JP2004320380A - Band control method and its band controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily achieve the traffic priority control of a user and the band control at a low cost. <P>SOLUTION: A classifier 14 classifies packets into VoIP and data. A policer 15 with priority makes the traffic band limitation, taking the priority of the input traffic into consideration. A policy action processor 16 inputs conformed packets of a traffic class needing a low-delay communication to transmission queues 22, 23 to be preferentially serviced, based on the traffic class of the inputted packets and the policer decision result, thus enabling a scheduler 24 to send the packets. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a band control method for performing predetermined band control on a traffic flow and transmitting the traffic flow, and a band control device therefor.
[0002]
[Prior art]
In recent years, in connection services of communication networks, high-speed connection services can be provided at low cost due to the spread of FTTH (Fiber To The Home). For data traffic flowing through such a communication network, it is necessary to perform QoS (communication quality) control according to the application to be used.
[0003]
As a technique for performing the QoS control, a scheduling technique using a different queue for each output port, a policing technique for limiting a maximum traffic flow rate, and the like are used. In the case of using these techniques, the traffic transmitted to a certain user is given priority to the application, for example, VoIP (Voice over IP) traffic for passing voice packets over a communication network with lower delay than other data traffic. For example, there is a case where it is desired to limit the total amount of traffic to a certain user to 10 Mbps which is the contracted bandwidth, for example, by transmitting the data in a targeted manner.
[0004]
For example, in order to control the delay time, it is possible to use a method of preparing different transmission queues for VoIP traffic and transmitting VoIP packets always 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 amount of traffic of the user by using a policing method which is a band limiting mechanism.In this case, however, the policing algorithm does not consider the priority of the traffic. 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 using a plurality of transmission queues and performing scheduling for controlling the total amount of transmission rates from the transmission queues.
[0007]
[Patent Document 1]
JP 2001-519120 A (FIG. 1)
[0008]
[Problems to be solved by the invention]
However, in the above-mentioned conventional example, there is a problem that complicated processing is required particularly when the number of users is large, and it is difficult to realize the processing on a high-speed network. Further, in Patent Literature 1, there is a problem that implementation is complicated because of performing multi-stage scheduling.
[0009]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a band control method and a band control device capable of easily realizing user traffic priority control and band control at low cost.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the band control method according to claim 1, in a band control method for transmitting input data by performing a predetermined band control, at least two predetermined bands are set within the predetermined band. A first control step of guaranteeing a bandwidth of the input data based on a threshold to limit a flow rate of the traffic of the input data, and differentiating the data whose flow rate is limited based on a policy condition of the data. A bandwidth control method is provided, comprising: a storage control step of storing data in a transmission queue; and a second control step of controlling delay of the data traffic using a plurality of the transmission queues.
[0011]
According to the present invention, for example, a plurality of thresholds are set based on the priority of a packet, the bandwidth of an input packet is guaranteed, and a packet whose bandwidth is guaranteed is different based on a policy condition such as a traffic class of the packet. By storing the information in a transmission queue and then performing scheduling for controlling the traffic delay, the traffic priority control and the bandwidth control of the user are realized.
[0012]
Further, in the band control device according to claim 2, in the band control device that performs band control on the traffic amount of input data and transmits the same, at least two thresholds are set within the predetermined band to be controlled, and based on the thresholds, Having first control means for guaranteeing a bandwidth of the input data and restricting a flow rate of the traffic of the data, and at least two transmission queues, wherein the flow rate is restricted based on a policy condition of the data. A band control device comprising: storage control means for storing data in the transmission queue; and second control means for controlling a delay of traffic of the data stored in the plurality of transmission queues. Provided.
[0013]
According to the present invention, a plurality of thresholds are set within a predetermined band to be controlled, the bandwidth of the input packet is guaranteed by the first control unit, and the flow rate is controlled by the storage control unit based on the traffic class of the packet. By performing means for storing the received packet in the transmission queue and scheduling for controlling the packet delay, traffic priority control and bandwidth control of the user are realized.
[0014]
Further, in the bandwidth control device according to claim 3, the first control means sets a threshold value according to a priority of the data.
[0015]
According to the present invention, for example, a plurality of priorities are set in accordance with the priorities of the packets, packets of a traffic class requiring low-delay communication are preferentially transmitted, and the bandwidth of input packets is guaranteed.
[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 as the policy condition based on a traffic class of data in a packet configuration. And
[0017]
According to the present invention, for example, policing is performed so that a conforming packet of a traffic class requiring low-delay communication such as VoIP is stored in a transmission queue that is preferentially served.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a band control method and a band control device according to the present invention will be described with reference to the accompanying drawings of FIGS.
[0019]
(Embodiment 1)
FIG. 1 is a configuration diagram illustrating an example of a configuration of a band control device according to the present invention. In FIG. 1, a router 10, which is a band control device, includes a plurality of input side NPs (network processors) 11 to 13 which are provided for each input port (three input ports in this embodiment) and perform policing control. Switch fabric 21 for distributing the allocated packets to appropriate output ports, and output side NPs 31 to 33 provided for each output port (three output ports in this embodiment) and performing band control on the distributed packets. Have been.
[0020]
The input side NPs 11 to 13 perform policing control on an input packet. The input sides NP11 to NP13 have the same configuration, and the configuration of the input side NP11 is representatively shown in the configuration diagram of FIG.
[0021]
In FIG. 2, the input side NP 11 includes a classifier 14, a policer 15 with a priority, a policy action processing unit 16, a QoS policy control unit 17, and an action table 18. In the input side NP 11, the classifier 14 uses, for example, a CAM (Contents Addressable Memory), and classifies traffic into a traffic class such as VoIP and data based on header information of an input packet. Is added to the internal header section (see FIG. 1) and output to the priority-added policer 15 together with the packet.
[0022]
The priority policer 15 limits the bandwidth in consideration of the priority of the input traffic so that the total number of conforming packets of each traffic class falls within the set 10 Mbps bandwidth. Specifically, the priority policer 15 is set to determine that the VoIP traffic conforms with a higher priority than the data traffic when determining whether the traffic flow conforms to the limited bandwidth. . The conformance / nonconformity information determined by this policer is added to the internal header and output to the policy action processing unit 16 together with the packet.
[0023]
Here, for example, a token bucket is used as an algorithm for performing policing, which is a feature of the present invention. This token bucket algorithm uses a virtual quantity called a token, which represents a traffic transmission right. That is, in the policer 15 with priority, as shown in FIG. 3, a virtual token bucket 15a for storing the token is prepared for the traffic flow whose flow rate is to be restricted, and the token bucket 15a is provided in the token bucket 15a. Tokens are replenished at a rate equal to the traffic limit.
[0024]
In the priority policer 15, a threshold is set for the amount of talk accumulated in the token bucket 15a in accordance with the priority of the packet. For low priority traffic, the token bucket 15a does not have a certain number of tokens or more. 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 is discarded or delayed so that the traffic flow is restricted.
[0025]
When the packet arrives, the packet processing unit 15b extracts a token proportional to the data amount from the token bucket 15a, and then transmits the packet. That is, in this embodiment, the thresholds T1 and T2 are set in advance for the amount of tokens in the token bucket 15a. When a packet of low-priority traffic arrives, the packet processing unit 15b determines whether there is a token of T2 or more. Then, a token proportional to the data amount is taken out from the token bucket 15a, and the packet is transmitted. If there is no token longer than T2, the packet is discarded. When a packet of high-priority traffic arrives, the packet processing unit 15b extracts a token proportional to the data amount from the token bucket 15a and transmits the packet if there is a token equal to or greater than T1. 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 in accordance with the priority, and if Ti <Tj, the traffic class i Can use the band more preferentially than the traffic class j.
[0026]
Thus, in this embodiment, even during congestion where the amount of transmission traffic is larger than the limited bandwidth, the highest priority traffic uses the bandwidth first, and the remaining bandwidth uses the next highest priority traffic. Bandwidth control is realized.
[0027]
The policy action processing unit 16 extracts a traffic class and a policer determination result of an input packet, searches the action table 18 based on the extracted information, and determines a process for the input packet. For example, the policy action processing unit 16 causes a packet to be input to a queue (e.g., the transmission queue 22) that is preferentially serviced with respect to a conforming packet of a traffic class that requires low-delay communication. If the packet does not conform to the unnecessary traffic class, the packet is discarded.
[0028]
In addition, the QoS policy control unit 17 performs a write process of writing the required QoS policy into the action table 18, and this QoS policy may be directly specified by the device administrator, or may be RSVP. (Resource Reservation Protocol).
[0029]
As shown in FIG. 2, the action table 18 has written therein a traffic class, a policer determination result of the traffic class, and action data corresponding to the traffic class.
[0030]
The switch fabric 21 is composed of transmission queues 22 and 23 for preferentially storing conforming packets of a traffic class requiring low-delay communication, and a scheduler 24 for selecting the transmission queues 22 and 23, extracting the packets, and transmitting the packets. ing. The scheduler 24 extracts a packet from each of the selected transmission queues at a timing according to the respective transmission priority, and outputs the packet to the output side NPs 31 to 33 provided for each output port. Note that the scheduler 24 always assigns a strict priority to transmit packets first, a weighted round-robin to transmit packets at a rate corresponding to the weight of each queue, or attaches a virtual time stamp to packets as long as the packets are in the priority queue. By performing such sorting, an existing technique such as WFQ (Weighted Fair Queuing) for determining a transmission packet can be used according to 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, the processing operations of the priority-added policer 15 and the policy action processing unit 16 will be described based on the flowcharts of FIGS. First, in FIG. 4, the priority-added policer 15 determines whether or not t−t0 = 1 / Ri (step 101). Here, t is the current time, t0 is the time at which the token was replenished last time, and Ri indicates the contracted bandwidth of the user i.
[0033]
Here, in the case of t−t0 = 1 / Ri, after setting t0 = t (step 102), it is determined whether the remaining amount B of the token bucket is less than the maximum capacity BMAX of the token bucket (step 103). If the capacity is less than 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 satisfied, the process proceeds to step 103.
[0034]
If the packet has not arrived, the process returns to step 101 to determine tt0 = 1 / Ri. When the packet arrives, the packet size is set to L and the priority is set to p (step 106), and then it is determined whether (token bucket remaining amount B)> (threshold Tp of priority p) (step 106). 107), if (token bucket remaining amount B)> (threshold Tp of priority p), that is, if token bucket remaining amount B is equal to or smaller than threshold Tp of priority p, the packet is discarded ( Step 109), and return to step 101. If (token bucket remaining amount B)> (threshold Tp 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), that is, if 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, and then the packet is transmitted (step 110), and the process returns to step 101.
[0036]
In FIG. 5, when a packet transmitted from the priority-added policer 15 arrives (step 201), the policy action processing unit 16 extracts a traffic class and a policer judgment result from an internal header attached to the packet, and stores an action table. Search (step 202). Then, it is determined whether the action of the corresponding item is discard (step 203).
[0037]
Here, if the action of the corresponding item in the searched action table is discard, the packet is discarded (step 204). If the action of the corresponding item is input to the priority queue, the packet is stored in the designated transmission queue 22 or 23 (step 205), and the process returns to step 201 and waits for the arrival of the next packet.
[0038]
As described above, in this embodiment, the priority-controlled policer 15 performs bandwidth control according to the priority of the packet, and the policy action processing unit 16 discards / transmits the packet based on the traffic class of the packet and the result of the policer determination. Since the scheduling is performed after the packet is determined and input to the appropriate transmission queue, the device configuration is simplified, and accordingly, the traffic priority control and the bandwidth control of the user 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 configuration diagram showing another example of the configuration of the policer shown in FIG. In FIG. 6, in the policer 15, a color (green and yellow) corresponding to the priority is set in the internal header as the traffic class of the packet. In correspondence with this color, a virtual token bucket 15c for storing green tokens and a virtual token bucket 15d for storing green and yellow tokens are prepared. The buckets 15c and 15d are replenished with tokens at a rate equal to the traffic limit. When the green token is filled in the token bucket 15c, the token is refilled in the token bucket 15d.
[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. After extracting 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]
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. You are dropping the packet.
[0042]
The policy action processing unit 16 extracts the traffic class (green and yellow) and the policer determination result of the input packet, searches the action table 18 based on the extracted information, and determines the processing for the input packet. For example, for a conforming packet of a traffic class (green) requiring low-delay communication, the policy action processing unit 16 causes the packet to be input to a queue that is serviced preferentially (for example, to the transmission queue 22), and For non-conforming packets 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 conformity / non-conformity of the packet from the color of the packet and the result of the policer determination. Since scheduling is performed after policing for determining transmission or discarding, the device configuration is simplified, and accordingly, traffic priority control and bandwidth control for users 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, in the present invention, a plurality of thresholds are set based on a traffic class using a policer with priority and a policer that supports a color-aware mode to guarantee the bandwidth of an input packet. Since the packet scheduling is performed after storing the bandwidth-guaranteed packets in different transmission queues based on the traffic class, the configuration is simplified, and the traffic priority control and the bandwidth control of the user are simplified at low cost. Can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an example of a configuration of a band control device according to the present invention.
FIG. 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. 3 is a configuration diagram illustrating an example of a configuration of a priority-added policer illustrated in FIG. 2;
FIG. 4 is a flowchart for explaining a processing operation of the policer shown in FIG. 3;
FIG. 5 is a flowchart illustrating a processing operation of a policy action processing unit illustrated in FIG. 2;
FIG. 6 is a configuration diagram illustrating another example of the configuration of the policer illustrated in FIG. 2;
[Explanation of symbols]
10 Router 11-13 Input side NP
14 classifier 15 priority policers 15a, 15c, 15d token buckets 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 (4)

In a band control method of transmitting input data by performing predetermined band control,
A first control step of guaranteeing a band of the input data based on at least two predetermined thresholds within the predetermined band and limiting a traffic flow of the input data;
Based on a policy condition of the data, a storage control step of storing the flow-limited data in different transmission queues,
A second control step of controlling a delay of the data traffic using a plurality of the transmission queues;
A bandwidth control method comprising: In a band control device that performs band control and transmits the traffic amount of input data,
Within the predetermined band to be controlled, at least two thresholds are set, and based on the thresholds, a band of the input data is guaranteed, and first control means for limiting a traffic flow of the data,
A storage control unit having at least two transmission queues and storing the flow-restricted data in the transmission queue based on a policy condition of the data;
Second control means for controlling a delay of traffic of the data stored in the plurality of transmission queues;
A bandwidth control device comprising: 3. The bandwidth control device according to claim 2, wherein the first control unit sets a threshold according to a priority of the data. 3. The bandwidth control device 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 data of a packet configuration as the policy condition.

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