Communication system and communication method

Abstract

In a communication system (50), a FlexBr(Master) (1) and a FlexBr(Slave) (2) each having a bridge function between a low-speed interface and a high-speed interface are connected by an optical path, the FlexBr(Slave) (2) notifies the FlexBr(Master) (1) of information related to the FlexBr(Slave) (2) and including information relating to a data amount currently stored in an input buffer unit to which data is input from a user terminal (20), and the FlexBr(Master) (1) performs bandwidth control of the input buffer unit of the FlexBr(Slave) (2) on the basis of a round-trip delay time calculated from the transmission time of the information related to the FlexBr(Slave) (2) and the reception time of the information related to the FlexBr(Slave) (2), and the information relating to the data amount currently stored in the input buffer unit such that time division multiplex control output in the low-speed interface thereof becomes possible.

Description

Communication system and communication method

[0001] The present disclosure relates to a communication system and a communication method.

[0002] In conventional communication networks, end points are connected via nodes such as optical access devices, optical transmission devices, IP routers, and Ethernet switches arranged in multiple network segments. The Open All-Photonics Network (APN) under the Innovative Optical and Wireless Network (IOWN (registered trademark)) initiative led by Nippon Telegraph and Telephone Corporation, or the All-Optical Network proposed by Huawei, are examples of communication network concepts that eliminate as many nodes that perform conventional photoelectric conversion or electrical processing as possible and connect end points via optical paths as much as possible. As disclosed in Non-Patent Documents 1, 2, 3, and 4, efforts are being made to further increase the capacity, reduce latency, and reduce power consumption of communication networks using innovative technologies centered on light.

[0003] On the other hand, in many use cases, the transmission speed of optical communication equipment is faster than the port speed of the interface (I / F) of the user device, and there is a speed gap in direct connection between end points via optical paths. For example, in the use case of mobile fronthaul of 5G networks such as those proposed by the IOWN (registered trademark) Global Forum (IGF), the speed on the low-speed I / F side is approximately 25 Gbps, and the speed on the network side I / F is 100 Gbps to 400 Gbps. By applying a bridge device that multiplexes and demultiplexes signals from multiple low-speed I / Fs and high-speed I / Fs, a wide variety of devices can be accommodated in the bridge device and connected to the network while effectively utilizing the optical path bandwidth and number of wavelengths on the network side. In the APN (All Photonics Network) of the IOWN (registered trademark) concept, a bridge device that satisfies the Quality of Service (QoS) requirements required in the IGF use case is defined as a Flexible Bridge (FlexBr) node, and several types of FlexBr are defined depending on the QoS requirements that can be satisfied. In particular, Non-Patent Document 4 discloses a technology in which a FlexBr is equipped with an APN-Transceiver (APN-T) that serves as the start and end points of an optical path that enables connection to an APN, and is connected by an optical path between the opposing APN-T and APN.

[0004] Generally, there are several methods for multiplexing and demultiplexing signals in bridge devices, including OTN (Optical Transport Network) signal processing, which performs multiplexing and demultiplexing on a port-by-port basis, the Flexible Ethernet (FlexE) method, and Layer 2 multiplexing and demultiplexing on an Ethernet frame-by-frame basis. Layer 2 bridge devices such as conventional switches perform multiplexing and demultiplexing on an Ethernet frame-by-frame basis by storing data in a buffer built into the device, saving data that exceeds the port transmission speed or the specified communication capacity inside the communication device, and reading the data from the buffer at a rate determined by the set rate in shaping, which is transmitted when capacity becomes available.

[0005] Nippon Telegraph and Telephone Corporation "IOWN | NTT R&D Website" [searched on 20247.05.16], Internet <URL: https: / / www.rd.ntt-iown / > Huawei Technologies Co., Ltd. "All-Optical Network" [searched on 20247.05.16], Internet <URL: https: / / www-file.huawei. com / - / media / corp2020 / pdf / giv / striding-Towards-The-intelligent-world-The_intelligent_world_all_optical_network_en.pdf?la=en> Huawei Technologies Co., Ltd. "Expectations for a green all-optical network for the super data society" [Retrieved 20247.05.16], Internet <URL: https: / / mpls-jp / 2022 / presentations / mpls2022-Huawei_Nan_Jiang.pdf Innovative Optical Wireless Network Global Forum, Inc. "Open All-Photonic Network Functional Architecture" [Retrieved May 16, 2024], Internet <URL: https: / / / -iowngf.org / wp-content / uploads / formidable / 21-iOWN-GF-RD-Open_APN_Functional_Architecture-2.0.pdf>

[0006] As described in Non-Patent Documents 1 to 4, for example, in a case where user terminal information from multiple locations is aggregated using a Layer 2 multiplexing / demultiplexing FlexBr and transferred to a corresponding data center server via an APN, when data transfer occurs simultaneously from multiple locations, data congestion does not occur because the network-side interface between the APNs is broadband, but data congestion may occur because the user device-side interface speed for transferring data to the server is slow. To avoid this congestion, conventional Layer 2 bridge devices employ a method of buffering all of this burst data or applying bandwidth control through flow control. However, with regard to the former, buffering all burst data from multiple locations in a single location on the server side using the APN's high-speed interface increases the complexity of the electrical design, potentially resulting in higher costs and increased power consumption. Regarding the latter issue, the former problem can be avoided because buffering can be performed not only on the server side but also at multiple locations on the user side. However, since many use cases that utilize APN involve long-distance transfers, there is a problem that when congestion occurs, flow control from the server side to the user side cannot be completed in time, resulting in data loss.

[0007] There is also a method of performing time division multiplexing control between bridge devices, as in a PON (Passive Optical Network) system, but unless it is an optical path connection network, there are problems such as large delays or delay jitter when nodes such as optical transmission devices, IP routers, or Ethernet switches are installed between bridge devices installed near the end points, making time division multiplexing control between bridge devices difficult.

[0008] An object of the present disclosure is to provide a communication system and a communication method that can reduce costs, power consumption, and data loss by distributing buffering.

[0009] The communication system disclosed herein is characterized in that in a network in which a main bridge device and a sub bridge device, each having a bridge function between a low-speed interface and a high-speed interface, are connected via an optical path, the sub bridge device notifies the main bridge device of information related to the sub bridge device, including information on the amount of data currently stored in an input buffer into which data is input from a user terminal, and the main bridge device controls the bandwidth of the input buffer in the sub bridge device so as to enable time-division multiplexed control output at the low-speed interface of the main bridge device, based on the round-trip delay time calculated from the time the information related to the sub bridge device was sent and the time the information related to the sub bridge device was received, and the information on the amount of data currently stored in the input buffer.

[0010] In a communication system of the present disclosure, in a network in which a master bridge device and a slave bridge device, each having a bridge function between a low-speed interface and a high-speed interface, are optically connected, a bandwidth control device that controls the bandwidth of the slave bridge device is optically connected to the network, and the master bridge device notifies the slave bridge device and the bandwidth control device of a master-slave round trip delay time calculated from the transmission time of a control signal transmitted from the slave bridge device and the reception time of the control signal, and the slave bridge device notifies the slave bridge device and the bandwidth control device of a master-slave round trip delay time calculated from the transmission time of the control signal transmitted from the bandwidth control device and the reception time of the control signal. The main bridge device and the bandwidth control device are each notified of information on the master-slave round trip delay time, the master-slave round trip delay time, and the amount of data currently stored in the input buffer into which data is input from the user terminal, and the bandwidth control device controls the bandwidth of the input buffer in the slave bridge device based on the information on the master-slave round trip delay time, the master-slave round trip delay time, and the amount of data currently stored in the input buffer of the slave bridge device, which are shared with the main bridge device and the slave bridge device, so as to enable time division multiplexed control output at the low speed interface of the main bridge device.

[0011] In a network in which a main bridge device and a sub bridge device, each having a bridge function between a low-speed interface and a high-speed interface, are optically connected, the method includes the steps of: the sub bridge device notifying the main bridge device of information related to the sub bridge device, including information on the amount of data currently stored in an input buffer into which data is input from a user terminal; and the main bridge device controlling the bandwidth of the input buffer in the sub bridge device so as to enable time-division multiplexed control output at the low-speed interface of the main bridge device, based on the round-trip delay time calculated from the time of sending the information related to the sub bridge device and the time of receiving the information related to the sub bridge device, and the information on the amount of data currently stored in the input buffer.

[0012] According to the present disclosure, by taking advantage of the characteristics of an optical path connection network with low latency and small delay jitter, time division multiplexing control is performed to avoid frame collisions between transmission devices, and dynamic bandwidth allocation according to the buffer capacity between devices is applied, thereby providing a communication system and communication method that can reduce costs, power consumption, and data loss by distributing buffering.

[0013] 1 is a network configuration diagram of a communication system according to embodiment 1. FIG. 2 is a block diagram showing an example of the configuration of a FlexBr (Master) according to embodiment 1. FIG. 3 is a block diagram showing an example of the configuration of a FlexBr (Slave) according to embodiment 1. FIG. 4 is an example of a table of an information collection and storage unit of a FlexBr (Master) according to embodiment 1, where (A) shows a FlexBr (Slave), an APN-T transmission unit of the FlexBr (Slave), and a delay amount corresponding to a port number of an APN-T reception unit of the FlexBr (Master), and (B) shows a CP transmission unit of the FlexBr (Master) and a maximum buffer capacity corresponding to a CP reception unit of the FlexBr (Slave). FIG. 5 is an example of a table of a report information storage unit of a FlexBr (Master) according to embodiment 1. 1 is a timing chart showing the operation of static information collection between a FlexBr (Master) and a FlexBr (Slave) according to the first embodiment. FIG. 2 is a timing chart showing the operation of data signal transmission / reception using time division multiplexing between a FlexBr (Master) and a FlexBr (Slave) according to the first embodiment. FIG. 3 is a timing chart showing the operation of data signal transmission / reception between a FlexBr (Master) and a FlexBr (Slave) according to the prior art. FIG. 4 is a flowchart showing an example of a bandwidth allocation process for a FlexBr (Slave) by a FlexBr (Master) according to the first embodiment. FIG. 5 is a flowchart of data transmission control and Report frame transmission by a FlexBr (Slave) according to the first embodiment. FIG. 6 is a network configuration diagram of a communication system according to a second embodiment.

[0014] Hereinafter, a communication device according to an embodiment will be described with reference to the drawings. The following embodiments are merely examples, and the embodiments can be appropriately combined and modified.

[0015] First Embodiment In the first embodiment, an example of application to a bridge device (FlexBr) having a bridge function between a low-speed interface and a high-speed interface in an APN will be described. A bridge device that controls bandwidth will be referred to as a master, and a bridge device that controls output will be referred to as a slave. FIG. 1 is a network configuration diagram of a communication system 50 according to the first embodiment. FlexBr (Master) 1 is connected to N FlexBr (Slave) #1 (2_1) to FlexBr (Slave) #N (2_N) via an APN 15. As an example, we will explain a case where a server device 10 is connected to a FlexBr (Master) 1 in a data center 18 via a user N / W 16, and a user terminal 20 is connected to FlexBr (Slave) 2_1 to 2_N (hereinafter abbreviated as "FlexBr (Slave) 2" depending on the situation) in a central office or user base (central office / user site 19) via a user N / W 17.

[0016] 2 is a block diagram showing an example of the configuration of the FlexBr (Master) 1 according to the first embodiment. The function of the input / output port, which is the external I / F of the FlexBr (Master) 1, will be explained using FIG. 2. As shown in FIG. 2, the Client Port (CP) #1 to CP #i transmitter 100_Tx (hereinafter abbreviated as "CP transmitter 100_Tx" depending on the situation) of the FlexBr (Master) 1 transmits the input signal from the signal separator 110 to an external device on the server device 10 side.

[0017] The CP#1 to CP#i receiving unit 100_Rx (hereinafter abbreviated as "CP receiving unit 100_Rx" depending on the situation) of FlexBr (Master) 1 receives signals from outside the server device 10 and outputs them to input buffer units 141_1 to 141_i (hereinafter abbreviated as "input buffer unit 141" depending on the situation). Also, the APN-T transmitting units #1 to #j 101_Tx (hereinafter abbreviated as "APN-T transmitting unit 101_Tx" depending on the situation) of FlexBr (Master) 1 output input signals from the signal multiplexing unit 140 to the APN 15 side and transmit them to the opposing device FlexBr (Slave) 2. Then, the APN-T receiving units #1 to #j101_Rx (hereinafter abbreviated as "APN-T receiving unit 101_Rx" depending on the situation) of FlexBr (Master) 1 receive input signals from the opposing device FlexBr (Slave) 2 and output them to the input buffer units 111_1 to 111_j (hereinafter abbreviated as "input buffer unit 111" depending on the situation) of the signal separation unit 110.

[0018] Next, the main signal processing function of the FlexBr (Master) 1 will be described. The signal separator 110 has the function of separating a high-speed signal received from the FlexBr (Slave) 2 on the APN 15 side into a low-speed main signal for each CP transmitter 100_Tx and a control signal to be processed inside the FlexBr (Master) 1. The main signal is distributed to each CP transmitter 100_Tx on a frame-by-frame basis according to the destination CP transmitter 100_Tx. A Report frame, which is a control signal described below, is transmitted to the dynamic bandwidth allocation unit 130, and a FlexBr (Slave) information frame is transmitted to the static information collection unit 120.

[0019] The dynamic bandwidth allocating unit 130 outputs a Gate frame, and the static information collecting unit 120 outputs a FlexBr (Master) information frame, to the signal multiplexing unit 140. The signal multiplexing unit 140 multiplexes the low-speed main signals received from each port on the CP receiving unit 100_Rx side and the control frames inside the FlexBr (Master) 1 into a high-speed main signal. The main signals from each port of the CP receiving unit 100_Rx, the FlexBr (Master) information frames from the static information collecting unit 120, which are control signals, and the Gate frames from the dynamic bandwidth allocating unit 130 are distributed on a frame-by-frame basis to the ports of each APN-T transmitting unit 101_Tx.

[0020] Next, a description will be given of the static information collection unit 120 that performs control signal processing to collect static information of the FlexBr (Slave) 2 used for bandwidth allocation. The static information collection unit 120 includes a delay information collection unit 121, a buffer information collection unit 122, and a collected information holding unit 123.

[0021] The static information collection unit 120 generates a FlexBr (Master) information frame for transmitting static information when linking with FlexBr (Slave) 2. The FlexBr (Master) information frame also describes a timestamp, port configuration information for the CP transmitter 100_Tx of FlexBr (Master) 1, and distribution setting information for the CP transmitter 100_Tx using a VLAN (Virtual Local Area Network) or the like.

[0022] The delay information collector 121 has time information and measures the transmission delay time between its own device, FlexBr (Master) 1, and its opposing device, FlexBr (Slave) 2, based on the timestamp of the FlexBr (Slave) information frame, and writes the delay information to the information holder 123. Because an optical path connection is established between FlexBr (Master) 1 and FlexBr (Slave) 2, the delay jitter is small and the delay information can be treated as static information.

[0023] The buffer information collection unit 122 collects information such as the maximum buffer capacity of the opposing device FlexBr (Slave) 2 based on the information in the FlexBr (Slave) information frame, and writes the information to the collected information holding unit 123. The collected information holding unit 123 then holds the written information. FIG. 4 shows an example of a table showing an example of the information written in the collected information holding unit 123. FIG. 4(A) shows FlexBr (Slave) 2, APN-T transmitters #1 to #j201_Tx of FlexBr (Slave) 2 (hereinafter abbreviated as "APN-T transmitter 201_Tx" depending on the situation), and the amount of delay, which correspond to the port number of the APN-T receiver 101_Rx of FlexBr (Master) 1. Also, Figure 4 (B) shows the CP transmitter 100_Tx of FlexBr (Master) 1, which corresponds to the CP#1 to CP#i receiver 200_Rx (hereinafter abbreviated as "CP receiver 200_Rx" depending on the situation) of FlexBr (Slave) 2, and the maximum buffer capacity.

[0024] Next, a description will be given of the dynamic bandwidth allocating unit 130 that performs processing for time division multiplexing control. The dynamic bandwidth allocating unit 130 includes a report processing unit 131, a report information holding unit 132, a bandwidth allocation calculation unit 133, and a gate generation unit 134.

[0025] The report processing unit 131 writes the transmission request amount of the opposite device from the report frame from the opposite device FlexBr (Slave) 2 into the report information holding unit 132 .

[0026] The report information holding unit 132 holds the transmission request amount. An example table of the transmission request amount is shown in Fig. 5. Fig. 5 shows the CP transmission unit 100_Tx of FlexBr (Master) 1 corresponding to the port number of the APN-T transmission unit 201_Tx of FlexBr (Slave) 2, and the report amount which is the transmission request amount.

[0027] The bandwidth allocation calculation unit 133 calculates a bandwidth allocation that can be transmitted from the opposing device FlexBr (Slave) 2 to the APN 15 side based on the information on the transmission request amount in the report information storage unit 132 and the minimum bandwidth allocation information in the collected information storage unit 123.

[0028] The gate generation unit 134 generates a gate frame for the FlexBr (Slave) 2 to perform output control based on the bandwidth calculated by the bandwidth allocation calculation unit 133 .

[0029] 3 is a block diagram showing an example of the configuration of the FlexBr (Slave) 2 according to embodiment 1. The function of the input / output port, which is the external I / F of the FlexBr (Slave) 2, will be described using FIG.

[0030] The CP#1 to CP#i transmitting units 200_Tx (hereinafter abbreviated as "CP transmitting units 200_Tx" depending on the situation) transmit the input signals from the signal separating unit 240 to an external device on the user terminal 20 side.

[0031] The CP receiving unit 200_Rx receives a signal from outside the server device 10 and outputs it to input buffer units 211_1 to 211_i (hereinafter abbreviated as "input buffer unit 211" depending on the situation).

[0032] The APN-T transmitter 201_Tx outputs the input signal from the signal multiplexer 210 to the APN 15 side, and transmits it to the FlexBr (Master) 1, which is the opposite device.

[0033] The APN-T receiving units #1 to #j 201_Rx (hereinafter abbreviated as "APN-T receiving unit 201_Rx" depending on the situation) output input signals from the opposing device, FlexBr (Master) 1, to input buffer units 241_1 to 241_j (hereinafter abbreviated as "input buffer unit 241" depending on the situation).

[0034] Next, the main signal processing function will be described. The signal separator 240 has the function of separating a high-speed signal received from the FlexBr (Master) 1 on the APN 15 side into a low-speed main signal for each CP transmitter 200_Tx and a control signal to be processed inside the FlexBr (Slave) 2. The main signal is distributed to each CP transmitter 200_Tx on a frame-by-frame basis according to the destination CP transmitter 200_Tx. The signal separator 240 also transmits a FlexBr (Master) information frame, which is a control signal, to the static information collector 220, and transmits a Gate frame to the output controller 230.

[0035] The signal multiplexing unit 210 multiplexes the low-speed main signals received from each port on the CP receiving unit 200_Rx side with the control frames inside the FlexBr (Slave) 2. The signal multiplexing unit 210 distributes and multiplexes the main signals from each CP receiving unit 200_Rx, the FlexBr (Master) information frames from the static information collecting unit 220, and the Report frames from the output control unit 230 for each port of the APN-T transmitting unit 201_Tx.

[0036] Next, a description will be given of the static information collection unit 220 that performs control signal processing for static information collection. The static information collection unit 220 includes a delay information collection unit 221 and a buffer information collection unit 222.

[0037] The static information collection unit 220 outputs a FlexBr (Slave) information frame to the signal multiplexing unit 210 for notifying the FlexBr (Master) 1, which is the opposing device, of control information.

[0038] The delay information collecting unit 221 synchronizes time with a timestamp extracted from a FlexBr (Master) information frame received from the opposing device, FlexBr (Master) 1. Then, the transmission time of the FlexBr (Slave) information frame based on the synchronized time is embedded as a timestamp in the FlexBr (Slave) information frame.

[0039] The buffer information collection unit 222 sets the buffer amount, which is the capacity of the input buffer unit 211, and the configuration in the input buffer unit 211 based on the port configuration information of the CP transmitting unit 100_Tx of the opposing device FlexBr (Master) 1 described in the FlexBr (Master) information frame, and embeds the set buffer amount and configuration in the response frame.

[0040] Next, a description will be given of the output control unit 230 that processes control signals for time division multiplexing control. The output control unit 230 includes a report generation unit 231 and a gate processing unit 232.

[0041] The report generation unit 231 generates a report frame based on the amount of data currently stored in the input buffer unit 211 and outputs it to the signal multiplexing unit 210 .

[0042] The Gate processing unit controls transmission to the APN 15 side by controlling the output ON / OFF of the output buffer based on the bandwidth allocation information notified by the Gate frame from the FlexBr (Master) 1.

[0043] For simplicity of explanation, the following operation will be described under the following assumptions: FlexBr is a bridge device of Layer 2, so it is possible to allocate ports on a frame-by-frame basis, but CP reception data from the user terminal 20 of FlexBr (Slave) 2 is allocated to a single CP transmission unit 100_Tx of FlexBr (Master) 1 determined for each CP reception unit 200_Rx of FlexBr (Slave) 2. If it is necessary to distribute the CP receiving unit 200_Rx of FlexBr (Slave) 2 to multiple CP transmitting units 100_Tx of FlexBr (Master) 1, FlexBr (Slave) 2 can grasp the distribution setting information of FlexBr (Master) 1, provide separate input buffers for each CP transmitting unit 100_Tx to which FlexBr (Master) 1 distributes, and perform bandwidth control in units of the divided buffers (queues), thereby realizing the following operations.

[0044] Also, the port speed of the APN-T transmitter 201_Tx is not assumed to be a bottleneck during time division multiplexing control. If the APN-T speed could become a bottleneck when the received data of multiple CP receivers 200_Rx are simultaneously multiplexed and output to the port of the same APN-T transmitter 201_Tx, the following operation can be realized by identifying the port of the APN-T transmitter 201_Tx of FlexBr (Slave) 2 during bandwidth allocation by FlexBr (Master) 1 and allocating bandwidth taking into account the maximum transmission speed of the port of the APN-T transmitter 201_Tx.

[0045] A FlexBr (Slave) 2 is connected only to a single FlexBr (Master) 1. If each port of the APN-T transmitter 201_Tx of the FlexBr (Slave) 2 is connected to a different FlexBr (Master) 1, the following operation is possible by dividing the buffer into separate buffers for each FlexBr (Master) 1 and controlling the bandwidth in divided buffer units. In other words, the FlexBr (Slave) 2 only needs to be provided with a buffer that receives output control instructions in a unit and configuration that enables time-division multiplexed output in the CP transmitter 100_Tx of the FlexBr (Master) 1.

[0046] Next, the operation of sharing, setting, and collecting static information between FlexBr (Master) 1 and FlexBr (Slave) 2 will be described. FIG. 6 is a time chart of the operation of collecting static information according to the first embodiment. The sequence shown in FIG. 6 is an example, and any method is acceptable as long as the static information required for time division multiplexing control can be shared, set, and collected between FlexBr (Master) 1 and FlexBr (Slave) 2. After the port of the APN-T transmitter 101_Tx transitions to Link up, FlexBr (Master) 1 transmits a FlexBr (Master) information frame to FlexBr (Slave) 2. The FlexBr (Master) information frame describes the transmission time stamp of FlexBr (Master) 1, the port configuration of the CP transmission unit 100_Tx, distribution setting information for the CP transmission unit 100_Tx, etc. FlexBr (Slave) 2 extracts the time stamp from the received frame and synchronizes time with FlexBr (Master) 1. It also sets the buffer capacity and configuration in the input buffer unit 211 based on the FlexBr (Master) information. Information about FlexBr (Slave) 2, including the transmission time stamp of the FlexBr (Slave) information frame, the set buffer capacity, and the configuration, etc., is described in the FlexBr (Slave) information frame and sent to FlexBr (Master) 1. FlexBr (Master) 1 grasps and stores delay information (Round-Trip-Time: RTT) of the optical path of APN 15 based on the transmission timestamp of the FlexBr (Slave) information frame and the reception time of the FlexBr (Slave) information frame. In the sequence shown in Figure 6, delay information between FlexBr (Master) 1 and FlexBr (Slave) 2, as well as static information required for dynamic bandwidth control such as the settings of each device, are shared and collected. When there is a change in the static information, the sequence shown in Figure 6 is executed again.

[0047] A time chart of time-division bandwidth control operation will be explained. The following method is merely an example, and it is sufficient if FlexBr (Master) 1 can control the bandwidth of each FlexBr (Slave) 2. Even when FlexBr (Master) 1 and FlexBr (Slave) 2 are far apart, bandwidth control using the main signal and in-channel control signal is desirable to improve the real-time nature of dynamic bandwidth allocation, and as an example, the Gate / Report frame used in PON systems will be applied and explained.

[0048] 7 is a time chart showing an example of data transmission and reception between FlexBr (Master) 1 and FlexBr (Slave) 2 according to the first embodiment. FlexBr (Master) 1 transmits a Gate frame, which is a transmission control instruction frame, to each FlexBr (Slave) 2. FlexBr (Slave) 2 controls the output of data transmission to the port of APN-T transmitter 201_Tx in accordance with time information based on the start time (Grant Start-Time: GST) or transmission time (Grant Length: GL) described in the Gate frame received from FlexBr (Master) 1. At that time, FlexBr (Slave) 2 also transmits a Report frame to notify FlexBr (Master) 1 of the amount of data currently stored in the input buffer unit 211. By repeating this series of sequences, data is transmitted from the CP receiving unit 200_Rx of FlexBr (Slave) 2 to the CP transmitting unit 100_Tx of FlexBr (Master) 1 by time division multiplexing.

[0049] In conventional Layer 2 bridge devices, all burst data was sometimes buffered to avoid congestion, but buffering all burst data from multiple locations at a single location on the server side using the high-speed I / F of APN15 as shown in Figure 8 increases the complexity of the electrical design and may result in higher costs and increased power consumption. However, as shown in Figure 7, in embodiment 1, data transmission is performed sequentially using time division multiplexing control, so congestion like in conventional technology can be avoided.

[0050] Next, the process for calculating the bandwidth that FlexBr (Master) 1 allocates to each CP of FlexBr (Slave) 2 will be described. This is merely an example, and it is sufficient to allocate bandwidth taking into account the RTT associated with long-distance transmission and to implement bandwidth control that takes into account buffer overflow in FlexBr (Slave) 2. Furthermore, although frame priority is not taken into account in the following example, bandwidth allocation may be performed taking into account the priority of frames buffered in FlexBr (Slave) 2. In the following example, bandwidth allocation is performed periodically, with this period being the bandwidth update period (time is a setting parameter), and bandwidth is allocated by each CP transmitter 100_Tx of FlexBr (Master) 1 in units of CP receivers 200_Rx of FlexBr (Slave) 2. Also, like a PON system, output control to the APN 15 side is performed by the GST and GL for each CP receiving unit 200_Rx of the FlexBr (Slave) 2. Figure 9 is a flowchart showing an example of a bandwidth allocation process for the FlexBr (Slave) 2 by the FlexBr (Master) 1 according to the first embodiment. In S1-9-1, the FlexBr (Master) 1 starts processing for each bandwidth update period.

[0051] In S1-9-2, FlexBr (Master) 1 calculates the minimum bandwidth allocation amount. If FlexBr (Master) 1 and FlexBr (Slave) 2 are far apart, the round trip time (RTT) becomes large, and there is a delay between when FlexBr (Master) 1 receives a report from FlexBr (Slave) 2 and when the gate frame arrives from FlexBr (Master) 1 to FlexBr (Slave) 2, and during that time, the input buffer unit 211 of FlexBr (Slave) 2 may overflow. To avoid buffer overflow, the minimum bandwidth allocation amount per CP receiving unit 200_Rx of FlexBr (Slave) 2 is calculated based on the collected static information and setting parameters. The calculation formula is the following formula (1). The Max-input Rate (MIR) in formula (1) is the traffic rate that is the basis for calculating the minimum bandwidth allocation, and is a setting parameter. In formula (1), Max Buffer is the maximum buffer capacity of the CP receiving unit 200_Rx of the target FlexBr (Slave) 2, and RTT is the round-trip delay time with the target FlexBr (Slave) 2, which are collected static information. If the result in the following formula is negative, the minimum bandwidth allocation is set to 0 because the buffer will not overflow due to the RTT.

[0052]

[0053] In S1-9-3, FlexBr (Master) 1 determines whether the total value of all minimum bandwidth allocation amounts exceeds the transmission speed of the CP transmitter 100_Tx of FlexBr (Master) 1. If the total value of the minimum bandwidth allocation amounts exceeds the transmission speed of the CP transmitter 100_Tx in S1-9-3, the procedure proceeds to S1-9-4, and if the total value of the minimum bandwidth allocation amounts does not exceed the transmission speed of the CP transmitter 100_Tx, the procedure proceeds to S1-9-5.

[0054] In S1-9-4, FlexBr (Master) 1 notifies FlexBr (Slave) 2 that the minimum bandwidth allocation exceeds the bandwidth available for transmission by the CP transmission unit 100_Tx of FlexBr (Master) 1. Upon receiving the notification, FlexBr (Slave) 2 takes measures such as changing the maximum buffer size or changing the transfer destination FlexBr (Master) 1 (changing the server device 10), and restarts static information collection.

[0055] In S1-9-5, the FlexBr (Master) 1 waits for all Report frame information from the CP receiving unit 200_Rx of the FlexBr (Slave) 2.

[0056] In S1-9-6, FlexBr (Master) 1 determines whether the report amount for the CP receiving unit 200_Rx of FlexBr (Slave) is 0. If the report amount for the CP receiving unit 200_Rx is 0 in S-9-6, the procedure proceeds to S1-9-7, and if the report amount for the CP receiving unit 200_Rx is not 0, the procedure proceeds to S1-9-8.

[0057] In S1-9-7, if the report amount is 0 for each CP receiving unit 200_Rx of FlexBr (Slave) 2, FlexBr (Master) 1 assigns only the minimum bandwidth allocation to the CP receiving unit 200_Rx of that FlexBr (Slave), and assigns 0 to the dynamic bandwidth allocation.

[0058] In S1-9-8, FlexBr (Master) 1 calculates the buffer overflow time for each CP receiving unit 200_Rx of FlexBr (Slave) 2 using the following formula (2) based on the report amount.

[0059]

[0060] In S1-9-9, FlexBr (Master) 1 calculates the dynamic bandwidth allocation amount based on the buffer overflow time for each CP receiver 200_Rx of FlexBr (Slave) 2. The surplus bandwidth is calculated by subtracting the sum of the minimum bandwidth allocations for each CP receiver 200_Rx of FlexBr (Slave) 2 from the transmission speed of the CP transmitter 100_Tx of FlexBr (Master) 1. FlexBr (Master) 1 proportionally distributes the surplus bandwidth to each CP receiver 200_Rx of FlexBr (Slave) 2 according to the buffer overflow time, resulting in dynamic bandwidth allocation. Furthermore, the GL given to the CP receiver 200_Rx of FlexBr (Slave) is the sum of the minimum bandwidth allocation and the dynamic bandwidth allocation.

[0061] In S1-9-10, FlexBr (Master) 1 writes the GST and GL of the CP receiving unit 200_Rx of FlexBr (Slave) 2 in the Gate frame and transmits the Gate frame to FlexBr (Slave) 2. The GST is the value obtained by subtracting the RTT. After executing S1-9-10, the procedure returns to S1-9-1, and FlexBr (Master) 1 resumes the processing shown in FIG. 9 for each bandwidth update period.

[0062] Next, the process by which FlexBr (Slave) 2 transmits data and a Report frame will be described. The following description is an example of transmission processing, and any method will do as long as the amount of data currently stored in the input buffer unit 211 can be notified to FlexBr (Master) 1 and the data can be transmitted in accordance with instructions from FlexBr (Master) 1. Figure 10 is a flowchart showing an example of Report / data transmission per CP receiver 200_Rx of FlexBr (Slave) 2 according to embodiment 1. In S1-10-1, FlexBr (Slave) 2 starts processing when the time on FlexBr (Slave) 2 reaches the GST described in the Gate frame received from FlexBr (Master) 1.

[0063] In step S1-10-2, the FlexBr (Slave) 2 transmits the data in the input buffer 211 for the period of GL described in the Gate frame received from the FlexBr (Master) 1.

[0064] In S1-10-3, FlexBr (Slave) 2 determines whether data remains in the input buffer unit 211 of FlexBr (Slave) after the GL period. If data exceeding the GL amount enters the CP receiving unit 200_Rx of FlexBr (Slave) in a burst, data remains. If data remains in the input buffer unit 211 in S1-10-3, the procedure proceeds to S1-10-5, and if no data remains in the input buffer unit 211, the procedure proceeds to S1-10-4.

[0065] In S1-10-4, if there is no remaining data in the input buffer unit 211, the FlexBr (Slave) 2 sets the Report amount to 0 and transmits the Report frame to the FlexBr (Master) 1.

[0066] In S1-10-5, FlexBr (Slave) 2 determines whether the input buffer unit 211 may overflow by the next bandwidth update period based on the amount of remaining data. One example of the determination formula is the following formula (3). In S1-10-5, if the value on the left side of formula (3) exceeds the value on the right side, the result is TRUE, and it is determined that the input buffer unit 211 may overflow.

[0067]

[0068] In S1-10-6, FlexBr (Slave) 2 determines that the input buffer unit 211 will not overflow by the next bandwidth update period, and transmits a Report frame in which the Report amount is equal to the remaining data amount to FlexBr (Master) 1.

[0069] In S1-10-7, FlexBr (Slave) 2 calculates the amount of additional transmission data using the following formula (4) so ​​that the amount of data will not overflow until the next bandwidth update period.

[0070]

[0071] In S1-10-8, FlexBr (Slave) 2 transmits to FlexBr (Master) 1 a Report frame in which the Report amount is the difference between the remaining data and the additional transmission data.

[0072] In S1-10-9, FlexBr (Slave) 2 transmits additional transmission data between the end of the GL period and the start of the next GST. In order to minimize data loss due to buffer overflow in the input buffer unit 111 of FlexBr (Master) 1, the data is shaped at a rate based on the amount of additional transmission data and the time until the next GST. Since the additional transmission data is data transmission outside the bandwidth allocated by FlexBr (Master) 1, an amount exceeding the transmission speed of the CP transmission unit 100_Tx of FlexBr (Master) 1 may temporarily be transmitted to FlexBr (Master) 1. For this reason, it is desirable to be able to switch between enabling and disabling this additional transmission data processing in the settings depending on the network design concept.

[0073] In the first embodiment, the buffer is placed as an input buffer on the receiving port side, but it may also be provided as an output buffer on the transmitting port side. In that case, a buffer is provided for each destination CP of FlexBr (Master) 1, and bandwidth control is performed on that buffer basis. The bandwidth allocation method has been explained using dynamic bandwidth allocation using Gate / Report frames and static bandwidth allocation according to RTT, but bandwidth control may also be performed using dynamic shaping according to traffic volume, or fixed bandwidth allocation without Report may be used.

[0074] In the example of the network configuration, the APN-T of FlexBr (Master) 1 and the APN-T of FlexBr (Slave) 2 are connected point-to-point, but the APN-Ts of FlexBr (Master) 1 and multiple FlexBr (Slave) 2 may be connected in a ring shape, and bandwidth control including the APN-T port may be performed.

[0075] 10, instead of shaping and transmitting data, FlexBr (Slave) 1 may control the bandwidth of the network on the CP side (low-speed interface side). The bandwidth control method may be, for example, flow control, or, if the CP has PON functionality, it may adjust the bandwidth allocation in the PON system.

[0076] As described above, time division multiplexing control is possible between a FlexBr (Master) 1 and multiple FlexBr (Slave) 2 connected via an optical path such as APN 15, due to low latency and small delay jitter. In the first embodiment, bandwidth control is performed from the FlexBr (Master) 1 to multiple FlexBr (Slave) 2, taking into consideration the delay time between the FlexBr (Master) 1 and the FlexBr (Slave) 2, which affects the transmission speed of the port on the server side or user device side, and the maximum buffer capacity of the FlexBr (Slave) 2. As a result, buffering can be distributed, and congestion due to frame collisions can be suppressed even if traffic is concentrated on a specific FlexBr (Master) 1 server-side port. Furthermore, assuming the control according to the first embodiment, it is possible to reduce the number of buffers provided in the device, thereby enabling lower costs and lower power consumption of the device.

[0077] <<Embodiment 2>> Next, embodiment 2 will be described. In embodiment 1, FlexBr (Master) 1 performed bandwidth control for FlexBr (Slave) 2. However, if the delay time between FlexBr (Master) 1 and FlexBr (Slave) 2 is large, the time between FlexBr (Slave) 2 sending a Report frame and receiving a Gate frame becomes longer, and dynamic bandwidth control becomes rougher, resulting in excessive bandwidth being allocated or insufficient bandwidth, and reduced bandwidth control efficiency. Embodiment 2 differs from embodiment 1 in that another device connected to the optical path performs bandwidth control near FlexBr (Slave) 2. However, apart from this difference, embodiment 2 is the same as embodiment 1, and therefore the same components as embodiment 1 are denoted by the same reference numerals as embodiment 1 and detailed description thereof will be omitted.

[0078] 11 is an example of a network configuration diagram of a communication system 60 according to embodiment 2. In embodiment 2, in addition to the configuration of embodiment 1, an APN-G (APN-Gateway) 4 is connected to an APN 15, which is an optical path. The APN-G 4 includes a static information collection unit 410 and a bandwidth allocation unit 420.

[0079] In a communication system 60 according to the second embodiment, the main signal path remains the same as in the first embodiment, but the bandwidth control function is separated from FlexBr (Master) 1 to APN-G4. The difference from the first embodiment is that the bandwidth allocation unit 130 provided in FlexBr (Master) 1 is moved to APN-G4, and static information such as the round-trip delay time and the transmission rate of the CP transmitter 100_Tx of FlexBr (Master) 3 is shared between APN-G4 and FlexBr (Slave) 2, and between APN-G4 and FlexBr (Master) 3. Therefore, the FlexBr (Master) 3 according to the second embodiment includes a signal separation unit 310 and a static information collection unit 320.

[0080] Bandwidth control (transmission and reception of Gate / Report frames) and communication for static information sharing between APN-G4 and FlexBr (Slave) 2 are performed using control signals multiplexed onto the main signal on APN 15. For example, they are wavelength-multiplexed onto the main signal as separate wavelengths, or frequency-multiplexed onto the main signal using AMCC (Auxiliary Management and Control Channel) or the like. Control signals do not require high-speed bandwidth like APN-T ports, and low speeds are sufficient as long as the control signals can be transmitted.

[0081] Communication between APN-G4 and FlexBr (Master) 3 may be via control signals on APN 15, just like communication between APN-G4 and FlexBr (Slave) 2, but since there is no dynamic control and the distance is long, only static information such as delay information between FlexBr (Master) 3 and FlexBr (Slave) 2 and the transmission speed of CP transmitter 100_Tx of FlexBr (Master) 3 is shared, so information may be shared via a management N / W 21 different from APN 15.

[0082] The round trip delay time is measured not only as the master-slave round trip delay time in the main signal path between FlexBr (Master) 3 and FlexBr (Slave) 2, but also as the band-slave round trip delay time in the control signal path between APN-G 4 and FlexBr (Slave) 2. When APN-G allocates bandwidth in a Gate frame, it takes both delay times into account and calculates the GST so that congestion does not occur in the CP transmitter 100_Tx of FlexBr (Master) 3. The RTT used in bandwidth allocation calculations such as minimum bandwidth allocation is only the band-slave round trip delay time between APN-G 4 and FlexBr (Slave) 2. The master-slave round trip delay time may be measured in the same manner as in the first embodiment, but may also be measured by FlexBr (Master) 3 from the transmission time of a control signal from FlexBr (Slave) 2 via an administration N / W 21 different from APN 15 and the reception time of the control signal at FlexBr (Master) 3. The master-slave round trip delay time is measured, for example, from the transmission time of a control signal from APN-G4 and the reception time of the control signal at FlexBr (Slave) 2.

[0083] In embodiment 2, APN-G4 has a function of bandwidth control of the input buffer unit 211 of FlexBr (Slave) 2 based on the master-slave round trip delay time and the slave-slave round trip delay time contained in the static information shared with FlexBr (Master) 3 and FlexBr (Slave) 2, and information on the amount of data currently stored in the input buffer unit 211, but this is not limited to APN-G4, and any device other than APN-G4 that has the bandwidth control function may be used.

[0084] As explained above, in the second embodiment, the bandwidth control is performed by a device other than the FlexBr (Master) 3, so that the bandwidth control can be performed near the FlexBr (Slave) 2, and the round-trip delay time of the bandwidth control frame is reduced, thereby improving the efficiency of the bandwidth control.

[0085] In addition, the "main bridge device" in the claims corresponds to "FlexBr (Master) 1, 3" in the detailed description of the invention, the "sub bridge device" in the claims corresponds to "FlexBr (Slave) 2" in the detailed description of the invention, the "input buffer" in the claims corresponds to "input buffer unit 211" in the detailed description of the invention, and the "bandwidth control device" in the claims corresponds to "APN-G4" in the detailed description of the invention.

[0086] 1 FlexBr (Master), 2 FlexBr (Slave), 3 FlexBr (Master), 4 APN-G, 20 User terminal, 110 Signal separation unit, 120 Static information collection unit, 130 Dynamic bandwidth allocation unit, 210 Signal multiplexing unit, 211 Input buffer unit, 220 Static information collection unit, 230 Output control unit, 310 Signal separation unit, 320 Static information collection unit, 410 Static information collection unit, 420 Bandwidth allocation unit.

Claims

1. A communications system in which a network in which a main bridge device and a sub bridge device, each having a bridge function between a low-speed interface and a high-speed interface, are connected by an optical path, the sub bridge device notifies the main bridge device of information related to the sub bridge device, including information on the amount of data currently stored in an input buffer into which data is input from a user terminal, and the main bridge device controls the bandwidth of the input buffer in the sub bridge device so as to enable time-division multiplexed control output at the low-speed interface of the main bridge device, based on the round-trip delay time calculated from the time the information related to the sub bridge device was sent and the time the information related to the sub bridge device was received, and the information on the amount of data currently stored in the input buffer.

2. A communication system according to claim 1, wherein said main bridge device controls the bandwidth of said input buffer in said slave bridge device using a main signal and an in-channel control signal.

3. A communication system as described in claim 1, wherein the main bridge device performs a static minimum bandwidth allocation for the input buffer in the secondary bridge device based on the round-trip delay time, the bandwidth update period, and the maximum buffer capacity of the input buffer in the secondary bridge device, and performs dynamic bandwidth allocation for surplus bandwidth outside the minimum bandwidth allocation in accordance with the amount of data currently stored in the input buffer.

4. A communication system as described in claim 3, wherein the main bridge device notifies the slave bridge device of the excess when the total of the static minimum bandwidth allocations exceeds the transmission speed of the low-speed interface of the main bridge device.

5. A communication system according to any one of claims 1 to 4, wherein the slave bridge device determines whether the input buffer of its own device will be exceeded by the next bandwidth update period after transmitting the bandwidth allocated in the bandwidth control by the master bridge device, and if it determines that the buffer will be exceeded, performs shaping outside the allocated bandwidth and transmits data.

6. A communication system according to any one of claims 1 to 4, wherein the slave bridge device determines whether the input buffer of its own device will exceed the capacity by the next bandwidth update period after transmitting the bandwidth allocated in the bandwidth control by the master bridge device, and if it determines that the capacity will be exceeded, performs the bandwidth control on the network on the low-speed interface side.

7. In a network in which a main bridge device and a sub bridge device, each having a bridge function between a low-speed interface and a high-speed interface, are optically connected, a bandwidth control device that controls the bandwidth of the sub bridge device is optically connected to the network, the main bridge device notifies the sub bridge device and the bandwidth control device of a main-sub round trip delay time calculated from the transmission time of a control signal transmitted from the sub bridge device and the reception time of the control signal, and the sub bridge device notifies the main bridge device and the bandwidth control device of the main-sub bridge round trip delay time calculated from the transmission time of a control signal transmitted from the bandwidth control device and the reception time of the control signal, and information on the amount of data currently stored in an input buffer into which data is input from a user terminal, A communication system in which the bandwidth control device controls the bandwidth of the input buffer in the slave bridge device so as to enable time division multiplexed control output at the low-speed interface of the main bridge device based on information on the main-slave round-trip delay time, the slave-slave round-trip delay time, and the amount of data currently stored in the input buffer of the slave bridge device, which information is shared with the main bridge device and the slave bridge device.

8. A communications method in a network in which a main bridge device and a sub bridge device, each having a bridge function between a low-speed interface and a high-speed interface, are optically connected, comprising: a step in which the sub bridge device notifies the main bridge device of information related to the sub bridge device, including information on the amount of data currently stored in an input buffer into which data is input from a user terminal; and a step in which the main bridge device controls the bandwidth of the input buffer in the sub bridge device so as to enable time-division multiplexed control output at the low-speed interface of the main bridge device, based on the round-trip delay time calculated from the time the information related to the sub bridge device is sent and the time the information related to the sub bridge device is received, and the information on the amount of data currently stored in the input buffer.

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