JP3445503B2 - Variable length packet segmentation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable-length packet division device used in data communication for transferring a large amount of information in a short time by simultaneously using a plurality of communication lines in parallel.

[0002]

2. Description of the Related Art The following two methods have been adopted as a method of transferring a large amount of information in a short time by using a plurality of communication lines in parallel at the same time. 1. On the transmission side, the transmission processing unit continuously receives a plurality of packets from the communication user. ATM (Asynchronous Transfer Mode) for each packet
Divide into cells. The divided cells are distributed to a plurality of lines and transmitted in parallel. The receiving side accepts a plurality of cells transmitted in parallel. The reception processing unit
The original packet is regenerated from the plurality of cells. The regenerated packets are sequentially transferred to the communication user.

2. On the transmission side, the transmission processing unit continuously receives a plurality of packets from the communication user. The plurality of packets are distributed to a plurality of lines for each packet and transmitted in parallel. The receiving side accepts a plurality of cells transmitted in parallel. The reception processing unit rearranges the plurality of packets in the original order and transfers the packets to the communication user.

[0004]

By the way, the above-mentioned conventional techniques have the following problems to be solved. In the above 1, since the packet is divided into a plurality of cells to form a cell, each cell occupies an information area of 8 to 10 bytes including 5 bytes of the ATM header and other headers. Since the payload of a cell is usually 48 bytes, 8 to 10 bytes of this header causes a large loss of information area. Further, in the above item 2, a large loss of the information area due to the header does not occur. However, when the packet size is large, the transmission time for each packet becomes long. The above-mentioned problems to be solved remain.

[0005]

The present invention adopts the following constitution in order to solve the above points. <Structure 1> A packet division device for forming a frame from a packet supplied from an upper layer and transmitting the formed frame to a plurality of lines. A size information acquisition unit that acquires size information indicating a packet size, and a value related to the packet size of the packet, which holds the value that is a threshold value for determining whether to divide the packet from the upper layer And a changeover switch having two output terminals, the changeover switch receiving the packet from the size information acquisition unit and outputting the received packet from any one of the output terminals, The size information is received from the size information acquisition unit, and the size information and the threshold value in the threshold value storage unit are combined. A comparing unit for comparing and setting an output destination of the packet in the changeover switch based on a result of the comparison; and receiving the packet from one of the output terminals of the changeover switch and dividing the received packet into a plurality of packets. A packet dividing unit that accepts the divided packet from the packet dividing unit, or accepts the packet from the other output terminal of the changeover switch to form a frame from the packet,
A distributor that distributes the formed frame to a plurality of lines,
A first-in first-out section that calculates a queue usage rate indicating the congestion level of the line, and accepts the queue usage rate from the first-in first-out section, and the queue usage rate exceeds a usage rate threshold value that is a predetermined value. And when it is determined that there is an increasing tendency,
When the threshold value of the threshold value storage unit is increased by a predetermined value and it is determined that the queue usage rate is equal to or less than the usage rate threshold value and tends to decrease, the threshold value of the threshold value storage unit is determined in advance. And a threshold increase / decrease instruction unit for decreasing the value,
The comparison unit determines that the comparison result is the packet size>
When the threshold value is set, the changeover switch is set to output the packet from the one output terminal of the changeover switch, and when the packet size ≦ the threshold value, the packet is output from the other output terminal of the changeover switch. A packet dividing device characterized in that the changeover switch is set to be output.

[0006] <Configuration 2> to form a frame from the packet supplied from the upper layer, a dividing apparatus of a packet for sending a frame the formed plurality of lines, receives a packet from the higher layer, A size information acquisition unit that acquires size information indicating the packet size of this packet, and a value related to the packet size of the packet, which is a threshold value for determining whether to divide the packet from the upper layer. A changeover switch having a threshold value storage unit for holding a value and two output terminals, the changeover switch receiving the packet from the size information acquisition unit and outputting the received packet from any one of the output terminals. And accepting the size information from the size information acquisition unit, the size information and the threshold value storage unit A comparison unit that compares the packet with the threshold value and sets an output destination of the packet in the changeover switch based on the result of the comparison, and receives the packet from one of the output terminals of the changeover switch, and the received packet And a packet dividing unit that divides the packet into a plurality of packets, or that receives the divided packet from the packet dividing unit or receives the packet from the other output terminal of the changeover switch to form a frame from the packet. ,
A distributor that distributes the formed frame to a plurality of lines,
From the upper layer, accept an allowable transfer time that represents the time allowed to transfer one packet, calculate the threshold value based on the allowable transfer time, and store the threshold value in the threshold value storage unit. A threshold calculation unit, a first-in first-out unit that calculates a queue usage rate indicating the congestion level of the line, and the queue usage rate is accepted from the first-in first-out unit, and the queue usage rate is a predetermined value. If a certain usage rate threshold value is exceeded and it is determined that there is an increasing tendency, the threshold value of the threshold value storage unit is increased by a predetermined value, and the queue usage rate becomes less than or equal to the usage rate threshold value, and a decreasing tendency. And a threshold increase / decrease instruction unit that decreases the threshold value of the threshold value storage unit by a predetermined value, and the comparison unit, when the comparison result is the packet size> the threshold value, Changeover switch The changeover switch is set from the one output terminal of the pitch in order to output the packet,
A packet dividing device, wherein when the packet size ≦ the threshold value, the changeover switch is set to output the packet from the other output terminal of the changeover switch.

[0007]

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. In the present invention, a packet with a large packet size is divided, and the divided packet is
Framed and transmitted in parallel. On the other hand, packets with a small packet size are framed without being divided.
Which it is transmitted. Whether or not the above-mentioned packet division is necessary is determined based on the packet size that is set in advance as a threshold value.
Be done.

That is, it is an object of the present invention to simultaneously solve the problems of the transmission time which becomes a problem when the packet size is large and the transmission efficiency which becomes a problem when the packet size is small. In order to achieve such an object, the following configuration is provided.

<Structure of Concrete Example 1> FIG. 1 is a block diagram of Concrete Example 1. From FIG. 1, the dividing device 1 according to the first example.
Is a size information acquisition unit 2, a comparison unit 3, and a threshold value storage unit 4.
, A changeover switch 5, a packet division unit 6, and a distribution unit 7.

The size information acquisition unit 2 is a unit that measures the packet size received from the upper layer 10 and sends the size information as the measurement result to the comparison unit 3. The comparison unit 3 is a unit that receives the size information from the size information acquisition unit 2 and the threshold value from the threshold value storage unit 4 and compares them. If the packet size is smaller than the threshold value, the changeover switch 5 is connected to the terminal A, and if the packet size is larger than the threshold value, the changeover switch 5 is connected to the terminal B.

The threshold storage unit 4 is a portion in which a threshold of a predetermined packet size is stored. The changeover switch 5 is a portion that receives a packet from the size information acquisition unit 2 and outputs the packet to the terminal A or the terminal B under the control of the comparison unit 3. The packet division unit 6 is a unit that receives a packet having a packet size larger than a threshold value from the terminal B of the changeover switch 5, divides the packet into the number of lines, and sends the divided packet to the distribution unit 7. The distribution unit 7 is a unit that distributes the received packet to the connected transmission circuit 8 in frame units.

<Operation of Specific Example 1> Before describing the operation of Specific Example 1, the basic principle of the present invention will be described with reference to the drawings. FIG. 2 is a comparative explanatory diagram of transmission times. FIG. 3 is a comparative explanatory diagram of payload usage efficiency.
In both figures, the horizontal axis represents the packet size (number of bytes). The vertical axis represents the transmission time (FIG. 2) and the payload usage efficiency (FIG. 3).

In both figures, (1) is divided into cell units for transmission, (2) is transmitted without dividing packets, and (3) is divided according to the present invention. It represents the case of transmission by transmission. However, the number of divisions is 4 as an example
In other words, if the number of transmitting circuits 8 in FIG.
Shows the graph when set to. Furthermore, the threshold value is temporarily set to 2048 bytes.

What can be understood from FIG. 2 is as follows. It can be seen that (2) has the longest transmission time.
(3) is exactly the same as (2) until it reaches the threshold value, and when it exceeds the threshold value, it is divided into four and transmitted, so the transmission time becomes about 1/4. However, since there is a newly added header, it becomes longer accordingly. In (1), after being divided into cells, it is distributed to 4 lines, but since the newly added header reaches about 20% of the payload, the transmission time is about 1
It will be considerably longer than / 4.

What can be understood from FIG. 3 is as follows. It can be seen that (2) has the highest payload usage efficiency. That is, it can be seen that the byte length of the newly added header can be ignored compared to the packet length in the range exceeding the threshold. Until (3) reaches the threshold,
It is exactly the same as (2), and when it exceeds the threshold value, it is divided into four and transmitted. However, even if it is divided, the byte length of the newly added header can be ignored compared to the packet length. . That is, it can be seen that the payload usage efficiency is almost equal to (2). In (1), it can be seen that, after being divided into cells, the newly added header reaches about 20% of the payload. That is, it can be seen that the payload usage efficiency is the worst.

In order to realize the basic principle described above, the dividing device 1 (FIG. 1) according to the specific example 1 operates as follows. FIG. 4 is an operation explanatory diagram of the first specific example. S1 in FIG.
The operation of the dividing device 1 (FIG. 1) according to the first specific example will be described along the operation steps from to S5.

S1. The packet input size information acquisition unit 2 (FIG. 1) receives a packet from the upper layer 10 (FIG. 1) and measures the packet size. The size information as the measurement result is sent to the comparison unit 3 (FIG. 1) and the packet is transferred to the changeover switch 5 (FIG. 1).

S2. Packet size> threshold Here, the threshold is temporarily set to 2048 bytes. The comparison unit 3 (FIG. 1) that has received the size information compares the packet size with the threshold value received from the threshold value storage unit 4 (FIG. 1). As a result of the comparison, when the packet size> the threshold value, the changeover switch 5 (FIG. 1) is connected to the terminal B and the process proceeds to S3. Alternatively, as a result of comparison, when the packet size ≦ threshold, the changeover switch 5 (FIG. 1) is connected to the terminal A and S4
Fly to. First, the case of packet size> threshold value will be described.

S3. Dividing the packet into the number of lines The packet dividing unit receives the packet and divides it into four (temporarily fixing the number of lines to 4), and sends it to the distributing unit 7. still,
When the packet size ≦ threshold value in S2, the packet is directly sent from the changeover switch 5 (FIG. 1) to the distribution unit 7 (FIG. 1).

S4. Distribute to each transmission circuit 8 (FIG. 1) The distribution unit 7 (FIG. 1) newly adds a header to the received information, frames it, and distributes it to each transmission circuit 8 (FIG. 1). S5. The frame distributed to the transmission / transmission circuit 8 (FIG. 1) on each line is transferred to the reception side via the line. With the above operation, the operation based on the above operation principle (FIGS. 2 and 3) is completed. In the explanation of the operation, the number of lines is fixed to 4 for convenience of explanation, but the number of lines is arbitrarily set depending on the type of information to be transmitted, the state of the network and the like.

<Effects of Specific Example 1> As described above, with the threshold as the boundary, the packet having a scale size larger than the threshold is divided and transferred, and the packet having the scale size smaller than the threshold is not divided and is directly transmitted. Since it is transferred, the following effects are obtained.

1. Both of the problems, that is, the transmission time that becomes a problem when the packet size is large and the transmission efficiency that becomes a problem when the packet size is small, are solved at the same time. 2. Furthermore, since the threshold value can be set arbitrarily, a compromise between transmission time and transmission efficiency, which differs depending on the type of data to be transmitted, can be set freely.

<Second Specific Example> FIG. 5 is a block diagram of a second specific example. From FIG. 5, the dividing device 11 according to the second specific example is
A size information acquisition unit 2, a comparison unit 3, a threshold value storage unit 4,
Changeover switch 5, packet dividing unit 6, and distributing unit 7
And a threshold calculator 9.

Only the differences from Example 1 will be described.
The threshold calculation unit 9 is a unit that receives the allowable transfer time from the upper layer 10, calculates the threshold, and stores the calculated threshold in the threshold storage unit 4. Here, the allowable transfer time is the time allowed to transfer one packet, and the type of network,
It depends on the type of information to be transferred. From this allowable transfer time, the threshold is calculated by the following equation. [Threshold value] = ([Allowable transfer time] −α) × (Transmission capacity of one line) (Equation 1) However, α is a factor other than the transmission delay time, for example, a processing time in the device. The other configuration is exactly the same as that of the first specific example.

FIG. 6 is an operation explanatory diagram of the second specific example. The operation of the dividing device 11 (FIG. 5) according to the second specific example will be described along the operation steps from s1 to s7 in FIG.

S1. From the allowable transmission time input upper layer 10 (FIG. 5) to the threshold calculation unit 9 (FIG. 5),
Receive the allowed transfer time. This allowable transfer time is a value that differs depending on the type of information and the like. s2. The threshold value calculation unit 9 (FIG. 5) that calculates the threshold value calculates the threshold value based on the allowable transfer time received from the upper layer 10 (FIG. 5), and stores the result in the threshold value storage unit 4 (FIG. 5). . Here, the calculation of the threshold value is performed by the above-mentioned (Formula 1). s3. The packet input size information acquisition unit 2 (FIG. 5) accepts a packet from the upper layer 10 (FIG. 5) and measures the packet size. The size information as the measurement result is sent to the comparison unit 3 (FIG. 5) and the packet is transferred to the changeover switch 5 (FIG. 5).

S4. Packet size> threshold Here, the threshold is temporarily set to 2048 bytes. The comparison unit 3 (FIG. 5) that has received the size information compares the packet size with the threshold value received from the threshold value storage unit 4 (FIG. 5). As a result of the comparison, when the packet size> the threshold value, the changeover switch 5 (FIG. 5) is connected to the terminal B and the process proceeds to s5. Alternatively, as a result of the comparison, when the packet size ≦ the threshold value, the changeover switch 5 (FIG. 5) is connected to the terminal A and s6
Fly to. First, the case of packet size> threshold value will be described.

S5. Dividing the packet into the number of lines The packet dividing unit receives the packet and divides it into four (temporarily fixing the number of lines to 4), and sends it to the distributing unit 7. still,
When the packet size ≦ threshold value in S2, the packet is directly sent from the changeover switch 5 (FIG. 5) to the distribution unit 7 (FIG. 5).

S6. Distribute to each transmitting circuit 8 (FIG. 5) The distributing unit 7 (FIG. 5) newly adds a header to the received information, forms a frame, and distributes to each transmitting circuit 8 (FIG. 5). s7. The frame distributed to the transmission / transmission circuit 8 (FIG. 5) on each line is transferred to the reception side via the line. With the above operation, the operation based on the above operation principle (FIGS. 2 and 3) is completed. In the explanation of the operation, the number of lines is fixed to 4 for convenience of explanation, but the number of lines is arbitrarily set depending on the type of information to be transmitted, the state of the network and the like.

<Effect of Specific Example 2> The following effects are obtained by including the threshold value calculation unit 9 which receives the allowable transfer time from the upper layer 10 and calculates the threshold value. 1. Thresholds can be set according to the requirements of higher layers. 2. As a result, depending on the type of transmission information, the transmission time and
It is possible to freely select which of the payload usage efficiency is to be prioritized.

<Third Specific Example> FIG. 7 is a block diagram of a third specific example. From FIG. 7, the dividing device 21 according to the third specific example is
A size information acquisition unit 2, a comparison unit 3, a threshold value storage unit 4,
Changeover switch 5, packet dividing unit 6, and distributing unit 7
A first-in first-out unit (FIFO) 12 and a threshold increase / decrease instruction unit 13.

Only the differences from Example 1 will be described.
The first-in first-out unit 12 is a unit that measures the congestion level of the lines and sends the queue usage rate to the threshold increase / decrease instruction unit 13.
Note that the first-in first-out unit 12 can be configured as software by measuring the number of received information and the number of transferred information by using a general-purpose buffer memory or the like.

The threshold value increase / decrease instructing unit 13 is provided in the first-in first-out unit 12
If the queue usage rate is accepted from the above, and it is determined that the queue usage rate exceeds a certain value (usage rate threshold value) and there is an increasing tendency, the threshold value stored in the threshold value storage unit 4 is set in advance. It is the part that increases a certain value. Similarly, when it is determined that the queue usage rate is below a certain value and there is a decreasing tendency, the threshold value stored in the threshold value storage unit 4 is decreased by a predetermined value. The other parts are exactly the same as in the first specific example.

Next, the operation of the threshold value increase / decrease instruction section 13 will be described. FIG. 8 is an operation explanatory diagram of the threshold value increase / decrease instruction unit. The operation of the threshold value increase / decrease instructing unit 13 (FIG. 7) provided in the specific example 3 will be described along the operation stages P1 to P6 in FIG. P1. The queue usage rate input threshold increase / decrease instruction unit 13 (FIG. 7) receives the queue usage rate from the first-in first-out unit 12 (FIG. 7) at regular intervals.

P2. Queue usage rate> usage rate threshold value threshold increase / decrease instruction unit 13 (FIG. 7) checks whether the received queue usage rate exceeds a predetermined queue threshold value. When the queue usage rate> the usage rate threshold, the process proceeds to P3, and when the queue usage rate ≦ the usage rate threshold, the process proceeds to P5. First, the case of queue utilization> usage threshold will be described.

P3. increase? The threshold value increase / decrease instruction unit 13 (FIG. 7) determines whether the received queue usage rate has an increasing tendency. If it does not increase, the operation ends. If it is increasing, proceed to P4.

P4. Threshold increase instruction The threshold increase / decrease instruction unit 13 (FIG. 7) increases the threshold value stored in the threshold storage unit 4 (FIG. 7) which is a predetermined value, and ends the operation. Next, the case of queue usage rate ≦ usage rate threshold value in P2 will be described.

P5. Decrease? The threshold increase / decrease instruction unit 13 (FIG. 7) determines whether the received queue usage rate is in a decreasing tendency. If it does not tend to decrease, the operation ends. If it is decreasing, proceed to P6.

P6. Threshold decrease instruction The threshold increase / decrease instruction unit 13 (FIG. 7) decreases the threshold value stored in the threshold storage unit 4 (FIG. 7) by a predetermined value, and ends the operation. The dividing device 21 according to the third specific example will be described below.
P4. Threshold increase instruction, and P6. Based on the threshold value stored by the threshold value reduction instruction, exactly the same operation as in the first specific example is executed. In addition, P1. The above-described operation is repeated each time the threshold increase / decrease instruction unit 13 (FIG. 7) receives the queue usage rate from the first-in first-out unit 12 (FIG. 7) at regular intervals by inputting the queue usage rate.

Concrete example 3 for executing the above operation is suitable for the following operation. That is, the initial value stored in the threshold value storage unit 4 (FIG. 7) is set to a small value. Therefore, in the initial state, the transmission time is prioritized over the payload usage efficiency. In principle, a packet is divided into a plurality of frames for transmission. Thereafter, when the line capacity becomes insufficient, the threshold value is increased and the division is suppressed. As a result, the payload usage efficiency is improved and the shortage of line capacity is alleviated. Also,
When the lack of capacity is resolved, the queue usage will decrease. Therefore, the threshold value increase / decrease instruction unit 13 (FIG. 7) decreases the threshold value, and the packet is divided again to shorten the transmission time.

<Effect of Concrete Example 3> By adding the first-in first-out unit (FIFO) 12 and the threshold value increasing / decreasing instruction unit 13 to the structure of the concrete example 1, the utilization status of the line is reflected in the threshold value. The effective use of the line is automatically achieved.

[Brief description of drawings]

FIG. 1 is a block diagram of a specific example 1. FIG.

FIG. 2 is a comparative explanatory diagram of transmission times.

FIG. 3 is a comparative explanatory diagram of payload usage efficiency.

FIG. 4 is an operation explanatory diagram of the first specific example.

FIG. 5 is a block diagram of a specific example 2.

FIG. 6 is an operation explanatory diagram of the second specific example.

FIG. 7 is a block diagram of a specific example 3;

FIG. 8 is an operation explanatory diagram of a threshold value increase / decrease instruction unit.

[Explanation of symbols]

1 dividing device 2 Size information acquisition section 3 comparison section 4 Threshold storage 5 Changeover switch 6 Packet division unit 7 Distributor 8 Transmitter circuit 10 Upper layer

─────────────────────────────────────────────────── ─── Continuation of front page (72) Hidenori Nakazato 1-7-12 Toranomon, Minato-ku, Tokyo Inside Oki Electric Industry Co., Ltd. (72) Hiroshi Ishida 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (56) Reference JP-A-5-153183 (JP, A) JP-A-7-79250 (JP, A) JP-A-63-92140 (JP, A) JP-A-64- 60041 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/28 H04L 12/56

Claims (2)

(57) [Claims] 1. From a packet supplied from an upper layer
Form a frame and connect the formed frame to multiple lines
A dividing apparatus of a packet for sending and receiving packets from the higher layer, a size information acquiring unit that acquires the size information indicating the packet size of the packet, a value for the packet size of the packet, the Up
Determine whether to split the packet from the next layer
A threshold value storage unit that holds the value as a because of the threshold, a changeover switch having two output terminals, receives the packet from the size information obtaining unit, receiving
Output the output packet from one of the output terminals.
A changeover switch for receiving the size information from the size information acquisition unit and comparing the size information with the threshold value in the threshold value storage unit.
The changeover switch based on the result of the comparison.
A comparing unit takes to set the output destination of the packet, it receives the packet from one of said output terminals of said changeover switch, dividing the accepted packets into a plurality
A packet dividing unit for, accept the divided packets from the packet splitting unit, or receives the packets from the other of said <br/> output terminal of the selector switch, the packet
And a distribution unit that distributes the formed frame to a plurality of lines, and a first-in destination that calculates a queue usage rate that indicates the congestion level of the lines.
Accepting the queue usage rate from the outbound and the first-in first-out,
This queue usage rate exceeds a usage rate threshold value that is a predetermined value.
And if it is determined that there is an increasing tendency, the threshold value
The threshold value of the storage unit is increased by a predetermined value, and the queue
The usage rate is below the usage rate threshold and tends to decrease.
If it is determined that the threshold value in the threshold value storage unit is set in advance,
A threshold value increase / decrease instruction unit for decreasing a predetermined value, wherein the comparison unit determines that the comparison result is the packet size>
At the threshold value, the one output terminal of the changeover switch
The switching switch so as to output the packet from a child
Set, when the packet size ≦ the threshold value, the switching
Output the packet from the other output terminal of the switch.
A packet splitting device, characterized in that the changeover switch is set to force the packet. 2. From a packet supplied from an upper layer
Form a frame and connect the formed frame to multiple lines
A packet dividing device for sending, which accepts a packet from the upper layer and transmits this packet.
Size to get the size information indicating the packet size of the packet
The value related to the information acquisition unit and the packet size of the packet,
Determine whether to split the packet from the next layer
A threshold value storage unit for holding the value serving as a threshold value for switching, and a changeover switch having two output terminals,
Accept the packet from the size information acquisition unit
Output the output packet from one of the output terminals.
Change switch and accepts the size information from the size information acquisition unit
And compares the size information with the threshold value in the threshold value storage unit.
The changeover switch based on the result of the comparison.
The packet is output from one of the output terminals of the selector switch and the comparison unit that sets the output destination of the packet.
The received packet and divide the received packet into multiple packets
And a packet dividing unit that receives the divided packets from the packet dividing unit.
Turn on or the other of the changeover switches
Accept the packet from the output terminal and
To form a frame from the
A distribution unit for distributing to the line, from said upper layer, to accept the allowable transfer time representing the acceptable time to transfer one of said packets, those
First in, first calculating calculates the threshold value based on the allowable transfer time, and a threshold calculating unit for storing the threshold value to the threshold storage unit, a queue utilization indicating the congestion of the line
Accepting the queue usage rate from the outbound and the first-in first-out,
This queue usage rate exceeds a usage rate threshold value that is a predetermined value.
And if it is determined that there is an increasing tendency, the threshold value
The threshold value of the storage unit is increased by a predetermined value, and the queue
The usage rate is below the usage rate threshold and tends to decrease.
If it is determined that the threshold value in the threshold value storage unit is set in advance,
A threshold value increase / decrease instruction unit for decreasing a predetermined value, wherein the comparison unit determines that the comparison result is the packet size>
At the threshold value, the one output terminal of the changeover switch
Use the changeover switch to output the packet from the child
Set, and when the packet size ≤ the threshold, the switching
Output the packet from the other output terminal of the switch.
A packet splitting device, characterized in that the changeover switch is set to force the packet.