← Problem Library
Network L7 NETWORK-052 · 26 min

BFD flaps continuously because control packets match the wrong firewall or QoS class

The routing session looks unstable for no obvious reason, but the real break is that BFD control traffic is handled differently from the data path and gets dropped or delayed.

NetworkPlatform ReliabilityLevel 7Pro26 min
Scenario

The routing session looks unstable for no obvious reason, but the real break is that BFD control traffic is handled differently from the data path and gets dropped or delayed.

What to check first
  • Identify the primary failure signal in the Fast-Failover Control Plane scenario.
  • Separate visible symptoms from the underlying technical dependency.
  • Describe the safest recovery path and the follow-up prevention work.
Checking checklist
  1. Summarize the current impact and the last known change.
  2. Collect direct evidence from logs, runtime state, and configuration before changing anything.
  3. Separate immediate recovery from permanent prevention work.
Recovery and prevention

Choose the smallest safe recovery action first, then record the prevention work that reduces repeat incidents.

Questions worth viewing together
What makes BFD incidents different from normal routing flaps?

BFD control packets can be filtered or delayed independently of the data path, so the session can flap for reasons ping tests miss.