JP3816831B2 - Optical network - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical network configuration for switching wavelength paths.
[0002]
[Prior art]
FIG. 6 shows a conventional optical network, and FIG. 7 is a diagram for explaining the wavelength multiplexing number of each link. In the nodes 1 to 7 constituting this optical network, each link is assumed to be a wavelength multiplexing link. As shown in FIG. 7, it is assumed that the links 12, 13, 23, 24, and 35 are 256-wave multiplexed, and the links 45, 46, 56, 57, and 67 are 128-wave multiplexed. . In the conventional configuration, the number of wavelength multiplexing may be different for each link as shown in the figure. Where the demand is high, it can be used by increasing the number of wavelength multiplexing. However, since the entire network is a single network operated with the same network policy, network resources cannot be used freely and efficiently.
[0003]
[Problems to be solved by the invention]
A conventional optical network includes a wavelength-multiplexed optical fiber and a node that can exchange an arbitrary wavelength channel multiplexed on the optical fiber with a wavelength channel of an arbitrary optical fiber. With the development of wavelength resources, it has become possible to use a wide range of wavelength resources such as S band and L band in addition to the conventional C band centered on 1.3 μm band and 1.5 μm band. If these bands are used, it is possible to use hundreds of wavelength channels or more, and it has become possible to construct an optical network with a larger capacity.
[0004]
Such an optical network is used for various applications of various users. Therefore, the optical network needs to be able to cope with various requirements due to differences in users and applications. For example, when setting up a semi-fixed path that stays at a specific connection destination or is held for a long time, and a wavelength path where the hold time of the wavelength path is short and the connection destination changes frequently, the network needs The conditions are different. Also, the algorithms for efficiently accommodating the wavelength paths of the respective characteristics in the network are different.
[0005]
For example, the routing algorithm for setting the wavelength path includes H.264. As described in Zang, et al, "A review of routing and wavelength assignment approaches for wavelength-routed optical WDM networks", SPIE Optical Networks Magazine, Vol. 1, No. 1, Jan. 2000, Least Load, There are methods such as First-Fit and Most-used. If the hold time of the path is short, use First-Fit with fast path setting control time. If the hold time is long, Most-used to increase the network usage rate, long hold time, but use wavelength conversion as much as possible. If wavelength resources are used transparently, it is better to select a routing algorithm such as Least Load, which is less likely to cause path setting collisions at the same wavelength.
[0006]
However, since the control circuits of the nodes constituting the conventional optical network all operate with the same control policy, they are networks operated with the same policy. Therefore, in a conventional optical network, it is difficult to properly use a plurality of routing algorithms, and it is difficult to realize a routing protocol that satisfies the requirements of all traffic. Therefore, selecting one of the routing protocols increases the possibility that the requirements will not be met, or the operation policy of the entire optical network becomes very complex and cannot be used efficiently when assigning wavelength resources in the network There was a risk of occurrence.
[0007]
The present invention solves such problems, can flexibly cope with different network requirements for each user and application, can support a plurality of network operation policies, and wavelength resources for policy routing throughout the optical network. It aims to operate efficiently without waste.
[0008]
[Means for Solving the Problems]
The optical network of the present invention is an optical network in which a plurality of nodes are connected by wavelength multiplexing links to form one physical network, and a logical sub-network using a virtual wavelength group (VWG) is the one physical network. is configured to include at least a portion of said plurality of nodes on the network, the physical wavelength groups contained in the virtual wavelength groups, characterized in that assigned independently for each link.
[0009]
It is desirable to configure a plurality of logical sub-networks on one physical network.
[0010]
The information of the split Ri devoted physical wavelength group in each link with respect to a virtual wavelength groups are ad among the plurality of nodes is desired. At this time, the assignment of the physical wavelength group to the virtual wavelength group may be controlled in an autonomous and distributed manner at each node and link.
[0011]
Information of the split Ri devoted physical wavelength group in each link is calculated by the central control unit with respect to a virtual wavelength groups, each of the nodes and links can also be controlled based on the information.
[0012]
The number of multiplexed wavelengths required by each link relative to virtual wavelength group observes the predetermined parameters in the network, by calculating based on the its parameters predetermined algorithm, a virtual wavelength groups On the other hand, the number of wavelengths allocated in each link can be automatically calculated.
[0013]
For each logical sub-networks, the operation policy of the network that is applied can be ad between nodes that make up the sub-networks.
[0014]
Can also the number of multiplexed wavelengths that are allocated on each link with respect to a virtual wavelength groups alters over time, can also be varied with time network management policies that apply to logical sub-networks.
[0015]
In other words, in the present invention, the available wavelength resources are allocated to several logical sub-networks for each link to configure a virtual sub-network. Furthermore, for each virtual subnetwork, the policy such as the routing protocol according to the application is changed and operated, and the wavelength multiplexing number is advertised for each link policy that changes from time to time. Make effective use of resources.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention. Here, an example is shown in which the nodes 1 to 7 are connected by wavelength multiplexing links, and three logical sub-networks are configured in one physical configuration.
[0017]
In this embodiment, the wavelength channel is divided into three, and it is logically assumed that there are virtual wavelength groups VWG1, 2, and 3. Each VWG is operated independently and is operated with different network policies. VWGs 1, 2, and 3 construct three logical sub-networks having different nodes and network shapes, and different routing algorithms are applied.
[0018]
FIG. 2 shows an example of assigning the number of multiplexed wavelengths for each link. The number of wavelength multiplexing assigned to each VWG differs for each link.
[0019]
FIG. 3 shows an example of assignment of wavelength channels, and shows an example of assignment of links 12 and 35 in FIG. The link reference number is represented by the reference numbers of the nodes at both ends of the link. The link 12 and the link 35 use different wavelength ranges, and the way of assigning the VWG to the wavelength is also different between the links 12 and 35. In FIG. 3, each VWG is composed of continuous wavelength groups, but a combination in which the wavelengths of each VWG are interleaved may be used.
[0020]
In this way, the actual wavelength band and the VWG are independent, and the correspondence between the physical wavelength channel of each link and the logical VWG may be taken at each node. Note that the physical wavelength and the logical wavelength of each link may be the same. In particular, when passing through a node transparently without using wavelength conversion or 3R, it is easier to use the matching.
[0021]
FIG. 4 is an example of a protocol for advertising the number of wavelengths of links used in these WGs and advertising the logical networks VWG1, 2, and 3. In addition, a policy applied to each logical network such as a routing algorithm applied to each VWG can be advertised. When this protocol is used, it is possible to dynamically change the number of wavelengths of each link in the logical wavelength band VWG that divides the method of use.
[0022]
As control methods, there are a self-distributed method and a centralized control method. The former is a method in which each node reflects its policy in a self-sustaining manner from the information obtained from the routing protocol, and the latter is a calculation algorithm in which the policy server in the network is instructed by the operator and the monitoring result of a certain parameter. The wavelength group assignment method is calculated according to the above, and the result is notified to all nodes. When the network size is small, a method of calculating the logical wavelength allocation and notifying each node using a single control device in a centralized manner can be configured.
[0023]
FIG. 5 shows an example of switching between two VWGs. Create two networks with different routing algorithms and dynamically change the network resources allocated to them. For example, in the example in the figure, the number of wavelength division multiplexed channels of all links is 20 waves from λ0 to λ19, and if the wavelength path to be set is a long hold path with a long set time interval, it is on the shortwave side of policy 1 of the network. If the wavelength path setting time interval is short hold, it is assigned to the long wave side of policy 2. Each routing policy uses an optimal algorithm or the like according to its application, so that it is possible to satisfy the requirements of each wavelength path while effectively using network resources. In accordance with the usage rate of the short hold path and the long hold path, the threshold of the short and long wave is dynamically changed so that wavelength resources can be allocated. At some time, when λ6 is advertised, the network advertises λ0 to λ6 as policy 1 network, and at the next time λ14 is advertised and λ0 to λ14 as policy 1 network. Thus, the resources of the entire network can be used effectively by dynamically adapting the necessary wavelength band throughout the network.
[0024]
【The invention's effect】
As described above, according to the present invention, it is possible to flexibly cope with different network requirements for each user or application, support a plurality of network operation policies, and waste wavelength resources for policy routing in the entire optical network. Can be operated efficiently.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention.
FIG. 2 is a diagram showing an example of assigning the number of multiplexed wavelengths for a link.
FIG. 3 is a diagram showing an example of wavelength channel allocation;
FIG. 4 is a diagram for explaining an example protocol for advertising the number of wavelengths of links used in the WG.
FIG. 5 is a diagram showing an example of switching between two VWGs.
FIG. 6 is a diagram showing a configuration example of a conventional optical network.
FIG. 7 is a diagram for explaining the wavelength multiplexing number of each link.
[Explanation of symbols]
1-7 nodes

Claims (9)

In an optical network where multiple nodes are connected by wavelength division multiplexing links to form one physical network ,
A logical sub-network using a virtual wavelength group (VWG) is configured to include at least a part of the plurality of nodes on the one physical network;
Optical networks this virtual wave physical wavelength group included in the group, characterized in that assigned independently for each link. The optical network according to claim 1, wherein a plurality of logical sub-networks are configured on the one physical network. The optical network according to claim 1 or 2, wherein information on a physical wavelength group assigned by each link to the virtual wavelength group is advertised between the plurality of nodes. 4. The optical network according to claim 3, wherein the allocation of the physical wavelength group to the virtual wavelength group is controlled in an autonomous and distributed manner at each node and link. The information of the split Ri devoted physical wavelength group in each link with respect to a virtual wavelength groups is calculated by the central control apparatus, according to claim 1 or 2, wherein each of the nodes and links is controlled based on the information Optical network. The number of multiplexed wavelengths required by each link relative to the virtual wavelength group observes the predetermined parameters in the network, by calculating based on the predetermined algorithm and the parameter, the virtual wavelength The optical network according to any one of claims 1 to 3, wherein the number of wavelengths allocated at each link to the group is automatically calculated. The optical network of claim 1 or 2 wherein operation policy of the network to be applied to each logical sub-network is ad between nodes that make up the sub-networks. The optical network according to any one of the to the number of multiplexed wavelengths that are allocated on each link with respect to a virtual wavelength groups claims 1 can vary over time 6. The optical network according to any one of claims 1 policy of the network management to be applied to the logical sub-network is variable over time 6.

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