slowing down every 60 seconds due to BGP scaner

Hi, I found all of my backbone routers slow down every 60 seconds , it will last 5 seconds . While this happens , the CPU may get more than 70% utilization and BGP scaner is the process that chewing the CPU (50%) . Customer with video stream noticed that . Cisco said it's normal .Any idea ? Thanks you ! Ben __________________________________________________ Terrorist Attacks on U.S. - How can you help? Donate cash, emergency relief information http://dailynews.yahoo.com/fc/US/Emergency_Information/