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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: NAP/ISP Saturation WAS: Re: Exchanges that matter...
On Tue, 17 Dec 1996, Chris Caputo wrote: > There is considerable difference between forwarding a packet that happens > to contain ICMP data (destination not the router) and responding to a > packet that contains ICMP data (destination is the router). In the > former, priority in a Cisco is the same for ICMP as it is for UDP or TCP, > since this part of the packet is not even being examined. In the later, > priority is lower and can be ignored altogether. > > I treat ignored (link good, but no response received) ICMP echo requests > as an indicator that a router is too loaded. If the router has been > pushed to the point of not being able to respond to an ICMP, how well is > it going to do when a bunch BGP updates occur? (rhetorical) Both are CPU > intensive operations. 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. 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..... Thanks, David ---------------------------------------------------------------------------- It's *amazing* what one can accomplish when one doesn't know what one can't do! - - - - - - - - - - - - - - - - -
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