JP2015133645A - node and scheduler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve use efficiency of a wavelength band allocated route-by-route in a network in which a node constituting the network performs time slot exchange in a bufferless manner without depending on a propagation delay time between nodes.SOLUTION: A node N retains a plurality of sets of TDM timing which are set according to each propagation delay time D1-D4 in each route between the nodes in the network. The node N controls to set the plurality of different sets of TDM timing for accommodating a control target TS in a manner to simultaneously operate on one interface in an optical switch of the node N, to allocate each TS of the plurality of different sets of TDM timing to one wavelength. A scheduler SC instructs to the node to allocate each TS, among the number of route-by-route TS according to a route-by-route traffic amount, to one wavelength at the route-by-route TDM timing in a manner not to mutually overlap.

Description

  The present invention relates to a node and a scheduler constituting a network.

  In conventional networks, such as optical ring networks, WDM (Wavelength Division Multiplexing) and TDM (Time Division Multiplexing) technologies are used to fix each optical wavelength in order to improve traffic accommodation efficiency. Defines a long time slot. The network is also expressed as NW, and the time slot is also expressed as TS. The optical ring NW has a configuration in which transmission paths using optical fibers are connected in a ring shape via a plurality of optical switch nodes (simply referred to as nodes), and the rings are connected in multiple stages via the nodes. An example of this optical ring NW is shown in FIG.

  The optical ring NW10 shown in FIG. 13 is connected to the upper ring R1 connected to the core NW (not shown) via the core node Na (node Na) and to the access NW (not shown) via the access node Nc (node Nc). The lower ring R2 is multi-ring connected in two stages via a ring intersection node Nb (node Nb).

  However, in the optical ring NW10, only one core node Na and one access node Nc are shown for easy understanding, but a plurality of each are actually connected. A plurality of lower rings R2 are also connected via another ring intersection node Nb (not shown). A ring intersection node is also expressed as an intersection node, and a core node, an intersection node, and an access node are also expressed as nodes. Further, the upper ring and the lower ring are also simply expressed as rings.

  In the following description, one-way communication is assumed for the sake of simplification. However, the number of TDM timings set according to the clockwise clockwise wavelength and the propagation delay time between the nodes at each of the nodes Na to Nc It is possible to support two-way communication by holding the rotation. In the optical ring NW10 shown in FIG. 13, it is assumed that counterclockwise (counterclockwise) one-way communication is performed as indicated by arrows Y1, Y2, Y3, and Y4. In this communication, the propagation delay time between the node Na and the node Nb is D1, the propagation delay time between the node Nb and the node Nc is D2, the propagation delay time between the node Nc and the node Nb is D3, and between the node Nb and the node Na. The propagation delay time is D4. Further, as indicated by arrows Y1 and Y2, the traffic direction from the node Na to Nb and from Nb to Nc is the downward direction. As indicated by arrows Y3 and Y4, the traffic direction from the node Nc to Nb and from Nb to Na is the upward direction.

  The TS exchange for enabling bufferless communication is performed at the intersection node Nb of the ring connection point without depending on the propagation delay times D1 to D4 between the nodes. For this reason, a plurality of TDM timings set according to the propagation delay times D1 to D4 of the paths between the nodes Na to Nc are set so that the TS arriving from different paths does not collide with the intersection node Nb. Nc is held, and TS is transmitted and received at each TDM timing. By doing in this way, it becomes possible to exchange the TS without any buffer at the intersection node Nb without depending on the propagation delay times D1 to D4 of the path between the nodes Na to Nc.

  In this optical ring NW10, in order to realize the TS exchange between the upper and lower rings R1 and R2, the ADD (insertion) and DROP (branch) of the data by the optical signal are different in each node Na, Nb and Nc. Controlled by timing.

  Here, in order to simplify the control of TDM timing, it is common to use a fixed-length TS, but the upstream traffic and downstream traffic of each node Na, Nb, Nc are accommodated at different TDM timings. Therefore, another wavelength is assigned for each TDM timing. Here, a wavelength for upstream traffic (also referred to as upstream wavelength) λu and a wavelength for downstream traffic (also referred to as downstream wavelength) λd are set. Then, TSs defined for the respective wavelengths λu and λd are allocated to the nodes Na to Nc according to the traffic amount from the nodes Na to Nc. By periodically changing the TS allocation amount, it is possible to allocate the bandwidth to each node Na to Nc according to the traffic amount between the nodes Na to Nc, and to improve the bandwidth utilization efficiency of the network. Become. Hereinafter, uplink traffic is abbreviated as uplink, and downlink traffic is abbreviated as downlink.

  In this way, by separating the TDM control timings of the ADD TS assigned to the upstream wavelength λu and the DROP TS assigned to the downstream wavelength λd, the TS between the multi-rings is independent of the ring length. It is possible to exchange.

  Next, the timing of TS that periodically operates in each of the nodes Na to Nc of the optical ring NW10 will be described with reference to the timing chart shown in FIG. However, in FIG. 14A, it is assumed that one of the plurality of core nodes Na is set as the master node Na (node Na). As shown on the time axis of the master node Na, the period t obtained by adding the time widths of the five time slots TS1 to TS5 between the time τ1 and the time τ5 is the TS repetitive transmission period (TS transmission period). Thereafter, similarly, as shown between time τ5 and time τ8, a TS transmission cycle t is generated for each of the five time slots TS1 to TS5. The TS transmission cycle t is also indicated by the cycle t in FIGS. 14 (b) to 14 (d).

  In the access node Nc shown in FIG. 14C, the DROP TS serving as the reference TS is shown in FIG. 14C-1 on the upper side, and the ADD TS is shown in FIG. 14C-2 on the lower side. The DROP TS is assigned to the downstream wavelength λd, and the ADD TS is assigned to the upstream wavelength λu.

  First, when synchronizing the start timing of the reference TS in each of the nodes Na to Nc, as shown in FIGS. 14 (a) to (c), the node Nb is moved from the master node Na to the node Nb as indicated by an arrow Y1 at time τ1. On the other hand, a synchronization frame (not shown) for determining the TS start timing is transmitted in the downlink direction. Further, as indicated by the arrow Y2 at time τ2 from the node Nb, a synchronization frame is transmitted in the downstream direction to each node Nc.

  That is, the synchronization frame is received from the master node Na at the node Nb at the time τ2 after the propagation delay time D1, and further received at the node Nc at the time τ3 after the propagation delay time D2. Further, the synchronization frame received by the node Nb is transmitted in the upstream direction through the propagation delay time D4 shown in FIG. 1, and is received by the master node Na. As a result, the master node Na measures the one-round delay time (upper ring one-round delay time Du) of the upper ring R1.

  Furthermore, in order to measure the one-round delay time of the lower ring R2 (lower ring one-round delay time D), the synchronization frame received at the node Nc at the time τ3 is the node Nc as shown by the arrow Y3 in FIG. To the node Nb in the upward direction and received at the node Nb at time τ4 after the propagation delay time D3. The received synchronization frame is transmitted in the upstream direction from the intersection node Nb shown in FIG. 13 via the propagation delay time D4, and is also received by the master node Na.

  By transmitting and receiving this synchronization frame, the propagation delay times D1 to D4 between the nodes Na, Nb, and Nc and the one-cycle delay times Du and D of the upper ring R1 and the lower ring R2 are measured and grasped by the master node Na. The

  Further, the node Na starts the TS operation when the synchronization frame is transmitted, and the other nodes Nb and Nc start the TS operation when the synchronization frame is received. As a result, the start timing of the TS that operates between the nodes Na to Nc is shifted by the propagation delay times D1 to D4 between the nodes Na to Nc. Thereby, the operation timing of the reference TS can be synchronized in each of the nodes Na to Nc.

  Thereafter, when the ADD TS is synchronized in the access node Nc shown in FIG. 14C, at the time τ6 from the intersection node Nb shown in FIG. Then, a synchronization frame (not shown) for determining the ADD TS start timing sent from the master node Na is transmitted.

  This synchronization frame is received by the access node Nc at time τ7 after the propagation delay time D2. Thereby, the start timing of the ADD TS can be set.

Therefore, in order to properly implement TS exchange between the rings, in the access node Nc, as shown in FIG. 14C-2, the start timing of the ADD TS is delayed by a shift amount δ described later from time τ7. It is assumed that time τ9 shifted to.
However, the shift amount δ is obtained by the equation δ = t−D. t is a TS transmission cycle, and D is a lower ring round-trip delay time.

  The ADD TS having the start timing at time τ9 shown in FIG. 14C-2 is received at the intersection node Nb at time τ10 after the propagation delay time D3, as indicated by an arrow Y3. At the intersection node Nb, time τ10 is the start timing of the ADD TS. Further, the ADD TS received at the intersection node Nb at the time τ10 is transmitted to the master node Na as indicated by an arrow Y4 in FIG. 13, and is received at the master node Na at a time after the propagation delay time D4. This reception time is the start timing of the ADD TS in the master node Na.

  Since the start timing of the ADD TS is delayed by the shift amount δ from the start timing of the DROP TS, the TDM control timing between the DROP TS and the ADD TS is properly separated without colliding. Therefore, TS exchange between multi-rings can be performed without depending on the ring length so that TS collision does not occur. As this type of technology, there is a technology described in Non-Patent Document 1.

Yuta Hattori and 4 others, “Examination of multi-ring compatible time slot synchronization method in optical L2 switch network”, NTT Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, Proceedings of the IEICE Conference Volume: 2013, P451, March 05, 2013

  By the way, in the optical ring NW10, different wavelength bands are allocated in accordance with the maximum value of the traffic amount for each route. Then, TS is allocated to each of the nodes Na to Nc according to the traffic amount from each of the nodes Na to Nc with respect to the wavelength allocated for each path. For this reason, it is necessary to estimate the maximum traffic amount for each route in advance and assign a wavelength of a band corresponding to the maximum traffic amount for each route. For example, it is necessary to assign the upstream wavelength λu and the downstream wavelength λd for each path.

  Assuming that the maximum traffic volume for each uplink and downlink is 20 Gbps, it is necessary to fixedly assign two wavelengths λu and λd in a band corresponding to each uplink and downlink to 20 Gbps. However, the traffic volume varies depending on the time zone, and depending on the time zone, there may be a traffic volume as small as 5 Gbps. For this reason, the average traffic volume may be less than the maximum traffic volume.

  Therefore, the conventional optical ring NW10 has a problem that the efficiency of use of the wavelength band is lowered when communication is performed in a wavelength band lower than the wavelength band fixedly assigned to each path.

  The present invention has been made in view of such circumstances, and in a network in which nodes constituting a network exchange time slots in a bufferless manner without depending on the propagation delay time between the nodes, each path is provided. It is an object of the present invention to provide a node and a scheduler that can improve the utilization efficiency of an allocated wavelength band.

  As means for solving the above-mentioned problem, the invention according to claim 1 is a node that holds a plurality of TDM timings set according to a propagation delay time of a route between nodes constituting a network, A plurality of different TDM timings for accommodating time slots are set so as to operate simultaneously on one interface of the optical switch in the node, and a control for assigning a plurality of time slots having different TDM timings on one wavelength is performed. It is a node characterized by comprising control means for performing.

  According to this configuration, a time slot (also referred to as a TS) having different TDM timings is assigned to one wavelength in a node, so that, for example, the total number of upstream and downstream wavelengths (total wavelength band) is set to the conventional maximum traffic of upstream and downstream. The total number of fixed assignments corresponding to the amount can be reduced, and therefore, the wavelength band can be used efficiently.

  According to a second aspect of the present invention, the control means performs control to change the number of the different TDM timings to be operated simultaneously on one interface of the optical switch according to the traffic amount of each path of the number of paths. The node according to claim 1, wherein:

  According to this configuration, the number of different TDM timings to be operated simultaneously on one interface of the optical switch is changed from “10” to “7” or “3” to “7” according to the traffic amount of each path. It can be changed to “6”. That is, it can be changed to an appropriate number according to the traffic volume of the route.

  According to a third aspect of the present invention, there is provided a traffic amount detection unit for detecting a traffic amount for each route from each node constituting a network, and a time slot having a different TDM timing for each route for which the traffic amount is detected by the traffic amount detection unit. And a bandwidth allocation determination unit that generates a node control signal for performing control to allocate to one wavelength at TDM timing for each path so that they do not overlap each other.

  According to this configuration, the scheduler instructs the node to assign TSs having different TDM timings for each wavelength to one wavelength of the optical switch of the node so that they do not overlap with each other, so the wavelength band is efficiently used for the node. Can be made.

  According to a fourth aspect of the present invention, the bandwidth allocation determining unit determines the number of time slots corresponding to the traffic amount for each route detected by the traffic amount detecting unit for each route, and determines the time for each determined route. 4. The scheduler according to claim 3, wherein time slots of the number of slots are allocated on the one wavelength at TDM timing for each path so as not to overlap each other.

  According to this configuration, the scheduler can instruct the node to allocate TS of the number of TSs corresponding to the traffic amount of each path to one wavelength so that they do not overlap each other at different TDM timings for each path. Therefore, the node can efficiently use the wavelength band of one wavelength so that the free band is reduced.

  Advantageous Effects of Invention According to the present invention, in a network in which nodes constituting a network perform time slot exchange without buffering without depending on the propagation delay time between the nodes, the use efficiency of the wavelength band assigned for each path is improved. It is possible to provide a node and a scheduler capable of

It is a figure which shows the optical ring network of a multi-ring structure using the node and scheduler which concern on embodiment of this invention. It is a block diagram which shows the structure of a scheduler. It is a block diagram which shows the structure of a node. It is a figure which shows the time slot of the fixed length prescribed | regulated for every optical wavelength. It is a timing chart for demonstrating the characteristic operation | movement of this embodiment. It is a timing chart for demonstrating the example of a search of TS position by a scheduler. It is a timing chart for demonstrating the operation | movement of the TDM mixed control when TS amount update period T is not set by a node and a scheduler. It is a timing chart for demonstrating the operation | movement of the TDM mixed control at the time of TS amount update period T setting by a node and a scheduler. It is a 1st flowchart for demonstrating operation | movement of a scheduler. It is a 2nd flowchart for demonstrating operation | movement of a scheduler. It is a flowchart for demonstrating operation | movement of a node. It is a figure for demonstrating the effect of this embodiment. It is a block diagram of the conventional optical ring NW. It is a timing chart for demonstrating the synchronous control of the reference | standard TS in the node of the conventional optical ring NW, and the synchronous control of ADD TS.

Embodiments of the present invention will be described below with reference to the drawings.
<Configuration of Embodiment>
FIG. 1 is a diagram illustrating an optical ring network having a multi-ring configuration using nodes and a scheduler according to an embodiment of the present invention. The embodiment of the present invention will be described by taking the optical ring NW as an example. However, the present invention is not limited to this, and any network that transmits and receives information using WDM and TDM may be used.
The optical ring NW20 shown in FIG. 1 includes an upper ring R1 connected to the core NW via a plurality of core nodes Na1 and Na2, and 2 connected to an access NW via a plurality of access nodes Nc1, Nc2, Nc3 and Nc4. The lower rings R2a and R2b have a multi-ring (multiple ring) configuration in which two ring intersection nodes (intersection nodes) Nb1 and Nb2 are connected in two stages. This multi-ring configuration corresponds to the configuration of the optical ring NW 10 of the comparative example shown in FIG. In addition, the optical ring NW20 includes a scheduler SC connected to one core node Na1 (master node Na1) set as a master node among the plurality of core nodes Na1 and Na2. The configuration of the scheduler SC is shown in FIG. 2, and the configuration of the core nodes Na1 and Na2 and the access nodes Nc1 to Nc4 is shown as a node N in FIG.

  The core nodes Na1 and Na2 and the access nodes Nc1 to Nc4 shown in FIG. 1 include an Ether-TS {Ethernet (registered trademark) -time slot} conversion unit indicated by a graphic 22a in a frame 22 and a WDM / TDM switch indicated by a graphic 22b. The intersection nodes Nb1 and Nb2 are provided with a WDM / TDM switch indicated by a graphic 22b. However, the Ethernet-TS conversion unit converts an Ethernet packet and a fixed-length TS to each other.

  The optical ring NW20 is connected to the edge nodes EA and EJ of the external core NW via the core nodes Na1 and Na2 of the upper ring R1, and the external access NW via the access nodes Nc1 to Nc4 of the lower ring R2. It is connected to the.

  Further, it is assumed that the optical ring NW20 performs counterclockwise one-way communication as indicated by arrows Y1, Y2a, Y2b, Y3a, Y3b, and Y4. Further, as shown in FIG. 3, it is assumed that one optical switch unit 31 is mounted on one node N.

  In the optical ring NW 20 having such a configuration, a fixed-length TS is defined for each optical wavelength using WDM and TDM techniques in order to improve traffic accommodation efficiency. For example, as shown in FIG. 4, for each optical wavelength indicated by λ1, λ2, and λ3, a fixed-length time slot having a time width t0 is defined as indicated by TS1 to TS5. Further, a TS transmission cycle t (cycle t) obtained by adding the time widths t0 of TS1 to TS5 is defined, and a TS amount update cycle T (cycle T) is defined by two TS transmission cycles t. This rule is the same as that of the optical ring NW10 described above. FIG. 4 shows, as an example, the data of the edge node EA with “A” in TS1 of the optical wavelength λ1, and the data of the edge node EJ with “J” in TS2 of the optical wavelength λ2.

  Hereinafter, in the description of the optical ring NW20 of the present embodiment, all the rings R1, R2a, R2b and all the nodes Na1, Na2, Nb1, Nb2, Nc1, Nc2, Nc3, Nc4, the upper ring R1 and the lower ring The ring R2a, the core node Na1, the intersection node Nb1, and the access node Nc1 will be described as representatives. Nodes Na1, Nb1, and Nc1 are expressed as nodes Na1... Nc1 and are also expressed as nodes N.

  The feature of this embodiment is that a plurality of nodes N shown in FIG. 3 for accommodating TSs to be controlled in one interface (a wavelength conversion unit described later) of the optical switch unit 31 in accordance with an instruction from the scheduler SC. The different TDM timings are simultaneously operated to allocate a plurality of TSs having different TDM timings on one wavelength. For example, as shown in FIG. 5, TS1, TS5 by TDM timing (TDMu) for uplink traffic different in timing from downlink, TS1, TS2, TS3 by TDM timing (TDMd) for downlink traffic at one wavelength λ1 However, they are mixed and operated so that they do not interfere with each other. A blank slot BS is interposed between TDMu and TDMd so that TDMu and TDMd do not interfere with each other, and one frame of TS1, TSDMd of TS1, TS3 of TDMd and TS5 of TDMu including this blank slot BS is newly added. The TS transmission cycle is tN. Hereinafter, in order to make uplink and downlink easy to understand, TDMu is also expressed as uplink TDMu and TDMd is also expressed as downlink TDMd.

  Further, in the present embodiment, it is assumed that there are different uplink traffic and downlink traffic for TDM timing, but actually, there are as many different TDM timings as there are paths (routes).

  Next, as a feature of the present embodiment, the scheduler SC detects the uplink and downlink traffic amounts of the multi-rings R1 and R2a, and the uplink and downlink TS numbers (each TS amount) based on the detected traffic amounts. To decide. Further, the scheduler SC instructs the node to assign to one wavelength λ1 so that the TS of the determined number of uplink TSs (number of uplink TSs) and the TS of downlink TSs (number of downlink TSs) do not overlap. To N. At this time, when the scheduler SC assigns TS of each number of uplink and downlink TS to one wavelength λ1, the TS of the uplink TS number is assigned by the uplink TDMu, and the TS of the downlink TS number is assigned by the downlink TDMd.

  The detailed configuration of the scheduler SC will be described with reference to FIG. The scheduler SC includes an input / output unit 50, a traffic information holding unit 51, a topology information holding unit 52, a route determination unit 53, a route information holding unit 54, a traffic amount detection unit 55, and a traffic amount management unit 56. A delay information holding unit 57, a TDM system TS determination unit (also referred to as a TS determination unit) 58, a TDM system TS management unit (also referred to as a TS management unit) 59, a bandwidth allocation determination unit 61, a schedule table 62, A node control signal generation unit 63 is provided. The topology information holding unit 52 is connected to an information setting unit 70 outside the scheduler SC.

  The information setting unit 70 is configured so that a network administrator or the like performs an information setting operation via an input unit, information on all the nodes Na1... Nc1 of the optical ring NW20, information on all the rings R1 and R2a, Physical topology information r1 including connection information of the nodes Na1... Nc1 and the rings R1 and R2a is set in the topology information holding unit 52.

  The topology information holding unit 52 holds the topology information r1 set by the information setting unit 70, and the route information of nodes and links that may be passed between the nodes Na1... Nc1 according to the held topology information r1. The r2 is output to the route determination unit 53. The topology information holding unit 52 overwrites and holds the same topology information r1 every time the information setting unit 70 inputs the same topology information r1.

  The input / output unit 50 receives the traffic information including the route between the nodes Na1... Nc1 and the traffic amounts of the uplink and downlink from each node Na1... Nc1, identifies the transmission source and the destination from the traffic information, and receives the traffic information. The traffic information r 3 after filtering the traffic information is output to the traffic information holding unit 51. Further, the input / output unit 50 outputs the one-week delay time of each ring of the multi-rings R1 and R2a and the inter-node delay time to the delay information holding unit 57 as delay information r9. Further, the input / output unit 50 transmits a node control signal r15 (described later) input from the node control signal generation unit 63 to each node Na1... Nc1 every TS amount update period T.

  The traffic information holding unit 51 classifies the input traffic information r3 for each transmission source and destination, stores them in a storage means (not shown), and holds the held traffic information r4 between the nodes Na1... Nc1. And output to the route determination unit 53, the traffic amount detection unit 55, and the band allocation determination unit 61.

  The route determination unit 53 determines a communication route between the nodes Na1... Nc1 (traffic transmission end and reception end) from the inputted traffic information r4 and route information r2, and each of the determined nodes Na1. The communication path information r5 is output to the path information holding unit 54. The communication path information r5 is information including a transit node, a transit link, and a hop number that is the number of nodes through which a packet passes.

  The route information holding unit 54 holds the input communication route information r5, and from the held communication route information r5, the communication route information r6 between the nodes Na1. The data is output to the TS determination unit 58 and the bandwidth allocation determination unit 61. The route information holding unit 54 overwrites and holds the same communication route information r5 each time it is input.

  The traffic amount detection unit 55 performs uplink / downlinks between the nodes Na1... Nc1 for each TS amount update period T based on the input communication path information r6 between the nodes Na1... Nc1 and the traffic information r4. Each traffic volume is detected, and each detected traffic volume information r 7 is output to the traffic volume management unit 56.

  The traffic volume management unit 56 holds the input traffic volume information r 7 while overwriting and outputs the held traffic volume information r 8 to the bandwidth allocation determination unit 61.

  The delay information holding unit 57 holds the inputted delay information r9 while overwriting and outputs the held delay information r10 to the TS determination unit 58.

  The TS determination unit 58 detects the TS position for each of the uplink and downlink TDM timings operating in the optical switch unit 31 (see FIG. 3) of the node N based on the input communication path information r6 and delay information r10. By doing so, the TS position where the TDM timing does not overlap between the uplink and the downlink is searched for in each uplink and downlink.

  An example of TS position search will be described with reference to a timing chart shown in FIG. In FIG. 6, the period T of the downlink TDMd is between the times τ1 to τ3 and between the times τ3 to τ5, and the period t of the uplink TDMu is between the times τ2 to τ4 delayed by the time DE from the start time τ1 of the downlink TDMd. And between time τ4 and τ6. That is, the downlink TDMd operates faster. At this time, the TS determining unit 58 determines that the downlink TS1 on the downlink TDMd side does not overlap with the uplink TS1, TS2, TS3 on the uplink TDMu side, and the downlink TS2 does not overlap with the uplink TS2, TS3, TS4, It is searched that the downlink TS3 does not overlap with the uplink TS3, TS4, TS5, the downlink TS4 does not overlap with the uplink TS4, TS5, TS1, and the downlink TS5 does not overlap with the uplink TS5, TS1, TS2. Similarly, the search is performed on the upstream TDMu side.

  The TS determination unit 58 illustrated in FIG. 2 outputs the TS position information searched as described above to the TS management unit 59 as the TS position information r11.

  The TS management unit 59 holds the input TS position information r11 while overwriting and outputs the held TS position information r12 to the bandwidth allocation determination unit 61.

  The bandwidth allocation determination unit 61 performs the following processing based on the input traffic information r4, communication path information r6 between the nodes Na1... Nc1, traffic amount information r8, and TS position information r12. That is, the bandwidth allocation determination unit 61 determines the number of uplink / downlink TSs based on each uplink / downlink traffic amount indicated in the traffic volume information r8, and allocates each TS number of TSs at each uplink / downlink TDM timing. One wavelength is determined. The wavelength is determined by designating input port numbers i1 to i4 and output port numbers o1 to o4 (see FIG. 3) of the optical switch unit 31 as will be described later.

  Further, the band allocation determination unit 61 allocates TS of each uplink / downlink TS to the determined one wavelength so that the uplink and downlink TDM timings do not overlap with the TS position indicated by the TS position information r12. Search for a free TS position for The band allocation determining unit 61 determines the searched vacant TS position as an allocated TS position for allocating a TS.

  For example, as shown in FIG. 6, the bandwidth allocation determination unit 61 first allocates downlink TS1 and TS4 at the empty TS positions for allocating TS of the number of downlink TSs (for example, “2”) on the downlink TDMd side. Determine with position. Next, the bandwidth allocation determination unit 61 determines, on the upstream TDMu side, an upstream TS1 of an empty TS position that does not overlap with the downstream TS1 and TS4 for allocating TS of the number of upstream TSs (for example, “1”) as the allocated TS position. To do. The bandwidth allocation determination unit 61 outputs the determined content to the schedule table 62 as the bandwidth allocation information r13.

  The schedule table 62 holds the input band allocation information r13 while overwriting and updating the storage unit (not shown), and outputs the held band allocation information r14 to the node control signal generation unit 63.

  The node control signal generation unit 63 obtains a schedule for processing such as data transmission and switch switching of the node N based on the input bandwidth allocation information r14, and performs node control including this schedule content and the bandwidth allocation information r14. The node control signal r15 is generated as a signal r15 and output to the input / output unit 50. The node control signal r15 is generated every TS amount update period T.

  Next, the configuration of the node N will be described with reference to FIG. The node N includes an optical switch unit 31, a control information reception unit 32, a counter management unit 33, an internal clock unit 34, a delay measurement unit 35, a control information transmission unit 36, a TS control unit 37, and a plurality of TSs. A management unit 38, a reference TS synchronization unit 39, a TDM timing switching unit 40, a buffer unit 42, and an ADD / DROP interface unit 43 are provided. The TDM timing switching unit 40 and the TS control unit 37 constitute the control means described in the claims.

  Further, at node N, code a is an offset value, code b is a clock signal, code c is reference time information, code d is current time information, code e is time stamp information from another node, code f is assigned TS information, Symbol g is TS processing scenario information in each TS, symbol h is TS transmission timing information, symbol i is optical switch switching timing information, symbol p is TDM control information, symbol j is buffer storage amount information, symbol k is cycle t and cycle T head start position information, symbol l is TS change information, symbol m is TDM switching timing information, symbol n is head start timing information of a plurality of TSs, and symbol r15 is a node control signal transmitted from the above-described scheduler SC. .

  The optical switch unit 31 performs ADD (insertion) / DROP (branch) on data TS by optical signals, and includes a plurality of input ports i1 to i4 and a plurality of output ports o1 to o4. However, i1 to i4 are also input port numbers, and o1 to o4 are also output port numbers.

  In the following, the operation of a wavelength switch that changes an output port by wavelength conversion will be described as an example of mounting an optical switch (optical switch unit 31).

  Each of the input ports i1 to i4 includes a wavelength converter (not shown) that converts an input wavelength into a wavelength of a predetermined color. The color of the wavelength converted by the wavelength conversion unit corresponds to an individual wavelength number, and each wavelength number corresponds to the output port number o1 to o4. That is, the input port numbers i1 to i4, TDM timings to be described later, and output port numbers o1 to o4 are specified as to what color wavelength the wavelength input from the input ports i1 to i4 is to be converted and output. This is possible. Each TDM timing is a plurality of TDM timings set according to the propagation delay times D1 to D4 of the path between the nodes Na1... Nc1 in the optical ring NW20. In this example, each TDM timing is assumed to be a TDM timing for downlink traffic (abbreviated as downlink TDM) and an TDM timing for uplink traffic (abbreviated as uplink TDM). The wavelength converter corresponds to the optical switch interface described in the claims.

  The control information receiving unit 32 receives a control signal from another node dropped by the optical switch unit 31 and outputs the time stamp information e in the control signal to the delay measuring unit 35 and from the reference node (master node). The reference time information c is output to the counter management unit 33. Further, the control information receiving unit 32 outputs the assigned TS information f in the control signal from another node to the multiple TS management unit 38.

  Further, the control information receiving unit 32 receives a node control signal r15 sent from the scheduler SC dropped by the optical switch unit 31 every TS amount update period T, and uses this node control signal r15 as TS change information l. The data is output to the TDM timing switching unit 40.

  The internal clock unit 34 outputs to the counter management unit 33 a clock signal b for advancing the time counter value existing in the counter management unit 33.

  The counter management unit 33 sets the reference time information c as a time counter value as an initial time counter value, and increments the time counter value according to the clock signal b from the reception time of the synchronization frame. Then, the counter management unit 33 outputs the incremented time counter value as current time information d to the control information reception unit 32, the delay measurement unit 35, the TS control unit 37, the control information transmission unit 36, and the reference TS synchronization unit 39. To do.

  The delay measurement unit 35 measures the propagation delay time between the other node and the own node N from the time stamp information e from the other node and the current time information d, and determines each propagation delay time between the measured nodes. An offset value a that determines the start timing of the TS of the node is obtained, and this offset value a is output to the multiple TS management unit 38.

  The multiple TS management unit 38 shifts the start timing of the reference TS, which is the assigned TS information f of the other node, by the offset value a, and manages the shifted TS. In addition, the multiple TS management unit 38 stores the TS position assigned to each TS from the assigned TS information f of the other node. Then, the multiple TS management unit 38 outputs TS processing scenario information g indicating the TS position of each TS managed in this way to the TS control unit 37, and also starts the start start timing information n of the multiple TSs at the TDM timing. Output to the switching unit 40.

  The reference TS synchronization unit 39 ticks a TS (reference TS) with a constant period from the current time information d generated based on the reference time from the reference node, and performs TS control on the start t position information k of the period t and the period T. To the unit 37.

  The TDM timing switching unit 40 uses the TS change information 1 and the head start timing information n of the plurality of TSs to switch the optical switch unit 31 for uplink traffic (also referred to as uplink) or downlink traffic (also referred to as downlink). TDM switching timing information m instructing switching for operating at timing is generated and output to the TS control unit 37.

  The TS change information l is information based on the node control signal r15 transmitted from the scheduler SC. The node control signal r15 includes band allocation information r14 (= r13) generated by the scheduler SC. This bandwidth allocation information r14 includes instructions for the input port numbers i1 to i4 and output port numbers o1 to o4 of the optical switch unit 31 for determining one wavelength, and each uplink and downlink TS based on each uplink and downlink traffic volume. A number instruction and an instruction to assign TS of each number of uplinks and downlinks to one wavelength to allocation TS positions where TDM timing does not overlap in uplink and downlink. Therefore, the TS change information l gives an instruction corresponding to the instruction of the band allocation information r14.

  The ADD / DROP interface unit 43 exchanges ADD / DROP signals between an external device (not shown) and the node N.

  The buffer unit 42 includes a buffer for accumulating data input to the node N from the external device via the ADD / DROP interface unit 43, and is added from the buffer TX (TX is a transmitter) to the optical switch unit 31. Data is received by the RX (RX is a receiver) and transmitted to the external device via the ADD / DROP interface unit 43.

  The control information transmission unit 36 transmits the data amount accumulated in the buffer of the buffer unit 42 and the time counter value that is the current time information d from the counter management unit 33 to the representative node (for example, master node) as the optical switch unit 31. To send through.

  The TS control unit 37 compares the time counter value, which is the current time information d, with the timing value described in the TS processing scenario information g according to the TS processing scenario information g in each TS from the plurality of TS management units 38, and Switch switching timing information i and TS transmission timing information h are obtained. Further, the TS control unit 37 outputs the optical switch switching timing information i to the optical switch unit 31 and outputs TS transmission timing information h to the buffer unit 42 to control TS transmission and TS switch operation.

  Also, the TS control unit 37 outputs a TDM control signal p to the optical switch unit 31 and the buffer unit 42 based on the TDM switching timing information m input from the TDM timing switching unit 40. Since the TDM control signal p is based on the TDM switching timing information m, the TDM control signal p includes contents based on the band allocation information r14.

  That is, the TS control unit 37 designates the input port numbers i1 to i4 and the output port numbers o1 to o4 of the optical switch unit 31 in order to determine one wavelength by the TDM control signal p, and sets one wavelength determined by this designation. Then, TDM mixed control is performed in which TS of each number of uplink and downlink TSs based on each uplink and downlink traffic volume is allocated to an allocated TS position designated so that the TDM timing does not overlap between uplink and downlink.

  During this TDM mixed control, the TX of the buffer unit 42 connected to the input port (i3 in FIG. 3) of the optical switch unit 31 has the same TDM timing (uplink TDMu or downlink TDMd) as the wavelength conversion unit of the input port i3. Need to work. Therefore, the TS control unit 37 outputs the same TDM control signal p output to the optical switch unit 31 to the buffer unit 42, and the TX of the buffer unit 42 has the same TDM timing (upstream TDmu) as the wavelength conversion unit of the input port i3. Alternatively, control is performed so as to operate in downlink TDMd).

  A specific example of performing TDM mixed control when the TS amount update period T is not set will be described with reference to the timing chart shown in FIG. As shown in FIG. 7, the downlink TDMd TS transmission period t is a period between time τ11 to τ14 with five TS1 to TS5 as one frame and between time τ14 to τ17. The period t of the upstream TDMu is delayed from the period t of the downstream TDMd by the time DE between times τ11 to τ12, and is a period between times τ12 to τ15 and between times τ15 to τ18.

  At this time, as shown in FIGS. 7A and 7B, the scheduler SC designates the downlink TS1 having the time width t0 from the time τ11 and the downlink TS4 having the time width t0 from the time τ13 on the downlink TDMd side. The Furthermore, on the upstream TDMu side, it is assumed that the upstream TS1 having the time width t0 is designated from the time τ12 so as not to overlap the downstream TS1 and TS4. However, it is assumed that the downlink TS1, TS4 and the uplink TS1 are vacant TSs.

  Specifically, the scheduler SC designates one input port number (for example, i3) for determining one wavelength, and a downlink TS1 by downlink TDMd is assigned to this one wavelength, and then an uplink TS1 by uplink TDMu. Next, it is specified that the downlink TS4 by the downlink TDMd is allocated. Furthermore, the output port number o1 for outputting the assigned downlink TS1 is specified between the time τ11 and the time width t0, and the output port number o2 for outputting the uplink TS1 is the time width t0 from the time τ12. The output port number o4 for outputting the downlink TS4 is specified between the time τ13 and the time width t0.

  The optical switch unit 31 is subjected to TDM mixed control by a TDM control signal p including such designated contents. By this control, as shown in FIG. 7C, the optical switch unit 31 assigns data to TS1 of TDMd that is the downstream TDM timing to one wavelength specified by one input port i3, and then the upstream TDM Data is allocated to TS1 of TDMu which is the timing, and then data is allocated to TS4 of downstream TDMd. In this way, downlink TS1, uplink TS1, and downlink TS4 with different TDM timings are allocated to one wavelength in a mixed manner so that blank slots BS are interposed between them so as not to interfere with each other.

  However, between the time τ11 to τ14 and the time τ14 to τ17 due to the allocation of the downlink TS1, the uplink TS1, and the downlink TS4, respectively, is a new TS transmission cycle tN, and a cycle obtained by combining the two cycles tN is a new TS amount. The update cycle TN. In this example, the new TS transmission cycle tN and the previous cycle t have the same time width. However, if the number of uplink / downlink TS allocations exceeds a predetermined value, the number of blank slots BS also increases, so that a new TS transmission cycle tN becomes longer than the previous cycle t.

  Next, a specific example of TDM mixed control when the TS amount update period T is set will be described with reference to the timing chart shown in FIG. As shown in FIG. 8, the TS amount update period T of the downlink TDMd is a period between times t11 to τ17 corresponding to two periods of time τ11 to τ14 and time τ14 to τ17. The period T of the upstream TDMu is delayed from the period T of the downstream TDMd by the time DE between the times τ11 to τ12, and the time t12 to two periods of the time τ12 to τ15 and the time τ15 to τ18. The period between τ18.

  The example shown in FIG. 8 is different from the example of FIG. 7 in that a TS amount update period T is set. In the example shown in FIG. 8, as described with reference to FIG. 7 above, one input port number (for example, i3) for determining one wavelength is designated by the scheduler SC, and it is downloaded to this one wavelength. It is specified that downlink TS1 by TDMd is allocated, then uplink TS1 by uplink TDMu, and then downlink TS4 by downlink TDMd are allocated. Furthermore, the output port number o1 for outputting the assigned downlink TS1 is specified between the time τ11 and the time width t0, and the output port number o2 for outputting the uplink TS1 is the time width t0 from the time τ12. The output port number o4 for outputting the downlink TS4 is specified between the time τ13 and the time width t0.

  The optical switch unit 31 is subjected to TDM mixed control by a TDM control signal p including such designated contents. By this control, as shown in FIG. 8C, the optical switch unit 31 assigns data to TS1 of TDMd that is the downstream TDM timing to one wavelength specified by one input port i3, and then the upstream TDM Data is allocated to TS1 of TDMu which is the timing, and then data is allocated to TS4 of downstream TDMd. In this way, downlink TS1, uplink TS1, and downlink TS4 with different TDM timings are allocated to one wavelength in a mixed manner so that blank slots BS are interposed between them so as not to interfere with each other.

  However, between the time τ11 to τ14 and the time τ14 to τ17 due to the allocation of the downlink TS1, the uplink TS1, and the downlink TS4, respectively, is a new TS transmission cycle tN, and a cycle obtained by combining the two cycles tN is a new TS amount. The update cycle TN. In this example, the new TS transmission cycle tN and the previous cycle t have the same time width, and the new TS amount update cycle TN and the previous cycle T have the same time width. However, if the number of uplink / downlink TS allocations exceeds a predetermined value, the number of blank slots BS also increases, so that the new TS transmission periods tN and TN become longer than the previous periods t and T.

  The above description is based on the assumption that one optical switch unit 31 is mounted on one node N. However, when a plurality of optical switch units 31 are mounted on one node, The same control as described above may be performed for one optical switch unit 31.

  In the above description, it is assumed that a plurality of different TDM timings for accommodating the TS to be controlled are for upstream and downstream traffic. However, when there are as many different TDM timings as there are paths (routes), these different TDM timings are simultaneously operated by one input port (wavelength conversion unit) (for example, i1) as one interface of the optical switch unit 31. Thus, control for assigning a plurality of TSs having different TDM timings on one wavelength may be performed. This control is performed by the TDM control signal p output from the TS control unit 37 to the optical switch unit 31 based on the TDM switching timing information m from the TDM timing switching unit 40.

  Further, the TS control unit 37 performs control to change the number of different TDM timings to be simultaneously operated at one input port i1 of the optical switch unit 31 according to the traffic amount of each path of the optical ring NW20. For example, it is assumed that the number of paths is 10, and the maximum number of different TDM timings that are simultaneously operated on one input port i1 is “10”. In this case, when there is traffic on all routes, the number of TDM timings that are operated simultaneously on one input port i1 is “10”. Thereafter, if there is no traffic on the four routes, the number of TDM timings may be set to “6” under the control of the TS control unit 37 because the route having traffic is six. That is, it is possible to change the number of different TDM timings operated simultaneously on one input port i1 in accordance with the number of routes having traffic.

<Operation of Embodiment>
Next, the operation by the TDM mixed control (TDM mixed operation) of the optical switch unit 31 of the nodes Na1... Nc1 constituting the optical ring NW20 of this embodiment will be described with reference to the flowcharts shown in FIGS. 9 and 10 are flowcharts for explaining the bandwidth allocation determining operation of the scheduler SC for causing the optical switch unit 31 to perform the TDM mixed operation, and FIG. 11 is a TDM mixed control of the optical switch unit 31 of the access node Nc1. It is a flowchart explaining the operation | movement by.

  First, the bandwidth allocation determination operation of the scheduler SC will be described with reference to FIG. 9 and FIG. However, in the scheduler SC shown in FIG. 2, the topology information holding unit 52 stores information on all the nodes Na1... Nc1 of the optical ring NW20 shown in FIG. Information and physical topology information r1 including connection information of the nodes Na1... Nc1 and the rings R1 and R2a are set and held. It is assumed that the topology information holding unit 52 outputs the route information r2 of nodes and links that may be passed between the nodes Na1... Nc1 according to the topology information r1 to be held.

  In step S1 shown in FIG. 9, the input / output unit 50 receives traffic information including the path between the nodes Na1... Nc1 and the traffic amounts of uplink and downlink from the nodes Na1. Then, the destination information is identified, and the traffic information r3 after filtering the received traffic information is output to the traffic information holding unit 51. Further, the input / output unit 50 outputs the one-week delay time and inter-node delay time of each of the multi-rings R1 and R2a to the delay information holding unit 57 as delay information r9.

  In step S2, the traffic information holding unit 51 classifies and holds the input traffic information r3 for each transmission source and destination, and the route information determining unit 53 stores the traffic information r4 between the nodes Na1. And output to the traffic amount detection unit 55 and the band allocation determination unit 61.

  In step S3, the route determination unit 53 determines the communication route between the nodes Na1... Nc1 from the input traffic information r4 and the route information r2, and the communication route information between the determined nodes Na1. r5 is output to the route information holding unit 54.

  In step S4, the route information holding unit 54 holds the input communication route information r5, and from the held communication route information r5, the communication route information r6 between the nodes Na1. The data is output to the detection unit 55, the TS determination unit 58, and the bandwidth allocation determination unit 61.

  In step S5, the traffic amount detection unit 55 determines between the nodes Na1... Nc1 for each TS amount update period T based on the input communication path information r6 between the nodes Na1... Nc1 and the traffic information r4. The amount of traffic in each of the upstream and downstream traffic is detected. In this case, the ratio of the upstream and downstream traffic amounts is, for example, “1: 2”. Hereinafter, this is referred to as each traffic amount (“1: 2”). The traffic amount detection unit 55 outputs the traffic amount information r7 including the detected uplink and downlink traffic amounts to the traffic amount management unit 56.

  In step S 6, the traffic volume management unit 56 holds the input traffic volume information r 7 while overwriting it, and outputs the held traffic volume information r 8 to the band allocation determination unit 61.

  In step S 7, the delay information holding unit 57 holds the inputted delay information r 9 while overwriting and outputs the held delay information r 10 to the TS determination unit 58.

  In step S8, the TS determination unit 58, for each uplink and downlink TDM timing that operates in the optical switch unit 31 (see FIG. 3) of the node N, based on the input communication path information r6 and delay information r10. The TS position where the TDM timing does not overlap between the upstream and downstream is searched for in each upstream and downstream. For example, as shown in FIG. 6, the downlink TS1 on the downlink TDMd side does not overlap the uplink TS1, TS2, TS3 on the uplink TDMu side, the downlink TS2 is the uplink TS2, TS3, TS4, and the downlink TS3 is the uplink TS3, TS4. , TS5, downstream TS4 and upstream TS4, TS5, TS1, and downstream TS5 does not overlap upstream TS5, TS1, TS2. Similarly, the TS determination unit 58 searches on the upstream TDMu side, and outputs TS position information r11 including the search contents to the TS management unit 59.

  In step S <b> 9, the TS management unit 59 holds the input TS position information r <b> 11 while being overwritten and updates, and outputs the held TS position information r <b> 12 to the band allocation determination unit 61.

  Next, in step S10 shown in FIG. 10, the bandwidth allocation determining unit 61 determines the node Na1... Based on the input traffic information r4, the communication route information r6 between the nodes Na1... Nc1, and the traffic amount information r8. Each traffic amount (“1: 2”) in the upstream and downstream traffic on the communication path between Nc1 is recognized. The bandwidth allocation determination unit 61 determines the number of uplink TSs as “1” and the number of downlink TSs as “2” based on each uplink and downlink traffic volume (“1: 2”). Further, the band allocation determining unit 61 assigns one wavelength to which TSs having the numbers of upstream and downstream TSs “1” and “2” are allocated in a mixed manner to the input port numbers i1 to i4 and the output port number o1 of the optical switch unit 31. Specify ~ o4.

  Next, the band allocation determination unit 61 allocates the TSs having the numbers of uplinks and downlinks “1” and “2” to the determined one wavelength so that the uplink and downlink TDM timings do not overlap. The TS position is determined based on the TS position information r12.

  For this purpose, the band allocation determining unit 61 first determines in step S11 whether or not there is a free TS in each TS on the uplink TDMu side and the downlink TDMd side. For example, as shown in FIG. 6, in order to allocate a TS having a downlink TS number “2” on the downlink TDMd side, it is first determined whether or not the downlink TS1 is an empty TS.

  As a result, if the downstream TS1 is not an empty TS, the process proceeds to step S12. On the other hand, if the downlink TS1 is an empty TS, the process proceeds to step S13, and the bandwidth allocation determination unit 61 determines the downlink TS1 as an allocation TS1 for allocating the first TS of the TS number “2”. .

  After this determination, in step S14, the bandwidth allocation determination unit 61 determines whether or not the allocated TS positions of the TSs for all the uplink and downlink numbers determined in step S10 have been determined. As a result, if the allocated TS positions for all the TS numbers have not been determined, the process proceeds to step S12.

  In step S12, the bandwidth allocation determination unit 61 searches for the next TS2 (downstream TS2 in FIG. 6) where the upstream and downstream TDM timings do not overlap. Next, returning to step S11, it is determined whether or not the searched downlink TS2 is an empty TS. As a result, if the downlink TS2 is not an empty TS, the process proceeds to step S12 to search for the next TS3 (downlink TS3 in FIG. 6). It is assumed that this downstream TS3 is also searched for not being a free TS in step S11, and the next downstream TS4 searched for in step S12 (downstream TS4 in FIG. 6) is searched for a free TS in step S11.

  In this case, in step S13, the bandwidth allocation determination unit 61 determines the downlink TS4 as the allocation TS2 of the second TS of the TS number “2”. After this determination, in step S14, the bandwidth allocation determination unit 61 determines whether or not the allocated TS positions for the number of TSs for all uplinks and downlinks have been determined. As a result, it is assumed that the allocation TS1 and TS4 for all the TS numbers “2” in the downlink are determined, but it is determined that the allocation is not yet determined on the uplink side. That is, the allocated TS positions for all TS numbers are not determined.

  In this case, in step S12, the band allocation determining unit 61 searches for an upstream TDMu-side TS1 (upstream TS1 in FIG. 6) where the upstream and downstream TDM timings do not overlap. Next, returning to step S11, it is determined whether or not the searched uplink TS1 is an empty TS. As a result, if the uplink TS1 is an empty TS, the bandwidth allocation determination unit 61 determines the uplink TS1 as the uplink allocation TS1 for allocating the TS having the uplink TS number “1” in step S13.

  After this determination, when the bandwidth allocation determining unit 61 determines in step S14 that the allocated TS positions for all the uplink and downlink TS numbers have been determined, the process proceeds to step S15. In step S15, the bandwidth allocation determining unit 61 outputs the determined content to the schedule table 62 as the bandwidth allocation information r13.

  In step S <b> 16, the schedule table 62 holds the input band allocation information r <b> 13 and outputs the held band allocation information r <b> 14 to the node control signal generation unit 63.

  In step S17, the node control signal generation unit 63 obtains a schedule for performing processing such as data transmission and switch switching of the corresponding node based on the input band allocation information r14, and includes the schedule content and the band allocation information r14. Is generated as a node control signal r15, and the node control signal r15 is output to the input / output unit 50.

  In step S18, the input / output unit 50 transmits the node control signal r15 to the corresponding access node Nc1, for example, every TS update period T.

  Next, the operation by the TDM mixed control of the optical switch unit 31 of the access node Nc1 will be described with reference to FIG. However, the configuration of the access node Nc1 refers to the node N shown in FIG.

  In step S <b> 21, the control information receiving unit 32 of the node Nc <b> 1 receives a control signal from another node dropped by the optical switch unit 31, and outputs the assigned TS information f in the control signal to the multiple TS management unit 38. Further, the control information receiving unit 32 receives a node control signal r15 sent from the scheduler SC dropped by the optical switch unit 31 every TS amount update period T, and uses this node control signal r15 as TS change information l. The data is output to the TDM timing switching unit 40.

  In step S22, the TDM timing switching unit 40 performs TDM timing switching for the optical switch unit 31 to operate at the TDM timing for uplink or downlink from the TS change information l and the head start timing information n of the plurality of TSs. The instructed TDM switching timing information m is generated and output to the TS control unit 37.

  Here, since the TDM switching timing information m is based on the TS change information l corresponding to the band allocation information r14 described above, the input port numbers i1 to i4 and the output port of the optical switch unit 31 for determining one wavelength. Instructions for numbers o1 to o4, instructions for each number of uplink / downlink TSs based on each uplink / downlink traffic amount, TS for each number of uplink / downlinks for one wavelength, and TDM timing do not overlap in uplink and downlink This is a signal for giving an instruction to assign to the assigned TS position.

  In step S23, the TS control unit 37 compares the time counter value as the current time information d with the timing value described in the TS processing scenario information g according to the TS processing scenario information g in each TS, and switches the optical switch switching timing. Information i and TS transmission timing information h are obtained. The TS control unit 37 outputs the optical switch switching timing information i to the optical switch unit 31 and outputs the TS transmission timing information h to the buffer unit 42 to control TS transmission and TS switch operation.

  In step S <b> 24, the TS control unit 37 outputs the TDM control signal p to the optical switch unit 31 and the buffer unit 42 based on the TDM switching timing information m input from the TDM timing switching unit 40.

  In step S25, the TS control unit 37 designates the input port numbers i1 to i4 and the output port numbers o1 to o4 of the optical switch unit 31 in order to determine one wavelength by the TDM control signal p. Furthermore, the TS control unit 37 assigns TS of each number of uplinks and downlinks based on the uplink and downlink traffic amounts to one wavelength determined by the designation, so that the TDM timing is designated so that the uplink and downlink do not overlap with each other. TDM mixed control assigned to the assigned TS position, which is the position, is performed.

  A specific example of this TDM mixed control will be described with reference to FIG. As shown in FIGS. 8 (a) and 8 (b), on the downlink TDMd side, a downlink TS1 having a time width t0 from time τ11 and a downlink TS4 having a time width t0 from time τ13 are assigned on the downlink TDMd side by the scheduler SC. It is specified. Further, on the upstream TDMu side, the upstream TS1 having the time width t0 from the time τ12 is designated as the allocated TS position so as not to overlap the downstream TS1 and TS4.

  That is, the scheduler SC designates the input port number i3 for determining one wavelength, the downlink TS1 and TS4 are assigned to this one wavelength, and the uplink TS1 is assigned. Further, the scheduler SC designates the output port number o1 for outputting the assigned downlink TS1 between the time τ11 and the time width t0, and the output port number o2 for outputting the uplink TS1 is the time from the time τ12. The output port number o4 for outputting the downlink TS4 is specified between the time t0 and the time width t0. The optical switch unit 31 is subjected to TDM mixed control by the TDM control signal p including such designated contents.

  At the time of this TDM mixed control, in step S26, the TS control unit 37 outputs the same TDM control signal p output to the optical switch unit 31 to the buffer unit 42, and the TX of the buffer unit 42 is the wavelength conversion unit of the input port i3. And control so as to operate at the same TDM timing (uplink TDMu or downlink TDMd). With this control, TX operates at the same TDM timing as the wavelength conversion unit of the input port i3.

  Accordingly, in step S27, the optical switch unit 31 assigns downlink TS and uplink TS with different TDM timings to one wavelength in accordance with TDM mixed control so that they do not interfere with each other, and transmits them from a corresponding output port to a predetermined node. To do. For example, as shown in FIG. 8C, the optical switch unit 31 assigns the downlink TS1 at the downlink TDM timing to one wavelength specified by the input port i3 in accordance with the TDM mixed control, and then the uplink TDM. An uplink TS1 of timing is allocated, and then a downlink TS4 of downlink TDM timing is allocated, and these are transmitted from the corresponding output ports o1, o2, o4 to a predetermined node.

<Effect of embodiment>
As described above, the node N of the present embodiment constitutes the optical ring NW20 as a network using WDM and TDM, and a plurality of nodes set according to the propagation delay times D1 to D4 of the paths between the nodes in the network. It is assumed that the TDM timing is maintained. As a feature of the present embodiment, the node N is configured to change a plurality of different TDM timings for accommodating a TS to be controlled by the TDM timing switching unit 40 and the TS control unit 37 as control means, and to switch the optical switch in the node N. The input port (for example, i1) as one interface of the unit 31 is set to operate simultaneously, and is configured to perform control to allocate a plurality of TSs having different TDM timings on one wavelength.

  The scheduler SC that controls the node N according to the present embodiment includes a traffic amount detection unit 55 and a band allocation determination unit 61. The traffic amount detection unit 55 detects the traffic amount for each route from the node N. The band allocation determination unit 61 allocates TSs having different TDM timings for each path for which the traffic volume is detected by the traffic volume detection unit 55 to one wavelength at the TDM timing for each corresponding path so as not to overlap each other. A node control signal r15 for performing control is generated. Further, the bandwidth allocation determining unit 61 determines the number of TSs corresponding to the traffic amount for each route detected by the traffic amount detecting unit 55 for each route, and the TS of the determined TS number for each route is mutually determined. In order not to overlap, it is allocated on one wavelength at the TDM timing for each corresponding path.

  It should be noted that since there is no traffic on a route where the traffic amount is not detected by the traffic amount detection unit 55, there is no need to allocate a TS.

  According to these nodes N and scheduler SC, the following effects can be obtained. However, each route is assumed to be the upstream and downstream routes of the multi-rings R1 and R2a shown in FIG. Conventionally, the number of wavelengths must be fixedly assigned to each of the upstream and downstream rings in the rings R1 and R2a. For this reason, it is necessary to assign the number of wavelengths (wavelength band) corresponding to the maximum traffic amount to each uplink and downlink, and the number of wavelengths (total number of wavelengths) corresponding to the total value of each maximum traffic amount is required. Therefore, when the amount of uplink and downlink traffic is small, the wavelength band cannot be used efficiently.

  However, in the present embodiment, the scheduler SC instructs the number of TSs corresponding to the uplink and downlink traffic amounts to one wavelength so as not to overlap each other at different uplink and downlink TDM timings. In response to the instruction, the node N assigns each uplink and downlink TS to one wavelength, so that the wavelength band of one wavelength can be efficiently used so that the free band is reduced. For this reason, it is not necessary to assign a wavelength band corresponding to the maximum traffic amount for each uplink and downlink as in the prior art. Therefore, since it is only necessary to assign a wavelength band having a traffic volume lower than the maximum traffic volume to each uplink and downlink, the total number of uplink and downlink wavelengths is reduced. Further, since the node N assigns each uplink / downstream TS to one wavelength by controlling one interface of the optical switch unit 31 by the control means, the node depends on the propagation delay time between the nodes. TS exchange can be performed without buffering.

  For example, as shown in the simulation result shown in FIG. 12, conventionally, the number of wavelengths (wavelength band) of about “25”, which is the sum of the uplink and downlink indicated by the line 101, is necessary. However, in this embodiment, as shown by the line 102, by assigning the uplink / downlink TS to one wavelength, there is an effect that the total number of wavelengths of “14-15” is sufficient.

  Further, the TS control unit 37 performs control to change the number of different TDM timings to be simultaneously operated at one input port i1 of the optical switch unit 31 according to the traffic amount of each path of the optical ring NW20.

  For example, it is assumed that the number of paths is 10, and the maximum number of different TDM timings that are simultaneously operated on one input port i1 is “10”. In this case, when there is traffic on all routes, the number of TDM timings that are operated simultaneously on one input port i1 is “10”. After that, if there is no traffic on the two routes, the number of routes having traffic is 8, and the number of TDM timings may be set to “8” under the control of the TS control unit 37. In this way, the number of different TDM timings that are operated simultaneously on one input port i1 can be changed in correspondence with the number of routes with traffic. Therefore, waste of the wavelength band can be eliminated.

10,20 Optical ring NW
N node (core node, access node)
Na1, Na2 core node (master node)
Nb1, Nb2 Ring intersection node (intersection node)
Nc1, Nc2, Nc3, Nc4 Access node R1 Upper ring R2a, R2b Lower ring SC scheduler

Claims (4)

A node holding a plurality of TDM timings set according to a propagation delay time of a path between nodes constituting the network,
A plurality of different TDM timings for accommodating time slots to be controlled are set to operate simultaneously on one interface of the optical switch in the node, and a plurality of time slots having different TDM timings are set on one wavelength. A node characterized by comprising control means for performing allocation control. 2. The control unit according to claim 1, wherein the control unit performs control to change the number of the different TDM timings to be simultaneously operated on one interface of the optical switch in accordance with a traffic amount of each route of the number of routes. The listed node. A traffic amount detection unit for detecting the traffic amount for each route from each node constituting the network;
Node control for performing control to allocate time slots having different TDM timings for each path in which the traffic volume is detected by the traffic volume detection unit to one wavelength at TDM timing for each path so as not to overlap each other. A scheduler comprising: a band allocation determination unit that generates a signal. The bandwidth allocation determination unit determines the number of time slots corresponding to the traffic amount for each route detected by the traffic amount detection unit for each route, and sets the time slots corresponding to the determined time slots for each route. 4. The scheduler according to claim 3, wherein allocation is performed on the one wavelength at a TDM timing for each path so as not to overlap each other.

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