overlay network node provided on upper layer of a predetermined network and having functions relating to a specific overlay network service, wherein said overlay network node comprises: means for transmitting a Notify message including identification information of said legacy overlay network node and identification information of said end node to a predetermined or an arbitrary overlay network node when it is grasped that said data packet is to be transferred to an end node receiving said specific overlay network service from an overlay network node not having the functions relating to said specific overlay network service; means for judging whether the overlay network node itself receiving said Notify message is adequate or not as a transfer destination of said data packet addressed to said end node from said legacy overlay network node; and means for giving an instruction to said legacy overlay network node so that the data packet addressed to said end node is to be transferred to the overlay network node when it is judged that the overlay network node itself is adequate as a transfer destination of said data packet.

With the arrangement as described above, even in an overlay network system where an overlay network node having specific functions and an overlay network node not having the specific functions are present in mixed state, the specific functions can be reliably provided to the subscribers of the overlay network service. Also, the overlay network node judges whether it can be an adequate transfer destination of the data packet from the legacy home agent or not. When it is judged that the overlay network node itself is an adequate transfer destination, an instruction can be given to the legacy home agent so that the data packet is transferred to the overlay network node . The present invention provides the overlay network node as described above, wherein an overlay network node belonging to an overlay network node provided on upper layer of a predetermined network and having functions relating to a specific overlay network service, wherein said overlay network node comprises: means for grasping an overlay network node adequate as a transfer destination of said data packet from said legacy overlay network node by referring to a predetermined setting information when it is grasped that said data packet is transferred to an end node receiving said specific overlay network service from an overlay network node not having the functions relating to said specific overlay network service; and means for giving an instruction to said legacy overlay network node so that the data packet addressed to said end node is to be transferred to said adequate overlay network node .

With the arrangement as described above, even in an overlay network system where an overlay network node having specific functions and an overlay network node not having the specific functions are present in mixed state, the specific functions can be reliably provided to the subscribers of the overlay network service. Also, the specific functions can be reliably offered to the subscriber with high efficiency in a system with less change in network topology.

Also, the present invention provides the overlay network node as described above, wherein it is so arranged that said end node grasps that registration or updating to need said specific overlay network service has been performed under the circumstance that said data packet is transferred either directly or indirectly while said specific overlay network service cannot be offered to said end node from said legacy overlay network node.

With the arrangement as described above, when it is grasped that an arbitrary overlay network node having specific functions grasps that the end node has performed registration or updating to need the specific overlay network service, an operation is carried out to reliably provide the specific functions to the end node, The present invention has the arrangement as described above. The invention has such effects that, even in an overlay network system where an overlay network node having specific functions and an overlay network node not having specific functions are^' present in mixed state, the specific functions can be reliably offered to the subscriber of the overlay network service,

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematical drawing to show an example of network arrangement in an embodiment of the present invention;

Fig. 2 schematically shows an example of information contained in an update message in the embodiment of the invention; Fig. 3 schematically shows an example of information contained in a Query message in the embodiment of the invention;

Fig. 4 schematically shows an example of information contained in a Response message in the embodiment of the invention; Fig. 5 schematically shows an example of information contained in a Notify message in the embodiment of the invention;

Fig. 6 is a block diagram to show the functions of EHA in the embodiment of the invention; and Fig. 7 is a flow chart to show an example of operation of EHA in the embodiment of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Description will be given below on the best aspect of the invention referring to the attached drawings.

Fig. 1 is a schematical drawing to show an example of network arrangement in an embodiment of the present invention. In the network arrangement shown in Fig. 1, a plurality of home agent, i.e. EHAs (Enhanced Home Agents) 120, 130, and 140, and LHAs (Legacy Home Agents) 150 and 160 are present in a network on a global network 100. Also, a mobile node 110 is in a state subscribed in the service of the overlay network.

Each of the EHAs 120, 130 and 140 is a home agent to execute registration function for multiple care-of addresses in Monami 6 and data flow filtering function as well as optimization function of the overlay network. Each of the EHAs 120, 130 and 140 is a home agent having the function of Monami 6 in addition to the standard function as prescribed in the mobile IP and the functions indispensable as a node on the overlay network. For this reason, it is referred as EHA (Enhanced Home Agent) in the present specification.

On the other hand, each of the LHA 150 and LHA 160 is a home agent to execute only the indispensable function (optimization function of the overlay network) as a node on the overlay network. Each of LHA 150 and LHA 160 has the standard function prescribed in the mobile IP and the indispensable function as a node on overlay network, but it does not have the functions of Monami 6. For this reason, it is referred as a "legacy" home agent in the present specification.

In Fig. 1, the mobile node 110 receives data streams from three correspondent nodes (CN 170, CN 180, and CN 190) . When the protocol stacks of Monami 6 are used, the mobile node can register an interface to use a path 111 connected to the global network 100 via EHA 120 and an interface using a path 112 connected to the global network 100 via EHA 130.

Further, the mobile node 110 can also specify how the data streams from CN 170, CN 180 and CN 190 are to be transferred. Here, discussion will be made on a case where the use of the path 112 is specified for the data stream from CN 170 and the use of the path 111 is specified for the data streams from CN 180 and CN 190.

According to the prior art, LHA 150 and LHA 160 cannot register a plurality of care-of addresses.

Accordingly, it is not possible to have a binding cache having a plurality of entries for a single mobile node 110. Therefore, each of LHA 150 and LHA 160 performs normal operation of the mobile IP and may have binding information relating to the current care-of address of the mobile node 110 by simply using information included in a first option of update information of the binding to be delivered on the overlay network. (In the overlay network, the function of Monami 6 is utilized, and binding information relating to the registration of a plurality of care-of addresses is distributed. )

LHA 150 and LHA 160 do not grasp that there is an alternative path to the mobile node 110 (i.e. the fact that the mobile node 110 can transmit and receive the data streams by using a plurality of paths) . Hence, LHA 150 and LHA 160 cannot be aware of the flow filtering rules from the mobile node 110 and cannot perform the operation according to the flow filtering rules.

According to the present invention, EHA, which understands the function of Monami 6, can update the binding cache of LHA relating to the mobile node 110 to an EHA adequately selected or elected, for instance. According to the binding information relating to the mobile node 110 held by LHA 150 and LHA 160, a specific EHA can be specified as transfer destination of a packet addressed to the mobile node 110. As a result, according to the operation of the present invention, EHA 150 can record EHA 140 as a next hop position relating to the mobile node 110, and LHA 160 can record EHA 130 as a next hop position relating to the same mobile node 110. The data streams from CN 170 and CN 180 to the mobile node 110 reach LHA 150 via a path 171 and a path 181, and the data streams are transferred to EHA 140 via a path 151 by LHA 150. Then, EHA 140 performs filtering according to the preference requested by the mobile node 110 and transfers the data via a path 141 and the path 111 to EHA 120 or transfers the data via a path 142 and the path 112 to EHA 130.

Similarly, on the data streams reaching EHA 130 from CN 190 via LHA 160 and via a path 161, EHA 130 performs filtering according to the preference requested from the mobile node 110 and transfers the data directly via the path 112 to the mobile node or transfers via a path 131 and the path 111 to EHA 120.

As described above, according to the present invention, the filtering can be adequately performed in accordance with the preference requested from the mobile node 110. As a result, improvement can be made on the situations in the past where the filtering could be adequately performed in accordance with the preference requested from the mobile node 110 and LHA 150 uses only one of the paths among a plurality of paths (e.g. a path, which holds only the binding information using the path 111) . All data packets are transferred to EHA 120, and the preference requested from the mobile node 110 can be accurately executed. Next, description will be given on several messages used in the present invention. It is not that all messages are needed, and the messages to be used can be selectively changed according to the condition of the implementation. Several messages used in the present invention contain important information elements, which are needed in the operation according to the present invention. These messages may be incorporated in or may be substituted with the existing protocol message such as the mobile IP or ICMP (Internet Control and Management Protocol) as far as the purpose and the effects can be attained.

Fig. 2 schematically shows an example of information included in an update message in an embodiment of the invention. Fig. 2 shows an update message to be used to give instruction to LHA that a packet addressed to the mobile node 110 should be transferred to an adequate EHA. This update message is transmitted from EHA to LHA.

According to the present invention, consideration is given on the interchangeability with LHA, which is not aware of the function of Monami 6, and the update message is embedded in the existing binding update message of the mobile IP or it is embedded in an arbitrary message used in the overlay network in order to update the node belonging to the overlay network. In Fig. 2, a type field 200 of the update message

(given as an update message type in Fig. 2) is used for the purpose of indicating that this message is an update message. As the value of the type field 200, an arbitrary value to be understood by both a transmission side node and a receiving side node can be set. For instance, when binding update message of the mobile IP is used as the update message, the value of the type field 200 is simply a value to indicate that this update message is a normal binding update message. Also, in a mobile node identifier field 210 (it is shown as a mobile node identifier in Fig. 2), identifier and location information of the mobile node 110 are included, and these are used to identify the mobile node 110 relating to the update message. In case of the mobile IP, a home address option may be used as the mobile node identifier field 210. Further, in a target proxy home agent identifier field 220 (it is given as a target proxy home agent identifier in Fig. 2), identifier and location information of EHA selected in relation to the mobile node 110 are included. In the example as given above, the value of the target proxy home agent identifier field 220 is the information of EHA 140 with regard to LHA 150 and the information of EHA 130 regard to LHA 160. This target proxy home agent is an EHA as set to a pair of the mobile node and LHA. According to the present invention, binding information of the address of the mobile node and the address of EHA is registered at LHA. When LHA intercepts a packet addressed to the mobile node, LHA will be able to transfer the packet to the associated EHA (target proxy home agent) . Then, the packet intercepted at LHA is always sent via a router passing through EHA and can receive the service based on the specific function supported at EHA. Hereinafter, the target proxy home agent may be described as a target proxy EHA.

When the binding update message of the mobile IP is used as this update message, a source address field or an alternative care-of address option field may be regarded as the target proxy home agent identifier field 220.

Fig. 3 schematically shows an example of information included in a query message in the embodiment of the invention. In Fig. 3, a format of the query message is shown.

According to the present invention, the query message is normally transmitted from EHA, which has no knowledge of the target proxy EHA relating to LHA or to the mobile node. When EHA transmits this query message, it is turned to a state to wait for a response .message, which is a response to this query message. This query message is a message to be transmitted for the purpose of grasping the target proxy EHA. So far as this purpose can be attained, it may be transmitted to a database already known, or it may be a multi-cast of a specific group or a broad-cast on the overlay network.

In Fig. 3, a type field 300 of the query message (given as a query message type in Fig. 3) is used to indicate that this message is a query message. Also, identifier and location information of the mobile node 110 are included in a mobile node identifier field 310

(given as a mobile node identifier in Fig. 3) , and it is used for accurately specifying the mobile node 110 relating to the query message. Also, identifier or location information of LHA is included in a legacy home agent identifier field 320 (given as a legacy home agent identifier in Fig. 3) , and this clearly indicates LHA relating to the query message.

An SN field 330 is a field where sequence number (SN) of this message is described. This SN field 330 is used to facilitate the matching of the pair of the mobile node and LHA, the specifying of the duplicated detection of the response message, and the optimization of the response message. In the overlay network where a plurality of LHAs are present, two or more pairs of the mobile node and LHA may exist. Values of different SN fields 220 (i.e. sequence numbers) are given to these pairs, and the values may be transmitted by a query message when necessary.

Fig. 4 schematically shows an example of information included in a response message in the embodiment of the invention. A format of the response message is given in Fig. 4. According to the present invention, this response message is transmitted as a response to the query message transmitted previously.

Fig. 4 shows a type field 400 of the response message (given as a response message type in Fig. 4), and this is a field to indicate that this message is a response message. Also, a sequence number present in the SN field 330 of the query message, which is the basis of the preparation of this response message, is included in an SN field 410.

When the sequence number is not present in the SN field 330 of the query message, a value of the mobile node identifier field 310 of the query message or a value of a legacy home agent identifier field 320 is inserted in the SN field 410 of the response message so that the same value as the query message is contained in it.

In a target proxy home agent identifier field 420 (given as a target proxy home agent identifier in Fig. 4), identifier or location information of EHA (target proxy home agent) , selected in relation to a pair of the mobile node 110 and LHA as described in the query message, is included.

Also, in a metric field 430 (given as a metric in Fig. 4) is an optional field, and additional information relating to the selection of EHA at the target proxy home agent identifier field 420 may be contained in it. For instance, in the metric field 430, information such as user preference or priority level and information such as current load and cost of EHA, which is a selected candidate, is included as information. A plurality of the target proxy home agent identifier field 410 and the metric field 430 may be present in duplication within the response message for providing a plurality of selected candidates (EHAs) as the response to the query message.

Fig. 5 schematically shows an example of information included in a Notify message in the embodiment of the invention. A format of the Notify message is given in Fig. 5. This Notify message is basically similar to the query message as explained in connection with Fig. 3, but it is different in that the transmitter of the

Notify message does not request a response to the Notify message.

The Notify message may be transmitted to a central controller of the mobile node 110 or it may be multi- cast to a multi-cast group of the controller node or it may be broadcast on an overlay network.

A type field 500 of the Notify message (given as a Notify message type in Fig. 5) is a field to indicate that this message is a Notify message. A mobile node identifier field 510 (given as a mobile node identifier in Fig. 5) and a legacy home agent identifier field 520 (given as a legacy home agent identifier in Fig. 5) fulfill the functions to attain the purpose similar to the one as explained in the query message shown in Fig. 3.

In order to accomplish the operation according to the present invention, several new functions must be introduced to EHA as described above. Fig. 6 is a block diagram to show the functions of EHA in the embodiment ^■ of the present invention. In Fig. 6, various types of functions needed by EHA are shown as functional blocks. The EHA shown in Fig. 6 corresponds to EHA 120, EHA 130 or EHA 140 as shown in Fig. 1, for instance.

In a lower layer interface 600, one or more physical network access cards or its drive and software API (Application Programming Interface) are included. A message to be inputted to or outputted from the network is delivered to each protocol stack via the lower layer interface 600. For instance, the message is delivered to an overlay network protocol processing unit 610 via a path 601, and to a mobile IP processing unit 620 via a path 602. In this case, a Monami 6 processing unit 630 to fulfill the Monami 6 function as described above is included in the mobile IP processing unit 620, which is a mobile IP stack. Also, an entity of a system manager 640 has the function to manage the operation according to the present invention. The system manager 640 receives a message relating to the present invention as described above from an overlay network protocol processing unit 610 via a path 610 or from a mobile IP processing unit 620 (and further, from a Monami 6 processing unit 630) via a path 621.

The system manager 640 can gain access to a negotiation processing unit 650 with negotiation function and to a decision processing unit 660 having decision function. Fig. 6 shows an example of arrangement, in which the system manager 640 is mounted with the negotiation function and the decision function, and the system manager 640 includes the negotiation processing unit 650 and the decision processing unit 660.

Further, the system manager 640 is connected to a policy engine 670 via a path 641. The policy engine 670 is realized, for instance, as a remote entity arranged at a remote site, and a system manager of LHA may perform communication with the policy engine via the network.

Also, the system manager 640 has the functions to operate the negotiation processing unit 650 or the decision processing unit 660 depending on the circumstances or to make inquiry on the policy engine 670 when necessary.

The policy engine 670 is a local repository or a remote repository of the rules or the policy to match the selection of a candidate of the target proxy EHA relating to each pair of the mobile node 110 and LHA.

The negotiation processing unit 650 performs the processing for the purpose of acquiring a candidate of the target proxy EHA relating to a predetermined pair of the mobile node 110 and LHA. In the overlay network, there must be a candidate for at least one target proxy EHA to one LHA. This information is transmitted from the negotiation processing unit 650 to the decision processing unit 660.

The operation at the negotiation processing unit 650 or the decision processing unit 660 largely depends on the conditions of implementation. These operations can be divided to the three cases as given below. In all of these three cases, the EHA where operations of the negotiation processing unit 650 and the decision processing unit 660 are performed may be an EHA, which received a request from the mobile node 110 or may be a central entity to perform the management on the operation relating to the mobile node 110.

In the first case as given above, it is so arranged that the negotiation processing unit 650 creates and transmits the query message as shown in Fig. 3. The negotiation processing unit 650 of the other EHA, which receives this query message, creates a response message according to local information or domain information and replies to the EHA, which has given the request (source node of the query message) .

The negotiation processing unit 650 of the EHA, which is the source node of the query message, acquires one or more response messages received and delivers information in each response message (the information included in the target proxy home agent identifier field 420) or additional information (the information included in the metric field 430) to the decision processing unit 660.

The decision processing unit 660 selects an EHA, which becomes a candidate relating to each LHA, by using the rules and the policy acquired from the policy- engine 670, for instance, and transmits an update message as shown in Fig. 2 to each LHA.

The decision processing unit 660 can select an EHA, which becomes a candidate relating to each LHA, by using various types of information such as traffic or load conditions, or amount of network resources available at EHA. The threshold value to be used as judging criteria of these types of information can be acquired from the policy engine 670, for instance. According to this first case, the number of the messages to be used can be efficiently controlled. Also, the target proxy home agent can be dynamically selected.

In the second case, it is so arranged that the negotiation function 650 of EHA transmits a Notify message as shown in Fig. 5 when a request to ask the service is received from the mobile node 110.

Upon receipt of this Notify message, EHA delivers the information included in the Notify message to the local decision processing unit 660. The decision processing unit 660 decides whether to run as a candidate or not as the target proxy EHA for each of the LHAs described in the received Notify message according to the information currently grasped. When the decision processing unit 660 judges that it is an adequate candidate for the target proxy EHA relating to the LHA, the decision processing unit 660 creates and transmits an update message to the LHA. The decision processing unit 660 can judge whether it is adequate or not to run by itself as a candidate for each LHA by using various types of information such as traffic or load conditions, or amount of network resources available at EHA.

In the second case, a plurality of EHAs (e.g. a plurality of EHAs existing around LHA) may run as candidates in duplication as the target proxy EHA to one LHA. As a result, each LHA may receive a plurality of update messages. Binding cache is sequentially overwritten according to the information obtained from the update message. Also, in order that there will be no LHA, which does not receive the update message, the source node of the Notify message must transmit the update message with the information relating to the target proxy EHA as selected by default or selected arbitrarily to all of the LHAs.

This second case is easy to execute. Further, it is advantageous in that LHA can be arranged dynamically by using real-time data, and the cost for calculation of EHA can be reduced.

The third case may be a case where the negotiation processing unit 650 and the decision processing unit 660 have already grasped the topology of the overlay network. In this case, it is so arranged, for instance, that the negotiation processing unit 650 acquires a list of EHAs, which are to run as candidates for each pair of the mobile node and LHA from the local database or from remote database, and that the decision processing unit 660 creates and transmits the update message to each LHA.

In the third case, static information (e.g. location information or the like) is normally used for the selection of the target proxy home agent. By providing a centralized information server to offer quasi-static information on the network, improvement can be made so that it does not depend too much upon the static information.

According to the third case, the number of the transmitting messages can be efficiently reduced. The response can be obtained more quickly and the time to the updating of LHA can be shortened.

Fig. 7 is a flow chart to show an example of the behavior of EHA in the embodiment of the invention. The flow chart of Fig. 7 shows an overview of the behavior of EHA. In the flow chart shown in Fig. 7, assumption is made on a case where EHA takes an idle state as the initial state (Step S700) . When EHA receives a binding update message (i.e. binding update of Monami 6) to request the function specific to Monami 6 and not supported by LHA (such as registration of a plurality of care-of addresses and flow filtering function) from the mobile node 110, a pair of the mobile node and LHA is created for all of LHAs of the overlay network (Step S720) .

These pairs are delivered to the negotiation processing unit 650 and the decision processing unit 660, and an adequate EHA for each LHA of the overlay network is selected as the target proxy EHA (Step S730) for the mobile node 110. After the target proxy EHA has been selected for each LHA, update message including the target proxy EHA is created and transmitted to each LHA (Step S740) . EHA to be selected as the target proxy EHA of each LHA may be different for each pair of LHA and the mobile node.

In the present invention, improvement may be made on various functions available at EHA (the function, which the mobile node is going to use but is not supported by LHA) in addition to the function to select the path. As an example of such functions, there are dynamic load balancing, improvement of dynamic quality up-grading and down-grading of the media stream, QoS guarantee, etc.

In the present specification, drawings and descriptions have been given to pay due attention and consideration that the present invention represents the most practical and the preferred embodiment. However, it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and the scope of the claims in the details of design and parameters relating to the system manager 640, the negotiation processing unit 650, the decision processing unit 660 or other component elements .

Each of the functional blocks used in the description of the embodiment of the invention can be realized as an LSI (Large Scale Integration) , typically represented by an integrated circuit. These may be produced individually as one chip or may be produced in a single chip including a part or all. Here, it is referred as LSI, while it may be called IC (Integrated Circuit) , system LSI, super LSI or ultra LSI, depending on the difference in the degree of integration.

Also, the method to produce the integrated circuit is not limited to LSI, and it may be realized by a dedicated circuit or a general-purpose processor. After the manufacture of LSI, FPGA (Field Programmable Gate Array) , which can be programmed after the manufacture of LSI, or a reconfigurable processor, in which connection or setting of circuit cells inside LSI can be reconfigured, may be used. Further, with the progress in semiconductor technique or other technique derived from it, if a new technique of circuit integration to replace LSI may emerge, the functional blocks may be integrated by using such technique. For instance, the adaptation of biotechnology is one of such possibilities.

INDUSTRIAL APPLICABILITY

The present invention provides the effects that, even when an overlay network node having specific functions and an overlay network node not having specific functions are present in mixed state in an overlay network system, the specific functions can be reliably offered to a subscriber of the overlay network service. The present invention can be applied to an overlay network, which abstracts and represents a packet switched data communication network such as IP network.

Claims

1. An overlay network system, comprising a plurality of overlay network nodes having functions relating to a specific overlay network service and one or more legacy overlay network nodes not having functions relating to said specific overlay network service, and an overlay network is formed on upper layer of a certain predetermined network, wherein: a data packet reaching said legacy ^■ overlay network node is transferred to an arbitrary overlay network node having functions relating to said specific overlay network service for the purpose of providing said specific overlay network service to an end node.

2. The overlay network system according to claim 1, wherein, when an arbitrary overlay network node having function relating to said specific overlay network service grasps that said data packet is transferred either directly or indirectly from said legacy overlay network node to said end node while said specific overlay network service cannot be offered, an inquiry message including identification information of said legacy overlay network node and identification information of said end node is transmitted to a predetermined or an arbitrary overlay network node, identification information of an adequate overlay network node as a transfer destination of said data packet is received from said legacy overlay network node as a response to said inquiry message, and an instruction is given to said legacy overlay network node so that a data packet addressed to said end node is transferred to said adequate overlay network node.

3. The overlay network system according to claim 2, wherein, when an overlay network node receiving said inquiry message receives a plurality of responses and grasps a plurality of said adequate overlay network nodes, one of said adequate overlay network nodes is selected from said plurality of adequate overlay network nodes, and an instruction is given to said legacy overlay network node as a transfer destination of said data packet.

4. The overlay network system according to claim 1, wherein, when an arbitrary overlay network node having function relating to said specific overlay network service grasps that said data packet is transferred to said end node from said legacy overlay network node, a Notify message including identification information of said legacy overlay network node and identification information of said end node is transmitted to a predetermined or an arbitrary overlay .network node, an overlay network node receiving said Notify message judges whether the overlay network node itself is adequate or not as a transfer destination of said data packet addressed to said end node from said legacy overlay network node, and if it is judged that the overlay network node itself is adequate as the transfer destination of said data packet, an instruction is given to said legacy overlay network node so that the data packet addressed to said end node is transferred to the overlay network node itself.

5. The overlay network system according to claim 2, wherein, when an arbitrary overlay network node having function relating to said specific overlay network service grasps that said data packet is transferred either directly or indirectly from said legacy overlay network node to said end node while said specific overlay network service cannot be offered, it is so arranged that said end node grasps that registration or updating to need said specific overlay network service has been performed.

6. The overlay network system according to claim 4, wherein, when an arbitrary overlay network node having function relating to said specific overlay network service grasps that said data packet is transferred either directly or indirectly from said legacy overlay network node to said end node while said specific overlay network service cannot be offered, it is so arranged that said end node grasps that registration or updating to need said specific overlay network service has been performed.

7. The overlay network system according to claim 2, wherein a path is set up to pass through the overlay network node, said node being judged as adequate as the data packet addressed to said end node, and it is so arranged that subsequent data packet addressed to said end node is transferred via said path.

8. The overlay network system according to claim 4, wherein a path is set up to pass through the overlay network node, said node being judged as adequate as the data packet addressed to said end node, and it is so arranged that subsequent data packet addressed to said end node is transferred via said path.

9. The overlay network system according to claim 1, wherein an overlay network node is set up in advance, said overlay network node having function relating to said specific overlay network service adequate as a transfer destination of a data packet reaching said legacy overlay network node.

10. An overlay network node belonging to an overlay network node provided on upper layer of a predetermined network and having functions relating to a specific overlay network service, wherein said overlay network node comprises: means for transmitting an inquiry message including identification information of said legacy overlay network node and identification information of said end node to a predetermined or an arbitrary overlay network node when it is grasped that said data packet is transferred either directly or indirectly while said specific overlay network service cannot be offered to an end node to receive said specific overlay network service from a legacy overlay network node not having the functions relating to said specific overlay network service; means for receiving identification information of an overlay network node adequate as a transfer destination of said data packet from said legacy overlay network node as a response to said inquiry message; and means for giving an instruction to said legacy overlay network node so that the data packet addressed to said end node is to be transferred to said adequate overlay network node.

11. The overlay network node according to claim 10, wherein: said overlay network node has means for selecting one of said adequate overlay network nodes from a plurality of said adequate overlay network nodes when a plurality of responses to said inquiry message have been received and said plurality of adequate overlay network nodes have been grasped, and it is so arranged that an instruction is given to said legacy overlay network node that said selected adequate overlay network node is to 'be regarded as a transfer destination of said data packet.

12. An overlay network node belonging to an overlay network node provided on upper layer of a predetermined network and having functions relating to a specific overlay network service, wherein said overlay network node comprises: means for transmitting a Notify message including identification information of said legacy overlay network node and identification information of said end node to a predetermined or an arbitrary overlay network node when it is grasped that said data packet is to be transferred to an end node receiving said specific overlay network service from an overlay network node not having the functions relating to said specific overlay network service; means for judging whether the overlay network node itself receiving said Notify message is adequate or not as a transfer destination of said data packet addressed to said end node from said legacy overlay network node; and means for giving an instruction to said legacy overlay network node so that the data packet addressed to said end node is to be transferred to the overlay network node when it is judged that the overlay network node itself is adequate as a transfer destination of said data packet.

13. An overlay network node belonging to an overlay network node provided on upper layer of a predetermined network and having functions relating to a specific overlay network service, wherein said overlay network node comprises: means for grasping an overlay network node adequate as a transfer destination of said data packet from said legacy overlay network node by referring to a predetermined setting information when it is grasped that said data packet is to be transferred to an end node receiving said specific overlay network service from an overlay network node not having the functions relating to said specific overlay network service; and means for giving an instruction to said legacy overlay network node so that the data packet addressed to said end node is to be transferred to said adequate overlay network node.

14. The overlay network node according to claim 10, wherein it is so arranged that said end node grasps that registration or updating to need said specific overlay network service has been performed under the circumstance that said data packet is transferred either directly or indirectly while said specific overlay network service cannot be offered to said end node from said legacy overlay network node.

15. The overlay network node according to claim 12, wherein it is so arranged that said end node grasps that registration or updating to need said specific overlay network service has been performed under the circumstance that said data packet is transferred either directly or indirectly while said specific overlay network service cannot be offered to said end node from said legacy overlay network node.

16. The overlay network node according to claim 13, wherein it is so arranged that said end node grasps that registration or updating to need said specific overlay network service has been performed under the circumstance that said data packet is transferred either directly or indirectly while said specific overlay network service cannot be offered to said end node from said legacy overlay network node.