bgp route selection

[Thomas Goldberg]

Hello,

can yomeone please explain me the following behaviour:
There's one eBGP session (b_dtag1) and one iBGP session with one of
our RR Servers (b_rr1).
The RR redistributes the blackhole prefixes learned from the Spamhouse
BGP Feed (BGPf).

The prefix 64.112.128.0/18 is supposed to be blackholed.

These are the two routes learned from the two peers:
bird> show route all 64.112.128.0/18
64.112.128.0/18    via X.X.X.X on eth0 [b_dtag1 Apr06] * (100) [AS3320i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 3320 3491 25847 46879
        BGP.next_hop: X.X.X.X
        BGP.local_pref: 100
                   blackhole [b_rr1 15:36 from Y.Y.Y.Y] (100/-) [AS65535i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 65190
        BGP.next_hop: 192.168.2.11
        BGP.med: 0
        BGP.local_pref: 40000
        BGP.community: (65190,1000) (65535,65281)

As you can see the (older) regular eBGP route is picked over the
blackhole route:

Based on the Route selection rules from
http://bird.network.cz/?get_doc&f=bird-6.html#ss6.2 I expected that
the first (Prefer route with the highest Local Preference attribute)
and the second (Prefer route with the shortest AS path) rule would
result in the blackhole route being picked.

Best Regards
Thomas Goldberg