JP2007158640A - Band-limiting method and apparatus, and network communication apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new band limiting method and apparatus capable of limiting a transmission rate, without having to performing rate measurments. <P>SOLUTION: On the basis of the maximum band BW<SB>MAX</SB>, the minimum band BW<SB>MIN</SB>and a packet-length Length that has been transmitted immediately before, packet intervals GAP<SB>BW-MAX</SB>and GAP<SB>BW-MIN</SB>are respectively generated. The time elapsed from the point of time of completing packet transmission and the packet intervals GAP<SB>BW-MAX</SB>and GAP<SB>BW-MIN</SB>are compared, and maximum band notifying signals S<SB>MAX</SB>and minimum band notifying signals S<SB>MIN</SB>are respectively outputted to a transmission determination part 100. The transmission determination part determines the transmission priority from the notifying signals. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bandwidth limiting method and apparatus for transmitting data at an appropriate rate to a network, and a network communication device using the same.

  In recent broadband environments, various services such as video, audio, and data have been developed, and more efficient network construction has been required in a limited band. In order to smoothly operate such a network, a router having a bandwidth limiting function for guaranteeing a minimum bandwidth or setting an upper limit of bandwidth for each packet flow or service has been proposed.

  For example, in the packet transfer rate monitoring and control apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-237841 (Patent Document 1), the packet transfer rate is measured using the transfer interval and the received packet length of the received packet, and the measured value and the maximum The priority order is determined by comparing the limit rate and the minimum guaranteed rate, and the surplus bandwidth is distributed fairly (see, for example, paragraphs 0006 and 0029 of Patent Document 1).

Japanese Patent Laid-Open No. 2002-237841

  The bandwidth limiting function described in Patent Document 1 controls the packet transfer rate based on the measured value of the packet transfer rate. If the rate control can be executed without measuring the packet transfer rate, the circuit configuration is changed. It can be simplified and integration into a digital IC is facilitated.

  Therefore, an object of the present invention is to provide a new band limiting method and apparatus that enables transmission rate limiting without performing rate measurement, and a network communication device using the same.

  The bandwidth limiter according to the present invention limits the bandwidth of each flow based on a plurality of set bandwidths set for each of the plurality of flows, and generates a packet interval that satisfies each condition of the plurality of set bandwidths. The transmission priority of the next packet in each flow is determined based on a comparison between the elapsed time from the packet transmission completion time and the packet interval.

  More specifically, the packet until the start of transmission of the next packet based on each of the plurality of set bands and the packet length of the transmitted packet, based on the measurement means for measuring the elapsed time from the packet transmission completion time point Packet interval generation means for generating an interval, comparison means for comparing the elapsed time and the packet interval, and transmission priority of the next packet in the flow based on the comparison result for each of the plurality of set bands Transmission determining means. The transmission determination unit can permit or prohibit packet transmission of each flow according to the transmission priority.

  It is desirable that the transmission priority includes a high transmission priority when the bandwidth is below the minimum bandwidth and a low transmission priority when the bandwidth is equal to or higher than the minimum bandwidth. The transmission determination is executed so as to permit transmission of a packet having a low transmission priority when there is no packet having a high transmission priority.

  As described above, according to the present invention, a packet interval that satisfies each condition of a plurality of set bands is generated, and the next packet in each flow is compared based on a comparison between the elapsed time from the packet transmission completion time and the packet interval. Determine the transmission priority. Therefore, it is possible to disable transmission during a period when the packet interval is not reached, to satisfy the maximum bandwidth condition, and to generate transmission permission so as to guarantee the minimum bandwidth according to the elapsed time. Rate control can be performed without measuring the packet transfer rate. That is, it is not necessary to perform complicated control of adjusting the packet interval by measuring the packet transfer rate and comparing it with the maximum bandwidth and the minimum bandwidth as in the conventional case.

  Further, the transmission determination unit can easily determine whether or not transmission is possible simply by monitoring the comparison result of the comparison unit, and the transmission rate can be controlled with a relatively simple logic configuration. In particular, since the band limiting device can be realized with a logic configuration, integration into a digital IC such as a CPU or a medium access control device is facilitated.

FIG. 1 is a block diagram showing an example of a network system for requesting and providing a service through a router having a bandwidth limiting device according to an embodiment of the present invention. In this network system example, it is assumed that the router 10 accommodates a plurality of terminals T _{1 to} T _N (N is an integer of 2 or more) and has a bandwidth limiting function according to the present invention.

Router 10 is a network communication device, a plurality of servers S ₁ -S M each terminal through the network 20 _(M is an integer of 2 or more) connected to one of, individual service from the server for each terminal Make provision possible. Here, the terminal T ₁ is connected to the server S ₁ to receive video data service provision, and the terminal T ₂ is connected to the server S ₂ to provide voice data (VoIP: Voice over IP) service provision to the terminal T _3. Are connected to the server S ₃ to receive Internet communication data services.

In general, a large bandwidth is required for video data communication between the terminal T ₁ and the server S ₁ , but not so much bandwidth is required for audio data communication between the terminal T ₂ and the server S ₂ . However, real-time performance is required for video and audio distribution, and the shortage of bandwidth directly affects the quality that can be easily judged by the user, such as image quality and sound quality, so it is necessary to guarantee a minimum bandwidth.

On the other hand, the Internet communication data between the terminal T ₃ and the server S ₃ need not guarantee a minimum bandwidth unless real-time performance is particularly required. However, securing a large bandwidth for services such as video data distribution and voice communication results in a decrease in the communication speed of the Internet communication data service. Therefore, under circumstances where there is an upper limit on the bandwidth used by the network, the system administrator or user sets the upper limit of the bandwidth used, and it is possible to use the bandwidth fairly according to the characteristics of each service. It is important to adjust the bandwidth allocation.

In the example shown in FIG. 1, for example, video communication between the terminal T ₁ and the server S ₁ is limited to a maximum of 50 Mbps and guaranteed a minimum of 20 Mbps. Similarly, the voice communication between the terminal T ₂ and the server S ₂ is limited to a maximum of 10 Mbps, and a minimum of 1 Mbps is guaranteed. Internet communication between the terminal T ₃ and the server S ₃ is limited to a maximum of 50 Mbps, and the minimum bandwidth is not guaranteed. Such band allocation adjustment and limitation are executed by the bandwidth limiting apparatus according to the present embodiment.

  FIG. 2 is a block diagram showing a schematic functional configuration of a router having the bandwidth limiting device according to the present embodiment. However, in FIG. 2, the configuration along the packet flow is illustrated so that the operation can be easily understood.

  In FIG. 2, the router 10 is provided with a CPU 11 and a memory 12 for executing control of the entire router. The CPU 11 is a program control processor and executes control of the entire apparatus and routing processing according to a program stored in the memory 12. The memory 12 includes a recording device such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

  The CPU 11 is connected to the band limiting circuit 14 via the buffer 13 and further connected to the wide area network WAN 20 through the medium access control device MAC (WAN), the physical layer device PHY (WAN), the transformer (WAN), and the connector (WAN). Data transmission / reception to / from the WAN 20 is performed. On the other hand, the CPU 11 is connected to the local area network LAN 30 through the buffer 15, the medium access control device MAC (LAN), the physical layer device PHY (LAN), the transformer (LAN), and the connector (LAN), and transmits / receives data to / from the LAN 30. I do. The buffers 13 and 15 may be configured separately from FIFO memories, but a part of the memory 12 may be used as a buffer.

  The band limiting circuit 14 according to the present embodiment is connected between the buffer 13 and the medium access control device MAC (WAN), and limits the band of transmission data to the WAN 20 under the control of the CPU 11. Hereinafter, the configuration and operation of the band limiting circuit 14 will be described in detail.

  FIG. 3 is a functional block diagram showing an example of the band limiting circuit according to the present embodiment. Here, it is assumed that the band limiting circuit 14 performs transmission band control of a plurality (N) of packet flows. N is an arbitrary integer of 2 or more.

A band limiting circuit 14 shown in FIG. 3, the band calculating unit performs band limitation BWCAL ₁ -BWCAL _N are provided for the transmission circuit TX ₁ -TX _N respectively corresponding to the N transmit band. The bandwidth calculation unit BWCAL _i (i = integer from 1 to N) outputs a maximum bandwidth notification signal S _MAXi and a minimum bandwidth notification signal S _MINi to be described later to the transmission determination unit 100, and a selection permission signal S _Pi corresponding to them. Are respectively transferred to the transmission circuit TX _i . Each transmission circuit transmits the transmission data of the band to the WAN 20 if the input selection permission signal is active.

The transmission determination unit 100 determines whether or not data transmission of the band is possible, in other words, the priority order from the maximum band notification signal S _MAXi and the minimum band notification signal S _MINi input from each band calculation unit BWCAL _i according to the logic described later. The transmission determination unit 100 may be configured by hardware as one determination logic circuit, but can also be realized by executing a program on the CPU 11.

FIG. 4 is a block diagram illustrating an example of the band calculation unit BWCAL in the present embodiment. The bandwidth calculation unit BWCAL is provided with a maximum bandwidth setting register 101 and a minimum bandwidth setting register 102. The CPU 11 sets a maximum data transfer bandwidth (maximum communication rate) BW _MAX and a minimum data transfer bandwidth (minimum communication rate) BW _MIN , respectively. Is set. For example, in a transmission line with a total bandwidth of 100 Mbps such as 100BASE-TX, the maximum bandwidth BW _MAX = 50 Mbps and the minimum bandwidth BW _MIN = 33 Mbps are set. The transmission byte counter 103 counts the number of bytes of the transferred packet and always holds the number of bytes of the packet transferred immediately before.

The maximum bandwidth GAP generation unit 104 calculates the packet interval GAP _{BW = MAX} necessary for transfer at the maximum rate, using the maximum bandwidth BW _MAX from the register 101 and the number of previous packet bytes Length from the transmission byte counter 103. To do. Similarly, the minimum bandwidth GAP generation unit 105 uses the minimum bandwidth BW _MIN from the register 102 and the number of previous packet bytes Length from the transmission byte counter 103, and the packet interval GAP _BW− necessary for performing transfer at the minimum rate. Calculate _MIN . These packet intervals GAP can be calculated by equation (1).

In Equation (1), TR is the transmission rate (kbit), and BW is the maximum bandwidth BW _MAX or the minimum bandwidth BW _MIN (kbit). When a packet of Length byte = (Length × 8) bits is transmitted at the transmission rate TR, the interval GAP until the subsequent packet is transmitted is
(Length × 8) :( Length × 8 + GAP) = BW: TR
It can be obtained from the proportional expression.

For example, in a transmission line with a transmission rate TR = 100 Mbps (= 100000 kbps), when the maximum bandwidth BW _MAX = 20 Mbps (= 20000 kbps) and the number of previous packet bytes Length = 1500 bytes,
GAP _{BW = MAX} = ((100000-20000) × 1500 × 8) / 20000
= 48000 (bit)
It becomes. In this case, the packet transmission interval GAP _{BW = MAX} = 48000 bits means that if the next packet is transmitted after the elapse of time corresponding to an interval four times the transmitted packet (1500 × 8 = 12000 bits), the maximum bandwidth BW _MAX = This means that data transfer of 20 Mbps is performed.

  Therefore, comparators 106 and 107 and a time counter 108 are provided to compare the packet transmission interval GAP and the elapsed time. The time counter 108 starts when the previous packet transmission is completed, and sequentially increases the count number C according to the transfer clock for data communication. For example, 100BASE-TX counts according to a 100 MHz clock.

The comparator 106 compares the maximum bandwidth packet interval GAP _{BW = MAX} with the elapsed count value C and outputs a maximum bandwidth notification signal S _MAX indicating whether or not the elapsed time C has reached GAP _{BW = MAX} . Similarly, the comparator 107 compares the minimum bandwidth packet interval GAP _BW-MIN and the elapsed time count value C, and outputs a minimum bandwidth notification signal S _MIN indicating whether or not the elapsed time C has reached GAP _BW-MIN. .

Transmission determination unit 100 determines a packet transmission priority from the maximum bandwidth notification signal S _MAX and minimum bandwidth notification signal S _MIN, determines packet transmission capability of each flow accordingly. Hereinafter, when the elapsed time C does not reach the maximum bandwidth packet interval GAP _{BW = MAX} (when GAP _{BW = MAX} > C), S _MAX = 1, and after reaching (when GAP _{BW = MAX} ≦ C), S Similarly, when _MAX = 0 and the elapsed time C has not reached the minimum bandwidth packet interval GAP _BW-MIN (when GAP _BW-MIN > C), S _MIN = 1, and after arrival (GAP _BW-MIN ≦ (C), assuming that S _MIN = 0, the transmission determination operation of the transmission determination unit 100 will be described.

FIG. 5 is a timing chart for explaining the transmission determination operation in this embodiment. Here, the case where the maximum bandwidth BW _MAX = 50 Mbps and the minimum bandwidth BW _MIN = 33 Mbps is set in the transmission path of 100 Mbps for all bands such as 100BASE-TX.

As shown in FIG. 5A, data on the LAN 20 is actually transmitted to the WAN 30 in the transmission period 201, and time T (corresponding to the number of transmission bytes Length × 8 [bit]) is required until packet transmission is completed. Shall be. In this example, since the entire bandwidth is set to the maximum bandwidth BW _MAX = 50 Mbps on the transmission path of 100 Mbps, the maximum bandwidth GAP generation unit 104 is set at the same time interval as the packet transmission period 201 (= T) according to the equation (1). Since the corresponding packet transmission interval GAP _{BW = MAX} is generated and the minimum bandwidth GAP generation unit 105 is set to the minimum bandwidth BW _MIN = 33 Mbps, the packet transmission interval GAP _BW corresponding to a time interval almost twice as long as the time T _-MIN is generated.

Therefore, as shown in FIG. 5B, the maximum bandwidth notification signal S _MAX output from the comparator 106 rises at the time point 0 and rises at the time point 2 ^* T (the calculation is not exactly twice, so “2 ^* "T" is displayed.) As shown in FIG. 5C, the minimum band notification signal S _MIN rises at time 0 and rises at time 3 ^* T (displayed as “3 ^* T” because it is not exactly three times in the calculation). Go down.

The transmission determination unit 100 receives the maximum band notification signal S _MAX and the minimum band notification signal S _MIN as shown in FIGS. 5B and 5C, and determines whether transmission is possible as follows.

(1) Since S _MAX = 1 and S _MIN = 1 from time T when packet transmission is completed to time 2 ^* T, it is determined that the transmission is impossible period 202 and transmission of the transmission data is not permitted. That is, the transmission is prohibited only for the same time as the time T required for data transmission so as not to exceed the maximum bandwidth BW _MAX (transmission prohibited).

(2) Since S _MAX = 0 and S _MIN = 1 from time point 2 ^* T to time point 3 ^* T, it is determined that the transmission is possible period 203 and the transmission prohibition is canceled. However, since it does not fall below the minimum bandwidth BW _MIN , there is no need to actively start transmission. Therefore, in this case, as long as there is no other transmission data below the minimum bandwidth, transmission may be executed (low priority).

(3) Since S _MAX = 0 and S _MIN = 0 after time point 3 ^* T, it is determined that the transmission period 204 is below the minimum bandwidth BW _MIN and needs to be actively transmitted (high) priority).

In this way, the four states including the transmission state are managed by the two signals of the maximum band notification signal _SMAX and the minimum band notification signal _SMIN , and the transmission priority is determined depending on which state is present. Therefore, it is possible to limit the bandwidth without measuring the packet transfer rate. Further, as shown in FIG. 4, the bandwidth calculation unit BWCAL can be realized with a counter-based logic configuration, and is suitable for integration. .

  FIG. 6 is a block diagram showing a configuration of a band limiting circuit according to an embodiment of the present invention. Here, a case where four types of band limitation are performed is shown. By adding a bandwidth calculation unit, it is possible to easily cope with more bandwidth settings. However, in today's broadband situation, with the provision of various services such as video, audio, and data, there are many cases where four types of bandwidth limitations are required for use of the device, so four transmission circuits are supported here. The case is illustrated.

The band limiting circuit is provided with band calculation units BWCAL ₁ -BWCAL ₄ that perform band limiting on transmission circuits TX ₁ -TX ₄ (not shown) respectively corresponding to four transmission bands. Each band calculation unit BWCAL _i (i = 1 to an integer of 1 to 4) can be realized by the logic configuration shown in FIG. Each band calculation unit BWCAL _i outputs the already described maximum band notification signal S _MAXi and minimum band notification signal S _MINi to the transmission determination unit 100. The selection permission signal S _Pi determined based on them is output to the corresponding transmission circuit TX _i .

Transmission determination unit 100 determines the priority of each data transmission by using the inputted respectively from the band calculation unit _{BWCAL 1 ~BWCAL 4 (S MAX1,} S MIN1) ~ (S MAX4, S MIN4). Hereinafter, the transmission determination operation will be described.

  FIG. 7 is a flowchart showing the transmission determination operation of the band limiting circuit in this embodiment. In the transmission determination operation, first, a state in which it is necessary to actively perform data transmission (the transmission possible period 204 in FIG. 5) is determined first, and there is no longer a state in which it is necessary to actively perform data transmission. Thus, the basic operation of determining a state in which it is not necessary to actively transmit (transmission enabled period 203 in FIG. 5) is repeated.

When activated, the transmission determination unit 100 first determines whether or not the maximum bandwidth notification signal and the minimum bandwidth notification signal (S _MAX1 , S _MIN1 ) from the bandwidth calculation unit BWCAL ₁ are (0, 0) (Step 0). S301). If (S _MAX1 , S _MIN1 ) = (0, 0), since it is below the minimum bandwidth BW _MIN1 as described above, it is necessary to actively transmit data, and the selection permission signal S _P1 is activated. (Step S309). After making the selection permission signal S _P1 active, the process returns to step S301 again. At that time, if it is in the transmission period 201 or the transmission impossible period 202, (S _MAX1 , S _MIN1 ) = (1, 1) (see FIGS. 5A and 5B).

If (S _MAX1 , S _MIN1 ) ≠ (0, 0) (NO in step S301), the maximum bandwidth notification signal and the minimum bandwidth notification signal (S _MAX2 , S _MIN2 ) from the bandwidth calculation unit BWCAL ₂ are (0, 0) (step S302). If (S _MAX2 , S _MIN2 ) = (0, 0), since it is below the minimum bandwidth BW _MIN2 as described above, it is necessary to actively transmit data, and the selection permission signal S _P2 is activated. (Step S310). After making the selection permission signal S _P2 active, the process returns to step S301 again. If that time transmission period 201 or transmission impossible period _{202 (S MAX1, S MIN1)} = (1,1) a and, if similarly the transmission period 201 or transmission impossible period 202 even step S302 (S _MAX2, S _MIN2 ) = (1, 1) (see FIGS. 5A and 5B). Further, in long transmission period is 203 in step _{S301 (S MAX1, S MIN1)} = (0,1), if transmission period 203. In the step _{S302 (S MAX2, S MIN2)} = (0,1) is there.

If (S _MAX2 , S _MIN2 ) ≠ (0, 0) (NO in step S302), the maximum bandwidth notification signal and the minimum bandwidth notification signal (S _MAX3 , S _MIN3 ) from the bandwidth calculation unit BWCAL ₃ are (0, 0) is determined (step S303). If (S _MAX3 , S _MIN3 ) = (0, 0), since it is below the minimum bandwidth BW _MIN3 as described above, it is necessary to actively transmit data, and the selection permission signal S _P3 is activated. (Step S311). After making the selection permission signal S _P3 active, the process returns to step S301 again, and the determinations of steps S301 to S303 are performed as described above.

(S _MAX3, S _MIN3) (NO in step S303) ≠ if (0,0), maximum band notification signal and minimum bandwidth notification signal from the band calculation unit _{BWCAL 4 (S MAX4, S MIN4} ) is (0, 0) is determined (step S304). (S _MAX4, S _MIN4) if = (0, 0), since below the minimum bandwidth BW _MIN4 as described above must be done actively transmitting data, to activate the selection permission signal S _P4 (Step S312). After making the selection permission signal S _P4 active, the process returns to step S301 again, and the determinations of steps S301 to S304 are performed as described above.

If (S _MAX4, S _MIN4) a ≠ (0,0) (NO in step S304), at the moment, it can be seen that does not require an active transmission in a band of all kinds.

Subsequently, the transmission determination unit 100 determines whether or not the maximum bandwidth notification signal and the minimum bandwidth notification signal (S _MAX1 , S _MIN1 ) from the bandwidth calculation unit BWCAL ₁ are (0, 1) (step S305). . If (S _MAX1 , S _MIN1 ) = (0, 1), the selection permission signal S _P1 is activated (step S309). After making the selection permission signal S _P1 active, the process returns to step S301 again, and the determinations of steps S301 to S305 are performed as described above.

If (S _MAX1 , S _MIN1 ) ≠ (0, 1) (NO in step S305), the maximum bandwidth notification signal and the minimum bandwidth notification signal (S _MAX2 , S _MIN2 ) from the bandwidth calculation unit BWCAL ₂ are (0, 1) is determined (step S306). If (S _MAX2 , S _MIN2 ) = (0, 1), the selection permission signal S _P2 is activated (step S310). After activating the selection permission signal S _P2 , the process returns to step S301 again, and the determinations of steps S301 to S306 are performed as described above.

If (S _MAX2 , S _MIN2 ) ≠ (0, 1) (NO in step S306), the maximum bandwidth notification signal and the minimum bandwidth notification signal (S _MAX3 , S _MIN3 ) from the bandwidth calculation unit BWCAL ₃ are (0, 1) is determined (step S307). If (S _MAX3 , S _MIN3 ) = (0, 1), the selection permission signal S _P3 is activated (step S311). After making the selection permission signal S _P3 active, the process returns to step S301 again, and the determinations of steps S301 to S307 are performed as described above.

(S _MAX3, S _MIN3) (NO in step S307) ≠ if (0,1), maximum band notification signal and minimum bandwidth notification signal from the band calculation unit _{BWCAL 4 (S MAX4, S MIN4} ) is (0, 1) is determined (step S308). _{(S MAX4, S MIN4) =} (0,1) is to activate a selection permission signal S _P4 If (step S312). After activating the selection permission signal S _P4 , the process returns to step S301 again, and the determinations in steps S301 to S308 are performed as described above.

If (S _MAX4, S _MIN4) a ≠ (0,1) (NO in step S308), control returns to step S301, or step S301~S312 are repeated.

Thus transmission circuit is permitted transmitted by output selection permission signal S _P from the transmission determination unit 100 can perform transmission can transmit selected in accordance with the band set.

  In the present embodiment, the transmission band limitation of four flows is exemplified, but also in the case of a transmission band of a plurality of flows, the number of steps S301 to S304, S305 to S308, and S309 to S312 in FIG. It can be controlled in the same way.

  As described above, the maximum bandwidth notification signal and the minimum bandwidth notification signal include information for prohibiting transmission at the maximum bandwidth or higher, and the transmission determination unit 100 only needs to monitor the maximum bandwidth notification signal and the minimum bandwidth notification signal. It is possible to easily determine whether or not transmission is possible. Therefore, transmission rate control can be performed with relatively simple information processing.

  The bandwidth limiting device and method according to the present invention can be applied to a network communication device such as a router.

It is a block diagram which shows an example of the network system which performs a service request and provision through the router provided with the band limiting apparatus by one Embodiment of this invention. It is a block diagram which shows the schematic function structure of the router which has the band-limiting apparatus by this embodiment. It is a functional block diagram which shows an example of the band-limiting circuit by this embodiment. It is a block diagram which shows an example of the zone | band calculating part BWCAL in this embodiment. It is a timing chart for demonstrating the transmission determination operation | movement in this embodiment. It is a block diagram which shows the structure of the band-limiting circuit by one Example of this invention. It is a flowchart which shows the transmission determination operation | movement of the band-limiting circuit in a present Example.

Explanation of symbols

10 Router 11 CPU
12 memory 13 buffer 14 band limiting circuit 15 buffer 100 transmission judgment unit 101 maximum band register 102 minimum band register 103 transmission byte counter 104 maximum band GAP generation unit 105 minimum band GAP generation unit 106 comparator 107 comparator TX transmission circuit BWCAL band calculation Part

Claims (19)

In an apparatus for limiting the bandwidth of each flow based on a plurality of set bandwidths set for each of a plurality of flows,
A packet interval generating means for generating a packet interval that satisfies each condition of the plurality of setting bands;
Transmission determination means for determining the transmission priority of the next packet in each flow based on the comparison between the elapsed time from the packet transmission completion time and the packet interval;
A bandwidth limiting device characterized by comprising: In an apparatus for limiting the bandwidth of each flow based on a plurality of set bandwidths set for each of a plurality of flows,
A measuring means for measuring an elapsed time from completion of packet transmission;
Packet interval generation means for generating a packet interval until the start of transmission of the next packet based on each of the plurality of setting bands and the packet length of the transmitted packet;
Comparing means for comparing the elapsed time and the packet interval;
Transmission determination means for determining the transmission priority of the next packet in the flow based on the comparison result for each of the plurality of set bands;
A bandwidth limiting device characterized by comprising:   The band limiting device according to claim 2, wherein the transmission determination unit permits or prohibits packet transmission of each flow according to the transmission priority.   The packet interval generation means generates a maximum bandwidth packet interval generation means based on the maximum bandwidth and the packet length, and generates a minimum bandwidth packet interval based on the minimum bandwidth and the packet length. The bandwidth limiting device according to claim 2 or 3, further comprising bandwidth packet interval generation means. The comparison means generates a first determination signal indicating whether or not the elapsed time has reached the maximum bandwidth packet interval, and whether or not the elapsed time has reached the minimum bandwidth packet interval. Second comparison means for generating a second determination signal indicating
The band limiting device according to claim 4, wherein the transmission determination unit determines the transmission priority based on the first and second determination signals.   The band limiting device according to claim 2, wherein at least the packet interval generation unit, the comparison unit, and the transmission determination unit are configured in logic and incorporated in a digital integrated circuit.   A router comprising the bandwidth limiting device according to claim 6. Interface means for connecting to the network;
Control means for controlling routing;
The router according to claim 7, wherein the bandwidth limiting device is integrated in one of the control unit and the interface unit. In a router having a function of limiting the bandwidth of each flow based on the maximum bandwidth and the minimum bandwidth set for each of a plurality of flows,
A measuring means for measuring an elapsed time from a transmission completion time of a packet transmitted immediately before in an arbitrary flow;
Packet interval generation means for generating a packet interval until the start of transmission of the next packet based on each of the maximum bandwidth and the minimum bandwidth set in the flow and the packet length of the transmitted packet;
Comparing means for comparing the elapsed time and the packet interval;
For each of the plurality of flows, transmission determination means for determining a transmission priority of a next packet based on the comparison result regarding each of the maximum bandwidth and the minimum bandwidth;
A plurality of transmission circuits provided for each of the plurality of flows and permitting or prohibiting packet transmission according to the transmission priority;
A network communication device comprising: In a method of limiting the bandwidth of each flow based on a plurality of setting bands set for each of a plurality of flows,
Generating a packet interval that satisfies each of the plurality of setting bands,
Determining the transmission priority of the next packet in each flow based on the comparison between the elapsed time from the packet transmission completion time and the packet interval;
A bandwidth limiting method characterized by the above. In a method of limiting the bandwidth of each flow based on a plurality of setting bands set for each of a plurality of flows,
Measure the elapsed time from when packet transmission is completed,
Based on each of the plurality of setting bands and the packet length of the transmitted packet, generate a packet interval until the start of transmission of the next packet,
Comparing the elapsed time and the packet interval;
Determining the transmission priority of the next packet in the flow based on the comparison result for each of the plurality of set bands;
A bandwidth limiting method characterized by the above.   The bandwidth limiting method according to claim 11, wherein packet transmission of each flow is permitted or prohibited according to the transmission priority.   The band limiting method according to claim 12, wherein the transmission priority includes a high transmission priority when the bandwidth is below the minimum bandwidth and a low transmission priority when the bandwidth is equal to or higher than the minimum bandwidth.   The bandwidth limiting method according to claim 13, wherein the packet transmission with the low transmission priority is permitted when there is no packet having the high transmission priority. In a program for causing a computer to execute a bandwidth limiting method for limiting the bandwidth of each flow based on a plurality of set bandwidths set for each of a plurality of flows,
Generating a packet interval that satisfies each of the plurality of setting bands;
Determining the transmission priority of the next packet in each flow based on the comparison between the elapsed time from the packet transmission completion time and the packet interval;
A bandwidth limiting program characterized by comprising: In a program for causing a computer to execute a bandwidth limiting method for limiting the bandwidth of each flow based on a plurality of set bandwidths set for each of a plurality of flows,
a) measuring an elapsed time from completion of packet transmission;
b) generating a packet interval until starting transmission of the next packet based on each of the plurality of setting bands and the packet length of the transmitted packet;
c) comparing the elapsed time with the packet interval;
d) determining a transmission priority of the next packet in the flow based on the comparison result for each of the plurality of setting bands;
A bandwidth limiting program characterized by comprising:   The bandwidth limiting program according to claim 16, wherein packet transmission of each flow is permitted or prohibited according to the transmission priority.   The bandwidth limiting program according to claim 17, wherein the transmission priority includes a high transmission priority when the bandwidth is below the minimum bandwidth and a low transmission priority when the bandwidth is equal to or higher than the minimum bandwidth. Said step d)
d-1) determining whether there is a packet having the high transmission priority;
d-2) a step of permitting transmission of the packet when the packet having the high transmission priority exists;
d-3) if there is no packet with the higher transmission priority, determining whether there is a packet with the lower transmission priority;
d-4) if there is a packet with the lower transmission priority, permitting transmission of the packet;
The bandwidth limiting program according to claim 18, wherein d-5) upon completion of step d-4), the process returns to step d-1).

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