JP4087279B2 - BAND CONTROL METHOD AND BAND CONTROL DEVICE THEREOF - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bandwidth control method for transmitting a traffic flow by performing predetermined bandwidth control, and a bandwidth control apparatus thereof.
[0002]
[Prior art]
In recent years, in connection services for communication networks, high-speed connection services can be provided at low cost due to the widespread use of FTTH (Fiber To The Home). Data traffic flowing through such a communication network needs to be subjected to QoS (communication quality) control according to the application used.
[0003]
As a technical method for performing this QoS control, a scheduling method using a different queue for each output port, a policing method for limiting the maximum flow rate of traffic, and the like are used. When these methods are used, priority is given to VoIP (Voice over IP) traffic for passing voice packets over a communication network to the application, for example, voice communication over a communication network with lower delay than other data traffic. In some cases, it is desired to limit the total amount of traffic to a certain user to 10 Mbps, which is a contract bandwidth.
[0004]
For example, in order to control the delay time, a method can be used in which different transmission queues are prepared for VoIP traffic, and VoIP packets are always transmitted before other data queues. However, this approach cannot meet the requirement to limit the total amount of transmission traffic to the user.
[0005]
Therefore, it is conceivable to limit the traffic volume of the user by using a policing technique that is a bandwidth limiting mechanism, but in this case, the priority of traffic is not considered in the policing algorithm, so if the total traffic limit is exceeded, A situation occurs in which priority traffic such as VoIP is discarded.
[0006]
As a method of solving such a situation, there has been a method of performing scheduling for controlling the total amount of transmission rates from these transmission queues while using a plurality of transmission queues.
[0007]
[Patent Document 1]
JP 2001-519120 A (FIG. 1)
[0008]
[Problems to be solved by the invention]
However, the above-described conventional example has a problem that the processing becomes complicated, especially when the number of users is large, and it is difficult to realize it on a high-speed network. Further, in Patent Document 1, there is a problem that implementation is complicated because multi-stage scheduling is performed.
[0009]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a bandwidth control method and a bandwidth control device thereof that can easily realize user traffic priority control and bandwidth control at low cost.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the bandwidth control method according to claim 1, in the bandwidth control method for transmitting input data by performing predetermined bandwidth control, at least two predetermined in the predetermined bandwidth are transmitted. The first control step of guaranteeing the bandwidth of the input data based on a threshold and limiting the flow rate of the traffic of the input data is different from the data limited in the flow rate based on the policy condition of the data. There is provided a bandwidth control method including a storage control step of storing in a transmission queue, and a second control step of controlling a delay in traffic of the data using a plurality of the transmission queues.
[0011]
According to the present invention, for example, a plurality of threshold values are set based on the priority of the packet to guarantee the bandwidth of the input packet, and the bandwidth-guaranteed packet is different based on the policy condition such as the traffic class of the packet. By storing in a transmission queue and then performing scheduling for controlling traffic delay, user traffic priority control and bandwidth control are realized.
[0012]
Further, in the bandwidth control device according to claim 2, in the bandwidth control device that transmits the traffic amount of the input data by performing bandwidth control, at least two threshold values are set within the predetermined bandwidth to be controlled, and based on the threshold values. A first control unit that guarantees a bandwidth of the input data and limits a flow rate of the traffic of the data, and at least two transmission queues, and the flow rate is limited based on a policy condition of the data A bandwidth control device comprising: storage control means for storing data in the transmission queue; and second control means for controlling a delay in traffic of the data stored in the plurality of transmission queues. Provided.
[0013]
According to the present invention, a plurality of threshold values are set within a predetermined bandwidth to be controlled, the bandwidth of the packet input is guaranteed by the first control means, and the flow rate is controlled by the storage control means based on the traffic class of the packet. By implementing means for storing the received packets in the transmission queue and scheduling for controlling the packet delay, the user traffic priority control and bandwidth control are realized.
[0014]
In the bandwidth control device according to a third aspect, the first control means sets a threshold value according to the priority of the data.
[0015]
According to the present invention, for example, a plurality of priorities are set according to packet priorities, and packets of traffic classes that require low-delay communication are preferentially transmitted to guarantee bandwidth of incoming packets.
[0016]
Further, in the bandwidth control device according to claim 4, the storage control means stores the flow-limited data in a corresponding transmission queue based on a traffic class of data of a packet configuration as the policy condition. And
[0017]
According to the present invention, for example, policing is performed so that a conforming packet of a traffic class that requires low-latency communication such as VoIP is stored in a preferentially served transmission queue.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of a bandwidth control method and bandwidth control apparatus according to the present invention will be described below with reference to the accompanying drawings of FIGS.
[0019]
(Embodiment 1)
FIG. 1 is a block diagram showing an example of the configuration of the bandwidth control apparatus according to the present invention. In FIG. 1, a router 10 serving as a bandwidth control device includes a plurality of input side NPs (network processors) 11 to 13 that are provided for each input port (three input ports in this embodiment) and perform policing control. A switch fabric 21 that distributes the assigned packets to appropriate output ports, and output NPs 31 to 33 that are provided for each output port (three output ports in this embodiment) and perform bandwidth control on the distributed packets. Has been.
[0020]
The input side NPs 11 to 13 perform policing control on input packets. The input side NPs 11 to 13 have the same configuration, and the configuration of the input side NP 11 is representatively shown in the configuration diagram of FIG.
[0021]
In FIG. 2, the input NP 11 includes a classifier 14, a policer 15 with priority, a policy action processing unit 16, a QoS policy control unit 17, and an action table 18. In the input side NP11, the classifier 14 uses, for example, CAM (Contents Addressable Memory), etc., and classifies traffic into traffic classes such as VoIP and data based on the header information of the input packet. Is added to the internal header portion (see FIG. 1) and output to the policer 15 with priority together with the packet.
[0022]
The prioritized policer 15 considers the priority of the input traffic and limits the bandwidth so that the total number of conforming packets of each traffic class falls within the set 10 Mbps bandwidth. Specifically, the prioritized policer 15 is set so that the VoIP traffic is preferentially determined to be more suitable than the data traffic when determining whether the traffic flow rate conforms to the limited bandwidth. . The conformance / nonconformity information determined by this policer is added to the internal header portion and output to the policy action processing portion 16 together with the packet.
[0023]
Here, for example, a token bucket is used as an policing algorithm which is a feature of the present invention. In this token bucket algorithm, a virtual quantity representing a traffic transmission right called a token is used. That is, in the policer 15 with priority, as shown in FIG. 3, a virtual token bucket 15a for storing this token is prepared for the traffic flow whose flow rate is to be limited, and this token bucket 15a Tokens are replenished at a rate equal to the traffic flow limit.
[0024]
In the prioritized policer 15, a threshold is set for the amount of talk accumulated in the token bucket 15a according to the priority of the packet, and for tokens with low priority, there is no token exceeding a certain level in the token bucket 15a. In this case, even if a token remains, the packet processing unit 15b performs the same processing as when there is no token. Here, if there are not enough tokens in the token bucket 15a, the traffic flow is limited by performing processing such as discarding or delaying the traffic.
[0025]
The packet processing unit 15b transmits a packet after taking out from the token bucket 15a a token proportional to the amount of data when the packet arrives. That is, in this embodiment, threshold values T1 and T2 are set in advance for the amount of tokens in the token bucket 15a, and when a packet of low priority traffic arrives, the packet processing unit 15b Then, a token proportional to the data amount is taken out from the token bucket 15a and transmitted, and if there is no token equal to or greater than T2, the packet is discarded. Further, when a packet of high priority traffic arrives, the packet processing unit 15b, when there is a token of T1 or more, extracts a token proportional to the data amount from the token bucket 15a and transmits the packet. If there is no token, the packet is discarded. The threshold value Ti (Ti is an index representing a traffic class) according to the present invention can be set to three or more according to the priority. If Ti <Tj, traffic class i Can use the bandwidth preferentially over the traffic class j.
[0026]
As a result, in this embodiment, even during congestion when the amount of transmitted traffic is larger than the restricted bandwidth, the highest priority traffic uses the bandwidth first, and the remaining bandwidth is used by the next highest priority traffic. Bandwidth control is realized.
[0027]
The policy action processing unit 16 extracts the traffic class and policer determination result of the input packet, searches the action table 18 based on the information, and determines the processing for the input packet. For example, the policy action processing unit 16 inputs a packet to a preferentially serviced queue (for example, the transmission queue 22) for a conforming packet of a traffic class that requires low-latency communication, and low-latency communication. This packet is discarded for a non-conforming packet of a traffic class that is not necessary.
[0028]
Further, the QoS policy control unit 17 performs a writing process for writing the required QoS policy into the action table 18, and this QoS policy may be directly designated by the administrator of the apparatus, or may be an RSVP. It may be determined by a signaling protocol such as (Resource Reservation Protocol).
[0029]
As shown in FIG. 2, the action table 18 is written with a traffic class, a policer determination result of the traffic class, and action data corresponding thereto.
[0030]
The switch fabric 21 includes transmission queues 22 and 23 that preferentially store conforming packets of a traffic class that requires low-latency communication, and a scheduler 24 that selects these transmission queues 22 and 23 to extract and transmit the packets. ing. The scheduler 24 extracts packets from the selected transmission queues at timings corresponding to the respective transmission priorities, and outputs the packets to the output side NPs 31 to 33 provided for each output port. As long as there is a packet in the priority queue, the scheduler 24 always attaches a strict priority to be transmitted first, a weighted round robin to transmit the packet at a rate corresponding to the weight of each queue, or a virtual time stamp to the packet. Therefore, existing techniques such as WFQ (Weighted Fair Queuing) for determining a transmission packet can be used in accordance with the application.
[0031]
The output side NPs 31 to 33 perform bandwidth control again on the IP packet input from the switch fabric 21 as necessary, and transfer the packet to the network.
[0032]
Next, processing operations of the prioritized policer 15 and the policy action processing unit 16 will be described based on the flowcharts of FIGS. First, in FIG. 4, the prioritized policer 15 determines whether or not t−t0 = 1 / Ri is satisfied (step 101). Note that t is the current time, t0 is the time when the token was replenished last time, and Ri is the contracted bandwidth of the user i.
[0033]
Here, in the case of t−t0 = 1 / Ri, after t0 = t (step 102), it is determined whether the token bucket remaining amount B is less than the maximum capacity BMAX of the token bucket (step 103), and this maximum If it is less than the capacity BMAX, the token remaining amount B is increased by one (step 104). Next, it is determined whether or not the packet has arrived (step 105). Also, if t−t0 = 1 / Ri is not true, the process proceeds to step 103.
[0034]
Here, when the packet has not arrived, the process returns to step 101 to determine t−t0 = 1 / Ri. If the packet arrives, the packet size is set to L and the priority is set to p (step 106). Next, it is determined whether (token bucket remaining amount B)> (threshold p of priority p) (step p). 107), if (token bucket remaining amount B)> (priority p threshold Tp), that is, if the token bucket remaining amount B is equal to or smaller than the priority p threshold Tp, the packet is discarded ( Step 109) and return to Step 101. If (token bucket remaining amount B)> (threshold p of priority p), it is determined whether (token bucket remaining amount B)> (size L) (step 108).
[0035]
Here, if (token bucket remaining amount B) ≧ (size L) is not satisfied, that is, if the token bucket remaining amount B is smaller than size L, the packet is discarded (step 109), and (token bucket remaining amount B). If ≧ (size L), a value obtained by subtracting the packet size L from the token bucket remaining amount B is set as the token bucket remaining amount B, then packet transmission is performed (step 110), and the process returns to step 101.
[0036]
In FIG. 5, when the packet transmitted from the policer 15 with priority arrives (step 201), the policy action processing unit 16 extracts the traffic class and the policer determination result from the internal header attached to the packet, and displays the action table. Search (step 202). Then, it is determined whether or not the action of the corresponding item is discard (step 203).
[0037]
If the action of the corresponding item in the retrieved action table is discard, the packet is discarded (step 204). If the action of the corresponding item is input to the priority queue, after storing the packet in the designated transmission queue 22 or 23 (step 205), the process returns to step 201 to wait for the next packet arrival.
[0038]
As described above, in this embodiment, the policer 15 with priority performs band control according to the priority of the packet, and the policy action processing unit 16 discards / transmits the packet from the packet traffic class and the policer determination result. Since scheduling is performed after the packet is input to the appropriate transmission queue after determination, the device configuration is simplified, and accordingly, user traffic priority control and bandwidth control can be easily realized at low cost.
[0039]
(Embodiment 2)
In the second embodiment, a case where a color-aware mode (Color Aware Mode) is used will be described. FIG. 6 is a block diagram showing another example of the configuration of the policer shown in FIG. In FIG. 6, in the policer 15, the color corresponding to the priority (green and yellow) is set in the internal header portion as the traffic class of the packet. Corresponding to this color, a virtual token bucket 15c for collecting green tokens and a virtual token bucket 15d for collecting green and yellow tokens are prepared. Buckets 15c and 15d are replenished with tokens at a rate equal to the traffic flow limit. When the token of green is filled in the token bucket 15c, the token bucket 15d is replenished.
[0040]
For example, when a green packet arrives, the packet processing unit 15e extracts a token proportional to the amount of data from the token bucket 15c and then transmits the green packet. If there is no token in the token bucket 15c, After taking out the token from the bucket 15d, the traffic class of the packet is changed to yellow and transmitted. If there is no token in the token bucket 15d, the packet processing unit 15e discards the packet.
[0041]
Further, for example, when a yellow packet arrives, the packet processing unit 15e extracts a token proportional to the data amount from the token bucket 15d, and then transmits a yellow packet. When there is no yellow token in the token bucket 15d The packet is discarded.
[0042]
The policy action processing unit 16 extracts the traffic class (green and yellow) of the input packet and the policer determination result, searches the action table 18 based on these information, and determines the processing for the input packet. For example, the policy action processing unit 16 causes a packet that conforms to a traffic class (green) that requires low-latency communication to be input to a preferentially serviced queue (for example, to the transmission queue 22), and For a non-conforming packet of a traffic class that does not require low-latency communication, this packet is discarded.
[0043]
As described above, in this embodiment, the policer 15 performs bandwidth control according to the color, and the policy action processing unit 16 determines the conformity / nonconformity of the packet from the packet color and the policer determination result, thereby determining the packet packet. Since scheduling is performed after policing for determining transmission or discard, the device configuration is simplified, and accordingly, user traffic priority control and bandwidth control can be easily realized at low cost.
[0044]
The present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.
[0045]
【The invention's effect】
As described above, according to the present invention, by using a policer with priority and a policer that supports color-aware mode, a plurality of thresholds are set based on a traffic class to guarantee the bandwidth of an input packet. Since the packet is scheduled after the bandwidth guaranteed packet is stored in a different transmission queue based on the traffic class, the configuration is simplified and the traffic priority control and bandwidth control of the user is easy at low cost. Can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of a configuration of a bandwidth control device according to the present invention.
2 is a configuration diagram illustrating an example of a configuration of an input side NP and a switch fabric illustrated in FIG. 1. FIG.
FIG. 3 is a configuration diagram showing an example of a configuration of a prioritized policer shown in FIG. 2;
4 is a flowchart for explaining a processing operation of the policer shown in FIG. 3; FIG.
FIG. 5 is a flowchart for explaining the processing operation of the policy action processing unit shown in FIG. 2;
6 is a configuration diagram showing another example of the configuration of the policer shown in FIG. 2. FIG.
[Explanation of symbols]
10 Router 11-13 Input side NP
14 Classifier 15 Prioritized policers 15a, 15c, 15d Token bucket 15b, 15e Packet processing unit 16 Policy action processing unit 17 QoS policy control unit 18 Action table 21 Switch fabric 22, 23 Transmission queue 24 Scheduler 31-33 Output side NP
B Token bucket remaining amount L Packet size p Priority T1, T2, Ti, Tj, Tp Threshold

Claims (3)

In a bandwidth control method for transmitting input data by performing predetermined bandwidth control,
A first control step of determining the priority of the data;
Within the predetermined band, at least two threshold values predetermined for the token bucket are provided according to the priority of the data, and based on the priority of the data, the threshold corresponding to the priority, and the token amount When the token amount is less than the threshold corresponding to the priority, the bandwidth of the input data is guaranteed and the traffic flow of the input data is limited so that the data is discarded. A second control step;
A storage control step of storing the data limited in the flow rate in a different transmission queue based on the policy condition of the data;
A third control step of controlling a delay in the traffic of the data using a plurality of the transmission queues;
A band control method comprising: In a bandwidth control device that controls the amount of traffic of input data and transmits it,
Within the predetermined bandwidth to be controlled , at least two threshold values set in advance in the token bucket are set according to the priority of the data, the priority of the data, the threshold according to the priority, and the token amount, If the token amount is less than the threshold corresponding to the priority , the bandwidth of the input data is guaranteed and the traffic flow of the data is limited so that the data is discarded. First control means;
Storage control means for storing at least two transmission queues, and storing the flow-limited data in the transmission queue based on a policy condition of the data;
Second control means for controlling a delay in traffic of the data stored in the plurality of transmission queues;
A bandwidth control device comprising:   3. The bandwidth control apparatus according to claim 2, wherein the storage control unit stores the flow-limited data in a corresponding transmission queue based on a traffic class of packet-structured data as the policy condition.

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