JP2015050479A - Packet switch, packet switching method and band control program - Google Patents

Packet switch, packet switching method and band control program Download PDF

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JP2015050479A
JP2015050479A JP2013178526A JP2013178526A JP2015050479A JP 2015050479 A JP2015050479 A JP 2015050479A JP 2013178526 A JP2013178526 A JP 2013178526A JP 2013178526 A JP2013178526 A JP 2013178526A JP 2015050479 A JP2015050479 A JP 2015050479A
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flow
unit
packet
input
output
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久野 隆治
Takaharu Kuno
隆治 久野
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株式会社オー・エフ・ネットワークス
O F Networks Co Ltd
沖電気工業株式会社
Oki Electric Ind Co Ltd
株式会社フジクラ
Fujikura Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a packet switch capable of achieving flow-by-flow band guarantee and band impartiality between flows, and capable of accommodating a large number of flows with a suppressed transfer amount between an input IF unit and an output IF unit.SOLUTION: Each input IF unit includes: a flow discrimination unit for discriminating an input packet flow; a flow rate restriction unit for restricting a flow rate on a flow-by-flow basis, on condition that an output buffer in a packet switch unit scheduled to buffer a packet related to a flow is in a congestion state and an input flow rate exceeds a threshold; and a congestion instruction unit, on receiving the notification of a congestion state and/or a non-congestion state of the output buffer, for setting the notification information into the flow rate restriction unit. In regard to the output IF unit, a state notification unit is provided for periodically monitoring an output buffer state to notify each input IF unit.

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 switch 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.

  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 a plurality of input interface units, a plurality of output interface units, 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, suppresses the amount of transfer information between the input interface unit and the output interface unit, and guarantees bandwidth for each flow (the flow here may be a flow group). An object of the present invention is to provide a packet switching apparatus, a packet switching method, and a bandwidth control program capable of realizing a fairness of bandwidth between flows and economically accommodating many 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. 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) identifies a flow of an input packet. (1-2) The flow is limited for each flow, the output buffer that is scheduled to buffer packets related to the flow is in a congested state, and the input flow rate has a threshold value. A flow restriction unit that restricts the flow on the condition that it exceeds, and (1-3) a packet related to the flow A congestion instruction unit for receiving a notification of congestion and / or non-congestion state of the output buffer to be buffered, and setting the state of the output buffer in the flow restriction unit, and (2) related to each output interface means And periodically monitoring the state of the output buffer corresponding to the output interface means, and each input interface of the transmission source of the packet buffered by the output buffer for the congestion and / or non-congestion state of the output buffer. A state notifying unit for notifying the means is provided.

  A bandwidth control program according to a second aspect of the present invention includes a plurality of input interface means for inputting a packet, a plurality of output interface means for outputting the packet, and the output interface according to the destination of the packet from each of the input interface means (1) a flow identification for identifying a flow of an input packet; (1) identifying a flow of an input packet; and a computer mounted on a packet switching device having a plurality of input buffers, a packet switch, and a packet switching unit having a plurality of output buffers. (2) The flow rate is limited for each flow, the output buffer that is scheduled to buffer packets related to the flow is in a congested state, and the input flow rate exceeds the threshold value. A flow restriction unit that restricts the flow rate to the condition; and (3) buffering packets related to the flow. A congestion instruction unit for receiving the notification of congestion and / or non-congestion state of the output buffer to be set, and setting the state of the output buffer in the flow restriction unit; and (4) periodically monitoring the state of the output buffer. The output buffer is configured to function as a state notification unit that notifies the input interface means of the transmission source of the packet buffered by the output buffer.

  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. In the packet switching method 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) the flow identification unit provided in each input interface means is input (2) the flow rate limiting unit provided in each of the input interface means that the output buffer scheduled to buffer the packet related to the flow is in a congested state, and that the input flow rate is The flow is limited for each flow on condition that the threshold is exceeded. (3) The congestion instruction unit provided in each of the input interface means receives the notification of the congestion and / or the non-congestion state of the output buffer that is scheduled to buffer the packet related to the flow, and outputs the output to the flow restriction unit. (4) a status notification unit provided in association with each output interface means periodically monitors the status of the output buffer corresponding to the output interface means, and The congestion and / or non-congestion state is notified to each input interface means of the transmission source of the packet buffered by the output buffer.

  According to the present invention, the amount of transfer information between the input interface unit and the output interface unit can be kept low, the bandwidth can be guaranteed for each flow, and the fairness of the bandwidth between the flows can be economically accommodated. A packet switching device, 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 1st Embodiment. It is a block diagram for explaining the operation of the packet switching apparatus according to the first embodiment. It is explanatory drawing (the 1) of the flow volume limiting method in the packet switching apparatus of 1st Embodiment. It is explanatory drawing (the 2) of the flow volume limiting method in the packet switching apparatus of 1st Embodiment. It is a flowchart which shows the process (algorithm) which changes the threshold value for flow volume restrictions in the packet switching apparatus of 1st Embodiment. It is a flowchart which shows the process (algorithm) which changes the priority which receives flow volume restrictions when the threshold value is exceeded in the packet switching apparatus of 1st Embodiment. It is explanatory drawing that the packet switching apparatus of 1st Embodiment can eliminate a congestion state by performing the process which changes the threshold value for flow volume limitation. It is explanatory drawing that a congestion state can be eliminated by performing the process which the packet switching apparatus of 1st Embodiment changes the priority which receives flow volume restriction | limiting when a threshold value is exceeded. It is a block diagram which shows the functional structure of the packet switching apparatus of 2nd Embodiment.

(A) First Embodiment Hereinafter, a first embodiment of a packet switching apparatus, 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 the First Embodiment FIG. 1 is a block diagram showing a functional configuration of the packet switching apparatus 1 of the first embodiment. The packet switching device 1 of the first embodiment may be configured entirely by hardware, partially configured by hardware, and the rest by a CPU and a program executed by the CPU. Whichever configuration method is employed, it can be functionally represented in FIG. For example, a flow identification unit 102, a flow rate limiting unit 103, a slave side bandwidth control unit 105, a master side bandwidth control unit 204, and the like, which will be described later, 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 (a is 0 to X), the packet switching unit 3 analyzes the destination of the packet, and the output interface unit 200-b (b is 0 to 0) corresponding to the destination. X) is a packet. 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 reception unit 101, a flow identification unit 102, a flow rate restriction unit 103, a slave side bandwidth control unit 105, and a transmission control unit 104.

  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 provides the identification information and the packet to the subsequent flow rate limiting unit 103. Is. Here, the priority level determined by the priority identifier may be a plurality of levels, and is not limited to two levels. For example, there may be eight levels of priority 0 to 7 (see FIG. 6 described later).

  The flow rate limiting unit 103 monitors the input bandwidth for each contract user including the received packet, and in accordance with an instruction from the congestion instruction unit 402 of the slave side bandwidth control unit 105, the congestion of any output buffer 302 of the packet switching unit 3 Sometimes, the flow rate is limited by exceeding one or a plurality of threshold values set in advance for each contract user, or when non-congested, the packet is transmitted to the transmission control unit 104 in the subsequent stage without limiting the flow rate. It is. Further, the flow restriction unit 103 changes the threshold for each contract user or switches the priority for restricting the flow for one or a plurality of contract users in accordance with an instruction from the flow restriction reference setting unit 403 of the slave side bandwidth control unit 105. It is something to do.

  The transmission control unit 104 multiplexes a packet for each contract user from the input port PIN and a control packet from a control packet transmission unit 412 of the master side bandwidth control unit 204 described later, and transmits the multiplexed packet to the packet switching unit 3. .

  The slave side bandwidth control unit 105 includes a control packet reception unit 401, a congestion instruction unit 402, and a flow rate restriction reference setting unit 403.

  The control packet receiving unit 401 receives a control packet given from the output interface unit 200.

  The congestion instruction unit 402 instructs all the contract users to execute the flow restriction in the flow restriction unit 103 according to the congestion state of the output buffers 302-0 to 302-X in the packet switching unit 3. This is performed for the restriction unit 103. For example, if the output buffer 302-1 is in a congested state, the flow rate restriction for the contract user of the flow passing through the output buffer 302-1 is performed.

  The flow restriction reference setting unit 403 changes the setting value of one or a plurality of thresholds for the input band in the flow restriction unit 103 set for each contract user, or the priority of restriction when the threshold is exceeded. The upper limit value is changed.

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

  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 it is a user packet or a control packet, distributes the user packet to the packet transmission unit 203, and distributes the control packet to the slave side bandwidth control unit of the input interface unit 100. 105.

  The packet transmission unit 203 outputs the user packet from the packet distribution unit 202 to the output port POUT.

  The master side bandwidth control unit 204 includes a congestion state generation unit 411 and a control packet transmission unit 412.

  The congestion state generation unit 411 monitors the output buffer congestion state of the packet switching unit 3 and generates a control packet for notifying the slave side bandwidth control unit 105 of the congestion state.

  The control packet transmission unit 412 transmits the control packet generated by the congestion state generation unit 411 to the transmission control unit 104 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, and a plurality of output buffers 302-0 to 302-X.

  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 congestion state generation unit 411 of the corresponding output interface units 200-0 to 200-X.

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

  FIG. 2 is a drawing for explaining the operation. In FIG. 2, for the sake of simplicity of explanation, the number of input / output interface units is three and belongs to the same input / output interface unit 2-a (a is 0 to X; X here is 2). An example in which the packet switching apparatus 1 is configured so that a packet from the input interface unit 100-a cannot be given to the output interface unit 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.

  Here, the packets of the contract user A and the contract user B are input to the input / output interface unit 2-0, and the packets of the contract user C and the contract user D are input to the input / output interface unit 2-1. And

  User packets input to the input / output interface units 2-0 and 2-1 (hereinafter, user packets are simply referred to as packets) pass through the packet receiving units 101-0 and 101-1, respectively, and then flow identification units 102- At 0 and 102-1, the flow is identified for each contract user and input to the flow rate restriction units 103-0 and 103-1.

  Each flow restriction unit 103-0, 103-1 has two flow restriction thresholds (hereinafter referred to as first threshold value R1 and second threshold value R2) as shown in FIG. It is set, and for each contract user, it is monitored whether or not the input flow rate (input data amount) exceeds the first threshold value R1 and the second threshold value R2, and the flow rate is appropriately limited according to the monitoring result. In the example of FIG. 3A, two threshold values, the first threshold value R1 and the second threshold value R2, are used, but the flow rate restriction threshold value is not limited to two, and may be one or three or more. good.

  The packets output from the flow rate limiting units 103-0 and 103-1 are given to the packet switching unit 3 through the transmission control units 104-0 and 104-1. In the packet switching unit 3, the input packet is buffered by the input buffers 300-0 and 300-1, and then switched according to the destination of the packet by the packet switch 301, and the output buffer 302-2 corresponding to the destination Sent to.

  FIG. 2 shows an output buffer 302-in which all the packets of the contract user A and contract user B of the input / output interface unit 2-0 and the contract user C and contract user D of the input / output interface unit 2-1 are the same. 2 shows an example of transmission.

  The packet buffered in the output buffer 302-2 is sent to the reception control unit 201-2 of the input / output interface unit 2-2, and is distributed to the packet transmission unit 203-2 by the packet distribution unit 202-2. The data is transmitted to the output port POUT-2 by the transmission unit 203-2. The amount of data that can be received by the reception control unit 201-2 is transmitted to the output port POUT-2 without decreasing even after passing through the packet distribution unit 202-2 and the packet transmission unit 203-2.

  Here, the output buffer 302-2 of the packet switching unit 3 has, for example, the total data amount of each of the contract users A, B, C, and D stored in the output port POUT-2 of the input / output interface unit 2-2. If the amount of data is not continuously exceeded, congestion does not occur and excessive accumulation of data does not occur (congestion state “0”).

  However, if the total data amount of each contract user A, B, C, D exceeds the amount of data transmitted to the output port POUT-2, congestion occurs (congestion state “1”). .

  The congestion state generation unit 411-2 of the input / output interface unit 2-2 periodically monitors whether or not the output buffer 302-2 is in a congestion state at a preset monitoring interval, and includes an input including the monitoring result. Control packets addressed to the output interface units 2-0 and 2-1 are generated and given to the control packet transmission unit 412-2 for transmission. Such a control packet is transmitted from the transmission control unit 104-2 to the packet switching unit 3, and via the packet switching unit 3, the reception control units 201-0 and 201- of the input / output interface units 2-0 and 2-1. Is given to 1.

  In each of the input / output interface units 2-0 and 2-1, control packets received by the reception control units 201-0 and 201-1 are transmitted to the control packet reception unit 401-0 by the packet distribution units 202-0 and 202-1. , 401-1. Each control packet receiving unit 401-0, 401-1 determines from the received control packet which input / output interface unit the output buffer is congested and / or uncongested (for example, the source of the control packet) The flow rate restriction reference setting units 403-0 and 403-1 and the congestion instruction units 402-0 and 402-1 are notified of the presence or absence of a congestion state.

  Each congestion instruction unit 402-0 and 402-1 has the same period as the congestion state generation unit 411-2 of the input / output interface unit 2-2 described above monitors the congestion state of the output buffer 302-2 of the packet switching unit 3. At a cycle, the presence / absence of the notified congestion state is monitored, and the monitoring result is notified to the flow restriction units 103-0 and 103-1.

  Each flow restriction unit 103-0 and 103-1 performs flow restriction for each contract user as necessary based on the notified congestion state presence / absence information. If it is a non-congested state, the flow restriction units 103-0 and 103-1 transmit the input packet to the transmission control units 104-0 and 104-1, without restricting the flow rate. On the other hand, if it is a congestion state, the flow restriction units 103-0 and 103-1 perform flow restriction. For example, the flow restriction is discarding of input packets.

  Hereinafter, the flow rate limiting method will be described with reference to FIG. FIG. 3A shows the input flow rate (total data amount of input data) to the flow restriction unit 103 (103-0 or 103-1), and FIG. 3B shows the flow restriction unit 103 (103-0). Alternatively, the output flow rate from 103-1) is shown, and the difference between the input flow rate and the output flow rate is a limited flow rate.

  In the example of the flow rate limiting method shown in FIG. 3, the packets input for each contracted user are high priority packets (indicated as high priority frames in FIG. 3; hereinafter referred to as high priority frames) and low priority packets ( In FIG. 3, it is described as a low-priority frame; hereinafter referred to as a low-priority frame, and is divided into two. ) Is compared with the first threshold value R1 and the second threshold value R2, and a specific flow rate limiting method is determined. For example, there are eight stages with priorities of 0 to 7. Frames with priorities 0 to 4 are set as low priority frames, and frames with priorities 5 to 7 are set as high priority frames. If the priority of the frame (packet) from the contract user A is 6, the flow restriction unit 103 identifies it as a high priority frame, and if the priority of the frame (packet) from the contract user B is 4, the flow rate The restriction unit 103 identifies the frame as a low priority frame.

  When the input flow rate exceeds the larger first threshold value R1 of the two threshold values, the flow rate limiting unit 103 limits the flow rate to the first threshold value R1 without distinguishing between the high priority frame and the low priority frame. The first half period t1 to t2 of the sixth cycle T6 in FIG. 3B is a period in which such flow rate restriction is performed.

  If the input flow rate does not exceed the first threshold value R1, but the input flow rate exceeds the second threshold value R2, the flow restriction unit 103 restricts the flow rate of only the low priority frame to the second threshold value R2. . Periods t2 to t3 of the second period T2, the fourth period T4, and the sixth period T6 in FIG. 3B are periods in which such flow rate restriction is performed.

  Furthermore, when the input flow rate does not exceed the second threshold value R2, the flow rate limiting unit 103 does not perform the flow rate limitation without distinguishing between the low priority frame and the high priority frame. The period after the period t3 of the sixth cycle T6 in FIG. 3B is a period in which such flow rate restriction is not executed.

  The presence / absence of the flow rate restriction is based on the presence / absence of a congestion state instructed at every congestion state monitoring period. In the fifth cycle T5 of FIG. 3B, the input flow rate exceeds at least the second threshold value R2, but this cycle is a non-congested cycle and the flow rate restriction is not performed. The flow restriction unit 103 does not restrict the flow without distinguishing between low priority frames and high priority frames.

  FIG. 4 shows a case where all the frames input to the flow restriction unit 103 are high priority frames. As shown in FIG. 4A, it is assumed that the input flow rate to the flow rate limiting unit 103 does not exceed the first threshold value R1 even though it exceeds the second threshold value R2. In this case, even if a congestion state occurs on the destination side and the flow rate is limited, there is no period in which the input flow rate exceeds the second threshold value R2, and therefore, as shown in FIG. Does not limit the flow rate, and the congestion on the destination side continues.

  Unlike FIG. 4, even when all the input frames are low priority frames, the congestion state may continue because the second threshold R2 is not exceeded, and high priority frames and low priority frames are mixed. Even if it is input, the congestion state may continue because the second threshold value R2 is not exceeded.

  In order to avoid the continuation of the congestion state as described above, in the first embodiment, a flow rate restriction reference setting unit 403 is provided to change the thresholds R1 and R2 dynamically, or to set priority for restricting the flow rate. It was decided to change it dynamically. Note that it is rare that the congestion state as shown in FIG. 4 continues, and the flow rate restriction reference setting unit 403 may not be provided.

  The flow rate restriction reference setting unit 403 may only change the threshold values R1 and R2 dynamically, or only change the priority of receiving the flow restriction when the threshold value is exceeded. Moreover, both the dynamic change of the threshold values R1 and R2 and the dynamic change of the priority that receives the flow restriction when the threshold value is exceeded may be performed.

  FIG. 5 is a flowchart showing processing (algorithm) for changing the threshold values R1 and R2. FIG. 5 shows processing for one contract user, and the processing shown in FIG. 5 is executed for each contract user.

  When the start shown in FIG. 5 starts, the flow rate restriction reference setting unit 403 sets the default value r1 [u] for the contract user u as the first and second thresholds R1 [u] and R2 [u] of the contract user u, A parameter representing a decrease width M (when a threshold value is changed by setting a value c to a boundary value (representing a parameter) that is smaller by one than the number C of consecutive periods of congestion in which r2 [u] is changed and the threshold value is changed. ) Is set to an initial value m, and a value l is set to a threshold lower limit value (a parameter representing) L (step S10). In other words, the boundary value C described above is the upper limit value C of the number of consecutive cycles in a congested state that maintains the previous threshold. Further, there is a relationship r1 [u]> r2 [u] between the default values r1 [u] and r2 [u] of the first and second threshold values.

  Thereafter, the continuous count value count of the congestion state cycle is set to an initial value 0 (step S11).

  When a new notification cycle is reached, the flow restriction reference setting unit 403 determines whether the notification content of congestion and / or non-congestion in that cycle is a congestion state “1” (step S12). If the non-congested state is “0”, the process returns to step S10 described above to return to the default setting.

  On the other hand, if the state of the new notification cycle is the congestion state “1”, the flow restriction reference setting unit 403 increments the continuous count value count by 1 (step S13), and then continues the cycle in which the value count maintains the threshold value. It is determined whether or not the upper limit value C is exceeded (step S14). If the value count does not exceed the upper limit value C, the flow restriction reference setting unit 403 returns to step S12 described above and waits for notification of congestion and / or non-congestion in the next cycle. On the other hand, if the value count exceeds the upper limit C (if the number of consecutive periods of the congestion state “1” exceeds the predetermined number), the flow rate restriction reference setting unit 403 sets the smaller threshold R2 [u]. By comparing with the threshold lower limit L, it is determined whether or not there is room for reducing the threshold (step S15). If there is no room to decrease the threshold, the flow restriction reference setting unit 403 returns to step S12 described above and waits for notification of congestion and / or non-congestion in the next cycle. On the other hand, if there is room to reduce the threshold, the flow restriction reference setting unit 403 changes the first and second thresholds R1 [u] and R2 [u] to values smaller by M (step S16), the process returns to the above-described step S11.

  As described above, the first and second thresholds R1 [u] and R2 [u] are decreased by M every time the period of the congestion state continues C times, and the period of the non-congestion state is generated. Returns to the default state.

  In FIG. 5, the number of consecutive periods of the congestion state in which the first threshold value R1 [u] is decreased by a predetermined unit (M) and the second threshold value R2 [u] are decreased by a predetermined unit (M). The number of continuous periods of the congestion state to be performed is the same, but the number of continuous times may be different. In FIG. 5, the unit amount (M) for decreasing the first threshold value R1 [u] is the same as the unit amount for decreasing the second threshold value R2 [u]. It may be different.

  FIG. 6 is a flowchart showing a process (algorithm) for changing the priority for receiving the flow restriction when the threshold is exceeded. FIG. 6 shows processing for one contract user, and the processing shown in FIG. 6 is executed for each contract user.

  Starting from FIG. 6, the flow restriction reference setting unit 403 discards the frame when the first and second thresholds R1 [u] and R2 [u] of the contract user u are exceeded. As [u] and PRI2 [u], default values pri1 [u] and pri2 [u] relating to the contract user u are set, and a boundary value (1) smaller than the continuous number of times C of the congestion state in which the threshold value is changed. The value c is set in (representing parameter) (step S20). Here, the priority is 0 to 7, and the values pri1 [u] and pri2 [u] are values greater than 0 and less than 7, respectively. Further, there is a relationship of pri1 [u]> pri2 [u] between the values pri1 [u] and pri2 [u]. Since the frame that is discarded is larger when the large first threshold value R1 is exceeded, there is such a relationship.

  Thereafter, the flow restriction reference setting unit 403 monitors whether the continuous number of periods of the congestion state “1” exceeds the predetermined number C (steps S21 to S24). The process of monitoring whether the continuous number of periods of the congestion state “1” exceeds the predetermined number C is the same process as in FIG. 5 (see steps S11 to S14 in FIG. 5).

  When the number of continuous periods of the congestion state “1” exceeds the predetermined number (“YES” in step S24), the flow restriction reference setting unit 403 discards the frame related to the first threshold value R1 with the highest priority PRI1. It is determined whether or not [u] has reached the highest priority (7). If the highest priority has not been reached, the highest priority PRI1 [u] for discarding the frame is set to a priority higher by one. And if it has reached the highest priority, it is left as it is, and it is determined whether or not the highest priority PRI2 [u] for discarding the frame relating to the second threshold R2 has reached the highest priority (7), If the highest priority has not been reached, the highest priority PRI2 [u] for discarding the frame is changed to a priority higher by 1, and if the highest priority has been reached, it remains as it is (step S25). It returns to the step S21, which was mentioned.

  As described above, every time the congestion state cycle continues C times, the upper limit values PRI1 [u] and PRI2 [u] of the priority for receiving the flow restriction when the threshold value is exceeded are increased by one level, and the cycle of the non-congestion state is increased. If it happens, it will return to the default state.

  In FIG. 6, the number of consecutive periods of the congestion state in which the highest priority PRI1 [u] for discarding the frame related to the first threshold R1 is increased by one level, and the highest priority PRI2 [u for discarding the frame related to the second threshold R2 ] Is the same as the continuous number of periods of the congestion state that increases the level by one step, but these continuous numbers may be different. Further, in FIG. 6, the increment unit of the priority for raising the highest priority PRI1 [u] and PRI2 [u] for discarding the frame is not limited to 1, and differs depending on the parameters PRI1 [u] and PRI2 [u]. May be.

  FIG. 7B is an explanatory diagram showing the flow rate restriction when the flow rate restriction reference setting unit 403 performs the threshold value changing process shown in FIG. 5, and FIG. 7A is the same as FIG. (Drawing) is explanatory drawing which shows the mode of the flow volume restriction | limiting when not performing the change process of the threshold value shown in FIG.

  FIG. 7A shows a case where the flow rate is not limited unless the fixed first threshold value R1 is exceeded because only the high priority frame is used. In FIG. 7B, as a result of performing the processing (algorithm) shown in FIG. 5, the first threshold value R1 and the second threshold value R2 are changed to small values, and the same input flow rate as in FIG. 1 shows a case where a portion exceeding the threshold value R1 occurs and the flow rate is limited.

  By such a flow rate limitation, when the congestion state of the output buffer corresponding to the destination of the packet (flow) is resolved and the non-congestion state is notified, the first threshold value R1 and the second threshold value R2 are restored to the default values.

  FIG. 8B is an explanatory diagram showing the state of flow restriction when the flow restriction reference setting unit 403 performs priority changing processing for receiving flow restriction when the threshold is exceeded as shown in FIG. (Same drawing as FIG. 4 mentioned above) is explanatory drawing which shows the mode of the flow restriction | limiting when not performing the change process of the priority which receives a flow restriction | limiting at the time of exceeding the threshold value shown in FIG.

  As the priority, for example, a CoS value that is a priority in VLAN (IEEE 802.1Q Virtual Local Area Network) is used, or a ToS (Type of Service) value in an IP header in IPv4 (Internet Protocol Version 4) is used. It is determined by using the value of TC (Traffic Class) in the IP header in IPv6 (Internet Protocol Version 6). In the description of FIG. 8, each frame shows a case where a CoS value that is a priority in the VLAN is applied as a priority value. FIG. 8 shows a case where only a frame with CoS = 4 is input. Assume that the default priority for receiving a flow restriction when the threshold is exceeded is CoS = 6 or less for the first threshold R1, and CoS = 3 or less for the second threshold R2.

  In the case of FIG. 8A in which priority change processing for receiving flow rate restriction when the threshold value is exceeded is not executed, the input flow rate exceeds the second threshold value R2 because the priority of the input frame is CoS = 4. However, the flow rate is not limited.

  On the other hand, it is assumed that the priority is changed by the priority changing process in which the period of the congestion state continues and the flow rate is restricted when the threshold value is exceeded. For example, it is assumed that CoS = 7 or less with respect to the first threshold value R1, and CoS = 4 or less with respect to the second threshold value R2. As a result of this change, the frame with the priority CoS = 4 becomes a frame that is restricted when the input flow rate exceeds the second threshold R2, and is subjected to flow rate restriction as shown in FIG. 8B.

  By such a flow rate restriction, when the congestion state of the output buffer corresponding to the destination of the packet (flow) is resolved and a non-congestion state is notified, the priority of receiving the flow restriction when the threshold is exceeded returns to the default value.

  As described above, the flow rate restriction reference setting unit 403 may only change the threshold values R1 and R2 dynamically (see FIG. 5). (See FIG. 6). Further, both the dynamic change of the thresholds R1 and R2 and the dynamic change of the priority that receives the flow restriction when the threshold is exceeded are performed. It may be.

  Examples of the third setting method include the following three methods.

  First, change the thresholds R1 and R2 only until the threshold can no longer be reduced (see FIG. 5), and if the congestion continues, change the priority to receive flow restriction when the threshold is exceeded. You may make it start (refer FIG. 6). Conversely, until the priority for receiving the flow restriction when the threshold is exceeded cannot be increased any more, only the priority for receiving the flow restriction when the threshold is exceeded is changed, and if the congestion state continues, the thresholds R1 and R2 The change may be started.

  Second, when the congestion state continues and the flow restriction criterion needs to be changed for the first time (when the continuous number of periods of the congestion state becomes the predetermined number first), the threshold values R1 and R2 are changed. (Refer to Fig. 5) Next, when it is necessary to change the flow restriction standard, change the priority to receive the flow restriction when the threshold is exceeded (see Figure 6), and then change the flow restriction standard Is changed, the thresholds R1 and R2 are changed, and in the same manner, whenever the change of the flow restriction standard is required, the priority change for receiving the flow restriction when the threshold is exceeded, and the thresholds R1 and R1 are changed. The change of R2 may be executed alternately.

  Thirdly, whenever the congestion state continues and the change of the flow restriction criterion becomes necessary, the thresholds R1 and R2 may be changed and the priority for receiving the flow restriction when the threshold is exceeded may be changed.

(A-3) Effect of First Embodiment According to the first embodiment, the output interface unit monitors the congestion state of the output buffer of the packet switching unit, and notifies the input interface unit of the congestion state. Since the input interface unit restricts the flow bandwidth of each flow as necessary and outputs a frame, a plurality of flows from a plurality of input interface units are concentrated and output to one input / output interface unit. Even in such a case, it is possible to realize bandwidth guarantee and fairness among contracting users without generating packet discarding at the packet switching unit or output interface unit as much as possible.

  Further, according to the first embodiment, the bandwidth control information notified from the output interface unit side to the input interface unit side is the congestion and / or non-congestion state (“1” of the output buffer of the packet switching unit belonging to the output port). "Or" 0 "), the amount of transmission of bandwidth control information is very small. Control frames such as sending multiple frames together as dedicated frames and sending them in broadcast frames using dedicated ports of the packet switching unit The amount can be reduced. This is very effective when the bandwidth control information is transferred in the same in-channel as the user packet.

  Furthermore, according to the first embodiment, the bandwidth control information is as small as two values of congestion and / or non-congestion, and the processing method of the transmission limited bandwidth is simple, so hardware can be realized with a very small circuit scale. Is effective and the control cycle can be speeded up.

  Furthermore, according to the first embodiment, when congestion does not occur, even when any contract user occupies a large band, the flow rate is not statically restricted, and congestion occurs. However, all the contract users belonging to the output port are given a congestion instruction at the same time, but even if there are contract users with a small input bandwidth by providing a threshold for each contract user, the contract user who occupies a large bandwidth It is possible to achieve fairness because bandwidth control is performed between them.

  Further, according to the first embodiment, it is possible to quickly limit the contract user who occupies the bandwidth by increasing the monitoring period of the congestion state, and increase the number of thresholds. Therefore, detailed priority frame control is possible, and by ensuring that the total of arbitrary thresholds of all contracted users is less than or equal to the output possible bandwidth of the output port, it is possible to secure a guaranteed bandwidth for frames with priority higher than the arbitrary threshold. Is possible.

  Furthermore, according to the first embodiment, when the period of the congestion state continues, the reference of the flow rate restriction is changed, so that the congestion state can be prevented from continuing for a long time.

(B) Second Embodiment Next, a second embodiment of the packet switching apparatus, the packet switching method, and the bandwidth control program according to the present invention will be briefly described with a focus on differences from the first embodiment.

FIG. 9 is a block diagram illustrating a functional configuration of the packet switching apparatus 1A according to the second embodiment, and corresponds to FIG. 2 used in the description of the packet switching apparatus 1 according to the first embodiment. In FIG.
In the first embodiment, the congestion state information of the output buffers 302-0 to 302-X of the packet switching unit 3 is transferred in the same in-channel as the user packet. However, since the information amount of this information is binary (one bit can be applied), each output interface unit 200 provides a separate control line to each input interface unit to transfer information. It is also possible to do.

  The packet switching apparatus 1A according to the second embodiment transmits the congestion and / or non-congestion state of the output buffers 302-2 and 302-3 of the packet switching unit 3 using a level signal indicated by “1” or “0”. It is configured.

In the second embodiment, what is transferred in the same in-channel as the user packet can be easily configured by another signal line. Therefore, in the case of in-channel, it is necessary to transfer the packet in the user packet. There is an effect that the band compression of the user packet generated by the in-channel method is completely eliminated. Also, in the congestion monitoring period, control packetization or the like is unnecessary, and the speed can be made higher than that of the first embodiment. Also, by not using in-channel, it exists on the input interface unit 100 side. Further, the control packet receiving unit 401, the packet multiplexing function unit in the transmission control unit 104, the packet distribution unit 202 existing on the output interface unit 200 side, the control packet transmission unit 412, and the like are not required. FIG. 9 shows a case where a plurality of output ports are provided instead of the single output port of FIG. 2 for explaining the above-described operation example. However, even if the number of output ports increases, the circuit scale does not increase as the types of the congestion instruction unit 402 and the flow rate restriction reference setting unit 403 increase. Not causing an increase in circuit scale in proportion to the betting amount, effect so that there is no need to use it a buffer provided in the flow restriction portion.

(C) Other Embodiments In the description of the above-described embodiment, various modified embodiments have been referred to. However, modified embodiments as exemplified below can be cited.

  In the embodiment described above, the congestion state generation unit is provided in the output 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 (presence / absence of congestion state), the congestion state generation unit is not related to the output interface unit but to each output buffer of the packet switching unit. It may be provided. Further, for example, the congestion state generation unit may be provided on a dedicated board instead of the output interface unit or the packet switching unit.

  In the above embodiment, the flow and the contract user correspond to each other on a one-to-one basis. However, the present invention is not limited to this. For example, a plurality of flows may be set for one contract user.

  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. Of course, the number of thresholds and the number of priority levels are not limited to the above-described numbers.

  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 control packet for notifying the congestion and / or the non-congestion state is regularly transmitted. However, the present invention is not limited to this notification method. For example, even if the congestion state is regularly monitored, the notification is periodically performed during a period from when the congestion state is once detected until the predetermined time elapses after the congestion state is resolved. You may do it.

  Although the case where the number of threshold values is the same for all contract users (flows) has been described in the above embodiment, the number of threshold values related to flow rate control may differ depending on the contract user. For example, a contract user with a large contract bandwidth may have a larger number of thresholds than other contract users.

  In the above embodiment, when the non-congestion state occurs even in one cycle when the congestion state is continuous, the threshold value etc. is immediately returned to the default state. Regarding the period, the condition may be that two or more periods are continuous.

1, 1A ... packet switching device, 2-0 to 2-X ... input / output interface unit,
100: Input interface section,
DESCRIPTION OF SYMBOLS 101 ... Packet receiving part, 102 ... Flow identification part, 103 ... Flow restriction part, 104 ... Transmission control part, 401 ... Control packet receiving part, 402 ... Congestion instruction part, 403 ... Flow restriction reference setting part,
200 ... output interface part,
201: Reception control unit, 202 ... Packet distribution unit, 203 ... Packet transmission unit, 411 ... Congestion state generation unit, 412 ... Control packet transmission unit,
3 ... Packet switching part,
300-0 to 300-X ... input buffer, 301 ... packet switch, 302-0 to 302-X ... output buffer.

Claims (7)

  1. 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 flow identifier for identifying the flow of the input packet;
    The flow restriction is performed for each flow, and the flow restriction is performed on the condition that the output buffer that is scheduled to buffer packets related to the flow is in a congested state and that the input flow rate exceeds the threshold value. A flow restriction unit;
    A congestion indication unit that sets a state of the output buffer in the flow rate limiting unit in response to notification of congestion and / or non-congestion state of the output buffer that is scheduled to buffer packets related to the flow,
    In relation to each output interface means above,
    The state of the output buffer corresponding to the output interface means is periodically monitored, and the congestion and / or non-congestion state of the output buffer is notified to each input interface means of the packet source buffered by the output buffer. A packet switching device characterized in that a state notification unit is provided.
  2.   The flow rate limiting unit applies a plurality of thresholds for limiting the flow rate for each flow, and the higher the input flow rate exceeds the higher threshold value, the higher the priority the packet is the target of the flow rate limitation. The packet switching device described in 1.
  3.   2. A flow rate restriction reference setting unit that changes a flow restriction reference so as to be strict according to a continuous period of congestion of the output buffer that is scheduled to buffer packets related to a flow. 3. The packet switching device according to 2.
  4.   4. The packet switching apparatus according to claim 3, wherein the flow rate restriction reference setting unit decreases the threshold as the continuous period of the congestion state of the output buffer becomes longer.
  5.   The flow rate restriction reference setting unit increases the priority of a packet whose flow rate is restricted when the threshold value is exceeded as the continuous period of the congestion state of the output buffer becomes longer. 5. The packet switching device according to 4.
  6. 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 flow identifier for identifying the flow of the input packet;
    The flow restriction is performed for each flow, and the flow restriction is performed on the condition that the output buffer that is scheduled to buffer packets related to the flow is in a congested state and that the input flow rate exceeds the threshold value. A flow restriction unit;
    A congestion instruction unit for receiving a notification of congestion and / or a non-congestion state of the output buffer scheduled to buffer packets related to a flow, and setting the state of the output buffer in the flow rate limiting unit;
    As a state notification unit for periodically monitoring the state of the output buffer and notifying the input interface means of the source of the packet buffered by the output buffer of the congestion and / or non-congestion state of the output buffer. A bandwidth control program characterized by functioning.
  7. 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,
    The flow identification unit provided in each of the input interface means identifies the flow of the input packet,
    The flow rate limiting unit provided in each input interface means the flow on condition that the output buffer that is scheduled to buffer packets related to the flow is in a congested state and that the input flow rate exceeds a threshold value. Limit the flow rate every time,
    The congestion instruction unit provided in each of the input interface means receives the notification of the congestion and / or the non-congestion state of the output buffer that is scheduled to buffer the packet related to the flow, and sets the state of the output buffer to the flow restriction unit. Set,
    The status notification unit provided in association with each output interface means periodically monitors the status of the output buffer corresponding to the output interface means, and indicates whether the output buffer is congested and / or uncongested. A packet switching method comprising: notifying each input interface means of a transmission source of a packet to be buffered by a buffer.
JP2013178526A 2013-08-29 2013-08-29 Packet switch, packet switching method and band control program Pending JP2015050479A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002261766A (en) * 2001-02-28 2002-09-13 Matsushita Electric Ind Co Ltd Convergence control method and apparatus
JP2007166421A (en) * 2005-12-15 2007-06-28 Mitsubishi Electric Corp Packet processing apparatus
JP2007258787A (en) * 2006-03-20 2007-10-04 Fujitsu Ltd Flow control method and flow controller

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002261766A (en) * 2001-02-28 2002-09-13 Matsushita Electric Ind Co Ltd Convergence control method and apparatus
JP2007166421A (en) * 2005-12-15 2007-06-28 Mitsubishi Electric Corp Packet processing apparatus
JP2007258787A (en) * 2006-03-20 2007-10-04 Fujitsu Ltd Flow control method and flow controller

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