Mesh Restoration Using Global Pre-computed Transit Lists
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Solution Overview
Problem
Conventional communication networks face issues with bandwidth oversubscription and increased restoration times due to a lack of global network visibility, leading to crankback and inefficient use of available bandwidth during mesh restoration events.
Innovation Solution
The implementation of a global restoration calculation algorithm that calculates pre-computed, contention-free restoration paths using Associated Hop Designated Transit Lists (DTLs), which are then distributed to nodes for efficient link failure management, eliminating crankback and optimizing bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If nodes independently calculate restoration paths using conventional mechanisms, then each node can determine its own restoration routes, but bandwidth oversubscription occurs and restoration times increase due to lack of global network visibility
Solution Approach 1:
The patent pre-calculates restoration paths using Associated Hop Designated Transit Lists (DTLs) before failures occur. The global restoration pre-calculation computes contention-free restoration paths for all possible single-link failures and stores them in DTLs at each node, eliminating the need for real-time path calculation during failures and avoiding bandwidth oversubscription.
Solution Approach 2:
The patent introduces a global restoration pre-calculation mechanism that acts as an intermediary to coordinate restoration paths across the network. This centralised calculation approach mediates between multiple nodes' restoration needs, ensuring that selected paths are contention-free and avoiding the bandwidth oversubscription that occurs with independent node-based calculations.
2Device complexity
If nodes independently calculate restoration paths, then distributed control is maintained, but signaling traffic increases and routing message propagation is delayed
Solution Approach 1:
The patent performs restoration path calculations in advance and stores results in DTLs at each node. During actual failures, nodes simply retrieve pre-computed paths from their local DTLs without generating additional signaling traffic, thereby reducing network overhead while maintaining distributed control for path selection.
Solution Approach 2:
The patent implements a feedback mechanism where the global restoration pre-calculation uses routing updates about actual network bandwidth utilization to refine future path selections. This feedback loop allows the system to adapt to changing network conditions while maintaining the benefits of pre-computed paths.
3Reliability
If bundle diverse paths are excluded from restoration calculations to ensure protection validity, then restoration path validity is improved, but available restoration bandwidth is reduced and cost increases
Solution Approach 1:
The patent applies local quality by associating specific DTLs with individual failed links rather than applying blanket bundle diversity restrictions across all possible failures. Each node receives link-specific DTLs that contain only the bundle diversity constraints relevant to that particular link failure, allowing restoration paths to utilise otherwise available bandwidth while maintaining validity for the actual failure scenario.
Solution Approach 2:
The global restoration pre-calculation pre-determines which bundle diverse paths are actually needed for each specific link failure scenario. By calculating restoration paths in advance for each possible single-link failure, the system identifies and reserves only the necessary bundle diverse paths, avoiding the overly conservative exclusion of all bundle diverse paths that would increase cost and reduce available bandwidth.
Data Source
AI summary
The present disclosure provides systems and methods for mesh restoration based on Associated Hop Designated Transit Lists (DTLs). The Associated Hop DTLs are calculated through a global restoration calculation (GRC) algorithm that can be run by a central controller in an offline manner. The restoration paths calculated by the GRC algorithm can then be pushed down to the originating nodes for each connection to utilize at the time of a given failure scenario. This GRC algorithm can be performed for each possible bundle failure in the network, where a bundle failure is determined by the set of all links which may fail together due to common shared risk, such as a common conduit or DWDM fiber. The globally calculated, contention free, restoration paths are then pushed down to each node in the network.