Such attacks are possible because Internet is decentralized. There is no way to tell peers that you don't want to get traffic from some AS. And investigation i

Such attacks are possible because Internet is decentralized. There is no way to tell peers that you don't want to get traffic from some AS. And investigation is difficult because attacking nodes might be in different countries, in some of which DDOS attacks are not illegal. Maybe it is time to start building international firewalls to protect local infrastructure?