KR20040025039A - Dynamic lightpath setup method for waveband switching WDM transport networks - Google Patents

Abstract

PURPOSE: A method is provided to achieve improved possibility of success of optical path formation and cancellation even in the dynamic environment. CONSTITUTION: A method comprises a first step of searching waveband paths(32) on the relevant routing path when a new optical path formation request arises; a second step of setting a new optical path by using the waveband path having both ends corresponding to the source node and the object node of the routing path; a third step of setting a new optical path by using the waveband path allowing for a setting of optical path between the source node and the object node, if the waveband path having both ends corresponding to the source node and the object node of the routing path does not exist; a fourth step of setting a new optical path by using the optical path which allows for a sequential passage between the source node and the object node due to the addition of the new waveband path, if the optical path setting is impossible in the third step; and a fifth step of dividing at least one of the waveband paths searched in the first step, and setting a new optical path by using the divided waveband path, if the optical path setting is impossible in the fourth step.

Description

Dynamic lightpath setup method for waveband switching WDM transport networks

The present invention relates to a method for setting a light path, and more particularly, to adjust the operation of each switching node on a routing path determined between a source node and a destination node according to a dynamically generated light path request to increase the probability of acceptance success. It relates to a light path setting method to enable.

Waveband refers to a continuous wavelength channel.

Wavelength channel switching requires the handling of individual wavelength channels, which makes the optical switch very large.

On the other hand, waveband switching can significantly reduce the size of the optical switch compared to the switching method of the wavelength channel unit, but has a feature that it is impossible to configure the connection as close as the wavelength channel method.

The conventional study on waveband switching assumes a static environment in which the demands of the optical path are all determined in advance and the waveband routing is performed in an optimal form.

However, in order to accommodate the changing traffic such as IP traffic, it is necessary to change the setting of the optical path accordingly, and it is impossible to accurately predict all the optical path demands in advance, and thus, static IP / WDM The design of the optical network does not lead to optimization of performance.

The most important thing in the operation of a dynamic WDM network is that it must be able to accommodate the customer's request to create the optical path as closely as possible.

When the waveband path is predetermined and fixed, it may be impossible to set the optical path regardless of the use of the wavelength channel depending on the configuration of the waveband path.

Therefore, an object of the present invention is to increase the probability of the success of the optical path generation in the situation where the request for the generation and termination of the optical path is dynamically provided to accommodate the customer's optical path generation without clogging as much as possible.

1 is a block diagram showing the structure of a waveband switching node system.

FIG. 2 is a view showing the shape of actually receiving the optical path using the waveband switching node system of FIG.

3 is a diagram illustrating one embodiment of dynamic optical path establishment in a linearly configured WDM optical transport network;

4 is a diagram illustrating an embodiment of setting a new optical path by adding a new waveband path in the situation of FIG.

FIG. 5 is a diagram illustrating an embodiment of setting a new optical path by dividing a waveband path in the situation of FIG. 4. FIG.

6 is a flowchart illustrating a process of generating a new light path.

7 is a flowchart illustrating a light path termination process.

In the optical path setting method of the present invention for achieving the above object, a first step of searching for waveband paths having an idle wavelength channel on a corresponding routing path when a new optical path generation request is made, among the waveband paths found in the first step; If there is a waveband path whose both ends correspond to the source node and the destination node of the routing path, a waveband path whose both ends correspond to the source node and the destination node in step 2 and step 2 of setting a new optical path using the waveband path, if the end is present. If does not exist, if the optical path can be set between the source node and the target node by sequentially passing among the waveband paths searched in the first step, the new path is set using the third and third steps. If it is impossible to set the optical path through the new waveband path, the source node and the destination node If it is possible to set the optical paths that pass through sequentially, if it is impossible to set the optical path by adding a new waveband path in steps 4 and 4 of setting a new optical path using at least one of the waveband paths found in the first step, And dividing one and setting an optical path using the divided waveband path.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the structure of a waveband switching node system.

The waveband multiplexing / demultiplexing units 12 and 20 receive wavelength multiplexed signals incident from neighboring node systems and separate them into waveband units, and multiplex the wavelength multiplexed signals of waveband units incident in opposite directions to other neighboring nodes. Transfer it to the system.

The waveband cross connect (WBXC) 14 switches the wavelength-multiplexed signals separated by the waveband units in the waveband multiplexing / demultiplexing units 12 and 20 into signals of different wavebands or wavelengths according to the optical path setting. .

That is, when the WBXC (Waveband Cross Connect) 14 is provided with a plurality of reflectors in a matrix form and outputs a specific optical signal to each subscriber system connected to the corresponding node, the WBXC 14 outputs a signal incident on a specific waveband to another waveband. In the case of converting the signal to the same waveband or converting the signal to a signal having a different wavelength, the wavelength multiplexed optical signal incident to the corresponding waveband unit is output to the WXC (Wavelength Cross Connect) 16.

Of course, the same operation is performed in the reverse direction.

Wavelength Cross Connect (WXC) 16 switches the signals of each wavelength separated in wavelength channel units and outputs the signals to the respective subscriber systems through the wavelength channel ports of the corresponding wavelengths or outputs them to the Waveband Cross Connect (WBXC) 14. .

Between the WBXC (Waveband Cross Connect) 14 and the WXC (Wavelength Cross Connect) 16, the wavelength-multiplexed signal of the individual waveband unit is separated into the wavelength channel unit signal and the signal of the wavelength channel unit is again divided into the individual waveband unit. A multiplexer / demultiplexer 18 is provided to multiplex the wavelength multiplexed signal.

The multiple / demultiplexer 18 has a wavelength conversion function for wavelength control of individual wavelength channels.

FIG. 2 is a view showing a shape in which the optical path is actually received using the waveband switching node system of FIG.

Given a request to create a new optical path between node system N1 as a source node and node system N3 as a destination node, a waveband path 22 between the nodes is established and a new optical path 24 in the wavelength channel of the waveband path. Is accepted.

At this time, the node system N2 performs switching only in units of wavebands, and the optical path is loaded on the wavelength channel through the WXC 16 at the source node N1 and the destination node N2 of the optical path.

3 is a diagram illustrating an embodiment of setting a dynamic optical path in a linearly configured WDM optical transport network.

In this embodiment, the WDM network configuration in which four wavelengths are multiplexed is shown as an example, and the four wavelengths are divided into two wavebands.

A total of three optical paths are shown in the embodiment accommodated in three waveband paths 32, 34, 36.

FIG. 4 shows that when a new optical path is to be accommodated between the node system N2 and the node system N5 in the situation of FIG. 3, no further waveband path can be established between the node system N2 and the node system N5. The node system N4 represents a shape in which a new optical path is accommodated by generating an additional waveband path between the node system N4 and the node system N5 through an idle wavelength channel in the existing waveband.

That is, the new optical path passes through the two wavebands in sequence.

At this time, when the wavelength channel of the new optical path is different in the waveband path 32 and the waveband 38, the wavelength channel switching function is required at the WXC 16 of the node system N4, which is a junction node.

FIG. 5 illustrates a case in which a new optical path setting is required between the node system N2 and the node system N3 in the situation of FIG. 4.

It is not possible to establish a new waveband path between node system N2 and node system N3, and there is no combination of wavebands passing sequentially.

In this case, the sequential path is created by dividing the existing waveband path. When selecting the waveband path to be divided, it is preferable to minimize the setting of the conventionally accepted optical path. Therefore, the waveband path 34 of FIG. 4 is divided.

The new optical path is accommodated in the spare wavelength channel in the divided waveband path 34, and the conventional optical path is switched through the WXC 16 of the node system N2, which is an intermediate node.

6 is a flowchart illustrating a light path setting method according to the present invention using the above-described methods.

When a request for creating a new optical path is given, the routing path of the optical path is determined, and then waveband paths having an extra wavelength channel are searched using the waveband path and the wavelength channel status on the routing path (step 601). In this case, the set of designated waveband paths is designated as A.

In this case, when the request for generation of the optical path is given, the routing path between the source node and the destination node can be easily determined through the shortest path search algorithm, and thus the selection of the routing path is considered to have already been made and the waveband path on the selected routing path is determined. I use it.

The set A of the waveband paths designated in step 601 is searched for whether there is a waveband path that matches both ends of the new optical path, that is, the source node and the destination node (step 602).

As a result of the search, if a waveband path coinciding with the source node and the destination node exists, the optical path is accepted using the idle wavelength channel of the waveband path (step 603).

For example, in FIG. 3, when a new optical path is to be accommodated between the node system N2 and the node system N4, the waveband path 32 having the idle wavelength channel in the corresponding routing path N2-N4 becomes an element of the set A. Since both ends of the waveband path 32 coincide with both nodes of the routing paths N2-N4, the new optical path is accommodated using the idle wavelength channel of the waveband 32 path.

However, if there is no waveband matching the source node and the destination node, it is searched whether the light path can be set via the elements of A sequentially (step 604).

If there are waveband paths that can be optically set through the elements of A sequentially, the new optical path is accommodated using a combination of only the smallest waveband paths among them (step 605).

In step 604, if there is no waveband in which the optical path can be set sequentially among the elements of A, a new waveband path is added to A to search whether the optical path can be set sequentially.

As a result, if there is a section that can set the optical path by sequentially adding a new waveband path between the source node and the destination node, a new waveband path is created in the corresponding section, and then only the minimum elements are sequentially passed. Accept the furnace (step 607).

For example, in FIG. 3, when a new optical path is to be set between the node system N2 and the node system N5, the new optical path cannot be set only by the waveband path 32 in the corresponding routing path, and another wave to set the optical path through the sequence sequentially. Since there is no band, we add a new waveband path to see if it can accept the path between node system N2 and node system N5.

Since there is a waveband path 32 having an idle wavelength channel between node system N2 and node system N4 in FIG. 3, a new waveband path 38 is created between node system N4 and node system N5 as shown in FIG. 4. It is possible to accommodate a new optical path through two waveband paths 32, 38 sequentially between N2 and node system N5.

That is, between the node system N2 and the node system N4, the idle wavelength channel λ ₂ of the preset waveband path 32 is used, and a new waveband path 38 is additionally generated only between the node system N4 and the node system N5.

If the optical path setting is not possible even by adding a new waveband path in step 606, it is determined whether the optical path setting is possible between the source node and the destination node by dividing at least one of the waveband paths belonging to A (step 608). .

As a result of the search, when there are waveband paths that can be set as optical paths through division, the waveband paths that divide the waveband paths constituting the new optical path with the smallest number of waveband paths are divided and divided. The optical path is then accommodated using the split waveband path (step 609).

When there are waveband paths to be split under the same conditions, the spare wavelength channel preferentially splits more waveband paths.

For example, in FIG. 4, when a new optical path is to be established between the node N2 and the node N3, there is no waveband path having an idle wavelength channel in the corresponding period N2-N3, and a new waveband path is added to the corresponding period N2. Since the optical path of N3) cannot be set, the waveband path 34 having the idle wavelength channel is divided into two waveband paths 34-1 and 342 as shown in FIG.

In FIG. 5, the new optical path is set up by only one waveband path 34-2 divided in one waveband path 34, but the plurality of waveband paths are divided and the plurality of divided waveband paths are sequentially By way of example, an optical path between the source node and the destination node can be set.

If the sequential waveband path combination is not found even through the division in step 608, the optical path generation request is rejected (step 610).

7 is a flowchart illustrating a processing process according to a preset light path termination request according to the present invention.

When a cancellation request for any one of the preset optical paths is generated, the waveband path that accommodates the optical path is searched (step 701) and then the canceled light path is deleted from the searched waveband path (step 702).

At this time, the optical path to be canceled may be made through a plurality of wavebands sequentially, and furthermore, such a sequential optical path may be made by division as shown in FIG. 5.

Thus, in such a case, it is searched for which of the optical paths remaining after the termination of any optical path is possible to reverse the above-described step 609 (step 703).

That is, if the remaining optical paths are sequentially routed between different waveband paths having the same wavelength channel due to the optical path deletion according to step 702, unnecessary switching in the node system by combining them into one waveband path This can reduce the movement.

If possible, combine the corresponding waveband paths (step 704).

Next, the termination of the specific optical path searches whether there is a waveband path in which all wavelength channels are idle (step 705), and if such a waveband path exists, the waveband path is terminated (step 706).

As described above, by using the dynamic light path setting method of the present invention, even in a dynamic environment in which a demand for generation and termination of the light path is frequently generated, the probability of success of the light path reception is increased in accordance with the request of the customer's light path generation and cancellation in real time. Can be.

Claims (6)

Searching for waveband paths with idle wavelength channels on a corresponding routing path when a new optical path generation request is made; A second step of setting a new optical path by using a waveband path whose both ends correspond to the source node and the destination node of the routing path among the waveband paths searched in the first step; In the second step, when there is no waveband path in which both ends correspond to the source node and the destination node, the scene between the source node and the destination node is sequentially passed through one of the waveband paths found in the first step. A third step of setting a new optical path using this if possible; If it is impossible to set the optical path through the sequential pass-through in the third step, a fourth optical path may be set by using a new waveband path, and if the optical path is sequentially set between the source node and the target node. step; And If it is impossible to set the optical path by adding a new waveband path in the fourth step, a fifth step of dividing at least one of the waveband paths found in the first step and setting the optical path using the divided waveband path An optical path setting method in a waveband switching wavelength division multiplexing transmission network comprising a. The method of claim 1, In the fifth step, in the waveband switching wavelength division multiplexing transmission network, a waveband path having the smallest number of waveband paths constituting the new optical path is selected and split when split among the splittable waveband paths. How to set the light path. The method of claim 2, If the number of waveband paths constituting the new optical path is the same, the waveband path having a large number of free wavelength channels are divided first. The method of claim 3, wherein And in the fifth step, performing the second to fourth steps using the divided waveband paths. A first step of searching for a waveband path containing the requested optical path for termination; A second step of deleting the requested optical path from the waveband path searched in the first step; And In the waveband switching wavelength division multiplexing transmission network including a third step of combining the corresponding wavebands when there are optical paths sequentially passing through different waveband paths having the same wavelength channel due to the second optical path deletion. How to set the path of light. The method of claim 5, wherein And a fourth step of canceling a waveband path in which all wavelength channels are idle after deleting the optical path of the second step.