Reverse Path Discovery for Bidirectional Forwarding Detection
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Solution Overview
Problem
Existing communication networks lack an efficient method for discovering reverse Segment Routing (SR) policies, particularly in scenarios without a centralized SDN controller, leading to manual or tedious processes for initiating Bidirectional Forwarding Detection (BFD) procedures.
Innovation Solution
A four-stage procedure is implemented, allowing nodes in a network to perform reverse path discovery and BFD without centralized control. This involves sending echo requests and replies to determine reverse SR policies, which can then be used for initiating BFD procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If manual processes are used to discover reverse SR policies, then network control can be distributed without centralized controllers, but the process becomes tedious and time-consuming for network administrators
Solution Approach 1:
The system enables nodes to automatically discover reverse SR policies through self-service mechanisms. Initiator nodes send path discovery requests and automatically receive and process reverse path information from reflector nodes, eliminating the need for manual administrator intervention while maintaining distributed control architecture
Solution Approach 2:
The system performs preliminary path discovery actions before BFD procedures are needed. By establishing reverse path information in advance through automated echo request/reply exchanges, the system prepares the network infrastructure proactively, so that when BFD is required, the reverse path is already known and configured
2Extent of automation
If centralized SDN controllers are used to discover reverse SR policies, then automated path discovery is achieved, but the system becomes dependent on centralized control infrastructure
Solution Approach 1:
The invention extracts the path discovery functionality from centralized SDN controllers and implements it directly at the network nodes. Each node runs its own path discovery protocol, sending echo requests and processing replies locally, thereby removing the dependency on centralized control infrastructure while maintaining full automation
Solution Approach 2:
The system segments the path discovery function into independent node-level operations rather than a centralized control function. Each node independently performs path discovery to and from its peers, dividing the previously centralized task into distributed atomic operations that can be executed autonomously
3Reliability
If BFD procedures are initiated without reverse path information, then fault detection can be attempted, but the detection accuracy and efficiency are reduced
Solution Approach 1:
The system uses feedback from path discovery echo replies to inform subsequent BFD procedures. Reverse path information obtained through the automated discovery process is fed back into the BFD initialization, ensuring that fault detection uses accurate reverse path routing information for improved detection reliability
Data Source
AI summary
Systems and methods at a reflector node include steps of receiving a request from an initiator node in the network, the request having been sent in a forward direction from the initiator node to the reflector node to discover a reverse path in a reverse direction from the reflector node to the initiator node, and transmitting a reply to the initiator node with one or more reverse Segment Routing (SR) policies that meet one or more path constraint parameters in the request. The reply can include associated Segment Identifiers (SIDs) for the one or more reverse SR policies. The steps can further include implementing one of Bidirectional Forwarding Detection (BFD) or a Multi-Protocol Label Switching (MPLS) Ping procedure with the initiator node, sent over one of the one or more reverse SR policies.