JP6457915B2 - Optical transmission apparatus, optical concentrating network system, optical transmission method and program - Google Patents

Description

  The present invention relates to an optical transmission apparatus, an optical concentration network system, an optical transmission method, and a program utilizing a device and an apparatus for communication using optical TDM (Time Division Multiplexing) technology represented by PON (Passive Optical Network). .

  Conventionally, as a network using optical TDM technology, for example, PON 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 house are connected via an optical fiber and an optical coupler. Usually, a plurality of ONUs are connected to one OLT, and TDM or TDMA (Time Division Multiple Access) is applied between the OLT and ONU to multiplex and demultiplex data in an optical area while applying data. By transmission, resources such as optical fiber cores and OLTs 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.

  Although a tree configuration is often adopted as the physical topology of PON, as described in Non-Patent Document 1, a ring configuration is also considered. A configuration example of 1 + 1 protection (described later) between OLT and ONU in the PON of this type of ring configuration is shown in FIG.

FIG. 8 is a block diagram showing the configuration of the optical concentrator network system 10 when PON is applied to the ring topology.
In the optical concentration network system 10 shown in FIG. 8, an optical transmission device 11 as a representative node and a plurality of optical transmission devices 12, 13 and 14 as nodes are two physically independent signal transmission paths. It is connected in a ring shape by a first optical fiber (first optical transmission line) 16 and a second optical fiber (second optical transmission line) 17. The transmission lines of the two ring-shaped optical fibers 16 and 17 can transmit data in the clockwise direction and the counterclockwise direction in mutually different directions (reciprocal directions) indicated by the arrows, and a failure occurs in either one of the transmission lines. When the transmission occurs and becomes impossible, transmission is possible on the other transmission line. This is the configuration of the 1 + 1 protection described above. The optical transmission device 11 is also referred to as a representative node 11, and each of the optical transmission devices 12, 13 and 14 is also referred to as a node 12, 13 and 14.

  The representative node 11 includes a plurality of IO (input / output processing) units 20a to 20n, an OLT 21, and optical demultiplexing units 23a and 23b. The OLT 21 is configured to include an SW (switch) unit 25, an OSU (Optical Subscriber Unit) 26a and 26b, and a DWBA (Dynamic Wavelength and Bandwidth Assignment) function unit 27.

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

  In representative node 11, 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 11 on a one-to-one basis, and perform SNI transmission / reception with hosts 41a to 41n. -LT (application server-network interface-line terminal). Also in the node 13, a plurality of hosts 43a to 43n outside the node 13 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 12 and 14, hosts 42a to 42n and 44a to 44n (only one is shown) are connected to the IO units (not shown) one to one.

  The IO units 20a to 20n of the representative node 11 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 26a to the host (for example, 41a) 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 PDS (Passive Double Star) optical line termination devices. The OSUs 26a and 26b receive the optical burst data from the ONUs 32a and 32b of the nodes 12 to 14 and output the optical burst data 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 12 to 14, dynamic wavelength switching is also considered in accordance with the traffic volume while considering dynamic wavelength switching. It is to allocate a band.

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

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

  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 11 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.

  In the system 10 having such a configuration, for example, when transmitting a client signal transmitted from the host 43a connected to the IO unit 34a of the node 13 to the host 41a connected to the IO unit 20a of the representative node 11, It is possible to transmit clockwise through the one optical fiber 16 as indicated by the arrow Y 1 or counterclockwise as indicated by the arrow Y 2 through the second optical fiber 17. That is, data transmission can be performed clockwise and counterclockwise using two ring-shaped transmission paths. Therefore, when a failure occurs in one of the transmission paths and transmission becomes impossible, data transmission can be performed through the other transmission 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 transmission paths (arrow Y1), data transmission can be performed through the other transmission path (arrow Y2) without stopping data transmission.

G. Kramer, B. Mukherjee and G. Pesavento, EthernetPON (ePON): design and analysis of an optical access network, Phot. Net. Commun., [Online], 3, 2001, [September 25, 2015] , Internet <URL: http://www.www.glenkramer.com/papers/epon_pnc.pdf> "IEEE Std. 802.3ah-2004", IEEE, 2004, Section 44.3.2.2 Optional Shared LAN Emulation, [online], 2004, [search on September 25, 2015], Internet <URL: http: // www .google.com / url?> N. Nadarajah et al., “Novel Schemes for Local Area Network Emulation in Passive Optical Networks With RF Subcarrier Multiplexed Customer Traffic,” Journal of Lightwave Technology, [online], Oct. 2005, [September 25, 2015] , Internet <URL: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad> AD Hossain et al., “Ring-based local access PON architecture for supporting private networking capabilities,” OSA Journal of Optical Networking, vol. 5, no. 1, pp. 26-39, [online], Jan. 2006, [ Search on September 25, 2015], Internet <URL: http://www.eng.uwo.ca/electrical/faculty/shami_a/publications.html>

  By the way, in order to provide a flexible communication form in the system 10 described above, communication between ONUs of different nodes 12 to 14 becomes important. However, in the PON, basically, only communication between the OLT 21 and the ONUs 32a and 32b is supported, and direct communication between the ONUs of any of the nodes 12 to 14 is impossible.

  As a means for realizing communication between ONUs, Non-Patent Document 2 describes a study of an OLT loopback method in which data from an ONU of a certain node is folded back by the OLT and transmitted to an ONU of another node. This is a designation “Shared LAN Emulation”, and is optionally defined in the Ethernet Passive Optical Network (EPON) (Ethernet: registered trademark) of IEEE of the Institute of Electrical and Electronics Engineers.

  For example, as shown in FIG. 9A, the transmission data is copied (copied) in the node 12 as shown in FIG. The transmission path is transmitted in the counterclockwise direction passing through the node 13 shown by Y 4, and these data are folded back at the OLT of the representative node 11 and transmitted to another node 14. Alternatively, as shown in FIG. 9B, the transmission data is copied at node 12 and transmitted in the clockwise direction indicated by arrows Y5 and Y6, and the data indicated by arrow Y5 is transmitted at the OLT of representative node 11 It turns around clockwise and transmits to another node 15. On the other hand, the data indicated by the arrow Y6 is turned counterclockwise at the OLT of the representative node 11, passes through the node 13, and is transmitted to another node 14 counterclockwise.

  However, in FIG. 9A, the data after the turning back at the OLT indicated by the arrow Y4 is transmitted to the node 14 through the same transmission path as the data after the turning back at the OLT indicated by the arrow Y3. Therefore, when the failure 100 occurs in the optical fiber of the same transmission line and transmission becomes impossible, the copied data of both systems become transmission impossible, so the data is normally transmitted by the other transmission line that can be realized by 1 + 1 protection. There is a problem that transmission can not be continued.

  Further, in FIG. 9B, data of both systems before turning back at the OLT indicated by arrows Y5 and Y6 are transmitted to the OLT through the same transmission path in the same direction. For this reason, when failure 101 occurs in the optical fiber of the same transmission path and transmission becomes impossible, there arises a problem that transmission of data of both systems copied by node 12 becomes impossible.

  Besides this, as described in Non-Patent Document 3, a method for realizing communication between ONUs without OLT folding has also been proposed. However, there is a problem that the cost increases because the transmission / reception function of the OLT is required for all ONUs, or a special device for reflecting data between ONU nodes is required.

  Furthermore, as described in Non-Patent Document 4, a configuration in which data is relayed and transmitted by ONU of each node on a ring has been proposed as a configuration without OLT folding back. However, in that configuration, even if the special device between the nodes is minimized, the ONU electrically receives and transmits data one node at a time, so that the nodes become in chains, and the transmission delay increases. There is a problem of

  The present invention has been made in view of such circumstances, and can perform highly reliable inter-ONU communication equivalent to 1 + 1 protection without increasing delay due to addition of a special device or electrical processing. An object of the present invention is to provide an optical transmission apparatus, an optical concentration network system, an optical transmission method, and a program.

As means for solving the above problems, the invention according to claim 1 is an OLT (Optical Line Terminal) as an optical line termination device that terminates a signal transmitted to and received from an external device and serves as a control subject , A plurality of ONUs (Optical Network Units) as optical circuit terminating devices serving as objects for the control entity are connected in a ring by at least two optical transmission lines, and the two optical transmission lines are identical to the same data. path between the ONU but when passing through, an optical transmission apparatus having the OLT from one of the ONU are turned back at the OLT is need use the network to be transmitted to the other of the ONU, via the OLT , Path setting control means for performing control to set three independent logical paths, and when the path setting control means performs setting control of the three paths, And at least two paths between the ONU and the OLT toward the OLT via the optical transmission path in the opposite direction, and the data folded back at the OLT travels to the ONU via the two optical transmission paths in the opposite direction, It is an optical transmission apparatus characterized in that control is performed to set the three paths in three different ones of at least four paths in which at least two paths between ONUs are combined.

  The invention according to claim 6 is characterized in that a first optical transmission apparatus having an OLT as an optical line termination apparatus which terminates a signal transmitted to and received from an external apparatus, and which is a control subject, and an object with respect to the control subject And a plurality of second optical transmission devices each having an ONU as an optical line termination device, and the first optical transmission device and the second optical transmission device connected in a ring shape, and data is reciprocated in the ring path. What is claimed is: 1. A light concentration network system comprising: two optical transmission lines for transmission, wherein data is returned from one of the ONUs to the OLT and transmitted to the other of the ONUs; The path setting control means performs control to set three independent logical paths in the path between the ONUs via the OLT, and the path setting control means performs setting control of the three paths, Data is before At least two paths between the ONU and the OLT that travel from the ONU to the OLT via the two optical transmission paths in the opposite direction, and the data folded back at the OLT passes the two optical transmission paths in the opposite direction. It is an optical concentration network system characterized in that control is performed to set the three paths in three different paths out of at least four paths combining an OLT going to an ONU and at least two paths between the ONUs.

The invention according to claim 7, terminates the signal transmitted and received between the external device, and the OLT as an optical line terminal to be controlled mainly as an optical line terminal comprising the object with respect to the control entity A plurality of ONUs are connected in a ring shape by at least two optical transmission paths, and when the same data passes through the two optical transmission paths, one of the ONUs is folded back at the OLT and the other of the ONUs an optical transmission apparatus having the OLT that need use the network to be transmitted to the previous SL optical transmission apparatus, the path between the ONU via the OLT, to set an independent logical three paths In the step of performing control and in performing the setting, at least two paths between the ONU and the OLT, wherein the data travels from the ONU to the OLT through the two optical transmission paths in opposite directions, The three paths among three different paths among at least two paths in which data folded back by LT is directed to the ONU through the two optical transmission paths in the opposite direction and at least two paths between the ONU and the ONU And performing the control of setting.

The invention according to claim 8, terminates the signal transmitted and received between the external device, and the OLT as an optical line terminal to be controlled mainly as an optical line terminal comprising the object with respect to the control entity A plurality of ONUs are connected in a ring shape by at least two optical transmission paths, and when the same data passes through the two optical transmission paths, one of the ONUs is folded back at the OLT and the other of the ONUs the computer as an optical transmission device having the OLT that need use the network to be transmitted to, the path between the ONU via the OLT, separate lines cormorants means control to set the logical three paths, when performing control of the setting, the at least two paths between ONU and OLT the data through the opposite directions through the optical transmission line of the two from the ONU toward the OLT, folding in the OLT The three data paths are set in three different paths among at least four paths combining the OLT and the at least two paths between the ONUs toward the ONU via the two optical transmission paths in opposite directions. It is a program for functioning as a means to perform control.

  According to the constructions of claims 1, 6, 7 and 8, the following effects can be obtained. There are at least four paths between the ONU and the OLT, and between the OLT and the ONU, since they are transmittable in opposite directions by two ring-shaped optical transmission paths. Three independent paths are set in three different ones of the four paths, and the same three data paths are transmitted with the same data. As a result, data can be transmitted through the other optical transmission path even if a failure occurs in one of the optical transmission paths between the ONUs turned back at the OLT at the start point and the end point of the data transmission. Therefore, highly reliable inter-ONU communication equivalent to 1 + 1 protection can be performed without increasing the delay due to the addition of a special device or electrical processing for each node.

  In the invention according to claim 2, the path setting control means reduces delay from each path in which data transmission is performed in opposite directions in the two optical transmission paths between the ONU and the OLT and between the OLT and the ONU. The optical transmission apparatus according to claim 1, wherein control is performed to set the three paths in order of paths.

  According to this configuration, since data transmission is performed by setting three paths in order of paths with less delay, high-speed transmission with less delay can be performed.

  In the invention according to claim 3, when the path setting control means performs communication between the ONUs via the OLT, it is possible to distribute the total bandwidth obtained by integrating a plurality of wavelengths to each ONU to a predetermined bandwidth. 3. The optical transmission apparatus according to claim 1, wherein control is performed to dynamically switch wavelengths and allocate bands.

  According to this configuration, in the communication between ONUs by turning back the OLT, the wavelength and the band can be dynamically and flexibly allocated by performing the dynamic band allocation, so that efficient communication can be realized. .

The invention according to claim 4 terminates the signal transmitted and received between the external device, and the OLT as an optical line terminal to be controlled mainly as an optical line terminal comprising the object with respect to the control entity A plurality of ONUs are connected in a ring shape by at least two optical transmission paths, and when the same data passes through the two optical transmission paths, one of the ONUs is folded back at the OLT and the other of the ONUs an optical transmission apparatus having the OLT that need use the network to be transmitted to the OLT, in the path between the ONU via the OLT, through said optical transmission path of the two from the ONU Set up two paths in the upstream route to the OLT, branch one of the two paths at the turnaround point at the OLT, and add the other of the two paths to this bifurcated path Path setting control means for performing control to set three paths from the turning point of the OLT to the downstream path toward the ONU via the two optical transmission paths, and two paths of the upstream path And a multiplexer unit for copying one of the two data passed through to make two data, and a multiplexer unit for transmitting the copied two data to the bifurcated path at the turning point. An optical transmission apparatus characterized by

  According to this configuration, in the upstream and downstream paths through the two optical transmission paths between the ONUs that return at the start point and the end point of the data transmission in the opposite direction, a failure occurs in one optical transmission path. Even in this case, data can be transmitted through the other optical transmission line. Furthermore, since only two upstream paths are required, bandwidth consumption can be reduced.

According to claim 5 the invention, prior Symbol OLT, comprising: a load data is folded in the OLT, a monitor section for monitoring a load which is the sum of the load of the data transmitted towards the relevant OLT to the ONU the path setting control means, when the previous SL two paths set and the first path setting a three path to the downlink path to the upstream path is made, the load to be monitored by the monitor unit Switching to a second path setting in which three independent logical paths are set in a path between the ONUs via the OLT when the amount is equal to or more than a predetermined first load amount; when the setting is made, when a load to be monitored by the monitor unit becomes second load below a predetermined, and performs control to switch on the first path setting according the optical transmission instrumentation according to claim 4 It is.

  According to this configuration, the following effects can be obtained. In the first path setting, when the communication load increases in the OLT, congestion occurs with communication data for branching and return processing in the OLT in addition to the downstream communication data from the normal OLT to the ONU. there is a possibility. Therefore, during the first path setting, the monitoring unit monitors the communication load amount in the OLT, and when the monitoring load amount becomes equal to or more than the predetermined first load amount, switching control to the second path setting is performed. I do. In this second path setting, since there is no branching and loop back processing in the OLT as in the first path setting, the above congestion can be eliminated. In addition, since the switching to the first path setting is made when the second load amount is less than or equal to the second path setting, band consumption can be reduced.

  According to the present invention, an optical transmission apparatus capable of performing highly reliable inter-ONU communication equivalent to 1 + 1 protection without adding a special device or increasing delay due to electrical processing, optical concentration network system, optical transmission Methods and programs can be provided.

FIG. 1 is a block diagram showing a configuration of a light concentration network system according to a first embodiment of the present invention. It is a block diagram which shows the structure of the node of 1st Embodiment, and the flow of copied data. It is a block diagram which shows the structure of the node of 1st Embodiment, and the selection aspect of several data. It is a block diagram which shows one structural example of ONU of the node of 1st Embodiment. It is a block diagram which shows the structure of the optical concentration network system which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of the representation node of 2nd Embodiment, and the flow of copied data. It is a block diagram which shows the structure of the node of 2nd Embodiment, and the flow of copied data. FIG. 6 is a block diagram showing the configuration of a light concentration network system when PON is applied to a ring topology. (A) A block diagram showing a failure of an optical fiber after turning at an OLT in a conventional optical concentration network system, and (b) A block diagram showing a failure at an optical fiber before turning at an OLT is there.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Configuration of First Embodiment>
FIG. 1 is a block diagram showing the configuration of a light concentration network system according to a first embodiment of the present invention. However, in the light concentration network system (system) 10A shown in FIG. 1, the portions corresponding to those of the conventional system 10 shown in FIG.

  In the system 10A of the first embodiment shown in FIG. 1, as in the conventional system 10, the representative node 11A and the plurality of nodes 12A, 13A, and 14A are the first as two physically independent signal transmission paths. The optical fiber 16 and the second optical fiber 17 are connected in a ring shape. The ring-shaped optical fibers 16 and 17 can transmit data in directions different from each other, such as clockwise and counterclockwise directions indicated by arrows. Therefore, the clockwise direction and the counterclockwise direction indicated by the arrows in each of the optical fibers 16 and 17 may be the opposite direction. However, the optical fibers 16 and 17 can also perform data transmission in the same rotation direction.

  The first embodiment is characterized in that a representative node 11A and a plurality of nodes 12A to 14A connected in a ring shape with two optical fibers 16 and 17 include a start node (for example 12A) and an end node (for example 14A) Between ONUs, three paths to be folded back at the OLT 21A are set as follows. That is, a total of three paths: a current-use OLT return path (active path) indicated by arrow Y11, a spare OLT return path (backup path) indicated by arrow Y12, and a redundant OLT return path (redundant path) indicated by arrow Y13. And transmit data from the start point to the end point through each path Y11 to Y13 to realize communication between ONUs. As a result, as will be described in detail later, with the same amount of equipment as before, high reliability equivalent to 1 + 1 protection without increasing the delay due to the addition of a special device and electrical processing for each node. It is possible to perform communication between ONUs. The OLT 21A is a control entity, and the ONU is an object for the control entity.

  However, for example, in the case of the current path Y11, the turning back at the OLT 21A is performed so that the OSU 26Aa of the OLT 21A enters the SW unit 25 and is turned back here to enter the OSU 26Aa again. In such a return path, the transmission direction of data transmitted from the ONUs of the nodes 12A to 14A to the OLT 21A is defined as the upstream direction, and conversely, the transmission direction of data transmitted from the OLT 21A to the ONU is defined as the downstream direction.

  The representative node 11A includes a plurality of IO units 20a to 20n, an OLT 21A, and optical demultiplexing units 23a and 23b. The OLT 21A includes an SW unit 25, a plurality of OSUs 26Aa and 26Ab, and a DWBA function unit 27A. Each of the OSUs 26Aa and 26Ab has the same configuration, and includes an OAM (Operations, Administration, Maintenance) function unit 51 and a buffer unit 52, as typified by the OSU 26Aa. The DWBA function unit 27A is connected to the SW unit 25 via the IF (interface) 53, and is also connected to the OSUs 26Aa and 26Ab. Furthermore, the DWBA function unit 27 is connected to an OpS (operation system) 56 outside the representative node 11A via the IF 54.

  In representative node 11A, as described in the background art, the plurality of IO units 20a to 20n are connected to the plurality of host computers (hosts) 41a to 41n as external devices in a one-to-one relationship with hosts 43a to 43n. It is SNI-LT which performs signal transmission and reception. These IO units 20a to 20n terminate the client signals transmitted from the hosts 41a to 41n and transmit them to the SW unit 25, and convert the light burst data from the SW unit 25 into client signals to be a host Send to 41a-41n.

  A plurality of external hosts 42a to 42n, 43a to 43n, and 44a to 44n are connected to the respective IO units 34Aa to 34An (FIG. 2) of the nodes 12A to 14A on a one-to-one basis.

  As described above, the SW unit 25 of the representative node 11 transmits packet data from the OSU 26Aa to the host (for example, 41a) of the destination by the MAC address according to the correspondence table between the MAC address and the port set in advance. Transfer through.

  The OSUs 26Aa and 26Ab receive the light burst data from the ONUs of the nodes 12A to 14A and output the light burst data to the SW unit 25, receive the packet data from the SW unit 25, and transmit the optical data to the ONU. In this configuration, the PON section is between the OSU 26Aa, 26Ab and the ONU.

  The DWBA function unit 27A has the function of dynamic wavelength band allocation described in the background art, and sets three paths of the working path Y11, the protection path Y12 and the redundant path Y13 between the start point and the end point of data transmission. Perform path setting control. The path setting control may be performed by the OpS 56 by linking the external OpS 56 operating the system 10A with the DWBA function unit 27A. In OpS 56, it is also possible for a person to perform path setting control arbitrarily. The three paths are indicated by arrows Y11 to Y13, but data can also be transmitted in the reverse direction from node 14A to 12A. The DWBA function unit 27A or OpS 56 constitutes a path setting control unit described in the claims.

  In path setting control, three paths Y11 to Y13 for working, protection, and redundancy are described in the four paths (described later) between the OLT 21A and the ONUs connected via two optical fibers 16 and 17 as described later. Set to The four paths are, for example, two upstream paths transmitting between the ONU of the node 12A and the OLT 21 via the two optical fibers 16 and 17 in opposite directions, and two ONUs of the OLT 21A and the node 14A. This is due to the combination of two downstream routes which transmit 16, 17 in opposite directions.

  The DWBA function unit 27A sets two independent paths Y11 and Y13 in an upstream path from the ONU at the start point (node 12A) to the OLT 21A via the first optical fiber 16 by path setting control, and this setting is performed. The remaining one path Y12 is set in the upstream path through the second optical fiber 17 which performs data transmission in the direction opposite to the path. Furthermore, two paths Y11 and Y12 different from the upstream pair are set in the downstream path toward the ONU of the end point (node 14A) via the first optical fiber 16 by folding back at the OLT 21A, and The remaining one path Y13 is set in the path through the second optical fiber 17.

  In other words, when performing setting control of the three paths Y11 to Y13, the DWBA function unit 27A moves from the ONU at the start point of data to the ONU-OLT toward the OLT 21A via the two optical fibers 16 and 17 in the opposite direction. And two paths Y11 and Y13 of the three paths Y11 to Y13 between the OLT-ONU going to the ONU at the end point through the two optical fibers 16 and 17 in the opposite direction and the data folded back at the OLT 21A. Control is performed so that one optical fiber 16 side is set, and the remaining one path Y12 is set to the other optical fiber 17.

  By setting the three paths Y11 to Y13 in this manner, data transmission can be performed on the other optical fiber 17 even if a failure occurs in one of the optical fibers 16 in each of the upstream and downstream paths. It has become.

  Next, the configuration of the nodes 12A to 14A transmitting data to such three paths Y11 to Y13 will be described. Each of the nodes 12A to 14A has the same configuration, and is shown in FIGS. 2 and 3 as a representative of the nodes 12A and 14A. The node 12A shown in FIG. 2 includes a plurality of optical demultiplexing units 31a and 31b, a plurality of ONUs 32Aa and 32Ab, a SW unit 33 having ports 1a, 1b, 1c and 1d, and a plurality of IO units 34Aa to 34An. It is configured to be equipped. Each of the ONUs 32Aa and 32Ab includes an OAM function unit 61 and a buffer unit 62 as represented by the ONU 32Aa. The ports 1a to 1d connect the ONUs 32Aa and 32Ab to the IO units 34Aa to 34An.

  Each of the IO units 34Aa to 34An includes a client signal termination conversion unit (termination conversion unit) 65, a copy unit 66, a selection unit 67, and a TRX (transceiver) 2b, as representatively shown in the IO unit 34Aa. Is configured. The TRX 2 b is connected to the TRX 2 a of the host 42 a via a network, and transmits and receives signals to and from the TRX 2 a.

  The termination conversion unit 65 terminates the client signal transmitted from the host 42a via the TRX 2a, 2b, and outputs this to the copy unit 66 as client data D1. Further, as shown in FIG. 3, the termination conversion unit 65 receives the client data D1s which is input from the ONUs 32a and 32b to the selection unit 67 via the SW unit 33, converts the client data D1s selected by the selection unit 67 into a client signal and converts it into TRX2b. Output. Optical burst data is also simply referred to as data.

  Returning to FIG. 2, the copying unit 66 copies the data D1 input from the termination conversion unit 65 into three data indicated by reference numerals D11, D12, and D13, and switches the copied three data D11 to D13. Output to section 33. At this time, the copy unit 66 applies labeling to the three data D11 to D13 to instruct passing through predetermined paths Y11 to Y13, and outputs the data to the SW unit 33. The SW unit 33 transmits the three data D11 to D13 to the three paths Y11 to Y13 described above via the ONUs 32Aa and 32Ab.

  Here, a more detailed copy processing example will be described. First, the host 42a or the end conversion unit 65 gives the data D1 a label to be described later for return communication in the OLT 21A, and the copy unit 66 determines the copy and transmission path based on the label. At this time, the copying unit 66 performs copying and label rewriting or capsulering, which will be described later, on the data D1 to which a label for return communication is added, and the same sequence number is applied to the processed data D11 to D13. It gives and outputs to SW section 25.

  The labels described above are VLAN (Virtual Local Area Network) tags, MPLS (Multi Protocol Label Switching) labels, and the like. Further, label rewriting is performed, for example, by rewriting the label A attached to the data D1 by the host 42a or the termination conversion unit 65 to labels A11, A12, and A13 for attaching the copied data D11, D12, and D13. is there. The encapsulation is to put the label A of the data D1 in the label B to be a label BA, and to assign the label BA to the data D11 after copying. Similarly, label A is put in label C to be label CA, this label CA is added to data D12 after copying, label A is put in label D to be label DA, and data DA after copying this label DA It is to give to D13.

  Next, as shown in FIG. 3, the selection unit 67 selects one of the three data D11 to D13 transmitted through the three paths Y11 to Y13, and selects the selected one data D1 s. Input to the termination conversion unit 65. The end conversion unit 65 converts the input data D1s into a client signal and outputs the client signal to the TRX 2b. The output client signal is transmitted and received between the TRXs 2b and 2a and processed by the host 44a. However, in FIGS. 2 and 3, although the aspect in which data is transmitted from node 12A to node 14A is described by arrows D11 to D13, data transmission can be performed in the opposite direction by setting a path in the opposite direction. It is.

  When the selection unit 67 performs the above-described selection, the selection unit 67 determines whether the data is copied data by the copying unit 66, and in the case of copied data D11 to D13, the first-come And so on to select only one data (for example, D11) and input it to the termination conversion unit 65.

  Among the data D11 to D13 to which the same sequence number n as the sequence number n held by the selection unit 67 is given, the first arrival priority process inputs to the termination conversion unit 65 the data (for example, D11) that arrives earliest. The data D12 and D13 of the same sequence number n as the second arrival are discarded. Thereafter, the selection unit 67 updates the held sequence number to n + 1.

  In the late arrival waiting process, all the data D11 to D13 to which the same sequence number n as the sequence number n held by the selection unit 67 is given arrive, or the earliest data (for example, D11) arrives. After a predetermined time has elapsed, the data (for example, D11) with the youngest label among the arrival data at the current point is input to the termination conversion unit 65. Thereafter, the selection unit 67 updates the held sequence number to n + 1. The termination conversion unit 65 rewrites the label of the input data D11 to the original label. Alternatively, after decapsulating to obtain the original data D11, this data D11 (D1s) is transmitted to the host 44a.

  By the way, when setting up the above-mentioned three paths Y11 to Y13, the DWBA function unit 27A shown in FIG. 1 avoids the path with a large load of data transmission of four paths and sets the path with a small load. You may The load is traffic volume or delay information, and the traffic volume is detected by the DWBA function unit 27A. The operator can confirm this detected traffic volume at OpS 56. In addition, since the delay also increases when the traffic volume is large, delay information according to the relationship between the traffic volume and the delay may be used as the load information.

  The delay information can be measured as described later by the ONUs 32Aa and 32Ab shown in FIGS. 2 and 3 and the OAM function unit 51 provided in the OSUs 26Aa and 26Ab of the representative node 11A shown in FIG. However, the ONUs 32Aa and 32Ab also include a buffer unit 52, similarly to the OSUs 26Aa and 26Ab.

  The OAM function unit 51 is a function for performing operation, management, and maintenance of the network, and in the case of Ethernet (registered trademark), from the performance information of the network acquired by flowing Ethernet OAM information (OAM frame) through the route. The delay is detected, and the detected delay is transmitted to the DWBA function unit 27A. However, the performance information is standardized by the ITU-T (International Telecommunication Union Telecommunication Standardization Division) as the international recommendation "Y. 1731". The OAM function unit 51 regularly measures the delay time of each path using the standardized performance information such as performance measurement as it is. This delay time can be measured as, for example, 1 second, 2 seconds, and 3 seconds, and the DWBA function unit 27A selects a path in the order of smaller delay time among the measured values.

  Alternatively, the DWBA function unit 27A recognizes the buffer information (queue information) of the buffer unit 52 deployed as described above in the network, and the path having a short buffer length (queue length), in other words, the amount of buffer is small and low. It is also possible to select a load path. As described above, the DWBA function unit 27A obtains the buffer information of the buffer unit 52 to newly add the buffer information of the downlink direction in addition to the buffer information of the uplink direction defined in the above-mentioned Non-Patent Document 2 and the like. By combining the above, it is possible to set up a flexible path across uplink and downlink paths. In the existing PON, the DWBA function unit manages only the amount of upstream buffer from the ONU.

  In the PON, the ONUs 32Aa and 32Ab can transmit the amount of information (the amount of data) accumulated in the buffer unit 52 that buffers (holds) data in the upstream direction to the OLT 21A. Also, the buffer unit 52 of the OSU 26Aa, 26Ab buffers data in the downlink direction. The buffer unit 52 transmits the buffer amount to the DWBA function unit 27A of the OLT 21A.

  Therefore, the DWBA function unit 27A in the OLT 21A detects how much the amount of information is accumulated in each buffer unit 52 for each path, in other words, detects a delay amount according to the buffer amount for each path. You can select a low load path.

Here, one configuration example of the ONU 32Aa (32Ab) for transmitting the queue information (buffer information) necessary for selecting the low load path to the DWBA function unit 27A is shown in FIG. 4 and will be described.
As shown in FIG. 4, the ONU 32Aa is connected to the SW unit 33 through the queue units 52a and 52b as the OAM function unit 51 and the buffer unit 52 (see FIG. 2 or 3) and the ports 1e, 1b and 1c. Client PHY unit (processing function unit of layer 1 for performing encoding / decoding, etc.) 71, classifier unit 72, queue reading units 73 and 74, queue monitoring unit 75, packet monitoring unit 76, notification Signal generation units 77a and 77b, monitor signal generation instruction setting unit 78, data MUX (multiplexer) unit 79, PON PHY data separation unit (separation unit) 80, transmission instruction information queue unit 81, transmission unit 82, And a receiver unit 83. The data MUX unit 79 is also referred to as the MUX unit 79.

  Characteristic elements of this configuration are a classifier unit 72, a packet monitoring unit 76, and a MUX unit 79. The classifier unit 72 determines by identification whether the data D11 or D13 received from the host 42a shown in FIG. 2 is an OLT return target signal or not, and the signal of an OLT return target signal or a signal not for an OLT return target of the queue unit 52a. Store in a predetermined storage unit. The stored data is monitored by the queue monitor unit 75, and the queue monitor unit 73 monitors the stored data and the like, and is read by the queue reading unit 73 and input to the MUX unit 79.

  The MUX unit 79 receives the normal data input thereto, uplink queue information, downlink queue information, delay information which are notification signals generated by the notification signal generation units 77a and 77b described later, and an OAM function unit 51 described later. Multiplex OAM related information from The multiplexed data signal is uplink data to be transmitted from the transmission unit 82 via the separation unit 80 to the OLT 21A (FIG. 1) via the optical demultiplexing unit 31a or 31b.

  On the other hand, the data returned by the OLT 21 A is received by the receiving unit 83 via the optical demultiplexing unit 31 a or 31 b, and is input to the separating unit 80. The separation unit 80 separates the OAM frame from the input data and outputs the OAM frame to the OAM function unit 51. The OAM function unit 51 detects the delay of the transmission path to the OLT 21A from the OAM frame, and outputs the detected delay information to the MUX unit 79, and finally to the DWBA function unit 27A (FIG. 1). Tell. Further, the separation unit 80 outputs the transmission / reception control signal input to the separation unit 80 to the transmission instruction information queue unit 81. Transmission instruction information queue unit 81 instructs reading by queue reading unit 73 and data transmission by transmission unit 82 in accordance with the transmission / reception control signal.

  Also, after the downlink data separated by the separation unit 80 is stored in the queue unit 52b, it is read out by the queue reading unit 74 and finally from the client PHY unit 71 through the SW unit 33 (for example, as shown in FIG. It is output to 3 of 44a). At this time, the downlink data stored in the queue unit 52 b is monitored by the packet monitor unit 76. The monitor unit 76 monitors the queue state of the downlink data stored in the queue unit 52b, and averages the downlink queue length (buffer length), maximum queue length (maximum buffer length), packet processing delay information, queue overflow amount, etc. Are obtained according to the instruction of the monitor signal generation instruction setting unit 78, and are input to the notification signal generation unit 77b.

  The notification signal creation unit 77 b creates a notification signal according to the input information from the packet monitor unit 76 and the instruction information of the monitor signal creation instruction setting unit 78, and inputs the notification signal to the MUX unit 79. The notification signal creation unit 77 a creates a notification signal according to the input information from the queue monitor unit 75 described above and the instruction information from the monitor signal creation instruction setting unit 78 and inputs it to the MUX unit 79.

  In addition, the DWBA function unit 27A illustrated in FIG. 1 can perform dynamic band allocation control also in the communication between ONUs as follows. That is, in general OLT-ONU communication, a bandwidth is dynamically allocated to each ONU in order to perform efficient communication by PON-DBA (dynamic band allocation). In other words, when performing communication between ONUs through the OLT 21A, the wavelength is dynamically switched and the bandwidth is allocated so that the total bandwidth obtained by integrating a plurality of wavelengths can be distributed to the predetermined bandwidth for each ONU. is there.

  This dynamic band allocation can also be realized by performing DWBA (Dynamic Wavelength Band Allocation) or DBA including traffic of a path that is looped back at the OLT 21A as in this embodiment. Therefore, the wavelength and band can be dynamically and flexibly allocated by the DWBA function unit 27A performing dynamic band allocation by DWBA or DBA in inter-ONU communication by return of the OLT 21A.

  Further, in the OLT 21A, the DWBA function unit 27A is connected to the SW unit 25 via the IF 53. With this connection, the DWBA function unit 27A exchanges control signals with the SW unit 25 to cooperate with each other, and controls data transmission of each path Y11 to Y13 between ONUs. In this control, not only OLT-ONU communication, but also inter-ONU communication, control of shaping for suppressing the communication amount to a certain level, control of concentrating data transmission on a certain path, and the like are possible.

<Effect of First Embodiment>
The features of the first embodiment described above and the effects thereof will be described mainly with reference to FIG.
(1) The representative node 11A includes the DWBA function unit 27A that performs control to set three independent logical paths Y11 to Y13 in the path between the ONUs via the OLT 21A. When setting and controlling three paths Y11 to Y13, the DWBA function unit 27A at least two paths between the ONU and the OLT 21A, in which data travels from the ONU via the two optical fibers 16 and 17 in the opposite direction to the OLT 21A. And three different paths out of at least two of the four paths combining the OLT 21A and at least two paths between the ONUs and data folded back at the OLT 21A toward the ONU via the two optical fibers 16 and 17 in opposite directions Control was performed to set Y11 to Y13.

  By this, the following effects can be obtained. That is, at least four paths exist between the ONU and the OLT 21A and between the OLT 21A and the ONU, since they are transmittable in opposite directions by two ring-shaped optical fibers 16 and 17. Three independent paths Y11 to Y13 are set to three different paths among the four paths, and the same data is transmitted to the set three paths Y11 to Y13. Thus, data can be transmitted through the other optical fiber 17 even if a failure occurs in one of the optical fibers 16 between the ONUs returning at the OLT 21A at the start point and the end point of the data transmission. Therefore, highly reliable inter-ON communication equivalent to 1 + 1 protection can be performed without adding a special device or increasing delay.

  (2) The path setting control means (to be described later) sets three paths in the order of less delay from each path in which data transmission is performed in opposite directions by two optical fibers 16 and 17 between ONU and OLT 21A and between OLT 21A and ONU. Added control to set the path.

  As a result, since data transmission is performed by setting three paths in order of paths with less delay, high-speed transmission with less delay can be performed.

  The following three examples (2-1) to (2-3) can be given as examples of performing control to set three paths in order of paths with less delay from each path.

  (2-1) The amount of traffic of each path in which data transmission is performed in opposite directions by the two optical fibers 16 and 17 between the ONU and the OLT 21A and between the OLT 21A and the ONU as the DWBA function unit 27A as path setting control means And control to set three paths in the order of the path with the small amount of detected traffic.

  As a result, since data transmission is performed by setting three paths in order of paths with a small amount of traffic, high-speed transmission with less delay can be performed.

  (2-2) An OAM function unit as path setting control means for obtaining the delay information of a plurality of paths by flowing an OAM frame (OAM information) for measuring the performance of the transmission path to a plurality of paths in the ONU and OLT 21A. 51 is provided. The OAM function unit 51 flows the OAM frame to each path in which data transmission is performed in the opposite direction with two optical fibers 16 and 17 between the ONU and the OLT 21A and between the OLT 21A and the ONU, and acquires delay information of each path. Thus, control is performed to set three paths Y11 to Y13 in order of paths with less delay.

  As a result, since data transmission is performed by setting three paths in order of paths with less delay, high speed transmission can be performed.

  (2-3) A buffer unit for holding data to be transmitted to each path in which data transmission is performed in the opposite direction by the two optical fibers 16 and 17 between the ONU and the OLT 21A and between the ONU and the OLT 21A and between the OLT 21A and the ONU 52 is provided. The DWBA function unit 27A as path setting control means acquires the amount of data held in the buffer unit 52, and performs control to set three paths in the order of the path in which the buffer unit 52 having a small amount of acquired data intervenes .

  As a result, data to be transmitted to each path is held, and three paths are set in the order of paths through which the buffer unit 52 with a small amount of held data intervenes, thereby performing high-speed transmission.

  (3) When performing communication between ONUs through the OLT 21A, the DWBA function unit 27A dynamically switches wavelengths so that the total bandwidth obtained by integrating a plurality of wavelengths for each ONU can be distributed to a predetermined bandwidth. Control to allocate bandwidth.

  Thus, in the inter-ONU communication based on the return of the OLT 21A, the wavelength and the band can be dynamically and flexibly allocated by performing dynamic band allocation, and efficient communication can be realized.

  Next, an optical transmission method will be described. In this method, a representative node 11A having an OLT 21A as an optical line termination device serving as a control subject, which terminates signals transmitted to and received from an external device (host), and an optical line termination serving as an object relative to the control subject A plurality of nodes 11A to 14A having an ONU as a device are connected in a ring shape by at least two optical fibers 16 and 17, and when the same data passes through the two optical fibers 16 and 17, one of them is The optical transmission apparatus 11A used as the representative node 11A or the nodes 12A to 14A is included in a network that is returned from the ONU 1 to the OLT 21A and transmitted to the other ONU.

  The optical transmission apparatus 11A performs the control of setting three independent logical paths in the path between ONUs via the OLT 21A, and the control of setting the optical transmission apparatus, the light is transmitted from the ONU 2 data At least two paths between the ONU and the OLT 21A going to the OLT 21A through the fibers 16 and 17 in opposite directions, and data folded back at the OLT 21A are the OLT 21A and ONU going to the ONU through two optical fibers 16 and 17 in the opposite direction. Performing control to set three paths Y11 to Y13 in three different ones of at least four paths in which at least two paths between them are combined.

  According to this method, data can be transmitted through the other optical fiber 17 even if a failure occurs in one of the optical fibers 16 between the ONUs returning at the OLT 21A at the start point and the end point of the data transmission. . Therefore, highly reliable inter-ON communication equivalent to 1 + 1 protection can be performed without adding a special device or increasing delay.

  In addition, a program for executing the computer of the present embodiment will be described. The computer terminates a signal transmitted / received to / from an external device (host), and a representative node 11A having an OLT 21A as an optical line termination device serving as a control subject, and an optical line termination device serving as an object to the control subject And a plurality of nodes 11A to 14A having an ONU as a ring connected by at least two optical fibers 16 and 17, and when the same data passes through the two optical fibers 16 and 17, one of the nodes 11A to 14A is connected. It is assumed that the optical transmission apparatus is used as the representative node 11A or the nodes 12A to 14A in a network which is returned from the ONU by the OLT 21A and transmitted to the other ONU.

  This program controls the computer to set three independent logical paths on the path between ONUs via the OLT 21A, and when the control of the setting is performed, two optical signals from ONU are used. At least two paths between the ONU and the OLT 21A going to the OLT 21A through the fibers 16 and 17 in opposite directions, and data folded back at the OLT 21A are the OLT 21A and ONU going to the ONU through two optical fibers 16 and 17 in the opposite direction. Function as a means for performing control to set three paths Y11 to Y13 in three different paths among at least four paths in which at least two paths between them are combined.

  According to this program, between the ONU and the OLT 21A, and between the OLT 21A and the ONU, at least four paths can be transmitted since they can be transmitted in opposite directions by two ring-shaped optical fibers 16 and 17 respectively. Exists. Three independent paths Y11 to Y13 are set to three different paths among the four paths, and the same data is transmitted to the set three paths Y11 to Y13. Thus, data can be transmitted through the other optical fiber 17 even if a failure occurs in one of the optical fibers 16 between the ONUs returning at the OLT 21A at the start point and the end point of the data transmission.

<Configuration of Second Embodiment>
FIG. 5 is a block diagram showing the configuration of a light concentration network system according to a second embodiment of the present invention. However, in the light concentration network system 10B shown in FIG. 5, the portions corresponding to the system 10A of the first embodiment shown in FIG.

  The system 10B of the second embodiment shown in FIG. 5 differs from the system 10A of the first embodiment in that a representative node 11B and a plurality of nodes 12B-14B connected in a ring shape with two optical fibers 16 and 17 Among them, between the ONUs of the start point node (for example 12B) and the end point node (for example 14B), two paths Y11 and Y12 in the upstream path between the ONU and OLT 21B, and the path return point (IO unit 20Ba) and ONU The point is that three paths Y11, Y12, and Y13B are set in the downward route between them. However, although the IO unit 20Ba at the turning point is described outside the OLT 21B in FIG. 5, it may be included in cooperation with the OLT 21B, and may be in the OLT 21B.

  The setting of the two upstream paths Y11 and Y12 and the three downstream paths Y11, Y12 and Y13B is performed by path setting control described later by the DWBA function unit 27B. That is, the DWBA function unit 27 sets two paths, the working path Y11 and the protection path Y12, in the upstream path between the start point node 12B and the OLT 21B. Furthermore, the current path Y11 is branched into two at the turning point of the OLT 21B, and one of the two branches is set as the redundant path Y13B, and this is added to the working path Y11 and the protection path Y12 from the turning point of the OLT 21B. The downstream path between ONUs of the end point node 14B is set.

  In the path setting control, as in the first embodiment, a person can arbitrarily perform path setting control in OpS 56. The DWBA function unit 27B or the OpS 56 constitutes path setting control means described in the claims.

  In detail, the DWBA function unit 27B sets one independent current path Y11 in an upstream path from the ONU at the start point (node 12B) to the OLT 21B via the first optical fiber 16 by the path setting control. The other protection path Y12 is set as an upward path through the second optical fiber 17 that performs data transmission in the direction opposite to the set path. Furthermore, the working path Y11 is branched into two at the turning point of the OLT 21B, one of the two branches being the redundant path Y13B, the working path Y11 passing from the turning point through the second optical fiber 17, and the first optical fiber from the turning point The three paths added to the protection path Y12 via 16 are set as the downstream path from the turning point of the OLT 21B to the ONU of the end point node 14B.

  As described above, two paths are set up in the upstream path through the first and second optical fibers 16 and 17 between the ONU and the OLT 21B in opposite directions, and one of the paths is branched at the turning point of the OLT 21B. From the turnaround point, three paths are set in the downward path through the first and second optical fibers 16 and 17 in the opposite direction between the ONUs. As a result, in each of the upstream and downstream paths, even if a failure occurs in one of the optical fibers 16 in the transmission disabled state, data transmission is possible on the other optical fiber 17.

  Next, the configuration of representative node 11B for transmitting data to such three paths Y11, Y12, and Y13B will be described with reference to FIG. The representative node 11B illustrated in FIG. 6 includes a plurality of optical demultiplexing units 23a and 23b, a plurality of OSUs 26Ba to 26Bd, an SW unit 25 having ports 3a to 3h, and a plurality of IO units 20Ba to 20Bd. It is done. In this case, it is assumed that the OLT 21B is configured by including the OSUs 26Ba to 26Bd, the SW unit 25 and the IO units 20Ba to 20Bd.

  Each of the IO units 20Ba to 20BAd, as typified by the IO unit 20Ba, includes a client signal terminal conversion unit (terminal conversion unit) 91, an MUX unit 92, a copy unit 93, a filter unit 94, and a load monitor unit. (Monitoring unit) 95 and the TRX 4 b are configured. The TRX 4 b is connected to the TRX 4 a of the host 41 a via a network, and transmits and receives signals to and from the TRX 4 a.

The termination conversion unit 91 terminates the client signal transmitted from the host 41 a via the TRX 4 a and 4 b, and outputs this to the MUX unit 92.
The filter unit 94 determines, for example, whether the data (signal) D11 transmitted from the node 12B shown in FIG. 7 and passed through the uplink route is a copy target or not. The data is separated and output to the copy unit 93. Here, although the node B12 shown in FIG. 7 has the same configuration as the IO unit 34Aa shown in FIG. 2, the copy unit 66B has a function of copying the data D1 into two data D11 and D12.

  Referring back to FIG. 6, the filter unit 94 outputs the data D11 transmitted via the uplink route to the termination conversion unit 91 when the data D11 is not a copy target. If the end conversion unit 91 determines that the data D11 not to be copied is not uplink target data at the turnaround point but normal uplink data, the end conversion unit 65 transmits the data D11 as it is to the host 41a via the TRX 4b. Ru. When it is determined that the data D11 not to be copied is data to be turned back, the data D11 is folded back to the downstream path (the second optical fiber 17 side) via the MUX unit 92.

  The copying unit 93 copies the data D11 to be copied into two data D11 and D13, and outputs the two copied data D11 and D13 to the SW unit 25. At this time, the copy unit 93 applies labeling to the two data D11 and D13 to instruct passing through the predetermined paths Y11 and Y13B, and outputs the data to the SW unit 25. The SW unit 25 transmits the two data D11 and D13 to the two downstream paths Y11 and Y13B described above.

  The load monitoring unit 95 acquires data from the termination conversion unit 91 and the filter unit 94, monitors the load amount of the IO unit 20Ba, and obtains information (load information) of the monitoring load amount as the DWBA function unit 27B (FIG. 5). Output to The monitoring load amount is the sum of the load amount of the downstream communication from the normal OLT 21B to the ONU 32Bb and the load amount for the data branching and return processing in the OLT 21B.

  When the load amount of the IO unit 20Ba increases, congestion may occur with communication data for branching and return processing in the OLT 21B in addition to the downstream communication data from the normal OLT 21B to the ONU 32Bb. Therefore, the following processing is performed when the load amount increases to a predetermined load amount or more (referred to as a dangerous load amount) so that the congestion does not occur. The dangerous load amount is a first load amount described in the claims.

  That is, when the load amount monitored by the load monitor unit 95 becomes a dangerous load amount, the DWBA function unit 27B sets up two upstream and three downstream paths according to the second embodiment (first path). The switching control is performed to switch the setting (setting) to the setting (second path setting) of the three paths Y11 to Y13 described in the first embodiment. When switching to the second path setting, the data D1 is copied to three data D11 to D13 by the IO units 34Aa (see FIG. 2) of the nodes 12B to 14B as described in the first embodiment, Control to transmit to three paths Y11 to Y13 is performed. When processing is performed in this manner, the system 10B of the second embodiment is configured to have the configuration function of the system 10A of the first embodiment as well.

  In addition, when the load amount according to the load information from the load monitoring unit 95 falls to a predetermined load amount or less (referred to as a safety load amount), the DWBA function unit 27B sets the current second path setting to the first Perform switching control to switch to path setting. The safety load amount is a load amount at which the above congestion does not occur. The safety load amount is a second load amount described in the claims. When switching to the first path setting, as described above, the data D11 of the current path Y11 is copied at the turning point of the OLT 21B, and the two data D11 and D13 are downstream paths of the current path Y11 and the redundant path Y13B. Transmitted to At this time, the protection path Y12 is also folded back and transmitted to the downstream path.

  In addition, during operation in the first path setting, when the load amount from the load monitor unit 95 exceeds the dangerous load amount, the switching unit (not shown) of the OLT 21B sets the second path to the DWBA function unit 27B. The switching signal may be output, and the DWBA function unit 27B may perform control to switch from the first path setting to the second path setting. After that, when the safety load amount is less than the above, the switching unit outputs a switching signal from the second to the first path setting to the DWBA function unit 27B, and the DWBA function unit 27B sets the first path to the second path setting. Control to switch to

  Further, when the dangerous load amount or more or the safety load amount or less, the switching unit outputs an alarm signal to the external OpS 56, and the OpS 56 switches the second path setting or the first path setting to the DWBA function unit 27B. A signal may be output and the DWBA function unit 27B may switch paths. When an alarm signal is output to the above OpS 56, the alarm may be transmitted to the maintenance person, and the maintenance person may perform the switching operation.

<Effect of Second Embodiment>
The features of the second embodiment described above and the effects thereof will be described with reference to FIG.
(1) The OLT 21B includes the DWBA function unit 27B, the copy unit 93 (FIG. 6), and the MUX unit 92 (FIG. 6) which is the multiplexer unit 92. The DWBA function unit 27B sets two paths Y11 and Y12 in the upstream path from the ONU to the OLT 21B via the two optical fibers 16 and 17 in the path between the ONUs via the OLT 21B. Furthermore, one of the two paths Y11 and Y12 is branched into two at a turning point at the OLT 21B, and three paths Y11 and Y12 are obtained by adding the other Y12 of the two paths to the bifurcated paths Y11 and Y13B. , Y 13 B are controlled to be set as the downstream path from the turning point of the OLT 21 B to the ONU via the two optical fibers 16 and 17. The copying unit 93 copies one data D11 of the two data D11 and D12 passed through the two paths Y11 and Y12 of the uplink route into two data D11 and D13. The MUX unit 92 transmits the two copied data D11 and D13 to the paths Y11 and Y13B branched into two at the turning point.

  According to this configuration, in the upstream and downstream paths through the two optical fibers 16 and 17 between the ONUs that turn back at the OLT 21 B at the start point and the end point of the data transmission, the failure to transmit to one of the optical fibers 16 occurs Data can be transmitted by the other optical fiber 17 even if Furthermore, since only two set paths Y11 and Y12 are required for the uplink path, the band consumption can be reduced.

  (2) The optical transmission apparatus (representative node 11A, nodes 12A to 14A) of the first embodiment and the optical transmission apparatus (representative node 11B, nodes 12B to 14B) of the second embodiment are provided. The load monitor unit 95 monitors the amount of load obtained by summing the load of the data to be looped back and the load of the data transmitted from the OLT 21B toward the ONU. When the first path setting is made, the DWBA function unit 27B performs the first operation when the load amount monitored by the load monitor unit 95 becomes equal to or more than the dangerous load amount as the first load amount set in advance. Control to switch from path setting to second path setting. In addition, when the load amount monitored by the load monitor unit 95 becomes equal to or less than the predetermined safety load amount as the second load amount when the second path setting is performed, the first path setting is performed. Control to switch is performed.

  By this, the following effects can be obtained. In the first path setting, when the communication load amount increases in the OLT 21B, congestion occurs with communication data for branching and return processing in the OLT 21B in addition to the downstream communication data from the normal OLT 21B to the ONU. there is a possibility. Therefore, the load amount of communication in the OLT 21B is monitored during the first path setting, and the switching control is performed to the second path setting when the monitored load amount is equal to or more than the predetermined dangerous load amount. In this second path setting, as in the first path setting, since there is no branching and return processing in the OLT 21B, the above congestion can be eliminated. In addition, since the switching to the first path setting is performed when the safety load amount is less than or equal to the second path setting, band consumption can be reduced.

  In addition, about a specific structure, it can change suitably in the range which does not deviate from the main point of this invention.

10A, 10B Optical Concentration Network System 11A, 11B Representative Node (First Optical Transmission Device)
12A-14A, 12B-14B (2nd light transmission apparatus)
16, 17 optical fiber (optical transmission line)
21A, 21B OLT
20a to 20n, 20Ba to 20Bn IO parts 23a, 23b, 31a, 31b Optical demultiplexing parts 25 SW parts 26Aa, 26Ab, 26Ba to 26Bd OSU
27A, 27B DWBA function unit (path setting control means)
32Aa, 32Ab ONU
33 SW unit 34Aa to 34An IO unit 41a to 41n, 42a to 42n, 43a to 43n, 44a to 44n host computer (external device)
51 OAM function unit 52 buffer unit 56 OpS (path setting control means)
65, 91 Client signal termination conversion unit 66, 66B, 93 Copy unit 67 Select unit 72 Classifier unit 76 Packet monitor unit 79, 92 MUX unit (multiplexer unit)
94 Filter 95 Load monitor (monitor)

Claims (8)

Terminates signals transmitted and received between the external device, the OLT as an optical line terminal to be controlled mainly (Optical Line Terminal), a plurality of ONU of an optical line terminal comprising the object with respect to the control entity (Optical Network Unit) is connected in a ring shape with at least two optical transmission lines, and when the same data passes through the two optical transmission lines, one of the ONUs is folded back at the OLT and the other is an optical transmission apparatus having the OLT that need use the network to be transmitted to the ONU,
And path setting control means for performing control to set three independent logical paths in the path between the ONUs via the OLT.
When the path setting control means sets and controls the three paths, at least two paths between the ONU and the OLT, in which data is directed from the ONU to the OLT through the two optical transmission paths in opposite directions; The three different routes among at least two of the four combined routes of the OLT and the at least two routes between the ONUs that the data folded back at the OLT is directed to the ONU via the two optical transmission paths in opposite directions An optical transmission device that performs control to set a path. The path setting control means sets the three paths in ascending order of delay from each path where data transmission is performed in opposite directions in the two optical transmission paths between the ONU and the OLT and between the OLT and the ONU. The optical transmission apparatus according to claim 1, wherein the control is performed. The path setting control means dynamically switches wavelengths so that a total band obtained by integrating a plurality of wavelengths for each ONU can be distributed to a predetermined band when performing communication between the ONUs via the OLT. The optical transmission apparatus according to claim 1 or 2, wherein control for allocating a bandwidth is performed. Terminates signals transmitted and received between the external device, and the OLT as an optical line terminal to be controlled mainly a plurality of ONU of an optical line terminal comprising the object with respect to the control entity, at least 2 are connected in a ring shape in the optical transmission line of the present, physicians use the optical transmission path of the two when passing through the same data, the network from one of the ONU are turned back at the OLT are transmitted to the other of the ONU An optical transmission apparatus having the above-mentioned OLT ,
The OLT is
In the path between the ONUs via the OLT, two paths are set in an upstream path from the ONU to the OLT via the two optical transmission paths, and one of the two paths is At the OLT, three branches are branched at a turnaround point and the other of the two paths is added to the two branched paths, and the ONU via the two optical transmission paths from the OLT turnaround point. Path setting control means for performing control to set a downlink route toward
A copy unit that copies one of the two pieces of data sent via the two paths of the upstream path into two pieces of data;
An optical transmission apparatus comprising: a multiplexer unit for transmitting the two copied data to the path branched into two at the turning point. Before SL OLT, a monitor unit for monitoring the load of the data is folded in the OLT, a load which is the sum of the load of the data transmitted towards the relevant OLT to the ONU,
The path setting control means
When prior SL two paths set and the first path setting a Three path to the downlink path to the upstream path is made, the load to be monitored by the monitor unit is a predetermined 1 When the load amount is exceeded, switching is made to the second path setting in which three independent logical paths are set in the path between the ONUs via the OLT, and the second path setting is made. 5. The optical transmission apparatus according to claim 4 , wherein control to switch to the first path setting is performed when the load amount monitored by the monitor unit becomes equal to or less than a predetermined second load amount. . A first optical transmission apparatus having an OLT as an optical line termination apparatus that terminates signals transmitted to and received from an external apparatus, and an ONU as an optical line termination apparatus that becomes an object to the control entity And a plurality of second optical transmission devices each having the first optical transmission device and the second optical transmission device connected in a ring shape, and two optical transmission paths transmitting data in opposite directions to the ring-shaped path An optical concentration network system in which data is returned from one of the ONUs to the OLT and transmitted to the other ONU,
The first optical transmission apparatus includes path setting control means for performing control to set three independent logical paths in a path between the ONUs via the OLT.
When the path setting control means sets and controls the three paths, at least two paths between the ONU and the OLT, in which data is directed from the ONU to the OLT through the two optical transmission paths in opposite directions; The three different routes among at least two of the four combined routes of the OLT and the at least two routes between the ONUs that the data folded back at the OLT is directed to the ONU via the two optical transmission paths in opposite directions A light concentration network system characterized by performing control to set a path. Terminates signals transmitted and received between the external device, and the OLT as an optical line terminal to be controlled mainly a plurality of ONU of an optical line terminal comprising the object with respect to the control entity, at least 2 are connected in a ring shape in the optical transmission line of the present, physicians use the optical transmission path of the two when passing through the same data, the network from one of the ONU are turned back at the OLT are transmitted to the other of the ONU An optical transmission apparatus having the above-mentioned OLT ,
Before Symbol optical transmission equipment,
Performing control to set three independent logical paths in a path between the ONUs via the OLT;
At the time of performing the setting control, at least two paths between the ONU and the OLT that the data travels from the ONU to the OLT via the two optical transmission paths in the opposite direction, and the data folded back by the OLT is the two Performing control to set the three paths in at least three different paths among at least two paths combining the OLT and the at least two paths between the ONUs toward the ONU through the optical transmission path in the opposite direction; ,
An optical transmission method characterized in that: Terminates signals transmitted and received between the external device, and the OLT as an optical line terminal to be controlled mainly a plurality of ONU of an optical line terminal comprising the object with respect to the control entity, at least 2 are connected in a ring shape in the optical transmission line of the present, physicians use the optical transmission path of the two when passing through the same data, the network from one of the ONU are turned back at the OLT are transmitted to the other of the ONU A computer as an optical transmission device having the above-mentioned OLT ,
Wherein the path between the ONU via the OLT, independent logical three rows cormorants means control to set the path,
When the setting control is performed, at least two paths between the ONU and the OLT that the data travels from the ONU to the OLT via the two optical transmission paths in the opposite direction, and the data folded back by the OLT is the two. Means for performing control to set the three paths in at least three different paths among at least two paths combining the OLT and the at least two paths between the ONUs toward the ONU via the optical transmission path in the opposite direction;
Program to function as.

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