P2MP-TE Sub-tree Re-optimization via Intermediate Node Feedback
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Solution Overview
Problem
Loosely routed networks, such as those using Point-to-MultiPoint (P2MP) MPLS and GMPLS, often establish sub-optimal label switched paths due to the lack of explicit route identification, leading to remerge paths that are inefficient and consume additional link bandwidth resources.
Innovation Solution
An intermediate node in the network determines and transmits a remerge-free preferred path to a head-end node through re-evaluation requests, optimizing signal paths and eliminating remerge paths by expanding loose next hops and using signaling mechanisms like RSVP-TE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If loosely routed label switched paths are established without explicit route identification, then ease of operation is improved, but manufacturing precision deteriorates
Solution Approach 1:
The system performs preliminary path optimization by determining remerge-free preferred paths before data transmission begins. The head-end node receives re-evaluation requests and determines optimal paths in advance, expanding loose next hops and identifying preferred paths before actual data flow, thus ensuring both ease of operation and path optimization precision
Solution Approach 2:
The system implements feedback mechanisms where intermediate nodes send re-evaluation requests to head-end nodes about path availability and optimization opportunities. This feedback loop allows the system to continuously improve path routing while maintaining operational simplicity, as the head-end node can adjust paths based on network conditions and remerge detection
2Adaptability or versatility
If intermediate nodes determine paths by expanding loose next hops, then adaptability is improved, but device complexity increases
Solution Approach 1:
The system extracts the complex path determination and remerge detection functions from intermediate nodes and concentrates them at the head-end node. Intermediate nodes simply forward re-evaluation requests and available information, while the head-end node performs the computationally intensive path optimization, thus reducing intermediate node complexity while maintaining adaptability
Solution Approach 2:
The head-end node acts as an intermediary that receives re-evaluation requests from intermediate nodes, performs complex path analysis by expanding loose next hops, and determines optimal remerge-free paths. This intermediary approach allows intermediate nodes to maintain simplicity while the system as a whole achieves high adaptability through centralized intelligent routing
3Ease of operation
If remerge paths are allowed in loosely routed networks, then ease of operation is maintained, but loss of energy increases
Solution Approach 1:
The system converts the potential harm of remerge paths into a benefit by detecting and eliminating them. Re-evaluation requests identify where remerge paths would occur, and the system proactively determines alternative remerge-free preferred paths, thus transforming what would be harmful resource waste into an opportunity for optimization without complicating operation
Data Source
AI summary
In one embodiment, for a point to multipoint label switched path, an intermediate node receives a re-evaluation request from a head-end node for at least one routing path having a destination in a loosely routed network for a single destination or for a plurality of destinations in the label switched path forming tree or sub-tree. In response to the re-evaluation request, the intermediate node determines an availability for a remerge-free preferred path for the destination(s), which includes at least one loosely routed next hop, and the intermediate node transmits a preferred path available message to the head-end node based on the determined availability of the remerge-free preferred path.