Covering prefix blackholing traffic to one of its covered prefixes....
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? Does this happen often? Thanks! Steven Wallace Indiana University
* ssw@iu.edu (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.
Sent from my iPhone
On Apr 23, 2017, at 08:59, Steven Wallace <ssw@iu.edu> 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
participants (3)
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Joel Jaeggli -
Niels Bakker -
Steven Wallace