What is BGP Flowspec?

By | March 18, 2023

BGP Flowspec is an extension to BGP that enables the distribution of filtering rules across BGP-enabled routers. These rules specify the type of traffic that should be allowed or denied based on specific criteria such as source or destination IP addresses, protocols, port numbers, and traffic rate. BGP Flowspec can be used to mitigate DDoS attacks by identifying and blocking traffic that matches the attack characteristics in real-time.

BGP Flowspec Use Cases

BGP Flowspec is useful in mitigating DDoS attacks, but it also has other use cases. Here are some of them:

  1. Filtering unwanted traffic: BGP Flowspec can be used to filter out unwanted traffic such as spam, malware, and other types of traffic that don’t conform to network policies.
  2. Traffic shaping: BGP Flowspec can be used to shape traffic by enforcing traffic policies that prioritize certain types of traffic over others.
  3. Controlling traffic flow: BGP Flowspec can be used to control traffic flow by directing traffic to specific paths, optimizing network performance, and reducing congestion.

BGP Flowspec Configuration

To configure BGP Flowspec, you need to create filtering rules and distribute them across BGP-enabled routers. The filtering rules can be created using the following criteria:

  1. Source IP address
  2. Destination IP address
  3. Protocol (TCP, UDP, ICMP)
  4. Source port number
  5. Destination port number
  6. Traffic rate
  7. IP Fragmentation
  8. TCP Flags

Once the filtering rules have been created, they can be distributed across BGP-enabled routers using BGP Flowspec. This involves configuring the BGP Flowspec feature on the router, defining the Flowspec rules, and distributing them across the network.

Deployment Considerations

Here are some considerations to keep in mind when deploying BGP Flowspec:

  1. Network topology: BGP Flowspec is best suited for large networks with multiple routers. For small networks, traditional access control lists (ACLs) may be sufficient.
  2. Resource requirements: BGP Flowspec requires significant computational resources, including CPU and memory. Ensure that your network devices can handle the additional load.
  3. Filter rule management: Managing filter rules can be challenging, especially in large networks with many filtering rules. Consider using automation tools to help manage the rules.
  4. Security: Ensure that the filter rules are properly configured to prevent false positives and false negatives. A false positive occurs when legitimate traffic is blocked, while a false negative occurs when malicious traffic is allowed.


BGP Flowspec is an extension to BGP that provides fine-grained control over network traffic by allowing the creation and distribution of filtering rules to mitigate DDoS attacks. BGP Flowspec is useful in filtering unwanted traffic, traffic shaping, and controlling traffic flow. When deploying BGP Flowspec, ensure that your network topology can support it, your network devices have sufficient resources, and that the filter rules are properly configured to prevent false positives and false negatives.

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