LSP Protection via Interface Classification in RRO Nodes
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Solution Overview
Problem
In existing MPLS networks, NNHOP backup LSPs cannot be correctly identified, leading to incomplete protection of main LSPs due to ambiguity in determining Merge Points (MPs) when checking 'Local protection available' flags in upstream RRO nodes.
Innovation Solution
The method involves setting interface classification identifications in Record_Route Objects (RRO) and configuring NNHOP protection by finding the second nearest upstream RRO node corresponding to the outgoing interface, ensuring accurate protection identification and state configuration for LSPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NNHOP backup LSP is established to protect upstream LSP, then protection coverage is improved, but ambiguity in identifying Merge Point leads to incorrect protection configuration
Solution Approach 1:
The patent introduces an intermediary mechanism (RRO node list with interface classification identifications) to mediate between the backup LSP establishment and the Merge Point identification. This intermediary structure carries explicit interface identification information from upstream nodes, allowing downstream nodes to accurately determine the correct upstream outgoing interface without ambiguity, thus resolving the contradiction between providing broad protection coverage and ensuring precise Merge Point identification
Solution Approach 2:
The patent adds a new dimension of information (interface classification identifications in RRO nodes) to the existing LSP protection mechanism. By embedding interface identification data within the RRO node list that flows downstream, the system transforms the Merge Point identification problem from a ambiguous upstream flag-checking process into a precise downstream lookup process based on interface matching, thereby improving identification accuracy while maintaining protection coverage
2Difficulty of detecting and measuring
If upstream RRO nodes are checked for 'Local protection available' flags, then protection status can be detected, but ambiguity arises when multiple upstream nodes have protection flags set
Solution Approach 1:
The patent segments the protection status information by associating it with specific interface identifications rather than propagating it ambiguously through multiple upstream nodes. Each RRO node in the downstream list contains interface classification identifications that uniquely map to the corresponding upstream outgoing interface, allowing the downstream node to segment and identify the correct protection relationship without confusion from multiple flagged nodes
Solution Approach 2:
The patent implements a feedback mechanism where the downstream node uses the interface classification identifications from the RRO node list to verify and confirm the correct upstream interface. This feedback loop ensures that even when multiple upstream nodes have protection flags set, the downstream node can accurately identify the intended upstream outgoing interface by matching interface identifiers, thus preventing information loss and maintaining detection accuracy
Data Source
AI summary
A method for protecting a label switched path is disclosed. The method includes: setting, in a record_route object node list, interface classification identifications in record_route objects corresponding to interfaces of resource reservation protocol nodes respectively, and delivering the list downstream; when a downstream resource reservation protocol node receives the record_route object node list from upstream, finding, by the downstream resource reservation protocol node, a record_route object node corresponding to a last outgoing interface of a nearest outgoing interface in the record_route object node list according to the interface classification identifications, and setting next next hop protection for a corresponding label switched path according to a protection identification of the record-route object node. A system and device for protecting a label switched path are also disclosed. With the invention, an RSVP node may implement NNHOP protection for an upstream LSP correctly.