WO2015022807A1

WO2015022807A1 - Master station device, control device, communication system, and communication method

Info

Publication number: WO2015022807A1
Application number: PCT/JP2014/065594
Authority: WO
Inventors: 向井　宏明; 隆志西谷
Original assignee: 三菱電機株式会社
Priority date: 2013-08-12
Filing date: 2014-06-12
Publication date: 2015-02-19
Also published as: JP2016181734A

Abstract

The present invention solves the problem of providing a master station device capable of reducing the time required for resuming normal data transmission/reception after the occurrence of a change in wavelength. The present invention is a master station device (OLT1) that accommodates one or more slave station devices (ONU101, 102, …, 109) and allocates one wavelength selected from among multiple candidates to each slave station device in order to communicate with the slave station devices. When a slave station device that requires a change in the used wavelength , the master station device instructs the slave station device to change the wavelength and causes the slave station device to notify terminal devices under the slave station device of the address of the slave station device.

Description

Parent station apparatus, control apparatus, communication system, and communication method

The present invention relates to a master station device, a control device, a communication system, and a communication method that accommodate one or more slave station devices.

The PON system (Passive Optical Network), which is one of the communication systems, accommodates one or more ONUs (Optical Network Units) as slave station devices in the OLT (Optical Line Terminal) as the master station device. One or more terminal devices (hereinafter referred to as terminals) can be connected.

In the PON system, the OLT assigns LLIDs (Logical Link IDs) to the subordinate ONUs to manage each ONU, and manages the terminals connected to each ONU by MAC address. That is, the OLT holds a correspondence table (MAC address table) between the LLID of each ONU and the MAC address of each terminal. When an upstream frame from the terminal is received via the ONU, the source address ( SA: Source Address) is registered in the MAC address table in association with the LLID of the ONU (ONU that relays the upstream frame). When the OLT receives the downstream frame from the upper network, the OLT refers to the MAC address table, assigns the LLID associated with the destination address (DA: Destination Address) to the downstream frame, and broadcasts it to all ONUs. . When each ONU receives a downlink frame assigned with its own LLID, it forwards it to the subordinate terminal, and when it receives a downlink frame assigned with an LLID different from that assigned to itself. Discard without forwarding. Further, the OLT determines a time during which transmission to each ONU is permitted so that the upstream frame from each ONU does not collide, and each ONU transmits an upstream frame at the permitted time. Such a PON system is called a TDM (Time Division Multiplexing) system.

In addition, the conventional TDM PON system communicates using a single wavelength, but TWDM (Time and Wavelength Division Multiplexed) uses multiple wavelengths by wavelength multiplexing the conventional PON system. -A PON system has been proposed (see Patent Document 1 and Non-Patent Document 1). In this TWDM-PON system, the wavelength accommodating the ONU is changed according to the traffic situation. For example, the OLT first starts communication with a predetermined ONU using the wavelength of λ11. After that, when the traffic passing through λ11 increases and the transmission capacity becomes insufficient, communication with this ONU is performed. Change the wavelength to be used to λ12. Since the TWDM-PON system uses a plurality of wavelengths, the LLID of each ONU, the wavelength used for communication with each ONU, and the MAC address of each terminal are registered in the MAC address table managed by the OLT. As the TWDM-PON system, there can be considered a mode in which the OLT and the ONU use the same wavelength in the upstream and downstream in time division and a mode in which different wavelengths are used in the upstream and downstream.

JP 2011-228800 A

When the wavelength change occurs, the correspondence relationship between the LLID, the wavelength, and the MAC address registered in the MAC address table does not match the actual correspondence relationship, but the MAC address table is updated in response to reception of the upstream frame ( When an upstream frame is received, the MAC address is relearned). Therefore, the learning result before the wavelength change remains in the MAC address table until the upstream frame is received from the ONU whose wavelength has been changed after the wavelength change has occurred. I will send it. That is, there is a problem in that the downlink frame cannot be correctly transmitted until the uplink frame is transmitted.

The present invention has been made in view of the above, and a master station device, a control device, a communication system, and a communication capable of shortening a time required until data transmission / reception can be normally performed after a wavelength change occurs The purpose is to obtain a method.

In order to solve the above-described problems and achieve the object, the master station device according to the present invention accommodates one or more slave station devices, and selects one wavelength selected from a plurality of candidates for each slave station device. When a slave station device that is assigned and communicates and detects a slave station device that needs to change the wavelength to be used, the slave station device is instructed to change the wavelength, and the terminal device under the slave station device is assigned its own address. A wavelength management unit for notification is provided.

The control device according to the present invention is a control device in a master station device that accommodates one or more slave station devices, and assigns each wavelength selected from a plurality of candidates to each slave station device for communication. When a slave station device that needs to change the wavelength to be used is detected, the slave station device is instructed to change the wavelength, and the terminal device under the slave station device is notified of its own address.

The communication system according to the present invention is a communication system in which a master station device accommodates one or more slave station devices, and one wavelength selected from a plurality of candidates is assigned to each slave station device for communication. The master station device, when detecting a slave station device that needs to change the wavelength to be used, instructs the slave station device to change the wavelength, and causes the terminal device under the slave station device to notify its own address. And

The communication method according to the present invention is a communication method in a communication system in which a master station device accommodates one or more slave station devices, and one wavelength selected from a plurality of candidates is assigned to each slave station device for communication. A determining step in which the master station device determines the necessity of changing the wavelength used by each slave station device; and a wavelength for the slave station device that the master station device has determined that the wavelength needs to be changed. An instruction step for instructing a change, and a request step in which the master station device requests notification of its own address to a terminal device under the slave station device that has instructed the wavelength change.

According to the master station device, the control device, the communication system, and the communication method according to the present invention, it is possible to reduce the service interruption time in which data cannot be transmitted / received after the wavelength change occurs.

FIG. 1 is a diagram showing a configuration example of a communication system according to the present invention. FIG. 2 is a diagram illustrating an example of the MAC address table. FIG. 3 is a diagram illustrating a hardware configuration example of the OLT. FIG. 4 is a diagram illustrating an example of the wavelength switching operation. FIG. 5 is a diagram illustrating an example of the updated MAC address table. FIG. 6 is a flowchart illustrating an example of a control operation related to wavelength switching.

Hereinafter, embodiments of a master station apparatus, a control apparatus, a communication system, and a communication method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a communication system according to the present invention. In this embodiment, for the sake of simplicity, a TWDM-PON system using two waves will be described as an example, but the present invention can also be applied to a system using three or more waves. In addition, although the description will be made assuming that the same wavelength is used for uplink and downlink communication, the present invention can also be applied to a system using different wavelengths for uplink and downlink.

As shown in FIG. 1, the TWDM-PON system is connected to an OLT 1 via an optical fiber 100 and a station side device (also referred to as “Optical Line Terminal”, hereinafter referred to as “OLT”) that operates as a master station device. .., 109,..., And a user side device (also referred to as “Optical Network Unit”, hereinafter referred to as “ONU”) 101, 102,. The ONU 101 is assigned LLID # 1. Similarly, LLID # 2 and LLID # 9 are assigned to the ONU 102 and ONU 109, respectively. One or more terminal devices (hereinafter referred to as terminals) can be connected to each ONU. In this embodiment, the MAC addresses of the terminals connected to the ONU 101 are MAC-ADDR # 1-1 to MAC-ADDR # 1-l, and the MAC addresses of the terminals connected to the ONU 102 are MAC-ADDR # 2. -1 to MAC-ADDR # 2-m, and the MAC addresses of the terminals connected to the ONU 109 are MAC-ADDR # 9-1 to MAC-ADDR # 9-n.

The OLT 1 distributes a downlink frame received from a higher-order network that omits the description to a wavelength management unit 2 that determines and changes a wavelength to be used for communication with each ONU, and distributes each of the ONUs to one of a plurality of wavelengths. A frame distribution unit 3 for transferring the received upstream frame to the upper network, and

PON termination units

10 and 20 for terminating the PON control performed between the ONUs are provided. The

PON terminators

10 and 20 serving as frame transmission / reception means (frame transmission / reception units) communicate with the subordinate ONUs using different wavelengths. In the example of FIG. 1, the PON terminator 10 communicates with

subordinate ONUs

101, 102,... Using the wavelength λ # 1, and the PON terminator 20 communicates with subordinate ONUs 109,. To do. As described above, in the communication system shown in FIG. 1, the PON terminator 10 and the PON terminator 20 use different wavelengths λ # 1 and λ # 2, so that two PON systems logically have the same optical fiber. Coexist in the network (optical fiber 100).

The frame distribution unit 3 holds a MAC address table (information storage unit) 4. In this MAC address table 4, information on the distribution destination of the downstream frame received from the upper network is registered (see FIG. 2). ). FIG. 2 is a diagram illustrating an example of information registered in the MAC address table 4. In the MAC address table 4 shown in FIG. 2, the transmission destination terminals of frames destined for MAC-ADDR # 1-1 to MAC-ADDR # 1-l are connected to the ONU of LLID # 1, and the LLID # 1 The ONU is information indicating that it is accommodated in the PON terminator 10 (PON # 1), and the transmission destination terminal of the frame addressed to MAC-ADDR # 2-1 to MAC-ADDR # 2-m is LLID # 2. Information indicating that the ONU connected to the ONU and the LLID # 2 is accommodated in the PON terminator 10 (PON # 1) is a frame addressed to MAC-ADDR # 9-1 to MAC-ADDR # 9-n Information indicating that the ONU of LLID # 9 is accommodated in the PON terminator 20 (PON # 2) is registered. Therefore, for example, when receiving a downstream frame whose destination address (DA: Destination Address) is MAC-ADDR # 1-1, the frame distribution unit 3 refers to the MAC address table 4 and associates the LLID associated with this destination address. Is assigned to the downstream frame and output to the distribution destination (PON termination unit 10 or 20) associated with MAC-ADDR # 1-1. The configuration of the MAC address table 4 shown in the figure is merely an example, and any configuration can be used as long as the ONU in which the terminal of each MAC address is accommodated and the wavelength used by each ONU are known. Absent. Moreover, it may not be a table format.

Each ONU has a configuration in which the wavelength used for communication with the OLT 1 can be changed, and performs communication using the wavelength specified by the OLT 1. That is, FIG. 1 shows an example in which the

ONUs

101 and 102 use the wavelength λ # 1 and the ONU 109 uses the wavelength λ # 2. However, all ONUs including the

ONUs

101, 102, and 109 have the wavelength λ # 1. Communication with OLT 1 is performed using one of λ # 2 designated by OLT 1.

FIG. 3 is a diagram illustrating a hardware configuration example of the OLT 1. As shown in the figure, the OLT 1 transmits a PON control unit (control device) 201 that performs processing on the OLT side based on the PON protocol, a reception buffer 202 for storing uplink data received from each ONU, and a transmission to the ONU. Between a transmission buffer 203 for storing downlink data to be transmitted, an optical transceiver 204 that performs optical signal transmission / reception processing, a WDM coupler (WDM) 205 that wavelength-multiplexes a plurality of optical signals having different wavelengths, and a network. A physical layer processing unit (PHY) 206 that realizes a physical interface function of an NNI (Network Node Interface). The optical transceiver can transmit and receive a plurality of optical signals having different wavelengths. Note that the PON control unit 201 performs band allocation for giving transmission permission so that transmission time zones do not overlap each ONU for each group of ONUs having the same wavelength to be used, as in the conventional PON system. The transmission data from the ONU is prevented from colliding. The PON control unit 201 includes the wavelength management unit 2, the frame distribution unit 3, the PON termination unit 10, and the PON termination unit 20 illustrated in FIG. 1 and has functions of these components.

Hereinafter, a characteristic operation in the communication system according to the present embodiment, specifically, a control operation when the OLT 1 and each ONU switch the wavelength used for communication will be described with reference to FIGS. 4 and 6. FIG. FIG. 4 is a diagram illustrating an example of a wavelength switching operation, and FIG. 6 is a flowchart illustrating an example of a control operation related to wavelength switching. It is assumed that the OLT 1 and each ONU are communicating in the state shown in FIG. 1, and the operation when wavelength switching is performed from this state will be described.

In the OLT 1 communicating with the

ONUs

101 and 102 using the wavelength λ # 1 and communicating with the ONU 109 using the wavelength λ # 2, the wavelength management unit 2 transmits traffic passing through the

PON termination units

10 and 20. Monitoring. As a result of monitoring, for example, when the traffic passing through the PON termination unit 10 approaches the limit of the transmission capacity, the connection destinations of some of the ONUs connected to the PON termination unit 10 are changed (that is, used) It is determined that the wavelength to be changed is necessary. In this case, for example, it is determined to change the connection destination of the ONU 101 to the PON termination unit 20. Then, the wavelength management unit 2 instructs the ONU 101 via the PON termination unit 10 to switch the wavelength to be used to λ # 2. Upon receiving this instruction, the ONU 101 changes the wavelength to be used to λ # 2 ((1) in FIG. 4, step S1 in FIG. 6). There are no specific rules for the wavelength switching instruction method. The instruction may be given by any method. For example, control information instructing wavelength switching is inserted into a downlink data frame to be received by the ONU 101 and transmitted.

When the wavelength switching unit 2 completes the wavelength switching instruction to the ONU 101, the wavelength management unit 2 obtains the MAC address of each terminal connected to the ONU 101 from the PON terminating unit 20 that performs communication using the wavelength λ # 2 after switching. For sending an address resolution control frame (ARP: Address Resolution Protocol request). Upon receiving the instruction, the PON terminator 20 transmits an ARP request. This ARP request is received by all the ONUs (here, the ONUs 101 and 109) using the wavelength λ # 2, and further forwarded to the terminal. Then, it reaches each terminal connected to the ONUs 101 and 109 ((2) in FIG. 4, step S2 in FIG. 6).

Each terminal that receives the ARP request (terminals whose MAC addresses are MAC-ADDR # 1-1 to # 1-1, # 9-1 to # 9-n) returns an ARP response including its own MAC address. Each ARP response is received by the PON termination unit 20 of the OLT 1 as an upstream frame from the

ONU

101 or 109 and passed to the frame distribution unit 3 ((3) in FIG. 4).

When receiving the ARP response, the frame distribution unit 3 updates the held MAC address table 4 based on the MAC address notified by the ARP response ((4) in FIG. 4, step S3 in FIG. 6). When receiving an ARP response from each terminal under the ONU 101 where wavelength switching has occurred, the frame distribution unit 3 updates the MAC address table 4, and MAC-ADDR # 1-1 to MAC-ADDR # 1-1 are set as destination addresses. The set distribution destination of the frame is set to the PON termination unit 20 (see FIG. 5). FIG. 5 is a diagram illustrating an example of the updated MAC address table. When an ARP response is received from each terminal under the ONU 109, the MAC address table 4 is not updated.

When the update of the MAC address table 4 is completed, downstream frames addressed to MAC-ADDR # 1-1 to MAC-ADDR # 1-l are assigned LLID # 1 in the frame distribution unit 3 and then distributed to the PON termination unit 20 And transmitted from the PON terminator 20 at the wavelength λ # 2. The downlink frame assigned LLID # 1 is received by the

ONUs

101 and 109 using the wavelength λ # 2, and the ONU 101 assigned LLID # 1 transfers the received downlink frame to the destination terminal. The ONU 109 to which LLID # 1 is not assigned discards the received downlink frame.

As described above, in the communication system according to the present embodiment, the OLT 1 monitors whether or not the wavelength used for communication with each ONU needs to be changed, and if the change is necessary, instructs the wavelength change. A control frame for address resolution is broadcast using the wavelength after the change, and notification of the MAC address is instructed to each terminal under the ONU. Also, the MAC address table is updated based on the notified MAC address. Thereby, after wavelength switching, the information registered in the MAC address table, that is, the association between the MAC address of the terminal and the output destination of the downlink frame is immediately updated, and the service interruption time can be reduced. Usually, an ARP request is periodically made from a server in the upper network, and the transmission interval of the ARP request is in minutes. For this reason, in the conventional method, after a wavelength change occurs, it takes a certain time until an upstream frame is received from the ONU, and the MAC address table cannot be updated. However, according to the present embodiment, as described above, after the wavelength change occurs, the OLT 1 broadcasts an ARP request to instruct each terminal under the ONU to notify the MAC address, and based on the received uplink frame, the MAC address Since the contents of the table are updated quickly, the service interruption time can be reduced to seconds or milliseconds.

As described above, the master station device according to the present invention is useful for a communication system capable of changing the wavelength of light used for communication with a slave station device.

1 station side device (OLT), 2 wavelength management unit, 3 frame distribution unit, 4 MAC address table, 10, 20 PON termination unit, 100 optical fiber, 101, 102, 109 user side device (ONU), 201 PON control Part, 202 reception buffer, 203 transmission buffer, 204 optical transceiver, 205 WDM coupler (WDM), 206 physical layer processing part (PHY).

Claims

A master station apparatus that accommodates one or more slave station apparatuses and allocates one wavelength selected from a plurality of candidates to each slave station apparatus for communication.
When detecting a slave station device that needs to change a wavelength to be used, the slave station device is provided with a wavelength management unit that instructs the slave station device to change the wavelength and that notifies a terminal device under the slave station device of its own address. Master station device.
A plurality of frame transmission / reception units that transmit / receive a frame to / from the slave station device under its control using a wavelength assigned to itself,
When the wavelength assigned to the slave station device is changed, the wavelength management unit is connected to the slave station device via the frame transmitter / receiver that uses the changed wavelength among the plurality of frame transmitter / receivers. 2. The master station device according to claim 1, wherein the terminal device is notified of the own address.
An information storage unit storing information about the wavelength used by the slave station device and the slave station device in which the terminal device of the transmission destination is accommodated;
A frame distribution unit that distributes a downlink frame received from an upper network to the frame transmission / reception unit based on information in the information storage unit;
When the information in the information storage unit is updated based on the information of the own address notified from the terminal device subordinate to the slave station device, the frame distribution unit, based on the updated information, The master station apparatus according to claim 2, wherein the master station apparatus is assigned to the frame transmitting / receiving unit that uses the wavelength after the change.
4. The master station device according to claim 1, wherein the master station device operates as an OLT of a TWDM-PON system.
5. The wavelength management unit according to claim 1, wherein the terminal device under the slave station device whose wavelength to be used is changed is notified of the own address using an ARP request. The master station device described in 1.
A control device in a master station device that accommodates one or more slave station devices and communicates by assigning one wavelength selected from a plurality of candidates to each slave station device,
When a slave station device that requires a change in wavelength to be used is detected, the slave station device is instructed to change the wavelength, and a terminal device under the slave station device is notified of its own address.
A communication system in which a master station device accommodates one or more slave station devices and performs communication by assigning one wavelength selected from a plurality of candidates to each slave station device,
When the master station device detects a slave station device that needs to change the wavelength to be used, the master station device instructs the slave station device to change the wavelength, and causes a terminal device under the slave station device to notify its own address. Communication system.
A communication method in a communication system in which a master station apparatus accommodates one or more slave station apparatuses and assigns and communicates one wavelength selected from a plurality of candidates to each slave station apparatus,
A determination step in which the master station device determines the necessity of changing the wavelength used by each slave station device;
An instruction step in which the master station device instructs the slave station device to change the wavelength;
A request step in which the master station device requests notification of its own address to a terminal device under the slave station device instructed to change the wavelength;
A communication method comprising: