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</head><body bgcolor="#FFFFFF" text="#000000"><span>Could it be as
simple as a stateful firewall?<br>
<br>
Anurag Bhatia wrote on 6/12/2019 14:44:</span><br>
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<div dir="ltr">Hello everyone, <div><br></div><div>Trying to get my
head around a certain unexpected behaviour. </div><div><br></div><div><br></div><div>I
am running two site to site VPNs (wireguard now, OpenVPN earlier)
between my home and a remote server over two different WAN links. Both
WAN links are just consumer connections - one with public IP and one
with CGNATed IP. </div><div>The redundancy here is taken care of by the
OSPF running via FRR on both ends. </div><div><br></div><div><br></div><div>The
unexpected behaviour I get is that if I set OSPF cost to prefer say
link1 between home -> server and prefer link 2 between server ->
home then connectivity completely breaks between the routed pools. The
point to point IPs stay reachable (which is over expected links i.e
symmetric via both ends). As long as both ends prefer link1 or link2, it
works fine. At first, I thought it had to do something with NAT but
still can't understand how. Since VPN tunnels have a keep-alive timer
(for 10 seconds), the tunnel is always up. Any idea why asymmetric
packets are being dropped here? </div><div>This exact behaviour was in
case of earlier OpenVPN + bird + iBGP and is still the same when I moved
everything to Wireguard for VPN + FRR for routing + OSPF. </div><div><br></div><div><br></div><div><br></div><div><br></div><div>Thanks. </div><div><br
clear="all"><div><br></div>-- <br><div dir="ltr"
class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div
dir="ltr"><div dir="ltr"><div><font face="arial, helvetica, sans-serif"><br></font></div><div><br></div><font
face="arial, helvetica, sans-serif">Anurag Bhatia<br></font><div><font
face="arial, helvetica, sans-serif"><a href="http://anuragbhatia.com"
target="_blank" moz-do-not-send="true">anuragbhatia.com</a></font></div></div></div></div></div></div></div></div>
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