JP6069229B2 - node - Google Patents

Description

The present invention relates to a node constituting the 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. 16 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. 16, 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. 17A, 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. This TS transmission cycle t is also indicated by the cycle t in FIGS. 17B to 17D.

  In the access node Nc shown in FIG. 17C, the DROP TS serving as the reference TS is shown in FIG. 17C-1 on the upper side, and the ADD TS is shown in FIG. 17C-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. 17A to 17C, 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. 16 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. 17 (c), at the time τ6 from the intersection node Nb shown in FIG. 17 (b), as shown by the arrow Y2, the access node Nc 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. 17 (c-2), the start timing of the ADD TS is delayed from the time τ7 by a shift amount δ described later. 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 whose start timing is time τ9 shown in FIG. 17 (c-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 time τ10 is transmitted to the master node Na as indicated by an arrow Y4 in FIG. 16, 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. and to provide a node which can improve the utilization efficiency of the 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, In accordance with the TDM timing of the path to which the time slot is assigned, the switching means switches the TDM timing operating at each interface of the optical switch in the node, and the switching means has the same number of TDMs as the number of paths in the network. The node has a timing and switches the TDM timing .

According to this configuration, the node switches the TDM timing that operates at each interface of the optical switch in the node in accordance with the TDM timing of the path to which the time slot to be controlled (hereinafter also referred to as TS) is allocated. The required number of wavelengths can be allocated by switching the TDM timing in accordance with the change in the traffic amount. In addition, it is possible to switch from the TDM timing of the currently operating route to the TDM timing of a route different from this.

The invention according to claim 2 is a node that holds a plurality of TDM timings set in accordance with a propagation delay time of a path between nodes constituting the network, and is adapted to a TDM timing of a path to which a time slot to be controlled is assigned. In addition, switching means for switching TDM timings operating at each interface of the optical switch in the node is provided, and the switching means has a number of band change timings equal to the number of paths in the network, and the TDM timing is after switching a node you and switches the band change timing.

According to this configuration, the node switches the TDM timing that operates at each interface of the optical switch in the node in accordance with the TDM timing of the path to which the time slot to be controlled (hereinafter also referred to as TS) is allocated. The required number of wavelengths can be allocated by switching the TDM timing in accordance with the change in the traffic amount. In addition, since the band change timing is also switched after switching the TDM timing operating at each interface of the optical switch unit in the node, the TS position of the switching destination TDM timing can be received at the transmission destination node. Can be adjusted to the position.

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. an object of the present invention is to provide a node that can.

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 figure which shows the time slot of the fixed length prescribed | regulated for every optical wavelength. It is a block diagram which shows the structure of a scheduler. It is a figure which shows a ring structure in case five nodes are connected. It is explanatory drawing of the first fit base method. It is explanatory drawing of the sorting base method. It is a block diagram which shows the structure of a node. 6 is a timing chart of a first example when switching from downlink TDM to uplink TDM. It is a timing chart of the 2nd example in the case of switching from downlink TDM to uplink TDM. It is a timing chart of the 1st example in the case of switching from uplink TDM to downlink TDM. It is a timing chart of the 2nd example in the case of switching from uplink TDM to downlink TDM. 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 a node and a scheduler. 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 core nodes Na1 and Na2 and the access nodes Nc1 to Nc4 include an Ether-TS {Ethernet (registered trademark) -time slot} conversion unit indicated by a graphic 22a in the frame 22 of FIG. 1, a WDM / TDM switch indicated by a graphic 22b, and 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.

  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. 2, 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. 2 shows, as an example, the data of the edge node EA by “A” for TS1 of the optical wavelength λ1, and the data of the edge node EJ by “J” for 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 (node Na1), the intersection node Nb1 (node Nb1), and the access node Nc1 (node Nc1) will be described as representatives. Nodes Na1, Nb1, and Nc1 are expressed as nodes Na1... Nc1.

  The feature of the optical ring NW 20 of the present embodiment is that the scheduler SC first detects the upstream and downstream traffic amounts of the multi-rings R1 and R2a, and the upstream and downstream wavelengths according to the ratio of the detected traffic amounts. The number (each wavelength band) is determined, and it is determined to assign the wavelength of each wavelength number to the rings R1 and R2a as the upstream wavelength λu and the downstream wavelength λd. Furthermore, the scheduler SC determines each uplink / downlink TS amount (number of TSs) based on each detected traffic amount, assigns this uplink TS amount to an empty TS position of the uplink wavelength λu, and determines the downlink TS amount. Is assigned to a free TS position of the downstream wavelength λd. Next, each node Na1... Nc1 determines the uplink or downlink TDM timing that operates at the interface of the optical switch (a wavelength converter described later) and the above-mentioned allocated TS amount according to the instruction of the scheduler SC, and the TS amount update period. This is because the period is changed periodically at T.

  More specifically, for example, when the downstream traffic volume is “1” and the upstream traffic volume is “3” as the wavelength band corresponding to each upstream and downstream traffic volume, the wavelength band corresponding to each traffic volume. Λu and λd are assigned. Thereafter, it is assumed that the downstream traffic amount is “3” and the upstream traffic amount is changed to “1”. In this case, the scheduler SC allocates wavelengths from “3” band for current upstream traffic to “2” bands for downstream traffic, sets the wavelength band for downstream traffic to “3”, and sets the wavelength band for upstream traffic. Is set to “1”, for example, to the node Nc1. In accordance with the instruction, the node Nc1 assigns the wavelength for the “2” band in the “3” band for the current upstream traffic to the downstream, thereby setting the wavelength band for the downstream traffic to “3”, and for the upstream traffic. An operation for setting the wavelength band to “1” is performed.

  The 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 TDM system determination unit 55, and a TDM system management unit 56. , A band allocation determining unit 57, a schedule table 58, and a node control signal generating unit 59. An information setting unit 60 outside the scheduler SC is connected to the topology information holding unit 52.

  The information setting unit 60 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, 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 60, 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 60 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 transmits a node control signal r11 (described later) input from the node control signal generation unit 59 to each of the nodes 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 TDM system determination unit 55, and the bandwidth allocation determination unit 57.

  The route determination unit 53 determines a communication route (path) between the nodes Na1... Nc1 (traffic transmission end and reception end) from the input traffic information r4 and route information r2, and each determined node The communication route information r5 between Na1... Nc1 is output to the route 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 bandwidth allocation determination unit 57. The route information holding unit 54 overwrites and holds the same communication route information r5 each time it is input.

  The TDM system determining unit 55 determines whether the uplink / downlink between the nodes Na1... Nc1 is performed at each TS amount update period T based on the communication path information r6 between the nodes Na1... Nc1 and the traffic information r4. TDM timing that detects each traffic volume, determines the number of upstream and downstream wavelengths according to the ratio of each detected traffic volume, and operates at each upstream and downstream interface of the optical switch in each node Na1. To decide. To explain this further, the total number of uplink and downlink wavelengths in the ring is set in advance as “10”, for example, and the total number of wavelengths “10” is set to the ratio of each traffic amount of uplink and downlink “for example, 7: In response to “3”, the number of upstream wavelengths is determined as “7”, and the number of downstream wavelengths is determined as “3”. This determination is made every TS amount update cycle T. The TDM system determining unit 55 outputs the wavelength number information r7 determined as described above to the TDM system managing unit 56.

  The total number of wavelengths (total wavelength band) is the number of wavelengths corresponding to a traffic amount lower than 40 Gbps when the maximum traffic amount for each uplink and downlink is 20 Gbps and the total is 40 Gbps, for example.

  For example, at time τ1, the uplink traffic volume is 20 Gbps (maximum traffic volume) and the downlink traffic volume is 10 Gbps, and at time τ2, the uplink traffic volume is 10 Gbps and the downlink traffic volume is 20 Gbps (maximum traffic volume). Assume a changing case. In this case, conventionally, since the number of wavelengths had to be fixedly assigned to the ring, it was necessary to assign the number of wavelengths corresponding to the maximum traffic amount of 20 Gbps to each of the upstream and downstream, and the total number of wavelengths was 40 Gbps. A corresponding number of wavelengths was required.

  However, in the present invention, the number of upstream and downstream wavelengths is set by exchanging with each other according to the amount of upstream and downstream traffic, so if the total number of wavelengths is set to the number of wavelengths corresponding to 30 Gbps, Thus, it is possible to accommodate the amount of traffic in both upstream and downstream at the time τ1 and τ2. Therefore, in this embodiment, the total number of wavelengths can be set to the number of wavelengths corresponding to 30 Gbps, which is lower than the conventional 40 Gbps.

  The TDM system management unit 56 holds the input wavelength number information r7 while overwriting and outputs the held wavelength number information r8 to the band allocation determination unit 57.

  The bandwidth allocation determining unit 57 determines the wavelength of the wavelength number based on the wavelength number information r8 based on the input traffic information r4, the communication path information r6 between the nodes Na1... Nc1, and the wavelength number information r8. A determination is made to assign λu and downlink wavelength λd to the rings R1 and R2a. Further, the bandwidth allocation determination unit 57 determines the number of uplink / downlink TSs based on the amount of uplink / downlink traffic, and the uplink wavelength λu at each TDM timing determined by the TDM system determination unit 55. And determine to assign the number of downlink TSs to the idle TS position of the downstream wavelength λd. Furthermore, the bandwidth allocation determination unit 57 determines that the number of TSs is allocated at each TDM timing of the optical switch operating at each node Na1... Nc1. Then, the bandwidth allocation determining unit 57 outputs the above determination content to the schedule table 58 as the bandwidth allocation information r9.

  The schedule table 58 stores and holds the input band allocation information r9 in a storage unit (not shown), and outputs the held band allocation information r10 to the node control signal generation unit 59. Each time the same bandwidth allocation information r9 is input from the bandwidth allocation determination unit 57, the schedule table 58 overwrites and holds the same.

  The node control signal generation unit 59 obtains a schedule for performing processing such as data transmission and switch switching of the corresponding node based on the input bandwidth allocation information r10, and includes the schedule contents and the bandwidth allocation information r10 to obtain a node control signal. The node control signal r11 is output to the input / output unit 50. The node control signal r11 is generated every TS amount update cycle T.

  Here, processing performed by the TDM system determination unit 55 and the band allocation determination unit 57 will be described in detail. The TDM system determination unit 55 calculates and compares the traffic amounts of uplink and downlink in units of the upper ring R1 and the lower ring R2a from the traffic information r4 for each source and destination of the input node. This is performed every TS amount update cycle T. Next, the TDM system determining unit 55 determines the number of wavelengths (uplinks) used in the uplink TSs in the rings R1 and R2a according to the ratio “for example, 7: 3” of uplink and downlink traffic amounts in the rings R1 and R2a. (Number of wavelengths) “for example 7” and the number of wavelengths used in the downlink TS (number of wavelengths for downlink) “for example 3” are determined, and the optical switches in the respective nodes Na1. The TDM timing to be determined is determined.

The number of upstream wavelengths of the upper ring R1 is obtained by the following equation (1).
Upper ring upstream wavelength number (xu) = CEILING (E, v) (1)
In Equation (1), E = total number of wavelengths of upper ring (n) × total amount of upper ring uplink traffic / (total amount of upper ring uplink traffic + total amount of upper ring downlink traffic), and v = 1.

  However, CEILING (E, v) is a sealing function and is represented by CEILING (numerical value, reference value). This CEILING (numerical value, reference value) function is a function that rounds up a specified reference value to a number larger than the target numerical value. That is, in the ceiling function, the “numerical value” is rounded up to the nearest value among multiples of the designated “reference value”. For example, if E = 2.5 (numerical value) and v = 1 (reference value), CEILING (2.5,1) = 3. That is, the number of upstream wavelengths of the upper ring R1 is obtained as a positive integer. The same applies to the lower ring R2a.

The number of downstream wavelengths of the upper ring R1 is obtained by the following equation (2).
Downstream wavelength number (xd) of upper ring R1 = upper ring total wavelength number (n) −upper ring upstream wavelength number (xu) (2)

Next, the number of upstream wavelengths of the lower ring R2a is obtained by the following equation (3).
Number of wavelengths for lower ring uplink (yu) = CEILING (F, v) (3)
In Equation (3), F = total number of lower ring wavelengths (q) × lower ring uplink traffic total amount / (lower ring uplink traffic total amount + lower ring downlink traffic total amount), and v = 1.

The number of downstream wavelengths of the lower ring R2a is obtained by the following equation (4).
Lower ring downlink wavelength number (yd) = lower ring total wavelength number (q) −lower ring uplink wavelength number (yu) (4)

  Next, the band allocation determining unit 57 obtains the number of wavelengths by the TDM system determining unit 55 as shown in the above equations (1) to (4), and this wavelength number information r7 is managed by the TDM system managing unit 56. When the wavelength number information r8 is input, the wavelength of each wavelength number based on the wavelength number information r8 is determined to be assigned as the upstream wavelength λu and the downstream wavelength λd at each TDM timing determined by the TDM system determination unit 55. Do.

  Here, when there are a plurality of lower rings, the band allocation determination unit 57 performs the first or second allocation determination process described later after determining the number of wavelengths. Here, the precondition is a one-way two-stage ring. The number of lower rings is dl, the upper ring is an integer multiple of the TS length, the lower ring is a non-integer multiple of the TS length, the number of wavelengths of the two-stage ring is W waves, and the number of TS in the period t is S. However, the one-way two-stage ring is the upper ring R1 and the lower rings R2a and R2b shown in FIG. 1, and the number of lower rings is dl = 2 and two lower rings R2a and R2b.

  The first assignment determination process is a process of assigning upstream wavelengths (ADD wavelengths) λu1 and λu2 having different wavelengths to the two lower rings R2a and R2b. In this case, different ADD wavelengths λu1 and λu2 are assigned to the two lower rings R2a and R2b, and a plurality of nodes in the same lower ring (for example, R2a) share the ADD wavelength λu1. The TS in the shared ADD wavelength λu1 can be DROPed at an arbitrary node in the upper ring R1.

  In this case, the TS allocation for communication from the lower rings R2a and R2b to the upper ring R1 is TS allocation calculation in parallel with dl (= 2) lower rings R2a and R2b because the number of lower rings is dl (= 2). (Described later). As described above, since the TS allocation can be calculated in parallel in the dl lower rings R2a and R2b, the calculation is faster than the case of calculating sequentially.

  The TS allocation for communication from the upper ring R1 to the lower rings R2a and R2b is a wavelength obtained by subtracting dl of the lower ring number from the W wave of the total number of wavelengths of the two-stage ring, that is, (W-dl) wavelength. TS allocation calculation using is performed.

  The second assignment determination process is a process for assigning the same ADD wavelength λu to all the lower rings R2a and R2b. In this case, for example, an A wave out of W waves is assigned for downstream traffic, and a (W-A) wave is assigned as an ADD wavelength λu for upstream traffic. Note that which of the first assignment determination process and the second assignment determination process is used is set in advance.

  Further, TS allocation for communication from the lower rings R2a and R2b to the upper ring R1 is performed by TS allocation calculation using (WA) wavelength. Further, TS allocation for communication from the upper ring R1 to the lower rings R2a and R2b is performed by TS allocation calculation using the A wavelength.

  Next, the band allocation determining unit 57 determines the number of uplink / downlink TSs based on the uplink / downlink traffic amount. That is, the band allocation determination unit 57 determines to allocate TSs that exist for the number of wavelengths × TS number (t / t0) to each path (route) of upstream traffic and downstream traffic. However, t is a repetition transmission cycle (TS transmission cycle) of TS1 to TS5 shown in FIG. 2, and t0 is a time width of 1TS.

  Further, the bandwidth allocation determination unit 57 can calculate the total traffic amount of the number of requested TSs of all the uplinks and downlinks for each destination from the traffic information r4 of each node, and the total traffic amount is calculated for each uplink and downlink. By comparing with the size of the wavelength band allocated to the network, it is determined whether the requested number of TSs for all the uplink and downlink paths can be accommodated in the allocated wavelength band.

  For example, when the total wavelength band allocated to uplink and downlink is “10”, it is assumed that “7” is allocated as the uplink wavelength band and “3” is allocated as the downlink wavelength band. In this case, if the number of requested TSs for all uplink paths is “7” and the number of requested TSs for all downlink paths is “2”, the downlink wavelength band “3” can be accommodated. However, if the number of requested TSs for all the upstream paths is “7” and the number of requested TSs for all the downstream paths is “5”, it cannot be accommodated in the downstream wavelength band “3”.

  When it is determined that the bandwidth can be accommodated, the bandwidth allocation determination unit 57 determines the allocation of the number of TSs as requested. For example, if the total traffic volume of the destination is 100 Mbps = 1 TS, the allocation of 10 TS is determined for a request whose total traffic volume of the destination is 1 Gbps. On the other hand, if it is determined that accommodation is not possible, allocation is not possible as requested for all paths (each ground-to-ground path), so the number of TSs allocated to each path can be reduced (reduction processing is performed) and accommodation is possible. To do. When reducing the number of TSs, the following is performed.

  The bandwidth allocation determination unit 57 determines the required bandwidth of each ground path, in other words, the number of TSs requested by each node for each path (the number of requested TSs), the physical bandwidth of each ring R1, R2a (uplink / downlink all allocated wavelength bandwidth) ), The number of requested TS for each path is reduced so that it can be accommodated by any one of the following methods (1) to (3). Decide to be.

  For example, as shown in FIG. 4, it is assumed that five nodes N1, N2, N3, N4, and N5 are connected to one ring R. In the case of this example, all the ground-to-ground paths have 20 paths from one individual node to the other four nodes. That is, the path from N1 to N2 {path ID (identification) = ID1)}, the path from N1 to N3 (ID2), the path from N1 to N4 (ID3), and from N1 to N5 Path (ID4), path from N2 to N3 (ID5), ... (middle omitted), path from N5 to N3 (ID19), path from N5 to N4 (ID20) There are 20 ways.

  (1) is a first fit (First Fit) based method. In this method, ID1 to ID20 are associated with 20 paths in advance as described above. At the same time, as shown in FIG. 5, a fair TS number Sf (for example, “3”) is defined.

  The fair TS number Sf is a threshold value that prevents the TS below the fair TS number Sf from being reduced when the requested TS number of each path is reduced. The fair TS number Sf is a value obtained by dividing the number of TSs in one signal frame = “S” by the number of paths passing through the ring R. For example, when S = 30 is shared by 10 paths passing through the ring R, Sf = 3.

  The bandwidth allocation determination unit 57 detects the number of requested TSs in the ascending order (or descending order) ID1, ID2, ID3,... Of each path ID after the ID1 to ID20 of each path and the fair TS number Sf are defined. If the detected TS number is larger than the fair TS number Sf, the requested TS number is decreased until the fair TS number Sf is reached.

  For example, in the example shown in FIG. 5, since the ID1 path requests “five” TSs, the TS exceeding the fair TS number Sf “3” is decreased by “two”. Next, since the ID2 path requests “7” TSs, the TS exceeding the fair TS number Sf “3” is decreased by “4”. Next, since the ID3 path requests “4” TSs, the TS exceeding the fair TS number Sf “3” is decreased by “1”. Next, the ID4 path requests “one” TS, and since this is a number equal to or less than the fair TS number Sf “3”, the reduction process is not performed. Thereafter, the same processing is performed up to the ID 20 pass in ascending order. This reduction process is performed until all the requested TS numbers can be accommodated.

  Also, when the number of requested TS is reduced as described above, the ID of the reduced path is stored as history information, and whether or not the reduction process is performed for the corresponding path according to the history information. To decide. For example, the number of request TSs for the path stored in the previous reduction process is not reduced in the current reduction process. With this process, it is possible to avoid a situation in which only a specific path is reduced in TS each time. In other words, the situation where excessive unfairness occurs can be avoided.

  (2) is a random fit (Random Fit) based method. In this method, as in (1) above, ID1 to ID20 are associated with each path, and the fair TS number Sf (for example, “3”) is defined.

  After this definition, the ID of each path to which the TS number exceeding the fair TS number Sf is assigned is randomly detected each time, and the requested TS number of the detected path is decreased until the fair TS number Sf is reached. If the number of requested TSs is reduced by detecting paths at random in this way, the paths are detected without depending on the reduction history, so that there is an excessive unfairness that only a specific path is reduced each time. The resulting situation can be avoided. In addition, since the paths are not detected in ascending order (or descending order), the time for reduction processing is suppressed.

  (3) is a sorting-based method. In this method, sorting is performed by the number of requested TSs of each path, the paths are arranged in the descending order of the number of requested TSs, and the number of requested TSs is decreased in the order of the increasing number of paths. In addition, you may perform in order with few request TS numbers.

  For example, as shown in FIG. 6A, the number of request TSs for the ID1 path is “5”, the number of request TSs for the ID2 path is “7”, the number of request TSs for the ID3 path is “4”, and the ID4 When the number of requested TSs for the path is “1”,... By this sorting, for example, as shown in FIG. 6 (b), ID2, ID10, ID1, ID3, ID9,..., ID15, ID4, and ID17 are arranged in descending order of the number of request TSs. The requested TS number is decreased until all the TS numbers can be accommodated.

  When this reduction process is performed, three types of processes can be considered as indicated by the lines 3a, 3b, and 3c in FIG. 6B. The process indicated by the line 3a is a process for making the requested TS numbers for all paths uniform (may be substantially uniform) so that the requested TS numbers for all paths ID1 to ID20 can be accommodated. In the process indicated by the line 3b, in addition to the process of the line 3a, a TS is slightly added to a path having many requests. The process indicated by the line 3c is to give a penalty to a path whose request for the number of TS is excessively large (such as an ID2 or ID10 path) and to equalize the number of requested TS.

  Next, the configuration of the core node Na1 or the access node Nc1 of the optical ring NW20 is shown as a block configuration diagram of the node N in FIG. Note that FIG. 7 may have a configuration of the intersection node Nb1.

  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 switching means described in 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 a TDM switching control signal, symbol j is buffer accumulation amount information, symbol k is a period t and The head start position information of period T, code l is TS change information, code m is TDM switching timing information, code n is head start timing information of a plurality of TSs, and code r11 is a node control signal transmitted from the scheduler SC described above. is there.

  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 between the nodes Na1... Nc1 as many as the number of paths (number of paths) in the optical ring NW20. In this embodiment, 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 r11 sent from the scheduler SC dropped by the optical switch unit 31 every TS amount update period T, and uses this node control signal r11 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 instructs TDM switching timing information that instructs 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. m is generated and output to the TS control unit 37.

  The TS change information l is information based on the node control signal r11 transmitted from the scheduler SC. The node control signal r11 includes band allocation information r10 (= r9) generated by the scheduler SC. This bandwidth allocation information r10 is information for giving the following three instructions. The first is to assign wavelengths of each number of upstream and downstream wavelengths according to the ratio of upstream and downstream traffic volume between nodes in which traffic exists to the multi-rings R1 and R2a as upstream wavelength λu and downstream wavelength λd. To give instructions. Second, in each uplink / downlink TS number based on each uplink / downlink traffic volume, the uplink TS number is assigned to an empty TS position of the uplink wavelength λu, and the downlink TS number is assigned to an empty TS position of the downlink wavelength λd. To give instructions. The third command instructs the allocation of the number of TSs at each TDM timing of the optical switch unit 31 operating at each node.

  That is, by using the TS change information 1 based on the band allocation information r10, the input port for uplink (for ADD) or downlink (for DROP) of the optical switch unit 31 is designated, and the uplink or downlink for this designated input port is designated. Specify TDM timing. Further, the TS change information 1 designates how many TSs are allocated within the designated TDM timing, and designates the TS number (for example, TS3) of which TS of the designated TS number is used. . In this example, the TDM timing is for uplink or downlink, but there are actually as many paths as there are paths.

  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.

  Further, the TS control unit 37 controls the switching of the TDM timing of the optical switch unit 31 by outputting the TDM switching control signal p to the optical switch unit 31 based on the TDM switching timing information m input from the TDM timing switching unit 40. I do.

  That is, the TS control unit 37 designates the input port numbers i1 to i4 for uplink or downlink of the optical switch unit 31 by the TDM switching control signal p, and the uplink or downlink of the designated input ports i1 to i4. The output port number (wavelength number) o1 to o4 is designated from which output port the TS of the TS number that operates at the TDM timing is transmitted, and TDM timing switching control is performed.

  The TDM timing switching control will be specifically described with reference to timing charts shown in FIGS. FIG. 8 is a timing chart of a first example when switching from downlink TDM to uplink TDM. FIG. 9 is a timing chart of the second example when switching from downlink TDM to uplink TDM. FIG. 10 is a timing chart of a first example when switching from uplink TDM to downlink TDM. FIG. 11 is a timing chart of a second example when switching from uplink TDM to downlink TDM.

  First, a first example of switching from downlink TDM to uplink TDM without changing the bandwidth will be described with reference to FIG. When switching to the uplink TDM while the optical switch unit 31 of the access node Nc1 is operating in the downlink TDM, for example, at the time τ5 when the TS transmission cycle t ends, the switch to the uplink TDM is performed as indicated by an arrow. In this case, there is a time from the time when switching to the uplink TDM (between TS3 between τ2 and τ6) to the next start time τ6 of the uplink cycle t, and this time becomes the offset value os1. Therefore, it is necessary to shift the offset value os1 after switching from the downlink TDM to the uplink TDM.

As an example, the offset value os1 is obtained by the following equation (5).
os1 = t-MOD (D, t) (5)
However, MOD (D, t) is a MOD function and is expressed by MOD (numerical value, divisor). D is a ring one-week delay time (one round delay time of the lower ring R2a), and t is a TS transmission cycle. The MOD (numerical value, reference value) function is a function for obtaining a remainder when a numerical value is divided by a divisor. For example, when D = 11 (numerical value) and t = 3 (divisor), MOD (11, 3 ) = 2.

  In this way, switching is performed from the time τ6 shifted by the offset value os1 to the upstream period t. In other words, the TS control unit 37 switches the TDM timing that operates at each input port (wavelength conversion unit) i1 to i4 of the optical switch unit 31 in accordance with the TDM timing of the path to which the TS to be controlled is assigned. This switching is switching from the downlink TDM to the uplink TDM.

  Next, a second example in which the bandwidth is changed to switch from the downlink TDM to the uplink TDM will be described with reference to FIG. As described above, after shifting the offset value os1 by the time to obtain the start time τ6 of the upstream TS amount update period T, the length of the first (first) upstream period T having the time τ6 to τ10 as one period T Is shortened by the amount corresponding to the sealing function (CF), and thereby the start timing of the second and subsequent upstream periods T is advanced by the amount corresponding to the ceiling function. However, the sealing function is also expressed as a CEILING (D, t) function.

  Specifically, as shown by an arrow CF from time τ10 to time τ10-CF, the upstream period T between the first time τ6 and time τ10 is shortened by the CEILING (D, t) function (CF). . Note that the scale of the arrow CF is conceptually shown. That is, the length of the first ascending period T is as short as T-CF between time τ6 and time τ10-CF. Time τ10-CF is the start timing of the second up period T, and the second and subsequent up periods T are the same as before the first shortening, so the start timings of the second and subsequent up periods T are substantially the same. , CEILING (D, t) function (CF minutes) is advanced. That is, the band change timing is switched.

That is,
Length of first ascending period T: T-CEILING (D, t)
Length of up-cycle T after the second time: T
It becomes.

  In other words, the TS control unit 37 has the same number of band change timings as the number of paths in the optical ring NW 20, and as described above, the input ports (wavelength conversion units) i1 to i4 of the optical switch unit 31. When the operating TDM timing is switched (switching from the downlink TDM to the uplink TDM), processing for switching the band change timing is also performed. This process is performed by the TDM switching control signal p.

  Next, a first example of switching from uplink TDM to downlink TDM without changing the bandwidth will be described with reference to FIG. When switching to the downlink TDM while the optical switch unit 31 of the access node Nc1 is operating in the uplink TDM, for example, at the time τ15 when the TS transmission cycle t ends, the switch to the downlink TDM is performed as indicated by an arrow. In this case, there is a time from the time when switching to the downlink TDM (between TS3 between τ12 and τ16) to the next start time τ16 of the downlink cycle T, and this time becomes the offset value os2. Therefore, after switching from the upstream TDM to the downstream TDM, it is necessary to shift the offset value os2.

As an example, the offset value os2 is obtained by the following equation (6).
os2 = MOD (D, t) (6)

  In this way, switching is performed from the time τ16 shifted by the offset value os2 to the upstream period t. In other words, the TS control unit 37 switches the TDM timing that operates at each input port (wavelength conversion unit) i1 to i4 of the optical switch unit 31 in accordance with the TDM timing of the path to which the TS to be controlled is assigned. This switching is switching from upstream TDM to downstream TDM.

Next, a second example in which the bandwidth is changed to switch from uplink TDM to downlink TDM will be described with reference to FIG. As described above, after shifting the offset value os2 by time to obtain the start time τ16 of the downlink TS amount update cycle T, the length of the first (first) downlink cycle T with the time τ16 to τ20 as one cycle T is further set. The numerical value calculated by the following equation (7) is shortened.
ABS {t-MOD (D, t) -CEILING (D, t)} (7)
However, ABS {t-MOD (D, t) -CEILING (D, t)} is an ABS function, and the calculation result in {t-MOD (D, t) -CEILING (D, t)} is absolute. Calculate as a value.
That is, the length of the first down period T is shortened by the ABS function (ABS part), and thereby the start timing of the second and subsequent down periods T is advanced by the ABS function.

  Specifically, the downward period T between the first time τ16 and the time τ20 is shortened by an ABS function (ABS) as indicated by an arrow ABS from time τ20 to time τ20-ABS. Note that the scale of the arrow ABS is conceptually shown. That is, the length of the first down period T is shortened to T-ABS between time τ16 and time τ20-ABS. The time τ20-ABS is the start timing of the second down period T, and the second and subsequent down periods T are the same as before the first shortening, so the start timings of the second and subsequent down periods T are substantially the same. , The ABS function (ABS) is advanced. That is, the band change timing is switched.

That is,
Length of first down cycle T: ABS {t-MOD (D, t) -CEILING (D, t)}
Second and subsequent downward period T length: T
It becomes.

  In other words, the TS control unit 37 has the same number of band change timings as the number of paths in the optical ring NW20, and the input ports (wavelength conversion units) i1 to i4 of the optical switch unit 31 as described above. After switching the operating TDM timing (switching from uplink TDM to downlink TDM), control is performed to further switch the band change timing. This control is performed by a TDM switching control signal p.

  In this way, by switching from the downlink TDM to the uplink TDM or from the uplink TDM to the downlink TDM, the wavelength of the wavelength band for each uplink and downlink traffic can be mutually exchanged in the uplink and downlink according to the amount of each uplink traffic. It is possible to assign. Accordingly, the node N can periodically change the TDM timing that operates in the optical switch unit 31 and the above-described allocated TS amount at the TS amount update period T.

<Operation of Embodiment>
Next, the switching operation of the TDM timing of the optical switch unit 31 of the nodes Na1... Nc1 constituting the optical ring NW20 of the present embodiment will be described with reference to the flowcharts shown in FIGS. 12 and 13 are flowcharts for explaining the bandwidth allocation determination operation of the scheduler SC for causing the optical switch unit 31 to perform the TDM timing switching operation, and FIG. 14 is the TDM timing switching of the optical switch unit 31 of the access node Nc1. It is a flowchart explaining operation | movement.

  First, the bandwidth allocation determination operation of the scheduler SC will be described with reference to FIGS. However, in the scheduler SC shown in FIG. 3, the topology information holding unit 52 receives information on all the nodes Na1... Nc1 of the optical ring NW20 and all the rings R1 and R2a 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. 12, the input / output unit 50 receives traffic information including the path between each node Na1... Nc1 and each traffic amount of uplink and downlink from each node 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.

  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 TDM system determination unit 55 and the band allocation determination unit 57.

  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 determination unit 55 and the bandwidth allocation determination unit 57.

  In step S5, the TDM system determination unit 55 determines between the nodes Na1... Nc1 for each TS amount update period T based on the communication path information r6 between the nodes Na1... Nc1 and the traffic information r4. The upstream and downstream traffic amounts are detected, and the number of upstream and downstream wavelengths is determined according to the ratio of the detected traffic amounts. For example, when the total number of uplink and downlink wavelengths is set to “10” in advance, and the ratio of the uplink and downlink traffic amounts is “7: 3”, the uplink wavelength number is “7” and the downlink wavelength is “7”. The number of wavelengths is determined to be “3”. Further, the TDM system determination unit 55 determines the TDM timing that operates at the input ports i1 to i4 as the upstream and downstream interfaces of the optical switch unit 31 in each node Na1... Nc1.

In this case, for example, when the ratio of the uplink and downlink traffic amounts in the previous TS amount update cycle T is “4: 6”, the uplink wavelength number is “4” and the downlink wavelength number is “6”. To do. This means that when the ratio of each traffic amount changes to “7: 3” in the current TS amount update period T, “3” out of the number of downstream wavelengths “6” is changed to upstream, and the number of upstream wavelengths Is determined to be “7” and the number of downstream wavelengths is determined to be “3”. In this case, as described later, in the optical switch unit 31 of the node Nc1, it is necessary to switch the TDM timing from the downlink to the uplink.
The TDM system determining unit 55 outputs to the TDM system managing unit 56 the wavelength number information r7 determined to be the upstream wavelength number “7” and the downstream wavelength number “3”.

  In step S <b> 6, the TDM system management unit 56 holds the input wavelength number information r <b> 7 while overwriting and outputs the held wavelength number information r <b> 8 to the band allocation determination unit 57.

  In step S7, the bandwidth allocation determination unit 57 performs the following determination processing based on the input traffic information r4, the communication path information r6 between the nodes Na1... Nc1, and the wavelength number information r8. First, a determination is made to assign the wavelength of the number of wavelengths based on the wavelength number information r8 to the rings R1 and R2a as the upstream wavelength λu and the downstream wavelength λd.

  In step S8 shown in FIG. 13, the bandwidth allocation determination unit 57 compares the number of requested TSs for each of the upstream and downstream paths for each destination and the size of the wavelength band allocated to each of the upstream and downstream from the traffic information r4. Thus, it is determined whether or not the requested number of TSs for all the uplink and downlink paths can be accommodated in the allocated wavelength band.

  If the result of this determination is that accommodation is impossible (No), in step S9, the bandwidth allocation determination unit 57 determines to reduce the number of TSs allocated to each path that cannot be accommodated so that accommodation is possible.

  On the other hand, if it can be accommodated (Yes), or after determining the decrease in the number of TSs in step S9, in step S10, the bandwidth allocation determination unit 57 determines the number of TSs in the uplink and downlink based on the traffic volume in the uplink and downlink. Then, a determination is made to assign the number of uplink TSs to an empty TS position of the upstream wavelength λu and to assign the number of downstream TSs to an empty TS position of the downstream wavelength λd.

  Next, in step S11, the bandwidth allocation determining unit 57 determines that the allocation of the number of TSs in step S10 is performed at each TDM timing of the optical switch operating in each node Na1... Nc1. Then, the bandwidth allocation determining unit 57 outputs the above determination content to the schedule table 58 as the bandwidth allocation information r9.

  In step S <b> 12, the schedule table 58 holds the input band allocation information r <b> 9 and outputs the held band allocation information r <b> 10 to the node control signal generation unit 59.

  In step S13, the node control signal generation unit 59 obtains a schedule for performing processing such as data transmission and switch switching of the corresponding node based on the input band allocation information r10, and includes the schedule content and the band allocation information r10. The node control signal r11 is generated and output to the input / output unit 50.

  In step S14, the input / output unit 50 transmits the node control signal r11 to the corresponding access node Nc1, for example, every TS update period T.

  Next, the TDM timing switching operation 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 r11 sent from the scheduler SC dropped by the optical switch unit 31 every TS amount update period T, and uses this node control signal r11 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 r10 described above, the ratio of the uplink and downlink traffic amounts is changed from “4: 6” of the previous cycle T to the current cycle T. In the case of changing to “7: 3”, the content includes an instruction to switch the TDM timing from the downlink to the uplink. The TDM switching timing information m is a signal for instructing the input port number (for example, i1, i2), the TDM timing, and the output port number (for example, o3, o4) of the optical switch unit 31 for the switching. At the same time, the TDM switching timing information m is a signal indicating the number of TSs assigned to the wavelength of the TDM timing to be switched by the instruction and the TS number of the free TS to which the TS of this TS number is assigned.

  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 S24, the TS control unit 37 outputs the TDM switching control signal p to the optical switch unit 31 based on the TDM switching timing information m, and the upstream or downstream input port number i1, of the optical switch unit 31. TDM timing switching control is performed by designating i2, TDM timing, and output port numbers (wavelength numbers) o3 and o4.

  In this TDM timing switching control, for example, as shown in FIG. 9, when switching from downlink TDM to uplink TDM, switching from downlink TDM to uplink TDM is performed at time τ5 when the TS amount update period T ends. At this time, a predetermined offset value os1 is shifted from the time point τ5 at which switching is performed to obtain the start time τ6 of the upstream period T. Thereafter, the length of the leading (first) ascending period T with the time τ6 to τ10 as one period T is shortened by the CEILING (D, t) function (CF), and the ascending period T of the second and subsequent times is shortened. The length is held in the length period T as it is.

  In step S25, the optical switch unit 31 sets the number of wavelengths in the uplink and downlink in accordance with the switching control of the TDM timing in step S24, and sets the number of wavelengths according to the amount of traffic in the uplink and the signal by the wavelength of these wavelengths. As many TSs as the number of TSs corresponding to the amount of traffic in the uplink and downlink are allocated to the empty TS.

  For example, when switching from downlink to uplink in the TDM timing switching control, the optical switch unit 31 sets “6” of the number of downlink wavelengths to “3”, and sets “6-3” = “3” to uplink. change. With this change, “4” of the number of upstream wavelengths is changed to “7”. The optical switch unit 31 assigns TS of the number of TSs corresponding to the amount of uplink and downlink traffic to the unused TS of the signal with the number of uplink wavelengths “7” and the number of downlink wavelengths “3” after the change. As a result, communication in the case where the ratio of the upstream and downstream traffic amounts is “7: 3” is realized.

  When switching from uplink TDM to downlink TDM in step S24, switching from uplink TDM to downlink TDM is performed at time τ15 when the TS amount update period T ends, as shown in FIG. At this time, a predetermined offset value os2 is shifted from the time point τ15 at which the switching is performed to obtain a start time τ16 of the down cycle T. Thereafter, the length of the first (first) downstream period T with time τ16 to τ20 as one period T is set to the ABS {t-MOD (D, t) -CEILING (D, t)} function (ABS minutes). ) Shorten the length of the second and subsequent downward periods T to the length period T as it is.

<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 an optical switch unit in the node N in accordance with the TDM timing of the route to which the TS to be controlled is allocated by the TDM timing switching unit 40 and the TS control unit 37 as switching means. The TDM timings operating at the input ports (wavelength converters) i1 to i4 as 31 interfaces are switched.

  The scheduler SC connected to the node N of this embodiment includes a TDM system determination unit 55 and a band allocation determination unit 57.

  The TDM system determining unit 55 assigns a different wavelength to each route in the network, detects each traffic amount for each route from the node N, and sets each number of wavelengths assigned to each route according to the ratio of each detected traffic amount. At the same time, a process for determining the TDM timing that operates at each interface of the optical switch in each node is performed.

  The bandwidth allocation determining unit 57 allocates the wavelength of each wavelength determined by the TDM system determining unit 55 for each path, and assigns the allocated TS amount for each path to each node N according to the traffic volume for each path between the nodes N. A process of generating a node control signal r11 for performing control for determining and allocating the TS of the allocated TS amount for each determined path to a free TS position set to the wavelength of each path at the determined TDM timing Do.

  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.

  In this embodiment, the node N that has received the node control signal r11 from the scheduler SC switches the TDM timing of the optical switch unit 31 from the downlink TDM timing to the uplink TDM timing according to each uplink and downlink traffic amount, or uplink Switch from TDM timing to downstream TDM timing. Here, for example, it is assumed that the downlink TDM timing is switched to the uplink TDM timing. By this switching, the node N performs an operation of allocating TS of the assigned TS amount instructed to the vacant TS position of the wavelength of the uplink route designated by the node control signal r11 at the uplink TDM timing after the switching.

  That is, when the ratio of the uplink and downlink traffic amounts changes, the node N dynamically changes the number of wavelengths and the allocated TS amount allocated to the uplink or downlink path so as to conform to the changed ratio. By dynamically changing in this way, the following effects can be obtained. For example, it is assumed that the ratio of uplink and downlink traffic amounts is “4: 6”, and the number of uplink wavelengths is assigned as “12” and the number of downlink wavelengths is “18” accordingly. Thereafter, it is assumed that the ratio of the upstream and downstream traffic amounts has changed to “7: 3”. In this case, “9” of the number of downstream wavelengths “18” is changed to the upstream TDM timing, the number of upstream wavelengths is “21”, and the number of downstream wavelengths is “9”. In this way, the number of wavelengths can be dynamically switched, and an allocated TS amount of TS can be allocated to the wavelength of the number of wavelengths after switching.

  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 (for example, “20”) corresponding to each maximum traffic amount of uplink and downlink to each uplink and downlink route. Therefore, “20” + “20” = “40” is necessary as the total number of wavelengths of the upstream and downstream paths.

  In the present embodiment, the total number of wavelengths of the uplink and downlink paths can be dynamically allocated to the uplink and downlink paths according to the amount of uplink and downlink traffic. In general, since it is unlikely that both uplink and downlink have the maximum traffic volume, in this embodiment, the total number of wavelengths for both uplink and downlink is calculated based on the total wavelength number “40” corresponding to each maximum traffic volume for uplink and downlink. For example, “30” can be used, and the upstream and downstream wavelengths can be used efficiently.

  Further, this will be described in detail with reference to the simulation result shown in FIG. FIG. 15 (a) shows how the upstream traffic indicated by the line Tru increases and the downstream traffic indicated by the line Trd decreases as time (minutes) elapses. For example, at the time of 1 minute, the uplink traffic volume is 125 Gbps, and the downlink traffic volume is 5 Gbps. At 13 minutes, the upstream and downstream traffic volume is the same 65 Gbps, and at 23 minutes, the upstream traffic volume is 5 Gbps and the downstream traffic volume is 125 Gbps.

  In this case, conventionally, in order to accommodate each uplink and downlink maximum traffic volume of 125 Gbps, for example, if one wavelength is 10 Gbps, the number of wavelengths corresponding to 125 Gbps is “13”, and the total number of uplink and downlink wavelengths Was “26”. Since the total number of wavelengths “26” is fixed, it becomes constant over time as indicated by a line 101 in FIG.

  However, in this embodiment, since the total number of wavelengths is dynamically allocated for uplink and downlink, the number of wavelengths that can accommodate traffic when the total traffic amount of both uplink and downlink is the largest may be allocated as the total number of wavelengths. . In FIG. 15A, the largest total traffic amount is 125 Gbps + 5 Gbps = 130 Gbps at the time of 1 minute or 23 minutes. Here, the number of wavelengths “for example, 14” corresponding to the traffic amount having a margin slightly more than 130 Gbps is assigned as the total number of wavelengths.

  At this time, since the ratio of the uplink and downlink traffic amounts is “1:25” at the time of 1 minute, “1” may be assigned to the number of uplink wavelengths and “13” may be assigned to the number of downlink wavelengths. At the time point of 13 minutes, since the ratio of each traffic amount is the same, the same “7” may be assigned to the number of upstream and downstream wavelengths. At the time of 23 minutes, the ratio of the uplink and downlink traffic amounts is “25: 1”, so “13” may be assigned to the number of upstream wavelengths and “1” to the number of downstream wavelengths.

  In this way, since the number of wavelengths may be dynamically allocated in accordance with the ratio of each traffic amount in the upstream and downstream, as shown by the line 102 in this embodiment in FIG. The number of wavelengths smaller than the number of wavelengths shown can be set as the total number of wavelengths. Accordingly, since the total number of wavelengths can be efficiently used according to each traffic amount between the upstream and downstream, the utilization efficiency of the wavelength band can be improved.

  The switching means of the node N has the same number of TDM timings as the number of routes in the network, and is configured to switch the TDM timing.

  As a result, the TDM timing of the currently operating path can be switched to the TDM timing of a different path. For example, it is possible to switch from the TDM timing of the currently operating downstream path to the TDM timing of the upstream path different from this.

  The switching means of the node N has the same number of band change timings as the number of routes in the network, and is configured to switch the band change timing after switching the TDM timing.

  In this way, for example, after switching to the uplink TDM timing, the band change timing is further switched to match the TS position of the uplink TDM timing with the receivable position at the destination node N.

  Further, the bandwidth allocation determination unit 57 determines that the number of TSs (requested bandwidth) requested by each node N for each path is larger than the number of TSs that can be accommodated in the wavelengths of the respective wavelengths determined by the TDM system determination unit 55. Then, processing is performed to reduce the requested number of TSs of the determined path so that it can be accommodated in the wavelength of the corresponding wavelength.

  According to this, when the requested TS number is larger than the number of TSs that can be accommodated in the wavelength of each allocated wavelength for each path, the requested TS number is decreased so that the communication is performed so that it falls within the wavelength of the allocated each wavelength number. Can be done.

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 (2)

A node holding a plurality of TDM timings set according to a propagation delay time of a path between nodes constituting the network,
In accordance with the TDM timing of the route to which the time slot to be controlled is assigned, the switching means for switching the TDM timing that operates at each interface of the optical switch in the node ,
The switching means has a number of TDM timings equal to the number of routes in the network, and switches the TDM timings . A node holding a plurality of TDM timings set according to a propagation delay time of a path between nodes constituting the network,
In accordance with the TDM timing of the route to which the time slot to be controlled is assigned, the switching means for switching the TDM timing that operates at each interface of the optical switch in the node ,
The switching means has a number of band change timings equal to the number of paths in the network, and switches the band change timing after switching the TDM timing .

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