JP2003304274A - Reserve optical path band securing method and optical path switching device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To automatically set up a backup optical path and further minimize the amount of equipment required for the backup optical path. SOLUTION: In an optical path switching apparatus provided with an optical path setting management function unit for securing a band of a backup optical path to be switched when a working optical path set in an optical communication network becomes unavailable, an optical path setting management is performed. A function unit configured to store risk classification information of the optical path switching device and risk classification information of each link connected to the optical path switching device, a database holding risk classification information registered in an optical channel accommodated in the optical path switching device; A protection optical path setting process for inputting the risk classification information notified from another optical path switching device when the protection optical path band is secured, and outputting the bandwidth to be secured as the protection light path and the newly updated risk classification information. And parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backup optical path band securing method for securing a band of a backup optical path in an optical path switching device (optical router) in a large capacity optical communication network, and an optical path switching for realizing the same. Regarding the device.

[0002]

2. Description of the Related Art Due to an increase in data communication traffic such as the Internet, Tbit / s at present, and 10 to 10 in the near future.
Introduction of a node device having a throughput of 0 Tbit / s or more is under study. As a means for realizing a node device having such a large-scale transfer capability, since it exceeds the limit of electrical processing, an optical router (reference: K.Shimano et al., I
n Technical Digest of NFOEC'2001, vol.1, p.5, 200
1) is influential. In this optical router, the management of the optical communication network is performed in a distributed manner for each node, and the optical path connection setting is also performed based on the signaling process between the nodes. That is, in the optical communication network using the optical router, the setting management of the optical path is autonomously distributed for each node.

In such an optical communication network,
The shared protection method is promising as a means for providing highly reliable network services while making effective use of resources. This system secures a spare optical path band accommodated in a path completely different from the working optical path, and shares this spare optical path band with a spare optical path for another working optical path. As a result, it is possible to secure the predetermined reliability while conserving the resources of the backup optical path required for the entire network.

[0004]

By the way, in order to realize the shared protection method in such an autonomous distributed optical communication network, it is necessary to expand the signaling protocol for securing the spare optical path band. For example, as shown in FIG. 12, when a band is temporarily reserved for the working optical path and a band is secured, nodes # 1, # 2, #
The optical path is opened along the path of # 3 and # 6. On the other hand, with respect to the backup optical path, only the use of the band corresponding to the backup optical path is registered, and the actual optical path is not connected until the working optical path becomes unconnectable due to some influence. There is a need. Therefore, in order to secure the band of the backup optical path by the signaling process similar to the setting of the working optical path, it is necessary to include the identification information that makes it clear that the backup optical path is set.

Further, in order for the shared protection method to function effectively, a plurality of working optical paths that are switched due to a failure of a part of the network device do not secure the same protection optical path band together. It is necessary to set a backup optical path.

In view of the above points, the present invention automatically sets a backup optical path, and further, a backup optical path bandwidth ensuring method and a backup optical path band securing method capable of minimizing the amount of equipment required by the backup optical path. An object is to provide an optical path switching device.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a backup optical path band securing method for securing a band of a backup optical path to be switched when a working optical path becomes unavailable in a node of an optical communication network. Notifies the downstream node of the identification information indicating that the optical path is the backup optical path and the risk classification information to which the working optical path corresponding to the backup optical path belongs when the bandwidth of the backup optical path is secured.

Further, each node of the backup optical path band securing method of the present invention is notified of danger classification information of the working optical path from the downstream node (or upstream node) which has secured the band when the working optical path is connected. To this, add the risk classification information of the link containing the node and the working optical path connected to the node to the upstream node (or downstream node)
To notify.

The present invention provides an optical path switching apparatus having an optical path setting management function section for securing a band of a spare optical path to be switched when a working optical path set in an optical communication network becomes unusable. The path setting management function unit holds the risk classification information of the optical path switching device and each link connected to the optical path switching device, and the risk classification information registered in the optical channel accommodated in the optical path switching device. Database, and input the risk classification information notified from other optical path switching device at the time of securing the spare optical path band, and output the band secured as a spare optical path and the newly updated risk classification information. And a path setting processing unit.

The risk classification information registered in the optical channel is
The risk classification information to which the working optical path, which has secured the optical path as a backup optical path band, belongs.

Further, the backup optical path setting processing section attempts to set the risk classification information sets A1, A2, ..., An held by the optical channel group existing on the route for which the backup optical path is to be secured. The configuration is such that an optical channel for which the logical product of the set B of risk classification information held by the working optical path of the backup optical path is φ (empty set) is searched. Alternatively, a set of risk classification information A′1, A′2, ..., A ′ possessed by the optical channel group existing on the route for securing the backup optical path and already set as the backup optical path band An optical channel for which the logical product of n and the set B of the risk classification information of the input optical path connection request is φ (empty set) may be searched first.

Here, the risk classification information is a numerical value assigned to a single, a partial set, or a whole set of links and nodes accommodating the working optical path.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows an example of the configuration of an optical path switching apparatus of the present invention. In the figure, the optical path switching device is composed of a packet switch unit 1, an optical switch unit 2, and an integrated control function unit 3 that integrally manages these. The optical switch unit 2 uses, for example, a 128 × 128 switch, and has a capability of connecting four fiber links with 32 optical paths multiplexed and inputting / outputting 128 optical paths. The transmission speed of each optical path is 2.5 Gbit / s and it is terminated by the SONET OC-48 interface.

The integrated control function unit 3 of each optical path switching device is
Advertising information control signals are exchanged with each other via the control signal line. The control signal line has a transmission rate of 155 Mbit / s
It is composed of SONET OC-3 lines, and control signals are, for example, OSPF / IS-IS protocol packets for acquiring the network topology of optical communication networks, and RSVP for setting / releasing optical paths set between packet switches. -TE /
It is a CR-LDP protocol packet or a link management protocol (LMP) packet that monitors the failure of each fiber link. Therefore, the integrated control function unit 3 is equipped with a function unit that processes these control signal protocols,
Routing processing function unit (OSPF / IS-IS protocol processing function unit) 31, optical path setting management function unit (RSVP-TE / CR-LDP protocol processing function unit) 32, link failure managing failure of optical fiber and adjacent node The management function unit (LMP protocol processing function unit) 33 is configured.

The routing processing function unit 31 has a function of defining a cost for each fiber link and searching for a route that minimizes the accumulated fiber link cost between the start point node and the end point node of the optical path to be set. The Dijkstra method is applied to the search algorithm. Further, the routing processing function unit 31 has a database holding risk classification information of the own node and each link connected to the own node, and defines the risk classification for each fiber link and each node.

FIG. 2 shows a configuration example of the optical communication network in the first embodiment of the present invention. In the figure, the risk classification information 91 to 96 is assigned to the nodes # 1 to # 6, respectively. Further, for example, when the fiber link connecting between the nodes # 1 and # 2 is represented by “12” by taking the node number, the danger classification information 80 is assigned to the fiber link 12, and the fiber links 14, 23, 24 are similarly set. , 35, 3
Risk classification information 81, 82, 8 in 6, 45, 56 respectively
2,85,84,83,86 are assigned.

For the sake of convenience, the node risk classification information is in the 90's and the fiber link risk classification information is 80.
It's the number one. Further, the same risk classification information 82 is assigned to the fiber link 23 and the fiber link 24. However, this is a risk that fiber cutting occurs at the same time because both fiber links are accommodated in the same clay pipe in some sections. It shows that the property is high.

The optical path setting management function unit 32 has a database holding route information of optical paths input to and output from the node and attribute information of optical channels input to and output from the node. Danger classification information to which the set optical path or backup optical path belongs is registered in this database, and is managed for each optical channel (danger classification information DB for each optical channel interface). In addition to inputting the danger classification information notified from other nodes when securing the spare optical path band, the optical channel secured as the spare optical path and the newly updated danger classification information are output, and the spare optical path is output. It has a spare optical path setting processing unit that searches for an optical channel that accommodates a path. Also, the routing processing function unit 3
The working optical path is set according to the route designated by 1.

FIG. 3 shows a working optical path setting sequence. A provisional bandwidth reservation request for the working optical path is notified from the starting node # 1 to the ending node # 6, and the node # 6 receiving the notification requests the node # 1 to secure the working optical path bandwidth. Notice.

FIG. 4 shows a backup optical path setting sequence. Step 1: Of the fiber link costs registered in the routing processing function unit 31, it is assumed that the fiber link cost of the set route of the working optical path is infinite only when searching for the route of the backup optical path. This is a measure for setting a backup optical path on a route different from the same fiber link as the working optical path.

Step 2: When a route based on the constraint of Step 1 can be found, the starting node # 1 notifies the downstream node on the route of the provisional reservation of the bandwidth of the backup optical path. The notification signal includes identification information indicating that the spare optical path is set, and risk classification information to which the working optical path corresponding to the spare optical path belongs. However, the risk classification information of the node # 1 at the start point and the node # 6 at the end point of the working optical path is not included. This risk classification information is obtained from the routing processing function unit 31 of the starting node # 1 when calculating the route of the working optical path.

Step 3: The downstream node, which has received the preliminary optical path band reservation notification, searches for a band (optical channel) that can be secured toward the end-point node # 6. For example, as shown in FIG. 5, the optical switch unit 2 of the node # 4 switches the paths of the optical channels of the three fiber links 14, 24, 45, and the wavelength converter (that is connected between the input and output thereof) ( WC) converts the wavelength of the signal light. The node # 4 holds the risk classification information to which the optical channel belongs, as the attribute information of the optical channel input to and output from the node # 4. The risk classification information held by the optical channel at the time of system startup is information of the own node, the optical channel accommodating fiber link, and the opposite node of the optical channel.

If an optical channel that can secure the spare optical path band can be found based on this database, the spare optical path band securing is temporarily registered in the database that holds the state of the optical channel that temporarily reserves the band. , The risk classification information held by the working optical path of the spare optical path is provisionally registered. Then, it notifies the downstream node of the provisional reservation of the bandwidth of the backup optical path. The notification signal includes identification information indicating that the spare optical path is set, and risk classification information to which the working optical path corresponding to the spare optical path belongs. Similar operations are performed in all the relay nodes of the backup optical path.

Step 4: The node # 6 at the end point, which has received the provisional reservation notification of the reserve optical path bandwidth, provisionally reserves the necessary reserve optical path bandwidth within its own node, and then on the optical channel to be provisionally reserved. Temporary registration for securing a backup optical path band is performed in a database holding the state, and risk classification information held by the working optical path of the backup optical path is registered. Then, the upstream node is notified of the "preservation" of the band. However, the optical switch unit 2 of the optical path switching device does not operate at all for securing the band reserve of the spare optical path, and only the database update process of the integrated control function unit 3 is performed.

Step 5: The relay node, which has received the band reserve reservation notice from the downstream node, performs the main registration of reserve optical path band reserve in the database holding the state of the temporarily reserved optical channel, and the active optical path of the spare optical path concerned is registered. Register the risk classification information held by the pass. After that, the upstream node is notified of the band reservation of the protection optical path. Even in the relay node, the optical switch unit 2 of the optical path switching device does not operate to secure the band of the backup optical path, and only the database update process of the integrated control function unit 3 is performed. Similar operations are performed in all the relay nodes of the backup optical path.

Step 6: The node # 1 at the starting point, which has received the band reserve reservation notice from the downstream node, performs the main registration of reserve optical path band reserve in the database holding the state of the temporarily reserved optical channel, and the reserve optical path concerned. The risk classification information held by the working optical path of is registered. Even in the node # 1 at the starting point, the optical switch unit 2 of the optical path switching device does not operate to secure the bandwidth of the backup optical path, and only the database update process of the integrated control function unit 3 is performed.

As described above, the risk classification information to which the working optical path which secures the optical channel as the spare optical path band belongs is registered in the database which holds the information of the optical channel secured as the spare optical path.

If the spare optical path band is secured by such a series of operations, even if the working optical path falls into a communication disabled state due to a failure of the transmission path or the like, the spare optical path set in advance is set. You can switch quickly.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention.
2 shows a configuration example of an optical communication network in the embodiment of FIG. In the figure, the risk classification information assigned to each of the nodes # 1 to # 6 and each fiber link is the same as that of the first embodiment shown in FIG. 2, and the basic operation is also the same as that of the first embodiment. Here, it is assumed that the optical path is set from the node # 1 to the node # 5.

The feature of this embodiment lies in the case where a method called crankback is introduced to the band provisional reservation notification of the working optical path. Crankback is a kind of abnormal processing that occurs when a temporary reservation of a band of the working optical path is made on the basis of a route according to an instruction from the routing processing function unit 31 and the band provisional reservation fails at a certain relay node. . That is, in the example shown in FIG. 6, after returning to the upstream node # 2 by failing to secure the band at the node # 4, the shortest route from the node # 2 to the end node # 5 is searched again, Band provisional reservation notification is performed according to the route. Here, the shortest route from the node # 1 to the node # 5 is # 1- # 4-
The reason why # 1- # 2- # 3- # 5 is used instead of # 5 is that the number of channels provided by the fiber link 14 is smaller than that of the fiber link 12 (high cost).

FIG. 7 shows a working optical path setting sequence. FIG. 8 shows a setting sequence of the backup optical path. The basic setting sequence is the same as that of the first embodiment. However, when the band provisional reservation method of the present embodiment is introduced, the risk classification information actually held by the working optical path does not always match the risk classification information of the working optical path retrieved by the start node. . Therefore, at the time of securing the band of the working optical path, the danger classification information of the fiber link accommodating the working optical path and each node is notified to the upstream node, and the danger classification information held by the actually set working optical path is set as the start point node. Then, the backup optical path is set according to the procedure of the first embodiment. As a result, even if an abnormal process occurs during connection of the working optical path, it is possible to accurately obtain the risk classification information held by the working optical path.

(Third Embodiment) FIG. 9 shows a third embodiment of the present invention.
6 shows an example of the configuration of the optical switch unit 2 in the embodiment. The basic operation is similar to that of the second embodiment. The feature of the present embodiment resides in the band securing algorithm of the spare optical path performed at each node when the spare optical path is set.

In FIG. 9, the optical switch section 2 of the node # 4 switches the paths of the optical channels of the three fiber links 14, 24 and 45, and the wavelength converter (WC) connected between its input and output. Converts the wavelength of the signal light. Here, when the protection optical path is secured, the risk classification information held by the working optical path notified from the upstream node and each optical channel trying to secure the band toward the end node of the protection optical path are held. Take the logical product of the risk classification information.

Specifically, a set A1, A2, ..., Of risk classification information held by the optical channels 1 to n for which a band is to be secured is held.
An optical channel for which the logical product of An and the set B of the risk classification information held by the working optical path of the protection optical path to be set is φ (empty set) is searched. This means an operation of searching for an optical channel that does not hold the risk classification information of the protection optical path for which the band is to be secured. That is, as shown in FIG. 10, a plurality of working optical paths having the same risk classification information are set so as not to select the same optical channel as their backup optical path bands.

By such an operation, the protection optical path band is shared by the plurality of working optical paths, while a specific protection optical path band is set so that the plurality of working optical paths do not compete with each other due to the failure of the network device. be able to. As a result, while suppressing the required amount of spare optical path equipment,
It is possible to build a network with high failure recovery probability, low cost, and high reliability.

(Modification of Third Embodiment) FIG. 11 shows a configuration example of the optical switch section 2 in a modification of the third embodiment of the present invention. The basic operation is the same as that of the third embodiment. The feature of this embodiment is that the band securing algorithm for the spare optical path performed at each node at the time of setting the spare optical path is slightly different, and the optical channel that secures the band as the spare optical path is
It is in the process of being preferentially searched from the one already used as the backup optical path.

That is, a set of risk classification information A'1, A'2, ... Held by the optical channel group existing on the route for securing the backup optical path and already set as the backup optical path band. , A'n and the set B of the risk classification information of the input optical path connection request are logically φ (empty set), and the optical channel is searched first. In this search algorithm, when an optical channel suitable for securing a band as a backup optical path cannot be found, an optical channel search for the backup optical path is performed in the above third embodiment.

With this processing, in this embodiment,
Optical channel A24 of wavelength λ4 in fiber link 45
Is reserved as the band of the spare optical path requested to be set. In the optical channel A24, the band of the backup optical path (# 3- # 2- # 4- # 5- # 6) for the working optical path between the nodes # 3- # 6 accommodated in the fiber link 36 is also secured. It is in a state of being.

Further, in this embodiment, as in the case of the third embodiment, while a spare optical path band is shared by a plurality of working optical paths, a specific spare optical path band is broken by a network device failure. It can be set so that the working optical paths do not conflict. As a result, it is possible to suppress the amount of equipment of the spare optical path as compared with the third embodiment.

[0040]

As described above, the backup optical path band securing method and the optical path switching apparatus of the present invention can automatically set the backup optical path and effectively operate the shared protection system. The amount of equipment required for the spare optical path can be minimized. As a result, a low cost and highly reliable optical communication network can be constructed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an optical path switching device of the present invention.

FIG. 2 is a diagram showing a configuration example of an optical communication network according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a setting sequence of a working optical path.

FIG. 4 is a diagram showing a setting sequence of a backup optical path.

FIG. 5 is a diagram showing a configuration example of an optical switch section 2 according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a configuration example of an optical communication network according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a setting sequence of a working optical path.

FIG. 8 is a diagram showing a setting sequence of a backup optical path.

FIG. 9 is a diagram showing a configuration example of an optical switch section 2 according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a configuration example of an optical communication network in a third embodiment of the present invention.

FIG. 11 is a diagram showing a configuration example of an optical switch section 2 according to a third embodiment of the present invention.

FIG. 12 is a diagram showing a basic configuration of an optical communication network.

[Explanation of symbols]

1 Packet switch unit 2 Optical switch section 3 Integrated control function unit 31 Routing Processing Function Unit 32 Optical path setting management function 33 Link failure management function unit

Continued front page    (72) Inventor Katsuhiro Shimano             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Nobuaki Matsuura             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 5K021 BB01 CC13 DD04 FF01                 5K030 GA12 HA08 JA14 JL03 KA05                       KX23 LB08 MB04 MD01                 5K102 AA35 AA41 AA44 AD01 AL10                       LA44 MA05 MB11 NA01 PD16                       RB11

Claims (8)

[Claims] 1. A spare optical path band securing method for securing a band of a spare optical path to be switched when a working optical path becomes unavailable in a node of an optical communication network, wherein each node secures a band of the spare optical path. Occasionally, a backup optical path band characterized by notifying downstream nodes of identification information indicating that the optical path is a backup optical path and risk classification information to which the working optical path corresponding to the backup optical path belongs How to secure. 2. A spare optical path band securing method for securing a band of a spare optical path to be switched when a working optical path becomes unavailable in a node of an optical communication network, wherein each node is connected to a working optical path. , When the downstream node (or upstream node) that secures the band is notified of the danger classification information of the working optical path, the danger classification information of the link containing the node and the working optical path connected to the node is notified to this. Add upstream node (or downstream node)
A method for securing a backup optical path band, which comprises notifying a user. 3. The backup optical path band securing method according to claim 1, wherein the risk classification information is assigned to a single, a partial set or a whole set of links and nodes accommodating a working optical path. A method for securing a backup optical path band, which is characterized by a numerical value. 4. An optical path switching device comprising an optical path setting management function section for securing a band of a spare optical path to be switched when a working optical path set in an optical communication network becomes unusable. The setting management function unit holds the risk classification information of the optical path switching device and each link connected to the optical path switching device, and the risk classification information registered in the optical channel accommodated in the optical path switching device. A database,
A spare optical path setting processing unit that inputs the risk classification information notified from another optical path switching device when the spare optical path band is secured and outputs the band secured as a spare optical path and the newly updated risk classification information An optical path switching device comprising: 5. The optical path switching device according to claim 4, wherein the risk classification information registered in the optical channel is risk classification information to which a working optical path that secures the optical path as a backup optical path band belongs. An optical path switching device characterized by being present. 6. The optical path switching apparatus according to claim 4, wherein the backup optical path setting processing unit is a set of risk classification information held by an optical channel group existing on a route for which a backup optical path is to be secured. A1, A2, ..., An and a set B of risk classification information held by the working optical path of the protection optical path to be set
An optical path switching device, which is configured to search for an optical channel whose logical product is φ (empty set). 7. The optical path switching device according to claim 4, wherein the backup optical path setting processing unit exists on a route for which a backup optical path is to be secured, and has already been set as a backup optical path band. The logical product of the set A'1, A'2, ..., A'n of the risk classification information held by the existing optical channel group and the set B of the risk classification information of the input optical path connection request is φ (an empty set. ) The optical path switching device characterized by first searching the optical channel that becomes 8. The optical path switching device according to claim 4, wherein the risk classification information is assigned to a single, a partial set, or a whole set of links and nodes accommodating a working optical path. An optical path switching device characterized by being a numerical value.