export filter matches, but not announced

micah anderson micah at riseup.net
Thu Jul 23 20:03:02 CEST 2020


Hi,

I have a peer configured with an export filter called 'bgp_nullroute',
and if I do 'birdc show route filter bgp_nullroute' i see a netblock
there.

I thought that would mean that this netblock would be exported/announced
to the peer, but its not being exported, but there is something that I
do not understand, I would appreciate a nudge in the right direction!

protocol bgp nullroute {
  description "nullroute server";
  local as ASN;
  source address 199.254.238.1;
  neighbor 192.168.1.1 as 64512;
  multihop 255;
  import filter bgp_in_nullroute;
  export filter bgp_nullroute;
}

protocol static static_nullroute {
         import filter static_nullroutes;
         include "static_nullroutes.conf";
}

file static_nullroutes.conf has:
route 204.13.164.220/32 blackhole;

define ASN = 16652;


filter bgp_nullroute {
   if (ASN,666) ~ bgp_community && net.len = 32 && our_network() then {
   accept;
   }
   else reject;
}


bird> show route all filter bgp_nullroute
204.13.164.220/32  blackhole [static_nullroute 09:11:08] (200)
	Type: static unicast univ
	BGP.community: (16652,666)

bird> show protocols all nullroute
name     proto    table    state  since       info
nullroute BGP      master   up     2020-07-23 10:01:28  Established   
  Description:    nullroute server
  Preference:     100
  Input filter:   bgp_in_nullroute
  Output filter:  bgp_nullroute
  Routes:         0 imported, 0 exported, 0 preferred
  Route change stats:     received   rejected   filtered    ignored   accepted
    Import updates:              0          0          0          0          0
    Import withdraws:            0          0        ---          0          0
    Export updates:         802145        134     802011        ---          0
    Export withdraws:           71        ---        ---        ---          0
  BGP state:          Established
    Neighbor address: 192.168.1.1
    Neighbor AS:      64512
    Neighbor ID:      192.168.1.220
    Neighbor caps:    refresh AS4
    Session:          external multihop AS4
    Source address:   199.254.238.1
    Hold timer:       159/180
    Keepalive timer:  3/60

-- 
        micah


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