JP2013046132A - Communication system and master station device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize bands in a metro ring network by enabling dynamic modification of communication band allocation for use for data transmission from a remote node to a master station device.SOLUTION: In a communication system according to the present invention including a ring network connecting a plurality of node devices and the master station device in a ring shape and a plurality of sub-station devices, on the basis of band requests from the plurality of sub-station devices, the master station device allocates a first communication band for use for communication from a sub-station device to a node device. On the basis of the band requests from the plurality of sub-station devices, the master station device includes a ring network band allocation unit for allocating a second band for use for communication between node devices constituting the ring network. Using the second communication band, each node device includes a data transfer unit for transferring data, transmitted from the plurality of sub-station devices using the first communication band, to the master station device.

Description

  The present invention relates to a communication system configured by one-to-many connection of a station-side device and a subscriber-side device.

  A PON (Passive Optical Network) which is one form of an optical communication system is a station side device (Optical Line Terminal, hereinafter referred to as OLT as appropriate) arranged in a central office and a subscriber side arranged in a plurality of subscriber homes. A device (Optical Network Unit, hereinafter abbreviated as ONU as appropriate) is connected in a one-to-many manner using a star coupler and optical fiber, and the upstream direction (direction from the subscriber to the central office) performs time division multiplex communication. Since the downstream direction has a function of performing continuous communication and filtering with the ONU identifier assigned to the frame on the ONU side, it is widespread as an economical communication system that accommodates a plurality of ONUs with one OLT (for example, Non-patent document 1).

  In recent years, standardization of 10 Gbps class-PON (10G-EPON) for the purpose of further increasing the communication capacity of the access network has been completed (for example, see Non-Patent Document 2). When 10G-EPON is applied, the communication speed in the PON section is 10 times that in the case of EPON. In this case, two merits can be considered. The first merit is that the communication carrier operates with the same number of subscribers per OLT as the number of subscribers of a 1 Gbps class PON, so the communication capacity per subscriber increases and the subscribers It is to be able to benefit from the increased capacity of the section. The second advantage is that the communication carrier accommodates more subscribers per OLT than the 1 Gbps class PON, thereby lowering the operation cost and allowing the subscriber to be equal to or more than the 1 Gbps class PON. Service (communication capacity).

  Generally, 1 Gbps class PON star couplers use up to 32 or 64 branches, and the number of branches beyond that is almost realized due to the small communication capacity and loss of the optical transmission line due to branching by the star coupler. Although not done, the number of ONUs accommodated by multi-branching has been studied conventionally (see, for example, Patent Document 1). In Patent Document 1, a plurality of PON signals with different wavelengths handled by a plurality of station-side devices installed in a central office are connected to a WDM coupler that multiplexes or demultiplexes each wavelength, and is multiplexed by a WDM coupler. A wavelength multiplexed signal is connected to a plurality of transponders capable of transmitting and receiving a PON signal having a wavelength corresponding to a specific station-side device using one optical fiber and a star coupler, and the transponder and the plurality of ONUs are connected to one optical fiber and A multi-branching method is disclosed in which a star-type coupler is connected and a PON signal is transmitted and received by time division multiplexing in the upstream direction.

  Also, when considering the effective use of a 10 Gbps class PON device, it is possible to increase the number of subscribers per OLT and reduce the operating cost of the communication carrier, rather than just considering the improvement of the communication speed per subscriber. It is desirable to have an operational form that improves satisfaction.

  Applying this type of operation and sharing the OLT with a larger number of subscribers results in lowering the OLT power consumption (total power consumption of all OLTs on the station side) and spreading it all over the world. This is in line with the trend toward lower power consumption.

  However, only with the provisions stipulated in the international standard of 10 Gbps class (Non-Patent Document 2 above), the transmission quality deteriorates due to multi-branching, so that the distance between the currently served central office and the subscriber's home is not reduced. It is difficult to realize branching. For example, it is possible to achieve both service distance and multi-branching by increasing the power of OLT and ONU transmitters or inserting an amplifier in the fiber, but the transmission power of OLT and ONU is high. Then, operation and technical problems occur, such as a higher hazard level for access fiber laying workers and difficulty in amplifying an upstream burst signal with an amplifier.

  Further, in the method disclosed in Patent Document 1, the configuration of the station-side device is not changed from the conventional configuration, and a transponder is newly inserted, so that multi-branching is possible, but low power consumption is achieved. The problem that is difficult. Further, as a problem common to the conventional system, when a service is provided to a larger number of subscribers with one OLT, the central office device and the subscriber device are connected by a single fiber. When a fiber (especially a trunk line) breaks down, the problem that a failure area expands arises.

  Therefore, in order to solve the above-mentioned problems, in a PON apparatus of 10 Gbps class or higher, a subscription that allows power saving and a redundant configuration while allowing an increase in the number of subscribers per OLT (multiple branching) is allowed. For the purpose of providing a person accommodation device, a method of consolidating more ONUs into one OLT than before is disclosed by the fusion of OTN technology and PON technology (for example, see Non-Patent Document 3).

  The OLT and the ONU are connected via a remote node (RN) and a metro ring network (Optical Transport Network, OTN) such as a ROADM network. The RN is an overhanging OLT node that converts upstream burst light from the ONU into continuous light, and the ROADM network is a network that multiplexes and transfers data between the RN and the OLT-IF. Since the upstream signal from the ONU is multiplexed by the optical splitter, GATE control is performed so that the upstream signal from each ONU does not collide after multiplexing. In this GATE control, the OLT serves as a command tower and notifies the transmission permission to each ONU, so that the upstream signal from each ONU is separated in time to avoid a collision (the OLT is upstream of each ONU). Specify bandwidth in time). In the RN, the burst optical signal received from each ONU is electrically converted, converted into a continuous optical signal, and transferred to a node in the metro ring network. In the node of the metro ring network, the signal of one or a plurality of RNs is mapped to the OTN frame, allocated to the wavelength (λ) in the metro ring network, and transferred to the aggregated OLT. In this way, burst light between ONU and OLT is converted into continuous light at a remote node (RN) and transferred to an OLT aggregated via a metro ring network such as ROADM, so that PON multi-branching / extension or It is intended to realize power saving.

JP 2008-206008 A

IEEE802.3 IEEE802.3av IEICE Technical Report CS2010-9 (2010-7)

  In Non-Patent Document 3 described above, the PON function is integrated into the OLT, and the PON signal is directly accommodated in the OTN signal and transmitted / received, thereby improving multi-branching, lengthening, network reliability improvement, and low power consumption. The way to achieve it is shown. However, when mapping one or a plurality of RN signals to an OTN frame, the bandwidth allocation must be fixed bandwidth allocation (dynamic bandwidth cannot be changed), and a bandwidth that considers the maximum traffic must always be secured. Therefore, there is a problem that the bandwidth in the metro ring network cannot be effectively used. That is, in the case where 10-GEPON is accommodated below the remote node, a bandwidth equivalent to 10 Gbps needs to be fixedly assigned to each remote node as OTN frame mapping. However, since the actual average upstream traffic is very small, the bandwidth is wasted.

  The present invention has been made to solve the above-described problems, and by effectively changing the mapping of the remote node to the OTN frame, it is possible to effectively use the bandwidth in the metro ring network. It aims to be.

  A communication system according to the present invention includes a ring network in which a plurality of node devices and a master station device are connected in a ring shape, and a plurality of slave station devices that transmit data to the master station device via the plurality of node devices. The master station device allocates a first communication band used for communication from the slave station device to the node device based on bandwidth requests from the plurality of slave station devices, and the slave station device assigns the first communication band. And a communication system for transmitting data to the node device, wherein the master station device uses the second request for communication between the node devices constituting the ring network based on bandwidth requests from the plurality of slave station devices. A ring network band allocating unit that allocates a band, and the node apparatus transfers data transmitted from a plurality of slave station apparatuses to the master station apparatus using the first communication band based on the second communication band Comprises that the data transfer unit.

  Further, the master station device according to the present invention includes a ring network in which a plurality of node devices and master station devices are connected in a ring shape, and a plurality of slave station devices that transmit data to the master station device via the plurality of node devices. The master station device allocates a first communication band used for communication from the slave station device to the node device based on bandwidth requests from a plurality of slave station devices, and the slave station device has a first A master station device applicable to a communication system that transmits data to a node device using a communication band, and for communication between node devices constituting a ring network based on bandwidth requests from a plurality of slave station devices A ring network band allocation unit that allocates a second communication band to be used is provided.

  According to the present invention, the bandwidth in the metro ring network can be effectively utilized by dynamically changing the communication bandwidth allocation used for data transmission from the remote node to the master station device.

It is a block diagram of the communication system shown in Embodiment 1 of this invention. It is a figure showing the example of the mapping of the OTN frame shown in Embodiment 1 of this invention. It is a block diagram of the communication system shown in Embodiment 2 of this invention. It is a sequence diagram showing the measuring method of RTT shown in Embodiment 2 of this invention. It is a sequence diagram showing the example of the band control shown in Embodiment 2 of this invention.

Embodiment 1 FIG.
A communication system to which the present invention is applied will be described with reference to the drawings, taking a PON system as an example. FIG. 1 shows a configuration example of a communication system according to Embodiment 1 of the present invention. In FIG. 1, this communication system includes a ring network (metro ring network) in which a plurality of node devices and a master station device are connected by duplexed optical fibers, and an optical fiber and an optical coupler (for example, 32). And a slave station device (hereinafter referred to as ONU (Optical Network Unit)) 5 connected via a branch coupler 4. The node device is assumed to be composed of ROADM 2 and RN 3 described later, and the master station device is assumed to be composed of ROADM and OLT 1. Note that ROADM 2 and RN 3 or OLT 1 may be configured as separate devices, or may be provided within the same device. Note that the same or similar devices are distinguished by adding “−” and a number after the number (for example, ROADM 2-1). When these devices are generically referred to or not distinguished from each other, they will be described using symbols without “-” (for example, ROADM2). Here, two node devices are provided on the ring network, but the number is not limited, and three or more node devices may be provided.

  A part of the devices constituting the ring network is a master station device that operates as a master station. In the communication system shown in FIG. 1, the master station apparatus is composed of OLT 1 and ROADM 2-0. The OLT 1 is a communication device that connects an upper network and a ring network, and accommodates a plurality of ONUs 5 via node devices and a metro ring network. The OLT 1 includes a TRx 11, an OTN Framer 12, a highly integrated PON-MAC 13, and a bandwidth calculation / reservation information generation unit 14. The TRx11 converts the optical signal transferred from the ROADM 2-0 into an electric signal in the upstream direction (ONU → OLT direction), and from the upper network in the downstream direction (OLT → ONU direction), NNI ( Data (electrical signal) received via the Network Network Interface and processed inside the OLT is converted into an optical signal and transferred to the ROADM 2-0. The OTN Framer 12 maps various electrical signals to an OTN (Optical-channel Transport Network) frame, and demaps the OTN frame to various electrical signals. The highly integrated PON-MAC 13 is configured so that the MAC function of the conventional PON is highly integrated, that is, is compatible with a large number of ONUs, and performs PON control conforming to the IEEE standard or the ITU-T standard.

  The ROADM 2 extracts (drops) a signal of a specific wavelength from the optical signal flowing on the ring network and transfers it to the OLT 1 or an RN described later. Further, the signal from the OLT 1 or RN3 is added (added) on the ring network (output to the ring network).

  The remote node (RN) 3 connected to the ROADM 2 converts the burst optical signal received from each ONU into an electrical signal, converts it into a continuous optical signal, and transfers it to the ROADM 2 of the metro ring network. The OLT 1 and the RN 3 are connected via the ROADM 2 and the ring network, and communicate by performing OTN frame transfer by continuous optical WDM at a transmission speed higher than the communication speed between the RN and the ONU under its control. On the other hand, each ONU 5 accommodated in each RN 3 is connected in a star topology using the optical coupler 4 as in the conventional PON, and communicates by the conventional TDMA-PON system.

  Next, the configuration of the remote node (RN) 3 will be described. Note that the RNs shown in FIG. 1 have the same configuration. The RN3 includes a TRx41, an OTN Framer 42, an ODU-XC43, a TS mapping 44, a PON Tx35, a Burst CDR36, a PON Rx37, and a WDM38. Similar to the OTN Framer 12 of the OLT 1, the OTN Framer 32 maps various electric signals to OTN frames used in a ring network (metro ring network), and demaps the OTN frames to various electric signals.

  The ODU-XC 33 is a function that realizes cross-connect switching in units of ODU frames in the OTN frame, and in this embodiment, realizes cross-connect switching in units of TS (Tributary Slot) defined by ODUflex (mapping to TS). . The PON Tx in the RN is an optical transmission function that performs electrical-to-optical conversion (same as the function in the conventional OLT), and the PON Rx in the RN is an optical reception function that performs optical-to-electrical conversion (the light is a burst) (in the conventional OLT) The Burst CDR 36 in the RN is a function for extracting a clock from a burst signal (equivalent to the function in the conventional OLT). The TS mapping 34 in the RN 3 has a function of mapping the electric signal received from the ONU 5 side to the TS and transferring the electric signal mapped to the TS from the ODU-XC 33 to the PON Tx 35.

  The ONU 5 is a subscriber-side terminal device in the PON system, and is connected to a terminal or the like (not shown in FIG. 1). The ONU 5 is composed of a plurality of groups of ONUs. Each group of ONUs is connected to a plurality of WDMs 38 provided in the RN 3 in a star topology, and TDMA control is performed for each group. .

Next, the operation will be described. Here, only the operation in the uplink direction will be described.
First, the OLT 1 performs a Discovery process standardized by the IEEE, ITU-T standard, etc., and registers the ONU 5. That is, a control signal is transmitted to each ONU via the ring node and the RN, and the ID and the like of each ONU are registered based on a response signal to the control signal from the ONU. At this time, the RTT (Round Trip Time) between the OLT 1 and each ONU is measured, and the RTT of the OLT 1 and each ONU 5 is also registered. Further, as will be described later, in order to perform bandwidth allocation in the metro ring network, an RTT between each ONU 5 and RN3 is required, but the RN3 measures the RTT between each ONU and RN at the time of Discovery processing. It is also possible to provide a function and transmit it to the OLT 1 by including it in an OTN frame or the like of the metro ring network, or to provide a function for measuring the RTT of each ONU 5 and RN 3 in the OLT 1.

  When the registration of the ONU 5 to the OLT 1 is completed, the OLT 1 transmits a transmission permission signal (MPCP Gate frame) to each ONU 5. The ONU 5 that has received the transmission permission signal checks its own buffer and the like, and transmits a bandwidth request corresponding to the amount of data desired to be transmitted to the OLT 1 based on the transmission permission signal received from the OLT 1. In the OLT 1, based on the bandwidth request received from each ONU 5, a communication band (first communication band) used by the ONU 5 for communication with the RN 3 and a communication band (first communication band used by the RN 3 for communication in the metro ring network) 2 communication band). In the PON upstream traffic (ONU → OLT traffic), the upstream signal from the ONU is multiplexed by the optical coupler, and therefore the GATE control is performed so that the upstream signal from each ONU does not collide after the multiplexing. Hereinafter, bandwidth allocation in the first communication band and the second communication band will be described in detail.

  First, the OLT 1 integrates the communication bandwidth required by each ONU 5 from the bandwidth request received from the ONU 5 connected to each RN 3. In addition, for each RN3, the communication bandwidth required by all ONUs 5 connected to the RN3 is also accumulated. The OLT 1 can recognize when and how much upstream traffic is generated from which RN 3 based on the accumulated communication band and the RTT between the RN and the ONU. Based on the accumulated communication band amount, a communication band to be used for communication in a ring network (metro ring network) is assigned to each RN 3. That is, TS (Tributary Slot) in the metro ring network is reserved for each RN. Specifically, it is possible to adopt a configuration in which band allocation is performed by wavelength division multiplexing, time division multiplexing, or a combination thereof. Here, TS is a transfer unit defined by ODUflex, and in the 100 Gbps metro ring network that is expected to spread in the future, 80 TS are prepared (1.25 Gbps per one), and this TS can be arbitrarily set. It is possible to transmit data by combining a number of these.

  Various communication band allocation methods are conceivable. For example, based on a method of performing allocation according to the integrated amount for each RN 3, communication quality predetermined for the ONU 5 accommodated in each RN 3, and the like. For example, a method of assigning communication bands by weighting can be considered.

  Next, in the OLT 1, based on the band allocation result (second communication band allocation result) in the metro ring network allocated to each RN 3, the communication band (first communication band) of the communication between the ONU and the RN is determined. Perform bandwidth allocation. That is, for each ONU, the data transmission start time and transmission time are calculated, and a transmission permission signal (GATE frame) including the calculated transmission start time and transmission time is notified to each ONU 5.

  In the OLT 1, a transmission permission signal (GATE frame) is transmitted to each ONU 5, and the overhead (reservation area, etc.) of the OTN frame transmitted on the ring network is used, and information on the band allocation for each RN 3 (second) The communication band allocation information) is also transferred.

  Each RN transfers the transmission permission signal (GATE frame) transferred from the OLT 1 to the corresponding ONU 5 and extracts the TS reservation status from the overhead of the OTN frame (reserved area or the like). The ONU 5 that has received the transmission permission signal transferred from the RN 3 transmits data such as its own buffer to the RN 3 based on the transmission start time and the transmission time included in the transmission permission signal. In RN3, based on the TS reservation status extracted from the overhead (reserved area or the like) of the OTN frame, the upstream traffic from the ONU side is TS mapped, switched by ODC-XC, and transferred to OLT1. FIG. 2 shows an example of OTN frame mapping. As shown in FIG. 2, TS is reserved in each RN 3 according to the amount of data from the ONU accommodated in each RN.

  Since the communication system according to Embodiment 1 of the present invention is configured as described above, it is possible to dynamically change the communication band in the metro ring network, and communication of ONUs connected to each RN. By changing the communication band in the metro ring network according to the bandwidth request, it becomes possible to effectively use the band in the metro ring.

Embodiment 2. FIG.
As shown in the first embodiment, it is necessary for the OLT to recognize the RTT between the RN and the ONU in order to perform appropriate second communication band allocation (TS reservation for each RN). It becomes. In the second embodiment, a mode in which the RTT between the RN and the ONU is simply measured in the OLT will be described.

  In the conventional PON, bandwidth control is performed between the OLT and the ONU on the assumption that the RTT does not change for each frame and has a fixed delay (the delay for each frame is fixed). However, in a PON system that intervenes a metro ring network, although there is a fixed delay between the RN and the ONU, in the first embodiment, frame mapping, cross-connect switching, etc. are performed in the metro ring network. , RTT between RN and OLT may be variable for each frame. Therefore, the RTT for each frame between the ONU and the OLT also becomes variable, and the contention control in the burst section (RN-ONU section) may not operate normally with the same bandwidth control as before.

  Further, the conventional method of obtaining the RTT is a method of obtaining the RTT between the OLT and the ONU, and does not obtain the RTT between the RN and the ONU described in the first embodiment. Therefore, in the second embodiment, the variable delay information in the metro ring network is calculated, and when the MPCP frame is transmitted in the RN-ONU section, the above information is taken into account, so that in the OLT, the RTT between the RN and the ONU. It aims at deriving easily.

  FIG. 3 shows the configuration of the communication system according to the second embodiment. The same reference numerals as those in the configuration of the communication system shown in the first embodiment (FIG. 1) are the same or corresponding parts, and the description is omitted. In FIG. 3, the time synchronization 15 in the OLT 1 and the time synchronization 39 in the RN 3 are circuits that realize time synchronization in the metro ring network, and the implementation method is not particularly defined, but the OTN overhead and the OSC optical are not specified. For example, there are a method that can be realized by an IEEE 1588-like procedure using a method such as GPS, and a method that is realized by using GPS or the like. The operations other than the RTT measurement between the RN 3 and the ONU 5 are the same as those in the first embodiment, and only the RTT measurement operation between the RN and the ONU will be described here.

  FIG. 4 shows how to obtain RTT in the communication system according to Embodiment 2 of the present invention. FIG. 5 shows GATE control in the communication system according to Embodiment 2 of the present invention. The method for obtaining the RTT between RN and ONU will be described with reference to FIG. Note that the frame exchange and basic operation have the same configuration as that of the conventional PON in consideration of circuit simplification.

The RTT is measured in the above-described Discovery process, and can be measured by performing the following procedures (1) to (7).
(1) The OLT 1 transmits a Discovery-Gate to which information on the metro time at transmission is added in addition to the local time T1 to each ONU 5. (2) The local time value of the Discovery-Gate is set to T1 + in the RN3. (B-a) and transmitted to ONU 5 (metro time b is the metro time when the Discovery-Gate is received by the RN, and ba is a delay in the Metro-ring network of the corresponding Discovery-Gate frame. (It will be time)
(3) Set T1 + (b−a) in the ONU local timer (4) Transmit Register-Request (ONU transmission time = T2) at T2 after T _wait (5) Register-Request (ONU transmission) at RN At time = T2), the metro time c when the Register-Request is received is added as additional information and sent to the OLT. (6) The ONU is based on the metro time d when the Register-Request is received at the OLT. The transmission time is corrected to T2 + (dc) (dc is the delay time in the metro ring network of the corresponding Register-Request frame)
(7) RTT between RN and ONU can be calculated by the following formula
_{RTT = T DOWNSTREAM + T UPSTREAM =} T RESPONSE -T WAIT - (ba) - (dc)
= (T3-T1)-[T2- {T1 + (ba)}]-(ba)-(dc)
= T3-T2- (dc)
= T3- {T2 + (dc)}

  FIG. 5 shows an example of bandwidth control. In FIG. 2, the OLT 1 transmits a local time, GST (Grant Start Time), and GL (Grant Length) to the ONU. Here, the local time for transmission from the OLT is Tx, and GST = Ty-RTT (time Ty that is desired to arrive at the RN, time before RTT) and GL = L1 are included in the transmission permission signal (Gate). The RN performs time synchronization in the metro network in advance, calculates a delay (variable delay for each frame) ba in the metro ring network, and sets the local time and GST of the transmission permission signal received from the OLT to Tx + Update (ba), Ty-RTT + (ba), and transfer to ONU.

  The ONU 5 sets the local time included in the received transmission permission signal to itself, and starts data transmission for the time indicated in the GL from the time indicated in the GST. Thereby, contention control in the burst section (RN-ONU section) can be performed normally.

  Since the communication system according to the second embodiment is configured as described above, the RTT between the RN and the ONU in the OLT can be easily performed using only parameter information recognized by the OLT while following the conventional PON control as much as possible. It is possible to calculate.

1 master station device (OLT), 2-0 to 2 ROADM, 3-1, 2 remote node (RN), 4-11 to 1n, 4-21 to 2n optical coupler, 5-111 to 1 nm, 5-2111 2 nm Slave station (ONU), 11 TRx, 12 OTN Framer, 13 Highly integrated PON-MAC, 14 Bandwidth calculation / reservation information generation unit, 15 Time synchronization unit, 31-1, 2 TRx, 32-1, OTN Framer 33-1, 2 ODU-XC, 34-1, 2 TS mapping, 35-11 to 1n, 21 to 2n PON Tx, 36-11 to 1n, 21 to 2n Burst CDR, 37-11 to 1n, 21 to 2n PON Rx, 38-1, 2 WDM, 39-1, 2 Time synchronization

Claims (7)

A ring network in which a plurality of node devices and a master station device are connected in a ring; and a plurality of slave station devices that transmit data to the master station device via the plurality of node devices, the master station device Assigns a first communication band used for communication from the slave station apparatus to the node apparatus based on a bandwidth request from the plurality of slave station apparatuses, and the slave station apparatus allocates the first communication band. A communication system for transmitting data to the node device,
The master station device includes a ring network bandwidth allocating unit that assigns a second communication bandwidth to be used for communication between node devices constituting the ring network based on bandwidth requests from the plurality of slave station devices,
The node device, based on a second communication band allocated by the ring network band allocating unit, transmits data transmitted from the plurality of slave station devices using the first communication band to the master station device. A data transfer unit for transferring to
A communication system characterized by the above. The master station device further includes an RTT measurement unit that measures an RTT (Round Trip Time) between the slave station device and the node device,
The ring network band allocation unit allocates the second communication band based on a band request from the plurality of slave station devices and an RTT measured by the RTT measurement unit;
The communication system according to claim 1. The master station device includes time synchronization means for performing time synchronization with the plurality of node devices,
The RTT measurement unit calculates an RTT between the node device and a slave station device connected to the node device based on a time synchronized by the time synchronization unit;
The communication system according to claim 2. The ring network band allocating unit performs allocation by associating the first communication band and the second communication band;
The communication system according to any one of claims 1 to 3. The node device converts a burst optical signal from a reconfigurable optical add / drop multiplexer (ROADM) that extracts and adds signals to the ring network and a slave station device connected to the device into a continuous optical signal, A remote node that performs OTN frame mapping to use the converted optical signal in the ring network;
The communication system according to any one of claims 1 to 4. The ring network is a wavelength multiplexing network that performs communication by multiplexing a plurality of different wavelengths,
The ring network band allocation unit allocates a wavelength to be used to the remote node;
The communication system according to any one of claims 1 to 5. A ring network in which a plurality of node devices and a master station device are connected in a ring; and a plurality of slave station devices that transmit data to the master station device via the plurality of node devices, the master station device Assigns a first communication band used for communication from the slave station apparatus to the node apparatus based on a bandwidth request from the plurality of slave station apparatuses, and the slave station apparatus allocates the first communication band. A master station device applicable to a communication system for transmitting data to the node device,
A ring network band allocating unit that allocates a second communication band to be used for communication between node apparatuses constituting the ring network based on band requests from the plurality of slave station apparatuses;
A master station device.

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