Router Redundancy via BFD Session Segmentation
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Solution Overview
Problem
Existing methods for implementing redundancy protection in multicast routing, such as those using BFD sessions between DR/BDR pairs, lead to a high number of messages and increased latency in switchover times, especially in telecommunication scenarios, where millisecond protection is required, due to the need for numerous BFD sessions across multiple interfaces.
Innovation Solution
The method involves establishing BFD sessions only between active and backup interfaces within protection groups, allowing the second router to detect status changes in the active interface and quickly switch over when a failure occurs, thereby reducing the number of BFD sessions and enabling rapid substitution of interfaces to maintain multicast traffic distribution or reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BFD sessions are established between all DR/BDR pairs across multiple interfaces to ensure redundancy protection, then reliability of multicast traffic distribution is improved, but the number of protocol messages increases and switchover time increases
Solution Approach 1:
The patent segments the network interfaces into multiple protection groups, where each group is independently monitored by a single BFD session. Instead of establishing BFD sessions between all DR/BDR pairs across all interfaces, the system creates separate protection groups (e.g., first protection group with first interface, second protection group with second interface) and establishes one BFD session per group. This segmentation reduces the total number of BFD sessions from O(n²) to O(n), thereby reducing message overhead and switchover time while maintaining reliability within each group.
Solution Approach 2:
The patent applies partial action by monitoring only the necessary interfaces for redundancy protection rather than all possible interface combinations. Instead of establishing BFD sessions for every potential DR/BDR pair (excessive action), the system selectively establishes BFD sessions only for the specific interfaces that require protection, achieving sufficient reliability with minimal protocol overhead.
2Speed
If BFD sessions are deployed between all DR/BDR pairs to achieve fast convergence, then convergence efficiency is improved, but network bandwidth is wasted due to high-frequency transmission of detection messages
Solution Approach 1:
The patent segments the monitoring function into multiple independent protection groups, each with its own BFD session. By dividing the network interfaces into separate groups (first protection group, second protection group, etc.), the system reduces the number of simultaneous BFD sessions required. This segmentation maintains fast convergence within each group while reducing the aggregate bandwidth consumption across the entire network.
Solution Approach 2:
The system performs partial monitoring by establishing BFD sessions only for the specific interfaces that require redundancy protection, rather than monitoring all possible interface combinations. This partial action achieves sufficient convergence speed for critical interfaces while minimizing the overall bandwidth consumption of detection messages in the network.
3Reliability
If multiple BFD sessions are maintained for hundreds or thousands of interfaces to ensure comprehensive protection, then coverage of protection is improved, but the number of messages generated increases causing switchover to reach second scale
Solution Approach 1:
The patent applies segmentation by organizing numerous interfaces into multiple protection groups, where each group is managed by a single BFD session. Instead of maintaining separate BFD sessions for hundreds or thousands of individual interfaces (which would create excessive complexity), the system segments interfaces into logical groups (first protection group, second protection group, etc.), reducing the number of BFD sessions from O(n) to O(log n) or O(√n) depending on group size, thereby maintaining protection coverage while reducing session complexity.
Solution Approach 2:
The patent merges multiple interfaces into protection groups, where each group is monitored by a single BFD session. By combining the monitoring function for multiple interfaces into one session per group, the system reduces the total number of BFD sessions required. This merging approach maintains comprehensive protection coverage across all interfaces while significantly reducing the complexity of session management and message generation.
Data Source
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AI summary
A method for implementing redundancy protection applied in a first router includes: providing (11) a first protection group comprising one active interface and any number of inactive interfaces selected from interfaces of the first router, wherein all of interfaces in the first protection group serve to distribute or receive multicast traffic; activating (12) bidirectional forwarding detection BFD protocol only at the active interface in the first protection group, so as to enable the active interface in the first protection group to establish interaction with an active interface in a second protection, such that a second router can determine a status of the active interface in the first protection group through the active interface in the second protection group; and stopping (13) the all of interfaces in the first protection group to distribute or receive the multicast traffic when failure occurs at the active interface in the first protection group.