Ruhr-CIX Blackholing guide

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

Besides signaling a blackhole via direct peering, you can signal blackholes via the route servers at Ruhr-CIX.

Blackholing via direct peering

You have to set the appropriate BGP next-hop (your router IP) manually when signaling 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.

Blackholing via the Route Servers

If you want to blackhole a certain IP prefix by using the Ruhr-CIX 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 Ruhr-CIX and interconnected IXPs:
IXPBlackhole Next-Hop IP address IPv4Blackhole Next-Hop IP address IPv6BGP BLACKHOLE Community
DE-CIX Dusseldorf185.1.170.662001:7f8:9e::de3a:42:1

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 Ruhr-CIX route server guide.