JPH07336409A - Connection control system/method - Google Patents

Abstract

PURPOSE:To provide an effective connection control system/method which can omit its waiting state by settling the connection different from the connection that was settled before the restart of communication when it is restarted. CONSTITUTION:In the present connecting operation state, an 'unused' terminal identifier of its own station is acquired from a connection record table (S1). Then it is decided whether the terminal identifier was used or not in the precedent connecting operation state (S2). If the identifier was not used, the identifier is 'used' as the terminal identifier of its own station (S3). If the identifier was used, it is decided whether the maximum existence period of a segment is passed or not from the disconnection time (S4). If so, the step shifts to S3. If not, another 'unused' terminal identifier of its own station is acquired (S5). Then the step shifts to S2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection control method and a connection control method for establishing a connection when computers communicate with each other via a network.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a system for performing communication between computers via a network. In the figure, computers 1a, 1b, 1c, 1d, 1e, 1f are the source and destination of messages, and are connected to the networks 2a, 2b, 2c, 2d, 2e, 2f, respectively. The gateways 3a, 3b, 3c, 3d, 3e are used for exchanging messages between networks, and general-purpose computers are generally used.

When the protocol used for each network is different, protocol conversion is performed when sending and receiving a message. Therefore, it takes time for the message to pass through the gateway. The gateway 3a is connected to the networks 2a, 2c, 2d, 2e, and the gateway 3b
Is connected to networks 2b and 2c, gateway 3c is connected to networks 2b, 2c and 2e, gateway 3d is connected to networks 2a, 2c and 2f, and gateway 3e is connected to networks 2d and 2e. Network 2a, 2b, 2
The computers c, 2d, 2e, 2f connect computers (not shown) in addition to the computers 1a, 1b, 1c, 1d, 1e, 1f, respectively, to form a local network. Then, a network number for identification is added.

Next, the operation will be described. Computer
When 1a sends a message to the computer 1b, it determines which of the gateways 3a, 3d of the network 2a to send. For example, if it decides to send to the gateway 3a, it sends a message to the network 2a to send to the gateway 3a. The gateway 3a looks at the destination of the received message, considers the operating status of other networks and other gateways, and the distance to the destination,
Decide to which of the gateways 3b and 3c as the route to send. For example, if it decides to send to gateway 3b, it sends a message to network 2c to send to gateway 3b. The gateway 3b recognizes that the destination is the computer 1b connected to the network 2b and sends a message to the computer 1b. Other computers can send messages as well.

FIG. 6 is an explanatory view for explaining a situation in which data transfer in the transport layer of the OSI reference model modeled as a standard of a communication system is realized in the system shown in FIG. In the figure, 4a (or 4b) is a unit for executing a process of transferring data by an application program on the computer 1a (or 1b). TCP
The module 5a (or 5b) is an executing entity that establishes a logical connection connecting both processes 4a and 4b and enables communication.

The process 4a on the computer 1a which transfers data requests the TCP module 5a to establish a logical connection with the process 4b on the computer 1b of the partner station. When the connection is established, the process 4a indicates the location of the transmission data buffer 9a in which the data to be transmitted is stored, and requests the TCP module 5a to transfer the data. The TCP module 5a divides the transmission data in the buffer into transmission units to form a data section 82,
A set of control codes for controlling data transfer is formed as a header part 81, and both parts 81 and 82 are packaged to form a segment 8.

The control code includes a sequence number indicating the sequence in which the divided messages should be transmitted, and the TCP module 5a sets the segments 8 in the order of the transmission numbers to the computer 1b of the partner station.
Transfer to TCP module 5b above. Upon receiving the segment 8, the TCP module 5b looks into the header portion 81 of the segment 8 and collects the data portion 82 to form the received data.
The data is stored in the reception data buffer 9b prepared by 4b, and the process 4b is notified that the data reception is completed.
If the transfer service is stopped while data is being transferred by the established connection, the connection is blocked and other stations are prohibited from using the connection.

FIG. 7 is an explanatory diagram showing a conventional procedure for establishing a logical connection for both processes 4a and 4b in FIG. In the figure, the arrow indicates the direction from the active side to the passive side of the program executed to establish the connection, and the numbers in parentheses attached to the arrow indicate the order of establishing the connection. The logical connection 6 is a communication path in the transport layer that connects the processes 4a and 4b, and the computer 1a (or 1b)
The end on the side is port 6a (or 6b). Both ports
A termination identifier is assigned to each of 6a and 6b as a port number for identifying the logical connection 6. The TCP modules 5a and 5b are the same as the TCP modules 5a and 5b in FIG. OS 7a (or 7b) is the OS of computer 1a (or 1b), port 6a (or 6b) and process 4a
(Or 4b) is uniquely associated with. Next, a procedure for establishing the logical connection 6 will be described.

(1) First, the process 4b on the computer 1b
Requests the OS 7b to allocate port 6b in order to accept the request for establishing the connection from the process 4a on the computer 1a. (2) The OS 7b assigns the termination identifier (denoted as "100") of the port 6b to the process 4b so as not to duplicate the port used at the time of request. And TCP
Instructs module 5b to prepare to establish a logical connection. (3) If the terminal identifier "100" of the assigned port 6b is
OS 7b notifies process 4b. The process 4b waits for a request to establish a logical connection. The termination identifier "100" of the port 6b is widely known to other processes. (4) Process 4a on computer 1a is computer 1b
Request OS 7a to establish a logical connection to the terminal identifier "100" of port 6b above. (5) The OS 7a allocates the terminating identifier of the free port 6a (assumed to be "200") to the process 4a, and the port 6b on the computer 1b designated for the TCP module 5a.
Command to establish a logical connection to the terminal identifier "100" of the. (6) The TCP module 5a sends a request message for establishing the logical connection 6 by designating the termination identifiers "200" and "100" to the TCP module 5b. (7) Upon receiving the message, TCP module 5b investigates whether the specified termination identifier "100" is assigned, and if it is assigned, it uses port 6b.
Notify that there was a request to establish a logical connection to the. (8) This notification is transmitted to process 4b via OS 7b. (9) Process 4b determines whether or not to accept the request, and if yes, notifies OS 7b of the acceptance. (10) OS 7b notifies TCP module 5b of acceptance. (11) The TCP module 5b sends an acceptance message to the TCP module 5a. (12) The TCP module 5a sends an acceptance message to the port 6a. (13) This acceptance message is processed via OS 7a.
4a is transmitted, and the logical connection 6 is established. This is the connect operation.

As described above, in the conventional connect operation, the terminal identifier of the port 6a (or 6b) is locally managed by the computer 1a (or 1b), and the process 4a (or
OS 7a (or 7b) assigns the terminal identifier to 4b). Then, disconnection of the logical connection 6, that is, disconnection operation is also performed in accordance with the connection operation.

[0011]

Since the conventional connection control system is constructed as described above, when the same logical connection 6 is repeatedly established and disconnected, that is, both ports 6a, When the same termination identifier is repeatedly used as the port number of 6b, the sequence number of the segment used in the disconnected logical connection and the sequence number of the segment used in the newly established logical connection do not overlap. Is desirable.
This is because when the segment transferred by the released connection is floating around the network and alive, and the connection arrives at the receiving side after the connection is released and is newly opened, it is used as the identification number of the segment. This is because when the sequence numbers are the same, the receiving side cannot distinguish them. The maximum time during which the segment remains in the network thereafter is called the maximum time to live.

Therefore, when the abnormality of the logical connection is confirmed or the logical connection is blocked and the connect operation is performed to reestablish the logical connection, the maximum survival of the segment is confirmed from the time when the abnormality (or the block) is confirmed. Waiting for a connect operation until time has passed. Further, when the connection operation is waited for, the transmission data is lost if the storage capacity of the transmission data buffer of the computer is small.

The present invention solves such a problem, and when continuing to communicate with the same partner station, by establishing a logical connection different from the previous one, there is no waiting and a connection control method and connection control with good transfer efficiency are provided. The purpose is to provide a method.

[0014]

The connection control system according to the first invention is a connection control system for establishing a logical connection for communication between computers and for disconnecting the logical connection after the communication is completed. Then, based on the storage means for storing the connection control information for performing the control for establishing the logical connection and the contents stored in the storage means, the partner station of this communication is the same as the partner station of the previous communication. If the first determination means for determining whether or not the first determination means is the same, it is determined whether or not a predetermined time has elapsed from the time of disconnecting the logical connection in the previous communication. If the judging means and the second judging means judge no, a logical connection that is logically different from the logical connection in the previous communication is established. Characterized by comprising a connection establishment unit that.

The connection control system according to the second invention is
A setting for storing the identifier for identifying the logical connection by the storage means and the disconnection time when the logical connection is disconnected as the connection control information, and setting the content stored in the storage means to a predetermined value after the computer is turned on. It is characterized by having means.

The connection control method according to the third invention is
A connection control method for establishing a logical connection for communication between computers and for disconnecting the logical connection after the communication is completed. The connection control information for controlling the establishment of the logical connection is stored. , Based on the stored connection control information, it is determined whether the partner station of this communication is the same as the partner station of the previous communication. If the result is the same, the logical connection in the previous communication is disconnected. It is characterized in that it is determined whether or not a predetermined time has elapsed from the time, and if the determined result is no, a logical connection that is logically different from the logical connection in the previous communication is established.

A connection control method according to the fourth invention is
An identifier for identifying a logical connection and a disconnection time when the logical connection is disconnected are stored as the connection control information, and after the power of the computer is turned on, the content stored as the connection information is set to a predetermined value. .

[0018]

In the first invention or the third invention, connection control information for performing control for establishing a logical connection is stored, and the partner station of this communication is the partner station of the previous communication based on the stored connection control information. If the results are the same, it is determined whether a predetermined time has passed from the time when the logical connection in the previous communication was disconnected, and the result is If, then a logical connection that is logically different from the logical connection in the previous communication is established, and waiting is not necessary when establishing the logical connection.

In the second invention or the fourth invention, in the first invention or the third invention, the identifier for identifying the logical connection and the disconnection time when the logical connection is disconnected are stored as the connection control information, and the power of the computer is turned on. After the input, the content stored as the connection information is set to a predetermined value.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments thereof. Figure 1 shows the case of performing inter-computer communication in the transport layer of the OSI reference model.
It is explanatory drawing which shows the procedure of establishing a logical connection. In the figure, the arrow indicates the direction from the active side to the passive side of the program executed to establish the connection, and the numbers in parentheses attached to the arrow indicate the order of establishing the connection.

The computer 1a (or 1b) is the computer 1b (or 1a) of the partner station via a network (not shown).
Transfer data to. Process 4a (or 4b) is the unit in which the application program on computer 1a (or 1b) executes the process of transferring data, and TCP module 5a (or 5b) is the logical connection 61 (or 6).
It is the executing entity that establishes 2) and enables communication. The logical connection 61 (or 62) is a communication path in the transport layer that connects the processes 4a and 4b.

The terminal of the logical connection 61 on the computer 1a (or 1b) side is the port 61a (or 6b).
When communication is restarted after the established logical connection 61 is disconnected, the logical connection 62 is established between both processes 4a and 4b. The end of the logical connection 62 on the computer 1a (or 1b) side is the port 62a (or 6b)
Is. Connection control module 60a is port 61a
(Or 62a) is the executing entity that determines the termination identifier as the port number, and the connection control module 60b is the port
It is the executing entity that determines the termination identifier as the port number of 6b.

Then, the connection control module 60a (or 60b) uses a logical connection to manage each port.
Information about the connect operation for establishing 61 (or 62) or the disconnect operation for disconnecting the logical connection 61 (or 62) is recorded as one record per connection in a connection recording table (not shown), and clocks are counted to measure the time. It is equipped with a timer that does.
The OS 7a (or 7b) uses process 4a (or 4b), TCP module 5a (or 5b) and connection control module 60.
A (or 60b) is integrated to transfer data.

FIG. 2 is a record format of a record recorded in the connection recording table by the connection control module 60a in FIG. In the figure, 63 is an item indicating the port number of the port 62a of the own station, which acts as a termination identifier of the own station for identifying the logical connection 62. When establishing a logical connection 62 using this local station termination identifier 63, set "1" in the item of the local station termination identifier flag 64 to display "use",
When disconnecting the logical connection 62, "unused" is displayed as a bit "0" in the item of the flag 64 for local station termination identifier. This display is performed by the connection control module 60a.

The partner station termination identifier 65 is an item indicating the port number of the partner station port 6b, and is a logical connection 62.
Acts as a termination identifier of the partner station for identifying the.
The own station address 66 is an item indicating the address of the computer 1a as the data transfer source, and the partner station address 67 is an item indicating the address of the computer 1b as the data destination, both of which are from the process 4a to the connection control module 60a. And is used when establishing a logical connection 62. The disconnection time 68 is an item indicating the time when the logical connection 62 is disconnected, and the time when the disconnection operation is completed is displayed by the connection control module 60a at that time. When the abnormality of the logical connection 62 is confirmed, the confirmed time is displayed.

The above is the connection control module 60a.
However, it goes without saying that the record format recorded by the connection control module 60b is similar to this.

Next, returning to FIG. 1, a procedure for establishing the logical connection 62 will be described. (1) First, the process 4b on the computer 1b is a computer
In order to accept the request for establishing the connection from the process 4a on 1a, the connection control module 60b is instructed to prepare for establishing the connection. (2) The connection control module 60b requests the allocation by indicating the termination identifier to the OS 7b so that the termination identifier of the port 6b is set to "100". The termination identifier "10" for this port 6b
The "0" is widely known to other processes. (3) The OS 7b confirms that the terminal identifier "100" of the port 6b is not used by any other process (not shown) on the computer 1b, allocates the identifier "100", and sends it to the connection control module 60b. Notify that you have assigned as requested. (4) OS 7b commands TCP module 5b to prepare for establishing a connection. (5) The process 4a on the computer 1a instructs the connection control module 60a on the probability of logical connection to the terminal identifier "100" of the port 6b on the computer 1b. (6) The connection control module 60a sets the terminating identifier of the vacant port 62a to the OS to set the terminating identifier to "200".
Request the assignment as shown in 7a. (7) The OS 7a confirms that the terminal identifier "200" of the port 62a requested to be allocated is not used by another process (not shown) on the computer 1a, and the identifier "20" is checked.
"0" is assigned and the connection control module 60a is notified that it has been assigned as requested. (8) The OS 7a instructs the TCP module 5a to establish a connection to the terminal identifier "100" of the port 6b of the specified process 4b. (9) The TCP module 5a specifies the termination identifiers "200" and "100" to the TCP module 5b and sets the logical connection 62.
Send a request message to establish. (10) Upon receiving the message, TCP module 5b investigates whether the specified termination identifier "100" is assigned, and if it is assigned, it uses port 6b.
Notify that there was a request to establish a logical connection to the. (11) This notification is transmitted to the connection control module 60b via OS 7b. (12) The connection control module 60b determines whether or not to accept the request, and if it accepts, the acceptance of the request,
Notify OS 7b and process 4b. (13) OS 7b notifies TCP module 5b of acceptance. (14) The TCP module 5b sends an acceptance message to the TCP module 5a. (15) The TCP module 5a sends an acceptance message to the port 62a. (16) This acceptance message is transmitted to the connection control module 60a via the OS 7a. (17) The connection control module 60a notifies the process 4a that the logical connection has been established, and the logical connection 62 is established. This is the connect operation.

After the connect operation, the data is transferred, and after the data transfer, the disconnect operation is performed. This disconnect operation is also performed according to the connect operation. In this way, the connection control module 60a (or 60b) assigns the termination identifier of the port 62a (or 6b).

Next, the operation of the connection control module 60a for determining the termination identifier of the port 62a will be described. FIG. 3 is a flowchart showing the procedure for determining the termination identifier of the port 62a in the order (6) of establishing the connection of FIG.

The connection control module 60a, which has been notified from the OS 7a that the process 4a requests the establishment of the connection, is the process of the partner station given when the request is transmitted.
The address of the computer 1b of the other station is identified based on the information about the other station 4b, and the value of the other station address and the given terminal identifier of the port 6b are the contents of the other station address 67 and the other station terminal identifier 65 in the connection record table. Local station termination identifier flag 64 from the matching records
The content of the local station termination identifier 63 that is “unused” (the one used as the local station termination identifier before the last time) is read (S
1).

Next, when the read value establishes the logical connection 61, that is, at the last connect operation, the port
It is determined by investigating the connection record table whether it has been used as the termination identifier of 61a (S2). If the determination result is NO, the read value is used as the termination identifier of the port 62a, registered in the own station termination identifier 63 of the record to be recorded this time in the connection recording table, and the corresponding own station termination identifier flag 64 is set to ""Use" is displayed (S
3). If the judgment result is YES, the built-in timer judges whether or not the maximum survival time of the segment has elapsed from the disconnection time when the logical connection 61 was disconnected (S4). Move to S3,
If it has not elapsed, the other station termination whose flag for the station termination identifier is "unused" among the records corresponding to the station termination identifier 65, the station address 66, and the station address 67 in the connection recording table The content of the identifier 63 is read (S5), and the process proceeds to step S2.

In this way, the connection control module 60
When a communication is restarted, a value different from the terminal identifier before the restart is set as the terminal identifier based on the connection record table that records the items related to the connection so far. Therefore, both TCP modules 5a and 5b establish a logical connection 62 different from the logical connection 61 before the restart. In the meantime, there is no waiting time. Since this logical connection 62 is different from the logical connection 61, the segment that is floating and alive in the network is not given to the process 4b.

When the computer 1a is regularly inspected,
Contents of the connection record table stored in an external storage device, periodic inspection is performed by turning off the power, and after the periodic inspection is completed, the power is turned on again and the computer 1a is started up and stored in the external storage device. To the connection record table. In this case, the content of the connection record table loses temporal continuity. Therefore, it is necessary to update the content of this connection record table to a predetermined value so that it can be used for subsequent determination of the local station termination identifier.

FIG. 4 is a flow chart showing the procedure for updating the connection recording table to a predetermined value when the computer 1a is restarted. First, the first record is read from the connection record table (S1), and it is determined whether or not the item of the flag 64 for the terminal termination identifier is "unused" (S2). In the case of YES, it is judged whether the current time of reading the record has passed the maximum survival time of the segment from the contents of the disconnect time 68 (S3). In the case of YES, the contents of the disconnect time are "0". Initialize as
(S4). Determine if there is a record to read next
(S5) If YES, read the next record from the connection record table (S6), and move to step S2.

If NO in step S2, the content of the flag 64 for the terminal termination identifier of the local station is set to "unused", and the current time is substituted as the content of the disconnection time 68 (S7).
Move to S5. If NO in step S3, step
Move to S5. If NO in step S5, the procedure ends. By thus updating the contents of the connection record table to the predetermined value, the connection record table can be continuously used for determining the terminal termination identifier even after the computer 1a is restarted.

[0036]

As described above, according to the first invention or the third invention, the other party of the current communication and the other party of the previous communication are the same on the basis of the connection control information for performing the control for establishing the logical connection. However, if the predetermined time has not passed from the time of disconnecting the logical connection in the previous communication, a logical connection different from the previous time is established, so waiting time until the logical connection is established is unnecessary. Therefore, the transmission data is not lost when the storage capacity of the transmission data buffer of the computer is small.

According to the second invention or the fourth invention, the identifier for identifying the logical connection and the time when the logical connection is disconnected are stored as the connection control information, and are stored as the connection control information after the power of the computer is turned on. Since the content is set to the predetermined value, the logical connection can be established in the same manner as before the power supply to the computer was cut off, so that the waiting time until the logical connection is established is unnecessary.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a procedure for establishing a logical connection according to the first invention.

FIG. 2 is a format of a record recorded by the connection control module in FIG.

FIG. 3 is a flowchart showing a procedure in which the connection control module in FIG. 1 determines a termination identifier.

FIG. 4 is a flowchart showing a procedure for updating a connection recording table according to the second invention.

FIG. 5 is a schematic diagram showing an inter-computer communication system via a network.

FIG. 6 is a schematic diagram showing data transfer in inter-computer communication.

FIG. 7 is a schematic diagram showing a procedure for establishing a conventional logical connection.

[Explanation of symbols]

 1a, 1b… 1f Computer 2a, 2b… 2f Network 3a, 3b… 3e Gateway 4a, 4b Process 5a, 5b TCP module 6 Logical connection 6a, 6b Port 7a, 7b OS 60a, 60b Connection control module 61,62 Logical Connection 61a, 62a port

Claims (4)

[Claims] 1. A connection control method for establishing a logical connection for communication between computers and for controlling the disconnection of the logical connection after the communication is completed, the connection being for performing control for establishing the logical connection. Storage means for storing control information; first determination means for determining whether or not the partner station of the current communication is the same as the partner station of the previous communication based on the contents stored in the storage means; If the determination means is the same, the second determination means for determining whether or not a predetermined time has elapsed from the time of disconnecting the logical connection in the previous communication; and if the second determination means is determined to be no previous time Connection establishing means for establishing a logical connection that is logically different from the logical connection in the communication of ® emission control system. 2. The storage means stores an identifier for identifying a logical connection and a disconnection time at which the logical connection is disconnected as the connection control information, and after the power of the computer is turned on, the content to be stored by the storage means is predetermined. The connection control system according to claim 1, further comprising setting means for setting the value. 3. A connection control method for establishing a logical connection for communication between computers and for controlling the disconnection of the logical connection after the communication is completed, which is a connection for performing a control for establishing a logical connection. Stores control information, judges whether the partner station of this communication is the same as the partner station of the previous communication based on the stored connection control information, and if the judgment result is the same, the logic of the previous communication It is characterized by determining whether a predetermined time has elapsed from the time when the physical connection was disconnected, and if the result of the determination is negative, establishes a logical connection that is logically different from the logical connection in the previous communication. Connection control method. 4. An identifier for identifying a logical connection and a disconnection time when the logical connection is disconnected are stored as the connection control information, and after the power of the computer is turned on, the content stored as the connection information is set to a predetermined value. The connection control method according to claim 3.