1Gbps copper link (trunk) connecting an ISR router and a L3 switch. ISR side using dot1q subinterface and provides routing.
ISR's interface input counter has some overruns and tons of ignored (and no other errors). Flow control enabled on both sides and it looks like pause frames are being sent and received. cpu histogram showing high cpu usage roughly when the interface error counter incremented. No relevant console logs.
No interface error on switch side.
CEF enabled on both devices.
How can I confirm the issue is ISR route's routing performance bottleneck? I can probably try interface history, is bps or pps more useful in this case? How do you make a case that upgrading is necessary?
