I know this is very general, but I have a router that is getting as much as 15% packet loss with large packets (up to 1500 bytes). The MTU on both router interfaces is 1500. The router fastethernet interface is directly connected to a 2500 ethernet interface. Going into the local network no loss. Going to the 2500 losses up to 15% with large packets. No loss on smaller packets. I have an idea what the problem is, but was wondering what others thought.