WO2013187474A1 - 光ネットワークシステム、光スイッチノード、マスターノードおよびノード - Google Patents
光ネットワークシステム、光スイッチノード、マスターノードおよびノード Download PDFInfo
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Definitions
- the present invention relates to an optical network system, an optical switch node, a master node, and a node.
- Non-patent Document 1 discloses a reconfigurable ROADM (Reconfigurable Optical Add / Drop Multiplexer: wavelength multiplexing apparatus capable of remote wavelength control) as a kind of OADM.
- the OADM serving as the basic configuration will be briefly described.
- FIG. 146 is a block diagram showing a configuration example of a conventional OADM.
- the OADM includes an optical SW (switch) setting unit 501, an optical SW unit 502, a demultiplexing unit 503, a multiplexing unit 504, and transmission / reception units 505-1 to 505-N. .
- FIG. 147 is a diagram illustrating a configuration example of a ring-type optical network system in which the OADMs illustrated in FIG. 146 are connected in a ring shape via a transmission path.
- wavelength ⁇ 1 is assigned to an optical signal transmitted / received between OADM 510A and OADM 510C
- wavelength ⁇ 3 is assigned to an optical signal transmitted / received between OADM 510A and OADM 510D.
- the wavelength ⁇ 2 is assigned to the optical signal transmitted / received between the OADM 510B and the OADM 510C
- the wavelength ⁇ 4 is assigned to the optical signal transmitted / received between the OADM 510B and the OADM 510D. In this way, wavelength paths with different wavelengths are set for each ground.
- FIG. 148 shows the configuration of a conventional metro network.
- a plurality of reconfigurable optical add / drop multiplexers (ROADMs) 530 are provided as nodes in an optical fiber network 531 provided in a ring shape.
- ROADMs reconfigurable optical add / drop multiplexers
- FIG. 149A and FIG. 149B are diagrams for explaining the operation principle of a conventional metro network using such ROADM. For example, paths with different wavelengths ⁇ 1 to ⁇ 3 are set from point A to point C to point D shown in FIG. 149A. At point D, data from points A to C (Data1 to Data4) shown in FIG. 149B are set. Are received asynchronously in time with each other.
- optical ring NW Network
- WDM Time Division Multiplexing
- Non-Patent Document 3 proposes a time slot (TS: Time Slot) exchange method between rings in a WDM / TDM in a multi-ring NW in which a plurality of rings are connected in multiple stages.
- TS Time Slot
- Non-Patent Document 3 by adjusting the fiber length between the rings, at a ring exchange point (a node connecting the rings), a communication time slot for upper ring communication (referred to as a first time slot)
- a communication time slot for upper ring communication referred to as a first time slot
- wavelength paths having different wavelengths are set for each ground, so the number of nodes that can be installed in the ring is limited to the number of wavelengths.
- the number of wavelengths is four from ⁇ 1 to ⁇ 4, and the number of nodes is four as indicated by reference numerals 510A to 510D. That is, in the conventional ring-type optical network, the number of nodes that can be installed is limited by the number of wavelengths.
- the wavelength path is statically set between the ground, so that the bandwidth utilization efficiency is improved.
- the bandwidth utilization efficiency is improved.
- the fiber length varies due to changes in the outside air temperature.
- the ring length fluctuates, the time slot arrival timing at the ring exchange point shifts, and there is a problem that a collision between the first time slot and the second time slot occurs at the ring exchange point.
- a certain node on the ring as a master node is periodically (When the propagation delay time for one round of the ring is not an integral multiple of the time slot with respect to the time slot processing timing operating every t time), the arrival timing of the time slot transmitted from other nodes and the time slot processing at the master node Deviation in timing occurs.
- the present invention has been made in order to solve the above-described problems.
- the present invention makes it possible to increase the number of nodes without depending on the number of wavelengths, and a dynamic bandwidth according to the traffic volume while using the WDM technology.
- an optical network capable of improving the traffic accommodation efficiency as a whole system, and further allowing the master node to process time slots arriving from other nodes and to transfer time slots from other nodes.
- An object is to provide a system, an optical switch node, a master node, and a node.
- an optical network system of the present invention is an optical network system including a master node and a plurality of optical switch nodes, and the master node converts a wavelength path of an arbitrary wavelength into a time slot of a predetermined time.
- the time slot is assigned to each of the optical switch nodes, and each of the optical switch nodes synchronizes the time slot based on information distributed from the master node, and transmits / receives data or routes. It was set as the structure which switches.
- the optical switch node of the present invention is an optical switch node connected to the master node via a transmission line, and has a predetermined time allocated to the master node based on information distributed from the master node.
- the master node of the present invention is a master node connected to a plurality of optical switch nodes via a transmission line, and divides a wavelength path with an arbitrary wavelength into time slots of a predetermined time, and the time slots are divided into the time slots.
- the node of the present invention is a node existing on the ring in a single ring network consisting of a single ring or a multi-ring network consisting of a plurality of rings connected in multiple stages, Is a master node, the time slot control unit for setting the time of each node other than the master node, and when the own node is a node other than the master node, the first time from the time set by the master node
- the reference time slot synchronization unit for ticking the time slot and the own node is the master node, the propagation delay time between the master node and each node other than the master node, and the propagation delay for one round of the ring
- each of the nodes other than the master node A delay measurement unit that calculates an offset value of a fixed node and sets the calculated offset value in the specific node; and when the own node is the specific node, the start timing of the first time slot of the own node is And a plurality of time slot management units that en
- the number of nodes can be increased without depending on the number of wavelengths.
- the time slot allocation and the wavelength allocation in each optical switch node can be changed according to the traffic inflow amount, so that the dynamic band allocation according to the traffic volume between the grounds can be realized, and the system as a whole As a result, the number of wavelengths used and the number of receivers can be reduced as the traffic accommodation efficiency is improved.
- the master node is configured so that each of the nodes other than the master node is based on the propagation delay time between the master node and each node other than the master node and the propagation delay time for one round of the ring.
- the node has a maximum of two types of time slots.
- the lower ring node is synchronized with the reference time slot of the ring switching point node. Directed time slots can be deployed, which can avoid the occurrence of time slot collisions at the ring switching point node.
- the master node when a time slot is deployed, in order to consider the propagation delay time for one round of the ring, in the case of a single ring network, the master node The time slot that has arrived can be processed, and the time slot from another node can be transferred.
- FIG. 2 is a functional block diagram for explaining a configuration of an optical switch node of the optical network system shown in FIG. 1. It is a block diagram which shows one structural example of the optical switch node in 1st Embodiment.
- FIG. 4 is a diagram schematically showing transmission paths for control signals and optical signals in the optical switch node shown in FIG. 3. It is a block diagram which shows one structural example of the master optical switch node in 1st Embodiment. It is a figure which shows typically the transmission path
- FIG. 8 is an image diagram when the trigger output interval of FIG. 7 is “TS length”.
- FIG. 8 is an image diagram when the trigger output interval of FIG. 7 is a “TS cycle”.
- FIG. 8 is an image diagram when the trigger output interval of FIG. 7 is “TS cycle ⁇ N”.
- It is a figure for demonstrating the operation
- It is a figure for demonstrating the operation
- It is a time series diagram for demonstrating the setting method of TS length and TS period with respect to ring length.
- FIG. 1 It is a block diagram which shows one structural example of the optical switch node in 2nd Embodiment. It is a figure which shows typically the transmission path
- FIG. 27 is a diagram schematically illustrating transmission paths of a control signal and an optical signal in the optical switch node illustrated in FIG. 26. It is a block diagram which shows one structural example of the master optical switch node in 3rd Embodiment. It is a figure which shows typically the transmission path
- FIG. 31 is a diagram schematically showing a transmission path of a control signal and an optical signal in the optical switch node shown in FIG. 30. It is a block diagram which shows one structural example of the master optical switch node in 4th Embodiment.
- FIG. 31 is a diagram schematically showing a transmission path of a control signal and an optical signal in the optical switch node shown in FIG. 30. It is a block diagram which shows one structural example of the master optical switch node in 4th Embodiment.
- FIG. 33 is a diagram schematically illustrating transmission paths of a control signal and an optical signal in the master optical switch node illustrated in FIG. 32. It is a figure which shows the variation in the case where time is used with the TS start distribution function / TS synchronization function, and the time counter is set to the time with delay difference. It is a figure for demonstrating the operation
- FIG. 45 is a diagram schematically showing transmission paths for control signals and optical signals in the optical switch node shown in FIG. 44. It is a block diagram which shows one structural example of the master optical switch node in 5th Embodiment.
- FIG. 47 is a diagram schematically showing transmission paths of control signals and optical signals in the master optical switch node shown in FIG. 46. It is a figure which shows the structural example of the optical network system of 5th Embodiment. It is a system diagram for demonstrating TS start time at the time of setting common time. It is a time series diagram for demonstrating TS start time at the time of setting common time.
- FIG. 10 is a diagram showing classified optical TS-SWs applicable in the first to fifth embodiments.
- FIG. 3 is a diagram for explaining the configuration of the optical TS-SW according to the first embodiment.
- FIG. 6 is a diagram for explaining a configuration of an optical TS-SW according to a second embodiment.
- FIG. 10 is a diagram for explaining a configuration of an optical TS-SW according to a third embodiment.
- FIG. 10 is a diagram for explaining a configuration of an optical TS-SW according to a fourth embodiment.
- FIG. 10 is a diagram for explaining a configuration of an optical TS-SW according to a fifth embodiment.
- FIG. 10 is a diagram showing classified optical TS-SWs applicable in the first to fifth embodiments.
- FIG. 3 is a diagram for explaining the configuration of the optical TS-SW according to the first embodiment.
- FIG. 6 is a diagram for explaining a configuration of an optical TS-SW according to a second embodiment.
- FIG. 10 is a diagram for explaining
- FIG. 10 is a diagram for explaining a configuration of an optical TS-SW according to a sixth embodiment.
- FIG. 10 is a diagram showing TWC wavelength requirements of the optical TS-SW of Example 6.
- FIG. 10 is a diagram for explaining a configuration of an optical TS-SW in Example 7.
- FIG. 10 is a diagram showing TWC wavelength requirements of the optical TS-SW of Example 7.
- FIG. 10 is a diagram for explaining a configuration of an optical TS-SW according to an eighth embodiment.
- FIG. 10 is a diagram illustrating a TWC wavelength requirement of an optical TS-SW according to an eighth embodiment. It is a figure which shows the example of 1 structure of optical TS-SW containing TWC and FWC.
- FIG. 10 is a diagram showing TWC wavelength requirements of the optical TS-SW of Example 6.
- FIG. 61 is a block diagram illustrating a configuration example of a TWC illustrated in FIG. 60.
- FIG. 61 is a block diagram illustrating a configuration example of the FWC illustrated in FIG. 60.
- It is a figure which shows the basic composition of a broadcast & select type spatial switch.
- It is a figure which shows the other structural example of a broadcast & select type spatial switch.
- It is a system diagram explaining the outline
- FIG. 3 is a diagram illustrating a ring topology of an optical switch node in the case of a unidirectional ring in a trigger type configuration. It is a figure explaining the ring topology of the optical switch node in the case of the bidirectional
- FIG. 2 is a block diagram showing a basic configuration of an optical TS-SW unit.
- FIG. It is a block diagram which shows the structure of a variable wavelength converter (TWC). It is a block diagram which shows the structure of a fixed wavelength converter (FWC).
- TWC variable wavelength converter
- FWC fixed wavelength converter
- FIG. 3 is a block diagram showing an example of the configuration of an optical TS-SW unit that can be exchanged between a double ring, 1ADD, 1DROP, and fiber and uses a control wavelength.
- FIG. 10 is a block diagram showing another configuration example of an optical TS-SW unit that can exchange between a double ring, 1ADD, 1DROP, and fiber.
- FIG. 3 is a block diagram showing a configuration example of an optical TS-SW unit that enables inter-fiber wavelength switching and intra-fiber wavelength switching without providing an FWC.
- FIG. 3 is a block diagram illustrating a configuration example of an optical TS-SW unit using a control wavelength with a double ring, 1ADD, 1DROP, and 1 AWG per fiber. It is a block diagram which shows the structural example of the optical TS-SW part of the double ring using FWC, and an ADD / DROP1 channel. It is a figure which shows the TWC wavelength requirement of the optical TS-SW part.
- FIG. 3 is a block diagram showing a configuration example of an optical TS-SW unit that enables inter-fiber wavelength switching and intra-fiber wavelength switching without providing an FWC.
- FIG. 3 is a block diagram illustrating a configuration example of an optical TS-SW unit using a control wavelength with a double ring, 1ADD, 1DROP, and 1 AWG per fiber. It is a block diagram which shows the
- FIG. 3 is a block diagram showing a configuration example of an optical TS-SW unit that enables intra-fiber wavelength switching using a double ring using FWC and an ADD / DROP1 channel. It is a figure which shows the TWC wavelength requirement of the optical TS-SW part.
- FIG. 3 is a block diagram showing an example of the configuration of an optical TS-SW unit that enables inter-fiber wavelength switching and intra-fiber wavelength switching using a double ring using FWC and an ADD / DROP 1 channel. It is a figure which shows the TWC wavelength requirement of the optical TS-SW part.
- FIG. 3 is a diagram illustrating a basic configuration of a broadcast and select type optical TS-SW unit.
- FIG. 1 It is a figure which shows another example of a structure of a broadcast and selection type
- time slot (reverse direction) used by the single ring NW It is a figure explaining the time slot (reverse direction) used by the single ring NW. It is a figure explaining the time slot (reverse direction) used by the single ring NW. It is a figure explaining the other example of the time slot (forward direction) used by multiring NW. It is a figure explaining the other example of the time slot (forward direction) used by multiring NW. It is a figure explaining the other example of the time slot (forward direction) used by multiring NW. It is a figure explaining the other example of the time slot (forward direction) used by multiring NW. It is a figure explaining the time slot (reverse direction) used by multi-ring NW. It is a figure explaining the other example of the time slot (reverse direction) used by multi-ring NW.
- FIG. 5 is a system diagram for explaining an operation sequence at the time of transferring a time response of SC in Sub MC. It is a figure explaining the operation
- FIG. 146 is a diagram illustrating a configuration example of a ring-type optical network system in which the OADMs illustrated in FIG. 146 are connected in a ring shape via a transmission line.
- FIG. It is a figure which shows an example of a structure of the conventional metro network. It is a figure which shows the structural example of the optical network by the wavelength division multiplexing which uses ROADM. It is a figure explaining the operation
- FIG. 1 is a diagram showing a configuration example of an optical network system according to an embodiment of the present invention.
- the optical network system has a configuration in which optical switch nodes (hereinafter, optical switch nodes are also simply referred to as “nodes”) 101A to 101D are connected via a transmission path (physical path).
- optical switch node 101A is a master node (optical master node).
- FIG. 1 shows a case where there are four optical switch nodes 101A to 101D, the number of optical switch nodes is not limited to four as long as it is plural.
- the transmission path is also expressed as a ring.
- the optical switch node 101A divides a wavelength path by an arbitrary wavelength ⁇ x into time slots of a fixed time, and assigns the time slots to the optical switch nodes 101B to 101D.
- Each of the optical switch nodes 101B to 101D transmits and receives data in synchronization with a time slot (also referred to as “TS” in the following description) based on information distributed from the optical switch node 101A serving as a master node.
- TS time slot
- FIG. 2 is a functional block diagram for explaining the configuration of the optical switch node of the optical network system shown in FIG.
- the optical switch nodes 101A to 101D include a time slot synchronization unit 151, an optical TS-SW unit (optical time slot switch unit) 152 that is a wavelength switch, the routers 103A to 103D and the optical TS-SW unit 152 shown in FIG. TS transmission / reception unit 153 that transmits / receives data to / from.
- TS-SW is an abbreviation for time slot switch, and so on.
- the time slot synchronization unit 151 divides a wavelength path of an arbitrary wavelength into time slots of a predetermined time, and divides the time slot into the optical switch nodes 101B to 101D. Assign to each of the.
- the optical TS-SW unit 152 of the master node 101A transmits information for performing transmission / reception of data in synchronization with the time slot assigned by the time slot synchronization unit 151 to each of the optical switch nodes 101B to 101D. Delivered to 101B-101D.
- the time slot synchronization unit 151 optically transmits / receives data by synchronizing the time slots of a certain time allocated from the master node 101A based on information distributed from the optical switch node 101A.
- the TS-SW unit 152 is instructed.
- the optical TS-SW units 152 of the optical switch nodes 101B to 101D perform data transmission / reception in accordance with instructions from the time slot synchronization unit 151.
- FIG. 1 shows a state in which the optical switch nodes 101A to 101D hold time slot information indicating instruction contents related to data processing
- the time slot information may be stored in advance in each node.
- the master node 101A may be distributed to the optical switch nodes 101B to 101D.
- the wavelength path is divided into time slots of a fixed time, assigned to each node, and each node performs data transmission / reception and route switching in the assigned time slot.
- Each node in the same wavelength path synchronizes data transmission and route switching so that data does not collide, and data transmission or ADD (insertion) / DROP (branch) can be performed in units of assigned time slots.
- a method for obtaining synchronization there is a method based on a trigger from the master node 101A, and another method is based on time.
- an optical TDM ring system independent of the number of wavelength paths can be realized. Furthermore, it becomes possible to reduce the number of wavelengths and the number of receivers required for each of the nodes 101A to 101D.
- the optical network system of the present embodiment will be specifically described.
- a master node transmits a trigger to each node, thereby obtaining time slot (TS) synchronization of each node. Then, by setting the TS length or TS cycle to 1 / integer of the ring length, the master node can synchronize the timing at which the trigger makes one round with the master node and the timing at which another trigger is output. And periodic data transmission / reception can be realized in a ring network.
- TS time slot
- FIG. 3 is a block diagram showing a configuration example of the optical switch node 1 in the present embodiment.
- FIG. 4 is a diagram schematically showing transmission paths of control signals and optical signals in the optical switch node 1 shown in FIG. A broken line arrow indicates the transmission direction of the control signal, and a solid line arrow indicates the transmission direction of the optical signal.
- a broken line arrow indicates the transmission direction of the control signal
- a solid line arrow indicates the transmission direction of the optical signal.
- the optical switch node 1 includes a TS information management unit 10 that sets TS information, a TS synchronization unit (time slot synchronization unit) 20, an optical TS-SW unit 30, a TS transmission / reception unit 40, Have
- the TS synchronization unit 20 includes a trigger detection unit 21, an optical SW control unit 22, and a transmission control unit 23.
- a demultiplexing unit 31 is connected to the input side of the optical signal, and a multiplexing unit 32 is connected to the output side of the optical signal.
- the TS information management unit 10 has a storage unit (not shown) for storing TS information.
- the TS length or the TS cycle is set to 1 / integer of the ring length.
- the TS information includes instruction contents related to data processing, such as data destination nodes and operation information for the data.
- the operations referred to here include DROP and ADD.
- the trigger detection unit 21 detects a trigger for synchronizing the start timing of the time slot set in each node, and notifies the optical SW control unit 22 and the transmission control unit 23 of the detection result.
- the optical SW control unit 22 counts the elapsed time after receiving the trigger detection notification, refers to the TS information management unit 10, and instructs the optical TS-SW unit 30 to switch in the time slot assigned to itself.
- the optical TS-SW unit 30 switches the route in response to a switching instruction from the optical SW control unit 22.
- the transmission control unit 23 counts the elapsed time after receiving the trigger detection notification, refers to the TS information management unit 10, and instructs the TS transmission / reception unit 40 to transmit data in the time slot assigned to itself.
- the TS transmitting / receiving unit 40 stores data input from the outside in a buffer (not shown), transmits data read from the buffer to the optical TS-SW unit 30 in accordance with an instruction from the transmission control unit 23, and transmits the optical TS. -Send data received from the SW unit 30 to the outside.
- the external is, for example, a communication device such as the router 103A to 103D shown in FIG.
- the demultiplexing unit 31 separates the wavelength of the optical signal input from the outside via the transmission line and outputs the optical signal to the optical TS-SW unit 30.
- the multiplexing unit 32 wavelength-multiplexes the optical signal input from the optical TS-SW unit 30 and outputs it to the outside via a transmission line.
- the demultiplexing unit 31 and the multiplexing unit 32 are not essential components, and instead of providing the demultiplexing unit 31 and the multiplexing unit 32, the number of fibers in the transmission path may be increased.
- a master optical switch node also referred to as a master node
- FIG. 5 is a block diagram showing a configuration example of the master node 2 in the present embodiment.
- FIG. 6 is a diagram schematically showing transmission paths of control signals and optical signals in the master node 2 shown in FIG.
- the master node 2 includes a trigger generation unit 50 that generates a trigger for time slot synchronization and transmits the trigger to each node 1. .
- the trigger generation unit 50 sets any one of “TS length”, “TS period”, and “TS period ⁇ N” as the transmission period.
- FIG. 7 is a diagram showing a variation when a trigger is used in the TS start distribution function 50a and the TS synchronization function 20a. As shown in FIG. 7, the trigger output interval can be selected from “TS length”, “TS period”, and “TS period ⁇ N”.
- FIG. 8 schematically shows the TS output unit in each case of “TS length” (* 1), “TS period” (* 2), and “TS period ⁇ N” (* 3) shown in FIG.
- FIG. 8A is an image diagram when the trigger output interval is “TS length”
- FIG. 8B is an image diagram when the trigger output interval is “TS cycle”
- FIG. 8C is a diagram where the trigger output interval is “TS cycle ⁇ N”. It is an image figure in the case.
- FIG. 9 is a diagram for explaining the operation in the case of No. 1001 shown in FIG. With reference to FIG. 9, an operation when data is transmitted as an optical signal from a node A other than the master node 2 from the node A to the node B, from the node A to the node C, and from the node B to the node C will be described.
- Preliminary TS information is set for each node A to C.
- [1] and [2] in FIG. 9 show an example of TS information set in the node A and the node B.
- TS numbers “0” to “2” to be ADDed to one type of wavelength are not duplicated in each of the nodes A to C.
- Set TS length to 1 / integer of ring length.
- the master node 2 transmits a trigger to the node A at intervals of the TS length (20 ⁇ sec).
- the trigger that makes one round of the ring ends.
- the unit of TS length is ⁇ sec.
- the node A When receiving the trigger, the node A performs the first operation of the TS information after the offset time (5 ⁇ sec) as shown in [4]. However, the unit of the offset time is ⁇ sec. Note that the unit of the offset time is sometimes referred to as a count because 5 ⁇ sec may be counted as 5 counts in the system timing operation. That is, the node A ADDs the data of the destination node B to TS0 as shown in the first row of [1]. In this case, the optical SW connection port is connected from port number 3 to 2. When the node A receives the next trigger, the node A performs the second operation of the TS information in the same manner. The node A performs the third operation of the TS information in the same manner when the next trigger is received. That is, the node A ADDs the data of the destination node C to the TS 2 as shown in the third row of [1]. At this time, the optical SW connection port is also connected from port number 3 to 2.
- Node B When Node B receives the trigger, it performs the first operation of the TS information after an offset time (5 ⁇ sec) as shown in [5]. That is, the node B DROPs the data of TS0 as shown in [2]. At this time, the optical SW connection ports are connected to port numbers 1 to 3.
- the node B When the node B receives the next trigger, the node B performs the second operation of the TS information in the same manner. That is, the node B ADDs the data of the destination node C to TS1 as shown in [2]. In this case, the optical SW connection port is connected from port number 3 to 2.
- FIG. 10 is a diagram for explaining the operation in the case of No1002 shown in FIG. With reference to FIG. 10, an operation when data is transmitted as an optical signal from node A to node B, from node A to node C, and from node B to node C will be described.
- Preliminary TS information is set for each node A to C.
- [1] and [2] in FIG. 10 show an example of TS information set in the node A and the node B.
- TS numbers to be ADDed to one type of wavelength are not duplicated in each node.
- the TS length is set so that the TS cycle (TS length ⁇ m) is 1 / integer of the ring length.
- the master node 2 transmits a trigger to the node A at TS cycle intervals.
- the trigger that makes one round of the ring ends.
- the optical SW connection port is connected from port number 3 to 2.
- FIG. 11 is a diagram for explaining the operation in the case of No. 1004 shown in FIG. With reference to FIG. 11, an operation when data is transmitted from the node A to the node B, from the node A to the node C, and from the node B to the node C will be described with reference to FIG.
- Preliminary TS information is set for each node A to C.
- [1] and [2] in FIG. 11 show an example of TS information set in the node A and the node B.
- TS numbers to be ADDed to one type of wavelength are not duplicated in each of the nodes A to C.
- the TS length is set so that the TS cycle (TS length ⁇ m) is 1 / integer of the ring length.
- the master node 2 transmits a trigger to the node A at intervals of TS period ⁇ N.
- the trigger that makes one round of the ring ends.
- the node A When the node A receives the trigger, as shown in [4], after the offset time (here, 5 counts), the TS information is sequentially executed from the first to the m-th TS information, and after the m-th is executed, the next Until the first trigger is received, the first to mth operations are repeated.
- the node A repeats the operations from the first to the m-th TS information as in the case of the first trigger. That is, the node A ADDs the data of the destination node B to TS0 as shown in the first row of [1], and then the data of the destination node C to TS2 as shown in the third row of [1]. ADD.
- the optical SW connection ports are connected from port numbers 3 to 2.
- the node B When the node B receives the trigger, as shown in [5], after the offset time (5 counts), the node B performs the TS information in order from the first to the mth, and after executing the mth, receives the next trigger. Steps 1 to m are repeated.
- the node B repeats the operations from the first to the m-th TS information as in the case of the first trigger. That is, the node B DROPs the data of TS0 as shown in [2], and then ADDs the data of the destination node C to TS1.
- the optical SW connection port is connected from port numbers 1 to 3 at the time of DROP, and then connected from port numbers 3 to 2 at the time of ADD.
- 12A and 12B are diagrams for explaining a method of setting the TS length / TS cycle with respect to the ring length.
- each node A to C transmits and receives data through a transmission path indicated by a ring-shaped broken line. Therefore, in order to receive data beyond the master node 2 as in “Node C ⁇ Node A” (see FIG. 12A), the TS length or the TS cycle may be set to 1 / integer of the ring length L. . Specifically, when the trigger output interval is the TS length, the TS length is set to 1 / integer of the ring length L, and when the trigger output interval is TS period or TS period ⁇ N, the TS period is equal to the integer of the ring length L. 1 should be used. Accordingly, the node A can receive the data transmitted by the node C by the trigger newly transmitted by the master node 2.
- FIG. 13 is a diagram showing a time slot timing shift due to fluctuation.
- FIG. 14 shows the data in the time slot and the guard time.
- guard times are provided before and after the data.
- TS length time slot
- FIG. 15 is a block diagram showing a configuration example of the optical switch node 1A in the case of a unidirectional ring. Since the configuration in the case of the unidirectional ring is similar to the configuration described with reference to FIGS. 3 and 4, detailed description is omitted.
- FIG. 16 is a block diagram showing a configuration example of the optical switch node 1B in the case of a bidirectional ring.
- two trigger detection units 21 and two TS information management units 10 are provided for clockwise rotation and counterclockwise rotation.
- the master node that transmits the trigger transmits the trigger clockwise and counterclockwise in the ring, and each node has the same direction as the trigger transmission / reception direction based on the TS information of the TS information management unit 10 corresponding to the transmission / reception direction of the trigger.
- Data transmission / reception and SW switching are performed.
- each node uses the time slot information management unit (clockwise) to perform data transmission / reception and SW switching in the same manner as in the counterclockwise direction.
- 17A, 17B, 18A, and 18B are diagrams showing variations of the trigger transmission configuration.
- FIGS. 18A and 18B are configuration examples when the trigger is not passed through the optical TS-SW unit 30.
- the optical TS-SW unit 30 is set to broadcast.
- the optical TS-SW unit 30 branches the trigger.
- the optical TS-SW unit 30 is set to DROP / ADD.
- the trigger detection unit 21 branches the trigger.
- an OE-EO (optical-electrical) conversion is performed and the trigger is branched by an electric signal, or the trigger is branched by an optical coupler.
- the trigger detection unit 21 branches the trigger.
- FIG. 19A to 19C are diagrams showing variations of the connection configuration of the TS transceiver 40 and the optical TS-SW unit 30.
- FIG. 19A to 19C are diagrams showing variations of the connection configuration of the TS transceiver 40 and the optical TS-SW unit 30.
- FIG. 19A is a configuration example in the case of one output and one input
- FIG. 19B is a configuration example in the case of one input per queue
- FIG. 19C is a configuration example of two outputs per queue.
- the TS transceiver 40 includes a plurality of queues 40q1 and 40qn, and transmission data is stored in separate queues for each destination.
- the connection between the TS transmitting / receiving unit 40 and the optical TS-SW unit 30 is ADD / DROP and one port at a time.
- the TS transmission / reception unit 40 includes a plurality of queues 40q1 and 40qn, and the connection between the TS transmission / reception unit 40 and the optical TS-SW unit 30 is one ADD port for each queue, and the destination is different. Data can be output simultaneously if the ring transmission direction is different.
- the TS transceiver 40 includes a plurality of queues 40q1 and 40qn and a buffer 40b, and the connection between the TS transceiver 40 and the optical TS-SW unit 30 includes two DROP ports from the left and right of the ring. Can also be received.
- 20A and 20B are diagrams for explaining variations of the clock supply method.
- FIG. 20A is a block diagram showing a configuration of the optical switch node 1C when the internal clock (CK3) is used for counting elapsed time.
- Examples of the internal clock (CK3) include a cesium oscillator, a rubidium oscillator, and a crystal oscillator.
- FIG. 20B is a block diagram showing a configuration of the optical switch node 1D when the external clock (CK4) is used for the elapsed time count.
- Examples of the external clock (CK4) include a GPS (Global Positioning System) clock and a JJY clock (Japanese standard radio clock).
- a wavelength path by one wavelength is divided into time slots and assigned to a plurality of nodes so that the time slots do not overlap, thereby performing data transmission / reception or route switching for each node. be able to. Therefore, the number of nodes can be increased without depending on the number of wavelength paths.
- time slot information is embedded in a trigger and distributed to each node together with the trigger.
- FIG. 21 is a block diagram showing a configuration example of the optical switch node 1E in the second embodiment.
- FIG. 22 is a diagram schematically showing transmission paths for control signals and optical signals in the optical switch node 1E shown in FIG.
- the optical switch node 1E of the second embodiment is not provided with the TS information management unit 10 shown in FIG.
- the trigger detection unit 21 when receiving the trigger, delivers the TS information embedded in the trigger to the transmission control unit 23 and the optical SW control unit 22. It has become.
- FIG. 23 is a block diagram showing a configuration example of a master optical switch node (master node) 2E in the second embodiment.
- FIG. 24 is a diagram schematically showing transmission paths for control signals and optical signals in the master node 2E shown in FIG.
- the master node 2E of the second embodiment embeds TS information in the trigger and distributes it together with the trigger.
- An information distribution unit 60 is further included.
- FIG. 25 is a diagram for explaining the operation when the trigger output interval is “TS length” in the optical network system of the second embodiment. With reference to FIG. 25, the operation when data is transmitted from node A to node B using an optical signal will be described.
- the master node 2E describes the TS information 200, 201, 202 in the trigger and transmits it at intervals of the TS length.
- the information is 1 trigger 1TS.
- the node A receives the next trigger, it performs the same as above.
- the second embodiment not only the same effects as in the first embodiment can be obtained, but also there is an advantage that it is not necessary to provide the TS information management unit 10 in each node of the master node 2E and the optical switch node 1E. is there.
- the method described here is characterized in that the TS start is specified by time.
- the synchronization by the trigger described above needs to be on the same route as the trigger and the data, but the TS synchronization by the time can set the TS start time in advance, and even if the TS start time is distributed, the data and There is no need to distribute via the same route.
- the time setting in each node is performed when a time in which a delay time corresponding to the data transmission path is added to the time of the master node (a third embodiment and a fourth embodiment described later), and for all nodes. It is conceivable that a common time is set (a fifth embodiment described later).
- the TS start time can be made common to all nodes.
- common time there exists the characteristic that the time setting using GPS etc. can be utilized.
- the master node sets the time of each node at a time shifted from the transmission delay time by transmitting the time stamp, and synchronizes the time slot at the time common to each node, and the data Realizes transmission and reception.
- FIG. 26 is a block diagram showing a configuration example of the optical switch node 1F in the third embodiment.
- FIG. 27 is a diagram schematically showing transmission paths for control signals and optical signals in the optical switch node 1F shown in FIG.
- the optical switch node 1F includes a TS information management unit 10 that sets TS information, a TS synchronization unit 25, a time counter 70, an optical TS-SW unit 30, and a TS transceiver 40.
- the TS synchronization unit 25 includes a control signal processing unit 26, a transmission control unit 23, and an optical SW control unit 22.
- a demultiplexing unit 31 is connected to the input side of the optical signal, and a multiplexing unit 32 is connected to the output side of the optical signal.
- the control signal processing unit 26 detects a control signal for synchronizing the timing of the time slot of each node, notifies the time counter 70 of the time stamp value in the signal, and the time slot start time in the signal (hereinafter referred to as “time slot start time”). , Expressed as TS start time) to the transmission control unit 23 and the optical SW control unit 22.
- the time counter 70 sets a counter value to the time stamp value notified from the control signal processing unit 26, and supplies the counter value to the transmission control unit 23 and the optical SW control unit 22.
- the transmission control unit 23 When receiving the notification of the TS start time from the control signal processing unit 26, the transmission control unit 23 refers to the TS information management unit 10, and when the counter value supplied from the time counter 70 reaches the TS start time, The TS transmitter / receiver 40 is instructed with the assigned time slot.
- the TS transmitting / receiving unit 40 stores data input from the outside in a buffer (not shown), transmits data read from the buffer to the optical TS-SW unit 30 in accordance with an instruction from the transmission control unit 23, and transmits the optical TS. -Send data received from the SW unit 30 to the outside.
- the optical SW control unit 22 When receiving the notification of the TS start time from the control signal processing unit 26, the optical SW control unit 22 refers to the TS information management unit 10, and when the counter value supplied from the time counter 70 becomes the TS start time, the optical SW control unit 22 is instructed to switch to the optical TS-SW unit 30 in the time slot assigned to 22.
- the optical TS-SW unit 30 switches the route in response to a switching instruction from the optical SW control unit 22.
- FIG. 28 is a block diagram showing a configuration example of a master optical switch node (master node) 2F in the third embodiment.
- FIG. 29 is a diagram schematically showing transmission paths of control signals and optical signals in the master node 2F shown in FIG.
- the master node 2F includes a TS start distribution unit 80 and a delay time calculation unit 90 in addition to the configuration described with reference to FIG.
- the TS start distribution unit 80 includes a control signal generation unit 81 and a master time counter 82.
- the master time counter 82 supplies a counter value to the control signal generator 81.
- the control signal generator 81 generates a control signal including the TS start time, adds the counter value supplied from the master time counter 82 to the control signal as a time stamp, and transmits the control signal to each node 1F.
- the delay time calculation unit 90 subtracts the time stamp value from the reception time of the control signal that has made one round of the ring, calculates the time for one round of the ring, and writes this calculation result in the TS information management unit 10.
- optical network system of the third embodiment is the same as that of the fourth embodiment to be described later, so the description thereof is omitted here.
- the master node 2F sets the time of each node 1F at the time shifted by the transmission delay time by transmitting the time stamp, and each node 1F synchronizes with the time slot at the common time, and the data It is possible to execute transmission / reception or route switching.
- the fourth embodiment is such that a master node distributes TS information to each node.
- FIG. 30 is a block diagram showing a configuration example of the optical switch node 1G in the fourth embodiment.
- FIG. 31 is a diagram schematically showing transmission paths for control signals and optical signals in the optical switch node 1G shown in FIG.
- the optical switch node 1G of the present embodiment is different in that the TS information management unit 10 of the optical switch node 1F shown in FIG. 26 is not provided.
- FIG. 32 is a block diagram showing a configuration example of a master optical switch node (master node) 2G in the fourth embodiment.
- FIG. 33 is a diagram schematically showing transmission paths for control signals and optical signals in the master node 2G shown in FIG.
- the master node 2G is not provided with the TS information management unit 10, but the TS information distribution unit that supplies the TS information to the control signal generation unit 81 60 is provided.
- FIG. 34 is a diagram showing a variation when the time is used in the TS start distribution function and the TS synchronization function, and the time counter is set to the time with delay difference.
- a plurality of information may be collectively included in the control signal SS and sent as control signals for setting the TS information, and the control signals SS1, SS2, It may be sent in SS3. That is, the control signal SS collectively includes a TS start time, a time stamp, and TS information.
- the control signal SS1 includes a TS start time
- the control signal SS2 includes a time stamp
- the control signal SS3 includes TS information.
- FIG. 35 is a diagram for explaining the operation in the case of No. 2002 shown in FIG. Referring to FIG. 35, a case where local time / TS start time is distributed and all TSs are set in advance will be described.
- the master node 2G sets time slot information in each of the nodes A and B. Subsequently, as shown in [3], the master node 2G transmits a control signal SS4 including a TS start time and a time stamp value (for example, 80) every TS cycle.
- a control signal SS4 including a TS start time and a time stamp value (for example, 80) every TS cycle.
- the node A When the node A receives the control signal SS4 from the master node 2G as shown in [4], the node A sets the time counter (80) to the time stamp value (80). Then, as shown in [5], when the time counter reaches the TS start time (100), the node A performs operations in order from TS0. That is, the node A performs the operation of the TS information when the time “TS start time + TS number ⁇ TS length” is reached.
- the node A uses the time counters 100 to 120 to add data to TS0 as shown in the first row of [1], and as shown in the third row of [1] using the time counters 140 to 160. Add data to TS2.
- FIG. 36A and FIG. 36B are diagrams for explaining a method for setting a time to which a transmission line delay time is added.
- the master node 2G transmits a time synchronization signal with a time stamp as shown in a frame G1.
- Each optical switch node 1G sets the time stamp value of the received time synchronization signal to the current time, as shown in the frame G2.
- the time (T1) when the time synchronization signal is transmitted is given as a time stamp.
- a time synchronization signal SC1 to which the time stamp value T1 is assigned is transmitted to each optical switch node 1G.
- the time stamp value (T1) is set as the current time of the own optical switch node 1G.
- the master node 2G transmits and sets the time synchronization signal SC1 with a time stamp to the optical switch node 1G.
- the time synchronization signal SC1 by periodically transmitting the time synchronization signal SC1, the change of the transmission path length due to the temperature change Can be absorbed.
- FIG. 37A and FIG. 37B are diagrams for explaining variations of the method for setting time with delay.
- FIG. 37A shows a case of counterclockwise rotation (counterclockwise) as shown by an arrow Y1
- FIG. 37B shows a case of clockwise rotation (clockwise) as shown by an arrow Y2.
- the master node 2G transmits a control signal with a time stamp to set to each of the nodes 1G1, 1G2, and 1G3 either in the counterclockwise direction shown in FIG. 37A or in the clockwise direction shown in FIG. 37B.
- the master node 2G transmits the local time t included in the control signal as a time stamp value, and the node 1G1 receives this control signal.
- the node 1G1 sets the time stamp value t of the control signal as the local time in the time counter of the own node 1G1.
- the local time of the node 1G1 is set to a time (ta) that is shifted by the delay time a from the local time of the master node.
- t is set as the local time.
- the local time of the node 1G2 is set to a time (tab) that is shifted from the local time of the master node 2G by the delay time (a + b).
- t is set as the local time.
- the local time of the node 1G3 is set to a time (ta ⁇ b ⁇ c) that is shifted by the delay time (a + b + c) from the local time of the master node 2G.
- each node 1G1 to 1G3 preferably includes two time counters for clockwise and counterclockwise.
- FIG. 38 is a block diagram showing a configuration example of the optical switch node 1H in the case of a unidirectional ring. Since the configuration in the case of the unidirectional ring is the same as the configuration described with reference to FIGS. 26 and 27, the detailed description is omitted.
- 39A and 39B are block diagrams showing an example of the configuration of the optical switch nodes 1I and 2J in the case of a bidirectional ring.
- the optical switch node 1I shown in FIG. 39A is also applied as the master node 2I as described later.
- the control signal processing unit 26, the TS information management unit 10, and the time counter 70 are provided in two clockwise and counterclockwise directions.
- the master node 2I transmits the control signal clockwise and counterclockwise of the ring, and each node 1I operates using the TS information and the time counter 70 of the TS information management unit 10 corresponding to the transmission / reception direction of the control signal.
- Each node 1I when receiving the clockwise control signal, uses the clockwise TS information management unit 10 and the clockwise clock counter 70.
- FIG. 39B shows the configuration of the master node 2J.
- the master node 2J transmits the control signal clockwise or counterclockwise in the ring and performs data transmission in the direction opposite to the control signal transmission / reception direction, the time obtained by subtracting the delay time by the delay time calculation unit 90 from the TS start time works as.
- the master node performs the same method as the one-way ring.
- FIG. 40 is a diagram for explaining the DROP switching time of the master node 2J.
- transmission / reception (straddling communication) across the master node 2J means that in the forward direction of transmission, the master node 2J is passed through the master node 2J from the node 1J3 connected to the upstream side of the master node 2J. The signal is received by the node 1J1 connected to the downstream side of 2J, or the signal is received by the node further downstream.
- the node 1J1 connected to the downstream side of the master node 2J passes through the master node 2J, and receives a signal at the node 1J3 connected to the upstream side of the master node 2J. Furthermore, the signal is received at an upstream node.
- the DROP switching time of the master node 2J is set to “TS start time + TS number ⁇ TS length + ring one round time”.
- the DROP switching time is similarly set to “TS start time + TS number ⁇ TS length + one ring round time” for transmission / reception across the master node 2J.
- FIG. 41 is a diagram showing an example of setting TS information of the master node.
- a ring one round time (a + b + c + d) is added to cope with the case where the reception time does not become the transmission time.
- the time for the master node 2J to DROP is “TS start time + TS number ⁇ TS length + ring time for one ring”.
- the first method is to measure the delay time in advance with a measuring instrument such as OTDR and set the measurement result in the TS information management unit 10.
- the setting in the TS information management unit 10 may be manual.
- the second method is to calculate from the control signal that makes one round of the ring. This second method will be described with reference to FIG. FIG. 42 is a diagram for explaining a calculation method and a setting method of the ring one round time.
- the master node 2K generates a control signal SS10 with a time stamp in the control signal generation unit 81, and transmits the control signal SS10. Then, the master node 2K receives the control signal SS10 with a time stamp returned around the ring by the delay time calculation unit 90, and calculates the ring one-round time by subtracting the time stamp value from the reception time, Write to the TS information management unit 10.
- FIG. 43 is a diagram showing a variation when the time counter is set to a common time.
- the common time since the common time is set, it is not necessary to distribute a signal for setting the local time of each node.
- the nodes share common time information, measure the delay time, and subtract the delay time from the TS start time to synchronize the TS.
- FIG. 44 is a block diagram showing a configuration example of the optical switch node 1L in the fifth embodiment.
- FIG. 45 is a diagram schematically showing transmission paths for control signals and optical signals in the optical switch node 1L shown in FIG.
- the optical switch node 1L includes a TS information management unit 10 that sets TS information, a TS synchronization unit 25, a common time counter 75, a delay time management unit 95, and an optical TS-SW unit 30. And a TS transmission / reception unit 40.
- the TS synchronization unit 25 includes a control signal processing unit 26, a transmission control unit 23, and an optical SW control unit 22.
- a demultiplexing unit 31 is connected to the input side of the optical signal
- a multiplexing unit 32 is connected to the output side of the optical signal.
- the control signal processing unit 26 When receiving the control signal, the control signal processing unit 26 notifies the transmission control unit 23 and the optical SW control unit 22 of the TS start time. When the control signal includes TS information, the control signal processing unit 26 writes the TS information in the TS information management unit 10.
- the TS information management unit 10 manages TS information and causes the transmission control unit 23 and the optical SW control unit 22 to refer to the TS information.
- the TS information includes information on the TS number, data transmission destination, operation, optical SW connection port number, TS length, and TS cycle.
- the transmission control unit 23 When the transmission control unit 23 receives the TS start time notification from the control signal processing unit 26, the transmission control unit 23 refers to the TS information management unit 10 and the delay time management unit 95, and performs the operation of the corresponding TS number. If the operation is ADD, the TS transmission / reception unit is instructed to transmit data to the data transmission destination. The transmission control unit 23 receives the time from the common time counter 75.
- the TS transmitter / receiver 40 transmits / receives data between an external device (not shown) and the optical TS-SW unit 30.
- the external device is, for example, a communication device such as a router illustrated in FIG.
- the TS transmitting / receiving unit 40 transmits the data so that the corresponding optical switch node becomes the destination according to the transmission instruction from the transmission control unit 23.
- the TS transmission / reception unit 40 stores the data in a queue in the buffer until a transmission instruction is received from the transmission control unit 23.
- the optical SW control unit 22 When the optical SW control unit 22 receives the TS start time notification from the control signal processing unit 26, the optical SW control unit 22 refers to the TS information management unit 10 and the delay time management unit 95 and performs the operation of the corresponding TS number. If the operation is ADD or DROP, the optical TS-SW unit 30 is instructed to switch. After instructing switching, the optical TS-SW unit 30 is instructed to switch back after the TS length has elapsed. The optical SW control unit 22 receives time from the common time counter 75.
- the optical TS-SW unit 30 switches the connection in the optical SW in response to a switching instruction from the optical SW control unit 22.
- the common time counter 75 receives a clock (not shown) and counts the time. This time is common to all nodes.
- the delay time management unit 95 manages the delay times of the master node and the own node.
- FIG. 46 is a block diagram showing a configuration example of the master node 2L in the present embodiment.
- FIG. 47 is a diagram schematically showing transmission paths for control signals and optical signals in master node 2L shown in FIG.
- the master node 2L includes a control signal generation unit 81 instead of the delay time management unit 95 in the configuration described with reference to FIG.
- the control signal generation unit 81 generates a control signal including a TS start time and a time stamp, and transmits the control signal to each node.
- FIG. 48 is a diagram illustrating a configuration example of an optical network system according to the fifth embodiment.
- the master node 2L shown in FIG. 48 corresponds to the master node 2L shown in FIG. 46, and the nodes 1L1 to 1L5 correspond to the optical switch node 1L shown in FIG. In this configuration, the master node 2L transmits the control signal SS11 and the data D11 in the counterclockwise direction indicated by the arrow Y3.
- FIG. 49A is a configuration diagram of an optical network system in which a master node 2L and two nodes 1L1 and 1L2 are ring-connected.
- FIG. 49B is a diagram for explaining the TS start time when the common time is set in the optical network system.
- each node 1L1, 1L2 is a value obtained by adding the delay time a or a + b with the master node 2L to the transmitted TS start time t. Is newly set as the TS start time.
- FIG. 50 is a diagram for explaining a delay time measuring method.
- the configuration related to the delay time measurement method is shown in the figure, and the other configurations are not shown in the figure.
- the master node 2M transmits a time stamp from the time stamp transmission unit 81m. In the case of a bidirectional ring, reverse rotation is also performed.
- the delay time management unit 95 manages both the clockwise and counterclockwise delay times of the ring.
- FIG. 51 is a diagram in which optical TS-SW units applicable to the above-described embodiment are classified.
- the optical TS-SW unit accommodates the data line of the ring network, and changes the connection relation between the input port and the output port according to the instructions of the scheduler.
- the optical TS-SW unit is a wavelength routing type switch by wavelength conversion or a broadcast & select type spatial switch. More specifically, when accommodating wavelength-multiplexed data lines, as shown in [1], a demultiplexing unit is installed before the input of the optical TS-SW unit, and data input by wavelength multiplexing is, for example, N Each wavelength is demultiplexed and given to input ports denoted by IN 1 to IN N.
- a multiplexing unit is installed after the optical TS-SW unit, the optical signals from the N output ports OUT 1 to OUT N of the optical TS-SW unit are wavelength-multiplexed, and the next node on the ring network The data is transmitted to (next node).
- the optical TS-SW unit also has functions of optical signal insertion (ADD) and optical signal branching (DROP).
- An ADD port is provided as an input port of the optical TS-SW unit, and a DROP port is an optical port. It is provided as an output port of the TS-SW unit.
- the demultiplexing unit and the multiplexing unit are not provided. In this case, the number of data lines in the ring is equal to the number of terminals (ports) obtained by subtracting the number of ADD / DROP interfaces in the optical switch.
- Examples 1 to 5 are configuration examples of an optical TS-SW unit that does not have an FWC (fixed wavelength converter), and Examples 6 to 8 are configuration examples of an optical TS-SW unit that has an FWC. It is.
- an alphabetic suffix is added to the number of wavelength ⁇ .
- optical TS-SW unit The configuration of the optical TS-SW unit according to the first embodiment will be described. Here, it is assumed that a double ring, 1ADD / 1DROP, and fiber exchange are possible.
- FIG. 52 is a diagram for explaining the configuration of the optical TS-SW unit 30A of the first embodiment.
- (Arrayed Waveguide Grating) 30a arranged in front of it, k number of 1 ⁇ N AWGs 30b and 30c as wavelength converting and demultiplexing units, and k (N ⁇ 2) THRUs (Passing) / DROP TWC1 to TWC4, one ADD TWC [A], one optical receiver 30e as a DROP IF (interface), and k (N-1) ⁇ 1 multiplexing units 30x , 30y.
- TWC is a variable wavelength converter.
- the recursive AWG (also simply referred to as AWG) 30a performs a process of distributing the optical signal input to each input port to the output port according to the wavelength.
- the optical TS-SW unit 30A shows an example in which wavelength switching between fibers is performed in a 1ADD / 1DROP configuration that does not use FWC when a double ring uses four wavelengths per ring.
- optical TS-SW unit The configuration of the optical TS-SW unit according to the second embodiment will be described. Here, the case of a double ring, 1ADD / 1DROP, exchangeable fiber, and switch control wavelength is assumed.
- FIG. 53 is a diagram for explaining the configuration of the optical TS-SW unit 30B according to the second embodiment.
- k circular 1 ⁇ N AWGs 30b and 30c Arranged in the preceding stage, as a wavelength converting section and a demultiplexing section, k circular 1 ⁇ N AWGs 30b and 30c, k (N ⁇ 2) THRU / DROP TWC1 to TWC4, and one ADD TWC [A], an optical receiver 30e as one DROP IF, and k (N ⁇ 1) ⁇ 1 multiplexers 30x and 30y.
- FIG. 54 is a diagram for explaining the configuration of the optical TS-SW unit 30C according to the third embodiment.
- k circular 1 ⁇ N AWGs 30b and 30c Arranged in the preceding stage, k circular 1 ⁇ N AWGs 30b and 30c as wavelength converting and demultiplexing parts, k (N ⁇ 2) THRU / DROP TWC1 to TWC4, one in the subsequent stage It has an ADD TWC [A] and demultiplexing unit 30j, an optical receiver 30e as one DROP IF, and k (N ⁇ 1) ⁇ 1 multiplexing units 30x and 30y.
- FIG. 55 is a diagram for explaining the configuration of the optical TS-SW unit 30D according to the fourth embodiment.
- the configuration of the optical TS-SW unit of Example 5 will be described. Here, a case of a double ring, 1ADD / 1DROP, 1AWG / 1 fiber, and switch control wavelength is assumed.
- FIG. 56 is a diagram for explaining the configuration of the optical TS-SW unit 30E according to the fifth embodiment.
- AWGs 30t and 30u arranged in the preceding stage thereof, k circular 1 ⁇ N AWGs 30b and 30c as wavelength converting and demultiplexing units, k (N ⁇ 2) THRU / DROP TWC1 to TWC4, One ADD TWC [A], one optical receiver 30e as DROP IF, ADD / DROP TWC [A / D] between fibers, and k N ⁇ 1 multiplexers 30x, 30y.
- a control wavelength for performing switch control is prepared, and in order to ensure reachability of the control wavelength, couplers 30f and 30g are connected to the demultiplexing unit and copied by each switch.
- the data wavelength is 2 wavelengths / fiber
- the control wavelength is 1 wavelength / fiber.
- the optical TS-SW unit 30E uses a double wavelength ring (4 wavelengths per ring) and one fiber per AWG 30t, 30u, and uses a control wavelength in a 1ADD / 1DROP configuration that does not use FWC. Is shown.
- FIG. 57A is a diagram for explaining the configuration of the optical TS-SW unit 30F according to the sixth embodiment.
- FIG. 57B is a diagram showing TWC wavelength requirements for eight TWC1 to TWC8 and ADD TWC [A] in the optical TS-SW unit 30F.
- the optical TS-SW unit 30F includes a 9 ⁇ 9AWG 30v, eight TWC1 to TWC8 provided in the preceding stage, and eight FWC1 to FWC4 + FWC1 to FWC1 provided in the subsequent stage of 9 ⁇ 9. It has FWC4 and ADD TWC [A].
- the suffix for the wavelength for THRU is r
- the suffix for the wavelength for DROP is g
- the suffix for the wavelength for ADD is b.
- ADD means that a signal input to IN1 of AWG 30v is output to any one of OUT1 to OUT9.
- DROP means that signals input to IN2 to IN9 of AWG 30v are output to OUT9. Through means that a signal input to IN2 to 9 of the AWG 30v is output to an OUT number obtained by subtracting 1 from the IN number. Detailed operation will be described with reference to FIG. 57A.
- the wavelength is converted into any one of ⁇ 1b to 8b by TWC [A] depending on where OUT1 to 8 are output, and input to IN1.
- the correspondence between the wavelength input to IN1 and the output destination is ⁇ 1b is OUT1, ⁇ 2b is OUT2, ⁇ 3b is OUT3, ⁇ 4b is OUT4, ⁇ 5b is OUT5, ⁇ 6b is OUT6, ⁇ 7b is OUT7, and ⁇ 8b is OUT8.
- the signals coming from the fibers 1 and 2 are demultiplexed by the AWGs 30b and 30c, and the wavelengths are converted by the TWCs 1 to 8 according to whether they pass through or drop.
- the wavelength and output destination will be described by taking TWC1 as an example. In the case of through, ⁇ 1g and ⁇ 2r are OUT1.
- optical TS-SW unit of Example 7 The configuration of the optical TS-SW unit of Example 7 will be described. Here, the case of double ring (1 ring 4 wavelengths), ADD / DROP 1CH, and intra-fiber wavelength switching is assumed.
- FIG. 58A is a diagram for explaining the configuration of the optical TS-SW unit 30G according to the seventh embodiment.
- FIG. 58B is a diagram showing TWC wavelength requirements for eight TWC1 to TWC8 and ADD TWC [A] in the optical TS-SW unit 30G.
- the optical TS-SW unit 30G shown in FIG. 58A has the same configuration except that the optical TS-SW unit 30F shown in FIG. 57A is different in wavelength requirements from TWC1 to TWC8, [A], and thus the description thereof is omitted.
- the subscript of the wavelength for THRU is r
- the subscript of the wavelength for DROP is g
- the subscript of the wavelength for ADD is b
- the subscript is y.
- a signal input to IN2 to 5 of the AWG 30v is output to any one other than the output destination through OUT1 to 4. This means that the signal input to IN6 to 9 of AWG30v is output to any one other than the output destination through OUT5 to 8.
- FIGS. 58A and 58B Since ADD, Drop, and Through are the same as in the sixth embodiment, the case of intra-fiber exchange will be described by taking TWC1 as an example.
- the wavelength of the signal input to TWC1 is set to ⁇ 3y.
- the wavelength of the signal input to TWC1 is set to ⁇ 3y.
- optical TS-SW unit of Example 8 The configuration of the optical TS-SW unit of Example 8 will be described. Here, a case of double ring (1 ring 4 wavelengths), ADD / DROP 1CH, wavelength exchange between fibers and within fiber is assumed.
- FIG. 59A is a diagram for explaining the configuration of the optical TS-SW unit 30H according to the eighth embodiment.
- FIG. 59B is a diagram showing TWC wavelength requirements for eight TWC1 to TWC8 and ADD TWC [A] in the optical TS-SW unit 30H.
- the optical TS-SW unit 30H illustrated in FIG. 59A has the same configuration except that the optical TS-SW unit 30F illustrated in FIG. 57A is different in wavelength requirements from TWC1 to TWC8 and [A], and thus description thereof is omitted.
- the subscript of the wavelength for THRU is r
- the subscript of the wavelength for DROP is g
- the subscript of the wavelength for ADD is b
- the subscript is y
- the inter-fiber exchange wavelength subscript is p.
- FIG. 60 is a block diagram showing a configuration example of the optical TS-SW unit 30J including TWC and FWC.
- the optical TS-SW unit 30J includes one or a plurality of input ports and a plurality of output ports, a demultiplexer (demultiplexing unit) 30b for demultiplexing the wavelength-multiplexed input optical signal for each wavelength, and each input An AWG 30a that distributes an optical signal input to a port to an output port according to its wavelength, and a TWC that performs wavelength conversion to select passage (through), insertion (ADD), and branching (DROP) at an optical switch node.
- a demultiplexer (demultiplexing unit) 30b for demultiplexing the wavelength-multiplexed input optical signal for each wavelength
- An AWG 30a that distributes an optical signal input to a port to an output port according to its wavelength
- a TWC that performs wavelength conversion to select passage (through), insertion (ADD), and branching (DROP) at an optical switch node.
- the optical signal transmitted by wavelength multiplexing from the previous stage is demultiplexed into wavelengths ⁇ 1 to ⁇ 8 by the demultiplexer 30b, and these demultiplexed optical signals are respectively transmitted from the AWG 30a via the TWC1 to TWC8. Is given to the input port.
- an optical signal to be inserted is provided to the input port of the AWG 30a via the TWC [A] 1 to TWC [A] 3.
- Eight of the output ports of the AWG 30a are for transmission to the next stage, and optical signals from these output ports are respectively input to the multiplexer (multiplexing unit) 30x via the FWC1 to FWC8, and are wavelength-multiplexed. It is transmitted to the next stage.
- the AWG 30a has an output port used for branching (DROP), and an optical receiver 30e is connected to this output port.
- the optical receiver 30e includes a photoelectric element (APD) that performs photoelectric conversion, a limiting amplifier (LIM) that absorbs a power difference between optical signals, and a clock that absorbs a phase difference between the optical signals.
- a data recovery circuit (CDR) is connected in series in this order, and receives an optical signal by absorbing a power difference / phase difference between signals.
- the wavelength ⁇ 8 is a fixed wavelength for control.
- Each channel of ADD and DROP is also used for control, and is connected to a switch control unit 30k for controlling the optical TS-SW unit 30J.
- the switch control unit 30k is also configured with an APD, a LIM, and a CDR.
- FIG. 61 is a block diagram showing a configuration example of TWC1 to TWC8 (or TWC [A] 1 to TWC [A] 3) shown in FIG.
- the TWC includes an optical burst receiver 301, a wavelength tunable light source 302a, and a modulator 303a.
- the optical burst receiver 301 has APD, LIM, and CDR.
- the optical signal transmission path is indicated by a solid line, and the electrical signal transmission path is indicated by a broken line.
- APD performs photoelectric conversion that converts optical signals into electrical signals.
- LIM serves to reduce the power difference that occurs between frames.
- the power difference is caused by, for example, a loss difference due to different transmission path lengths or an output power difference of the light source.
- CDR serves to reduce the phase difference that occurs between frames.
- the phase difference is caused by, for example, a phase difference due to a different transmission path length.
- the wavelength variable light source 302a changes the oscillation wavelength in order to change the output destination in the AWG 30a.
- the modulator 303a replaces the received signal with a different wavelength.
- the TWC performs optical-electric-optical (OEO: Optical-Electrical- Optical) conversion with the above-described configuration, so that the power of the attenuated light can be recovered even when data is transmitted over a long distance using an optical signal. This eliminates the need for an optical amplifier.
- OEO optical-electric-optical
- FIG. 62 is a block diagram showing an example of the configuration of FWC1 to FWC8 shown in FIG.
- the FWC includes an optical burst receiver 311a and a fixed wavelength light source 312.
- the optical burst receiver 311a has APD, LIM, and CDR.
- the optical signal transmission path is indicated by a solid line, and the electrical signal transmission path is indicated by a broken line.
- APD performs photoelectric conversion.
- LIM serves to reduce the power difference that occurs between frames.
- the power difference is caused by, for example, a different loss or an output power difference of the light source for each port received by the AWG.
- CDR serves to reduce the phase difference that occurs between frames.
- the phase difference is caused by, for example, an optical path difference between different AWGs 30a.
- the fixed wavelength light source 312 performs wavelength conversion so that the wavelengths of the pass-through data and the ADD data are the same so that they are output to the same port by a demultiplexer (not shown) in the next stage.
- optical TS-SW unit is a broadcast & select type spatial switch
- FIG. 63 is a diagram showing a basic configuration of a broadcast & select type spatial switch.
- the optical TS-SW unit 30K shown in FIG. 63 includes an AWG 30b that demultiplexes a wavelength multiplexed signal (WDMi), a plurality of N ⁇ 1 SW 30m, a DROP N ⁇ 1 SW 30n, an ADD TWC 30d, and a plurality of N ⁇ And a coupler 30p for multiplexing optical signals from 1SW.
- the N ⁇ 1 SW 30m includes a semiconductor optical amplifier (SOA).
- SOA semiconductor optical amplifier
- the optical TS-SW unit 30K demultiplexes an optical signal input as a wavelength multiplexed signal (WDMi) by the AWG 30b, and transmits each demultiplexed wavelength component to a plurality of N ⁇ 1 SWs 30m by the coupler 30g.
- signal transmission or blocking control (through control) is performed by a semiconductor optical amplifier (SOA).
- SOA semiconductor optical amplifier
- One of the N ⁇ 1 SWs 30m is a DROP port.
- the output of the remaining N ⁇ 1 SW 30m and the output from the TWC 30d for ADD are combined by the coupler 30p and transmitted to the next stage as a wavelength multiplexed signal (WDMo).
- Each N ⁇ 1 SW 30m is provided with an SOA for each input port, an SOA for an output port, and a space switch. When the number of ports is N, the number of SOAs to be controlled is N 2 .
- FIG. 64 is a diagram showing another configuration example of a broadcast & select type spatial switch.
- the AWG 30b in the previous stage is eliminated from the configuration of the optical TS-SW unit 30K shown in FIG. 63, and the N ⁇ 1 SW 30m using SOA is changed to the wavelength tunable filter 30q. It is configured to switch between transmission and blocking of an arbitrary wavelength. In each wavelength tunable filter 30q, a signal is transmitted or blocked (through control) with respect to an arbitrary wavelength by the wavelength filter. In this configuration, since the AWG 30b in the previous stage is not required, the number of elements to be controlled for the switch can be reduced from N 2 to N as compared with that shown in FIG.
- processing by time division division (TDM) is used together with the addition of the concept of time slots (TS) having a constant time period to the optical network by wavelength division multiplexing (WDM).
- TDM time division division
- WDM wavelength division multiplexing
- a master node and an optical switch node corresponding to an OADM node in the conventional optical network are provided, and the master node dynamically performs TS allocation and wavelength allocation in each optical switch node. I am trying to change it.
- 65A and 65B are diagrams showing an outline of the operation of the optical network based on the present embodiment.
- optical switch nodes 121 are respectively provided at points A to D, and data transmission by optical communication is performed between these points via a ring-shaped optical network.
- a master node 120 is provided for instructing the optical switch node 121 to assign a slot and switch the optical switch.
- the master node 120 is drawn separately from the optical switch node 121, but any one of the optical switch nodes may function as the master node. That is, a master node may be provided in any one of the optical switch nodes.
- the optical switch node performs data transmission and switch switching according to the TS information assigned as indicated by the arrow Y10 from the master node 120, so that the same destination data can be transmitted at a single wavelength without causing data collision. It becomes possible.
- all data from the points A to C to the point D are transmitted using the wavelength ⁇ 1.
- ⁇ 1>, ⁇ 2>, and ⁇ 3> of time slots TS are assigned to points A, B, and C, respectively.
- WDM can be achieved by changing the wavelength used in each time slot ⁇ 1>, ⁇ 2>, ⁇ 3>. For example, different wavelengths can be used for different destinations, and time slots can be assigned to each transmission source node for the same destination.
- FIG. 66A shows the configuration of an optical network system according to another embodiment of the present embodiment.
- a ring-shaped optical network is provided, and a master node 120 and a plurality of optical switch nodes 121 are provided on the optical network.
- the optical network includes a one-way transmission data line 122 used for data transmission and control lines 123 and 124 used for control data transmission.
- the control line 123 transmits control information clockwise in the figure on the network.
- the control line 124 transmits control information counterclockwise in the figure.
- This optical network system is an N-wavelength multiplexing WDM / TDM ring network that performs ADD / DROP of data using both wavelength multiplexing and time multiplexing using time slots (TS).
- TS time slots
- dynamic bandwidth allocation is performed according to the amount of traffic from the external network. This band allocation is realized by changing the allocation amount of TS defined in the wavelength and the optical network system.
- data from the external network is converted into data in a time slot according to the allocated TS amount.
- bufferless / headerless switching is performed with light by WDM / TDM.
- the master node 120 (A) The amount of traffic flowing in from each optical switch node 121 is periodically collected, and the TS amount assigned to each switch node 121 is determined in correspondence with the traffic amount. (B) taking into account the propagation delay time between the buffers of different optical switch nodes 121, and specifying the timing to start the operation according to the assigned TS; (C) Reassign time slots according to the amount of traffic collected from each optical switch node every fixed period (T). It has the function. As described above, the master node 120 may exist in the optical switch node.
- the optical switch node 121 is composed of a WDM / TDM switch. In addition to the WDM / TDM switch, the optical switch node provided at the edge of the optical network is provided with a buffer unit that performs TS conversion.
- the optical switch node 121 is (A) Accumulating input signals from an external network in a buffer and reporting the data amount for each destination to the master node 120. (B) According to the TS table set from the master node 121, data transmission (ADD) from its own buffer and route change in the WDM / TDM switch are performed.
- Such an optical switch node 121 includes an optical TS-SW unit that realizes an ADD / DROP and a WDM / TDM switch, as will be described later.
- a control wavelength different from that for data is used, or fibers (for example, control lines 123 and 124 shown in the figure) different from those for data are used. .
- This is to ensure reachability so that the TS table for operating the active optical TS-SW unit (WDM / TDM switch) reaches each optical switch node 121.
- the master node 120 assigns time slots to control signals and data signals transmitted from the optical switch node 121 so that packet collision does not occur in the ring.
- the buffer unit of the optical switch node 121 does not need to exist in the same device, and may be installed in a geographically distant place. In this case, any one such as a delay measurement between the buffer unit and the switch control unit may be used. A form having a mechanism for measuring whether the distance is some degree is desirable. Further, the control signal line and the data line between the optical switch nodes 121 can be wavelength-multiplexed and shared by the fiber.
- 66B shows a case where data is transmitted from the optical switch node 121 indicated by ⁇ 1> to ⁇ 3> in FIG. 66A to the optical switch nodes indicated by A and B (B is also the master node 120).
- An example of TS allocation is shown.
- the optical switch nodes indicated by ⁇ 1> to ⁇ 3> transmit in the assigned time slot, and repeat transmission in the same debt slot until reallocation is performed.
- the optical network system of this embodiment it is necessary to accurately control the transmission / reception timing at each optical switch node.
- a configuration for that purpose two configurations of a trigger type and a time synchronization type are assumed.
- the configurations of the master node 120 and the optical switch node 121 differ depending on whether the trigger type or the time synchronization type is used.
- the trigger type is based on the assumption that the control packet and the data packet have the same path, that is, have the same propagation delay time, and at the moment when the TS information (trigger) from the master node 120 arrives, in each optical switch node 121.
- the time synchronization type measures the propagation delay time between the buffers and between the optical switch nodes even when the control packet and the data packet do not pass through the same route, and performs the time synchronization control considering the propagation delay, This prevents a slot collision between optical switch nodes.
- FIG. 67A shows the configuration of the master node 120 in the trigger type
- FIG. 67B shows the configuration of the optical switch node 121 in the trigger type.
- solid arrows indicate data signal paths
- broken arrows indicate control signal paths.
- the trigger-type master node 120 includes a demultiplexing unit 131 that separates the wavelength of an optical signal input from the transmission line, a multiplexing unit 132 that wavelength-multiplexes a signal output to the transmission line, and a demultiplexer (demultiplexing unit).
- the control signal receiving unit 133 that receives the control signal separated in 131, the traffic information collecting unit 134 that totals the traffic information transmitted from each optical switch node, and the optical TS-SW unit of each optical switch node TS allocation for performing time slot allocation for each optical switch node 121 based on the topology management unit 135 that manages connection information, the traffic information aggregated by the traffic information collection unit 34, and the topology information acquired by the topology management unit 135 Unit 136, TS start distribution unit 137 that generates a trigger pulse at regular intervals, and TS information together with the trigger pulse for each optical switch. And TS information distribution section 138 that distributes the Chinodo, and a.
- the trigger-type optical switch node 121 includes a demultiplexing unit 141 that demultiplexes an optical signal that enters from the transmission path, a multiplexing unit 142 that wavelength-multiplexes a signal output to the transmission path, and a demultiplexer (demultiplexing unit). ) An optical TS-SW provided between the control signal receiving unit 143 that receives the control signal separated at 141 and the demultiplexing unit 141 and the multiplexing unit 142 and that realizes an ADD / DROP and a WDM / TDM switch.
- TS synchronization unit 145 that is connected to control signal receiving unit 143 to realize time slot synchronization, and a buffer that stores data input from an external device, and transmits data from the buffer to optical TS-SW unit 144
- the TS transceiver unit 146 that receives data from the optical TS-SW unit 144 and transmits data to an external device, and the amount of data stored in the buffer of the TS transceiver unit 146 are masked.
- a traffic information transmitting unit 147 to be transmitted to the traffic information collecting unit 134 of the Nodo 120, and a.
- the TS synchronization unit 145 detects a trigger for synchronizing the timing of the time slot of the optical switch node from the signal received by the control signal reception unit 133, counts the elapsed time after receiving the trigger information notification, and triggers In accordance with the time slot information notified together with the information, the TS transmission / reception unit 146 and the optical TS-SW unit 144 are instructed to transmit data in the time slot assigned to the own node. In response to the switching instruction from the TS synchronization unit 145, the optical TS-SW unit 144 switches the route, and the TS transmission / reception unit 146 transmits data from the buffer to the optical TS-SW unit 144.
- FIG. 68A shows the configuration of the master node 120 in the time synchronization type
- FIG. 68B shows the configuration of the optical switch node 121 in the time synchronization type.
- solid arrows indicate data signal paths
- broken arrows indicate control signal paths.
- the time-synchronized master node 120 has the same configuration as that of the trigger type shown in FIG. 67A, but includes a time distribution unit 39 that distributes the local time of its own node to each optical switch node. It is different from that shown in FIG. 67A.
- the TS start distribution unit 137 instead of generating a trigger pulse, specifies the time at which the optical switch node starts an operation based on the TS information, and the TS information distribution unit 138 stores the TS information. Delivered to each optical switch node.
- the time-synchronous optical switch node 121 has the same configuration as the trigger type shown in FIG. 67B, but includes a TS information management unit 148 that holds the received time slot information. It is different from what is shown.
- the TS synchronization unit 145 detects a control signal for synchronizing the timing of the time slot of each node, notifies a time stamp value in the signal to a time counter (not shown), and the time slot start time ( Thereafter, in accordance with the TS start time and backup), the TS transmission / reception unit 146 and the optical TS-SW unit 144 are instructed to transmit data in the time slot assigned to the own node.
- each optical switch node In 121 since the master node 120 simultaneously distributes the time slot information and the trigger indicating the start of the time slot to each optical switch node 121, each optical switch node In 121, the TS information management unit 148 need not be provided.
- FIGS. 67A, 67B, 68A, and 68B it is possible to avoid providing the demultiplexing units 131 and 141 and the multiplexing units 132 and 142 by increasing the number of fibers in the transmission path. it can.
- the master node 120 collects traffic information from each optical switch node 120.
- traffic information from a plurality of optical switch nodes 121 does not collide with each other in a control fiber or wavelength. It is necessary to. Therefore, the master node 121 also performs time slot allocation for control signal transmission. Therefore, in this embodiment, each optical switch node 121 starts the control signal time slot increment from the moment of receiving the control signal transmission TS allocation signal. The time slot number at the start is set to 1, and the slot number is incremented for each unit time slot. When the incremented slot number becomes the time slot number described in the control signal transmission TS allocation signal, this optical switch node can transmit the traffic information (TS transmission / reception unit unit) to the master node 120.
- This time slot is periodic, and each optical switch node 121 can transmit a control signal at a constant period.
- FIG. 69 shows a procedure for sending traffic information from the optical switch node 121 to the master node 120 by such control. This procedure will be described.
- the master node 120 assigns a control time slot to each optical switch node 121 by a control signal.
- the optical switch node 121 receives the data packet transmitted from the external communication device 190, and measures the traffic volume.
- the optical switch node 121 transmits the traffic amount to the master node 120 as traffic information.
- step 214 the master node 120 grasps the traffic amount from the traffic information, and calculates a time slot allocation amount (time slot length) according to the traffic amount.
- step 215 the calculated time slot length is notified to the optical switch node 121.
- step 216 the optical switch node 121 sets a time slot having the notified time slot length and transmits data.
- the traffic information notification there is one that notifies the data size accumulated in the buffer of the TS transmission / reception unit 146 and the estimated time until the buffer overflow occurs.
- the predicted time until the buffer overflow occurs is an estimate of how many seconds the buffer of the TS transceiver 146 will cause the buffer overflow.
- a large TS can be preferentially allocated to the virtual queue in the TS transmission / reception unit in which buffer overflow may occur, and buffer overflow can be avoided.
- FIG. 70 is a diagram for explaining prediction of buffer overflow. It is assumed that a plurality of virtual queues 1 to N are set in the TS transmission / reception unit 146.
- the number of seconds after which the buffer overflows is predicted from the degree of decrease in the remaining memory portion in the virtual queue. If the time interval between time t and time t + 1 is ⁇ T, and the remaining memory of the virtual queue decreases by ⁇ data during this time, [(remaining memory amount at time t + 1) / ⁇ data] ⁇ ⁇ T is calculated until the buffer overflow occurs. It will be the estimated time.
- the master node 120 may be notified of (a) the current total accumulated data amount and (b) the maximum TS amount that does not exceed the set threshold value.
- FIG. 71 shows the relationship between the threshold, the current total accumulated data amount expressed as an uplink data frame (indicated by [a]), and the maximum TS amount not exceeding the threshold (indicated by [b]). Yes.
- FIG. 72 shows various examples assumed when TS start distribution and TS synchronization are performed by a trigger.
- the trigger and the data are transmitted on the same path by wavelength multiplexing, for example.
- FIG. 73 illustrates the relationship between time slots and triggers.
- An example in which a trigger is output for each time slot as shown in No. 1011 of FIG. 72 is shown in * 1 of FIG. 73, and Nos. 1012 and 1013 in FIG.
- An example in which a trigger is output for each TS cycle as shown in FIG. 73 is shown by * 2 in FIG. 73, and an example in which a trigger is output every N times the TS cycle as shown in Nos. 1014 and 1015 in FIG. 73 * 3.
- FIG. 74 shows an operation example of transmission from node A to node B, node A to node C, and node B to node C in the case of No 1011 in FIG. 72 (in the case of * 1 in FIG. 73).
- the master node 120 sets TS information in each optical switch node.
- the TS number of the time slot that is to be inserted (ADD) into one wavelength is not duplicated in each node.
- the TS length is set to 1 / integer of the ring length.
- the ring length here is a propagation delay when a signal goes around the ring once.
- the master node 120 transmits triggers at TS length intervals.
- the trigger makes one round of the ring, but the trigger that makes one round ends at the master node 120.
- the trigger is sequentially received by each node. As shown in [3], when the node A receives the trigger, it performs the operation of the first row of the TS information after the offset time (here, 5 counts) (inserts the data of the destination B in the time slot TS0 (ADD )). Similarly, when the next trigger is received, the operation of the second row of TS information is performed. When the next trigger is received, the operation in the third row of TS information is performed (data of destination node C is ADDed to time slot TS2).
- Node B Since the trigger propagates on the ring, it is also received by Node B. However, as shown in [4], when Node B receives the trigger, it performs the operation of the first row of TS information after the offset time (5 counts). Implement (branch (DROP) data of time slot TS0). When the next trigger is received, the operation of the second row of the TS information is similarly performed (data of the destination node C is added to TS1).
- FIG. 75 shows an operation example in which transmission is performed from node A to node B, from node A to node C, and from node B to node C in the case of No. 1012, 1013 in FIG. ing.
- the master node 120 sets TS information in each optical switch node 121.
- the TS numbers of the time slots that are ADDed to one wavelength are not duplicated in each of the nodes A to C.
- the TS length is set so that the TS cycle (TS length ⁇ m) is 1 / integer of the ring length.
- the master node 120 transmits a trigger at a TS cycle interval.
- the trigger that makes one round of the ring is terminated by the master node 120.
- FIG. 76 shows an operation example of transmitting from node A to node B, from node A to node C, and from node B to node C in the case of No. 1014 or 1015 in FIG. 72 (in the case of * 3 in FIG. 73).
- the master node 120 sets TS information in each of the nodes A to C as shown in [1].
- the TS number of the time slot that is ADDed to one wavelength is not duplicated in each node.
- the TS length is set so that the TS cycle (TS length ⁇ m) is 1 / integer of the ring length.
- the master node 120 transmits at intervals of TS period ⁇ N.
- the trigger that makes one round of the ring is terminated by the master node 120.
- the node A receives the trigger, as shown in [3], the node A sequentially executes the TS information from the first line to the m-th line after the offset time (here, 5 counts). The operation from the 1st line to the m-th line of the TS information is repeated until the next trigger comes.
- the TS information is repeatedly executed from the first line to the m-th line after the offset time.
- the node B sequentially executes the TS information from the first line to the m-th line after the offset time (5 counts here) as shown in [4] until the next trigger comes. This is repeated.
- the TS information is repeatedly executed from the first line to the m-th line.
- FIG. 77A shows such a network configuration.
- the TS length or the TS cycle may be set to 1 / integer of the ring length (the TS length also when the trigger output interval is the TS length). Is an integer of the ring length, and when the trigger output interval is TS period or TS period ⁇ N, the TS period is set to 1 / integer of the ring length). Accordingly, the node A can receive the data transmitted by the node C by the trigger newly transmitted by the master node 120.
- the transmission / reception timing of each node's time slot may shift due to clock fluctuations.
- the transmission / reception timing of the time slot may shift.
- FIG. 78 illustrates a time slot timing shift.
- the clocks match, the timings of the time slots transmitted and received by the nodes 120 and A to C are the same, but the clock becomes fast like node A or slow like node B due to clock fluctuation.
- the timings of the time slots TS1 and TS2 may be shifted, and the time slots may overlap between the nodes A to C. Therefore, in order to prevent data collision from occurring even when such clock fluctuations occur, as shown in FIG. 79, in consideration of overlapping time slots due to clock fluctuations, guarding is performed before and after the data in the clock slots. What is necessary is just to set time.
- FIG. 80A shows the configuration of the optical switch node 121A in the case of a unidirectional ring.
- the description of the traffic information transmission unit is omitted, and this optical switch node 121A is equivalent to that shown in FIGS. 67B and 68B.
- FIG. 80B shows a configuration of an optical switch node 121B adapted to a bidirectional ring.
- each optical switch node 121A and 121B has the TS information of the TS information management units 148a and 148b corresponding to the transmission / reception direction of the trigger. And data transmission / reception and SW switching in the same direction as the transmission / reception direction of the trigger.
- the time synchronization type is characterized in that the TS start is designated by time.
- the trigger type synchronization described above it is necessary to transmit the trigger and the data through the same route.
- the TS start time can be set in advance, and even when the TS start time is distributed. There is no need to distribute data along the same route.
- As a method of setting the time of each node in the time synchronization type (a) a case where a delay time corresponding to the data transmission path is added to the time of the master node 120 and (b) the master node 120 is set. And a common time may be set for the entire optical switch node 121.
- a characteristic of the time setting (time with delay difference) in (a) is that the value of the TS start time can be made common to all nodes.
- time setting based on time with delay difference will be described.
- TS start distribution and TS synchronization are set according to a time with delay difference
- a time with a time difference corresponding to the delay time between the nodes is set for each node.
- FIG. 81 there are several methods for setting the TS start distribution and TS synchronization in this case.
- control signal for setting as a combination of information distributed by the master node 120, as shown by a symbol SS20 in FIG. As indicated by SS21 to SS23, there are some which transmit these separately. When transmitted separately, the time stamp can be sent independently, so that the deviation of the counter value can be corrected.
- FIG. 83A shows an example in which the control signal is transmitted counterclockwise as indicated by the arrow Y1, and when the master node 120 transmits a control signal with a time stamp at the local time t, the node 121a, the node 121b, and the node 121c are transmitted. A delay is added during transmission.
- the time stamp of the control signal is set in the time counter of its own node. As a result, the local time is set to a time shifted by the delay time.
- FIG. 83B shows an example in which a control signal is transmitted clockwise from the master node 120 as indicated by an arrow Y2.
- the master node transmits a control signal with a time stamp, both counterclockwise and clockwise.
- the delay in the clockwise direction and the delay in the counterclockwise direction are different for each node. Therefore, each node maintains a clockwise counter for counterclockwise and counterclockwise counterclockwise, and the local counterclockwise and counterclockwise are local. Manage time.
- FIG. 84A shows the configuration of the optical network system
- FIG. 84B shows a time setting time chart in time synchronization based on time with delay difference.
- the master node 120 controls the optical switch nodes (also simply referred to as switch nodes or nodes) 121a and 121b by specifying the optical switch switching time and the packet transmission time.
- the node 120 needs to set the time for each of the switch nodes 121a and 121b.
- the master node 120 transmits a time setting packet with a time stamp to the optical switch node.
- each optical switch node 121a, 121b sets the value described in the time stamp as the current time of its own node when receiving the time setting packet.
- the master node 120 since the master node 120 needs to know in advance the one-way propagation delay time to each of the nodes 121a and 121b, it is necessary to actually measure the delay.
- the propagation delay time can be measured by reciprocally transmitting / receiving the time stamp given by the master node 120 to the same path between the master node 120 and the optical switch nodes 121a and 121b.
- 85A and 85B are diagrams illustrating such delay time measurement. As shown in [1] in the figure, first, the master node 120 transmits a time setting packet with a time stamp, and each optical switch node 121a, 121b that receives the packet sets [2], [3].
- a delay measurement packet including a time stamp given by the master node 120 is returned as a response packet to the master node 120.
- the master node 120 calculates the one-way propagation delay time from the difference from the response packet arrival time to the time of the first time stamp. Actually, since there is a processing delay in the optical switch, it is necessary to consider the processing time as shown in the figure.
- FIG. 86A shows an optical switch node 121A corresponding to a unidirectional ring.
- this optical switch node 121A omits the description of the traffic information transmission unit, and in order to clarify the time synchronization by the TS synchronization unit 145, a time counter 149 and an internal clock 150 are provided. Although described, it is substantially the same as that described in FIG. 68B.
- the control signal receiving unit, the TS information management unit, and the time counter are respectively counterclockwise and clockwise. Two are provided.
- a control signal receiving unit 143b, a TS information management unit 148b, and a time counter 149b are shown for clockwise rotation.
- the master node 120 transmits control signals clockwise and counterclockwise on the ring, and each optical switch node 121A, 121B is based on TS information of the TS information management unit corresponding to the transmission / reception direction of the control signal and the time counter. Perform the action. For example, when a clockwise control signal is received, the clockwise TS information management unit 48b is used.
- each node transmits data in the same direction as the direction in which the time stamp was sent because the local time with a delay time difference is set for the master node.
- reception time of local time of receiving node “transmission time of local time of transmitting node”.
- “reception time of the local time of the receiving node” “local time of the transmitting node” Transmission time ”+“ time of one round of ring (a + b + c + d) ”.
- DROP In order to branch (DROP) this data at the master node 120, it is necessary to set the DROP switching time at the master node 120 to “TS start time + one ring round time”. Similarly, for transmission / reception across the master node 120 such as from the node 121c to the node 121a, the DROP switching time is set to “TS start time + round time of the ring”, or the TS is reversed so as not to cross the master node 120. It is necessary to make settings.
- the delay time is measured in advance with a measuring instrument such as an OTDR (optical pulse tester: OpticalOptTime Domain Reflectmeter), and the measurement result is manually transmitted to the TS information management unit.
- a method of setting and a method of calculating from a control signal that makes one round of the ring There are a method of setting and a method of calculating from a control signal that makes one round of the ring.
- a control signal with a time stamp is generated and transmitted by the master node, and the control signal that has made one round of the ring is transmitted to the delay measurement function unit (not shown) of the master node. ), And a value obtained by subtracting the time stamp value from the reception time may be calculated as the ring one round time.
- FIG. 88 shows an operation example of distribution of local time and TS start time in the time synchronization type configuration with time with delay difference in the case of No. 2013 in FIG.
- all TSs are set in advance.
- the master node 120 sets time slot information in the node A.
- the master node 120 transmits a control signal including a TS start time and a time stamp value for each TS cycle.
- the node A sets its own time counter to the time stamp value of the control signal.
- the node A starts operation in order from the time slot TS0 when the time counter reaches the TS start time.
- the operation of TS information is performed.
- ADD is performed in the time slot TS0 of the time counters 100 to 120, and ADD is performed in the time slot TS2 with the time counters 140 to 160.
- Node A repeats this operation until the next TS start time is transmitted.
- the node B receives the control signal again, the node B sets the time counter of its own node to the time stamp value of the control signal.
- the node B operates in order from the time slot TS0 when the time counter reaches the TS start time.
- the common time is time information that can be obtained in each node irrespective of other nodes.
- Such a common time is a single time system and does not depend on each propagation delay in each node.
- These include high-precision internal clocks provided at each node (for example, atomic time standards such as cesium oscillators and rubidium oscillators, or crystal oscillators), and external clocks that can be enjoyed equally at each node.
- atomic time standards such as cesium oscillators and rubidium oscillators, or crystal oscillators
- external clocks that can be enjoyed equally at each node.
- a GPS clock or a JJY clock Japanese standard radio clock
- FIG. 90A shows a configuration of an optical network system
- FIG. 90B shows a procedure for distributing a common time to each node using GPS and measuring a delay.
- a GPS receiver is connected to each of the master node 120 and each optical switch node 121a, 121b, and an accurate time obtained by GPS is set as a local time of each node 120, 121a, 121b. It has become.
- the master node 120 transmits a delay measurement packet to which the time (T1) inside the master node is given as a time stamp. Each node receives this delay measurement packet.
- propagation delay time current time-time from the time stamp value (T1) of the received packet and the current time at the own node. The propagation delay time is calculated as the stamp value.
- each node 121a, 121b notifies the measured propagation delay time to the master node 120 as shown in [3].
- the time synchronization based on this common time does not need to use a duplex control signal line (clockwise and counterclockwise control lines), and can be realized by a single configuration, that is, a one-way control line.
- a duplex control signal line clockwise and counterclockwise control lines
- the propagation delay time measured without collision can be transmitted.
- the TS start time when time synchronization is performed based on the common time will be described.
- the time synchronization based on the common time since the local time of each node is exactly the same, it is necessary to consider the delay between nodes in order to determine the start time of the time slot so that data collision does not occur. That is, assuming that the TS start time transmitted by the master node is t, each node needs to newly set a value obtained by adding the delay time with the master node to the transmitted TS start time t.
- 91A and 91B illustrate the determination of such a TS start time. In this description, as shown in FIG.
- FIG. 91A [1] is assigned to the ring-connected master node 120, [2] is assigned to the node 121a, [3] is assigned to the node 121b, and the nodes [1] to [3] are assigned.
- FIG. 91B the same reference numerals [1] to [3] are shown to represent nodes.
- the TS start time of the master node [1] is shown in FIG. 91B at time t1.
- FIG. 92 is a time sequence diagram showing an operation of grasping the topology when the control ring is single.
- the master node 120 In order to grasp the connection configuration between the optical switch nodes 121 connected to the ring network and the terminal (external communication device) 190 connected to the optical switch node 121, the master node 120 First, an ID (identification number) of the switch, an ID of an interface (TS transmission / reception unit) of the switch, and the like are requested (ID request S1), and the optical switch node 121 responds to the ID request with an ID response. Returns S2. Thereafter, the master node 120 requests the optical switch node 121 for the address of the terminal (external communication device) 190 connected to the optical switch node 121 as a management terminal address request (management terminal address request S3). ).
- the optical switch node 121 is notified S4 each time the terminal address is updated from the terminal 190 connected thereto, and stores each terminal address 190m. Through S5, the master node 120 is notified of the address of the terminal (external communication device) 190 being managed. Thereby, the master node 120 has the switch ID of the optical switch node 121 connected to the ring network, the ID of the TS transceiver, the port number connected to the TS transceiver in the optical switch node 121, and the optical switch node 121. 2, the port number used for link establishment and the address of the terminal 190 existing under the optical switch node 121 are grasped.
- each optical switch node 121 is connected in a daisy chain after receiving a control signal from the master node 120 in order to avoid data collision for topology management. Specifically, the information requested from the master node 120 is added to the back of the received packet and transmitted to the optical switch node 121 at the next stage.
- each optical switch node needs to send data to the next optical switch node or DROP via the optical TS-SW unit, and send a trigger (or control signal) to the next optical switch node. It needs to be given to the control signal receiving unit of the own node.
- the transmission configuration of the trigger and the control signal includes variations as shown in FIGS. 93A to 93D, for example.
- the control signal is also referred to as a trigger.
- the trigger is also passed through the optical TS-SW unit 144.
- the trigger is branched by the optical TS-SW unit 144 and supplied to the control signal receiving unit 143.
- the optical TS-SW unit 144 is set to broadcast.
- FIG. 93C shows that the trigger is not passed through the optical TS-SW unit 144, and the control wavelength ⁇ c is subjected to OE (light / electricity) -EO (electricity / light) conversion to obtain an electric signal.
- the trigger is branched, or the trigger is branched using an optical coupler, and is supplied to the control signal receiver 143.
- the control signal receiving unit 143 triggers the control wavelength ⁇ c independently of the data. Branched.
- connection configuration between the optical TS-SW unit and the TS transmission / reception unit includes variations as shown in FIGS. 94A to 94C, for example.
- the TS transmission / reception unit 146 has one output and one input. In the TS transmission / reception unit 146, transmission data is stored in a separate queue for each destination.
- the TS transmission / reception unit 146 is connected to the optical TS-SW unit 144 by ADD and DROP one port at a time.
- the one shown in FIG. 94B is one output for each queue of the TS transmitter / receiver 146, and the input is one for the entire TS transmitter / receiver 146.
- transmission data is stored in a separate queue for each destination.
- the connection at the optical TS-SW unit 144 of the TS transmission / reception unit 146 uses one ADD port for each queue.
- One DROP port is used for the entire TS transceiver 146. Since an ADD port is used for each queue, data with different destinations can be output simultaneously if the ring transmission directions are different.
- FIG. 94C shows a configuration in which a buffer is provided in the TS transmission / reception unit 146 and data is received from the two DROP ports in the buffer with respect to that shown in FIG. 94B. Since two DROP ports are used, simultaneous reception from both the clockwise and counterclockwise directions in the ring is possible.
- the optical TS-SW unit 144 includes an input port and an output port, accommodates the data line of the ring network, changes the connection relationship between the input port and the output port according to an instruction from the master node 120, At the same time, processing such as wavelength conversion is also performed as necessary.
- Such an optical TS-SW unit 144 can be configured as a wavelength routing type switch by wavelength conversion, or as a broadcast and select type spatial switch, as will be described below with a specific example. You can also.
- Data lines accommodated in the optical TS-SW unit 144 include a data line that is wavelength-multiplexed and a data line that is not wavelength-multiplexed.
- 95A and 95B are diagrams showing an outline of the optical TS-SW unit 144 configured as a wavelength switch.
- FIG. 95A shows a case where a wavelength-multiplexed data line is accommodated
- FIG. 95B shows a data line that is not wavelength-multiplexed. The case of accommodating is shown.
- a demultiplexing unit 141 is installed before the input of the optical TS-SW unit 144, and the data input by wavelength multiplexing is, for example, N wavelengths. Are applied to the input ports indicated by IN 1 to IN N. Then, a multiplexing unit 142 is installed at the subsequent stage of the optical TS-SW unit 144, and optical signals from the N output ports OUT 1 to OUT N of the optical TS-SW unit 144 are wavelength-multiplexed, The data is transmitted to the next node (next node).
- the optical TS-SW unit 144 also has functions of optical signal insertion (ADD) and optical signal branching (DROP), and an ADD port is provided as an input port of the optical TS-SW unit 144. Port is provided as an output port of the optical TS-SW unit 144.
- ADD optical signal insertion
- DROP optical signal branching
- the demultiplexing unit and the multiplexing unit are not provided.
- the number of data lines in the ring is equal to the number of terminals (ports) obtained by subtracting the number of ADD / DROP interfaces in the optical switch.
- FIG. 96 shows an example of the basic configuration of the optical TS-SW unit 144 configured as a wavelength switch.
- the optical TS-SW unit 144 includes one or a plurality of input ports and a plurality of output ports.
- the optical demultiplexer 141 demultiplexes the wavelength-multiplexed input optical signal for each wavelength, and the light input to each input port.
- AGW array waveguide grating
- DROP branch
- TWC tunable wavelength converter
- TWC [A] 1 to TWC [A] 3 for performing wavelength conversion at the same time
- a multiplexer (multiplexing unit) 142 that performs wavelength conversion so that an optical signal is output to the same port at a demultiplexing unit in the next stage, and a fixed wavelenght converter (FWC) 1 to FWC8, and an AWG 144i.
- Branch at (DRO P) and an optical receiver 144j for receiving the optical signal an optical signal transmitted by wavelength multiplexing from the previous stage is demultiplexed into wavelengths ⁇ 1 to ⁇ 8 by a demultiplexer 141, and these demultiplexed optical signals are respectively transmitted from the AWG 144i via TWC1 to TWC8. Is given to the input port. Apart from these, an optical signal to be inserted is provided to the input port of the AWG 144i via the TWC [A] 1 to TWC [A] 3.
- the AWG 144i has an output port used for branching (DROP), and an optical receiver 144j is connected to the output port.
- the optical receiver 144j includes a photoelectric element (APD) that performs photoelectric conversion, a limiting amplifier (LIM) that absorbs a power difference between optical signals, and a clock that absorbs a phase difference between the optical signals.
- a data recovery circuit (CDR) is connected in series in this order, and receives an optical signal by absorbing a power difference / phase difference between signals.
- the wavelength ⁇ 8 is a fixed wavelength for control.
- Each channel of ADD and DROP is also used for control, and is connected to a switch control unit for controlling the optical TS-SW unit 144.
- FIG. 97A shows an example of the configuration of the TWC.
- a thick solid line indicates an optical signal
- a thick dotted line indicates an electric signal.
- the TWC includes an optical burst receiver 170 composed of APD, LIM, and CDR, a variable wavelength light source 171 that can change an oscillation wavelength in order to change an output destination in the AWG, and an optical burst receiver 170.
- a modulator 172 that modulates the light from the wavelength tunable light source 171 by the electrical signal.
- the LIM is provided to absorb loss differences due to different transmission path lengths and the output power difference of the light source
- the CDR is provided to absorb phase differences due to different transmission path lengths.
- Such a TWC can recover the power of light attenuated by long-distance transmission by performing optical-electrical-optical conversion. By using the TWC, an optical amplifier becomes unnecessary.
- FIG. 97B shows an example of the configuration of the FWC.
- a thick solid line indicates an optical signal
- a thick dotted line indicates an electric signal.
- the FWC is used for wavelength conversion so that the wavelength of the passing data and the ADD data is the same so as to be output to the same port in the optical demultiplexing unit 170 of the APD, LIM and CDR, and the demultiplexing unit in the next stage.
- the LIM is provided to absorb a difference in loss and a difference in output power of the light source for each port in the AWG
- the CDR is provided in order to absorb a phase difference due to different transmission paths in the AWG. It has been.
- the wavelength switch type optical TS-SW unit may have various configurations.
- FIG. 98 shows what kind of configuration is assumed. Here, how many fibers per AWG are provided, whether FWC is provided, whether a port for ADD connection is provided in the front or back of the AWG, wavelength switching is performed between the fibers, or in the fiber It shows what kind of configuration is possible depending on whether or not. If the FWC is not used, the cost can be reduced accordingly. If the fiber-to-fiber wavelength exchange is used, communication is possible even if a single optical fiber is broken, so that fault tolerance is improved. In addition, more flexible operation is possible with intra-fiber wavelength conversion.
- FIG. 99 corresponds to the case [1] in FIG. 98, and uses a K-duplex ring with K fibers and uses N wavelengths per ring, and the configuration of the optical TS-SW unit 144
- An example is shown.
- an example of how wavelength exchange is performed between K fibers when no FWC is deployed is shown.
- kN wavelengths ⁇ i (0 ⁇ i ⁇ kN ⁇ 1) by setting a plurality of wavelengths having the same value (i MOD N) to the same wavelength, the signal after switching can be obtained without introducing FWC.
- the wavelength conversion unit (TWC) at the next stage inputs the same wavelength unit.
- kN ⁇ kN orbiting AWGs 141a and 141b are provided, and N TWC1 to TWC8 and k number of orbiting 1 ⁇ N AWG144i as demultiplexing units are provided at the preceding stage, and the latter stage is provided.
- k output ports 144k and 144l are provided.
- FIG. 100 corresponds to the case of [1a] in FIG. 98, and performs wavelength switching between fibers in a 1ADD / 1DROP configuration that does not use FWC in the case of a K-double ring and N wavelengths per ring.
- An example is shown.
- kN wavelengths ⁇ i (0 ⁇ i ⁇ kN ⁇ 1) a plurality of wavelengths having the same value (i MOD N) are set to the same wavelength, and a kN ⁇ kN cyclic AWG 144i is provided, and k pieces are provided in the preceding stage.
- Cyclicity 1 ⁇ N AWGs 141c and 141d, k (N ⁇ 2) through / branch (DROP) TWC1 to TWC4, and one add (ADD) TWC [A] are provided. .
- the k circular 1 ⁇ N AWGs 141c and 141d function as a demultiplexing unit that also performs wavelength conversion.
- an optical receiver 144j On the output side of the kN ⁇ kN recursive AWG 144i, an optical receiver 144j that is a branching interface and k (N ⁇ 1) ⁇ N multiplexing units 142c and 142d are provided.
- FIG. 101 corresponds to the case of [1a] in FIG. 98.
- inter-fiber wavelength switching is performed in a 1ADD / 1DROP configuration that does not use FWC.
- An example is shown in which the control wavelength is further used.
- kN wavelengths ⁇ i (0 ⁇ i ⁇ kN ⁇ 1) a plurality of wavelengths having the same value (i MOD N) are set to the same wavelength, and a kN ⁇ kN cyclic AWG 144i is provided, and wavelength conversion is performed in the preceding stage.
- K ⁇ 1 AWGs 141c and 141d functioning as a demultiplexing unit, k (N ⁇ 2) TWC1 to TWC4 for Through / Drop (DROP), and one insertion (ADD) ) TWC [A].
- an optical receiver 144j that is a branching interface and k (N ⁇ 1) ⁇ N multiplexing units 142c and 142d are provided. Further, in this configuration, a control wavelength for performing switch control is prepared, and in order to ensure the reachability of the control wavelength, a coupler 144r is connected to each demultiplexing unit, and copying is performed by each switch. .
- FIG. 102 corresponds to the case of [1b] in FIG. 98, and performs wavelength switching between fibers in a 1ADD / 1DROP configuration that does not use FWC in the case of a K-double ring and N wavelengths per ring.
- An example is shown.
- kN ⁇ kN circular AWG 144i is provided, and in the preceding stage, k circular 1 ⁇ N AWGs 141c and 141d functioning as a demultiplexing unit that also performs wavelength conversion, and k (N ⁇ 2) through / Branches (DROP) TWC1 to TWC4 are provided.
- FIG. 103 corresponds to the case of [2] in FIG. 98, and is an inter-fiber wavelength exchange and an intra-fiber wavelength exchange without deploying an FWC in the case of a K-double ring and using N wavelengths per ring.
- the wavelength conversion unit at the next stage inputs the same wavelength unit.
- kN ⁇ kN recursive AWG 144i is provided, and TWC1 to TWC8 and k recursive 1 ⁇ N AWGs 141c and 141d as demultiplexing units are provided in the preceding stage, and k pieces are provided in the subsequent stage.
- N ⁇ 1 star couplers 144s and 144t and k output ports 144k and 144l are provided.
- FIG. 104 corresponds to the case of [3] in FIG. 98, and uses a 1-ADD / 1DROP configuration in which one fiber per AWG is used while using k-fold rings (N wavelengths per ring) and FWC is not used.
- An example using a control wavelength is shown.
- kN wavelengths ⁇ i (0 ⁇ i ⁇ kN ⁇ 1) a plurality of wavelengths having the same value (i MOD N) are set as the same wavelength, and k N ⁇ N recursive AWGs (two 4 AWGs in the figure) are used.
- ⁇ 4 orbiting AWG) 144h and 144i are provided.
- k revolving 1 ⁇ N AWGs 142c and 142d functioning as a demultiplexing unit that also performs wavelength conversion
- k (N ⁇ 2) passes (Through ) / Branch (DROP) TWC1 to TWC4 and one insertion (ADD) TWC [A].
- the insertion TWC [A] is connected to the upper 4 ⁇ 4 AWG 144h in the drawing.
- the optical receiver 144j which is a branching interface, and k N ⁇ N multiplexing units 142c and 142d are provided in the subsequent stage of the k N ⁇ N revolving AWGs 144h and 144i.
- the optical receiver is connected to the lower 4 ⁇ 4 AWG 144i in the drawing.
- An ADD / DROP TWC [A / D] between the fibers is provided so as to connect the output of the upper 4 ⁇ 4 AWG 144h and the input of the lower 4 ⁇ 4 AWG 144i.
- a coupler 144r is connected to each demultiplexing unit, and copying is performed by each switch.
- FIG. 105A shows a specific example of the basic configuration shown in FIG. 96.
- a configuration in which a double ring with four wavelengths per ring is used and ADD / DROP is performed on one channel is shown.
- As the AWG 144i a 9 ⁇ 9 AWG 144g is used, and FWC1 to FWC4 + FWC1 to FWC4 are provided on the output ports of the AWG 144g excluding the DROP port, respectively.
- FIG. 105B shows the wavelength requirements in each TWC [A], TWC1 to TWC8 provided on the input side of the AWG 144g.
- FIG. 106A corresponds to the case of [0a] in FIG. 98.
- a double ring with four wavelengths per ring is used, and FWC1 to FWC4 + FWC1 to FWC4 are provided in the subsequent stage of 9 ⁇ 9 AWG 144g.
- a configuration is shown in which ADD / DROP is performed on one channel and wavelength switching is performed within the fiber.
- FIG. 106B shows the wavelength requirements in each TWC [A], TWC1 to TWC8 provided on the input side of the AWG 144g.
- FIG. 107A corresponds to the case of [0b] in FIG. 98.
- a double ring with four wavelengths per ring is used, and FWC1 to FWC8 are provided at the subsequent stage of 9 ⁇ 9AWG144g, and ADD / A configuration is shown in which DROP is performed in one channel, and wavelength switching between fibers and wavelength switching in the fiber are performed.
- FIG. 107B shows the wavelength requirements in each TWC [A], TWC1 to TWC8 provided on the input side of the AWG 144g.
- optical TS-SW unit as a broadcast and select type spatial switch
- FIG. 108 shows a basic configuration of the broadcast and select type optical TS-SW unit 144A.
- the optical signal input by wavelength division multiplexing (WDM) is demultiplexed by the AWG 141, and each demultiplexed wavelength component is transmitted to a plurality of N ⁇ 1SW (switch) 144t by the coupler 144r.
- N ⁇ 1SW 144t signal transmission or blocking control (through control) is performed by a semiconductor optical amplifier (SOA).
- SOA semiconductor optical amplifier
- One of N ⁇ 1SW 144t is a DROP port.
- the output of the remaining N ⁇ 1SW 144t switch and the output from the ADD TWC [A] 1 are combined by the coupler 142 and transmitted to the next stage as a wavelength multiplexed signal.
- Each N ⁇ 1SW 144t is provided with a semiconductor optical amplifier (SOA) 144u for each input port, an SOA 144w for an output port, and a space switch 144v.
- SOA semiconductor optical amplifier
- N the number of SOAs to be controlled is N 2 .
- FIG. 109 shows another example of the configuration of the broadcast and select type optical TS-SW unit 144B.
- 108 requires a large amount of SOAs 144u and 144w to form N ⁇ 1SW 144t. Therefore, in FIG. 109, wavelength tunable filter 144x is used instead of N ⁇ 1SW 144t in FIG.
- signal transmission or blocking control through control
- 109 can reduce the number of elements to be controlled for the switch from N 2 to N as compared with that shown in FIG.
- time slot transmission node node A
- time slot reception node node B
- the transmission signal from node A arrives at node B with a delay of propagation delay time 301AB between nodes A and B. Therefore, the time slot start timing 301A of the time slots TS1 to TS5 operating at the node A is made earlier by the propagation delay time (+ guard band) 301AB than the time slots TS1 to TS5 operating at the node B. ing.
- the time slots TS1 to TS5 operating at the node A and the time slots TS1 to TS5 operating at the node B are synchronized.
- time slots TS1 to TS5 operate periodically, and hereinafter, the start timing of the time slot period is referred to as a time slot start position.
- the operation period of each time slot and the length of the time slot are measured by a counter existing in each of the nodes A and B, and can be measured by counting up for each clock of the local clock frequency.
- the multi-ring 302 is configured by connecting an upper ring 303 and a plurality of lower rings 304 at a ring switching point node A.
- the reference time slot (first time slot) 305 is operated at the ring exchange point node A and each node B of the lower ring 304.
- the reference time slot 305 is a time slot synchronized with the time slot operating in the origin node A0 existing in the upper ring 303.
- the origin node A0 is defined as any one of a plurality of nodes connected to the ring as the origin node, and corresponds to the master node described above.
- the reference time slot synchronization method is as follows.
- the synchronization frame transmitted from the origin node A0 at the timing of the reference time slot start position in the origin node A0 (the time value in the origin node when the synchronization frame is transmitted is inserted in the synchronization frame) Is transmitted to each node other than the origin node, and each node other than the origin node receives the synchronization frame from the origin node A0, and sets the time value in the synchronization frame as the current time of its own node.
- each node B of the lower ring 304 starts the reference time slot by receiving the synchronization frame from the origin node A0.
- Ring switching point node A is synchronized with reference time slot (first time slot) 305 in its own node with respect to node B of lower ring 304 where transmission is performed as indicated by TS1 indicated by arrow Y20.
- the time slot (second time slot) 306 for the upper ring 303 shifted by the offset value (delay time) DB is set.
- the offset value DB corresponds to the propagation delay time DB from the node B to the ring exchange point node A shown in the multi-ring 302.
- the time slot 306 for the upper ring 303 of the node B is synchronized with the reference time slot 305 of the ring exchange point node A.
- the reference time slot 305 is used for downlink communication indicated by arrow Y20 from the upper ring 303 to the lower ring 304, and transmission is performed as indicated by TS5 indicated by arrow Y21 from the lower ring 304 to the upper ring 303.
- TS5 is a data insertion target time slot.
- the TDM control timing used for time slot transmission (ADD) to the upper ring 303 and time slot reception (DROP) from the upper ring 303 is separated.
- the time slot 306 for the upper ring of each node B of the lower ring 304 is synchronized with the reference time slot 305 of the ring switching point node A, and for the upstream communication from the lower ring 304 to the upper ring 303,
- time slots can be exchanged between rings without occurrence of a time slot collision.
- the required guard band length can be shortened. Note that a conceptual diagram of a logical configuration using uplink and downlink time slots is shown (arrow Y22).
- Any origin node A0 starts a reference time slot and synchronizes the reference time slot with each node other than the origin node.
- the reference time slot synchronization method is as follows.
- the synchronization frame transmitted from the origin node A0 at the timing of the reference time slot start position in the origin node A0 (the time value in the origin node when the synchronization frame is transmitted is inserted in the synchronization frame) Is transmitted to each node other than the origin node, and each node other than the origin node receives the synchronization frame from the origin node A0, and sets the time value in the synchronization frame as the current time of its own node. Start the reference time slot. As a result, the reference time slot 308 is synchronized between the origin node A0 and nodes other than the origin node.
- the ring switching point node A sets a time slot 309 for the upper ring synchronized with the reference time slot 308 of the ring switching point node A for each node B of the lower ring 304.
- the ring switching point node A measures the ring one-round delay of the lower ring B.
- D1 time is a delay time of a path from a lower node (for example, B) to an upper node (for example, A)
- D2 time is, conversely, from an upper node A to a lower node B. It is the delay time of the route to go.
- the time slot 309 for the upper ring of each node B of the lower ring 304 is started earlier than the time slot start timing of the reference time slot of each node B of the lower ring 304 itself.
- the time slot start timing of the reference time slot 308 of the ring switching point node A can be matched.
- the method of measuring the lower ring round delay time is as follows: (a) Ring exchange point node A transmits a lower ring round trip delay measurement frame, and (b) Ring exchange point node A makes a round trip around the lower ring. The measurement frame is received, and measurement is performed by subtracting the counter value at the time of (c), (a), and (b) processing.
- Each Node B of the lower ring 304 engraves a time slot (time slot for the upper ring) 309 in which the time slot start timing is shifted by the offset value with respect to the reference time slot 308 of its own node.
- the time slot 309 for the upper ring of each node B of the lower ring 304 and the reference time slot 308 of the ring switching point node A are synchronized.
- the ring exchange point node A transmits a synchronization frame for starting the increment of the time slot 309 for the upper ring to each node B of the lower ring 304.
- the ring switching point node A transmits the lower ring round-trip delay measured in the synchronization frame as a time stamp.
- the transmission timing is the start timing of the time slot period of the reference time slot after measuring the lower ring round time so that the synchronization frame arrives at the head position of the reference time slot in each node B of the lower ring 304.
- each Node B of the lower ring 304 cuts the time slot 309 for the upper ring ahead of the reference time slot 308 of its own node by one cycle of the lower ring described in the synchronization frame. .
- the counter for the time slot for the upper ring is started with an initial value obtained by adding the time stamp value in the synchronization frame to the reference counter value at the time of reception of the synchronization frame.
- a method for synchronizing a reference time slot operating at the origin node A0 and a time slot (strand time slot) used when straddling the origin node A0 in a unidirectional single network will be described below.
- the reference time slot synchronization method is realized by delivering a synchronization frame from the origin node A0 to a node other than the origin node.
- reachability between nodes is ensured by using a control wavelength different from the data wavelength.
- the origin node A0 transmits a synchronization frame at the start start position of the reference time slot in the own node.
- Nodes other than the origin node receive the synchronization frame by copying the control signal with the optical coupler, start the bit counter for the reference time slot from the timing at which the synchronization frame is received, and start the step of the reference time slot.
- This counter is used for counting the time slot period and the time slot length, and counts up for each clock of the local clock frequency.
- the reference time slot operates by delaying the start time of the time slot period by the propagation delay time between nodes, and the reference time slot can be synchronized between the nodes.
- ADD / DROP of time slots between different nodes in the direction in which the synchronization frame is transmitted can be performed.
- the origin node A0 measures the ring one-round delay in order to match the time slot start timing of the straddling time slot of a node other than the origin node in accordance with the reference time slot of the origin node A0. To do. This is because the time slot transmitted from a node other than the origin node arrives at the origin node A0 after D1 time, and the time slot start timing of the reference time slot of the node other than the origin node is relative to the reference time slot of the origin node A0. This is because the sum of the delays of D2 hours is the ring one round delay time (D1 + D2).
- the time slot for straddling nodes other than the starting node starts from the time one cycle of the ring earlier than the time slot start timing of the reference time slot of the own node (node other than the starting node). It is possible to match the time slot start timing of the reference time slot.
- the ring one-round delay time is measured by: (a) the origin node A0 transmits a synchronization frame, (b) the origin node receives a synchronization frame that has rounded the ring, and (c), (a), (b) Measure by subtracting the counter value at the time of processing. (3) The setting of the straddling time slot synchronized with the reference time slot of the origin node A0 will be described.
- the origin node A0 transmits a synchronization frame for starting the increment of the stride time slot to nodes other than the origin node.
- the originating node A0 transmits the ring one-round delay measured in the synchronization frame as a time stamp.
- the transmission timing is set to the time slot start position of the reference time slot after measuring the ring round time so that the synchronization frame arrives at the time slot start position of the reference time slot of the node other than the origin node.
- the nodes other than each origin node cut the spanning time slot by advancing the ring one round time described in the synchronization frame with respect to the reference time slot of the own node.
- the straddling counter is started with an initial value obtained by adding the time stamp value in the synchronization frame to the reference counter value at the time of reception of the synchronization frame.
- time slot transmission / reception from a node other than the origin node to the origin node A0 becomes possible.
- Each node includes an optical switch unit (optical time slot switch unit) 311, a buffer unit 312, a control information transmission unit 313, a reference TS synchronization unit 314, a delay measurement unit 315, a multiple TS management unit 316, and a counter
- optical switch unit optical time slot switch unit
- buffer unit 312 a buffer unit 312
- a management unit 317, an internal clock unit 318, a TS control unit 319, a TS amount update time calculation unit 320, and a control information reception unit 321 are provided.
- symbol a is a delay measurement result
- b is a clock
- c is a reference time
- d is a current time
- e is time stamp information from another node
- f is assigned TS information
- g is time stamp information in each TS
- h is TS transmission timing
- i is the optical switch switching timing
- j is the buffer storage amount
- k is the start start position of the reference TS amount
- l is the TS change information
- m is the TS information and TS switching timing
- n is the start start timing of multiple TSs It is.
- the optical switch unit 311 performs ADD / DROP of time slots.
- the control information receiving unit 321 receives the control signal dropped by the optical switch unit 311.
- the buffer unit 312 includes a buffer that accumulates data input from an external device (not shown), transmits data from the buffer TX to the optical switch unit 311, and receives data from the optical switch unit 311 via RX. Send to external device.
- the control information transmission unit 313 transmits the data amount accumulated in the buffer of the buffer unit 312 and the time counter value inside the counter management unit 317 to the origin node.
- the reference TS synchronization unit 314 engraves a time slot (reference time slot) with a fixed period from the time set by the origin node (the time when the synchronization frame is received from the origin node).
- the delay measurement unit 315 measures and measures the propagation delay time between the other nodes from the time stamp in the control signal (delay measurement frame) from the other node and the time counter value in the counter management unit 317.
- the propagation delay time between each node is calculated from the propagation delay time with other nodes, and an offset value for determining the start timing of the time slot of each node is obtained.
- the multiple TS management unit 316 manages time slots in which the start timings of the offset values are shifted from the reference time slot of each node according to the offset value from the delay measurement unit 315. In addition, the multiple TS management unit 316 shifts the start timing of the offset value with respect to the reference time slot in accordance with the offset value included in the control signal (multiple time slot start frame) from another node, so that the time slot has a fixed period. Engrave. In addition, the multiple TS management unit 316 stores the time slot position assigned to each time slot.
- the counter management unit 317 sets the time stamp in the synchronization frame received from the origin node as the initial time counter value, and increments the time counter value according to the clock from the internal clock unit 318 from the time when the synchronization frame is received.
- the internal clock unit 318 supplies a clock for advancing the time counter value existing in the counter management unit 317 to the counter management unit 317.
- the TS control unit 319 compares the time counter value in the counter management unit 317 with the timing value described in the time slot processing scenario according to the time slot processing scenario in the multiple TS management unit 316, and the optical switch unit 311 Time slot transmission and time slot switch operations are controlled for the buffer unit 312.
- the TS control unit 319 controls transmission of a delay measurement frame and a plurality of time slot start frames, which will be described later.
- the TS amount update time calculation unit 320 calculates a time slot amount common to a plurality of time slots and a time slot switching timing.
- Each input / output of the optical switch unit 311 and TX (transmission) and RX (reception) in the buffer unit 312 operate according to at least one time slot.
- M-C 331 is a starting node as a master node
- Sub M-C 332a and 332b (332) are ring switching point nodes as sub-master nodes
- S-C 333a to 333c (333) are nodes as slave nodes (described above) Applicable to optical switch nodes other than the master node).
- M-C 331 is a representative node (starting node) that exists on the optical network system.
- M-C331 performs transmission of a synchronization frame that causes the nodes 332 and 333 to start a time slot, and measurement of a propagation delay time between the nodes 332 and 333 and calculation of an offset value.
- the main roles of SubM-C332 are as follows.
- the SubM-C 332 transmits a plurality of time slot start frames for starting a new time slot shifted by the calculated offset value to the time slots already operating in the nodes 332 and 333. It is located at the exchange point and controls the optical switch unit 311 (see FIG. 113).
- the SubM-C 332 engraves a plurality of time slots according to the instruction of the M-C 331. Further, the optical switch unit 311 inside the own node is controlled according to the time slot assigned by the M-C 331.
- SC-333 is a node that is located outside the ring exchange point and controls the optical switch unit 311 and the buffer unit 312 (see FIG. 113).
- the main roles of S-C333 are as follows.
- the S-C 333 cuts a plurality of time slots according to the instruction of the M-C 331. Further, the optical switch unit 311 and the buffer unit 312 in the own node are controlled according to the time slot allocated by the MC 331.
- the upper ring 335 and the two lower rings 336a and 336b are connected by the nodes (ring exchange point nodes) 332a and 332b which are SubM-C, and the starting node is connected to the upper ring 335.
- 331 and an SC (optical switch node) 333c, and lower rings 336a and 336b include nodes (optical switch nodes) 333a and 333b.
- the propagation delay time between nodes is assumed to be “150” between the origin node 331 and the node 332a and “200” between the node 332a and the node 333b.
- the origin node is simply referred to as a node 331
- the ring switching point node is simply referred to as a node 332
- the optical switch node is also simply referred to as a node 333.
- the time slot start timing is set in order to shift the start timing of the time slot that periodically operates in each of the nodes 331 to 333 by the propagation delay time between each of the nodes 332 and 333 and the start node 331.
- one origin node 331 is provided on the optical network system.
- a synchronization frame for determining the time slot start timing t10 is transmitted from the start node 331 to the nodes 332a and 333b other than the start node as indicated by arrows Y25 and Y26.
- Each of the nodes 332 and 333 other than the origin node starts a time slot operation when receiving a synchronization frame.
- the start timing of the time slot operating in each of the nodes 332a and 333b other than the origin node is shifted by the propagation delay time “150, 200” between the nodes 332a and 333b and the origin node 331.
- the time t13a shifted by “” is the start timing of the time slot synchronized with the burst transmission cycle of the node 333b.
- a time slot transmitted in the direction of arrows Y25 and Y26 from the origin node 331 is referred to as a forward time slot.
- the origin node 331 gives the current time inside the origin node 331 as a time stamp to the synchronization frame, and transmits the synchronization frame to each of the nodes 332 and 333 other than the origin node.
- the nodes 332 and 333 other than the origin node receive the synchronization frame, they set the time stamp in the synchronization frame as the current time of their own node.
- the time of each of the nodes 332 and 333 other than the origin node is set so as to be shifted by the propagation delay time with respect to the origin node 331.
- the control wavelength is used separately from the data wavelength for transmission of the synchronization frame.
- the control wavelength is copied by the optical coupler 322 or the like for each of the nodes 332 and 333 with respect to one control wavelength as in the frame 324. May be.
- transmission may be performed by P-to-P (Peer to Peer) using individual control wavelengths for the nodes 332 and 333. That is, the nodes may be directly connected to each other on the network by P-to-P to transmit and receive data.
- the start node 331 has a synchronization frame provided with the current time (T1) inside the start node 331 as a time stamp, and each node 332 other than the start node as indicated by an arrow Y31. , 333.
- Each of the nodes 332 and 333 other than the origin node sets the time stamp in the synchronization frame received from the origin node 331 as the current time T1 of the own node. Then, after the processing time ta set by the parameter, a delay measurement frame provided with the current time T2 inside the own node as a time stamp is transmitted to the origin node 331 as indicated by an arrow Y32. The explanation at the time of transmission is also shown in a frame 118a. At this time, the delay measurement frame is transmitted through a path through which the origin node 331 has transmitted the synchronization frame. By passing the delay measurement frame through the same path as the synchronization frame, the propagation delay time between the nodes 331 to 333 can be measured.
- the delay measurement frame is repeatedly transmitted at random timing because there is a possibility that the delay measurement frames from the nodes 331 to 333 collide with each other. Alternatively, transmission is performed according to the time slot assigned to each of the nodes 331 to 333. Since the delay measurement frame is transmitted to each of the nodes 331 to 333 via the active optical switch, a control wavelength is used separately from the data wavelength.
- the origin node 331 measures the propagation delay time between the nodes 332 and 333 other than the origin node, and calculates the propagation delay time between adjacent nodes based on this measurement result. For example, the origin node 331 calculates the difference between the propagation delay time between the nodes 331-333b and the propagation delay time between the nodes 331-332a, and sets this difference as the propagation delay time between the adjacent nodes 332a-333b.
- a conceptual diagram and explanation of the propagation delay time measured in this way and the calculated propagation delay time are shown in frames 118d and 118c in FIG. However, in the frame 118d, symbols A to E are shown for nodes (optical switch nodes) other than the master node that is the starting node.
- the origin node 331 measures the ring one round delay time for use in a communication time slot across the origin node.
- the ring one-round delay time measurement method is as follows: (a) the origin node 331 transmits a ring one-round delay measurement frame, (b) the origin node 331 receives a ring one-round delay measurement frame, and c), (a) and (b) Measure by subtracting the counter value at the time of processing.
- the ring exchange point node 332 measures the lower ring round-trip delay time for use in a communication time slot from the nodes 333a and 333b of the lower rings 336a and 336b to the node 333c of the upper ring 335.
- the method of measuring the lower ring round delay time is as follows: (a) the ring switching point node 332 transmits a lower ring round trip delay measurement frame, and (b) the ring switching point node 332 makes one round of the lower ring.
- the measurement frame is received, and measurement is performed by subtracting the counter value at the time of (c), (a), and (b) processing.
- FIGS. 119A and 119B a method for measuring the propagation delay time will be described with reference to FIGS. 119A and 119B.
- FIG. 119A a case where the paths of the synchronization frame and the delay measurement frame are symmetrical will be described.
- Each of the nodes 332 and 333 other than the origin node sets the time stamp in the synchronization frame as the current time of its own node, and gives the time (or the time recorded according to the local clock of each node from that time) as the time stamp.
- the same frame as the synchronization frame transmitted in the direction indicated by the arrow Y30 is transmitted in the reverse direction as indicated by the arrow Y31.
- the optical coupler 322 is placed on a route different from the optical switch unit 311 so that the delay measurement frame always reaches the origin node 331, and the delay measurement frame is transmitted.
- the origin node 331 takes the difference between the time stamp in the received delay measurement frame and the time in its own node when the delay measurement frame is received, so that the round-trip propagation delay time between the nodes 332 and 333 is obtained. Measure. Next, a case where the paths of the synchronization frame and the delay measurement frame are asymmetric will be described with reference to FIG. 119B.
- Each of the nodes 332 and 333 other than the origin node sets a time (common time) that is common to the nodes (including the origin node) 331 to 333 (for example, using the GPS receiver 324), and uses the common time as a time.
- the delay measurement frame provided as a stamp is transmitted to the origin node 331 in the same direction as indicated by an arrow Y32 through a route different from the synchronization frame transmitted in the direction indicated by the arrow Y30.
- the origin node 331 takes the difference between the time stamp in the received delay measurement frame and the common time inside the node when the delay measurement frame is received, thereby causing a one-way propagation delay between the nodes 332 and 333. Measure time.
- each node 331 to 333 continues to transmit a delay measurement frame at random timing, so that the delay from each of the nodes 332 and 333 to the origin node 331 Reach the measurement frame.
- a control time slot that is synchronized based on the delay time between the origin node 331 and each of the nodes 332 and 333, collision of delay measurement frames between different nodes 332 and 333 is achieved. Avoidance is possible.
- a delay measurement frame may be transmitted to the origin node in P-to-P using individual control wavelengths for each of the nodes 331 to 333.
- the origin node 331 transmits and receives a synchronization frame addressed to the own node using the control wavelength, and based on the time stamp in the synchronization frame and the time in the own node, the origin node 331 Measure the propagation delay time.
- the ring switching point node 332 transmits and receives a synchronization frame addressed to the own node using the control wavelength, and based on the time stamp in the synchronization frame and the time in the own node, the upper ring 335 Alternatively, the propagation delay time for one round of the lower ring 336 is measured. Note that the propagation delay time for one round of the lower ring 336 is notified to the origin node 331.
- the origin node 331 calculates the propagation delay time between the nodes 332 and 333 other than the origin node by calculating the difference in propagation delay time between the nodes 332 and 333 other than the origin node and the origin node 331. .
- the origin node 331 and the ring exchange point nodes 332a and 332b transmit and receive a synchronization frame addressed to the own node, and when the synchronization frame is received, the current time and the synchronization frame within the own node are received.
- the propagation delay time for one round of the ring is measured by taking the difference from the time stamp in the ring.
- a dedicated wavelength is allocated so that the synchronization frame always reaches its own node, or a synchronization frame is transmitted according to a time slot allocated to each node.
- ADD IFs interfaces
- variable time slots are created with one ADD IF.
- the origin node 331 Based on the propagation delay time between the nodes 332 and 333 other than the origin node, the origin node 331 sets a plurality of time slots for the nodes 332 and 333 in consideration of the propagation delay for the number of routes. To do.
- the origin node 331 indicates a multiple time slot start frame indicating an offset value from a forward time slot already operating in each of the nodes 332 and 333 other than the origin node as indicated by an arrow Y33 from time t11. It transmits to each node 332a, 333b other than the origin node.
- Each of the nodes 332a and 333b other than the origin node cuts a time slot (time slot for the upper ring) shifted by an offset value as indicated by an arrow Y34 with respect to the forward time slot when receiving a plurality of time slot start frames. start. This content is shown in a frame 121f.
- i the number of stages of the ring to which each node belongs when counted from the upper ring.
- the number of time slots in the upper ring and the lower ring is as follows (1) and (2).
- the number of time slots in the upper ring is two (a forward time slot and a ring round-trip time slot).
- the number of time slots in the lower ring is four (forward time slot, ring round time slot, upper ring forward time slot time slot, upper ring round time slot time slot) It is.
- time slots from the lower ring 336 to the upper ring 335 will be described with reference to FIGS. 122A and 122B.
- the node 333b can perform ADD on the upper ring by using the time slot (time slot for the upper ring) whose start timing is advanced.
- time slots necessary for bi-directional communication in multi-ring time slot data arrival from both the left and right sides with respect to the origin node
- the definition of the propagation delay time is as follows, as shown in FIG. 123A.
- Dru Propagation delay time for one round of the upper ring.
- Dn propagation delay time between MC and SC in the upper ring.
- Ds Propagation delay time between MC and Sub MC in the upper ring.
- Drl Propagation delay time for one round of the lower ring.
- Dp Propagation delay time between Sub MC to SC in the lower ring.
- the forward time slot is a time slot that is delayed by Dn time with respect to the forward time slot inside the MC in the upper ring, and is forward with respect to the forward time slot inside the MC in the lower ring.
- the time slot is delayed by Ds + Dp time.
- the backward time slot is a time slot advanced by 2Dn hours with respect to the forward time slot in the own node in the upper ring.
- a time slot delayed by t-MOD (2Dn, t) time with respect to the forward time slot in the own node here, MOD (A, B) means the remainder of A ⁇ B)
- the time slot is delayed by t0-MOD (2Dn, t0) time with respect to the forward time slot in the own node.
- the time slot is advanced by 2 (Ds + Dp) hours with respect to the forward time slot in the own node.
- the time slot is delayed by t-MOD (2 (Ds + Dp), t) time with respect to the forward time slot in the own node.
- the time slot is delayed by t0-MOD (2 (Ds + Dp), t0) time with respect to the forward time slot in the own node.
- the forward straddling time slot is a time slot advanced by Dru time with respect to the forward time slot in the own node in the upper ring.
- the time slot is delayed by t-MOD (Dru, t) time with respect to the forward time slot in the own node.
- the time slot is delayed by t0-MOD (Dru, t0) time with respect to the forward time slot in the own node.
- the time slot is advanced by Drl time with respect to the forward time slot in the own node.
- the time slot is delayed by t-MOD (Drl, t) time with respect to the forward time slot in the own node.
- the time slot is delayed by t0-MOD (Drl, t0) time with respect to the forward time slot in the own node.
- the reverse straddling time slot is a time slot advanced by 2Dn-Dru time with respect to the forward time slot in the own node in the upper ring.
- the time slot is delayed by t-MOD (2Dn-Dru, t) time with respect to the forward time slot in the own node.
- the time slot is delayed by t0-MOD (2Dn-Dru, t0) time with respect to the forward time slot in the own node.
- the time slot is advanced by 2 (Ds + Dp) -Drl time with respect to the forward time slot in the own node.
- the time slot is delayed by t-MOD (2 (Ds + Dp) -Drl, t) time with respect to the forward time slot in the own node.
- the time slot is delayed by t0 ⁇ MOD (2 (Ds + Dp) ⁇ Drl, t0) time with respect to the forward time slot in the own node.
- the time slot for the time slot for straddling the upper ring forward direction is a time slot advanced by Dru + Drl time with respect to the forward time slot in the own node in the lower ring.
- the time slot is delayed by t-MOD (Dru + Drl, t) time with respect to the forward time slot in the own node.
- the time slot is delayed by t0-MOD (Dru + Drl, t0) time with respect to the forward time slot in the own node.
- the time slot for the time slot for crossing the upper ring in the reverse direction is a time slot advanced by 2 (Ds + Dp) ⁇ (Dru + Drl) time with respect to the forward time slot in the own node in the lower ring.
- the time slot is delayed by t-MOD (2 (Ds + Dp) ⁇ (Dru + Drl), t) time with respect to the forward time slot in the own node.
- the time slot is delayed by t0 ⁇ MOD (2 (Ds + Dp) ⁇ (Dru + Drl), t0) time with respect to the forward time slot in the own node.
- a time slot (forward direction) used in the single ring NW will be described with reference to FIGS. 124A to 124C.
- the system configuration is such that M-C 351, S-C 352, 353, and 355 are ring-connected by a transmission line 357.
- the basic policy is to have each node 352-354 engrave another time slot to match the time slot operating in MC-351.
- FIG. 124A shows the case of forward communication as indicated by arrow Y41, and since there is no cross-border communication across MC-351, the time slots of each node 351 to 354 are all forward time slots 358.
- the straddling communication in the forward communication means that a signal passes in the forward direction as indicated by the arrow Y43 between the M-C 351 and the S-C 354 which are the origin nodes indicated by the bidirectional arrow Y42 in FIG. 124C. That is. In other words, the communication is straddling from the node 354 side to the origin node (MC) 351.
- FIG. 124B shows a case where there is a crossing of M-C351 as indicated by an arrow Y44.
- the time slots of the nodes 353 and 354 having the M-C 351 crossing become the forward crossing time slot 359, and the others become the forward time slot 358.
- the basic policy is to have each node 352-354 engrave another time slot to match the time slot operating in MC-351.
- FIG. 125A shows the case of reverse communication as indicated by arrow Y45, and since there is no MC-351 crossing communication, the time slots of the nodes 351 to 354 are all reverse time slots 361.
- the crossing communication in the reverse direction communication means that the signal passes in the reverse direction as indicated by the arrow Y46 between the M-C 351 and the S-C 354, which are the origin nodes indicated by the bidirectional arrow Y42 in FIG. 125C. That is. In other words, the communication is straddling from the origin node (MC) 351 to the node 354 side.
- FIG. 125B shows a case where there is a crossing of M-C351 as indicated by an arrow Y47.
- the time slot of the node 354 with the M-C 351 straddling becomes the reverse straddling time slot 362, and the others are the reverse time slots 361.
- the origin node 351 records time slots other than the forward time slot among the nodes 352 to 354 other than the origin node in consideration of the direction of the time slot and whether or not the origin node 351 is straddled.
- the offset value to be set in the node (specific node) 354 that needs to be detected is determined.
- time slot (forward direction) used in the multi-ring NW will be described with reference to FIGS. 126A to 126D.
- M-C 351, S-C 352, and 353 are connected by the upper ring 357, and the upper ring 357 and the lower ring 377 are connected by the sub switching ring node SubM-C 371, and the lower ring 377 is connected to the S-C 372
- the system configuration is such that 373 is connected.
- the basic policy is to allow each node 352, 353, 371-373 to have other time slots to match the time slots operating in the MC 351.
- FIG. 126A shows a case where there is communication from the lower ring 377 to the upper ring 357 during forward communication as indicated by an arrow Y51.
- the time slot of the node 373 in the lower ring 377 is a forward time slot 375, and the others are forward time slots 376.
- the cross-over communication from the lower ring 377 to the upper ring 357 in the forward communication is an arrow between the S-C 373 and the Sub M-C 371 which are nodes of the lower ring 377 indicated by the bidirectional arrow Y42b in FIG. 126D.
- the signal passes in the forward direction as indicated by Y52. That is, as shown in FIG.
- the time slot of the node 373 of the lower ring 377 becomes the time slot 378 for the upper ring forward straddling time slot.
- M ⁇ C351 crossing communication forward crossing communication
- FIG. 126B shows a case where there is a straddle from the lower ring 377 to the upper ring 357 and a straddle of MC-351, as indicated by an arrow Y53.
- the time slots of the nodes 371 and 353 of the upper ring 357 related to the crossing of the M-C 351 become the forward crossing time slots 377a and 377b, and the time slot of the node 373 related to the crossing of the lower ring 377 is the time slot for the upper ring forward crossing.
- Are directed time slots 378, and others are forward time slots 376.
- FIG. 126C shows a case where there is a crossing of M-C 351 and communication from the upper ring 357 to the lower ring 377 as indicated by an arrow Y54.
- the time slot of the node 353 of the upper ring 357 related to the crossing of the M-C 351 is the forward time slot 377b, and the other is the forward time slot 376.
- the time slots from the upper ring 357 to the lower ring 377 that have communication from the upper ring to the lower ring but do not straddle the MC are all forward time slots 376.
- time slots (in the reverse direction) used in the multi-ring NW will be described.
- the basic policy is to allow each node 352, 353, 371-373 to have other time slots to match the time slots operating in the MC 351.
- FIG. 127A shows a case where there is communication from the upper ring 352 to the lower ring 377 during reverse communication as indicated by an arrow Y55.
- the time slot of the node 373 of the lower ring 377 is a reverse span time slot 381, and the others are reverse time slots 382.
- the cross-over communication from the upper ring 357 to the lower ring 377 in the reverse direction communication is between the SubM-C 371 that is the node of the upper ring 357 and the S-C 373 of the lower ring 377 indicated by the bidirectional arrow Y42b in FIG. 127D.
- a signal passes in the opposite direction as indicated by an arrow Y56. That is, as shown in FIG.
- the time slot of the node 373 of the lower ring 377 becomes the time slot 383 for the time slot for straddling the upper ring in the reverse direction.
- the M ⁇ C351 crossing communication reverse direction crossing communication
- FIG. 127B shows a case where there is a bridge from the upper ring 357 to the lower ring 377 and an MC 351 bridge, as indicated by an arrow Y57.
- the time slot of the node 373 in the lower ring 377 becomes the time slot 383 for the upper ring reverse direction crossing time slot, and the time slot of the upper ring 357 and the SubM-C 371 in the upper ring 357 straddling the M-C 351 are reverse time slots.
- 384a and 384b, and others are reverse time slots 382.
- the origin node 351 has the time slot direction, the presence / absence of straddle of the origin node 351, the presence / absence of straddle from the upper ring 357 to the lower ring 377, and the stride from the lower ring 377 to the upper ring 357.
- offset values to be set in nodes (specific nodes) 353 and 373 that need to have time slots other than the forward time slots among the nodes 352, 353, and 371 to 373 other than the origin node determined. .
- the MC [1] starts counting the time counter value of the counter management unit 317 (see FIG. 113) in the MC [1], and the control forward time slot and data Start both ticks in the forward time slot.
- the initial value of the time counter value is “100”
- the control time slot starts from TS1, “200” is TS2, “300” is TS3, and the time slot is sequentially increased according to the time counter value count-up. It will be incremented.
- a data time slot (not shown) is also cut at the same time.
- MC [1] performs delivery setting of the initial time counter value to each node [2] to [5] other than MC.
- the initial time counter value is distributed by being included in the command setting information in the synchronization frame.
- a control forward time slot number used for distribution of the initial time counter value, a destination MAC address, a destination controller ID, and an allocation control time slot number assigned to respond to the initial time counter value are set.
- the initial time counter value may be included in the time counter operation start command.
- MC [1] is a forward time slot for control, and a synchronization frame provided with an initial time counter value “100, 200, 300,...” As a time stamp is sent to each node [3] other than MC. To deliver.
- the time stamp adding process delay time (for example, 1) from the time counter value “300” at the head of the control forward time slot TS3 is transmitted.
- the time stamp giving process delay time is the time taken for the time stamp giving process, as shown by arrow Y61.
- the control forward time slot start time counter value is “300” which is the head counter value of the control forward time slot used for transmission.
- the control forward time slot start time slot number is “TS3”, which is the time slot number of the control forward time slot corresponding to SubM-C [3].
- the data forward time slot start time counter value is “450” which is the head counter value of the data forward time slot delimiter immediately after the control forward time slot used for transmission.
- the data forward time slot start time slot number is the data forward time slot number “TS2” corresponding to SubM-C [3].
- “1” is added as a delay time for adding a time stamp, and therefore an accurate counter value “300” is obtained by subtracting “1”. Do to get.
- SubM-C [3] also receives the data forward time slot start time counter value “450”, and therefore also records “450”.
- MC [1] is a forward time slot for control, and distributes a synchronization frame with an initial time counter value as a time stamp to each of nodes [2] to [4] other than MC [1]. .
- SC [2] starts a counterclockwise time slot (including a data time slot).
- SubM-C [3], [4], and SC [5] simultaneously perform the data time slot in addition to the control time slot.
- MC [1] may simultaneously deliver a synchronization frame from both counterclockwise and clockwise.
- Each of the nodes [2] to [5] other than the MC when the synchronization frame to which the initial time counter value is added as a time stamp is delivered from the MC [1], the response to the response is in the order of control. Use directional time slots.
- MC [1] is a node close to MC [1] as indicated by arrows Y63, Y64, and Y65 with respect to nodes [2] to [5] other than MC in the upper ring.
- the youngest control time slots are assigned in order.
- MC [1] is indicated by an arrow Y66 in order from a node (for example, [5]) close to MC [1] or SubM-C [3], [4] with respect to the node of the lower ring.
- a young slot is assigned from among control time slots other than the control time slot assigned in the higher ring.
- SubM-C [3] and [4] are based on the assumption that the lower ring topology controller ID has been grasped in advance and set by a command in advance. In addition, SubM-C [3] and [4] distribute the initial time counter value to the lower ring at a timing within one cycle of the period from the time of reception of the initial time counter value. In addition to the control forward time slot, the data time slot is also stepped simultaneously.
- SC [6] is a node connected to a lower link to which SC [5] is connected.
- the SCs [5] and [6] of the lower ring use the control forward time slots TS7 and TS8 assigned to the own node by the MC [1], as indicated by arrows Y67 and Y68.
- a delay measurement frame to which the initial time counter value of the own node is added as a time stamp is transmitted to SubM-C [3].
- SC [5] and [6] return the initial time counter value to the SubM-C [3] at a timing within one cycle of the cycle from the reception of the initial time counter value.
- SC [5] and [6] add “for example, 1” for the circuit processing delay time from the time counter value to the initial time counter value transmission, and give the added value as the time counter value of the own node.
- SubM-C [3] When SubM-C [3] receives a delay measurement frame to which the initial time counter value is added as a time stamp from SC [5] of the lower ring, as indicated by arrow Y67, the propagation delay as indicated by frame 135a is received. Measure time. Further, SubM-C [3] uses the forward time slot for control assigned to its own node by MC [1] to S-C [1], as shown by arrow Y69. A delay measurement frame to which the initial time counter value of C [5] is added as a time stamp is transmitted in the time slot “TS12”. Note that SubM-C [3], after transmission, newly receives the initial time counter value from SC [6] of the lower ring as indicated by arrow Y68, the control assigned to the next cycle is performed. Transmit in the forward time slot.
- 136A shows a configuration diagram of the multi-ring network, and symbols [1] to [5] of the respective nodes are attached.
- SubM-C [3] distributes a synchronization frame to which the initial time counter value addressed to SC [5] of the lower ring is given as a time stamp in the time slot “TS9” indicated by arrow Y71. After one round and returning to SubM-C [3], DROP. Thereby, as shown in a frame 136a, the propagation delay time for one round of the lower ring is measured.
- the SubM-C [3] receives the delay measurement frame with the initial time counter value given as a time stamp from the lower ring SC [5], it is assigned to its own node by the MC [1]. Using the control forward time slot, as shown by an arrow Y72, a delay measurement frame in which the initial time counter value of SC [5] is given as a time stamp is transmitted to MC [1]. When SubM-C [3] receives a new initial time counter value from SC of the lower ring after transmission, transmission is performed in the control forward time slot assigned to the next cycle. Do.
- SC [2] (or SubM-C) receives a frame for starting a plurality of time slots from MC [1] as indicated by an arrow Y73, as shown by reference numeral 137b within the frame 137a, Based on the forward time slots for control and data operating in the node, the next time slot is generated as shown by the arrow Y74.
- a reverse time slot for control and data indicated by reference numeral 137c a forward crossing time slot indicated by reference numeral 137d, a reverse crossing time slot indicated by reference numeral 137e, and a forward crossing of upper rings indicated by reference numeral 137f
- a time slot for the time slot and a time slot for the time slot for straddling the upper ring reverse direction indicated by reference numeral 137g are generated.
- the SC [2] (or SubM-C) receives the multiple time slot start frame from the MC as indicated by the arrow Y73
- the multiple time slot start is started.
- the operation is started for the time slot [TS4] that is earlier than the head position of the data forward time slot by the offset value.
- This time slot is defined as a reverse time slot.
- the first implementation example is an implementation example of a lower ring in unidirectional communication (up and down path is asymmetric) and multi-ring.
- Arrow Y76 indicates ADD / DROP in the lower ring
- arrow Y77 indicates ADD for the upper link from TX1, which is the transmission unit
- arrow Y78 indicates ADD for the upper link from TX2. It is necessary to operate in different time slots in the ADD to the time slot in the lower ring and the ADD of the time slot to the upper ring.
- TX (ADD IF) for the number of time slots is deployed. Also, the wavelength used in each time slot is different.
- the start timing is set to the time t31 for the lower ring one week delay. Accelerate.
- This enables ADD in different time slots at the same timing.
- the forward time slot TS1 [TX1] and the upper ring time slot time slot TS3 [TX2] can be transmitted simultaneously.
- reception is possible in the forward time slot TS1 [RX].
- the second implementation example is an implementation example of a lower ring in a multi-ring for one-way communication (up / down path is asymmetric), but unlike the first implementation example, as shown in a frame 142a, an upper and lower ring ADD IF is shared. Therefore, since it is not necessary to prepare ADD IFs for the number of time slots, the device cost can be reduced.
- the arrow Y76 indicates DROP in the lower ring, and the arrows Y79a and Y79b indicate ADD for the upper link from TX which is a transmission unit.
- time slots “TS1 to TS7” operating in the ADD IF shown in the frame 142b define time slots with unequal intervals of the period t ⁇ n, and transmit the respective time slots “TS1 to TS7”.
- the size of the period t ⁇ n is determined from the start position Pa of the earliest time slot and the start position Pb of the latest time slot (Pb ⁇ Pa) in the period t having the same number of cycles for a plurality of time slots. It becomes.
- a multi-ring NW (one-way communication, two-way communication) as shown in FIG. 143 is targeted, and time slot exchange in a WDM / TDM network of the multi-ring NW is possible.
- control problem surrounded by the broken line can be solved.
- the propagation delay time of the upper ring round is not an integral multiple of the time slot.
- Time slots can be synchronized. This is because the propagation delay time for one round of the ring can be measured.
- the time slot when transmitting the time slot from the lower ring to the upper ring can be synchronized. The reason is that occurrence of a time slot collision at the ring switching point node can be avoided.
- the left and right time slots when the time slots arrive from both the left and right sides to the same output IF of the same origin node can be synchronized.
- the reason is that the time slot can be set according to the direction of the time slot, the presence / absence of ring crossing, the presence / absence of MC crossing, and the like.
- a single ring NW (one-way communication, two-way communication) as shown in FIG. 144 is targeted, and time slot exchange is performed in a WDM / TDM network having a single ring NW and a plurality of origin nodes. It becomes possible.
- control problem surrounded by the broken line can be solved.
- the propagation delay time of the upper ring round is not an integral multiple of the time slot. Time slots can be synchronized. This is because the propagation delay time for one round of the ring can be measured.
- the time slot can be set according to the direction of the time slot, the presence / absence of the MC crossing, and the like.
- FIG. 145 shows a summary of the problems of the prior art and the specific solution of this embodiment for the problem.
- the origin node is based on the propagation delay time between the origin node and each node other than the origin node and the propagation delay time for one round of the ring.
- Each of the other nodes is provided with a maximum of two types of data time slots.
- the lower ring node is for the upper ring synchronized with the reference time slot of the ring exchange point node.
- Time slots can be deployed. As a result, it is possible to avoid occurrence of a time slot collision at the ring exchange point node.
- the origin node has a propagation delay time for one round of the ring that is not an integral multiple of the time slot. Arriving time slots can be processed. Thereby, the effect that the time slot from another node can be transferred is acquired.
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Abstract
Description
さらに、本発明のノードは、単一のリングからなるシングルリングネットワークまたは複数のリングが多段接続されてなるマルチリングネットワークからなる光ネットワークシステムにおいて、前記リング上に存在するノードであって、自ノードがマスターノードである場合、前記マスターノード以外の各ノードの時刻を設定するタイムスロット制御部と、自ノードが前記マスターノード以外のノードである場合、当該マスターノードにより設定された時刻から第1のタイムスロットを刻む基準タイムスロット同期部と、自ノードが前記マスターノードである場合、当該マスターノードと当該マスターノード以外の各ノードとの間の伝搬遅延時間と、前記リングの1周分の伝搬遅延時間とを基に、当該マスターノード以外の各ノードのうちの特定ノードのオフセット値を算出し、算出したオフセット値を前記特定ノードに設定する遅延測定部と、自ノードが前記特定ノードである場合、自ノードの第1のタイムスロットの開始タイミングを、前記マスターノードにより設定されたオフセット値分だけずらした第2のタイムスロットを刻む複数タイムスロット管理部とを備える構成である。
以下に、本実施形態の光ネットワークシステムを具体的に説明する。
第1の実施形態の光ネットワークシステムは、マスターノードがトリガを各ノードに送信することで、各ノードのタイムスロット(TS)同期を取る。そして、マスターノードがTS長またはTS周期をリング長の整数分の1に設定することで、トリガがリング1周してマスターノードで終端するタイミングと別のトリガを出力するタイミングとを合わせることができ、リングネットワークで周期的なデータ送受信を実現できる。
つまり、ノードAは、[1]の1行目に示すように宛先ノードBのデータをTS0にADDする。この際の光SW接続ポートはポート番号3から2へ接続される。ノードAは次のトリガを受信したら、同様にTS情報の2番目の動作を実施する。ノードAは、次のトリガ受信時も同様にTS情報の3番目の動作を実施する。つまり、ノードAは、[1]の3行目に示すように宛先ノードCのデータをTS2へADDする。この際の光SW接続ポートもポート番号3から2へ接続される。
第2の実施形態は、タイムスロット情報をトリガ内に埋め込んでトリガと一緒に各ノードに配信するものである。
第3の実施形態の光ネットワークシステムは、マスターノードがタイムスタンプを送信することで伝送遅延時間ずれた時刻で各ノードの時刻を設定し、各ノードが共通した時刻でタイムスロットを同期し、データ送受信を実現するものである。
第4の実施形態は、第3の実施形態の光ネットワークシステムにおいて、マスターノードがTS情報を各ノードに配信するものである。
以降同様に、次のノード1G2においては、ローカル時刻はtが設定される。これにより、ノード1G2のローカル時刻は、マスターノード2Gのローカル時刻よりも遅延時間(a+b)分ずれた時刻(t-a-b)に設定される。ノード1G3においては、ローカル時刻はtが設定される。これにより、ノード1G3のローカル時刻は、マスターノード2Gのローカル時刻よりも遅延時間(a+b+c)分ずれた時刻(t-a-b-c)に設定される。
但し、マスターノード2Jを跨ぐ送受信(跨ぎ通信)とは、送信の順方向においては、マスターノード2Jの上流側に接続されたノード1J3から、マスターノード2Jをスルーして(跨いで)、マスターノード2Jの下流側に接続されたノード1J1で信号を受信、又は更に下流のノードで信号を受信することである。送信の逆方向においては、マスターノード2Jの下流側に接続されたノード1J1から、マスターノード2Jをスルーして(跨いで)、マスターノード2Jの上流側に接続されたノード1J3で信号を受信又は更に上流のノードで信号を受信することである。
例えば、ノード1J1がローカル時刻=t2でデータ送信すると、そのデータはマスターノード2Jには、マスターノード2Jでのローカル時刻=t2+a+b+c+dに到着する。このため、マスターノード2JのDROP切替時間は、「TS開始時刻+TS番号×TS長+リング1周時間」にする。ノード1J3からノード1J1へデータを送受信する場合のように、マスターノード2Jを跨ぐ送受信についても同様にDROP切替時間は、「TS開始時刻+TS番号×TS長+リング1周時間」にする。
第5の実施形態は、各ノードが共通時刻の情報を共有し、遅延時間を測定し、TS開始時刻から遅延時間を引いてTS同期するものである。
更に説明すると、波長多重したデータ線を収容する場合には、[1]に示すように、光TS-SW部の入力前に分波部を設置して、波長多重により入力したデータを例えばN個の波長に分波してそれぞれをIN 1~IN Nで示される入力ポートに与える。そして、光TS-SW部の後段に合波部を設置し、光TS-SW部のN個の出力ポートOUT 1~OUT Nからの光信号を波長多重し、リングネットワーク上での次のノード(次段のノード)に伝送するようにしている。光TS-SW部は、光信号挿入(ADD)及び光信号分岐(DROP)の機能も備えており、ADD用のポートが光TS-SW部の入力ポートとして設けられ、DROP用のポートが光TS-SW部の出力ポートとして設けられている。
波長多重しないデータ線を収容する場合には、[2]に示すように、分波部及び合波部は設けられない。この場合、リングのデータ線数は、光スイッチにおけるADD/DROP用のインタフェース数を引いた端子(ポート)の数と等しくなる。
光TS-SW部30Aは、λi(i=0~kN-1)のkN個の波長において、(i MOD N)が同じ値となる複数波長を同一波長として、kN×kNの周回性AWG(Arrayed Waveguide Grating:アレイ導波路型回折格子)30aと、その前段に配置され、波長変換部および分波部としてk個の周回性1×N AWG30b,30cと、k(N-2)個のTHRU(通過)/DROP用TWC1~TWC4と、1つのADD用TWC[A]と、1つのDROP IF(インタフェース)としての光受信器30eと、k個の(N-1)×1 合波部30x,30yとを有する。図52は、k=2、N=4の場合である。
但し、TWCは、可変波長変換器である。また、周回性AWG(単に、AWGともいう)30aは、各入力ポートに入力した光信号をその波長に応じて出力ポートに振り分ける処理を行うものである。 つまり、光TS-SW部30Aは、2重リングであって1リングあたり4波長を用いる場合の、FWCを用いない1ADD/1DROP構成でファイバ間波長交換を行う例を示している。
つまり、光TS-SW部30Bは、2重リングであって1リングあたり4波長を用いる場合の、FWCを用いない1ADD/1DROP構成でファイバ間波長交換を行い、さらに制御用波長を用いる例を示している。
つまり、2重リングであって1リングあたり4波長を用いる場合の、FWCを用いない1ADD/1DROP構成でファイバ間波長交換を行う例を示している。
つまり、2重リングであって1リングあたり4波長を用いる場合に、FWCを配備しないでファイバ間波長交換とファイ内波長交換とを可能にした光TS-SW部30Dの構成例を示している。
ADDは、AWG30vのIN1に入力された信号をOUT1~9の何れかに出力することを意味する。DROPは、AWG30vのIN2~9に入力された信号をOUT9に出力することを意味する。スルーは、AWG30vのIN2~9に入力された信号をIN番号から1を引いたOUT番号に出力することを意味する。
図57Aをもとに詳細な動作を説明する。ADDする場合、OUT1~8のどこに出力するかによりTWC[A]により波長をλ1b~8bの何れかに変換してIN1に入力する。IN1に入力される波長と出力先の対応はλ1bがOUT1、λ2bがOUT2、λ3bがOUT3、λ4bがOUT4、λ5bがOUT5、λ6bがOUT6、λ7bがOUT7、λ8bがOUT8となる。ファイバ1及びファイバ2からくる信号はAWG30b,30cで分波され、スルーするか、DROPするかに応じてTWC1~8により波長が変換される。TWC1を例に波長と出力先を説明すると、スルーする場合はλ1g、λ2rはOUT1となる。
図58Aに示す光TS-SW部30Gは、図57Aの光TS-SW部30FとTWC1~TWC8,[A]の波長要件が異なるだけで、同構成であるため、その説明を省略する。図58Aおよび図58Bでは、各波長を識別するために、THRU用波長の添え字をrとし、DROP用波長の添え字をgとし、ADD用波長の添え字をbとし、ファイバ内交換波長の添え字をyとしている。
ファイバ内交換は、AWG30vのIN2~5に入力された信号をOUT1~4のスルーする出力先以外の何れかに出力する。AWG30vのIN6~9に入力された信号をOUT5~8のスルーする出力先以外の何れかに出力することを意味する。図58Aおよび図58Bをもとに詳細な動作を説明する。ADD、Drop、スルーは実施例6と同じなため、ファイバ内交換の場合をTWC1を例に説明する。AWG30vのIN2に入力された信号の出力先をOUT2に変更する場合は、TWC1に入力された信号の波長をλ3yとする。同様にOUT3に出力する場合はλ4y、OUT4に出力する場合はλ5yとする。
図59Aに示す光TS-SW部30Hは、図57Aの光TS-SW部30FとTWC1~TWC8,[A]の波長要件が異なるだけで、同構成であるため、その説明を省略する。図59Aおよび図59Bでは、各波長を識別するために、THRU用波長の添え字をrとし、DROP用波長の添え字をgとし、ADD用波長の添え字をbとし、ファイバ内交換波長の添え字をyとし、ファイバ間交換波長の添え字をpとしている。
ファイバ間交換は、AWG30vのIN2~5に入力された信号をOUT5~8の何れかに出力する。AWG30vのIN6~9に入力された信号をOUT1~4の何れかに出力することを意味する。図59Aおよび図59Bをもとに詳細な動作を説明する。ADD、Drop、スルー、ファイバ内交換は実施例7と同じなため、ファイバ間交換の場合をTWC1を例に説明する。AWG30vのIN2に入力された信号の出力先をOUT5に変更する場合は、TWC1に入力された信号の波長をλ6pとする。同様にOUT6に出力する場合はλ7p、OUT7に出力する場合はλ8p、OUT8に出力する場合はλ9pとする。
光TS-SW部30Jは、1または複数の入力ポートと複数の出力ポートとを備え、波長多重された入力光信号を波長毎に分波する分波器(分波部)30bと、各入力ポートに入力した光信号をその波長に応じて出力ポートに振り分けるAWG30aと、光スイッチノードでの通過(Through)、挿入(ADD)及び分岐(DROP)を選択するために波長変換を実行するTWC[A]1~TWC[A]3,TWC1~TWC8と、次段に伝送するために各波長の出力光信号を波長多重する合波器(合波部)30xと、次段の分波部(図示せず)で光信号が同一ポートに出力されるように波長変換するFWC1~FWC8と、AWG30aで分岐(DROP)させた光信号を受信する光受信器30eと、から構成されている。
図示したものでは、前段から波長多重によって伝送された光信号は分波器30bにより波長λ1~λ8に分波され、これらの分波された光信号は、それぞれ、TWC1~TWC8を介してAWG30aの入力ポートに与えられている。これらとは別に、挿入されるべき光信号が、TWC[A]1~TWC[A]3を介してAWG30aの入力ポートに与えられている。AWG30aの出力ポートのうち8個は次段への伝送用であり、これらの出力ポートからの光信号はそれぞれFWC1~FWC8を経て合波器(合波部)30xに入力され、波長多重されて次段に伝送される。
それとは別に、AWG30aには分岐(DROP)に用いられる出力ポートがあり、この出力ポートには、光受信器30eが接続されている。光受信器30eは、光電変換を行う光電素子(APD)と、光信号間のパワー差を吸収するためのリミッティング増幅器(LIM)と、光信号間での位相差を吸収するためのクロック・データ・リカバリ回路(CDR)とがこの順で直列に接続された構成となっており、信号間のパワー差/位相差を吸収して光信号を受信する。
なお、図60に示したものでは、波長λ8は、制御用の固定波長とされている。また、ADD及びDROPの1チャネルずつも制御用のものとされて、光TS-SW部30Jを制御するためのスイッチ制御部30kに接続されている。スイッチ制御部30kも、APD,LIM,CDRを備えて構成されている。
図61は図60に示すTWC1~TWC8(又はTWC[A]1~TWC[A]3)の一構成例を示すブロック図である。
図63に示す光TS-SW部30Kは、波長多重信号(WDMi)を分波するAWG30bと、複数のN×1 SW30mと、DROP用N×1 SW30nと、ADD用TWC30dと、複数のN×1SWからの光信号を合波するカプラ30pとを有する。N×1 SW30mは、半導体光増幅器(SOA)を含む構成である。
次に、第6の実施形態について、図面を参照して説明する。
(a)各光スイッチノード121から流入するトラヒック量を定期的に収集し、トラヒック量に対応させて各スイッチノード121に割り当てるTS量を決定する、
(b)異なる光スイッチノード121のバッファ-バッファ間の伝搬遅延時間を考慮に入れて、割り当てたTSに従って動作開始するタイミングを指定する、
(c)一定周期(T)毎に各光スイッチノードから収集したトラヒック量に応じてタイムスロットの再割当を実施する、
という機能を有する。上述したように、マスターノード120は光スイッチノード内に存在してもよい。
光スイッチノード121は、
(a)外部ネットワークからの入力信号をバッファに蓄積し、宛先ごとのデータ量をマスターノード120に報告する、
(b)マスターノード121から設定されたTSテーブルに従い、自バッファからのデータ送信(ADD)とWDM/TDMスイッチにおける方路変更を行う、
(c)マスターノード121から再度TSテーブルが設定されるまで、一定周期(周期t)に対する動作情報が記されたTSテーブルに従い、送信/スイッチ切り替え動作を行う、
という機能を有する。このような光スイッチノード121は、後述するように、ADD/DROPとWDM/TDMスイッチとを実現する光TS-SW部を備える。
図69は、このような制御によって光スイッチノード121からマスターノード120にトラヒック情報を送る際の手順を示している。
この手順を説明する。ステップ211において、マスターノード120が制御信号により各光スイッチノード121に制御用のタイムスロットの割り当てを行う。次に、ステップ212において、光スイッチノード121は、外部通信装置190から送信されてくるデータパケットを受信し、トラヒック量を測定する。ステップ213において、光スイッチノード121は、そのトラヒック量をトラヒック情報としてマスターノード120へ送信する。
次に、ステップ214において、マスターノード120が、そのトラヒック情報からトラヒック量を把握し、トラヒック量に応じたタイムスロットの割り当て量(タイムスロット長)を計算する。ステップ215において、その計算されたタイムスロット長を光スイッチノード121へ通知する。ステップ216において、光スイッチノード121は、その通知されたタイムスロット長のタイムスロットを設定してデータの送信を行う。
図70は、バッファあふれの予測を説明する図である。TS送受信部146内に複数の仮想キュー1~Nが設定されているものとする。仮想キューにおける残メモリ部分の減少度合いから、バッファが何秒後にあふれるかを予測する。時刻tと時刻t+1との時間間隔をΔTとし、この間に、仮想キューの残メモリがΔdataだけ減少したとすると、[(時刻t+1での残メモリ量)/Δdata」×ΔTが、バッファあふれ発生までの予測時間ということになる。
図72は、TS開始配信とTS同期をトリガによって行う場合に想定される各種の例を示している。ここでは、例えば波長多重によって、トリガとデータとが同一経路で伝送されることを前提としている。
これに対し物理トポロジが双方向の場合には、図86Bに示すように、光スイッチノード121Bにおいて、制御信号受信部、TS情報管理部および時刻カウンタのそれぞれについて左回り用と右回り用との2つずつ設ける。図では、右回り用のものとして、制御信号受信部143b、TS情報管理部148bおよび時刻カウンタ149bが示されている。マスターノード120は、リングの右回り、左回りに制御信号を送信し、各光スイッチノード121A,121Bは、制御信号の送受信方向に対応したTS情報管理部のTS情報と時刻カウンタとに基づいて動作を行う。例えば、右回りの制御信号を受信したら、右回り用のTS情報管理部48bを利用する。
図示したノードAの場合であれば、時刻カウンタ100~120のタイムスロットTS0においてADDを実施し、時刻カウンタ140~160でタイムスロットTS2にADDする。ノードAは、次のTS開始時刻が送信されるまで、この動作を繰り返す。その後、ノードBは、[5]に示すように、制御信号を再度受信したら、その制御信号のタイムスタンプ値に自ノードの時刻カウンタを設定する。その後、[6]に示すように、ノードBは、時刻カウンタがTS開始時刻になったら、タイムスロットTS0から順に動作する。ここに示したノードの場合であれば、時刻カウンタ100((時刻カウンタ=TS開始時刻+TS番号×TS長)~120においてTS0をDROPし、時刻カウンタ120~140でにおいてS2にADDする。次のTS開始時刻が送信されるまで、このTS情報による動作を繰り返す。
この説明では、図91Aに示すように、リング接続されたマスターノード120に[1]、ノード121aに[2]、ノード121bに[3]を付して、各ノード[1]~[3]として表わし、図91Bにも同符号[1]~[3]を示してノードを表している。
図91Aに示すリングの左回りにおいて、マスターノード[1]のTS開始時刻を、図91Bに時刻t1で示す。左回りにおいて、マスターノード[1]とノード「2」間の信号送信時の遅延時刻はaなので、時刻t1+a=t2がノード[1]の左回りのTS開始時刻となる。同様に、マスターノード[1]とノード[3]間の遅延時刻はa+bなので、時刻t1+a+b=t3がノード[3]の左回りのTS開始時刻となる。
次に、右回りにおいて、マスターノード[1]とノード「3」間の遅延時刻はcなので、時刻t1+c=t2aがノード[3]の右回りのTS開始時刻となる。同様に、マスターノード[1]とノード[2]間の遅延時刻はc+bなので、時刻t1+c+b=t4がノードの右回りのTS開始時刻となる。
図示したものでは、前段から波長多重によって伝送された光信号は分波器141により波長λ1~λ8に分波され、これらの分波された光信号は、それぞれ、TWC1~TWC8を介してAWG144iの入力ポートに与えられている。これらとは別に、挿入されるべき光信号が、TWC[A]1~TWC[A]3を介してAWG144iの入力ポートに与えられている。AWG144iの出力ポートのうち8個は次段への伝送用であり、これらの出力ポートからの光信号はそれぞれFWC1~FWC8を経て合波器142に入力し、波長多重されて次段に伝送される。それとは別に、AWG144iには分岐(DROP)に用いられる出力ポートがあり、この出力ポートには、光受信器144jが接続されている。光受信器144jは、光電変換を行う光電素子(APD)と、光信号間のパワー差を吸収するためのリミッティング増幅器(LIM)と、光信号間での位相差を吸収するためのクロック・データ・リカバリ回路(CDR)とがこの順で直列に接続した構成を有し、信号間のパワー差/位相差を吸収して光信号を受信する。なお、図96に示したものでは、波長λ8は、制御用の固定波長とされている。また、ADDおよびDROPの1チャネルずつも制御用のものとされて、光TS-SW部144を制御するためのスイッチ制御部に接続されている。
次に、第7の実施形態について、図面を参照して説明する。 まず、図110を参照して、タイムスロット同期の定義について説明する。
マルチリング302は、上位リング303と、複数の下位リング304とが、リング交換点ノードAで接続されて構成されている。
(1)リング交換点ノードAと下位リング304の各ノードBとにおいて基準タイムスロット(第1のタイムスロット)305を動作させる。
(2)リング交換点ノードAは、矢印Y20で示すTS1のように送信が行われる下位リング304のノードBに対して、自ノードにおける基準タイムスロット(第1のタイムスロット)305に対して同期したオフセット値(遅延時間)DB分ずらした上位リング303向けタイムスロット(第2のタイムスロット)306を設定する。但し、オフセット値DBとは、マルチリング302に示すノードBからリング交換点ノードAへの伝搬遅延時間DBに対応している。
これにより、ノードBの上位リング303向けタイムスロット306と、リング交換点ノードAの基準タイムスロット305とを同期させる。そして、ノードBにおいて、上位リング303から下位リング304への矢印Y20で示す下り通信には基準タイムスロット305を用い、下位リング304から上位リング303への矢印Y21で示すTS5のように送信が行われる上り通信には上位リング向けタイムスロット306を用いる。但し、TS5はデータ挿入対象のタイムスロットである。
(1)起点ノードA0何れは、基準タイムスロットを開始し、起点ノード以外の各ノードに対して基準タイムスロットを同期させる。基準タイムスロットの同期方法は、起点ノードA0が起点ノードA0内の基準タイムスロット開始位置のタイミングで送信した同期フレーム(同期フレーム内には同期フレームを送信した時の起点ノード内の時刻値を挿入している)を、起点ノード以外の各ノードに配信し、起点ノード以外の各ノードは、起点ノードA0からの同期フレームを受信すると、同期フレーム内の時刻値を自ノードの現在時刻として設定し、基準タイムスロットを開始する。これにより、起点ノードA0と起点ノード以外のノード間で基準タイムスロット308が同期される。この基準タイムスロット308を用いることで、同期フレームを配信した方向に対する、異なるノード間でのタイムスロットのADD/DROPが可能となる。
(2)リング交換点ノードAは、下位リング304の各ノードBに対して、リング交換点ノードAの基準タイムスロット308に同期した上位リング向けタイムスロット309を設定する。下位リング304の各ノードBにおける上位リング向けタイムスロット309を設定するために、リング交換点ノードAは下位リングBのリング1周遅延を測定する。
これは、マルチリング302において、下位リング304の各ノードBから送信したタイムスロット309がリング交換点ノードAにD1時間後に到着することと、下位リング304の各ノードBの基準タイムスロットの開始タイミングがリング交換点ノードAの基準タイムスロット308に対してD2時間遅れていることの和(D1+D2)が、下位リング1周遅延時間になることに起因する。但し、D1時間とは、下位のノード(例えばB)から上位のノード(例えばA)に向かう経路の遅延時間であり、D2時間とは、その逆に、上位のノードAから下位のノードBに向かう経路の遅延時間である。
このことから、下位リング304の各ノードBの上位リング向けタイムスロット309は、下位リング304の各ノードB自体の基準タイムスロットのタイムスロット開始タイミングに対して、リング1周時間早く開始することで、リング交換点ノードAの基準タイムスロット308のタイムスロット開始タイミングに合わせることができる。
下位リング1周遅延時間の測定の方法は、(a)リング交換点ノードAが下位リング1周遅延測定フレームを送信し、(b)リング交換点ノードAが下位リング1周したリング1周遅延測定フレームを受信し、(c)、(a)(b)処理時のカウンタ値を引き算することで測定する。
(3)下位リング304の各ノードBは、自ノードの基準タイムスロット308に対して、オフセット値分だけタイムスロット開始タイミングをずらしたタイムスロット(上位リング向けタイムスロット)309を刻む。これにより、下位リング304の各ノードBの上位リング向けタイムスロット309とリング交換点ノードAの基準タイムスロット308とを同期させる。リング交換点ノードAは、下位リング304の各ノードBに対して、上位リング向けタイムスロット309の刻みを開始させるための同期フレームを送信する。この時、リング交換点ノードAは同期フレーム内に測定した下位リング1周遅延をタイムスタンプとして付与して送信する。送信するタイミングは、下位リング304の各ノードBにおける基準タイムスロットの先頭位置で同期フレームが届くように、下位リング1周時間を測定した後の基準タイムスロットのタイムスロット周期の開始タイミングとする。下位リング304の各ノードBは、同期フレームを受信した後、自ノードの基準タイムスロット308に対して、同期フレーム内に記載された下位リング1周時間分早めて上位リング向けタイムスロット309を刻む。具体的には、同期フレーム受信時の基準カウンタ値に同期フレーム内のタイムスタンプ値を足した値を初期値として、上位リング向けタイムスロット用のカウンタを開始させる。この上位リング向けタイムスロット309を用いることで下位リング304のノードBから上位リング303のノードA0へのタイムスロット送受信が可能となる。
(1)基準タイムスロットを全ノード間で同期させる。基準タイムスロットの同期方法は、起点ノードA0から起点ノード以外のノードに同期フレームを配信することで実現する。同期フレームの通信として、データ用の波長とは別の制御用波長を用いることでノード間のリーチャビリティを確保する。
具体的には、起点ノードA0は自ノード内の基準タイムスロットの先頭開始位置で同期フレームを送信する。起点ノード以外のノードは光カプラで制御信号をコピーすることで同期フレームを受信し、同期フレームを受信したタイミングから基準タイムスロット用のビットカウンタを開始し、基準タイムスロットの刻みを開始する。本カウンタはタイムスロット周期とタイムスロット長のカウントを行うためのものであり、ローカルクロック周波数の1クロック毎にカウントアップする。この結果、基準タイムスロットはノード間の伝搬遅延時間分だけタイムスロット周期の開始時間が遅れて動作し、各ノード間で基準タイムスロットを同期させることができる。この基準タイムスロットを用いることで、同期フレームを送信した方向における異なるノード間でのタイムスロットのADD/DROPが可能となる。
(2)リング1周遅延測定では、起点ノードA0の基準タイムスロットに合わせて起点ノード以外のノードの跨ぎ用タイムスロットのタイムスロット開始タイミングを合わせるために、起点ノードA0がリング1周遅延を測定する。これは、起点ノード以外のノードから送信したタイムスロットが起点ノードA0にD1時間後に到着することと、起点ノード以外のノードの基準タイムスロットのタイムスロット開始タイミングが、起点ノードA0の基準タイムスロット対してD2時間遅れていることの和が、リング1周遅延時間(D1+D2)になることに起因する。
このことから、起点ノード以外のノードの跨ぎ用タイムスロットは、自ノード(起点ノード以外のノード)の基準タイムスロットのタイムスロット開始タイミングに対して、リング1周時間早く開始することで起点ノードA0の基準タイムスロットのタイムスロット開始タイミングに合わせることができる。
リング1周遅延時間の測定の方法は、(a)起点ノードA0が同期フレームを送信し、(b)起点ノードがリング1周した同期フレームを受信し、(c)、(a)(b)処理時のカウンタ値を引き算することで測定する。
(3)起点ノードA0の基準タイムスロットに同期した跨ぎ用タイムスロットの設定について説明する。起点ノードA0は、起点ノード以外のノードに対して、跨ぎ用タイムスロットの刻みを開始させるための同期フレームを送信する。この時、起点ノードA0は同期フレーム内に測定したリング1周遅延をタイムスタンプとして付与して送信する。送信するタイミングは、起点ノード以外のノードの基準タイムスロットのタイムスロット開始位置で同期フレームが届くように、リング1周時間を測定した後の基準タイムスロットのタイムスロット開始位置とする。
各起点ノード以外のノードは、同期フレームを受信した後、自ノードの基準タイムスロットに対して、同期フレーム内に記載されたリング1周時間分早めることにより、跨ぎ用タイムスロットを刻む。具体的には、同期フレーム受信時の基準カウンタ値に同期フレーム内のタイムスタンプ値を足した値を初期値として、跨ぎ用カウンタを開始させる。この跨ぎ用タイムスロットを用いることで起点ノード以外のノードから起点ノードA0へのタイムスロット送受信が可能となる。
M-C331は、各ノード332,333に対してタイムスロットを開始させる同期フレームの送信と、・各ノード332,333間の伝搬遅延時間の測定・オフセット値の算出とを行う。
SubM-C332の主な役割は次の通りである。
SubM-C332は、各ノード332,333ですでに動作しているタイムスロットに対して、算出したオフセット値分ずらした新規タイムスロットを開始させる複数タイムスロット開始用フレームを送信するものであり、リング交換点に位置し、光スイッチ部311(図113参照)を制御する。
S-C333は、M-C331の指示に従い複数のタイムスロットを刻む。また、M-C331により割り当てられたタイムスロットに従って、自ノード内部の光スイッチ部311とバッファ部312の制御を行う。
また、タイムスロット開始タイミングの設定は、各ノード331~333において周期的に動作するタイムスロットの開始タイミングを、各ノード332,333と起点ノード331間の伝搬遅延時間分だけずらすために行う。
まず、光ネットワークシステム上に起点ノード331を1台設ける。そして、起点ノード331から、起点ノード以外の各ノード332a,333bに対してタイムスロット開始タイミングt10を決定するための同期フレームを矢印Y25,Y26で示すように送信する。起点ノード以外の各ノード332,333は、同期フレーム受信時にタイムスロット動作を開始させる。この結果、起点ノード以外の各ノード332a,333bで動作するタイムスロットの開始タイミングは、各ノード332a,333bと起点ノード331間の伝搬遅延時間「150,200」分ずれて動作することになる。
即ち、起点ノード331のタイミング時刻t10から伝送遅延「150」分ずれた時刻t11aが、ノード332aのバースト送信周期に同期したタイムスロットの開始タイミングとなり、更に、タイミング時刻t10から伝送遅延「150+200=350」分ずれた時刻t13aが、ノード333bのバースト送信周期に同期したタイムスロットの開始タイミングとなる。
以降では、基準タイムスロットの中で、図115Aにおいて、起点ノード331から矢印Y25,Y26の方向へ送信されるタイムスロットを順方向タイムスロットと呼ぶ。
起点ノード331は、起点ノード331内部の現在の時刻をタイムスタンプとして同期フレームに付与し、起点ノード以外の各ノード332,333に対して同期フレームを送信する。起点ノード以外の各ノード332,333は、同期フレームを受信した時に、同期フレーム内のタイムスタンプを自ノードの現在時刻として設定する。この結果、起点ノード以外の各ノード332,333の時刻は、起点ノード331との間の伝搬遅延時間分ずれて設定されることになる。
このとき、アクティブな光スイッチ部311を経由して同期フレームを各ノード332,333に送信するため、同期フレームの送信には、データ用の波長とは別に制御用波長を用いる。
このとき、遅延測定フレームは、起点ノード331が同期フレームを送信した経路を通って送信する。遅延測定フレームを同期フレームと同じ経路を通すことで、ノード331~333間の伝搬遅延時間を測定可能とする。なお、遅延測定フレームの送信は、各ノード331~333からの遅延測定フレームが衝突する可能性があるため、ランダムなタイミングで繰り返し送信する。もしくは各ノード331~333に対して割り当てられたタイムスロットに従い送信する。また、遅延測定フレームは、アクティブな光スイッチを経由して各ノード331~333に送信されるため、データ用の波長とは別に制御用波長を用いる。
また、起点ノード331は起点ノードを跨いだ通信用タイムスロットに用いるためにリング1周遅延時間を測定する。リング1周遅延時間の測定の方法は、(a)起点ノード331がリング1周遅延測定フレームを送信し、(b)起点ノード331がリング1周したリング1周遅延測定フレームを受信し、(c)、(a)(b)処理時のカウンタ値を引き算することで測定する。
図119Aを参照して、同期フレームと遅延測定フレームの経路が対称である場合について説明する。
起点ノード以外の各ノード332,333は、同期フレーム内のタイムスタンプを自ノードの現在時刻として設定し、その時刻(または、その時刻から各ノードのローカルクロックに従って刻んだ時刻)をタイムスタンプとして付与した遅延測定フレームを起点ノード宛に、矢印Y30で示す方向に送信される同期フレームと同経路を、矢印Y31で示すように逆方向に送信する。このとき、起点ノード331に必ず遅延測定フレームが届くように、光スイッチ部311とは別の経路で光カプラ322を置き、遅延測定フレームを送信する。
次に、図119Bを参照して同期フレームと遅延測定フレームの経路が非対称である場合について説明する。
起点ノード以外の各ノード332,333は、各ノード(起点ノードを含む)331~333に共通となる時刻(共通時刻)を設定し(例えば、GPS受信器324を用いる)、その共通時刻をタイムスタンプとして付与した遅延測定フレームを起点ノード331宛に、矢印Y30で示す方向に送信される同期フレームの経路とは異なる経路で、矢印Y32で示すように同じ方向に送信する。
(A)複数のノード331~333で制御用波長を共有するときには、各ノード331~333がランダムなタイミングで遅延測定フレームを送信し続けることで、起点ノード331まで各ノード332,333からの遅延測定フレームを到達させる。2回目以降の測定においては、起点ノード331と各ノード332,333間の遅延時間をもとに同期した制御用のタイムスロットを用いることで、異なるノード332,333間での遅延測定フレームの衝突回避が可能となる。
(B)ノード331~333毎に個別の制御用波長を用いてP-to-Pに遅延測定フレームを起点ノードに送信してもよい。
例えば、片方向通信(各ノードに対して、片側回りでデータ到着)の2段リングの場合、上位リングと下位リングのタイムスロット数は次の(1)、(2)ようになる。
(1)上位リングのタイムスロット数は、2つ(順方向タイムスロット、リング1周用タイムスロット)である。
(2)下位リングのタイムスロット数は、4つ(順方向タイムスロット、リング1周用タイムスロット、上位リングの順方向タイムスロット向けタイムスロット、上位リングのリング1周用タイムスロット向けタイムスロット)である。
次に、図122A、図122Bを参照して、下位リング336から上位リング335向けのタイムスロットについて説明する。
(1)上位リング335のノード332aに対して、下位リング336bのノード333bのタイムスロット開始タイミングは、図122Bに時刻t11aとt13aで示すように伝搬遅延時間D45だけ遅い。
(2)下位リングノード333bから送信したタイムスロットのデータは、上位リングノード332aにおいて、矢印Y35で示すように伝搬遅延時間D54だけ遅れて到着する。
次に、図123Bを参照して説明する。但し、図123Bには、起点ノード331をM-Cと表わしている。また、図123Aおよび図123Bの説明において、t:タイムスロット周期、t0:タイムスロット長とする。
[1]順方向タイムスロットは、上位リングにおいて、M-C内部の順方向タイムスロットに対してDn時間遅れたタイムスロットであり、下位リングにおいて、M-C内部の順方向タイムスロットに対してDs+Dp時間遅れたタイムスロットとなる。
[2]逆方向タイムスロットは、上位リングにおいて、自ノード内部の順方向タイムスロットに対して2Dn時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(2Dn,t)時間分遅めたタイムスロット(ここで、MOD(A,B)は、A÷Bの余りを意味する。例えば、MOD(3,2)=1、MOD(2,7)=2、以下、同じとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(2Dn,t0)時間分遅めたタイムスロットとなる。
下位リングにおいて、自ノード内部の順方向タイムスロットに対して、2(Ds+Dp)時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(2(Ds+Dp),t)時間分遅めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(2(Ds+Dp),t0)時間分遅めたタイムスロットとなる。
[3]順方向跨ぎタイムスロットは、上位リングにおいて、自ノード内部の順方向のタイムスロットに対して、Dru時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(Dru,t)時間分遅めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(Dru,t0)時間分遅めたタイムスロットとなる。
下位リングにおいて、自ノード内部の順方向のタイムスロットに対して、Drl時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(Drl,t)時間分遅めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(Drl,t0)時間分遅めたタイムスロットとなる。
[4]逆方向跨ぎタイムスロットは、上位リングにおいて、自ノード内部の順方向のタイムスロットに対して、2Dn-Dru時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(2Dn-Dru,t)時間分遅めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(2Dn-Dru,t0)時間分遅めたタイムスロットとなる。
下位リングにおいて、自ノード内部の順方向のタイムスロットに対して、2(Ds+Dp)-Drl時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(2(Ds+Dp)-Drl,t)時間分遅めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(2(Ds+Dp)-Drl,t0)時間分遅めたタイムスロットとなる。
[5]上位リング順方向跨ぎ用タイムスロット向けタイムスロットは、下位リングにおいて、自ノード内部の順方向タイムスロットに対して、Dru+Drl時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(Dru+Drl,t)時間分遅めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(Dru+Drl,t0)時間分遅めたタイムスロットとなる。
[6]上位リング逆方向跨ぎ用タイムスロット向けタイムスロットは、下位リングにおいて、自ノード内部の順方向タイムスロットに対して、2(Ds+Dp)-(Dru+Drl)時間分進めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t-MOD(2(Ds+Dp)-(Dru+Drl),t)時間分遅めたタイムスロットとなる。
もしくは、自ノード内部の順方向のタイムスロットに対して、t0-MOD(2(Ds+Dp)-(Dru+Drl),t0)時間分遅めたタイムスロットとなる。
ここで、順方向通信における下位リング377から上位リング357への跨ぎ通信とは、図126Dに双方向矢印Y42bで示す下位リング377のノードであるS-C373とSubM-C371との間を、矢印Y52で示すように順方向に信号が通過することである。即ち、図126Bに示すように、下位リング377のノード373のタイムスロットが上位リング順方向跨ぎ用タイムスロット向けタイムスロット378となる。なお、図126Dの同じ矢印Y52で示すように、双方向矢印Y42aで示す上位リング357のノードであるS-C353とM-C351との間を、順方向に信号が通過する場合は、M-C351の跨ぎ通信(順方向跨ぎ通信)となる。
ここで、逆方向通信における上位リング357から下位リング377への跨ぎ通信とは、図127Dに双方向矢印Y42bで示す上位リング357のノードであるSubM-C371と下位リング377のS-C373との間を、矢印Y56で示すように逆方向に信号が通過することである。即ち、図127Bに示すように下位リング377のノード373のタイムスロットは上位リング逆方向跨ぎ用タイムスロット向けタイムスロット383となる。なお、図127Dの同じ矢印Y56で示すように、双方向矢印Y42aで示す上位リング357のノードであるS-C353とM-C351との間を、逆方向に信号が通過する場合は、M-C351の跨ぎ通信(逆方向跨ぎ通信)となる。
また、図128に示すように、伝搬遅延時間D1~D4は、M-C[1]とS-C[2]間がD1、M-C[1]とSubM-C[3]間がD2、M-C[1]とSubM-C[4]間がD3、SubM-C[3]とS-C[5]間がD4となっている。
この例の場合、制御用順方向タイムスロット開始時刻カウンタ値は、送信に用いた制御用順方向タイムスロットの先頭カウンタ値の「300」である。制御用順方向タイムスロット開始タイムスロット番号は、SubM-C[3]に対応する制御用順方向タイムスロットのタイムスロット番号の「TS3」である。データ用順方向タイムスロット開始時刻カウンタ値は、送信に用いた制御用順方向タイムスロットの直後のデータ用順方向タイムスロットの区切りの先頭カウンタ値の「450」である。データ用順方向タイムスロット開始タイムスロット番号は、SubM-C[3]に対応するデータ用順方向タイムスロット番号の「TS2」である。
次に、図131を参照して、上位リングのSubM-C[3],[4]における初期時刻カウンタ値の受信時の動作シーケンスについて説明する。
また、SubM-C[3]は、データ用順方向タイムスロット開始時刻カウンタ値の「450」も受信するので、その「450」も刻む。
また、M-C[1]は、左回り、右回りの両方から同時に同期フレームを配信する場合もある。
この制御用順方向タイムスロット以外に、データ用タイムスロットの刻みも同時に行っている。
下位リング内のタイムスロットへのADD、上位リングへのタイムスロットのADDで異なるタイムスロットで動作する必要がある。
21 トリガ検出部
22 光SW制御部
23 送信制御部
26 制御信号処理部
50 トリガ生成部
60 TS情報配信部
80 TS開始配信部
81 制御信号生成部
90 遅延時間算出部
20,25,145 TS同期部
30,152 光TS-SW部
40,153 TS送受信部
101A~101D 光スイッチノード
120 光マスターノード(マスターノード)
121 光スイッチノード
122 データ線
123,124 制御線
31,141 分波部
32,142 合波部
133,143,143a,143b 制御信号受信部
134 トラヒック情報収集部
135 トポロジ管理部
136 TS(タイムスロット)割当部
137 TS開始配信部
138 TS情報配信部
139 時刻配信部
144 光TS-SW(スイッチ)部
145 TS同期部
146 TS送受信部
147 トラヒック情報送信部
148,148a,148b TS情報管理部
149,149b 時刻カウンタ
150 内部クロック
311 光スイッチ部
312 バッファ部
313 制御情報送信部
314 基準TS同期部
315 遅延測定部
316 複数TS管理部
317 カウンタ管理部
318 内部クロック部
319 TS制御部
320 TS量更新時算出部
321 制御情報受信部
530 ROADM(再構成可能光分岐挿入多重)装置
531 光ファイバネットワーク
Claims (25)
- マスターノードおよび複数の光スイッチノードを含む光ネットワークシステムであって、
前記マスターノードは、任意の波長による波長パスを一定時間のタイムスロットに分割し、前記タイムスロットを前記光スイッチノードの各々に割り当て、
前記光スイッチノードの各々は、前記マスターノードから配信される情報に基づいて、前記タイムスロットの同期を取ってデータの送受信または方路切替を行うことを特徴とする光ネットワークシステム。 - 前記光スイッチノードの各々は、前記マスターノードから配信されるトリガに基づいて、前記タイムスロットの同期を取ることを特徴とする請求項1に記載の光ネットワークシステム。
- 前記トリガに、データ処理に関する指示内容を示すタイムスロット情報が含まれることを特徴とする請求項2に記載の光ネットワークシステム。
- 前記マスターノードは、タイムスロット開始時刻およびタイムスタンプを含む制御信号を前記光スイッチノードの各々に配信し、
前記光スイッチノードの各々は、前記マスターノードから前記制御信号を受信すると、伝送遅延時間分だけずれた時間を設定することで決まる、前記光スイッチノードの各々に共通した時刻に基づいて、前記タイムスロットの同期を取ってデータの送受信または方路切替を行うことを特徴とする請求項1に記載の光ネットワークシステム。 - 前記マスターノードが前記光スイッチノードの各々に、データ処理に関する指示内容を示すタイムスロット情報を配信することを特徴とする請求項4に記載の光ネットワークシステム。
- 前記マスターノードは、タイムスロット開始時刻およびタイムスタンプを含む制御信号を前記光スイッチノードの各々に配信し、
前記光スイッチノードの各々が共通時刻の情報を共有し、前記光スイッチノードの各々は、前記マスターノードから前記制御信号を受信すると、該制御信号の受信時刻から該タイムスタンプの値を引いた遅延時間に基づいて、前記タイムスロットの同期を取ってデータの送受信または方路切替を行うことを特徴とする請求項1に記載の光ネットワークシステム。 - 波長多重による光伝送を行うリング型の光ネットワークを更に備え、
前記光スイッチノードの各々は、前記光ネットワークに設けられ、光スイッチ動作とデータの挿入および分岐とを行い、
前記マスターノードは、前記光ネットワーク上でのデータの衝突が起こらないように前記光スイッチノードの各々に対してタイムスロットを割り当て、割り当てたタイムスロットを示すタイムスロット情報を当該光スイッチノードの各々に配信し、前記光スイッチノード間のトラヒック量に応じて前記タイムスロットの割り当てを行うことにより帯域割り当てを可能にした
ことを特徴とする請求項1に記載の光ネットワークシステム。 - 前記マスターノードは、前記光スイッチノードの各々から送信されてくるトラヒック情報を集計するトラヒック情報収集部と、前記集計したトラヒック情報を使用して前記光スイッチノードの各々に対するタイムスロットの割り当てを行うタイムスロット割当部と、前記タイムスロット情報を配信するタイムスロット配信部と
を備え、
前記光スイッチノードは、光スイッチ動作とデータの挿入および分岐とを行う光タイムスロットスイッチ部と、当該光スイッチノードに接続する外部通信装置と光タイムスロットスイッチ部との間でのデータの送受信を行うタイムスロット送受信部と、当該光スイッチノード宛ての前記タイムスロット情報に基づいて、前記光タイムスロットスイッチ部での光スイッチ動作および前記タイムスロット送受信部での送受信タイミングを制御するタイムスロット同期部と
を備えることを特徴とする請求項7に記載の光ネットワークシステム。 - 前記マスターノードは、タイムスロットの開始を示すトリガを所定周期で発生するタイムスロット開始配信部を備えて前記タイムスロット情報と前記トリガとを前記同一経路で配信し、
前記光スイッチノードにおいて前記タイムスロット同期部は、当該光スイッチノードが受信した前記トリガを検出して、該トリガに基づき、前記タイムスロット情報によって指定された処理を実行するように前記光タイムスロットスイッチ部および前記タイムスロット送受信部を制御する
ことを特徴とする請求項8に記載の光ネットワークシステム。 - 前記光ネットワークにおいて、前記トリガは、当該光ネットワークにおける制御用波長を用いて、または、前記光スイッチノード間のデータの伝送に用いられるものとは異なるファイバを用いて伝送される
ことを特徴とする請求項9に記載の光ネットワークシステム。 - 前記タイムスロットの時間長または前記タイムスロットの繰返し周期を、前記光ネットワークの1周の伝搬遅延の整数分の1に設定する
ことを特徴とする請求項7乃至10のいずれか1項に記載の光ネットワークシステム。 - 前記タイムスロット情報は、対応するタイムスロットの開始時刻に関する情報を含み、
前記光スイッチノードの各々は、当該光スイッチノードでのローカル時刻に基づいて、前記開始時刻に応じて前記タイムスロット情報で指定された処理を実行する
ことを特徴とする請求項7または8に記載の光ネットワークシステム。 - 前記マスターノードは、当該マスターノードのローカル時刻をタイムスタンプとして有する時間同期フレームを前記光スイッチノードに配信する時刻配信部を備え、
前記時間同期フレームを受信した前記光スイッチノードの各々は、前記タイムスタンプで示される時刻に当該光スイッチノードのローカル時刻を設定する
ことを特徴とする請求項12に記載の光ネットワークシステム。 - 前記光ネットワークにおいて、前記時間同期フレームは、当該光ネットワークにおける制御用波長を用いて、または、前記光スイッチノード間のデータの伝送に用いられるものとは異なるファイバを用いて伝送される
ことを特徴とする請求項13に記載の光ネットワークシステム。 - 前記マスターノードおよび前記光スイッチノードの各々に、伝搬遅延に依存しない共通の時刻がローカル時刻として設定され、
前記マスターノードは、前記光スイッチノードの各々に対する伝搬遅延時間の測定結果に基づいて、データの衝突が起こらないように前記タイムスロットの割り当てを行う
ことを特徴とする請求項12に記載の光ネットワークシステム。 - 前記マスターノードは、複数の前記光スイッチノードの中の1つに設けられる
ことを特徴とする請求項7に記載の光ネットワークシステム。 - 単一のリングからなるシングルリングネットワークまたは複数のリングが多段接続されてなるマルチリングネットワークを備え、
前記リング上の1台のノードを前記マスターノードとし、
前記マスターノードは、
前記マスターノード以外の前記光スイッチノードである各ノードの時刻を設定し、
前記マスターノード以外の各ノードは、
前記マスターノードにより設定された時刻から第1のタイムスロットを刻み、
前記マスターノードは、
前記マスターノードと前記マスターノード以外の各ノードとの間の伝搬遅延時間と、前記リングの1周分の伝搬遅延時間とを基に、前記マスターノード以外のノードのうちの特定ノードのオフセット値を算出し、算出したオフセット値を前記特定ノードに設定し、
前記特定ノードは、
自ノードの第1のタイムスロットの開始タイミングを、前記マスターノードにより設定されたオフセット値分だけずらした第2のタイムスロットを刻む
ことを特徴とする請求項1に記載の光ネットワークシステム。 - 前記マスターノードは、
前記マスターノード内部の現在時刻をタイムスタンプとして付与した同期フレームを、前記マスターノード以外の各ノードに対して送信し、
前記マスターノード以外の各ノードは、
前記同期フレームの受信時に、当該同期フレーム内のタイムスタンプを、自ノード内部の現在時刻として設定し、
自ノード内部の現在時刻をタイムスタンプとして付与した遅延測定フレームを、前記マスターノードに対して送信し、
前記マスターノードは、
前記遅延測定フレームの受信時に、当該遅延測定フレーム内のタイムスタンプと前記マスターノード内部の現在時刻とを基に、前記マスターノードと前記マスターノード以外の各ノードとの間の伝搬遅延時間を測定する
ことを特徴とする請求項17に記載の光ネットワークシステム。 - 前記光ネットワークシステムは、前記シングルリングネットワークからなり、
前記マスターノードは、
前記同期フレームを、自ノードに対して送信し、
前記同期フレームの受信時に、当該同期フレーム内のタイムスタンプと当該マスターノード内部の現在時刻とを基に、前記リングの1周分の伝搬遅延時間を測定する
ことを特徴とする請求項18に記載の光ネットワークシステム。 - 前記マスターノードは、
前記マスターノードと前記マスターノード以外の各ノードとの間の伝搬遅延時間の測定結果と、前記リングの1周分の伝搬遅延時間の測定結果とを基に、タイムスロットの方向および前記マスターノードの跨ぎの有無を考慮して、前記特定ノードに設定するオフセット値を決定する
ことを特徴とする請求項19に記載の光ネットワークシステム。 - 前記マルチリングネットワークは、上位リングと下位リングとがリング交換点ノードで接続されてなり、前記マスターノードは、前記上位リング上のノードであり、
前記マスターノードは、
前記同期フレームを、自ノードに対して送信し、
前記同期フレームの受信時に、当該同期フレーム内のタイムスタンプと当該マスターノード内部の現在時刻とを基に、前記上位リングの1周分の伝搬遅延時間を測定し、
前記リング交換点ノードは、
前記同期フレームを、自ノードに対して送信し、
前記同期フレームの受信時に、当該同期フレーム内のタイムスタンプと前記リング交換点ノード内部の現在時刻とを基に、前記下位リングの1周分の伝搬遅延時間を測定する
ことを特徴とする請求項18に記載の光ネットワークシステム。 - 前記マスターノードは、
前記マスターノードと当該マスターノード以外の各ノードとの間の伝搬遅延時間の測定結果と、前記上位リングおよび前記下位リングの1周分の伝搬遅延時間の測定結果とを基に、タイムスロットの方向、前記マスターノードの跨ぎの有無、前記上位リングから前記下位リングへの跨ぎの有無および前記下位リングから前記上位リングへの跨ぎの有無を考慮して、前記特定ノードに設定するオフセット値を決定する
ことを特徴とする請求項21に記載の光ネットワークシステム。 - マスターノードと伝送路を介して接続される光スイッチノードであって、
前記マスターノードから配信される情報に基づいて、前記マスターノードに割り当てられた一定時間のタイムスロットの同期を取ってデータの送受信または方路切替を指示するタイムスロット同期部と、
前記タイムスロット同期部からの指示にしたがって、前記データの送受信または方路切替を行う光タイムスロットスイッチ部と
を備えることを特徴とする光スイッチノード。 - 複数の光スイッチノードと伝送路を介して接続されるマスターノードであって、
任意の波長による波長パスを一定時間のタイムスロットに分割し、該タイムスロットを前記光スイッチノードの各々に割り当てるタイムスロット同期部と、
前記光スイッチノードの各々に前記タイムスロット同期部が割り当てたタイムスロットと同期を取ってデータの送受信または方路切替を実行させるための情報を、該光スイッチノードの各々に配信する光タイムスロットスイッチ部と
を備えることを特徴とするマスターノード。 - 単一のリングからなるシングルリングネットワークまたは複数のリングが多段接続されてなるマルチリングネットワークからなる光ネットワークシステムにおいて、前記リング上に存在するノードであって、
自ノードがマスターノードである場合、前記マスターノード以外の各ノードの時刻を設定するタイムスロット制御部と、
自ノードが前記マスターノード以外のノードである場合、当該マスターノードにより設定された時刻から第1のタイムスロットを刻む基準タイムスロット同期部と、
自ノードが前記マスターノードである場合、当該マスターノードと当該マスターノード以外の各ノードとの間の伝搬遅延時間と、前記リングの1周分の伝搬遅延時間とを基に、当該マスターノード以外の各ノードのうちの特定ノードのオフセット値を算出し、算出したオフセット値を前記特定ノードに設定する遅延測定部と、
自ノードが前記特定ノードである場合、自ノードの第1のタイムスロットの開始タイミングを、前記マスターノードにより設定されたオフセット値分だけずらした第2のタイムスロットを刻む複数タイムスロット管理部と
を備えることを特徴とするノード。
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EP2863589A1 (en) | 2015-04-22 |
JPWO2013187474A1 (ja) | 2016-02-08 |
CN104429023A (zh) | 2015-03-18 |
CN107257263B (zh) | 2019-04-26 |
US20150131991A1 (en) | 2015-05-14 |
US9883262B2 (en) | 2018-01-30 |
EP2863589A4 (en) | 2016-06-01 |
JP5937684B2 (ja) | 2016-06-22 |
CN104429023B (zh) | 2018-04-13 |
EP3264688B1 (en) | 2021-08-18 |
EP3264688A1 (en) | 2018-01-03 |
CN107257263A (zh) | 2017-10-17 |
EP2863589B1 (en) | 2020-03-11 |
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