JP2005101852A - Frame control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of controlling the handling of frames exceeding the minimum guaranteed bandwidth of each user to be fair among users while suppressing an increase in cost.
SOLUTION: Based on a minimum guaranteed bandwidth set for each user and a control bandwidth larger than the minimum guaranteed bandwidth set according to the minimum guaranteed bandwidth, the minimum guaranteed bandwidth is exceeded and the control bandwidth is Different markings are applied to the frames that do not exceed the frames that exceed the control bandwidth, and the frames of each marked user are accumulated. Depending on the amount of accumulated frames, different types of marking are handled differently. I do.
[Selection] Figure 1

Description

  The present invention relates to a technique for controlling the transmission band of a frame for each user, and more particularly, to a technique for making the handling of frames exceeding the minimum guaranteed bandwidth of each user fair among users in a frame switch.

  In recent years, QoS (Quality of Service) is known as a technique for reserving a band for a specific communication on a network and guaranteeing a constant communication speed. QoS is an important technology for services that do not allow delay and stop of communication, such as real-time delivery of voice or moving images (radio / TV type service) or videophone.

  In addition, CoS (Class of Service) is known as one of the technologies for ensuring communication quality and securing bandwidth. In CoS, priority is set for a frame, and the frame switch changes the handling of the received frame according to the priority.

  FIG. 8 is a block diagram showing a configuration of the frame switch 100. The frame received by the frame switch 100 is input to the forwarding unit 120 via the ingress interface (input interface) 111 of the interface unit 110 corresponding to the incoming route. The forwarding unit 120 performs switching (forwarding) processing based on a frame destination or the like. The frame after the forwarding process is output from the egress interface (output interface) 112 of the interface unit 110 corresponding to the route of the frame.

  Each ingress interface 111 and egress interface 112 have a configuration as shown in FIG. 9 when CoS is performed in the frame switch 100. FIG. 10 shows the configuration of the traffic conditioner 132 provided in the ingress interface 111. The traffic conditioner 132 includes a frame flow rate measuring unit (meter) 135 and a marking processing unit (marker and dropper) 136.

  In the frame switch 100, a frame input to the ingress interface 111 is recognized as a different flow for each user by the first classifier 131 by referring to a priority bit (classification bit), a VLAN (Virtual LAN) value, or the like in the frame. . The traffic conditioner 132 measures the flow rate of the frame with respect to the flow for each user, and performs marking and discard processing according to the measurement result. Specifically, a minimum guaranteed bandwidth (Committed Rate: CR) and a maximum allowable bandwidth (Peak Rate: PR) for a frame are defined in advance for each user (see FIG. 11). When the flow rate of the frame is measured, the CR and PR of the user are referred to, and the frames that do not exceed the CR are marked with “G“ Green ””, exceeding the CR and exceeding the PR. “Y“ Yellow ”” marking is applied to the frames that do not exist, and “R“ Red ”” marking is applied to the frames that exceed the PR, and the marking processing unit 136 performs “G”. The frame (G frame) marked with "Y" and the frame (Y frame) marked "Y" are output to the forwarding unit 120, and the frame (R frame) marked "R" Discard.

  “PR (Peak Rate)” indicates a rate (transmission band) that exceeds this value and is not allowed to flow a frame. For this reason, the frame exceeding “PR” is marked with “R“ Red ””, and the R frame is discarded by the marking processing unit 136 or is discarded by a switch unit (not shown). The

  “CR (Committed Rate)” indicates a rate (transmission band) at which frame transfer is guaranteed up to this value. For this reason, “Green” marking is performed on frames that do not exceed “CR”. The G frame marked “Green” is guaranteed bandwidth (transfer) in the output buffer at the subsequent stage.

  In addition, the marking processing unit 136 performs “Yellow” marking on a frame that is “Peak Rate” or less and “Committed Rate” or more. The Y frame marked “Yellow” is normally transferred in the output buffer section at the subsequent stage, but is discarded when it is congested.

  The frame output from the forwarding unit 120 enters the output buffer unit 134 via the second classifier 133 of the egress interface 112 of the interface unit 110. In the output buffer unit 134, the buffer control unit 140 writes each frame input from the second classifier 133 toward the buffer of the corresponding class according to the class identification result. However, in each of the buffers 137 to 139, a first threshold value (threshold value B) and a second threshold value (threshold value A) for the accumulated amount of frames in the buffer are set, and the buffer control unit 140 is set for each buffer. Based on the first and second threshold values, the following frame writing control is performed (see FIG. 13). When storing a frame (for example, class A), the buffer control unit 140 compares the threshold A and threshold B of the buffer (buffer 137) corresponding to the class of the frame with the accumulated amount of frames in the buffer. For example, the following control is performed. When the amount of frames stored in the buffer 137 is equal to or less than the threshold B, the buffer control unit 140 writes both the Y frame and the G frame in the buffer 137. When the accumulated frame amount is greater than or equal to the threshold B and less than or equal to the threshold A, the buffer control unit 140 discards the Y frame and writes the G frame. When the accumulated frame amount is equal to or greater than the threshold A, the buffer control unit 140 discards all the frames “G” and “Y”. With such write control, bandwidth guarantee corresponding to CR is realized. Each frame written in each of the buffers 137 to 139 is read from the buffer by the buffer control unit 140 by read control in consideration of characteristics between classes, and is output from the interface unit 110.

  As a prior art related to the invention of the present application, a technique related to a router apparatus that performs traffic guarantee and separation flexibly (see, for example, Patent Document 1), or a technique that enables frame discard with a small amount of processing (for example, a patent) Reference 2).

JP 2002-44139 A JP 2001-111556 A

By the way, the conventional techniques as described above have the following problems. That is, in the prior art, write control to the buffer for each class, that is, discard control is performed based only on the type of marking applied to the frame, and it is an object of determination which user the frame belongs to. It wasn't. In other words, changing the frame discard rate for each user has not been performed.
For this reason, for example, when there are two users with the same PR and CR setting values (for example, specified by the VLAN value), one user has more “Yellow” frames (Y frames than the other user). ), The Y frame of one user passes through the frame switch 100 more than the Y frame of the other user. That is, a phenomenon occurs in which the Y frame of one user passes at a certain rate, but the Y frame of the other user becomes difficult to pass through the frame switch 100. Further, in the conventional technology, when a certain user transmits a large amount of Y frames, the Y frame of this user sets a higher CR than this user, but the transmission amount of Y frames is higher than that user. There was a phenomenon in which the frame switch 100 passed more than Y frames of other few users. Such a phenomenon is not preferable from the viewpoint of fairness of frame transfer between users.

  As a method for solving the above-mentioned problem, for example, as shown in FIG. 15, there is a method in which an intra-class buffer is further divided for each user (for example, VLAN), and reading is performed at a rate allocated to each VLAN. is there. However, in such a method, since buffers corresponding to the number of VLANs must be prepared, there is a problem that the hardware of the frame switch increases, thereby increasing the cost.

  The present invention has been made in view of the above matters, and can control the handling of frames exceeding the minimum guaranteed bandwidth of each user to be fair among users while suppressing an increase in cost. Providing technology is an issue to be solved.

In order to solve the above problems, the present invention employs the following means.
The present invention provides a measuring means for measuring a flow rate of a frame for each user, a minimum guaranteed bandwidth set for each user frame, and a minimum guaranteed bandwidth set according to the minimum guaranteed bandwidth. Marking means for marking differently on frames that exceed the minimum guaranteed bandwidth and do not exceed the control bandwidth based on a large control bandwidth and frames that exceed the control bandwidth; and The frame control device includes a buffer for storing frames and a buffer control unit that performs different handling for frames with different marking types according to the amount of frames stored in the buffer.

  In the present invention, the control bandwidth of each user is, for example, a value obtained by increasing the minimum guaranteed bandwidth of each user by a predetermined ratio common to the users.

  Alternatively, the control bandwidth of each user is a value obtained by adding a predetermined bandwidth common to the users to the minimum guaranteed bandwidth of each user.

  Alternatively, the control bandwidth of each user is a value obtained by reducing the maximum allowable bandwidth set for each user by a predetermined ratio common to users within a range larger than the minimum guaranteed bandwidth.

  Alternatively, the control bandwidth of each user is in a range larger than the minimum guaranteed bandwidth and smaller than the maximum allowable bandwidth based on the minimum guaranteed bandwidth and the maximum allowable bandwidth set for each user and a predetermined function common among the users. This is the value obtained.

  As described above, according to the present invention, it is possible to change the handling of the frame depending on whether or not the control bandwidth set in accordance with the minimum guaranteed bandwidth of each user is exceeded. Therefore, if the control bandwidth of each user is set so that the bandwidth between the minimum guaranteed bandwidth and the control bandwidth is fair among users, the handling between users can be fair.

  The conditions (calculation formulas, etc.) for calculating the control band may be common among users or may be different. For example, a bandwidth obtained by increasing the minimum guaranteed bandwidth set for each user by a predetermined ratio may be used as the control bandwidth, and each control bandwidth is set by adding a fixed value to the minimum guaranteed bandwidth for each user. May be.

  Preferably, in the marking means of the present invention, for each user's frame, a first marking is applied to a frame that does not exceed the minimum guaranteed bandwidth of the user, and a frame that exceeds the minimum guaranteed bandwidth and does not exceed the control bandwidth. The second marking is applied, the third marking is applied to the frames exceeding the minimum guaranteed bandwidth and the control bandwidth, and a threshold for the amount of buffer frames stored in the buffer is set. For each frame to be written to the buffer, if the accumulated amount of the frame does not exceed the threshold, the frames with the first to third markings are written to the buffer, If the accumulated amount exceeds the threshold, the frames with the first and second markings are written to the buffer. It is seen, and the third marking is discarded without writing the frame has been subjected to the buffer.

  Preferably, the marking means according to the present invention applies, for each user's frame, a first marking to a frame that does not exceed the minimum guaranteed bandwidth of the user, and exceeds the minimum guaranteed bandwidth and does not exceed the control bandwidth. The frame is subjected to the second marking, the third marking is applied to the frame exceeding the minimum guaranteed bandwidth and the control bandwidth, and the buffer has a threshold value for the amount of frames stored in the buffer. For each frame to be written to the buffer, if the accumulated amount of the frame does not exceed the threshold value, the frames with the first to third markings are written to the buffer, and the frame If the accumulated amount exceeds the threshold, each frame with the first and second markings is stored in the buffer. It can included, and for a frame in which the third marking is applied to write the rest was discarded by a predetermined ratio according to the accumulated amount.

  In this way, if the threshold is exceeded, frames that exceed the control bandwidth of each user are treated (discarded) in the same way between users, thus ensuring fairness among users with respect to frame discard. Is possible.

  Further, the present invention provides a measuring means for measuring the flow rate of a frame for each user, a minimum guaranteed bandwidth set for each user frame, and the minimum guaranteed bandwidth set according to the minimum guaranteed bandwidth. Based on a plurality of control bands that are larger than the maximum guaranteed bandwidth, the amount that does not exceed the minimum guaranteed bandwidth, the amount that exists between the minimum guaranteed bandwidth and the smallest control bandwidth, the amount that exists between control bands, and the maximum control bandwidth Marking means for performing different marking on each of the excess frames, a buffer for storing the marked frames of each user, and a buffer in which a threshold for a storage amount of frames prepared for at least the number of the control bands is set; Depending on the relationship between the buffer frame accumulation amount and the plurality of threshold values, different handling is performed for frames with different marking types. It can be specified as a frame control device which includes a Ffa controller.

  In this way, since the control band is set in a plurality of stages and the threshold value of the buffer frame accumulation amount corresponding to this is prepared, it is possible to perform fine control on the handling of frames.

In addition, the present invention has a plurality of functions for obtaining the control bandwidth from the minimum guaranteed bandwidth of the user, and calculates the control bandwidth of each user with a function using a parameter corresponding to the amount of frames stored in the buffer. It can comprise so that it may further have a calculating part.
In this way, for example, when the accumulation amount is small, the control band can be increased, and the control band can be decreased as the accumulation amount increases. In other words, the control band can be increased or decreased according to the traffic volume.

  According to the present invention, it is possible to make the handling of frames that exceed the minimum guaranteed bandwidth of each user fair between users while suppressing an increase in cost.

  A frame switch according to an embodiment of the frame control device of the present invention will be described below with reference to the drawings. The frame switch according to the present embodiment includes a plurality of interfaces that perform input / output processing connected to a plurality of computers such as servers and personal computers (PCs). In addition, the switch according to the present embodiment transmits a frame transmitted from a connected computer to another computer, based on a destination address attached to the frame, and transmits to the interface connected to the other computer (forwarding ) Process.

  Then, in addition to the above switching processing, the frame switch according to the present embodiment performs CoS control in which a priority is set for the frame and the handling of the received frame is changed according to the priority. In the frame switch according to the present embodiment, when performing the CoS control, the traffic conditioner performs frame marking according to the flow rate of the frame for each user flow. Based on the marking of the frame, the frame switch according to the present embodiment controls the writing of the frame to the output buffer according to the amount of the frame accumulated in the output buffer. Thus, according to the frame switch according to the present embodiment, it is possible to eliminate the unfairness of the flow rate of frames passing through the frame switch between users, that is, the transmission band.

<First Embodiment>
Next, the frame switch according to the present embodiment will be described. This frame switch can apply the same configuration as the conventional configuration as shown in FIGS. However, the configuration of the traffic conditioner in the ingress interface of the interface unit and the buffer control unit of the output buffer in the egress interface are different from those of the conventional frame switch.

  The frame switch according to the present embodiment includes a forwarding unit and a plurality of interface units connected to the forwarding unit as shown in FIG. Each interface unit includes an ingress interface (input interface) and an egress interface (output interface).

  The frame received by the frame switch is input to the forwarding unit via the ingress interface of the interface unit corresponding to the entry route. The forwarding unit performs a switching (forwarding) process based on the destination of the frame and outputs the frame to the interface unit corresponding to the route of the frame. In the output destination interface unit, the frame is output via the egress interface.

  As shown in FIG. 9, the ingress interface includes a first classifier and a traffic conditioner. The egress interface includes a second classifier and an output buffer unit.

  Each block of the frame switch 100 according to the present embodiment corresponds to the means of the frame control device of the present invention as follows. That is, the buffer of the frame control device corresponds to the output buffer unit 134 of the frame switch 100. Further, the buffer control unit of the frame control device corresponds to the buffer control unit 140 of the present frame switch 100.

FIG. 1 is an example of a functional block diagram showing a device configuration of a traffic conditioner 10 according to the present embodiment. The traffic conditioner 10 is provided in place of the traffic conditioner 132 in the prior art.

  In FIG. 1, a traffic conditioner 10 includes a frame flow measurement unit (meter) 11, a peak rate (Peak Rate) storage unit 12, a minimum guaranteed bandwidth (Committed Rate) storage unit 13, an NR (Next Rate) generation unit 14, A marking processing unit (marker & dropper) 15 is provided.

  Each block of the traffic conditioner 10 corresponds to the means of the frame control apparatus of the present invention as follows. That is, the measurement means of the frame control device corresponds to the flow rate measurement unit 11 of the traffic conditioner 10. Further, the marking means of the frame control device corresponds to the marking processing unit 15 of the traffic conditioner 10. Further, the calculation unit of the frame control device corresponds to the NR generation unit 14 of the traffic conditioner 10.

  The traffic conditioner 10 determines the frame flow rate for frames for each flow recognized as different flows for each user by the first classifier referring to the priority bit (classification bit), VLAN (Virtual LAN) value, etc. in the frame. Measurement, marking on the frame according to the measurement result, and discarding of the frame are performed.

  Of the components of the traffic conditioner 10, the flow rate measuring unit 11 measures the transmission band of the frame for each user flow recognized by the first classifier.

  FIG. 2 is a conceptual diagram of the flow rate comparison used for the marking process by the flow rate measuring unit 11 of the traffic conditioner 10. The flow rate measuring unit 11 compares the measured flow rate with the flow rate based on numerical values previously defined for each flow. At this time, the flow rate measuring unit 11 corresponds to the flow, that is, the user, the maximum allowable bandwidth (Peak Rate: PR) stored in the peak rate storage unit 12 and the minimum guaranteed bandwidth ( Refer to Committed Rate (CR) and compare with the flow rate of the above flow.

  As described above, “Peak Rate” indicates a transmission band (rate) that is not allowed to flow beyond this value. “Committed Rate” indicates a transmission band (rate) in which frame transfer is guaranteed up to this value.

  The flow rate measurement unit 11 compares the NR value generated by the NR generation unit 14 (corresponding to the control band of the present invention) with the flow rate of the frame for each measured flow. The NR value is generated by the NR generation unit 14 from the minimum guaranteed bandwidth value stored in the minimum guaranteed bandwidth storage unit 13 by calculation.

  As an NR calculation method by the NR generation unit 14, for example, a method of calculating a value of a predetermined percentage H% increase with respect to each user's CR, a predetermined value P [bps] (bandwidth) is added to each user's CR And a method of calculating using a predetermined function based on the CR of each user. Note that the NR value may be dynamically generated by calculation as described above, and a preset NR is statically prepared on the storage device and used as necessary. May be.

  The marking processing unit 15 receives a flow flow comparison result from the flow measurement unit 11. Then, based on the comparison result, the marking processing unit 15 divides individual frames into frames that do not exceed CR, frames that exceed CR and do not exceed NR, frames that exceed NR and do not exceed PR, and PR. Separate and mark the frames beyond.

That is, the marking processing unit 15 applies “G“ Green ”” marking, which corresponds to the first marking of the present invention, to the frames not exceeding CR. In addition, the frame which does not exceed NR is marked with “Y1“ Yellow1 ”” corresponding to the second marking of the present invention, and the marking processing unit 15 exceeds NR and does not exceed PR. The minute frame is marked with “Y2“ Yellow2 ””, which corresponds to the third marking of the present invention, and the marking processing unit 15 sets “R“ Red ”” to the frame exceeding the PR. Mark.

  Then, the marking processing unit 15 reads the frame with the “G” marking (G frame), the frame with the “Y1” marking (Y1 frame), and the frame with the “Y2” marking. Output to the forwarding unit 120. Further, the marking processing unit 15 discards the frame (R frame) on which the “R” marking is applied. Note that the discarding of the R frame may be performed by, for example, a forwarding unit or an egress interface.

  In the present invention, the NR (control band) is a value for classifying frames (frames corresponding to Y frames in the prior art) that exceed the CR of each user and do not exceed the PR. In the control part 16 (refer FIG. 3), it prepares so that different handling may be performed depending on whether this control band value is exceeded. Then, as will be described later, the buffer control unit 16 handles the frames (Y1 frame, Y2 frame) classified according to whether or not the NR is exceeded according to the accumulation amount of the frame of the buffer. , A frame corresponding to the Y frame is treated fairly among users. In the present embodiment, the buffer control unit 16 performs control such that Y1 frames that do not exceed NR are written to the buffer and Y2 frames that exceed NR are discarded according to the frame accumulation amount. The amount of Y1 frame written to the buffer at this time is defined within a range that is not unfair among users. The threshold value that determines whether this range is inside or outside is the control band in the present invention.

  As described above, when the buffer is congested, control is performed such that the Y1 frame is written into the buffer and the Y2 frame is discarded. For this reason, the traffic conditioner 10 can increase or decrease the ratio between the Y1 frame and the Y2 frame determined in advance for each flow (in other words, the discard rate of the Y frame for each user) for each user. The Y2 frame is accumulated in the buffer when the buffer is not congested, but is discarded when the buffer is congested.

  As described above, in the frame switch according to the present embodiment, the buffer control unit 16 of the output buffer unit refers to the frame accumulation amount in each buffer based on the marking performed by the marking processing unit 15 of the traffic conditioner 10. Thus, different processing is performed on each of the G, Y1, and Y2 frames to control writing / discarding to each buffer.

  The forwarding unit 120 that has received the frame marked by the traffic conditioner 10 performs frame forwarding (switching) processing. For example, when the frame switch 100 is a layer 3 switch, the IP address is referred to and forwarding is performed. For example, when the frame switch 100 is a layer 2 switch, the forwarding unit 120 performs forwarding with reference to the MAC address.

  The frame output from the forwarding unit is input to the second classifier of the egress interface of the interface unit. The second classifier identifies the class set in the frame based on a predetermined identifier set in the frame (for example, the value of the “CoS” field).

<Output buffer control>
Next, processing in the output buffer unit will be described. The output buffer unit according to the present embodiment includes a plurality of buffers prepared for each class classified by the second classifier as shown in FIG. 12, and a buffer control unit that performs frame write / read control for each buffer. 16. The buffer control unit 16 performs frame writing / reading control for each class, that is, for each buffer.

  FIG. 3 is an explanatory diagram of buffer control by the buffer control unit 16. However, since the buffer control unit 16 performs similar control on the buffers of each class, FIG. 3 shows a buffer 18 of a certain class (for example, class A) as an example of the buffer.

  The frame identified by the second classifier is output toward the buffer corresponding to the class of the identification result. The buffer control unit 16 performs write control on a frame to be written to each buffer (a frame to be written) according to the amount of frames stored in each buffer. This is the same as in the prior art. The frame reading control by the buffer control unit 16 is the same as in the conventional technique.

  However, in the present embodiment, threshold values B1 and B2 are set in advance in the buffer 18 as threshold values for changing the content of the write control in accordance with the buffer accumulation amount. Further, a threshold A is set in the buffer 18 as an upper limit value of the frame buffer accumulation amount. However, the threshold value A is an upper limit value and does not necessarily need to be set.

  Then, the buffer control unit 16 performs frame writing control on the buffer 18 based on the marking type set to the writing target frame and the frame accumulation amount as follows.

  First, when the accumulation amount of frames in the buffer 18 is equal to or less than the threshold value B1, the buffer control unit 16 writes the G frame, the Y1 frame, and the Y2 frame in the buffer 18. On the other hand, when the frame accumulation amount of the buffer 18 is not less than the threshold B1 and not more than B2, the buffer control unit 16 writes the G frame and the Y1 frame in the buffer 18 and discards the Y2 frame. On the other hand, when the frame accumulation amount is not less than the threshold B2 and not more than the threshold A, the buffer control unit 16 writes the G frame in the buffer 18 and discards the Y1 and Y2 frames. When the accumulated amount of frames is equal to or greater than the threshold A, the buffer control unit 16 discards all frames.

  As described above, when the frame accumulation amount is between the threshold values B1 and B2, the buffer control unit 16 performs different handling for the Y1 frame and the Y2 frame. That is, of the frames (corresponding to Y frames) existing between the CR and PR of each user, the portion that does not exceed NR is written to the buffer, and the portion that exceeds NR is discarded. In other words, between the threshold values B 1 and B 2, a frame with the Y 1 marking of each user is written, and the frame with the Y 2 marking is discarded even though the buffer 18 has a space. At this time, the NR is set so that the band to which the Y1 marking is applied does not feel unfair from the viewpoint of other users. For example, the NR is set so that the G and Y1 markings are applied to the amount (for example, 120% of the CR) corresponding to the CR set by each user through a contract with the network service provider. This ensures fairness among users for handling Y frames. The above-described write control for the buffer is performed in the same manner for other classes of buffers.

<Second Embodiment>
Next, in the frame switch 100 according to the present embodiment, the frame write control stored in the output buffer based on the marking performed by the traffic conditioner 10 is changed to the write control of the first embodiment, The case where it is performed using RED (Random Early Detection) control will be described as a second embodiment.

  FIG. 14 is a graph showing the concept of RED control used for write control in the buffer control unit 16. In RED control, when the threshold value is exceeded, all Y frames are not discarded, but out of the input (write target) frames, a predetermined percentage (%) according to the frame accumulation amount at that time Discard the frame. In the RED control, the frame discard rate (%) is increased when the frame accumulation amount in the buffer increases thereafter.

  The second embodiment is different from the first embodiment only in the frame writing control by the buffer control unit 16. In the second embodiment, as in the first embodiment, threshold values B1, B2, and A are set for each buffer for each class.

  The buffer control unit 16 performs the following write control based on the marking type of each frame and the threshold of the buffer accumulation amount. When the frame accumulation amount for the buffer 18 is not less than the threshold B1 and not more than B2, the buffer control unit 16 writes G and Y1 frames to the buffer 18 and discards them while increasing the ratio of discarding Y2 frames. At this time, the buffer control unit 140 increases the discard ratio at a predetermined rate according to the buffer accumulation frame amount. When the buffer accumulation amount of the frame of the buffer 137 is greater than or equal to the threshold B2 and less than or equal to the threshold A, the buffer control unit 140 writes the G frame to the buffer 137 and sets the Y1 and Y2 frames to a predetermined amount according to the buffer accumulation frame amount. Discard while increasing the discard rate by rate. The predetermined ratio is not limited to a specific numerical value, and various numerical values can be set.

FIG. 4 is an example of a conceptual diagram showing output buffer control by RED control of the frame switch 100 according to the present embodiment. As can be seen from FIG. 4, since the threshold for starting RED control is different between the Y1 frame and the Y2 frame, the change in the frame discard rate of RED control is different.
As described above, according to the second embodiment, when the threshold value B1 is exceeded, all Y2 frames are not discarded after that, but Y2 frames are discarded at a constant rate proportional to the frame accumulation amount by RED control. To do. After that, when the threshold value B2 is exceeded, the Y1 frame is discarded at a constant rate proportional to the frame accumulation amount. Even if such RED control is introduced, the fairness of the band exceeding the CR can be ensured by different handling between Y1 and Y2 with NR as the boundary.

<Third Embodiment>
Next, an example of switching processing for a frame from a computer by the frame switch according to the present embodiment will be described. The third embodiment is a specific example of the first embodiment.
FIG. 5 is a functional block diagram showing the configuration of the frame switch 30 according to the third embodiment. The frame switch 30 is shown by extracting a part according to the embodiment of the present invention from the configuration of the frame switch as shown in FIG. Specifically, two ingress interfaces 4a and 4b, a forwarding unit 2 and an egress interface 5 among the plurality of interface units are shown.

Each ingress interface 4a and 4b includes traffic conditioners 10a and 10b similar to the traffic conditioner 10 described in the first embodiment. Frames from individual computers belonging to the VLAN are input to the ingress interfaces 111a and 111b. Specifically, frames from each VID (VLAN-ID) = 1, 2 are input to the ingress interface 4a. Also, frames from VID = 3, 4 are input to the ingress interface 111b. The destinations of the frames with VID = 1 to 4 are the same in the frame switch 30, and the forwarding unit 2 sends the frames set with VID = 1 to 4 from the ingress interfaces 4 a and 4 b to the egress interface 5. To enter.

  In the egress interface 5, input frames are classified by the second classifier 7 (classifier B) and input to the output buffer unit 8. Each input frame is a frame to be written to the corresponding class of buffer. The egress interface 5 has a plurality of buffers prepared for each class, and frame write / read control for each buffer is performed by a buffer control unit similar to the buffer control unit 16 (not shown).

  Here, each frame for which VID = 1, 2, 3, 4 is set is a class A frame and is a frame to be written to the buffer 8a corresponding to the class A. For these frames, the buffer control unit uses thresholds A, B1, and B2 for the amount of accumulated frames and markings (G, Y1, and Y2) applied to the frames as shown in the first embodiment. Based on this, frame writing control is performed.

  FIG. 6 is a table showing individual VIDs in this processing example, that is, the minimum guaranteed bandwidth value CR for each user, and the calculated value NR. FIG. 6 shows individual VIDs, set minimum guaranteed bandwidth CR, and NR obtained by calculation. In this processing example, “NR = 120% of CR” is defined. For example, in FIG. 6, the minimum guaranteed bandwidth for VID = 1 is 30 Mbps, and the NR is 36 Mbps. This rule (function) is commonly applied to users (VID = 1 to 4).

  Then, the traffic conditioners 10a and 10b perform marking as follows according to the CR and NR of each VID. When the flow rate measurement unit 11 measures a band exceeding “Peak Rate”, the traffic conditioners 10a and 10b perform “Red” marking on the frame. In addition, each traffic conditioner 10a, 10b performs “Green” marking for frames below “CR”. Further, the traffic conditioners 10a and 10b perform “Yellow1” marking on frames of “CR” or more and “NR” or less. Further, the traffic conditioners 10a and 10b perform “Yellow2” marking on the frames from “NR” to “Peak Rate”. Frames marked with “Green”, “Yellow 1”, and “Yellow 2” are defined as G frame, Y1 frame, and Y2 frame, respectively.

The buffer control unit of the output buffer unit 8 performs the following writing control on the writing target frame on which the marking is performed as described above, based on the predetermined thresholds A, B1, and B2.
When the accumulated amount of frames in the buffer 8a is equal to or less than the threshold value B1, the buffer control unit writes the G frame, Y1 frame, and Y2 frame in the buffer 8a. If the accumulated amount of frames in the buffer 8a is not less than the threshold B1 and not more than B2, the buffer control unit writes the G frame and Y1 frame to the buffer 8a and discards the Y2 frame. When the frame accumulation amount of the buffer 8a is not less than the threshold value B2 and not more than the threshold value A, the buffer control unit writes the G frame to the buffer 137 and discards the Y1 frame and the Y2 frame. When the frame accumulation amount in the buffer 8a is equal to or greater than the threshold A, the buffer control unit 140 discards all frames.

  The frame switch 30 having the above configuration has a frame input with each VID = 1 to 4 set, and the output buffer unit 8 also receives a frame from another interface unit (not shown). Assume that For this reason, it is assumed that the output buffer unit 8 is in a light congestion state.

  FIG. 7 is a table showing the flow rate of each VID frame in the output buffer unit 8. In FIG. 7, the minimum guaranteed bandwidth CR corresponding to each VID (VID = 1 to 4), the NR obtained by calculation, the input flow rate of the assumed frame, and the writing control by the buffer control unit of the frame switch 30 were performed. The output flow rate of the frame in this case and the output flow rate (by the control of the prior art) when the writing control is not performed are shown.

In the example shown in FIG. 7, frames exceeding the CR of each VID (user) are input from each VID, as shown in the assumed input flow rate. For example, the input flow rate of VID = 2 is 50 Mbps, which is 10 times CR.
When the flow control of the frame according to the present invention is not performed in the situation of the input flow as described above, the output flow control is performed based on the total input flow of the frames from all the VIDs. In this processing example, the output flow rate from the buffer 8a for each VID is obtained by the following calculation formula.

[Output flow rate for each VID] = [Setting CR] + ([Input flow rate for each VID]-[Setting CR]) x F
In this processing example, F = 50%.

  For this reason, for example, the output flow rate from VID = 2 is 27 Mbps, which corresponds to a flow rate of 540% with respect to CR. On the other hand, the output flow rate from VID = 4 flows 45 Mbps, which corresponds to a flow rate of 112% with respect to CR. As described above, when the flow rate control is not performed (according to the prior art), a difference (unfairness) in actual output flow rate with respect to the band CR guaranteed in advance occurs between VIDs, that is, users.

  On the other hand, when the flow control according to the present invention is performed, the output flow rate for each VID is a flow rate corresponding to 120% of CR defined as NR. Therefore, according to the flow rate control by the frame switch 30, according to the CR set for each VID (user), the band that does not feel unfair from the viewpoint of other VIDs (users) is equal to or more than CR. Therefore, each user does not have to feel unfair in handling the frames exceeding the CR of each user. As described above, according to the third embodiment, when the control using CoS (dif-serv or the like) is performed by the frame switch, it is possible to eliminate the unfairness of the transmission band that occurs between users.

  The first to third embodiments are realized by adding a configuration for calculating or storing NR to the conventional frame switch and modifying the configuration of the marking processing unit and the buffer control unit. Can do. For this reason, in implementing the present invention, it is not necessary to change the configuration or add hardware. Therefore, it is possible to suppress an increase in cost for eliminating unfairness.

<Modification>
The frame switch according to the present embodiment can be modified as follows, for example.
For example, a traffic conditioner may generate a plurality of control band values NR (1 to n). In this case, the marking processing unit performs three or more markings Y1 to Yn + 1 for frames of CR or more and PR or less. That is, different markings Y1 to Yn + 1 are applied to the frame between CR and PR between CR and the minimum NR, between NR, and between the maximum NR and PR. Then, three or more threshold values B1 to Bn + 1 corresponding to the markings Y1 to Yn1 are set for the buffer, and the buffer control unit performs frame writing control with three or more markings and three or more threshold values B1 to B1. Control based on Bn + 1. As described above, by having a plurality of control switching points, finer flow rate control is possible.

In the present embodiment, the control band NR is generated from the minimum guaranteed band CR. However, for example, the NR generated by the traffic conditioner 10 may be calculated and generated from the maximum allowable band PR. By generating NR from the maximum allowable bandwidth PR, the flow control can be performed for each user's maximum allowable bandwidth
Discard processing can be performed in association with NR.

  Further, the control band NR may be generated from the minimum guaranteed band CR and the maximum allowable band PR. For example, NR is calculated by adding the minimum guaranteed bandwidth and the maximum allowable bandwidth and then dividing by 2 as a predetermined function, and introducing CR and PR of each user into the function.

  Further, the parameter of the function for generating NR may be changed according to the frame accumulation amount of the buffer. When changing the parameter of the NR generation function, the traffic conditioner calculation unit is configured to receive the frame accumulation amount from the output buffer unit as needed. The measuring unit is configured to change the NR used in the measurement and comparison of the frame flow rate according to the frame accumulation amount. For example, the initial value of the NR generation function is set to “20% increase in CR”. Then, the NR generation function is changed to “10% increase in CR”, “30% increase in CR”, or the like according to the frame accumulation amount of the buffer. In this case, for example, control can be performed such that the NR value decreases as the frame accumulation amount increases, and the NR value increases as the frame accumulation amount decreases.

  As described above, by changing the parameter of the function that generates NR in accordance with the frame accumulation amount of the buffer, fine control reflecting the buffer status is possible. Also, a plurality of NR arithmetic expressions may be prepared, and the arithmetic expression may be changed according to the frame accumulation amount.

<Others>
The present invention can be specified as follows.

 (Appendix 1) Measuring means for measuring the flow rate of a frame for each user, the minimum guaranteed bandwidth set for each user, and the minimum guaranteed bandwidth set according to this minimum guaranteed bandwidth for each user's frame Marking means for marking differently on frames that exceed the minimum guaranteed bandwidth and do not exceed the control bandwidth based on a large control bandwidth and frames that exceed the control bandwidth; and A frame control device (1) comprising: a buffer for storing frames; and a buffer control unit that performs different handling for frames with different marking types according to the amount of frames stored in the buffer.

(Supplementary note 2) The frame control device according to supplementary note 1, wherein the control bandwidth of each user is a value obtained by increasing the minimum guaranteed bandwidth of each user by a predetermined ratio common to the users.

(Supplementary note 3) The frame control device according to supplementary note 1, wherein the control bandwidth of each user is a value obtained by adding a predetermined bandwidth common among users to the minimum guaranteed bandwidth of each user.

(Supplementary Note 4) The control bandwidth of each user is a value obtained by reducing the maximum allowable bandwidth set for each user by a predetermined ratio common to the users within a range larger than the minimum guaranteed bandwidth. The frame control device according to appendix 1.

(Supplementary Note 5) The control bandwidth of each user is larger than the minimum guaranteed bandwidth and smaller than the maximum allowable bandwidth based on the minimum guaranteed bandwidth and the maximum allowable bandwidth set for each user and a predetermined function common among the users. The frame control device according to appendix 1, which is a value obtained in a range.

(Additional remark 6) The said marking means gives a 1st marking to the frame which does not exceed the minimum guarantee zone | band of the user about each user's frame, and makes the frame which does not exceed the control zone | band with the minimum guarantee zone | band. The second marking is performed, the third marking is performed on the frames exceeding the minimum guaranteed bandwidth and the control bandwidth, a threshold for the accumulated amount of the buffer frames is set in the buffer, and the buffer control unit For each frame to be written to the buffer, if the accumulated amount of the frame does not exceed the threshold value, the frames with the first to third markings are written to the buffer, and the frame is accumulated. If the amount exceeds the threshold, write each frame with the first and second markings to the buffer; One said third frame marking is applied discarded without writing into the buffer, the frame control device according to any one of Appendices 1 to 5 (2).

(Supplementary note 7) A second threshold value is set in the buffer, and the buffer control unit, when the frame accumulation amount exceeds the threshold value and does not exceed the second threshold value, Each frame with the first and second markings is written to the buffer, and the frame with the third marking is discarded without being written to the buffer, and the accumulated amount of the frames satisfies the second threshold value. The frame according to appendix 6, wherein if it exceeds, the frame with the first marking is written to the buffer, and the frame with the second and third markings is discarded without being written to the buffer. Control device.

(Supplementary Note 8) The marking means performs, for each user's frame, a first marking on a frame that does not exceed the minimum guaranteed bandwidth of the user, and a frame that exceeds the minimum guaranteed bandwidth and does not exceed the control bandwidth. The second marking is applied, the third marking is applied to the frames exceeding the minimum guaranteed bandwidth and the control bandwidth, the buffer has a threshold for the amount of stored frames in the buffer, and the buffer control unit For each frame to be written to, if the accumulated amount of the frame does not exceed the threshold, the frames with the first to third markings are written to the buffer, and the accumulated amount of the frame Is over the threshold, the frames with the first and second markings are written to the buffer, and The third frame marking is applied to write the rest was discarded by a predetermined ratio in accordance with the accumulated amount, the frame control device according to any one of Appendices 1 to 5 (3).

(Supplementary Note 9) A second threshold value is set in the buffer, and the buffer control unit determines that the buffer amount is greater than the threshold value and does not exceed the second threshold value. Each frame with the first and second markings is written to the buffer, and the frame with the third marking is discarded in a proportion corresponding to the accumulation amount and the rest is written, and the accumulation amount of the frame is If the second threshold value is exceeded, the frame with the first marking is written to the buffer, and each of the frames with the second and third markings is determined according to the accumulation amount. 9. The frame control device according to appendix 8, wherein only the proportion is discarded and the rest is written.

(Appendix 10) Measuring means for measuring the flow rate of a frame for each user, and the minimum guaranteed bandwidth set for each user for each user's frame, and the minimum guaranteed bandwidth set according to this minimum guaranteed bandwidth Based on a plurality of large control bandwidths, the minimum guaranteed bandwidth is not exceeded, the minimum guaranteed bandwidth is between the smallest control bandwidth, the minimum control bandwidth, and the maximum control bandwidth is exceeded. Marking means for applying different markings to each of the frames, a buffer for storing the marked frames of each user, and a buffer in which a threshold for the accumulation amount of frames prepared for at least the number of the control bands is set; and Depending on the relationship between the amount of accumulated frames and the plurality of thresholds, frames with different marking types are handled differently. Frame control device including a § controller, (4).

(Supplementary Note 11) An arithmetic unit that has a plurality of functions for obtaining the control bandwidth from the minimum guaranteed bandwidth of the user, and calculates the control bandwidth of each user with a function using a parameter corresponding to the amount of frames stored in the buffer The frame control device (5) according to any one of appendices 1 to 10, further comprising:

(Additional remark 12) It is provided with the input interface part, at least 1 output interface part, and the forwarding part which transfers the flame | frame input from the said input interface part to any output interface part according to the destination, The said input interface The measurement unit measures the flow rate of the frame for each user, and for each user's frame, the minimum guaranteed bandwidth set for each user and larger than the minimum guaranteed bandwidth set according to the minimum guaranteed bandwidth The output interface unit, comprising: marking means for marking different frames on the basis of the control bandwidth and exceeding the minimum guaranteed bandwidth and not exceeding the control bandwidth, and on the frame exceeding the control bandwidth, A buffer for storing each marked user's frame; For each frame input from the forwarding unit, the marking is referred to.If the threshold of the accumulated amount of the frame set in the buffer is not exceeded, the threshold is set regardless of the marking type. A buffer control unit that discards all of the frames that have been marked to indicate the amount exceeding the control band or at a predetermined rate according to the accumulated amount, and writes the other frames to the buffer. A frame switch characterized by including.
In the present invention, the above components can be combined as much as possible.

  The present invention is applicable to industries that provide a fair amount of transfer between users for frames that exceed the minimum guaranteed bandwidth of each user.

It is an example of the functional block diagram which shows the apparatus structure of the traffic conditioner which concerns on one embodiment of this invention. The conceptual diagram of the marking by the marking process part in a traffic conditioner is shown. The conceptual diagram of output buffer control in the switch provided with a traffic conditioner is shown. It is an example of the conceptual diagram which shows the output buffer control by RED control of the switch concerning this Embodiment. It is a functional block diagram which shows the structure of the switch which concerns on this process example provided with this traffic conditioner. 10 is a table showing a set minimum guaranteed bandwidth value CR and a calculated value NR for each VID in this processing example. It is a table | surface which shows the flow volume of the flame | frame from each VID to the output buffer in this processing example. It is a block diagram which shows the structure of the conventional frame switch. It is a block diagram which shows the structure of the ingress interface and egress interface of the conventional frame switch. It is a block diagram which shows the structure of the conventional traffic conditioner. It is a conceptual diagram of the marking to the frame by the conventional traffic conditioner. It is a block diagram which shows the structure of the output buffer which concerns on the conventional frame switch. It is an example of the concept of buffer control in the conventional output buffer. It is a graph which shows the concept of RED control. It is a figure which shows an example at the time of providing the buffer which classified the class for every VLAN.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Traffic conditioner 11 Flow measurement part 12 Peak rate storage part 13 Minimum guaranteed band storage part 14 NR generation part 15,136 Marking process part 16 Buffer control part 18,137,138,139 Buffer 100 Frame switch 110 Interface part 111 Ingress interface 112 egress interface 120 forwarding unit 131 first classifier 132 traffic conditioner 133 second classifier 134 output buffer unit 135 measuring unit

Claims (5)

Measuring means for measuring the flow rate of the frame for each user;
For each user's frame, based on a minimum guaranteed bandwidth set for each user and a control bandwidth larger than the minimum guaranteed bandwidth set according to the minimum guaranteed bandwidth, the control exceeds the minimum guaranteed bandwidth and the control Marking means for applying different markings to a frame not exceeding the bandwidth and a frame exceeding the control bandwidth;
A buffer to store each user's marked frame;
A frame control device including: a buffer control unit that performs different handling for different types of marking according to the amount of frames stored in the buffer. For each user's frame, the marking means applies a first marking to a frame that does not exceed the minimum guaranteed bandwidth of the user, and a second marking to a frame that exceeds the minimum guaranteed bandwidth and does not exceed the control bandwidth. The third marking is applied to the frame that exceeds the minimum guaranteed bandwidth and control bandwidth,
In the buffer, a threshold is set for the amount of frames stored in the buffer,
The buffer control unit, for each frame to be written to the buffer,
If the accumulated amount of the frame does not exceed the threshold, write each frame with the first to third markings in the buffer,
If the accumulated amount of the frame exceeds the threshold value, the frames with the first and second markings are written to the buffer, and the frame with the third marking is written to the buffer. The frame control device according to claim 1, wherein the frame control device is discarded without any problem. For each user's frame, the marking means applies a first marking to a frame that does not exceed the minimum guaranteed bandwidth of the user, and a second marking to a frame that exceeds the minimum guaranteed bandwidth and does not exceed the control bandwidth. The third marking is applied to the frame that exceeds the minimum guaranteed bandwidth and control bandwidth,
In the buffer, a threshold for the accumulated amount of frames in the buffer is set,
The buffer control unit, for each frame to be written to the buffer,
If the accumulated amount of the frame does not exceed the threshold, write each frame with the first to third markings in the buffer,
When the accumulated amount of the frame exceeds the threshold value, each frame subjected to the first and second markings is written to the buffer, and the accumulated amount of the frame subjected to the third marking is set to the accumulated amount. 3. The frame control device according to claim 1, wherein a predetermined ratio is discarded and the rest is written. Measuring means for measuring the flow rate of the frame for each user;
For each user's frame, the minimum guaranteed bandwidth is not exceeded based on the minimum guaranteed bandwidth set for each user and a plurality of control bands larger than the minimum guaranteed bandwidth set according to the minimum guaranteed bandwidth. Marking means for applying different markings to each frame, the portion existing between the minimum guaranteed bandwidth and the smallest control bandwidth, the portion existing between the control bandwidths, and the portion exceeding the maximum control bandwidth;
A buffer in which a threshold for an accumulation amount of frames prepared for at least the number of the control bands is set;
A frame control apparatus comprising: a buffer control unit that performs different handling for frames with different marking types in accordance with a relationship between an accumulation amount of frames in the buffer and the plurality of threshold values. A plurality of functions for obtaining the control bandwidth from the minimum guaranteed bandwidth of the user, and further comprising an arithmetic unit that calculates the control bandwidth of each user with a function using a parameter corresponding to the amount of frames stored in the buffer. Item 5. The frame control device according to any one of Items 1 to 4.

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