I seem to have a problem with my RB751-U-2nHD where it will spike to 100% CPU usage and sit there for several minutes making it almost totally unresponsive, if watchdog is enabled it will then eventually reboot itself.
I do have an SSTP tunnel established, however I don't think it's encryption causing the CPU spikes as there shouldn't have been any significant traffic on that interface, infact Cacti shows 100Bits/s which is presumably is just background traffic to keep the link up, but may have missed some polls due my RB being unresponsive at the time.
The RB is connected to 2 ADSL2+ connections and is doing PPPoE for one of them but again there wasn't much throughput on either of them at the time as far as I can tell.
Is there a way to find out whats causing the sudden high load?