After having two Ciscos explode and no new ones available until
monday, I'm attempting to make a Soekris net4501 take over as a
router.  However, when packet rates start getting high (up to 1kpps, I
suspect), the system will start pausing more and more frequently for
up to several minutes. At this time all network and (serial) console
activity freezes totally. According to top, it seems that the ioflush
process is running (very high system activity percentage). Interrupt
load gets up to around 20% when the pausing starts.

Most of the traffic is coming in from gif tunnels and going out
on vlan interfaces. No messages are printed on the console,
nor in syslogs, at any time. The kernel is 1.6.1_STABLE from
last week.

Any assistance would be much appreciated.

 -v