JPH0630471B2 - Optical repeater for star coupler - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical repeater for a star coupler that relays a packet signal by coupling a star coupler on a lower network side and a star coupler on a lower network side. .

[Conventional technology]

FIG. 5 shows the configuration of the conventional optical repeater for star couplers disclosed in, for example, "Study of 1811 inter-star optical connection repeater using different wavelengths" in the research paper of the IEICE General Conference in 1985. It is a block diagram shown. In the figure, 1 is an optical repeater for a star coupler (hereinafter referred to as a repeater), 2 is a lower network side transmission circuit, 3 is a lower network side electric-optical conversion circuit, 4 is a filter, 5 is a lower network side receiving circuit. , 6 is a lower network side optical-electrical conversion circuit, 7 is a filter, 8 is a lower network side carrier detection circuit, and 10 is a collision detection circuit which is a pattern generation circuit (hereinafter referred to as a pattern generation circuit) for generating a pattern including a code rule violation that is easy to detect collision. , JAM signal generating circuit), 13 is an upper network side transmitting circuit, 14 is an upper network side receiving circuit, 15 is an upper network side carrier detecting circuit, and 16 is a code rule violation of an output signal of the upper network side receiving circuit 14. An upper network side collision detection circuit for detecting a collision by discriminating, 17 is a gate circuit, 18,
19 is a lower network side device, 20 is a lower network side star coupler, 2
Reference numerals 1 and 22 are upper network side devices, and 23 is a higher network side star coupler.

Next, the operation of the conventional star coupler optical repeater shown in FIG. 5 will be described. Communication between devices controlled by the CSMA / CD system starts transmission if there is no signal on the transmission path, and normally completes transmission if no collision occurs. However, when two or more stations start transmission almost at the same time and a collision occurs during transmission, the procedure is to stop transmission and retransmit after waiting time.

First, a normal relay operation from the lower network side device to the upper network side device will be described. An optical signal (wavelength λ ₁ ) output from the lower network side device 18 is input to the lower network side receiving circuit 5 via the lower network side star coupler 20, passes through the filter 7, and is transmitted to the lower network side optical circuit. The electric conversion circuit 6 converts the electric signal. The output signal of the lower network side receiving circuit 5 after being photoelectrically converted by the lower network side optical-electrical converting circuit 6 is inputted to the lower network side carrier detecting circuit 8 and the upper network side transmitting circuit 13.
The lower network side carrier detection circuit 8 makes its output significant from the output signal of the lower network side reception circuit 5, and outputs it to the gate circuit 17. The upper network side transmission circuit 13 electro-optically converts the output signal of the lower network side reception circuit 5 (having a wavelength λ ₁ ) and outputs it to the upper network side star coupler 23. The optical signal output from the upper network side transmitting circuit 13 is received by the upper network side devices 21 and 22 via the upper network side star coupler 23, and is also received by the upper network side receiving circuit 14. The optical signal received by the upper network side receiving circuit 14 is optoelectrically converted, and the upper network side carrier detecting circuit 15, the upper network side collision detecting circuit 16 and the gate circuit 1 are provided.
It is output to 7. The upper network side carrier detection circuit 15 makes its output significant from the output signal of the upper network side reception circuit 14,
Output to the gate circuit 17. Upper network side collision detection circuit 16
Does not make its output significant from the output signal of the upper network side receiving circuit 14, and outputs it to the gate circuit 17. Gate circuit 17
Indicates that the output of the lower network side carrier detection circuit 8 is significant, the output of the upper network side carrier detection circuit 15 is significant, and the output of the upper network side collision detection circuit 16 is not significant. No signal is output to the transmission circuit 2 on the lower network side so that a cyclic collision of signals does not occur.

Next, a normal relay operation from the upper network side device to the lower network side device will be described. The optical signal (wavelength λ ₁ ) output from the upper network side device 21 is optically transmitted by the upper network side receiving circuit 14.
Electrically converted and output. Upper network side carrier detection circuit 1
5 makes the output significant from the output signal of the upper network side receiving circuit 14 and outputs it to the gate circuit 17. The upper network side collision detection circuit 16 does not make its output significant from the output signal of the upper network side receiving circuit 14, and outputs it to the gate circuit 17. In the gate circuit 17, the output of the lower network side carrier detection circuit 8 is not significant, the output of the upper network side carrier detection circuit 15 is significant, and the output of the upper network side collision detection circuit 16 is not significant. The output signal of the receiving circuit 14 is output to the lower network transmitting circuit 2. Lower network side transmission circuit 2, the lower network side electric - converted by the optical converter circuit 3 into an optical signal (the wavelength lambda _2), the wavelength lambda ₁ of the wavelength lambda ₂ of the optical signal by the filter 4
, And outputs it to the star coupler 20 on the lower network side. The output signal of the transmission circuit 2 on the lower network side having the wavelength λ ₂ passes through the star coupler 20 on the lower network side, and the devices 18 and 1 on the lower network side.
Received at 9. Similarly, the signal is also input to the lower network side receiving circuit 5, but the filter 7 removes the wavelength λ ₂ component and no signal is output from the lower network side receiving circuit 5. Therefore, a collision due to signal circulation does not occur in the upper network side star coupler 23.

Next, the relay operation to the upper network side when the lower network side devices collide with each other will be described. The optical signal collided by the lower network side star coupler 20 is optoelectrically converted by the lower network side receiving circuit 5. The lower network side carrier detection circuit 8 is the lower network side reception circuit 5
Output signal of the gate circuit 17
Output to. The upper network side transmission circuit 13 electro-optically converts the output signal of the lower network side reception circuit 5 as it is, and outputs it to the upper network side star coupler 23. Here, the lower network side receiving circuit 5
The output optical signal of is a signal of a higher level if the collision generated in the lower network side star coupler 20 is a collision of optical signals with different levels, but in the case of collision of signals of the same level, The signal includes a code rule violation due to overlapping signals. Therefore, the output signal of the upper network side transmission circuit 13 may include a code rule violation.

Upper network transmission circuit 1 received by upper network reception circuit 14
The output signal of 3 is optoelectrically converted, and the lower network side carrier detection circuit 15, the upper network side collision detection circuit 16 and the gate circuit 1 are provided.
It is output to 7. The lower network side carrier detecting circuit 15 makes its output significant by the output signal of the upper network side receiving circuit 14. The upper network side collision detection circuit 16 is a higher network reception circuit 14.
If the output signal of 1 contains a violation of the coding rule, the output is significant, and if the violation of the coding rule is not included, the output is not significant. The gate circuit 17 outputs the lower network side carrier detection circuit 8 and the upper network side carrier detection circuit 15.
The output state of the upper network side collision detection circuit 16 is checked, and if the output of the lower network side collision detection circuit 16 is significant, the output of the JAM signal generation circuit 10 is output to the lower network side transmission circuit 12.
If the output of the upper network collision detection circuit 16 is not significant, nothing is output to the lower network transmission circuit 2. Lower network side transmission circuit 2
Converts the JAM signal into electric light and outputs it to the lower network side star coupler 20.

Next, the relay operation to the lower network side when the upper network side devices collide with each other will be described. The optical signal collided by the upper network side star coupler 23 is optoelectrically converted by the upper network side receiving circuit 14 and output to the upper network side carrier detection circuit 15, the upper network side collision detection circuit 16 and the gate circuit 17. The upper network side carrier detection circuit 15 makes its output significant by the output signal of the upper network side reception circuit 14. Upper network side collision detection circuit 16
Makes the output significant by the output signal of the upper network side receiving circuit 14. The gate circuit 17 is a higher network collision detection circuit 16
Is significant, the output of the JAM signal generation circuit 10 is selected and output to the lower network side transmission circuit 2. The lower network side transmission circuit 2 converts the JAM signal into an electric-optical signal and outputs it to the lower network side star coupler 20.

Since the above operation is performed, when a collision occurs between the lower network side devices 18 and 19, the repeater 1 outputs a JAM signal to the lower network side star coupler 20 and the respective lower layers until the JAM signal stops. It cannot be retransmitted to the network side devices 18, 19.

[Problems to be solved by the invention]

Since the above-described conventional optical coupler for star coupler is configured as described above, when relaying a collision between the lower network side devices 18 and 19 to the upper network side, the upper network side can detect the collision. However, since the JAM signal is output to the lower network side, there is a problem that the throughput is reduced.

The present invention has been made to solve such a problem, and an object thereof is to obtain an optical repeater for a star coupler that does not reduce the throughput even when a collision occurs between devices on the lower network side.

[Means for solving problems]

The optical coupler for a star coupler according to the present invention monitors the coding rule with the output of the upper network side receiving circuit as an input, and when a coding rule violation is detected, a code for correcting and outputting the coding rule violation. A rule violation correction circuit is provided, and the output of the code rule violation correction circuit is input to the upper network side transmission circuit.

[Action]

In the star coupler optical repeater of the present invention, when a collision occurs between devices on the lower network side, a code rule violation for a code rule violation that occurs is detected, and the code rule violation is corrected by a code rule violation correction circuit. Therefore, a signal that does not violate the coding rule is input to the upper network transmission circuit.

〔Example〕

FIG. 1 is a block diagram showing the configuration of an optical repeater for a star coupler which is an embodiment of the present invention. In the figure, reference numerals 1 to 8, 10, 13 to 23 are the same as those of the conventional example shown in FIG. 9 receives the output of the lower network side receiving circuit 5 as an input, and when the output of the lower network side receiving circuit 5 contains a coding rule violation, corrects the coding rule violation and outputs it to the upper network side transmitting circuit 13. A code rule violation correction circuit, 11 is an identical polarity continuous detection circuit, and 12 is an exclusive OR circuit (hereinafter referred to as a first EXOR).

FIG. 2 is a circuit configuration diagram showing an example of a code rule violation correction circuit in the star coupler optical repeater of FIG. In the figure, 24 is a first flip-flop (hereinafter, referred to as a first F-flop).
/ F), 25 is the second FXOR, and 26 is the second F
/ F, 27 is a third FXOR, 28 is a NOR circuit (hereinafter,
Reference numeral 29 is an AND circuit (hereinafter referred to as ABD).

FIG. 3 is a time chart showing the output of each section in the coding rule violation correction circuit of FIG.

Next, the operation of the optical repeater for a star coupler according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. 2 and 3. The normal relay operation from the lower network side device to the upper network side device, the normal relay operation from the upper network side device to the lower network side device, and the relay operation to the upper network side when the upper network side devices collide This is the same as the above-mentioned conventional example.
The relay operation to the upper network side in the case where the lower network side devices having different operations from those of the conventional example collide with each other will be described. The optical signal is collided by the star coupler 20 on the lower network side, and the optical signal is optoelectrically converted by the receiving circuit 5 on the upper network side. The lower network side carrier detection circuit 8 makes its output significant by the output signal of the lower network side reception circuit 5, and outputs it to the gate circuit 17 and the code rule violation correction circuit 9. The coding rule violation correction circuit 9 corrects the coding rule violation generated in the output signal of the lower network side receiving circuit 5 due to the signal collision between the lower network side devices and outputs the operation to the upper network side transmitting circuit 13. This will be described with reference to the circuit configuration diagram of the Manchester code rule coding rule violation correction circuit 9 shown in FIG. 2 and the time chart shown in FIG.

When the collision occurs, the output 5a of the lower network side receiving circuit 5 has a coding rule violation that is not Manchester-coded data that the same polarity of 3 bits or more continues. In FIG. 2, the output 5a of the receiving circuit 5 on the lower network side
Is input to one input of the first EXOR 12, and the output of the same polarity continuous detection circuit 11 is input to the other input. At the output of the first EXOR 12, an output 12a in which the same polarity continuity of 3 bits or more contained in the output 5a of the lower network side receiving circuit 5 is corrected is obtained. That is, in the same polarity continuous detection circuit 11, the output 1 of the first EXOR 12
2a is stored in the first F / F 24, and its output 24a is obtained. By the second EXOR 25, the polarities of the output 5a of the lower network side receiving circuit 5 and the output 24a of the first F / F 24 (that is, the output 5a at the present time and the output 12 one bit before)
As a result of determining whether the (polarity of a) matches or does not match, the second E
The output 25a of the XOR 25 is obtained. Similarly, the first F
The output 24a of the / F24 is stored in the second F / F26,
The output 26a of the second F / F 26 is obtained. Third EX
The OR 27 matches the polarities of the output 24a of the first F / F 24 and the output 26a of the second F / F 26 (that is, the polarities of the output 12a one bit before and the output 12a two bits before),
As a result of the determination of non-coincidence, the output 2 of the third EXOR 27
7a is obtained. The output 28a of the NOR 28 is the output 5a of the lower network side receiving circuit 5 and the output 24a of the first F / F 24.
And a signal that becomes significant when the polarities of the 3 bits of the output 26a of the second F / F 26 match. The output 29a of the lower network side carrier detection circuit 8 by the AND 29 is the output 29 of the AND 29 as a continuous detection signal of the same polarity in a significant section.
a is obtained. AN as this same polarity continuous detection signal
When the output 29a of D29 becomes significant, the polarity of the output 5a of the lower network side receiving circuit 5 is inverted by the first EXOR 12, so that the output 12a of the first EXOR 12 has the same polarity continuity of 3 bits or more corrected. The obtained signal is obtained.

Therefore, the signal input to the upper network transmission circuit 13 does not include any coding rule violation. The upper network side transmission circuit 13 carries out an electro-optical conversion of the input signal and outputs it to the upper network side star coupler 23. The output signal of the upper network side transmitting circuit 13 is received by the upper network side receiving circuit 14 via the upper network side star coupler 23, is optically-electrically converted by the upper network side receiving circuit 14, and is in the upper network side carrier detecting circuit. 15, lower network side collision detection circuit 1
6, output to the gate circuit 17. The upper network side carrier detection circuit 15 makes its output significant by the output signal of the upper network side reception circuit 14. Since the lower network collision detection circuit 16 receives a signal that does not violate the coding rule, its output is not significant. Therefore, the gate circuit 17 does not output anything to the lower network side transmission circuit 2.

Here, with respect to the embodiment of the present invention and the conventional example, the operation in the case where a collision occurs between the devices on the lower network side is compared using the _Time- S _pace diagram, and it is shown that the throughput is improved by implementing the present invention. explain.

FIG. 6 shows T in the case of the optical repeater for star coupler of FIG.
FIG. 7 is a diagram showing an _ime- S _pace diagram, and FIG. 7 is a diagram showing a T _ime- S _pace diagram in the case of the star coupler optical repeater of FIG. In each figure, t ₁ is a signal propagation delay time from the lower network side device 18 to the lower network side star coupler 20, t ₂ is a signal propagation delay time from the lower network side device 19 to the lower network side star coupler 20, and t _L Is a signal propagation delay time from the lower network side star coupler 20 to the repeater 1,
t _H is the signal propagation delay time from the repeater 1 to the upper network side star coupler 23, and Δt is the lower network side devices 18 and 1, respectively.
Difference in time 9 has started transmission, T _C is the lower network side device 1
8, 19 is a time from when a collision is detected to when transmission is stopped, T _i is an interval time until the next packet can be transmitted after the lower network side devices 18 and 19 finish receiving, Δd is a propagation delay time generated in the repeater 1.

In FIG. 6, the time until the next packet can be transmitted after the collision occurs is obtained. The time 18a at which the lower network device 18 starts transmission is set to time 0. The time 19a at which the lower network device 19 starts transmission is Δt. The time 18b when the lower network device 18 starts receiving is 2t ₁ . The time 18c at which the lower network side device 18 starts receiving the collision signal is Δt + t ₂ + t ₁ . Lower network side device 1
The time 18d when 8 stops transmitting is Δt + t ₂ + t ₁ + T
It becomes _C. Time 19 when the lower network device 19 stops transmission
d becomes Δt + 2t ₂ + T _C. Time 18e when the lower network side device 18 finishes receiving the signal from the lower network side device 19
Becomes _{△ t + 2t 2 + T C} + t 2 + t 1. Therefore, the time 18g at which the lower network device 18 can transmit again is Δ
a _{t + 2t 2 + T C +} t 2 + t 1 + T i.

Similarly, in FIG. 7, the time until the transmission becomes possible again after the collision occurs is obtained. Here, the points having the same reference numerals as in FIG. 6 are at the same time. The time 1a when the repeater 1 starts reception on the lower network side is t ₁ + t _L. The time 1b at which the repeater 1 starts transmission to the upper network side is t ₁ + t _L + Δd. The time 1c at which the repeater 1 starts to receive the signal colliding with the lower network side is Δt + t ₂ + t _L. Time 1 when the repeater 1 starts transmitting a signal including a coding rule violation to the upper network side
d is Δt + t ₂ + t _L + Δd. Time 1e when the repeater 1 starts reception on the upper network side is t ₁ + t _L + Δd + 2t
_H. The time 1f at which the repeater 1 starts receiving the signal including the coding rule violation on the upper network side is Δt + t ₂ + t _L + Δd.
A + 2t _H. The time 1g at which the repeater 1 starts transmitting the JAM signal to the lower network side is Δt + t ₂ + t _L + Δd + 2t.
_H + Δd. Time 1h the relay 1 has finished receiving the lower network side is a _{△ t + 2t 2 + T C} + t 2 + t L. The time 1i when the repeater 1 finishes the reception on the upper network side is Δt + 2
t ₂ + T _C + t ₂ + t _L + Δd + 2t _H. Time 1j that relay 1 stops to output the JAM signal to the lower network side, _{△ t + 2t 2 + T C} + t 2 + t L + △ d + 2t H
+ Δd. Therefore, the time 18f the lower network side device 18 ends the reception _{△ t + 2t 2 + T C} + t 2 + t L + △
d + 2t _H + Δd + t _L + t ₁ and the lower network device 1
At time 18h when the packet can be transmitted again at 8, Δt
_{+ 2t 2 + T C + t} 2 + t L + △ d + 2t H + △ d + t
It becomes _L + T _i . Comparing the time 18g with the time 18h, 2 (Δd + t _H + t _L ), that is, the signal from the lower network side is relayed by the relay device 1 from the lower network side star coupler 20 and returned to the lower network side star coupler 20 again. It can be seen that the throughput of the conventional example is reduced by the time required to come.

Although the coding rule violation correction circuit 9 is connected between the upper network side receiving circuit 5 and the upper network side transmitting circuit 13 in the above embodiment, as shown in FIG. The following effects can be obtained by connecting 30 between the upper network side receiving circuit 14 and the gate circuit 17 or between the gate circuit 17 and the lower network side transmitting circuit 2. That is, when a collision occurs between the devices on the upper network side, continuous signals of the same polarity may be output from the upper network side receiving circuit 14 for a long time depending on the condition of the collision. When the polarities of consecutive signals having the same polarity are the same as those in the idle state, the lower network side transmission circuit 2 stops transmission. Lower network side device 18
In Nos. 19 and 19, when there is no received signal, the transmission mode is set, and if there is a pursuit of transmission, transmission is started, re-collision occurs on the upper network side, and throughput is lowered. Since the coding rule violation correction circuit 30 operates so that the transmission to the lower network side does not stop, the above-mentioned decrease in throughput can be prevented. In FIG. 4, 30 is a code rule violation correction circuit, 31 is a same polarity continuous detection circuit, and 32 is a fourth EX.
It is OR.

〔The invention's effect〕

As described above, according to the present invention, in a star coupler optical repeater, when a collision occurs between lower network side devices and a code rule violation occurs in the output of the lower network side receiving circuit, a code rule violation correction circuit is used. Since it is configured to correct the coding rule violation and output it to the upper network side, when a collision occurs between devices on the lower network side, it is possible to obtain an optical repeater for a star coupler that does not reduce the throughput. Is played.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an optical repeater for a star coupler according to an embodiment of the present invention, and FIG. 2 is a circuit showing an example of a code rule violation correction circuit in the optical repeater for a star coupler of FIG. FIG. 3 is a configuration diagram, FIG. 3 is a time chart showing the output of each section in the coding rule violation correction circuit of FIG. 2, and FIG. 4 is a block diagram showing the configuration of an optical repeater for a star coupler which is another embodiment of the present invention. FIG. 5 is a block diagram showing a configuration of a conventional star coupler optical repeater, and FIG. 6 is a diagram showing a T _ime -S _pace diagram in the case of the star coupler optical repeater of FIG. 1, FIG. FIG. 6 is a diagram showing a T _ime -S _pace diagram in the case of the star coupler optical repeater of FIG. 5; In the figure, 1 ... Star coupler optical repeater, 2 ... Lower network side receiving circuit, 3 ... Lower network side electrical-optical conversion circuit, 4
...... Filter, 5 ...... Lower network side receiving circuit, 6 ...... Lower network side optical-electrical conversion circuit, 7 ...... Filter, 8 ...... Lower network side carrier detection circuit, 9 ...... Code rule violation correction circuit, 10 …
... Pattern generation circuit (JAM signal generation circuit) that generates a pattern including a code rule violation that is easy to detect collision in the collision detection circuit, 11 ... Same polarity continuous detection circuit, 12 ... First
Exclusive OR circuit (EXOR), 13 ... Upper network side transmitting circuit, 14 ... Upper network side receiving circuit, 15 ... Upper network carrier detecting circuit, 16 ... Upper network side collision detecting circuit, 1
7 ... Gate circuit, 18, 19 ... Lower network side device, 20
...... Lower network side star coupler 21,22 ...... Upper network side device, 23 ...... Upper network side star coupler, 24 ...... First flip-flop (F / F), 25 ...... Second EXOR,
26: second F / F, 27: third EXOR, 28
... NOR circuit (NOR), 29 ... AND circuit (AN)
D), 30 ... Code rule violation correction circuit, 31 ... Same polarity continuous detection circuit, 32 ... Fourth EXOR. In the drawings, the same reference numerals indicate the same or responsible parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 63-281541 (JP, A) JP 61-58343 (JP, A) JP 62-49739 (JP, A) JP 59- 165537 (JP, A)

Claims (3)

[Claims] 1. A high-order network side star coupler and a low-order network side star coupler are coupled and bidirectionally encoded data is converted into a CS.
In an optical repeater for a star coupler that relays in the MA / CD system, a light source that outputs a wavelength that is different from the wavelength of the light source of the devices connected to the star coupler on the lower network side and that can be received by this device is selected. The lower network side transmission circuit used and a lower layer connected with a filter for removing the wavelength component of the light source of the lower network side transmission circuit and passing the wavelength component of the light source of the device connected to the lower network side star coupler Network side receiver circuit, lower network side carrier detection circuit that determines the presence or absence of signals on the lower network side by using the output of the lower network side receiving circuit as input, and the output of the lower network side signal circuit as input, and monitors the code rule In addition, when a code rule violation is detected, a code rule violation correction circuit that corrects the code rule violation and outputs it, and a light source that outputs a wavelength that can be received by the devices connected to the upper side star coupler Using It is possible to receive the wavelength of the light source of the device connected to the upper network side transmission circuit and the upper network side star coupler that receives the output of the above coding rule violation correction circuit and the wavelength of the light source of the above upper network side transmission circuit. High-level network side receiving circuit, a high-level network side collision detection circuit for detecting a mutual collision of the high-level network side device by identifying a coding rule violation, and a fixed pattern generation circuit for outputting a signal including the coding rule violation And the output of the fixed pattern generation circuit and the output of the upper network side reception circuit as input, the output of the lower network side carrier detection circuit, the output of the upper network side carrier detection circuit and the output of the upper network side collision detection circuit. Are used as control signal inputs, the output of the upper network side carrier detection circuit becomes significant after the output of the lower network side carrier detection circuit becomes significant, and the output of the upper network side collision detection circuit is present. If not, nothing is output, and when the output of the upper network side collision detection circuit becomes significant, a gate circuit for outputting the output of the fixed pattern generation circuit to the lower network side transmission circuit. An optical repeater for a star coupler, which is characterized in that 2. The coding rule violation correction circuit is also provided between the upper network side receiving circuit and the gate circuit, or between the gate circuit and the lower network side transmitting circuit. An optical repeater for a star coupler according to claim 1. 3. The coding rule violation correction circuit receives the output of the lower network side reception circuit as an input, and when the same polarity code continues in a 3-bit section, the output is toggled with an initial value being an insignificant state. It is constituted by a polarity continuity detection circuit, an exclusive OR circuit in which the output of the lower network side reception circuit and the output of the same polarity continuity detection circuit are input and the output is connected to the higher network side transmission circuit. An optical repeater for a star coupler according to claim 1, characterized in that.