JP2003318983A - Failure recovery method for optical cross-connect network - Google Patents

Abstract

(57) [Summary] In an optical cross-connect network controlled by GMPLS, failure recovery can be performed at high speed only by an optical switch unit, and when failure recovery cannot be performed only by an optical switch unit, a GMPLS control unit In this way, the failure recovery is performed by the control of the optical cross-connect network to cope with various connection forms of the optical cross-connect network. When a backup path can be secured by an optical switch unit when a failure occurs in communication of an optical path, the optical switch unit notifies a GMPLS control unit of failure information and switching information, and The control unit updates the label information and the path management information based on the failure information and the switching information from the optical switch unit. When that is not possible, the optical switch unit notifies only the failure information to the GMPLS control unit, and the GMPLS control unit updates the label information and the path management information based on the failure information from the optical switch unit. , Secure a backup path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure recovery method for an optical cross-connect network, which is an optical cross-connect network for performing optical cross-connect switching by GMPLS, and is capable of performing high-speed failure recovery only by an optical switch section. The present invention relates to a method of recovering a failure in an optical cross connect network.

[0002]

2. Description of the Related Art In recent years, due to the rapid spread of the Internet, optical communication technology has been attracting attention as a large-capacity backbone communication means. GMPLS (Generalize) is a technique for defining such an optical communication protocol.
d Multi Protocol Label Switching). GMPL
S is a WMP (Wavelength D) which is a conventional MPLS label.
ivision Multiplexing (wavelength division multiplexing) is applied to the wavelength, and it becomes possible to control the path in wavelength units by linking the router and the optical cross connect.
If a switching router equipped with PLS is used, it is possible to perform switching without changing the optical signal, and at the same time, the route selection can be realized by the IP technology.

By the way, as a recovery (protection / restoration) of the photonic network, a GMPLS-based recovery method discussed in IETF (Internet Engineering Task Force) and I
TU-T (International Telecommunication Union-Te
There are two physical layer-based recovery methods that are discussed in the lecommunication Sector).

When an optical path is controlled by using GMPLS, the data plane (physical layer) through which the main signal flows and the control plane (control layer) through which the GMPLS control signal flows are separated as the hierarchical structure of the network. There are two levels. According to this hierarchy, the GMPLS control unit is requested to notify the failure from the optical switch unit belonging to the physical layer and requests the optical switch unit to switch the path, thereby realizing the recovery of the optical path. The type of recovery is IETF draft (Generali
zed MPLS Recovery Mechanisms: draft-lang-ccamp-rec
overy-oo.txt), various recovery methods such as 1: 1 span protection, M: N path protection, path restoration, etc. are being studied.

For recovery mainly by the physical layer, IT
UT's ASTN (Automatic Switching Transport Ne
twork). 871 (Framework for optical transpo
rt network recommendations).

[0006]

In the above GMPLS-based recovery method, since GMPLS itself does not have a mechanism for detecting a link failure, it takes a long time to switch to the backup path after a failure occurs. There was a point.

Further, the above-mentioned physical layer-based recovery is
At present, it can be realized only in point-to-point or ring form, and a switching technique in mesh form has not been established. For example, SDH (Synchronous Digi
tal Hierarchy) APS (Automatic Protectio)
High speed switching in point form and ring form using n Switch) bytes is an existing technique, but in the mesh form, recovery technique such as switching to a detour route in case of failure is not established.

The present invention has been made to solve the above problems, and an object thereof is to provide an optical cross-connect network in which an optical path is controlled by GMPLS so that failure recovery can be performed at high speed only by an optical switch section. In addition, if failure recovery cannot be performed only with the optical switch, G
An object of the present invention is to provide a failure recovery method for an optical cross-connect network, which can cope with various connection configurations of the optical cross-connect network by performing failure recovery under the control of the MPLS control unit.

[0009]

In order to solve the above problems, the present invention controls an optical path by GMPLS and provides an optical cross connect network having a GMPLS control unit and an optical switch unit in the optical cross connect. In the failure recovery method, if a backup path can be secured by the optical switch section when a failure occurs in the communication of the optical path, the optical switch section sends the failure information and the switching information to the GM.
The PLS control unit is notified, and the GMPLS control unit updates the label information and the path management information based on the fault information and the switching information from the optical switch unit, and the communication of the faulty optical path is backed up. Try to recover from a disaster by doing a pass.

When it is impossible to secure a backup path by the optical switch unit, the optical switch unit notifies the GMPLS control unit of failure information, and the GMPLS control unit is notified.
The control unit updates label information and path management information based on the failure information from the optical switch unit, secures a backup path, and performs communication of the failed optical path by the backup path. Try to recover from the disaster.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS.

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. 1 to 19. (I) System Configuration of Optical Cross-Connect Network First, the system configuration of the optical cross-connect network of the present invention will be described with reference to FIGS. FIG. 1 is a network configuration diagram of an optical cross connect network of the present invention. FIG. 2 is a detailed configuration diagram of the optical cross connect network of the present invention. FIG. 3 is a diagram for explaining communication in the optical switch unit. FIG. 4 is a diagram for explaining an optical cross connect monitoring / control software configuration.

As shown in FIG. 1, the optical cross-connect network of the present invention includes optical cross-connects 11, 12 ,.
WDM (Wavelength Div) between "OXC"
ision multiplexing) lines 31, 32, ... Are connected in a mesh form, and routers 71-30 are connected to each OXC 11, 12 ,. The optical path management server 4 makes an optical path setting request to the OXCs 11, 12, ... Based on the request from the user. Then, an optical path is set between the routers by the trigger from the optical path management server 4.

The detailed structure of the OXC is shown in FIG. That is, the OXC 14 includes the GMPLS controller 51 and the optical switch unit 61, and the GMPLS controller belongs to the GMPLS as a network layer.
The control plane through which the control signal flows and the data plane to which the optical switch unit belongs and through which the main signal flows are composed of two layers. The GMPLS controller 51 is connected to the GMPLS controller 52 of the adjacent OXC and is connected to each GM.
Between PLS controllers, optical path management server 4 and each OX
It is assumed that the GMPLS controllers of C are interconnected at the IP level.

Upon receiving an optical path generation request from the optical path management server 4, the GMPLS controllers 51, 52 receive GM.
The PLS signaling protocol is used to determine the used wavelength and route of the optical path. Then, the optical switch is set based on the information, and the optical path between the routers 25 and 28 is established. As a GMPLS signaling protocol, TE-RSVP (Traffic Engineering-Resource) is used.
Reservation Protocol), CR-LDP (Constraint
Routing-Label Distribution Protocol) exists, but in this embodiment, CR-LDP will be used as the GMPLS signaling protocol for description.

The concept of communication in the optical switch section is shown in FIG.

The optical switch section has a function of switching a path for each wavelength. A plurality of WDM lines and router lines are connected to the optical switch section. WDM for WDM line
A route number and usable wavelengths are assigned as channel numbers for each line, and one route number and an individual channel number for each connecting router are assigned to a router line. The channels are divided into those for input and those for output. Then, the optical switch unit performs switching control between the input route and channel number designated by the GMPLS controllers 51 and 52 and the output route and channel number.

Communication in the above optical switch section is performed by GMPL.
This is performed by controlling the S controller.

The GMPLS controller 51 is equipped with a GMPLS control program 41, a routing protocol 42, and a forwarding DB 43 as shown in FIG.

The GMPLS control program 41 is a GMPLS
It is a program that performs processing such as LS protocol processing and optical switch control. The routing protocol 42 is
This is a protocol for automatically collecting the topology of the OXC network using the control plane and storing the result in the forwarding DB 43. Regarding the routing protocol 42, the OS discussed in IETF
It can be realized by using a technology of PF (Open Shortest Path First) optical extension. On the other hand, the optical switch unit 61 is equipped with an OXC monitoring / control program 44 for controlling the optical switch and monitoring / controlling the optical path.

The GMPLS controller 51 and the optical switch unit 61 are connected by the Ethernet 46 (Ethernet is a registered trademark), and the GMPLS control program 41 is used.
And message communication between the OXC monitoring and control program 44. By this message communication, control of the optical switch and notification of optical path failure / switching notification from the optical switch unit to the GMPLS controller are performed. (II) Data Structure Related to GMPLS Controller Next, the data structure related to the GMPLS controller will be described with reference to FIGS. This is GM
A table and a database (DB) used by the PLS control program 41. FIG. 5 is a schematic diagram showing the structure of the connection router management table. FIG. 6 is a schematic diagram showing the structure of the route management table. FIG. 7 is a schematic diagram showing the structure of the label status management table. Figure 8
FIG. 3 is a schematic diagram showing the structure of an optical path management table. FIG. 9 is a schematic diagram showing a forwarding DB structure.

The connection router management table is the OXC of its own.
Is a table for managing routers connected to the OXC, and as shown in FIG. 5, the channel number (field 501) and the IP address (field 502) of the router connected to its own OXC are set.

The route management table is a table for managing the route of the own OXC, and as shown in FIG. 6, the route number (field 601) assigned to the WDM line and its route. Adjacent GMPL connected first
The IP address (field 602) of the S controller is set. In the case of GMPLS, generally, the control signal and the main signal are on different lines, so the transmission line of the control signal (for example, Label Request message described later) does not match the line (route) of the generated optical path.
In the present embodiment, it is assumed that the route number and the IP address of the adjacent GMPLS controller have a one-to-one correspondence, and the route of the optical path to be generated can be specified from the source address of the control signal.

The label status management table is a table for managing the label status of the WDM line.
An input channel number (field 71) and a channel state (field 72) which are present for each M lines and can be used are set as shown in FIG. The label to be used is determined by the receiving side. In this embodiment, WDM is used.
The input channel (actually the wavelength) of the line corresponds to the label.

The optical path management table is a table for managing the optical paths set by the GMPLS controller, and includes an optical path ID (field 81), an input route number and a channel number (fields 82, 83), and an output path. Route number and channel number (fields 84, 85), and
The address (field 86) of the destination router of the path,
The path identification code flag (field 87) is set.

The path identification code is an Ingress / Core / Egress OXC to identify which type of OXC this OXC corresponds to the path.
Codes for identifying the three types of OXC are entered. The three types of OXC will be described in detail later.

Here, the route numbers and channel numbers set in the above table are set manually or by automatic configuration, and are set between the optical switch unit 61 and the GMPLS controller 51, and
It is assumed that the GMPLS controllers 51 and 52 adjacent to each other have negotiated each value.

The forwarding DB 43 is used for a routing protocol for determining the route (route) of the optical path, and is the IP of the destination router which is the destination.
Next hop GMP for address (field 91)
The IP address of the LS controller (field 92) is set by the routing protocol. (II
I) Generation of optical path in OXC Next, referring to FIGS.
The process when an optical path is generated by OXC using is described.

In GMPLS CR-LDP, a protocol for generating a bidirectional optical path between OXCs and a protocol for generating a unidirectional optical path with one request are prepared. First, the user will describe only the sequence for generating the directional optical path.
Based on the network configuration of the optical cross-connect network as shown in FIG. 1, a source router that is the entrance of the optical path and a destination router that is the exit of the optical path are specified and a request for the creation of the optical path is made. The source router and destination router each have an SA (Source Add) as an IP address.
ress) and DA (Destination Address) are assigned.

Then, the optical path management server 4 starts processing for generating an optical path between the source router and the destination router requested by the user. First, when the optical path management server 4 receives an optical path generation request from a user, the optical path management server 4 issues an optical path generation request to the GMPLS controller of the OXC to which the transmission source router is connected.

By the way, in GMPLS, three types of OXCs forming a network are provided, and a protocol is defined accordingly.

Ingress OXC is an OXC that is the entrance of an optical path, and conversely, Egress OXC.
C is an OXC at the exit of the optical path, and the intermediate OXC is called a Core OXC.

The following optical path generation processing is performed by Ingress
OXC, Egress OXC, Core OX
The processing is different for C and will be described separately. Also, the optical path generation processing described here is a standard sequence of GMPLS.

As described below, Ingress which is the entrance of the optical path, Core in the middle, and Eg which is the exit.
Messages are sequentially exchanged to the OXC of the lessons,
A one-way optical path from SA to DA requested by the path management server 4 is generated. (A) Optical Path Generation Processing by Ingress OXC First, the processing when an optical path is generated by the Ingress OXC will be described with reference to FIG. FIG. 10 shows O
Ingress OXC when generating an optical path with XC
It is a flowchart which shows the process of.

The Ingress OXC is an OXC to which a transmission source router is connected, and is an OXC which receives a request for optical path generation from the optical path management server 4.

When the GMPLS control program 41 of Ingress OXC receives the optical path generation request from the optical path management server 4, it first generates an optical path ID (step 101). This is an identifier for uniquely identifying the optical path of the OXC network and is used for managing the optical path. Here, as shown in FIG. 8, Ingress OXC is used.
GMPL to the IP address of the GMPLS controller
It is a value to which a consistent number locally managed by the S controller is added.

Next, the forwarding DB3 is searched by using the sent DA as a key, and the Label Req
uest message (hereinafter, simply “Label Req
The IP address of the GMPLS controller that transmits the "user" is acquired (step 102).

Label Request is a certain O
This is a message in which the XC requests another OXC to allocate a label for transmission. Label Request
The OXC, to which st is transmitted, responds to that by Label.
Mapping message (hereinafter, simply "Label
The assigned label (channel number, wavelength of the optical path) is notified by "Mapping").

First, the route management table is searched by using the obtained IP address of the GMPLS controller as a key to obtain the transmission route number of the optical path (step 10).
3).

Next, the optical path ID and DA are set as the parameters of the Label Request, and the GMP having the IP address of the transmission destination obtained in step 102 is set.
Send to LS controller (step 104), Lab
Waiting to receive el Mapping (step 10)
5).

Label sent to this OXC
For Mapping, the input channel (L) specified by the GMPLS controller that is the source of LabelMapping is set.
abel Mapping Seen from the receiving side, it becomes an output channel) is set.

Therefore, when the GMPLS controller of this OXC receives Label Mapping,
Based on the above parameters, an input route and channel number and an output route and channel number are specified and a switch setting request is issued to the optical switch section (step 1).
06).

That is, on the input side, the route number and channel number for the SA designated at the time of the optical path generation request, on the output side the route number for transmitting the Label Request, and the channel set in the received Label Mapping are set. Specify the number.

After setting the optical switch, the information of the set optical path is set in the optical path management table shown in FIG. 8 (step 107). That is, in this process,
The optical path ID generated in step 101, the input / output route number and channel number designated by the GMPLS controller for the optical switch unit, and the destination address (DA) of the destination router.
And a code indicating "Ingress" in the path identification code is set in each of the fields 81 to 87. Finally, the optical path ID is notified to the optical path management server 4, and the processing is ended. (B) Optical Path Generation Processing in Core OXC Next, processing when generating an optical path in Core OXC will be described with reference to FIG. FIG. 11 is a flowchart showing the processing of Core OXC when an optical path is generated by OXC.

Core OXC is Ingress O
It was OXC located in the middle of the pathway between XC and Egress OXC.

Therefore, it is located upstream of the path (Ingr
ess OXC or Core OXC) OXC
Will receive the Label Request from.

When the GMPLS control program 41 of the Core OXC receives the Label Request (step 111), the DMP that has been set is the same as the processing (steps 102 to 103) in the Ingress OXC.
Search forwarding DB with A as key
Bel Request The route management table is searched from the IP address of the GMPLS controller of the transmission destination and the IP address of the transmission destination GMPLS controller to acquire the transmission route number (steps 112 and 113). And
Send Label Request (Step 11
4), waiting for reception of LabelMapping (step 115).

OXC (Core O which is downstream of the path
XC or Egress OXC) Label
Upon receiving Mapping, Label Request
An input channel is secured by referring to the label status management table of the route that received st (step 116). La
The bell Request reception route number can be confirmed by searching the route management table shown in FIG. 6 for a route that matches the Label Request transmission source address.

There are four types of channel states: "vacant", "in use", "abnormal", and "reserved".
The S controller secures an empty channel here, and changes the channel status 72 of the label status management table shown in FIG. 7 corresponding to the secured input channel from "empty" to "in use". Then, after securing the input channel, an optical path generation request is issued to the optical switch section (step 117). For the input route and channel number,
Designate the route number that received the Label Request and the number of the input channel secured in step 116,
Label Request is used for the output route and channel number.
The route number that sent the est and the received LabelMa
Specifies the channel number set in pping.

Update the optical path management table (step 11)
8) After that, the secured input channel number is Labeled
Set to Mapping, Label Request
st Send to the GMPLS controller of the OXC upstream of the transmission source path.

Optical path management table update processing (step 1
18) is the same as the processing (step 107) in Ingress OXC, except that the set of path identification codes is a code representing “core”. (C) Optical path generation processing by Egress OXC Next, processing when an optical path is generated by Egress OXC will be described with reference to FIG. Figure 12 shows OXC
7 is a flowchart showing the processing of Egress OXC when generating an optical path in.

The Egress OXC is the OXC that is the exit of the optical path and is the OXC that is connected to the destination router of the destination.

The Egress OXC GMPLS control program 41 uses the OXC (Ingress) upstream of the path.
OXC or Core OXC) to Lab
When lRequest is received (step 121), the forwarding DB is searched using the set DA as a key. However, since it can be seen that the router with the DA IP address is connected to its own OXC,
Label R is determined to be a press OXC
The request is not transmitted (step 12)
2).

After the Egress OXC judges by itself, it refers to the label state management table of the route that received the Label Request and secures an input channel in an empty state. The state of the secured channel is updated from "free" to "in use", and the value of the channel state 72 of the label state management table is set (step 123). Then, the GMPLS controller issues an optical path setting request to the optical switch section (step 124).

At this time, L is added to the input route and channel number.
The route number that received the abel Request and the reception channel number secured in step 123 are designated, and the DA route number and the channel number are designated as the output route and the channel number.

Next, the optical path management table is updated (step 125), and the secured input channel number is Labeled.
Set it in the Mapping message and label it
G of the OXC upstream of the request source path
It is transmitted to the MPLS controller (step 126).

The optical path management table updating process is performed by Ingr
Processing by ess and Core OXC (Step 107,
Similar to 118), except that the set of path identification codes is a code representing "Egress". (III) Optical Path Failure Recovery Process Next, the failure recovery process when a failure occurs in the optical path of the optical cross-connect network of the present invention will be described with reference to FIGS. 13 and 19.

In the following, regarding the failure recovery processing when a failure occurs in the optical path of the optical cross connect network, the case where the switching to the backup path is performed mainly by the optical switch unit,
The case where the GMPLS controller is mainly used to switch to the backup path will be described below. (A) Case of Switching to Backup Path Mainly by Optical Switch Section First, a case of switching to backup path mainly by an optical switch section will be described with reference to FIGS. 13 to 16. FIG. 13 is an explanatory diagram of an example in which the optical switch unit mainly switches to the backup path. Figure 14
It is a schematic diagram of an event format. FIG. 15 is a schematic diagram of a backup path notification format. FIG.
6 is a flowchart showing a process of failure recovery when the GMPLS controller according to the first embodiment of the present invention receives an event.

In this case, when a failure occurs in the optical path and communication cannot be performed, switching to the backup path can be performed only by the optical switch section. For example, the fiber of the optical path in communication can be used. However, when the corresponding channel fails, other channels can be used.

At this time, by the operation of the OXC monitoring / control program 44 of the optical switch section, the failure recovery between the OXCs in which the failure has occurred is performed only by the optical switch section. Note that regarding this realization method, for example, S
It shall be realized by using the APS byte of DH transmission.

In the present embodiment, a free channel different from the original optical path can be used between the OXCs in which a failure has occurred, and only the operation of the OXC monitoring / control program 44 of the optical switch section is necessary. It shall be possible to switch to a free channel of.

For example, in the network configuration shown in FIG. 13, when a failure occurs in the channel number 1 between the OXC2 and OXC3, it is possible to switch to the idle channel number 3.

At this time, the OXC monitoring / control program 44 of the optical switch section is provided at the time of failure and at the time of failure recovery.
Event information is notified to the GMPLS control program 41 for each input / output channel.

The event format at this time is shown in FIG.
4, the event code (field 141),
Input / output code (field 142), event generation route number and event generation channel number (field 143,
144), switching code (field 145), switching route number, channel number (field 146,
147) is set in the area.

The event code is a code for identifying whether the event is a failure occurrence or a failure recovery. The input / output code is
It is a code that identifies whether the event is an input channel or an output channel. The switching code is a code for identifying whether or not switching has been performed, and "switching is performed",
It has three states: "no switching" and "no switching required".
Here, “switching performed” and “switching disabled” indicate whether the optical switch unit has switched to the backup path or not. Further, "no switching required" represents a failure in a place where a path is not set and which is not used and which does not need to be switched.

As shown in FIG. 13, Ingress
OXC1 OXC1, Core OXC OXC2, Eg
When OXC3 of less OXC is connected,
Channel number 1 for OXC2 and channel number 1 for OXC3
It is assumed that a failure has occurred in the route between. Here, what is called a primary path is a concept for a backup path, and is the original optical path that was originally used before a failure occurred.

In this example, O is set between OXC2 and OXC3.
The backup path is switched to the channel number 3 of XC2 and the channel number 3 of OXC3. To secure the switching route and channel number for the backup path,
Two ways are possible.

One is a method in which the OXC monitoring / control program 44 of the optical switch unit searches for and secures it by itself, and another is a method in which the GMPLS controller instructs the optical switch unit as shown in FIG. The switching route number (field 136) notified by the backup notification format and the switching channel number (field 13)
This is a method of holding the contents of 7) and using this information to switch to the backup path when a failure occurs.

When the switching is completed, each optical switch unit of the OXCs 2 and 3 notifies each GMPLS controller of this information as an event in the format shown in FIG.

GMPL in the GMPLS controller 51
When the S control program 41 receives the event, the S control program 41 shown in FIG.
The process shown in the flowchart of is executed.

First, when an event is received (step 1
50) Based on the input / output code of the event and the generation route number, it is checked whether or not the event is for the input channel of the WDM line (step 151).

Whether or not the faulty line is the WDM line can be checked by determining whether or not the event occurrence route is registered in the route management table. And WD
In the case of the input channel of the M line, the label state management table updating process (step 152) is performed as follows according to the event code.

When the event code is "fault", the label state management table is referenced by using the route number and the channel number of the fault as keys, and the state of the faulty input channel is changed from "in use" to " Update to "abnormal". And
If the switching code is "switching in progress", the status of the input channel that has been switched is changed from "empty" to "in use".
To update. If the event code is "failure recovery", the recovered route number and channel number are used as keys to refer to the label status management table, and the status of the recovered channel is updated from "abnormal" to "empty".

Next, the event code is checked (step 153), and in the case of "failure recovery", the processing ends.

When the event code is "fault",
The switching code is determined (step 154).

If the switching code is "switching unnecessary", the processing is terminated as it is, and if "switching is executed", the optical path management table is updated (step 15).
5). The update processing here refers to the input / output code 142, the route number 143 where the event has occurred, the channel number 144 where the event has occurred, the switching route number 146, and the switching channel number 147, and the route number of the new backup path, Set the channel number.

By the above processing, in the case of a failure that can be switched by the optical switch unit, even if the failure occurs, high-speed switching to the backup path can be performed and GM
The label status management table held by the PLS controller can be updated together with the status of the optical switch unit, and the information on the switched optical path can also be updated. Similarly, the label status management table can be updated together with the status of the optical switch section at the time of failure recovery or in the case of failure that does not require switching. (B) Case of Switching to Backup Path by GMPLS Controller Main Unit Next, a case of switching to backup path mainly by the optical switch unit will be described with reference to FIGS. 16 and 17 to 19. FIG. 17 is an explanatory diagram of an example in which the switching to the backup path is performed mainly by the GMPLS controller. Figure 18 Label WithDra
It is a flowchart which shows the process of the GMPLS controller of OXC which received the w message. FIG. 19 shows La
It is a flowchart which shows the process of the GMPLS controller of OXC which received the bell Release message.

In this case, when a failure occurs in the optical path and communication cannot be performed, the switching to the backup path cannot be performed only by the optical switch section. For example, the fiber of the optical path in communication is used. This is the time when the route becomes disconnected, and communication cannot be performed on the corresponding route, and a bypass route is needed to perform the intended communication.

Here, for example, it is assumed that all WDM lines between OXC2 and OXC3 have failed as shown in FIG.

When a failure occurs, the optical switch unit of the OXC2 must check that the output channel number 1 is a failure.
The optical switch section of the OXC3 indicates that the input channel number 1 is a failure, and the switching state is "switching is not possible".
Is notified to its own GMPLS controller.

GMPL in the GMPLS controller 51
When the S control program 41 receives an event (step 150), it checks whether the event is for the input channel of the WDM line from the input / output code of the event and the generation route number (step 151).

In this case, the OXC3 failure is the WD
This will cause an obstacle to the input channel of the M line (step 15
1) As described above, the GMPLS controller of the OXC3 rewrites the channel state 72 of the input channel number 71 of the label state management table to "in trouble" (step 152).

Next, the event code is checked (step 153), and if the event code is "fault", the switching code is judged (step 154).

Since the switching code is "not switchable", the faulty optical path is once deleted.

Therefore, the input / output code, the faulty route number, and the channel number are used as keys to search the target optical path from the optical path management table, and the optical path ID and the input / output route number are obtained. It is acquired and the corresponding entry is deleted (step 156). Then, a request is made to delete the optical path in which the failure has occurred (step 157).

In order to delete the optical path in the optical cross connect network, if the channel in which the failure has occurred is the input, GMP
The LS controller sends a Label Release message (hereinafter referred to as “Label Release”) to the GMPLS controller of the OXC on the egress side. On the other hand, if the failed channel is an output, the GMPLS controller will
Label Wi to the GMPLS controller of the side OXC
thdraw message (hereinafter "LabelWith"
called "draw").

Here, Label Release, L
label Withdraw is defined as a standard sequence of GMPLS.
Release is Egress from the Ingress side.
This is a GMPLS message sent to the user side, and is a path deletion request that is also used during normal operation. Label Wi
thdraw is a path deletion request at the time of abnormality transmitted from the Egress side to the Ingress side. La
Bel Release and Label Withdra
The IP address of the destination GMPLS controller of w can be obtained by referring to the route management table from the input / output route number of the optical path having the failure. Note that I
ngress and Egress OXC are end points of the optical path, and Label Releases
The e and Label Withdraw are not transmitted.

In the example of this embodiment shown in FIG. 17, OX
C2 GMPLS controller is L for OXC1
send abel Withdraw, GM of OXC3
The PLS controller is an Egress OXC,
Label Release is not transmitted.

Label Release and Label
An optical path ID to be deleted is set in l Withdraw, and the optical path to be deleted is specified by this value. L
abel Release, Label Withdr
Details of the aw process will be described later.

Then, in the case of Ingress OXC (step 158), the same SA as the deleted optical path,
The optical path generation process is performed again on the DA (step 159). At this time, it is assumed that the forwarding DB has already reflected the state at the time of the failure by the routing protocol, and the route (route) of the optical path to the DA has been updated so as to bypass the failure point. Ingres
The Label Request from the s OXC is sequentially transmitted to the OXC bypassing the failure, and the Egress OXC
Will be reached. That is, it can be said that the idea of this embodiment is to create a backup path at the time of a failure by a routing protocol.

In the case of the present embodiment shown in FIG. 17, L
abel Request is from OXC1 to OXC4
To OXC5, and from OXC5 to OXC3.

Ingress, Core, Egress
In OXC, Ing described with reference to FIG.
Processing for receiving an optical path generation request in the res OXC, FIG.
Label R at Core OXC as described in 1.
request reception processing, Egre described with reference to FIG.
By performing the Label Request reception process in ss OXC, as a backup path of the failure, S
An optical path from A to DA is generated.

In the optical path ID generation process (step 101) in the ingress OXC, an optical path ID different from the optical path ID deleted due to the failure is assigned. This is to prevent the conflict between the optical path deletion processing due to a failure and the optical path regeneration processing.

Next, referring to FIG. 18, Label Wit
The processing of the GMPLS control program 41 of GMPLS when the hdraw is received will be described.

First, when the Label Withdraw is received (step 171), the set path ID is used as a key to refer to the optical path management table to request the optical switch section to open the set switch (step 172). ). Then, for the input channel of the opened WDM line, the channel state of the label state management table is updated from "in use" to "empty" (step 1).
73). Further, the entry of the optical path for which the deletion request is made is deleted from the optical path management table (step 174).

Then, the type of the OXC is judged (step 175). If it is the ingress OXC, the processing is terminated, and if it is not the ingress OXC, the I
A Label Withdraw is transmitted to the GMPLS controller of the OXC on the ngress side (step 176).

Next, referring to FIG. 19, Label Rel
The processing of the GMPLS control program 41 of GMPLS when receiving the ease will be described.

First, when the Label Release is received (step 181), the optical path management table is referred to by using the set path ID as a key, and the optical switch section is requested to open the set switch (step 182). ). Then, for the input channel of the WDM line, the channel state of the label state management table is updated from "in use" to "empty" (step 18).
3). Further, the entry of the optical path for which the deletion request is made is deleted from the optical path management table (step 184).

Then, the type of the OXC is judged (step 185), and if it is Egress OXC, the processing is terminated, and if it is not Egress OXC, Eg.
A Label Release is transmitted to the next GMPLS controller of the OXC on the side of the pressure (step 186). By these processes, in the case of a failure that cannot be switched by the optical switch unit, the optical path disconnected by the failure is deleted once, and the input channel (label) of the WDM line used is released. It is carried out. Then, in the Ingress OXC, the optical path generation process is performed again to perform recovery.

By the above optical path generation processing, failure recovery processing, and optical path deletion processing, a highly reliable optical path can be efficiently provided to the user.

[Second Embodiment] A second embodiment of the present invention will be described below with reference to FIGS. 20 and 21. FIG. 20 is a schematic diagram of additional fields of the optical path management table. FIG. 21 is a GM according to the second embodiment of the present invention.
It is a flow chart which shows processing of failure recovery when a PLS controller receives an event.

In the first embodiment, when recovery cannot be performed in the optical switch section, the optical path in which a failure has occurred is labeled as Label Release and Label Wit.
Delete by hdraw and newly Lab between OXC
The backup path was re-established by l Request.

In the present embodiment, the GMPLS controller notifies the optical switch unit of the backup path secured in advance to generate the backup path and recover the failure.

When the optical path management server 4 accepts a path generation request from the user, it issues a working primary path generation request in the same manner as in the first embodiment. However, in addition to this, a backup path generation request is issued. OXC11 ~
Do for 15.

In the first embodiment, the optical path route is generated according to the forwarding DB 43 created by the routing protocol 42. However, in the first embodiment, the optical path management server 4 specifies the path route. To This is the GMPLS signaling protocol (CR
-LDP, TE-RSVP) can specify a path path, and can be realized by using that function.

The generation of the primary path and the backup path will be described below separately in terms. (I) Primary Path Generation Process First, the primary path generation process will be described.

Ingress, Core, Egress
The generation processing of the primary path in the OXC is performed by the optical path generation processing of the first embodiment (FIG. 10, FIG. 11, FIG.
The sequence is basically the same as that of 2), and only the processing different from that of the first embodiment will be described below.

The optical path management server 4 sends the SA to the Ingress OXC connected to the destination router.
And DA, path of primary path, path switch OXC
And path merge OXC are specified. For the path path,
The IP address of the GMPLS controller passing from the ingress OXC to the egress OXC is designated in order. Specify this path route, and
In the path switch OXC and the path merge OXC, the IP address of the GMPLS controller in the OXC is used as the identifier of the OXC.

Here, the path switch OXC is defined as an OXC in which the primary path and the backup path are branched, and the path merge OXC is defined as an OXC in which the primary path and the backup path are merged. To do.

Taking the relationship between the primary path, backup path and OXC shown in FIG. 17 as an example, the path switch OXC is OXC1 and the path merge OXC is OXC3.
Becomes

The path designated by the optical path management server 4 is I
Label Req by ngless OXC
It is added to est and transmitted. And Core OXC
Then, this path information is added to Label Request and transmitted.

In the first embodiment, Ingress,
Core OXC optical path generation processing (FIGS. 10 and 11)
In the above, although the forwarding DB was searched when the Label Request transmission destination was determined (steps 102 and 112), in the second embodiment, the path designated by the optical path management server 4 or the Label Reservation is used.
It is changed so as to be determined from the path information set in quest. Also, regarding the information of the path switch OXC and the path merge OXC designated by the optical path management server 4, L
It is added to the abel Request and notified to all OXCs on the primary path path.

Although the parameters must be set in the optical path management table when the primary path is generated, the optical path management table used by the GMPLS controller of the present embodiment is the optical path shown in FIG. 8 of the first embodiment. For the management table, the fields 201 to 201 shown in FIG.
204 is added. .

Path switch OXC (field 201)
The path merge OXC (field 202) is added to the Label Request as described above and notified. Ingress and Cor
In e and Egress OXC, it is set in each optical path management table update process (steps 107, 118, 125) at the time of primary path generation.

The switching route number and the switching channel number (fields 203 and 204) are the route number and the channel number to be switched as a backup path, and are set in the backup path generation processing described later. Note that this is effective only when the path switch O, which is a branching OXC, is used.
Only the XC and the path merge OXC, and other OXCs in which the primary path and the backup path do not branch are not aware of this parameter.

By the above processing, the optical path management server 4
A primary path is generated between SA and DA on the path designated by. Further, information on the path switch OXC and the path merge OXC is set in the entries of the path management table. (II) Backup Path Generation Processing Next, the backup path generation processing will be described.

After the primary generation request, the path management server 4 issues a backup path generation request to the path switch OXC by designating the path of the backup path and the path ID of the corresponding primary path.

Here, the path information of the backup path and the path ID of the primary path are Label Request.
It is added to st and transmitted.

Backup path Ingress, Co
The re and Egress OXC perform the same processing as the primary path generation processing. Here, the ingress OXC of the backup path is the path switch OX.
Egress OXC is path merge OXC. In the path switch OXC and the path merge OXC, the entry of the corresponding primary path is searched from the path management table, and the switching route number and the switching channel number are set in the fields 203 and 204 as the switching information to the backup path. At this time, the path switch OXC sets the route number and the channel number of the output of the backup path, and the path merge OXC
Then, set the input route number and channel number of the backup path.

Since no fault has occurred at the stage of this pack-up path generation processing, the path switch OXC
Then, the GMPLS controller of the path merge OXC does not actually make a path generation request to the optical switch unit. The path generation request to the optical switch unit is made when the failure of the following item occurs.

In the process of securing the input channel (label) of the path merge OXC, since the path is not actually set, the channel status of the label status management table is set to "reserved".

By the above processing, the optical path management server 4
A backup path is generated in the designated path between the path switch OXC and the path merge OXC designated by the above. Then, in the path switch OXC and the path merge OXC, the switching information to the backup path is set in the path management table.

The resource (label) of the backup path is "in use" or "reserved", and GMPLS is generated by an optical path generation request from another user.
Not used by the controller. Also, the optical switch unit does not know the information of the “reserved” input channel, but the path setting has already been performed for the input channel and the output channel on the opposite side, and the optical switch unit autonomously operates. Never use reserved channels. (III) Processing When Failure Occurs Next, processing of the GMPLS controller when a failure occurs will be described.

This is the processing until a failure occurs in the primary path and the GMPLS controller switches to the backup path.

The case of a fault that can be switched by the optical switch unit alone is the same as in the first embodiment. The problem in this embodiment is that the GMPLS controller unit mainly switches to the backup path. Is.

When a failure occurs, the event information is notified to the GMPLS controller as in the first embodiment.

Then, the GM in the GMPLS controller
Upon receiving the event, the PLS control program 41 executes the process shown in the flowchart of FIG.

As for the processes (steps 210 to 215) other than the event process in which the switching code is "not switchable",
Processing of the first embodiment 1 shown in FIG.
Since it is the same as that of (155), only the case where the switching code is "cannot switch" will be described.

If the switching code is "not switchable" (step 214), it is checked whether the faulty OXC is the path switch OXC or the path merge OXC (step 216). This refers to the path switch OXC and path merge OXC corresponding to the failure path from the optical path management table, and determines the IP of the own GMPLS controller.
It can be determined by checking whether it matches the address.

The faulty OXC is the path switch OX.
In the case of C or path merge OXC, the switching information of the optical path management table is referred to and a switching request is issued to the optical switch section (step 217).

Also in the path switch OXC, the path merge OX
If it is not C, a notification message (hereinafter, simply referred to as "notification") is transmitted to the adjacent GMPLS controller (step 218).

Notification is CR-LD.
This is an event notification message defined in P. By adding the failed optical path ID to the notification, the path switch O
Notify XC and path merge OXC. notifica
The destination of the transmission depends on whether the failure occurrence route is the Ingress side or the Egress side. On the ingress side, the adjacent GMP located in the direction of the egress side
If it is sent to the LS controller and is on the Egress side,
It transmits to the GMPLS controller located in the direction of the Ingress side.

GM that has received the notification
GMPLS control program 41 in PLS controller
Performs the same processing as the processing shown in FIG. 21 (steps 216 to 218). Own OXC is pass switch OXC
Or path merge OXC. Then, switch to the backup path or noti
The transmission process of the fication is performed.

The notification destination is I
When it is received from the egress side, the Egr is sent to the adjacent GMPLS controller located in the egress side.
When received from the ess side, the same is transmitted to the adjacent GMPLS controller located in the direction of the Ingress side.

In this way, the notification
n is Ingress and Eg from the faulty OXC.
It is propagated by hop-by-hop toward the OXC on the pressure side, and is transmitted to the path switch OXC and the path merge OXC. Then, the failed optical path is switched to the backup path and recovery is performed.

[0136]

According to the present invention, in an optical cross connect network in which an optical path is controlled by GMPLS, failure recovery can be performed at high speed only by the optical switch section, and failure recovery can be performed only by the optical switch section. When there is no such error, it is possible to provide a failure recovery method for the optical cross-connect network, which can cope with various connection configurations of the optical cross-connect network by recovering the failure under the control of the GMPLS control unit.

[Brief description of drawings]

FIG. 1 is a network configuration diagram of an optical cross connect network of the present invention.

FIG. 2 is a detailed configuration diagram of an optical cross connect network of the present invention.

FIG. 3 is a diagram for explaining communication in an optical switch unit.

FIG. 4 is a diagram for explaining an optical cross connect monitoring / control software configuration.

FIG. 5 is a schematic diagram showing the structure of a connection router management table.

FIG. 6 is a schematic diagram showing the structure of a route management table.

FIG. 7 is a schematic diagram showing the structure of a label status management table.

FIG. 8 is a schematic diagram showing the structure of an optical path management table.

FIG. 9 is a schematic diagram showing a forwarding DB structure.

FIG. 10 shows Ingre when an optical path is generated by OXC.
It is a flowchart which shows the process of ss OXC.

FIG. 11: Core when generating an optical path by OXC
It is a flowchart which shows the process of OXC.

FIG. 12 is an Egres when an optical path is generated by OXC.
It is a flowchart which shows the process of s OXC.

FIG. 13 is an explanatory diagram of an example in which switching to a backup path is performed mainly by an optical switch unit.

FIG. 14 is a schematic diagram of an event format.

FIG. 15 is a schematic diagram of a backup path notification format.

FIG. 16 is a flowchart showing a process of failure recovery when the GMPLS controller according to the first embodiment of the present invention receives an event.

FIG. 17 is an explanatory diagram of an example in which a GMPLS controller mainly switches to a backup path.

FIG. 18 is a flowchart showing the processing of the OXC GMPLS controller that has received the Label With Draw message.

FIG. 19 is a flowchart showing the processing of the GMPLS controller of the OXC that received the Label Release message.

FIG. 20 is a schematic diagram of additional fields of the optical path management table.

FIG. 21 is a flowchart showing a process of failure recovery when the GMPLS controller according to the second embodiment of the present invention receives an event.

[Explanation of symbols]

11-15 ... Optical cross connect, 21-30 ... Router,
31 to 37 ... WDM line, 4 ... Optical path management server, 71
~ 73 ... Router line. 51, 52 ... GMPLS controller, 61, 62 ... Optical switch section 41 ... GMPLS control program, 42 ... Routing protocol, 43 ... Forwarding DB, 44 ... OXC monitoring / control program.

Continued front page    F term (reference) 5K030 JL03 KX20 LA17 LB08 MB16                       MC07 MD01 MD06                 5K102 AA44 AL10 LA06 LA08 LA43                       PD17 RB11

Claims (6)

[Claims] 1. A GMPLS (Generalized Multi Protoc)
ol Label Switching) to control the optical path,
In a failure recovery method for an optical cross connect network having a GMPLS control unit and an optical switch unit in the optical cross connect, a backup path can be secured by the optical switch unit when a failure occurs in communication of the optical path. Occasionally, the optical switch unit may provide fault information and switching information to GMPL.
Notifying the S control unit, the GMPLS control unit updates label information and path management information based on the fault information and switching information from the optical switch unit, and the communication of the faulty optical path is A failure recovery method for an optical cross-connect network, characterized in that failure recovery is performed by using a backup path. 2. The GMPLS control unit notifies the optical switch unit of label information and path management information in advance in order to secure a backup path.
A method for recovering from a failure in the described optical cross-connect network. 3. The optical switch section notifies the GMPLS control section of failure recovery information when the failure is recovered, and the GMPLS control section sets the label information to be empty, in use, abnormal, or reserved. Managed in four states, and the failure information from the optical switch unit, the switching information,
The fault recovery method for an optical cross-connect network according to claim 1, wherein the label information is updated based on the fault recovery information. 4. When it is impossible to secure a backup path by the optical switch unit, the optical switch unit notifies the GMPLS control unit of failure information, and the GMPLS control unit receives the fault information from the optical switch unit. Update the label information and path management information based on the failure information,
2. The method for recovering from a failure in an optical cross-connect network according to claim 1, wherein a backup path is secured and communication of the failed optical path is performed by the backup path. 5. When it is impossible to secure a backup path by the optical switch unit, the GMPLS control unit deletes the faulty optical path and deletes it in the optical cross-connect that is the path generation source. The method for recovering a fault in an optical cross-connect network according to claim 4, wherein the optical path is regenerated. 6. A failure recovery method for an optical cross-connect network, wherein an optical path is controlled by GMPLS, and an optical cross-connect has a GMPLS control section and an optical switch section. And a failure occurs in the communication of the optical path, it is impossible to secure a backup path by the optical switch unit, the optical switch unit notifies the GMPLS control unit of failure information, and the GMPLS The control unit updates the label information and the path management information based on the fault information from the optical switch unit, and the GMPLS control unit notifies the GMPLS control unit of the optical cross connect to perform the switching, and the switching The GMPLS control unit of the optical cross connect that performs the backup is based on the information of the backup path that it holds. A failure recovery method for an optical cross-connect network, characterized in that an up path is secured and communication of the failed optical path is performed by the backup path.