Preemptible Backup Paths for Mesh Network Restoration
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Solution Overview
Problem
Current network restoration methods face challenges in minimizing restoration time while avoiding inefficient bandwidth usage, as existing backup paths are either pre-calculated and unused or established at the same priority as active paths, leading to suboptimal resource allocation.
Innovation Solution
Implementing preemptible established backup paths in a network, where a primary path is established at a designated priority, and a backup path at a lower priority, allowing for quick switching to the backup path upon failure and potential preemption for new service requests, thereby minimizing restoration time and optimizing bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If dedicated protection paths are established for working paths, then restoration time is reduced to sub-50 ms, but bandwidth usage becomes inefficient as protection paths remain active and unused
Solution Approach 1:
The backup path priority is made dynamic rather than static. Initially established at lower priority to allow bandwidth sharing, the priority is elevated to designated priority only when needed for restoration, transforming the system from static resource allocation to dynamic adaptation based on actual failure conditions
Solution Approach 2:
The priority parameter of the backup path is changed from a fixed value to a variable that transitions from lower priority during normal operation to designated priority upon failure detection. This parameter change enables the system to achieve fast restoration while avoiding permanent bandwidth reservation
2Loss of energy
If mesh restoration paths are pre-calculated without establishing them, then bandwidth usage is optimized, but restoration time increases to several seconds due to path computation and signaling delays
Solution Approach 1:
The backup path is established in advance during service provisioning, but held in a lower-priority state rather than being fully activated. This preliminary action prepares the path structure beforehand while avoiding the full resource commitment of traditional dedicated protection, enabling faster restoration than on-demand calculation
Solution Approach 2:
The system transitions from static pre-calculated paths (mesh restoration) and static dedicated paths (1+1 protection) to a dynamic hybrid approach where the backup path exists physically but its activation status changes dynamically based on failure conditions and network resource availability
3Loss of time
If backup paths are established at the same priority as active paths, then fast restoration is achieved, but network bandwidth is exhausted leaving no bandwidth for dynamic reroutes
Solution Approach 1:
Different priority levels are assigned to different paths based on their function and state. The backup path operates at lower priority during normal conditions to allow bandwidth sharing, but can be elevated to designated priority when needed, creating local quality differentiation that resolves the global resource allocation conflict
Solution Approach 2:
The priority assignment is made dynamic rather than fixed. The backup path's priority parameter changes from lower to designated priority upon failure, enabling the system to adapt resource allocation in real-time based on actual network conditions and restoration needs
Data Source
AI summary
A method, implemented in a node in a network, for a preemptible established backup path for a mesh restorable service includes, responsive to a new service request for the mesh restorable service with the preemptible established backup path, establishing a primary path designated as a current path for the mesh restorable service at a designated priority; establishing a backup path for the mesh restorable service at a lower priority than the designated priority, subject to bandwidth availability in the network; and responsive to a fault affecting the primary path, switching to the backup path and raising a priority of the backup path to the designated priority.