JP2002232472A - Packet transfer control method, program to allow computer to execute the method, and recording medium for recording the program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packet transmission control method that can transfer a flow depending on the priority placed thereon by judging a respectively state of packets so as to properly control transfer of each flow in the transfer control of each flow with the priority placed thereon. SOLUTION: The packet transfer control method of this invention is characterized in that information with respect to packets of each flow is captured and stored and using the stored information with respect to the flows and the packets again sets a transfer rate set to a packet temporary storage buffer in a relay node when a priority is placed on the flow generated by an application and transfer control is applied to the packets on the basis of the priority in a network terminal at a user side utilizing the application to receive a network service or the relay node transferring the packets sent from the network terminal at the user side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a user who uses a service provider on a network such as an interface service provider (ISP) or an application service provider (ASP) for providing services such as continuous media communication and large-capacity data communication. The present invention relates to a terminal on the service provider side, a packet transfer control method applied to a network communication device, a program for causing a computer to execute the method, and a recording medium on which the program is recorded.

[0002]

2. Description of the Related Art Internet service providers (ISPs) and application service providers (ASPs) that provide connection services on a wide area network such as the Internet have been increasing with the increase in users who use these services. Along with this, various services have been provided, each of which has different requirements for maintaining connection charges and quality, and diversification of services has complicated requirements. Therefore, it is required to clarify the requirements of such an application even in the conventional best-effort service, and currently Diffserv (Differentiat)
ed Service) [1] [2].

FIG. 10 and FIG. 11 show examples of packets for which priorities are set on a network terminal or a relay node on the user side. FIG.
, The priority is set in the user terminal 1-1 and transferred to the relay nodes 1-2, 1-3,... FIG.
Then, the user terminal 2-1 does not set the priority,
The priority is set in the relay node 2-2 and is transferred to the relay node 2-3.

FIG. 12 shows setting of priorities in Diffserv. The relay node 3-4, which forwards packets transmitted from the user-side network terminals 3-1, 3-2, 3-3,
The priority is set to the packet using rv. Dif
In fserv, the TOS field (Field) in IPv4 [3] is changed to DSCP (Differentia)
The service is used as a ted service code point and a priority is set. The packet for which the priority is set in the IP packet 3-5 is controlled based on this value in the network where the priority control is performed.

[0005] In a relay node that receives a packet with these priorities set, transfer control based on the priority is performed in an output buffer (queue) that holds the packets in order to avoid congestion. FIG. 13 shows CBQ (Class-Based Queuing), which is one of the techniques for performing packet transfer control and discarding according to priority.
[4] is shown. Relay node 4-1
Are queues 4-3, 4-4, 4-5, 4-4 provided for each priority in a classifier 4-2 for classifying received packets.
Are stored once in order. Each queue 4-3, 4-
Are statically determined, and at the time of packet transfer, packets are transferred so as to satisfy the minimum necessary transmission capacity (queue length) set for each flow. . At this time, when the reception rate of the packet exceeds the set transfer rate, the excess is discarded without being transferred.

[0006]

When requirements such as priorities are set in order to maintain communication quality and various transfer controls are performed on the relay node side, the class in which each priority is set by these controls is set. Although the relative transfer quality between the applications is guaranteed, it is not necessarily guaranteed that the minimum transfer quality required for the application is satisfied. Also,
In a network environment in which a plurality of applications are running, when the amount of data to be transferred exceeds the line capacity, congestion occurs, the transfer quality of the application deteriorates, and user dissatisfaction increases.

In order to prevent the packet from being discarded for such a reason, the transfer rate of the packet is controlled and the packet discard rate is controlled based on the priority. However, a buffer (queue) for holding the packet in the relay node for transferring the packet is used. Since the setting of the capacity is statically performed, it is difficult to appropriately control the packet discard rate of the entire traffic because the high-priority packet can be protected but the low-priority packet cannot be protected well. in this way,
In order to perform more appropriate processing with respect to the ever-increasing network traffic, it is necessary to perform processing that dynamically responds to traffic fluctuations.

[0008] The present invention has been made in view of the above circumstances, and the transfer control of each flow to which a priority is given is given to a flow by judging the packet reception state and appropriately controlling the transfer control. An object of the present invention is to provide a packet transfer control method capable of performing transfer according to priority, a program for causing a computer to execute the method, and a recording medium on which the program is recorded.

[0009]

In order to achieve the above object, a packet transfer control method according to the present invention is provided. A service provider such as an Internet service provider (ISP) or an application service provider (ASP) provides various network services. A network terminal on the user side that uses an application for receiving the network service, or a packet transmitted from the network terminal on the user side, on a network provided and having various traffics having different characteristics depending on the network service. In a relay node that performs packet transfer, when a priority is set to a flow generated by an application and packet transfer control (priority control) is performed based on the value of the priority, a packet associated with each flow is Acquires broadcast, stored, using information on the flow and packet stored temporary storage buffer of a packet in the relay node (queue)
The resetting of the transfer rate set in is performed.

Further, in the packet transfer control method according to the present invention, the number of discarded packets for each flow is stored as information, a packet discard rate for each flow is calculated from the stored number of discarded packets, and the priority of the flow is determined. The transfer rate set in the buffer for temporarily storing packets (queue) in the relay node that transfers the packet is reset from the calculated value of the packet loss rate.

The present invention also provides the packet transfer control method, wherein the reception capacity for each flow is stored as information.
Based on the packet transmission capacity (queue length) set for each priority and the flow reception capacity, the time at which packet discarding occurs (packet discard prediction time) is calculated,
The transfer rate set in the temporary storage buffer (queue) of the packet in the relay node that transfers the packet is reset according to the time.

[0012] The present invention also provides the packet transfer control method, wherein when a constraint condition defining the quality of the communication application used by the user exists, the relay node for transferring the packet within the constraint condition. The present invention is characterized in that the transfer rate set in the buffer for temporarily storing packets (queue) is reset.

Further, according to the present invention, in the packet transfer control method, when there is a policy condition in the network where the policy control is performed, the packet is temporarily stored in the relay node for transferring the packet within the range of the policy condition. It is characterized in that the transfer rate set in the buffer (queue) is reset.

Further, the present invention is characterized in that in the packet transfer control method, a process of transferring the reset transfer rate value to a user-side network terminal which is a packet transmission source is performed.

Further, the present invention is characterized in that in the packet transfer control method, a process of transferring the reset transfer rate value to another related relay node is performed.

Further, according to the present invention, in the packet transfer control method, a user-side network terminal receiving the transfer rate information reset by a predetermined relay node adjusts the packet rate to the reset transfer rate value. Is transmitted.

Further, according to the present invention, in the above packet transfer control method, a network relay node receiving the transfer rate information reset by a predetermined relay node adjusts the value of the reset transfer rate to transmit a packet. Is performed.

Further, according to the present invention, in the packet transfer control method, a buffer for temporarily storing each packet based on a transmission capacity (queue length) of a packet set for each priority and a reception capacity of a flow. Queue capacity), and the transfer rate is reset according to the calculated ratio.

Further, according to the present invention, in the above-mentioned packet transfer control method, the available capacity of each queue after a predetermined time is determined from the packet transmission capacity (queue length) set for each priority and the flow reception capacity. It is characterized in that the capacity is predicted and the transfer rate is reset according to the predicted ratio.

Further, a program according to the present invention causes a computer to execute the packet transfer control method.

[0021] The recording medium of the present invention stores a program for causing a computer to execute the packet transfer control method.

In a network relay device such as a router, control of a packet transfer rate and control of a packet discard rate based on priority are performed as means for preventing packet discard. The process of dynamically changing the capacity of the (queue) is different from the conventional method. In particular, no processing is performed to predict and change the packet reception rate.

[0023]

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

[First Embodiment] FIG. 1 is a structural explanatory view showing a first embodiment of the present invention.

In FIG. 1, a relay node 5-1 classifies a received packet into a classifier (C
lassifier) 5-2.
Queues 5-3, 5-4, 5 provided for each of 3, 4,.
-5, 5-6,... Each queue 5-
The capacities of 3,5-4,5-5,5-6 are statically determined, and here, 500 Kbps, 1.5 Mbps,
It is assumed that they are 2 Mbps and 6 Mbps.

At this time, at time t (second), a data buffer (data buffer) 5-7 for holding information is provided.
For example, discard information of a packet having a value of priority 4 is held as information of a packet stored in the queue 5-6. At this time, the calculator (calcul)
ator) 5-8 is a data buffer (data buffer)
fer) The packet discard rate is calculated from the information of 5-7. Here, a 7 Mbps packet arrives at the queue 5-6, and the packet discard rate of the queue 5-6 is 0.142%.
That is, it is assumed that a 1 Mbps packet is discarded.

Next, a calculator (calculato)
r) 5-8 recalculates the queue length (transfer rate) of each queue 5-3, 5-4, 5-5, 5-6 based on the value of the packet discard rate. In FIG. 1, the queue 5-
Transfer rates of 3,5-4,5-5,5-6 are each 300
Kbps, 1.1 Mbps, 1.6 Mbps, 7 Mbps
is reset to s. As a result, the transfer rate of the queue 5-6 where the packet has been discarded increases, and the packet discard can be suppressed.

[Embodiment 2] FIG. 2 is a structural explanatory view showing Embodiment 2 of the present invention.

In FIG. 2, the relay node 6-1 is configured as shown in FIG.
Similarly, in a classifier 6-2 for classifying received packets, queues 6-3, 6-4, 6-5, and 6 provided for each priority.
-6, ... are stored once in order. Each queue 6-3,6-
The capacities of 4, 6-5 and 6-6 are statically determined. Here, 500Kbps, 1.5Mbps, 2Mbps
s, 6 Mbps.

At this time, the data buffer (data buffer) 6-7 for holding the information has a queue 6-
The reception capacities of the flows stored in 3, 6-4, 6-5, and 6-6 are recorded for each time period. At time t (second), for example, it is assumed that the reception capacity of the flow in the queue 6-6 having the value of the priority 4 is 7 Mbps. At this time, a calculator 6-8
Is a data buffer 6-7
From this information, the time at which packet discarding starts is calculated. Here, it is assumed that the reception capacity is maintained, and the queue 6
The packet discard prediction time is calculated by a calculation formula of −6 transfer rate / (reception capacity−transmission capacity). By the calculation, packet discarding starts six seconds after the relay node starts receiving the packet sequence (flow).

At this time, the data buffer (data bu)
(fer) 6-7 recalculates each queue length (transfer rate) at time t + 5 (seconds). In FIG. 2, the transfer rates of the queues 6-3, 6-4, 6-5, and 6-6 are 300 Kbps, 1.1 Mbps, 1.6 Mbps,
It is reset to 7 Mbps. As a result, the transfer rate of the queue 6-6 in which packet discarding has occurred increases, and packet discarding can be suppressed.

[Embodiment 3] FIG. 3 is a structural explanatory view showing Embodiment 3 of the present invention.

In FIG. 3, the relay node 7-1 is configured as shown in FIG.
It has the same configuration as.

At this time, at a time t (second), a data buffer (data buffer) 7-7 holding information is provided.
Holds packet discard information and quality information required by the application sending the packet. At this time, the packet discard capacity of the queue 7-6 is 1M.
bps, and the calculator
or) 7-8 calculates a packet discard rate from the packet discard information. It is also assumed that the lower limit of the transfer rate of the packet in the queue 7-5 is 1.8 Mbps and the lower limit of the transfer rate of the packet in the queue 7-6 is 5.5 Mbps as the quality information requested by the application.

Next, a calculator (calculato)
r) 7-8 is for each queue 7-3, 7- based on the above values.
The queue lengths (transfer rates) of 4, 7-5 and 7-6 are recalculated. If the quality information required by the application is not considered, the result is the same as in the case shown in FIG.
Transfer rates of 3, 7-4, 7-5 and 7-6 are each 300
Kbps, 1.1 Mbps, 1.6 Mbps, 7 Mbps
is reset to s. However, this does not meet the requirements of the application. In consideration of this, the queue 7-
5 has a transfer rate of 1.8 Mbps. The transfer rates of the other queues 7-3, 7-4, and 7-6 are 200
Kbps, 1 Mbps, and 7 Mbps are reset. As a result, the transfer rate of the queue 7-6 in which the packet has been discarded increases, so that the packet discard can be suppressed and the quality required by the application can be secured.

Fourth Embodiment FIG. 4 is a structural explanatory view showing a fourth embodiment of the present invention.

In FIG. 4, the relay node 8-1 is
It has the same configuration as.

At this time, at time t (second), a data buffer (data buffer) 8-7 holding information is stored.
Holds the discard information of the packet and the policy information obtained by the information packet 8-9 transmitted from the policy server. At this time, it is assumed that the packet discarding capacity of the queue 8-6 is 1 Mbps, and the calculator (c
(Calculator) 8-8 calculates the packet discard rate from the packet discard information. Further, it is assumed that the lower limit of the transfer rate of the packet of the queue 8-5 is 1.8 Mbps and the lower limit of the transfer rate of the packet of the queue 8-6 is 5.5 Mbps as the policy information.

Next, a calculator (calculato)
r) 8-8 determines each queue 8-3, 8-
The queue lengths (transfer rates) of 4, 8-5 and 8-6 are recalculated. If the quality information required by the application is not taken into account, the result is the same as in the case shown in FIG.
Transfer rates of 3,8-4,8-5,8-6 are each 300
Kbps, 1.1 Mbps, 1.6 Mbps, 7 Mbps
is reset to s. However, this is against policy information. In consideration of the policy information, the transfer rate of the queue 8-5 becomes 1.8 Mbps. Other queues 8-3,
The transfer rates of 8-4 and 8-6 are 200 Kbps,
It is reset to 1 Mbps and 7 Mbps. As a result, the transfer rate of the queue 8-6 in which packet discarding has occurred increases, and packet discarding can be suppressed without violating policy information.

[Fifth Embodiment] FIG. 5 is a structural explanatory view showing a fifth embodiment of the present invention.

In FIG. 5, it is assumed that the relay node 9-2 has reset the transfer rate as shown in the first, second, third or fourth embodiment. At this time, the relay node 9-2
Transmits the reset transfer rate information packet 9-4 to the user side network terminal 9-1 in order to notify the changed transfer rate to the user side network terminal 9-1.
Return to.

[Sixth Embodiment] As in the fifth embodiment, the relay node 9-2 in FIG.
It is assumed that the transfer rate shown in 2, 3, or 4 has been reset. At this time, the relay node 9-2 transmits the reset transfer rate information packet 9-4 to the other relay node 9-3 related to the packet transfer so as to notify the changed transfer rate to the relay node 9-3. Return to -3.

[Embodiment 7] FIG. 6 is a structural explanatory view showing Embodiment 7 of the present invention.

In FIG. 6, it is assumed that the user-side network terminal 10-1 has received the transfer rate information packet reset by the relay node shown in the fifth embodiment. At this time, the network terminal 10-1 on the user side
The relay node transmits the packet 10-4 which has been subjected to the process of changing the transfer rate of the packet to the reset value according to the information of the transfer rate information packet reset by the relay node. As a result, it is possible to reduce the latency of the packet transfer process due to the packet being discarded at the relay node.

[Eighth Embodiment] As in the seventh embodiment, in FIG. 6, the relay node 10-3 receives the transfer rate information packet reset by the relay node shown in the fifth embodiment. I do. At this time, the relay node 10-3
Performs a process of changing the packet transfer rate according to this information. This can reduce the latency of the packet transfer process due to the packet being discarded at the relay node.

[Embodiment 9] FIG. 7 is a structural explanatory view showing Embodiment 9 of the present invention.

In FIG. 7, a relay node 11-1 has a classifier 11-2, and queues 11-3, 11- provided for each priority.
4, 11-5, and 11-6. The capacities of the queues 11-3, 11-4, 11-5, and 11-6 are determined by conditions such as priority. Here, each 5
00Kbps, 1.5Mbps, 2Mbps, 6Mbps
s.

A data buffer (data) for holding information
buffer 11-11, each queue 11-3, 1
The reception capacities of the flows stored in 1-4, 11-5, and 11-6 are recorded for each time period. At time t (second), each queue 11- having a value of priority 1, 2, 3, 4
The receiving capacities of 3, 11-4, 11-5, and 11-6 are 0.15 Mbps, 0.3 Mbps, and 0.69 Mbps, respectively.
s, 7.0 Mbps. At this time, the calculator 11-8 adds a capacity of 1 Mbps to the priority 11 queue 11-6, and
A process for resetting to Mbps is performed. Queue 4 of priority 4
The distribution from queues other than 1-6 is calculated from the ratio of the reception capacity of each priority queue. Here 0.1
Since 5: 0.3: 0.69 = 5: 10: 23, the queues 11-3, 11-4, 11-5 of the priorities 1, 2, and 3 are set.
From 132Kbps, 263Kbps and 605Kb respectively
The capacity of each ps is allocated to the queue 11-6 of the priority 4.

Accordingly, each of the queues 11-3, 1 after resetting is set.
The capacities of 1-4, 11-5 and 11-6 are respectively 368
Kbps, 1.23 Mbps, 1.395 Mbps, 7
Mbps. As a result, the transfer rate of the queue 11-6 in which the packet has been discarded increases, and the packet discard of the queue 11-6 of priority 4 can be suppressed.

[Embodiment 10] In the configuration similar to that of FIG. 7, each of the queues 11-3 having the values of the priorities 1, 2, and 3
FIG. 8 shows the reception capacities of 11-4 and 11-5. Thereby, at time t-2 (second), 0.25 Mbps,
0.6 Mbps, 0.91 Mbps, and 0.21 Mbps, 0.46 Mbps and 0.81 Mbps at t-1 (sec), respectively
0.15 Mbps and 0.3 Mbps in ps and t (sec), respectively
s, 0.69 Mbps. Similarly, it is assumed that the reception capacity of the queue 11-6 having the priority 4 is 7 Mbps at t (second).

At this time, a calculator (calcul)
attor) 11-8 is assigned to the priority 11 queue 11-6.
A process of adding a capacity of Mbps and resetting it to 7 Mbps is performed. Queues 11 other than the priority 4 queue 11-6
-3, 11-4, and 11-5 are assigned to the queues 11-3, 11-4, and 11-5 of the respective priorities at the time t.
A predicted value of the reception capacity at +1 is calculated and obtained from the ratio. Here, the prediction is performed by the least square method. Assuming that the capacity c (T) at time T of each of the queues 11-3, 11-4, and 11-5 follows c (T) = aT + b, each of the queues 11-3, 11-4, and 11-5 has Σ ( c (T)-
(AT + b)) It is obtained by finding a and b that minimize ² .

When this is calculated, priority 1 and priority 1 are obtained from FIG.
Each of the queues 11-3, 11-4, and 11-5 at time t + 1 is 0.103 Mbps and 0.153 Mbps at time t + 1.
ps, 0.583 Mbps. Therefore, each of the queues 11-3, 11-4, and 11-5 of the priorities 1, 2, and 3
From 0.118Mbps, 0.176Mbps,
Queue 11 of priority 4 with a capacity of 0.670 Mbps each
Assign to -6.

Accordingly, each of the queues 11-3, 1 after resetting is set.
The capacities of 1-4, 11-5 and 11-6 are 0.3
82 Mbps, 1.324 Mbps, 1.33 Mbps
s, 7.0 Mbps. As a result, the transfer rate of the queue 11-6 in which the packet has been discarded increases,
Packet discarding of the priority 11 queue 11-6 can be suppressed.

Incidentally, the packet transfer control method in each of the above embodiments is specifically executed by a computer such as a personal computer based on a predetermined program in advance. The program can be recorded on a predetermined computer-readable recording medium.

[0055]

As described above, according to the present invention, in an environment where a large number of applications and service provision destinations exist, a relay node or a network terminal on the user side is used based on information of a flow transmitted from each application. By controlling the transfer rate in
It is possible to suppress the bias of quality deterioration of each flow.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory diagram showing a packet discard rate calculation and a transfer rate reset according to a first embodiment of the present invention.

FIG. 2 is a configuration explanatory diagram showing a packet discard prediction time calculation and a transfer rate reset according to a second embodiment of the present invention;

FIG. 3 is a configuration explanatory diagram showing transfer rate resetting in consideration of application quality information according to Embodiment 3 of the present invention.

FIG. 4 is a configuration explanatory diagram showing transfer rate resetting in consideration of policy information according to Embodiment 4 of the present invention.

FIG. 5 is a configuration explanatory diagram showing transmission of reset transfer rate information according to Embodiments 5 and 6 of the present invention.

FIG. 6 is a configuration explanatory diagram showing transmission rate resetting on the terminal side according to Embodiments 7 and 8 of the present invention.

FIG. 7 is a configuration explanatory view showing resetting of a queue length in consideration of a queue free space according to Embodiments 9 and 10 of the present invention.

FIG. 8 is an explanatory diagram showing a packet reception capacity of each queue used in Embodiment 10 of the present invention.

FIG. 9 is an explanatory diagram showing calculation of a queue length reset value by the least squares method used in Embodiment 10 of the present invention.

FIG. 10 is a configuration explanatory view showing priority setting on a user terminal side according to a conventional packet transfer control method.

FIG. 11 is a configuration explanatory diagram showing priority setting on a relay node side according to a conventional packet transfer control method.

FIG. 12 is a diagram illustrating Diff related to a conventional packet transfer control method.
FIG. 9 is a configuration explanatory diagram showing the setting of packet priority in serv.

FIG. 13 shows a CBQ according to a conventional packet transfer control method.
FIG. 3 is a configuration explanatory diagram showing (Class Based Queuing) and packet discarding.

[Explanation of symbols]

 5-1 Relay node 5-2 Classifier 5-3 Queue 5-4 Queue 5-5 Queue 5-6 Queue 5-7 Data buffer 5-8 Calculator

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ryutaro Hosoi 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term (reference) in Nippon Telegraph and Telephone Corporation 5K030 HA08 HB17 HC01 JA11 JL07 KA03 LA03 LB15 LC01 LC08 LC13 LE05 MA13 MB15 5K034 EE11 FF11 HH04 HH23 HH37 HH42 HH63 MM08 MM11 NN04

Claims (13)

[Claims] 1. A service provider such as an Internet service provider or an application service provider provides various network services,
On a network in which various traffics having different characteristics depending on the network service exist, a user-side network terminal that uses an application for receiving the network service, or a relay that transfers a packet transmitted from the user-side network terminal. In the node, when a priority is set for a flow generated by an application and packet transfer control is performed based on the priority value, information on a packet for each flow is obtained and stored, and the stored flow is stored. And a transfer rate set in a temporary buffer for storing packets in the relay node using the information on the packet and the packet transfer control method. 2. The packet transfer control method according to claim 1, wherein the number of discarded packets for each flow is stored as information, and a packet discard rate for each flow is calculated from the stored number of discarded packets. From the calculated packet loss rate value,
A packet transfer control method, comprising resetting a transfer rate set in a temporary buffer for storing packets in a relay node that transfers the packets. 3. The packet transfer control method according to claim 1, wherein the reception capacity of each flow is stored as information, and the packet transmission capacity is set based on the transmission capacity of the packet set for each priority and the reception capacity of the flow. A packet transfer control method comprising: calculating a time at which discarding occurs; and resetting a transfer rate set in a temporary buffer for storing packets in a relay node that transfers the packet in accordance with the time. 4. The packet transfer control method according to claim 2, wherein when a constraint condition defining the quality of the communication application used by the user exists, the packet is transferred within the range of the constraint condition. A packet transfer control method, comprising resetting a transfer rate set in a buffer for temporarily storing packets in a relay node. 5. The packet transfer control method according to claim 2, wherein when there is a policy condition in a network in which the policy control is performed, a packet is temporarily stored in a relay node that transfers the packet within a range of the policy condition. A transfer rate set in a temporary storage buffer. 6. The packet transfer control method according to claim 2, wherein the process of transferring the reset transfer rate value to a user-side network terminal that is a packet transmission source is performed. Characteristic packet transfer control method. 7. The packet transfer control method according to claim 2, wherein a process of transferring the reset transfer rate value to another related relay node is performed. Transfer control method. 8. The packet transfer control method according to claim 6, wherein the user-side network terminal receiving the transfer rate information reset by the predetermined relay node adjusts the value of the reset transfer rate. A packet transfer control method characterized by transmitting a packet. 9. The packet transfer control method according to claim 7, wherein the network relay node receiving the transfer rate information reset by a predetermined relay node adjusts the value of the packet by resetting the value of the reset transfer rate. A packet transfer control method characterized by performing transmission. 10. The packet transfer control method according to claim 2,3,4 or 5, wherein a temporary capacity of each packet is determined based on a transmission capacity of the packet set for each priority and a reception capacity of the flow. A packet transfer control method comprising calculating a free space in a storage buffer, and resetting a transfer rate according to the calculated ratio. 11. The packet transfer control method according to claim 2, wherein the transmission capacity of the packet set for each priority and the reception capacity of the flow are used to determine each packet after a predetermined time. A packet transfer control method comprising: estimating a free space in a queue; and resetting a transfer rate according to the estimated ratio. 12. A program for causing a computer to execute the packet transfer control method according to claim 1. 13. A recording medium on which a program for causing a computer to execute the packet transfer control method according to claim 1 is recorded.