BLACKHOLE community RFC7999

[Job Snijders]

On Thu, Oct 20, 2016 at 05:35:43PM +0200, Clemens Schrimpe wrote:
> >> Just FYI: https://www.rfc-editor.org/rfc/rfc7999.txt
> >> I guess this feature deserves to be implemented.
> > 
> > Oh, sure. We plan to implement it.
> 
> It would be nice if export filters for the Kernel protocol could set a
> route type, as in iproute(8):
> 
> TYPE := [ unicast | local | broadcast | multicast | throw |
>           unreachable | prohibit | blackhole | nat ]
> 
> That would probably make more versatile than a static RFC7999 hack,
> while allowing to easily implement RFC7999 and others.

Be careful not to overshoot:

RFC 7999 says:

4.  Vendor Implementation Recommendations

   Without an explicit configuration directive set by the operator,
   network elements SHOULD NOT discard traffic destined towards IP
   prefixes that are tagged with the BLACKHOLE community.  The operator
   is expected to explicitly configure the network element to honor the
   BLACKHOLE community in a way that is compliant with the operator's
   routing policy.

   Vendors MAY provide a shorthand keyword in their configuration
   language to reference the well-known BLACKHOLE community attribute
   value.  The suggested string to be used is "blackhole".