JPS6331336A - Network simulator - Google Patents

Abstract

PURPOSE:To efficiently perform simulation without increasing a time required for the simulation to an infeasible extent, by operating each communication node of a network perfectly in parallel and asynchronously. CONSTITUTION:Node processing means 110-112, and application processing means 120-122 are constituted of processor units. An execution managing means 100 makes the node processing means, and the application processing means execute asynchronously. A simulator managing means 101 sends out information required for the simulation by a communication path means 130, to each of the node processing means, and sets a logical communication path between the node processing means so as to form a network desired to simulate. An execution managing means 100 freezes an operating state at every constant time, and simultaneously starts up the simulator managing means 101, and collects the state of each node process by the communication path means 130, then informs it to a user.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a network simulator for verifying and evaluating distributed control algorithms in a network.

(Prior Art) In a loosely coupled network, communication nodes basically have autonomy. Therefore, the nodes are running in parallel and asynchronously with each other. For example, network simulators are used to evaluate the validity and performance of algorithms such as distributed access control and distributed reliability control in such networks. In this network simulator, it is necessary to simulate the asynchronous parallel operation of the communication nodes described above, and it is also necessary to take into account the delay that always exists in an actual communication channel. In other words, the above-mentioned communication path delay, the execution time of algorithms such as access control or reliability control executed in a distributed manner at each communication node, and the execution order across all communication nodes, etc.
The uncertainty associated with asynchronous concurrency must be taken into account. In conventional sequential processing type simulators, each communication node process is sequentially executed and simulated at sufficiently small intervals to monitor the state of the nodes, and the simulation for the sufficiently small interval is used to monitor the state of the nodes.
- After one round of nodes, all the states of each communication node were collected and used as the state of the network in that time interval. Here, the communication node process refers to software for simulating control procedures to be performed by a communication node on an actual network. In addition, by changing the parameters in the simulator, we can simulate the execution time, execution order, and causality of state transitions between communication nodes in all cases, and take into account the asynchronous parallel operations and uncertainties mentioned above. The above has been realized.

(Problems to be Solved by the Invention) In the above-described sequential processing type simulation, simulations are sequentially performed for each sufficiently small time period for all communication nodes forming the network. Furthermore, in order to take into account the above-mentioned uncertainty that is essential for simulating a loosely coupled network,
It was necessary to simulate every possible combination of parameters. For this reason, the structure of the simulator becomes complicated, and the time required for simulation increases exponentially, especially when the network to be simulated becomes large-scale.

The purpose of the present invention is to provide an environment close to the actual system by making each communication node of the network perform completely parallel and asynchronous operations in order to simulate accurately, and the time required for simulation is unrealistic even when the network becomes large. The goal is to make it possible to perform efficient simulations.

(Means for Solving the Problem) The present invention provides a plurality of node process means corresponding to communication nodes of a network to be simulated, and an application process connected to the node process means for realizing functions within the communication nodes. means, communication path means for connecting all of the node process means, and execution management connected to each of the node process means and each of the application process means, for causing the node process means and the application process means to execute asynchronously and in parallel. means, and simulator management means connected to the node process means, for connecting the node process means in an arbitrary manner by the communication path means, and for notifying the user of the network simulator of the operating status of the node process means. It is characterized by consisting of.

(Operation) As an example of access control in a computer network, polling control in a network configuration as shown in FIG. 4 is widely known. Here, in order to trace how the polling control algorithm is executed, the operation will be described in a case where the network simulator according to the present invention is used.

The computer network shown in FIG. 4 is configured by connecting a plurality of terminal concentrators 402 and 403 to one central processing unit 401 via an input line 410 and an output line 420. Here, the terminal line concentrators 402 and 403 have a function of accommodating a plurality of terminals.

The central processing unit 401 transmits a polling signal to each terminal concentrator. On the other hand, each terminal line concentrator sends a message to the central processing unit 4 only when it receives a polling signal addressed to itself.
It is possible to send a signal to 1. Furthermore, when the central processing unit 401 learns that the transmission of a signal from one terminal concentrator has ended, it transmits a polling signal to the next terminal concentrator, and thereafter repeats polling control in this manner to communicate with all terminal concentrators. Do the following.

A case where the execution status of polling control in the computer network described above is traced using the network simulator according to the present invention shown in FIG. 1 will be described. In a computer network that performs access control using polling control, its functions include:
A communication node function that controls physical communication such as sending signals to a desired terminal concentrator and receiving signals from a desired terminal concentrator, and ensuring that the communication is fair and reliable for all terminal concentrators. Access control functions can be broadly divided into two: This network simulator provides a node process means for the communication node, and an application process means for the access control function.

The user of the network simulator informs the simulator management means 101 shown in FIG. 1 of the network connection status shown in FIG.
1 and the terminal line concentrators 402 and 403 perform the polling control execution procedure. The simulator management means 101 uses, for example, the node process means 110 and the application process means 120 to simulate the operation of the central processing unit 401, and uses the node process means 110 and the application process means 120 to simulate the operation of the terminal line concentrators 4Q2 and 403, respectively. It is assumed that processing means 111, 112 and application processing means 121, 122 are used.

Next, the simulator management means 101 logically sets the network connection state as follows. That is, the simulator management means 101 controls the central processing unit 401
1 from the node process means 110 corresponding to 1. Logical communication paths are set for all node processing means 111 and 112 corresponding to each terminal line concentrator. Also, node processing means 111, 112, 113 corresponding to each terminal concentrator
From there, a logical communication path is set for the node processing means 110 corresponding to the central processing unit 401. In this way, the physical communication path of the computer network shown in FIG. 4 is logically set on the network simulator.

Furthermore, the simulator management means 101 further controls the central processing unit 401 and the terminal concentrator 402 that have been notified by the user.
The polling control procedure executed by 403 is notified to the application process means corresponding to each device. That is, the application process means 120 that simulates the central processing unit 401 is given a processing procedure for transmitting a polling signal to each terminal concentrator, and the application process that simulates each terminal concentrator 402 and 403 is given a processing procedure for transmitting a polling signal to each terminal concentrator. The means 121 and 122 are provided with a processing procedure for detecting a polling signal addressed to itself from among the observed polling signals, and transmitting the signal to the central processing unit 401, for example, when the polling signal is detected. It will be done.

After the initial settings of the network simulator are completed as described above, the simulator management means 101 instructs the execution management means 100 to start the network simulator.

The execution management means 100 causes each node process means and each application process means to operate in parallel, and also causes the simulator management means 101 to operate for a certain period of time every preset period. An inquiry is made as to the operating status of polling control of the application process means.

The operational status of the polling control inquired at this time includes, for example, the identifier of the terminal concentrator being polled at that time, the polling cycle of each terminal concentrator, etc. Based on this information, the user can determine the operation of the polling control. You can understand the status.

In the polling control described above, the validity of the algorithm itself is already clear. However, if a failure occurs in the central processing unit that is about to implement polling control, or if a failure occurs in the communication link itself, the simple polling control described above cannot recover. Therefore, by adding a timeout function to the simple polling control described above, or even multiplexing central processing units and adding control to change to a standby central processing unit when a failure occurs, It becomes possible to obtain high reliability. When the control procedure is complicated in this way,
Although it is no longer possible to theoretically verify the validity of the control procedure, this network simulator makes it possible to verify the validity by notifying each application process means of the control procedure and having it execute it. moreover,
Since the network status is observed at regular intervals,
An evaluation of the time efficiency of this algorithm can also be performed.

(Embodiment) FIG. 1 is a functional block diagram showing an example of the basic configuration of a network simulator according to the present invention.

In FIG. 1, node processing means 110, 111, 112,
Application process means 120, 121, 122
is composed of, for example, an independent processor unit.

In FIG. 1, the communication path means 130 connects the simulator management means and all the node process means by path-type coupling, as an example. In FIG. 1, the execution management means 100 first causes the node process means and the application process means to execute asynchronously. This means that, for example, the execution management means 100 may individually send independent tarocks to the processor units constituting the node process means and the application process means via the control line 14.
This is possible by giving 0, 141, 142, 150, 151°152, respectively. Next, the simulator management means 101 sends information necessary for simulation by the communication path means 130 to each node process means. The information here is unique to each node process, and refers to, for example, the identifier of an adjacent node process used to set up a logical transmission path described below, or an algorithm to be verified. The algorithm further includes passes 160,
161 and 162, it is sent to the application process. Here, the above information is provided, as in the second embodiment shown in FIG. It is also possible to separately send the information necessary for the processing to the node process means and the application process means.

For example, in the above example, the identifier of the adjacent node is sent by the communication path means 210 to the node process means, and the algorithm to be verified is sent by the communication path means 211 to the application process means. Next, the simulator management means 101 sets logical communication paths between the node process means in the following manner so as to form a network to be simulated. First, simulator management means 101
For example, by providing a path arbitration device in the LAN, and allocating the right to use the communication path 130 to each node process means in accordance with a request from the node process means, the node process means can be assigned to a desired node process means corresponding to a desired network topology. be able to send messages to. In this way, a logical communication path forming a network to be simulated on the communication path 130 is set. In addition, in order to notify the user of the network simulator of the operating status of each node process means, the execution management means 100
Freezes the operating states of all node process means and application process means for a certain period of time at regular intervals, and at the same time starts the simulator management means 101 and collects the state of each node process by the communication path means 130. Notify the user.

FIG. 3 shows a third embodiment of the present invention. FIG. 3 shows a case where there are four node process means and four application process means. In the example shown in FIG. 3, there are four node process means 310, 311, 312, 313
are communication path means 330, 331, 332, 333, 33
4,335 are connected to form a complete graph.

Furthermore, paths 336, 337, 338, and 339 are provided between the simulator management means and each node process means, which are used to collect information necessary for initializing the simulation and the operating status of each node process means. Here, the logical communication path is set as follows. For example, the node process means 310.312,31
3, 311, the simulator management process means 301 first connects the node processes 310 through the path 336 to the node processes 311, 312 that are adjacent on the network to be simulated. gives an identifier. Furthermore, it is also notified that the inner node processing means 311 is located on the upstream side and the node processing means 312 is located on the downstream side.

In other words, the node process means 313 connected to the node process means 310 by the communication path means 335 is not logically adjacent to the node process means 310, and receives messages from the communication path 330. 333 indicates that a message is to be sent. By giving this information to each node process, each node process is logically connected on a loop. In a similar manner, the node processing means can be coupled into any shape of network form, such as a mesh type.

(Effect of the invention) The effects of the above simulator will be shown below.

The simulator of the present invention provides an environment close to the actual system by making each communication node of the network perform completely parallel and asynchronous operations in order to accurately simulate, and the time required for simulation is unrealistic even when the network becomes large. It is possible to perform efficient simulation without increasing the value to a certain value.

Furthermore, by logically setting communication paths, it is possible to set the topology of the desired network to be simulated, so the network topology has flexibility to change.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing a first embodiment of a simulator according to the invention, FIG. 2 is a functional block diagram showing a second embodiment of a simulator according to the invention, and FIG. 3 is a functional block diagram showing a second embodiment of a simulator according to the invention. FIG. 4 is a functional block diagram showing the third embodiment, and FIG. 4 is a diagram showing one example of access control in a computer network. In the figure, 100.300...execution management means, 110.111,112,310,311,312,3
13... Node process means, 120.121, 122, 320, 321, 322, 3
23... Application process means, 130.210, 211, 330, 331, 332, 3
33,334,335,336,337°338.33
9... Communication path means, 140.141, 142, 150, 151, 152, 1
60,161,162...Control path, 401...Central processing unit, 402.403...Terminal line concentrator, Fig. 4 Central processing unit

Claims (1)

[Scope of Claims] 1. A plurality of node process means corresponding to communication nodes of a network to be simulated, an application process means connected to the node process means for realizing functions within the communication nodes, and all of the above. a communication path means for connecting each of the node process means; an execution management means connected to each of the node process means and each of the application process means for causing the node process means and the application means to execute asynchronously and in parallel; The simulator management means is connected to the network simulator, connects the node process means in an arbitrary manner by the communication path means, and notifies the user of the network simulator of the operating state of the node process means. network simulator. 2. The execution management means activates the simulator management means for a certain period of time at regular intervals, notifies the user of the network simulator of the operating state of the node process means, and when the simulator management means is not executed. 2. The network simulator according to claim 1, wherein said node process means and said application process means are executed in parallel asynchronously. 3. The simulator management means sets, for each node process means, a logical communication path between the node process means and an adjacent node process means based on the form of the network to be simulated, and The identifier and access order information of the communication path means are notified to the node process means, and each of the node process means receives the message input from the communication path means set in the node process and the message from the node process according to the access order information. 3. The network simulator according to claim 1, wherein the network simulator is configured to cause the communication path means to perform communication between the node processes.