JPH07507188A - optical processing system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] optical processing system FIELD OF THE INVENTION The present invention relates to optical processing systems, and in particular to packet switching networks. Regarding optical header recognition in

In a communications network switch circuit, the physical circuit is is formed between two terminals. Regarding certain forms of traffic such as speech , the information sent does not completely fill the connection between the two terminals. i.e. information The beginning of the information does not reach the destination terminal before the end of the information leaves the sending terminal, but there are two circuits. is kept open for the duration of the transmission of information between the terminals. digital data For high-speed circuits that carry This is possible by sharing the route. This is the packet switching network. is one way to achieve improved resource utilization of data in packets. transmitted through the network. Besides the data itself, each packet has an address and sequence (control) information that controls the progress of packets through the network. Contains a header containing. address encoded in the packet header and sequence information to perform routing control. data on the network node to coded. A packet switching network creates a virtual circuit between two terminals. A known method for encoding packet headers used as a permanent connection between terminals. The method relies on time correlation techniques. The use of packet switching networks is related to cut speed. Moreover, its usage is related to the ratio of data time to wasted time. Dependent. i.e. the time the network is transmitting data and the time the data is being transmitted (occupies separate time slots at the head of the packet's data) This is the time of the packet header), and the guard band area separates adjacent packets and avoids packet duplication due to dispersion during transmission. That is the most important thing.

It is an object of the present invention to provide a packet-switching network which increases the utilization of networks. Provides alternative techniques for encoding and decoding header information in networks That's true.

The invention provides first and second nodes interconnected by a network transmission line. a first node, the first node transmits an optical device at a first wavelength; an optical data generator that generates a data signal and an optical control (header) signal at a second wavelength; an optical header generator with a control signal period at least equal to the data signal period; means for multiplexing data and control signals onto a transmission line in such a manner as to Provide sufficient delay between the start time of transmitting the control signal and the start time of transmitting the data signal. associated with a delay device so that when the control signal arrives at the second node, it is completely connected to the data signal. and a delay device and control means for ensuring that the second node overlaps with the second node. , responds to the signal at a second wavelength to control the routing of the optical signal through the switch. It is equipped with a switch and control device.

When a control signal overlaps a data signal, the two signals occupy the same time slot. Ru.

The optical data generator generates the optical data signal in the packet, and the optical data generator generates the optical data generator in the packet. preferably constituted by a laser and a modulator that modulates the output of the laser. . The header generator consists of a laser.

The system turns on the header laser at or just before the start of a data packet. Switch the header laser to stop the header laser at or immediately after the end of a data packet. A modulator is provided to modulate the data laser.

The control device of the second node includes a splitter that demultiplexes a portion of the control signal; and a narrow bandpass filter centered at a second wavelength, the output of the filter being is used to control the operation of the switch. The amplifier consists of a splitter and a filter. It is located in between.

The switch is an optical switch such as NLOA. Instead, the switch is photoelectric It is a child switch. In either case, the switch has two outputs. one to the network transmission line and the other to the receiver.

Preferably, a narrow band filter is located between the switch and the receiver; The filter band is centered around the first wavelength.

Preferably, there is a plurality of second nodes, each of which has a network transmission line. an optical data generator and an optical header generator of the first node; provides data and control signals at different predetermined wavelengths to each second node. can be tuned to provide

In a preferred embodiment, each second node transmits data and control signals to a transmission line. A module is provided to supply the input. Each module an optical data generator for generating a first data signal at a predetermined wavelength; and a second predetermined wavelength. an optical header generator that generates an optical control signal at a selected wavelength, and on the transmission line. and means for multiplexing the data signal and control signal.

Each module has a storage device that stores data waiting to be transmitted, and a control that determines the appropriate first and second predetermined wavelengths to be delivered to the specified destination; Preferably, control means and a lookup table are provided.

The optical data generator, optical header generator and first node multiplexing means are modules. the module is provided with a storage device for storing data awaiting transmission; Determine the appropriate control and data signal wavelengths to be delivered to the signal's destination node. Control means and lookup tables are provided. In this case, the first node is a switch A switch or switch that responds to a signal at a predetermined wavelength controls the path of an optical signal through the and a controller for demultiplexing a portion of the input control signal. a narrow bandpass filter centered at said predetermined wavelength; The output of the filter is used to control the operation of the switch.

Each delay device has a sufficient delay between the start of transmission of the control signal and the start of transmission of the data signal. It is related to the control means that gives the delay and the lookup table of each module, and the control guarantees complete overlap with the data signal when it arrives at the card.

The module accommodates changes in the effective optical path length of the inter-node network transmission line. Additional control means are provided to adjust the lookup table to compensate. Each module Additional control means of the tool may be constituted by the first and second processing means. Preferably, the first processing means monitors the input control signal and determines the optical path length information obtained therefrom. is effective for feeding back the information to the node transmitting the control signal, and the processing means are dependent on the optical path length information received from the first processing means of another module. The module updates the search table by updating the search table. of each module The first processing means is a local processor associated with the control means of the module; The processing means are constituted by a local processor associated with the lookup table of the module. There is. Additionally, the system includes a central management unit that controls the local processors. It's okay.

The invention will be explained in detail by way of example with reference to the accompanying drawings, in which: FIG.

FIG. 1 is a schematic diagram of a wavelength ladder encoding/decoding device constructed according to the present invention. is a diagram, FIG. 2 is a schematic diagram of one form of a destination switch used in the apparatus of FIG. 1; (a) to (d) of FIG. 3 show the optical signal characteristics of the optical switch of FIG. 2, Figure 4 shows a simple ring network comprising equipment of the type shown in Figure 1. A schematic diagram, FIG. 5 is a schematic diagram of a star network equipped with equipment of the type shown in FIG. and FIG. 6 shows an overview of a ring/star network with equipment of the type shown in FIG. It is a schematic diagram, Figure 7 illustrates the wavelength routing network used by the networks of Figures 5 and 6. 1 is a schematic diagram of a cross-connect switch; FIG.

According to the drawing, Figure 1 shows one node of a fiber network to which packets are switched. node 1, whose network includes multiple similar nodes. node 1 are connected to the network via input and output fibers 2 and 3, respectively. It will be done. The input fiber 2 was equipped with an optical data generator 4 and a header generator 5 Connected to a head end station (not shown in detail). The optical data generator 4 is Laser (not shown) at 2.5 gigabits per second and a wavelength of 1.55 μm By modulating the Generate a data packet. The header generator 5 supports data packets with a length of 16 bits. with a corresponding effective speed of 155 megabits per second and a wavelength of e.g. 1.3 μm. header (control) signal by modulating a second laser (not shown) (one of which is indicated at 58). This modulation is performed by the header generator 5. The laser is switched on at or just before the start of data packet 4a and selected to be switched off at or immediately after the end of a data packet. system The control signal wavelength is selected to match the receiving wavelength of node 1, and the header generator 5 Tunable to provide control signals at different wavelengths, each wavelength connected to the network Match the receiving wavelength of the node. The two signals 4a and 5a are sent to the WDM coupler 6. Therefore, it is superimposed on the fiber 2.

Node 1 adds data to the network and drops data from the network 4 It includes a port optical switch 8. Switches 8 have first and second input ports, respectively. 9a and 9b, the first input port connects the input fiber through the splitter 7. 2, and the second input port is connected to the data addition module -10 (details below). ). Switches 8 have respective first and second outputs. port) 11a and llb, the first output port is connected to the output fiber 3. The second output port receives 2.5 gigabits per second through a bandpass filter 13. It is connected to machine 12.

The splitter 7 demultiplexes a part (usually several percent) of the control signal 5a of the input packet. This branched signal is passed through a 1.3 μm optical amplifier 15 to a bandpass filter 14. supply the signal. Since the filter 14 has a narrow band centered at 1.3 μm, , the branched signal is supplied with a wavelength of the branched signal that matches the wavelength of the band of the filter. pass the issue. The output of the filter 14 is supplied to the control board 16 of the optical switch 8. , thereby opening the switch and connecting the first input port 9a to the second output port l. Connect to lb. In this method, data packets destined for node 1 are receiver]2. The control signal 5a becomes the data signal 4a in the packet. When duplicating, switch 8 selects when or just before the beginning of the data reaches the switch. It is opened and closed when or immediately after the end of the data exits the switch. Therefore Therefore, the control signal supplied to the control boat 16 is at least the same as the data packet. It has a duration. The filter 13 has a wavelength of 1°55 μm (data wavelength) as its center. Because it has such a narrow band, the only signals that reach receiver 12 are data signals.

The filter 13 not only filters out the remaining control signal 5a, but also filters out noise. Remove. If the wavelength of the branched signal does not match the wavelength of the band of the filter 14, The filter has no output signal, the first switch 8 remains closed, and its first input The output port 9a is connected to its first output port Ila. In this method, Data/control packets related to the branched signal are routed through node 1 to the output fiber. 3 and network.

Switch 8 may be an all-optical switch such as a non-linear output amplifier (NLOA). is preferable. Instead, the switch is an optoelectronic device such as lithium niobate , the optoelectronic converter 17 (shown in dashed lines) in that case is the filter 14 and the control board 16 of the switch 8. Converter 17 has equivalent processing capacity A large enough electronic signal is input to control the switch 8. It is necessary to perform a certain amount of amplification to ensure that readily available This type of simple optoelectronic The part is capable of producing switch rise and fall times shorter than ins. Wear.

The module IO of node 1 has the packet (header address decoder described above) when dropped by a node (triggered by ) or (triggered by protocols (such as token-ring protocols) are controlled and correct network protocols. If you allow input on an empty line when ensuring network access, Data packets can be added on top. Data for transmission in this method The packets are held in a storage device 18 provided to module IO. Sara In addition, module 10 includes an optical header generator 20 and a data generator 21 . occurrence devices 20 and 21 transmit data at one of a plurality of predetermined wavelengths; is tunable to transmit control signals at one of different wavelengths. Each search table 22 and 23 relate to data and header generators 20 and 21 respectively, so , the wavelength of both data and control signals for the requested purpose of a given packet. is supplied accurately. If variance is a potential problem, lookup tables 22 and 23 are calculating the difference between the transmission times of the control signal and the data signal so selected; a delay that provides a suitable delay between the transmission start times of control and data signals. The device 24 can be commanded so that the control signal 5a is transmitted to the destination node. The optical switch 8 guides the entire data signal and completely overlaps the data signal 4a. guarantee that no cuts are lost. Loss of data bits causes errors and degrade network performance due to

In addition, the header end station includes storage, look-up tables and delay devices (parts of module IO). 18.22.23 and 24), so the data for transmission is for sending to any given node of the network. Data and header wavelengths are determined and appropriate delays are applied to the header to reduce dispersion problems. The transmission in the header and data signals takes place within the storage time. i.e. head end The department includes a data addition module of the same type as provided in node 1.

In addition, the wavelengths of the control and data signals appropriate to each node can be set, e.g. Node 1 (and network filters 13 and 14 tunable to other similar nodes connected to the It is also possible to provide In this case, the head end station is It can be the same as node 1.

The effective optical path of a network link caused by environmental changes such as temperature Due to the change in , the delay between any pair of nodes changes. This change Due to the control signal 5a moving in relation to the signal 4a, there is no loss of information at the destination node 1. arise. This change in optical path length is likely to occur on a time scale smaller than the <kHz level. occurs in the rules. All optical path lengths are known and the network is “synchronous” (all optical path lengths are known). In other words, the state in which the control signal 5a overlaps with the data signal 4a at node 1 is Feedback information between nodes monitors optical path length to ensure that However, it is necessary to adjust lookup tables 22 and 23 accordingly. This fee The back signal is achieved by monitoring the arrival of control signal 5a at node 1. It will be done.

In this way, the network (by monitoring the nodes where signals arrive) ) knows where the information is coming from, and the predetermined control signal 5a enters the node. When monitoring relative times to come, any differences in path delays are monitored. Figure 1 As shown in FIG. The search tables 22 and 23 of the node 1 are provided, and each node is stored in another local processor 14a. This is achieved by branching a part of the output signal of one filter 14. Destination Processor 14a of node 1 determines what happens to the network and takes appropriate steps. How to send update control signals through the network to all other nodes This indicates whether to update the search tables 22 and 23. These update signals are via a central management unit supplied to the end stations, or perhaps to a sub-station of Node 1. and other central management devices. The need to have a central management device , the total processing time of local Bromo Tussa 22a, 23a and 14a is remains “stable” and that the update control signal is in a normal state (or the network after it has naturally recovered (responsive to the previous signal). whether it is sufficient to ensure that the change does not cause problems; Dependent. In other words, the time taken to adjust the network is at most should be equal to the time constant of the perturbation effect.

The local bromo nosas 22a and 23a at each sending node 1 are connected to the network. receive update control information from each other node in the Process this to correct 2 and 23 exactly. In this way, (head end The search tables 22 and 23 of all nodes 1 (including departments) compensate for environmental changes. Continuously updated to compensate. The local management processors 22a and 23a are Instruct how to improve the lookup table. It therefore follows that processors 22a and 23 a has multiple interactions to implement the best solution for the network as a whole. Ideal when examining dependent signals, where information traverses the path to a given purpose Cover all links. Therefore, the required capacity is It is related to the number of nodes 1.

The feasibility of the encoding/decoding device described above with reference to FIG. 8) using the configuration shown in Figure 2. It was tested experimentally using Approximately 1.55μm (1,535μm to 1.56μm The data signal 4a with a wavelength of It is modulated by /s. The control signal 5a is 10 at a data bit rate of 1716. It was a DFB laser output of 1.31 μm modulated in 10 patterns. these Signal 4a s 5a is the bulk material NLO based on standard bias conditions The light was incident on the absorber facet 8a of A8. Improved characteristics absorber bias occurred when the amount was reduced. The output from NLOA8 is bandpass filtered at the data wavelength. 13 was used. A typical gated data signal is shown in Figure 3 (a ) to (d). These results are related to IG B/s data. However, equivalent configurations are seen at speeds of 2.5 Gb/s. 5 G b NLOAs running at speeds of /s or higher have been announced, and further speed improvements are expected. It is expected to optimize the location.

Operation in two modes (resonant amplifier and injection lock) is described. Resonance increase The results for the breadth mode are shown in Figures 3(a) and (b), and for the injection lock case. The results for both modes are shown in FIGS. 3C and 3D. Regarding both cases The measured attenuation factor of the gated data signal and the rejected data signal is The EYE diagram shows a clean aperture and a good This indicates that the error rate characteristics are expected. Contrast ratio (off relative to 0) The on-level power (relative to level power) was 10 dB or more. resonant amplifier The gate rise and fall for the case are ~25ns, and the NLOA It depends on the detuning of the data wavelength from the Apley-Perot mode. ~10GHz The detuning range is related to the network configuration to ensure good performance. There was a possibility that a length was required.

In injection lock mode (NLOA or threshold), rising and falling Although the time is shorter than the bit period (400 ps), the network with fast gate control time The advantages are balanced by very difficult detuning requirements, sufficient operation is approximately It is possible to obtain data over a wavelength range of Hz.

The techniques described above can be used in packet, virtual and circuit systems. . It maintains a transparent data channel (packet duration, requested rise specific bit rate information (such as fall time, fall time, etc.) at different wavelengths. feeds the control channel. The principle of the invention is that the data bit rate is r-frame systems such as Synchronized Digital Hierarchy (SDH) and high-speed Used in circuit switch networks. The technology is LAN, MAN and WA used in distribution applications for data communication networks in N environments, The general principle can also be used in trunk applications when configured correctly.

The technique includes rings, stars and can be used in star/ring configurations. In other words, Figure 4 is simple. The wavelength header encoding/decoding technology of the present invention in a ring network is One possible configuration in use is shown. This network consists of the nodes in Figure 1. It includes four nodes 31, each of which is similar. Node 31 is trunk spar 3 2 in a ring configuration. Each node 31 has a trunk spar 32 different address wavelengths λ1, λ2, λ3 and matching the control signal wavelength input by and λ4. Therefore, the filters 41 of the nodes 31 are clearly different and each It has a narrow band centered on the appropriate address wavelengths λ11λ2, λ3 and λ4. ing.

Data from the network is transferred to Trunk Spur 32 and ) enters the ring via the trunk multiplexer 33 and connects the ring to each node 31. It goes around and gets transmitted. The information on the line is interrogated at each node 31 for any given packet. When the control signal 5a of the node matches the address wavelength of the node, the data leaves the ring. Local data that is guided and ready for transmission to the network is appended to that location. can be done. As with the embodiment of FIG. Add/drop functionality exists on both wavelengths. Data circulating in the ring is multiplexed back onto the trunk spar 32 after being completely transmitted around the ring. be done. Therefore, this type of configuration is a network for the transfer of control information between nodes. Effective for workpiece signals.

Information flowing into and out of the ring is In this case, the wavelengths or bit rates need not be the same. For example, trunknet If the work is a wavelength routing network (of data wavelengths), the information to the outside is transmitted on an available network wavelength. Therefore, the control signal wavelength is It is possible with a value that matches well. Figure 4 shows only four nodes 31 on the ring. However, the principle extends to virtually any number of nodes, the number of which can be controlled over a wavelength range, filter bandwidth, the bandwidth of wavelength routing cross-connects in the network, and determined by factors such as arbitrary dispersion problems. As mentioned above, each node 31 contains an amplifier that amplifies the branched signal, so a very low percentage of the input signal needs to be branched and multiple nodes can be combined.

FIG. 5 shows five rings, each similar to the ring described above with reference to FIG. 4 shows a star network having a ring 40. Each ring 40 is a node of FIG. It includes four nodes 41, each similar to 1. Each ring 4o has a It is connected to a wavelength routing cross-connect 43 via a wavelength routing cross-connect 43 . each trunk spa -42 is each data wavelength λ, λ, λdrlxl dslt2 dtta 3 and λdgfa4.

Each node 41 of each ring 40 receives a header wavelength input via a trunk spar 42. They have matching different address wavelengths λ to S2o. Also, the file of node 41 The routers 4 are different, each centered around an appropriate address wavelength λ to λ2o. It has a narrow band.

Wavelength routing cross-connects 43 interconnecting the five rings 40 are connected to Ensures that the linked data is being routed along the same valid path. This cross-connection 43 is shown in detail in FIG. 7 and includes control and data fields. have the same interconnect for both fields, and any switch in these fields tings are driven at the same time. Send data to another node 41 in the network The desired node 41 has a precise data wavelength (e.g. λ) and a precise control signal wavelength. (For example, also λ2) is selected. Cross-connect 43 conducts a control signal band rather than a single wavelength. Rather than guiding each of these wavelengths separately, the A band of λ4 is derived.

This principle is used to guide the outgoing wavelengths, increasing the capacity of the network.

FIG. 6 shows a star ring configuration having five rings 50, each ring shown in FIG. 4 nodes 51, respectively, which are similar to the nodes in . Each ring 50 has a Connects to inner ring 54 via rank spur 52 and wavelength routing cross-connect 53. It is continued. The trunk spar 52 further leads to a central wavelength routing cross-connect 55. and data dxtAl dstt5 at each data wavelength λ to λ, respectively. is configured to carry light. Each node 51 of each ring 50 has a trunk Different address wavelengths λ to λ matched with control signal wavelength input by spur 52 It has 2o. Also, the filters 4 of the nodes 51 are different, and each It has a narrow band centered on an appropriate address wavelength λ to λ2o. wavelength path finger Constant cross-connects 53 and 55 are similar to those shown in FIG. This ensures that the connected data is routed along the same valid path.

Cross-connections 43.53 and 55 for conflict resolution or rerouting Any switching required in the arrival control signal 5a It requires complete overlap in time with the data signal 4a. This duplication is Must occur only within the switching window. Transmission node search tables 22 and 2 3 controls need to be considered when setting up transmission. Therefore, the network and the complexity of wavelength selection. This is especially true when a packet is sent to the sending node. This is the case where the destination nodes are guided by one or more cross-connections between them; The connection is such that the optical switch in the control cross-connect is non-contact with respect to the optical switch in the data cross-connect. Although not required when operated synchronously, control signals and It is of utmost importance to ensure redundancy of the data signals.

Controller bias -95°10Ith Country WAwIi investigation report Continuation of front page (51) Int, C1,6 identification code Internal office reference number HO4J 14102 HO4M 3100A 7406-5KHO4Q 11102 9076-5 9372-5K I HO489100E

Claims (24)

[Claims] 1. a first and a second node interconnected by a network transmission line; A communication system comprising: a first node transmitting optical data at a first wavelength; an optical data generator that generates a signal at a second wavelength and an optical control (header) signal at a second wavelength; The optical header generator is configured such that the period of the control signal is at least equal to the period of the data signal. means for multiplexing data and control signals onto a transmission line in a manner that a delay that provides a sufficient delay between the start time of transmission of the signal and the start time of transmission of the data signal. the data signal and the control signal when the control signal arrives at the second node. a delay device and control means to ensure complete overlap; A second node provides a signal at a second wavelength for controlling the path of the optical signal through the switch. A communications system that includes switches and controls that respond to signals. 2. The system of claim 1, wherein the optical data generator generates the optical data signal in packets. Mu. 3. The optical data generator consists of a laser and a modulator that modulates the output of the laser. The system according to claim 1 or 2, wherein the system comprises: 4. Any one of claims 1 to 3, wherein the header generator is constituted by a laser. System described in section. 5. Switch on the header laser at or just before the start of a data packet; To switch off the header laser at or immediately after the end of a data packet Claim 4 dependent on claim 2, further comprising a modulator for modulating the header laser. The system described. 6. The controller of the second node demultiplexes a portion of the control signal. and a narrow bandpass filter centered at a second wavelength, such that the output of the filter is Any one of claims 1 to 5, wherein the method is used to control the operation of a switch. The system described. 7. Claim 6, further comprising an amplifier located between the splitter and the filter. system. 8. The system according to any one of claims 1 to 7, wherein the switch is an optical switch. . 9. 9. The system of claim 8, wherein the optical switch is an NLOA. 10. The system according to any one of claims 1 to 7, wherein the switch is an optoelectronic switch. stem. 11. The switch has two outputs, one of which leads to the network transmission line. 11. A system according to any one of claims 1 to 10, wherein one Mu. 12. A narrowband filter located between the switch and the receiver and centered on the first wavelength. 12. The system of claim 11, further comprising: a computer. 13. a plurality of second nodes interconnected by network transmission lines; exists, and the optical data generator and optical header generator of the first node are predetermined. tunable to provide data and control signals at different wavelengths to each second node. 13. A system according to any one of claims 1 to 12, wherein the system is capable of: 14. Each second node is a module that provides data and control signals to the transmission line. 14. A system according to any one of claims 1 to 13, further comprising: a. 15. an optical device in which each module generates an optical data signal at a first predetermined wavelength; an optical header generator that generates an optical control signal at a second predetermined wavelength; and means for multiplexing said data and control signals onto a transmission line. 15. The system of claim 14. 16. A claim in which each module has a storage device for storing data awaiting transmission. The system according to item 15. 17. Each module connects the appropriate first or and a second predetermined wavelength. A system according to claim 15 or 16. 18. The optical data generator, optical header generator and multiplexing means of the first node are a storage device provided in the module for storing data that the module is waiting to transmit; control means and look-up tables are provided for the appropriate destination node of the signal to be injected. 18. The method according to claim 13, wherein the wavelength of the control and data signals is determined. system. 19. The first node controls the path of the optical signal through the switch. a switch and a control device responsive to an input control signal; a splitter to demultiplex a portion of the signal and a splitter to demultiplex the predetermined wavelength; The output of the filter controls the operation of the switch. 20. The system of claim 18, wherein the system is used for: 20. Provide sufficient delay between control and data signal transmission start times to to ensure complete overlap with the data signal when the signal arrives at the destination node. control means and each delay device associated with the lookup table of each module. A system according to any one of claims 17 to 19. 21. The module provides additional controls to adjust the lookup table and Claims 18 to 2 compensate for changes in effective optical path length of the network transmission line. 0. The system according to any one of 0. 22. Additional control means for each module are configured by first and second processing means. the first processing means monitors the input control signal and the optical path length information obtained therefrom; is effective for feeding back the control signal to the node transmitting the control signal, and the second a processing means relates to a lookup table of a module, and from a first processing means of another module; The system according to claim 21, wherein the search table is updated depending on the obtained optical path length information. . 23. The first processing means of each module is a local program associated with the control means of the module. processor, and the second processing means is a local processor associated with the module's lookup table. 23. The system of claim 22, wherein the system is configured by a server. 24. Claim 23 comprising a central management device for controlling the local processors. The system described.