JP2012120015A - Switching hub - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that prevents discarding of a flooding frame and suppresses load due to the flooding frame.SOLUTION: A reception control part 4 of a switching hub 1 stores a value of inner priority registered in a priority table 14a in a tag and gives the value to a received frame in an inner priority setting part 14. A measurement part 8 measures a transfer amount in the process of transferring of a flooding frame to an inner priority change part 10. In addition, a prescribed reference value is set to the measurement part 8 beforehand, and a value of priority that is given to the flooding frame is reduced for the inner priority change part 10 when the transfer amount exceeds the reference value. A transmission control part 12 transmits a frame in order of a frame that is waiting in a queue of which a value of the inner priority is higher.

Description

  The present invention relates to a switching hub that relays frames while suppressing a load caused by flooding.

  For switching hubs that relay frames at Layer 2 (data link layer), if the received frame is a flooded frame whose destination address indicates a broadcast address, multicast address, or unknown unicast address, the port that received the frame It is generally known that transmission (flooding) is simultaneously performed from a plurality of other ports.

  In a network composed of a plurality of switching hubs, for example, when a large number of flooding frames are transmitted due to a failure of a certain switching hub, there is a problem that a communication band between the switching hubs is compressed by the flooding frames.

  On the other hand, a prior art is known in which a setting load value of a broadcast frame is defined in advance in the switching hub, and the switching hub discards the broadcast frame when the load of the broadcast frame exceeds a set reference value (for example, Patent Documents). 1).

JP 2000-101629 A

  However, in the above-described prior art, the discarded flooding frame includes a frame that should be transferred originally, and such a frame may be discarded.

  Therefore, an object of the present invention is to provide a technique for suppressing a load caused by a flooding frame while preventing the flooding frame from being discarded.

  In order to solve the above problems, a switching hub of the present invention is a switching hub that relays a frame, and a setting unit that sets a predetermined reference value, and when a frame is received, this is a unicast in which a destination is specified. A discriminating unit for discriminating whether or not the frame is a flooding frame other than a frame, a measuring unit for measuring a frame transfer amount in the process of transferring a received frame, and a frame transfer amount measured by the measuring unit And a priority changing unit that lowers the priority of the frame transfer order with respect to the frame determined to be a flooding frame by the determining unit.

  According to the switching hub of the present invention, the load caused by the flooding frame can be suppressed while preventing the flooding frame from being discarded.

It is a block diagram which shows the functional structure of the switching hub of 1st Embodiment. It is a table | surface which shows schematically the priority table in a reception control part. It is a figure which shows roughly the transfer process of the frame in a reception control part, a measurement part, and an internal priority change part. It is a figure which shows roughly the transfer process of the frame in a transmission control part. It is a graph which shows roughly the ratio for which the transfer amount of the flooding frame measured by the measurement part occupies the maximum transfer amount of a frame. It is a flowchart which shows the transfer process of the flame | frame by a switching hub. It is a block diagram which shows roughly the functional structure of the switching hub in 2nd Embodiment. It is a block diagram which shows roughly the functional structure of the switching hub in 3rd Embodiment. It is a figure which shows roughly the structure of the transmission control part in the switching hub of 4th Embodiment. It is a figure which shows roughly the structure of the transmission control part in the switching hub of 5th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Also, the switching hub of this embodiment has data transfer functions such as OSI (Open Systems Interconnection) reference model layer 2 and layer 3 and relays frames in the same way as a general switching hub.

[First Embodiment]
FIG. 1 is a block diagram showing a functional configuration of the switching hub 1 of the first embodiment. A solid arrow in FIG. 1 represents the frame transfer direction. A dotted arrow indicates a transmission direction of a signal transmitted by each configuration.

  The switching hub 1 includes a plurality of ports 2, a reception control unit 4, an FDB (Forwarding DataBase) 6, a measurement unit 8, an internal priority change unit 10, and a transmission control unit 12.

  The plurality of ports 2 are connected to other switching hubs and network devices (not shown). When a frame transmitted from each switching hub or network device is received, it is transferred to the reception control unit 4. In addition, the frame transferred from the transmission control unit 12 is transmitted to the switching hub and the network device.

  The reception control unit 4 includes an internal priority setting unit 14. The reception control unit 4 performs transfer processing of received frames in the same manner as a general switching hub. In addition, the internal priority setting unit 14 newly adds a tag storing an internal priority value related to the frame transfer order to the frame transferred from the port 2 to the frame.

  The internal priority setting unit 14 includes a priority table 14a. The priority table 14a includes, for example, IEEE (Institut of Electrical and Electronics Engineers) 802.1P, IEEE802.1Q, and the like. A value indicating the priority for executing priority control and bandwidth control specified in QoS (Quality of Service) conforming to the standard, and a value indicating the internal priority corresponding thereto are registered in correspondence with each other. Has been.

  When the received frame is, for example, a MAC (Media Access Control) frame, the internal priority setting unit 14 is an area of C-TAG (Customer-vlan TAG) and S-TAG (Service-vlan TAG) in the MAC frame. The priority value stored in these is specified. Further, when the received frame is a MAC-in-MAC format frame, the internal priority setting unit 14 includes an I-TAG (Service Instance-TAG) or a B-TAG (Backbone-TAG) in the frame. The priority values stored in these areas are specified. Next, the internal priority setting unit 14 specifies the priority value in the priority table 14a that matches the specified priority value, and the internal priority value registered corresponding to the priority value. A tag storing the internal priority value is added to the frame.

  Further, when receiving a frame from the port 2, the reception control unit 4 transfers the frame while referring to the information learned by the FDB 6. For example, when the destination information of the received frame is a unicast address indicating a MAC address assigned to a specific terminal device or server, the reception control unit 4 refers to the FDB 6 and matches the above unicast address. Specify the address to be used. Then, when an address that matches the unicast address is registered in the FDB 6, the reception control unit 4 transfers this to the transmission control unit 12. Then, the transmission control unit 12 transmits this frame from the single port 2.

  On the other hand, when the unicast address is not registered in the FDB 6 or when the destination information indicates a broadcast address or a multicast address, that is, a frame other than the unicast frame whose destination information is specified with reference to the FDB 6 ( Hereinafter, in the case of “flooding frame”, the reception control unit 4 transfers the flooding frame to the measurement unit 8. Note that the processing executed by the reception control unit 4 will be described in more detail later with reference to FIGS. 2, 3, and 5.

  The measuring unit 8 transfers the flooding frame transferred from the reception control unit 4 to the internal priority changing unit 10. The measuring unit 8 measures the transfer amount of the flooding frame in the process of transferring the flooding frame to the internal priority changing unit 10.

  In the present embodiment, the measurement unit 8 can also function as a reference value setting unit. That is, a reference value indicating a predetermined ratio with respect to the maximum frame transfer amount (communication band) in the switching hub 1 is preset in the measurement unit 8. For example, as the “predetermined ratio with respect to the maximum frame transfer amount”, the ratio of the flooded frame transfer amount to the maximum frame transfer amount can be used. The reference value is set by, for example, an administrator or an operator who manages the switching hub 1. In addition, the above-described worker or the like can set a plurality of reference values. At this time, the measuring unit 8 instructs the internal priority changing unit 10 or the transmission control unit 12 to execute the processing according to each reference value. The processing executed by the measuring unit 8 will be described in more detail later with reference to FIGS. 3, 5, and 6.

  The internal priority changing unit 10 as an internal priority changing unit transfers the flooding frame transferred from the measuring unit 8 to the transmission control unit 12. When the internal priority changing unit 10 receives a signal indicating that the internal priority value stored in the tag of the frame is reduced from the measuring unit 8, the internal priority changing unit 10 transfers the received flooding frame to the transmission control unit 12. Then, the value of the internal priority added to this is lowered. Specifically, the internal priority changing unit 10 rewrites the internal priority value added to the received frame to a value lower than this value.

  The transmission control unit 12 includes a plurality of internal priority queues, and temporarily waits (buffers) the frames transferred from the reception control unit 4 and the internal priority change unit 10 in the internal priority queues. Keep it. Each internal priority queue is assigned a value for each internal priority, and the frames transferred from the reception control unit 4 and the internal priority change unit 10 are tagged with a tag (internal priority). Is assigned to each internal priority queue based on the degree value).

  In addition, the transmission control unit 12 uses, for example, a predetermined scheduling scheme based on the priority control and bandwidth control specified in the above-described QoS, and frames that have been queued in each internal priority queue in descending order of the internal priority value. Send from port 2. At this time, the transmission control unit 12 performs transmission after removing the tag added to the frame by the internal priority setting unit 14. Note that the processing executed by the transmission control unit 12 will be described in more detail later with reference to FIGS.

  FIG. 2 is a table schematically showing the priority table 14 a in the reception control unit 4. For example, QoS is defined between a user who uses a network and a telecommunications carrier that provides the network. Based on this QoS rule, the user determines priorities for various data transmitted and received within a predetermined communication band. In contrast, a telecommunications carrier that provides a network defines internal priorities corresponding to the above priorities, and registers the priorities and internal priorities in the priority table 14a in association with each other.

  In FIG. 2, the “priority” column and the “internal priority” column are provided in the left and right columns, respectively. In the “priority” column arranged in the left column, the priority values defined in the C-TAG, S-TAG area, and the like are shown. As for the value from “0” to “7” shown in the “priority” column, the priority for frame transfer increases as the value increases, and the priority for frame transfer decreases as the value decreases. Also, the diagonal lines in the “priority” column indicate the case where the priority is not defined for the received frame.

  In the column of “internal priority” arranged in the right column, the value of internal priority is shown. The values “0” to “n” shown in the “internal priority” column correspond to the “slashed lines” and “0” to “7” values shown in the “priority” column, respectively.

  For example, when the priority value stored in the frame received by the switching hub 1 is “6” or “7”, the internal priority setting unit 14 uses the internal priority “n” corresponding to the tag as a tag. Store and add this to the frame. When the priority is not defined for the received frame (“slashed line” in the “priority” column), the internal priority setting unit 14 sets the corresponding internal priority value “1” or “0”. "Is stored in the tag and added to the frame. In FIG. 2, the highest internal priority value is indicated as “n” for convenience, but it may be an arbitrary integer.

  FIG. 3 is a diagram schematically showing frame transfer processing in the reception control unit 4, the measurement unit 8, and the internal priority change unit 10. FIG. 4 is a diagram schematically showing frame transfer processing in the transmission control unit 12. Note that “UC” and “FD” surrounded by squares in FIGS. 3 and 4 respectively represent a unicast frame and a flooding frame whose destination is specified. Also, the values of (n), (n−1), (1), and (0) represent the internal priority values added to “UC” and “FD” for convenience. In FIG. 3, an arrow indicated by a solid line represents a direction in which the frame is transferred.

  When the frame is transferred from the port 2, the internal priority setting unit 14 of the reception control unit 4 refers to the priority table 14a and stores the tag storing the internal priority value corresponding to the frame priority. Append.

  Further, the reception control unit 4 functioning as a determination unit specifies the destination information of the received frame and the transfer destination port 2 with reference to the FDB 6. At this time, if the destination information of the frame is registered in the FDB 6 and the transfer destination port 2 indicates the specified unicast frame (UC), the reception control unit 4 transfers the frame to the transmission control unit 12. To do. On the other hand, when the destination information of the frame indicates a flooding frame (FD) other than the unicast frame, the reception control unit 4 transfers the frame to the measurement unit 8.

  The measuring unit 8 functioning as a measuring unit measures the transfer amount of the flooding frame in the process of transferring the flooding frame transferred from the reception control unit 4 to the internal priority changing unit 10. When the transfer amount of the flooding frame being measured exceeds a preset reference value, the measurement unit 8 causes the internal priority changing unit 10 to decrease the internal priority value added to the frame. Send a signal to that effect.

  The internal priority changing unit 10 transfers the flooding frame transferred from the measuring unit 8 to the transmission control unit 12. The internal priority changing unit 10 also functions as a priority changing unit. When the above signal is received from the measuring unit 8, the internal priority added to the flooded frame transferred from the measuring unit 8 is added. The degree value (“n” or “n−1”) is rewritten to a lower value (for example, “0” or “1”) and transferred to the transmission control unit 12.

  The transmission control unit 12 shown in FIG. 4 uses the unicast frame and flooding frame transferred from the reception control unit 4 and the internal priority change unit 10 based on the internal priority value added to them. To the queue. The frames distributed to the queues having the internal priorities are temporarily held here.

  Further, the transmission control unit 12 transmits a frame waiting in each internal priority queue from the port 2 by a predetermined scheduling method. For example, the transmission control unit 12 transmits the unicast frame and the flooding frame that are waiting in the “queue with the internal priority n” illustrated in FIG. 4, and then waits at the “internal priority n−1”. Unicast frame and flooding frame are transmitted.

  FIG. 5 is a graph schematically showing the ratio of the flooding frame transfer amount measured by the measurement unit 8 to the maximum frame transfer amount. The switching hub 1 of the first embodiment can set a plurality of reference values in the measurement unit 8. In addition, the measurement unit 8 instructs the internal priority changing unit 10 or the transmission control unit 12 to execute the process according to the reference value.

  In the graph shown in FIG. 5, the Y axis indicates the ratio of the flooded frame transfer amount to the maximum frame transfer amount. The X axis represents time. A graph indicated by a solid line represents a ratio of the flooding frame transfer amount measured by the measurement unit 8 in a predetermined time to the maximum frame transfer amount.

  The “reference value A” and “reference value B” shown on the Y axis indicate the ratio of the flooding frame transfer amount measured by the measuring unit 8 to the maximum frame transfer amount. “Reference value A” and “reference value B” can be freely set in advance by an operator or administrator who manages the switching hub 1 in advance. Here, as an example, the ratio indicating “reference value A” is defined as 60%, and the ratio indicating “reference value B” is defined as 80%. The three dotted lines shown in the X-axis direction indicate “reference value A”, “reference value B”, and 100%, respectively.

  For example, at an arbitrary time A shown in FIG. 5, the ratio of the flooding frame transfer amount measured by the measurement unit 8 to the maximum frame transfer amount is greater than the reference value A and higher than the reference value B. Few. At this time, the measuring unit 8 sends a signal to the internal priority changing unit 10 to reduce the value of the internal priority added to the flooding frame. The internal priority changing unit 10 that has received this signal lowers the value of the internal priority stored in the tag attached to the flooding frame transferred from the measuring unit 8.

  Further, at any time B, the ratio of the flooded frame transfer amount measured by the measuring unit 8 to the maximum frame transfer amount is larger than the reference value B. At this time, the measurement unit 8 transmits to the transmission control unit 12 a signal indicating that the flooding frames that exceed the reference value B are discarded. The transmission control unit 12 that has received this signal discards, for example, the flooding frames that exceed the reference value among the frames that are waiting in the queues of the internal priorities.

  FIG. 6 is a flowchart showing frame transfer processing by the switching hub 1. The procedure will be described below.

Step S100: The internal priority setting unit 14 of the reception control unit 4 adds a tag storing the internal priority value to the received frame.
Step S102: Next, the reception control unit 4 determines whether or not the received frame is a flooding frame. Specifically, the reception control unit 4 confirms the destination information of the received frame, and when the destination information is a broadcast address or a multicast address, or even if it is a unicast address, the address is registered in the FDB 6. If not, the received frame is determined to be a flooding frame (Yes). In this case, the reception control unit 4 transfers the flooding frame to the measurement unit 8 (step S104).

  On the other hand, if the destination information of the received frame is a unicast address and the address is registered in the FDB 6, the reception control unit 4 determines that the received frame is not a flooding frame (No). In this case, the reception control unit 4 transmits the received frame to the transmission control unit 12 (step S106).

  Step S108: The measuring unit 8 measures the amount of flooding frames transferred in the process of transferring the flooding frames received from the reception control unit 4 to the internal priority changing unit 10. At this time, if the measured transfer amount of the flooding frame is equal to or larger than the reference value B shown in FIG. 5 (Yes), the transmission control unit 12 discards the flooding frame that exceeds the reference value B. A signal is sent (step S110). The transmission control unit 12 that has received this signal discards the flooding frames that exceed the reference value among the frames that are waiting in the queues of the internal priorities. On the other hand, if the measured flooding frame transfer amount is less than the reference value B (No), the process proceeds to the next step S112.

  Step S112: The measurement unit 8 determines whether or not the measured flooding frame transfer amount exceeds the reference value A shown in FIG. When the measured flooding frame transfer amount is equal to or greater than the reference value A (Yes), the measuring unit 8 causes the internal priority changing unit 10 to decrease the internal priority value added to the frame. Send a signal to that effect. (Step S114). At this time, when the internal priority changing unit 10 receives the above signal, the internal priority changing unit 10 sets the value of the internal priority added thereto in the process of transferring the flooding frame received from the measuring unit 8 to the transmission control unit 12. Lower. On the other hand, when the measured amount of flooding frames transferred is less than the preset reference value A (No), the process proceeds to the next step S116. If it is less than the reference value A, the flooding frame is transferred from the measurement unit 8 to the transmission control unit 12 via the internal priority change unit 10.

Step S116: The transmission control unit 12 sets the flooding frame and the unicast frame received from the internal priority changing unit 10 and the reception control unit 4 to each internal priority based on the tag (internal priority value) added thereto. Sort to the appropriate queue.
Step S118: Next, the transmission control unit 12 transmits a frame waiting in each internal priority queue based on a predetermined scheduling method, and ends this processing.

  As described above, when an amount of flooding frames exceeding the preset reference value A is transferred in the switching hub 1, the switching hub 1 does not immediately discard the flooding frames but adds them. Decrease the internal priority value. As a result, the unicast frame whose destination is specified can be transmitted preferentially. Further, when the flooding frame transfer amount with respect to the maximum frame transfer amount decreases, the flooding frame waiting in the queue having a low internal priority value can be transmitted.

  In the first embodiment, as a predetermined scheduling method, a method of transmitting frames in descending order of internal priority values is employed. However, the number of frames that can be transmitted continuously from each internal priority queue. May be a weighted round robin (Weighted Round Robin) method.

[Second Embodiment]
Next, the switching hub 1 of 2nd Embodiment is demonstrated. FIG. 7 is a block diagram schematically showing a functional configuration of the switching hub 1 in the second embodiment. The second embodiment is different from the first embodiment in that the reception control unit 4 includes a measurement unit 8. The other configurations are the same as those in the first embodiment, and here, the same reference numerals are given to the common configurations together with the drawings, and redundant descriptions are omitted.

  The reception control unit 4 measures the reception amount of all frames transferred from the port 2 in the measurement unit 8 included therein. Further, as the reference value set in the measurement unit 8, the ratio of the received frame amount to the maximum frame transfer amount is used. At this time, if the received amount of frames measured by the measurement unit 8 is equal to or greater than the reference value A shown in FIG. 5 and less than the reference value B, the reception control unit 4 sends a flooding frame to the internal priority change unit 10. A signal to reduce the value of the internal priority added to is transmitted. Further, when the reception amount of the frame measured by the measurement unit 8 is equal to or larger than the reference value B shown in FIG. 5, the reception control unit 4 discards the flooding frame exceeding the reference value B with respect to the transmission control unit 12. Send a signal to the effect.

  Thus, by setting the reference value based on the reception amount of the frame, the measurement unit 8 always grasps the ratio of the transfer amount of the actually transmitted / received frame to the maximum transfer amount of the frame. Can do. In this case, even if a large amount of unicast frames are transferred in the network, the unicast frames are transferred with priority over the flooding frames. When the received amount of frames is equal to or greater than the reference value B, the switching hub 1 discards only the flooding frames that exceed the reference value B, and accordingly, unicast frames or flooding frames that need to be transferred. Can be transferred reliably.

[Third Embodiment]
Next, the switching hub 1 of 3rd Embodiment is demonstrated. FIG. 8 is a block diagram schematically showing a functional configuration of the switching hub 1 in the third embodiment. The third embodiment is different from the first and second embodiments in that the measurement unit 8 measures the amount of frames waiting in each internal priority queue of the transmission control unit 12. The other configurations are the same as those in the first embodiment, and here, the same reference numerals are given to the common configurations together with the drawings, and redundant descriptions are omitted.

  The measuring unit 8 measures the amount of frames waiting in each internal priority queue of the transmission control unit 12. Further, the measurement unit 8 can individually measure the amount of frames waiting in a queue with a specific internal priority. At this time, when the amount of frames waiting in a queue with a specific internal priority exceeds a preset reference value, the measurement unit 8 is added to the flooding frame with respect to the internal priority change unit 10 A signal indicating that the internal priority value is to be decreased is transmitted, or a signal indicating that the flooding frame corresponding to the reference value is discarded is transmitted to the transmission control unit 12.

  For example, the measurement unit 8 compares the amount of frames waiting in the internal priority n queue with a high internal priority with the reference value, and the frame amount is the reference value A or the reference value B shown in FIG. Is exceeded, the above signal is transmitted to the internal priority changing unit 10 or the transmission control unit 12. Thereby, the transmission control unit 12 can transmit a unicast frame based on a predetermined scheduling method defined in the priority control and the band control, and can efficiently suppress the transfer amount of the flooding frame.

[Fourth Embodiment]
Next, a switching hub according to a fourth embodiment will be described. FIG. 9 is a diagram schematically illustrating the configuration of the transmission control unit 12 in the switching hub 1 of the fourth embodiment. The fourth embodiment is different from the transmission control unit 12 in the first to third embodiments in that an internal priority dedicated to a flooding frame is defined separately from the internal priority.

  In the fourth embodiment, the transmission control unit 12 provides a dedicated queue for flooding frames in addition to the internal priority queue. In addition to the priority value assigned to the internal priority queue, an internal priority value dedicated to flooding frames is allocated to the queue dedicated to flooding frames.

  In the first and third embodiments, when the measured flooding frame transfer amount is not less than the reference value A and less than the reference value B shown in FIG. Thus, a signal indicating that the value of the internal priority added to the flooding frame is lowered is transmitted.

  At this time, in the fourth embodiment, the internal priority changing unit 10 transfers the flooding frame received from the measuring unit 8 to the transmission control unit 12 and uses the internal priority value added to the flooding frame as described above. Change to the internal priority value corresponding to the queue dedicated to flooding frames. Then, based on the internal priority value added to the flooding frame received from the internal priority changing unit 10, the transmission control unit 12 distributes it to a queue dedicated to each flooding frame.

  On the other hand, in the second embodiment, when the measured flooding frame transfer amount is not less than the reference value A and less than the reference value B shown in FIG. A signal indicating that the value of the internal priority added to is lowered is transmitted.

  At this time, in the fourth embodiment, when the transmission control unit 12 receives the signal from the measurement unit 8, the transmission control unit 12 decreases the value of the internal priority assigned to the queue dedicated to the flooding frame.

  As described above, the switching hub 1 of the fourth embodiment temporarily stops the transmission of the flooding frame according to the reference value in the same manner as the switching hub 1 of the first to third embodiments, and preferentially transmits the unicast frame. can do. Further, when the ratio of the flooding frame transfer amount to the maximum frame transfer amount decreases, the flooding frame waiting in the queue dedicated to the flooding frame can be transmitted. As a result, the switching hub 1 can efficiently control the forwarding of the flooding frame without discarding the flooding frame that is originally necessary for the forwarding.

[Fifth Embodiment]
Next, a switching hub according to a fifth embodiment will be described. FIG. 10 is a diagram schematically illustrating the configuration of the transmission control unit 12 in the switching hub 1 of the fifth embodiment. In the fifth embodiment, the transmission control unit 12 uses a unicast frame-dedicated queue (UC: internal priority queue) and a flood-frame-dedicated queue (MC (multicast), BC (broadcast), The difference from the first to fourth embodiments is that DLF (unicast frame with unknown destination): internal priority queue) is provided for each internal priority value.

  In the fifth embodiment, the priority table 14 a of the reception control unit 4 includes “UC: internal priority queue” and “MC / BC / DLF: internal priority queue” arranged in the transmission control unit 12. The values corresponding to the values of the internal priorities assigned to each other are defined, and these values are registered corresponding to the priority values.

  In addition, when the frame transferred from the port 2 is a flooding frame, the internal priority setting unit 14 of the reception control unit 4 is registered in the priority table 14a in accordance with the priority value defined therein. Add the internal priority value to the flooding frame.

  In the fifth embodiment, as in the first and third embodiments, the measurement unit 8 has a measured flooding frame transfer amount that is not less than the reference value A and less than the reference value B shown in FIG. A signal for lowering the internal priority added to the flooding frame is transmitted to the internal priority changing unit 10. When the internal priority changing unit 10 receives the signal, the internal priority changing unit 10 lowers the value of the internal priority added to the flooding frame received from the measuring unit 8 in the process of transferring the flooded frame to the transmission control unit 12.

  Further, the transmission control unit 12 distributes the flooding frame received from the internal priority changing unit 10 to each of “MC, BC, DLF: internal priority queue” based on the internal priority value added thereto. .

  A plurality of reference values may be set for the measurement unit 8. At this time, the measurement unit 8 may cause the internal priority change unit 10 to change the value of the internal priority according to each reference value.

  As described above, in the fifth embodiment, a dedicated priority is assigned to a queue dedicated to each flooding frame. For example, the reception control unit 4 determines the internal priority of the flooding frame that should originally be transferred. If the value is set high, even if the reference value B is exceeded, this is prevented from being discarded.

  As described above, the switching hub of the present invention can efficiently suppress the amount of flooded frames transferred by using the priority control and bandwidth control functions defined in commonly used QoS, and the flooding frame. Is prevented from being destroyed.

  The present invention is not limited to the first to fifth embodiments described above, and various modifications can be made. For example, in the fifth embodiment, when the measurement unit 8 transmits a signal for reducing the internal priority added to the flooding frame to the transmission control unit 12 as in the second embodiment, the transmission control unit 12 May reduce the value of the internal priority added to the received flooding frame, and then distribute it to each “MC, BC, DLF: internal priority queue”.

DESCRIPTION OF SYMBOLS 1 Switching hub 4 Reception control part 8 Measurement part 10 Internal priority change part 12 Transmission control part 14 Internal priority setting part 14a Priority table

Claims (7)

A switching hub that relays frames,
Setting means for setting a predetermined reference value;
A discriminating means for discriminating whether or not this frame is a flooding frame other than the specified unicast frame;
Measuring means for measuring a transfer amount of the frame in a process of transferring the received frame;
When the transfer amount of the frame measured by the measurement unit exceeds the reference value, the priority regarding the frame transfer order is lowered with respect to the frame determined to be the flooding frame by the determination unit. A switching hub comprising priority changing means. The switching hub according to claim 1,
The setting means includes
A switching hub, wherein a plurality of the reference values are set for the maximum transfer amount of the frame. The switching hub according to claim 1 or 2,
A reception control unit that defines the priority for the received frame;
The priority changing means includes
When the transfer amount of the frame measured by the measuring unit exceeds the reference value, the priority defined in the frame determined to be a flooded frame by the determining unit is lowered. Switching hub characterized by The switching hub according to any one of claims 1 to 3,
The setting means includes
Set the reference value indicating the ratio of the flooding frame transfer amount to the maximum transfer amount of the frame that can be relayed,
The measuring means includes
A switching hub characterized in that the transfer amount of the frame determined to be the flooding frame by the determining means is measured. The switching hub according to any one of claims 1 to 4,
A plurality of queues for temporarily waiting the frames for each priority defined in the frames, and a transmission control unit for transmitting the frames waiting in the queues based on the priorities Prepared,
The measuring means includes
Measure the total amount of frames waiting in each queue,
The priority changing means includes
When the total amount of the frames measured by the measuring means exceeds the reference value, the switching hub is configured to lower the priority defined for the flooding frames. The switching hub according to claim 5,
The transmission control unit
For any one of the plurality of queues, temporarily wait only for the flooding frame,
The measuring means includes
The switching hub, wherein when the transfer amount of the flooding frame exceeds the reference value, the priority specified for the flooding frame waiting in the queue is lowered for the transmission control unit. The switching hub according to claim 5,
The reception control unit
The priority specific to each of the unicast frame and the flooding frame is defined,
The measuring means includes
Measure the transfer amount of the flooding frame,
The priority changing means includes
If the transfer amount of the flooding frame measured by the measuring means exceeds the reference value, the priority defined in the flooding frame is lowered,
The transmission control unit
The switching hub according to claim 1, wherein the frame is divided into the unicast frame and the flooding frame and distributed to the respective queues for each of the priorities.

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