I have a GRE over IPSec tunnel that gets high bandwidth utilization every 2-3 days and stays like that for 2-3 days. I look at the traffic using netflow on the 2811 router and 95% of the packets in and out are either GRE or IPSec. I only have two tunnels on this router (tunnel mode). My question is are GRE and IPSec causing the spike in bandwidth and if so what can I do to fix it?
I have this problem too.