JPH07175739A - Network communication node - Google Patents

Abstract

PURPOSE:To easily change the address recognizing method in regard of a network communication node which can know or recognize the physical address of a scheduled destination of communication before the communication is carried out. CONSTITUTION:A network communication node 3 includes an application layer 4 and an operating system layer 5 as the software components. Then an address recognizing agent 9 is included in the layer 4 end therefore can be easily replaced with another agent 9 compared with a conventional case where the agent 9 is contained in the layer 5. For instance, the agent 9 has such a constitution that can select two types of address recognizing methods. Thus it is possible to immediately deal with change of the address recognizing method of a network 1 just by changing the selection of those address recognizing methods.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network communication node which performs a process of knowing a physical address of a node to be communicated with prior to execution of communication.

[0002]

2. Description of the Related Art When communicating between nodes connected to a network, it is common to use the physical address and logical address of each node. For example, in TCP / IP protocol communication using Ethernet, a 48-bit Ethernet address and a 32-bit Internet are used.
The address is used.

The physical address is an address unique to a node and is an address that can be read out within the node. The logical address is an address arbitrarily set in the network. Since the logical address is set arbitrarily, the same logical address may be given to different nodes. Therefore, it is necessary to manage by a correspondence table (address correspondence table) between the logical address and the physical address so as to prevent such a case. Figure 8
Shows an example of the address correspondence table.

When trying to communicate from one node A connected to the network to another node B, usually, the logical address of the node B is known, and the physical address is not. Therefore, it is necessary to know (recognize) the physical address corresponding to the logical address.
This is called "address recognition", and taking the correspondence of addresses as a result of recognition is called "Address Resolution".
tion).

As a method of recognizing an address, for example,
There is a method in which all nodes have an address correspondence table, and know by referring to it, an address server method, a broadcasting method, and the like. FIG. 2 is a diagram illustrating an address recognition method in network communication. In FIG. 2, 1 is a network, 2 is an address server, A, B,
C is a node. The address server 2 is a server that manages the correspondence relationship between the logical address and the physical address for all the nodes connected to the network 1. Specifically, the same address is managed so that it is not used twice. 2A shows a network to which the address server 2 is not connected, and FIG. 2B shows a network to which the address server 2 is connected.

The method (1) is carried out in a network in which the address server 2 is not installed as shown in FIG. 2A, but in the network in which address recognition is performed by this method, all nodes A, B, C Has an address correspondence table in which correspondence relationships between logical addresses and physical addresses of all nodes connected to the network 1 are recorded. Then, for example, node A is node B
When attempting to communicate with, the node A looks up the address correspondence table held by itself and finds a physical address using the logical address of the node B as a clue.

The method (1) has the drawbacks that as the scale of the network increases, the task of updating the address correspondence table when adding or disconnecting nodes becomes complicated and the amount of work becomes enormous.

The address server method of (2) is a method performed in the network 1 in which the address server 2 is installed, as shown in FIG. 2B, and when it is desired to know the physical address of the communication destination, the address server 2 Contact us to know. For example, when the node A wants to know the physical address of the node B, the address inquiry packet in which the logical address of the node B is written is sent to the address server 2. The address server 2 which received it checks the physical address of the node B from the address correspondence table, and notifies it by sending back the address notification packet in which it was written to the inquiring node A.

The broadcasting method (2) is performed in a network as shown in FIG. 2 (a) in which the address server 2 is not installed. In this method, an inquiry is made to all nodes, and the corresponding node replies. For example, when the node A wants to know the physical address of the node B, the address inquiry packet in which the logical address of the node B is written is broadcast to the network 1 (sent to all nodes without specifying the destination). All nodes receive it, but only the corresponding node B notifies it by sending back an address notification packet in which its own physical address is written to node A.

It should be noted that both the address server method and the broadcast method allow each node to hold an address correspondence table relating to some nodes with which it frequently communicates. When communicating with the node registered in the address correspondence table, it is not necessary to make an inquiry to the address server 2, so that the communication can be started immediately.

FIG. 3 is a diagram showing a software configuration of a conventional network communication node. In FIG.
1 is a network, 4 is an application layer, 5 is an operating system layer, 6 is a user application, 7 is an entry, 8 is a communication driver, and 9 is an address recognition agent. The entity of the entry 7 is a memory, and the information (eg, the head address) indicating the location of the location where the content to be transmitted is stored (location existing in another memory area) is written in the entry 7. The communication driver 8 determines, for example, a communication path and delivers and receives packets. Conventionally, the address recognition agent 9 is provided in the communication driver 8.

The address recognition agent 9 has an address recognition procedure and is a part that executes address recognition. As described above, the address correspondence table for some nodes may be provided. The address recognition procedure is for generating an address inquiry packet and transmitting it if there is a request for a physical address inquiry, or for extracting an answer content and reporting it to the user application 6 when an address notification packet is sent. This is a predetermined procedure. Therefore, the address recognition procedure differs depending on whether the address recognition is performed by the address server method or the broadcast method.

A request to communicate with which node is issued from the user application 6 in the application layer 4. The request is for operating system layer 5
The communication driver 8 written in the entry 7 of the above, and having received the notification, causes the address recognition agent 9 to start the operation.

For example, if the set address recognition agent 9 performs address recognition by the address server method, an address inquiry packet addressed to the address server is generated and sent. If the set address recognition agent 9 performs address recognition by the broadcast method, the address inquiry packet generated for the broadcast method is broadcast. The answered physical address is transmitted to the user application 6 via the entry 7.

[0015] As a conventional document relating to a node for network communication for address recognition, there are, for example, JP-A-2-227767, JP-A-3-237553, and "TC".
"P / IP network construction principle / protocol / architecture" (P40-46, "Chapter 5 Correspondence between Internet address and physical address (ARP)", "Inside
Apple Talk "(P2-3 to 2-12," Chapter 2 Apple T
alk Address Resolution Protocol ”).

[0016]

(Problems) However, the above-described conventional network communication node has the following problems. The first problem is that since the address recognition agent that executes address recognition is provided in the communication driver of the operating system layer, it is difficult to easily change the address recognition method of the node. is there.
The second problem is that only the address recognition agent that recognizes the address by a single method is set in the communication driver, so the address recognition method in the network to which the driver belongs is changed or the address recognition method is changed. However, if the connection is changed to a different network, it cannot be used as it is.

(Description of Problems) First, the first problem will be described. Although not shown in FIG. 3, the operating system layer is where software for basic operations is incorporated as its name suggests. Conventionally, the address recognition agent is provided in the communication driver therein. Was incorporated. Therefore, when changing the address recognition method, it is necessary to partially change the operating system layer, but it is generally troublesome to change it in the operating system layer, and it is not possible to change the address recognition method. It wasn't easy.

Next, the second problem will be described. Conventionally, the address recognition agent set in the communication driver is only for one address recognition method, such as the address server method for the address server method. Therefore, when the address recognition method in the network to which the user belongs has been changed, the address recognition agent suitable for the method cannot be used until it is reset. An object of the present invention is to solve the above problems.

[0019]

In order to solve the above problems, according to the present invention, in a network communication node having an application layer and an operating system layer as a software configuration, an address recognition agent is incorporated in the application layer. did.
Further, an address recognition agent incorporated in the application layer is provided with an address recognition procedure corresponding to each of a plurality of address recognition methods, a determination unit that determines the address recognition method of the network based on the received address notification packet, and a determination result of the determination unit. And a selection unit for selecting an address recognition procedure.

[0020]

[Operation] Since the address recognition agent is built in the application layer, it is easier to replace the address recognition agent and change it to another one compared to the conventional method that was built in the operating system layer. Like The reason for this is that if incorporated in the application layer, changes can be made as easily as exchanging user applications. Therefore, even if the address recognition method in the connected network is changed or the network is connected to another network having a different address recognition method, it is possible to easily deal with the change.

If an address recognition agent incorporated in the application layer is provided with a structure capable of supporting any of a plurality of address recognition methods by selection, when the network address recognition method is changed, Just select the one that suits you,
You can respond immediately.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an address recognition agent is
Build in the application layer, not the operating system layer. Since it is embedded in the application layer, it can be incorporated or deleted as easily as incorporating or deleting a normal user application. Therefore, even if the address recognition method in the currently connected network is changed or the connection is changed to another network having a different address recognition method, the address recognition agent can be easily changed.

The built-in address recognition agent may be compatible with only one type of address recognition method, such as compatible with only the address recognition method for the address server method, or for the address server method and the broadcast method. It may be possible to support two types of address recognition methods. When it is possible to support two types of address recognition methods, it is determined which of the address recognition methods is used in the connected network, and the one that is compatible with that is selected.

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a software configuration of a network communication node according to the present invention. Reference numerals correspond to those in FIG. 3, 9-1 is an address correspondence table, 9-
2 is an address recognition procedure for the address server method,
9-3 is a broadcast method address recognition procedure, 9-4 is a selection unit, 9-5 is a determination unit, 9-6 is a packet generation unit, 10 is an entry, and 11 is a kernel.
The kernel 11 is a core part of the operating system, and is a program that manages tasks, memory, and input / output. The address correspondence table 9-1 is an address correspondence table only for some nodes.

This example is an example in which two types of address recognition methods, one for the address server method and one for the broadcast method, can be supported. Therefore, the address server method address recognition procedure 9-2 and the broadcast method address recognition procedure 9-3 are prepared. As will be described later in detail, the determining unit 9-5 determines which method is used in the network 1, and the selecting unit 9-4 selects an address recognition procedure that matches the determination result.

The operation is performed in the order of 1 to 3 shown in FIG. The operation is an operation in which the address recognition agent 9 requests the kernel 11 to register or delete the address recognition procedure held by itself in the entry 10. Operation of kernel 11 is an operation of actually registering or deleting in the entry 10.

Specifically, the head addresses of the address server method address recognition procedure 9-2 and the broadcast method address recognition procedure 9-3 written in the memory of the application layer 4 are registered in the entry 10. , It will be erased. Normal,
Entry 1 automatically when node 3 is started
Registered as 0. And it is erased if necessary. Address recognition is started when another user application 6 in the application layer 4 makes a request (communication operation) to some node to communicate.
Next, the operation thereafter will be described.

FIG. 4 is a flow chart for explaining the address recognition operation in the network communication node of the present invention. Step 1 ... When the user application 6 needs to communicate with another node, it indicates the logical address of the node to be communicated with and issues a request (address recognition request) to know the physical address corresponding to this. The request is
It is transmitted to the communication driver 8 via the entry 7 (operation thereof).

Step 2 ... The communication driver 8 calls (the operation of) the address recognition procedure which is set at that time. It is possible that none of them is set, but in that case, the broadcast method address recognition procedure 9-3 is called (defined in this way). The following operation is performed according to the procedure of the called address recognition procedure. First, referring to the address correspondence table 9-1 held by itself, it is checked whether or not the physical address corresponding to the logical address is registered therein.

Step 3 ... If registered, the physical address is obtained from the address correspondence table. Step 4 ... When ending the address recognition operation, the end code to be sent to the user application 6 is set to a code meaning "success" in the address recognition. Step 5 ... If it is not registered in the address correspondence table 9-1, it is checked whether the address recognition method of this node 3 is decided. This can be known by examining the state of the selection unit 9-4.

Step 6 ... If none of the above is determined, an address inquiry packet is generated by the broadcast method. In step 2, if no address recognition method is set, the broadcast method address recognition procedure 9-3 is called, so the address inquiry packet is also generated by the broadcast method. . The packet is generated by the packet generator 9-6.

Step 7 ... Requests the communication driver 8 to send the generated address inquiry packet to the network 1 and continue receiving for a certain period of time after the sending (operation). The reason for limiting the reception time is that if the user waits forever, it cannot proceed to the next processing. The receive duration is limited to the amount of time normally required for another node to send back a reply packet.

Steps 8-10 ... These steps are
This is address notification packet reception processing H. This process
The content of the address notification packet, which is a reply from another node or the address server, is sent when the communication driver 8 sends it to the address recognition agent 9 (operation thereof). Details of the processing here will be described with reference to FIG. 7.

FIG. 7 is a diagram showing an address notification packet reception process when the address recognition method is not set in the address recognition agent. The address recognition method setting process includes a process of checking where the received address notification packet is sent and a process of setting the address recognition method based on the result of the check. There are four cases according to the source of the address notification packet.

(First case) The address notification packet is
When sent from both the node to be communicated with and the address server. Address recognition method setting process ... Since the address notification packet is sent from the address server, it is determined that the address server method is adopted as the address recognition method in this network. This determination is made by the determination unit 9-5. Since such a determination is made, the selecting unit 9-4 sets the address recognition method by selecting the address recognition method 9-2 for the address server method as the address recognition procedure of the node 3.

Address Correspondence Table Processing ... Next, address correspondence table processing is performed as to whether or not the replied physical address is registered in the address correspondence table 9-1. It was sent 2
When the physical addresses, which are the reply contents of the one address inquiry packet, match, the reply is recognized as correct, so that it is registered in the address correspondence table 9-1 for later communication. If they do not match, it is unclear which answer is correct, so do not register.

End code setting ... Finally, the end code is set. When the two reply physical addresses match, the address recognition is set to "success". When they do not match, it is not possible to know which physical address is correct, so the code "Address management information failure" is set.

(Second case) The address notification packet is
When sent only from the address server. Address recognition method setting process ... Since the address notification packet is sent from the address server, it is determined that the address server method is adopted as the address recognition method in this network. Therefore, the address recognition method of the node 3 is set by selecting the address recognition method 9-2 for the address server method.

Since the address notification packet has not been sent from the node to which the communication is scheduled, the node is in a state where communication is impossible such as the power being off. Is judged.

Address correspondence table processing: The physical address returned in the address notification packet is the address server 2
If the address (eg, broadcast address) indicates that it is not registered in the address correspondence table of
The address is not registered in the address correspondence table 9-1 of the node 3. On the other hand, if the replied physical address is other than the above-mentioned address, the physical address is registered in the address correspondence table of the address server 2 and is a correct physical address.
It is also registered in the address correspondence table 9-1.

End code setting: When the address is not registered in the address correspondence table of the address server 2, a code "address not registered" is set. When I was registered,
Set the code of "communication with other party".

(Third case) The address notification packet is
When it is sent only from the node to which communication is scheduled. Address recognition method setting process ... Since there is no address notification packet from the address server, and only the address notification packet from the node to be communicated with is received, it is determined that the address recognition method is the broadcast method. Then, as the address recognition procedure of the node 3, the address recognition procedure for broadcast method 9-3 is selected to set the address recognition method.

However, in this case, the following two cases can be considered. The first is the case where the broadcast method is really adopted and therefore there is no address notification packet from the address server. The second is the case where the address server method is actually used, but the address server is in a state of being unable to send an address notification packet because the address server has fallen into some sort of failure. In the second case,
It is not correct that the judgment unit 9-5 makes the judgment of the broadcast method from the viewpoint of whether the judgment itself is correct, but it is necessary to change to the broadcast method when the address server is out of order. Therefore, it is a correct judgment from the viewpoint of whether or not the judgment is useful for dealing with the following.

Address Correspondence Table Processing: The replied physical address is registered in the address correspondence table 9-1 of the node 3. Set the end code ... Set the code that the address recognition was "successful".

(Fourth case) When the address notification packet is not sent from anywhere. Address recognition method setting process: There is no clue to determine the address recognition method. Since it cannot be determined, the address recognition method is not set either. That is, the selection unit 9-4 in FIG.
Is an address recognition procedure 9 for the address server method
-2, None of the broadcast method address recognition procedures 9-3 is selected.

Address correspondence table processing: Since there is no reply for the physical address, the address correspondence table 9-1 for the node 3
I can't register for. Exit code setting: Set the code "There is an unexplained communication failure".

Step 11 ... When the address recognition method for the node 3 is determined (that is, when the address recognition procedure 9-2 for the address server method or the address recognition procedure 9-3 for the broadcast method is selected in FIG. 1) ), And generate an address inquiry packet according to the method. Different methods use different packet destinations.

Step 12 ... Requests the communication driver 8 to send the generated address inquiry packet to the network 1 and continue receiving for a fixed time after the sending (operation). The reason for limiting the reception time is the same as that described in step 7. Steps 13 to 15 ... These steps are the address notification packet reception process H. The content of the address notification packet, which is a reply from another node or the address server, is sent when the communication driver 8 sends it to the address recognition agent 9 (operation thereof).

The processing contents differ depending on whether the currently set address recognition method is the address server method or the broadcast method. The details of the processing when the address server method is set will be described with reference to FIG. 5, and the details of the processing when the broadcast method is set will be described.
This will be described with reference to FIG.

FIG. 5 is a diagram showing an address notification packet reception process when the address server method is set in the address recognition agent. There are two possible cases for this processing.

(First case) The address notification packet is
When sent only from the address server 2. Address recognition method setting process ... Since the address notification packet is sent from the address server, it is determined that the address server method is adopted as the address recognition method in this network. Therefore, the address server method should be set as the address recognition method, but since the method has already been set, the setting need not be changed.

Address correspondence table processing: When the returned physical address is an address (eg, broadcast address) indicating that it has not been registered in the address correspondence table of the address server 2, the physical address of the communication destination is planned. Since it is unknown, it is not registered in the address correspondence table 9-1 of the node 3. When a physical address other than the above address is replied, it is the physical address of the scheduled communication destination registered in the address correspondence table of the address server 2, and is registered in the address correspondence table 9-1.

End code setting: When the physical address of the node to be communicated is not registered in the address correspondence table of the address server 2, a code of "address not registered" is set. When registered in the address correspondence table of the address server 2, the address recognition sets a code of “success”.

(Second case) When the address notification packet is not sent from anywhere. Address recognition method setting process ... Since it was not sent from the address server, it cannot be determined that it is the address server method. Since it was not sent from the node to be communicated with, it cannot be determined that the method is the broadcast method. Since neither can be determined, the currently set address server method is canceled. Address correspondence table processing: Since the physical address is not answered, there is no way to register it in the address correspondence table 9-1. In the second case, it is necessary to return to the blank state and then perform the processing from step 5 again. Since the setting of the address recognition method has been canceled, when reprocessing, the process proceeds from step 5 to step 6.

FIG. 6 is a diagram showing an address notification packet reception process when the broadcast method is set in the address recognition agent. This process has 4
There are two possible cases.

(First case) The address notification packet is
When sent from both the node to be communicated with and the address server. Address recognition method setting process ... Since the address notification packet is sent from the address server, it is determined that the address server method is adopted as the address recognition method in this network. Therefore, the selection unit 9
-4, the address recognition method is set by selecting the address recognition procedure 9-2 for the address server method as the address recognition procedure of the node 3.

Address Correspondence Table Processing: When the physical addresses that are the reply contents of the two sent address inquiry packets match, the reply is recognized as correct, so the address correspondence table 9-1 of the node 3 Register with. If they do not match, it is unclear which answer is correct, so do not register.

End code setting: When the two physical addresses that have been returned are in agreement, the address recognition is set to "success". In case of disagreement,
Set the code "Address management information failure".

(Second case) The address notification packet is
When sent only from the address server. Address recognition method setting process ... Since the address notification packet is sent from the address server, it is determined that the address server method is adopted as the address recognition method in this network. Therefore, the address recognition procedure for the address server method 9-2 is selected as the address recognition procedure for the node 3, and the address recognition method is set to the address server method.

Since the address notification packet has not been sent from the node to which the communication is scheduled, the node is in a state where communication is impossible such as the power being off. Is judged.

Address correspondence table process: The physical address returned in the address notification packet is the address server 2
If the address (eg, broadcast address) indicates that it is not registered in the address correspondence table of
The address is not registered in the address correspondence table 9-1 of the node 3. On the other hand, if the replied physical address is other than the above-mentioned address, the physical address is registered in the address correspondence table of the address server 2 and is a correct physical address.
It is also registered in the address correspondence table 9-1.

Setting of end code ... When the address is not registered in the address correspondence table of the address server 2, a code of "address not registered" is set. When I was registered,
Set the code of "communication with other party".

(Third case) The address notification packet is
When it is sent only from the node to which communication is scheduled. Address recognition method setting process ... Since there is no address notification packet from the address server, and only the address notification packet from the node to be communicated with is received, the address recognition method is not the address server method.
The broadcast method is determined. Since the broadcast method is currently set as the address recognition method of the node 3, it is not changed.

Address Correspondence Table Processing ... The responded physical address is registered in the address correspondence table 9-1 of the node 3. Set the end code ... Set the code that the address recognition was "successful".

(Fourth case) When no address notification packet is sent from anywhere. Address recognition method setting process: There is no clue to determine the address recognition method. Since it cannot be determined, the address recognition method is left as it is. Address correspondence table process: Since there is no reply about the physical address, there is no way to register it in the address correspondence table 9-1 of the node 3. Exit code setting: Set the code "There is an unexplained communication failure".

Step 16 ... It is determined whether or not the reprocessing from Step 5 is necessary. "Second case" in FIG.
Would require reprocessing. When the process returns to step 5 for reprocessing, the process goes to step 5 NO. Step 17 ... The address recognition result is notified from the address recognition agent 9 to the communication driver 8 (operation thereof). The communication driver 8 notifies the user application 6 of the result of communication (operation thereof).

As in this example, the address recognition agent 9 incorporated in the application layer 4 is selected by the selection unit 9-4.
If the address server method and the broadcast method are supported by the selection in step 1, even if the address server fails in the network of the address server method, it is possible to immediately switch to the broadcast method and continue the communication.

That is, if the address server fails, no address notification packet is sent from the address server, so the address recognition agent 9 of each node cancels the address server method (the second case in FIG. 5). ) Reprocessing (step 16 → step 5 → in FIG. 4)
In steps 6 to 10), the address recognition method is reset to the broadcast method (the third case in FIG. 7). Since communication can be continued in this way, the node becomes extremely resistant to failure (good in failure resistance).

The example of FIG. 1 is an example in which the address recognition agent 9 incorporated in the application layer 4 is adapted to a plurality of address recognition methods.
Of course, as the address recognition agent 9, one corresponding to one address recognition method (for example, only the address server method) can be incorporated. In that case, the address recognition agent does not need to have a determination unit and a selection unit.

If, for example, an address recognition agent compatible with the address server method is incorporated, the address recognition agent 9 is replaced with one compatible with the broadcasting method when connecting to the network of the broadcasting method. Since the address recognition agent in the application layer can be easily exchanged with the user application, it can be easily exchanged as compared to the conventional node incorporated in the operating system layer.

[0071]

As described above, according to the network communication node of the present invention, since the address recognition agent is incorporated in the application layer, the address recognition agent is replaced as compared with the conventional one which is incorporated in the operating system layer. Then, you can easily change to another one. Therefore, even when the address recognition method in the connected network is changed or the network is connected to another network having a different address recognition method, the change can be easily dealt with.

If an address recognition agent incorporated in the application layer is provided with a configuration capable of supporting any of a plurality of address recognition methods, if the network address recognition method is changed, the address recognition agent can be changed. Just select the one that suits you,
You can respond immediately. Also, the obstacle resistance is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a software configuration of a network communication node according to the present invention.

FIG. 2 is a diagram illustrating an address recognition method in network communication.

FIG. 3 is a diagram showing a software configuration of a conventional network communication node.

FIG. 4 is a flowchart illustrating an address recognition operation in the network communication node of the present invention.

FIG. 5 is a diagram showing an address notification packet reception process when an address server method is set in the address recognition agent.

FIG. 6 is a diagram showing an address notification packet reception process when a broadcast method is set in the address recognition agent.

FIG. 7 is a diagram showing an address notification packet receiving process when the address recognition method is not set in the address recognition agent.

FIG. 8 is a diagram showing an address correspondence table.

[Explanation of symbols]

1 ... network, 2 ... address server, 3 ... node,
4 ... Application layer, 5 ... Operating system layer, 6 ... User application, 7 ... Entry, 8
... communication driver, 9 ... address recognition agent, 9-
1 ... Address correspondence table, 9-2 ... Address server method address recognition procedure, 9-3 ... Broadcast method address recognition procedure, 9-4 ... Selection unit, 9-
5 ... Judgment unit, 9-6 ... Packet generation unit, 10 ... Entry, 11 ... Kernel

Claims (2)

[Claims] 1. A network communication node comprising an application layer and an operating system layer as a software configuration, wherein an address recognition agent is incorporated in the application layer. 2. An address recognition agent incorporated in an application layer, an address recognition procedure corresponding to each of a plurality of address recognition methods, a judgment unit for judging a network address recognition method from a received address notification packet, and the judgment unit. 2. The network communication node according to claim 1, further comprising: a selection unit that selects an address recognition procedure according to the result of the determination.