Cross-IGP Backup Path Selection Using SRLG Diversity
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Solution Overview
Problem
In IP/MPLS networks, existing methods for establishing backup paths fail to ensure high reliability of user data across different Internal Gateway Protocol (IGP) domains, leading to lower safety of user data due to the inability to compute and establish the best backup path, resulting in a high risk of failure when the backup and main paths share the same Shared Risk Link Groups (SRLG) information.
Innovation Solution
A method and device that allow a first node in one IGP domain to receive path information from a second node in a neighboring IGP domain, including SRLG information, to establish or select a backup path with different SRLG information, thereby reducing the risk of failure by diversifying the risk of the backup path from the main path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backup path is established using existing IGP domain methods, then backup path can be computed within single domain, but cannot obtain best backup path under cross-IGP domain scenario leading to lower data safety
Solution Approach 1:
The patent extends the backup path computation capability from single-IGP-domain to multi-IGP-domain scenarios. The boundary node performs path computation that considers SRLG information from multiple IGP domains, making the system universally applicable across different domain boundaries while maintaining the ability to compute optimal backup paths in cross-domain environments.
Solution Approach 2:
The boundary node acts as an intermediary between different IGP domains. It receives path information from one domain, processes it considering SRLG constraints, and computes backup paths that span multiple domains. This intermediary mechanism enables coordinated backup path computation across domain boundaries, resolving the limitation of existing single-domain approaches.
2Reliability
If backup path shares same interface group or equipment room as main path, then path selection is simple, but backup path fails simultaneously with main path when encountering failure
Solution Approach 1:
The patent applies different quality criteria to path selection at different locations. At the boundary node, it considers both local interface group information and global SRLG information from multiple domains. This local quality differentiation enables the system to select backup paths that are locally simple but globally independent in terms of failure risk.
Solution Approach 2:
The system changes the parameter used for path selection from purely local interface group considerations to include SRLG information that spans multiple domains. By incorporating this additional parameter, the system can identify backup paths that avoid shared risk link groups, ensuring failure independence even when paths traverse the same physical infrastructure.
3Reliability
If SRLG information is considered for path selection, then backup path avoids shared risk links, but computation cannot be performed under cross-IGP domain scenario
Solution Approach 1:
The patent segments the cross-domain path computation into manageable parts. The boundary node receives path information from one domain, processes SRLG constraints locally, and computes backup paths that span multiple domains. This segmentation makes the complex cross-domain computation feasible by breaking it down into discrete, manageable steps at domain boundaries.
Solution Approach 2:
The system performs preliminary path computation within individual IGP domains before handling cross-domain scenarios. Boundary nodes pre-process path information and SRLG constraints locally, then use this prepared information to compute optimal backup paths across domain boundaries. This preliminary action simplifies the overall computation process and makes cross-domain SRLG-aware path selection feasible.
Data Source
AI summary
Embodiments of the present disclosure provide a method and device for establishing backup path, a method and device for selecting backup path. The method comprises a first node in a first IGP domain receiving a response message of successful establishment of a main path from a second node in a second IGP domain through the main path; the first node obtains path information of the main path from the response message; the path information of the main path includes at least SRLG information of a link composing the main path; the first node establishes, according to the path information of the main path, a backup path between the first node and the second node; the SRLG information of a link composing the backup path is different from the SRLG information of the link composing the main path.