Patent Application
20050089034
The present invention relates to a technique of virtually or logically configuring within the LAN a network dedicated to use among specific group members, and a technique of performing routing using a label in packet communication.
These days, general-purpose information processing apparatuses such as a personal computer (to be simply referred to as a PC hereinafter) have become tools necessary for daily work, and create and edit many data every day. At present, sharing of information and various devices (printer and the like) is indispensable, and PCs are connected to a LAN (Local Area Network) (“IDG Information Communication Series: 10 Gigabit Ethernet Textbook” published by IDG Japan, “IDG Information Communication Series: Multiprotocol Label Switching Textbook” published by IDG Japan, and “Microsoft Windows2000 Server Resource Kit” published by Nikkei BP SoftPress).
When a LAN is constructed, PCs, i.e., client terminal devices (to be referred to as client devices hereinafter) used by users and a server computer (to be referred to as a server device hereinafter) exist on the LAN. These devices are connected by a connection device (switching hub: to be simply referred to as a switch hereinafter) to share data via the server device.
Information as an individual product created by a PC is utilized as shared data in a group, subjected to correction, reference, and improvement, and stored as precise results in a database shared within the group.
The server-client environment using the LAN has rapidly spread in office. A client PC is set on the desk of each worker, whereas the server is installed in a server room managed by the administrator and provides a data infrastructure for daily work. Data sharing in the company LAN produces a high added value which can be achieved not by an individual but by cooperative work (collaboration). Data sharing becomes the core of business activity.
The LAN environment has rapidly been developed as the information infrastructure of the company, and at present has reached a large scale in which almost all workers in the company participate in this environment.
Recently, terminal devices of a new type which assume common use in LAN connection become available along with the spread of the LAN infrastructure. Preferable examples are a network camera and video distribution server. Such device distributes a relatively large volume of color moving picture data by streaming to the LAN, and a PC receives and displays the data.
As the LAN scale becomes large, new needs arise in the company LAN.
One of the needs is a demand for virtually configuring a dedicated network used among specific members in the company, i.e., a network for a specific group.
In particular, this need is strong among members of a specific group such as a human resources group, manager group, or project group which treats confidential information. Jobs among specific members often have contents with high priority, and thus are desirably processed preferentially to LAN packets.
A need from another viewpoint is a demand for separating the traffic between an image terminal device and a general terminal in order to prevent traffic congestion due to image data streaming distribution caused by an image-associated terminal device (multimedia terminal device) present in the LAN. This need is strong especially in, e.g., a design or development group in which visual communication is indispensable for work. The current LAN processes streaming data similarly to general data packets. Images may be omitted due to a congestion delay of data packets unless the data compression ratio is increased. However, an increase in compression ratio degrades the image quality, and there are needs for separation of stream data, and a priority process for separated stream data that is different from a priority process for general packets.
These needs are summarized into a technical demand “a network configured by only specific terminal devices subjected to a priority process is implemented in a general LAN”.
The first need is the implementation of a private area network within the LAN that is configured by terminal devices (personal computers) used by specific members with high secureness. In other words, the first need is the implementation of channel separation of the data traffic within a specific group from the general LAN traffic for the purpose of security. This need also arises for a priority process for the traffic separated from the LAN traffic.
The second need is the implementation of a private area network within the LAN that is configured by specific multimedia terminal devices. In other words, the second need is the implementation of channel separation between streaming data and general LAN data. This need also arises for a priority process for stream data over general packets.
These needs are summed up into the following requirements for a private area network within the LAN.
1. A terminal device in a specific group must be accessible to a company information terminal device within the LAN.
2. An outsider terminal device within the LAN must not be accessible to a terminal device in a specific group.
3. Terminal devices in different specific groups must not be accessible to each other.
4. A specific group packet is processed preferentially to a LAN packet.
That is, the priority is set to “specific group packet>LAN packet”.
5. A stream packet from a specific group is processed preferentially to a general packet.
That is, the priority is set to “stream of specific group>general packet of specific group”.
From requirement 1, an area network for a specific terminal device group must be virtually configured within the LAN instead of configuring an area network independently of the company LAN.
In order to implement a virtual private area network within the LAN, the following methods are taken.
1. A dedicated domain is created for terminal devices of a specific group and managed by a dedicated server.
2. A company LAN is configured with a single domain, and a specific group is formed and managed as a user group.
According to the first method, since a domain different from that of a general LAN in the company is set, user names, passwords, and the like dedicated to the domain of the specific group can be used.
According to the second method, since a specific group is one of user groups within a single domain, user names, passwords, and the like are set for only the single domain. Management of access to a resource by the specific group depends on rights setting of the specific group in the domain server.
These methods suffer the following problems.
User authentication is group management on the basis of the user name and password of the specific group to the dedicated domain in the first method, and similarly on the basis of the authentication result of the user name and password in log-on to the single LAN domain in the second method.
In either case, access is managed on the basis of authentication of “user name and password”, which is weak in the company LAN.
The company holds public information on an individual such as the employee number, extension number, and position, and the department holds an address book and the like. It is not difficult to break a password by analogy based on the public information.
That is, the security of password management is not strong in the company LAN.
In addition, the IP communication method in the current LAN has a security problem. IP communication broadcasts address information of a terminal device. Any terminal devices can be connected to communicate with each other as far as they are electrically connected to the LAN. Access management is performed on the session layer, which is a fundamental problem. The current LAN transmits data by an IEEE 802.3 Ethernet® method. The feature of this communication method is based on a media access control (MAC) address corresponding to MAC and an IP address corresponding to the data link layer. The IP address represents the final transmission destination address, and the MAC address represents the next transfer destination address in each transmission step. Since the MAC address must be acquired from the IP address of a partner device, an ARP (Address Resolution Protocol) is adopted. This protocol makes it possible to transmit data by the MAC address as far as the partner device falls within the subnet range. If the partner device falls outside the subnet range, a router is interposed, and the first transmission destination becomes the MAC address of the router.
The originating IP address and originating MAC address of a terminal device must be set in a transmission packet in order to receive a response from the partner device. As a method of obtaining the IP address of the terminal device, the DHCP is used. The MAC address is a known address which is set in the factory and held by the network card of the terminal device.
More specifically, the terminal device must issue an inquiry in order to obtain its IP address and the MAC address of the transfer destination. The current IP network always performs connection in any one of the data link layer (Ethernet), network layer (IP layer), and transport layer (TCP/UDP layer). In other words, terminal devices can be basically connected, and a security function of determining whether their connection is permitted depends on password management by an application on the session layer or upper layer.
The subnet communication method (layer 2 communication) after acquiring the IP address of the terminal device and the MAC address of the transfer destination is as follows. Within the subnet, communication connection is done using only the MAC address. When the layer 2 communication method based on the MAC address is defined as a LAN communication method, details of the LAN communication method within the subnet are as follows.
This communication method will be explained by exemplifying communication between device A connected to port “1” of a LAN switch (switching hub) and device B connected to port “5”, as shown in
Assume that device A is to communicate with device B.
1. Device A sets its MAC address MAC-A, its IP address IP-A, MAC address MAC-B of the partner device, and IP address IP-B of the partner device in an Ether frame to generate and transmit transmission frame FR-A.
2. The LAN switch reads originating MAC address MAC-A from input frame FR-A from port 1, and registers MAC address MAC-A in a MAC address table ensured in the apparatus. The MAC address table holds the correspondence between the port number (in this case, port “1”) and MAC address MAC-A.
3. The switch does not have the MAC address of destination device B in the MAC address table at first, and broadcasts (or floods) the input packet to all associated ports.
4. When the destination MAC of received frame FR-A coincides with MAC address MAC-B of device B, destination device B which has received broadcasted frame FR-A sets its MAC address MAC-B, its IP address IP-B, MAC address MAC-A of the partner device, and IP address IP-A of the partner device in Ether frame FR-B, and sends back Ether frame FR-B.
5. In
Subsequent communication between device A and device B is one-to-one communication without flooding because the addresses of the two terminal devices have been registered in the MAC address table of the switch. Communication between the two devices does not influence other ports.
After a series of communication operations end and when a predetermined time (e.g., 5 min) has elapsed, the correspondence “port and originating MAC address” registered in the MAC address table within the LAN switch is deleted.
In this LAN communication,
1. The MAC address and IP address of a transmission device leak due to flooding.
2. This method always permits communication connection between devices, and authentication of access to a partner device depends on password check on the session stage.
For this reason, a MAC address and IP address can be acquired on the basis of a broadcasted flooding packet. By generating a frame having a disguise MAC address and IP address, up to communication connection on the transport layer can be achieved. Access management depends on only password authentication management on the session layer.
Since the MAC address (set in the manufacture) and IP address (set by the DHCP) are given values which cannot be changed by the user, leakage cannot be prevented by any measure such as a periodic change of the MAC address and IP address. Also, the password is very weak in the company and can be easily broken by analogy, as described above.
In this manner, the conventional method can construct a specific group area network within the LAN, but cannot construct a securely separated specific group area network.
The following problem also occurs in the implementation of a private area network by image terminal devices of a specific group.
In LAN communication, transaction type burst (or bulk) data of a general LAN terminal device (personal computer) and stream type successive data of an image terminal device are similarly divided into Ethernet packets and then transmitted. Stream type data requires isochronism in regard to the time, but an attribute which can be added to packet data is only priority in the packet process queue. For example, when a burst jumbo packet pertaining to burst data is being transferred, transmission of even a stream packet with the highest priority must wait for the end of the transfer process.
In this manner, a burst packet and stream packet are transmitted by the same process and controlled by only the process order priority. A stream packet from an image terminal device is obstructed by a burst packet from a general LAN terminal device, and cannot be supplied at a necessary timing.
These problems can be easily understood from the assumption that a network monitor directly connectable to the LAN is developed and the isochronous stream of uncompressed image data is transmitted via the LAN and displayed on the network monitor.
That is, the current LAN suffers contention between stream data and general burst data of a personal computer on the LAN. In this case, stream data must be permitted to pass even by interrupting general burst data during processing.
As described above, the conventional LAN cannot preferentially process stream data.
It is an object of the present invention to implement a secure specific group area network which is configured by only specific terminal devices within the LAN.
For this purpose, the present invention proposes a new communication method which is different from the conventional LAN communication method and is used for communication between specific terminal devices. The LAN method is used for communication in the general LAN, whereas the new communication technique is used in the specific group.
The new communication technique has the following requirements.
First, communication does not leak address information such as the MAC address or IP address. That is, a technique which does not require flooding is provided.
Second, communication connection between unnecessary terminal devices is basically inhibited, and security on a layer lower than the session stage is ensured. That is, unwanted terminal devices cannot be connected (no data link).
Third, the frame format of the Ethernet (IEEE 802.3) is maintained, and compatibility and coexistence with existing LAN communication are achieved.
It is another object of the present invention to provide a configuration/means for implementing a private area network within the LAN with the following features on the basis of the new communication method.
1. A terminal device in a specific group must be accessible to a company information terminal device within the LAN.
2. An outsider terminal device within the LAN must not be accessible to a terminal device in a specific group.
3. Terminal devices in different specific groups must not be accessible.
Connection switches and specific terminal devices require a configuration which copes with both communication means for the LAN and communication means in the specific group.
More specifically, the configuration/means provided by the present invention is implemented in the form of a connection switch, server, and terminal device. These devices cooperate with each other to reflect the configuration/means of the present invention.
In this fashion, the present invention implements a private area network within the LAN that is configured by terminal devices (PCs and the like) used by specific members.
In other words, the present invention provides a method of separating the channel of the data traffic within a specific group from that of the general LAN traffic for the purpose of security.
At this time, a mechanism of preventing erroneous transfer of a data packet between different specific groups due to a communication error or the like is also necessary.
The present invention further provides means for performing communication between terminal devices of a specific group preferentially to LAN communication.
As for streaming communication between terminal devices of a specific group, the present invention provides means for performing an absolute priority process over general burst communication. Data steaming in a private area network within the LAN is implemented.
In this case, a control mechanism upon congestion between streaming signals is required.
To achieve the above objects, for example, a network switching apparatus according to the present invention has the following arrangement.
More specifically, a switching apparatus having a plurality of connection ports for connecting a plurality of terminal devices to a network, comprising:
A network is configured by connecting one or a plurality of switching apparatuses having this arrangement. This network can suppress leakage of information even if a device which communicates by using general address information is connected.
A preferred aspect of the present invention discloses, as a new communication method in the LAN, a communication technique of performing switching operation using a full-routing label.
Communication using the full-routing label will be called PAN (Private Area Network) communication hereinafter.
The PAN communication method is implemented by cooperating route management server means, a plurality of connection switching means, and a plurality of terminal device means.
The PAN communication method comprises
In correspondence with these sessions, the route management server comprises means for performing the first route management session and means for performing the second communication session.
The first route management session means comprises the first step of creating a full-routing label between connection switches, the second step of creating a full-routing label between terminal devices, the third step of creating a routing label table which lists the relationship between all full-routing labels, terminal devices, and connection switches, the fourth step of creating a label switch table from the routing label table and distributing the label switch table to each connection switch, and the fifth step of creating a destination label table from the routing label table and distributing the destination label table to each terminal device.
In the first step, each constituent device has the following constituent means or step.
The route management server comprises means for performing LAN communication, means for assigning full-routing labels to connection switches sequentially from a connection switch connected to the route management server, and means for communicating with the connection switches on the basis of the assigned full-routing labels.
Each connection switch comprises means for performing LAN communication, means for detecting another connection switch connected to the connection switch, and means for performing PAN communication with the route management server on the basis of the assigned full-routing label.
The full-routing label assigned by the route management server is different between routes, and the same label is not assigned to different routes.
In the second step, the route management server comprises means for instructing the connection switch by PAN communication to obtain connection information of connected terminal devices.
The connection switch comprises means for communicating with a connected terminal device by LAN communication and obtaining predetermined setting information, and means for notifying the route management server by PAN communication of the obtained connection information of the terminal device.
The terminal device comprises means for providing predetermined setting information by LAN communication to a connection switch connected to the terminal device.
The route management server comprises means for assigning a full-routing label to a terminal device on the basis of connection information of the terminal device to a connection switch, and means for notifying the connection switch by PAN communication of the full-routing label.
The connection switch comprises means for notifying the terminal device by LAN communication of the full-routing label.
The terminal device comprises means for performing PAN communication using the assigned full-routing label.
In the third step, the route management server comprises means for creating a routing label table which lists the relationship between all full-routing labels, terminal devices, and connection switches.
In the fourth step, the route management server comprises means for creating a label switch table for each connection switch from the routing label table, and means for exclusively distributing the label switch table of the connection switch to only a corresponding connection switch by the PAN communication.
In the fifth step, the route management server comprises means for creating a destination label table for each terminal device from the routing label table, and means for exclusively distributing the destination label table to only a corresponding terminal device by the PAN communication.
The second communication session is formed by the first state associated with communication setting in which whether PAN communication using the routing label is possible is confirmed and prepared, the second state in which actual communication operation using the routing label is performed, and the third state associated with the end of communication in which actual communication using the routing label ends.
In the first communication setting state, each constituent device has the following constituent means.
The terminal device comprises means for transmitting to a connection switch a communication request packet containing an identifier representing PAN communication, an identifier for identifying a specific group, and a routing label corresponding to a destination terminal device.
The connection switch comprises means for notifying the terminal device of communication permission under predetermined conditions.
In the second communication operation state, an originating terminal device comprises means for transmitting to a predetermined destination terminal device upon reception of the transmission permission response, a data packet containing an identifier representing PAN communication, an identifier for identifying a specific group, and a full-routing label within a predetermined specific group.
Each connection switch comprises means for outputting a packet to a predetermined output port on the basis of a predetermined routing label and transmitting the packet to the destination terminal device.
In the third communication end state, the originating terminal device comprises means for transmitting a transmission end packet containing an identifier representing PAN communication, an identifier for identifying a specific group, and a routing label corresponding to the destination terminal device during communication. The connection switch performs a communication end process.
In order to achieve cost reduction by reduction of an internal memory resource (holding a label table), the connection switch according to the present invention incorporates only small-scale cache memory means, and has means which is received from the route management server, as needed.
The route management server comprises flag means representing whether a corresponding label has been cached in a corresponding connection switch in a routing label table managed by the route management server, and means for, in confirming a destination label in the communication setting state, confirming the caching/non-caching flag, and when no label is cached, transmitting a corresponding routing label to the cache of the corresponding connection switch.
In the connection switch compatible to both PAN communication and LAN communication according to the present invention, erroneous switch control by a destination label communication error in the communication operation state is prevented, and the delay time in switch control is minimized. For these purposes, the frame format of communication data is formed by the first field containing the first identifier representing communication with a specific group, the second field containing the second identifier for identifying a specific group, the third field containing the third identifier for designating all switching routes from originating terminal devices to destination terminal devices within a predetermined specific group, and the fourth field containing a CRC error check function to the first, second, and third identifiers.
For a data packet having this structure, the connection switch comprises means for reading the first, second, third, and fourth fields in the data packet received at a predetermined port, means for confirming, on the basis of CRC information of the fourth field, whether no transmission error exists in pieces of first, second, and third field information, and means for determining PAN communication with a specific group on the basis of the first identifier of the first field when no error exists, performing a determination process of determining, on the basis of the second identifier of the second field, which of specific groups includes the connection switch, selecting a routing label table corresponding to the specific group on the basis of determination, and performing a predetermined switching process to a destination terminal device within the specific group in accordance with the selected routing label table on the basis of the third identifier of the third field.
The connection switch also comprises means for activating a retransmission process upon detection of a transmission error.
The series of operations of the connection switch are generally implemented by hardware means.
The connection switch is also characterized by selecting a corresponding table from a plurality of conversion tables (routing label tables) corresponding to a plurality of specific groups on the basis of the second identifier, and performing switch control using the third identifier on the basis of the selected table.
In order to realize compatibility with both PAN communication and LAN communication, the connection switch according to the present invention comprises the first switch control means associated with the LAN method, the second switch control means associated with the PAN method, and means for switching the first and second switching methods in accordance with a predetermined identifier.
The connection switch according to the present invention is further characterized by comprising means for, when a PAN packet from a specific group and a LAN packet from a local area network congest at the same output port of the connection switch, giving priority to a process of a data packet from the specific group on the basis of the first identifier representing communication with the specific group. In this case, even if a LAN packet is first processed, a subsequent PAN packet is preferentially processed.
Moreover, the connection switch comprises means for, when an isochronous PAN packet and general PAN packet congest at the same output port of the connection switch, preferentially processing the packet having isochronism identification information on the basis of an identifier representing the type of PAN packet. In this case, the connection switch comprises means for, even if a general PAN packet is first processed, processing a subsequent isochronous PAN packet with an absolute priority.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.
A communication method according to the embodiment will be explained.
This communication method is based on the principle of a label switch. The label switch is originally adopted as an MPLS (Multi Protocol Label Switch: standardized by IETF) in the trunk router of the Internet.
As the principle of the label switch, as shown in
In the example of
Assume that a terminal device within LAN 1 connected to port 1 of edge router 1 transmits a data packet to a terminal device at an IP address 1.1.1.16 that belongs to a forwarding equivalent class (FEC) 1.1.1.0/24 present in LAN 2. At this time, edge router 1 inserts label a1 into a data packet, and sends the data packet to port 3.
Core router 1 which has received the data packet refers to label a1, and outputs the data packet to port 6. At this time, the label is replaced (swapped) from a1 to b1. Core router 2 refers to label b1, converts the label from b1 to c1, and outputs the data packet to port 6. Edge router 2 refers to label c1, and outputs the data packet to port 4 connected to LAN 2. In output, the label is removed.
In general, the label is so assigned as to close within each router, and is swapped between routers. There is also a proposal for a global label which does not require any swapping between routers.
The MPLS groups transfer data packets in accordance with the FEC of layer 3, and assigns the same label to the data packet group corresponding to the FEC.
Forwarding of layer 2 by the trunk router is performed by referring to only the label.
The MPLS has a frame format as shown in
As shown in
The embodiment proposes a new communication method used within the local area network (LAN) of layer 2 on the basis of the label switch principle. By the new communication method, a specific group area network (Private Area Network: to be simply referred to as PAN hereinafter) is configured within the LAN.
More specifically, the PAN communication method is adopted as the second switching method in addition to address communication in a conventional LAN (to be referred to as a LAN communication method hereinafter), and the specific group area network PAN is configured within the LAN. Further, the embodiment makes various proposals for a “connection switch of layer 2” which copes with both the LAN method and PAN method and implements construction of the PAN within the LAN.
The PAN communication mechanism according to the embodiment will be described in detail.
The PAN communication method is formed by a management session for configuring and maintaining the PAN and a communication session of performing PAN communication.
That is, the PAN communication method is formed by a management session in which a PAN communicable environment is set and managed, and a communication session in which PAN communication is actually done between terminal devices.
The management session is a phase which constructs the PAN. More specifically, the management session starts when a manager in an office which requires construction of the PAN installs
The PAN-compatible communication I/F adaptor can take any form such as an internal card which is mounted into the PCI bus slot of a personal computer or an external adaptor which is connected to a USB interface.
A process which must be executed first by the manager, i.e., PAN administrator is a PAN initial setting session in the PAN management session. The PAN administrator activates a setting application functioning as a PAN server in the PAN server, and starts the PAN initial setting session. The user I/F of the initial setting session that is provided by the PAN server is used to set the PAN, i.e., a predetermined PAN ID and the PAN device IDs of all members (step 1 in
The PAN ID is formed by
The PAN type includes an ISO PAN which performs isochronous transmission, and a bulk PAN which processes confidential data but does not require isochronism. One of these PAN types is selected (the ISO PAN is higher in priority than the bulk PAN).
The PAN priority designates the priority process order when a plurality of PANs of the same type exist. The PAN identifier sets a unique number (the PAN server generates a predetermined warning so as not to contend with another PAN identifier).
As described above, a plurality of PAN IDs can be registered in one PAN server. When only one PAN ID is registered, the “PAN priority” is kept unchanged regardless of the input value. When “project X” is registered as a PAN name and the “PAN priority” upon setting another PAN (its name is “project Y”) coincides with the previously set PAN priority, as shown in
The ID of a PAN device (device such as a switch, PC, printer, or scanner belonging to the PAN) is formed by
The device type describes whether the device is a connection switch or terminal device, and for a terminal device, whether the terminal device is a printer, camera, or the like. Even data of the same isochronism can represent the priority of isochronism.
The terminal device priority represents the priorities of devices of the same type. The terminal device identifier sets a unique number (the PAN server generates a predetermined warning so as not to contend with another terminal device identifier within the same PAN).
The PAN ID and PAN device ID form a PAN member ID. This means that PAN members belong to different PANs even with the same PAN device ID as far as PAN IDs are different. The PAN device ID is uniquely defined. In short, when PAN IDs are different even with the same PAN device ID, PAN members are different.
As shown in
A PAN communication sequence will be explained with reference to
After PAN setting ends in the above way, the PAN administrator issues a predetermined instruction to the PAN server, and the PAN server (route management server) executes the initial setting session (step 2).
In the “initial setting session”, the PAN server assigns all devices (connection switches and terminal devices having PAN I/F adaptors) predetermined PAN device IDs which have already been set. The PAN server creates the connection tree of terminal devices for the PAN device IDs, presents the connection tree to the PAN administrator, and asks the PAN administrator to confirm it (step 3).
The PAN administrator confirms and decides the connection tree of terminal devices for the PAN device IDs, and issues a predetermined instruction to the PAN server (step 4).
The PAN server assigns labels to all routes from terminal devices to terminal devices on the basis of the instruction, creates a routing label table, and presents the routing label table to the PAN administrator (step 5).
The PAN administrator gives approval of whether the PAN configuration is OK (step 6).
If the PAN configuration is OK, the PAN administrator issues a routing label table distribution instruction to the PAN server (step 8).
Based on the instruction, the PAN server shifts to a “distribution session” in which the routing label table is distributed to connection switches and terminal devices (step 9).
Upon the completion of distributing the routing label table, the PAN server notifies the PAN administrator of the completion of distributing the routing label table. The PAN administrator determines whether to shift to the communication session (step 10).
If OK, the PAN administrator issues a communication session shift instruction to the PAN server (step 11).
The PAN server shifts to the “communication session” on the basis of the instruction, and notifies a predetermined connection switch of the start of the communication session (step 12).
If the routing label table is different from a desired configuration in step 6, or a PAN member is changed or added later (step 13), and the routing label table must be updated, the PAN administrator activates an “update session”, and instructs the PAN server to reconfigure the routing label table (step 7).
As a result, information which controls members belonging to the PAN is formed for the set/registered PAN ID in the PAN server, as shown in
By the operation of the above-described PAN management session, full-routing labels are assigned to all routes between terminal devices, as shown in
The operation of the “initial setting session” in which a label table for designating all routes is created will be explained in detail.
In
As will be explained to avoid misunderstanding, the PAN server according to the embodiment is a server for managing the route. A general file server, print server, and database server may be any of the terminal devices 38 to 40, 45, and 46 shown in
The connection switches 32 and 41 in
For easy understanding,
1. In
It should be noted that when the connection switch 32 (also the connection switch 41) in the embodiment receives a route setting request, it assumes that the PAN server which controls the PAN ID exists on the extension of a port number (information which specifies a port) at which the request has been received, and stores and saves the port number in a predetermined storage device so as to discriminate the connection switch 32 from other PAN members belonging to the PAN ID.
Subsequent communication between the PAN server 31 and the connection switch 32 can comply with the PAN communication method. PAN communication is routing communication, unlike LAN communication, and does not flood communication data under any condition.
2. The PAN server 31 requests the connection switch 32 to search for PAN member terminal devices by PAN communication (PAN Enum).
3. The connection switch 32 searches for terminal devices of the first layer directly connected to the connection switch 32 (terminal devices connected to the first connection switch) by LAN communication (detects devices by using a general MAC address and IP address), and lists only the terminal devices of predetermined PAN members (including port number information). The connection switch 32 also lists the connection switch 41 of the second layer connected to the connection switch 32. The connection switch 32 notifies the PAN server 31 by PAN communication of the list (including MAC address information of connected devices) of PAN member terminal devices of the first layer directly connected to the connection switch 32, and the list of the connection switch of the second layer.
4. By LAN communication, the PAN server 31 can obtain the MAC addresses of devices of the first layer directly connected to the connection switch 32. The connection switch 32 checks the MAC addresses (as described above, the MAC addresses of devices belonging to the PAN ID are set), and determines whether each device should be registered in the PAN ID. For terminal devices determined to be registered, the connection switch 32 sets the PAN ID and PAN device IDs. The PAN server 31 assigns labels (two labels for transmission and reception) for communication with each terminal device, and sends the labels (only for communication with the PAN server) to the terminal device NIC (network adaptor). The PAN server 31 disables LAN communication. Thereafter, the terminal devices of the first layer and the PAN server can communicate with each other via the PAN.
5. The PAN server 31 temporarily enables LAN communication, communicates with the connection switch 41 of the second layer via the LAN, and assigns the connection switch 41 predetermined management labels K3 and K4 for communication with the PAN server 31. K3 is a label used for communication from the PAN server 31 to the connection switch 41, and K4 is a label used for communication from the connection switch 41 to the PAN server 31.
6. The PAN server disables LAN communication. Thereafter, the connection switch 41 of the second layer and the PAN server 31 can communicate with each other via the PAN.
7. The PAN server requests the connection switch 41 of the second layer to search for PAN member terminal devices of the second layer directly connected to the device (connection switch 41) by PAN communication.
8. The connection switch 41 of the second layer searches for terminal devices of the second layer directly connected to the connection switch 41 by LAN communication (detects devices by using a general MAC address and IP address), and lists only predetermined PAN member terminal devices. The connection switch 41 notifies the PAN server 31 by PAN communication of the list of PAN member terminal devices of the second layer directly connected to the connection switch 41.
9. By LAN communication, the PAN server 31 sets a predetermined PAN ID and PAN device IDs for the PAN member terminal devices of the second layer directly connected to the connection switch 41. The PAN server 31 assigns labels (two labels for transmission and reception) for communication with each terminal device, and sends the labels (only for communication with the PAN server) to the terminal device NIC. The PAN server 31 disables LAN communication. The PAN server 31 notifies the connection switches 32 and 41 of the routing label tables of terminal devices. Thereafter, the terminal devices of the second layer and the PAN server can communicate with each other via the PAN.
10. The same operation continues until all PAN members are confirmed.
Upon the completion of confirming all members, the PAN server 31 obtains information on the connection routes of connection switches (for example, information representing that the PAN server is connected to port “4” of the connection switch 32 and port “5” of the connection switch 41 is connected to port “1” of the connection switch 32), and information representing a connection switch and its port to which a member device belonging to the PAN ID is connected. The PAN server 31 generates the tree of all routes on the basis of these pieces of information.
An example of the connection routing table created by the above-described “initial setting session” is shown in
The “distribution session” (step 9 in
1. The PAN server 31 reports the entire connection routing tables of predetermined PAN member terminal devices to the PAN administrator (step 5 in
The PAN server 31 assigns, without omission, unique identification IDs to the “PAN-compatible communication I/F adaptors” (Network Interface Adaptors/Cards: to be simply referred to as NICs hereinafter) of all predetermined PAN member terminal devices which have been approved. Also, the PAN server 31 generates the routing label tables of all the terminals without omission.
Each table in
2. The PAN server 31 distributes, to the PAN connection switches 32 and 41, routing label tables which define the switching method.
The update session will be described in more detail by exemplifying addition of a new member.
A LAN member which is permitted by the PAN administrator and newly participates in the PAN installs a predetermined NIC and predetermined driver software in the terminal device of the LAN member. Subsequently, the LAN member executes the following operation. If the newly registered terminal device is not a PC or the like but a scanner, printer, or the like which is connectable to the PAN from the beginning, no software need be installed.
1. The PAN administrator adds and sets the PAN device ID of the new member. At this time, the PAN administrator also registers the MAC address of a device serving as the new member.
2. The terminal device as the new member activates a predetermined PAN NIC setting mode. At this time, a PAN identifier to which the terminal device is to belong is also input. The new terminal device transmits a registration request by LAN communication.
3. It can be easily understood that the device transmits a registration request by LAN communication because the device has not been recognized as a PAN member yet. The request is transmitted using the DHCP (BOOTP protocol) on a general LAN. When the connection switches 32 and 41 in the embodiment also have an existing LAN function, an IP acquisition request in the LAN and a PAN member registration request in the PAN must be discriminated. For this purpose, when a 2-byte frame type in a received frame is 0x0800 representing general IP communication, the connection switch in the embodiment broadcasts the request to the DHCP server because this request aims at IP acquisition. When the frame type is 0x8847 (representing an MPLS packet), the connection switch determines that the request is sent from a device to be registered as a PAN member. In this case, the connection switch specifies a PAN server which controls the PAN ID stored in the switch, on the basis of a PAN identifier in the received registration request. The connection switch outputs the request to a port connected to the PAN server by PAN communication. For this reason, each connection switch (switching apparatus) stores a port connected to the PAN server which controls each PAN identifier.
4. The PAN server receives this notification, and presents it to the PAN administrator via a predetermined user I/F. When an input instruction representing that the device is approved is received from the PAN administrator (for example, an authentication button on the user interface is pressed), or the device is determined to have a MAC address permitted to be newly registered, the PAN server sets the PAN ID and PAN device ID of the terminal device by LAN communication. The PAN server assigns the terminal device (also including a newly registered device) a routing label for the PAN server, and distributes the routing label by LAN communication. The PAN server then disables LAN communication.
5. The PAN server updates the routing label tables of all terminals including the new member terminal device, and sends only the routing label table between each terminal device and other terminal devices to each terminal device by PAN communication. The PAN server also sends the routing label table of only each PAN connection switch to the switch present on the route by PAN communication. Of these settings, only settings associated with the new terminal device are desirably notified to reduce the communication amount. Consequently, the new terminal device can be registered as a PAN member and can perform PAN communication.
A method of implementing within the LAN a plurality of PANs which can be generated by PAN communication using the routing label will be explained.
The VLAN means a virtual LAN. The VLAN divides a company LAN which tends to be big into virtually (not physically but logically) small partitions (for, e.g., respective departments), and limits the broadcasting (flooding) range. For example, for a LAN in which 10,000 people participate, broadcasting (flooding) targets 10,000 people unless the LAN is divided into VLANs. This is the reason of setting the VLAN.
In
In
The VPAN means a virtual PAN, and represents that the PAN is virtually (not physically but logically) configured within the LAN.
In
Routing label tables for the configuration of
The above-described “management session” is summarized as follows.
1. The label is always set by the PAN server in a session different from the “communication session”. The label designates an entire route up to the end terminal (in the trunk system, the label closes within a switch and uses different values between switches. That is, the label is swapped between switches). The label is unique within one PAN and closes within the PAN. By grouping, a plurality of PANs can be configured.
2. The “setting session” includes the “initial setting session” of the PAN and the “update session” after construction.
3. The “distribution session” of the label follows the PAN initial setting session and PAN update session, and individual label tables are distributed to terminal devices and connection switches. After that, the session can shift to the “communication session” of the PAN.
The label in the embodiment is a mechanism given by only the PAN administrator, i.e., the management session of the PAN server. The security is maintained by generating and managing a label separately from the communication session. In other words, the terminal device itself cannot generate any label.
Communication between terminal devices within the PAN, i.e., the communication session will be described in detail.
When the PAN server activates the “communication session”, terminal devices can perform PAN communication. In the communication session, terminal devices and connection switches perform the following operation.
1. An originating terminal device assigns a label (in the trunk MPLS, an edge router assigns a label). Since the PAN is configured within the LAN, the originating terminal device dynamically selects PAN communication or LAN communication.
2. The connection switch identifies whether the data packet is a LAN data packet or PAN data packet, and selects a switching method. The connection switch performs general address communication in the LAN, and label switching in the PAN. Transmission by PAN communication is processed with an absolute priority to transmission by LAN communication, which realizes isochronous data transmission.
As an actual implementation, the embodiment discloses a label error check method, label table cache method, and the like.
3. Based on a held correspondence table, a destination terminal device confirms and authenticates the PAN ID and label value of the transmission source that are contained in the received data packet. If the PAN ID and label value coincide with those in the table, the destination terminal device receives the data packet.
As shown in
In the communication start state, whether the connection switch can start communication is determined in response to a PAN communication start request from the originating terminal device, and a communication permission response is sent back to the originating terminal device. At this time, a communication route corresponding to the full-routing label changes to a use-reserved state.
The connection switch determines whether to permit communication on the basis of the following criteria:
In the label communication state, a PAN communication packet from the originating terminal device is output to a predetermined port by label switching operation.
In the communication end state, the label communication state ends, and the use-reserved state of the communication route corresponding to the full-routing label is canceled.
In order to explain the communication session in more detail, the frame format of a PAN data packet used in the communication session will be described with reference to
In
Reference numeral 140 denotes a detailed content of the PAN member ID that is mainly formed by a PAN ID and PAN device ID.
Since switching operation is done on the basis of the routing label in PAN communication, the destination MAC address (DA) and originating MAC address (SA) fields can be used for various PAN identifiers. Note that “1” is set at the local bit of the MAC address so as not to adversely affect the MAC address (used for LAN communication) of a general Ether. Even if a packet flows through an existing LAN hub, the address is not interpreted as a global MAC address as far as the local bit is set.
Reference numeral 141 denotes the contents of the
Reference numeral 142 denotes the contents of the PAN device ID that is formed by
Reference numeral 143 denotes the contents of a field which contains a PAN/LAN communication identifier. In this case, 0x8847 is used as an identifier representing PAN communication. “0x8847” represents an MPLS packet, and means that a routing label follows.
Reference numeral 144 denotes a label format which is defined by the MPLS and used by the full-routing label in the embodiment.
Reference numeral 145 denotes a use method of the TTL area in the MPLS label format according to the present invention. A CRC is calculated using a destination PAN member ID, originating PAN member ID, type, label, EXP, and S, and the CRC value is so set as to achieve label switching earlier than FCS. SCS (Switch Check Sequence) implements high-speed label switching operation without any error.
Reference numeral 146 denotes a use method of the EXP area in the MPLS label format in the embodiment. The first one bit contains identification information (routing ID) representing whether the label is a PAN local label in order to establish matching with the edge router (
The remaining two bits in the EXP area are used for a communication sequence in the communication session. More specifically, these two bits represent four states:
The embodiment employs the label field so as to apply the MPLS method, but an original method can also be employed.
In
In
Reference numeral 128 denotes a destination PAN member ID; 129, an originating PAN member ID; 130, a PAN/LAN communication identifier; 131, a full-routing label; 132, attribute data used between terminal devices; and 133, a type field which defines the protocol of subsequent data. Reference numeral 134 denotes a data payload; and 135, a frame check sequence.
As shown in
In order to cope with the two methods, the LAN adaptor (NIC) in the embodiment has, e.g., a structure shown in
When the PAN member ID of a terminal device having this adaptor is decided, it is written in the register 252. The LAN frame and PAN frame can be switched at a desired timing by issuing a switching instruction to the switch 253 from the PC (accurately, the CPU of the PC).
The operation of the communication session will be described in detail with reference to
In
The connection switches 161 and 162 shift to the communication session in accordance with an instruction from the PAN server 164.
In the communication session, predetermined routing label tables have already been distributed to connection switches and PAN terminal devices. Routing label tables exist by the number of corresponding PANs.
The PAN terminal device 160 uses a LAN communication packet in
For the LAN packet, the MAC address of a destination terminal device in the DA (120 in
For the PAN packet, the destination PAN member ID formed by the PAN ID (141 in
The LAN communication packet and PAN communication packet from the PAN terminal device 160 are input to an input port 165 of the connection switch 161.
The connection switch 161 refers to the type field (122 or 130 in
When the type is 0x0800 representing a LAN communication packet, the connection switch 161 floods (broadcasts) the packet, and the flooding packet reaches the connection switch 162 via ports 166 and 167. The connection switch 162 similarly floods the packet, and the flooding packet reaches the LAN server 163.
When the LAN server responds to the packet, the MAC addresses of the terminal device and LAN server are registered in the MAC address tables (correspondence tables between ports and MAC addresses) of the connection switches 161 and 162, and LAN communication is executed. Details of the sequence of registration in the MAC address table has been described above, and a detailed description thereof will be omitted.
In this fashion, the terminal device 160 and LAN server 163 communicate with each other via the LAN.
When the type is 0x8847 representing a PAN communication packet, the connection switch 161 performs a PAN communication process on the basis of the PAN identifier (141 in
The communication session in PAN communication is formed by
These states correspond to the remaining two bits (146 in
In PAN communication, the first packet is a communication start request in the communication start state. As shown in
In
When a communication start request packet from an originating terminal device is received at the port 201 in
After the end of storage, the PAN header CRC reading unit 208 calculates a CRC and confirms whether the received packet data does not have any error (step S21 in
If the CRC has an error, the PAN routing label table selection/control unit 211 controls the response transmission unit 213 to send back a negative acknowledge containing retransmission request information to the originating terminal device (S22 in
If the CRC has no error, the PAN routing label table selection/control means 211 executes a predetermined process on the basis of the determination result of the PAN/LAN communication identifier reading unit 206.
That is, if the data packet is not a PAN communication packet, a process of, e.g., discarding the packet as a frame error is done (S24 in
If the data packet is a PAN communication packet, the PAN routing label table selection/control unit 211 selects a corresponding routing label table from a plurality of PAN routing label tables 212 on the basis of determination information of the PAN identifier reading unit 205 (S25 in
Whether label information read by the full-routing label reading unit 207 exists in the selected routing label table is determined (S26 in
If the label exists in the selected routing label table, the PAN routing label table selection/control unit 211 confirms whether a PAN packet is in use at any port on a route corresponding to the label (S28 in
When two connection switches exist, as shown in
More specifically, when the terminal device issues a PAN communication start request to the PAN server (164 in
The operation flow of the label communication state (2 in
Steps S40 to S45 in
In step S46, switch control is performed using the full-routing label. The PAN routing label table selection/control unit 211 controls the PAN absolute priority control unit 214 on the basis of label information from the full-routing label reading unit 207, and forcibly switches the switch control logic 215 to switch control based on the label. The switch core 216 outputs a PAN label communication packet to a predetermined port.
For example, when the full-routing label to the PAN server (164 in
Consequently, the PAN terminal device (160 in
A reply PAN packet from the PAN server (164 in
The operation of PAN absolute priority control will be explained in more detail.
The LAN terminal device 171 (see
1. When a PAN communication packet is input during output of a LAN communication packet to the port 166, the PAN communication packet quickly replaces the LAN communication packet and is output. At this time, the LAN packet is broken, but retransmission control is done by the TCP/IP protocol and no problem arises.
2. When a LAN communication packet is input during output of a PAN communication packet to the port 166, the LAN communication packet is queued and waits till the end of outputting the PAN communication packet.
In this manner, the PAN communication packet always undergoes the congestion process at each connection switch with an absolute priority over a LAN communication packet.
Congestion control between PAN communication packets will be explained.
The PAN terminal device 172 can communicate with the PAN server 164 via the PAN using a PAN communication packet (see
When the timing of a PAN communication packet output from the PAN terminal device 160 and that of a PAN communication packet output from the PAN terminal device 172 coincide with each other, congestion occurs at the link port 166 of the connection switch 161. In this case, the connection switch 161 performs the following output priority control.
Case in Which Congested PAN Communication Packets are of the Same Type (Isochronism or Bulk)
1. When a new PAN communication packet is input during output of another PAN communication packet to the port (166 in
2. Priority Process Method of PAN Communication Packet Registered in Busy Queue
A queue process may be done on the basis of, e.g., the following priority policy using the PAN type bit and PAN priority bit contained in the PAN ID, and the PAN device type bit and PAN terminal device priority bit contained in the PAN device ID (see
Case in Which Congested PAN Communication Packets are Isochronous Packet and Bulk Packet
An isochronous PAN communication packet undergoes a congestion process with an absolute priority to a bulk (general) PAN communication packet on the basis of isochronism identification information (contained in the PAN type). At this time, the bulk PAN communication packet is broken, but retransmission control can be done on an upper layer and no problem arises.
The operation flow of the communication end state will be explained (3 in
The operation of the communication end state is shown in
In step S66, communication reservation is canceled. The PAN routing label table selection/control unit 211 (see
In the above description, the connection tree of terminal devices is created for PAN device IDs in the “initial setting session”. Routing labels are distributed to connection switches and terminal devices in the “distribution session”. PAN communication is established in the “communication session”. Operation of setting a route between terminal devices upon detection of the start of communication, assigning a label, and starting PAN communication will be explained.
Processes up to creation of the connection tree of all routes in the connection example shown in
In assigning a label at the start of communication, no routing label is assigned immediately after creation of the connection tree, and the state after creation of the connection tree is kept unchanged.
This means that steps up to step 4 of
As for the connection routing table in
The states of the communication session from the start of communication of the first terminal device with the second terminal device from the above state to the end of communication will be explained with reference to
In “1. communication start state”, when the originating terminal device transmits a communication start request to the PAN server, the PAN server decides a route to the destination terminal device, and assigns a label.
This process is the same as label assignment in the initial setting session. In this case, a label is assigned to only a route through which the communication start request has been transmitted, whereas labels are assigned to all routes in the initial setting session.
As for the connection routing table in
In “2. label distribution state”, the PAN server notifies the originating terminal device, the destination terminal device, and all connection switches on the communication route of the assigned routing label.
Similar to the distribution session, the routing label is distributed to only the originating terminal device, destination terminal device, and connection switches on the route through which the communication start request has been transmitted, and is not distributed to another route.
By using the notified label, the originating terminal device and destination terminal device communicate with each other.
The “label communication state” is the same as the state in
In “4. communication end state” at the end of communication, when the originating terminal device transmits a communication end request to the PAN server, the PAN server sends back a communication end response to the originating terminal device. This process is the same as the state in
In “5. label discard state”, the PAN server notifies the originating terminal device, the destination terminal device, and all connection switches on the communication route to discard the confirmed label used.
At this time, the PAN server blanks the routing label column of the connection routing table in
The routing label column may be blanked upon reception of discard complication notifications from the originating terminal device, the destination terminal device, and all connection switches on the route, instead of a one-way notification from the PAN server.
This realizes effective use of the label, and after a label is discarded, no terminal device can communicate using the label. Even if the label is eavesdropped during communication, the network is not illicitly intruded after label discard, improving the security.
In this case, the destination terminal device serving as a communication start detection means transmits a communication start request. Alternatively, the originating terminal device may transmit a label request to the PAN server.
The “initial setting session” may execute processes up to label assignment without distributing any label.
This means that steps up to step 6 of
Also in this case, assigned labels are distributed to terminal devices and connection switches on the communication route at the start of communication.
In this example, the communication traffic for distributing labels in the “initial setting session” can be suppressed, but many labels must be prepared.
It has not been described that when a label is to be assigned, a label different from one assigned to another route is assigned.
For example, assuming a network configuration as shown in
More specifically, in assigning a label to route 1 between terminal A and terminal B, label 1 is assigned as a label commonly usable by node 1, node 2, node 3, and node 4. In searching for a label commonly usable by node 5, node 6, node 7, and node 8 on route 2 between terminal C and terminal D, the label is searched for independently of the label assigned to route 1. At this time, labels are searched for as a label usable on route 2 sequentially from smaller numbers. This general software method assigns label 1 to route 2, too.
However, the use of the same label on different routes may cause the following problem.
The network configuration in packet communication is generally designed in consideration of an alternate route upon occurrence of a fault. If the label is assigned in consideration of only the first set route, a packet may pass through nodes on another route assigned with the same label upon occurrence of a fault on the network.
If a fault occurs at node 7 on route 2 during communication using label 1 assigned to route 1 and route 2 in
Since node 3 has already used label 1, one of measures 1) and 2) must be adopted.
When a fault occurs at node 6 and node 7 on route 2, terminal C and terminal D can keep communicating with each other via route 22 of node 5→node 2→node 3→node 8. At this time, a new label must be assigned to communication route 22 because node 3 receives packets addressed to different destinations from the same port.
When a unique label is assigned to each route on the whole network,
For example, similar to the above case, the following operation is executed upon occurrence of a fault when terminal A and terminal B communicate with each other using label 1 on route 1 and terminal C and terminal D communicate with each other using label 2 on route 2.
On route 21 upon occurrence of a fault at node 7
Also, the transfer destination at node 8 does not change on route 22 upon occurrence of a fault at node 6 and node 7.
Hence, assignment of a unique label to each route on the whole network is significant.
According to the method of assigning a unique label to each route on the whole network, when labels are assigned to all routes on the whole network, they are sequentially assigned, as shown in
This method has already been utilized in various ways and is a known technique, and a detailed description thereof will be omitted.
The above-described operation is merely an example, and in some cases, only an operation necessary for the description has been explained. The embodiment is not limited to the above operation.
The illustrated configurations, label tables, flowcharts, formats, server windows, and the like are also merely examples, and the embodiment is not limited to the illustrated ones.
The terms used for the description are not limited to things meant by the terms, and include things which can be replaced with practical ones. For example, “terminal” may be “terminal” or “terminal+adaptor (including card)”.
As described above, the embodiment implements a PAN communication method having the following functions.
1. One-to-one virtual direct connection using a full-routing label can be achieved between a given specific terminal device and another specific terminal device.
2. Since no flooding (broadcasting) is done, address information such as a MAC address or IP address does not leak.
3. Terminal devices which need not communicate with each other are not assigned with any full-routing label, and cannot achieve communication connection.
4. The frame format of the Ethernet can be maintained, and the PAN method can coexist with the LAN method.
A specific group area network (PAN) configured by only specific terminal devices is implemented within the LAN on the basis of the new PAN communication method.
Requirements for the PAN are as follows.
As has been described above, the present invention can construct within the LAN a private area network (PAN) which is configured by terminal devices (personal computers and the like) of a specific group, is hardly influenced by the LAN traffic, and has high security.
Especially, no network peripheral device can perform advanced password check on the session layer. Even such device can securely transmit data by the PAN communication method.
The present invention can also implement channel separation between general LAN data and streaming data in the private area network within the LAN that is configured by specific multimedia terminal devices.
Streaming data can be supplied between terminal devices of a specific group without any influence of general LAN burst data.
Instead of performing creation and distribution of the full-routing label in the first session, a route from an originating terminal to a destination terminal is decided at the start of the communication session from the terminal device. A routing label is assigned to the set route, and the assigned routing label is distributed to the originating terminal, the destination terminal, and connection switches on the route. Thereafter, the communication shifts to PAN communication. At the end of the communication session, the use of the assigned routing label is stopped. This realizes effective use of the label within the private area network (PAN).
Also in assigning a label in each communication session, a label which is not identical to one that has already been assigned to another communication route and is in use is assigned. The routing label changes for each route, similar to creation and distribution of the full-routing label in the first session. When an alternate route is set to continue communication between terminal devices upon occurrence of a fault on one route in the private area network (PAN), the routing label in use can be kept used. Communication between terminal devices can continue by newly notifying only connection switches on the alternate route of a routing label.
As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.
Claim of Priority
This application claims priority from Japanese Patent Application Nos. 2003-289158 filed on Aug. 7, 2003 and 2004-178403 filed on Jun. 16, 2004, which are hereby incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-289158(PAT.) | Aug 2003 | JP | national |
| 2004-178403(PAT.) | Jun 2004 | JP | national |
