JPH0697764B2 - D channel contention control test method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a test method of whether or not each terminal of ISDN has a D-channel contention control function, and more specifically, each of ISDN terminals. In order to test whether or not the D-channel contention control function possessed by the terminals is normal, each terminal outputs data to the D-channel at the same time, and a contention state is generated between the terminals.

[Prior Art] According to CCITT-I.430, when a terminal starts communication, D
It is necessary to output control data to a control bit called a channel. At this time, a plurality of terminals may start to output data to the D channel at the same time, which may cause a race condition between the terminals. Therefore, each terminal has a contention control function specified in CCITT-I.430, and prevents malfunction due to contention.

Next, the connection state between the terminal and the DSU will be described with reference to FIG.
In FIG. 2, 1 is a terminal and 2 is a DSU. According to CCITT-I.430, up to eight terminals 1 can be connected to one DSU2.

Each terminal 1 is connected to DSU2 by T line and R line, sends data to DSU2 through T line, and receives data from DSU2 through R line. The T line and the R line form a data bus.

Next, the main part of the frame structure according to FIG. 3 / I.430 of CCITT-I.430 will be described with reference to FIG. Frame from terminal 1
It is composed of a frame A for sending data to the DSU2 and a frame B for sending data from the DSU2 to the terminal 1. The frame A has a D channel and the frame B has an E channel.

When the terminal 1 transmits data to the D channel of the frame A, the DSU 2 loops back the same data as the E channel of the frame B through the R line. Each terminal 1 constantly monitors the E channel data of frame B. If the terminal 1 does not use the D channel of frame A, the terminal 1 continues to send data "1" to the D channel of frame A.

The ISDN terminal, which is the object of the present invention, transmits data in synchronization with one clock, sends a pattern unique to each terminal to the D channel, and the DSU sends the D channel pattern to the E channel as it is.

When the terminal 1 recognizes that the E-channel data of the frame B is data "1" a certain number of times in succession, it determines that communication with the DSU2 is possible, and the D-frame of the frame A
Send data to the channel.

During data transmission, the terminal 1 compares the transmitted D channel data with the R channel E channel data, and if they match, continues transmitting data. In this state, the other terminals use frame A
, The D channel cannot be used, and a waiting state is set.

Further, when the patterns of the terminals that have simultaneously issued requests overlap on the D channel, the terminal 1 survives only the pattern of the specific terminal by the mechanism in which “0” is stronger than “1”.
Only the terminal that gets on the channel and has the same E-channel and D-channel pattern is permitted to communicate, and the other terminals are in the waiting state again because the E-channel and D-channel patterns do not match. The transmission data of each terminal is not lost, and it seems that there is no conflict.

In this way, in the case where a plurality of terminals 1 connected to the DSU2 try to start communication at the same time, each terminal 1 uses CCITT
-Has a function of avoiding contention with each terminal 1 according to the procedure of D channel contention control as specified in I.430.

Conventionally, the communication line test in the configuration shown in FIG. 2 is performed by connecting a communication line tester such as a protocol analyzer to the T line and the R line and monitoring the line data, for example, according to the CCITT-I.430 standard. Analyze if it is working.

CSMA / CD (Carrier Sense Multiple Access with Collision Detection Function) is designed to minimize the phenomenon of transmission data collision. When collision occurs, two or more data transmission equipment The transmitted data physically collides with each other, destroying each other and the transfer fails.

[Problems to be Solved by the Invention] When a plurality of terminals 1 simultaneously start communication,
Whether the contention avoidance function of each terminal 1 operates according to CCITT-I.430, that is, when one of the terminals 1 becomes able to transmit data to the DSU after a D channel contention condition occurs. If you want to test whether other terminals are in a waiting state, etc., multiple terminals 1 connected to DSU2
Need to send out data at the same time. However, since each terminal performs an operation of outputting data simultaneously by a tester, it is very difficult to test for a race condition that can be performed only when a plurality of terminals start outputting data at the same time.

An object of the present invention is to provide a method of causing each terminal 1 to transmit data at the same time so as to generate a contention state between the terminals in order to test whether or not each terminal 1 has a normal D channel contention control function. To do.

[Means for Solving the Problems] In order to achieve this object, according to the present invention, a plurality of terminals 1 are connected to a DSU by a bus of T line and R line, and each terminal 1 has a pattern unique to each terminal on a D channel. Then, the DSU sends the D channel pattern to the E channel as it is, and when the patterns of the terminal 1 that simultaneously issued the request on the D channel overlap, the “0” is stronger than the “1” and the specific terminal 1 Only the pattern of survives on the E channel,
In the ISDN home data line where the terminal 1 whose channel and D channel patterns match is allowed to communicate, the tester 3 that connects to the T line and R line buses and monitors the line data is The data and the T-line D-channel folding signal are input, and the multiplexer 4 that outputs the data or the T-line D-channel folding signal by the control signal of the controller 6, and the output of the multiplexer 4 are input,
A D channel race condition generating section having an output circuit 5 for connecting the output to the R line is provided. First, the multiplexer 4 converts the data into the R line output and puts it in the E channel, and each terminal 1 is called to the tester 3. Then, the multiplexer 4 stops the transmission of the data, sets each terminal 1 in a communicable state, and simultaneously sends a data signal from each terminal 1 to the T line D.
Send to channel to test.

[Operation] Next, the D channel competition control test method according to the present invention will be described with reference to FIG. Reference numeral 3 in FIG. 1 is a tester, and other parts are the same as those in FIG. The tester 3 is provided with a D channel race condition generator, and is connected to the T line and the R line in the same manner as the DSU2 in FIG. That is, the tester 3 operates as a pseudo DSU.

Next, the configuration of the D channel race condition generating section of the tester 3 will be described with reference to FIG. 4 in FIG. 4 is a multiplexer, 5
Is an output circuit, and 6 is a controller. The multiplexer 4 receives the data "0" and the D-channel data of the T line, and extracts the data "0" or the T-line D-channel return data by the control signal of the controller 6. The output circuit 5 assembles the signal from the multiplexer 4 into a frame format specified in CCITT-I.430.

The data “0” input to the multiplexer 4 is given by a data generator (not shown) or the like, and the T-line D-channel return data is transmitted among a plurality of terminals connected to the T-line. This is the output data of the enabled terminal.

When starting the test, first, the controller 6 sets the data of the output of the multiplexer 4 to "0" and transmits the data "0" to the E channel. In this state, connect the other terminal 1 to the tester 3
In response to the call request, the tester 3 transmits data "0" indicating that the D channel of the T line is in use to the E channel, so that each terminal 1 enters the waiting state.

After putting all the terminals 1 connected to the tester 3 into the waiting state, the controller 6 stops the transmission of the data “0” and switches to the T-line D channel return data side. As a result, the terminals 1 in the waiting state simultaneously enter the transmission state for the T-line D channel, and a D channel contention state occurs between the terminals. The tester 3 monitors the data of the T line and the R line in this state, and performs the test in the competitive state.

[Effect of the Invention] According to the present invention, the tester is provided with the D channel race condition generating section which is composed of the multiplexer, the output circuit and the controller, and is connected to the bus. Data “0” is output to D
Put the channel into a pseudo use state, put each terminal in the call request state to the tester, put all the terminals in the waiting state, switch the multiplexer output with the controller, and return the T-line D channel. Since data is output to the E channel and the use state of the D channel is stopped and data signals are simultaneously transmitted from each terminal, the contention state can be surely generated between the terminals, and the D channel contention that each terminal has. The control function can be easily tested.

[Brief description of drawings]

FIG. 1 is an explanatory view of a D channel contention control test method according to the present invention, FIG. 2 is a connection state diagram of a DSU and a terminal, and FIG. 3 is a CCI.
FIG. 4 is a main diagram of a frame configuration according to FIG. 3 / I.430 of TT-I.430, and FIG. 4 is a configuration diagram of a D channel race condition generation unit of the tester 3. 1 ... Terminal, 2 ... DSU, 3 ... Tester, 4 ... Multiplexer, 5 ... Output circuit, 6 ... Controller.

Claims (1)

[Claims] 1. A plurality of terminals (1) are connected to a home data line terminating device (hereinafter referred to as "DSU") by buses of T line and R line, and each terminal (1) has a D channel with a pattern unique to each terminal. Then, the DSU sends the D channel pattern to the E channel as it is, and when the patterns of the terminal (1) that simultaneously issued the request on the D channel overlap, "0" is specified by a mechanism stronger than "1". Only the pattern of the terminal (1) survives and rides on the E channel, and the terminal (1) whose E channel and D channel patterns match is allowed to communicate IS
In the DN's home data line, the tester (3) that is connected to the T and R line buses and monitors the line data receives the data indicating that the line is in use and the T line D channel loopback signal as input, and the controller A multiplexer (4) that outputs the data or the T-line D-channel folding signal by the control signal of (6), and an output circuit (5) that inputs the output of the multiplexer (4) and connects the output to the R line. A D channel race condition generation unit is provided, and first, the multiplexer (4) outputs the data to the R line and puts it in the E channel to put each terminal (1) into a call request state to the tester (3). In addition, the transmission of the data is stopped by the multiplexer (4), each terminal (1) is set in a communicable state, and a data signal is simultaneously transmitted from each terminal (1) to the T-line D channel for testing. D channel conflict control test method according to.