Communication control method, communication control device and program

Abstract

In order to forward data efficiently in an electro-optical hybrid switching network, monitoring data is acquired and a first threshold value is modified on the basis of the monitoring data, said monitoring data being a) the blocking rate at the time of optical circuit configuration in an optical circuit switching network, b) a quantity relating to a flow that has been forwarded to an electrical packet network by a connection device, c) the buffer usage condition of an electrical communication apparatus in the electrical packet network, d) the packet forwarding delay of the electrical communication apparatus in the electrical packet network, or similar, and said first threshold value being for identifying a first flow that is forwarded by the connection device via the optical circuit switching network and a second flow that is forwarded via the electrical packet network, and being for identifying a flow that has a size exceeding the first threshold value as the first flow and identifying a flow that has a size smaller than or equal to the first threshold value as the second flow.

Description

[Technical Field]

[0001] The present invention relates to a communication control technique for controlling communication in an electro-optical hybrid switch network. [Background technology]

[0002] The emergence of fifth-generation mobile communication systems (5G) and the Internet of Things (IoT) is spurring an increase in communication traffic within data centers. For example, it is predicted that global IP traffic in data centers will reach 20.6 zettabytes in 2021, with approximately 75% of that amount being processed within data centers. Meanwhile, current data center networks are constructed using multiple layers of electrical switches (e.g., Non-Patent Document 1), and large-scale data centers consume tens of thousands to hundreds of thousands of kilowatts of power. In order to process even larger volumes of communication traffic, it is desirable to increase the communication bandwidth of data center networks while reducing power consumption.

[0003] In current data center networks, electrical switch / router configurations are hierarchical, with top-of-rack (ToR) switches positioned at the bottom for aggregating server computers, storage, etc. For example, Patent Document 1 discloses an example of the configuration and control method of a data center network based on current electrical switches / routers.

[0004] To meet these demands, an electro-optical hybrid switch network that combines electrical and optical switches has been proposed (see, for example, Non-Patent Document 2). In the technology described in Non-Patent Document 2, traffic from server computers and storage devices passes through a ToR switch, which then interconnects the ToR switch with higher-level electrical and optical switches. Traffic flows passing through the ToR switch or traffic flows generated by individual server computers and storage devices are monitored, and a path using either an electrical or optical switch is selected depending on the size of the flow. For example, small flows of 15 Mb / s or less are classified as "mouse flows," while large flows exceeding this size are classified as "elephant flows." Mice flows are processed by electrical switches, while elephant flows are processed by optical switches. By switching large flows over optical lines in this way, an electro-optical hybrid switch network can process larger volumes of communication traffic with lower power consumption than current datacenter networks (i.e., networks with multiple hierarchical electrical switches). Furthermore, an electro-optical hybrid switch network that can accommodate large-scale datacenters uses optical circuit-switched switches with thousands of ports, and its configuration method has also been proposed (see, for example, Non-Patent Document 3).

[0005] For example, as shown in Non-Patent Document 3, even if a method is adopted in which Mice flows are processed by electrical switches and Elephant flows are processed by optical switches, the problem of how to distinguish between Mice flows and Elephant flows remains. To address this problem, a method has been proposed in which a threshold for distinguishing between Mice flows and Elephant flows is dynamically determined for each ToR switch (for example, Non-Patent Document 4). According to this document, the threshold is dynamically determined by learning using a neural network, but this requires learning and increases the amount of calculation required to determine the threshold.

[0006] Furthermore, in an electro-optical hybrid switch network, even if an optical line is set up between the sending and receiving ToR switches to transfer Elephant flows, this alone does not ensure efficient data transfer across the entire electro-optical hybrid switch network. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 8,483,096 [Non-patent literature]

[0008] [Non-Patent Document 1] Arjun Singh,et.al.,"Jupiter Rising: A Decade of Clos Topologies and Centralized Control in Google's Datacenter Network",Proc.ACM SIGCOMM 2015 Conference (SIGCOMM '15),pp.88-97,London,United Kingdom,Aug.2015 [Non-patent document 2] Nathan Farrington,et.al.,"Helios: A Hybrid Electrical / Optical Switch Architecture for Modular Data Centers",Proc.ACM SIGCOMM 2010 Conference (SIGCOMM '10),pp.339-350,New Delhi,India,Aug.2010 [Non-patent document 3] Ken-ichi Sato, "Realization and Application of Large-Scale Fast Optical Circuit Switch for Data Center Networking", IEEE / OSA Journal of Lightwave Technology, Vol. 36, No. 7, pp. 1411-1419, Apr. 2018 [Non-patent document 4] Y. Tang et al., "Flow Splitter: A Deep Reinforcement Learning-Based Flow Scheduler for Hybrid Optical-Electrical Data Center Network," in IEEE Access, vol. 7, pp. 129955-129965, 2019, doi: 10.1109 / ACCESS.2019.2940445. Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention, in one aspect, to provide a novel technique for more efficient data transfer in an electro-optical hybrid switch network. [Means for solving the problem]

[0010] A communication control method according to a first aspect of the present invention is a communication control method for controlling communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network, and each of which is responsible for one or more devices, and includes the steps of: (A) acquiring monitor data that is a blocking rate when an optical line is set up in the optical circuit switching network, an amount related to a flow transferred by the connection device to the electrical packet network, a buffer usage status in a telecommunications device in the electrical packet network, or a packet transfer delay or packet discard rate in a telecommunications device in the electrical packet network; and (B) changing, based on the monitor data, a first threshold value for distinguishing between a first flow that the connection device transfers via the optical circuit switching network and a second flow that the connection device transfers via the electrical packet network, wherein the first threshold value is used to identify a flow having a size exceeding the first threshold as the first flow and to identify a flow having a size equal to or smaller than the first threshold as the second flow.

[0011] A communication control method according to a second aspect of the present invention is a communication control method for controlling communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network, and each of which is responsible for one or more devices, and includes the steps of (A) determining whether the flow rate of a flow flowing through an optical line set between certain connection devices in the optical circuit switching network is below a threshold, and (B) if the flow rate of the flow is below the threshold, disconnecting the optical line and transmitting packets related to the flow to the certain connection device that is the source of the flow via the electrical packet network. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the configuration of an electro-optical hybrid switch network according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of the electric switch unit. [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of the optical switch unit. [Figure 4] FIG. 4 is a diagram illustrating an example of a functional configuration of the communication control device. [Figure 5] FIG. 5 is a diagram illustrating a processing flow according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating a processing flow according to the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating a processing flow according to the third embodiment. [Figure 8] FIG. 8 is a diagram illustrating a processing flow according to the fourth embodiment. [Figure 9] FIG. 9 is a diagram illustrating a processing sequence according to the fifth embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a table used for blocking detection. [Figure 11] FIG. 11 is a diagram showing another example of the rack configuration. [Figure 12] FIG. 12 is a diagram showing yet another example of the rack configuration. [Figure 13] FIG. 13 is a block diagram of a computer device that is a communication control device. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Embodiment 1] FIG. 1 shows an example of the configuration of an electro-optical hybrid switch network according to an embodiment of the present invention. The electro-optical hybrid switch network shown in FIG. 1 includes a rack unit 1, a ToR switch unit 2, an electrical switch unit 3, an optical switch unit 4, a communication control device 5, a cabling unit 6, a control line 7 for the electrical switch unit 3, a control line 8 for the optical switch unit 4, and a control line 9 for the ToR switch unit 2. This electro-optical hybrid switch network is a multi-layer switch network with a ToR switch unit 2 at a lower level and an electrical switch unit 3 and an optical switch unit 4 at an upper level. Hereinafter, the lower layer will be referred to as a distribution layer, and the upper layer will be referred to as an aggregation layer. The optical switch unit 4 is an example of an optical circuit-switched network, and the electrical switch unit 3 is an example of an electrical packet network.

[0014] The rack unit 1 includes racks 1-1 to 1-n, and the ToR switch unit 2 includes ToR switches 2-1 to 2-n. The ToR switches are electric switches or electric routers, and are an example of connection devices. Each ToR switch in the ToR switch unit 2 is connected to the electric switch unit 3 by an electric or optical cable wiring unit 61. Each ToR switch in the ToR switch unit 2 is connected to the optical switch unit 4 by an optical cable wiring unit 62. For example, in the data center of Non-Patent Document 1, the ToR switch unit 2 may include approximately 1,000 or more ToR switches, in which case approximately tens of thousands to hundreds of thousands of servers are accommodated. The servers are an example of information processing devices, and are devices managed by the ToR switches, including servers and storage devices.

[0015] FIG. 2 shows an example of the configuration of the electrical switch unit 3 shown in FIG. 1. The electrical switch unit 3 includes a single- or multi-layer electrical router or an electrical packet switch. These are examples of telecommunications equipment. For example, h pieces of telecommunications equipment 311-31h connected to the ToR switch unit 2 in the distributed layer are connected to j pieces of telecommunications equipment 3k1-3kj located in the highest stage k of the electrical switch unit 3 by i pieces of telecommunications equipment 321-32i. The number of stages k of the electrical switch unit 3 and the parallel number h of the telecommunications equipment located in the lowest stage of the electrical switch unit 3 are numerical values ​​equal to or greater than 1. Furthermore, the parallel numbers i and j of the telecommunications equipment located in higher stages are numerical values ​​equal to or greater than 0.

[0016] FIG. 3 shows an example of the configuration of the optical switch unit 4 shown in FIG. 1. The optical switch unit 4 includes one or more optical circuit-switched switches. The optical circuit-switched switch is an example of optical communication equipment. Optical communication equipment and electrical communication equipment are collectively referred to as communication equipment. For example, the optical circuit-switched switches 411 to 41m are connected to each ToR switch in the ToR switch unit 2 in the distributed layer. The number of parallel optical circuit-switched switches, m, is 1 or greater. To handle the data center described in Non-Patent Document 1, optical circuit-switched switches with thousands of ports are used. For example, an example of a method for configuring a large-scale optical switch is disclosed in Non-Patent Document 2. The optical line may be configured using wavelength multiplexing, time division multiplexing, or both. The optical switch unit 4 may also be realized by combining multiple hierarchical switches with fewer ports, as in the configuration of the electrical switch unit 3 shown in FIG. 2.

[0017] 4 shows an example of the configuration of the communication control device 5 shown in FIG. 1. The communication control device 5 includes an electrical switch control unit 51, an optical switch control unit 52, and a ToR switch control unit 53. The electrical switch control unit 51 is connected to the electrical switch unit 3 via a control line 7 for the electrical switch unit 3. The optical switch control unit 52 is connected to the optical switch unit 4 via a control line 8 for the optical switch unit 4. The ToR switch control unit 53 is connected to the ToR switch unit 2 via a control line 9 for the ToR switch unit 2. Note that in the communication control device 5, the electrical switch control unit 51, the ToR switch control unit 53, and the optical switch control unit 52 may cooperate to perform control by exchanging monitored data, for example.

[0018] The electrical switch control unit 51 collects connection information (information on the connection state) of the electrical switch unit 3, for example, via the control line 7 for the electrical switch unit 3, and performs settings for the telecommunications devices in the electrical switch unit 3 regarding switching of the electrical switch unit 3. Although not used in this embodiment, the electrical switch control unit 51 also acquires data on the buffer usage status of each telecommunications device in the electrical switch unit 3, data on packet transfer delays, packet discard rates, etc., and outputs the data to the ToR switch control unit 53, for example.

[0019] The optical switch control unit 52 collects connection information (information about the connection state) of the optical switch unit 4 via the control line 8 for the optical switch unit 4, and performs settings for the optical circuit switching switch in the optical switch unit 4 regarding switching of the optical switch unit 4. The optical switch control unit 52 also detects blocking, for example, by determining whether an input / output port of the optical circuit switching switch that satisfies an optical line setting request from the ToR switch unit 2 is already in use. Furthermore, the optical switch control unit 52 calculates a blocking rate obtained by dividing the number of optical line setting requests for which blocking was detected in a predetermined period by the total number of optical line setting requests in the predetermined period, and outputs the blocking rate to, for example, the ToR switch control unit 53.

[0020] The ToR switch control unit 53 collects connection information (information about the connection state) of the ToR switch unit 2 via the control line 9 for the ToR switch unit 2, and performs settings for the ToR switches in the ToR switch unit 2. In this embodiment, the ToR switch control unit 53 performs processing to change the flow threshold, as described below, based on the blocking rate obtained from the optical switch control unit 52, and performs settings for each ToR switch included in the ToR switch unit 2. Note that, although not used in this embodiment, the ToR switch control unit 53 may also obtain data on the statistics of flows transferred from each ToR switch included in the ToR switch unit 2 to the electrical switch unit 3. In addition, it may also obtain data on the flow rate of flows transferred from each ToR switch included in the ToR switch unit 2 via the optical switch unit 4.

[0021] The ToR switch according to this embodiment determines whether to output a flow to one of the electrical communication devices in the electrical switch unit 3 or to one of the optical communication devices in the optical switch unit 4, mainly based on the size of the flow, except for flows that are determined to be transferred via the electrical switch unit 3 and flows that are determined to be transferred via the optical switch unit 4. At this time, the flow size is compared with the flow threshold. For example, the ToR switch transfers flows that are equal to or greater than the flow threshold via the optical switch unit 4, and transfers flows that are less than the flow threshold via the electrical switch unit 3.

[0022] Although this flow threshold may be fixed, this may result in inefficient data transfer. For example, if the blocking rate is high, even if a flow is to be transferred through the optical switch unit 4, blocking may prevent the establishment of an optical line, resulting in delays or loss of data transfer. In such a case, increasing the flow threshold will allow only larger flows to be transferred through the optical switch unit 4, thereby reducing the blocking rate. On the other hand, if the blocking rate is low, it is estimated that there are few flows to be transferred through the optical switch unit 4, so the flow threshold is lowered to allow more flows to be transferred through the optical switch unit 4. This makes it possible to effectively utilize the optical switch unit 4 and reduce the load on the electrical switch unit 3, thereby improving overall delay performance and efficiency.

[0023] 5 is executed by, for example, the ToR switch control unit 53. For example, steps S1 to S9 are executed at predetermined time intervals.

[0024] The ToR switch control unit 53 acquires a blocking rate from, for example, the optical switch control unit 52 (step S1). Then, the ToR switch control unit 53 compares the blocking rate with a predetermined threshold value for the blocking rate to determine whether the blocking rate is equal to or less than the threshold value (step S3). If the blocking rate exceeds the threshold value, the ToR switch control unit 53 executes a setting for each ToR switch of the ToR switch unit 2 to increase the current flow threshold by a predetermined value in order to suppress further occurrence of blocking (step S5). As a result, the ToR switch will only forward flows of larger size via the optical switch unit 4, and it is expected that the blocking rate will decrease. Then, the process proceeds to step S9.

[0025] On the other hand, if the blocking rate is equal to or less than the threshold, the ToR switch control unit 53 executes a setting for each ToR switch to decrease the current flow threshold by a predetermined value (step S7) in order to increase the flow forwarding via the optical switch unit 4. As a result, the ToR switch will be able to forward even smaller flows via the optical switch unit 4.

[0026] Then, the ToR switch control unit 53 determines whether to terminate the processing due to reasons such as an instruction to stop changing the flow threshold based on the blocking rate or a power outage (step S9), and if the processing is not terminated, returns to step S1, and if the processing is terminated, terminates the processing.

[0027] By repeating this process, an appropriate flow threshold can be dynamically set in response to changes in the blocking rate over time.

[0028] In this process, the same flow threshold is set for each ToR switch, but different flow thresholds may be set for each ToR switch. This is because different models of ToR switches may have different performance, and the configurations and processing statuses of the servers they handle may also be different. For example, the blocking rate may be calculated for each ToR switch, and the process flow of FIG. 5 may be executed for each ToR switch. Furthermore, the flow threshold set for each ToR switch may be changed by changing the predetermined values ​​in steps S5 and S7 of the process flow of FIG. 5 for each ToR switch. Furthermore, although one flow threshold is calculated, it may be adjusted for each ToR switch. The communication control device 5, including the ToR switch control unit 53, manages the flow thresholds set for each ToR switch.

[0029] In the example described above, the ToR switch control unit 53 changes the flow threshold and sets it for each ToR switch, but if the flow threshold is changed for each ToR switch, the flow threshold may be changed in the ToR switch. Also, although an example has been shown in which the ToR switch control unit 53 changes the flow threshold, another part of the communication control device 5 may change the flow threshold and the ToR switch control unit 53 may set it.

[0030] [Embodiment 2] In some cases, overall efficiency can be improved by dynamically changing the flow threshold based on the load on the electrical switch unit 3. In this embodiment, statistics of the usage status (e.g., usage rate) of the packet buffers of the telecommunications devices included in the electrical switch 3 are used as one of the indices representing the load on the electrical switch unit 3. Examples of statistics include the average, median, and maximum values.

[0031] More specifically, the process shown in Fig. 6 is executed by, for example, the ToR switch control unit 53. For example, steps S11 to S19 are executed at predetermined time intervals.

[0032] The electrical switch control unit 51 acquires the packet buffer usage rate (packet buffer usage rate) of each piece of telecommunications equipment in the electrical switch unit 3 from that piece of telecommunications equipment, and the ToR switch control unit 53 acquires the packet buffer usage rate of each piece of telecommunications equipment from the electrical switch control unit 51 (step S11). The ToR switch control unit 53 identifies statistics of the packet buffer usage rate as an index value according to the packet buffer usage rate of each piece of telecommunications equipment (step S13).

[0033] The ToR switch control unit 53 then compares the identified index value with a predetermined threshold for that index value, and determines whether the index value is equal to or greater than the threshold (step S15). If the index value is equal to or greater than the threshold, the ToR switch control unit 53 executes a setting for each ToR switch to, for example, lower the flow threshold by a predetermined value so as not to further increase the packet buffer usage rate (step S17). That is, a setting is made to increase the use of the optical switch unit 4. Then, the process proceeds to step S19. On the other hand, if the index value is less than the threshold, the process proceeds to step S19 without performing any particular process.

[0034] Then, the ToR switch control unit 53 determines whether to terminate the processing due to reasons such as an instruction to stop changing the flow threshold based on an index value corresponding to the bucket buffer usage rate or a power outage (step S19), and if the processing is not terminated, returns to step S11, and if the processing is terminated, terminates the processing.

[0035] By repeating this process, an appropriate flow threshold can be dynamically set in accordance with changes over time in the packet buffer usage status, such as the packet buffer usage rate.

[0036] In this process, the same flow threshold is set for each ToR switch, but a different flow threshold may be set for each ToR switch. This is because the ToR switches may differ in performance due to different models, or the configurations and processing conditions of the servers they handle may also differ. For example, the flow threshold set for each ToR switch may be changed by changing the predetermined value for each ToR switch in step S17 of the process flow in Figure 6. Also, although one flow threshold is calculated in step S17, it may be adjusted for each ToR switch. The communication control device 5, including the ToR switch control unit 53, manages the flow threshold set for each ToR switch.

[0037] In the example described above, the ToR switch control unit 53 changes the flow threshold and sets it for each ToR switch, but when changing the flow threshold for each ToR switch, the ToR switch may change the flow threshold notified from the ToR switch control unit 53. Furthermore, in Fig. 6, the flow threshold is not changed when the index value is less than the threshold, but the flow threshold may be set to be increased.

[0038] Also, although an example has been shown in which the ToR switch control unit 53 changes the flow threshold, another part of the communication control device 5 may change the flow threshold, and the ToR switch control unit 53 may perform the setting.

[0039] [Embodiment 3] Regarding the load on the electrical switch unit 3, not only the packet buffer usage rate of the telecommunications equipment described in the second embodiment but also statistics regarding the flows forwarded to the electrical switch unit 3 by each ToR switch of the ToR switch unit 2, specifically, the traffic volume within a certain period of time due to all flows forwarded to the electrical switch unit 3, may be used.

[0040] More specifically, the process shown in Fig. 7 is executed by, for example, the ToR switch control unit 53. For example, steps S21 to S27 are executed at predetermined time intervals. In this embodiment, the process of Fig. 7 is executed for each ToR switch included in the ToR switch unit 2.

[0041] The ToR switch control unit 53 acquires from a certain ToR switch the amount of traffic (traffic volume) that the certain ToR switch has transferred to the electrical switch unit 3 within a certain period of time (step S21). Then, the ToR switch control unit 53 determines whether the traffic volume is equal to or greater than a predetermined threshold for the traffic volume (step S23). If the traffic volume is equal to or greater than the threshold, the ToR switch for which the traffic volume was measured is configured to lower the flow threshold by, for example, a predetermined value so that the traffic volume does not increase any further and the load on the electrical switch unit 3 does not increase (step S25). Then, the process proceeds to step S27. On the other hand, if the traffic volume is less than the threshold, the process proceeds to step S27 without performing any particular process.

[0042] Then, the ToR switch control unit 53 determines whether to terminate the process due to a reason such as an instruction to stop changing the flow threshold based on the index value according to the traffic volume or a power outage (step S2 7 ), if the processing has not ended, the process returns to step S21, and if the processing has ended, the process ends.

[0043] By repeating this process, an appropriate flow threshold value can be dynamically set in accordance with changes over time in flow statistics such as traffic volume.

[0044] In the above example, the ToR switch control unit 53 changes the flow threshold for each ToR switch, but each ToR switch itself may change the flow threshold. Alternatively, the same flow threshold may be determined for each ToR switch by calculating statistics (e.g., average, median, maximum, etc.) of the traffic volume obtained from each ToR switch. The communication control device 5, including the ToR switch control unit 53, manages the flow threshold set for each ToR switch. When a flow threshold is determined for each ToR switch, it notifies the ToR switch control unit 53.

[0045] In addition, in FIG. 7, the flow threshold is not changed when the index value is less than the threshold, but the flow threshold may be set to be increased.

[0046] Also, although an example has been shown in which the ToR switch control unit 53 changes the flow threshold, another part of the communication control device 5 may change the flow threshold, and the ToR switch control unit 53 may perform the setting.

[0047] [Embodiment 4] Regarding the load of the electric switch unit 3, each electric communication Alternatively, the packet transfer delay or packet loss rate in the device may be used.

[0048] More specifically, the process shown in Fig. 8 is executed by, for example, the ToR switch control unit 53. For example, steps S31 to S39 are executed at predetermined time intervals.

[0049] The electrical switch control unit 51 acquires the packet transfer delay or packet loss rate of each telecommunications device from the corresponding telecommunications device in the electrical switch unit 3, and the ToR switch control unit 53 acquires the packet transfer delay or packet loss rate of each telecommunications device from the electrical switch control unit 51 (step S31). The ToR switch control unit 53 identifies a statistic as an index value corresponding to the packet transfer delay or packet loss rate of each telecommunications device (step S33). The statistic may be, for example, an average value, a median value, or a maximum value.

[0050] The ToR switch control unit 53 then compares the identified index value with a predetermined threshold for that index value, and determines whether the index value is equal to or greater than the threshold (step S35). If the index value is equal to or greater than the threshold, the ToR switch control unit 53 executes a setting for each ToR switch to, for example, lower the flow threshold by a predetermined value so as not to further increase packet transfer delays or packet discard rates (step S37). That is, a setting is made to increase the use of the optical switch unit 4. Then, the process proceeds to step S39. On the other hand, if the index value is less than the threshold, the process proceeds to step S39 without performing any particular process.

[0051] Then, the ToR switch control unit 53 determines whether to terminate the processing due to, for example, an instruction to stop changing the flow threshold based on this index value or a power outage (step S39), and if the processing is not terminated, returns to step S31, and if the processing is terminated, terminates the processing.

[0052] By repeating this process, an appropriate flow threshold is dynamically set in accordance with the change over time in the statistics of packet transfer delay or packet discard rate.

[0053] In this process, the same flow threshold is set for each ToR switch, but a different flow threshold may be set for each ToR switch. This is because the ToR switches may differ in performance due to different models, or the configurations and processing conditions of the servers they handle may also differ. For example, the flow threshold set for each ToR switch may be changed by changing the predetermined value for each ToR switch in step S37 of the process flow in FIG. 8. Also, although one flow threshold is calculated in step S37, it may be adjusted for each ToR switch. The communication control device 5, including the ToR switch control unit 53, manages the flow threshold set for each ToR switch.

[0054] In the example described above, the ToR switch control unit 53 changes the flow threshold and sets it for each ToR switch, but if the flow threshold is changed for each ToR switch, the ToR switch may change the flow threshold notified from the ToR switch control unit 53. Furthermore, in Fig. 8, the flow threshold is not changed when the index value is less than the threshold, but the flow threshold may be set to be increased.

[0055] Also, although an example has been shown in which the ToR switch control unit 53 changes the flow threshold, another part of the communication control device 5 may change the flow threshold, and the ToR switch control unit 53 may perform the setting.

[0056] [Embodiment 5] In the above-described embodiment, the flow threshold is adjusted to improve the efficiency of data transfer in an electrical-optical hybrid switch network. However, even if an optical line is set up in an optical circuit switching network, if that optical line is not used effectively, the overall efficiency will not be improved. In other words, if the flow rate (e.g., the number of bytes sent per unit time) through a set optical line is below a threshold, that optical line is not being used effectively, and it would be more efficient to disconnect that optical line and allow the setting up of another optical line. From this perspective, the following processing is performed.

[0057] Specific processing contents will be explained using Fig. 9. Note that the case of transferring data from ToR switch #A to ToR switch #B will be explained as an example.

[0058] First, when the ToR switch #A decides to transfer data via the optical circuit switching network, i.e., the optical switch unit 4, it transmits an optical line setting request to the communication control device 5, requesting the setting up of an optical line with the ToR switch #B (step S41). Whether or not to transfer data via the optical circuit switching network may be determined by determining whether or not the flow has a size exceeding the flow threshold, as in the premise of the first to fourth embodiments, and if the flow has a size exceeding the flow threshold, it may be determined to transfer data via the optical circuit switching network. However, it may also be determined to transfer data via the optical circuit switching network based on other criteria.

[0059] In response to the optical line setting request, the optical switch control unit 52 of the communication control device 5 transmits a connection setting request to the optical communication equipment associated with the optical switch unit 4 (step S43). The communication control device 5 also transmits an optical line connection setting request to the ToR switch #B (step S45). Furthermore, the communication control device 5 transmits a transmission connection request to the ToR switch #A requesting the setting of an optical line and data transmission (step S47).

[0060] The ToR switch #B performs optical line connection setup in response to the optical line connection setup request and returns a reception permission notice to the communication control device 5 (step S49). Furthermore, the ToR switch #A performs optical line connection setup in response to the transmission connection request, prepares for data transmission, and returns a transmission permission notice to the communication control device 5 (step S51). Furthermore, the optical communication device associated with the optical switch unit 4 performs connection setup in response to the connection setup request and sends a connection completion notice to the communication control device 5 (step S52). In this way, upon receiving responses from the ToR switch #B, the ToR switch #A, and the optical switch unit 4, the communication control device 5 sends a data transmission command to the ToR switch #A (step S53). Steps S41 to S53 constitute the optical line connection setup time.

[0061] Upon receiving a transmission command from the communication control device 5, the ToR switch #A starts transmitting data to the ToR switch #B via the set optical line (step S55). The ToR switch #A measures the flow rate of the flow flowing through the set optical line and transmits the flow rate of the flow to the communication control device 5, for example, at predetermined time intervals (steps S57, S61, S65). In response to this, for example, upon receiving the flow rate of the flow from the ToR switch #A, the ToR switch control unit 53 of the communication control device 5 determines whether the flow rate of the flow is equal to or less than a predetermined threshold for the flow rate of the flow (steps S59, S63, S67). If the flow rate of the flow exceeds the threshold, it is determined that the set optical line is being used effectively, and the optical line remains set. In this example, it is assumed that the flow rate of the flow is determined to exceed the threshold in steps S59 and S63.

[0062] On the other hand, in this example, it is assumed that it is determined in step S67 that the flow rate has fallen below the threshold. Then, in order to disconnect the set optical line, the communication control device 5 transmits an optical line release request to the ToR switch #A (step S69). This is the time for data transfer via the optical line.

[0063] When ToR switch #A receives the optical line release request, it starts transmitting data via the electrical switch unit 3 (i.e., the electrical packet network) because there is still data to be transmitted (step S73). The connection switching time is from step S69 until ToR switch #A starts transmitting data via the electrical switch unit 3, and the time from step S73 onwards is the time for transferring data via the electrical switch unit 3. Note that a description of the settings for the electrical switch unit 3 is omitted.

[0064] Meanwhile, the communication control device 5 transmits an optical line connection release request to the optical communication device associated with the optical switch unit 4 (step S71). Also, the communication control device 5 transmits an optical line connection release request to the ToR switch #B (step S75). In response to this, the ToR switch #A performs processing to disconnect the optical line and transmits an optical line release notification to the communication control device 5 (step S77). Also, the optical communication device associated with the optical switch unit 4 performs processing to release the set optical line and transmits a connection release notification to the communication control device 5 (step S79). Furthermore, the ToR switch #B performs processing to disconnect the optical line and transmits an optical line release notification to the communication control device 5 (step S81). By starting data transmission via the electrical packet network before disconnecting the optical line, it is possible to minimize delay time.

[0065] By executing such processing, whether or not to continue the connection of an already established optical line is judged based on the flow rate of the flow through that optical line, and if the flow rate of the flow through that optical line is below a threshold, the optical line is disconnected and data is transferred via the electrical packet network, thereby making effective use of the optical circuit switching network. Note that even if there is a sufficient flow rate initially, a situation may arise in which the flow rate subsequently decreases, and therefore it is possible to deal with such changes in the flow rate over time.

[0066] [Other technical elements] A possible method for detecting blocking is to determine that blocking has occurred if the input / output ports of the optical circuit switching switch that satisfy the optical line setting request from the ToR switch unit 2 are already in use. For example, the optical switch control unit 52 manages the connection status of each optical switch (optical communication equipment) using a table such as that shown in FIG. 10. FIG. 10 shows the connection status of one optical circuit switching switch in the optical switch unit 4, which has P number of input ports and Q number of output ports. Note that the connection status indicates whether connection is possible or not for each combination of input / output ports. If connection is not possible (x) for the number of input ports P and the number of output ports Q in all the optical circuit switching switches (optical communication equipment) in the optical switch unit 4 in FIG. 3, the setting of the optical line between the specific ToR switches is blocked.

[0067] In the example of FIG. 10, each row corresponds to an input port and each column corresponds to an output port. Connectable input / output port pairs are indicated by a circle (○), while input / output port pairs that are already connected or cannot be connected because they are excluded are indicated by a cross (×) or a minus sign (-). Note that pairs of input / output ports with the same number are excluded (-). In this example, input port 2 and output port 1, and input port P and output port 3 are already connected, and pairs related to these input / output ports are indicated by a connected cross (×) or a minus sign (-). Thus, in this embodiment, the connection status of the optical switch unit 4 can be confirmed simply by managing and referencing a table such as that shown in FIG. 10, without managing the connection status of the entire network. The conventional techniques described in Patent Document 1 and Non-Patent Document 2 confirm the availability of all electrical and optical communication devices connected to the electro-optical hybrid switch network and determine whether blocking is occurring and whether line setup is possible. Therefore, this embodiment enables lower latency and simpler control than the conventional techniques.

[0068] [Other embodiments] The above-described embodiment has been described assuming a configuration in which a ToR switch is installed in each rack, as shown in FIG. 1 . However, the present invention is not limited to this. For example, as shown in FIG. 11 , a rack 1-x including connection devices 20-1 to 20-n having functions equivalent to a ToR switch may be installed at the end of racks 1-1 to 1-n, in parallel with racks 1-1 to 1-n, each of which includes one or more servers, memories, etc. The racks 1-1 to 1-n are connected to the connection devices 20-1 to 20-n via electrical or optical links 11. This is called an end-of-row configuration. Alternatively, as shown in FIG. 12 , a middle-of-row configuration may be adopted, in which rack 1-x is located in the middle of racks 1-1 to 1-n. In either case, a one-to-one relationship may be established, such as connection device 20-1 serving rack 1-1 and connection device 20-2 serving rack 1-2, or one or more racks may be served by one connection device 20. Furthermore, there may be cases where the servers and memories that each connection device 20 is responsible for are set independently of the rack.

[0069] That is, the connection devices 20-1 to 20-n having functions equivalent to ToR switches can also cooperate with the communication control device 5 to realize an electro-optical hybrid switch network that enables the above-mentioned low-delay data transfer.

[0070] Although the embodiments of the present invention have been described above, the present invention is not limited to these. For example, the functional configuration example of the communication control device 5 is merely an example and may not correspond to the program module configuration. Furthermore, with regard to the processing flow and operation sequence, the order of steps may be changed or multiple steps may be executed in parallel as long as the processing results are unchanged.

[0071] Furthermore, combinations of the embodiments and combinations of any technical features in each embodiment may be made as needed depending on the purpose.

[0072] The communication control device 5 described above is, for example, a computer device, and as shown in FIG. 13, includes a memory 2501, a CPU (Central Processing Unit) 2503, a hard disk drive (HDD: Hard Disk Drive) 2505, a display control unit 2507 connected to a display device 2509, a drive device 2513 for a removable disk 2511, an input device 2515, and a communication control unit 2517 for connecting to a network. and A peripheral device connector 2521 for connecting peripheral devices to the HDD 2505 is connected via a bus 2519. The HDD may be a storage device such as a solid state drive (SSD). The operating system (OS) and application programs for implementing the processes of the present invention are stored in the HDD 2505 and are read from the HDD 2505 to the memory 2501 when executed by the CPU 2503. The CPU 2503 controls the display control unit 2507, communication control unit 2517, and drive device 2513 according to the processing content of the application program to perform predetermined operations. Data during processing is mainly stored in the memory 2501, but may also be stored in the HDD 2505. For example, the application program for implementing the above-described processes is stored and distributed on a computer-readable removable disk 2511 and installed from the drive device 2513 to the HDD 2505. It may also be installed on the HDD 2505 via a network such as the Internet and the communication control unit 2517. Such a computer device realizes the various functions described above through organic cooperation between hardware such as the CPU 2503 and memory 2501 described above and programs such as the OS and application programs.

[0073] The communication control device 5 may be implemented in a single device, or its functions may be distributed across multiple devices. Also, some of the functions of the electrical switch control unit 51, optical switch control unit 52, and ToR switch control unit 53 may be distributed across the electrical switch unit 3, optical switch unit 4, and ToR switch unit 2. Furthermore, the CPU may be a GPU (Graphics Processing Unit) or FPGA (Field-Programmable Gate Array), etc.

[0074] The above-described embodiment can be summarized as follows.

[0075] A communication control method according to a first aspect of this embodiment is a communication control method for controlling communication between connection devices that are connected via an optical circuit-switched network and via an electric packet network, and each of which is responsible for one or more devices, and includes the steps of (A) acquiring monitor data that is a blocking rate at the time of optical line setup in the optical circuit-switched network, an amount related to a flow forwarded by a connection device (e.g., one or each of the connection devices) to the electric packet network, a buffer usage status in telecommunications equipment in the electric packet network, or a packet forwarding delay or packet discard rate in telecommunications equipment in the electric packet network, and (B) changing, based on the monitor data, a first threshold value (e.g., a flow threshold value in the embodiment) for distinguishing between a first flow forwarded by the connection device via the optical circuit-switched network and a second flow forwarded by the connection device via the electric packet network, wherein the first threshold value is used to identify a flow having a size exceeding the first threshold value as the first flow and to identify a flow having a size equal to or smaller than the first threshold value as the second flow.

[0076] By changing the first threshold based on the monitor data, it becomes possible to appropriately send data from the connection device according to the status of the optical circuit switching network or the electrical packet network, thereby enabling efficient data transfer overall. Note that the changed first threshold or a value determined based on the first threshold (for example, a value adjusted for each individual connection device) may be set in the connection device.

[0077] In the above-described communication control method, if the blocking rate is less than a second threshold determined for the blocking rate, the first threshold may be reduced. A low blocking rate indicates a small number of flows to be transferred through the optical circuit-switched network, and reducing the first threshold increases the number of flows to be transferred through the optical circuit-switched network, thereby improving overall efficiency.

[0078] In the above-described communication control method, if the blocking rate is equal to or greater than the second threshold, the first threshold may be increased. A high blocking rate indicates that there are many flows to be transferred via the optical circuit-switched network, and increasing the first threshold reduces the number of flows to be transferred via the optical circuit-switched network, thereby improving overall efficiency.

[0079] Furthermore, in the above-described communication control method, the amount of the flow may be the amount of traffic transferred by any of the connection devices to the electrical packet network within a certain period of time. In this case, if the amount of traffic exceeds a third threshold value determined for the amount of traffic, the first threshold value for any of the connection devices may be reduced so that the amount of traffic becomes equal to or less than the third threshold value.

[0080] Furthermore, in the above-described communication control method, the flow-related quantity may be a statistic of the amount of traffic transferred by each of the connection devices to the electrical packet network within a certain period of time. In this case, if the traffic amount statistic exceeds a third threshold value determined for the traffic amount statistic, the first threshold value for each of the connection devices may be reduced so that the traffic amount statistic becomes equal to or less than the third threshold value.

[0081] Furthermore, in the above-described communication control method, when an index value according to the buffer usage status is equal to or greater than a fourth threshold value predetermined for the index value, the first threshold value may be lowered so that the index value becomes less than the fourth threshold value. High usage of the buffer in the telecommunications equipment means a high load on the electrical packet network, and lowering the first threshold value to allow more flow to the optical circuit-switched network can reduce the load on the electrical packet network. This can improve overall efficiency.

[0082] Furthermore, in the above-described communication control method, if an index value corresponding to a packet transfer delay or a packet discard rate is equal to or greater than a predetermined fifth threshold value for the index value, the first threshold value may be lowered so that the index value becomes less than the fifth threshold value.

[0083] The packet transfer delay and packet discard rate are also index values ​​that represent the load on the electrical packet network, and if the load on the electrical packet network is high, the first threshold is adjusted to lower it.

[0084] Furthermore, the above-described communication control method may further include the steps of: determining whether the flow rate of a flow flowing through an optical line set between certain connection devices in an optical circuit switching network is equal to or less than a sixth threshold; and, if the flow rate of the flow is equal to or less than the sixth threshold, disconnecting the optical line and transmitting packets related to the flow to the certain connection device that is the source of the flow via an electrical packet network. This is based on the premise that large-sized flows are transmitted through the optical circuit switching network, but if the flow rate of the flow is equal to or less than the threshold, the optical line is being wasted. Therefore, disconnecting the optical line and transferring the flow via the electrical packet network improves overall efficiency.

[0085] A communication control method according to a second aspect of this embodiment is a communication control method for controlling communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network, and each of which is responsible for one or more devices, and includes the steps of (A) determining whether the flow rate of a flow flowing through an optical line set between certain connection devices in the optical circuit switching network is below a threshold, and (B) if the flow rate of the flow is below the threshold, disconnecting the optical line and transmitting packets related to the flow to the certain connection device that is the source of the flow via the electrical packet network.

[0086] A program for causing a computer to execute the above-described method can be created, and the program is stored in various storage media.

Claims

1. A communication control method for controlling communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network, and each of which is responsible for one or more devices, comprising: a blocking rate when setting up an optical line in the optical line switching network; Amounts related to flows forwarded by the connection device to the electrical packet network; Buffer usage in telecommunications equipment within the electrical packet network; or acquiring monitor data representing packet transfer delays or packet loss rates in telecommunication devices within the electrical packet network; changing a first threshold value for distinguishing between a first flow forwarded by the connection device through the optical circuit switched network and a second flow forwarded by the connection device through the electrical packet network, the first threshold value being used to identify a flow having a size exceeding the first threshold value as the first flow and a flow having a size equal to or smaller than the first threshold value as the second flow, based on the monitor data; A communication control method including:

2. If the blocking rate is less than a second threshold value defined for the blocking rate, the first threshold value is decreased. The communication control method according to claim 1.

3. If the blocking rate is equal to or greater than a second threshold value defined for the blocking rate, the first threshold value is increased.

3. The communication control method according to claim 1 or 2.

4. the quantity related to the flow is the quantity of traffic transferred by any of the connection devices to the electrical packet network within a certain period of time; If the amount of traffic exceeds a third threshold value defined for the amount of traffic, the first threshold value for any of the connected devices is reduced so that the amount of traffic becomes equal to or less than the third threshold value. The communication control method according to claim 1.

5. the flow-related quantity is a statistic of the amount of traffic transferred by each of the connection devices to the electrical packet network within a certain period of time; If the traffic volume statistics exceed a third threshold value determined for the traffic volume statistics, the first threshold value for each of the connection devices is reduced so that the traffic volume statistics becomes equal to or less than the third threshold value. The communication control method according to claim 1.

6. When the index value according to the buffer usage status is equal to or greater than a fourth threshold value that is predetermined for the index value, the first threshold value is reduced so that the index value becomes less than the fourth threshold value. The communication control method according to claim 1.

7. When an index value corresponding to the packet transfer delay or the packet discard rate is equal to or greater than a fifth threshold value that is predetermined for the index value, the first threshold value is reduced so that the index value becomes less than the fifth threshold value. The communication control method according to claim 1.

8. determining whether a flow rate of a flow passing through an optical line established between certain connection devices in the optical line switching network is equal to or less than a sixth threshold; If the flow rate of the flow is equal to or less than the sixth threshold, disconnecting the optical line and transmitting packets related to the flow to the certain connection device that is the source of the flow via the electrical packet network; 8. The communication control method according to claim 1, further comprising:

9. A communication control method for controlling communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network, and each of which is responsible for one or more devices, comprising: determining whether a flow rate of a flow passing through an optical line established between certain connection devices in the optical line switching network is equal to or less than a threshold; If the flow rate of the flow is equal to or less than the threshold, disconnecting the optical line and transmitting packets related to the flow to the certain connection device that is the source of the flow via the electrical packet network; A communication control method including:

10. A communication control device that controls communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network and each of which is responsible for one or more devices, The communication control device includes: Memory and a processor connected to the memory; and The processor: a blocking rate when setting up an optical line in the optical line switching network; Amounts related to flows forwarded by the connection device to the electrical packet network; Buffer usage in telecommunications equipment within the electrical packet network; or Obtaining monitor data representing packet transfer delays or packet loss rates in telecommunications devices within the electrical packet network; and changing a first threshold value for distinguishing between a first flow to be transferred by the connection device through the optical circuit switched network and a second flow to be transferred by the connection device through the electrical packet network, the first threshold value being for identifying a flow having a size exceeding the first threshold value as the first flow and a flow having a size equal to or smaller than the first threshold value as the second flow, based on the monitor data. Communications control device.

11. A communication control device that controls communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network and each of which is responsible for one or more devices, The communication control device includes: Memory and a processor connected to the memory; and The processor: In the optical circuit switching network, determining whether a flow rate of a flow passing through an optical line set between certain connection devices is equal to or less than a threshold value; If the flow rate of the flow is equal to or less than the threshold, the optical line is disconnected and packets related to the flow are transmitted to the certain connection device that is the source of the flow via the electrical packet network. Communications control device.

12. A communication control method for controlling communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network, and each of which is responsible for one or more devices, comprising: acquiring monitor data representing a blocking rate at the time of optical line setup in the optical line switching network; changing a first threshold value for distinguishing between a first flow forwarded by the connection device through the optical circuit switched network and a second flow forwarded by the connection device through the electrical packet network, the first threshold value being used to identify a flow having a size exceeding the first threshold value as the first flow and a flow having a size equal to or smaller than the first threshold value as the second flow, based on the monitor data; Including, The blocking rate is Blocking detected when an input / output port of an optical circuit switching switch included in the optical circuit switching network and which satisfies an optical line setting request is already in use is obtained by dividing the number of optical line setting requests detected in a predetermined time by the total number of optical line setting requests within the predetermined time. Communication control method.

13. determining whether a flow rate of a flow passing through an optical line established between certain connection devices in the optical line switching network is equal to or less than a second threshold; If the flow rate of the flow is equal to or less than the second threshold, disconnecting the optical line and transmitting packets related to the flow to the certain connection device that is the source of the flow via the electrical packet network; The communication control method according to claim 12, further comprising:

14. A communication control device that controls communication between connection devices that are connected via an optical circuit switching network and via an electrical packet network and each of which is responsible for one or more devices, The communication control device includes: Memory and a processor connected to the memory; and The processor: Obtaining monitor data representing a blocking rate at the time of optical line setup in the optical line switching network; changing a first threshold value for distinguishing between a first flow forwarded by the connection device through the optical circuit switched network and a second flow forwarded by the connection device through the electrical packet network, the first threshold value being for distinguishing a flow having a size exceeding the first threshold value as the first flow and a flow having a size equal to or smaller than the first threshold value as the second flow, based on the monitor data; The blocking rate is Blocking detected when an input / output port of an optical circuit switching switch included in the optical circuit switching network and which satisfies an optical line setting request is already in use is obtained by dividing the number of optical line setting requests detected in a predetermined time by the total number of optical line setting requests within the predetermined time. Communications control device.

15. The processor: In the optical circuit switching network, determining whether a flow rate of a flow passing through an optical line established between certain connection devices is equal to or less than a second threshold value; If the flow rate of the flow is equal to or less than the second threshold, disconnect the optical line and transmit packets related to the flow to the certain connection device that is the source of the flow via the electrical packet network. The communication control device according to claim 14.

16. 14. A program for causing a processor to execute the communication control method according to any one of claims 1, 2, 4 to 7, 9, 12 and 13.

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