How to Resolve Frequent BGP Session Flaps in Google Cloud?
Short answer
D Ask the on-premises team to enable Bidirectional Forwarding Detection (BFD).
Question
Key Takeaways
Examines BGP stability mechanisms where candidates often confuse fault tolerance features like Graceful Restart with rapid failure detection tools like BFD.
This question tests best practices for stabilizing BGP peering between on-premises networks and Google Cloud. The community consensus strongly favors enabling Bidirectional Forwarding Detection (BFD) to rapidly detect and mitigate session instability.
Common mistake: Option C (Graceful Restart) is frequently chosen because it helps maintain forwarding during control plane restarts, but it does not actively prevent or quickly detect the underlying physical or link flaps causing BGP session drops.
Expert Analysis
Why the Answer Is Correct
Enabling BFD provides sub-second failure detection for BGP sessions, which directly addresses frequent session flaps by rapidly tearing down and re-establishing peering when link issues occur. In Google Cloud’s Cloud Router architecture, BFD is explicitly recommended for high-availability interconnects to ensure quick convergence and minimize traffic disruption. Configuring BFD aligns with industry best practices for stabilizing dynamic routing over potentially unstable physical links.
Why the Other Options Are Wrong
Switching to static routing eliminates dynamic path selection and scalability, making it unsuitable for complex hybrid environments. Increasing the BGP hold timer actually masks underlying connectivity issues by delaying flap detection, which can lead to traffic blackholing. Graceful restart preserves forwarding state during BGP peer restarts but does not resolve the root cause of rapid session drops caused by link instability.
Community Comment Notes
Candidates frequently debate between options C and D, as both relate to BGP resilience. Comment [2] correctly points to Google’s official troubleshooting documentation, which emphasizes BFD for detecting rapid session changes. The majority vote favoring D reflects the exam’s focus on proactive failure detection rather than post-failure state preservation. Clarifying the distinction between fast detection and control-plane recovery resolves most confusion.
Official Reference
https://cloud.google.com/network-connectivity/docs/router/support/troubleshoot-bgp-sessions
This link opens the official vendor documentation in a new tab.
Exam Strategy
When troubleshooting dynamic routing instability, prioritize mechanisms that provide rapid fault detection over those that merely preserve state. Always match the symptom of frequent flaps with the solution of fast detection rather than applying general redundancy features.
Community Votes
67% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 3 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 3
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RKS_2021 👍 1 Answered Chttps://cloud.google.com/network-connectivity/docs/router/support/troubleshoot-bgp-sessions
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RKS_2021 👍 1 Answered Dquestion is about review the configuration, therefore D is correct.
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1f01b87 👍 1 Answered DD is the correct answer
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