As you know 3925 routers have 10/100/1000 Mbps interfaces builtin on it. Does it means it can give 1000 Mbps WAN speed if i have a 1Gbps connection terminated on it..??
There is a difference between "Interface Speed" and "Router Switching Speed/Capacity" Every router has its limitations, you can check the switching capacity of your router in the document mentioned above.
