JP6533449B2 - Optical transmission system, optical transmission method, controlled node, and optical transmission program - Google Patents

Description

  The present invention relates to an optical transmission system, an optical transmission method, a controlled node, and an optical transmission program technology.

  Conventionally, as a network using optical TDM technology, for example, PON (Passive Optical Network) has been studied or introduced as a means of configuring a broadband access network. The PON is an optical network in which one optical fiber can be shared by a plurality of subscribers, in which a branching device (optical coupler) is inserted in the middle of the optical fiber network.

  In PON in a broadband access network, an OLT (Optical Line Terminal) disposed in a central office and an ONU (Optical Network Unit) disposed in a user's home are connected via an optical fiber and an optical coupler. Usually, a plurality of ONUs are connected to one OLT, and time division multiplexing (TDM) or time division multiple access (TDMA) is applied between the OLT and the ONU to demultiplex data in the optical domain. By transmitting data while performing the above, resources such as the optical fiber core and the OLT can be shared by multiple users. The OLT is an optical line terminal at the central office side, and the ONU is a subscriber unit as an optical line terminal at the user home.

  A tree configuration is often adopted as a physical topology of PON, but a ring topology is also considered. In this ring topology, unlike a tree, two physically independent paths (inner and outer) can be set as PON. Therefore, even if a failure occurs in one of the paths, data in the other path is not blocked, which is suitable for high reliability.

Note that, as described in Non-Patent Document 1, in the redundant configuration in which two transmission paths directed to the same destination are prepared in advance, the same data is transmitted to the two transmission paths even before a failure occurs. Is called “1 + 1 protection” (described later with reference to FIG. 9).
On the other hand, as described in Non-Patent Document 2, a method of flowing data through one transmission path before a failure occurs, switching to another transmission path after the failure occurs, and flowing spare data Is called “1: 1 protection” (explained later in FIG. 10).

  FIG. 9 shows a light concentration network system 10P with 1 + 1 protection. In this optical concentration network system 10P, two paths between the OLT 21 and the ONU 32 in the PON of the ring topology are made redundant (fault-tolerant).

The optical concentration network system 10P is a first optical fiber as two signal transmission paths in which the optical transmission device 11P (representative node 11P) and the optical transmission devices 12P-14P (nodes 12P-14P) are physically independent. It is connected in a ring shape by the 16 and the second optical fiber 17.
The transmission path of the two ring-shaped optical fibers (the first optical fiber 16 and the second optical fiber 17) can transmit data in the clockwise direction and the counterclockwise direction which are different from each other as indicated by the arrows. When a failure occurs in the above transmission line and transmission becomes impossible, transmission is possible on the other transmission line.

For example, it is assumed that the client signal transmitted from the host 43a connected to the IO (Input / Output) unit 34a of the node 13P is transmitted to the host 41a connected to the IO unit 20a of the representative node 11P.
The IO unit 34a copies the same data to transmit data in the clockwise direction indicated by the arrow Y1 through the first optical fiber 16 and the counterclockwise direction indicated by the arrow Y2 through the second optical fiber 17. Do. When the IO unit 20a receives the same data from the clockwise direction and the counterclockwise direction, the IO unit 20a transfers them to the host computer 41a as one data (for example, discards one of the data).

Arrows Y1 and Y2 are both data flows from the node 13P (ONU 32a, 32b) to the representative node 11P (OSU (Optical Subscriber Unit) 26a, 26b), and this flow direction is hereinafter referred to as "up". . On the other hand, the flow direction of data from the representative node 11P to the node 13P is "down".
That is, in the same upward direction, data transmission can be performed clockwise and counterclockwise using two ring-shaped routes. Therefore, when a failure occurs in one of the paths and transmission becomes impossible, data transmission can be performed through the other path. For example, when a failure occurs in the first optical fiber 16 and transmission becomes impossible, data transmission can be performed by the second optical fiber 17. Therefore, even when a failure occurs in one of the paths, blocking of data transmission can be suppressed.
Although not shown in the figure, in the downward direction as well, since data transmission is possible clockwise and counterclockwise using two ring-shaped routes, a fault occurs in either one of the routes. Even when it occurs, interruption of data transmission can be suppressed.

  Hereinafter, details of each component in FIG. 9 will be described. The representative node 11P is configured to include a plurality of IO (input / output processing) units 20a to 20n, an OLT 21, and optical demultiplexing units 23a and 23b such as optical couplers. The OLT 21 includes an SW (switch) unit 25, OSUs 26a and 26b, and a Dynamic Wavelength and Bandwidth Assignment (DWBA) function unit 27.

  Each of the nodes 12P to 14P has the same configuration, and as represented by the node 13P, the optical demultiplexing units 31a and 31b, the ONUs (Optical Network Units) 32a and 32b, the SW unit 33, and a plurality of It comprises IO units 34a to 34n.

  In representative node 11P, a plurality of IO units 20a to 20n are connected to a plurality of host computers (also referred to as hosts) 41a to 41n outside representative node 11P on a one-to-one basis, and perform signal transmission / reception with hosts 41a to 41n. -LT (application server-network interface-line terminal). Also in the node 13P, a plurality of hosts 43a to 43n outside the node 13P are connected on a one-to-one basis to the same plurality of IO units 34a to 34n as described above. Similarly, in the other nodes 12P and 14P, hosts 42a to 42n and 44a to 44n (only one is shown) are connected in a one-to-one correspondence with IO units (not shown).

  The IO units 20a to 20n of the representative node 11P terminate the client signals transmitted from the hosts 41a to 41n and transmit them to the SW unit 25, and the signals from the SW unit 25 are used as client signals to the hosts 41a to 41n. Send to

  The SW unit 25 is a normal electrical packet switch, and is a switch equivalent to L2-SW (layer 2 switch). The SW unit 25 transmits packet data from the OSU 26 a to the host (for example, 41 a) of the destination by the MAC address according to the correspondence table between the MAC address (Media Access Control address) and the port set in advance. It transfers via the part 20a.

  The OSUs 26a and 26b are optical line terminal devices of the PDS (Passive Double Star) system. The OSUs 26a and 26b receive the optical burst data from the ONUs 32a and 32b of the nodes 12P to 14P and output them to the SW unit 25, and receive the packet data from the SW unit 25 and transmit the optical data to the ONUs 32a and 32b. . In this configuration, the PON section is between the OSUs 26a and 26b and the ONUs 32a and 32b.

  The DWBA function unit 27 has a function of dynamic wavelength band allocation. With dynamic wavelength band allocation, in order to efficiently distribute the total bandwidth of multiple wavelengths integrated to ONUs 32a and 32b of nodes 12P to 14P, dynamic wavelength switching is also taken into consideration, according to the traffic volume. It is to allocate a band.

  The optical demultiplexing units 23 a and 23 b perform any processing of multiplexing, demultiplexing, and through on data as an optical signal transmitted through the first optical fiber 16 and the second optical fiber 17. Do. For example, the optical demultiplexing unit 23a multiplexes the packet data from the OSU 26a and transmits the multiplexed data to the node 14P via the first optical fiber 16, and separates the optical burst data from the node 12P and outputs it to the OSU 26a. .

  The optical demultiplexing units 31a and 31b in the nodes 12P to 14P also perform any of multiplexing, demultiplexing, and through processing as described above. For example, the optical demultiplexing unit 31a multiplexes packet data from the ONU 32a and transmits it to the node 12P via the first optical fiber 16, demultiplexes the optical burst data from the node 14P, and outputs the optical burst data to the ONU 32a, or The optical burst data from the node 14P is passed through and transmitted to the node 12P.

  The ONUs 32a and 32b transmit and receive data related to the PON. The ONUs 32a and 32b receive optical data from the OSUs 26a and 26b of the representative node 11P and output the optical data to the SW unit 33, and receive packet data from the SW unit 33 and transmit optical bursts to the OSUs 26a and 26b. . The IO units 34a to 34n terminate the client signals transmitted from the hosts 43a to 43n and transmit them to the SW unit 33, and transmit the signals from the SW unit 33 to the hosts 43a to 43n as client signals.

FIG. 10 shows a light concentration network system 10Q with 1: 1 protection. Similarly to the optical concentration network system 10P of FIG. 9, in this optical concentration network system 10Q, the optical transmission device 11Q (representative node 11Q) and the optical transmission devices 12Q to 14Q (nodes 12Q to 14Q) are physically independent. It is connected in a ring shape by a first optical fiber 16 and a second optical fiber 17 as two signal transmission paths.
Comparing FIG. 9 with FIG. 10, the optical demultiplexing units 23a and 23b of the representative node 11P replace the light SW 29 of the representative node 11Q, and the optical demultiplexing unit 31 of each of the nodes 12P to 14P corresponds to each of the nodes 12Q to 14Q. Coupler group (1x2 coupler 31a1, 1x2 coupler 31a2, 2x1 coupler 31a3). That is, in the “1: 1 protection”, since it is not necessary to receive data from a plurality of optical fibers at the same time, the reception interface of each of the nodes 12P to 14P can be simplified as a coupler group.

  The light SW 29 accommodates two optical fibers. Then, when the optical SW 29 detects a fault such as the cardiac muscle breakage of one optical fiber in operation, the optical SW 29 newly operates another optical fiber which is not operating and switches the route. This realizes failure recovery.

K.-D. Langer et al., "Promising Evolution Paths for Passive Optical Access Networks," Proc. ICTON 2004, Tu. B.1.1. C.-H. Yehet al., “A Protection Method for Ring-Type TDM-PONs against Fiber Fault” Proc. OFC / NFOEC, Mar. 2007.

When providing network services, it is necessary to balance and realize both the improvement of the quality of service and the reduction of the cost for providing the service.
In the optical concentration network system 10P in which 1 + 1 protection is realized as in Non-Patent Document 1 etc., the amount of equipment such as requiring two ONUs 32 in each ring node increases.
In the optical concentration network system 10Q in which 1: 1 protection is realized, such as Non-Patent Document 2, only one ONU 32 is required for each ring node, so that the amount of equipment can be reduced. However, in 1: 1 protection, since failure detection and switching processing are performed after failure occurrence, switching time to the spare system at the time of failure occurrence occurs more than in 1 + 1 protection, and network reliability due to the data blocking time Will decrease.

  Therefore, the present invention has as its main object to provide a well-balanced network service using an optical TDM technology represented by PON, which has high fault tolerance and reduced the amount of equipment.

In order to solve the above problems, according to the present invention, a representative node as a control entity and a plurality of controlled nodes controlled by the representative node are connected on a PON in a ring shape by a plurality of optical transmission lines. An optical transmission system that performs communication control of signals transmitted by
Said controlled node, when transmitting or receiving a same data signal to each of the optical transmission path, it has a ONU to switch the different wavelengths the wavelengths of the data signal flowing through each of said optical transmission line,
The data signal reordering process is performed so that the representative node is the controlled node whose distance on the optical transmission path from the representative node is longer, the data signal destined for the controlled node is earlier. It is characterized by doing .

Thus, the controlled node can perform data communication with a plurality of optical transmission paths with one ONU. Therefore, by flowing the same data signal to a plurality of optical transmission paths, it is possible to provide a PON service with high fault tolerance, and to reduce the amount of equipment by eliminating the need for the controlled node to have a plurality of ONUs. it can.
In addition, since the total time required for transmission to the controlled node can be shortened, throughput is improved.

In the present invention, communication control of a signal transmitted on a PON in which a representative node as a control entity and a plurality of controlled nodes controlled by the representative node are connected in a ring shape by a plurality of optical transmission lines An optical transmission system that
When the controlled node transmits or receives the same data signal for each of the optical transmission paths, it has an ONU that switches the wavelength of the data signal flowing through each of the optical transmission paths as different wavelengths.
In a period in which the representative node performs an operation of switching the wavelength at which the ONU of the controlled node receives a data signal, an idle signal whose data content has no meaning and may be discarded may be transmitted to the controlled node. It is characterized by transmitting.

Thus, the controlled node can perform data communication with a plurality of optical transmission paths with one ONU. Therefore, by flowing the same data signal to a plurality of optical transmission paths, it is possible to provide a PON service with high fault tolerance, and to reduce the amount of equipment by eliminating the need for the controlled node to have a plurality of ONUs. it can.
Also , by sending an idle signal (during preparation for reception) while the reception wavelength switching processing of the ONU is being performed, it is possible to prevent the data signal from arriving erroneously.

  The present invention is characterized in that the ONU of the controlled node performs an operation of switching a wavelength when transmitting and receiving a data signal of the own device independently of an operation of switching a wavelength of the ONU of another device. Do.

  As a result, it is possible to reduce the waiting time until all the nodes complete the wavelength switching and become able to communicate, thereby improving the throughput.

According to the present invention, communication of signals transmitted on a PON connected in a ring shape by at least two optical transmission paths between a representative node as a control entity and a plurality of controlled nodes controlled by the representative node An optical transmission system that performs control,
The controlled node is
An ONU that transmits data signals at a fixed wavelength and receives data signals at a predetermined wavelength ;
Data transmitted to each of the optical transmission paths by performing wavelength conversion on at least one data signal when transmitting a plurality of identical data signals output from the ONU to different optical transmission paths Wavelength converters that make the wavelengths of the signals different from one another;
And a band pass filter configured to switch a plurality of predetermined wavelengths from any one of the plurality of predetermined wavelengths to pass the data signal received from another node to the ONU.

  By this, even if there is no wavelength switching function inside the ONU, a network service using optical TDM technology represented by PON, which has high fault tolerance and reduced the amount of equipment and is well-balanced, is provided. be able to.

  According to the present invention, it is possible to provide a well-balanced network service using an optical TDM technology represented by PON, which has high fault tolerance and reduced the amount of equipment.

FIG. 1 shows a light concentration network system of 1 + 1 redundant configuration according to the present embodiment. FIG. 2 shows details of an optical demultiplexing unit used in the optical concentration network system of FIG. 1 according to the present embodiment. Fig. 5 shows a node used in place of the node of Fig. 1 according to the present embodiment. Fig. 5 shows a node used in place of the node of Fig. 1 according to the present embodiment. It is a sequence diagram which shows the transmission processing of the downlink signal at the time of synchronizing wavelength switching between nodes without reordering concerning this embodiment. It is a sequence diagram which shows the transmission processing of the downlink signal at the time of having reordering concerning this embodiment, and performing wavelength switching independently between nodes. It is a sequence diagram which shows the transmission processing of an upstream signal at the time of synchronizing wavelength switching between nodes concerning this embodiment. FIG. 8 is a sequence diagram showing transmission processing of uplink signals when wavelength switching is independently performed between nodes according to the present embodiment and transmission timings are assigned in order from communication with a short transmission distance. 1 shows a light concentration network system of 1 + 1 protection according to the present embodiment. 1 shows a light concentration network system with 1: 1 protection according to the present embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a light concentration network system 10A in a 1 + 1 redundant configuration. Similarly to the optical concentration network system 10P of FIG. 9 and the optical concentration network system 10Q of FIG. 10, the optical concentration network system 10A also includes the optical transmission device 11A (representative node 11A) and the optical transmission devices 12A-14A (representative node 11A). Nodes 12A to 14A as controlled nodes to be controlled are connected in a ring shape by first and second optical fibers 16 and 17 as two physically independent signal transmission paths. Between the OLT 21 and the ONU 32 in the PON of the ring topology are made redundant (fault tolerant) as two paths.
Here, although two (1 + 1 and 1: 1) are illustrated in the present embodiment as the number of optical transmission paths, two or more may be used as long as the number is two or more.

Each optical transmission apparatus is configured as a computer having a central processing unit (CPU), a memory, a storage unit (storage unit) such as a hard disk, and a network interface.
The computer operates a control unit (control means) configured of respective processing units described later by the CPU executing a program (also referred to as an application or an abbreviation of the application) read into the memory.

  Hereinafter, each component of the optical concentration network system 10A will be described focusing on differences from the optical concentration network system 10P. The components with the same reference numerals are basically the same between the optical concentration network system 10A and the optical concentration network system 10P.

The representative node 11A includes the IO units 20a to 20n for each of the host computers 41a to 41n to which the connection is to be made, the SW unit 25, the OLT 21, and two redundant optical demultiplexers 23a and 23b. Ru.
The OLT 21 has two OSUs 26 and a DWBA function unit 27.
Each node other than the representative node 11A, such as the node 13A, includes two systems of optical demultiplexing units 31a and 31b, AWGs 35a and 35b, ONU 32, SW unit 33, and IO units for host computers 43a to 43n as connection destinations. And 34a to 34n.

  The IO units 20 and 34 are network interfaces for connecting to the host computers 41 to 44. The IO unit 20 is an SNI-LT (application server-network interface-line terminal), and relays communication between the host computer 41 and the SW unit 25. The IO unit 34 is a UNI-LT (User-Network Interface-Line Terminal), and relays communication between the host computer 43 and the SW unit 33.

A zone in which PON data is transmitted and received is between the two OSUs 26 and one ONU 32. The down signal is transferred in the order of SW unit 25 → OSU 26 → ONU 32 → SW unit 33, and the up signal is transferred in the order of SW unit 33 → ONU 32 → OSU 26 → SW unit 25.
The SW units 25 and 33 transfer packet data in accordance with a transfer table set or learned in advance, in the same manner as a layer 2 switch device transferring a normal electrical packet.
The OSU 26 includes a TRX 26x, which is a transmitter / receiver, an "L1" functional unit that processes a first layer of a protocol processing unit 26y (Open Systems Interconnection) for data transfer processing, and an "L2" functional unit that processes a second layer. And.

Although two ONUs 32 are required at the node 13P, the wavelength switching control described later at the node 13A requires only one ONU 32 which also serves two systems, thus realizing downsizing of the apparatus and power saving. . On the other hand, in comparison with the node 13P, AWGs 35a and 35b are added to the node 13A. However, since the AWGs 35a and 35b are passive optical devices, they do not consume power by themselves, and are parts with little additional burden on the node 13A such as a low failure rate. Since the failure rate of the AWGs 35a and 35b is low, the maintenance cost due to failure replacement can be reduced.
Therefore, by sharing one ONU 32 physically in two systems, the effect of reducing the number of ONUs 32 is larger than the additional cost of the AWGs 35a and 35b, so the node 13A is realized at lower cost than the node 13P. it can.

The ONU 32 of the node 13A has a protocol processing unit 32y (L1 / L2 similar to the protocol processing unit 26y) for data transfer processing, similarly to the ONU 32 of the node 13P. On the other hand, ONU 32 of node 13A has Tunable-TRX 32x. This Tunable-TRX 32x can change the wavelength of an optical signal to be transmitted or received (Tunable) according to time in addition to the function of a normal transceiver (TRX).
In addition, it is suggested that the transceiver (TRX) on the ONU 32 side has wavelength variability in the access system standard NG-PON 2 (Next-Generation Passive Optical Network 2) standardized by the ITU (International Telecommunication Union). ing.

The AWG 35a is a signal branching unit for transferring data to one of the optical demultiplexing units 31a and 31b according to the transmission wavelength determined by the Tunable-TRX 32x.
The AWG 35 b is a signal transfer unit that transfers data received from the optical demultiplexing units 31 a and 31 b to the Tunable-TRX 32 x. The Tunable-TRX 32x can receive two systems of data by changing the setting of the reception wavelength (Tunable Filter).

  The optical demultiplexing units 23 and 31 perform Add / Drop / Through of optical signals transmitted in the PON. In the representative node 11P, illustration of the inside of the optical demultiplexing unit 23 is omitted. However, in the representative node 11A of FIG. The parts (23a1, 23a2, 23b1, 23b2) are also illustrated. These optical communication units are mounted, for example, as a functional unit (for example, an AWG, an optical coupler, an optical splitter, etc.) that performs optical multiplexing and optical demultiplexing.

The DWBA function unit 27 manages the wavelength in the PON and the allocation state of the TDM. Then, the DWBA function unit 27 performs control processing of each of the representative nodes 11A and the nodes 12A to 14A as illustrated below.
Performs DBA (Dynamic Bandwidth Allocation) calculation and DWBA calculation, and notifies the OSU 26 and the SW unit 25 of the calculation result to dynamically allocate the PON band and wavelength resource to the ONU.
Control to switch the wavelength that Tunable-TRX 32x uses for transmission and reception at a predetermined timing.
• Instructs the IO units 20 and 34 to insert an idle signal for reception wavelength switching, and instructs reordering of data signals to be transmitted (change of transmission order).

As the transfer processing of the downstream signal, when the IO unit 20 receives from the host computer 41 a signal whose destination is the host computer 43, the downstream unit copies the downstream signal and rotates the copy result clockwise (first optical fiber 16). It transfers sequentially via separate OSU 26a, 26b by counterclockwise rotation (2nd optical fiber 17).
The Tunable-TRX 32x sequentially receives downstream signals of the two wavelengths by switching the reception wavelength setting. The IO unit 34 selects one signal from the received two downstream signals by the selector, and transfers the one signal to the host computer 43.

As the transfer processing of the upstream signal, when the IO unit 34 receives the signal having the host computer 41 as the destination from the host computer 43, the IO unit 34 copies the upstream signal and rotates the copy result clockwise (first optical fiber 16). The wavelengths are switched to different wavelengths in the counterclockwise direction (the second optical fiber 17) and then sequentially transferred. Therefore, the Tunable-TRX 32x sequentially transmits upstream signals of the two wavelengths by switching the transmission wavelength setting.
The IO unit 20 transfers one signal to the host computer 41 after the selector selects one signal from two upstream signals received by two different OSUs 26 respectively.

  Thus, similarly to the optical concentration network system 10P, the optical concentration network system 10A can provide 1 + 1 protection. That is, even if any of the first optical fiber 16 or the second optical fiber 17 is broken, the data signal is transferred from the remaining unbroken optical fiber, so the data signal interruption time is not generated. It is

FIG. 2 shows the details of the optical demultiplexing unit 31b of FIG.
The optical demultiplexing unit 31b includes components for processing upstream signals (MUX 101, coupler / AWG 102a, amplifier 103a, filter 104) and components for processing downstream signals (MUX 101, coupler / AWG 102b, amplifiers 103b, Filter 104). And.
Both the couplers / AWGs 102 a and 102 b input the signal to be through from the side of the filter 104 and output the signal to the side of the MUX 101.
An upstream signal to be added is input from the AWG 35 a to the coupler / AWG 102 a.
The coupler / AWG 102 b outputs the signal to be dropped to the AWG 35 b.
Since the amplifiers 103a and 103b only amplify the signal, they may be omitted as appropriate.

FIG. 3 shows a node 13B used in place of the node 13A in the optical concentration network system 10A of FIG. In place of the Tunable-TRX 32x of the node 13A, a TRX 32z having no wavelength switching function is used at the node 13B.
Therefore, in order to give the same function to the node 13A and the node 13B, the node 13B has a wavelength switching function outside the TRX 32z.

  Specifically, a TWC (Tunable Wavelength Converter) 112 which is a wavelength converter is provided on the output side of the ONU 32. Furthermore, the transmission path passing through the TWC 112 and the transmission path not passing through the TWC 112 are divided by the splitter 111, and the transmission path is integrated and output to the AWG 35a. In the AWG 35a, since the signal passing through the TWC 112 and the signal not passing through the TWC 112 have different wavelengths, they can be distributed to separate optical fibers.

Further, the AWG 35 b multiplexes the signal from the first optical fiber 16 and the signal from the second optical fiber 17. Therefore, it is a filter that passes only the signal of the desired wavelength and inputs it to the ONU 32, and uses the Tunable-BPF 114 that can switch the desired wavelength.
A signal which is not passed by the Tunable-BPF 114 is output to the receiver Rx 115 and the buffer 116. This output signal can be used as spare system information.

FIG. 4 shows a node 13C used in place of the node 13A in the optical concentration network system 10A of FIG. Compared to the node 13A, two ONUs 32a are deployed in the node 13C. Further, in the node 13C, optical signal processing units 121 and 122 for transmitting and receiving signals between the two ONUs 32a and the AWGs 3535a and 35b are added.
Thus, although the amount of equipment increases, even if one of the ONUs 32a fails, the reliability can be secured by the operation of the other ONU 32a.

  The node 13C realizes 1 + 1 protection on the line side, in which Tunable-TRX 32x transmits and receives two different wavelength signals to the first optical fiber 16 and the second optical fiber 17, respectively. On the other hand, the two ONUs 32a in the node 13C can perform any of the following operations.

  (Operation 1) One ONU 32a is operated, and when the ONU 32a fails, the operation of another ONU 32a is started (redundant configuration such as 1: 1 protection of ONU device). That is, one ONU 32a of the two ONUs 32a is switched to operate. As a result, power saving can be realized because one ONU 32a is in a sleep state before a failure occurs.

  (Operation 2) The two ONUs 32a are operated in combination, and when one ONU 32a fails, the operation of the other ONU 32a is continued (redundant configuration such as 1 + 1 protection of ONU device). That is, due to the occurrence of a failure, two ONUs 32a are degenerated into one ONU 32a. As a result, even when a failure occurs, it is not necessary to cause a data communication break. Furthermore, by operating the two ONUs 32a, even if maintenance work such as component replacement is performed for one of the ONUs 32a, since the other ONU 32a is operating, no data communication interruption occurs. It is

  As described above, the node 13C described in FIG. 4 has a configuration in which the number of ONUs 32a (including the Tunable-TRX 32x) of the node 13A is increased to two. Similarly, the combination of the ONU 32 (TRX 32z not including the Tunable function) of the node 13B and the Tunable function (such as the TWC 112 or Tunable-BPF 114 in FIG. 3) may be increased to two sets.

  The flow of signals (data signals, control signals for wavelength switching, etc.) flowing through the light concentration network system 10A will be described below with reference to the sequence diagrams of FIGS. In the optical concentration network system 10A of FIG. 1, three nodes (nodes 12A to 14A) other than the representative node 11A are described, but in each sequence diagram, four nodes (nodes 12A to 15A) are described. . Furthermore, each node may be replaced with the nodes 13B and 13C of the modified example described in FIGS. 3 and 4.

FIG. 5 is a sequence diagram showing transmission processing of the downlink signal without reordering. Reordering is a process of changing the transmission order of a plurality of signals. Since the process of FIG. 5 is a relatively simple process, it has an advantage of easy implementation and operation.
Signals flowing from the left to the right in FIG. 5 (representative node 11A → node 12A → node 13A →...) Are signals flowing through the second optical fiber 17, and a signal flowing from the right to the left (representative node 11A → node 15A) → Node 14A → ...) are signals flowing through the first optical fiber 16. Note that “receive” shown in the figure indicates that the corresponding node receives (drops) the signal, and indicates that the node transfers (through) the signal in a place where “receive” is not described.

After flowing the signal of the first system from the representative node 11A to each node by way of the second optical fiber 17, each node switches the reception wavelength, whereby the signal of the second system is transmitted via the first optical fiber 16 You can receive the street.
The idle signal is a signal whose data content only for filling the blank period in which no data signal flows is meaningless and may be discarded, and is not transmitted to the host computers 41 to 44. Since the downstream signal is transmitted as a continuous signal with no gap, an idle signal is required in a period in which no data signal is generated. Also, by sending an idle signal (during preparation for reception) while performing wavelength switching processing in each ONU 32, it is possible to prevent the data signal from arriving erroneously.

Here, the command for activating the wavelength switching process is issued by, for example, the DWBA function unit 27, multiplexed with a normal data signal, and transmitted via the same route. Hereinafter, the information included in the wavelength switching command will be exemplified.
-Wavelength switching instruction to ONU 32 (ID of ONU32 / Tunable-TRX 32x, switching symmetry: both transmission / reception / transmission / reception, wavelength after switching, switching timing)
・ Idle signal transmission instruction to OSU 26 (ID of OSU26 / TRX26x, start timing of idle signal, end timing)

FIG. 6 is a sequence diagram showing transmission processing of a downlink signal with reordering.
First, the common point between FIG. 5 and FIG. 6 is rough control of signal transmission of the first system → reception wavelength switching → signal transmission of the second system → reception wavelength switching → signal transmission of the first system →...

  On the other hand, as a difference between FIG. 5 and FIG. 6, in FIG. 6, in the transmission processing of each system, the node that is the transmission destination has a longer transmission distance (hop number of nodes) from the representative node 11A of the transmission source. The point is that reordering processing is performed in which the order is changed first and then transmission. For example, in FIG. 5, although the transmission order to the node 15A at the first time was later than that of other nodes, the transmission distance from the representative node 11A to the node 15A is the longest, so in FIG. Replace with The nodes other than the representative node 11A need to correspond to two systems by one TRX, and by performing this processing, it is possible to suppress the total time required for communication of the two systems.

In order to realize the reordering process, the DWBA function unit 27 further instructs the IO unit 20 to perform reordering instruction (signal information to be reordered, reordering on / in addition to the wavelength switching instruction described above with reference to FIG. Off, ordering information).
In addition, reception wavelength switching timings in nodes other than the representative node 11A are independently performed without synchronization. Through these, the throughput of the downlink signal can be improved.

FIG. 7 is a sequence diagram showing transmission processing of uplink signals when wavelength switching is synchronized between nodes. The representative node 11A receives the uplink signal transmitted from each node other than the representative node 11A. In the uplink processing of FIG. 7 as well as the downlink processing of FIG. 5, after the first system signal flows from each node via the second optical fiber 17, each node synchronously switches the transmission wavelength. , And the second system signal can be transmitted through the first optical fiber 16.
As described with reference to FIG. 5, the DWBA function unit 27 transmits, to each node, a wavelength switching instruction including the switching timing and the like even in the case of the upstream signal. In addition, since the upstream signal of FIG. 7 is a burst signal (temporal intermittent signal), it becomes a non-signal period which does not output light except data transmission timing. Therefore, unlike FIG. 5, the idle signal is unnecessary.

FIG. 8 is a sequence diagram showing transmission processing of upstream signals when wavelength switching is independently performed between nodes. Unlike FIG. 7, each node switches the transmission wavelength after its own transmission processing independently without synchronizing with other nodes.
As a result, since it is possible to reduce the waiting time until all nodes complete wavelength switching and become able to communicate, throughput is improved. In addition, since the DWBA function unit 27 arbitrarily assigns transmission timings to perform data transmission sequentially from the node with the smallest transmission distance from the representative node 11A, it is possible to suppress the total time required to complete data communication.

In the present embodiment described above, the control method of the light concentrating network system 10A utilizing the PON device and device has been described.
In the optical concentration network system 10P in which 1 + 1 protection is realized by the PON in the ring topology, the amount of equipment such as requiring two ONUs 32 in each ring node increases.
On the other hand, in the optical concentration network system 10Q in which the 1: 1 protection is realized, only one ONU 32 is required for each ring node, so the amount of equipment can be reduced. However, in the 1: 1 protection, since the switching time to the spare system at the occurrence of a failure occurs, the reliability of the network is reduced due to the data blocking time.
Therefore, in the optical concentration network system 10A, one ONU 32 having a Tunable-TRX 32x is prepared for each node. As a result, it is possible to provide a network service using an optical TDM technology represented by PON, which is well-balanced with a reduced amount of equipment while realizing 1 + 1 protection by wavelength switching.

10A Optical Clustering Network System 11A Representative Node 12A-15A Node (Controlled Node)
16 1st optical fiber 17 2nd optical fiber 20 IO section 21 OLT
23 optical demultiplexing unit 25 SW unit 26 OSU
27 DWBA function unit (wavelength switching control unit)
31 optical demultiplexing unit 32 ONU
32x Tunable-TRX
32z TRX
33 SW section 34 IO section 35 AWG
41a to 41n host computer

Claims (7)

Communication of signals transmitted on a PON (Passive Optical Network) in which a representative node as a controlling entity and a plurality of controlled nodes controlled by the representative node are connected in a ring shape by a plurality of optical transmission paths An optical transmission system that performs control,
Said controlled node, when transmitting or receiving a same data signal to each of the optical transmission path, have a ONU (Optical Subscriber Unit) for switching the different wavelengths of the wavelength of the data signal flowing through each of said optical transmission line,
The representative node performs a data signal reordering process such that the transmission order of data signals to the controlled node becomes faster as the distance from the representative node to the controlled node increases as the distance on the optical transmission path increases. An optical transmission system characterized by performing . Communication of signals transmitted on a PON (Passive Optical Network) in which a representative node as a controlling entity and a plurality of controlled nodes controlled by the representative node are connected in a ring shape by a plurality of optical transmission paths An optical transmission system that performs control,
Said controlled node, when transmitting or receiving a same data signal to each of the optical transmission path, have a ONU (Optical Subscriber Unit) for switching the different wavelengths of the wavelength of the data signal flowing through each of said optical transmission line,
The representative node transmits, to the controlled node, an idle signal whose data content is discarded during a period in which the ONU of the controlled node performs an operation of switching a wavelength when receiving a data signal. Optical transmission system. The ONU of the controlled node executes an operation of switching a wavelength when transmitting and receiving a data signal of the own device, independently of an operation of switching a wavelength of the ONU of another device. Or the optical transmission system of Claim 2 . A signal transmitted on a PON (Passive Optical Network) in which a representative node as a control entity and a plurality of controlled nodes controlled by the representative node are connected in a ring by at least two optical transmission paths An optical transmission system that performs communication control,
The controlled node is
An ONU (Optical Subscriber Unit) that transmits data signals at a fixed wavelength and receives data signals at a predetermined wavelength ,
Data transmitted to each of the optical transmission paths by performing wavelength conversion on at least one data signal when transmitting a plurality of identical data signals output from the ONU to different optical transmission paths Wavelength converters that make the wavelengths of the signals different from one another;
An optical transmission system comprising: a band pass filter for switching from a plurality of predetermined wavelengths to any one wavelength and passing the data signal received from another node to the ONU. Communication of signals transmitted on a PON (Passive Optical Network) in which a representative node as a controlling entity and a plurality of controlled nodes controlled by the representative node are connected in a ring shape by a plurality of optical transmission paths An optical transmission method performed by an optical transmission system that performs control,
Wherein the controlled node ONU (Optical Subscriber Unit), when sending or receiving a same data signal to each of the optical transmission path, switching the different wavelengths the wavelengths of the data signal flowing through each of said optical transmission line,
The representative node performs a data signal reordering process such that the transmission order of data signals to the controlled node becomes faster as the distance from the representative node to the controlled node increases as the distance on the optical transmission path increases. An optical transmission method characterized by performing . Communication of signals transmitted on a PON (Passive Optical Network) in which a representative node as a controlling entity and a plurality of controlled nodes controlled by the representative node are connected in a ring shape by a plurality of optical transmission paths A controlled node used in an optical transmission system that performs control,
Said controlled node, when transmitting or receiving a same data signal to each of the optical transmission path, switching the different wavelengths the wavelengths of the data signal flowing through each of said optical transmission line, the reordering instruction from the representative node have a ONU that sends and receives data signals at timing (Optical Subscriber Unit),
The reordering instruction is an instruction to make the transmission order of data signals to the controlled node earlier as the controlled node is longer as the distance from the representative node on the optical transmission path is longer. Control node. Communication of signals transmitted on a PON (Passive Optical Network) in which a representative node as a controlling entity and a plurality of controlled nodes controlled by the representative node are connected in a ring shape by a plurality of optical transmission paths An optical transmission program executed by an optical transmission system that performs control, comprising:
In the case of transmitting or receiving the same data signal for each of the optical transmission paths to an ONU (Optical Subscriber Unit) of the controlled node, the wavelength of the data signal flowing through each of the optical transmission paths is switched as different wavelengths .
In the representative node, the data signal reordering process is performed so that the transmission order of the data signal to the controlled node becomes faster as the distance to the controlled node increases as the distance from the representative node on the optical transmission path increases. An optical transmission program characterized in that it is performed .

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