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

Joel Jaeggli joelja at
Mon Apr 24 15:19:44 UTC 2017

Sent from my iPhone

> On Apr 23, 2017, at 08:59, Steven Wallace <ssw at> wrote:
> 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.

If you announce a route in general you should expect to route it.

Assuming this is the intended behavior of both parties announcing the covering aggregate and the more specific. The site should either drop the offending peer route forcing it to transit, or take full feed from it's transit. And let the longest match win.

> Is this accepted behavior, or should a peer announcing a covering prefix always delver packets to its covered routes?

Generally but there are exceptions.

> Does this happen often?
> Thanks!
> Steven Wallace
> Indiana University

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