ACIX Blackholing Guide

Blackholing is typically used to fight massive DDoS attacks which congest the physical connection between ACIX and a customer router. A detailed description of how Blackholing works at ACIX is available here.

Besides signalling a blackhole via direct peering, you can signal blackholes via the route servers at ACIX.

You have to set the appropriate BGP next-hop (your router IP) manually when signalling a blackhole on a direct peering session.

Please also ask you peers to accept up to /32 for IPv4 and up to /128 for IPv6 from you, for allowing the service to work correctly.

If you want to blackhole a certain IP prefix by using the ACIX route servers, there are two ways of achieving this:

• The BGP announcement carrying the IP prefix that should be blackholed is marked with the BLACKHOLE BGP Community (65535:666). This is the recommended way as it makes the handling a lot easier.
  or
• The BGP announcement carrying the IP prefix that should be blackholed contains a pre-defined blackhole IP address as a BGP next-hop. The table below lists the IPv4 and IPv6 blackhole IP addresses for ACIX:

Please do not set the NO-EXPORT or NO-ADVERTISE Community on the BGP announcements marked as blackhole as this tells the route servers to not re-distribute this announcement. The route servers will add NO-EXPORT automatically.

Configuration examples of how to setup a BGP session to the route server can be found in the ACIX Route Server Guide.