← Problem Library
Network L6 NETWORK-002 · 30 min

Port exhaustion in a high-request segment and kernel tuning

Covers how ephemeral ports, TIME_WAIT, and sysctl parameters connect to a service failure.

NetworkPlatform ReliabilityLevel 6Pro30 min
Scenario

As tasks sending many outbound requests in a short time increase, only some servers intermittently see upstream connection failures. The ss output shows TIME_WAIT piling up rapidly, and the ephemeral port range and reuse policy cannot handle the current request pattern.

What to check first
  • Identify the primary failure signal in the Performance Ops 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
Why is this a strong CCNP-style troubleshooting problem?

It forces you to connect socket exhaustion symptoms with kernel behavior and application connection reuse instead of stopping at generic timeout alerts.