JP6647193B2 - Optical ring network system and path control method therefor - Google Patents

Description

  The present invention relates to an optical ring network system and a path control method thereof.

  The power consumption of network elements (NEs), which is a network (NW) device, is increasing rapidly in proportion to the amount of Internet traffic in recent years, and it is increasingly important to construct networks with low power consumption and low cost. It has become. Above all, access / metro network devices with a large number of devices occupy the majority of NW power consumption, so it is important to reduce power consumption including radical architectural changes in access / metro networks.

  In the access network, it is considered that a wider band and lower power consumption per band are progressing in the future. The current metro network is based on a ring NW, and an optical ring system based on WDM (Wavelength division multiplex) using an OADM (Optical Add / Drop Multiplexer) that performs Add / Drop (A / D) at an optical level is commercially available. Has been Specifically, at present, a 10 Gbps / 100 Gbps ring system has been put into practical use, and will reach 400 Gbps / 1 Tbps in the near future. On the other hand, demand for low-speed paths of about 1 Gbps to 10 Gbps is expected in the future, and it is demanded that paths having a wide range of granularities from 1 Gbps to 100 Gbps be accommodated in the same ring and handled (Add / Drop).

  In order to accommodate a low-speed path such as 1 Gbps, in order to improve the accommodation efficiency, the path is edited once at the electric level, multiplexed to 10 Gbps, and then multiplexed to a 100 Gbps path. is there. However, in this configuration, since the processing of the electric signal is interposed, the power consumption increases as the capacity increases. Therefore, multiplexing at the optical level is practical for reducing power consumption. The technique described in Non-Patent Document 1 aims at reducing the power consumption of a metro network and the like, and as an approach based on an optical TDM (Time Division Multiplexing) method, each path on the same wavelength of a WDM transmission line in the network. , A band, that is, a time slot (hereinafter, also referred to as TS), and constitutes path handling (Add / Drop) in the optical layer. According to this conventional technique, it is expected that effective use of wavelength resources and power saving can be achieved.

  However, in the approach based on the optical TDM system, it is necessary to perform collision avoidance control so that, for example, a collision between a time slot of an Add signal and a time slot of a through signal does not occur. In the related art, Add / Drop operation is performed without causing a collision between TSs by performing high-speed wavelength switching for each TS according to a TS table set by a scheduler.

Kyota Hattori and 5 others, "Proposal of Optical L2 Switch Network", IEICE Technical Report, IEICE, June 14, 2012, vol.112, no.87, PN2012-3 (2012-06), p.13-18

  In the related art, complicated collision avoidance control is required, and the cost increases. Therefore, in an optical ring network system in which a master node serving as a control subject and a plurality of slave nodes serving as objects with respect to the control subject are connected by an optical transmission line, a control method in power-saving optical TDM is reduced. It can be realized by For example, a PON (Passive Optical Network) is a P2MP (Point to Multipoint) type optical network composed of passive (passive) elements such as an optical splitter, and can be realized at low cost. In the PON, an OLT (Optical Line Terminal) functioning as a master node and a plurality of ONUs (Optical Network Units) functioning as slave nodes are connected by P2MP.

  Therefore, in the PON, it is possible to set the time for the Add operation in the slave node for the upward traffic from the slave node to the master node. However, the time for the Add / Drop operation in the slave node cannot be set for the downlink traffic, and the time for the Drop operation in the slave node cannot be set for the uplink traffic. In other words, the PON of the current system has a problem in that when a path is formed between nodes sharing the same wavelength on the ring, a path cannot be formed between any nodes on the ring.

  In view of the above, an object of the present invention is to provide an optical ring network system and a path control method for solving the above-mentioned problem and enabling a path configuration between arbitrary nodes sharing the same wavelength on a ring.

In order to solve the above-described problems, the optical ring network system according to the present invention enables a master node serving as a control subject and a plurality of slave nodes serving as objects to the control subject to be able to perform bidirectional communication on an optical transmission line. An optical ring network system connected in a ring by a double ring, wherein the master node adjusts the time between each slave node and a time synchronization function unit, and a path of a path to be set in the ring. A path setting processing unit configured to set time information specifying Add / Drop time for each time slot and path setting information including a time slot time for the master node and each slave node on the same wavelength based on the path information; An optical switch that transmits or blocks a main signal that conducts the ring, and a previous switch based on the time set in the path setting information. A timing control unit for performing Add / Drop control on a main signal by an optical switch, wherein the slave node stores a path setting information set by the master node and a main signal for conducting the ring. An optical switch for transmitting or blocking, and a timing control unit for performing Add / Drop control on a main signal by the optical switch based on the time set by the path setting information , wherein the time synchronization function unit Between the master node and the slave node, the round trip time of the communication path from the master node to the slave node by round trip signal transmission is further calculated. Communicable from an optical transmission line or a master node in a second direction opposite to the first direction. Through the optical transmission path, the path generated for the slave node with respect to upstream traffic that is traffic toward the master node in the same direction as the return path transmitting the control signal from the slave node to the master node in the round-trip signal transmission. in setting information, as the time for the Add / Drop operation, characterized that you specify a time from the reception time at the master node is obtained by subtracting the round trip time.

Further, the master node according to the present invention has a master node serving as a control subject and a plurality of slave nodes serving as objects with respect to the control subject are formed in a ring with a double ring that enables bidirectional communication on an optical transmission line. A master node in the connected optical ring network system, a time synchronization function unit that performs time adjustment with each slave node, and the master node and the A path setting processing unit that sets time information specifying Add / Drop time for each time slot and path setting information including a time slot time for each slave node on the same wavelength, and transmits or blocks a main signal for conducting the ring An optical switch to be connected to the main signal by the optical switch based on the time set in the path setting information. / Includes a timing control unit which performs Drop control, the said time synchronization function unit, between the slave node to be communicated, the round trip time by the reciprocating signal transmission communication route from the master node to the slave node The path setting processor calculates an optical transmission path using a ring capable of communicating in a first direction from a master node or an optical transmission path using a ring capable of communicating in a second direction opposite to the first direction from a master node. In the round-trip signal transmission, in the path setting information generated for the slave node with respect to the upstream traffic that is the traffic heading to the master node in the same direction as the return path transmitting the control signal from the slave node to the master node in the round-trip signal transmission, , As the time for performing the Add / Drop operation, Characterized by specifying a time obtained from the kicking reception time by subtracting the round trip time.

The path control method according to the present invention includes a master node to be controlled mainly by a double ring in which the multiple slave nodes and an optical transmission line to be object to the control entity enables two-way communication A path control method in an optical ring network system connected in a ring, comprising: a time synchronization step of performing time synchronization between each of the slave nodes by the master node; and a path information of a path to be set in the ring. A path setting information generation step of setting time information specifying an Add / Drop time for each time slot and path setting information including a time slot time for the master node and each slave node on the same wavelength based on the slave node; Control signal including the path setting information generated for the slave node to be communicated to. A path setting information receiving step of receiving path setting information notified by the slave node by a control signal from the master node, and storing the received path setting information in a storage unit. look including a path setting information updating step of setting, the master node, following said time synchronization step, between the slave node to be communicated, a reciprocating from the master node of the communication path to the slave node The round trip time due to signal transmission is further calculated, and in the path setting information generating step, communication is performed in a second direction opposite to the first direction from an optical transmission path by a ring or a master node capable of communicating in a first direction from the master node. From the slave node in the round trip signal transmission, through an optical transmission path with a possible ring In the path setting information generated for the slave node with respect to the upstream traffic which is the traffic toward the master node in the same direction as the return path for transmitting the control signal addressed to the master node, the time at which the Add / Drop operation is performed is defined as A time obtained by subtracting the round trip time from the reception time at the node is designated .

According to the optical ring network system having such a configuration, the master node, or the path control method of such a procedure, the master node performs time synchronization with each slave node, and then sets the path information of the path to be set. , The path setting information is set in the master node and each slave node. The path setting information includes time information for specifying the Add / Drop time for each time slot on the same wavelength for the master node and each slave node, and the time slot time. Here, the time for performing Add / Drop is set for the master node and each slave node for each time slot on the same wavelength, so that the time slot of the Add signal and the time slot of the through signal are different. Collision avoidance control can be performed so that collision does not occur. Also, by setting the time on the path, the time for performing Add / Drop is set for each node on the ring for each time slot. Therefore, the time slot in which an empty space is created after dropping data at the end node of the predetermined path is set. At the next node, control can be performed such that an Add operation is performed using another data as a main signal with a time difference corresponding to the propagation time (FIGS. 12 and 10). That is, one time slot can be used with a time difference by a plurality of paths. Therefore, a path can be configured between arbitrary nodes sharing the same wavelength on the ring.
Further, according to the optical ring network system, the master node, or the path control method of the above procedure, in the optical ring network system, it is possible to set the Drop time in the upstream traffic that is impossible with the current PON. it can. Therefore, a bidirectional path configuration between arbitrary nodes sharing the same wavelength on the ring can be performed.

Further, the optical ring network system according to the present invention, the path setting processing unit, constitute the time slots for each specified path on the same wavelength, the opposite downlink traffic and the the uplink traffic Path setting information generating means for generating the path setting information for uplink traffic for each of the master node and each of the slave nodes, and updating path setting information for setting the path setting information generated for the master node in a storage unit Means, and path setting information notifying means for notifying a communication target slave node of a control signal including the path setting information generated for the slave node.

  According to such a configuration, in the optical ring network system, the Add / Drop time can be set in the downstream traffic, which is impossible with the current PON. Therefore, a bidirectional path configuration between arbitrary nodes sharing the same wavelength on the ring can be performed.

  According to the present invention, a path configuration between arbitrary nodes sharing the same wavelength on a ring can be performed.

It is a schematic structure figure showing typically the optical ring network system concerning the embodiment of the present invention. FIG. 3 is a functional block diagram schematically showing a master node. It is a functional block diagram which shows a slave node typically. FIG. 3 is a functional block diagram schematically illustrating a configuration example of a path setting processing unit, where (a) illustrates a path setting processing unit of a master node, and (b) illustrates a path setting processing unit of a slave node. FIG. 9 is an explanatory diagram schematically showing a flow of a path setting process in a master node for downlink traffic. FIG. 8 is an explanatory diagram schematically showing a flow of a path setting process in a master node for uplink traffic. FIG. 9 is an explanatory diagram schematically showing a flow of a path setting process in a slave node of downlink traffic. FIG. 9 is an explanatory diagram schematically showing a flow of a path setting process in a slave node of uplink traffic. FIGS. 6A and 6B are time charts illustrating an example of a path configuration in a comparative example, in which FIG. 7A is a system configuration and a path, FIG. (D) shows the path setting, and (e) shows the main signal conduction. 5 is a time chart for explaining a path configuration example of downlink traffic in an optical ring network system, wherein (a) is a system configuration and a path, (b) is a system configuration and a path route information represented on a straight line, and (c) is a Time setting, (d) shows path setting, and (e) shows main signal conduction. 5 is a time chart for explaining an example of a path configuration of uplink traffic in an optical ring network system, where (a) is a system configuration and a path, (b) is a system configuration and a path route information represented on a straight line, and (c) is a line chart. Time setting and RTT measurement, (d) shows path setting, and (e) shows main signal conduction. FIG. 2 is an explanatory diagram schematically illustrating an example in which a time slot is configured for each path on the same wavelength in an optical ring network system.

  Hereinafter, an optical ring network system and a path control method thereof according to the present invention will be described in detail with reference to the drawings.

(1st Embodiment)
[Configuration of Optical Ring Network System]
As shown in FIG. 1, the optical ring network system 1 is configured such that a plurality of network elements (network devices, hereinafter abbreviated as NE) are connected in a ring R by an optical transmission line. Here, NE # 0 is a master node (hereinafter, referred to as MN) serving as a control entity, and terminates a signal transmitted / received to / from an external device arranged outside the ring R. The other NEs # 1 to # 4 are slave nodes (hereinafter referred to as SNs) that are objects to the control subject. As will be described in detail later, each NE is connected to an optical switch (optical SW), an interface (IF) for inputting / outputting a client signal transmitted from an external device such as a router (not shown), or a control device (not shown). And an interface (IF) for inputting a control signal to be received.

In FIG. 1, the flow of the optical signal counterclockwise (counterclockwise) when the ring R is viewed from above is indicated by three types of arrows.
The thin arrow indicates a Gigabit Ethernet (registered trademark) client signal (1G), which is added (inserted) to the ring R at NE # 3 and dropped (dropped) from the ring R at NE # 0. The path for the upstream traffic from NE # 3 to NE # 0 is set in such a manner as to be performed. Since Add / Drop itself is conventionally known, it will not be particularly described below.

The bold arrow indicates a 100 GbE client signal (100 G), which is added by NE # 0 and dropped by NE # 3 for the downstream traffic from NE # 0 to NE # 3. The path has been set. Note that the upstream traffic is traffic in the direction from the SN to the MN, and the downstream traffic is traffic in the direction from the MN to the SN.
The dashed arrow indicates a 10 GbE client signal (10 G). This signal is added by NE # 4, passed through NE # 0, and dropped by NE # 1 and NE # 4 and NE # 1. A path is set between # 1.

  The ring R is a transmission line using an optical fiber, and it is assumed that one-way communication is performed. In the present embodiment, in order to enable two-way communication, the ring R as viewed from above in FIG. 1 has a double configuration as shown in FIG. For example, in FIG. 10A, the inner ring is a left-handed (counterclockwise) path, and the outer ring is a right-handed (clockwise) path. In FIG. 1, a clockwise (clockwise) ring is omitted.

[Master node configuration]
A configuration example of the master node (MN) will be described with reference to FIG.
The master node (MN) 100 includes an optical switch 110, optical couplers 120 and 130, a signal processing unit 140, a memory 150, a time synchronization function unit 160, a path setting processing unit 170, a timing control unit 180, It has.

The optical switch 110 transmits (ON) or blocks (OFF) an input optical signal which is a main signal or a control signal for conducting the ring R.
The optical coupler 120 branches an optical signal input from an optical fiber, which is an optical transmission line constituting the ring R, to the optical switch 110 and the signal processing unit 140.
The optical coupler 130 combines the optical signal output from the optical switch 110 and the optical signal output from the signal processing unit 140 and transmitted in a burst. The burst signal is a signal having a difference in light intensity.

  The signal processing unit 140 performs input / output processing of a client signal sent from an external device such as a router. As shown in FIG. 2, the signal processing unit 140 includes a burst reception unit 141, a header analysis unit 142, a switch unit 143, an IF transmission unit 144, an IF reception unit 145, a switch unit 146, and a buffer 147. And a burst transmission unit 148.

In FIG. 2, the signal processing unit 140 shown by a broken line on the right side omits internal sub-blocks, but forms a pair with the signal processing unit 140 shown by a broken line on the left side in FIG. That is, the signal processing unit 140 on the left side inputs the optical signal from the optical coupler 120 to which the signal of the clockwise transmission path is input to the burst receiving unit 141, and the optical signal from the burst transmitting unit 148 via the optical coupler 130. This is a configuration for outputting to the counterclockwise transmission path.
On the other hand, in the signal processing unit 140 on the right side, the optical signal from the optical coupler 120 to which the signal on the counterclockwise transmission path is input is input to the burst receiving unit 141, and the optical signal from the burst transmitting unit 148 is transmitted via the optical coupler 130. In this configuration, the data is output to the clockwise transmission path.

The burst receiving unit 141 converts an optical signal transmitted from another network device (NE) and branched by the optical coupler 120 into an electric signal. The converted electric signal is input to the header analysis unit 142.
The header analyzer 142 analyzes the header of the input signal and determines whether the input signal is a control signal or a main signal. The control signal is sent to the path setting processing unit 170, and the main signal is sent to the switch unit 143.
The switch unit 143 is a switch unit similar to a normal electric SW (L2-SW). The switch unit 143 transfers packet data to an external device such as a router according to a table set in advance.

The IF transmission unit 144 is an Ethernet (registered trademark) interface, converts an electric signal sent from the switch unit 143 into an optical signal, and sends the optical signal to a router or other external device as a client signal.
The IF receiving unit 145 is an Ethernet (registered trademark) interface, terminates a client signal from an external device such as a router, converts an optical signal as a client signal into an electric signal, and sends the optical signal to the switch unit 146.

  The switch unit 146 is a switch unit similar to a normal electric SW (L2-SW). The switch unit 146 transfers the packet data to the ring R according to a table set in advance.

  The buffer 147 stores data (client signal) input from an external device such as a router. Data is transmitted from the buffer 147 to the burst transmission unit 148. The buffer 147 transmits the control signal input from the path setting processing unit 170 from the burst transmission unit 148 to another network device (NE).

  The burst transmission unit 148 converts a data signal and a control signal to be transmitted to another network device (NE) from an electric signal to an optical signal, and transmits the optical signal as an optical burst signal according to an instruction of the path setting processing unit 170. . The optical burst signal is transmitted to the ring R, which is an optical transmission line, via the optical coupler 130.

The memory 150 is a storage unit that stores path setting information, and is configured by, for example, a general semiconductor memory or the like.
Here, the path setting information includes Add time and Drop time for each time slot in the network device (NE) for the downlink traffic and the uplink traffic, and the time slot time.
The time slot time is a time slot time according to a set band for each path and does not include a so-called guard time.
The memory 150 stores the path setting information of the MN 100 and the path setting information of each slave node (SN).

The time synchronization function unit 160 adjusts time with each SN.
The time synchronization function unit 160 increments the reference value (reference time) set by the MN 100 according to a clock from an internal clock unit (not shown). The incremented value (counter value) indicates the current time of the MN 100. In time adjustment with the SN, a time stamp of the current time of the MN 100 is added to the control signal.

For the uplink traffic, the time synchronization function unit 160 calculates a round-trip time (RTT: round-trip time) between the MN 100 and the SN to be communicated by the round-trip signal transmission of the communication path from the MN 100 to the SN.
The time synchronization function unit 160 measures the round trip time between each SN from the time stamp value described in the control signal from each SN and the counter value in the time synchronization function unit 160.

  The path setting processing unit 170 includes, based on the path information of the path to be set in the ring (R), the time information specifying the Add / Drop time for each time slot on the same wavelength for the MN 100 and each SN and the time slot. The path setting information including the time is set.

  In the present embodiment, as an example, as shown in FIG. 4A, the path setting processing unit 170 includes a path information acquiring unit 171, a path setting information generating unit 172, a path setting information updating unit 173, a path setting Information notification means 174.

  The route information obtaining means 171 obtains path route information (hereinafter, path route information) from a control device (not shown) arranged outside the MN 100 via a control interface (omitted in FIG. 2). The path route information includes, as information on both end points of the path, identification information and operation information on two NEs that perform one or both of Add / Drop path handling. The path route information may be either a path of upstream traffic or a downstream traffic between NEs forming the ring R, and an operator of the control device can set a desired route. In the present embodiment, it is assumed that the path route information is stored in the MN 100 before setting a path. The path route information may be externally input and updated each time processing is performed.

The path setting information generating means 172 forms a time slot (TS) for each path specified on the same wavelength, and generates path setting information for downlink traffic and uplink traffic for the MN 100 and each SN. Is what you do.
The path setting information generation unit 172 uses the transmission timing synchronized with the time at the MN 100 (the counter value in the time synchronization function unit 160) as the time stamp in the path setting information on the downlink traffic with respect to the SN to be communicated. , To the burst transmission unit 148.

  The path setting information generating means 172 calculates the time obtained by subtracting the round trip time from the reception time at the MN 100 as the time for performing the Add / Drop operation in the path setting information for the uplink traffic for the SN to be communicated. specify. Specifically, the transmission timing is notified to the burst transmission unit 148 as a time stamp. The round trip time is measured by the time synchronization function unit 160.

The path setting information updating unit 173 sets the path setting information generated for the MN 100 in the memory 150.
The path setting information notifying unit 174 notifies the control target SN of a control signal including the path setting information generated for each SN.

The timing control unit 180 performs Add / Drop control on the main signal by the optical switch 110 based on the time set in the path setting information.
The timing control unit 180 controls the transmission (ON) or the cutoff (OFF) of the optical switch 110 based on the time set in the path setting information for the downlink traffic and the uplink traffic.
The timing control unit 180 compares the counter value (current time) in the time synchronization function unit 160 with the timing value (assigned time) described in the path setting information according to the path setting information set by the MN 100, and performs burst transmission. The unit 148 controls the TS transmission operation.

[Slave node configuration]
A configuration example of the slave node (SN) will be described with reference to FIG.
As shown in FIG. 3, the slave node (SN) 200 includes an optical switch 110, optical couplers 120 and 130, a signal processing unit 140, a memory 250, a time synchronization function unit 260, and a path setting processing unit 270. , A timing control section 280. In the configuration of the SN 200, the same components as those of the MN 100 in FIG. Although the signal processing unit 140 shown by a broken line on the right side in FIG. 3 omits internal sub-blocks, it forms a pair with the signal processing unit 140 shown by a broken line on the left side in FIG. 3 as follows. .

  The memory 250 is a storage unit that holds the path setting information of the SN 200 set by the MN 100, and is configured by, for example, a general semiconductor memory.

Time synchronization function section 260 receives the reference value (reference time) set by MN 100, and increments the reference value according to a clock from an internal clock section (not shown).
In the time setting for setting the path of the uplink traffic, the time synchronization function section 260 performs time synchronization upon receiving a control signal from the MN 100, and then performs transmission time of the control signal addressed to the MN 100 from the SN 200 (time in the SN 200). (The current time of the control signal).
The time synchronization function unit 260 performs time synchronization when receiving a control signal from the MN 100 in the time setting for setting the path of the downstream traffic, but since the round-trip time is not measured, the control signal with the time stamp is provided. Do not reply to.

The path setting processing unit 270 includes, as an example, a path setting information receiving unit 271 and a path setting information updating unit 272, as shown in FIG.
The path setting information receiving means 271 receives the path setting information notified from the MN 100 by a control signal.
The path setting information updating unit 272 sets the received path setting information in the memory 250.

The timing control section 280 controls the transmission (ON) or the cutoff (OFF) of the optical switch 110 for the downlink traffic and the uplink traffic based on the time set in the path setting information.
The timing control unit 280 compares the counter value (current time) in the time synchronization function unit 260 with the timing value (assigned time) described in the path setting information according to the path setting information received from the MN 100 and stored in the memory 250. Then, it controls the TS transmission operation for the burst transmission section 148.

[Path setting at master node for downlink traffic]
The flow of the path setting process in the master node (MN) for the downlink traffic will be described with reference to FIG. 5 (see FIGS. 2, 3 and 4A as appropriate).
First, the path setting processing unit 170 of the MN 100 transmits the time information from the time synchronization function unit 160 to each SN 200, and synchronizes the time with each SN 200 (Step S101: time synchronization). In FIG. 5, the flow of the control signal in step S101 is indicated by a thin broken arrow.

  Then, the path setting processing section 170 of the MN 100 generates path setting information (Add / Drop time and time slot time) for each SN 200 and itself (MN 100) by the path setting information generating means 172, and updates the path setting information updating means 173. Then, the path setting information generated for the MN 100 is stored in the memory 150 (step S102: path setting information updating step). In FIG. 5, step S102 is indicated by a thin solid line arrow.

  Then, the path setting processing unit 170 of the MN 100 transmits the path setting information set in step S102 to each SN 200 by the path setting information notifying unit 174 (step S103: path setting information notification step). In FIG. 5, step S103 is indicated by a thick solid line arrow.

  Then, based on the time set by the path setting information stored in the memory 150, the timing control unit 180 of the MN 100 controls the burst transmission unit 148 for burst signal output timing control (Add), and also controls the downstream optical switch 110. (Through) / OFF (Drop) control is performed on (step S104). In FIG. 5, step S104 is indicated by a thick broken line arrow.

[Path setting at master node for uplink traffic]
Next, the flow of the path setting process in the master node (MN) for uplink traffic will be described with reference to FIG. 6 (see FIGS. 2, 3, 4 (a) and 5 as appropriate).
The path setting processing unit 170 of the MN 100 transmits the time information from the time synchronization function unit 160 to each SN 200, synchronizes the time with each SN 200 (step S101: see FIG. 5), and measures the round trip time ( Step S111: time synchronization, RTT measurement). In FIG. 6, the flow of the control signal in step S111 is indicated by a broken arrow.

  Then, based on the round trip time acquired in step S111, the path setting processing unit 170 of the MN 100 uses the path setting information generation unit 172 to set the path setting information (Add / Drop time and time slot) for each SN 200 and itself (MN 100). ), And the path setting information updating means 173 stores the path setting information generated for the MN 100 in the memory 150 (step S112: path setting information generating step). In FIG. 6, step S112 is indicated by a thin arrow.

  Then, the timing control unit 180 of the MN 100 performs ON (Through) / OFF (Drop) control for the optical switch 110 in the up direction based on the time set by the path setting information stored in the memory 150 (Step S113). ). In FIG. 6, step S113 is indicated by a thick arrow.

[Path setting in slave node for downlink traffic]
Next, the flow of a path setting process in the slave node (SN) for downlink traffic will be described with reference to FIG. 7 (see FIGS. 3, 4B and 5 as appropriate).
When the SN 200 receives time information for time setting from the MN 100 by the path setting processing unit 270 (step S101: see FIG. 5), the time synchronization function unit 260 synchronizes the time (step S201: time synchronization). ). In FIG. 7, the flow of the control signal in step S201 is indicated by a broken arrow.

  Then, when the path setting processing unit 270 of the SN 200 receives the path setting information (Add / Drop time and time slot time) from the MN 100 by the path setting information receiving unit 271 (step S103: see FIG. 5), the path setting information is updated. The path setting information is stored in the memory 250 by the means 272 (step S202: path setting information updating step). In FIG. 7, step S202 is indicated by a thin arrow.

Then, the timing control unit 2 80 of SN200, based on the set time in the path setting information stored in the memory 2 50 performs ON (Through) / OFF (Drop ) control over the bottom up direction of the optical switch 110 (Step S203). In FIG. 7, step S203 is indicated by a thick arrow.

[Path setting in slave node for uplink traffic]
Next, a flow of a process of setting a path in a slave node (SN) of uplink traffic will be described with reference to FIG. 8 (see FIGS. 3, 4B, 5, and 7 as appropriate).
SN200 is by the path setting section 270, from the MN 100, receives the time information for the time setting (step S101: FIG. 5, step S201: see FIG. 7), with the time synchronization function unit 2 60 synchronizes the time , A control signal with a time stamp indicating the transmission time in SN 200 is returned to MN 100 (step S211: RTT measurement). The MN 100 can measure the RTT based on the reply from the SN 200. In FIG. 8, the flow of the control signal in step S211 is indicated by a broken arrow.

  Then, when the path setting processing unit 270 of the SN 200 receives the path setting information (Add / Drop time and time slot time) from the MN 100 by the path setting information receiving unit 271 (step S103: see FIG. 5), the path setting information is updated. The path setting information is stored in the memory 250 by the means 272 (step S212: path setting information updating step). In FIG. 8, step S212 is indicated by a thin arrow.

Then, the timing control unit 2 80 of SN200, based on the set time in the path setting information stored in the memory 2 50, the burst signal output timing control to burst transmission unit 148 (Add), The upper up direction of ON (transmission) / OFF (Drop) control is performed on the optical switch 110 (step S213). In FIG. 8, step S213 is indicated by a thick arrow.

Hereinafter, a path control method in the optical ring network system 1 according to the embodiment of the present invention will be described in comparison with the current PON method.
[Path control method of comparative example]
First, an example of a path configuration in the case of the current PON system which is a comparative example will be described with reference to FIG. In the system configuration shown on a straight line in FIG. 9B, NE # 0 (MN) is arranged at the left end, and NEs are sequentially arranged counterclockwise on the ring in FIG. 9A. It is. Note that the rightmost NE # 0 is the same MN as the leftmost NE # 0.

In the example shown in FIG. 9B, in an optical signal of a predetermined wavelength, data from an external device is added to TS # 1, which is a time slot, by NE # 1 and dropped by NE # 0. Path route information is assumed.
Also, it is assumed that the path route information is such that data from an external device is added to the TS # 2 of the same wavelength by the NE # 2 and dropped by the NE # 0.

In order to set the path of the route information shown in FIG. 9B, it is necessary to previously set the time and measure the RTT between the NE # 0 (MN) and each SN as shown in FIG. 9C. There is.
For example, NE # 0 (MN) by sending a control signal including a time stamp of transmission time T ₁₀ to NE # 1, and sets the time at which the control signal NE # 1 receives the T ₁₀ (step S1). Here, the suffix (10) of T means the set time transmitted from NE # 0 to NE # 1, and if _Tij , it is transmitted from NE # j to NE # i. Means the set time.
Then, NE # 0 calculates the round trip time RTT ₀₁ between NE # 0 and NE # 1. Here, the subscript (01) of the RTT means the round trip time measured from NE # 0 to NE # 1, and if it is RTT _ij , the round trip measured from NE # i to NE # j. Means time. Here, round trip time RTT ₀₁ is determined as the difference between the NE # 0 is the time T ₀₁ that has received a control signal including a time stamp of transmission time T ₁₁ in NE # 1 from NE # 1, and the transmission time T ₁₁ Can be

Further, NE # 0 (MN) by sending a control signal including a time stamp of transmission time T ₂₀ to NE # 2, and sets the time at which the control signal NE # 2 has received the T ₂₀ (step S2). Then, NE # 0 calculates the round trip time RTT ₀₂ between NE # 0 and NE # 2. Hereinafter, similarly, the NE # 0 (MN) sets the time with the SN.

Here, it is assumed that the above paths are set with the times at which the data of TS # 1 and TS # 2 drop at NE # 0, for example, as T ₁ and T ₂ respectively.
In this case, as shown in FIG. 9D, the NE # 0 (MN) sets the time t at which the NE # 1 performs the Add operation on the TS # 1 to (T ₁ -RTT ₀₁ ). _By transmitting _1- RTT ₀₁ (Add)) to NE # 1, a path is set to NE # 1 (step S3).
Further, NE # 0 (MN) is, NE # control signal is set to the time t for the Add operation with respect to _{TS # 2 (T 2 -RTT 02} ) in _{2 (T 2 -RTT 02 (Add} )) to NE # 2, the path is set to NE # 2 (step S4).

With this setting, when the time of NE # 1 is (T ₁ −RTT ₀₁ ), the NE # 1 performs an Add operation on the main signal for TS # 1 of a predetermined wavelength, as shown in FIG. (e), the time T ₁ of the NE # 0, NE # 0 to Drop data from NE # 1.
Also, the TS # 2 of the same wavelength, when the time of the NE # 2 is (T ₂ -RTT _02), the NE # 2 is the Add operation to the main signal, as shown in FIG. 9 (e) , to the time T ₂ of the NE # 0, NE # 0 to Drop the data from the NE # 2.

  However, in the current PON system, which is a comparative example, the Add / Drop path cannot be set in the downlink traffic from the MN to the SN, and the Drop path cannot be set in the uplink traffic.

[Configuration example of time slot for each path]
Next, as an assumption of a path control method for downlink traffic in the optical ring network system 1 according to the embodiment of the present invention, an example in which a time slot is configured for each path on the same wavelength will be described with reference to FIG.
In FIG. 12, for example, traffic in the direction from NE # 0 (MN) to NE # 1 (SN) and traffic in the direction from NE # 0 (MN) to NE # 2 (SN) are downlink traffic. Are schematically indicated by solid-line arrows connecting the shortest distances between the nodes, but actual traffic flows along a ring that is an optical transmission path. Hereinafter, this downstream traffic is referred to as NE # 0 → NE # 1, # 2 direction traffic.

  In FIG. 12, a signal (data) addressed to NE # 1 added to the main signal passing through the ring from NE # 0 is indicated by "01", and similarly, data addressed from NE # 0 to NE # 2 is "02". Indicated by. Here, for example, eight time slots are assumed. Then, in the NE # 0 → NE # 1 and # 2 direction traffic, TS # 1 is allocated to communication between NE # 0 and NE # 1, and TS # 2 is connected to NE # 0 and NE # 2. Assigned to communication.

  For example, in the traffic from NE # 0 to NE # 1, # 2, NE # 0 adds data "01" in TS # 1 and adds data "02" in TS # 2. Then, the NE # 1 drops the data “01” addressed to the own node transmitted by the TS # 1, and transmits (through) the data “02” transmitted by the TS # 2. Then, the NE # 2 drops the data “02” addressed to the own node transmitted by the TS # 2.

  In FIG. 12, focusing on NE # 1, which is a node through which the main signal passes (through), the time slot (TS # 1) of the main signal added by NE # 0 and the time of the main signal passing (through) It is necessary to control to avoid collision with the slot (TS # 2). In FIG. 12, paths for traffic in the upward direction are schematically indicated by broken-line arrows.

[Path control method for downlink traffic]
Next, a path control method relating to downlink traffic in the optical ring network system 1 in which a time slot is configured for each path on the same wavelength and collision avoidance control is performed will be described with reference to FIG. Note that the same configuration, processing, or procedure as in FIG. 9 will be omitted as appropriate.

  In the example shown in FIG. 10B, in an optical signal of a predetermined wavelength, path information such that data from an external device is added to NE # 0 and dropped by NE # 1 is added to TS # 1. I assume. Also, TS # 1 is assumed to have path route information in which data from an external device is added by NE # 1 and dropped by NE # 2. Further, NE # 2 adds path data from an external device and drops the data in NE # 3, and NE # 3 adds data from the external device and drops the data in NE # 4. Such path route information is assumed.

Further, it is assumed that the TS # 2 of the same wavelength has path route information in which data from an external device is added by the NE # 0 and dropped by the NE # 2.
Further, it is assumed that the TS # 3 of the same wavelength has path route information in which data from an external device is added by the NE # 1 and dropped by the NE # 3.

In order to set the path of the route information shown in FIG. 10B, it is necessary to set time in advance between NE # 0 (MN) and each SN as shown in FIG. 10C.
For example, NE # 0 (MN) by sending a control signal including a time stamp of transmission time T ₁₀ to NE # 1, and sets the time at which the control signal NE # 1 receives the T ₁₀ (step S11: Time synchronization step).
Further, NE # 0 (MN) by sending a control signal including a time stamp of transmission time T ₂₀ to NE # 2, and sets the time at which the control signal NE # 2 has received the T ₂₀ (step S12: Time synchronization step). Hereinafter, similarly, the NE # 0 (MN) sets the time with the SN.

Here, it is assumed to set a path as a TS # 1, TS # 2, TS # respectively, for example T ₁ a time to Add each data NE # 0 of _3, T _2, T 3.
In this case, as shown in FIG. 10 (d), NE # 0 (MN) is, NE # control signal to set the time t to T ₁ to the Drop / Add operate on TS # 1 in ₁ (T 1 (Drop / Add)) and, by sending control signal (T ₃ to set the time t to the Add operation T ₃ with respect to TS # 3 and (Add)) to NE # 1, passes set to NE # 1 ( Step S13). Step S13 corresponds to a path setting information notification step and a path setting information receiving step.

Further, NE # 0 (MN) includes a control signal to set the time t to T ₁ to the Drop / Add operate on TS # 1 in _{NE # 2 (T 1 (Drop} / Add)), with respect to TS # 2 Drop By transmitting a control signal (T ₂ (Drop)) for setting the operation time t to T ₂ to NE # 2, the path is set to NE # 2 (step S14).

Further, NE # 0 (MN) includes a control signal to set the time t to T ₁ to the Drop / Add operate on _{TS # 1 (T 1 (Drop} / Add)) in NE # 3, with respect to TS # 3 Drop By transmitting a control signal (T ₃ (Drop)) for setting the operation time t to T ₃ to NE # 3, the path is set to NE # 3 (step S15).

Further, NE # 0 (MN) by sending a control signal to set the time t to T ₁ to the Drop operation with respect to TS # 1 in _{NE # 4 (T 1 (Drop} )) to NE # 4, NE The path is set to # 4 (step S16). Steps S14 to S16 correspond to a path setting information notification step and a path setting information receiving step.

With these settings, for TS # 1 of a predetermined wavelength, at time T ₁ of the NE # 0, the NE # 0 to the Add operation to the main signal, as shown in FIG. 10 (e) to, NE # 1 is the time T ₁ of the NE # 1, while Drop data from NE # 0, NE # 1 to the Add operation to the main signal.
Then, NE # 2 is the time T ₁ of the NE # 2, while Drop data from NE # 1, NE # 2 is the Add operation to the main signal.
Then, NE # 3 is the time T ₁ of the NE # 3, while Drop data from NE # 2, NE # 1 to the Add operation to the main signal.
Then, NE # 4 is the time T ₁ of the NE # 4, to Drop data from NE # 3.

Also, if you set in this way, for the TS # 2 of the same wavelength, at time T ₂ of the NE # 0, the NE # 0 to the Add operation to the main signal, in FIG. 10 (e) as shown, NE # 1 is the data at time T ₂ of the NE # 1 transmitted (through), NE # 2 at time T ₂ of the NE # 2, to Drop data from NE # 0.

Also, if you set in this way, for the TS # 3 of the same wavelength, at time T ₃ of NE # 1, the NE # 1 to the Add operation to the main signal, in FIG. 10 (e) as shown, NE # 2 is then through the time T ₃ of the NE # 2, NE # 3 at time T ₃ of the NE # 3, to Drop data from NE # 1.

[Path control method for uplink traffic]
Next, a path control method relating to upstream traffic in the optical ring network system 1 in which a time slot is configured for each path on the same wavelength and collision avoidance control is performed will be described with reference to FIG. Note that the same configuration, processing, or procedure as in FIGS. 9 and 10 will be omitted as appropriate.

  The example shown in FIG. 11B differs from FIG. 9B in that the following path route information is added to the path route information shown in FIG. 9B. That is, in an optical signal of a predetermined wavelength, path information in which data from an external device is added to NE # 4 and dropped by NE # 3 is assumed for TS # 1. Also, TS # 1 is assumed to have path route information in which data from an external device is added by NE # 3 and dropped by NE # 2. Further, it is assumed that the path route information is such that data from an external device is added in NE # 2 and dropped in NE # 1.

The path route information assumed for TS # 2 having the same wavelength is the same as the path route information shown in FIG.
Further, for TS # 3 of the same wavelength, path route information is assumed in which data from an external device is added by NE # 3 and dropped by NE # 1.

  In order to set the path of the route information shown in FIG. 11B, it is necessary to previously set the time and measure the RTT between the NE # 0 (MN) and each SN as shown in FIG. 11C. There is. These operations are the same as those in FIG. Step S21 in FIG. 11B is the same process as step S1 in FIG. 9B, and step S22 in FIG. 11B is the same process as step S2 in FIG. 9B.

Here, it is assumed that setting the TS # 1, TS # 2, TS # respectively, for example T ₁ each data time to Drop in NE # 0 of 3, T _2, T ₃ as the path.
In this case, as shown in FIG. 11D, the NE # 0 (MN) sets the time t at which the Add / Drop operation is performed on the TS # 1 in the NE # 1 to (T ₁ −RTT ₀₁ ). (T ₁ −RTT ₀₁ (Add / Drop)) and a control signal (T ₃ −RTT ₀₁ (Drop)) for setting the time t at which the Drop operation is performed on TS # 3 to T ₃ −RTT ₀₁ are NE # 1. (Step S23). Step S23 corresponds to a path setting information notification step and a path setting information receiving step.

Further, NE # 0 (MN) is a NE # control signal to set the time t to T ₁ -RTT ₀₂ for the Add / Drop operation with respect to TS # 1 in _{2 (T 1 -RTT 02 (Add} / Drop)) , By transmitting a control signal (T ₂ -RTT ₀₂ (Add)) for setting the time t at which the Add operation is performed on TS # 2 to T ₂ -RTT ₀₂ to NE # 2, thereby setting a path to NE # 2. (Step S24).

Further, NE # 0 (MN) includes a control signal to set the time t to T ₁ -RTT ₀₃ for the Add / Drop operation with respect to TS # 1 in _{NE # 3 (T 1 -RTT 03} (Add / Drop)) , By transmitting a control signal (T ₃ -RTT ₀₃ (Add)) for setting the time t at which the Add operation is performed on TS # 3 to T ₃ -RTT ₀₃ to NE # 3, thereby setting the path to NE # 3. (Step S25).

Further, NE # 0 (MN), the control signal to set the time t to the Add operation to T ₁ -RTT ₀₄ with respect to TS # 1 in _{NE # 4 (T 1 -RTT 04} (Add)) to NE # 4 By transmitting, the path is set to NE # 4 (step S26). These steps S23 to S26 correspond to a path setting information notification step and a path setting information receiving step. Note that the path setting process may be executed in the order far from NE # 0 (MN) (in the order of steps S26, S25, S24, and S23).

With this setting, when the time of NE # 4 is (T ₁ −RTT ₀₄ ), NE # 4 transmits the main signal of TS # 1 of the predetermined wavelength. when the Add operation to, as shown in FIG. 11 (e), when the time of the NE # 3 is (T ₁ -RTT _03), with NE # 3 to Drop data from NE # 4, NE # 3 performs an Add operation on the main signal.
Then, NE # 2, when the time of the NE # 2 is (T ₁ -RTT _02), while Drop data from NE # 3, NE # 2 is the Add operation to the main signal.
Then, NE # 1, when the time of the NE # 1 is (T ₁ -RTT _01), while Drop data from NE # 2, NE # 1 to the Add operation to the main signal.
And, NE # 0 is, the time T ₁ of NE # 0, to Drop the data from the NE # 1.

Also, if you set in this way, for the TS # 2 of the same wavelength, when the time of the NE # 2 is _{(T 2 -RTT 02), NE} # 2 is TS # for the second data to the main signal When the Add operation, as shown in FIG. 11 (e), at time T ₂ of the NE # 0, NE # 0 to Drop data from NE # 2.

Further, if the setting is made in this way, for the TS # 3 of the same wavelength, when the time of the NE # 3 is (T ₃ -RTT ₀₃ ), the NE # 3 transmits the data of the TS # 3 to the main signal. 11A, the NE # 2 transmits (through) data when the time of the NE # 2 is (T ₃ −RTT ₀₂ ), and the NE # 1 transmits the NE # 1 as shown in FIG. # 1 when time is of (T ₃ -RTT _01), to Drop the data from the NE # 3.

  According to the present embodiment, in the optical ring network system, the master node (MN) sets the time with each slave node (SN), and then, based on the path information of the path to be set, In the master node and each slave node, time setting information specifying the Add / Drop time for each time slot on the same wavelength and path setting information including the time slot time are set. Thereby, one time slot can be used with a time difference by a plurality of paths. Therefore, a path can be configured between arbitrary nodes sharing the same wavelength on the ring.

  Further, according to the present embodiment, Add / Drop time setting for downlink traffic and Drop time setting for uplink traffic, which were impossible with the current PON, can be performed, and a low-cost optical TDM configuration is realized. be able to. Furthermore, by configuring a TS for each path on the same wavelength, wavelength resources can be effectively used, and power saving can be achieved by configuring path handling in the optical layer instead of path editing and multiplexing at the electrical level. I can do it.

The present invention is not limited to the above embodiments, and various modifications are possible.
Moreover, you may deform | transform as follows. For example, the number of slave nodes (SN) is not limited to the four illustrated.
Although the ring NW has been described as a double ring, a single ring may be used. Further, the present invention can be applied to a multi-ring system having a layered structure having an upper ring and a lower ring.

  In the above-described embodiment, a burst signal on a single wavelength signal transmitted through an optical fiber constituting a ring has been described. However, the present invention relates to a parallel transmission method used in a future 400 Gbps / 1 Tbps class transmission method. It is applicable also in.

  As the burst receiver (burst receiving unit 141) in the MN 100 and the SN 200, in addition to the optical module configuration employed in the current PON system, it is also possible to configure a burst receiver on a digital coherent receiver. For example, a digital coherent receiver for a polarization multiplexing quaternary phase modulation (DP-QPSK: Dual Polarization-Quadrature Phase Shift Keying) system may be used.

1 Optical ring network system 100 MN (master node)
110 optical switch 120, 130 optical coupler 140 burst signal processing section 141 burst receiving section 142 header analyzing section 143 switch section 144 IF transmitting section 145 IF receiving section 146 switch section 147 buffer 148 burst transmitting section 150, 250 memory 160, 260 time synchronization Function unit 170, 270 Path setting processing unit 171 Path information obtaining unit 172 Path setting information generating unit 173, 272 Path setting information updating unit 174 Path setting information notifying unit 180, 280 Timing control unit 200 SN (slave node)
271 Path setting information receiving means R ring NE Network element (network device)

Claims (5)

An optical ring network system in which a master node serving as a control subject and a plurality of slave nodes serving as objects with respect to the control subject are annularly connected by a double ring that enables bidirectional communication of an optical transmission path. ,
The master node,
A time synchronization function unit for performing time synchronization with each slave node,
Based on the path information of the path to be set in the ring, the master node and each slave node provide time information specifying Add / Drop time for each time slot on the same wavelength and path setting information including a time slot time. A path setting processing unit to be set;
An optical switch that transmits or blocks a main signal that conducts the ring,
A timing control unit that performs Add / Drop control on a main signal by the optical switch based on the time set in the path setting information;
The slave node comprises:
A storage unit for holding path setting information set by the master node,
An optical switch that transmits or blocks a main signal that conducts the ring,
A timing control unit that performs Add / Drop control on a main signal by the optical switch based on the time set in the path setting information ;
The time synchronization function unit, between the slave node of the communication target, further calculates the round trip time by the round trip signal transmission of the communication path from the master node to the slave node,
The path setting processing unit passes an optical transmission path by a ring capable of communicating in a first direction from a master node or an optical transmission path by a ring capable of communicating in a second direction opposite to the first direction from the master node. In the round-trip signal transmission, the path setting information generated for the slave node with respect to the upstream traffic, which is the traffic going to the master node in the same direction as the return path for transmitting the control signal addressed to the master node from the slave node, includes Add / Drop. An optical ring network system for designating a time obtained by subtracting the round-trip time from a reception time at the master node as an operation time . The path setting processing unit,
Constitute the time slots for each specified path on the same wavelength, the path setting information for the downlink traffic and the uplink traffic in the opposite direction to the uplink traffic to the master node and each slave node Path setting information generating means for generating
Path setting information updating means for setting the path setting information generated for the master node in the storage unit;
The optical ring network system according to claim 1, further comprising: a path setting information notifying unit that notifies a control signal including the path setting information generated for the slave node to a slave node to be communicated. Master node in an optical ring network system in which a master node serving as a control subject and a plurality of slave nodes serving as objects with respect to the control subject are connected in a ring with a double ring that enables bidirectional communication of an optical transmission path. And
A time synchronization function unit for performing time synchronization with each slave node,
Based on the path information of the path to be set in the ring, the master node and each slave node provide time information specifying Add / Drop time for each time slot on the same wavelength and path setting information including a time slot time. A path setting processing unit to be set;
An optical switch that transmits or blocks a main signal that conducts the ring,
A timing control unit that performs Add / Drop control on a main signal by the optical switch based on the time set in the path setting information ;
The time synchronization function unit, between the slave node of the communication target, further calculates the round trip time by the round trip signal transmission of the communication path from the master node to the slave node,
The path setting processing unit passes an optical transmission path by a ring capable of communicating in a first direction from a master node or an optical transmission path by a ring capable of communicating in a second direction opposite to the first direction from the master node. In the round-trip signal transmission, the path setting information generated for the slave node with respect to the upstream traffic, which is the traffic going to the master node in the same direction as the return path for transmitting the control signal addressed to the master node from the slave node, includes Add / Drop. A master node, wherein a time obtained by subtracting the round-trip time from a reception time at the master node is specified as an operation time . The path setting processing unit,
  The time slot is configured for each path specified on the same wavelength, and the path setting information for the downstream traffic and the upstream traffic opposite to the upstream traffic is transmitted to the master node and the slave nodes. Path setting information generating means for generating
Path setting information updating means for setting the path setting information generated for the master node in the storage unit;
4. The master node according to claim 3, further comprising: a path setting information notification unit configured to notify a communication target slave node of a control signal including the path setting information generated for the slave node. 5. A master node to be controlled mainly multiple slave nodes and the path in the optical ring network system connected to the annular double ring that enables two-way communication optical transmission line as the object with respect to the control entity A control method,
By the master node,
A time synchronization step for adjusting the time with each slave node;
Based on the path information of the path to be set in the ring, the master node and each slave node provide time information specifying Add / Drop time for each time slot on the same wavelength and path setting information including a time slot time. A path setting information generating step to be set;
A path setting information notifying step of notifying a control signal including the path setting information generated for the slave node to a slave node to be communicated,
By the slave node,
Path setting information receiving step of receiving path setting information, notified by the control signal from the master node,
Look including a path setting information updating step of setting the path setting information thus received in the storage unit,
The master node,
Subsequent to the time synchronization step, between the slave node to be communicated with, the round-trip time by the round-trip signal transmission of the communication path from the master node to the slave node is further calculated,
In the path setting information generation step, an optical transmission path by a ring communicable from a master node in a first direction or an optical transmission path by a ring communicable from a master node in a second direction opposite to the first direction, In the round-trip signal transmission, the path setting information generated for the slave node with respect to the upstream traffic that is the traffic toward the master node in the same direction as the return path for transmitting the control signal addressed to the master node from the slave node includes Add / A path control method, wherein a time obtained by subtracting the round trip time from a reception time at the master node is specified as a time at which the Drop operation is performed .

Images