BFD Path Failure Detection in MPLS LSP Networks
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Solution Overview
Problem
In Bidirectional Forwarding Detection (BFD) sessions for Multiprotocol Label Switching (MPLS), existing technologies are unable to accurately identify which specific path has failed between a LSP ingress node and an egress node, hindering swift fault isolation and repair.
Innovation Solution
The implementation of logic at both ingress and egress nodes to discover and describe multiple paths, associate each path with a unique BFD discriminator, and bootstrap BFD sessions with path descriptors, enabling precise fault detection and signaling of failed paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BFD sessions are used to detect MPLS LSP data plane failures, then failure detection capability is improved, but the ability to identify which specific path has failed deteriorates
Solution Approach 1:
The invention segments the BFD detection mechanism by introducing path-specific discriminators that divide the detection space into distinct path identifiers. Each BFD session is associated with a specific path through a path discriminator value, allowing the system to detect failures while simultaneously identifying which specific path has failed among multiple LSPs between ingress and egress nodes.
2Adaptability or versatility
If multiple LSP paths exist between ingress and egress nodes, then path redundancy is improved, but the complexity of detecting and isolating failures on specific paths increases
Solution Approach 1:
The invention implements a feedback mechanism where BFD detection packets include path-specific discriminator information that returns to the ingress node. This feedback loop allows the system to automatically identify which specific path has failed based on the discriminator value in the failed BFD packets, reducing the complexity of failure isolation despite having multiple redundant paths.
3Ease of operation
If conventional BFD sessions are used without path descriptors, then session establishment is simplified, but fault isolation speed deteriorates
Solution Approach 1:
The invention applies preliminary action by embedding path descriptor information including discriminator values into BFD packets during normal operation. This pre-prepared path identification information is included in the BFD control packets, so when a failure occurs, the ingress node can immediately identify the failed path from the discriminator value in the failed packets without requiring additional complex analysis or time-consuming trace operations.
Data Source
AI summary
Improved detection of specific BFD LSP path failures is herein disclosed. The improved detection described herein allow for faster fault isolation of a failure along a LSP path, which in turn may allow for faster repair of the failure. When opening a BFD session with a LSP egress node, the LSP ingress node provides the LSP egress node a path descriptor along with the BFD Discriminator. If a BFD failure is detected at the LSP egress node, the LSP egress node can signal an alarm that includes a full description of the path.