[SR-Users] Keeping Registrations alive in IPv6 scenarios

[Sebastian Damm]

Hi,

while testing IPv6 with customers, we fell over quite a few cases, where
customers aren't reachable on inbound calls most of the time. And digging
into this, we found the home router firewall as the cause for those
problems.

Normally, you would think, all the NAT problems cease when switching to
IPv6. But actually, right now I don't know how to fix that problem.

In IPv4 NAT scenarios, we would flag the customer during the registration,
and Kamailio would send NAT pings (those 4 bytes of UDP junk) every few
seconds to keep the firewall in the NAT router open. And that worked pretty
great.

Now we have IPv6. We don't have NAT. But we still have a home router in
front of SIP devices, with a firewall. And this firewall will allow
outbound traffic. But after a few seconds it won't allow incoming
connections anymore. And the routers I have seen so far don't have a
configurable firewall where you could allow inbound traffic from our server.

Unfortunately, only our load balancer is IPv6, our registrar is still IPv4
only. And the loadbalancer doesn't know anything about registrations and
which customer needs an IPv6 keepalive.

Does anyone have a hint, how to keep the IPv6 registrations alive? Thanks
in advance.

Best Regards,
Sebastian
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