COMMUNICATION DEVICE
A communication device comprising: a checking unit checking whether a bandwidth from the ingress of first path down to the egress thereof and a bandwidth from the ingress of second path down to the egress thereof as a standby of a partial zone of first path, are established or not; a route information management unit generating, when the checking unit confirms that the bandwidth from the ingress of first path down to the egress thereof and the bandwidth from the ingress of second path down to the egress thereof as the standby of the partial zone of first path are established, route maintaining information for maintaining the bandwidth of the partial zone of first path; and a transmission unit transmitting the route maintaining information generated by the route information management unit to the neighboring communication device on the side of the egress of first path.
Latest FUJITSU LIMITED Patents:
- COMPUTER-READABLE RECORDING MEDIUM STORING DATA MANAGEMENT PROGRAM, DATA MANAGEMENT METHOD, AND DATA MANAGEMENT APPARATUS
- COMPUTER-READABLE RECORDING MEDIUM HAVING STORED THEREIN CONTROL PROGRAM, CONTROL METHOD, AND INFORMATION PROCESSING APPARATUS
- COMPUTER-READABLE RECORDING MEDIUM STORING EVALUATION SUPPORT PROGRAM, EVALUATION SUPPORT METHOD, AND INFORMATION PROCESSING APPARATUS
- OPTICAL SIGNAL ADJUSTMENT
- COMPUTATION PROCESSING APPARATUS AND METHOD OF PROCESSING COMPUTATION
This application claims the benefit of Japanese Patent Application No. 2007-227525 filed on Sep. 3, 2007 in the Japanese Patent Office, the disclosure of which is herein incorporated in its entirety by reference.
BACKGROUND OF THE INVENTION1. Field of the INVENTION
The present invention relates generally to a communication device and a network system in an MPLS (Multi Protocol Label Switching) network. The present invention relates more particularly to a communication device and a network system, which perform switching back based on a local Revertive system by setting up a communication path (LSP (Label Switched Path)) for an FRR (Fast ReRoute, which is a facility backup technique)) using RSVP-TE (Resource Reservation Protocol-Traffic Engineering).
2. Description of the Related Art
The MPLS is a packet forwarding technique using the label switching system. The MPLS involves utilizing a piece of identifying information (label) having a short fixed length in place of an IP header as routing information when forwarding a packet received by a router from another router to a different router. An MPLS-based routing method is exemplified by the FRR. The FRR is a method of preparing a communication path employed as a standby path beforehand in the MPLS network, then switching over, if a fault occurs in an active communication path, the path to the standby path, and recovering the communications. The FRR prepares the standby path beforehand and enables the communications to be quickly recovered from the fault.
Herein, the head-end node of the LSP (which is the node H in the case of the LSP#1 and is the node A in the case of the LSP #2) is referred to as an Ingress node, while the tail-end node of the LSP (which is the node T in the case of the LSP#1 and is the node C in the case of the LSP #2) is termed an Egress node. Further, the node corresponding to a branch point of the LSP (which is the node A in
The node A is configured as the PLR explicitly, and the node C is configured as the MP explicitly, and thereafter the respective LSPs are set up. The Protected LSP is set up by assigning the node A serving as the Ingress node a piece of route information of a route extending from the node H down to the node T as the Egress node via the node A, the node B and the node C.
Moreover, similarly, the Backup LSP is set up by assigning the node A serving as the Ingress node a piece of route information of a route extending from the node A down to the node C as the Egress node via the node D. Thereafter, the PLR (node A) generates an associative relation between the Protected LSP and the Backup LSP, i.e., a pair relation between the Protected LSP (LSP#1) and the Backup LSP (LSP#2).
As a result, a detour (bypass) route against occurrence of a link fault between the node A and the node B, a link fault between the node B and the node C or a node fault of the node B, is generated in a protection zone (between the node A, the node B and the node C) on the Protected LSP.
In a normal state, data traffic from the node H is carried via the Protected LSP to the node T.
This switch-back is referred to as a Local Revertive method. The Backup LSP might not be more optimal path than the Protected LSP (in terms of a delay and a bandwidth). Hence, in order to transmit the data traffic invariably along the optimal path (in terms of the delay and the bandwidth), the path is switched back to the Protected LSP from the Backup LSP.
- [Patent document 1] Japanese Patent Laid-Open Publication No. 2005-39362
When recovered from the link fault occurring between the node A and the node B in
It is an object of the present invention to provide a technology enabling switch-back to a middle zone from a second communication path in a network system including a first communication path and a second communication path generated so as to bypass the middle zone of the first communication path, data sent from an ingress of the first communication path being forwarded to an egress of the first communication path via the second communication path in place of the middle zone during a fault in the middle zone.
The present invention adopts the following means in order to solve the problems given above.
Namely, a first mode of the present invention is a communication device, in a communication network including: a first communication path, along which a plurality of communication devices is cascade-connected, having an ingress and an egress; and a second communication path, along which the plurality of communication devices is cascade-connected, the communication devices existing both ends thereof being different from each other on the first communication path, having its ingress corresponding to the communication device, of the communication devices at both ends, located on the side of the ingress of the first communication path and its egress corresponding to the communication device, of the communication devices at both ends, located on the side of the egress of the first communication path, the communication device being the communication device located at the ingress of the second communication path, comprising:
a checking unit checking whether a bandwidth from the ingress of the first communication path down to the egress thereof and a bandwidth from the ingress of the second communication path down to the egress thereof as a standby of a partial zone of the first communication path, are established or not;
a route information management unit generating, when the checking unit confirms that the bandwidth from the ingress of the first communication path down to the egress thereof and the bandwidth from the ingress of the second communication path down to the egress thereof as the standby of the partial zone of the first communication path are established, route maintaining information for maintaining the bandwidth of the partial zone of the first communication path; and
a transmission unit transmitting the route maintaining information generated by the route information management unit to the neighboring communication device on the side of the egress of the first communication path.
Further, a second mode of the present invention is a communication device, in a communication network including: a first communication path, along which a plurality of communication devices is cascade-connected, having an ingress and an egress; and a second communication path, along which the plurality of communication devices is cascade-connected, the communication devices existing both ends thereof being different from each other on the first communication path, having its ingress corresponding to the communication device, of the communication devices at both ends, located on the side of the ingress of the first communication path and its egress corresponding to the communication device, of the communication devices at both ends, located on the side of the egress of the first communication path, the communication device being the communication device located on the first communication path between the ingress and the egress of the second communication path, comprising:
a reception unit receiving route maintaining information for maintaining a bandwidth in a partial zone of the first communication path from the neighboring communication device on the side of the ingress of the first communication path;
a route information management unit stored with the route maintaining information; and
a transmission unit transmitting the route maintaining information to the neighboring communication device on the side of the egress of the first communication path.
Still further, a third mode of the present invention is a communication device, in a communication network including: a first communication path, along which a plurality of communication devices is cascade-connected, having an ingress and an egress; and a second communication path, along which the plurality of communication devices is cascade-connected, the communication devices existing both ends thereof being different from each other on the first communication path, having its ingress corresponding to the communication device, of the communication devices at both ends, located on the side of the ingress of the first communication path and its egress corresponding to the communication device, of the communication devices at both ends, located on the side of the egress of the first communication path, the communication device being the communication device located at the egress of the second communication path, comprising:
a reception unit receiving route maintaining information for maintaining a bandwidth in a partial zone of the first communication path from the neighboring communication device on the side of the ingress of the first communication path; and
a route information management unit stored with the route maintaining information.
According to the modes of the present invention, when the standby communication path is established in the partial zone of the main communication path, the communication device residing in the zone with the standby communication path established can be notified of this purport.
Moreover, according to the first mode of the present invention, the communication device may further comprise a reception unit receiving, from the neighboring communication device on the side of the egress of the first communication path, route error information showing occurrence of a link fault on the egress side from the neighboring communication device on the side of the egress of the first communication path, wherein when the checking unit confirms that the bandwidth from the ingress of the first communication path down to the egress thereof and the bandwidth from the ingress of the second communication path down to the egress thereof as the standby of the partial zone of the first communication path are established and when the reception unit receives, from the neighboring communication device on the side of the egress of the first communication path, the route error information showing the occurrence of the link fault on the egress side from the neighboring communication device on the side of the egress of the first communication path, the transmission unit may transmit the route maintaining information to the neighboring communication device on the side of the egress of the first communication path.
Furthermore, according to the second mode of the present invention, if the link fault occurs between the self communication device and the neighboring communication device on the side of the ingress of the first communication path, the transmission unit may transmit the route maintaining information stored in the route information management unit to the neighboring communication device on the side of the egress of the first communication path.
According to the modes of the present invention, if the link fault occurs on the first communication path, the bandwidth on the first communication path can be maintained by continuing to transmit the route maintaining information.
According to the present invention, it is feasible to provide a technology enabling switch-back to the middle zone from the second communication path in the network system including the first communication path and the second communication path generated so as to bypass the middle zone of the first communication path, the data sent from the ingress of the first communication path being forwarded to the egress of the first communication path via the second communication path in place of the middle zone during the fault in the middle zone.
An embodiment of the present invention will hereinafter be described with reference to the drawings. A configuration in the embodiment is an exemplification, and the present invention is not limited to the configuration in the embodiment.
EmbodimentTo begin with, a standard operational example of the communication network in
<<Setup of Protected LSP>>
An Object of the Path Message will be explained. The Object of the Path Message contains a Session Object (SO), a Fast Reroute Object (FRO), a Session Attribute Object (SAO), an Explicit Route Object (ERO), and an HOP Object.
The SO is an Object for identifying a session of the LSP. The SO is stored with pieces of information (IP addresses etc) of the Ingress node and the Egress node of the LSP.
The FRO is an Object which requests the setup with the LSP serving as the Protected LSP. The FRO is stored with a bandwidth needed in the LSP. The FRO is invariably contained in the Path Message of the Protected LSP.
The SAO is an Object representing a session attribute. The SAO is stored with information for requesting Local Protection.
The ERO is an Object for explicitly specifying a route of the LSP. The ERO is stored with an IP address of an Interface for receiving the Message.
The HOP Object is an Object showing a sender of the Message. The HOP Object is stored with an IP address of an Interface for transmitting the Message.
An Object of the Resv Message will be described. The Object of the Resv Message contains the Session Object (SO), a Record Route Object (RRO) and an HOP Object.
The SO is the Object for identifying the session of the LSP. In the same way as the SO of the Path Message is, the SO is stored with the information (IP addresses etc) for specifying the Ingress node and the Egress node of the LSP.
The RRO is an Object showing a sender of the Message. The RRO is stored with an IP address of an Interface for transmitting the Message. Further, the RRO is stored with reserved label information. Still further, the RRO is stored with information showing whether the Local Protection can be utilized or not.
The HOP Object is an Object showing a sender of the Message. The HOP Object is the same as the HOP Object of the Path Message.
The Path Message and the Resv Message can contain other Objects that are not shown above.
The Path Message and the Resv Message are route information for reserving a resource (bandwidth) of the communication path and also route information for updating the reservation of the resource (bandwidth) of the communication path.
As illustrated in
The Egress node (node T) sends the Resv Message back to the uplink node (node C) as a response to the received Path Message. The node C adds one RRO (C-IF1, Label200) to the received Resv Message, and sends the Message back to the uplink node (node B) by changing the HOP Object (C-IF1). The node B and the node A transmit the Resv Message toward the uplink node by executing the same process.
Thereafter, as for the Path Message and the Resv Message, in principle the same information is transmitted to the same node at a fixed cycle (e.g., 30 seconds). The transmitting operation at this fixed cycle is called “Refresh”. The Refresh maintains the LSP that has been set up.
<<Setup of Backup LSP>>
The Path Message is transmitted to the node C serving as the Egress node of the Backup LSP via the node D from the node A as the Ingress node of the Backup LSP. On the other hand, the Resv Message is transmitted to the node A as the Ingress node of the Backup LSP via the node D from the node C as the Egress node of the Backup LSP. Thus, the Backup LSP is set up and maintained by conducting the Refresh.
The node A as a PLR can recognize from receiving the Resv Message that the Backup LSP has been set up.
<<Signaling of Protected LSP after the Setup of the Backup LSP>>
The node A as the PLR notifies the Ingress node (node H) of the Protected LSP of a purport that the Backup LSP has been set up in the form of Local Protection available (LP available) information of the RRO. Through this notification, the Ingress node (node H) of the Protected LSP can recognize that the downlink and the downlink node are protected (Protection). In
<<Operation at Occurrence of Fault in Link>>
On the other hand, the node B determines from the recognition of the fault in the uplink that the Path Message is not Refreshed any more from the node A, and therefore transmits a Path Tear Message to the downlink node C. The Path Tear Message is a Message that requests a reserved resource with the Path Message to release. The node C receiving the Path Tear Message deletes the reserved-and-related reservation information. Note that in the node C, the Path Message is Refreshed from the Backup LSP side, and hence the Path Message is Refreshed to the node T from the node C.
<<Operation when Recovered from Link Fault>>
Herein, a purpose for executing the Local Revertive will be explained. Supposing that a link is, if another route exists, established between, e.g., the node A and anode X, after being switched over to the Backup LSP during the occurrence of the link fault between the node A and the node B, another LSP can be again set up on a route established by the node H, the node A, the node X, the node B, the node C and the node T. Thereafter again, however, a new Backup LSP must be prepared for this LSP (the nodes H, A, X, B, C and T). The already-set-up Backup LSP between the node A, the node D and the node C becomes an unnecessary LSP and therefore needs deleting. It is required that an administrator needs to execute these processes each time the fault occurs. It is, however, feasible to avoid these complicated processes by conducting the Local Revertive.
<Device>
<<Node>>
Next, the nodes in the present embodiment will be described. The nodes can function as the Ingress node, the Egress node, a Transit node (relay node), the PLR, the MP, etc, depending on their allocated positions and so on.
(External I/O IF Unit)
The external I/O IF unit 206 is an interface for control of the self-node and collecting the information.
(Reception Packet Processing Unit)
The reception packet processing unit 202 checks whether an abnormal state exists in the packet received from the input interface or not. The reception packet processing unit 202, if the received packet is normal, transmits the received packet to a proper management unit.
The reception packet processing unit 202, if the received packet is the Path Message, sends this received packet to the reception Path State management unit 212. The reception packet processing unit 202, if the received packet is the Resv Message, sends this received packet to the reception Resv State management unit 222. The reception packet processing unit 202, if the received packet is of main signal traffic, transmits this received packet to the label table & forwarding processing unit 240.
(Transmission Packet Processing Unit)
The transmission packet processing unit 204 transmits, to the output interface, the packets received from the transmission Path Message management unit 214, the transmission Resv Message management unit 224 or the label table & forwarding processing unit 240.
(Reception Path State Management Unit)
The reception Path State management unit 212 queries the label/route information management unit 230 about whether the route information of the received Path Message is proper or not. Further, the reception Path State management unit 212 manages each Object of the received Path Message, and checks whether the Path State is periodically Refreshed.
(Transmission Path Message Management Unit)
The transmission Path Message management unit 214, when functioning as the Ingress node, generates the Path Message on the basis of the route information and the bandwidth information inputted from the external I/O IF unit 206 in order to set up the LSP.
The transmission Path Message management unit 214, when functioning as the Egress node, does not transmit the Path Message.
The transmission Path Message management unit 214, when functioning neither as the Ingress node nor as the Egress node but as the relay node (Transit node), generates the transmission Path Message based on the received Path Message. At this time, the transmission Path Message management unit 214 queries the label/route information management unit 230 about the route information.
The transmission Path Message management unit 214, when functioning as the PLR and when receiving the notification that the Backup LSP has been set up from the reception Path State management unit 212, allocates an LPAO (Local Protection Available Object) to the LSP having the FRO.
The transmission Path Message management unit 214, when functioning as the MP and when receiving the LPAO, deletes the LPAO. If not the MP and when receiving the LPAO, the transmission Path Message management unit 214 lets the LPAO pass through as it is.
The transmission Path Message management unit 214, when recognizing the uplink fault, transmits the Path Tear Message to the downlink node. The transmission Path Message management unit 214 does not, however, transmit the Path Tear Message to the downlink node with respect to the LSP having the LPAO.
The transmission Path Message management unit 214 can be realized as a reservation unit for reserving (ensuring) the LSP resource and also as a reservation updating unit for updating (maintaining) a reserved status of the LSP resource.
(Reception Resv State Management Unit)
The reception Resv State management unit 222 transmits the label information of the receive Resv Message to the label/route information management unit 230 from the downlink node, and manages the received Resv State. On this occasion, the reception Resv State management unit 222 checks whether the Resv State is Refreshed at fixed time. Further, the reception Resv State management unit 222, when the Backup LSP is set up, notifies the transmission Resv Message management unit 224 of this purport.
(Transmission Resv Message Management Unit)
The transmission Resv Message management unit 224, when functioning as the Ingress node, does not transmit the Resv Message.
The transmission Resv Message management unit 224, when functioning as the Egress node or the Transit node, generates the transmission Resv Message based on the received Resv Message. At this time, the transmission Resv Message management unit 224 queries the label/route information management unit 230 about the to-be-allocated label information and route information.
(Label/Route Information Management Unit)
The label/route information management unit 230 manages the label information and the route information. The label/route information management unit 230 responds to the queries given from the respective blocks (the reception Path State management unit 212, the transmission Path Message management unit 214, the reception Resv State management unit 222, the transmission Resv Message management unit 224, the label table & forwarding processing unit 240, etc). The label/route information management unit 230 sends the label-related information to the label table & forwarding processing unit 240.
The reception Path State management unit 212, the transmission Path Message management unit 214, the reception Resv State management unit 222, the transmission Resv Message management unit 224 and the label/route information management unit 230 may be realized as one route information management unit.
The node can confirm from receiving the Path Message and the Resv Message of the LSP that the LSP resource is ensured.
(Label Table & Forwarding Processing Unit)
The label table & forwarding processing unit 240 receives the label-related information from the label/route information management unit 230 and retains the label information in a label table.
The label table & forwarding processing unit 240, when functioning as the Ingress node and when receiving the packet from the reception packet processing unit 202, determines a forwarding destination, then, thereafter, attaches a label to the packet and transmits the label-attached packet to the transmission packet processing unit 204.
The label table & forwarding processing unit 240, when functioning as the Transit node and when receiving the packet from the reception packet processing unit 202, determines, based on the label attached to the received packet, the forwarding destination, then reattaches a label to the packet, and transmits the label-reattached packet to the transmission packet processing unit 204.
The label table & forwarding processing unit 240, when functioning as the Egress node and when receiving the packet from the reception packet processing unit 202, determines, based on the label attached to the received packet, the forwarding destination, then removes the label from the packet, and transmits the label-removed packet to the transmission packet processing unit 204.
Operational Example in Present EmbodimentGiven below is an operational example of the communication network using the nodes described above.
When the fault occurs in the Protected LSP, a method of preventing the release of the resources of the downlink as viewed from an occurrence point of the fault by use of the LPAO, will be explained.
<<Setup of Protected LSP>>
The Protected LSP (LSP#1) is set up from the node H (Ingress node) toward the node T (Egress node). The network administrator explicitly designates the PLR and the MP as roles of the nodes within the network. An assumption in
In the node H, the external I/O IF unit 206 receives the information (e.g., the route information and the bandwidth information) for setting up the Protected LSP (LSP#1) from the outside. The external I/O IF unit 206 transmits the received information to the transmission Path Message management unit 214.
The transmission Path State management unit 214 generates, based on the received information, the Path Message for setting up the Protected LSP (LSP#1). This Path Message corresponds to a transmission Path Msg (Message) T102 of the node H in
The transmission Path State management unit 214 transmits the generated Path Message to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the received Path Message toward the node A according to the Path Message.
The transmission Path Msg T102 of the node H is recorded with the information necessary for generating the Path Message. For example, these necessary pieces of information are LSP identifying information, Session management information (SO), a request (FRO) for the bandwidth with respect to Fast Reroute, a request (SAO) for the Local Protection, explicit route information (ERO) and transmission Interface information (HOP). The node H generates, based on these pieces of information, the Path Message at the fixed cycle and transmits the Path Message (Refresh).
In the node A, the transmission packet processing unit 204 receives the Path Message from the node H. The transmission packet processing unit 204, since the received packet is the Path Message, transmits the received packet to the reception Path State management unit 212. The reception Path State management unit 212 of the node A queries the label/route information management unit 230 about whether the route information of the received Path Message is proper or not. The reception Path State management unit 212 retains intactly the information of each Object of the received Path Message as Path State T154.
The reception Path State management unit 212 of the node A updates the Path State T154 when receiving the next Path Message. The reception Path State management unit 212, if the Path Message is not received for a predetermined period of time (e.g., 150 seconds, which may also be the same as the fixed time described above) from the node H, clears the information of each Object of the Path State T154.
The reception Path State management unit 212 transmits the received Path Message to the transmission Path Message management unit 214.
The transmission Path Message management unit 214 of the node A receives the Path Message from the reception Path State management unit 212. The transmission Path Message management unit 214 deletes the reception IF information (A-IF1) of the self node A from the ERO of the Path Message. Further, the transmission Path State management unit 214 changes the HOP Object of the Path Message to the transmission IF information (A-IF2) of the self node A.
The transmission Path Message management unit 214 of the node A transmits the Path Message with the updated information to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the received Path Message toward the node B according to the Path Message.
Hereafter, in the case of the nodes B and C, in the same way as in the case of the node A, the Path Message is received and, after executing the predetermined processes, transmitted to the next node. In each of the nodes, the Path State and the transmission Path Msg are recorded, and the pieces of information such as the ERO and the HOP Object are sequentially updated.
In the node T (Egress node), the transmission packet processing unit 204 receives the Path Message from the node C. The transmission packet processing unit 204, as the received packet is the Path Message, transmits the packet to the reception Path State management unit 212.
The reception Path State management unit 212 of the node T queries the label/route information management unit 230 as to whether the route information of the received Path Message is proper or not. The reception Path State management unit 212 retains intactly the information of each Object of the received Path Message as a Path State T160.
The reception Path State management unit 212 of the node T, when receiving the next Path Message, updates the Path State T160. The reception Path State management unit 212, if the Path Message is not received from the node C for the predetermined time, clears the information of each Object of the Path State T160.
The transmission Resv Message management unit 224 of the node T (Egress node) generates (Refresh), based on a transmission Resv Msg T260, the Resv Message at the fixed cycle. The transmission Resv Message management unit 224 transmits the generated Resv Message to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the Resv Message received from the transmission Resv Message management unit 224 toward the node C based on the Resv Message.
In the node C (Transit node), the transmission packet processing unit 204 receives the Resv Message from the node T. The transmission packet processing unit 204, since the received packet is the Resv Message, transmits the packet to the reception Resv State management unit 222.
The reception Resv State management unit 222 retains intactly the information of each Object of the received Resv Message as a Resv State T208. The reception Resv State management unit 222 of the node C extracts the label information from the received Resv Message. The extracted label information is transmitted to the label/route information management unit 230. The label/route information management unit 230 transmits the label information received from the reception Resv State management unit 222 to the label table & forwarding processing unit 240. The label table & forwarding processing unit 240 retains the received label information in the label table.
The reception Resv State management unit 222 of the node C updates, when receiving the next Resv Message, a Resv State T208. The reception Resv State management unit 222, if the Resv Message is not received from the node T for the predetermined time (e.g., 150 seconds, which may be the same as the fixed time described above), clears the information of each Object of the Resv State T208.
The reception Resv State management unit 222 transmits the received Resv Message to the transmission Resv Message management unit 224.
The transmission Resv Message management unit 224 receives the Resv Message from the reception Resv State management unit 222. The transmission Resv Message management unit 224 adds transmission IF information (C-IF1) and the label information (200) of the self node C to the RRO of the Resv Message. Further, the transmission Resv Message management unit 224 changes the HOP Object of the Resv Message to the transmission IF information (C-IF1) of the self node C.
The transmission Resv Message management unit 224 transmits the Resv Message with the updated information to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the received Resv Message to the node B according to the Resv Message.
Hereafter, in the case of the nodes B and A, in the same way as in the case of the node C, the Resv Message is received and, after executing the predetermined processes, transmitted. In each of the nodes, the Resv State and the transmission Resv Msg are recorded, and the pieces of information such as the RRO and the HOP Object are sequentially updated.
In the node H (Ingress node), the transmission packet processing unit 204 receives the Resv Message from the node A. The transmission packet processing unit 204, as the received packet is the Resv Message, transmits the packet to the reception Resv State management unit 222.
The reception Resv State management unit 222 of the node H extracts the label information from the received Resv Message, and sends the extracted label information to the label/route information management unit 230. The reception Resv State management unit 222 retains intactly the information of each Object of the received Resv Message as Resv State T202.
Each node receives the Path Message and the Resv Message of the LSP and is thereby enabled to recognize that the LSP is set up, i.e., the resource is ensured.
The reception Resv State management unit 222 of the node H, when receiving the next Resv Message, updates the Resv State T202. The reception Resv State management unit 222, if the Resv Message is not received from the node A for the predetermined time, clears the information of each Object of the Resv State T202.
The node H receives the Resv Message and is thereby enabled to recognize that the Protected LSP is set up, i.e., the resource is ensured.
<<Setup of Backup LSP>>
The Backup LSP is set up in the same way as setting up the Backup LSP in the example of the standard operation illustrated in
<<Signaling of Protected LSP after Setup of Backup LSP>>
The node A as the PLR, upon a trigger that the Protected LSP and the Backup LSP have been set up, adds an LPAO (Local Protection Available Object) to the Path Message and transmits the Path Message to the downlink node. The node B serving as the Transit node let the LPAO pass through as it is, and the node C as the MP deletes this LPAO from the Path Message and transmits the Path Message to the downlink node.
Herein, the LPAO (Local Protection Available Object) is an Object showing that the Backup LSP is set up for the Protected LSP. The LPAO is the Object that does not exist in the standard signaling message. The LPAO is the Object, which is newly added according to the present embodiment. The LPAO is transmitted between the PLR and the MP.
When the node A as the PLR recognizes that the Backup LSP is set up, the reception Path State management unit 212 of the node A notifies the transmission Path Message management unit 214 that the Backup LSP is set up.
A check as to whether the Protected LSP and the Backup LSP are set up may be realized by way of a check unit of the node.
The transmission Path Message management unit 214 newly adds the LPAO to the LSP#1 having the FRO of the transmission Path Msg (
The transmission packet processing unit 204 sends the received Path Message toward the node B according to the Path Message.
In the node B serving as the Transit node, the transmission packet processing unit 204 receives the Path Message from the node A. The transmission packet processing unit 204, as the received packet is the Path Message, sends the packet to the reception Path State management unit 212.
The reception Path State management unit 212 of the node B queries the label/route information management unit 230 about whether the route information of the received Path Message is proper or not. The reception Path State management unit 212 retains the information of each Object (containing the LPAO) of the received Path Message as a Path State T356 as it is.
The reception Path State management unit 212 of the node B, when receiving the next Path Message, updates the Path State. The reception Path State management unit 212, if the Path Message is not received from the node A for the predetermined time, clears the information of each Object of the Path State T356.
The reception Path State management unit 212 of the node B sends the received Path Message to the transmission Path Message management unit 214.
The transmission Path Message management unit 214 of the node B receives the Path Message from the reception Path State management unit 212. The transmission Path Message management unit 214 deletes reception IF information (B-IF1) of the self-node B from the ERO of the Path Message. Further, the transmission Path Message management unit 214 changes the HOP Object of the Path Message to transmission IF information (B-IF2) of the self-node B.
The transmission Path Message management unit 214 of the node B transmits the Path Message (containing the LPAO) with the updated information to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the received Path Message to the node C according to the Path Message.
In the node C serving as the MP, the reception packet processing unit 202 receives the Path Message from the node B. The reception packet processing unit 202, since the received packet is the Path Message, transmits the packet to the reception Path State management unit 212.
The reception Path State management unit 212 of the node C queries the label/route information management unit 230 as to whether the route information of the received Path Message is proper or not. The reception Path State management unit 212 retains the information of each Object (containing the LPAO) of the received Path Message as a Path State T358 as it is.
The reception Path State management unit 212 of the node C, when receiving the next Path Message, updates the Path State. The reception Path State management unit 212, if the Path Message is not received from the node B for the predetermined time, clears the information of each Object of the Path State T358.
The reception Path State management unit 212 of the node C transmits the received Path Message to the transmission Path Message management unit 214.
The transmission Path Message management unit 214 of the node C receives the Path Message from the reception Path State management unit 212. The transmission Path Message management unit 214 deletes reception IF information (C-IF1) of the self-node C from the ERO of the Path Message. Further, the transmission Path Message management unit 214 changes the HOP Object of the Path Message to transmission IF information (C-IF2) of the self-node C.
The transmission Path Message management unit 214 deletes the LPAO from the received Path Message, and retains the Path Message as transmission Path Msg (
The transmission Path Message management unit 214 of the node C transmits the Path Message with the updated information to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the received Path Message to the node T according to the Path Message.
Furthermore, the node A as the PLR, when recognizing that the Backup LSP is set up, notifies the node H as the Ingress node that the Local Protection becomes available (LP available) as shown in the RRO of the Resv Msg T454 of the node A in
<<Operation when Link Fault Occurs>>
The node B recognizes that the Path Message is not Refreshed due to the link fault on the uplink. The node B, as the Path Message of the LSP has the FRO and the LPAO, does not release the resource based on the Path Tear Message but continues the Refresh operation to the downlink node (node C). With this scheme, it follows that the resource between the node B and the node C with respect to the Protected LSP (LSP#1) is maintained without being released. Namely, the release of the resource between the node B and the node C with respect to the Protected LSP (LSP#1) is inhibited.
The node A as the PLR, when recognizing the fault between the node A and the node B, switches over the data traffic to the Backup LSP side. The node A as the PLR, upon recognizing the fault between the node A and the node B, switches back the data traffic to the Backup LSP side. The reception Resv State management unit 222 does not receive the Resv Message from the node B, whereby the node A can recognize the fault between the node A and the node B. The node A thus detects the fault. The node A switches over the Path Message sent to the node B side to the Backup LSP side. At this time, the transmission Path Message management unit 214 of the node A changes the [B-IF1] and [C-IF1] of the ERO of the transmission Path Msg of the node A to [C-IF3] and changes [A-IF2] of the HOP to [A-IF3] (
The transmission packet processing unit 204 sends the received Path Message to the node C from the Backup LSP side according to the Path Message.
In the node C, the transmission packet processing unit 204 receives the Path Message from the node A on the side of the Backup LSP. The transmission packet processing unit 204, as the received packet is the Path Message, sends the packet to the reception Path State management unit 212.
The reception Path State management unit 212 of the node C queries the label/route information management unit 230 about whether the route information of the received path is proper or not.
The reception Path State management unit 212 adds LSP#1-BU (BackUp) to the Path State, and retains the information of each Object of the received Path Message (
The reception Path State management unit 212 of the node C transmits the received Path Message to the transmission Path Message management unit 214.
The transmission Path Message management unit 214 of the node C receives the Path Message from the reception Path State management unit 212. The transmission Path Message management unit 214 deletes the reception IF information (C-IF3) of the self-node C from the ERO of the Path Message. Further, the transmission Path Message management unit 214 changes the HOP Object of the Path Message to the transmission IF information (C-IF2) of the self-node C. The node C is the MP, and hence the transmission Path Message management unit 214 deletes the LPAO from the received Path Message.
The transmission Path Message management unit 214 transmits the Path Message with the updated information to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the received Path Message to the node T according to the Path Message.
On the other hand, the node B as the Transit node, when recognizing the fault between the node A and the node B, clears the Path State of the node B (
It follows that the node C receives the Path Message (LSP#1-BU) from the node A and the Path Message (LSP#1-P) from the node B.
During the occurrence of the fault between the node A and the node B, the node C receives the Path Message from the Protected LSP side and from the Backup LSP side as well. Hence, as shown in the transmission Resv Msg T658 of the node C in
Further, the node A receives the Resv Message from the Backup LSP side. The reception Resv State management unit 222 of the node A changes [C-IF1] of the RRO of the Resv State of the node A to [C-IF3] and changes the HOP to [B-IF1] (
The transmission Resv Message management unit 224 of the node A receives the Resv Message from the reception Resv State management unit 222. The transmission Resv Message management unit 224 updates the transmission Resv Msg. The transmission Resv Message management unit 224 transmits the Resv Message to the transmission packet processing unit 204. The transmission packet processing unit 204 sends the Resv Message toward the node H according to the Resv Message. These operations enable avoidance of a conflict among the resources during the occurrence of the fault.
The resource of the Protected LSP can be maintained by use of the LPAO showing that the Backup LSP is set up for the Protected LSP. The LPAO can be realized by route maintaining information.
The node A as the PLR, upon recognizing the recovery from the link fault, transmits the Path Message toward the node B. The node B receiving the Path Message sends the Path Message to the node C. The node C transmits the Resv Message to the node B, and the node B sends the Resv Message to the node A. The PLR (node A) receiving the Resv Message recognizes that the Protected LSP is normally recovered, then switches back the data traffic, and stops transmitting the Path Message sent toward the Backup LSP side.
According to this configuration, during even the occurrence of the link fault, the resource on the Protected LSP can be maintained, and therefore the data traffic can be switched back on the occasion of the recovery from the link fault.
The detection of the link fault can be realized by way of a detection unit. The switch-back of the data traffic can be actualized by way of a switch control unit. The maintenance of the resource of the Protected LSP can be realized by way of an inhibiting unit which inhibits the resource from being released.
<<Operation when Requested to Set Up New LSP>>
As shown in
<<Operation if Delete Request of LSP is Made on Protected LSP during Occurrence of Link Fault>>
An operation in the case of receiving a delete request (Path Tear) of the LSP on the Protected LSP during the occurrence of the fault, will be explained.
The node H, when receiving the delete request of the LSP#1, sends the Path Tear Message to the node T from the node H via the node A, the node D and the node C. According to this configuration, the resource of the LSP#1 via the Backup LSP is released.
The node B can not receive the Path Tear Message from the uplink (the node A) due to the occurrence of the fault between the node A and the node B. Consequently, the resource between the node B and the node C is not released. Such being the case, for avoiding the maintenance of the unnecessary resource, the node C as the MP, upon a trigger that the node C receives the Path Tear Message from the Backup LSP side, transmits the Resv Tear Message toward the uplink node B. The node B, when receiving the Resv Tear Message, releases the resource between the node B and the node C. According to this configuration, the resource between the node B and the node C is released.
According to this configuration, it is possible to handle the delete request of the LSP, which is received when switched over to the Backup LSP.
<<Operation if Link Fault Occurs between Node B and Node C>>
An operation (a method of preventing the uplink resource from being released at a point where the link fault occurs) if the link fault occurs not nearest to the node A as the PLR described above but between the node B and the node C, will be explained.
As described above, when the link fault occurs between the node A and the node B, the node A as the PLR can directly detect the abnormal state of the nearest downlink. The node A recognizing the link fault between the node A and the node B switches over the data traffic and the Path Message to the Backup LSP side.
On the other hand, as shown in
In the node serving as the PLR, the uplink is normal, the Path Message is Refreshed from the uplink, the nearest downlink is normal, and the Path Error Message is not received from the downlink, in which case the Path Message is Refreshed only on the side of the Protected LSP.
In the node serving as the PLR, the uplink is normal, the Path Message is Refreshed from the uplink, and the nearest downlink is abnormal, in which case the Path Message is Refreshed (switched over) on the side of the Backup LSP.
In the node serving as the PLR, the uplink is normal, the Path Message is Refreshed from the uplink, the Path Message to be transmitted contains the FRO and the LPAO, the nearest downlink is normal, and the Path Error Message is received from the downlink, in which case the Path Message is Refreshed on the side of the Protected LSP and on the side of the Backup LSP.
In the node serving as the PLR, the uplink is normal, the Path Message is Refreshed from the uplink, the Path Message to be transmitted contains neither the FRO nor the LPAO, the nearest downlink is normal, and the Path Error Message is received from the downlink, in which case the Path Message is Refreshed (switched over) on the side of the Backup LSP.
In the node serving as the PLR, if the uplink is abnormal, the Path Tear Message is transmitted.
According to this configuration, the node serving as the PLR changes the Refresh operation of the Path Message corresponding to the fault status of the downlink, whereby the resource conflict between the Protected LSP and another LSP can be avoided.
Claims
1. A communication device, in a communication network including: a first communication path, along which a plurality of communication devices is cascade-connected, having an ingress and an egress; and a second communication path, along which the plurality of communication devices is cascade-connected, the communication devices existing both ends thereof being different from each other on the first communication path, having its ingress corresponding to the communication device, of the communication devices at both ends, located on the side of the ingress of the first communication path and its egress corresponding to the communication device, of the communication devices at both ends, located on the side of the egress of the first communication path, the communication device being the communication device located at the ingress of the second communication path, comprising:
- a checking unit checking whether a bandwidth from the ingress of the first communication path down to the egress thereof and a bandwidth from the ingress of the second communication path down to the egress thereof as a standby of a partial zone of the first communication path, are established or not;
- a route information management unit generating, when the checking unit confirms that the bandwidth from the ingress of the first communication path down to the egress thereof and the bandwidth from the ingress of the second communication path down to the egress thereof as the standby of the partial zone of the first communication path are established, route maintaining information for maintaining the bandwidth of the partial zone of the first communication path; and
- a transmission unit transmitting the route maintaining information generated by the route information management unit to the neighboring communication device on the side of the egress of the first communication path.
2. A communication device according to claim 1, further comprising a reception unit receiving, from the neighboring communication device on the side of the egress of the first communication path, route error information showing occurrence of a link fault on the egress side from the neighboring communication device on the side of the egress of the first communication path,
- wherein when the checking unit confirms that the bandwidth from the ingress of the first communication path down to the egress thereof and the bandwidth from the ingress of the second communication path down to the egress thereof as the standby of the partial zone of the first communication path are established and when the reception unit receives, from the neighboring communication device on the side of the egress of the first communication path, the route error information showing the occurrence of the link fault on the egress side from the neighboring communication device on the side of the egress of the first communication path, the transmission unit transmits the route maintaining information to the neighboring communication device on the side of the egress of the first communication path.
3. A communication device, in a communication network including: a first communication path, along which a plurality of communication devices is cascade-connected, having an ingress and an egress; and a second communication path, along which the plurality of communication devices is cascade-connected, the communication devices existing both ends thereof being different from each other on the first communication path, having its ingress corresponding to the communication device, of the communication devices at both ends, located on the side of the ingress of the first communication path and its egress corresponding to the communication device, of the communication devices at both ends, located on the side of the egress of the first communication path, the communication device being the communication device located on the first communication path between the ingress and the egress of the second communication path, comprising:
- a reception unit receiving route maintaining information for maintaining a bandwidth in a partial zone of the first communication path from the neighboring communication device on the side of the ingress of the first communication path;
- a route information management unit stored with the route maintaining information; and
- a transmission unit transmitting the route maintaining information to the neighboring communication device on the side of the egress of the first communication path.
4. A communication device according to claim 3, wherein if the link fault occurs between the self communication device and the neighboring communication device on the side of the ingress of the first communication path, the transmission unit transmits the route maintaining information stored in the route information management unit to the neighboring communication device on the side of the egress of the first communication path.
5. A communication device according to claim 3, wherein when the reception unit receives delete request information for deleting the bandwidth of the first communication path from the neighboring communication device on the side of the egress of the first communication path, the route information management unit deletes the route maintaining information.
6. A communication device according to claim 3, wherein if the link fault occurs between the self communication device and the neighboring communication device on the side of the egress of the first communication path, the transmission unit transmits route error information showing the occurrence of the link fault on the side of the egress of the first communication path to the neighboring communication device on the side of the ingress of the first communication path.
7. A communication device, in a communication network including: a first communication path, along which a plurality of communication devices is cascade-connected, having an ingress and an egress; and a second communication path, along which the plurality of communication devices is cascade-connected, the communication devices existing both ends thereof being different from each other on the first communication path, having its ingress corresponding to the communication device, of the communication devices at both ends, located on the side of the ingress of the first communication path and its egress corresponding to the communication device, of the communication devices at both ends, located on the side of the egress of the first communication path, the communication device being the communication device located at the egress of the second communication path, comprising:
- a reception unit receiving route maintaining information for maintaining a bandwidth in a partial zone of the first communication path from the neighboring communication device on the side of the ingress of the first communication path; and a route information management unit stored with the route maintaining information.
8. A communication device according to claim 7, further comprising a transmission unit transmitting, if the link fault occurs on the first communication path between the ingress and the egress of the second communication path, when the route information management unit is stored with the route maintaining information, and when the reception unit receives delete request information for deleting a resource of the first communication path from the communication device on the second communication path, the delete request information to the neighboring communication device on the side of the ingress of the first communication path.
9. A network system including a first communication path having an ingress and an egress, and a second communication path, of which a branch point and a merge point, as viewed from the first communication path, are specified as an ingress and an egress, generated so as to bypass a middle zone of the first communication path that is specified from the branch point to the merge point, data to be sent, if any fault does not occur in the middle zone, from the ingress of the first communication path being forwarded to the egress of the first communication path via the middle zone, the system comprising:
- a detection unit detecting the fault in the middle zone;
- a switch control unit switching over, when the fault in the middle zone is detected, a part of a forwarding route of the data from the ingress down to the egress of the first communication path to the second communication path from the middle zone, and switching back, if recovered from the fault in the middle zone, the part of the forwarding route of the data from the ingress down to the egress of the first communication path to the middle zone from the second communication path; and
- an inhibiting unit inhibiting, during a period from the occurrence of the fault in the middle zone up to the recovery, a release of a resource for the first communication path with respect to a fault-not-yet-occurring area of the middle zone.
10. A communication device in a network system including a first communication path having an ingress and an egress, and a second communication path, of which a branch point and a merge point, as viewed from the first communication path, are specified as an ingress and an egress, generated so as to bypass a middle zone of the first communication path that is specified from the branch point to the merge point, data to be sent from the ingress of the first communication path being forwarded to the egress of the first communication path via the middle zone if any fault does not occur in the middle zone, a forwarding route of the data sent from the ingress of the first communication path being switched over to the second communication path from the middle zone if the fault occurs in the middle zone, and the forwarding route of the data sent from the ingress of the first communication path being switched over to the middle zone from the second communication path if the middle zone is recovered from the fault, the communication device disposed in the middle zone, comprising:
- a reservation unit reserving a resource for the first communication path that is related to the middle zone when generating the first communication path; and
- a reservation updating unit updating a reserved status of the resource for the first communication path,
- wherein the reserved status of the resource for the first communication path is not canceled due to the occurrence of the fault in the middle zone, and
- the reservation updating unit updates the reserved status even when the fault occurs in the middle zone.
Type: Application
Filed: Aug 14, 2008
Publication Date: Dec 11, 2008
Applicant: FUJITSU LIMITED (Kawasaki-shi)
Inventor: Toshifumi Yokoyama (Fukuoka)
Application Number: 12/191,499
International Classification: H04Q 11/00 (20060101);