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<div class="moz-cite-prefix">Maybe you forgot to disable rp_filter
on uplink ifaces?<br>
<br>
And prepend works for incoming traffic, for outgoing - there is
localpref. So, if outgoing traffic goes via ISP2 and incoming
passed via ISP1 - it's dropped if rp_filter is enabled.<br>
<br>
On 25.04.2017 10:36, Wojciech Bajorek wrote:<br>
</div>
<blockquote
cite="mid:CAA+tadJk__rEA1veb8n5QF7HOwM-c6iKkXMyp4yFdVCO5hqaKA@mail.gmail.com"
type="cite">
<div dir="ltr">Hi,
<div><br>
</div>
<div>I have a pretty simple BGP configuration with two ISP and
one static subnet to advertise.</div>
<div>There is also one prepending configured but I'm not sure if
it's working.</div>
<div><br>
</div>
<div>The thing is that for some reason when I connect both ISP
peers, traffic to the advertised ISP#2 networks (with shorter
path) stops working after a couple of seconds. Tracert shows
the last hop as ISP#2 border router.</div>
<div><br>
</div>
<div>Similar configuration on Juniper router works without any
problem, so I'm afraid that there is an error within my Bird
config. </div>
<div>Can you please help me out?</div>
<div><br>
</div>
<div>PS. Without prepending situation is exactly the same.</div>
<div><br>
</div>
<div>OS: Debian 8</div>
<div>Bird: 1.4.5-1+deb8u1</div>
<div><br>
</div>
<div>
<div> </div>
<div>router id 90.90.90.1;</div>
<div><br>
</div>
<div>protocol kernel {</div>
<div> persist;</div>
<div> scan time 15;</div>
<div> import all;</div>
<div> export all;</div>
<div>}</div>
<div><br>
</div>
<div>protocol device {</div>
<div> scan time 10;</div>
<div>}</div>
<div><br>
</div>
<div>filter bgp_isp1_out {</div>
<div> if net = <a moz-do-not-send="true"
href="http://90.90.90.0/24">90.90.90.0/24</a> then</div>
<div> {</div>
<div> accept;</div>
<div> }</div>
<div> else reject;</div>
<div>}</div>
<div><br>
</div>
<div>filter bgp_isp2_out {</div>
<div> if net = <a moz-do-not-send="true"
href="http://90.90.90.0/24">90.90.90.0/24</a> then</div>
<div> {</div>
<div> bgp_path.prepend(12345);</div>
<div> bgp_path.prepend(12345);</div>
<div> accept;</div>
<div> }</div>
<div> else reject;</div>
<div>}</div>
<div><br>
</div>
<div>protocol bgp bgp_isp1 {</div>
<div> import all;</div>
<div> export filter bgp_isp1_out;</div>
<div><br>
</div>
<div> local as 12345;</div>
<div> neighbor 2.3.4.5 as 2345;</div>
<div>}</div>
<div><br>
</div>
<div>protocol bgp bgp_isp2 {</div>
<div> import all;</div>
<div> export filter bgp_isp2_out;</div>
<div><br>
</div>
<div> local as 12345;</div>
<div> neighbor 3.4.5.6 as 3456;</div>
<div>}</div>
<div><br>
</div>
</div>
<div><br>
</div>
<div>Thank you.</div>
<div><br>
</div>
<div>Regards,</div>
<div>Wojciech Bajorek</div>
</div>
</blockquote>
<p><br>
</p>
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