JP6326727B2 - Packet switching apparatus, packet switching method, and bandwidth control program - Google Patents

Description

  The present invention relates to a packet switching device, a packet switching method, and a bandwidth control program, and can be applied to, for example, a node device used in a communication network using a packet switching method.

  A network such as a LAN (Local Area Network) or the Internet is a communication network using a communication method called a packet switching method. In these networks, a packet switching device is used as a node device. In the packet switching method, information is divided into units called packets and transmitted. For this reason, it becomes possible to wait in units of packets, and a line can be shared by a plurality of users and efficiently transferred in parallel. In addition, since packets are temporarily stored in the storage unit of the packet switching device and transferred, an intelligent network that can cope with various communication situations can be constructed.

  On the other hand, in recent years, with the diversification of services and applications provided using a network, there is an increasing need to guarantee various communication qualities. The index representing the communication quality includes a data discard rate, a propagation delay time, a propagation delay fluctuation, and the like. For example, in voice communication and video communication that require real-time performance, guarantee of a low discard rate, low delay, and low delay fluctuation is required. On the other hand, a low discard rate guarantee is required for data communications that do not require real-time performance.

  Due to differences in services and applications, in order to guarantee the respective communication quality levels, priority is determined for each service and application, and the demand for packet switching devices having a priority control function for outputting packets according to the priority has increased. ing.

  In addition, a bandwidth control function is required for a communication carrier to guarantee a minimum bandwidth corresponding to a communication service to a user and to limit a usable bandwidth by a maximum restricted bandwidth.

  Therefore, a packet switching apparatus having such a priority control function and a bandwidth control function has been proposed (for example, see Patent Document 1). The packet switching device disclosed in Patent Document 1 includes an input interface unit, an output interface unit, and a packet switching unit. The input interface unit transfers the received user packet to the packet switching unit according to the priority. The packet switching unit sends the user packet received from the input interface unit to the corresponding output interface unit based on the destination address. The output interface unit has a packet queue corresponding to the priority of user packets and a queue group in which these queues are grouped. Each queue group is allocated the minimum guaranteed bandwidth specified in the communication service contract. By controlling the read bandwidth from each queue group, the minimum bandwidth is guaranteed and the surplus bandwidth is allocated between users. Realization of fairness. Further, when reading from the queue group, the communication quality level is guaranteed by performing read control according to the priority in the queue group.

  However, in the packet switching device disclosed in Patent Document 1, when a packet is sent from a plurality of input interface units to one output interface unit, the total number of packets from each input interface unit is the packet switching unit and the output If the transmission bandwidth with the interface unit is exceeded, packet discarding occurs before the packet arrives at the output interface unit. For this reason, the bandwidth control becomes incomplete, and it is difficult to realize the minimum bandwidth guarantee and the fairness among users.

  As an invention that solves this problem, there is a packet switching device disclosed in Patent Document 2. The packet switching device disclosed in Patent Document 2 calculates a transmission permission amount according to a transmission request amount received from each input interface unit in an output interface unit, and the input interface unit performs transmission according to the transmission permission amount. I do. Since the bandwidth is managed by the output interface unit, packets are not discarded until the output interface unit receives them, such as between the input interface unit and the output interface unit, guaranteeing the minimum bandwidth of each contract, and between users Maintaining fairness is achieved.

JP-A-11-346246 JP2011-82912

  However, in the packet switching device disclosed in Patent Document 2, the transmission request amount for each packet queue is transmitted from the input interface unit to the output interface unit, and the output interface unit uses information such as each transmission request amount and the minimum guaranteed bandwidth. It is necessary to calculate the transmission permission amount of each packet queue and transmit the transmission permission amount for each packet queue from the output interface unit to the input interface unit. For this reason, when the number of packet queues and packet queue groups increases, it becomes difficult to realize a packet switching device due to factors such as an increase in transfer information from the input interface unit to the output interface unit and an increase in calculation processing load on the output interface unit. Become.

  The present invention has been made in view of the above circumstances. The amount of information transferred between the input interface unit and the output interface unit and the calculation processing load are kept low, the bandwidth guarantee for each flow group (or each flow), and the flow group ( Alternatively, the present invention intends to provide a packet switching apparatus, a packet switching method, and a bandwidth control program that can realize bandwidth fairness between flows.

According to a first aspect of the present invention, a plurality of input interface means for inputting a packet, a plurality of output interface means for outputting a packet, and a packet from each of the input interface means is output to the output interface means corresponding to a destination. In a packet switching device comprising a plurality of input buffers, a packet switch, and a packet switching means having a plurality of output buffers, (1) each of the input interface means (1-1) accumulates input packets. A plurality of packet storage units having different packet flows to be stored; (1-2) a flow identification unit that identifies a flow of an input packet and distributes the packet to one of the packet storage units; 3) A packet storage unit for reading the packets stored in the plurality of packet storage units. A packet read control unit that reads while switching, (1-4) an input band measurement unit that measures the input bandwidth of a packet to each of the packet storage units, and (1-5) an accumulation amount of each of the packet storage units And (1-6) a storage unit information transmission unit for transmitting information on the measured input bandwidth and the detected threshold excess, (2) Each output interface means (2-1) a transmission restriction band for obtaining a transmission restriction band for each of the plurality of input interface means when a congestion state of the output buffer corresponding to the output interface means is detected. And (2-2) a transmission control system for notifying the corresponding input interface means of the transmission restricted band of each of the input interface means obtained by the transmission restricted band calculating section. (3) the packet read control unit of each input interface means performs packet read control from the plurality of packet storage units based on the notified transmission limit band, (4) Further, the transmission limit band calculation unit may determine that the threshold excess detector does not exceed the threshold among the plurality of packet storage units included in the one input interface unit that is a target for obtaining the transmission limit band. For the detected packet accumulation unit, the first total value obtained by summing the input bands measured by the input band measurement unit, and the first total from the physical band between the packet switching unit and the output interface unit. The remaining bandwidth obtained by subtracting the value for the plurality of input interface means, and the information on excess threshold detected by the excess threshold detection unit. The transmission-limited band is obtained by obtaining a coefficient based on the report and adding the result obtained by multiplying the remaining band by the coefficient to the first total value.

According to a second aspect of the present invention, a plurality of input interface means for inputting a packet, a plurality of output interface means for outputting a packet, and a packet from each of the input interface means is output to the output interface means corresponding to a destination. A computer mounted in a packet switching apparatus having a plurality of input buffers, a packet switch, and a packet switching means having a plurality of output buffers; (1) storing input packets; A plurality of packet storage units, (2) a flow identification unit that identifies the flow of input packets and distributes the packets to any of the packet storage units, and (3) is stored in the plurality of packet storage units. The packet storage to read out the received packet based on the notified transmission limit band. A packet read control unit that reads out while switching the unit, (4) an input band measurement unit that measures the input bandwidth of the packet to each packet storage unit, and (5) the accumulated amount of each packet storage unit exceeds a threshold value Corresponding to one of the above output interface means, (6) a storage unit information transmitting unit for transmitting information on the measured input bandwidth and detected threshold exceeding, (7) A transmission bandwidth limit calculation unit for obtaining a transmission bandwidth limit for each of the plurality of input interface means when the congestion state of the output buffer is detected; and (8) determined by the transmission bandwidth limit calculation portion. Causing each of the input interface means to function as a transmission limit band notifying section for notifying the corresponding input interface means of each of the input interface means; (9) The limited bandwidth calculation unit is a packet storage unit that is detected by the threshold excess detection unit as not exceeding the threshold among the plurality of packet storage units included in the one input interface unit that is a target for obtaining the transmission limited bandwidth. The first total value obtained by summing up the input bands measured by the input band measuring unit, and the first total value from the physical band between the packet switching means and the output interface means, and the plurality of input interfaces. Calculating a residual band obtained by subtracting means and a coefficient based on information on excess threshold detected by the threshold excess detection unit, and adding the residual band multiplied by the coefficient to the first total value. Thus, the transmission limited band is obtained.

According to a third aspect of the present invention, a plurality of input interface means for inputting a packet, a plurality of output interface means for outputting a packet, and a packet from each of the input interface means is output to the output interface means corresponding to a destination. A packet switching method in a packet switching apparatus comprising a plurality of input buffers, a packet switch, and a packet switching means having a plurality of output buffers. The unit stores the input packet. (2) The flow identification unit of each input interface means identifies the flow of the input packet and distributes the packet to one of the packet storage units. 3) Packet read control of each input interface means Reads out the packets stored in the plurality of packet storage units while switching the packet storage unit to be read out. (4) The input bandwidth measuring unit of each input interface means transmits the packets to the respective packet storage units. (5) the threshold value excess detection unit of each input interface means detects whether or not the accumulated amount of each packet storage part exceeds the threshold value, and (6) each of the input interface means The storage unit information transmitting unit transmits the measured input band and the detected threshold excess information, and (7) the transmission limit band calculating unit of each output interface unit is the output buffer corresponding to the output interface unit. When a congestion state is detected, a transmission limited bandwidth is obtained for each of the plurality of input interface means, and (8) each output interface is A transmission limit band notifying unit of the communication means notifying the corresponding input interface means of the transmission limit band of each of the input interface means obtained by the transmission limit band calculating unit, and (9) each of the input interface means The packet read control unit performs read control of packets from the plurality of packet storage units based on the notified transmission limit band, and (10) further, the transmission limit band calculation of each output interface unit The unit is configured to input the input to the packet accumulating unit that is detected as not exceeding the threshold by the threshold excess detecting unit among the plurality of packet accumulating units included in the one input interface unit that is a target for obtaining the transmission limited band. A first total value obtained by summing the input bands measured by the band measuring unit, the packet switching means and the above The remaining bandwidth obtained by subtracting the first total value by the plurality of input interface means from the physical bandwidth with the output interface means, and a coefficient based on the threshold excess information detected by the threshold excess detection unit are obtained. At the same time, the transmission limited band is obtained by adding the remaining bandwidth multiplied by the coefficient to the first total value.

  According to the present invention, the amount of transfer information and the calculation processing load between the input interface unit and the output interface unit are kept low, the bandwidth is guaranteed for each flow group (or each flow), and the bandwidth between the flow groups (or flows) is fair. A packet switching apparatus, a packet switching method, and a bandwidth control program can be provided.

It is a block diagram which shows the functional structure of the packet switching apparatus of embodiment. It is a block diagram for explaining the operation of the packet switching device of the embodiment. It is a flowchart which shows the process of the transmission control zone | band calculation part in the packet switching apparatus of embodiment.

(A) Main Embodiment Hereinafter, an embodiment of a packet switching device, a packet switching method, and a bandwidth control program according to the present invention will be described with reference to the drawings.

(A-1) Configuration of Embodiment FIG. 1 is a block diagram illustrating a functional configuration of a packet switching apparatus 1 according to an embodiment. The packet switching apparatus 1 according to the embodiment may be configured entirely by hardware, partially configured by hardware, and the rest by a CPU and a program executed by the CPU. Even if the method is adopted, it can be functionally represented in FIG. For example, a flow identification unit 102, packet queues Q01 to Q0m,..., Qn1 to Qnm, an intra-group read control unit 103-0 to 103-n, an inter-group read control unit 104, a slave side bandwidth control unit 105, a master side The bandwidth control unit 203 and the like can be configured by a CPU and a program executed by the CPU.

  In FIG. 1, the packet switching device 1 includes at least a plurality of input / output interface units 2-0 to 2-X (X is an integer of 2 or more) and one packet switching unit 3. The plurality of input / output interface units 2-0 to 2-X and one packet switching unit 3 may be one unit, and the packet switching apparatus 1 may include a plurality of such units.

  Although FIG. 1 shows a detailed configuration of the input / output interface unit 2-0, the input / output interface units 2-0 to 2-X have the same internal configuration. In the following, the branch numbers “−0” to “−X” that distinguish the plurality of input / output interface units 2-0 to 2-X are omitted as appropriate, and the input / output interface units 2 (2-0 to 2-X) are omitted. The detailed structure of will be described. Although the branch number is omitted in FIG. 1, since the detailed configuration of the input / output interface unit 2-0 is shown, the branch number “−0” is correctly given.

  The input / output interface unit 2 transfers the packet input from the corresponding input port PIN to the packet switching unit 3, and the output interface unit 200 outputs the packet received from the packet switching unit 3 to the output port POUT. And have.

  When a packet is input from the input interface unit 100-a, the packet switching unit 3 analyzes the destination of the packet and gives the packet to the output interface unit 200-b corresponding to the destination. The packet switching apparatus 1 may be configured so that packets from the input interface unit 100-a belonging to the same input / output interface unit 2-a can be given to the output interface unit 200-a. The packet switching device 1 may be configured such that packets from the input interface unit 100-a belonging to the input / output interface unit 2-a cannot be given to the output interface unit 200-a.

  The input interface unit 100 includes a packet receiving unit 101, a flow identification unit 102, and a number of packet queues Q01 to Q0m grouped into a plurality (here, n + 1) of queue groups QG0 to QGn. In-group read control unit for each of Qnm and queue groups QG0 to QGn (referred to as QG0 read control unit to QGn read control unit in FIG. 1) 103-0 to 103-n, an inter-group read control unit (in FIG. 1) 104) (shown as a read control unit), a slave side band control unit 105, and a transmission control unit 106.

  The packet queues Q01 to Q0m belong to the queue group QG0, the packet queues Qn1 to Qnm belong to the queue group QGn, and the other packet queues are similarly grouped. FIG. 1 shows a case where there are m packet queues belonging to one queue group.

  The packet receiving unit 101 receives a received packet from the input port PIN and gives it to the flow identifying unit 102.

  The flow identifying unit 102 identifies the packet type based on the IP address, port number, priority identifier, and other information of the received packet from the packet receiving unit 101, and distributes the received packet to the packet queue corresponding to the identified packet type. Is.

  The packet queues Q01 to Q0m,..., Qn1 to Qnm are for queuing and storing incoming received packets. The packet queues Q01 to Q0m,..., Qn1 to Qnm are grouped into a plurality of queue groups QG0 to QGn as described above. For example, each queue group QG0 to QGn is assigned to each contract user such as contract user A, contract user B,. Each packet queue belonging to one queue group is provided for each packet priority determined by a priority identifier, for example.

  The intra-group read control units 103-0 to 103-n receive packets from the packet queues Q01 to Q0m,..., Qn1 to Qnm in the corresponding queue groups QG0 to QGn under the control of the inter-group read control unit 104, respectively. This is read and given to the inter-group read control unit 104. The in-group read control units 103-0 to 103-n control which packet queues Q01 to Q0m,..., Qn1 to Qnm in the corresponding queue groups QG0 to QGn are read. Any of the existing methods may be applied as a read control method by the read control units 103-0 to 103-n in each group. For example, a method of reading in order from the highest priority, a weighted round robin method, or the like is applied. it can.

  The inter-group read control unit 104 performs control to give one of the intra-group read control units 103-0 to 103-n the authority to read the received packet. The inter-group read control unit 104 receives a transmission limited band for the input interface unit 100 from the slave-side band control unit 105, and refers to this transmission limited band, and reads any of the intra-group read control units 103-0 to 103-103. -Controls at which timing a packet is read from the queue groups QG0 to QGn related to -n. Further, the inter-group read control unit 104 gives the packet given from any of the intra-group read control units 103-0 to 103-n to the transmission control unit 106.

  The slave side bandwidth control unit 105 controls the amount of packets per predetermined time (that is, bandwidth control) output from the inter-group read control unit 104 in cooperation with the master side bandwidth control unit 203 described later.

  The transmission control unit 106 includes a user packet output from the inter-group read control unit 104, a resource management packet (hereinafter referred to as an RMs packet) output from a slave side band control unit 105 described later, and a master side band described below. A resource management packet (hereinafter referred to as an RMm packet) output from the control unit 203 is multiplexed and given to the packet switching unit 3.

  The slave-side bandwidth control unit 105 includes a threshold excess detection unit 411, an input bandwidth measurement unit 412, an RMs packet transmission unit 413, and an RMm packet reception unit 414.

  The threshold excess detection unit 411 periodically detects an excessive amount of accumulated packets for each queue group QG0 to QGn by comparing with a threshold. As a threshold excess determination method, first, all the packet queues belonging to a queue group have a threshold value, and when any packet queue is in a threshold excess state, the queue group is in a threshold excess state. Second, there is a method of setting a threshold for the total accumulated packet amount of all packet queues belonging to the same queue group, and setting the queue group to the threshold excess state when the threshold is exceeded.

  The input bandwidth measuring unit 412 monitors the traffic from the flow identifying unit 102 to each of the packet queues Q01 to Q0m,..., Qn1 to Qnm, and inputs each packet queue Q01 to Q0m,. The input bandwidth for each of the queue groups QG0 to QGn is calculated from the data amount. Note that the flow identification unit 102 may also have the function of the input band measurement unit 412.

  The RMs packet transmission unit 413 receives bandwidth control information indicating whether or not the threshold is exceeded for each of the queue groups QG0 to QGn from the threshold excess detection unit 411 (for example, logical “1” in the excess state, logical “0” in the non-excess state). Information) and a value obtained by adding up the input bandwidths of all queue groups that are not in the threshold excess state among the input bandwidths of the queue groups QG0 to QGn measured by the input bandwidth measurement unit 412. Is. The RMs packet is given to the master side bandwidth control units 203-0 to 203-X of all the input / output interface units 2-0 to 2-X.

  The RMm packet receiving unit 414 receives the RMm packet transmitted from the master side bandwidth control unit 203-c of the output interface unit 200-c corresponding to the output buffer 302-c of the packet switching unit 3 to be described later. This notifies the inter-group read control unit 104-c of the transmission restricted bandwidth for each of the notified queue groups QG0 to QGn.

  The output interface unit 200 includes a reception control unit 201, a packet distribution unit 202, a master side bandwidth control unit 203, a reception buffer 204, and a packet transmission unit 205.

  The reception control unit 201 receives the packet output from the packet switching unit 3 and gives the received packet to the packet sorting unit 202.

  When receiving a packet from the reception control unit 201, the packet distribution unit 202 identifies whether the packet is a user packet, an RMm packet, or an RMs packet, distributes the user packet to the reception buffer 204, and controls the RMs packet on the master side bandwidth control. And distributes the RMm packet to the slave side bandwidth control unit 105 of the input interface unit 100.

  The master side bandwidth control unit 203 receives RMs packets output from all the input interface units 100-0 to 100-X, and if there is a congested output buffer 302-c in the packet switching unit 3 to be described later, these The transmission limit bandwidth allocated to each queue group in one or a plurality of input interface units for sending packets destined for the output buffer 302-c in a congested state is calculated from a value such as an over-threshold value notified by the RMs packet. The calculated transmission limited bandwidth is notified to the slave side bandwidth control unit of the corresponding input interface unit by the RMm packet.

  The reception buffer 204 temporarily accumulates user packets from the packet distribution unit 202 and outputs the user packets to the packet transmission unit 205.

  The packet transmission unit 205 outputs the user packet from the reception buffer 204 to the output port POUT.

  The master side bandwidth control unit 203 includes an RMs packet reception unit 421, a transmission limited bandwidth calculation unit 422, and an RMm packet transmission unit 423.

  The RMs packet receiving unit 421 receives the RMs packets output from all the input interface units 100-0 to 100-X, and the queue group exceeding the threshold value notified by the RMs packet and all the threshold values not exceeding the threshold value The transmission band limiting unit 422 is notified of the total input band value of the queue group.

  The transmission limited bandwidth calculation unit 422 is a threshold value excess state of each queue group notified from the RMs packet reception unit 421 and an input bandwidth total value of all queue groups not in the threshold excess state, and the output interface notified from the packet switching unit 3 Based on the congestion state of the output buffer corresponding to the unit 200 and the minimum guaranteed bandwidth for each queue group, the transmission limit for each queue group is set so that the bandwidth of each queue group becomes fair and satisfies the minimum guaranteed bandwidth. It determines the bandwidth. When the output buffer is not in a congested state, the transmission limit band calculating unit 422 determines to apply a predetermined fixed transmission limit band, and when the output buffer is in a congested state, Define the transmission bandwidth limit.

  Here, the minimum guaranteed bandwidth of each queue group may be preset in, for example, the transmission limited bandwidth calculation unit 422. For example, the RMs packet transmission unit (413) of the input interface unit (100) may receive the RMs packet. May be sent to the transmission limited bandwidth calculation unit 422 by placing the minimum guaranteed bandwidth of each queue group on the RMs packet.

  The RMm packet transmission unit 423 generates an RMm packet for notifying the transmission side bandwidth limit of each queue group obtained by the transmission limit bandwidth calculation unit 422 to the slave side bandwidth control unit of the corresponding input interface unit, and the generated RMm The packet is given to the transmission control unit 106 of the input interface unit 100.

  The packet switching unit 3 includes a plurality of input buffers 300-0 to 300-X, a packet switch 301, a plurality of output buffers 302-0 to 302-X, and a flow control unit 304.

  Each of the input buffers 300-0 to 300-X receives and buffers packets output from the corresponding input interface units 100-0 to 100-X.

  The packet switch 301 switches the packets received by the input buffers 300-0 to 300-X according to their destinations, and outputs the packets to the corresponding output buffers 302-0 to 302-X.

  Each of the output buffers 302-0 to 302-X appropriately buffers the packet from the packet switch 301 in order to transfer the packet to the corresponding output interface unit 200-0 to 200-X. Here, the congestion state of the output buffers 302-0 to 302-X can be read from the transmission limited bandwidth calculation unit 422 of the corresponding output interface units 200-0 to 200-X.

  The flow control unit 314 notifies the transmission control unit 106-x of the input interface unit 100-x corresponding to the input buffer 300-x so as not to discard the packet when a certain input buffer 300-x becomes congested. On the other hand, flow control is performed.

(A-2) Operation of Embodiment Next, the operation (packet switching method) in the packet switching device 1 of the embodiment will be described with reference to FIG.

  FIG. 2 is a drawing for explaining the operation. In FIG. 2, for simplification of explanation, the number of input / output interface units is three, and packets from the input interface unit 100-a belonging to the same input / output interface unit 2-a are output to the output interface unit. An example in which the packet switching apparatus 1 is configured so that it cannot be given to 200-a is shown. When the packet input from the input ports PIN-0 and PIN-1 of the input / output interface units 2-0 and 2-1 is output to the output port POUT-2 of the input / output interface unit 2-2 using FIG. An operation example will be described. In FIG. 2, only the blocks necessary for operation explanation are shown for the input / output interface units 2-0 to 2-2. In FIG. 2, for some blocks, branch numbers for clarifying differences such as the input / output interface units 2-0 to 2-2 are omitted, but in the following description, branch numbers are given as appropriate. To do.

  The input / output interface unit 2-0 receives contract user A and contract user B packets. The queue group QG0-0 includes the contract user A flow, and the queue group QG1-0 includes the contract user B flow. It is set to be identified and distributed. In addition, the packet distribution to the packet queues Q01, Q02, Q11, and Q12 in the queue groups QG0-0 and QG1-0 is performed according to the priority of the packet, and the high priority packet is assigned to the packet queues Q01 and Q11 with a low priority. Packets are set to be distributed to packet queues Q02 and Q12. The input / output interface unit 2-1 receives the packets of the contract user C and the contract user D, the flow of the contract user C is in the queue group QG0-1, and the contract user D is in the queue group QG1-1. The flow is set to be identified and distributed. Further, the distribution of the packets to the packet queues Q01, Q02, Q11, and Q12 in the queue groups QG0-1 and QG1-1 is performed according to the priority of the packet, and the high-priority packets are assigned low priority to the packet queues Q01 and Q11. Packets are set to be distributed to packet queues Q02 and Q12.

  The threshold value excess detection units 411-0 and 411-1 of each of the input / output interface units 2-0 and 2-1 periodically detect whether or not the packet accumulation amount exceeds the threshold value for each queue group.

  The input bandwidth measuring units 412-0 and 412-1 of the input / output interface units 2-0 and 2-1, respectively, integrate the input data amount for each queue group at a constant cycle, and each queue is calculated from the cycle and the integrated amount. The input bandwidth of the group is measured, and the input bandwidths of the queue groups that are determined to be in a state where the threshold is not exceeded by the threshold excess detection units 411-0 and 411-1 are totaled.

  The detected over-threshold state and the measured input bandwidth total value are notified to the RMs packet transmission units 413-0 and 413-1, and the RMs packet reception unit of the input / output interface unit 2-2 periodically by the RMs packet. 421-2.

  The RMs packet from the RMs packet transmission unit 413-0 is periodically transmitted to the RMs packet reception unit 421-1 of the input / output interface unit 2-1, and the RMs packet from the RMs packet transmission unit 413-1. Is periodically transmitted to the RMs packet receiving unit 421-0 of the input / output interface unit 2-0. FIG. 2 illustrates the operation at the time of congestion of the output buffer 302-2 corresponding to the input / output interface unit 2-2. For the purpose of explanation, further explanation of the transfer of these RMs packets is omitted.

  The RMs packet receiving unit 421-2 notifies the transmission limit bandwidth calculating unit 422-2 of the received threshold excess state and the input bandwidth total value of each queue group. The transmission bandwidth limit calculation unit 422-2 periodically reads the congestion state (information) of the output buffer 302-2 corresponding to the input / output interface unit 2-2 of the packet switching unit 3. Then, when the congestion state is read out, the transmission band limiting unit 422-2 reads out the threshold value excess state, the input band total value, and the minimum guaranteed band of each queue group, and sets the input interface unit (100-0 and 100-1). ) Is determined. The obtained transmission limited band is transmitted by the RMm packet transmission unit 423-2 to the RMm packet reception units 414-0 and 414-1 of the corresponding input interface units 100-0 and 100-1. The transmission limited band received by each RMm packet receiving unit 414-0, 414-1 is notified to the inter-group read control units 104-0, 104-1, and is read by the inter-group read control units 104-0, 104-1. The transmission band from each queue group QG0-0, QG1-0, QG1-0, QG1-1 is limited.

  The transmission band limit calculation unit 422-2 is configured to check the congestion state of the output buffer 302-2 of the packet switching unit 3, the threshold value excess state of the queue groups QG0-0, QG1-0, QG1-0, and QG1-1 and the total input bandwidth. From the value and the minimum guaranteed bandwidth set in the queue groups QG0-0, QG1-0, QG1-0, and QG1-1, the transmission limit in units of the input interface unit (100-0, 100-1) is as follows. Find the bandwidth.

  When the output buffer 302-2 of the packet switching unit 3 is in a non-congested state, all the transmission limited bands are physical bands between the input interface unit 100-0 or 100-1 and the packet switching unit 3 (that is, , No transmission limit).

  When the output buffer 302-2 of the packet switching unit 3 is in a congested state, the transmission limited bandwidth for each of the input interface units 100-0 and 100-1 is calculated by, for example, a calculation flowchart as shown in FIG.

  The calculation flowchart of FIG. 3 is not a case where the number of input / output interface units as shown in FIG. 2 is limited to three, but is expressed in a general-purpose form. FIG. 3 shows three calculation flowcharts (calculation routines), but the same processing may be performed by one calculation flowchart obtained by combining the three calculation flowcharts.

In FIG. 3, a variable Rmin [i] [u] represents a user u (0 to (N−1) belonging to an input port i (a value in the range of 0 to (M−1); which is PIN-i in FIG. 1). ) Is a minimum guaranteed bandwidth of the queue group QGu in FIG. Variable conj [i] [u], the buffer according to the user u belonging to the input port i (over-threshold status of a queue group) congestion state of (all packets queue Qu1~Qum belonging to the queue group QGu in FIG. 1) (congestion Is logic “1” and non-congestion is logic “0”). The variable inR [i] is a value obtained by adding up the input bandwidths of the users whose buffers are not congested among all the users belonging to the input port i. The constant BW is a physical band between the packet switching unit 3 and the output interface unit 200. The variable pRmin [i] is a value obtained by adding the minimum guaranteed bandwidths of the users whose buffers are congested among all users belonging to the input port i. The variable ΣpRmin is a total value of all the variables pRmin [i]. The variable eBW is an effective band. The constant M is the number of contract users per input / output interface unit (represented by n + 1 in FIG. 1). The constant N is the number of input / output interface units (represented by X + 1 in FIG. 1). Note that, as described above, the parameter i is a parameter that defines the input port. In other words, the parameter i is a parameter that defines the input interface unit.

  FIG. 3A is an operation flowchart for calculating the variable pRmin [i] and the variable ΣpRmin.

  When the process shown in FIG. 3A is started, the transmission limited band calculation unit 422 initializes the variable ΣpRmin and the parameter i defining the input port to 0 (ST100), and then sets the variable pRmin [i] and the user. Each specified parameter u is initialized to 0 (ST101).

  Then, transmission limit band calculation section 422 confirms the logical value of congestion state variable conj [i] [u] determined by parameters i and u at that time (ST102). If the logical value of the congestion state variable conj [i] [u] is “1” (represents the congestion state), the transmission limited bandwidth calculation unit 422 will determine the total guaranteed minimum bandwidth of the user whose buffer is in the congestion state. After pRmin [i] is increased by the minimum guaranteed bandwidth Rmin [i] [u] of the user determined by the current parameters i and u (ST103), the parameter u is incremented by 1 (ST104). On the other hand, if the logical value of the congestion state variable conj [i] [u] is “0” (represents a non-congested state), the transmission limited bandwidth calculation unit 422 immediately increments the parameter u by 1 ( ST104).

  After updating the parameter u, the transmission bandwidth limit calculation unit 422 compares the parameter u and the constant M, and sets the congestion state variables conj [i] [u] of all users related to the input port determined by the current parameter i. It is determined whether confirmation has been performed (ST105). If the confirmation of the congestion state variable conj [i] [u] of all users related to the input port determined by the current parameter i has not been completed, the transmission limited bandwidth calculation unit 422 returns to step ST102 described above.

  On the other hand, when the confirmation of the congestion state variable conj [i] [u] of all users related to the input port determined by the current parameter i is completed, the transmission bandwidth limit calculation unit 422 obtains the variable ΣpRmin for the current parameter i. After increasing the minimum guaranteed bandwidth total value pRmin [i] of the user in the congested state, the parameter i is incremented by 1 (ST106).

  After the parameter i is updated, the transmission bandwidth limit calculation unit 422 determines whether or not the processing of steps ST101 to ST106 described above has been performed for all input ports by comparing the parameter i with the constant N (ST107). If an unprocessed input port remains, the transmission band limiting unit 422 returns to step ST101 described above, and if the processing of steps ST101 to ST106 described above is executed for all input ports, FIG. A series of processing shown in a) is terminated.

  FIG. 3B is a calculation flowchart for calculating the variable eBW.

  When the processing shown in FIG. 3B is started, the transmission bandwidth limit calculation unit 422 initializes the effective bandwidth eBW to the physical bandwidth BW between the packet switching unit 3 and the output interface unit 200, and sets the parameter i to 0. Initialization is performed (ST200).

  Then, the transmission bandwidth limit calculation unit 422 decreases the effective bandwidth eBW by the total value inR [i] of the input bandwidths of the users whose buffers are not congested among all the users belonging to the input port determined by the current parameter i ( ST201). After that, the transmission limited band calculation unit 422 increments the parameter i by 1 (ST202), and determines whether or not the process of step ST201 described above has been performed for all the input ports by comparing the updated parameter i with the constant N. (ST203). If an unprocessed input port remains, the transmission band limiting unit 422 returns to step ST201 described above, and if the process of step ST201 described above is executed for all input ports, FIG. The series of processes shown in FIG.

  FIG. 3C is a calculation flowchart for calculating a transmission limited band according to each input interface unit. In addition, it is preferable that the calculation flowchart of FIG. 3 (a) and FIG.3 (b) is complete | finished before performing the calculation flowchart of FIG.3 (c). Even if it is not completed, it is necessary that the value necessary for the calculation in step ST301 has already been calculated.

  When the process shown in FIG. 3C is started, transmission limited band calculation section 422 initializes parameter i to 0 (ST300). Then, the transmission limited band calculation unit 422 calculates the transmission limited band [i] for the input port (in other words, the input interface unit) determined by the current parameter i according to the equation (1), and then calculates the parameter i. Increment by 1 (ST301). After that, the transmission limited band calculation unit 422 determines whether the transmission limited band [i] has been calculated for all the input interface units by comparing the updated parameter i and the constant N (ST302). If an uncalculated input interface unit remains, the transmission limited bandwidth calculation unit 422 returns to step ST301 described above, and if the transmission limited bandwidth [i] is executed for all the input interface units, FIG. The series of processes shown in c) is terminated.

Transmission limit band [i] = inR [i]
+ EBW × (pRmin [i] / ΣpRmin) (1)
The transmission limited bandwidth [i] calculated by the equation (1) is the total value inR [i] of the input bandwidth of the user whose buffer belonging to the input port i is not congested (that is, the first term on the right side of the equation (1)). ) And the minimum guaranteed bandwidth of the user whose buffer belonging to the input port i is congested with respect to the total value ΣpRmin of the minimum guaranteed bandwidth of the user whose buffer is congested among all the users belonging to all the input ports. A band obtained by allocating the effective band eBW to the input port i according to the ratio of the total value pRmin [i] (that is, the second term on the right side of the equation (1)) is secured.

  From the first term on the right side of the equation (1), it is expected that the bandwidth of the non-congested user is continuously secured. By the second term on the right side of the equation (1), fairness of bandwidth allocation between users in a congested state (in other words, between input interface units) in view of the minimum guaranteed bandwidth can be expected.

  Returning to FIG. 2, as described above, the RMm packet transmission unit 423-2 determines the transmission limited bandwidth obtained by the RMm packet reception units 414-0 and 414 of the corresponding input interface units 100-0 and 100-1. 1 and the transmission limited bands received by the RMm packet receiving units 414-0 and 414-1 are notified to the reading control units 104-0 and 104-1. The inter-group read control units 104-0 and 104-1 control the output band so that the output from the inter-group read control units 104-0 and 104-1 is equal to or less than the notified transmission limited band. Further, the inter-group read control units 104-0 and 104-1 control the packet output from each queue group within the limited output band by round robin using the minimum guaranteed band of the queue group as a weight. In-group read control units 103-0-0 and 103-1-0, 103-0-1 and 103-1-1.

  The intra-group read control units 103-0-0, 103-1-0, 103-0-1, 103-1-1-1104 are within the bandwidth allocated by the inter-group read control units 104-0, 104-1. A packet is read out from the packet queue side with a high priority by complete priority control.

  Hereinafter, the state of determination and control of the transmission limit band will be described with specific numerical values. Here, an example in which there are three input / output interface units as shown in FIG. 2 will be described.

  Now, the physical bandwidth between the input interface unit and the packet switching unit (hereinafter referred to as the input physical bandwidth as appropriate) is 10 Gbps, and the physical bandwidth between the packet switching unit and the output interface unit (BW; hereinafter referred to as the output physical band as appropriate). ) Is 10 Gbps, and the minimum guaranteed bandwidths of contract users A, B, C, and D are 10 Mbps, 20 Mbps, 30 Mbps, and 40 Mbps, respectively.

  If the total input bandwidth of the contract users A, B, C, and D is less than or equal to the output physical bandwidth of 10 Gbps, the output buffer 302-2 is in a non-congested state, so that each transmission limited bandwidth is 10 Gbps, and each user's input is Output as is.

  When the input bandwidths of the contract users A, B, C, and D all become 5 Gbps, the output buffer 302-2 is in a congestion state. At this time, flow control is applied to the input interface units 100-0 and 100-1, and output from the input interface units 100-0 and 100-1 is limited. Therefore, each queue group QG0-0, QG1-0, QG1 −0 and QG1-1 are in a threshold excess state.

  Therefore, by the process shown in FIG. 3A, pRmin [0] = 10 + 20 = 30 Mbps, pRmin [1] = 30 + 40 = 70 Mbps, and ΣpRmin = pRmin [0] + pRmin [1] = 100 Mbps. Further, since there is no non-congested user, inR [0] = 0 and inR [1] = 0, and eBW = 10 Gbps is obtained by the process shown in FIG. 3C, the transmission limited bandwidth of the input interface unit 100-0 is 0 + 10 Gbps × (30 Mbps / 100 Mbps) = 3 Gbps, and the transmission limited bandwidth of the input interface unit 100-1 is 0 + 10 Gbps × ( 70 Mbps / 100 Mbps) = 7 Gbps.

  The inter-group read control unit 104-0 of the input interface unit 100-0 performs the read process with the weight of the minimum guaranteed bandwidth of the contract users A and B, and the output bandwidth from the contract user A is 3 out of the transmission limited bandwidth 3 Gbps. × 10 / (10 + 20) = 1 Gbps, and the output bandwidth from the contract user B is 3 × 20 / (10 + 20) = 2 Gbps. On the other hand, the inter-group read control unit 104-1 of the input interface unit 100-1 performs the read process with the weight of the minimum guaranteed bandwidth of the contract users C and D, and the output bandwidth from the contract user C out of the limited bandwidth 7 Gbps is 7 × 30 / (30 + 40) = 3 Gbps, and the output bandwidth from the contract user D is 7 × 40 / (30 + 40) = 4 Gbps.

  Therefore, even when the input bandwidths of the contract users A, B, C, and D all become 5 Gbps, the output bandwidth of the contract users A, B, C, and D is controlled to 1 Gbps, 2 Gbps, 3 Gbps, 4 Gbps, and the minimum guaranteed bandwidth Fair bandwidth control according to

  In addition, when the input bandwidths of the contract users A, B, C, and D become 5 Gbps, 5 Gbps, 5 Gbps, and 1 Gbps, the output buffer 302-2 becomes congested. At this time, flow control is applied to the input interface units 100-0 and 100-1, and output from the input interface units 100-0 and 100-1 is restricted. Therefore, the queue groups QG0 of the contract users A, B, and C −0, QG1-0, and QG1-0) are in an over-threshold state, but the contract user D (the queue group QG1-1) is not in an over-threshold state because the input is 1 Gbps.

  Therefore, by the process shown in FIG. 3A, pRmin [0] = 10 + 20 = 30 Mbps, pRmin [1] = 30 Mbps, and ΣpRmin = pRmin [0] + pRmin [1] = 60 Mbps. Further, in this case, since only the contract user D is not in the threshold excess state, inR [0] = 0 and inR [1] = 1 Gbps, and eBW = 10−1 = 9 Gbps is obtained by the process shown in FIG. . 3C, the transmission limited bandwidth of the input interface unit 100-0 is 0 + 9 Gbps × (30 Mbps / 60 Mbps) = 4.5 Gbps, and the transmission limited bandwidth of the input interface unit 100-1 is 1 Gbps + 9 Gbps × ( 30 Mbps / 60 Mbps) = 5.5 Gbps.

  The inter-group reading control unit 104-0 of the input interface unit 100-0 performs the reading process with the weight of the minimum guaranteed bandwidth of the contract users A and B, and the output bandwidth from the contract user A out of the limited bandwidth 4.5 Gbps is 4.5 × 10 / (10 + 20) = 1.5 Gbps, and the output bandwidth from the contract user B is 4.5 × 20 / (10 + 20) = 3 Gbps. On the other hand, the output bandwidth of the contract user D from the inter-group reading control unit 104-1 of the input interface unit 100-1 remains 1 Gbps as the input bandwidth, and the remaining 4.5 Gbps becomes the output bandwidth of the contract user C. Therefore, even if the input bandwidth of the contract users A, B, C, and D is 5 Gbps, 5 Gbps, 5 Gbps, and 1 Gbps, the output bandwidth of the contract users A, B, and C is 1.5 Gbps, 3 Gbps, and 4.5 Gbps. Therefore, fair bandwidth control according to the minimum guaranteed bandwidth can be realized.

(A-3) Effects of Embodiment According to the above embodiment, the output interface unit manages the transmission bandwidth of all flows output from the output interface unit, and the managed bandwidth is transferred to the input interface unit side. Since the notification is made and the transmission bandwidth of each flow is controlled to the controlled bandwidth on the input interface unit side, a plurality of flows from a plurality of input interface units are concentrated on one output interface unit and output. Even in such a case, bandwidth guarantee and fairness among contracting users can be realized without causing packet discard in the packet switching unit or the output interface unit.

  Further, according to the above-described embodiment, the bandwidth control information notified from the input interface unit side to the output interface unit side is a threshold excess state (1 bit of logic “0” or “1”) of each queue group and This is the total input bandwidth value of the queue group in the non-congested state, and the bandwidth control information notified from the output interface side to the input interface side is not the transmission permission amount for each queue group, but the transmission per input interface unit. Since the bandwidth is limited, the transmission amount of bandwidth control information can be reduced. This is very effective when the bandwidth control information is transferred in the same in-channel as the user packet. In addition, since the bandwidth control information is reduced, the processing load of the transmission limited bandwidth calculation can be reduced.

  Furthermore, according to the above embodiment, there is a contract user whose input bandwidth is smaller than the bandwidth allocated with the minimum bandwidth guarantee ratio because the total bandwidth of the contracted users in the non-congested state is used for the transmission bandwidth limit calculation. Even in this case, it is possible to achieve fairness among contract users who are congested.

(B) Other Embodiments In the description of the above-described embodiment, various modified embodiments have been mentioned.

  In the above embodiment, the case of transferring the bandwidth control information between the master side bandwidth control unit and the slave side bandwidth control unit through the same in-channel as the user packet has been shown. You may make it do.

  In the above embodiment, the master side bandwidth control unit is provided in the output interface unit and the slave side bandwidth control unit is provided in the input interface unit. However, the present invention is not limited to this. For example, if an out-channel transfer method is applied to transfer bandwidth control information, the master-side bandwidth control unit should be provided in association with each output buffer of the packet switching unit, not the output interface unit. May be. For example, the master side bandwidth control unit may be provided on a dedicated board instead of the output interface unit or the packet switching unit.

  In the above embodiment, the case where the queue group and the contract user correspond one-to-one has been described, but the setting of the queue group is not limited to this. For example, a plurality of queue groups may be set for one contract user. For example, the queue group may be set from a viewpoint other than the contract user (for example, the destination area).

  In the above embodiment, the case where there is a concept of a queue group to which a plurality of packet queues belongs is shown, but the technical idea of the present invention can also be applied when there is no concept of a queue group. This modified embodiment corresponds to the case where there is one packet queue belonging to the queue group in the above embodiment, and corresponds to the case where there is no intra-group read control unit and there is only an inter-group read control unit.

  In the description of the operation of the above embodiment, the case where there are two input interface units is mentioned, but it is needless to say that there may be two or more input interface units, and the same effect can be obtained even when there are two or more input interface units.

  In the description of the operation of the above embodiment, the case where the queue group per input interface unit is 2 and the number of packet queues per queue group is 2 is mentioned, but it goes without saying that these may be 2 or more. Even in the case of two or more, the same effect can be obtained.

  In the specific operation description of the above embodiment, the example in which the read control from the packet queue is controlled by the high priority and the low priority, the complete priority type is described. For example, a control method such as weighted round robin (WRR) is used. Even if it uses, the same effect can be produced.

  In the above embodiment, a configuration including an input / output interface unit in which an input interface unit and an output interface unit are integrated (for example, a configuration in which an input interface unit and an output interface unit are mounted on the same board) is shown. However, it goes without saying that the input interface unit and the output interface unit may be separate.

  In the above-described embodiment, the RMs packet for notifying the measured input bandwidth and the threshold excess state is periodically transmitted. However, the congestion state of the corresponding output buffer is not transmitted periodically. When a transmission request is given from the recognized transmission limited bandwidth calculation unit, an RMs packet for notifying the measured input bandwidth and the threshold excess state may be transmitted.

  In the above embodiment, the case where fairness among contract users is realized based on the minimum guaranteed bandwidth is shown, but fairness may be secured by other methods or other parameters. For example, the control may be such that equal fairness is obtained for each contract user. In this case, the ratio of multiplying the effective bandwidth eBW in the second term on the right side of equation (1) may be the number of users in the congestion state at the port i with respect to the number of users in the congestion state at all ports. Further, for example, if the bandwidth contract with the user is performed in a range, the fairness can be improved by applying other parameters such as the median bandwidth of the range and the representative bandwidth of the range instead of the minimum guaranteed bandwidth. You may make it secure.

DESCRIPTION OF SYMBOLS 1 ... Packet switching apparatus, 2-0-2-X ... Input / output interface part,
100: Input interface section,
DESCRIPTION OF SYMBOLS 101 ... Packet receiving part, 102 ... Flow identification part, 103-0 to 103-n ... In-group read control part, 104 ... Inter-group read control part, 105 ... Slave side band control part, 106 ... Transmission control part, 411 ... Threshold excess detection unit, 412 ... input band measurement unit, 413 ... RMs packet transmission unit, 414 ... RMm packet reception unit, QG0 to QGn ... queue group, Q01 to Qnm ... packet queue,
200 ... output interface part,
DESCRIPTION OF SYMBOLS 201 ... Reception control part, 202 ... Packet distribution part, 203 ... Master side band control part, 204 ... Reception buffer, 205 ... Packet transmission part, 421 ... RMs packet reception part, 422 ... Transmission restriction band calculating part, 423 ... RMm Packet transmitter,
3 ... Packet switching part,
300-1 to 300-X: input buffer, 301: packet switch, 302-1 to 302-X: output buffer.

Claims (5)

A plurality of input interface means for inputting packets, a plurality of output interface means for outputting packets, and a plurality of input buffers and packets for outputting packets from the respective input interface means to the output interface means corresponding to the destination In a packet switching device comprising a switch and a packet switching means having a plurality of output buffers,
Each of the input interface means is
A plurality of packet storage units that store input packets and that have different packet flows;
A flow identification unit that identifies the flow of the input packet and distributes the packet to one of the packet storage units;
A packet read control unit that reads out packets stored in the plurality of packet storage units while switching a packet storage unit to be read; and
An input bandwidth measuring unit that measures the input bandwidth of the packet to each of the packet storage units;
An over-threshold detection unit for detecting whether or not the accumulated amount of each packet storage unit exceeds a threshold;
It has a measured input bandwidth, a storage unit information transmission unit for transmitting detected information exceeding the threshold,
Each output interface means is
A transmission band limiting operation unit for determining a transmission band limit for each of the plurality of input interface units when a congestion state of the output buffer corresponding to the output interface unit is detected;
A transmission limit band notifying unit for notifying the corresponding input interface means of the transmission limit band of each of the input interface means obtained by the transmission limit band calculating unit;
The packet read control unit of each input interface means performs packet read control from the plurality of packet storage units based on the notified transmission limit band,
Further, the transmission band limiting operation unit is
Among the plurality of packet accumulating units included in one input interface means that is a target for obtaining the transmission limited band, the input band measuring unit for the packet accumulating unit detected by the threshold excess detecting unit as not exceeding the threshold A first sum total of the input bands measured by
A residual bandwidth obtained by subtracting the first total value by the plurality of input interface means from a physical bandwidth between the packet switching means and the output interface means;
While obtaining a coefficient based on the information on the threshold excess detected by the threshold excess detector,
The packet switching device, wherein the transmission limited bandwidth is obtained by adding the remaining bandwidth multiplied by the coefficient to the first total value. Each of the packet storage units provided in the same input interface means has a plurality of storage parts,
The packet read control unit
A plurality of in-packet storage read control units for controlling reading from a plurality of storage parts constituting each of the packet storage units;
The packet switching apparatus according to claim 1, further comprising: an inter-packet storage unit read control unit that performs control for granting read control authority to any one of the plurality of in-packet storage unit read control units. The transmission band limiting unit is
Among the plurality of packet accumulating units included in one input interface means that is a target for obtaining the transmission limited band, a predetermined minimum guaranteed bandwidth is set for a packet accumulating unit that is detected as exceeding the threshold by the threshold excess detecting unit. A second sum total,
A third total value obtained by summing the second total value for all the plurality of input interface means is obtained, and
As the coefficient, a ratio obtained by dividing the second total value by the third total value is obtained, and a value obtained by multiplying the remaining bandwidth by the ratio is added to the first total value, whereby the transmission restriction is performed. The packet switching device according to claim 1, wherein a bandwidth is obtained. A plurality of input interface means for inputting packets, a plurality of output interface means for outputting packets, and a plurality of input buffers and packets for outputting packets from the respective input interface means to the output interface means corresponding to the destination A computer mounted in a packet switching device comprising a switch and a packet switching means having a plurality of output buffers;
A plurality of packet storage units that store input packets and that have different packet flows;
A flow identification unit that identifies the flow of the input packet and distributes the packet to one of the packet storage units;
A packet readout control unit that reads out packets stored in the plurality of packet storage units while switching the packet storage unit to be read based on the notified transmission limit band;
An input bandwidth measuring unit that measures the input bandwidth of the packet to each of the packet storage units;
An over-threshold detection unit for detecting whether or not the accumulated amount of each packet storage unit exceeds a threshold;
A storage unit information transmission unit for transmitting the measured input bandwidth, the detected threshold excess information, and
A transmission limit bandwidth calculating unit for obtaining a transmission limit bandwidth for each of the plurality of input interface means when a congestion state of the output buffer corresponding to any of the output interface means is detected;
The transmission limited bandwidth of each of the input interface means obtained by the transmission limited bandwidth calculation unit, function as a transmission limited bandwidth notification unit that notifies the corresponding input interface means,
Further, the transmission band limiting operation unit is
Among the plurality of packet accumulating units included in one input interface means that is a target for obtaining the transmission limited band, the input band measuring unit for the packet accumulating unit detected by the threshold excess detecting unit as not exceeding the threshold A first sum total of the input bands measured by
A residual bandwidth obtained by subtracting the first total value by the plurality of input interface means from a physical bandwidth between the packet switching means and the output interface means;
While obtaining a coefficient based on the information on the threshold excess detected by the threshold excess detector,
A band control program characterized in that the transmission limited band is obtained by adding the remaining band multiplied by the coefficient to the first total value. A plurality of input interface means for inputting packets, a plurality of output interface means for outputting packets, and a plurality of input buffers and packets for outputting packets from the respective input interface means to the output interface means corresponding to the destination In a packet switching method in a packet switching device comprising a switch and a packet switching means having a plurality of output buffers,
Each packet storage unit having a different packet flow stored in each input interface means stores the input packet,
The flow identification unit of each input interface means identifies the flow of the input packet and distributes the packet to any of the packet storage units,
The packet read control unit of each input interface means reads out the packets stored in the plurality of packet storage units while switching the packet storage units to be read,
The input bandwidth measuring unit of each input interface means measures the input bandwidth of the packet to each of the packet storage units,
The threshold value excess detection unit of each input interface means detects whether or not the accumulation amount of each packet accumulation unit exceeds a threshold value,
The storage unit information transmission unit of each of the input interface means transmits the measured input bandwidth, the detected information exceeding the threshold,
The transmission limit band calculating unit of each output interface means obtains a transmission limit band for each of the plurality of input interface means when a congestion state of the output buffer corresponding to the output interface means is detected,
The transmission limit band notifying unit of each output interface means notifies the corresponding input interface means of the transmission limit band of each of the input interface means obtained by the transmission limit band calculating unit,
The packet read control unit of each input interface means performs packet read control from the plurality of packet storage units based on the notified transmission limit band,
Further, the transmission limit band calculation unit of each output interface means,
Among the plurality of packet accumulating units included in one input interface means that is a target for obtaining the transmission limited band, the input band measuring unit for the packet accumulating unit detected by the threshold excess detecting unit as not exceeding the threshold A first sum total of the input bands measured by
A residual bandwidth obtained by subtracting the first total value by the plurality of input interface means from a physical bandwidth between the packet switching means and the output interface means;
While obtaining a coefficient based on the information on the threshold excess detected by the threshold excess detector,
A packet switching method, wherein the transmission limited bandwidth is obtained by adding the remaining bandwidth multiplied by the coefficient to the first total value.

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