JP2017147583A - Network repeater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network repeater capable of detecting a burst state with higher precision.SOLUTION: The network repeater includes: a port for receiving and transmitting a frame; a control part for determining whether or not a reception state of the frame is a burst state; and a token bucket processing part having a plurality of token buckets whose setting condition is different, used for detecting that a reception rate of the frame received by the port is in excess of a predetermined reference value. The control part determines it to be under a burst state only when an order of detecting that the reception rate is in excess of the predetermined reference value by the token bucket processing part is a predetermined order according to a state where each of the token buckets is empty.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a network relay device, and more particularly to a technique effective when applied to a network relay device capable of detecting a burst state.

  In a network system composed of network relay devices such as switches and routers, burst traffic that instantaneously increases traffic may occur. In particular, a phenomenon in which the traffic volume suddenly increases every millisecond or microsecond is called microburst. There is a desire to detect such a microburst and specify the source of the occurrence.

  Regarding detection of microbursts, for example, Japanese Patent Laying-Open No. 2013-168832 (Patent Document 1) describes a technique for identifying the source of microbursts while minimizing the processing burden on the control unit of the network relay device. ing. Specifically, received frames are classified into three groups based on reference values (first reference value and second reference value) related to the received amount (received band), and a specific group (for example, the received amount is the first reference value). Only when it is determined that it belongs to a group that does not exceed the second reference value, the contents of the received frame are duplicated and transmitted to the control unit.

JP 2013-168832 A

  According to the prior art, it is possible to detect the microburst in the network relay device, acquire the contents of the received frame, and specify the generation source.

  On the other hand, as a mechanism for detecting that the received amount exceeds each reference value, a token bucket (token bucket) mechanism widely used for bandwidth control is used. In other words, by setting the token bucket size (maximum bucket size) as the minimum value that realizes the reception bandwidth (reception rate) of the reference value, the reception rate exceeds the reference value when the token in the token bucket becomes empty Judge that

  In this case, when the reception rate of the received frame is much higher than the token supply rate in the token bucket, the token is emptied in a short time. Thereby, an instantaneous increase (burst state) of the reception rate due to burst traffic can be detected immediately. However, for example, a situation may occur in which the reception rate is slightly higher than the token supply rate. When this state continues for a long time, tokens may gradually decrease and eventually become empty, and it may be detected as a burst state even though the reception rate does not increase instantaneously.

  The present invention has been made in view of the above, and an object of the present invention is to provide a network relay device capable of detecting a burst state with higher accuracy. The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

  A network relay device according to an exemplary embodiment of the present invention includes a port that receives and transmits a frame, a control unit that determines whether a reception state of the frame is a burst state, and the frame that is received by the port. And a token bucket processing unit having a plurality of token buckets with different setting conditions for detecting that the reception rate of the token exceeds a predetermined reference value, and the control unit includes the token bucket processing unit In this case, the burst state is determined only when the order in which it is detected that the reception rate exceeds the predetermined reference value due to the token buckets being empty is the predetermined order. .

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  That is, according to the representative embodiment of the present invention, it is possible to detect the burst state with higher accuracy.

It is the figure which showed the outline | summary about the structural example of the network system in one embodiment of this invention. It is the block diagram which showed the outline | summary about the structural example of the Ethernet switch which is one embodiment of this invention. It is the figure which showed the outline | summary about the example of the detection method of the burst state in one embodiment of this invention. It is the figure which showed the example of the setting conditions of each token bucket in one embodiment of this invention. It is the graph which showed the example of the relationship between the reception time of the flame | frame in the token bucket in one embodiment of this invention, and the detection time until reference value excess. It is the figure which showed the outline | summary about the structural example of the token bucket process part in one embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted. On the other hand, parts described with reference numerals in some drawings may be referred to with the same reference numerals although not illustrated again in the description of other drawings.

<Network system configuration>
FIG. 1 is a diagram showing an outline of a configuration example of a network system according to an embodiment of the present invention. The network system 1 is configured by, for example, a wide area Ethernet (registered trademark), and includes a core network 2, one or more user bases 5, and one or more Ethernet switches (network relay devices) 4 arranged therebetween. Have. The function of the present invention is applied to these Ethernet switches 4. The Ethernet switch 4 includes one that is arranged at each user base 5 and accommodates the user terminal 6, and one that accommodates these Ethernet switches 4 and is connected to the router 3 of the core network 2. Note that the number and configuration of the above-described components in the network system 1 are not limited to those illustrated.

<Configuration of Ethernet switch>
FIG. 2 is a block diagram showing an outline of a configuration example of the Ethernet switch 4 according to the embodiment of the present invention. The Ethernet switch (network relay device) 4 includes, for example, a plurality of ports 10, a switching LSI (Large-Scale Integration) 20, a relay unit 30, a memory 40, and a control unit 50.

  The port 10 is an external interface to which a communication cable is connected, and functions as both a reception port that receives a frame and a transmission port that transmits a frame. The number of ports 10 included in the Ethernet switch 4 is not limited to that shown in the figure, and includes a number corresponding to the specifications of each Ethernet switch 4.

  The switching LSI 20 has a function of transmitting a frame from the port 10 to the relay unit 30 or from the relay unit 30 to the port 10 by performing processing such as encoding and decoding. The switching LSI 20 further includes units such as a token bucket processing unit 21 and a token bucket setting condition holding unit 22.

  The token bucket processing unit 21 cooperates with the control unit 50 to determine the reception status (reception bandwidth, reception rate) of the frame received from the port 10 according to the method described later using the token bucket mechanism. It has a function to detect the burst state. In this embodiment, the case where the burst state is detected on the ingress side when receiving a frame from the port 10 is taken as an example, but the burst state is detected when transmitting the frame to the port 10, that is, on the egress side. It is good also as a structure.

  When the token bucket processing unit 21 detects that the frame reception rate exceeds a predetermined reference value, the token bucket processing unit 21 notifies the control unit 50 and the like. Similarly to the technique described in Patent Document 1, the content of the target frame may be copied and added to the information of the port 10, and then transmitted to the control unit 50. Further, in this embodiment, only the detection of the burst state is intended, and even when the burst state is detected, the transmission of the frame received from the port 10 to the relay unit 30 (and vice versa) is continuously performed. Shall. Band control (for example, traffic policing and shaping) may be performed together with a general token bucket mechanism.

  The token bucket setting condition holding unit 22 holds a plurality of setting conditions such as a token bucket size and a token supply rate. The token bucket processing unit 21 has a plurality of token buckets for detecting a burst state, and the plurality of token buckets operate based on setting conditions held in the token bucket setting condition holding unit 22. The setting condition is variable, and the token bucket setting condition holding unit 22 holds a predetermined setting condition from the outside.

  The relay unit 30 has a function of realizing a MAC (Media Access Control) sublayer of a data link layer in an OSI (Open Systems Interconnection) reference model in cooperation with the memory 40 and the control unit 50. The relay unit 30 is implemented by, for example, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or the like, and includes various units such as an input processing unit 31 and an output processing unit 32.

  Based on the destination MAC address in the frame received from the switching LSI 20, the input processing unit 31 sets the output destination port 10 while referring to the FDB (Forwarding DataBase) 41 stored in the memory 40, and outputs the frame Processing to transmit to the processing unit 32 is performed. If the destination MAC address is not registered in the FDB 41, the frame is transmitted to the output processing unit 32 as a broadcast. Further, the input processing unit 31 performs processing for registering the source MAC address in the received frame in the FDB 41 in association with the number of the port 10 that received the frame. The output processing unit 32 transmits the frame received from the input processing unit 31 to the switching LSI 20.

  The memory 40 is a storage device that can be read and written, and stores an FDB 41. The control unit 50 is configured by a CPU (Central Processing Unit) and controls the entire Ethernet switch 4. In the present embodiment, the token bucket processing unit 21 has a function of determining whether or not it is in a burst state based on the result of detecting that the reception rate exceeds a predetermined reference value. When the token bucket processing unit 21 detects that the reception rate exceeds a predetermined reference value, a process of acquiring and recording information of a frame transmitted from the switching LSI 20 may be performed.

<Burst state detection method>
The basic concept of the burst state detection method in the present embodiment is the same as that of the prior art described in Patent Document 1. FIG. 3 is a diagram showing an outline of an example of a burst state detection method in the present embodiment. Similar to the prior art described in Patent Document 1, the reception rates are divided into three groups based on reference values (first reference value and second reference value). When the reception rate exceeds the first reference value, the burst state is determined. Then, only when it is determined that the reception rate belongs to a specific group (a group in which the reception amount exceeds the first reference value but does not exceed the second reference value), the received frame is duplicated and transmitted to the control unit 50. To do. In the example of FIG. 3, this corresponds to a period in which the reception rate does not exceed the second reference value in the time period from t3 to t4. By copying the content of the received frame and transmitting it to the control unit 50 only when belonging to a specific group, the processing load can be reduced.

  In the prior art, a token bucket (token bucket) mechanism is used to detect that the reception rate exceeds each reference value. Specifically, a token bucket corresponding to each reference value is set, and each token bucket size (maximum bucket size) is set as a minimum value that realizes the reception rate of each reference value. When the token in the token bucket becomes empty, it is determined that the reception rate has exceeded the corresponding reference value.

  In this case, when the reception rate of the received frame is much higher than the token supply rate in the token bucket, the token is emptied in a short time. Therefore, even if the reception rate increases instantaneously due to burst traffic, it can be immediately detected that the reception rate exceeds a reference value (for example, the first reference value). However, for example, even if the reception rate is slightly higher than the token supply rate, if this continues for a long time, the token may gradually decrease and eventually become empty. In this case, it is determined that the reception rate has exceeded the first reference value at this point in time, even though it is not actually a burst state, so that it is detected as a burst state.

  Therefore, in the present embodiment, as in the related art, it is determined whether the reception rate exceeds the reference value using the token bucket mechanism. In order to determine whether the first reference value is exceeded, Use token buckets. The setting conditions (token bucket size and token supply rate) of each token bucket are different from each other. And it is judged that it is a burst state only when each token bucket is empty (it is detected that the reception rate exceeds the first reference value) is in a predetermined order. As a result, it is possible to exclude a state in which the token in the token bucket is emptied over a long time with a low reception rate from the burst state detection target.

  FIG. 4 is a diagram showing an example of setting conditions for each token bucket in the present embodiment. In this embodiment, three token buckets a, b, and c are provided, and the token bucket size is set to increase in the order of token bucket a → b → c. On the other hand, the token supply rate is set to decrease in the order of token buckets a → b → c.

  FIG. 5 is a graph showing an example of the relationship between the frame reception rate in each token bucket and the detection time until the reference value is exceeded. The detection time until the reference value is exceeded in each token bucket at a certain reception rate, that is, the time until the token in the token bucket becomes empty is expressed by the following expression. That is, when the reception rate is R, the detection time is T, the token bucket size is S, and the token supply rate is r, T = S / (R−r). The graph of FIG. 5 specifically shows the relationship between the reception rate R and the detection time T for the token buckets a, b, and c shown in FIG. 4 based on this equation.

  In the present embodiment, as described above, the supply rate r is set to be smaller as the token bucket size S is larger in the token buckets a, b, and c. As a result, as shown in the example of FIG. 5, a portion where the curves of the graph intersect (the reception rate indicated by the broken line in the drawing is about 460 Mbps) occurs. In a region where the reception rate is higher than this reception rate (hereinafter referred to as “burst state detection rate”), the detection time until the reference value is exceeded at any reception rate is always shorter in the order of token buckets a → b → c. . In other words, it is understood that the reference value excess is always detected in the order of token buckets a → b → c. On the contrary, in a region where the reception rate is lower than the burst state detection rate, detection of exceeding the reference value does not occur in the order of token buckets a → b → c.

  Therefore, in the present embodiment, bursts are detected only when an excess of the first reference value is detected in the order of token buckets a → b → c, that is, in the same order as the ascending order of token bucket size (or descending order of supply rate). Treat with condition. This ensures that the reception rate is higher than the burst state detection rate, and does not detect the case where the first reference value excess is detected as a result of a relatively low reception rate continuing for a long time as a burst state. Can do. From the graph shown in FIG. 5, it can be said that the setting conditions of each token bucket in the example of FIG. 4 are settings suitable for detecting a burst state of about 500 Mbps to 1000 Mbps.

  In the above example, the burst state is handled only when an excess of the first reference value is detected in the order of token buckets a → b → c. On the other hand, in the example of FIG. 5, the curves of the token bucket a and the token bucket b intersect in the vicinity of the burst state detection rate. Therefore, if it is detected that the first reference value exceeds at least in the order of token bucket a → b, it can be ensured that the reception rate is higher than the burst state detection rate. That is, when the first reference value excess is detected in the order of the token bucket a → b, it can be handled as a burst state regardless of whether or not the first reference value excess is detected in the token bucket c. What is important is that the order in which the first reference value excess is detected is not reversed as in the token bucket b → a and the token bucket c → b. As long as this is satisfied, the number of token buckets can be any number greater than or equal to two. Moreover, it is not essential to detect the first reference value excess for all the set token buckets.

  In addition, when the average frame reception rate in the Ethernet switch 4 is larger than the smallest token supply rate in each token bucket (250 Mbps in the token bucket c in the example of FIG. 4), the target In the token bucket, the first reference value excess is always detected. In this case, overhead due to processing such as frame duplication and notification may occur. Therefore, it is desirable that the minimum value of the token supply rate is set to a value larger than the average reception rate at normal times.

  FIG. 6 is a diagram showing an outline of a configuration example of the token bucket processing unit 21 that detects that the first reference value is exceeded by the above-described method. In the example of FIG. 6, the token bucket processing unit 21 serially determines the first reference value excess for each of the token buckets a, b, and c shown in the example of FIG. 4 for the frame received by the switching LSI 20. Is configured to do. Specifically, a token bucket a determination unit 23a, a token bucket b determination unit 23b, and a token bucket c determination unit 23c (hereinafter may be collectively referred to as “token bucket determination unit 23”) are arranged in series. Yes.

  When each token bucket determination unit 23 detects that the first reference value has been exceeded due to the tokens in the corresponding token bucket becoming empty, it notifies the control unit 50 of each. At this time, similarly to the technique described in Patent Document 1, the content of the target frame may be copied and the information of the port 10 added thereto, and then transmitted to the control unit 50. Each token bucket determination unit 23 delivers the frame as it is to the subsequent token bucket determination unit 23 and the like even when the first reference value excess is detected. At this time, bandwidth control (for example, traffic policing or shaping) may be performed together with a token bucket mechanism.

  The control unit 50 stores the order in which the first reference value excess notification or the information including the content of the target frame is received from each token bucket determination unit 23. When the order is the same as the ascending order of the token bucket size of each token bucket, the burst state is determined. The stored content of the order exceeding the first reference value is reset when an order different from the ascending order of the token bucket size is detected. Alternatively, the stored contents may be made valid only within a predetermined time from the timing at which the first bucket value is first detected by any one of the token bucket determination units 23, and reset after a predetermined time has elapsed.

  In the example of FIG. 6, the frame is transferred in the order of token bucket a determination unit 23a → token bucket b determination unit 23b → token bucket c determination unit 23c, and it is determined that the first reference value has been exceeded in the order of token bucket a → b → c However, the present invention is not limited to this. As described above, in the present embodiment, only the order in which the first reference value excess is detected becomes a problem, and the determination order does not matter. Therefore, the order of delivering frames to the token bucket determination unit 23 (token bucket determination order) can be arbitrary.

  When a first reference value excess is detected in a plurality of token bucket determination units 23 for a certain frame, the temporal order of detection depends strictly on the determination order in each token bucket determination unit 23. It will be. However, in this case, since the determination is for the same frame, it is sufficient that the first reference value excess is detected at the same time regardless of the determination order. When the first reference value excess is detected for a plurality of token buckets at the same time, they may be handled as detected in the same order as the ascending order of the token bucket size, or may be handled as different orders.

  In addition, since the order in which the token buckets are determined does not matter, it is not essential to have a configuration in which a frame is serially transferred to each token bucket determination unit 23 as in the example of FIG. For example, it is possible to arrange a part or all of the token bucket determination units 23 in parallel so that the contents of the frame are duplicated and delivered in parallel to these.

  As described above, according to the Ethernet switch 4 (network relay device) which is an embodiment of the present invention, the reception rate is divided into three groups based on the reference values (first reference value and second reference value). . Only when it is determined that the reception rate belongs to a group that exceeds the first reference value but does not exceed the second reference value, the burst rate is determined.

  In order to determine whether the first reference value is exceeded, a plurality of token buckets having different setting conditions (token bucket size and token supply rate) are used. Specifically, the setting condition is such that the larger the token bucket size, the smaller the token supply rate. And it is judged that it is a burst state only when the order which detected exceeding the 1st standard value about each token bucket was the predetermined order, ie, the same order as the ascending order of token bucket size. As a result, it is possible not to detect a state in which the token rate of the token bucket is empty for a long time with a relatively low reception rate as a burst state.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of the above-described embodiment.

DESCRIPTION OF SYMBOLS 1 ... Network system, 2 ... Core network, 3 ... Router, 4 ... Ethernet switch, 5 ... User base, 6 ... User terminal,
10 ... Port,
DESCRIPTION OF SYMBOLS 20 ... Switching LSI, 21 ... Token bucket process part, 22 ... Token bucket setting condition holding part, 23a-c ... Token bucket ac determination part,
30 ... Relay unit, 31 ... Input processing unit, 32 ... Output processing unit,
40 ... memory, 41 ... FDB,
50. Control unit

Claims (4)

Ports that receive and transmit frames;
A controller that determines whether the reception state of the frame is a burst state;
A token bucket processing unit having a plurality of token buckets with different setting conditions for detecting that the reception rate of the frame received by the port exceeds a predetermined reference value;
The control unit is only when the order in which the token bucket processing unit detects that the reception rate exceeds the predetermined reference value due to each token bucket being empty is a predetermined order. A network relay device that determines that it is in a burst state. The network relay device according to claim 1,
Each of the token buckets is a network relay device configured such that the larger the token bucket size, the smaller the token supply rate. The network relay device according to claim 2,
The network relay device, wherein the predetermined order for determining that the control unit is in a burst state is the same order as the increasing order of the sizes of the token buckets. The network relay device according to claim 2,
The network relay device further includes a token bucket setting condition holding unit that holds in advance the size of each token bucket and a value of a token supply rate as the setting condition related to each token bucket.

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