JPS63169145A - Setting up processing system for data communication path in network - Google Patents

Abstract

PURPOSE:To prevent the overhead of a system and the resetting up of a communication path which is not intended after the disconnecting of the communication path by providing a selection means to select an active setting up of the communication path or the setting up after the reception of a communication path set up request from the opposite of communication. CONSTITUTION:A communication system A does not execute the setting up of a communication path (transmission of CACK) as long as the system A does not receive a communication path setting up request (reception of command CNCT) from the opposite of communication even if a communication path setting up request (CONTACT) is issued. A communication system B is a system which is designated to transmit a command CNCT immediately after the issuance of a CONTACT, hence transmits a command CNCT. At the time of disconnecting a communication path, the system A is in a waiting status as shown by an arrow 40, and waits for a connection-request from the system B. As a result, the overhead of a network system caused by the issuance of a CONTACT under the condition the opposite is enable to communicate, can be reduced, and further, the unintentional resetting up of a communication path after the disconnecting of the communication path can be prevented.

Description

Detailed Description of the Invention [Summary] The present invention provides a data communication system in which computers and computers and computers and terminals are connected by, for example, a local area network. By providing a means for selecting whether to establish the communication path actively or passively after receiving a communication path establishment request from the two communication partners, it is possible to establish a communication path even when the two communication partners are unable to communicate. This solves the network system overhead caused by issuing an establishment request and the unintentional re-establishment of the communication bus after disconnecting the communication bus.

[Industrial application field]

The present invention relates to a processing method for establishing a data communication bus in a network connecting computer systems or between computer systems and terminals.

For example, in a data communication system connected by a local area network, communication systems (computer systems and terminals) having various communication processing logics are connected to perform data communication. Therefore, there is a need for a method to enable smooth data communication between such communication systems and to reduce the overhead of the entire network system.

[Conventional technology]

FIG. 4 shows a conventional data communication system connected by a local area network, and how communication paths are established and communication paths are disconnected in the data communication system. Figure (a
1 shows a configuration example of a data communication system connected by a local area network, in which one communication system LA to ID are connected by a network 2. figure(
bl shows how a communication path is established between communication systems A and B, taking two communication systems A and B in the configuration example of FIG. 9(a) as an example. In Figure (b), 9 communication system A becomes available and a communication node activation request (
ACT), but at that point, 1 communication system B is still unavailable and communication is not possible, and 1 illustrated command CNCT is retried and times out.

When the communication system B becomes available, the two systems become communicable in response to the command CNCT issued by the nine communication system B. Figure Tel shows how the communication path between communication systems A and B is disconnected, taking communication system A and communication system B as an example. 1. When communication system B issues a disconnection request to communication system A in a state where a communication path has been established between systems A and B.

Considering that communication system A may be able to communicate with communication system B again.

Issue the graphical command CNCT. As a result, depending on the configuration of communication system B, the bus may be re-established.

That is, as shown in Figure 9, in a data communication system connected by a conventional local area network.

In establishing a communication path, the command CNCT is retried a certain number of times, as shown by the arrow IO in Figure 1 (bl), and eventually times out.This is a structure with a large overhead. Furthermore, when one communication bus is disconnected, error recovery processing is activated in one communication system A by using a communication path disconnection request from two communication systems B as a trigger, as shown by the arrow 20 in Figure 1 (C1). In order to prepare for a communication path re-establishment request from communication system B, C0NTACT is issued to communication system B. As a result, the structure is such that nine communication systems B are notified of a connection request.

[1JWJi point to be solved by the invention] In a conventional data communication system connected by a local area network, there are 9 communication bus establishment requirements.

Because the structure is such that it is issued unconditionally to the communication partner system, when two communication partner systems are in a state where communication is impossible, useless processing (issuance of command CNCT and retry) is activated. . Furthermore, even if one communication partner system issues a disconnection request, a problem arises in that a connection request is immediately notified to the communication partner system.

Means for Solving Problem C] FIG. 1 is a principle diagram showing the establishment and disconnection of a communication path in a data communication system connected by two networks according to the present invention. This is a system that is specified to perform communication after receiving a communication bus establishment request from the other party.

It is assumed that communication system B is a system designated as one that unconditionally establishes a communication path by itself.

As shown in FIG. 1, a data communication system connected by a network 2 according to the present invention includes a communication system A and a communication system A designated as one that establishes a communication bus after receiving a communication path establishment request from the other party. The configuration is set in advance such that communication system B is designated as one that unconditionally establishes a communication path by itself.

[Effect]

In the present invention, even if the communication system A in FIG. 1 issues one communication path establishment request (CONTACT), it receives a communication path establishment request (command
Unless you receive T.

Establishment of a communication path (transmission of CACK) is not performed.

That is, by receiving the command CNCT while in a waiting state as indicated by the arrow 30 in FIG. 1(b),
Send CACK. 2 Communication system B is a system designated to immediately establish a communication path (send command CNCT) when a communication path establishment request (CONTACT) is issued, as shown in Figure 1 Send command CNCT.

In addition, when disconnecting the communication path, the communication system A as shown in FIG. 1 (C1) operates in the same manner as in the conventional state shown in FIG. Then, it waits for a connection request from communication system B.

〔Example〕

FIG. 2 shows an embodiment of defining a communication system according to the present invention. The partner system with which communication system A communicates is communication system B, and the communication node used for communication with two communication systems B is represented by a communication node PU (arrow 50 in the figure) defined in one communication system A. Also.

The partner system with which communication system B communicates is communication system A, and the communication node used for communication with 1 communication system A is represented by communication node PU (arrow 60 in the figure) defined in 2 communication system B. In the communication node PU to the communication system, as shown in the arrow 70, < CNCTOUT
= NO, which means that one communication path is established after receiving a communication path establishment request from the other party. Furthermore, the communication node PU of one communication system B is defined as <CNCTOUT=YES as shown by the arrow 80 in the figure, which means that it unconditionally establishes nine communication paths by itself. Although the other parameters defined in Figure 1 are not directly related to the present invention, various definitions are described regarding the type of device and the like.

In the process of establishing a communication path between communication systems A and B shown in FIG. Activation processing (ACT) is activated for the communication node PU used for communication with system B. When the activation processing is activated, a communication path with communication system B is established during the activation processing. Request (CONT
ACT) is performed. However, as mentioned above, in the definition of communication node I)U(7), CNCTOUT=NO is defined, so the establishment of the actual communication path is delayed.
There are 2 and 6 people, so there is a special stem B.

With the transition from the communication disabled state to the communication enabled state, activation processing ( ACT) is activated.

When the activation process is started, a request to establish a communication path with the communication system A (CONTACT) is made during the process. In this case, since CNCTOUT-YES is defined in the definition of the communication node PU, the CNCT command is immediately transmitted to the communication system A. On the other hand, 2 communication systems A receive a communication path establishment request from 1 communication system B (reception of CNCT)
Therefore, a request for establishment of one communication path is transmitted (transmission of CACK) to one communication system B.

As a result of the above, two communication paths are established between the systems.

In the process of disconnecting the communication path between communication systems A and B shown in FIG.
A request to disconnect the communication path between communication system B and one communication system A is issued, and a DISC command is sent to communication system A. On the other hand, in communication system A, DI
Upon reception of the SC command, 1N0P is detected in the communication path with communication system B, and error recovery processing is activated.

During the error recovery process, in order to prepare for a request to establish a communication path again from communication system B,
Start the process. However, in the definition of 9 communication node PU, since CNCTOUT-No is defined, the actual communication path is not established and the communication path goes into a waiting state. Also, in 2 communication system B.

Since the DISC command was normally accepted by communication system A, DCTD is received and as a result, the communication path is completely disconnected.

Note that the re-establishment of one communication path is triggered by a connection request issued when communication of one communication system B is restarted. Also, what are the plans for re-establishing the 9 communication bus?

This is similar to the establishment of a communication path between the communication systems A and B shown in FIG. 3 (a1).

〔Effect of the invention〕

According to the present invention, between a host computer and a host computer,
Or in a data communication system that connects a host computer and a terminal via a network.

It is possible to reduce the overhead of the network system due to issuance of a communication path establishment request in a state where the communication partner is unable to communicate, and to prevent unintended re-establishment of the communication path after the communication path has been disconnected.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle configuration of the present invention, Fig. 2 is an example of communication system definition in the case of the present invention, Fig. 3 is an embodiment showing processing of communication path establishment and disconnection, and Fig. 4 is a conventional case. An illustrative diagram is shown. In the figure, 1 is a communication system and 2 is a network. 70 and 80 each represent a definition at the communication node. 0 4?
-- 〇Communication system A Communication system BP
UADTYPE-DSLA, PI
JADTYPE-DSLA. PIJBFSZ-n, P
I, IBFsZ −n. MAXDATA-n, MAX
DATA-n. N0DADDR=(a,b) N0
DADDR-(a,b). CLIADDR-(x,y), CLI
ADDR-(x, Y). PUTYPE-z, PUTY
PE-z. Communication system definition example 2 Figure (a) Communication system Ai! Communication system B (b) implementation example

Claims (1)

[Claims] In a data communication system in which a host computer and a host computer or a host computer and a terminal are connected via a network, a communication path is established in both the host computer and/or the terminal, A means for selecting whether to actively establish a communication path or passively after receiving a communication path establishment request from the communication partner is provided, and communication in which it is specified that the communication path is to be established actively by oneself is provided. The node has communication path establishment means that issues a communication path establishment command regardless of the state of the communication partner in the process of establishing a communication path with the communication partner, and also establishes the communication path after receiving a communication path establishment request from the communication partner. A communication node designated to perform passive communication is characterized by having communication path establishment means for issuing a communication path establishment command after receiving a communication path establishment command from the other party in communication path establishment processing with the other party. A processing method for establishing a data communication path in a network.