Hello Chris,

 �

According to the documentation, https://bird.network.cz/?get_doc 
<https://bird.network.cz/?get_doc&v=20&f=bird-6.html#ss6.17> 
&v=20&f=bird-6.html#ss6.17

 �

A route requires at least one next hop. “route 192.168.0.0/16;” should not pass 
the configuration check.

 �

Valid routes can be:

route 192.168.0.0/16 blackhole; # drop packets to the destination

route 192.168.0.0/16 reject; # reject packets to the destination 

route 192.168.0.0/16 via eth0;

route 192.168.0.0/16 via 192.168.1.1; # 192.168.1.1 is directly reachable

route 192.168.0.0/16 recursive 192.168.1.1; # use next hop by resolving the 
route to 192.168.1.1

 �

When you announcing the prefix to your neighbor, the neighbor finds next hop 
with bgp_next_hop, it only knows that 192.168.0.0/16 is reachable via your 
router, and doesn’t know that prefix is blackholed on your router.

 �

Static routes are the reachability information defined statically on your 
router, which should be told to the kernel to be effective. If you are not 
exporting the routes to your kernel (this is actually what you did in the 
configuration you provided), the blackhole here will not affect your IP packet 
forwarding.

 �

Regards,

Soha

 �

From: Bird-users <bird-users-boun...@network.cz> On Behalf Of LIU Chris via 
Bird-users
Sent: Tuesday, June 4, 2024 11:24 PM
To: BIRD Users <bird-users@network.cz>
Subject: bird BGP not advertise local routing, unless make it blackhole

 �

Classified as: Hitachi Rail – Public

 �

I am new for bird/BGP. My configuration as below. Basically it is working as 
expected except one thing.

This static routing, I want to advertise this route to BGP peers.

If I just configured as : � route 192.168.0.0/16,  �Bird doesn’t advertise this 
route unless add it as blackhole

blackhole is sink or just drop, why ?

  

protocol static static_bgp {

       ipv4;   

        check link;   

        route 192.168.0.0/16 blackhole;   

}

 �

 �

------------------------------------------

router id 1.1.1.1;

  

filter Filter_Export_Kernel {

       if net ~ [ 10.1.0.0/16 ] then { 

                accept;

       }

       else

               reject;

}

  

protocol kernel {

       scan time 10;

       ipv4 {       

                export filter Filter_Export_Kernel;   

        };

}

  

protocol device {

       scan time 10;

}

  

protocol static static_bgp {

       ipv4;   

        check link;   

        route 192.168.0.0/16 blackhole;   

}

  

protocol bgp BGP_INSTANCE_1 {       

        local xx.xx.xx.xx as 10001;

       neighbor yy.yy.yy.yy as 10002;       

        ipv4 {

               import all;

               export where proto ="static_bgp";

               preference 200;

       };       

        hold time 3;       

        bfd on;

}

  

protocol bfd BFD_INSTANCE_1 {

       interface "eth1" {

               min rx interval 1 s;

               min tx interval 1 s;

               idle tx interval 3000 ms;

               multiplier 3;

       };

       neighbor yy.yy.yy.yy local xx.xx.xx.xx;

}

---------------------------------

 �

Hitachi Rail – Public

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