Using upnp-router-control, I can see a large inbound traffic spike (nearly 2 times normal flow) every 11 seconds (100kB/s will spike to 180, 200 to 350, etc)
Outbound traffic spikes are smaller but happen about the same frequency.
Neither peak is enough to hit througput limits or ISP throttle values.
This only happens when amule(d) is running (tested on multiple machines), so I'm sure it's not caused by anything else.
Does anyone have any idea what these spikes are?