Next up - the Fire Wall. The corporate Fire Wall serves two purposes. It prevents some rather nasty things from the Internet from coming into the intranet. And it also can prevent sensitive corporate information from being sent out to the Internet. Once through the fire wall, a router picks up the packet and places it on to a much narrower road or band-width, as we say. Obviously, the road is not broad enough to take them all. Now you might wonder what happens to all those packets which don't make it along the way. Well, when Mr. IP doesn't receive an acknowledgment that a packet has been received in due time, he simply sends a replacement packet. The traffic on the Internet.