<div dir="ltr">Hello K.<div><br></div><div>Thanks for checking in this issue.</div><div>But, I can't understand.</div><div>If it was because of the iptables, it would have been a problem for BGP as well.<br></div><div>And I'm not using iptables rules, So Any packets weren't dropped.</div><div><br></div><div>* iptables status</div><div>============================================================</div><div># iptables -L<br>Chain INPUT (policy ACCEPT)<br>target   prot opt source        destination<br><br>Chain FORWARD (policy ACCEPT)<br>target   prot opt source        destination<br><br>Chain OUTPUT (policy ACCEPT)<br>target   prot opt source        destination<br>============================================================<br></div><div><br></div><div>* Port status<br>============================================================ </div><div># netstat -lnp | grep bird<br>tcp     0    0 <a href="http://0.0.0.0:179">0.0.0.0:179</a>       0.0.0.0:*        LISTEN    44890/bird<br>udp     0    0 <a href="http://0.0.0.0:3784">0.0.0.0:3784</a>       0.0.0.0:*              44890/bird<br>udp     0    0 <a href="http://0.0.0.0:4784">0.0.0.0:4784</a>       0.0.0.0:*              44890/bird<br>unix  2    [ ACC ]   STREAM   LISTENING   320049  44890/bird      /run/bird/bird.ctl<br>unix  2    [ ACC ]   STREAM   LISTENING   398938  44893/bird6      /run/bird/bird6.ctl<br></div><div>
============================================================
 <br></div><div><br></div><div>* BIRD Status<br>============================================================ </div><div># birdc show bfd sessions<br>BIRD 1.6.8 ready.<br>bfd1:<br>IP address         Interface  State    Since    Interval  Timeout<br>10.11.251.4        ---     Init    09:37:57    2.000   6.000<br>10.11.250.4        ---     Init    09:37:56    2.000   6.000<br></div><div><br></div><div># birdc show protocols<br>BIRD 1.6.8 ready.<br>name   proto   table   state  since    info<br>kernel1  Kernel  master  up   09:37:52<br>direct1  Direct  master  up   09:37:52<br>device1  Device  master  up   09:37:52<br>static1  Static  master  up   09:37:52<br>bfd1   BFD    master  up   09:37:52<br>as1    BGP    master  up   09:37:56   Established<br>as2    BGP    master  up   09:37:57   Established<br></div><div>
============================================================
 <br></div><div><br></div><div>Is it related to the increase in this value?<br></div><div><div>============================================================<br></div><div># netstat -s</div><div>...</div><div>Udp:<br>  52759 packets received<br>  0 packets to unknown port received<br>  0 packet receive errors<br>  34365164 packets sent<br>  0 receive buffer errors<br>  0 send buffer errors<br>  IgnoredMulti: 3399<br>...</div><div><div>============================================================<br></div><div><br></div><div>Please check it.</div><div><br></div><div>Regards.</div><div></div></div><div></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">2020ë…„ 7ě›” 16일 (목) ě¤í›„ 8:05, Kees Meijs | Nefos <<a href="mailto:kees@nefos.nl">kees@nefos.nl</a>>ë‹ěť´ 작성:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
Hi Seunghwan,<br>
<br>
It might be your problem isn't BIRD but packet filter related.<br>
<br>
Please check the BFD packets are allowed in iptables c.q. netfilter
using the correct ports and/or addresses.<br>
<br>
A possible reason why it starts working after a manual protocol
restart is a ESTABLISHED, RELATED rule.<br>
<br>
References:<br>
<ul>
<li><a href="https://tools.ietf.org/html/rfc5881" target="_blank">https://tools.ietf.org/html/rfc5881</a> (Encapsulation, IANA
Considerations)<br>
</li>
<li><a href="https://tools.ietf.org/html/rfc5883" target="_blank">https://tools.ietf.org/html/rfc5883</a> (IANA Considerations)<br>
</li>
</ul>
<br>
K.<br>
<br>
<div>On 16-07-2020 11:00, seunghwan hwang
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Hello.
<div>BFD is Not working normally.</div>
<div>My configuration is shown below.</div>
<div><br>
</div>
<div>OS: Ubuntu 18.04</div>
<div>Kernel:Â 4.15.0-54-generic</div>
<div>BIRD ver: 1.6.8</div>
<div>==================================</div>
<div>protocol bfd {<br>
    multihop {<br>
      min rx interval 300 ms;<br>
      min tx interval 300 ms;<br>
      multiplier 3;<br>
    };<br>
}<br>
</div>
<div><br>
</div>
<div>protocol bgp as1 {<br>
    import all;<br>
    export all;<br>
<br>
    local ~ as ~;<br>
    neighbor ~ as ~;  <br>
    enable route refresh off;<br>
    hold time 90;<br>
    bfd on;<br>
}<br>
<br>
protocol bgp as2 {<br>
    import all;<br>
    export all;
<br>
<br>
    local ~ as ~;<br>
    neighbor ~ as ~;  <br>
    enable route refresh off;<br>
    hold time 90;<br>
    bfd on;  <br>
}<br>
</div>
<div>==================================Â Â <br>
</div>
<div><br>
</div>
<div>After system reboot(# shutdown -r now), BGP neighbor is
established, But BFD sessions are stuck in 'INIT' status. And
BIRD does not send BFD packets.<br>
</div>
<div>BFD sessions have recovered after restart protocol bfd1(#
birdc restart bfd1).</div>
<div><br>
</div>
<div>Is it a normal situation?</div>
<div>I think BFD has to start the mechanism after BGP neighbor
is UP.</div>
<div>Is there any missing part of my configurations?<br>
</div>
<div>Please check it.</div>
<div><br>
</div>
<div>Regards</div>
</div>
</blockquote>
<br>
</div>
</blockquote></div>