Blackholing is typically used to fight massive DDoS attacks which congest the physical connection between SwissIX and a customer router. A detailed description of how Blackholing works at SwissIX is available here.
Besides signalling a blackhole via direct peering, you can signal blackholes via the route servers at SwissIX.
Blackholing via direct peering
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.
Blackholing via the Route Servers
If you want to blackhole a certain IP prefix by using the SwissIX 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 SwissIX:
| IXP | Blackhole next-hop IPv4 address | Blackhole next-hop IPv6 address | BGP BLACKHOLE Community |
| SwissIX | 91.206.53.66 | 2001:7f8:24::a5ec:b:dead | 65535:666 |
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 SwissIX Route Server Guide.