JP5094452B2 - COMMUNICATION DEVICE, COMMUNICATION SYSTEM, CONTROL METHOD, AND CONTROL PROGRAM - Google Patents

Description

  The present invention suppresses the number of frames that can be accumulated in the queue (hereinafter referred to as queue resources) and outputs a frame that could not be output during congestion when congestion is resolved (hereinafter referred to as bandwidth leveling). The present invention relates to a communication device, a communication system, a control method, and a control program.

  As an example of bandwidth leveling, there is a method in which, for example, a queue resource has a margin, and when a slight congestion occurs, the frame is accumulated in the queue and the accumulated frame is transmitted when the congestion is eliminated. There is. However, there is a problem of cost, and it is not possible to provide sufficient resources for leveling the bandwidth completely. Therefore, strictly speaking, the present situation is that the leveling of the band cannot be realized.

  In addition, as technical literatures filed prior to the present invention, there are literatures that disclose a method of utilizing the surplus bandwidth after guaranteeing the allowable value of the input rate and the minimum guaranteed bandwidth (for example, Patent Literatures 1 and 2) reference).

  Further, there is a document that discloses a technique for realizing fair bandwidth allocation for an active flow (see, for example, Patent Document 3).

  Further, there is a document that discloses a technique that enables fair network resource management for each connection (see, for example, Patent Document 4).

  Further, there is a document that discloses a technique for improving throughput and usability by avoiding the same connection continuous discard, retransmission segment discard, segment discard immediately after communication, discard concentration, and the like (see, for example, Patent Document 5).

In addition, there is a document that discloses a technique for averaging the data amount of packets between a plurality of flows to be merged when packet transfer flows that exceed the physical bandwidth of the transmission port merge (for example, see Patent Document 6). .
JP 2003-23452 A JP 2002-185459 A JP 2003-324474 A JP-A-10-247924 Japanese Patent Laid-Open No. 11-187031 JP 2005-260430 A

  The methods disclosed in Patent Documents 1 and 2 are based on the premise that bandwidth leveling can be realized within the minimum guaranteed bandwidth without causing a discard due to a lack of queue resources. Therefore, it is necessary to achieve bandwidth leveling by providing sufficient resources for the queue. However, as described above, there is a problem of cost, and it is necessary to provide sufficient resources for leveling the bandwidth completely. I can't. For this reason, in the methods disclosed in the above-mentioned Patent Documents 1 and 2, the bandwidth cannot be leveled without having extra queue resources.

  In Patent Document 3, the discard size is controlled by managing the queue size for each flow, but no consideration is given to standardizing the bandwidth without having extra queue resources.

  In Patent Document 4, queues are managed for each connection (each flow), but no consideration is given to standardizing bandwidth without having extra queue resources.

  Further, in Patent Document 5, continuous discard of the same connection is avoided, but no consideration is given to standardizing the bandwidth without having extra queue resources.

  Moreover, in the said patent document 6, the accumulation limit of the buffer for every output port is fed back, and the flow volume limit value is changed dynamically. However, since there is a restriction to reduce the accumulated amount before discarding, it is possible to ensure fairness for each flow, but no consideration is given to standardizing the bandwidth without having extra queue resources.

  Therefore, in Patent Documents 1 to 6 described above, the bandwidth cannot be standardized without having extra queue resources.

  The present invention has been made in view of the above circumstances, and is a communication device, a communication system, a control method, and a control capable of standardizing a bandwidth without having an extra queue resource, which is the above-described problem. The purpose is to provide a program.

  In order to achieve this object, the present invention has the following features.

<Communication device>
The communication apparatus according to the present invention is
Inflow band limiting means for discarding input frames at a certain rate;
Accumulating means for accumulating the frames that have passed through the inflow band limiting means in each queue;
An output means for holding the frames accumulated in each queue and outputting the held frames;
Management means for managing the accumulated information of the frames accumulated in each queue for each queue;
In accordance with the accumulated information, a frame newly accumulated in each queue or a frame held by the output means is discarded, and discard information for specifying the discarded discarded frame is designated as the inflow band limiting means. Control means for notifying to,
The inflow band limiting means is
When the discard information is received, discard of the same type of frame as the discard frame is suppressed based on the discard information, and the discard frame is supplemented with the suppressed frame.

<Communication system>
Further, the communication system according to the present invention includes:
A communication system comprising a plurality of devices and a relay device that relays a frame transmitted by the device,
The relay device is
It is the communication apparatus described above.

<Control method>
Further, the control method according to the present invention includes:
Inflow band limiting means for discarding input frames at a fixed rate, storage means for storing frames that have passed through the inflow band limiting means in each queue, holding frames stored in each queue, and holding the stored frames A control method performed by a communication device having output means,
Managing the accumulated information of the frames accumulated in each queue for each queue;
In accordance with the accumulated information, a frame newly accumulated in each queue or a frame held by the output means is discarded, and discard information for specifying the discarded discarded frame is designated as the inflow band limiting means. A process of notifying
When the inflow band limiting unit accepts the discard information, based on the discard information , suppressing discard of the same type of frame as the discard frame, and supplementing the discard frame with the suppressed frame; It is characterized by having.

<Control program>
Further, the control program according to the present invention is:
Inflow band limiting means for discarding input frames at a fixed rate, storage means for storing frames that have passed through the inflow band limiting means in each queue, holding frames stored in each queue, and holding the stored frames A control program to be executed by a communication device having output means,
A process of managing the accumulated information of the frames accumulated in each queue for each queue;
In accordance with the accumulated information, a frame newly accumulated in each queue or a frame held by the output means is discarded, and discard information for specifying the discarded discarded frame is designated as the inflow band limiting means. Processing to notify
When the inflow band limiting unit receives the discard information, based on the discard information, a process of suppressing discard of the same type of frame as the discard frame and supplementing the discard frame with the suppressed frame; Are executed by the communication device.

  According to the present invention, it is possible to standardize the bandwidth without having extra queue resources.

  First, the communication apparatus of this embodiment will be described with reference to FIG.

  The communication device according to the present embodiment stores inflow queue limiting means (inflow band limiting unit; corresponding to 1) that discards input frames at a fixed rate, and frames that have passed through inflow band limiting means (1) in each queue. A communication device having storage means (frame storage unit; corresponding to 3) and output means (output buffers; corresponding to 7 and 8) for holding the frames stored in each queue and outputting the stored frames .

  Then, the communication apparatus according to the present embodiment manages the accumulated information of the frames accumulated in each queue for each queue, and according to the managed accumulated information, newly stores frames or output means (7 , 8) discard the frame, and notify the inflow band limiting means (1) of discard information for specifying the discarded discard frame. Then, when receiving the discard information, the inflow band limiting unit (1) suppresses discard of the discard frame based on the discard information, and supplements the discard frame with the suppressed frame. As a result, the communication apparatus of this embodiment can standardize the bandwidth without having extra queue resources. Hereinafter, the communication apparatus of this embodiment will be described with reference to the accompanying drawings. In the following description, the communication device is described as a relay device.

(First embodiment)
<Internal configuration of relay device>
First, the internal configuration of the relay device of this embodiment will be described with reference to FIG.

  The relay device in this embodiment includes an inflow band limiting unit (1), a frame writing control unit (2), a frame storage unit (3), a discard control unit (4), and a queue management unit (5) The frame read control unit (6) and the output buffers (7, 8) are configured.

  The inflow band limiting unit (1) discards input frames at a certain rate and adjusts the frame relay rate of the relay device.

  The frame writing control unit (2) controls frame writing to the frame storage unit (3).

  The frame storage unit (3) performs temporary storage of frames using the shared buffer method.

  The frame reading unit (6) controls frame reading from the frame storage unit (3).

  The queue management unit (5) manages the frame accumulation information of the frame accumulation unit (3) for each logical queue. Examples of the frame accumulation information include the number of frames accumulated, information indicating in which order the frames are stored in which region in the shared buffer (information used when reading the frame), and the like.

  The discard control unit (4) performs frame discard determination for each queue based on the frame accumulation information of each queue managed by the queue management unit (5), and issues a discard instruction to the frame write control unit (2). It is something to be issued.

  The output buffer (7, 8) is provided for each queue, temporarily holds a frame to be output next, and outputs a frame when the output becomes possible.

<Processing operation of the relay device>
Next, the processing operation of the relay device of this embodiment will be described with reference to FIG.

  The discard control unit (4) determines whether the queue usage limit has been exceeded based on the frame accumulation information managed by the queue management unit (5). Note that “exceeding the queue usage upper limit” means that the number of accumulated frames in the queue exceeds the upper limit value that can be accumulated in the queue. The discard control unit (4) issues a discard instruction to the frame writing control unit (2) when it is determined that the use upper limit of the queue is exceeded.

  The frame writing control unit (2) discards the frame based on the discard instruction received from the discard control unit (4). Note that the frame writing control unit (2) of this embodiment feeds back the discard information to the inflow band limiting unit (1) when the frame is discarded. The discard information is information for specifying a frame that has been discarded.

  The inflow band limiting unit (1) discards the input frames at a certain rate, and adjusts the number of discarded frames of the corresponding frame based on the discard information fed back from the frame writing control unit (2). For example, it is assumed that the discard information that the frame discard of the flow ID = 1 (the flow ID indicates individual identification information assigned to each flow) is fed back to the inflow band limiting unit (1). In this case, the inflow band limiting unit (1) suppresses the frame discard of the next input flow ID = 1 and adjusts the number of frame discards in the entire relay device.

  As described above, when the frame writing control unit (2) discards a frame due to exceeding the use upper limit of the queue, the relay device according to the present embodiment transmits the discard information on the frame discard to the inflow band limiting unit (1 ) Feedback. Based on the discard information, the inflow band limiting unit (1) suppresses the same type of frame discard as the frame for which the frame writing control unit (2) discarded the frame, and the frame discard is performed with the suppressed frame. Compensate for the frame that was performed.

  As a result, even if a frame discard due to exceeding the queue usage upper limit occurs, the relay device of the present embodiment compensates for the corresponding frame for which the frame was discarded. It becomes possible to tolerate. Therefore, the relay apparatus according to the present embodiment can realize band leveling without having extra queue resources for suppressing frame discard in a light congestion state.

  FIG. 2 and FIG. 3 are examples in the case where the frame is discarded when the use upper limit of the queue is exceeded. 2 and 3 show a case where only one flow frame flows and relays at a rate of 1/3 of the input rate for the sake of simplicity.

  FIG. 2 shows the operation of the relay apparatus related to the present invention. In the operation shown in FIG. 2, after the input frame is limited to a rate of 1/3 due to the inflow band limitation, the frame is discarded due to exceeding the use upper limit of the queue. For this reason, the relay apparatus related to the present invention causes the rate of the output frame to be lower than the rate assumed in advance.

  FIG. 3 shows the operation of the relay device of this embodiment. In the operation shown in FIG. 3, as in FIG. 2, after the input frame is limited to a rate of 1/3 due to the inflow band limitation, the frame is discarded due to exceeding the upper limit of the queue usage. However, the relay apparatus according to the present embodiment feeds back the discard information of the corresponding frame that has been discarded due to exceeding the queue usage upper limit to the inflow band limiting unit (1), and the inflow band limiting unit (1) discards the frame. The number of discarded frames is adjusted. For this reason, the relay apparatus of this embodiment can set the rate of the output frame to a rate assumed in advance.

  FIG. 4 is a diagram showing a comparative example of frame rates between the relay device related to the present invention and the relay device of the present embodiment. In FIG. 4, the frame rate (a shown in FIG. 4) before being input to the inflow band limiting unit (1) passes through the inflow band limiting unit (1) and is input to the frame writing control unit (2). The frame rate (b shown in FIG. 4) before the transmission and the frame rate (c shown in FIG. 4) after passing through the frame writing control unit (2) are shown.

  In the relay apparatus related to the present invention, the input frame is limited to a rate of about 1/3 in the inflow band limiting unit (1). Then, due to temporary congestion, the upper limit of the queue usage occurs, and the frame writing control unit (2) discards the dotted frame.

  Further, in the relay device of the present embodiment, the input frame is limited to a rate of about 1/3 in the inflow band limiting unit (1) similarly to the related relay device described above. Then, due to temporary congestion, the upper limit of the queue usage occurs, and the frame writing control unit (2) discards the dotted frame. However, the relay device of this embodiment feeds back the discard information of the corresponding frame discarded by the frame writing control unit (2) to the inflow band limiting unit (1), and the inflow band limiting unit (1) Disposal is suppressed. For this reason, in the relay apparatus according to the present embodiment, band leveling is performed. On the other hand, the related relay apparatus does not perform band leveling.

Next, the operation of the inflow band limiting unit (1) of the present embodiment will be described with reference to FIG.
The inflow bandwidth limiter (1) holds the table shown in FIG. 5, manages the number of input frames and the allowable value of the inflow bandwidth for each “flow ID”, and discards frames that exceed the allowable value. The input frames are discarded at a certain rate. As long as it is possible to discard input frames at a certain rate, the method is not particularly limited, and any method can be applied to control the input frames to be discarded at a certain rate. .

  The initial state of the table of the inflow band limiting unit (1) is indicated by “T1”. The table of the present embodiment is configured with “Discard Flag”. In the initial state “T1” shown in FIG. 5, “Discard Flag” is all “0”. Thereafter, it is assumed that the discard information of flow ID = 3 is notified to the inflow band limiting unit (1) by the feedback of the discard information from the frame writing control unit (2). In this case, the inflow band limiting unit (1) receives the notification and updates the “discard flag” of the flow ID = 3 in the table to “1”. The updated table status is shown in “T2”. After that, when the frame with flow ID = 3 is input, the inflow bandwidth limiter (1) refers to the table, and since “Discard Flag” of flow ID = 3 is “1”, the flow ID = The third frame is passed unconditionally without being discarded.

  As a result, the relay apparatus according to the present embodiment is configured so that the total number of discarded frames is the sum of both the frame discard in the frame writing control unit (2) and the frame discard in the inflow band limiting unit (1). The number of discarded frames can be adjusted.

  The inflow band limiting unit (1) updates the “discard flag” to the initial value “0” after unconditionally passing the input frame having the “discard flag” of “1”, and normal inflow Shifting to bandwidth limitation control, the input frames are discarded at a certain rate.

  The inflow band limiting unit (1) passes the frame header with the discard flag added, and the frame writing control unit (2) suppresses the continuous discard of frames of the same flow.

<Frame discard judgment>
Next, frame discard determination of the frame writing control unit (2) will be described with reference to FIG. Note that the frame discard determination shown in FIG. 6 is performed for all frames destined for the discard target queue. As shown in FIG. 6, there are two types of frame discard determinations: “forced discard instruction” and “condition discard instruction”. The “forced discard instruction” is an instruction to discard a frame unconditionally. The “condition discard instruction” is an instruction to discard a frame according to the value of the discard flag.

  First, the frame writing control unit (2) determines whether or not the discard instruction received from the discard control unit (4) is a “forced discard instruction” (step S1). When the frame writing control unit (2) determines “forced discard instruction” (step S1 / Yes), the frame writing control unit (2) unconditionally discards the frame (step S3) and ends the process. If it is determined that it is not a “forced discard instruction” (step S1 / No), it is determined whether it is a “conditional discard instruction” (step S2). If the frame writing control unit (2) determines that it is not a “condition discard instruction” (step S2 / No), the process is terminated. If the frame writing control unit (2) determines that it is a “condition discard instruction” (step S2 / Yes), it refers to the “discard flag” in the header of the frame, and the “discard flag” is “1”. "Or" 0 "is determined (step S4). When the “discard Flag” is “0” (discard Flag = 0), the frame writing control unit (2) discards the frame (step S5) and ends the process. When “Discard Flag” is “1” (Discard Flag = 1), the process is terminated without discarding the frame. As described above, the frame writing control unit (2) performs frame discard according to the “forced discard instruction” and the “condition discard instruction” for the frame destined for the discard target queue.

<Specific examples of disposal>
Next, a specific example of the frame discarding process will be described with reference to FIGS.

  FIG. 7 shows an example when the remaining resource of the queue for port 0 (low priority) is “1”. In this case, the discard control unit (4) issues a condition discard instruction for the frame of port 0 (low priority) to the frame writing control unit (2). The frame write control unit (2) that has received the condition discard instruction for the frame of port 0 (low priority) refers to the discard flag of the frame of port 0 (low priority) that is input next, and the discard flag = 0. If so, discard the frame. If the discard flag = 1, the frame is not discarded, and the process waits until the next discard frame = 0 of the port 0 (low priority) is input. As a result, it is possible to suppress the continuous discard of frames of the same flow and prevent the frame discard from concentrating only on a specific flow.

  When the remaining resource of the queue for port 0 (low priority) becomes “0”, as shown in FIG. 8, the discard control unit (4) sends port 0 (low) to the frame write control unit (2). A priority discard instruction is issued. The frame writing control unit (2) that has received the forced discard instruction of the port 0 (low priority) frame unconditionally discards the next input port 0 (low priority) frame.

  FIG. 9 shows an example in which there are “2” or more individual remaining resources for each queue, but the remaining resource (Idle) of the entire queue is “1”. In this case, the discard control unit (4) issues a condition discard instruction without designating the port or priority of the discard target frame. The frame writing control unit (2) that has received a condition discard instruction that has not been specified refers to the discard flag of the input frame and discards it regardless of the port and priority of the next input frame. The frame is discarded according to the flag. If the discard flag = 0, the frame is discarded. If the discard flag = 1, the frame is not discarded and is written in the frame storage unit (3).

  In the state of FIG. 9, when the next input frame is a frame with discard flag = 1, the frame is not discarded and is written to the frame storage unit (3). The remaining resource is “0”. In this case, the discard control unit (4) issues a forced discard instruction without designating the port or priority of the discard target frame. The frame writing control unit (2) that has received a forced discard instruction for which nothing has been specified discards the next input frame unconditionally.

<Operation / Effect of Relay Device of this Embodiment>
As described above, when the frame writing control unit (2) discards a frame due to the occurrence of congestion, the relay device of the present embodiment feeds back the discard information of the frame to the inflow band limiting unit (1), The discarded frame will be compensated. For this reason, the relay apparatus of the present embodiment can realize band leveling without having extra resources.

  In addition, the relay device of the present embodiment allows the inflow band limiter (1) to pass with the discard flag added to the header of the frame, and the frame write controller (2) suppresses continuous discard of the same flow of frames. I have to. For this reason, the relay apparatus of this embodiment can prevent the frame discard from concentrating only on a specific flow.

(Second Embodiment)
Next, a second embodiment will be described.

  In the first embodiment, “discard Flag” is used as an indication of “presence / absence of frame discard” in the frame writing control unit (2), and the initial value of “discard Flag” before the occurrence of discard is “0”. It was said. Also, once the “Discard Flag” is updated to “1”, the “Discard Flag” is updated to the initial value “0” due to the unconditional passage of the frame of the relevant flow. In this case, the frame discard at the time of congestion is not suppressed.

  For this reason, the relay apparatus according to the second embodiment is characterized in that the initial value of “discard Flag” of a flow that cannot be discarded is set to “1” to always suppress frame discard at the time of congestion. In particular, in the queue management unit (5), when a plurality of flows are mixed and managed in one queue, it is possible to suppress frame discard of a specific flow in addition to the discard priority for each queue. Hereinafter, the relay apparatus according to the second embodiment will be described in detail.

  The relay device according to the second embodiment is configured in the same manner as the relay device according to the first embodiment shown in FIG. 1, and the operation of the inflow band limiting unit (1) is different.

  The inflow band limiting unit (1) of the present embodiment holds the table shown in FIG. 5, and sets the initial value of “Discard Flag” of “Flow ID” for which frame discard is always suppressed to “1”. As a result, the inflow band limiting unit (1) adds “discard Flag = 1” to the header of the frame with the corresponding flow ID, and therefore suppresses frame discard in the frame writing control unit (2). It becomes possible.

(Third embodiment)
Next, a third embodiment will be described.

  In the relay apparatus of the first embodiment, the frame writing control unit (2) performs frame discard when the use upper limit of the queue is exceeded.

  The relay apparatus according to the third embodiment is characterized in that the frame discard when the queue usage upper limit is exceeded is performed by the output buffer (7, 8). As a result, it is possible to discard a frame other than the frame write control unit (2) when the queue usage limit is exceeded, as in the first embodiment. Hereinafter, the relay device according to the third embodiment will be described in detail.

<Internal configuration of relay device>
First, an example of the internal configuration of the relay device of this embodiment will be described with reference to FIG.
The basic configuration of the relay apparatus according to the present embodiment is configured in the same manner as in the first embodiment, and operations performed by each unit are different.

  The discard control unit (4) of this embodiment determines whether the queue usage limit has been exceeded based on the frame accumulation information managed by the queue management unit (5). The discard control unit (4) issues a discard instruction to the output buffer (7, 8) when it is determined that the queue usage upper limit is exceeded. The output buffer (7, 8) discards the frame based on the discard instruction received from the discard controller (4). When the frame is discarded, the output buffer (7, 8) feeds back the discard information to the inflow band limiting unit (1). The inflow band limiting unit (1) discards input frames at a certain rate, and adjusts the number of discarded frames of the corresponding frame based on the discard information fed back from the output buffers (7, 8). Note that the frame writing control unit (2) in the present embodiment writes a frame to the frame storage unit (3) without performing the frame discarding determination as in the first embodiment.

<Specific examples of disposal>
Next, a specific example of the frame discarding process will be described with reference to FIGS.

  FIG. 11 shows an example when the remaining resource of the queue for port 0 (low priority) is “1”. In this case, the discard control unit (4) issues a condition discard instruction to the output buffer (8) of port 0 (low priority). The output buffer (8) that received the condition discard instruction refers to the discard flag of the frame held by the output buffer (8) itself, and if the discard flag is 0, the retained frame is discarded, The first frame in the queue for port 0 (low priority) is read from the frame storage unit (3). As a result, the remaining resource in the queue after reading becomes “2”, and a new frame can be put in the free resource. Further, when the discard flag = 1, the held frame is not discarded, and the process waits until the frame with the discard flag = 0 is retained in the output buffer (8). This makes it possible to suppress two consecutive discards of frames with the same flow.

  When the output buffer (8) itself holds the frame with the discard flag = 1 and the remaining resource in the queue is “0”, the discard controller (4) sets the output buffer (8) as shown in FIG. On the other hand, a compulsory disposal instruction is issued. The output buffer (8) that has received the forced discard instruction discards the frame held by the output buffer (8) itself unconditionally.

  FIG. 13 shows an example in which there are “2” or more individual remaining resources for each queue, but the remaining resource (Idle) in the entire queue is “1”. In this case, the discard control unit (4) determines an output buffer for issuing a condition discard instruction based on the accumulated number of each queue and the remaining number of resources. For example, in FIG. 13, when discarding a frame of a queue with the smallest remaining resource, a condition discard instruction is issued to the output Buffer (7). In addition, when discarding the frame of the queue having the maximum accumulated number, a condition discard instruction is issued to the output buffer (8).

  In addition, in order to determine the output buffer that issues the condition discard instruction, the judgment condition for determining the output buffer (when discarding the frame of the queue with the smallest remaining resource, (Determination conditions such as when discarding) are set in advance in the discard control unit (4), and the discard control unit (4) sets the discard control unit (4) The output buffer corresponding to the set judgment condition will be determined. As described above, the relay apparatus according to the present embodiment can adjust the priority of frame discard for each queue / priority.

  If a frame with discard flag = 1 is held in the output buffer that issued the condition discard instruction, the remaining resource in the entire queue becomes “0” by newly inputting the frame before discarding the frame. There is a case. In this case, the discard controller (4) arbitrates the next candidate output buffer that can be discarded immediately without fixing the output buffer that issues the forced discard instruction. It is possible to shorten the time until the process is performed.

  FIG. 14 shows an example in which frames are discarded from the second candidate queue. When an output buffer that has been instructed to discard by “forced discard instruction 0” cannot immediately discard a frame, the output buffer notifies the discard control unit (4) by “NAK response 0” that the frame cannot be discarded immediately. Upon receiving the notification, the discard control unit (4) arbitrates the second candidate discard target queue and outputs “forced discard instruction 1” to the output buffer of the second candidate. After discarding the frame, the second candidate output buffer notifies the discard control unit (4) of the completion of the frame discard with “ACK response 1” and completes the discarding process. The arbitration of the second candidate discard target queue is performed under the same conditions as when the first candidate queue that cannot be discarded immediately is excluded from the arbitration target and the first candidate queue is determined.

<Operation / Effect of Relay Device of this Embodiment>
As described above, in the relay device of this embodiment, when the discard of the frame exceeding the upper limit of use of the queue is performed in the output buffer (7, 8), the discard information on the discard of the frame is transmitted to the inflow band limiting unit (1 ) Feedback. Based on the discard information, the inflow band limiting unit (1) suppresses the same type of frame discard as the frame in which the output buffer (7, 8) discarded the frame, and discards the frame with the suppressed frame. Compensate for the frames you have done.

  As a result, the relay device according to the present embodiment can realize bandwidth leveling without having extra queue resources, as in the first embodiment. Furthermore, since the relay device of this embodiment is discarded from a frame having a long residence time at the time of congestion, the delay in the relay device can be reduced.

(Fourth embodiment)
Next, a fourth embodiment will be described.

  In the fourth embodiment, a case will be described in which the above-described relay apparatus is used under a traffic condition in which only some of the frames are relayed instead of relaying 100% of the frames. Hereinafter, a communication system to which the relay device of this embodiment is applied will be described in detail with reference to FIG.

<System configuration of communication system>
First, a system configuration example of the communication system according to the present embodiment will be described with reference to FIG.

  The communication system in the present embodiment includes a plurality of devices (N1 to N8) and a relay device (100). In FIG. 15, buses (B1 to B3) are buses that share a 100 Mbps band in each device. The relay device (100) is required to relay the frame from the bus (B1) and the frame from the bus (B2) to the bus (B3). At that time, the frame rate to be sent to the bus (B3) is 120 Mbps, and the bandwidth of the bus (B3) 100 Mbps is insufficient.

  Here, for example, all 20 Mbps frames transmitted from the device (N1) on the bus (B1) must be received by the device (N2) on the same bus, but the bus via the relay device (100) (B3) The device (N6) above needs to receive only 2Mbps at the 10% rate. Similarly, it is assumed that a frame transmitted from a certain device needs to be received at 100% by a device on the same bus and received at a rate of 10% by a device on a different bus. In that case, the frame rate flowing into the bus (B3) can be suppressed to 57 Mbps by relaying / discarding the frames relayed by the relay device (100) at a ratio of 1: 9. As described above, it is possible to apply the above-described relay device of the present embodiment under the traffic condition in which it is necessary to discard frames at a certain rate in the relay device (100).

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  For example, the control operation in each unit configuring the relay device in the present embodiment described above can be executed using hardware, software, or a combined configuration of both.

  In the case of executing processing using software, it is possible to install and execute a program in which a processing sequence is recorded in a memory in a computer incorporated in dedicated hardware. Alternatively, the program can be installed and executed on a general-purpose computer capable of executing various processes.

  For example, the program can be recorded in advance on a hard disk or ROM (Read Only Memory) as a recording medium. Alternatively, the program can be stored (recorded) temporarily or permanently in a removable recording medium. Such a removable recording medium can be provided as so-called package software. The removable recording medium includes a floppy (registered trademark) disk, a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto optical) disk, a DVD (Digital Versatile Disc), a magnetic disk, a semiconductor memory, and the like.

  The program is installed in the computer from the removable recording medium as described above. In addition, it is wirelessly transferred from the download site to the computer. In addition, it is transferred to the computer via a network by wire.

  In addition, the relay device in the present embodiment is not only executed in time series according to the processing operation described in the above embodiment, but also the processing capability of the device that executes the processing, or in parallel or individually as necessary. It is also possible to construct to execute processing.

  As is clear from the above description, the relay device of this embodiment has the following characteristics.

The relay apparatus according to the present embodiment includes an inflow band limiting unit (1) that discards input frames at a constant rate, and a frame storage unit (3) that stores frames that have passed through the inflow band limiting unit (1) in each queue. An output buffer (7, 8) that holds frames accumulated in each queue and outputs the held frames,
A queue management unit (5) for managing the accumulated information of the frames accumulated in each queue for each queue;
Depending on the accumulated information, the frame newly accumulated in each queue or the frame held in the output buffer (7, 8) is discarded, and the discard information for specifying the discarded discard frame is input to the inflow band. A disposal control unit (4) for notifying the limiting unit (1),
When receiving the discard information, the inflow band limiting unit (1) suppresses discard of the discard frame based on the discard information and supplements the discard frame with the suppressed frame.
In the above description, it has been described that the discard control unit (4) notifies the discard information to the inflow band limiting unit (1). However, in detail, in the relay device of the first embodiment shown in FIG. The write control unit (2) notifies the discard information to the inflow band limiting unit (1). Further, in the relay device of the third embodiment shown in FIG. 10, the output buffer (7, 8) notifies the inflow band limiting unit (1) of the discard information.

In the relay device of this embodiment,
Discard control unit (4) “In detail, frame write control unit; 2, or output buffer; 7, 8” notifies discard information including discard frame flow identification information to inflow band limiting unit (1) And
The inflow bandwidth limiter (1)
A discard flag for determining whether or not to discard a frame is managed for each flow identification information “corresponding to the flow ID” (corresponding to the table shown in FIG. 5),
When discard information is accepted, the discard flag corresponding to the flow identification information included in the discard information is changed to discard reject “corresponds to 1”, the input frame corresponding to the flow identification information is not discarded, and the discard frame is discarded. It is characterized by suppressing disposal of

In the relay device of this embodiment,
The inflow bandwidth limiter (1)
After the discard of the discard frame is suppressed, the discard flag is changed to discardable “corresponding to 0”, and the input frame is discarded at a certain rate.

In the relay device of this embodiment,
The inflow bandwidth limiter (1)
The discard flag is managed for each flow identification information as “0” that can be discarded in the initial state.
When discard information is accepted, the discard flag corresponding to the flow identification information included in the discard information is changed to discard rejection “1”, and the discard frame is discarded without discarding the input frame corresponding to the flow identification information. It is characterized by suppressing.

In addition, the relay device of this embodiment is
It has a setting means (not shown) for setting the discard flag as discard reject “1” in the initial state.

In the relay device of this embodiment,
The inflow bandwidth limiter (1)
A discard flag is added to a frame passing through the inflow band limiting unit (1) and output to suppress continuous discard of the discard frame.

Further, the relay device of this embodiment “corresponding to the relay device of the first embodiment”
It has a frame writing control unit (2) that writes a frame that has passed through the inflow band limiting unit (1) to the corresponding queue,
The disposal control unit (4)
In accordance with the accumulated information, a first condition discard instruction that conditionally discards a frame that is newly written to a predetermined queue, a first forced discard instruction that unconditionally discards a frame that is newly written to a predetermined queue, all Either the second condition discard instruction for discarding a frame to be newly written to the queue conditionally, or the second forcible discard instruction for unconditionally discarding the frame to be newly written to all queues, Notification control unit (2)
The frame writing control unit (2)
When the first condition discard instruction is accepted, the discard flag added to the frame to be newly written in the predetermined queue is referred to. When the discard flag is not discarded, the frame is not discarded and the frame is not discarded. If it is written in a predetermined queue and the discard flag is discardable, the frame is discarded, and the process of not writing the frame to the predetermined queue is performed.
When the first forced discard instruction is received, a frame to be newly written to the predetermined queue is unconditionally discarded, and the process of not writing the frame to the predetermined queue is performed.
When the second condition discard instruction is received, the discard flag added to the frame that has passed through the inflow band limiting unit (1) is referred to. When the discard flag is not discarded, the frame is not discarded, Write the frame to the corresponding queue, and if the discard flag can be discarded, discard the frame and perform processing that does not write the frame to the corresponding queue,
When the second forced discard instruction is received, the frame that has passed through the inflow band limiting unit (1) is unconditionally discarded, and the process that does not write the frame to the corresponding queue is performed. .

In the relay device “corresponding to the relay device of the third embodiment” in the present embodiment,
The output buffer (7, 8) is
It is provided individually for each queue, and each output buffer (7, 8) holds a frame corresponding to the queue of the output buffer (7, 8) itself,
The disposal control unit (4)
A means for determining an output buffer (7, 8) for notifying a condition discard instruction to conditionally discard a frame according to accumulated information, and notifying the determined output buffer (7, 8) for a condition discard instruction;
A means for determining an output buffer (7, 8) for notifying a forced discard instruction for unconditionally discarding a frame according to accumulated information, and notifying the determined output buffer (7, 8) for a forced discard instruction; Have
The output buffer (7, 8) is
When a condition discard instruction is accepted, the discard flag added to the frame held by the output buffer itself is referred. If the discard flag is not discarded, the discard flag is discarded without discarding the frame. In that case, discard the frame,
When a forced discard instruction is accepted, the frame held by the output buffer itself is unconditionally discarded.

  The present invention can be applied to an apparatus for leveling a used band.

It is a figure which shows the internal structural example of the relay apparatus of this embodiment. It is a figure which shows the operation example of the relay apparatus relevant to this invention, and is a figure which shows the case where frame discard is performed exceeding the use upper limit of queue. It is a figure which shows the operation example of the relay apparatus of this embodiment, and is a figure which shows the case where a frame discard is performed by exceeding the use upper limit of a queue. It is a figure which shows the comparative example of the frame rate of the relay apparatus relevant to this invention, and the relay apparatus of this embodiment. It is a figure for demonstrating the table which an inflow zone restriction | limiting part (1) hold | maintains. It is a figure which shows the processing operation example of frame discard determination. It is a 1st figure for demonstrating the specific example of the frame discard process in 1st Embodiment. It is a 2nd figure for demonstrating the specific example of the frame discard process in 1st Embodiment. It is a 3rd figure for demonstrating the specific example of the frame discard process in 1st Embodiment. It is a figure which shows the internal structural example of the relay apparatus of 2nd Embodiment. It is a 1st figure for demonstrating the specific example of the frame discard process in 2nd Embodiment. It is a 2nd figure for demonstrating the specific example of the frame discard process in 2nd Embodiment. It is a 3rd figure for demonstrating the specific example of the frame discard process in 2nd Embodiment. It is a figure which shows the example at the time of performing frame discard from the queue of the 2nd candidate. It is a figure which shows the system configuration example of the communication system of this embodiment.

Explanation of symbols

1 Inflow Band Limiting Unit 2 Frame Write Control Unit 3 Frame Accumulation Unit 4 Discard Control Unit 5 Queue Management Unit 6 Frame Read Control Unit 7, 8 Output Buffer
N1-N8 equipment 100 Relay equipment
B1-B3 bus

Claims (11)

Inflow band limiting means for discarding input frames at a certain rate;
Accumulating means for accumulating the frames that have passed through the inflow band limiting means in each queue;
An output means for holding the frames accumulated in each queue and outputting the held frames;
Management means for managing the accumulated information of the frames accumulated in each queue for each queue;
In accordance with the accumulated information, a frame newly accumulated in each queue or a frame held by the output means is discarded, and discard information for specifying the discarded discarded frame is designated as the inflow band limiting means. Control means for notifying to,
The inflow band limiting means is
When receiving the discard information, the communication apparatus suppresses discard of the same type of frame as the discard frame based on the discard information, and supplements the discard frame with the suppressed frame. The control means includes
Notifying the inflow band limiting means of the discard information including the flow identification information of the discard frame,
The inflow band limiting means is
A discard flag that determines whether or not to discard a frame is managed for each flow identification information,
When the discard information is received, the discard flag corresponding to the flow identification information included in the discard information is changed to discard, and the discard of the input frame corresponding to the flow identification information is not performed and the discard of the frame is suppressed. The communication apparatus according to claim 1, wherein: The inflow band limiting means is
3. The communication apparatus according to claim 2, wherein after discarding a frame of the same type as the discard frame is suppressed, the discard flag is changed to discardable and the input frame is discarded at a certain rate. The inflow band limiting means is
The discard flag is managed for each flow identification information as discardable in the initial state,
When the discard information is received, the discard flag corresponding to the flow identification information included in the discard information is changed to discard, and the discard of the input frame corresponding to the flow identification information is not performed and the discard of the frame is suppressed. The communication device according to claim 2 or 3, wherein   4. The communication apparatus according to claim 2, further comprising a setting unit that sets the discard flag as a discard reject in an initial state. The inflow band limiting means is
6. The method according to claim 2, wherein a discard flag is added to a frame that passes through the inflow band limiting unit and is output to suppress continuous discard of frames of the same type as the discard frame. The communication device described. Writing means for writing a frame that has passed through the inflow band limiting means into a corresponding queue;
The control means includes
In accordance with the accumulated information, a first condition discard instruction for conditionally discarding a frame to be newly written to a predetermined queue, a first forced discard instruction for unconditionally discarding a frame to be newly written to a predetermined queue, all A discard instruction of any one of a second condition discard instruction for discarding a frame newly written in the queue of the first condition and a second forced discard instruction for unconditionally discarding a frame newly written in all the queues; Notify the writing means,
The writing means includes
When the first condition discard instruction is accepted, a discard flag added to a frame to be newly written in a predetermined queue is referred to. When the discard flag is not discarded, the frame discard is not performed, When a frame is written to a predetermined queue and the discard flag is discardable, the frame is discarded, and the process of not writing the frame to the predetermined queue is performed.
When receiving the first forced discard instruction, unconditionally discards a frame to be newly written to a predetermined queue, and performs a process of not writing the frame to the predetermined queue,
When the second condition discard instruction is accepted, the discard flag added to the frame that has passed through the inflow band limiting unit is referred to. When the discard flag is not discarded, the frame discard is not performed. Write the frame to the corresponding queue, and if the discard flag is discardable, perform the process of discarding the frame and not writing the frame to the corresponding queue,
When the second forcible discard instruction is received, the frame discarding of the frame that has passed through the inflow band limiting unit is unconditionally performed, and processing for not writing the frame to the corresponding queue is performed. Item 7. The communication device according to Item 6. The output means includes
Provided individually for each queue, each output means holds a frame corresponding to the queue of the output means itself,
The control means includes
A means for notifying a condition discard instruction for conditionally discarding a frame according to the stored information, and a means for notifying the determined output means of a condition discard instruction;
Determining an output means for notifying a forced discard instruction for unconditionally discarding a frame according to the stored information, and notifying the determined output means for a forced discard instruction,
The output means includes
When the condition discard instruction is accepted, the discard flag added to the frame held by the output means is referred to. When the discard flag is not discarded, the discard flag is not discarded. If it can be discarded, discard the frame,
7. The communication apparatus according to claim 6, wherein when the forcible discard instruction is received, the frame discarding of the frame held by the output unit is performed unconditionally. A communication system comprising a plurality of devices and a relay device that relays a frame transmitted by the device,
The relay device is
A communication system, comprising the communication device according to claim 1. Inflow band limiting means for discarding input frames at a fixed rate, storage means for storing frames that have passed through the inflow band limiting means in each queue, holding frames stored in each queue, and holding the stored frames A control method performed by a communication device having output means,
Managing the accumulated information of the frames accumulated in each queue for each queue;
In accordance with the accumulated information, a frame newly accumulated in each queue or a frame held by the output means is discarded, and discard information for specifying the discarded discarded frame is designated as the inflow band limiting means. A process of notifying
When the inflow band limiting unit accepts the discard information, based on the discard information, suppressing discard of the same type of frame as the discard frame, and supplementing the discard frame with the suppressed frame; The control method characterized by having. Inflow band limiting means for discarding input frames at a fixed rate, storage means for storing frames that have passed through the inflow band limiting means in each queue, holding frames stored in each queue, and holding the stored frames A control program to be executed by a communication device having output means,
A process of managing the accumulated information of the frames accumulated in each queue for each queue;
In accordance with the accumulated information, a frame newly accumulated in each queue or a frame held by the output means is discarded, and discard information for specifying the discarded discarded frame is designated as the inflow band limiting means. Processing to notify
When the inflow band limiting unit receives the discard information, based on the discard information, a process of suppressing discard of the same type of frame as the discard frame and supplementing the discard frame with the suppressed frame; Is executed by the communication device.

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