I am using a vSwitch from Hetzner with an IPv6 network, I have configured CARP and works as expected, but the problem that I have noticed is that either because my IPv6 configuration or the vSwitch, is taking over a minute or more to start sending packages to the newly available (MASTER) server.

For testing without CARP, in one of the servers, I create an alias, something like:

ifconfig vlan0 inet6 2a01:4f8:fff0:60:dead:beef::1/64 alias

From another host in a terminal I start a ping6 2a01:4f8:fff0:60:dead:beef::1, after checking that the address is reachable by receiving some echo replies, I then I remove the alias:

ifconfig vlan0 inet6 2a01:4f8:fff0:60:dead:beef::1/64 -alias

Ping stops as expected, and then I add the same alias in another server:

ifconfig vlan0 inet6 2a01:4f8:fff0:60:dead:beef::1/64 alias

Approximately after a minute or more, the terminal running the ping the IP address starts to reply.

Therefore wondering how could I speed up the time for assigning the IP address, I think in IPv6 this is related to "neighbor discovery" but since I am using static address maybe is not the case.

Just in case I tested with IPv4 and the response was almost immediately after adding the IP alias or removing it the same I would like to achieve with IPv6 so that I could take advantage of CARP.

  • 1
    If the update answers your question, you should post that as an answer and add a new question based on your last paragraph. – Rob Apr 4 at 12:02

It turns out that it is because of how IPv6 works, This article helped me to better understand: https://www.stoklasa.one/carp-with-ipv6-protocol/

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