How to Troubleshoot High CPU Usage on Network Devices
Most network teams only find out their firewall is overloaded after users start complaining. A slow VPN, dropped calls, and random packet loss at 2 pm every day. The usual suspects get blamed first: the ISP, the switch, the application server. The firewall gets a pass because the dashboard says 40% CPU and everything looks fine. Here is the problem with that picture. Standard SNMP monitoring polls every 5 minutes. A CPU spike that peaks at 95% and recovers within 90 seconds never shows up.