JP2004007204A - Wavelength crankback light wavelength path setting method - Google Patents

Abstract

An object of the present invention is to reduce a calculation load required for recalculating a route and shorten a signaling time.
When the number of available wavelengths at a relay node becomes zero, wavelength conversion is performed if wavelength conversion is possible at the relay node, and wavelength conversion is possible if wavelength conversion is not possible. The wavelength conversion is performed by going back to the upstream relay node, the usable wavelength is reset at the relay node, and the used wavelength is reserved for the destination node on the route calculated first from the relay node.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The invention applies to optical networks. In particular, it relates to means and procedures for setting a wavelength path.
[0002]
[Prior art]
Conventionally, when a path is set by signaling after setting a path, if a block occurs at the relay node, return to the source node and perform the path calculation again, or return to the next upstream node and select another path. The wavelength path is set by using a method such as crankback (here, referred to as path crankback) in which is selected to restart signaling.
[0003]
[Problems to be solved by the invention]
As in the conventional method, when a wavelength path is blocked by a relay node when the path is set, a path calculation is performed again by going back to the upstream node, and the wavelength path is set again by signaling according to a new path candidate. Performing the calculation not only increases the calculation load, but also causes a longer signaling time.
[0004]
The present invention has been made in such a background, and it is an object of the present invention to provide a wavelength crankback optical wavelength path setting method capable of reducing a calculation load required for recalculating a route and shortening a signaling time. Aim.
[0005]
[Means for Solving the Problems]
According to the present invention, even if the reservable wavelength on the relay node on the route from the source node to the destination node becomes zero, the first calculated route from the source node to the destination node is used as it is, and the wavelength conversion is performed. It is possible to go back to a possible relay node and reserve a wavelength for setting an optical wavelength path on the path calculated first by wavelength conversion. As a result, the calculation load required for recalculating the route can be reduced, and the signaling time can be reduced.
[0006]
Here, the source node is a node that sends an optical path setting request, and the destination node is a node that is the destination of the optical path setting request. The optical path set between the source node and the destination node may be unidirectional or bidirectional. In the bidirectional case, either the source node or the destination node can be a data transmission source or a data reception node.
[0007]
That is, according to the present invention, when connecting a plurality of wavelength-multiplexed links at nodes constituting an optical communication network, a path for reserving a used wavelength from a source node to a destination node by signaling on a calculated path. The present invention is applied to the setting of an optical wavelength path for transferring a message from the source node to the destination node via the relay node, and when the number of usable wavelengths becomes zero at the relay node, wavelength conversion is possible at this relay node. If wavelength conversion is not possible, wavelength conversion is performed.If wavelength conversion is not possible, wavelength conversion is performed by going back to the upstream relay node where wavelength conversion is possible, and the available wavelength is reset at the relay node. A method for setting a wavelength-crankback light wavelength path, characterized in that a used wavelength is reserved for a destination node on the set route.
[0008]
In the path message, information of the relay node that is wavelength-convertable and is the most downstream among the relay nodes through which the path message has passed is recorded, and the number of usable wavelengths at the relay node becomes zero. In this case, if wavelength conversion is possible at this relay node, wavelength conversion is performed, and if wavelength conversion is not possible, wavelength conversion is performed by going back to the upstream relay node capable of wavelength conversion recorded in the path message. Then, the available wavelength is reset by the relay node, and the used wavelength can be reserved for the destination node on the route calculated first from the relay node.
[0009]
Alternatively, in the path message, information of a relay node that can perform wavelength conversion among the relay nodes through which the path message has passed is recorded together with information on the remaining number of wavelength conversion resources of the relay node, and is used by the relay node. When the number of possible wavelengths has become zero, wavelength conversion is performed if wavelength conversion is possible at this relay node, and wavelength conversion recorded in the path message is possible if wavelength conversion is not possible. The wavelength conversion is performed by going back to the upstream relay node having the largest remaining number of wavelength conversion resources, resetting the usable wavelength at the relay node, and from the relay node to the destination node on the route newly calculated first again. Can be reserved for the wavelength to be used.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
(Basic method)
With reference to FIG. 1, an example of an optical wavelength path setting method which is the basis of the present invention will be described. Here, when an optical wavelength path is set from the node A to the node E, the idle wavelength of the link between the nodes A and B is λ2 to λ4, and the idle wavelength of the link between the nodes B and C is λ1, λ3, λ4, The idle wavelengths of the links between the nodes C and D are λ1, λ2, λ4, and the idle wavelengths of the links between the nodes D and E are λ1 to λ3. At each node, the idle state of the wavelength in the signaling is represented in a bitmap format.
[0011]
Node A reserves free wavelengths λ2 to λ4, and node B reserves free wavelengths λ3 and λ4. At this time, the used wavelength λ2 of the node B disappears from the reservation. The same applies to the node C. Since only λ4 remains as a free wavelength, the free wavelength λ4 is reserved. Here, the reservable wavelength at the node D becomes zero.
[0012]
The wavelength crankback light wavelength path setting method according to the present embodiment uses the method in the case where the reservable wavelength is lost at the relay node on the way from the source node A to the destination node E. This is an example of a coping method.
[0013]
(First embodiment)
The signaling sequence of the first embodiment will be described with reference to FIG. The network has a linear configuration from a node A to a node E. The node B has two wavelength converters and the node C has one wavelength converter. Here, Wavelength status of link indicates what kind of idle state each link is currently in. In such a case, signaling is performed along the route from the node A to the node E. However, since all the wavelengths become unusable at the node E, it is necessary to go back to the upstream node and search for a node having a wavelength converter. become. In this case, since the wavelength conversion device is disposed at the node C, the wavelength conversion is performed at the node C, the signaling format is cleared once, and the signaling is similarly performed. As a result, since λ1 and λ2 are vacant at the node E, the nodes A to C use λ3 or λ4, and the wavelength of the node C is converted to λ1 or λ2. Uses the converted wavelength.
[0014]
This eliminates the need to calculate another route and return to the source node for the route even when the relay node blocks, so that the time required for path setting can be reduced.
[0015]
(Second embodiment)
A signaling sequence according to the second embodiment will be described with reference to FIG. The network has a linear configuration from a node A to a node E. The node B has two wavelength converters and the node C has one wavelength converter. Here, Wavelength status of link indicates what kind of idle state each link is currently in. In such a case, signaling is performed along the path from the node A to the node E. At this time, the node having the WC at the most downstream position is described in the WC (wavelength conversion resource) column of the signaling format. As a result, when signaling is performed from the node A to the node E, the node C is the node having the WC which is the most downstream, so that C is entered in the WC column. If the signaling is performed up to the node E, all the wavelengths become unusable. Therefore, the WC is performed up to the node C entered in the WC column, the signaling format is cleared once, and the signaling is similarly performed. I will go. As a result, since λ1 and λ2 are open at the node E, λ3 or λ4 is used from the node A to the node C, the wavelength is converted to λ1 or λ2 at the node C, and the wavelength is converted from the node C to the node E. Uses the converted wavelength.
[0016]
This makes it possible to know at which node the wavelength conversion can be performed, so that it is not necessary to confirm whether or not the wavelength conversion can be performed each time one node is traced.
[0017]
(Third embodiment)
A signaling sequence of the third embodiment will be described with reference to FIG. The network has a linear configuration from a node A to a node E. The node B has two wavelength converters and the node C has one wavelength converter. Here, Wavelength status of link indicates what kind of idle state each link is currently in. In such a case, signaling is performed along the path from the node A to the node E. At this time, the number of unused WCs at which node is input in the WC column of the signaling format. If the signaling is performed up to the node E, all the wavelengths become unusable. Therefore, the wavelength conversion is performed in the node B having the largest remaining WC from the number of the remaining WCs of each node input in the WC column, and the node The WC is performed retroactively to B, the Signaling format is cleared once, and the signaling is performed similarly. As a result, λ1 is vacant at the node E. Therefore, λ2, λ3, or λ4 is used from the node A to the node B, wavelength conversion is performed at the node B, and λ1 is used from the node B to the node E. Will do.
[0018]
This makes it possible to perform wavelength conversion at a node having the largest remaining resources of the wavelength converter.
[0019]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the calculation load required for recalculating the route and shorten the signaling time.
[Brief description of the drawings]
FIG. 1 is a diagram showing a signaling sequence of a first embodiment.
FIG. 2 is a diagram showing a signaling sequence of the second embodiment.
FIG. 3 is a diagram showing a signaling sequence of the third embodiment.
[Explanation of symbols]
1-4 Links AE nodes

Claims (3)

When connecting a plurality of wavelength-multiplexed links at the nodes constituting the optical communication network, a path message for reserving the used wavelength from the source node to the destination node by signaling on the calculated path is sent from the source node. Applied to an optical wavelength path setting for forwarding to the destination node via a relay node,
If the number of usable wavelengths at the relay node becomes zero, wavelength conversion is performed if wavelength conversion is possible at this relay node, and if wavelength conversion is not possible, an upstream relay node capable of wavelength conversion. A wavelength crank that performs wavelength conversion retroactively, resets an available wavelength at the relay node, and reserves a wavelength to be used for a destination node on the route calculated first again from the relay node. Back light wavelength path setting method. In the path message, information of the relay node that is wavelength-convertable and is the most downstream among the relay nodes through which the path message has passed is recorded, and the number of usable wavelengths at the relay node becomes zero. In this case, if wavelength conversion is possible at this relay node, wavelength conversion is performed, and if wavelength conversion is not possible, wavelength conversion is performed by going back to the upstream relay node capable of wavelength conversion recorded in the path message. 2. The wavelength crankback light wavelength path setting method according to claim 1, wherein the usable wavelength is reset at the relay node, and the used wavelength is reserved from the relay node to the destination node on the route newly calculated first. . In the path message, information on a relay node that can perform wavelength conversion in the relay node through which the path message has passed is recorded together with information on the remaining number of wavelength conversion resources of the relay node, and the available wavelengths in the relay node are recorded. If the number has become zero, wavelength conversion is performed if wavelength conversion is possible at this relay node, and if wavelength conversion is not possible, the wavelength conversion recorded in the path message is possible. Perform wavelength conversion by going back to the upstream relay node having a large number of remaining wavelength conversion resources, resetting the usable wavelength at that relay node, and using the destination node on the route newly calculated from the relay node first. 2. The wavelength crankback light wavelength path setting method according to claim 1, wherein a wavelength is reserved.

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