Covering prefix blackholing traffic to one of its covered prefixes....

Niels Bakker niels=nanog at
Mon Apr 24 15:10:23 UTC 2017

* ssw at (Steven Wallace) [Mon 24 Apr 2017, 16:51 CEST]:
>We have dual-homed sites that only accept routes from their peers, 
>and default to their transit provider. A site may receive a covering 
>prefix from a peer, but since they are not accepting the full table 
>from their transit provider they don’t see the covered (i.e., more 
>specific). In some cases the peer announcing the covering prefix 
>blackholes traffic to the covered prefix.
>Is this accepted behavior, or should a peer announcing a covering 
>prefix always delver packets to its covered routes?

A prefix announcement means a statement of capability and willingness 
to deliver packets to covered destinations.  Any deviation is a hijack.

>Does this happen often?

This is more common than it should be.

	-- Niels.

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