I have an old 2501 router (IOS 11.3(11b)T5) which I want to use as an NTP server (it is not used for anything else). I configure two external NTP servers, no problem. CPU utilization is around 5-8%. I then configure "ntp broadcast" on interface e0, and within seconds, CPU utilization is 98%, and the NTP process shows 40%+. If I disable NTP completely, CPU utilization goes back down to a 5% right away. I tried this on another router, and got exactly the same result. This is the only site at which I have seen this. Any ideas on what could be going on on my network which would cause this behavior?