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Re: IPv6 "is unreachable" route flapping

On 09/03/2020 23:03, Paul Ripke wrote:
On Mon, Mar 09, 2020 at 10:42:42AM +0000, Roy Marples wrote:
On 09/03/2020 10:28, Paul Ripke wrote:
Time has passed, and I'm now running netbsd-9 on the orange pi, and
on the amd64 router. I still see these issues with IPv6 route flaps.

  From the arm side:

Mar  9 20:52:20 thing1 dhcpcd[292]: emac0: Router Advertisement from fe80::52e5:49ff:fea6:f5d8
Mar  9 20:52:20 thing1 dhcpcd[292]: emac0: fe80::52e5:49ff:fea6:f5d8: no longer a default router

Well, that's pretty telling.
dhcpcd received a RA with a router lifetime of zero.
It's not that the route is flapping, it's the router saying it's no longer a
default router and should not be used.
dhcpcd is just doing what it's told.

The rest of the debug is irrelevant at this point.

Is there anything on your router restarting rtadvd as that would trigger the above?

Nothing restarting it, afaik. I do have a /etc/ppp/dhcp6c-script:


IP=$(ifconfig pppoe0 | awk '/inet6/ {print $2}' | cut -d / -f 1)
route change -inet6 default "$IP" || route add -inet6 default "$IP"
sleep 2 && /etc/rc.d/rtadvd reload

And /etc/rtadvd.conf:


I've commented out the SIGHUP, I forget why I added that - lost to the
mists of time. Alternately, I see rtadvd has a -C option, but that sounds
wrong. I'll see what happens with it commented out.

You shouldn't need it that reload.
rtadvd should spot the new/changed prefix via route(4) and do the right thing.

The -C option is noted as only used for testing clients as I use it from time to time to test dhcpcd. Not using it is the right thing to do :)


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