JPH0370057A - Inter-computer communication system - Google Patents

Abstract

PURPOSE:To shorten time required for releasing logical connection identifier state control resource LRM and to improve efficiency for utilizing the LRM by newly defining resource, which includes cyclic order numbers in a conventional logical connection identifier LR, as an LR and setting correspondence between the LR and LRM under the condition of (n):1 [(n)>1]. CONSTITUTION:A means is provided to newly define the resource, which includes the cyclic order numbers to be independently controlled by the correspondent LRM into the conventional LR, as the LR and to set the correspondence between the LR and LRM under the condition of (n):1. Then, a means is provided to update the order numbers in the LRM corresponding to logical connection to be released. A means is provided to compare the order numbers in the LRM, which is correspondent when data units are received, with the order numbers in the LRM as a transfer destination for the unit of received data, and to inform the data units of a transmission source when the order numbers are not equal. Further, a means is provided to forcedly release the logic connection without any condition by the means itself when one computer generates system-down during communication. Thus, time required for releasing the LRM can be shortened and the efficiency for utilizing the LRM can be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an inter-computer communication system, and in particular to an inter-computer communication system in which a cyclic condition is included in the method of assigning identifiers to logical connections and allocating state management resources. Regarding.

[Conventional technology]

The conventional method for assigning logical connection identifiers (hereinafter referred to as LR) and allocating logical connection identifier state management resources (hereinafter referred to as LRM) in the intercomputer communication method is to establish a logical connection as shown in the related diagram in Figure 5. Both computers independently define LR, and have a 1:1 correspondence between LR and LRM. When a request to establish a logical connection occurs, one LR is selected from among a plurality of currently available LRs, and the logical connection, LR, and LRM are associated with each other.

In addition, in order to allocate a certain LR to a logical connection, and when the communication used by this logical connection ends, it is possible to allocate the LR that was used until the previous time to a new logical connection, it is necessary to In order to prevent incomplete release of a connection from affecting the logical connection to which a new LR has been assigned, after a certain timing (hereinafter referred to as connection release guaranteed timing) has passed after the logical connection is used, the same connection is released again. LR of
It was a method that could be used.

[Problem to be solved by the invention]

In the conventional LR assignment and LRM assignment method described above, once the assignment of a logical connection to a certain LR is finished, and in order to assign the same LR to a new logical connection, a connection release guarantee timing must be taken. Therefore, the utilization efficiency of LR is low. Furthermore, when the number of usable LRs is small and the number of logical connection establishment requests is large, there is a problem that there is a high probability that logical connection establishment will be refused due to the inability to allocate an LR.

Additionally, if the connection release guarantee timing is insufficiently long, a newly established logical connection will be affected by the logical connection to which the same LR was previously assigned, resulting in an abnormal logical connection release phenomenon. There is also.

Furthermore, if one computer experiences a system down during data communication using a logical connection and recovers from the system down state, it searches for the LR currently in use from among all the LRs owned by its own system, and communicates with it. Compare the LR status of the computer you were using and your own system,
If a contradiction occurs in the state of a logical connection, it must be resolved. Therefore, when there are many LRs in use, there is a problem that it takes time to recover from a system failure.

[Means to solve the problem]

The computer-to-computer communication system of the present invention adds L to the conventional LR.
An LRM corresponding to R that includes a uniquely managed cyclic sequence number is newly defined as LR, and means for making the correspondence between LR and LRM n:1 (n>1), and a logical connection. means for updating the sequence number in the LRM corresponding to the logical connection to be released, and when a data unit is received using the logical connection, the sequence number in the LRM corresponding to the used logical connection and the received data unit. The data unit is compared with the sequence number in the transfer destination LR, and if they are equal, normal data unit reception processing is executed, and if they are not equal, the used logical protection is
A means to send a data unit to notify that the local system is not using it as necessary, and a method for recovering from a system down state when one computer experiences a system down during data communication using a logical connection. In this case, the configuration has a means for forcibly and unconditionally releasing the logical connection from itself.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing the correspondence between logical connections, LRs and LRMs, and the relationship between LR-LRM order numbers.

This shows that two logical connections have been established between computer #A and computer #3. Also, for logical connection #1, on computer #A, L
This shows that a l r is assigned to R. In computer #B, X is assigned to LR.

FIG. 2 is a data format diagram of LR.

The LR is composed of subfields called LR, RFN and LR, SQN, and the LR and RFN correspond to the LRM on a 1:1 basis, and the state of the LR is managed by the LRM. Also, L
R and SQN are assigned the sequence number SQN value held by the LRM corresponding to LR and RFN when the logical connection is established.

FIG. 3 is a state diagram showing changes in sequence numbers when LRM#a is used twice.

FIG. 3(a) shows that on computer #A, LRM#
When the SQN of a is 6Si, a request to establish logical connector 7 is generated, LRM #a is assigned to this logical connection #m, and as a result, ai is assigned to LR. FIG. 3(b) shows the logical connection # of FIG. 3(a).
m, and in the release process, set the SQN of LRM#a to 1.
5QN=i+1. In this state, a new logical connection establishment request is generated, LRM#a is reassigned to this logical connection #n, and LR is &+
A state in which +1 is assigned is shown.

FIG. 4 is a sequence diagram for explaining establishment, data transfer, and release of a logical connection.

FIG. 4(a) is an example of a normal sequence in which a logical connection is established, data is transferred, and then the logical connection is released, and the sequence number SQN of the LRM used by computers #A and #B is This indicates that it will be updated by releasing the logical connection.

Figure 4(b) is an example in which a logical connection release error has occurred, and after the computer #B reassigns LRM#X to a low logical connection, an RLSDL message is sent to the logical connection to which LRM#x was previously assigned. is being received. Since the sequence number LR,5QN=p of the forwarding destination LR of the received RLSDL message is different from the sequence number LRM,5QN=p+1 at the time of RLSDL transmission of LRM#x,
When receiving an RLSDL message, the RLCL message is sent to the transfer source LR in the RLSD, and the previous L RM #
The logical connection to which x was allocated is released. Further, it is shown that the logical connection to which LRM #x is currently assigned is not affected by receiving the RLSD from the logical connection to which LRM #x was previously assigned.

FIG. 4(c) shows that a system down occurs on computer #B during communication after establishing a logical connection.
This is an example in which the logical connection is forcibly released only on computer #B when recovering from a system down state. In the logical connection forced release process, LRM#x
The sequence number SQN of is added by 1, and 5QN=p+1.

Furthermore, after that, a new logical connection establishment request is generated, and LRM #x is again allocated to the logical connection. In this state, when an RLSDL message is received for the logical connection to which LRM#x was previously assigned, the sequence number LR,5QN=p in the destination LR of the RLSDL message and the sequence number LR of the current LRM#x
Since M, 5QN=p+1 are different, for RLSDL tsage, as in the case of FIG. 4(b), RLCL
message is sent and the logical connection is released.

In addition, all of Fig. 1, Fig. 2, Fig. 3, and Fig. 4 are CC
Data communication between computers is assumed using the ITT Blood 7 Signal System 5CCP function.

〔Effect of the invention〕

As explained above, in the present invention, a conventional LR including a cyclic sequence number is newly defined as an LR, and the correspondence between LR, I, and RM is n:1 (n>1). By doing so, the time required to release the LRM can be shortened by 6 hours, which has the effect of improving the utilization efficiency of the LRM. Additionally, if a certain LRM is used and the same LRM is subsequently assigned to a new logical connection, it is possible to completely prevent the new logical connection from being affected by a release error in the logical connection to which the LRM was previously assigned. This invention is effective, and even when a system goes down during data communication, even if discrepancies in the management status of the same logical connection are unavoidable between communicating systems, the present invention can be applied to simplify the recovery procedure from a system down. This also has the effect of reducing system downtime because the time required for system recovery procedures can be shortened.

4 is a sequence diagram for explaining the establishment, data transfer, and release of a logical connection to which the present invention is applied. FIG. 5 is a logical connection, LR, and LRM showing conventional LR assignment and LRM assignment. FIG.

Claims (1)

[Claims] In order to establish a logical connection between multiple computers that can operate in conjunction with each other, both relevant computers independently allocate a logical connection identifier and a logical connection identifier state management resource, and the logical connection identifier is shared between the two computers. In an intercomputer communication method, at least a transfer destination logical connection identifier or a transfer source logical connection identifier is set in a data unit to be transferred using the logical connection established by notifying the logical connection of the logical connection. a first control means for including in a connection identifier a cyclic sequence number uniquely managed by the logical connection identifier state management resource corresponding to the logical connection identifier; If so, the correspondence between the logical connection identifier and the logical connection identifier state management resource is canceled, the sequence number in the logical connection identifier state management resource is updated, and the logical connection identifier state is changed in the newly established logical connection. a second control means capable of allocating the logical connection identifier having a sequence number managed by a management resource; and the sequence number included in a data unit transferred from a partner computer using the logical connection. a notification that detects that the logical connection has been released in its own system and notifies the other party computer when the order numbers held in the logical connection identifier state management resource corresponding to the transfer destination logical connection identifier are not equal; means, one of the computers experiences a system down during data transfer using the logical connection between the computers, and in order to recover from the system down, the computer that caused the system down is forced to disable the logical connection. A computer-to-computer communication system characterized by having a third control means for opening the system under certain conditions.