JP2920790B2 - Packet switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an asynchronous transfer mode (A
The present invention relates to a packet switch used in an ultra-high-speed packet switching device for performing switching processing in other high-speed / broadband communication networks. In addition,
In recent years, ultra-high-speed packet switching devices are required to have a switching processing capacity of several Gbps per line, and there is a limit to the use of only electrical technology, so that a configuration using optical technology has been proposed.

[0002]

2. Description of the Related Art 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. The configuration of the packet switch shown here is based on the document “HYPASS: An Optoelectronic Hyb.
rid Packet-Switching System "(E. Arthurs, MSGoodma
n, H.Kobrinski and MPVecchi, IEEE JSAC, vol.6, pp.15
00-1510, 1988.) in a simplified manner.

In the figure, N incoming lines 50₁~ 50_NTo
Is N input buffers 51₁~ 51 _NAre connected
It is. Each input buffer 51₁~ 51_NCan be
Variable wavelength electro-optical converter 52₁~ 52_NVia optical coupling
The distributor 53 is connected. Each input buffer 51₁~ 51
_NAnd each variable wavelength electro-optical converter 52₁~ 52_NTo
Are signal lines 57₁~ 57_NAnd the signal line 58₁
~ 58_NThe control unit 54 is connected via the. Optical coupling / minute
The distributor 53 includes N fixed wavelength optical-electrical converters 55.₁~
55_NThrough N outgoing lines 56₁~ 56_NIs connected
You.

In such a configuration, N incoming lines 50
Packet input from ₁ to 50 _N are respectively accumulated in the N input buffers 51 ₁ to 51 _N. Control unit 54
Controls to the respective input buffer 51 ₁ to 51 _N, take out each of the input packet in the appropriate time slot other input packets and outgoing conflict does not occur.
Further, the control unit 54 controls each of the variable wavelength electro-optical converters 52 _1.
５２52 _N is controlled so that the packet of each time slot is converted into an optical signal having a wavelength λ _{1 to} λ _N assigned to the output line of the destination. Accordingly, the packet taken from the input buffer 51 ₁ to 51 _N, each variable wavelength electro - are converted into light signals of wavelengths according to the respective destinations via the optical transducer 52 ₁ to 52 _N.

[0005] The optical coupler / distributor 53 is provided with a variable wavelength
Bound capture an optical signal of each wavelength from the optical converter 52 ₁ to 52 _N, all of the fixed wavelength light has been arranged in each output line 56 ₁ ~ 56 _N - electrical converter 55 ₁ to 55 _N
Distribute to Each fixed wavelength light-to-electric converter 55 _{1 to} 55 _N
Extracts only the optical signal of the wavelength assigned to each output line from the input optical signals of each wavelength, reproduces the packet, and outputs the packet to the output line.

Namely, for example, in the case of outputting the packets of incoming 50 ₁ to output line 56 _N is variable wavelength electricity predetermined time slot - the wavelength to be set to the optical converter 52 ₁ lambda
With _N, the optical signal of the fixed wavelength light timeslots - by reproduced packet electric transducer 55 _N, it becomes possible exchange process at the optical level.

[0007]

In such a conventional packet switch, the variable wavelength electro-optical converter 52 is required to have a wavelength changing speed that enables the output of an optical signal having a different wavelength for each time slot. . By the way, the above AT
In a transmission system with a packet length of several tens of bytes, such as M, the line speed is several Gbps and the time slot length is several tens ns.
It is practically difficult to change the wavelength in such a short time. Therefore, in order to cope with the line speed, the wavelength tunable range of the variable wavelength electro-optical converter has to be narrowed, which has been a factor limiting the number of input and output lines that can be used simultaneously.

Further, in the configuration of the conventional packet switch shown in FIG. 5, it is impossible to simultaneously connect one incoming line and a plurality of outgoing lines to perform broadcast communication. When a failure occurs in the converter, it is necessary to stop or restrict the use of the corresponding input line. The present invention makes it possible to cope with high-speed line speed by relaxing the limitation of the wavelength change speed, and also to make it possible to use the incoming line in the event of a failure of the variable wavelength electro-optical converter, and further to provide a broadcast connection function. It is an object of the present invention to provide a packet switch that can realize the above.

[0009]

According to the present invention, there is provided an input buffer for accumulating packets input to a plurality of input lines corresponding to each input line, and an input buffer provided for the input line and extracting an electric signal extracted from each of the input buffers. A variable wavelength electro-optical converter for converting a packet into an optical signal of a wavelength assigned to each output line, and an optical signal output from each of the variable wavelength electro-optical converters is simultaneously distributed and output to all output lines. A fixed wavelength optical-to-electrical converter, which is provided for the outgoing line and converts only the optical signal of the wavelength corresponding to the outgoing line into an electric signal packet, and which is stored in each of the input buffers. A control unit for controlling the extraction of a packet in a predetermined time slot in which contention control on the outgoing line is performed, and setting a wavelength corresponding to the outgoing line of the packet to the variable wavelength electro-optical converter for each time slot. A plurality of variable wavelength electro-optical converters are arranged for each incoming line, and the control unit comprises a plurality of variable wavelength electro-optical converters corresponding to each incoming line for each time slot. A reservation table indicating which wavelength is to be changed is provided, and the wavelength for each time slot is set in the corresponding variable wavelength electro-optical converter according to the reservation table, and each variable wavelength electro-optical converter is set for each time slot. Are sequentially switched and controlled.

[0010]

According to the present invention, information on the wavelength to be changed by the variable wavelength electro-optical converter of each incoming line for each time slot is stored in a reservation table, and a plurality of variable wavelength electro-optical converters for each incoming line are assigned to each time slot. The wavelength of each wavelength is set in advance, and the variable wavelength electro-optical converter used for each time slot is sequentially switched. 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.

In addition, a plurality of variable wavelength electric
Since an optical converter is provided, even if a failure occurs in one of the optical wavelength converters, the control unit controls the variable wavelength electrical-optical converter so as not to use the variable wavelength electrical-optical converter, thereby reducing the use of the corresponding input line to another variable wavelength electrical-optical converter. -Can be continued using a light converter.
Furthermore, since a plurality of variable-wavelength electro-optical converters are provided for each incoming line, by setting different wavelengths for each variable-wavelength electro-optical converter, packets in an arbitrary time slot can correspond to those wavelengths. Broadcast connection can be made to the outgoing line.

[0012]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, the N number of incoming lines 10 ₁ to 10 _N, N pieces of the input buffer 11 ₁ to 11 _N are respectively connected, stores the packets input from the incoming line. Each input buffer 11 ₁ ~11 _N, M-number of tunable electrical respectively - optical converter _{12 1-1 ~12 1-M, ...} , 12 N-1 ~
12 _NM is connected, and a packet extracted from each input buffer is assigned to a wavelength λ ₁ assigned to an output line corresponding to each destination.
Converting the optical signal to [lambda] _N. An optical coupler / distributor 13 is connected to each of the variable wavelength electro-optical converters 12 _{1-1 to} 12 _1-M ,..., 12 _{N-1 to} 12 _NM to couple optical signals of each wavelength. Each of the input buffers 11 _{1 to} 11 _N and each of the variable wavelength electro-optical converters 12 _{1-1 to} 12 _1-M ,..., 12 _{N-1 to} 12
_The control unit 14 that takes out a packet from an input buffer and controls a wavelength to be converted by a variable wavelength electro-optical converter via the signal lines 18 ₁ to 18 _N and the signal lines 19 _{1 to} 19 _N respectively. Is connected. The control unit 14, the input buffer corresponding reservation table 15 ₁ to 15 _N
Is provided. N fixed-wavelength optical-to-electrical converters 16 _{1 to} 16 _N are connected to the optical coupler / distributor 13, and the wavelengths λ fixedly assigned to the outgoing lines 17 _{1 to} 17 _N connected to the respective converters 16 _{1 to} 16 _{N. 1} to [lambda] _N by selecting only light signals and converts it into an electric signal (packet).

In such a configuration, each of the incoming lines 10 ₁ to 10 ₁ .
10 the input buffer 11 ₁ to 11 _N for storing packets input from _N, control unit 14 the outgoing number of each packet
Notifying via the signal line 18 ₁ ~ 18 _N to. Control unit 14
Assigns time slots to each packet so that there is no competition with other packets on the outgoing line, and reserves the wavelength of the optical signal to be converted in each time slot for each input buffer corresponding to each input buffer. Tables 15 ₁ to 15 _N are set. Further, the control unit 14 controls the reservation tables 15 ₁ to 15 ₁ .
15 _N according to the content of the variable wavelength electro-optical converter 12
_{1-1 to} 12 _1-M ,..., 12 _{N-1 to} 12 _NM The wavelength of the optical signal to be converted is controlled via the signal lines 19 _{1 to} 19 _N , and the conversion operation is performed for each time slot. Switch the wavelength electro-optical converter. Accordingly, the packet taken out in each time slot from each of the input buffers 11 ₁ to 11 _N, each of M variable wavelength electro - in light converter, variable wavelength electrical doing each conversion - optical transducer Is converted into an optical signal having a wavelength corresponding to the outgoing line according to the destination.

The optical coupler / distributor 13 is connected to each variable wavelength
Bound capture an optical signal input from the optical converter, all the fixed wavelength light has been arranged in each output line 17 ₁ to 17 _N - partitioned electrical converter 16 ₁ ~ 16 _N. The fixed wavelength light - electrical converter 16 ₁ ~ 16 _N, the output from the optical signal of each wavelength, extracts only the respective output optical signals of wavelengths assigned to lines, to reproduce the packet input Output to line.

Here, paying attention to one incoming line 10, in the path from the input buffer 11 to the optical coupler / distributor 13, the control unit 14 controls the variable wavelength electro-optical converter 12 using the reservation table 15. An example will be described with reference to FIG. Although M = 3 in FIG. 2, the same applies to an arbitrary M. The control unit 14 sets information on the wavelength used in each time slot for the input packet stored in the input buffer 11 in the reservation table 15. In order to create the reservation table 15, a delay of a predetermined time slot is given in advance when the control unit 14 allocates a time slot.

In the figure, at time slot t, wavelength λ
₅ is used (e.g., corresponding to the outgoing line 17 ₅ in FIG. 1) is used the wavelength lambda _N are in time slot t + 1, indicating that the wavelength lambda ₁ in the time slot t + 2 is used. Further, in the time slot t, the variable wavelength electro - optical converter 12 _-1 performs conversion operation, where only the converted optical signal is input to the optical coupler-splitter 13, the variable wavelength electro - optical converter 12 _{- In steps 2} and _12-3 , the wavelength is changed according to the setting information in the reservation table 15 without performing the conversion operation. Therefore, in the time slot t + 1, the variable wavelength electro-optical converter _12-2 has already completed the change to the wavelength λ _N and can immediately transmit the optical signal of the wavelength λ _N. In the time slot t + 1, the other variable wavelength electro-optical converters 12 _-1 and 12 _-3 change to the wavelength according to the setting information of the reservation table 15 without performing the conversion operation.

With such a configuration, the reservation table 15
, Each variable wavelength electro-optical converter 12 can start the operation of changing to the wavelength used in each time slot in advance, so that the wavelength changing speed of one variable wavelength electro-optical converter 12 is equal to the line speed. Can respond sufficiently even if it is slow. Next, the operation of the control unit when a failure occurs in the M variable wavelength electro-optical converters corresponding to each input buffer will be described with reference to FIG.

In FIG. 3, similarly, attention is paid to one input line 10, and a control example in a path from the input buffer 11 to the optical coupling / distributor 13 will be described. Also, M = 3
However, the same applies to any M. Here, in order to facilitate the description, as a means for connecting the variable wavelength electro-optical converters 12 _{-1 to} 12 _-3 specified by the control unit 14 to the optical coupling / distributing unit 13, Gate switches 31 _{-1 to} 31 _-3 are provided.

If a failure occurs in the variable wavelength electro-optical converter _12-2 , the control unit 14 recognizes that a failure has occurred. Is controlled 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.

[0020] Thus, in the time slot t, the variable wavelength electro - optical converter 12 _-1 performs conversion operation, where only the converted optical signal through the gate switch 31 _-1 to the light coupling-divider 13 inputs Then, the variable wavelength electro-optical converter _12-3 changes the wavelength to the wavelength according to the setting information of the reservation table 15 without performing the conversion operation. Further, in the time slot t + 1, the variable wavelength electro - and optical transducer 12 _-3 already completed change to the wavelength lambda _1, it is possible to immediately sends the optical signal of the wavelength lambda _1. In the time slot t + 1, the variable wavelength electro - optical converter 12 _-1 make a change in the wavelength in accordance with the setting information of the reservation table 15 without conversion operations.

With such a configuration, an input packet from an incoming line can be processed by using another variable wavelength electro-optical converter 12 except for the variable wavelength electro-optical converter in which a failure has occurred. Next, the operation of the control unit for implementing broadcast communication will be described with reference to FIG.

In FIG. 4, similarly, attention is paid to one input line 10, and a control example in a path from the input buffer 11 to the optical coupling / distributor 13 will be described. Also, M = 3
However, the same applies to any M. Here, in order to facilitate the explanation, as means for connecting the variable wavelength electro-optical converters 12 _{-1 to} 12 _-3 designated by the control unit 14 to the optical coupling / distributing unit 13, Gate switches 31 _{-1 to} 31 _-3 are provided.

Now, it is assumed that packets taken out of the input buffer 11 are connected to three outgoing lines to which wavelengths λ ₁ , λ ₅ and λ _N are assigned. In the control unit 14, based on the information of the input packet and the outgoing line obtained in advance, the variable wavelength electro-optical converter 12 _-1 in the time slot t.
12 _-3, respectively wavelengths lambda _1, lambda _5, sets the convertible state optical signal of lambda _N. In addition, in the time slot t, each of the gate switches 31 _{-1 to} 31 _-3 is set so as to connect each of the variable wavelength electro-optical converters 12 _{-1 to} 12 _-3 and the optical coupler / distributor 13.

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 described above, according to the present invention, by arranging a plurality of M variable wavelength electro-optical converters corresponding to each incoming line and starting the wavelength changing operation in advance according to the reservation table, one M A packet switch corresponding to M times the line speed can be realized as compared with the conventional configuration using the variable wavelength electro-optical converter. It also shows that a packet switch corresponding to the conventional line speed can be realized even if a variable wavelength electro-optical converter having a wavelength change speed of 1 / M is used.

Further, the variable wavelength electro-optical converter has a redundant configuration corresponding to each incoming line, and it is possible to avoid a problem which affects the switching function of the incoming line only by disconnecting the failed variable wavelength electro-optical converter. Therefore, the fault tolerance of the packet switch can be improved. Also,
By arranging a plurality of M variable wavelength electro-optical converters corresponding to each incoming line, it is possible to realize broadcast communication of up to 1 to M.

[Brief description of the drawings]

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

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

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

FIG. 4 is a diagram illustrating a control example for implementing 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]

 Reference Signs List 10 incoming line 11 input buffer 12 variable wavelength electro-optical converter 13 optical coupler / distributor 14 control unit 15 reservation table 16 fixed wavelength optical-electrical converter 17 outgoing lines 18 and 19 signal line 50 incoming line 51 input buffer 52 variable wavelength electric -Optical converter 53 Optical coupling / distributor 54 Control unit 55 Fixed wavelength optical-electrical converter 56 Outgoing lines 57,58 Signal line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification symbol FI H04Q 3/52 101 (58) Investigated field (Int.Cl. ⁶ , DB name) H04L 12/28 H04L 12/56 H04B 10 / 02 H04J 14/00 H04J 14/02 H04Q 3/52 101 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. An input buffer for storing packets input to a plurality of input lines corresponding to each input line, and a packet of an electric signal provided from the input buffer and assigned to each input line, and assigned to each output line. Variable-wavelength electrical-optical converter for converting an optical signal of
An optical coupler / distributor for simultaneously distributing and outputting the optical signal output from the optical converter to all the outgoing lines; and an optical signal packet provided only for the outgoing line and transmitting only the optical signal having the wavelength corresponding to the outgoing line. A fixed-wavelength optical-to-electrical converter for converting the packets stored in the input buffers into predetermined time slots in which competition control on the outgoing line is performed. -In a packet switch comprising a control unit for setting a wavelength corresponding to an outgoing line of a packet in an optical converter, a plurality of the variable wavelength electro-optical converters are arranged for each incoming line, and the control unit A reservation table is provided which indicates to which wavelength each of the plurality of variable wavelength electro-optical converters corresponding to each incoming line changes for each slot, and for each time slot according to this reservation table. Tunable electric corresponding length respectively - packet switches, which is a sequentially switching control constituting the optical converter - Set to optical converters, each variable wavelength electrical per timeslot.