JPS61225944A - Device for evaluating detection of collision - Google Patents

Abstract

PURPOSE:To evaluate a collision detecting circuit while the operation of LAN is reflected by providing a collision control means, a transmission start means, plural interfaces, a time measuring means and an evaluation means. CONSTITUTION:Counters 61a, 61b receive an initial value from a processor 41 to start count, output transmission start signals 51a, 52b to local area network (LAN) interfaces 42a, 42b at overflow to continue the count. In receiving collision stop signal 52a, 52b from the LAN interfaces 42a, 42b in response to the detection of collision of transceivers 32a, 32b, count stop circuits 62a, 62b stop the counting of counters 61a, 61b. In receiving the collision detection signals 52a, 52b from the LAN interfaces 42a, 42b, a processor 41 fetches the count in response to the supply timing to calculate the collision detection time. Thus, the evaluation of the collision detection circuit is applied in the LAN operating state.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a CSMA/CD type local area network in which a plurality of transceivers each having a built-in collision detection circuit are connected to a transmission line, and particularly relates to a CSMA/CD type local area network that includes a plurality of transceivers each having a built-in collision detection circuit. The present invention relates to a collision detection and evaluation device that evaluates collision detection and evaluation.

[Technical background of the invention W4] Generally, the CSMA/CD method (carrier 5et
teeIUItil)Ie＆CCe5S with c
In a local area network (hereinafter referred to as a LAN) of the transmission line (C+Etectton) system, a communication station (transmission station) that has a packet to be transmitted monitors a carrier on a transmission path and determines whether the transmission path is in use. If there is no carrier on the transmission path, the transmitting station assumes that the transmission path is empty and transmits the packet. On the other hand, if there is a carrier on the transmission path, the transmitting station determines that the transmission path is in use, and waits until the transmission path becomes vacant before transmitting. At this time, if two or more stations transmit almost simultaneously, packet collision will occur on the transmission path. In this case, a collision detection circuit built into the transceiver in the transmitting station detects the collision, which causes each transmitting station to enter a retransmission procedure. In other words, each transmitting station stops transmitting,
Wait a suitable time and try sending again. Therefore, if the collision detection circuit misses a collision, retransmission will not be performed and the packet will be lost on the transmission path. Therefore, evaluation of the collision detection circuit (for example, measurement of collision detection rate and collision detection time) is important.

Evaluation of a conventional collision detection circuit will be explained with reference to FIG.

In FIG. 3, 11 is a transmission line. Transceivers 12a, 12b, . . . are connected to the transmission line 11.

Each of the transceivers 12a, 12b, . . . has a built-in collision detection circuit (not shown) for detecting a data (packet) collision on the transmission line 11.

When evaluating the collision detection circuits of the transceivers 12a and 12b, a collision detection evaluation device 20 is connected to the transceivers 12a and 12b. The collision detection evaluation device 20 includes a pulse generator 21 and a collision detection signal measuring device 22. Further, the pulse generator 21 is a pulse generator 23.2.
4 and a control circuit 25 that controls the same pulse generators 23 and 24.
It has The control circuit 25 simultaneously activates the pulse generators 23, 24 during the evaluation of the collision detection circuit. This causes the pulse generators 23 and 24 to
A pulse train (as transmission data) is generated from 5 until a stop command is given. A pulse train from the pulse generator 23 is output to, for example, a transceiver 12a, and sent onto the transmission line 11 by the transceiver 12a. At this time, the pulse train from the pulse generator 24 is output to, for example, the transceiver 12b, and sent onto the transmission line 11 by the transceiver 12b. As a result, a collision occurs on the transmission line 11. A collision detection signal measuring device 22 is connected to the transceivers 12a and 12b, and the transceiver 1
2a.

By the collision detection signal from each collision detection circuit in 12b,
It is measured whether each collision detection circuit correctly detects a collision.

[Problems with the Background Art] As mentioned above, in the conventional collision detection evaluation device, the data pattern is constant because the transmission data is generated by a pulse generator, and the transmission timing of the two transceivers is the same, so collisions occur. The timing is also uniquely determined. However, during actual LAN operation, the data pattern and length of the packet, as well as the data transmission timing of each transceiver, are random. For this reason, conventional collision detection and evaluation devices have a problem in that evaluations that reflect actual operating conditions cannot be performed.

[Object of the Invention] This invention has been made in view of the above circumstances, and its purpose is to evaluate the collision detection circuit built into the transceiver by
The object of the present invention is to provide a collision detection meter 1illi device that can perform collision detection in a state that reflects the actual operation of N.

[Summary of the Invention] According to the present invention, there is provided a collision detection and evaluation device that is applied to a CSMA/CD type local area network in which a plurality of transceivers each having a built-in collision detection circuit are connected to a transmission path.

The collision detection evaluation device includes a control means for performing collision control, a transmission activation means, a plurality of interfaces provided in one-to-one correspondence with some of the plurality of transceivers, a time measurement means, and an evaluation means. have.

The control means specifies the time difference between the transmission activation timings of each of the interfaces to the transmission activation means during the collision detection evaluation, and supplies independent arbitrary data for transmission to each of the interfaces. The transmission activation means activates transmission to each of the interfaces at each designated time difference in response to the time difference designation from the control means.

The interface activated for transmission by the transmission activation means sends a packet corresponding to the data supplied to the interface from the control means to the corresponding transceiver, and causes the collision detection circuit of the transceiver to detect a collision during the packet transmission period. A collision detection signal is output accordingly.

The time measuring means measures the time from when each of the interfaces starts transmitting to when the collision detection signal is output. The evaluation means evaluates the collision based on the measurement results of the time measurement means.
Evaluate the detection circuit.

[Embodiments of the invention] An embodiment of the present invention is shown in FIG. 1(a) below.

This will be explained with reference to (b).

Figure 1<a) shows a CSMA/CD system LAN.
The configuration is shown below. In the figure, 31 is a transmission path such as a coaxial cable. A plurality of transceivers 32a, 32b, .

The transceivers 32a, 32b, . . . each have a built-in collision detection circuit (not shown) that detects data (packet) collisions on the transmission line 31.

When evaluating the collision detection circuits of the transceivers 32a and 32b, a collision detection evaluation device 40 is connected to the transceivers 32a and 32b. The collision detection evaluation bag [40 has a collision detection evaluation bag 40 that controls the entire device and also performs collision detection evaluation, a LAN interface 42a, 42b, and a transmission activation/time measurement circuit 43.

LAN interface 42a, 42b c, processor 4
A transmission activation signal 5 from the transmission activation/time measurement circuit 43 receives transmission data from 1 and transmits a packet corresponding to the data.
Transceiver 32a according to 1a, 51b.

32b. The AN interfaces 42a, 42b also have the function of notifying the processor 41 and the transmission activation/time measuring circuit 43 of collision detection signals 52a, 52b in response to collision detection notifications from the collision detection circuits of the transceivers 32a, 32b.

The transmission start/time measurement circuit 43 includes a counter 4 that can be initialized by the processor 41, as shown in FIG. 1(b).
4, and registers 45a and 45b for latching the count value of the counter 44 in response to collision detection signals 52a and 52b from the LAN interfaces 42a and 42b. The counter 44 is configured to output, for example, a transmission activation signal 51a to start counting according to the initial setting from the processor 41, and to output a transmission activation signal 51b at the time of overflow to continue counting. Further, the contents of the registers 45a and 45b are led to the processor 41.

Next, the operation of one embodiment of the present invention will be explained.

When evaluating the collision detection circuit, the processor 41 in the collision detection evaluation bag [40] first sends the first transmission data to the LAN interface 42a and the second transmission data to the LAN interface 42b.
transmission data respectively.

Subsequently, the processor 41 activates the transmission activation/time measurement circuit 43
Set an arbitrary initial value to the counter 44 in the counter 4.
Start 4. As a result, the counter 44 outputs the transmission activation signal 51a and starts a counting operation (for example, a count-up operation). When the counter 44 eventually overflows, it outputs the collision detection signal 51b and continues counting from the count value O. Therefore, the counter 44 outputs the transmission activation signal 51 with a time difference proportional to the maximum countable value of the counter 44 - the initial value.
a and 51b are output. Therefore, when the initial value is the maximum value, the transmission activation signals 51a and 51b are output simultaneously (ie, with a time difference of O). The counter 44 may initially count down, and when it reaches under 70, output the transmission activation signal 51b and perform a count-up operation.

A transmission activation signal 51a from the counter 44 is supplied to the LAN interface 42a. As a result, the LAN interface 42a is activated, and the first
The first packet corresponding to the transmission data is output to the transceiver 32a. The transceiver 32a transmits the first packet from the LAN interface 42a onto the transmission line 31. In addition, the transmission start signal 5 from the counter 44
1b is supplied to the LAN interface 42b. As a result, the LAN interface 42b is activated and outputs the second packet corresponding to the second transmission data from the processor 41 to the transceiver 32b. Transceiver 3
2t) sends out the second packet from the LAN interface 42b onto the transmission line 31.

As the transceiver 32a sends the first packet and the transceiver 32b sends the second packet onto the transmission line 31, a collision occurs on the transmission line 31, and each collision detection circuit (not shown) of the transceivers 32a and 32b When the occurrence of this collision is detected in step 1), a collision detection signal is generated. Collision detection signals from transceivers 32a, 32b are routed to corresponding LAN interfaces 42a, 42b to notify collision detection. LAN interface 42a
, 42b are the transceiver 32a during the packet transmission period,
The collision detection signal from 32b is monitored, and if the same signal is supplied during the packet sending period, the collision detection signal 52a
, 52b to the processor 41 and the transmission activation/time measurement circuit 43.

The collision detection signal 52a from the LAN interface 42a supplied to the transmission start/time measurement circuit 43 is sent to the register 4.
5a, whereby the current count value of the counter 44 is latched into the register 45a. Similarly, the collision detection signal 52b from the LAN interface 42b supplied to the transmission start/time measurement circuit 43 is sent to the register 45b.
As a result, the current count value of the counter 44 is latched into the register 45b.

The processor 41 has a LAN interface 42a.

When the collision detection signals 52a and 52b are supplied from the register 42b, the register 45a responds to the respective supply timings.

45b and calculate the collision detection time.

The processor 41 has LAN interfaces 42a and 42b.
The data pattern of the transmission data given to, its data length,
Furthermore, a counter 44 (of the transmission start/time measurement circuit 43)
By variously changing the initial values given to , various collision states reflecting the actual operating form of the LAN can be realized. By repeating the above-described operations in this state, the processor 41 obtains the collision detection rate and calculates the statistical value of the collision detection time.

On the other hand, if no collision is detected by the transceivers 32a, 33b during the packet transmission period from the interfaces 42a, 42b, the interfaces 42a, 42b notify the processor 41 that no collision has been detected.

Note that the calculation of the collision detection time in the above operation description refers to the calculation of the collision detection time obtained by subtracting the delay time of the transmission path 31, for example, in addition to the calculation of the time from sending a packet until the collision signal is output. That is, calculation of the collision detection time of the collision detection circuits of the transceivers 32a and 32b is also included. FIG. 2 shows a modification of the transmission activation/time measurement circuit 43 of FIG. 1(b). The transmission start/time measurement circuit in Figure 2 includes:
In order to distinguish it from the transmission start/time@measuring circuit 43 of FIG. 1(b), it is given the reference numeral 43'. The transmission start/time measurement circuit 43' includes counters 61a and 61b that can be initialized by the processor 41, and a LAN interface 42.
A count stop circuit 62a stops the force run 1 operation of the counters 61a, 61b in response to collision detection signals 52a, 52b from 'a, 42b.

62b. The counters 61a and 61b each receive an initial value from the processor 41 and start counting, and when an overflow occurs, the transmission activation signal 51a,
51b to the LAN interfaces 42a and 42b to continue counting. In this case, the transmission activation signal 51a
, 51b is proportional to the difference between the two initial values.

The count stop circuits 62a and 62b are connected to the transceiver 32.
LAN interface 4 in response to collision detection between a and 32b.
When the collision detection signals 52a, 52b are supplied from the counters 2a, 42b, the counting operations of the counters 61a, 61b are stopped. The processor 41 has a LAN interface
When the collision detection signals 52a, 521) are supplied from the counters 61a, 42b, the count values of the counters 61a, 81b are taken in according to the respective supply timings, and the collision detection time is calculated.

In addition, in the above embodiment, the case of collision detection evaluation in the case of collision due to 2(lIll packets) was explained.
This invention can also be applied to evaluation of collisions of three or more packets.

[Effects of the Invention] As detailed above, according to the present invention, collisions between packets that are not just pulse trains can be realized, and the data pattern and data length of the transmission data that is the source of the packets can be arbitrarily varied. The timing of collision can be varied by setting an arbitrary time difference in the activation timing for packet transmission to each transceiver. Therefore, according to the present invention, the evaluation of the collision detection circuit built into the transceiver (collision detection rate, collision detection time, etc.) can be performed in a state that reflects the actual operation of the LAN.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram of a LAN according to an embodiment of the present invention, FIG. 1(b) is a block diagram of a transmission activation/time measurement circuit shown in FIG. 1(a), and FIG. 3 is a diagram showing a modified example of the transmission activation 7/time measuring circuit, and FIG. 3 is a diagram showing a conventional example. 31... Transmission path, 32a, 32b... Transceiver, 40... Collision detection evaluation device, 41... Processor, 42a, 42b... LAN interface, 43.
43'... Transmission start/time measurement circuit, 44.6fa,
61b...Counter. Applicant's agent Patent attorney Takehiko Suzue Figure 1 (b)

Claims (1)

[Claims] A control means for performing collision detection control in a CSMA/CD type local area network in which a plurality of transceivers each having a built-in collision detection circuit are connected to a transmission line;
The control means is provided in one-to-one correspondence with some of the plurality of transceivers, and sends a packet corresponding to arbitrary data independently given to each of the plurality of transceivers at the start of transmission to the corresponding transceiver during the packet sending period. a plurality of interfaces that output collision detection signals in response to collision detection by the collision detection circuit; transmission activation means for activating transmission on each of the interfaces at time differences respectively designated by the control means; Collision detection evaluation characterized by comprising: time measuring means for measuring the time from the time to when a collision detection signal is output, and evaluation means for evaluating the collision detection circuit based on the measurement results of the time measuring means. Device.