Another strategy is blackhole filtering. Network operators apply filtering rules at the network border routers to discard malicious traffic. This technique provides an additional layer of protection against DDoS attacks. To make the blackholing process more flexible and precise, ISPs and network operators often leverage BGP communities.
ISPs and network operators often use BGP communities, which allow them to tag and distribute routes to specific peers or customers. This grants more precise policy control and even allows customers to activate blackholing for unwanted traffic on their own.
More info: What is a vulnerability assessment
