JP2000092094A - Ethernet(r) transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently transmit and receive data mutually between terminals in Ethernet(R). SOLUTION: This Ethernet(R) transmitter-receiver is incorporated inside the terminals 1 and 13 connected to the Ethernet(R), is provided with a reception buffer 8 for writing a packet 17 received from the other terminal connected to the Ethernet(R) and reading the written packet 17 from a data processing part 3 and a transmission buffer 9 for storing the packet sent to the Ethernet(R) and is applied to the Ethernet(R) transmitter-receiver 4a for executing back pressure processing when the reception buffer 8 becomes full. Then, it is provided with terminal number detection means 15 and 16 detecting the number of the terminals connected to the Ethernet(R) from the packet received from the Ethernet(R) and a back pressure processing stop means 10a for stopping the back pressure processing when the number of the terminals detected by the terminal number detection means exceeds the threshold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal connected to an Ethernet, and more particularly to an Ethernet transmitting / receiving apparatus incorporated in the terminal for transmitting and receiving packets between the Ethernet and a data processing unit in the terminal.

[0002]

2. Description of the Related Art Generally, a plurality of terminals are connected to Ethernet which is a kind of communication network. Data transmission is performed between the terminals in accordance with the procedure and data format specified in Ethernet or IEEE802.3.

[0003] Referring to FIG.
The data transmission between and will be described.

[0004] In the terminal 1, a data processing unit 3 that actually performs various types of information processing, and an Ethernet transmitting / receiving device 4 that transmits and receives a packet containing data between the data processing unit 3 and the Ethernet 2 are provided. Is incorporated.

In the n-Ethernet transmitting / receiving device 4, for example, an F terminal having a receiving terminal 6, a transmitting terminal 7, and N storage areas is provided.
A reception buffer 8 comprising an IFO register and a transmission buffer 9 also comprising a FIFO register having M storage areas are incorporated. The transceiver 5 has a function of performing transmission and reception with respect to the Ethernet 2 separately.

Each packet into which the data flowing on the Ethernet 2 is incorporated is sequentially written into the empty storage area of the receiving buffer 8 via the receiving terminal 6 via the transceiver 5 as a receiving packet. The data processing unit 3 performs data processing by reading out the packets written in the respective storage areas of the reception buffer 8 in the order of writing. When the packet is read, the free storage area of the reception buffer 8 increases.

[0007] A packet in which data to be transmitted from the data processing unit 3 to another terminal via the Ethernet 2 is incorporated is written into an empty storage area of the transmission buffer 9. Each packet written in the transmission buffer 9 is read out by the transceiver 5 via the transmission terminal 7 and is read by the CSMA / CD.
According to the system, Ethernet 2 is transmitted at the transmittable timing.
Output to

Since the operation of writing a packet received from the Ethernet 2 into the reception buffer 8 and the operation of the data processing unit 3 reading data from the reception buffer 8 are asynchronous, when a new packet is received from the Ethernet 2, The reception buffer 8 may be full. In such a case, (a) discard the received packet.

(B) Perform back pressure processing to cause the source terminal to retransmit the packet.

When (a) is performed, when a communication abnormality is detected by an upper layer protocol such as connection-type TCP / IP of a network layer incorporated in the terminal of the transmission source of the corresponding packet, and retransmission of the corresponding packet is performed. Is carried out. However, since this method is implemented by software, a large amount of processing time is required. Further, the processing load on the CPU increases. Also, connectionless UDP
If the protocol is adopted, there is a concern that the program will be terminated prematurely.

FIG. 14 is a schematic configuration diagram of the Ethernet transmission / reception device 4 in which the back pressure processing function of (b) is incorporated. In the Ethernet transmission / reception device 4, in addition to the reception buffer 8 and the transmission buffer 7, the control unit 10, J
The UM pattern generator 11 and the selector 12 are incorporated.

The control unit 19 constantly monitors the reception buffer 8, and when a new packet is received when the reception buffer 8 is full, the control unit 19 switches the selector 12 to the JUM pattern generation unit 12 side, for example, a 32-bit data. The JUM pattern data 14 is output to the Ethernet 2 via the transmission terminal 7 and the transceiver 5.

That is, the Ethernet transmission / reception device 4 intentionally outputs the JUM pattern data 14 to the Ethernet 2 during data reception, thereby intentionally causing a collision with a transmission packet on the Ethernet 2 and transmitting the packet to the terminal at the transmission source. To retransmit the packet.

Since the retransmission of this packet is performed in hardware at the data link layer which is a lower protocol of the network layer, the retransmission is performed at high speed and the CP
There is no burden on U.

[0015]

However, FIG.
The following problems still exist in the Ethernet transmitting / receiving device 4 shown in FIG.

That is, when the number of storage areas in the reception buffer 8 is increased, the probability that the reception buffer 8 becomes full decreases, but the storage capacity of the reception buffer 8 has a certain limit. Therefore, with a certain probability, the reception buffer 8 becomes full and it is inevitable that the back pressure process is performed.

If only one to several terminals are connected to the Ethernet 2, the Ethernet 2
Even if the JUM pattern data 14 is output onto the Ethernet 2 by executing the back pressure processing of the Ethernet transmitting / receiving device 4 of each terminal connected to the
Only the UM pattern data 14 collides with the packet which should originally collide. And it hardly affects data communication between other terminals.

However, when a large number of terminals 1 and 13 are connected to the Ethernet 2 as shown in FIG. In this state, if the reception buffer 8 of the terminal 1 becomes full and the JUM pattern data 14 is output on the Ethernet 2 while the terminal 1 is performing data communication with the terminal 13 of A, the JUM pattern data Of course, the probability that the terminal 14 collides with a packet from another terminal 13, as well as a packet transmitted and received between the terminal 13 of B and the terminal 13 of C, for example, increases.

In this case, even if the reception buffer 8 in the terminal 13 of B and the terminal 13 of C is not full, B
Terminal 13 or the terminal 13 of C transmits the packet again. At this time, if there is no free storage area in the reception buffer 8 of the terminal 1, the JUM pattern data 14 is output to the Ethernet 2 again. The output again from the terminal 13 collides again with the packet.

As described above, there is a concern that the collisions occur in a chain, and eventually the operation of the entire Ethernet 2 stops, resulting in a system down.

The present invention has been made in view of such circumstances, and by monitoring the state of the Ethernet, by changing the response at the time when the reception buffer in each terminal becomes full, An object of the present invention is to provide an Ethernet transmission / reception device that can retransmit a packet from a transmission source without causing a system down of the Ethernet and at the most efficient time without burdening the CPU when the reception buffer becomes full. .

[0022]

According to the present invention, a packet received from another terminal connected to the Ethernet and incorporated in the terminal connected to the Ethernet is written and written from the data processing unit. It has a reception buffer from which packets are read, and a transmission buffer into which packets output from the data processing unit are written and at which the written packets are sent out to the Ethernet at a predetermined timing, so that the reception buffers become full. Then, the present invention is applied to an Ethernet transmitting / receiving apparatus that performs a back pressure process.

In order to solve the above problem, in the Ethernet transmitting / receiving apparatus of the present invention, the terminal number detecting means for detecting the number of terminals connected to the Ethernet from the packet received from the Ethernet, and the terminal number detecting means are provided. Back pressure processing stopping means for stopping the back pressure processing when the number of detected terminals exceeds the threshold value.

In general, when a large number of terminals are connected to the Ethernet, the probability that the JUM pattern data output on the Ethernet will collide with a packet which should not collide as described above increases.

Therefore, in the present invention, when the number of terminals exceeds the threshold value, the back pressure processing is stopped. Therefore, it is possible to prevent the Ethernet system from going down.

In this case, the received packet is simply discarded without being written to the reception buffer. In such a state, the packet transmission source terminal does not receive a response from the transmission destination terminal. Therefore, as described in the above section (a), the network layer incorporated in the packet transmission source terminal is used. The communication abnormality is detected by an upper-layer protocol such as connection-type TCP / IP, and the corresponding packet is retransmitted.

As a result, there is a disadvantage that the transmission processing time increases and the processing load on the CPU increases, but the disadvantage is much smaller than the disadvantage of the system down of the Ethernet.

In another aspect of the present invention, the terminal number detecting means in the above-mentioned Ethernet transmitting / receiving apparatus includes: an address extracting means for extracting a source address from a received packet; An address memory for storing different addresses and a counter for counting the number of addresses stored in the address memory are provided.

In the Ethernet transmission / reception device configured as described above, it is not necessary to separately provide a device for detecting the number of terminals for Ethernet.

In still another aspect of the present invention, there is provided an address memory clearing means for clearing the address stored in the address memory at a constant cycle.

In the thus configured Ethernet transmitting / receiving apparatus, even if a new terminal is newly connected to the Ethernet or the connected terminal is removed, the Ethernet transmitting / receiving apparatus is currently connected to the Ethernet. The number of terminals in use is automatically grasped.

Therefore, it is possible to more accurately determine whether or not the above-described back pressure process can be performed.

In still another invention, the address is stored in a state where the address is converted into a hash value.

In the thus configured Ethernet transmitting / receiving apparatus, the storage capacity of the address memory can be reduced.

Further, in the Ethernet transmitting / receiving apparatus of another invention, the ON / OFF state of the carrier flowing on the Ethernet is determined.
Carrier state monitoring means for monitoring the OFF state, communication amount detection means for detecting the communication amount on the Ethernet from the ON / OFF state of the carrier monitored by the carrier state monitoring means, and communication amount detection means within a specified time. A back pressure process stopping means is provided for stopping the back pressure process when the detected traffic exceeds the threshold value.

In the thus configured Ethernet transmitting / receiving apparatus, the actual traffic on the Ethernet is detected. When the traffic exceeds the threshold, the back pressure process is stopped.

Conversely, even when a large number of terminals are connected to the Ethernet, if the number of operating terminals is small, no particular problem occurs even if the back pressure process is performed. In this way, by performing the back pressure process as long as the situation of the Ethernet permits, the processing efficiency of data transmission and reception between terminal devices in the entire Ethernet can be improved.

[0038] In another embodiment of the present invention, a collision detecting means for detecting collision of packets flowing on the Ethernet, and when the number of collisions detected by the collision detecting means within a specified time exceeds a threshold value, a back-up is performed. There is provided back pressure processing stopping means for stopping the pressure processing.

In the thus configured Ethernet transmitting / receiving device, the JA transmitting / receiving device that outputs the data on the Ethernet itself is used.
If the number of collisions on the Ethernet, including the collision related to the M pattern data, exceeds the threshold value, there is a concern that system down will occur. In this case, the back pressure process is stopped.

According to still another aspect of the present invention, the back pressure processing stopping means includes a threshold value setting means for setting a threshold value for stopping the back pressure processing based on an external instruction.

In the thus configured Ethernet transmitting / receiving apparatus, the administrator of the Ethernet can arbitrarily change the threshold value for stopping the back pressure processing as needed.

In the Ethernet transmitting / receiving apparatus according to still another aspect of the present invention, an address extracting means for exceeding a destination address from a packet received from the Ethernet, and a self-set destination address extracted by the address extracting means are received by itself. Back pressure processing stopping means for stopping the back pressure processing when the destination address of the packet to be transmitted is not the destination address.

In the Ethernet configured as described above, if the destination address of the received packet is not a preset destination address related to itself, there is no problem even if the received packet is discarded. Therefore, under this condition, the back pressure process is not performed.

[0044]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a terminal in which an Ethernet transceiver according to a first embodiment of the present invention is incorporated. The same parts as those of the conventional terminal shown in FIG. 14 are denoted by the same reference numerals. Therefore, the detailed description of the overlapping part is omitted.

In the Ethernet transmission / reception apparatus 4a of the first embodiment, the reception buffer 8, the transmission buffer 9,
Control unit 10a, JAM pattern generation unit 11, selector 1
2, a hash operation unit 15 and an address memory 16
Is provided.

The packet 17 flowing on the Ethernet 2 has the format shown in FIG. That is, the first 7
A byte preamble 17a is set, a 1-byte SFD 17b is set second, a destination address (DA) 17c of 6 bytes is set third, and a source address (SA) 17d of 6 bytes is set fourth. Thereafter, data 17f is set, and finally, pads 17g, F
CS17h is set.

In the Ethernet transmission / reception device 4a of FIG. 1, the hash calculator 15 includes, for example, a 48-bit source address (for example, 48-bit address) incorporated in the packet 17 shown in FIG. 2 received from the Ethernet 2 via the transceiver 5 and the receiving terminal 6. SA) 17e is extracted, and a known hash calculation is performed on the 48-bit source address (SA) 17e, for example, a 12-bit source address (S
A) Convert to 17e and send to address memory 16.

The address memory 16 has a large number of storage areas, and writes the source address (SA) input from the hash calculator 15 into each storage area. However, if the same source address (SA) has already been written in the storage area, in order to avoid duplicate storage,
The source address (SA) input this time is discarded. Therefore, after a certain period of time, most of the terminals 1 connected to the Ethernet 2 are stored in the address memory 16.
Will be stored.

The control unit 10a constantly monitors the reception buffer 8 and the reception terminal 6, and when a new packet is received at the reception terminal 6 when the reception buffer 8 is full, the transmission data stored in the address memory 16 is stored. Original address (S
It is determined whether or not the number of terminals indicated by A) exceeds a predetermined threshold position.

As shown in FIG. 3A, when the number of terminals 13 connected to the Ethernet 2 does not exceed a predetermined threshold, the selector 12 is set to JU.
Switching to the M pattern generation unit 11, for example, outputs 32-bit JUM pattern data 14 to the Ethernet 2 via the transmission terminal 7 and the transceiver 5.

On the other hand, as shown in FIG. 3B, when the number of terminals 13 connected to the Ethernet 2 exceeds a predetermined threshold value, switching to the selector 12 is not performed. As a result, the selector 12 is connected to the transmission buffer 9 side.

In the thus configured Ethernet transmitting / receiving apparatus 4a of the first embodiment, each packet 17 flowing on the Ethernet 2 is emptied into the receiving buffer 8 via the receiving terminal 6 via the transceiver 5 as a received packet. Are sequentially written to the storage area. The data processing unit 3 performs data processing by reading out the packets written in the respective storage areas of the reception buffer 8 in the order of writing. When the packet is read, the free area of the reception buffer 8 increases.

A packet containing data to be transmitted from the data processing unit 3 to the Ethernet 2 is transmitted to the transmission buffer 9.
Is written to an empty storage area. Each packet written in each storage area of the transmission buffer 9 is read by the transceiver 5 via the transmission terminal 7 and output to the Ethernet 2 at a transmittable timing according to the CSMA / CD system.

When the number of terminals indicated by the number of source addresses stored in the address memory 16 exceeds the threshold value when a new packet 17 is received when the reception buffer 8 is full. Has stopped the back pressure process. Therefore, the system down of the Ethernet 2 can be prevented.

In this case, the received packet 17 is only discarded without being written into the reception buffer 8. In such a state, as described above, the packet 17
Since the source terminal 1 has no response from the destination terminal,
As described in the above section (a), the corresponding packet 1
7, a communication abnormality is detected by an upper-layer protocol such as connection-type TCP / IP of a network layer incorporated in the transmission source terminal 7 and retransmission of the corresponding packet 17 is performed.

As a result, there is a disadvantage that the transmission processing time increases and the processing load on the CPU increases, but the disadvantage is much smaller than the disadvantage of the Ethernet system down.

The address memory 16 stores the source address 17 in a state converted into a hash value. Therefore, the storage capacity of the address memory 16 can be reduced.

The threshold value for determining whether or not to execute the back pressure process can be arbitrarily set and changed by the Ethernet administrator.

As described above, the packet can be retransmitted from the transmission source without the system down of the Ethernet 2 and most efficiently and without burdening the CPU, and the Ethernet 2 can be operated efficiently.

(Second Embodiment) FIG. 4 is a block diagram showing a terminal in which an Ethernet transmitting / receiving apparatus according to a second embodiment of the present invention is incorporated. The same parts as those of the Ethernet transmission / reception device 4a of the first embodiment shown in FIG. Therefore, the detailed description of the overlapping part is omitted.

A life timer 18 is provided in the Ethernet transmitting / receiving device 4b of the second embodiment. The life timer 18 clears the source address taken from the packet 17 received from the Ethernet 2 stored in the address memory 16, for example, every day or every week.

Other operations are the same as those of the Ethernet transmitting / receiving apparatus 4a of the first embodiment shown in FIG.

In the thus configured Ethernet transmitting / receiving apparatus 4b of the second embodiment, even if the terminal 13 is newly connected to the Ethernet 2 or the connected terminal 13 is removed, The device 4b automatically grasps the number of the terminals 13 connected to the Ethernet 2 at the present time, and controls the execution / non-execution of the back pressure process according to the number of the terminals 13.

Therefore, the Ethernet 2 can be operated more efficiently.

(Third Embodiment) FIG. 5 is a block diagram showing a terminal 1 in which an Ethernet transmitting / receiving apparatus according to a third embodiment of the present invention is incorporated. The same parts as those of the Ethernet transmission / reception device 4a of the first embodiment shown in FIG. Therefore, the detailed description of the overlapping part is omitted.

In the Ethernet transmission / reception device 4c of the third embodiment, the hash operation unit 15 provided in the Ethernet transmission / reception device 4a of the first embodiment is eliminated. Then, the source address (SA) extracted from the packet 17 input from the receiving terminal 6 is written to the address memory 16 without bit compression.

In the thus configured Ethernet transmitting / receiving apparatus 4c of the third embodiment, the address memory 1
Since only the storage capacity of the Ethernet transmission / reception device 6 is increased, almost the same effect as the Ethernet transmission / reception device 4a of the first embodiment described above can be obtained.

(Fourth Embodiment) FIG. 6 is a block diagram showing a terminal 1 in which an Ethernet transceiver according to a fourth embodiment of the present invention is incorporated. The same parts as those of the Ethernet transmission / reception device 4a of the first embodiment shown in FIG. Therefore, the detailed description of the overlapping part is omitted.

In the Ethernet transmitting / receiving apparatus 4d of the fourth embodiment, a carrier monitoring unit 19 is provided instead of the hash calculation unit and the address memory.

That is, the data input from the Ethernet 2 to the reception terminal 6 via the transceiver 5 includes a reception clock (RCLK), reception data including a packet (RXD), and carrier detection (CD), as shown in FIG. , Collision detection (COL).

FIG. 8 is a waveform diagram of these four signals. The upper part of FIG. 8 shows a normal state where no collision occurs between packets, and the lower part of FIG. 8 shows an abnormal state when a collision occurs between packets.

In the normal state of the upper stage, the carrier detection (CD) rises and a reception clock (RCLK) is generated. The reception side receives the reception data (RXD) in synchronization with the reception clock (RCLK). The received data ends at the same time as the carrier detection (CD) falls. The reception clock ends after several cycles.

In the lower abnormal state, the Ethernet 2
When a collision occurs in a plurality of packets (data), the transceiver 5 detects the collision and activates collision detection (COL). If a collision occurs during data transmission, the data becomes invalid. Similarly, when the receiving side performs the back pressure process, the collision detection (COL) rises.

Then, the carrier monitoring unit 19 of the Ethernet transmission / reception device 4 d of the fourth embodiment monitors the on / off state of the carrier from the carrier detection (CD) via the reception terminal 6, and performs the specified time on the Ethernet 2. Detects the traffic in the inside and sends it to the control unit 10b. That is,
The longer the carrier is on, the greater the traffic.

The control unit 10b constantly monitors the reception buffer 8 and the reception terminal 6, and when a new packet is received at the reception terminal 6 when the reception buffer 8 is full, the packet is input from the carrier monitoring unit 19. It is determined whether or not the communication amount exceeds a predetermined threshold position.

If the traffic on the Ethernet 2 does not exceed the predetermined threshold value, the selector 12 is switched to the JUM pattern generator 11 and, for example, the 32-bit JUM pattern data 14 is transmitted to the transmission terminal 7. Then, the data is output to the Ethernet 2 via the transceiver 5.

On the other hand, if the traffic on the Ethernet 2 exceeds a predetermined threshold, the selector 12
Is not switched. As a result, the selector 12 is connected to the transmission buffer 9 side.

In the thus configured Ethernet transmission / reception device 4d of the fourth embodiment, the actual traffic on the Ethernet 2 is detected. When the traffic exceeds the threshold, the back pressure process is stopped.
In this way, by performing the back pressure processing as long as the situation of the Ethernet 2 permits, the processing efficiency of data transmission and reception between terminals in the entire Ethernet can be improved.

(Fifth Embodiment) FIG. 7 is a block diagram showing a terminal in which an Ethernet transmitting / receiving apparatus according to a fifth embodiment of the present invention is incorporated. The same parts as those of the Ethernet transmission / reception device 4a of the fourth embodiment shown in FIG. Therefore, the detailed description of the overlapping part is omitted.

In the Ethernet transmission / reception device 4 of the fifth embodiment, a collision counter 20 is provided instead of the carrier monitoring unit 19. This collision number counter 20
Is the above-mentioned collision detection (COL) via the receiving terminal 6.
And detects the number of collisions on the Ethernet 2 that occur within a specified time, and sends it to the control unit 10c.

The control unit 10c constantly monitors the reception buffer 8 and the reception terminal 6. When a new packet is received by the reception terminal 6 when the reception buffer 8 is full, the collision number counter 20 inputs the collision number. It is determined whether or not the number exceeds a predetermined threshold value.

If the number of collisions on the Ethernet 2 does not exceed the predetermined threshold value, the selector 12 is switched to the JUM pattern generation unit 11 and, for example, 3
The 2-bit JUM pattern data 14 is output to the Ethernet 2 via the transmission terminal 7 and the transceiver 5.

On the other hand, if the number of collisions on the Ethernet 2 exceeds a predetermined threshold, the selector 1
No switching for 2 is performed. As a result, the selector 12
Is connected to the transmission buffer 9 side.

In the thus configured Ethernet transmitting / receiving apparatus 4e, the actual number of collisions between packets on the Ethernet 2 is detected. When the number of collisions exceeds the threshold, the back pressure process is stopped. Therefore, substantially the same effects as those of the Ethernet transmitting / receiving device 4d of the fourth embodiment described above can be obtained.

(Sixth Embodiment) FIG. 9 is a block diagram showing the entire network including a switching hub 1a as a terminal in which an Ethernet transceiver according to a sixth embodiment of the present invention is incorporated.

In the switching hub 1a as a terminal in the system of the sixth embodiment, six Ethernet transmission / reception devices 4a numbered from 1 to 6 are incorporated. Each Ethernet transceiver 4a is shown in FIG.
Has the same structure as the Ethernet transmitting / receiving apparatus 4a of the first embodiment shown in FIG.

Each of the first to fifth Ethernet transmission / reception devices 4 a is connected to one or a plurality of terminals 13 and 22 via the Ethernet 2. The sixth Ethernet transmitting / receiving device 4 a is connected to another switching hub 23 via the Ethernet 2. Further, another plurality of terminals 24 are connected to the switching hub 23.

The switching hub 1a is provided with a switching processor 3a as a data processor connected to each Ethernet transmitting / receiving device 4a. The switching processing unit 3a sequentially reads out each packet 17 stored in each reception buffer 9 of each Ethernet transmission / reception device 4a, and designates the terminals 13, 22, and 23 indicated by the transmission destination address (DA) 17c of this packet 17. The Ethernet transmission / reception device 4a to which the Ethernet transmission / reception device 24 is connected is selected, and the read packet 17 is written in the transmission buffer 9 of the corresponding Ethernet transmission / reception device 4a. The Ethernet transmitting / receiving device 4a in which the packet 17 has been written in the transmission buffer 9 outputs the packet 17 to the Ethernet 2 to which it is connected.

Therefore, the terminals 13, 22, 24 connected to an arbitrary Ethernet 2 are connected to the switching hub 1a.
Terminal 13 connected to any Ethernet 2 via
Packets 17 incorporating various data for 22 and 24
Can be sent.

Each Ethernet transmission / reception device 1a incorporated in the switching hub 1a of the system of this embodiment comprises:
If, for example, four or more terminals are incorporated in the Ethernet 2 to which they are connected, the threshold is set so that the backpressure process is not executed.

Therefore, in the system of this embodiment, as shown in the figure, the back pressure processing is stopped in the first and sixth Ethernet transmitting / receiving devices 4a,
The second to fifth Ethernet transmitting / receiving devices 4a perform the back pressure process.

In the system configured as described above, when a large number of terminals 13 and 24 are connected and the back pressure process is performed, the first and sixth Ethernet transmission / reception which are highly likely to cause collisions frequently on the Ethernet 2 are performed. Device 4
Since the back pressure processing of a is stopped, it is possible to achieve substantially the same effect as the apparatus of the first embodiment shown in FIG.

(Seventh Embodiment) FIG. 10 shows a seventh embodiment of the present invention.
FIG. 1 is a block diagram illustrating an entire network including a switching hub 1a as a terminal in which an Ethernet transmitting / receiving apparatus according to an embodiment is incorporated. The same parts as those of the system of the sixth embodiment shown in FIG. 9 are denoted by the same reference numerals, and detailed description of the overlapping parts will be omitted.

In the system according to the seventh embodiment,
In the switching hub 1b as a terminal, four Ethernet transmission / reception devices 4f from No. 1 to No. 4 are incorporated. Further, in the switching hub 1b, each packet 17 received by each Ethernet transceiver 4f is stored.
A buffer number 8a is provided in which four reception buffers 8 capable of storing N pieces of data are assigned port numbers (terminal numbers) and formed.

In the switching hub 1b,
Since data processing is not performed, the reception buffer unit 8a also serves as a transmission buffer unit.

Further, in the switching hub 1b, as shown in FIG. 11, the terminals 13 and 22 of A to E are connected to which port of the switching hub 1b, that is, which Ethernet transmitting / receiving device 4f is connected. A MAC table 25 for storing is provided. Further, a switching control unit 3b as a data processing unit is provided.

FIG. 12 is a block diagram showing a detailed configuration of the Ethernet transmitting / receiving section 4f.

The packet 17 received from the Ethernet 2 via the transceiver 5 and the receiving terminal 6 is converted into parallel data by the S / P converter 26, and
8 is written. At the same time, the destination address DA and the source address SA of the packet 17 are stored in the address buffer 3
Written to 1. Each packet 17 written to the reception FIFO 28 is written to the reception buffer 8 designated by itself in the reception buffer unit 8a based on the instruction of the reception control unit 29.

The switching control unit 3b of the switching hub 1b reads out each packet 17 written in each reception buffer 8 of the reception buffer unit 8a, and
The port (Ethernet transmitting / receiving unit 4f) corresponding to the destination address DA of No. 7 is read from the MAC table 25, and the corresponding packet 17 is transferred to the corresponding Ethernet transmitting / receiving unit 4f.

In FIG. 12, a packet 17 to be transmitted
Is written to the transmission FIFO 29. Transmission FIFO2
The packet 17 read from 9 is converted to serial data by the P / S converter 30 via the selector 12 and then output to the Ethernet 2 via the output terminal 7 and the transceiver 5.

[0102] The MAC control unit 32
1 monitors, using the MAC table 25, whether the destination address DA and the source address SA stored at the present time belong to the same port (the same Ethernet transmitting / receiving device 4f). That is, in the case of the same port (the same Ethernet transmitting / receiving device 4f), the source terminal and the destination terminal are connected to the same Ethernet 2, so that the own Ethernet transmitting / receiving unit 4f does not need to receive the packet 17. .

As described above, the MAC control unit 32 determines whether or not the received packet 17 is a packet to be received by itself, and transmits the determination result to the reception control unit 27.

The reception control unit 27 constantly monitors its own reception buffer 8 and reception terminal 6, and when a new packet is received at the reception terminal 6 when its own reception buffer 8 is full, the MAC control is performed. The judgment result from the unit 32 is checked.

When it is necessary to receive the packet 17, the selector 12 is switched to the JUM pattern generator 11
To output the JUM pattern data 14 of, for example, 32 bits to the Ethernet 2 via the transmission terminal 7 and the transceiver 5.

On the other hand, if there is no need to receive this packet 17, switching to selector 12 is not performed. As a result, the selector 12 is connected to the transmission FIFO 29 side.

In the Ethernet transmission / reception device 4f of the seventh embodiment configured as described above, if the destination address of the received packet is not a preset destination address relating to itself, the received packet 17 is There is no problem if it is destroyed. Therefore, under these conditions,
No back pressure processing is performed. As a result, unnecessary back pressure processing is not performed, and the data transmission processing efficiency of the entire system can be improved.

[0108]

As described above, in the present invention,
By monitoring the status of the Ethernet, when the reception buffer in each terminal is full, it is determined whether or not to perform back pressure processing, and this back pressure processing is performed only when it is determined that it is safe. are doing.

Therefore, when the reception buffer in each terminal becomes full, the packet can be retransmitted from the transmission source without causing the system down of the Ethernet and most efficiently and without burdening the CPU.
Data transmission processing efficiency of the entire Ethernet can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a terminal in which an Ethernet transmitting / receiving apparatus according to a first embodiment of the present invention is incorporated.

FIG. 2 is a format diagram of a packet flowing over Ethernet.

FIG. 3 is a view for explaining the operation of the Ethernet transmitting / receiving apparatus of the first embodiment;

FIG. 4 is a block diagram showing a schematic configuration of a terminal in which an Ethernet transmitting / receiving apparatus according to a second embodiment of the present invention is incorporated;

FIG. 5 is a block diagram showing a schematic configuration of a terminal in which an Ethernet transmitting / receiving apparatus according to a third embodiment of the present invention is incorporated;

FIG. 6 is a block diagram showing a schematic configuration of a terminal in which an Ethernet transmitting / receiving apparatus according to a fourth embodiment of the present invention is incorporated.

FIG. 7 is a block diagram showing a schematic configuration of a terminal in which an Ethernet transmitting / receiving apparatus according to a fifth embodiment of the present invention is incorporated.

FIG. 8 is a waveform chart showing details of a data signal taken into the Ethernet transmitting / receiving apparatus according to the fourth and fifth embodiments of the present invention.

FIG. 9 is a diagram showing an entire system configuration including a switching hub in which an Ethernet transceiver according to a sixth embodiment of the present invention is incorporated.

FIG. 10 is a diagram showing an overall configuration of a system including a switching hub in which an Ethernet transceiver according to a seventh embodiment of the present invention is incorporated.

FIG. 11 is a diagram showing the storage contents of a MAC table formed in a switching hub in which the Ethernet transmission / reception device of the seventh embodiment is incorporated.

FIG. 12 is a block diagram showing a schematic configuration of an Ethernet transmitting / receiving apparatus according to the seventh embodiment;

FIG. 13 is a block diagram showing a schematic configuration of a conventional Ethernet transmitting / receiving apparatus.

FIG. 14 is a block diagram showing a schematic configuration of a conventional Ethernet transmitting / receiving apparatus.

FIG. 15 is a view for explaining the operation of a system in which the conventional Ethernet transmitting / receiving apparatus is incorporated.

[Explanation of symbols]

1, 13, 22, 24 Terminal 1a, 23 Switching hub 2 Ethernet 3 Data processing unit 3a Switching control unit 4, 4a, 4b, 4c, 4d, 4e, 4f Ethernet transmitting / receiving device 5 Transceiver 6 Receiving terminal 7 ... Transmission terminal 8 ... Reception buffer 9 ... Transmission buffer 10, 10a, 10b ... Control unit 11 ... JAM pattern generation unit 12 ... Selector 14 ... JAM pattern data 15 ... Hash operation unit 16 ... Address memory 17 ... Packet 18 ... Life timer 19 ... Carrier monitoring device 20 ... Collision counter 25 ... MAC table 27 ... Reception control unit 28 ... Reception FIFO 29 ... Transmission FIFO 32 ... MAC control unit

Claims (8)

[Claims] 1. A reception buffer which is incorporated in a terminal connected to the Ethernet and into which a packet received from another terminal connected to the Ethernet is written and from which a written packet is read from a data processing unit. And a transmission buffer for writing a packet output from the data processing unit and transmitting the written packet to the Ethernet at a predetermined timing. When the reception buffer becomes full, a back pressure In an Ethernet transmitting / receiving apparatus that performs processing, a terminal number detecting unit that detects the number of terminals connected to the Ethernet from a packet received from the Ethernet; and a terminal number detected by the terminal number detecting unit exceeds a threshold value. Back pressure processing stopping means for stopping the back pressure processing Ethernet transceiver having a. 2. The terminal number detecting means includes: an address extracting means for extracting a source address from a received packet; an address memory for storing different addresses among addresses sequentially extracted by the address extracting means; 2. The Ethernet transmitting / receiving apparatus according to claim 1, further comprising a counter for counting the number of addresses stored in the address memory. 3. The Ethernet transmission / reception apparatus according to claim 2, further comprising address memory clear means for clearing an address stored in said address memory at a predetermined period. 4. The Ethernet transmission / reception device according to claim 2, wherein the address memory stores the address in a state converted into a hash value. 5. A reception buffer which is incorporated in a terminal connected to the Ethernet and in which a packet received from another terminal connected to the Ethernet is written and from which the written packet is read out from the data processing unit. And a transmission buffer for writing a packet output from the data processing unit and transmitting the written packet to the Ethernet at a predetermined timing. When the reception buffer becomes full, a back pressure In an Ethernet transmitting / receiving apparatus that performs processing, a carrier state monitoring unit that monitors an on / off state of a carrier flowing on the Ethernet, and a communication on the Ethernet based on the on / off state of the carrier monitored by the carrier state monitoring unit Communication amount detecting means for detecting the amount of communication; and An Ethernet transmission / reception apparatus comprising: a back pressure processing stop means for stopping the back pressure processing when a communication amount detected by the detection means exceeds a threshold value. 6. A reception buffer incorporated in a terminal connected to the Ethernet, for writing a packet received from another terminal connected to the Ethernet, and for reading the written packet from the data processing unit. And a transmission buffer for writing a packet output from the data processing unit and transmitting the written packet to the Ethernet at a predetermined timing. When the reception buffer becomes full, a back pressure An Ethernet transmitting / receiving apparatus for performing processing, comprising: collision detecting means for detecting collision of packets flowing on the Ethernet; and when the number of collisions detected by the collision detecting means within a prescribed time exceeds a threshold value, the back pressure processing Ethernet transmission / reception device provided with back pressure processing stopping means for stopping . 7. The apparatus according to claim 1, wherein said back pressure processing stopping means includes a threshold value setting means for setting a threshold value for stopping said back pressure processing based on an external instruction. 2. The Ethernet transmitting / receiving device according to claim 1. 8. A reception buffer incorporated in a terminal connected to the Ethernet, for writing a packet received from another terminal connected to the Ethernet, and for reading the written packet from the data processing unit. And a transmission buffer for writing a packet output from the data processing unit and transmitting the written packet to the Ethernet at a predetermined timing. When the reception buffer becomes full, a back pressure In an Ethernet transmitting / receiving apparatus that performs processing, an address extracting unit that goes beyond a destination address from a packet received from the Ethernet; and a destination address extracted by the address extracting unit is transmitted beforehand. When the address is not the destination address, the back pressure process is stopped. Ethernet transceiver that includes a back-pressure processing suspension unit for.