JPH0313034A - Optical exchange control system - Google Patents

Abstract

PURPOSE:To avoid congestion on a link in multi-stage link constitution by converting collision information light at an outgoing terminal of an optical switch node into a different wavelength with a wavelength conversion section respectively and sending the information light subjected to wavelength multiplexing to the link from the outgoing terminal. CONSTITUTION:An optical switching node 1 is provided with a demultiplexing section 2 corresponding to an incoming terminal and a wavelength conversion section 3 corresponding to an outgoing terminal. Then collision information light at an outgoing terminal of the optical switch node 1 is converted into a different wavelength by the wavelength conversion section 3 to apply wavelength multiplexing. The information light subjected to wavelength multiplexing is sent from an outgoing terminal to a link 4, the light received via the link 4 is demultiplexed corresponding to the wavelength by the demultiplexer 2 in the optical switching node 1 and the result is sent. Thus, one of the collision information light is sent to the link 4 and the collision information light is simultaneously sent to the link 4 without storing the other light into the optical buffer memory section.

Description

[Detailed Description of the Invention] [Summary] Regarding an optical switching control method in an optical switching system with a multi-stage link configuration, the purpose is to avoid congestion on the links in the multi-stage link configuration, and to control multiple input/output lights. In an optical switching system having a multi-stage link configuration in which optical switch nodes accommodating highways are connected by links, the optical switch nodes are provided with a demultiplexer corresponding to an input terminal and a wavelength converter corresponding to an output terminal. the collision information light at the output terminal of the optical switch node is converted into different wavelengths by the wavelength converter and wavelength-multiplexed, and the wavelength-multiplexed information light is sent from the output terminal to the link. The optical switch node that receives the signal via the link is configured to separate the signals according to the wavelengths by the demultiplexer.

[Industrial application field]

The present invention relates to an optical switching control method in an optical switching system having a multi-stage link configuration.

In high-speed packet switching systems and asynchronous transfer mode (ATM) switching systems, the delay time and discard rate of packets or ATM cells pose problems. Therefore, when performing switching processing using an optical switching system with a multi-stage link configuration, it is necessary to avoid congestion in the links.

[Conventional technology]

An optical switching system with a multi-stage link configuration connects optical switch nodes on the input and output sides with links, respectively.
For example, in a conventional optical switching system with a two-stage link configuration,
It has the configuration shown in FIG. In the same figure,
41 to 4n, 51 to 5n are optical switch nodes, 61 is an optical switch section, 62 is an optical buffer memory section, 711 to 7n
n is link, 811-8nm is light input highway, 911
~9 nm indicates the Idemitsu highway, and the wavelength λ. This shows the case where ATM cell exchange processing is performed.

For example, the optical switch section 61 is constructed by forming intersecting waveguides on a LiNbO3 substrate by Ti diffusion, and applying a voltage to the intersections of the waveguides to change the refractive index at the intersections. , the input light can be switched and output. Further, the optical buffer memory section 62 can have a delay memory configuration using an optical fiber or the like, or a memory configuration using a bistable semiconductor laser.

When an ATM cell to which a header H containing information such as the destination is attached is exchanged and output from the cellular optical input highway 811 to the Idemitsu highway 9 nm, the optical switch node 41 that accommodates the input optical highway 811 and the optical switch node 41 that accommodates the Idemitsu highway 9 nm are connected. When the link 71n between the switch node 5n and the switch node 5n is vacant, the ATV cell A connects the optical switch section 61 to the optical buffer memory section 62 to the link 71n- along the route shown by the thick line.
The optical switch section 61→the optical buffer memory section 62 sends the signal to Idemitsu Highway 9 nm.

Furthermore, when the ATM cell B is exchanged and outputted from the input light highway 81m to the output light highway 9nl, the ATM cell is sent via the link 71n between the optical switch nodes 41.5n, and at that time, the ATM cell B is sent via the link 71n between the optical switch nodes 41.5n. When an ATM cell outage occurs, the ATM cells are temporarily stored in the optical buffer memory unit 62 of the ATM cell-switch node 41, and when the link 71n becomes vacant after being sent to the ATM cell rank 71n, the optical buffer memory unit 62
ATM cells temporarily accumulated in - that link? It will be sent to In.

As mentioned above, the optical switch nodes 41-4n51-5n
The optical switch section 61 is controlled according to the destination of the ATM cell, and the optical buffer memory section 62 is controlled according to the destination of the ATM cell.
A transmitting to 7nm or Idemitsu Highway 911-9nm
When TM cells collide, temporarily store ATM cells,
The accumulated ATM cells are sent out when there is no collision.

Also, when performing packet exchange processing, the optical switch section 61 and optical buffer memory section 62 operate in the same manner as in the above-mentioned ATM cell exchange processing.

[Problem to be solved by the invention]

As mentioned above, even if Idemitsu Highways 9nl and 9nm are empty, there may be a collision between ATM cells on the link 71n, and in that case, the transmission is sent to one ATM cell and the other ATM cell is The data is stored in the optical buffer memory section 62 and waits for transmission to the link 71n. In addition, in an optical switching system with a multi-stage link configuration in which optical switch nodes are provided in multiple stages,
Even if there is space on the Idemitsu Highway, more collisions will occur on the link, and the number of ATM cells temporarily stored in the optical buffer memory section 62 will be large (thus, the delay of ATM cells will become a problem).

Furthermore, since the capacity of the optical buffer memory section 62 is limited, collision ATM cells that cannot be stored will be discarded. In order to prevent this, it would be sufficient to increase the capacity of the optical buffer memory section 62, but this would cause problems of large size and economy, and would further exacerbate the problem of increased delay time as described above.

Also, in packet switching, as in the case of ATV cells, the problem of collisions in links occurs.

An object of the present invention is to avoid congestion on links in a multi-stage link configuration.

[Means to solve the problem]

The optical switching control system of the present invention avoids congestion on links by wavelength multiplexing, and will be explained with reference to FIG. 1.

The optical switch node 1 is provided with a demultiplexer 2 corresponding to the input terminal and a wavelength converter 3 corresponding to the output terminal, and the collision information light at the output terminal of the optical switch node 1 is converted into different wavelengths by the wavelength converter 3. This wavelength-multiplexed information light is sent from the output terminal to link 4, and received via link 4, is split into wavelengths by the demultiplexer 2 in the optical switch node 1. It is something that is sent out in waves.

[Effect]

When the transmission of information light composed of ATM cells, packets, etc. collides with the link 4 between the optical switch nodes 1, the colliding information light is converted into different wavelengths, wavelength multiplexed, and sent to the link 4. Therefore, it is possible to send out one of the collision information lights to the link 4 and store the other in the optical buffer memory section (the collision information lights can be sent out to the link 4 at the same time. Therefore, the collision information lights can be sent to the link 4 at the same time. In principle, this section can be omitted.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of an embodiment of the present invention, showing a case of a two-stage link configuration, where 11, 21, and 1222 are optical switch nodes, 13 to 16 are light input highways, 17 to 20 are links, and 23 to 26 is Idemitsu Highway, 31.32 is a wavelength conversion section, 33 is a demultiplexing section, 34 is an optical buffer memory section,
35 is a wavelength conversion section, and 36 is a multiplexing section. The demultiplexing section 33 corresponds to the demultiplexing section 2 in FIG. 1, and the wavelength λ1. The wavelength converter 3 in FIG. 1 is composed of the λ2 compatible optical buffer memory section 34, the wavelength converter 35, and the multiplexer 36.

Furthermore, for the optical switch section 61 in FIG.
1 and the configuration of the demultiplexer 33 correspond to each other.

The wavelength converter 31 converts the wavelength λ. It converts information light such as ATM cells and packets into a wavelength corresponding to the destination.
For example, when exchanging and outputting from the light input highway 13 to the output light highway 23 via the link 17, the wavelength is converted to λ1. Thereby, the signal is branched to the link 17 side by the branching section 33. Similarly, from the entrance highway 13 to the link 18
When the signal is exchanged and output to the Idemitsu Highway 26 via the wavelength λ2, it is converted to the wavelength λ2. Thereby, the signal is branched to the link 18 side by the branching section 33.

Although the optical buffer memory section 34 can be omitted in principle, for example, the Idemitsu Highway 23-2
If a collision occurs in link 6, links 17 to 2
0 or Idemitsu Highways 23 to 26, and since collisions in links 17 to 20 can be avoided by wavelength multiplexing, a small capacity configuration is sufficient.

Also, the wavelength conversion unit 35 in the optical switch node 11.21
is for converting to a different wavelength when a collision occurs in links 17 to 20, and is wavelength multiplexed in the multiplexer 36 and sent to links 17 to 20. . Furthermore, the wavelength conversion section 35 in the optical switch node 12.22 can also be omitted.

Further, the wavelength converter 32 converts the information light having the wavelength λ1, which is multiplexed by the multiplexer 36 of the optical switch node 12°22, into a wavelength λ. The information light of wavelength λ2 which is converted into and multiplexed into wavelength λ2 is converted into wavelength λ. , and the wavelength λ on the incident highways 13 to 16. It is for sending out to Idemitsu Highways 23 to 26 as the same wavelength.

Therefore, the wavelength conversion unit 35 of the optical switch node 12.22 on the Idemitsu Highway 23-26 side and the
Although it is sufficient to provide only one of the wavelength converters 32 connected to the optical switch nodes 11 and 26, the optical switch nodes 11,
12.21.22 are shown as having the same configuration.

Further, the wavelength conversion sections 31, 32, and 35 can have, for example, a tandem electrode configuration similar to a bistable semiconductor laser, and can convert the wavelength of input light according to the injected current.

For example, when outputting the ATV cell A from the incoming light highway 13 to the Idemitsu highway 26 and the ATM cell B from the incoming light highway 14 to the Idemitsu highway 25, the wavelength converter 31 changes the ATM cell liquid to the wavelength λ2. The demultiplexer 33 of the optical switch node 11
If the signals collide on the link 18, the wavelength converter 35 converts the ATM cell B to the wavelength λ1, for example. Therefore, in the combining section 36, the ATM cell liquid length λZ,
ATM cell B is wavelength multiplexed as wavelength λ1 and simultaneously sent out to link 18.

In the demultiplexer 33 of the optical switch node 22, the wavelengths λ1. λ
2, the ATM cell B with wavelength λ1 is split into optical buffer memory 34.2. The wavelength λ is added to the wavelength converter 32 via the wavelength converter 35 and the multiplexer 36. and sent to Idemitsu Highway 25. Also, an ATM cell liquid optical buffer memory 34 with wavelength λ2. The wavelength λ is added to the wavelength converter 32 via the wavelength converter 352 and the multiplexer 36. and is sent to Idemitsu Highway 26.

In other words, the ATM cell liquid is exchanged along the route shown by the thick line, and in the link 18, it is wavelength multiplexed and can be simultaneously transferred to the next optical switch node 22.

FIG. 3 is an explanatory diagram of the operation, and as shown in (al) and (b), ATM cell liquids with headers Ha and Hb are added from the light entrance highway 13 and 14, respectively, and A
When the TV cell A is exchanged and outputted to the Idemitsu Highway 26 and the ATM cell B to the Idemitsu Highway 25, the wavelength converter 31 converts the wavelength λ.

is converted to wavelength λ2. Then, in the demultiplexer 33, the wavelength λ3. Since wavelength λ2 is demultiplexed, A of wavelength λ2
The TM cell liquid is branched to the link 18 side.

Then, as shown in (C1, (d)), the wavelength conversion section 35
In this case, the ATM cell liquid length λ2 remains unchanged, and the ATM cell liquid length λ2 remains unchanged.
Cell B is converted from wavelength λ2' to wavelength λ. Then, they are multiplexed in the multiplexing section 36 (as shown in el),
The ATM cell fluid is wavelength multiplexed and sent to link 18.

The wavelength-multiplexed ATV cells A and B are demultiplexed by the demultiplexer 33 of the optical switch node 22, and as shown in FIGS.

was converted into ATM cell liquid light highway 26,
ATM cells B are sent out to Idemitsu Highway 25, respectively.

Therefore, even if a plurality of ATM cells collide on a link, the colliding ATM cells can be simultaneously sent out to the link by converting and multiplexing each wavelength to a wavelength with a different number of collisions. On the other hand, in the conventional example, for example,
After ATV cell A is sent out to the link first, ATM cell B is sent out as shown in (h).
Cell B will be delayed. However, according to the present invention, it is possible to perform the exchange process without causing such a delay, and the optical buffer memory section can be omitted or its capacity can be reduced. Furthermore, the present invention can be applied not only to a two-stage link configuration but also to a multi-stage link configuration in which optical switch nodes are provided in multiple stages.

〔Effect of the invention〕

As explained above, the present invention provides an optical switch node 1 with a demultiplexer 2 and a wavelength converter 3, and transmits information light such as ATM cells and packets in the link 4 between the optical switch nodes 1. When a collision occurs, the wavelength converter 3 converts the colliding information light into different wavelengths and wavelength-multiplexes them, and sends out the wavelength-multiplexed information light to the link.In the link 4, the information light collides. There is no need to perform hardware processing (therefore, the delay time and waste rate can be kept small, and the optical buffer memory section can be omitted or the capacity can be reduced, so it is economically possible to achieve high speed and large capacity). There is an advantage that it becomes possible to configure an optical switching system.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is an explanatory diagram of the operation of an embodiment of the present invention.
FIG. 4 is an explanatory diagram of a conventional example. 1 is an optical switch node, 2 is a demultiplexer, 3 is a wavelength converter,
4 is a link.

Claims (1)

[Claims] In an optical switching system having a multi-stage link configuration in which optical switch nodes accommodating a plurality of input/output optical highways are connected by links, the optical switch node (1) has an input terminal corresponding to an input terminal. Demultiplexer (
2) and a wavelength converter (3) corresponding to the output terminal, and the collision information light at the output terminal of the optical switch node (1) is converted into different wavelengths by the wavelength converter (3). The optical switch node (1) transmits the wavelength-multiplexed information light from the output terminal to the link (4), and receives the wavelength-multiplexed information light via the link (4). ) is an optical switching control method characterized by demultiplexing according to wavelength.