Poor network performance
 

Today I started experiencing some poor network performance.
The setup is a DHCP server (RedHat 9.0) connected on eth0 to a T1 line and using iptables to do the routing for the internal network eth1. Up untill this afternoon I was seeing a network performance on average of around 731kb/sec
The average for the past hour has been below 75kb/sec sometimes even dropping below 10kb/sec.

The cpu on the Linux box is now consitantly pegged above 90% system CPU with ksoftirqd_CPU using the majority of the CPU...

My network guy is out of town for 2 weeks....any ideas of where to start looking to get my performance back?