Ok... so this is a weird issue... we have about 43 routers reporting to our netflow server.  When we take the server offline for a time frame of about 10 minutes we start to experience a MAJOR Network storm.  Looking at PRTG and (setting up a secondary netflow) it appears that when the server goes offline ALL the devices immediatley start KILLING the network like utilization goes up 500% and its all focused on traffic trying to go to the netflow device.

 

 

Has anyone seen this?   

 

This is our typical Netflow Enable commands on the routers

 

 

ip flow-cache timeout active 5
ip flow-export source GigabitEthernet1/0
ip flow-export version 5
ip flow-export destination x.x.x.x 9996