JPH04369143A - Packet switch - Google Patents

Abstract

PURPOSE:To relax a limit to a wavelength revision speed and to allow the switch to cope with a high speed line speed by arranging plural variable wavelength electrooptic converters corresponding to each incoming line and starting wavelength revision in advance according to each reservation table. CONSTITUTION:Input buffers 111-11N storing a packet inputted from each incoming line inform an outgoing line number of each packet to a control section 14. The control section 14 allocates a time slot to each packet and sets a wavelength of an optical signal to be converted to reservation tables 151-15N. Moreover, the control section 14 controls each of variable wavelength electrooptic converters 121-1-12N-M to vary the wavelength of an optical signal to be converted in response to the content of the tables 151-15N and selects any of the converters 121-1-12N-M for conversion for each time slot. Thus, the revision of wavelength is implemented early prior to the conversion by each of the converters 121-1-12N-M and the wavelength is revised by using a time longer than a time slot.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to an asynchronous transfer mode (A
TM: Asynchronous Transfer
Mode) The present invention relates to a packet switch used in an ultra-high-speed packet switching device that performs switching processing in other high-speed/broadband communication networks. Incidentally, in recent years, ultrahigh-speed packet switching devices are required to have a switching processing capacity of several Gbps per line, and since electrical technology alone has its limits, configurations using optical technology have been proposed.

0002

2. Description of the Related Art FIG. 5 is a block diagram showing an example of the configuration of a packet switch used in a conventional ultra-high speed packet switching device using optical technology. The configuration of the packet switch shown here is based on the document “HYPASS: An Opto
electronic Hybrid Packet-
Switching System” (E. Arthu
rs, M. S. Goodman, H. Kobrinsk
i and m. P. Vecchi, IEEE JSA
C, vol. 6, pp. 1500-1510, 1988
．． ), the portions related to the present invention are simplified and quoted.

In the figure, N incoming lines 501 to 50N
are connected to N input buffers 511 to 51N, respectively. Each input buffer 511 to 51N has a variable wavelength electro-optic converter 521 to 52N, respectively.
An optical coupler/distributor 53 is connected thereto. Each input buffer 511 to 51N and each variable wavelength electro-optic converter 521 to 52N have signal lines 571 to 57N, respectively.
57N and signal lines 581 to 58N, the control unit 54 is connected thereto. The optical coupler/distributor 53 includes N fixed wavelength optical-to-electrical converters 551 to 55N.
The main output lines 561 to 56N are connected.

In such a configuration, N incoming lines 50
Packets input from 1 to 50N are stored in N input buffers 511 to 51N, respectively. The control unit 54 controls each of the input buffers 511 to 51N to take out each input packet at an appropriate time slot that does not cause outbound competition with other input packets. Further, the control unit 54 controls each variable wavelength electro-optical converter 521
~52N, the packets in each time slot are controlled to be converted into optical signals having wavelengths λ1 to λN assigned to the outgoing lines of their destinations. Therefore, the packets taken out from each of the input buffers 511 to 51N are converted into optical signals of wavelengths corresponding to their respective destinations via the variable wavelength electro-optic converters 521 to 52N.

[0005] The optical coupler/distributor 53 includes each variable wavelength electric
All fixed-wavelength optical-to-electrical converters 551 take in and combine optical signals of respective wavelengths from the optical converters 521 to 52N, and are arranged on each output line 561 to 56N.
~55N. Each fixed wavelength optical-to-electrical converter 5
51 to 55N extract only the optical signal of the wavelength assigned to each outgoing line from the inputted optical signals of each wavelength, reproduce the packet, and output it to the outgoing line.

That is, for example, when outputting a packet on the incoming line 501 to the outgoing line 56N, the wavelength set in the variable wavelength electro-optic converter 521 at a predetermined time slot is set to λN. By reproducing the signal into a packet using the fixed wavelength optical-to-electrical converter 55N, exchange processing at the optical level becomes possible.

[0007]

[Problems to be Solved by the Invention] In such a conventional packet switch, the variable wavelength electrical-to-optical converter 52 is required to have a wavelength changing speed that enables outputting optical signals of different wavelengths for each time slot. . By the way, the above AT
In transmission systems such as M, where the packet length is several tens of bytes, the line speed is several Gbps and the time slot length is several tens to hundreds of ns, but it is true that a large wavelength change in such a short period of time is not possible. It is difficult to do so. Therefore, in order to accommodate the line speed, the wavelength tuning range of the variable wavelength electro-optic converter has to be narrowed, and this is a factor that limits the number of incoming and outgoing lines that can be used simultaneously.

Furthermore, with the configuration of the conventional packet switch shown in FIG. 5, it is impossible to simultaneously connect one incoming line and multiple outgoing lines to perform broadcast communication. When a fault occurs in a converter, it is necessary to stop or restrict the use of the corresponding incoming line. The present invention makes it possible to support high-speed line speeds by relaxing the limitations on wavelength change speed, and also enables the use of the incoming line even in the event of a failure of the variable wavelength electrical-to-optical converter. The purpose is to provide a packet switch that can realize the following.

[0009]

[Means for Solving the Problems] The present invention includes an input buffer that stores packets input to a plurality of input lines corresponding to each input line, and an input buffer provided corresponding to the input line to store electrical signals taken out from each of the input buffers. A variable wavelength electrical-to-optical converter that converts packets into optical signals with wavelengths assigned to each outgoing line, and an optical signal output from each variable wavelength electrical-to-optical converter that is simultaneously distributed and output to all outgoing lines. a fixed-wavelength optical-to-electrical converter that is provided corresponding to the outgoing line and converts only the optical signal of the wavelength corresponding to the outgoing line into an electrical signal packet; a control unit that performs control to take out the packet in a predetermined time slot in which competition control is performed on the outgoing line, and sets a wavelength corresponding to the outgoing line of the packet in the variable wavelength electro-optical converter for each time slot; In the packet switch equipped with the above-mentioned packet switch, a plurality of the variable wavelength electrical-to-optical converters are arranged for each input line, and the control section determines which variable wavelength electrical-to-optical converters corresponding to each input line are arranged for each time slot. A reservation table is provided to indicate whether the wavelength should be changed, and according to this reservation table, the wavelength for each time slot is set to the corresponding variable wavelength electrical-to-optical converter. It is characterized by a configuration in which switching is controlled sequentially.

0010

[Operation] The present invention has information on the wavelength that is changed by the variable wavelength electrical-to-optical converter of each incoming line for each time slot in a reservation table, and transmits the information to each time slot to a plurality of variable wavelength electrical-to-optical converters for each incoming line. The wavelength for each time slot is set in advance, and the variable wavelength electro-optic converter used is sequentially switched for each time slot. Therefore, in each variable wavelength electro-optical converter, the wavelength changing operation can be performed prior to the conversion operation, and the wavelength can be changed using a time longer than the time slot.

[0011] Furthermore, each input line has a plurality of variable wavelength electric
Since an optical converter is provided, even if one of the converters fails, the controller controls the variable wavelength electrical-to-optical converter so that it is not used, thereby changing the use of the corresponding incoming line to the other variable wavelength electrical converter. - Can be continued using a light converter. Furthermore, since each incoming line is equipped with multiple variable wavelength electrical-to-optical converters, each variable wavelength electrical-to-optical converter can be set to a different wavelength to correspond to the packets of any time slot. Broadcast connection can be made to the outgoing lines.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, N incoming lines 101 to 10N
are connected to N input buffers 111 to 11N, respectively, and accumulate packets input from each incoming line. Each input buffer 111 to 11N includes M variable wavelength electro-optic converters 121-1 to 121-, respectively.
M, . Each variable wavelength electro-optical converter 121-1 to 12
1-M, . . . , 12N-1 to 12N-M are connected to an optical coupler/distributor 13, which couples optical signals of each wavelength. Each input buffer 111 to 11N and each variable wavelength electro-optic converter 121-1 to 121-M,...,12
Signal lines 181 are connected to N-1 to 12N-M, respectively.
~18N and signal lines 191 to 19N,
A control unit 14 that takes out packets from the input buffer and controls the wavelength converted by the variable wavelength electro-optical converter.
is connected. The control unit 14 is provided with reservation tables 151 to 15N corresponding to each input buffer. The optical coupler/distributor 13 includes N fixed wavelength optical-to-electrical converters 16.
1 to 16N are connected, and wavelengths λ fixedly assigned to corresponding output lines 171 to 17N connected to each
1 to λN are selected and converted into electrical signals (packets).

In such a configuration, each incoming line 101
The input buffers 111 to 11N that accumulate packets input from the packets to 10N notify the control unit 14 of the outgoing line number of each packet via signal lines 181 to 18N. The control unit 14 allocates time slots to each packet so that there is no conflict with other packets on the outgoing line, and accordingly assigns the optical signal to be converted in each time slot to each input buffer. Reservation wavelength table 15
Set to 1 to 15N. Further, the control unit 14 controls each of the variable wavelength electro-optic converters 121-1 to 121-M, ..., 1 according to the contents of the reservation tables 151 to 15N.
The wavelength of the optical signal to be converted into 2N-1 to 12N-M is controlled via signal lines 191 to 19N, and the variable wavelength electro-optic converter that performs the conversion operation is switched for each time slot. Therefore, each input buffer 111 ~
The packets taken out from 11N in each time slot are sent to the outgoing line according to the destination via the variable wavelength electrical-to-optical converters each performing a conversion operation among the M variable wavelength electrical-to-optical converters. It is converted into an optical signal of the corresponding wavelength.

The optical coupler/distributor 13 includes each variable wavelength electric
Optical signals input from the optical converters are taken in, combined, and distributed to all fixed wavelength optical-to-electrical converters 161 to 16N arranged on each output line 171 to 17N. Each fixed wavelength optical-to-electrical converter 161 to 16N extracts only the optical signal of the wavelength assigned to each outgoing line from the inputted optical signal of each wavelength, reproduces the packet, and transmits it to the outgoing line. Output.

[0015] Focusing on one incoming line 10, control of the variable wavelength electro-optical converter 12 using the reservation table 15 in the control unit 14 is performed on the path from the input buffer 11 to the optical coupler/distributor 13. An example will be explained with reference to FIG. Note that although M=3 in FIG. 2, the same holds true for any M. The control unit 14 sets, in the reservation table 15, information on the wavelength at which the input packets accumulated in the input buffer 11 are used in each time slot. Note that, in order to create the reservation table 15, when the control unit 14 allocates time slots, a delay of a predetermined time slot is given in advance.

In the figure, in time slot t, the wavelength λ
5 (e.g., corresponds to the outgoing line 175 in FIG. 1), and in time slot t+1 the wavelength λN
is used, and the wavelength λ1 is used in time slot t+2.
is used. Furthermore, in time slot t, the variable wavelength electro-optical converter 12-1 performs a conversion operation,
Only the converted optical signal is inputted to the optical coupler/distributor 13, and converted to the wavelength according to the setting information of the reservation table 15 without performing any conversion operation in the variable wavelength electrical-to-optical converters 12-2 and 12-3. Make changes. Therefore, in time slot t+1, the variable wavelength electro-optical converter 12-2 has already completed the change to wavelength λN, and immediately
can send out optical signals. Note that in the time slot t+1, the other variable wavelength electro-optic converter 12-
1 and 12-3 change the wavelength according to the setting information of the reservation table 15 without performing a conversion operation.

With this configuration, the reservation table 15
Accordingly, each variable wavelength electro-optical converter 12 can pre-initiate the changing operation to the wavelength used in each time slot, so that the wavelength changing rate of one variable wavelength electro-optical converter 12 is at line speed. Even if the system is slow, it can be handled satisfactorily. Next, the operation of the control section when a failure occurs in the M variable wavelength electro-optical converters corresponding to each input buffer will be described with reference to FIG. 3.

Similarly, in FIG. 3, focusing on one input line 10, an example of control on the path from the input buffer 11 to the optical coupler/distributor 13 will be explained. Also, M=3
However, the same holds true for any M. For ease of explanation, here, as a means for connecting one of the variable wavelength electro-optic converters 12-1 to 12-3 specified by the control unit 14 to the optical coupler/distributor 13, The configuration includes gate switches 31-1 to 31-3.

Now, if a failure occurs in the variable wavelength electrical-to-optical converter 12-2, the control unit 14 is aware of this, so when creating the reservation table 15, the variable wavelength electrical-to-optical converter control is performed so that no time slot is assigned to the device 12-2. That is, the corresponding gate switch 31-2 is closed to prohibit connection to the optical coupler/distributor 13.

Therefore, in time slot t, the variable wavelength electrical-to-optical converter 12-1 performs a conversion operation, and only the optical signal converted therein is input to the optical coupler/distributor 13 via the gate switch 31-1. The variable wavelength electrical-to-optical converter 12-3 does not perform any conversion operation and the reservation table 15 is
Change the wavelength according to the setting information. Further, in time slot t+1, the variable wavelength electro-optical converter 12-3
has already completed the change to wavelength λ1, and can immediately send out an optical signal of wavelength λ1. Note that in the time slot t+1, the variable wavelength electro-optical converter 1
2-1 performs a change to a wavelength according to the setting information of the reservation table 15 without performing a conversion operation.

With this configuration, it is possible to process input packets from the incoming line by using other variable wavelength electro-optic converters 12 except for the variable wavelength electro-optic converter in which a failure has occurred. Next, the operation of the control unit for realizing broadcast communication will be explained with reference to FIG. 4.

Similarly, in FIG. 4, focusing on one incoming line 10, an example of control on the path from the input buffer 11 to the optical coupler/distributor 13 will be described. Also, M=3
However, the same holds true for any M. Here, too, for ease of explanation, as a means for connecting one of the variable wavelength electro-optical converters 12-1 to 12-3 specified by the control unit 14 to the optical coupler/distributor 13, The configuration includes gate switches 31-1 to 31-3.

Now, it is assumed that a packet taken out from the input buffer 11 is broadcast-connected to three outgoing lines to which wavelengths λ1, λ5, and λN are assigned. In the control unit 14, each of the variable wavelength electro-optical converters 12-1 to 12-3 converts wavelengths λ1, λ5, λ5,
It is set to a state where it can be converted into an optical signal of λN. In addition, each gate switch 31-1 to 31-3 at time slot t
1-3 each variable wavelength electro-optical converter 12-1 to 12-
3 and the optical coupler/distributor 13 are connected.

With such a configuration, it is possible to realize broadcast communication in which an input packet from one incoming line is output to a plurality of outgoing lines.

[0025]

As explained above, the present invention arranges a plurality of M variable wavelength electro-optic converters corresponding to each incoming line, and starts the wavelength changing operation in advance according to the reservation table for each. It is possible to realize a packet switch that supports a line speed M times faster than the conventional configuration using variable wavelength electro-optic converters. It also shows that even if a variable wavelength electro-optical converter with a wavelength change speed of 1/M of the conventional one is used, it is possible to realize a packet switch that supports the same line speed as the conventional one.

Furthermore, variable wavelength electrical-to-optical converters are provided in a redundant configuration for each incoming line, and simply by disconnecting a faulty variable wavelength electrical-to-optical converter, it is possible to avoid problems with the switching function of that incoming line. Therefore, the fault tolerance as a packet switch can be improved. Also,
By arranging a plurality of M variable wavelength electro-optic converters corresponding to each incoming line, broadcast communication of up to 1 to M can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of controlling a variable wavelength electro-optic converter using a reservation table.

FIG. 3 is a diagram illustrating an example of control when a failure occurs in M variable wavelength electro-optical converters corresponding to each input buffer.

FIG. 4 is a diagram illustrating an example of control for realizing broadcast communication.

FIG. 5 is a block diagram showing a configuration example of a packet switch used in a conventional ultra-high-speed packet switching device using optical technology.

[Explanation of symbols]

10 Incoming line 11 Input buffer 12 Variable wavelength electrical-optical converter 13 Optical coupler/distributor 14 Control section 15. Reserved table 16 Fixed wavelength optical-electrical converter 17 Outgoing line 18, 19 Signal line 50 Incoming line 51 Input buffer 52 Variable wavelength electrical-optical converter 53 Optical coupler/distributor 54 Control section 55 Fixed wavelength optical-to-electrical converter 56 Outgoing line 57, 58 Signal line

Claims (1)

[Claims] 1. An input buffer for accumulating packets input to a plurality of incoming lines corresponding to each incoming line, and an input buffer provided corresponding to the incoming line to allocate electrical signal packets taken out from each of the input buffers to each outgoing line. a variable wavelength electrical-to-optical converter that converts the optical signal into an optical signal with a different wavelength, and an optical coupler/distributor that simultaneously distributes and outputs the optical signal output from each of the variable wavelength electrical-to-optical converters to all outgoing lines; A fixed wavelength optical-to-electrical converter is provided for each of the outgoing lines and converts only the optical signal of the wavelength corresponding to each outgoing line into electrical signal packets, and a fixed wavelength optical-to-electrical converter is provided for each outgoing line, and a fixed wavelength optical-to-electrical converter converts only the optical signal of the wavelength corresponding to each outgoing line into electrical signal packets, and a fixed wavelength optical-to-electrical converter is provided for each of the outgoing lines. and a control section that performs control to take out data in a predetermined controlled time slot and sets a wavelength corresponding to an outgoing line of the packet in the variable wavelength electro-optical converter for each time slot, A plurality of wavelength electrical-to-optical converters are arranged for each incoming line, and the control unit makes a reservation indicating to which wavelength each of the plurality of variable wavelength electrical-to-optical converters corresponding to each incoming line changes for each time slot. A table is provided, and the wavelength for each time slot is set in the corresponding variable wavelength electrical-to-optical converter according to this reservation table, and each variable wavelength electrical-to-optical converter is sequentially switched and controlled for each time slot. A packet switch featuring: