Would someone please tell me just why icmp echos are "cpu intensive"? Yes, I know they're in software. So what? A PC can respond to an ethernet loaded with them with a trivial percentage of it's CPU cycles. Recall that the high end routers do most of their forwarding in hardware. So echos are "cpu intensive" in that they take many, many, many more CPU cycles to process than packets which are forwarded by the hardware. For example, in a cisco 7000, the main traffic flow is switched by the silicon switch engine. Pings of the router themselves cause the packet to leave the silicon switch engine and sit on a queue (consuming buffer space), waiting for the CPU. When the CPU gets around to it, the packet is then copied out of the hardware up to the CPU. The CPU then makes a normal forwarding decision, and decides to receive the packet. It then decides to format the reply. Now it makes another forwarding decision, copies the packet back down into a hardware buffer and squirts it out. This sounds to me a whole lot more like a solution to an imagined problem, but I'm prepared to be convinced that responding to pings actually takes a great enough percentage of CPU cycles to slow down packet delivery..... In fact, responding to pings does not directly affect the speed of the hardware forwarding engine. However, it does increase buffer utilization in the hardware. It also deters routing protocol processing from happening, as it's consuming CPU. Tony