Patent EP0436201A1 successfully refreshed from Google Patents.
EP0436201A1
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EP
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Method for searching for alternate path in communication network
Assignee: Fujitsu Ltd
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Filing: 1990-12-21
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Granted: —
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Expires: 2010-12-21
Abstract
Abstract A method includes the steps of a) detecting a failure which occurs in a node or link (step 101), and b) identifying at most N nodes contained in each path affected by the occurrence of the failure (step 102,103). The method also includes the steps of c) broadcasting a restoration message having an identifier of the sender node and identifiers of the N nodes, the identifiers of the N nodes being candidate nodes (step 103), and d) determining whether or not a node is one of the candidate nodes (step 190). The node which is one of the candidate nodes is a destination node. Further, the method includes the steps of e) passing the restoration message through a repeater node (step 203) and f) determining a route via which the restoration message has been transferred to the destination node to be an alternate path (step 302).
Inventors
- 👤 Takafumi Chujo
- 👤 Hiroaki Komine
- 👤 Keiji Miyazaki
- 👤 Takao Ogura
- 👤 Tetsuo Soejima
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 09:19
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/64; H04Q3/66; H04Q3/665; H04L; H04L1/00; H04L1/24; H04L45/00; H04L45/02; H04L45/24; H04L45/247; H04L45/28; H04Q3/0016; H04Q3/0062; H04Q3/0075; H04Q3/0079
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
285 words
A method for searching for an alternate path in a communication network which has a plurality of nodes and a plurality of links which mutually connect adjacent nodes, information being transferred via a path which goes through nodes, said method comprising the step of: a) detecting a failure which occurs in a node or link (step 101), characterized in that said method comprises the steps of: b) identifying at most N (N is an integer equal to or greater than 2) nodes contained in each path affected by the occurrence of said failure, each said path being connected to a sender node which detects said failure, information being transferred to said sender node via said N nodes, said sender node serving as a start point of each alternate path which is to be established (steps 102, 103); c) broadcasting a restoration message to links which outgo from said sender node, said restoration message having an identifier of said sender node and identifiers of said N nodes specified for each said path affected by the occurrence of said failure, the identifiers of said N nodes specified for each said path being candidate nodes of an end point of each said alternate path (step 103); d) determining whether or not a node being considered is one of said candidate nodes, the node which is one of said candidate nodes being a destination node (step 190); e) passing said restoration message through a repeater node which is a node other than said candidate nodes (203); and f) determining a route via which said restoration message has been transferred to said destination node to be an alternate path connected between said sender node and said destination node (104, 105).
Claim 2
Dependent Claim
80 words
A method as claimed in claim 1, characterized by further comprising the steps of: generating, at each node, a path tracer which stores the identifiers of at most said N nodes via which information has been transferred to each said node; replacing the identifier of an oldest node contained in said path tracer by its own identifier; and sending out said path tracer including said its own identifier to a next node on a downstream side of a corresponding path.
Claim 3
Dependent Claim
97 words
A method as claimed in claim 2, characterized by further comprising the step of receiving, for each said path, said path tracer from each destination node, said path tracer having at most N nodes included in the corresponding path via which information is received by said sender node, wherein said N nodes contained in each said path affected by the occurrence of said failure are identified by said path tracer which is generated for each said path and which has at most N nodes of each said path via which information is received by said sender node.
Claim 4
Dependent Claim
79 words
A method as claimed in claim 3, characterized by further comprising the steps of: classifying path tracers received from destination nodes into a plurality of groups, each having identical path tracers (steps 102, 103); and generating said restoration message so that one restoration message is generated for each of said groups (103), said restoration message for each of said groups having the identifier of said sender node and the identifiers of at most N nodes of the corresponding path.
Claim 5
Dependent Claim
86 words
A method as claimed in claim 3, characterized by further comprising the steps of: classifying path tracers received from destination nodes into a plurality of groups, each having identical path tracers (steps 102, 103); and generating said restoration message so that a single restoration message is generated in common with said groups (step 103), said restoration message in common with each of said groups having the identifier of said sender node and the identifiers of at most said N nodes related to each of said groups.
Claim 6
Dependent Claim
68 words
A method as claimed in claim 4, characterized by further comprising the steps of: sending back an acknowledgement message to said sender node from each said destination node (step 302); and receiving, at said sender node, said acknowledgement message from each said destination node, wherein said step f) comprises the step of determining the route on the basis of said acknowledgement message received from each said destination node.
Claim 7
Dependent Claim
116 words
A method as claimed in claim 4, characterized by further comprising the steps of: sending back an acknowledgement message to said sender node from each said destination node (step 302); receiving, at said sender node, said acknowledgement message from each said destination node; specifying, at said sender node, one path tracer for each of said groups, said one path tracer being a path tracer which is first received by said sender node for each of said groups (step 104), wherein said step f) comprises the step of determining, for each of said groups, an alternate path corresponding to a route related to said one path tracer which is first received by said sender node (step 105).
Claim 8
Dependent Claim
84 words
A method as claimed in claim 4, characterized by further comprising: receiving, at each of said destination nodes, said restoration message (step 301); determining, at each of said candidate nodes, whether or not the restoration message is the first one received (step 301); sending back said acknowledgement message when it is determined that the restoration message is the first one received (step 302); and sending back no acknowledgement message when it is determined that the restoration message is not a first received restoration message.
Claim 9
Dependent Claim
38 words
A method as claimed in claim 5, characterized in that said step f) comprises the step of switching, at each node between said sender node and said destination node, its matrix switch so that said route is formed.
Claim 10
Dependent Claim
27 words
A method as claimed in claim 1, characterized in that said restoration message comprises information about the number of paths affected by the occurrence of said failure.
Claim 11
Dependent Claim
28 words
A method as claimed in claim 1, characterized in that said restoration message comprises information about an identifier of each path affected by the occurrence of said failure.
Claim 12
Dependent Claim
28 words
A method as claimed in claim 4, characterized in that said restoration message comprises information about the identifier of one destination node defined for each of said groups.
Claim 13
Dependent Claim
22 words
A method as claimed in claim 12, characterized in that said restoration message includes information about the identifier of said repeater node.
Claim 14
Dependent Claim
62 words
A method as claimed in claim 1, characterized by further comprising the steps of: judging, at said destination node, whether or not spare paths are available when said destination node receives said restoration message (step 304); and sending out said restoration message to the links extending from said destination node when it is judged that the spare paths are available (step 305).
Claim 15
Dependent Claim
48 words
A method as claimed in claim 1, characterized by further comprising: the steps of: omitting the identifier of the destination node from said restoration message (305); and writing information indicating the number of restorable paths which indicates the number of paths to be requested for alternate paths (305).
Claim 16
Dependent Claim
47 words
A method as claimed in claim 14, characterized in that said message comprises a port identifier indicating a link which extends from the destination node and which is inhibited from being used for broadcasting said restoration message when it is determined that the spare paths are available.
Claim 17
Dependent Claim
104 words
A method as claimed in claim 16, characterized by further comprising the steps of: storing said port identifier of said restoration message which is first received into said destination node (step 203); judging, at said destination node, whether or not the port identifier contained in the restoration message which is the second one received coincides with that stored in said destination node (304); and broadcasting said restoration message which is the second one received when it is judged that the port identifier contained in the restoration message which is the second one received does not coincide with that stored in said destination node (305).
References Cited (Backward Citations)
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