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Network L7 NETWORK-019 · 30 min

After a BGP route change, only certain ASNs take a detour path

A network operations problem where the global route is alive but only certain carrier networks get an inefficient detour.

NetworkIncident LeadershipLevel 7Team30 min
Scenario

A scenario that narrows down the root cause, centered on interpreting how a routing-policy change looks to external networks, in the situation of only certain ASNs taking a detour path after a BGP route change.

What to check first
  • Identify the primary failure signal in the Routing Control 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 is the key mistake in BGP path-change incidents?

Operators often validate only one ASN view instead of comparing import, export, and policy effects across every affected path.