JPH1127325A - ATM communication network - Google Patents

Abstract

(57) [Summary] [Problem] Traffic between a plurality of LANs by ATM increases as the scale of the LANs increases, and it becomes difficult to deal with them. SOLUTION: LANs are connected to a center network in a star shape. This center network is an optical wavelength routing network in which a transfer route is fixedly set for each wavelength. When a destination cell other than the own LAN arrives, the cell is transferred to a route other than the route from which the cell arrives. Thereby, this cell can finally reach the LAN of the desired destination. By periodically transmitting and receiving OAM cells, a failure in the transmission path can be detected and recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM (Asynchronou).
s Transfer Mode) Used for communication. The present invention provides a plurality of A
Local area network by TM (hereinafter referred to as LAN)
It is suitable for use in large-scale ATM communication networks including In particular, the present invention relates to a technology for detecting and recovering from a failure in a transmission line in communication between LANs by ATM.

[0002]

2. Description of the Related Art In an ATM communication network, a large-scale ATM communication network is constructed by interconnecting LANs using a plurality of ATMs. This conventional example is shown in FIG.
This will be described with reference to FIG. FIG. 21 shows a conventional ATM communication network.

In a conventional ATM communication network, for example, LAN
When the communication terminal 10 connected to 2-1 transfers a cell to the communication terminal 20, first, the communication terminal 20 as a destination is searched in the LAN 2-1. Is recognized, then LA
The cell is transferred to N2-2. Here, the communication terminal 20 as the destination is searched, and if it is recognized that the communication terminal 20 does not exist on the LAN 2-2, the cell is transferred to the LAN 2-3. By repeating such a procedure, the cell finally arrives at the communication terminal 20 connected to the LAN 2-4. If such a flow of cells occurs constantly, it is dealt with by providing a dedicated line 30.

[0004] In addition, the bridges 40 to 42 connecting the LANs 2-1 to 2-4 are connected to the cells that frequently pass through the bridges 40 to 42. Since it is possible to learn whether or not the cell exists, the cell transfer can be performed smoothly.

[0005]

SUMMARY OF THE INVENTION Such a conventional AT
In the M communication network, as the scale of the LANs 2-1 to 2-4 increases, the amount of traffic passing through the bridges 40 to 42 also increases.

For this purpose, it is necessary to provide a dedicated line 30 or to increase the line capacity of the bridges 40 to 42.
If the size of the is large, it will not be able to cope.

Further, the traffic distribution of the bridges 40 to 42 is not always distributed to the respective bridges 40 to 42 on average. -3, the traffic is biased in order from the bridge 42 closer to the LAN 2-4 to the bridge 41 and the bridge 40. Therefore, the capacity of each of the bridges 40-42 must be able to cope with the maximum traffic that can occur in the entire ATM communication network.

As described above, in the conventional ATM communication network, it is difficult to flexibly cope with traffic expected to increase in the future.

The applicant of the present application has filed a prior application (Japanese Patent Application No. 9-1496).
No. 14, unpublished at the time of filing the present application) proposed an ATM communication network using an optical wavelength routing network. The ATM communication network using the optical wavelength routing network is provided with a center network accommodating each LAN in a star shape so as to flexibly cope with expansion of each LAN. By using a fixed optical wavelength routing network for the center network, a large-scale ATM communication network can be easily realized without using a complicated device such as a center server.

FIG. 22 is a diagram showing failure detection in an ATM communication network. As shown in FIG. 22, in the cross-connect devices XC1 to XC3 which handle cells of electric signals, for example, a cross-connect device XC1 and a cross-connect device are used. X
When a failure that causes a disconnection of the transmission path with C2 occurs, the cross-connect device XC2 detects the failure and sends an AIS (Alarm Indication Signal) further downstream.

However, FIG. 23 is a diagram showing a transmission line disconnection state in an optical wavelength routing network. As shown in FIG. 23, optical wavelength cross-connect devices 3-1 to 3-, which handle optical cells as optical signals. In 3, the optical wavelength cross-connect device 3-2 and other optical wavelength cross-connects are provided even if a failure occurs in which the transmission path is disconnected between the optical wavelength cross-connect device WXP1 and the optical wavelength cross-connect device 3-2. The device cannot detect a failure.

The main cause is that the cross-connect devices XC1 to XC3 shown in FIG.
Are provided with a physical transmission line using an electric cable. Therefore, it is easy to constantly or periodically monitor the disconnection of the physical transmission path. For example, a low-level monitoring voltage is applied constantly or periodically, and if this voltage value becomes 0, it can be determined that disconnection has occurred.

However, between the optical wavelength cross-connect devices 3-1 to 3-3 handling optical signals shown in FIG.
Although a physical transmission line is provided by an optical fiber or simply a space, the optical wavelength cross-connect device 3-2 does not transmit an optical cell and does not arrive even if the physical transmission line is disconnected. Alternatively, it is difficult to identify whether the physical transmission path is disconnected and no optical cell arrives. There are also known techniques for detecting a failure by providing a special function to the optical wavelength cross-connect devices 3-1 to 3-3. However, all of these techniques use an SDH failure detection function or an operation system. Functions other than layers are used.

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and performs, in an ATM layer, fault detection and recovery control of a transmission line in an optical wavelength routing network which can flexibly cope with an increase in traffic. ATM that can do
It is intended to provide a communication network. SUMMARY OF THE INVENTION An object of the present invention is to provide an ATM communication network capable of easily configuring a large-scale and large-capacity network.

[0015]

SUMMARY OF THE INVENTION The present invention provides an AT having a plurality of local area networks based on ATM and a center network for transferring cells between the plurality of local area networks.
M communication network. A feature of the present invention is that it comprises means for converting a cell arriving from the local area network into an optical cell having a predetermined wavelength according to its destination and transferring the optical cell into the center network, wherein the center network comprises Optical wavelength routing means in which the output path of the optical cell is set according to the wavelength of the optical cell to be transmitted, wherein the transferring means includes means for generating a maintenance cell for detecting a failure in the transmission path; Means for transmitting the maintenance cell to a predetermined destination at a predetermined cycle, and means for determining that the transmission path has failed when the maintenance cell does not arrive at a predetermined cycle. In the center network, it is preferable that an output route of the optical cell is fixedly set.

As a result, each LAN is connected to the center network in a star configuration, and it is possible to avoid a decrease in throughput due to the passage of traffic. The most important feature of the present invention is to realize an ATM communication network which does not require a complicated device such as a center server by using an optical wavelength routing means for the center network. Therefore, as compared to the case where a complicated device such as a center server is provided, the maintenance and inspection of the center network is not troublesome, and the probability of occurrence of a failure or the like is low.
As described above, an optical wavelength routing network having a low probability of occurrence of a failure is used. However, in the present invention, a failure can be detected and restoration of a failed portion can be promptly executed.

The cell may be an optical cell already at the LAN stage, or may be an electric signal cell at the LAN stage and converted into an optical cell by the transfer means.

Preferably, the transfer means includes a table in which a local area network as a destination and wavelength information for transferring to the local area network are recorded.

It is desirable that a specific wavelength be assigned to the maintenance cell. Alternatively, it is preferable that a specific payload type identifier be written in the maintenance cell.

In the center network, a working route and a protection route are set, and the transfer means, when there is a transmission line in which a failure is detected by the determining means, sets the working route set in the transmission line as a protection route. Means for generating a switching cell in which a switching instruction for switching to a route is written and transferring the switching cell to a node serving as an end point of the working route;
The transfer means included in the node serving as the end point includes:
The switching cell is received, the working route is switched to the protection route, a new switching cell is generated according to the wavelength assigned to the protection route, and the switching cell is transferred to a node serving as a starting point of the transmission line on which the failure is detected. It is preferable that the transfer means included in the node serving as the starting point include means for receiving the switching cell and switching the working route to the protection route.

At this time, it is desirable to have a table in which wavelength information respectively assigned to the working route and the protection route is recorded.

A table in which wavelength information assigned to the working route and band information of the working route are recorded;
A configuration may also be provided that includes a means for setting a backup route in accordance with the determination result of the determining means or the arrival of the switching cell and updating the band information in this table. This makes it possible to flexibly set a backup route after a failure is detected.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of the first embodiment of the present invention. FIG. 2 is a block diagram of a main part of the access control unit according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating a destination table of the access control unit.

The present invention relates to a LAN 2-1 to ATM-2 based on ATM.
This is an ATM communication network provided with a center network 50 for transferring cells between the LANs 2-1 to 2-4.

Here, the feature of the present invention is that L
Access control units 1-1 to 1-4 as means for converting cells arriving from ANs 2-1 to 2-4 into optical cells of a predetermined wavelength according to their destinations and transferring them into the center network 50.
The center network 50 includes an optical wavelength cross-connect device 3-1 as an optical wavelength routing means in which the output route of the optical cell is set according to the wavelength of the input optical cell.
To 3-4, and the access control units 1-1 to 1-4 include:
OA as a maintenance cell for detecting a transmission line failure
An OAM cell generator 34 as a means for generating an M (Operation And Maintenance) cell; a transmission timer 22 as a means for transmitting the OAM cell to a predetermined destination at a predetermined cycle; This is provided with a reception timer unit 24 as means for determining that the transmission path has failed when it does not arrive in a periodic manner. The center network 50 is
The output path of the optical cell is fixedly set.

The access control units 1-1 to 1-4 have LANs 1-1 to 1-4 as destinations and the LANs 1-1 to 1-4.
4 includes a destination table T in which wavelength information to be transferred to the destination table 4 is recorded.

[0027]

【Example】

(First Embodiment) A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall configuration diagram of the first embodiment of the present invention. The first embodiment of the present invention is an embodiment relating to failure detection. In FIG. 1, reference numerals 1-1 to 1-4 denote an access control unit, reference numerals 2-1 to 2-4 denote a LAN by ATM, and reference numerals 3-1 to 3-1.
Reference numeral 3-4 denotes an optical wavelength cross-connect device, and reference numeral 50 denotes a center network. A solid line indicates a working route of the access control units 1-1 to 1-4, and a broken line indicates a backup route. The traffic between LANs is distributed to the access control units 1-1 to 1-1 which are distributed.
Routing processing is performed by 1-4.

For example, the traffic from the LAN 2-1 to the LAN 2-4 can be set as the working route by selecting the λ1 by the access control unit 1-1.
The data is automatically transferred to the access control unit 1-4 via 1, 3, 2 and 3-4 and transferred to the LAN 2-4. At this time, the optical wavelength cross-connect device 3-2 converts the wavelength λ1 into the wavelength λ2. By thus performing the fixed wavelength conversion, one wavelength is consistently provided from the start point to the end point. The degree of freedom of design can be improved as compared with the case of performing.

If the wavelength λ2 is selected by the access control unit 1-1, the optical wavelength cross-connect 3
-1, 3-3, and 3-4, the data is automatically transferred to the access control unit 1-4 and transferred to the LAN 2-4. At this time, the optical wavelength cross-connect device 3-3 fixedly converts the wavelength λ2 to the wavelength λ1. Thus, the access control unit 1
In the case of -1, recovery from the failure of the working route, that is, switching to the protection route can be performed only by selecting the optical wavelength.

The cells shown in FIG. 1 represent OAM cells. Neighboring access control units 1-1 and 1-2, 1-1
And 1-3, 1-2 and 1-4, and 1-3 and 1-4 transmit and receive OAM cells at regular intervals, thereby confirming the normality of connection with an adjacent access control unit. Perform detection.

FIG. 2 is a block diagram of the access control unit according to the first embodiment of the present invention. The transmission timer unit 22 sends a signal to the controller unit 21 at regular intervals. When a signal is sent from the transmission timer unit 22 to the controller unit 21, the controller unit 21 transmits the OAM cell to all the directly accessible access control units. For example,
If it is the access control unit 1-1, it transmits to the access control units 1-2 and 1-3.

In the access control units 1-1 to 1-4, the OAM cell determination unit 23 determines whether the arrival cell is an OAM cell. FIGS. 4 and 5 are diagrams for explaining the failure determination by the OAM cell. As shown in FIG. 4, the OAM cell is transmitted using a specific wavelength λ ₀ when transmitting the OAM cell. A method of determining by selecting only the signal of λ _{0 in} the cell determining unit, and as shown in FIG.
Generally, the OAM cell has the same VPI value and V as the user information cell.
There is a method of using a specific payload type identifier (PTI) that has a CI value and has a specific payload type identifier (PTI) that can be distinguished from the user information cell.

When the method shown in FIG. 4 is adopted, FIG.
In addition to the working and protection routes shown in (1), it is necessary to further provide a route with a wavelength λ0 for transferring OAM cells. By providing the route based on the wavelength λ0 in parallel with the working route, a failure of the working route can be detected.

The access control unit having received the OAM cell,
The OAM cell determination unit 23 recognizes the reception of the OAM cell, and resets the reception timer 24. Therefore, when the OAM cell does not arrive due to a failure in the transmission line, the reception timer 24 is not reset, and the reception timer 24 eventually expires. The controller 21 receives this time-up signal as a trigger and detects that a failure has occurred in the transmission path.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is an overall configuration diagram of the second embodiment of the present invention. FIG. 7 is a block diagram of a main part of an access control unit according to the second embodiment of the present invention. FIG. 8 is a diagram showing a wavelength management table. The second embodiment of the present invention is an embodiment relating to failure recovery. The configuration of the access control unit used here is a configuration in which a wavelength management table 25 is added to the configuration of the access control unit of the first embodiment of the present invention.

In FIG. 6, the optical wavelength cross-connect device 3
It is assumed that a failure has occurred in the transmission line between -1 and 3-2. The access control unit 1-2 cannot receive the OAM cell from the access control unit 1-1, and after a predetermined time, a trigger as a time-up signal is transmitted from the reception timer 24 to the controller unit 21 as shown in FIG. . Then, it recognizes from the wavelength management table 25 shown in FIG. 8 that there is a route not terminated by itself at the wavelength λ2 in addition to a route terminated by itself at the wavelength λ1, and reception to the access control unit 1-4 is performed. The switching cell for reception is generated by the reception switching cell generator 26 and transmitted using the wavelength λ2. The transmitted receiving switching cell is an optical wavelength cross-connect device 3-
Access control unit 1 automatically via 2 and 3-4
4 is transferred.

FIG. 9 is a block diagram of a main part of the access control section 1-4 according to the second embodiment of the present invention. FIG. 10 is a view showing a route management table of the access control section 1-4. The control unit 1-4 includes a reception switching cell determination unit 27.
Confirms that it has received a reception switching cell destined for itself, it manages a route in which it is a transmission / reception end in FIG.
The transmission switching cell addressed to the access control unit 1-1 is transmitted from the information in the route management table 28 shown in FIG. Then, the current route is deleted from the route management table 28, and the backup route is set as the current route.

The transmitted transmission switching cell is automatically transferred to the access control unit 1-1 via the optical wavelength cross-connect device 3-4, 3-3, 3-1. In the optical wavelength cross-connect device 3-3, the wavelength λ1 is converted to a wavelength λ2.

FIG. 11 is a block diagram of a main part of the access control unit 1-1 according to the second embodiment of the present invention, and FIG. 12 is a diagram showing a route management table of the access control unit 1-1. As shown in FIG. 11, when the access switching unit 1-1 confirms that the transmission switching cell determination unit 31 has received the transmission switching cell addressed to itself, the access control unit 1-1 deletes the working route from the route management table 28, and Failure recovery is performed by setting the 28 spare routes as working routes.

(Third Embodiment) FIG. 13 shows a third embodiment of the present invention.
This will be described with reference to FIG. In the first and second embodiments of the present invention, it has been described that the bandwidth of the backup route is reserved in advance, but in the third embodiment of the present invention, FIG.
It is assumed that the bandwidth of the backup route has not been secured.

FIG. 13 is a block diagram of a main part of the access control section 1-4 according to the third embodiment of the present invention. The access control section 1-4 uses the reception switching cell determination section 27 to perform reception switching for itself. When it is confirmed that the cell has been received, the band of the backup route has not yet been secured.
By reducing the bandwidth of the other routes from, the bandwidth up to the access control unit 1-3 is secured and the transmission switching cell is transmitted to the access control unit 1-3. Then, as shown in FIG. 10, the current route is deleted from the route management table 28, and the backup route is set as the current route.

FIG. 15 is a diagram showing the format of the transmission or reception switching cell. As shown in FIG. 15, the transmission switching cell contains information on the access control unit serving as the destination. The unit 1-3 knows that the transmission switching cell is not addressed to itself. Therefore, the access control unit 1-3 secures a band up to the access control unit 1-1 which is the adjacent access control unit and the destination as described above, and transmits the transmission switching cell to the access control unit 1-1. I do. FIG. 14 shows an access control unit 1-1 according to the third embodiment of the present invention.
The access control unit 1-1, which has received the transmission switching cell addressed to itself, deletes the working route from the route management table 28 as shown in FIG. The failure recovery is performed by setting the backup route of the current route as the working route.

(Fourth Embodiment) FIG. 16 shows a fourth embodiment of the present invention.
This will be described with reference to FIG. FIG. 16 is an overall configuration diagram of the fourth embodiment of the present invention. In the first to third embodiments of the present invention, OA
Although the transmission / reception of the M cell has been described as being performed on the entire scale in the center network 50 and performed between all the access control units 1-1 to 1-4, the fourth embodiment of the present invention provides This is an example performed only between control units.

For example, by transmitting and receiving OAM cells at regular intervals between the access control units 1-1 and 1-4, the connectivity between the access control units 1-1 and 1-4 can be confirmed. Thereby, a failure is detected. The access control unit is the same as that described in the first embodiment of the present invention shown in FIG. However, the OAM cell is transmitted only to the access control unit on the receiving side.

According to the fourth embodiment of the present invention, since failure detection can be performed locally, for example, failure detection can be performed only for a route that frequently communicates. Alternatively, failure detection may not be performed on a route that transmits and receives information of a type that is not greatly affected even if a failure occurs and communication is interrupted.
As a result, there is no need to secure a band for transmitting OAM cells to a route where the need for failure detection and prompt failure recovery is low, and network resources can be used effectively.

(Fifth Embodiment) FIG. 17 shows a fifth embodiment of the present invention.
19 to FIG. The fifth embodiment of the present invention is an embodiment relating to a failure detection and failure recovery procedure which is autonomously performed by the access control unit 1-4 in response to a failure between the optical wavelength cross-connect devices 3-1 and 3-2. This embodiment uses a specific access control unit 1-1 as described in the fourth embodiment.
This is applied to the case where the failure detection by the OAM cell is performed only between the points 1 and 4. That is, this embodiment is an example of a procedure for detecting a failure by itself without receiving a notification from another switching cell.

FIG. 17 is an overall configuration diagram of the fifth embodiment of the present invention. FIG. 18 shows an access control unit 1- of the fifth embodiment of the present invention.
FIG. 4 is a block diagram of a main part of Nos. 1 to 1-4. FIG. 19 is a diagram showing a wavelength management table according to the fifth embodiment of the present invention. FIG.
As shown in FIG. 7, if a failure occurs in the transmission line between the optical wavelength cross-connect devices 3-1 and 3-2, FIG.
8 is the access control unit 1-1.
After a certain period, a trigger as a time-up signal is transmitted from the reception timer unit 24 to the controller unit 21. Controller unit 21
In response to this trigger, the transmission switching cell generator 29 generates a transmission switching cell. This transmission switching cell is transmitted using the wavelength λ1 via the backup route with reference to the wavelength management table 25 shown in FIG.

The transmission switching cell arrives at the access control unit 1-1 via the optical wavelength cross-connect devices 3-4, 3-3 and 3-2. In the access control unit 1-1, the arrival of the transmission switching cell is recognized by the transmission switching cell determination unit 31, and the working route is switched to the backup route according to the procedure already described.

(Sixth Embodiment) FIG. 20 shows a sixth embodiment of the present invention.
This will be described with reference to FIG. In the sixth embodiment of the present invention, similarly to the fifth embodiment of the present invention, the failure detection and the autonomous access control unit 1-4 is performed by the access control unit 1-4 in accordance with the failure between the optical wavelength cross-connect devices 3-1 and 3-2. It is an example about a failure recovery procedure. This embodiment is similar to that described in the fourth embodiment.
OA only between specific access control units 1-1 and 1-4
This is applied when failure detection is performed by M cells. That is, this embodiment is an example of a procedure for detecting a failure by itself without receiving a notification from another switching cell. In the sixth embodiment of the present invention, it is assumed that the bandwidth of the backup route is not reserved in advance.

FIG. 20 is a block diagram of a main part of the access control section 1-4 according to the sixth embodiment of the present invention. The access control unit 1-4 cannot receive the OAM cell from the access control unit 1-1, and after a predetermined period, a trigger as a time-up signal is transmitted from the reception timer unit 24 to the controller unit 21. Since the bandwidth of the backup route has not been secured,
By reducing the bandwidth of another route from the bandwidth management table 33, the bandwidth up to the access control unit 1-3 is secured, and the transmission switching cell is transmitted to the access control unit 1-3. The following is the same as the procedure described above.

(Summary of Embodiment) In the embodiment of the present invention, in order to make the explanation easy to understand, each of the access control units 1-1 to 1-1 is explained.
The configurations 1-4 have been illustrated and described as if they were different configurations. In addition, there is a portion illustrated and described as if the access control units at the same position have different configurations in each embodiment. However, in practice, each of the access control units 1-1 to 1-4 can be configured to have a common configuration so that the access control units 1-1 to 1-4 can take arbitrary positions depending on the situation at that time.

[0052]

As described above, according to the present invention,
Failure detection and recovery control of a transmission line in an optical wavelength routing network that can flexibly cope with an increase in traffic can be performed at the ATM layer. According to the present invention, a large-scale and large-capacity network can be easily configured.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram of a main part of an access control unit according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a destination table of an access control unit according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining failure determination by an OAM cell.

FIG. 5 is a diagram for explaining failure determination by an OAM cell.

FIG. 6 is an overall configuration diagram of a second embodiment of the present invention.

FIG. 7 is a block diagram of a main part of an access control unit according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a wavelength management table of an access control unit according to the second embodiment of the present invention.

FIG. 9 is a block diagram of a main part of an access control unit according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a route management table of an access control unit according to a second embodiment of the present invention.

FIG. 11 is a block diagram of a main part of an access control unit according to a second embodiment of the present invention.

FIG. 12 is a diagram showing a route management table of an access control unit according to the second embodiment of the present invention.

FIG. 13 is a block diagram of a main part of an access control unit according to a third embodiment of the present invention.

FIG. 14 is a block diagram of a main part of an access control unit according to a third embodiment of the present invention.

FIG. 15 is a diagram showing a format of a transmission or reception switching cell.

FIG. 16 is an overall configuration diagram of a fourth embodiment of the present invention.

FIG. 17 is an overall configuration diagram of a fifth embodiment of the present invention.

FIG. 18 is a block diagram of a main part of an access control unit according to a fifth embodiment of the present invention.

FIG. 19 is a diagram showing a wavelength management table according to a fifth embodiment of the present invention.

FIG. 20 is a block diagram of a main part of an access control unit according to a sixth embodiment of the present invention.

FIG. 21 is a diagram showing a conventional ATM communication network.

FIG. 22 is a diagram showing failure detection in an ATM communication network.

FIG. 23 is a diagram showing a transmission path disconnection state in the optical wavelength routing network.

[Explanation of symbols]

 1-1 to 1-4 Access control unit 2-1 to 2-4 LAN 3-1 to 3-4 Optical wavelength cross-connect device 10, 20 Communication terminal 21 Controller unit 22 Transmission timer unit 23 OAM cell determination unit 24 Reception timer Unit 25 Wavelength management table 26 Switching cell generator for reception 27 Switching cell determination unit for reception 28 Route management table 29 Switching cell generator for transmission 30 Dedicated line 31 Switching cell determination unit for transmission 32 Cell transmission unit 33 Band management table 34 OAM Cell generator 40-42 Bridge 50 Center network T-table XC1-XC3 Cross-connect device

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04J 14/00 H04B 9/00 E 14/02

Claims (8)

[Claims] 1. An ATM communication network comprising a plurality of local area networks and a center network for transferring cells between the plurality of local area networks, wherein an ATM communication network includes a cell arriving from the local area network. Means for converting into an optical cell having a wavelength determined according to the destination and transferring the converted light into the center network, wherein the output path of the optical cell is set according to the wavelength of the input optical cell. An optical wavelength routing unit, wherein the transferring unit includes a unit for generating a maintenance cell for detecting a failure in a transmission line, and a unit for transmitting the maintenance cell to a predetermined destination at a predetermined cycle. Means for determining that the transmission line has failed when the maintenance cell does not arrive at a predetermined cycle. 2. The ATM communication network according to claim 1, wherein an output route of said optical cell is fixedly set in said center network. 3. The ATM communication network according to claim 1, wherein said transfer means includes a table in which a destination local area network and wavelength information to be transferred to the local area network are recorded. 4. The ATM communication network according to claim 1, wherein a specific wavelength is assigned to said maintenance cell. 5. The ATM communication network according to claim 1, wherein a specific payload type identifier is written in said maintenance cell. 6. A working route and a protection route are set in the center network, and the transfer unit, when there is a transmission line in which a failure is detected by the determining unit, a working route set in the transmission line. Including a means for generating a switching cell in which a switching instruction for switching to the backup route is written and transferring the switching cell to a node serving as an end point of the working route, wherein the transferring means included in the node serving as the end point includes The switching cell is received, the working route is switched to the protection route, a new switching cell is generated according to the wavelength assigned to the protection route, and the switching cell is transferred to a node serving as a starting point of the transmission line on which the failure is detected. The transfer means included in the node serving as the starting point receives the switching cell and switches the working route to the protection route. 2. The AT according to claim 1, further comprising
M communication network. 7. The ATM communication network according to claim 6, further comprising a table in which wavelength information assigned to each of the working route and the protection route is recorded. 8. A table in which wavelength information assigned to a working route and band information of the working route are recorded, and a spare route is set according to a judgment result of the judging means or arrival of the switching cell. 7. The ATM communication network according to claim 6, further comprising means for updating band information of the table.