On Mon, 14 February 2000, Randy Bush wrote:

ettore bugatti, maker of the finest cars of his day, was once asked why his cars had less than perfect brakes. he replied something like, "any fool can make a car stop. it takes a genius to make a car go."

The scary thing is this was really only a moderate attack. Network engineers created worse Internet disruptions by accident in the past. The difference is intent, not result. The good news is you can use the same techniques to protect against many different causes of service disruptions. Does it matter whether you get hammered by the slashdot effect, or a denial of service attack; a F5 tornado or a ryder truck; a backhoe or a gopher; or the scariest of them all, a Bell technician? I know some people joked when I suggested QoS might be a way to look at DoS, because attackers wouldn't set the low priority bit on their packets. But one way to protect against the slashdot effect or a DoS would be for a host to advertise how much available bandwidth they have, and when it is exceeded start "call gapping" (if I might borrow that term) at the edges. If Yahoo! couldn't handle 1Gigabit(byte) of traffic, their enginers could set their QoS/RSVP/RED with their providers to how much traffic they can handled. This might allow excess traffic to get dropped sooner on a more distributed basis, hopefully preventing single routers or hosts from getting overwhelmed and falling over. Since I've haven't thought QoS was good for anything in the past, maybe this could be the problem the QoS people have been looking to solve.

From what I've heard, the way most providers combatted the current attacks was installing filters and rate-limits on identifiable traffic. The protection depends on the attacker using packets which aren't necessary for the normal functioning of the site.