JPH10262093A - Transmission control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the checking of data omission and data retransmission, without changing other computer management information inside an existing computer, in the case of changing system constitution. SOLUTION: A transmission serial number management table 107 holds a latest serial number for each transmission destination. The computer 101-1 adds the latest serial number corresponding to the transmission destination to transmission data, stores them in a retransmission data storage buffer 108 and then transmits them to the computer 101-2. A reception serial number management table 113 holds the latest serial number for each transmission origin node. The computer 101-2 compares the received data with the latest serial number held and checks for data omission. At the time of detecting the data omission, a retransmission request is issued. The computer 101-1 takes out the data provided with a specified serial number from the retransmission data storage buffer 108 and retransmits them to the computer 101-2, in response to the retransmission request.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission control method for detecting whether data transmitted from a transmission node reaches a reception node via a network, and more particularly to a transmission control method for detecting data loss.

[0002]

2. Description of the Related Art For example, a unicast system and a broadcast system are used as communication systems of an information processing system in which a plurality of computers are connected via a network like a distributed processing system and mutually transmit data. The unicast method is a method in which a computer on the data transmission side performs one-to-one data transmission by designating the address of the computer on the data reception side. On the other hand, the broadcast method
In this method, one computer in a network generally performs one-to-n data transmission by specifying a common address for a plurality of computers, and transmitted data is received by all the computers addressed by the common address.

In such a communication system, a part of transmission data may be lost due to congestion on a network or a physical failure of a transmission path, so that data transmitted from a transmitting computer reaches a receiving computer. A technique for detecting whether or not the data has been transmitted and transmitting the data again when the data is not reached is required. In the case of the unicast method, when the receiving computer normally receives the data transmitted by the conventional transmitting computer, the receiving computer sends a reception completion signal to the transmitting computer, and the transmitting computer receives the reception completion signal and the data arrives. A technique for preventing data loss by retransmitting data when a reception completion signal is not received after confirming the reception completion signal is known. Such a method is described in, for example, “Address System Implementation Rules, pp. 4 (Implementation Rule Number: INTAP-S002).
(-02)), Information Processing Interoperability Technology Association ”, Int
ernet with TCP / IP, Vol. 2 (A
SCII).

A technique called a so-called remote procedure call (RPC) for calling a procedure in a server computer from a procedure in a client computer has been put to practical use. This RPC implements a network-transparent procedure call interface that performs processing on the server side without being aware of the network configuration on the client side. In such a technique, it is assumed that the client side waits until the processing on the server side is completed. Therefore, even if any data of the processing request from the client to the server or the processing result sent from the server to the client is lost. Processing on the client side does not end. Therefore, the client checks for data omission between the client and the server in the processing of the RPC, and the RP
C is also a case where the transmitting computer checks for missing data in the unicast communication method. Such techniques are described, for example, in "Introduction to DCE" and "Introduction to CORBA".

[0005]

According to the above prior art, the transmitting computer checks the completion of data transmission based on the reception completion notification from the receiving computer. Sender computer to do so, to determine whether to communicate with the advance which computer holds a correspondence table with the information indicating whether or not the address and data transmission for each recipient computer of the communication partner is completed, management Must.

In such a system, when a system configuration is changed or expanded, especially when a new computer enters the network system, information about the new computer is transmitted to all computers that transmit data to the participating computer. There is a problem that the management needs to be added, the management becomes complicated, and the cost increases due to a new data input or a stop of the operation of the computer. For example, when adding a new server to the network system, an entry for the new server must be added to the above-mentioned correspondence table used by the RPCs of all existing clients.

As a method for solving such a problem, for example, Japanese Patent Application Laid-Open No. 55-13725 discloses a method in which a transmitting computer broadcasts data by using an identifier called a content code, which is defined according to the content of data. And a method in which the receiving computer determines whether or not to receive data based on the content code is disclosed. However, in this method, since all data is transmitted by broadcasting, the transmitting computer cannot determine the completion of data transmission. That is, when data is lost due to a failure in a network or the like, failure recovery cannot be performed by retransmitting the data.

On the other hand, when the transmitting computer checks the completion of data transmission, it retransmits the transmission data when detecting a data loss, but the receiving computer mixes the latest data and the retransmitted data that are normally transmitted. Therefore, there is a problem that the order of the received data is not guaranteed.

An object of the present invention is to check for data loss without changing management information on other computers in an existing computer or stopping operation of a computer when a system configuration is changed or expanded. An object of the present invention is to provide a transmission control method that enables data retransmission.

Another object of the present invention is to guarantee the order of received data when retransmitted data and ordinary latest data are mixed.

[0011]

According to the present invention, a transmitting node holds the latest serial number for each destination, adds the latest serial number corresponding to the destination to transmission data, and transmits the data to a receiving node. The transmission control method is characterized in that the receiving node holds the latest serial number for each transmission source node, and compares the received serial number of the data received from the transmitting node with the held latest serial number to detect missing data.

If the transmitting node keeps the latest serial number corresponding to the group of the destination nodes that broadcasts as the destination, even if a new receiving node is added to the network system, the transmitting node will have a new serial number. There is no need to add information about the receiving node.

Further, the transmitting node sequentially saves the transmission data with the latest serial number, and responds to the retransmission request sent due to the missing data detected by the receiving node and uses the transmission data having the specified serial number as retransmission data. Send to the receiving node. Here, the transmitting node sequentially retransmits a series of transmission data from the transmission data having the retransmission requested serial number to the transmission data having the latest serial number corresponding to the transmission destination to the reception node, and the reception node is the transmission source node. If the retransmission data is received one by one in the order of the serial number from the reception data of the serial number for which the retransmission request is made, the order of the received data when the retransmitted data and the normal latest data are mixed is guaranteed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

(1) First Embodiment FIG. 1 is a configuration diagram of an electronic computer, and is a functional configuration diagram expressed by functional blocks focusing on parts related to the present invention. The system has a plurality of computers 101, and each computer 101 is connected to a transmission path 103 via a communication device 102 and can communicate with each other. In this embodiment, the application program is divided into a data transmission application 118 and a data reception application 117 for convenience of explanation. Further, the part of the communication management program interposed between the application program and the communication device 102 is divided into a function block used at the time of transmission, a function block used at the time of reception, and a function block for retransmission processing.

[0016] As functional blocks used at the time of transmission,
The transmission serial number management table 107 holds the latest serial number added to the transmission data. The transmission sequence number management unit 109 manages the transmission sequence number management table 107 and provides the latest sequence numbers. The data transmission interface 111 receives a data transmission request from the data transmission application 118, adds the latest serial number obtained via the transmission serial number management unit 109 to the transmission data, and stores the transmission data in the transmission buffer 106 and the retransmission data storage buffer 108. Data transmission unit 104
Extracts the transmission data from the transmission buffer 106, determines the destination of the transmission data with reference to the transmission destination management table 119, and transmits the transmission data via the communication device 102 to the transmission path 1.
03.

As functional blocks used at the time of reception,
The reception serial number management table 113 holds the latest serial number expected to be added to the received data. The reception serial number management unit 114 checks the serial number added to the reception data with reference to the reception serial number management table 113. The data receiving unit 105 communicates with the transmission line 10 via the communication device 102.
3 is stored in the reception buffer 112. The data reception interface 116 extracts the reception data from the reception buffer 112, and
4 to check the serial number added to the received data. If the added serial number is correct, it refers to the received data type management table 120 to determine to which application program the received data is passed, and passes the received data to the corresponding data receiving application 117.

As functional blocks for retransmission processing, a retransmission request transmission section 115 and a retransmission processing section 110 are provided. When the serial number added to the received data is incorrect, control is passed to the retransmission request transmission unit 115, and the retransmission request transmission unit 115 requests the computer 101 on the data transmission side to retransmit the data. Retransmission processing unit 1
In 10, control is passed when a retransmission request message is received, the requested transmission data is extracted with reference to the retransmission data storage buffer 108, and transmitted to the requesting computer 101.

In the above functional blocks, information or storage areas with tables and buffers are stored in the computer 10.
One main storage device or an external storage device. Other functional blocks are realized by a hardware mechanism or by executing a program stored in a main storage device of the computer 101.

FIG. 2 is a configuration diagram showing one configuration example of a network system to which the present invention is applied. The system connects a plurality of computers 101 via a common transmission path 103, and each computer 101 communicates via the transmission path 103. The transmission path 103 is a communication line such as a LAN or a WAN, and is physically composed of at least one cable, and can be connected to another transmission path 103 to configure a large-scale and wide-area system. Network connection device 20
Reference numeral 2 denotes a device for connecting the transmission paths 103, such as a bridge or router for connecting LANs, a modem for connecting WANs, a TA (Terminal Adapter), or the like.
A gateway connecting the LAN and the WAN can be used.

FIG. 3 shows a computer 101-1 on the data transmission side.
FIG. 6 is a diagram showing a procedure of data communication between the data receiving side and a computer 101-2 on the data receiving side. First, the data transmission application 118 of the computer 101-1 passes the transmission data to the data transmission interface 111 (1, omit the following ○). The data transmission interface 111 acquires a serial number to be added to the transmission data from the transmission serial number management table 107 via the transmission serial number management unit 109 (2). Next, the obtained serial number and transmission data are stored in the retransmission data storage buffer 1.
08 (3), and transmits the transmission data as normal data to the transmission path 103 via the data transmission unit 104 (4, 5). The data receiving unit 105 of the computer 101-2 receives this data and passes it to the data receiving interface 116 (6). Data receiving interface 1
The received serial number management unit 114 to which the control has been passed from 16 receives the serial number added to the received data and the received serial number management table 11.
The latest received serial number stored in No. 3 is compared to determine whether or not the received data has the correct serial number (7). If the received data is duplicated data, the data is discarded. If the received data is data having a correct serial number, the data is transmitted to the data reception application 117.
Distribute to When it is determined that the received data has arrived after one or more data has been lost, the data reception interface 116 passes control to the retransmission request transmission unit 115 (8). The retransmission request transmitting section 115
A retransmission request for the missing data via transmission line 1
03 (9). This retransmission request is
This is illustrated as t. The data receiving unit 105 of the computer 101-1 receives the retransmission request, and
Pass it to 0 (10). The retransmission processing unit 110 searches the retransmission data storage buffer 108 based on the serial number requested to be retransmitted (11), and transmits the corresponding data to the transmission path 103 as a response via the data transmission unit 104 (12, 13). Data receiving unit 10 of computer 101-2
5 receives this retransmission data and passes it to the data reception interface 116 (14). The data reception interface 116 determines that the data is retransmission data, passes it to the reception application 117 as normal data, and ends a series of retransmission processing.

FIG. 4 is a diagram showing the data structure of the transmission serial number management table 107. Transmission sequence number management table 107
Are the destination information 401 and the latest serial number 402
Consists of The transmission destination information 401 stores information such as an address and an identifier of the transmission destination computer. In the case of unicast communication, the address of the destination computer or an identifier corresponding to the address is specified in the destination information 401. In the case of broadcast communication, a group address of a group of a transmission destination to be broadcast or an identifier thereof is specified in the transmission destination information 401. For example, when performing broadcast communication using UDP / IP as a communication protocol, the destination information 401 is a subnet address of a segment for broadcasting data or an identifier corresponding thereto. In the example shown in FIG.
01 is an unified multicast group number, that is, an identifier in which a serial number is added to a code called MCG (Multi-cast Group) regardless of the difference between various communication protocols and the destination of unicast communication or the destination of broadcast communication. Used.
The latest serial number 402 stores the latest serial number added to the transmission data for each transmission destination.

FIG. 5 is a diagram showing the data structure of the retransmission data storage buffer 108. Retransmission data storage buffer 1
08 is a serial number 50 added to the transmission data.
1, transmission destination information 502 indicating a transmission destination of transmission data, a data type 503 for determining the content of the transmission data, and a transmission data unit 504 for storing the entity of the transmission data. The transmission destination information 502 is the same as the transmission destination information 401, and is specified by the data transmission application 118 or the data transmission application 1
18 is obtained by converting the data type 503 specified by 18 into the destination information 502 by the destination management table 119. The data type 503 is information indicating the content of data specified by the data transmission application 118.

FIG. 6 is a diagram showing the data structure of the destination management table 119. Each entry of the destination management table 119 includes a destination information 701 and a destination address 70
2, but a data type 503 may be further added. The destination information 701 is the same as the destination information 401. The transmission destination address 702 indicates a physical address of a data transmission destination. In the case of the destination of the broadcast communication, the destination address 702 indicates a group address such as a subnet address. Destination information 401
When a physical address is used as the destination information 502, the destination management table 119 is unnecessary. However, since the destination address 702 has a different address description format depending on the type of network used and the communication protocol, the destination information 701 must be a logical identifier so that the application program is not aware of such a physical address. It is desirable to provide a destination management table 119 for converting this logical identifier into a physical address.

FIG. 7 is a diagram showing a data structure of the reception serial number management table 113. Reception serial number management table 113
Each entry has a transmission source node number 601, a latest reception serial number 602, and a reception state 603. The transmission source node number 601 is a node number of the transmission source computer 101 and is included in a message from the transmission source. The latest reception serial number 602 is an expected latest reception serial number. The reception state 603 is set when a missing data is detected as a result of comparing the latest reception serial number 602 with the serial number added to the received data. The latest reception serial number 602 needs to be managed for each transmission source node. In the example of FIG. 7, for example, the latest reception serial number 602 that is expected to be next received from the transmission source whose transmission source node number 601 is Node5 is 102.

FIG. 8 shows the received data type management table 12.
It is a figure showing the data structure of 0. The reception data type management table 120 includes a data type 2201 and a data reception application 2202. Data type 2
201 is a data type included in the message from the transmission source. The data reception application 2202 indicates the data reception application 117 to which data is to be distributed in accordance with the data type 2201. The data reception interface 116 is a data reception application 117
Type 2201 notified at the time of issuing the data reception request and the data reception application 22 of the request source
02 is registered in the received data type management table 120. If the received data of the same data type is registered in the received data type management table 120 so as to be distributed to a plurality of data receiving applications 117, the received data is transmitted to all the data receiving applications 117 registered corresponding to the data type. To deliver.

FIGS. 9 to 11 are diagrams showing the data format of a message transmitted via the transmission path 103. FIG. FIG.
9 is a diagram showing a normal transmission data format 801. FIG. The flag 802 is a flag indicating that the type of the message is normal. The destination address 803 is the destination address 70
Same as 2. Data type 804 is destination address 8
The data type 503 corresponds to the data type 03. The serial number 805 is the latest serial number 402 obtained from the transmission serial number management table 107 corresponding to the transmission destination address 803. The transmission source node 806 is a node number indicating the transmission source computer 101 of the message. Data section 807 has data type 8
This is the same as the transmission data section 504 corresponding to the transmission data section 04. The normal transmission data format 801 includes other information used for detecting an error that occurs during communication, but these are omitted because they are not directly related to the present invention.

FIG. 10 is a diagram showing a retransmission request data format 901. The flag 902 is a flag indicating that the type of the message is a retransmission request. Destination address 90
3 is a physical address of a transmission destination of the retransmission request. FIG.
In the example of 0, since the subnet address is specified as the destination address 803, the destination address 903 also specifies the same subnet address. Data type 904
Indicates that the message is retransmission request data. The retransmission request serial number 905 is the serial number of the transmission data requested to be retransmitted. The retransmission request source node 906 is the node number of the computer 101 requesting retransmission. Request destination node 90
Reference numeral 7 denotes a node number of the computer 101 to which a retransmission request is issued, and is a transmission source node 806 of the received normal message. The retransmission request data format 901 includes other information used for detecting an error occurring during communication, but these are omitted because they are not directly related to the present invention.

FIG. 11 is a diagram showing a retransmission data format 1001. The flag 1002 is a flag indicating that the type of the message is retransmission data. Destination address 1
003 is a physical address of a transmission destination of retransmission data,
This is the same address as the destination address 803. The data type 1004 is the same data type as the data type 804. The serial number 1005 is the serial number of the received data that has received the retransmission request. The source node 1006 is the node number of the computer 101 that is the source of the retransmission data. Retransmission request source node 1
007 is the node number of the computer 101 that has requested retransmission. The retransmission data format 1001 includes other information used for detecting an error that occurs during communication.
These are omitted because they are not directly related to the present invention.

FIG. 12A is a flowchart showing the flow of processing from receiving a transmission request from the data transmission application 118 to transmitting data to the destination. The data transmission interface 111 receives data, destination information, and data type from the data transmission application 118 (step 1101). Next, the data transmission interface 111 calls the transmission sequence number management unit 109 and passes the transmission destination information. When only the data type is specified from the data transmission application 118, the transmission sequence number management unit 109 is called after acquiring the transmission destination information corresponding to the data type by referring to the transmission destination management table 119. The transmission sequence number management unit 109 searches the transmission sequence number management table 107 based on the received transmission destination information, and updates the latest transmission sequence 402 of the corresponding transmission destination information 401 by counting up by 1 (step 110).
2), and pass the updated latest serial number to the data transmission interface 111 (step 1103). The transmission serial number management unit 109 stores the latest serial number in the data transmission interface 111
You may update it after passing it to. Next, the data transmission interface 111 adds a record including the latest serial number, transmission destination information, data type, and transmission data to the retransmission data storage buffer 108 (step 1104). If the end of the retransmission data storage buffer 108 has been reached,
Will overwrite the first record. Flag 8
As 02, transmission data with Normal, transmission destination information, data serial number, data type, and transmission source node number is stored in the transmission buffer 106 (step 1105). The data transmission unit 104 takes out the transmission data from the transmission buffer 106, refers to the destination management table 119, converts the destination information into the destination address, and sends out the normal transmission message created on the transmission path 103 (step 11
06).

FIG. 12B shows the data receiving interface 1
16 is a flowchart of a process from receiving a retransmission request to transmitting retransmission data to a destination. The data reception interface 116 receives the retransmission request message from the reception buffer 112 (step 1111), and passes the retransmission requesting destination information, the retransmission request sequence number 905, and the retransmission request source node 906 to the retransmission processing unit 110. The retransmission processing unit 110 searches the retransmission data storage buffer 108 using the serial number 501 and the destination information 502 as keys, and determines whether there is a corresponding serial number (step 1112). If there is a corresponding record (step 1112 YES), the record is acquired (step 1113), and the flag 10
As 02, the response, the transmission destination information, the data type, the serial number, the retransmission data with the transmission source node and the retransmission request source node are stored in the transmission buffer 106 (step 1114). Next, the retransmission processing unit 110 searches the transmission serial number management table 107 based on the destination information, and determines whether or not the serial number matches the latest serial number of the destination information (step 1115). If the serial number is not the latest serial number (NO in step 1115), a next serial number obtained by adding 1 to the serial number is created (step 1116), and the processing from step 1112 is repeated using the next serial number as the serial number. When it is determined that the serial number matches the latest serial number of the destination information on the transmission serial number management table 107 (step 1115 YES), the processing of the retransmission processing unit 110 ends. The retransmission data stored in the transmission buffer 106 is
The data is transmitted by the data transmission unit 104 as a retransmission message onto the transmission path 103 (the same processing as in step 1106). On the other hand, when the corresponding serial number is not found in the retransmission data storage buffer 108 (step 1112 NO), the retransmission processing unit 110 displays the retransmission error on the display device of the transmission side computer 101-1 or receives the retransmission error.
2 is notified (step 1117). In this way, by serially retransmitting a series of serial numbers from the retransmission request serial number to the latest serial number, the order of data received by the receiving computer 101-2 is guaranteed when data loss occurs. After the receiving computer 101-2 detects the data loss and performs the retransmission request process, and before receiving the retransmission data, the computer 101-2 has a newer serial number than the serial number of the received data from which the data loss was detected. Subsequent transmission data with a serial number may be received. In this case, a state occurs in which the order of reception between the data to be retransmitted and the data received before that is out of order. In order to maintain such a receiving order, the receiving computer 101-2 discards data from the transmitting computer 101-1 without receiving it after data loss occurs,
The retransmitting computer 101-1 transmits a series of data from the missing data to the latest data.
The processing in step 1116 enables data transmission up to the latest data.

FIGS. 13A and 13B show the data receiving unit 1.
05 is a flowchart showing the flow of processing after data reception. When the data receiving unit 105 receives the message (step 1201), the flags 802, 902, 1
Check 002. If the flag is Normal (step 1202 Normal), the transmission destination address 803
To determine whether the message is to be received by the own node (step 1203). If the message is to be received by the own node (YES in step 1203), the data type 80 is referenced with reference to the received data type management table 120.
It is determined whether or not 4 is a data type to be received by the own node (step 1204). However, when the data type is not used as the communication protocol, there is no determination processing in step 1204. If the data type is to be received by the own node (YES in step 1204), the destination management table 1
After the destination address 803 is converted into the destination information with reference to 19, the received data is stored in the reception buffer 112 (step 1205). If the destination address 803 is not a destination address to be received by the own node, or if the data type 804 is not a data type to be received by the own node, the processing of the data receiving unit 105 is ended. The data reception interface 116 extracts the reception data from the reception buffer 112 (step 1206), calls the reception sequence number management unit 114, and receives the transmission source node 80.
Pass 6 and serial number 805. The reception serial number management unit 114 uses the source node number as a key
And determines whether or not the received transmission source node 806 is registered (step 1207). If there is a corresponding entry, the entry is acquired. If there is no corresponding source node number (step 1207N
O), the entry having the received source node 806 and the serial number 805 is registered in the reception serial number management table 113 (step 1208).

Turning next to FIG. 13B, the reception serial number management unit 11
No. 4 determines whether the latest received serial number 602 of the acquired entry matches the received serial number 805 (step 1209). If the reception serial number matches the latest serial number (YES in step 1209), the latest reception serial number 602 of the acquired entry of the reception serial number management table 113 is updated by counting up by 1 (step 12).
10). At this time, if a flag indicating data loss is set in the reception state 603 of the entry, the entry is reset.
Thereafter, the control returns to the data reception interface 116, and the data reception interface 116 refers to the reception data type management table 120 and passes the reception data to the corresponding data reception application 117 (step 1).
211). If the reception serial number does not match the latest serial number (step 1209 NO), the reception serial number management unit 114
It is determined whether or not 5 is larger than the latest reception serial number 602 of the entry (step 1212). When the reception serial number is greater than the latest serial number (step 1212: YES), the reception serial number management unit 114 sets a flag indicating a missing data in the reception status 603 of the entry, and returns the control to the data reception interface 116 with the latest serial number as the request serial number. . The data reception interface 116 passes the transmission destination information, the retransmission request serial number, and the request destination node to the retransmission request transmission unit 115, and issues a retransmission request. Here, the request destination node 907 is the source node 806 that has received the request. The retransmission request transmitting unit 115 creates retransmission request data from the received information and stores it in the transmission buffer 106 (step 1213). However, when reception serial number> latest serial number (step 1212YE
S) If a flag indicating data omission is set in the reception status 603 of the entry, it means that a retransmission request has already been made for the latest serial number. 116 simply discards the received data.
When reception serial number <latest serial number (step 1212N
O), the reception serial number management unit 114 notifies the data reception interface 116 of the fact, and the data reception interface 1
16 discards the received data.

If the flag is Response (Step 1202 Response), the data receiving unit 105
Determines whether the message is to be received by the own node with reference to the destination address 1003 (step 1221).
If the message is to be received by the own node (step 1
221 YES), referring to retransmission requesting node 1007, to determine whether or not the own node is a retransmission requesting node (step 1222). If the own node is the retransmission request source node (step 1222 YES), the destination address 1003 is converted to destination information with reference to the destination management table 119, and the received data is stored in the reception buffer 112 (step 1205). . The processing after step 1206 is as described above. If the destination address 1003 is not the destination address to be received by the own node, or if the retransmission request source node 1007 is not the own node, the process ends. Since the retransmission data is requested from the receiving computer 101-2, a plurality of receiving computer 101
-2, when data loss occurs, a plurality of retransmission requests are notified to the transmission source computer 101-1. Retransmission data is transmitted. In such a case, the receiving computer 101-2 determines whether or not the number of the retransmission request source node and the own node number match at the beginning of the data reception process so that retransmission data other than the retransmission data requested by itself is not received as much as possible. Is determined.

If the flag is Request (Step 1202 Request), the process proceeds to FIG. 13B, and the data receiving unit 105 determines whether or not the message is to be received by the own node with reference to the destination address 903 (Step 1).
231). If the message is to be received by the own node (YES in step 1231), it is determined whether or not the own node is the request destination node with reference to the request destination node 907 (step 1232). If the own node is the request destination node (step 1232: YES), the destination node refers to the destination management table 119, converts the destination address 903 into destination information, and stores the received data in the reception buffer 112 (step 1233). If the destination address 903 is not the destination address to be received by the own node, or if the request destination node 907 is not the own node, the process ends.

FIG. 14 is a diagram exemplifying a procedure for detecting missing data and retransmitting data between the transmitting computer 101-1 and the receiving computer 101-2. In this example, the transmitting computer 101-1 normally transmits the data of serial numbers 100, 101, and 102, and the receiving computer 101-2 has 1
The data of Nos. 00 and 101 are normally received. If the data of No. 102 does not reach the receiving computer 101-2 due to some failure of the transmission medium, the receiving computer 1
01-2 detects the omission of the data of the 102th data when the next data of the 103rd data is received. At this point, the receiving computer 101-2 transmits a retransmission request for the data No. 102, and the transmitting computer 101-1 retransmits the data No. 102 and the data No. 103.

According to the first embodiment, the transmitting computer 101-1 that has received the retransmission request uses the serial number 501 and the transmission destination information 502 as keys to acquire the requested retransmission data, Search 108. In addition, it is necessary to search for a series of retransmission data from retransmission data having a retransmission requested serial number to retransmission data having the latest serial number in response to one retransmission request. Therefore, there is a problem that the overhead of the process of searching the retransmission data storage buffer 108 is large.

FIG. 15 shows an example in which each destination information is used as an index, and a table of the retransmission data storage buffer 108 is provided for each destination information. By configuring the retransmission data storage buffer 108 in this manner, the speed of searching the retransmission data storage buffer 108 can be increased. However, since a buffer is prepared for each destination information, more storage area is required.

In the above two systems, the retransmission data storage buffer 108
Is full and retransmission data is overwritten, a retransmission error may occur because the retransmission data has been erased (NO in step 1112). In such a case,
Even if the retransmission error is notified to the data receiving application 117 of the receiving computer 101-2, there is a problem that it is not possible to know which data should be retransmitted between the application programs. In the third method, the transmission sequence number management table 107, the retransmission data storage buffer 108, and the reception sequence number management table 113 are configured on the basis of the data type, and when a retransmission error occurs, data can be retransmitted between application programs. Things.

In the third method, as shown in FIG. 16, the transmission serial number management table 107 is configured to hold the latest serial number 2002 for each data type 2001. FIG.
As shown in FIG. 7, the retransmission data storage buffer 108 is configured to have each data type as an index and to have a buffer for each data type. Also, as shown in FIG. 18, the reception serial number management table 113 is configured to provide the latest reception serial number 602 for each of the source node number 601 and the data type 2102. In the third method, the latest serial number corresponding to the data type specified by the data transmission application 118 is acquired with reference to the transmission serial number management table 107, and a buffer having the specified data type in the retransmission data storage buffer 108 as an index. To store the retransmission data. When the data loss is detected in the receiving computer 101-2, a retransmission request is sent to the transmitting computer 101-1 with the data type 2102 and the latest reception serial number 602. The transmission side computer 101-1 searches the retransmission data storage buffer 108 using the data type 2102 and the latest reception serial number 602 as keys to transmit the requested retransmission data. At this time, if a retransmission error occurs, the receiving computer 101
By notifying the data receiving application 117 of -2 with a retransmission error with the data type and the serial number requested for retransmission, it becomes possible to specify the target data when data is retransmitted between application programs.
The third method can speed up the search of the retransmission data storage buffer 108 as in the second method, and also enables data retransmission at the application level. However, a large storage area is required for the retransmission data storage buffer 108 and the like.

As described above, according to the first embodiment, the transmission sequence number management table 1 of the transmission side computer 101-1
07 is configured to hold the latest serial number for each logical transmission destination identifier as much as possible.
Each entry of the reception serial number management table 113 of 01-2 is configured to hold the latest serial number for each transmission source node, and the receiving computer 101-2 performs a serial number check, thereby checking for missing data and transmitting errors due to data retransmission. Recovery is possible. Therefore, even if a new computer 101 enters the network system, the transmitting computer 10
There is little need to update the management information such as the transmission sequence number management table 107 of FIG.
2 is configured so that an entry having a new transmission source node can be added online. Therefore, it can be said that the network system to which the first embodiment is applied is a system which can easily cope with addition and expansion of the computer 101. In particular, when the broadcast communication is adopted as the communication method, the range of the computer 101 that performs simultaneous broadcast is grouped as a multicast group, and the group identifier is used as the transmission destination information, It is understood that even if the computer 101 is added to the system, there is no need to add a new entry to the management information of the transmitting computer 101-1 and the entry of the computer 101 is not affected at all. As a protocol for unicast communication by designating a specific physical address or broadcast communication by designating a group address, for example, "TCP / TCP" issued by Soft Research Center, written by Takeshi Nishida.
A protocol called TCP / IP described in “IP—Network Protocol and Implementation” can be used.

(2) Second Embodiment In the first embodiment, when the receiving computer 101-2 checks for missing data, the receiving computer 101-2 receives data having a serial number next to the serial number of the missing data. Detect missing data. For this reason, the data following the data lost from the transmitting side computer 101-1 is transmitted, and the data loss cannot be detected until the subsequent data is received, which causes a problem that the retransmission request is delayed. The second embodiment is configured to shorten the time until the detection of data loss. In the second embodiment, in addition to the application of the functional blocks shown in FIG. 1, a periodic transmission manager 1301 for periodically transmitting the latest serial number of the transmitting computer 101-1 is added.

FIG. 19 shows a transmission-side computer 101-1 in the second embodiment in which a fixed-cycle transmission management unit 1301 is added.
FIG. 6 is a diagram showing a procedure of data communication between the receiving side computer 101-2. When the data transmission application 118 of the transmission side computer 101-1 passes the transmission data to the data transmission interface 111 (1), the data transmission interface 111 transmits a serial number to be added to the transmission data via the transmission serial number management unit 109. Serial number management table 107
(2), the obtained serial number and transmission data are stored in the retransmission data storage buffer 108 (3), and the transmission data is transmitted to the transmission path 103 via the data transmission unit 104 (4, 5). Hereinafter, the receiving computer 101-2 receives the data and performs the processing described in the first embodiment. The processing procedures from 1 to 14 with 〇 are the same as those in the first embodiment. In parallel with this series of normal data transmission processing, the periodic transmission manager 1301 periodically obtains the latest serial number for each piece of destination information via the transmission serial number manager 109 (2 '), and transmits the periodic message. The latest serial number is transmitted to each transmission destination (4 ', 5'). The data receiving unit 105 of the receiving computer 101-2 receives the latest serial number and passes it to the data receiving interface 116 (6 '). The data receiving interface 116 receives the latest serial number via the reception serial number managing unit 114 in the same manner as normal data reception. The serial number is checked (7 ').
When the data loss is detected, the retransmission request transmitting unit 115
Transmits a retransmission request (8, 9). That is, the transmitting computer 101-1 periodically updates the latest serial number with the receiving computer 101.
By transmitting the data to -2, the time until data loss is detected is reduced. FIG. 20 is a diagram illustrating an example of a procedure for detecting data loss due to a fixed-cycle message. In this example, the transmission side computer 101-1 has the serial number 100
No. 101, No. 102, and No. 102 are transmitted normally, and the receiving computer 101-2 normally receives data No. 100, No. 101. If the data of serial number 102 does not reach the receiving computer 101-2, the receiving computer 101
-2 detects the missing of the data of No. 102 when the next data of No. 103 is received. However, if the transmission of the 103rd data is slow, it takes a long time to detect the missing data. At this time, 1
It is possible to detect earlier that the No. 02 data is missing.

FIG. 21 is a diagram showing a fixed cycle data format 1701. The flag 1702 indicates that the type of message is a fixed period. The destination address 1703 is the same as the destination address 803. The data type 1704 indicates that the message is periodic data.
The serial number 1705 is the same as the serial number 805. The source node 1706 is the same as the source node 806. Here, the fixed-cycle message is composed of only control information, and the data section 80
It is desirable not to add actual data as in No. 7 in order to suppress the overhead of data transmission / reception and increase in traffic on the transmission path 103.

FIG. 22 is a flowchart showing the flow of the processing of the periodic transmission manager 1301. When the periodic transmission manager 1301 is started periodically (step 140).
1), it is determined whether or not the processing has been completed for all entries of the transmission sequence number management table 107 (step 14)
02). If the processing has not been completed (step 1402N
O), the destination information of the next entry in the transmission sequence number management table 107 is acquired (step 1403), the transmission sequence number management unit 109 is called, the transmission destination information is passed, and the latest sequence number is acquired (step 1404). The processing in step 1404 is the same as the processing in steps 1102 and 1103.
Next, periodic data including the acquired transmission destination information and the latest serial number is created and stored in the transmission buffer 106 (step 1).
405). Next, the index indicating the entry in the transmission sequence number management table 107 is advanced to the next, and the process returns to step 1402. When the above processing is completed for all transmission destinations in the transmission sequence number management table 107 (step 1402YE
S), the processing of the periodic transmission manager 1301 ends.

In implementing the second embodiment, the retransmission data storage buffer 108, the transmission serial number management table 1
07 and the data configuration of the reception serial number management table 113 are as follows:
Any of the first, second, or third methods described in the first embodiment can be applied. However, when the third method is applied, the transmission sequence number management table 107 has the data type 20
01 and the latest serial number 2002, the periodic transmission manager 1301 obtains the latest serial number by passing the data type to the transmission serial number manager 109 instead of the transmission destination information. There is no destination address 1703, and data type 1
Reference numeral 704 stores the acquired data type 2001.

(3) Third Embodiment In the third embodiment, the management of the transmission serial number, the retransmission data storage buffer 108, and the retransmission of data are centralized by a dedicated computer.

FIG. 23 shows a computer 101 according to the third embodiment.
FIG. 3 is a diagram showing the configuration of FIG. In the third embodiment, the transmission sequence number management table 107, the transmission sequence number management unit 109, the retransmission data storage buffer 108, and the retransmission processing unit 110 are not provided in each transmission side computer 101-1.
3 are provided in a concentrated manner. Transmission side computer 101-
When a transmission request is issued from the first data transmission application 118 (1), the data transmission interface 111
Transmits the transmission data to the retransmission computer 101-3 (2). The retransmission computer 101-3 receives this data, acquires the latest serial number from the transmission sequence number management table 107, stores the transmission data in the retransmission data storage buffer 108, and transmits the transmission data to the receiving computer 101-2. (3). The receiving computer 101-2 receives the data, checks the serial number as in the first embodiment, and distributes the data to the data receiving application 117 if there is no abnormality. When the data loss is detected, a retransmission request is transmitted to the retransmission computer 101-3 (4). Retransmission computer 1
01-3 acquires the requested transmission data from the retransmission data storage buffer 108, and retransmits the data to the receiving computer 101-2 (5). The receiving computer 101-2 receives the retransmitted data and distributes the data to the data receiving application 117 if the data has the correct serial number.

According to the third embodiment, the sending computer 1
In No. 01-1, the storage area for the transmission sequence number management table 107 and the retransmission data storage buffer 108 becomes unnecessary, and there is no need to receive a retransmission request and perform a retransmission process, thereby reducing processing overhead. Further, the receiving computer 101-2 can fixedly designate the retransmission request destination, and the load of the retransmission request processing is reduced.

[0050]

As described above, according to the present invention, the latest serial number which is synchronized with both the transmitting node and the receiving node is held. In order to make a retransmission request in such a case, there is an effect that even if a new node is added as a receiving node, it is not necessary to change the destination table managed by the transmitting node.

Further, even if the receiving node receives data retransmitted after detection of data loss and normal data in a mixed manner, the order of the received data is guaranteed.

Further, since the receiving node only has to send a retransmission request to the transmitting node only for the data for which data has been lost, the load on the network for transmitting the reception completion notification as in the related art can be reduced. is there.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a computer according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration example of a network system to which the present invention is applied;

FIG. 3 is a diagram illustrating a procedure of data communication between a transmitting side and a receiving side according to the first embodiment.

FIG. 4 is a transmission sequence number management table 107 according to the first embodiment;
FIG. 3 is a diagram showing a data configuration of FIG.

FIG. 5 is a diagram showing a data configuration of a retransmission data storage buffer 108 according to the first embodiment.

FIG. 6 is a diagram illustrating a data configuration of a transmission destination management table 119 according to the first embodiment.

FIG. 7 is a reception serial number management table 113 according to the first embodiment;
FIG. 3 is a diagram showing a data configuration of FIG.

FIG. 8 is a reception data type management table 120 according to the embodiment.
FIG. 3 is a diagram showing a data configuration of FIG.

FIG. 9 is a diagram illustrating a format of normal transmission data according to the embodiment;

FIG. 10 is a diagram illustrating a format of retransmission request data according to the embodiment;

FIG. 11 is a diagram illustrating a format of retransmission data according to the embodiment.

FIG. 12A is a flowchart illustrating a flow of a data transmission process starting from the data transmission application 118 according to the first embodiment.

FIG. 12B is a flowchart illustrating a flow of a retransmission data transmission process according to the first embodiment.

FIG. 13A is a flowchart illustrating a flow of a process when data is received according to the first embodiment.

FIG. 13B is a flowchart (continued) showing the flow of the process at the time of data reception according to the first embodiment.

FIG. 14 is a diagram illustrating a procedure for detecting missing data and retransmitting data according to the first embodiment;

FIG. 15 is a diagram showing another data configuration of the retransmission data storage buffer 108.

FIG. 16 is a diagram showing another data configuration of the transmission sequence number management table 107.

17 is a diagram showing still another data configuration of the retransmission data storage buffer 108. FIG.

FIG. 18 is a diagram showing another data configuration of the reception serial number management table 113.

FIG. 19 is a diagram illustrating a procedure of data communication between a transmission side and a reception side according to the second embodiment.

FIG. 20 is a diagram exemplifying a procedure of detecting data omission due to a fixed-cycle message according to the second embodiment;

FIG. 21 is a diagram illustrating a format of fixed-cycle data according to the second embodiment.

FIG. 22 is a fixed-cycle transmission management unit 1301 according to the second embodiment.
3 is a flowchart showing the flow of the processing of FIG.

FIG. 23 is a diagram illustrating a configuration of a computer 101 according to the third embodiment.

[Explanation of symbols]

107: transmission sequence number management table, 108: retransmission data storage buffer, 109: transmission sequence number management unit, 110: retransmission processing unit, 113: reception sequence number management table, 114: reception sequence number management unit, 115: retransmission request transmission unit, 1301: Periodic transmission manager

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigenori Samejima 1099 Ozenji Temple, Aso-ku, Kawasaki City, Kanagawa Prefecture Inside Hitachi, Ltd.System Development Laboratory Co., Ltd. Hitachi, Ltd. System Development Laboratory

Claims (10)

[Claims] 1. A transmission control method for detecting whether data transmitted from a transmitting node has reached a receiving node by connecting a node on a data transmitting side and a node on a data receiving side via a transmission path. The node holds the latest serial number for each destination, adds the latest serial number corresponding to the destination to the transmission data and sends it to the receiving node, and the receiving node holds the latest serial number for each source node. A transmission control method for detecting data omission by comparing a reception serial number of data received from a transmitting node with a latest serial number held. 2. The transmission node sequentially stores transmission data with the latest serial number, and retransmits the transmission data having the specified serial number in response to a retransmission request sent due to data omission detected by the reception node. The transmission control method according to claim 1, wherein the transmission is performed to the receiving node. 3. A series of transmission data is sequentially retransmitted from a transmission data having a serial number requested to be retransmitted by a transmission node to a transmission data having a latest serial number corresponding to the transmission destination to a reception node. 3. The transmission control method according to claim 2, wherein retransmission data is received one by one in the order of the serial number from the reception data of the serial number for which a retransmission request has been made for the transmission source node. 4. The transmission control method according to claim 1, wherein the transmission side node holds the latest serial number corresponding to the group of transmission destination nodes to be broadcast. 5. When receiving data from a source node that does not hold the latest serial number at the receiving node, a serial number assigned to the source node is newly held as the latest serial number. The transmission control method according to claim 1, wherein 6. A method in which the latest serial number is stored for each data type instead of the latest serial number for each destination, and the transmission data is attached to the latest serial number corresponding to the data type and transmitted to the receiving node. The transmission control method according to claim 1, wherein: 7. In addition to the transmission data, the latest serial number corresponding to the transmission destination is periodically transmitted to the receiving node, and the latest serial number received by the receiving node is compared with the latest serial number held by the receiving node. 2. The transmission control method according to claim 1, wherein the omission is detected. 8. A plurality of computers are connected via a transmission line,
In a computer constituting a network system for detecting whether data transmitted from a transmission side computer has reached a reception side computer, means for storing the latest serial number for each transmission destination, and transmitting data corresponding to the transmission destination. A means for sending the latest serial number to another computer, a means for storing the latest serial number for each source computer, and a method for comparing the received serial number of the data received from another computer with the held latest serial number. And a means for detecting omission. 9. A storage means for sequentially storing transmission data with the latest serial number, and transmission data having a serial number designated in response to a retransmission request sent due to data omission detected by another computer as retransmission data. 9. A computer according to claim 8, further comprising means for transmitting a request to another computer. 10. In a network system in which a plurality of computers are connected via a transmission path and which detects whether data transmitted from a transmitting computer has reached a receiving computer, the latest serial number is stored for each transmission destination. And a means for transmitting the transmission data sent from the first computer on the transmission side to the third computer on the reception side with the latest serial number corresponding to the transmission destination. Means for storing the latest serial number for each transmission source computer;
A third computer having means for detecting a missing data by comparing the received serial number of data received from the computer with the stored latest serial number.