METHOD OF RECOVERING FAULT IN MULTILAYER NETWORK AND APPARATUS THEREOF

A method of recovering a fault in a multilayer network and an apparatus thereof are provided, the method including obtaining lower layer backup path setting information through a signaling message that is used for a label based path setting, setting a backup path at a lower layer based on the obtained lower layer backup path setting information, and upon detecting a fault at the lower layer, performing a protection switching through the set backup path at the lower layer.

DETAILED DESCRIPTION

The following description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. In addition, terms described below are terms defined in consideration of functions in the present invention and may be changed according to the intention of a user or an operator or conventional practice. Therefore, the definitions must be based on content throughout this disclosure.

FIG. 1is a diagram illustrating an example of setting an LSP at a multilayer network applied with the present disclosure.

Referring toFIG. 1, a multilayer network includes multiple layers, for example, the multiple layers are divided into a lower layer and an upper layer in terms of levels, and the dividing of the layers is determined as relative to a current layer.

The multilayer network includes nodes each representing a network device. InFIG. 1, a N1 node110to a N5 node150are illustrated as an example. Each of the nodes110,120, . . . , and150manages a resource of at least one layer among multiple layers. Each of the nodes110,120, . . . , and150operates as a management system to manage resources between layers.

A label switched path (hereinafter, referred to as an LSP) representing a forwarding path may be set between nodes, and a packet is transmitted through the set LSP. There is a signaling protocol that is transmitted to all nodes on the LSP to reserve resources. The signaling protocol may be a resource reservation protocol (hereinafter, RSVP). The RSVP transmits/receives a path message and a Resv message between nodes, thereby setting a path used to transmit traffic. For the convenience of description, the following description will be made in relation to the RSVP.

The present disclosure relates to (1) a method of transmitting a lower layer backup LSP setting information through a RSVP signaling message, (2) a method of determining a frame format of information about setting a lower layer backup LSP, (3) a method of setting a lower layer backup LSP, and (4) a method of recovering a fault when a fault occurs in a lower layer in a multilayer network apparatus including multilevel LSPs and a system thereof.

In accordance with an embodiment of the present disclosure, it is assumed that LSPs from the N1 node110to the N5 node150represent forward paths set at layer 3, and there is no available resource of layer 3 interface connected from the N2 node120to the N5 node150. When the N1 node110representing a source node desires to establish an LSP with the N5 node150representing a destination node to transmit data therebetween, the N1 node110calculates a transmission path (N1-N2-N4-N5) by performing a routing based on interface information that is collected in advance, and transmits a path message representing a RSVP signaling message to is the N2 node120.

Similar to the N1 node, the N2 node120performs a routing based on interface information collected at layer 3, but there is no available interface connected to the N4 node140representing a next node. Accordingly, the N2 node120holds the RSVP signaling message, and checks whether an available resource capable of setting an LSP to the N4 node140is present in layer 2 that is a lower layer with respect to the N2 node120. If the available resource is present, the N2 node120sets a new lower layer LSP (N2-N3-N4) from the N2 node120to the N4 node140. On the contrary, if the available resource is not present in layer 2, the N2 node120checks whether an available resource is present at layer 1 that is a lower layer with respect to layer 2, and if the available resource is present, the N2 node120sets a LSP at layer 1. If an available resource for setting an upper layer LSP is not present even at the lower most layer, the LSP setting is regarded as a failure, and a path error message representing a path setting failure message is transmitted to the N1 node110representing the source node.

After the lower layer LSP setting is completed, the N2 node120sets a hierarchy LSP based on the lower layer LSP. That is, a lower layer LSP is first set, and an upper layer LSP is set on the lower layer LSP, and then a RSVP message is transmitted to the N4 node140. In the above embodiment, two hierarchy LSPs are generated. The first hierarchy LSP is N2-N3-N4, and the second hierarchy LSP is N1-N2-N4-N5. As the resource and interface information are shared by setting the multilevel LSPs as described above, the LSP setting failure is minimized and an efficient data transmission is achieved.

In accordance with the present disclosure, when a LSP is set at a lower layer, it is determined whether to set a backup LSP (BLSP), and if determined to set the BLSP, the BLSP at the lower layer is set. In addition, a transmitting node transmits lower layer backup LSP setting information to a receiving node through a RSVP signaling message, such that the receiving node automatically performs a lower layer backup LSP setting as well as a protection recovery at the occurrence of a fault by use of the lower layer backup LSP setting information.

Further, in a case in which a fault occurs at a multilayer network including multilevel LSPs, it is not that the fault is recovered through an upper layer backup LSP by notifying a source node of fault information, but that a partial recovery is performed through a lower layer backup LSP, so that a packet loss and a delay time for recovering the fault are reduced, thereby responding to the fault in a rapid manner.

FIG. 2is a flowchart showing a method of setting a backup LSP at a lower layer and recovering a fault when a fault occurs in accordance with an embodiment of the present disclosure.

Referring toFIG. 2, a lower layer working LSP is set in operation200, and if a RSVP signaling message including lower layer backup LSP setting information is received from a transmitting node, it is determined whether to set a backup LSP based on the received lower layer backup LSP setting information, and a backup LSP is set based on information about a protection recovery type used to set the backup LSP in operation210.

If a LSP fault is sensed at a lower layer in operation220, it is determined whether a backup LSP is set at the lower layer, and if the backup LSP is set at the lower layer, a protection switching is performed through the backup LSP at the lower layer without ascending to an upper layer in operation230. On the contrary, if the backup LSP is not set at the lower layer, a protection switching is performed through a backup LSP at an upper layer. In this case, the respective layers may be formed as hierarchy lower layers leading to the lowermost layer. That is, the lower layer is determined as relative to a current layer.

FIG. 3is a diagram illustrating a configuration of an attribute format of a lower layer backup LSP setting in accordance with an embodiment of the present disclosure.

In detail,FIG. 3shows an embodiment of an attribute format of a lower layer backup LSP setting that is included in an independent attribute of a RSVP signaling message to notify whether to set a lower layer backup LSP while transmitting additional information for the setting.

A C-Num field300of the attribute format of the lower layer backup LSP setting distinguishes an attribute value included in an RSVP message. A C-Type field310indicates a TLV value of attribute distinguished by the C-Num. Since one attribute may include a plurality of TLVs, a Type field320is used to distinguish each TLV. That is, the Type field320in accordance with the present disclosure is set as a TLV value used to set a lower layer backup LSP. A Length field330is a field representing the entire size of a TLV, and includes sizes of the Type field320, a Length field330, a LL_BLSP field340, and a P_Type field350. A Reserved field360is padded with zero.

The LL_BLSP field340may have a size of 2 bits, and indicate whether to set a lower layer backup LSP while indicating a lower layer backup LSP setting option. In accordance with an embodiment of the present disclosure, the value of <00> of the LL_BLSP field340indicates that the lower layer backup LSP is not set, and when the lower layer backup LSP is set, the value of <10> of the LL_BLSP field340indicates that the lower layer backup LSP is set if an available resource is present and that the lower layer backup LSP is not set if an available resource is not present, and the value of <11> of the LL_BLSP field340indicates that an entire LSP setting is failed if the setting of the backup LSP is failed due to the absence of an available resource when the lower layer backup LSP is set.

The P_Type field350indicates a protection recovery type applied when the backup LSP is set. In accordance with an embodiment of the present disclosure, depending on the value of the P_Type field350, recovery schemes 1:1, 1+1, M:N, and 1:N are selected. In this case, the sizes of the fields340and350related to the lower layer backup LSP setting may be defined depending on the circumference of the network.

The 1:1 scheme is a recovery scheme in which one backup path is allocated to one working path. In order to prevent waste of resources allocated to backup paths, the 1:N scheme is provided to allow one backup path to be shared among other working paths. The 1:N scheme is extended to the M:N scheme capable of recovering a multi-link fault. When a fault occurs, a protection switching of traffic is performed through the backup path.

The 1+1 scheme is similar to the 1:1 scheme in that a backup path is provided for one working path, but is characterized in that the same data is transmitted not only through a use path but also through an alternative path. That is, a receiving end receives the same data through two paths.

FIG. 4is a diagram illustrating a configuration of a TLV format of a lower layer backup LSP setting information in accordance with an embodiment of the present disclosure.

In detail,FIG. 4shows an embodiment of a format that is defined when a lower layer backup LSP setting information is included in a TLV of an LSP_ATTRIBUTE or an LSP_REQUIRED_ATTRIBUTES of an RSVP signaling message.

Since the LSP_ATTRIBUTE or LSP_REQUIRED_ATTRIBUTES may include a plurality of TLVs, a Type field400has a TLV ID value to set the lower layer backup LSP. A Length field410has a value corresponding to sizes of the Type400, Length410, LL_BLSP420, and P_Type430. The descriptions of the LL_BLSP420, P_Type430, and Reserved440, which represent fields related to the lower layer backup LSP setting, are identical to the above descriptions ofFIG. 3, and therefore will be omitted.

Meanwhile, the above embodiment described with reference toFIGS. 3 and 4are illustrated only as an example of the present disclosure, and information whether to set a lower layer backup LSP, information about a protection recovery type, and information about a processing method at the failure of the setting of the lower layer backup LSP may be delivered through explicit or connotative connection of at least one of thereof, and may be defined in a separate frame format including these information.

FIG. 5is a flowchart showing a method of setting a backup LSP at a lower layer in accordance with an embodiment of the present disclosure.

First, if an LSP setting at a lower layer is determined, a corresponding node sets a working LSP in operation500. Subsequently, it is determined whether the setting of the working LSP is successful in operation510, and if the setting of the working LSP setting is not successful, an upper layer LSP setting is also regarded as a failure and thus a LSP setting failure message is sent to a source node in operation560.

On the contrary, if the setting of the working LSP is successful, it is determined whether a lower layer backup LSP is to be set in operation520and a backup LSP setting is needed in operation550, and a backup LSP is set depending on a protection recovery type in operation530. Depending on the format of the lower layer backup setting information, operation520and operation550may be identified through a single piece of information, or as shown inFIG. 5, may be identified through separated pieces of information. If determined from operation550that the setting of the backup LSP is needed and the backup LSP setting is failed, the lower layer LSP setting is regarded as a failure and thus an LSP failure message is transmitted in operation560, and the setting ends.

FIG. 6is a diagram illustrating a configuration of a protection switching apparatus6in a multilayer network in accordance with an embodiment of the present disclosure.

Referring toFIG. 6, the protection switching apparatus6includes a signaling process unit600, a path setting unit610, and a protection switching unit620. The protection switching apparatus6may be located on a node of a multilayer network.

The signaling process unit600analyzes a lower layer backup path setting information of a received signaling message. The lower layer backup path setting information may include information whether to set a backup path at a lower layer, information about a protection recovery type, and information about a processing method at a failure of the setting of a backup path at a lower layer. The information whether to set the backup path at the lower layer is divided into a no-setting of a lower layer backup path, a setting of a lower layer backup path if an available resource for setting the path is present when the backup path at the lower layer is set, a no-setting of a lower layer backup path if an available resource for setting the path is not present when the backup path at the lower layer is set, and a failure of an entire path setting if the setting of the backup path is failed due to an absence of an available resource when the backup path at the lower layer is set.

The path setting unit610sets the backup path at the lower layer based on the lower layer backup path setting information that is analyzed through the signaling process unit600. In accordance with an embodiment of the present disclosure, the path setting unit610sets a working path at a lower layer, transmits a path setting failure message to a transmitting node if the setting of the working path at the lower layer is failed, and determines whether to set a backup path at the lower layer if the setting of the working path is successful. The path setting unit610sets the backup path at the lower layer based on the information about the protection recovery type if determined to set the backup path at the lower layer, and transmits a path failure message to the transmitting node if the setting of the backup path at the lower layer is failed.

The protection switching unit620is configured, if a fault at the lower layer is sensed, to perform a protection switching through the backup path of the lower layer that is set through the path setting unit610.

In accordance with an embodiment of the present disclosure, the protection switching unit620is configured, if a fault at a lower layer is sensed, to determine whether a backup path is set at a lower layer. The protection switching unit620, if determined that the backup path is set at the lower layer, performs a protection switching through the backup path at the lower layer, and if the backup path at the lower layer is not set, performs a protection switching through a backup path at an upper layer.

The present invention can be implemented as computer readable codes in a computer readable record medium. The computer readable record medium includes all types of record media in which computer readable data are stored. Examples of the computer readable record medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage. Further, the record medium may be implemented in the form of a carrier wave such as Internet transmission. In addition, the computer readable record medium may be distributed to computer systems over a network, in which computer readable codes may be stored and executed in a distributed manner.