JPH01243750A - Packet switching device - Google Patents

Abstract

PURPOSE:To improve the through-put rate of packet data by causing the route selecting priority of a high speed line to be low when the traffic of the high speed line goes over a traffic limit value or when a trouble is generated in the high speed line. CONSTITUTION:When a transmitting request is generated from a terminal, a route control part 13A of a packet converter 1A selects the table of a transmitting path to be used out of address information in the packet data, which are outputted from the terminal, and refers the selected table. Then, high speed lines 4a-4n, which can be utilized and have the high priority are informed of the terminal. The terminal executes transmission to the line. A traffic control part 2 obtains congestion degree in each high speed line 4a-4n and when this congestion degree goes to be high over a specified value, the route table is reloaded through a route table switching part 131 so that the priority of the line can be low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a packet switch used for data communications and the like.

(Prior art) Packet switches are connected to each other, for example, in a loop, through lines, and each packet switch receives packets sent from the line, extracts them one by one, and checks whether they are related to its own station or not. The packets related to the local station are sent from the destination address of the packet to the corresponding terminal, and the packets unrelated to the local station are sent to the transmitter of the local station.
The transmission packets from the local terminal are sent to the transmitting unit, and the transmitting unit receives the packets sent in this way and sends them out to the line in the order of the queue, thereby exchanging data between the target terminals. This is a device that performs the following.

FIG. 6 shows an example of the configuration of a packet switching network.

In such a configuration, packet data (destination node address + destination terminal address child data) generated from the terminal 2 is transmitted via the low-speed line 3 to the packet exchange 1111 to which the terminal is connected, and the packet exchange 1 that receives it
Then, extract the destination node address from the packet data, determine the high-speed line 4 that can transmit to this address, send the packet data to the high-speed line selected based on the determination, and the destination packet switch The packet data is received, and the designated terminal address in the packet data is checked. If the data is addressed to the own node, the packet data is transmitted to the terminal device according to the designated terminal address, and if it is not addressed to the own node, the packet data is transmitted to the terminal device according to the designated terminal address. It does things like take a detour to a high-end line that can communicate to the node address.

FIG. 7 shows an example of a transmission system of a conventional packet switch 1. The conventional packet transmission system will be explained with reference to this diagram. First, when there is a data transmission request to a terminal device, the terminal device adds the destination partner node address and the partner terminal address to the data according to the format of the packet data PD, and then sends the packet to the data via the low-speed line 3.
Send to. In packet switching till, when the terminal interface 11 receives this packet data PD, the receiving terminal interface 11 uses the control line 1 to determine the route necessary for transmitting it to the designated destination node address.
The node address is communicated to the route control unit 13 via 2.

The route control unit 13 has a fixed route table for each node address A1 as shown in FIG. A signal indicating whether packet data can be transmitted to the determined high-speed line (whether or not the high-speed line is busy) is sent and received through the control line 15 to the line interface 14 of No. 4 to check the status. the result,
If it is in a transmission enabled state (non-BUSY state), the route control unit 13 transmits to the terminal interface 11 through the control line 12 that transmission is possible via the high-speed line, and thereby the terminal interface 11 transmits the information through the data line 16. The packet data is transmitted to the high-speed line 4 via the high-speed line interface 14. It also searches for free high-speed lines in priority order across all route tables, and as a result,
If there is no free high-speed line, the route control unit 13
notifies the terminal interface 11 that transmission is not possible. As a result, the terminal interface 11 accumulates packet data for each route table in the data accumulation buffer 17 in the packet exchange all, and when any high-speed line becomes free, the terminal interface 11 receives the free data from the route control unit 13. In response to a command to enable transmission using a high-speed line, the accumulated packet data is sent in the order of the queue to the vacant high-speed line interface corresponding to the above-mentioned high-speed line according to the route table.

In this case, since the data storage buffer 17 is finite, if storage becomes impossible, packet data generated during the impossible period will be discarded.

(Problem to be Solved by the Invention) Packet switches are connected to each other, for example, in a loop, through lines, and each packet switch receives packets sent from a high-speed line, takes them out one by one, and then automatically processes the packets. It is checked whether the station is related or not, and packets related to the local station are sent from the destination address of the packet to the terminal corresponding to the destination, and packets not related to the local station are sent to the transmitter of the local station. sending,
Also, the transmission packets from the local terminal side are sent to the transmitting section, and the transmitting section receives the packets sent in this way and sends them out to the high-speed line in the order of the queue. This is a device that exchanges data.

In conventional devices, when there is a packet transmission request from a terminal connected to the local station, the destination address of the packet is checked and the route 1 table that indicates the priority of the high-speed line used for transmission to that destination is used. , it knows which high-speed line is being used, checks the status of that high-speed line, and if it is not available, uses the next highest-ranked high-speed line, and so on, and sends the above packet using the high-speed line determined according to the predetermined route table on the destination side. I was trying to do it.

In this way, in conventional equipment, the route table is fixed, so the selection order of high-speed lines in the route table is specific. If the line exceeds the traffic limit value or if a failure occurs in the high-speed line, time is spent searching for a free high-speed line to communicate packet data, and when the next packet data continues, the packet Data will accumulate in the packet switch, and as the accumulation increases, not only will some packet data be discarded, but the probability that such a situation will occur increases. As a result, the throughput rate of data from the terminal device, that is, the amount of processing per unit time continues to be low, resulting in poor efficiency.

Therefore, the purpose of this invention is to develop a traffic control method that can maintain a constant packet data throughput rate even when a high-priority high-speed line exceeds its traffic limit or a failure occurs. Its purpose is to provide packet switching equipment.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention is configured as follows. In other words, when multiple packet switches are connected via a Takato line and there is a request for transmission of packet data including destination information from a terminal connected to each packet switch, use is prioritized based on the destination information set in advance. In a packet switch used in a packet switching network, the packet data is transmitted by referring to a table of high-speed lines and using a high-speed line with a high priority among available high-speed lines. A high-speed line occupancy control unit that has a buffer that sequentially temporarily holds transmission packet data for each line and that disables packet data transmission from the terminal to the corresponding high-speed line when this buffer runs out of room; and a high-speed line occupancy control unit that holds the buffer. a high-speed line interface means having means for reading packet data and sending it to a corresponding high-speed line; and determining the degree of congestion for each high-speed line from the transmission request from the terminal and the transmission processing status in the high-speed line interface means;
traffic control means for generating a table rewriting command for a high-speed line compatible with the high-speed line interface means having a high degree of congestion when the degree of congestion becomes higher than a specified value;
The apparatus is configured to include means for making the table rewritable and rewriting the table so that the priority of the high-speed line is lowered when the table rewriting command is received.

(Function) In such a configuration, when a transmission request is generated from a terminal, the packet switch selects the table of the transmission route to be used from the destination information in the packet data output from the terminal, and refers to the selected table. Know which Takato line you should use. Then, among the available high-speed lines, the line with the highest priority in the table is used to execute the transmission, but here the data is sent to the selected high-speed line compatible high-speed line interface means, and the high-speed line interface means 11J is stored in the built-in buffer, read out, and transferred to a high-speed line! If the buffer runs out of space, it will no longer be possible to accept packet data from the terminal, so the packet switch will check the next highest priority high-speed line and control it so that it can be used for transmission. On the other hand, the traffic control means calculates the degree of congestion for each high-speed line from the transmission request from the terminal in the high-speed line interface means and the transmission processing status, and when the degree of congestion becomes higher than a specified value, the traffic control means determines the degree of congestion for each high-speed line from the transmission request from the terminal in the high-speed line interface means and the transmission processing status, and when the degree of congestion becomes higher than a specified value, the high-speed line with the high congestion degree Generates a table rewrite command for the high-speed line compatible with the line interface means. The table is rewritable, and upon receiving the table rewriting command, the table rewriting means rewrites the table so that the priority of the high-speed line is lowered, so that from the next packet data onwards, the packet data for the high-speed line will be changed. The transmission request probability is reduced, and the packet data accumulated within the high-speed line interface can be completely transmitted. In other words, this allows the traffic on the high-speed line to be reduced.

Therefore, even if a high-priority high-speed line becomes congested and exceeds its limit or a failure occurs, control will be made to avoid this high-speed line and use another, so the congestion will not be amplified. The high-speed line interface means is provided with a buffer for temporarily accumulating packet data, and the packet data is queued there, so when it is congested as in the past, the high-speed line that can be used for transmission is re-established by referring to the table. Since the trouble of re-checking and re-transmitting is eliminated, there is an advantage that the efficiency of transmission execution from the terminal is increased accordingly.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this device, and in the figure, 11a, 11b to lln are terminal interfaces, respectively. These terminal interfaces lla to lln are connected to terminal devices (not shown) via corresponding low-speed lines 3a to 3n, respectively. When there is a request to send Karame packet data, it receives the packet data from the terminal device, extracts the destination node address from the data, and sends it to the route control unit 13A via the control lines 12a to 12n corresponding to itself. , whereby the route control unit 1
It has a function to send packet data to the high-speed interface corresponding to the specified high-speed line according to the information of available high-speed lines returned from 3A.

Further, the route control unit 13A has route tables T1 to Tn for each destination node address that can be changed by rewriting as shown in FIG.
It also receives the destination node address, refers to the route table determined by this node address, learns the high-speed line that has the highest priority in the table among the high-speed lines that should be used and is registered in this table, and uses this line. The number is output as a request signal REQ to the high-speed line interfaces 14a to 14n corresponding to the high-speed line through the traffic control unit 21 in order to check whether or not this high-speed line can be used. The signals (BUSY, non-BUSY) are used to determine whether or not the high-speed line can be used, and if it is available, a signal to permit packet data transmission to the high-speed line is sent to the terminal interfaces lla to lln for the above packet data. It has the function of providing a transmission request to the terminal interface that issued the transmission request, and when it is unavailable, checking the next high-speed line in the route table and performing the same thing as described above.

In addition, the route tables T1 to Tn are formed on a rewritable memory such as a RAM, and are
When receiving a switching command from the route control unit 21, the route table switching unit 131 deletes the high-speed line number existing in all route tables, sequentially adds the lower-order high-speed line numbers, and sets the high-speed line number as the lowest one. It has a function to perform operations such as rewriting the route table so that

The traffic control unit 21 has a configuration as shown in FIG. 3, and includes control lines 22 and data lines 23 from the route control unit 13A, data lines 24a to 24n of each high-speed line, and control lines 15a to 15n for high-speed lines. Request connection signal RE
The high-speed line number selector 211 controls connection switching so that the corresponding ones are connected according to the contents of Q, and the number of occurrences of the request signal REQ and the number of occurrences of BtlSY in each of the high-speed line control lines 15a to 15n are measured. Traffic storage registers 213a to 2 that count each slide
13n, these traffic storage registers 213a to 21
Based on the count value of 3n, calculate the traffic of each high-speed line using the following formula 8USY pulse count according to the algorithm in Figure 5, and when the traffic on a certain high-speed line is larger than the traffic limit value (N%) Alternatively, when a failure occurs in the high-speed line (when there is a DO14N pulse notification), route switching control instructs the route table switching unit 131 of the route control unit 13A to give the high-speed line the lowest priority. 212.

The high-speed line interfaces 14a to 14n receive received packet data, etc. to the corresponding high-speed lines 14a to 1, respectively.
40, and is configured as shown in FIG. That is, it consists of a high-speed line occupancy control section 140, a high-speed line occupancy flag register 142, a data accumulation buffer 141, and a high-speed line connection section 143. When the high-speed line occupancy control section 140 receives a request signal REQ, it starts the data accumulation buffer.
It is known from the state of the high-speed line occupancy flag register 142 whether or not packet data can be stored in 141, and if storage is not possible, 8υSY is output on control line 15, and if storage is possible, non-B
The data storage buffer 141 receives packet data sent from the terminal interfaces lla to lln via the data line 24 and stores them in sequence, until the buffer becomes full. When this happens, a flag is set in the high-speed line occupancy flag register 142,
When there is room in the buffer, this flag is controlled to be lowered. The Takato line connection unit 143 is connected to the corresponding Takato line, and monitors the state of the high-speed line, and when transmission is possible, reads the packet data stored in the data storage buffer 141 in the order of the queue and sends it to the high-speed line. It has a function of outputting a DO14N signal to the control line 15 when a failure occurs in the high-speed line.

Next, the operation of this device having the above configuration will be explained.

In the packet switching 111A of the present invention, compared to the conventional one,
The route tables T1 to Tn in the route control unit 13A are constructed of rewritable memory and have a function of monitoring the degree of congestion of each high-speed line and issuing a command to change the high-speed line ranking in the route tables T1 to Tn. The provision of the traffic control unit 21 having the line interface 14a~
The difference is that a packet data storage buffer is provided in the route control unit 14n, and a route table switching unit 131 that changes the contents of the route table is added to the route control unit 13A.

In such a configuration, it is assumed that a terminal device first requests transmission of packet data having the data format described in the conventional example.

In this case, the terminal interface 1la (θ"11b~1
1n) transmits the destination node address of the packet data to the route control unit 13A via the control line 12a (Orl 2b to 12n). The route control unit 13A sequentially routes the high-speed line interface 14 a (
Orl 4 b to 14 n> is accessed to determine whether packet data can be transmitted. The role of the traffic control section 21 in this case will be explained using FIG. 3. When the route control unit 13A generates a packet data transmission request signal REQ (Takato line number) on the control line 22, the line number selector 211 issues a transmission request to the high-speed line interface 14a (Or14i to 14n) corresponding to the specified high-speed line number. The signal REQ of Takato line 11 control line 15a (
Orl 51-15n). If the high-speed line interface 15a (orl 5 i to 15n) is in a state where packet data can be transmitted, that is, in a non-BUS'l' state, the control line 15a (orl 5 i to 15n)
n) Set the inner BUSYII to non-8 (ISY), and set the BUSY line of the control line 22 to non-BUS via the line number selector 211.
By setting Y, the terminal interface 11 indicates that packet data can be transmitted through the route control unit 13A.
a (Orl l b ~ 11 n), thereby causing the terminal interface to transfer data lines 16 a (orl 6 b ~ 16 n) to its authorized high-speed line.
), data line 23, data line 24a (or24i~24
n). In addition, the high-speed line selected by the route control unit 13A is in a packet data transmission disabled state (BUS
Y state), the control line 15a (orl 51-1
5n) is set to 8USY, and this transmits the fact that the high-speed line is in the ausv state to the route control unit 13A via the ausv line of the control line 22 via the high-speed line number selector 211. A transmission request is made to the high-speed line with the priority.Therefore, the traffic control unit 21 uses the control lines 15a to 15a for each high-speed line.
15n transmission request signal REQ pulse and status signal BUSY pulse indicating that transmission is not possible from each of the high-speed line interfaces 14a to 14n are counted in the trapic storage register corresponding to each high-speed line, while route switching is performed. The control unit 212 sequentially calculates the traffic REQ pulse count of each high-speed line for each line according to the algorithm shown in FIG. , Check whether DOWN output is occurring on the high-speed line, and when the traffic limit value is exceeded on the currently used high-speed line, or when a failure occurs on the high-speed line (when a DOWN pulse notification occurs), Route control unit 13
A command is given to the route table switching unit 131 of A to give the high-to-home line the lowest priority.As a result, the route table switching unit 131 deletes the line number that exists in all route tables, and The high-speed line numbers are sequentially deleted, and the route table is rewritten so that the deleted high-speed line number is at the lowest priority.If you do this, the high-speed line will have the lowest priority from the next packet data. Therefore, the probability of requesting transmission of packet data to the high-speed line is reduced, and the packet data stagnant within the high-speed line interface can be completely transmitted.

In other words, this makes it possible to reduce traffic on the high-speed line. On the other hand, the high-speed line interfaces 14a to 14n each have a structure as shown in FIG. 4, and the corresponding high-speed lines 4a to 4n
terminal interface lla-ll for transmission to
When packet data is sent from n, the data storage buffer 141 stores as much packet data as possible, and the high-speed line connection section 143 sequentially transmits the packet data to the high-speed line according to the transmission speed of the high-speed line. If the data storage buffer 141 becomes full and packet data cannot be stored, an overflow signal from the data storage buffer 141 causes the high speed line occupancy flag register 142 to set a flag and set it as "line occupancy status \s". As a result, the high-speed line occupancy control unit 140 transmits a signal BUSY indicating that transmission is not possible. Furthermore, when the high-speed line connection unit 143 detects a high-speed line failure, it will transmit failure@DO14N. Furthermore, since the data storage buffer 141 is provided in each of the high-speed line interfaces 14a to 14n, packet data that is requested to be transmitted can be stored in this buffer one after another, so as long as this buffer does not become full. Unlike the conventional method, there is no need to perform route selection processing again when packet data is retained, and therefore the throughput rate of packet data is dramatically improved.

In this way, this device connects multiple packet switches using high-speed lines, and when there is a request to send packet data including destination information from a terminal connected to each packet switch, it transmits packet data based on the preset destination information. A packet used in a packet switching network in which the packet data is transmitted using a high-priority high-speed line among available high-speed lines by referring to a table of high-speed lines to be used with priority. The switching equipment has a data storage buffer that sequentially temporarily stores the transmitted packet data for each packet switching equipment, and high-speed line occupancy control that disables packet data transmission from the terminal to the corresponding high-speed line when there is no room in this buffer. a high-speed line interface having a means for reading packet data held by the buffer and sending it to a corresponding high-speed line; traffic control means that generates a table rewriting command for a high-speed line corresponding to a high-speed line interface with a high congestion level when the congestion level becomes higher than a specified value; 1 of the high-speed line upon receiving the command.
a table switching unit that rewrites the table so that the priority is lowered, and route control means that selects an available high-speed line according to the priority from the table selected according to the destination information of the packet data and notifies the terminal side. It is composed of Then, when a transmission request is generated from a terminal, the route control means of the packet switch selects a transmission route table to be used from the destination information in the packet data output from the terminal, and refers to the selected table and uses it. In addition to knowing the high-speed lines, the high-speed line that is available and has a high priority is checked and the terminal is notified.The terminal executes transmission to this line. sending,
The high-speed line interface accumulates data in its built-in buffer, reads it out, and sends it to the high-speed line IIN. When there is no room in the buffer, packet data cannot be accepted from the terminal, so the route control means has the next priority. The system checks for high-speed lines with high speeds and controls them so that they can be used for transmission.

On the other hand, the traffic control means determines the degree of congestion for each high-speed line from the transmission request from the terminal on the high-speed line interface and the transmission processing status, and when the degree of congestion becomes higher than a specified value, the high-speed line with the high congestion degree is A table rewrite command is generated for a high speed line compatible with the interface, and upon receiving this table rewrite command, the table switching section rewrites the table so that the priority of the high speed line concerned is lowered. Therefore, from the next packet data onward, the probability of requesting transmission of packet data to that high-speed line decreases, and it is possible to send all the packet data that has accumulated within that high-speed line interface. In other words, this allows the traffic on the high-speed line to be reduced.

Therefore, even if a high-priority high-speed line becomes congested and exceeds its limit or a failure occurs, the system will avoid this high-speed line and use another, so the congestion will not be amplified. The high-speed line interface means is provided with a buffer for temporarily accumulating packet data, and the packet data is queued there, so when it is crowded, as in the past, the table is referred to and the high-speed line that can be used for transmission is re-established. Since the trouble of re-checking and re-transmitting is eliminated, there is an advantage that the efficiency of transmission execution from the terminal is increased accordingly.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with appropriate modifications within the scope of the gist thereof.

C Effects of the Invention J As detailed above, the present invention lowers the route selection priority of the high-speed line when the traffic on the high-speed line exceeds the traffic limit value or when a failure occurs in the high-speed line. Since the route selection method uses priority, even if a high-speed line becomes overcrowded, the probability of a transmission request to that high-speed line decreases, so all the packet data accumulated on that high-speed line will be sent out. It is possible,
In addition to maintaining equal traffic on each high-speed line and increasing the throughput rate of packet data, the high-speed line interface is equipped with a data storage buffer, so there is no need to retry when packet data is stagnant. Since four selections can be omitted, the throughput rate of packet data can be increased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of a route table used in this device, FIG. 3 is a block diagram showing an example of the configuration of a traffic control section in this device, and FIG. Figure 4 is a block diagram showing an example of the configuration of a high-speed line interface in this device, Figure 5 is a flowchart showing the procedure for determining traffic, Figure 6 is a diagram showing an example of a packet switching network, and Figure 7 is a diagram showing a conventional FIG. M8, a block diagram showing an example of the configuration of a packet switch, is a diagram showing an example of a conventional route table. 4a to 4n...High speed line, lla to lln...Terminal interface, 13A...Route control unit, 14a to 1
4n... High-speed line interface, 21... Traffic control unit, 131... Route table switching unit, 140
. . . High-speed line occupancy control unit, 141 . . . Data accumulation buffer, 142 . . . High-speed line occupancy flag register, 1
43... Takato line connection unit, 212... Route switching command unit, 213a, 213n... Traffic storage register. Applicant's agent Patent attorney Suzue Takehiko 7 Toshisu A1 -ML Hachi Nafur Figure 2 E 6 Ko

Claims (1)

[Claims] Multiple packet switches are connected via high-speed lines, and when there is a request to send packet data including destination information from a terminal connected to each packet switch, a high-speed line is used with priority determined based on the destination information set in advance. Of the available high-speed lines, refer to the table below.
In a packet switching device used in a packet switching network that transmits the packet data using a high-speed line with a high priority, the packet switch has a buffer for sequentially temporarily holding the transmitted packet data for each of the high-speed lines, and has a buffer with sufficient capacity. high-speed line interface means, comprising: a high-speed line occupancy control unit that disables packet data transmission from the terminal to the corresponding high-speed line when the buffer runs out; and means for reading packet data held in the buffer and sending it to the corresponding high-speed line; , the degree of congestion for each high-speed line is determined from the transmission request from the terminal and the transmission processing status in the high-speed line interface means, and when the degree of congestion becomes higher than a specified value, the degree of congestion for each high-speed line interface means corresponding to the high-speed line interface means with the high degree of congestion is determined. A traffic control means for generating a table rewrite command for a high-speed line, and a means for rewriting the table so that the table can be rewritten and the priority of the high-speed line is lowered when the table rewrite command is received. A packet switching device characterized by: